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Sample records for glass holey fibres

  1. Recent advances in the development of holey optical fibers based on sulphide glasses

    NASA Astrophysics Data System (ADS)

    Smektala, F.; Brilland, L.; Chartier, T.; Nguyen, T. N.; Troles, J.; Niu, Y. F.; Danto, S.; Traynor, N.; Jouan, T.

    2006-02-01

    Microstructured optical fibers as new optical objects have been developed in the recent past years, firstly from silica glass and then from other oxide glasses such as tellurite or different heavy cations oxide glasses. However very few results have been reported concerning non-oxide glasses and more particularly chalcogenide glasses. In a photonic crystal fiber the arrangement of air holes along the transverse section of the fiber around a solid glassy core leads to unique optical properties, such as for example broadband single-mode guidance, adjustable dispersion, nonlinear properties. Since the effective modal area is adjustable thanks to geometrical parameters, chalcogenide microstructured fibers with small mode area are of interest for nonlinear components because of the intrinsic non linearity of chalcogenide glasses, several order of magnitude above these of the reference silica glass (100 to 1000 times the non linearity of silica glass). On the other hand, chalcogenide holey fibers with large mode area are of interest for infrared power transmission, in a wavelength range out of reach of silica fibers, and more particularly in the 3-5 μm atmospheric window. The aim of this paper is to present more specifically the recent results that have been achieved in the elaboration, light guidance and characterization of photonic crystal fibers from the sulfide Ge 20Ga 5Sb 10S 65 glass, which presents a large transparency window from 600 nm to 11 μm.

  2. 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.

  3. 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.

  4. Single-Mode Soft Glass Fibres

    NASA Astrophysics Data System (ADS)

    Jedrzejewski, Kazimierz

    1990-01-01

    The technology of single-mode optical soft glass fibres is developed. The well-known rod in tube technique with multiple sleeving was taken to achieve proper dimensions. The ultrasonic mill-drill was used to prepare different structures: high ▵ , high birefringent, D-shaped, multicore, metal wire/glass compound and doped. The temperature processes were carried out very carefully to avoid glass decomposition. The geometry, refractive index profiles, mode near field patterns and λc agreed with the predicted and material data. The losses were reasonably low, better then 370 dB/km (800 nm). The enhanced Verdet constants and nonlinear coefficients values, high dopants levels and other special properties including low process temperatures are very attractive for fibre short range applications, sensors and devices e.g. polarizers, couplers, lasers, filters.

  5. Modified glass fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Cao, Yumei

    A high ratio of strength to density and relatively low-cost are some of the significant features of glass fibre reinforced polymer composites (GFRPCs) that made them one of the most rapidly developed materials in recent years. They are widely used as the material of construction in the areas of aerospace, marine and everyday life, such as airplane, helicopter, boat, canoe, fishing rod, racket, etc. Traditionally, researchers tried to raise the mechanical properties and keep a high strength/weight ratio using all or some of the following methods: increasing the volume fraction of the fibre; using different polymeric matrix material; or changing the curing conditions. In recent years, some new techniques and processing methods were developed to further improve the mechanical properties of glass fibre (GF) reinforced polymer composite. For example, by modifying the surface condition of the GF, both the interface strength between the GF and the polymer matrix and the shear strength of the final composite can be significantly increased. Also, by prestressing the fibre during the curing process of the composite, the tensile, flexural and the impact properties of the composite can be greatly improved. In this research project, a new method of preparing GFRPCs, which combined several traditional and modern techniques together, was developed. This new method includes modification of the surface of the GF with silica particles, application of different levels of prestressing on the GF during the curing process, and the change of the fibre volume fraction and curing conditions in different sets of experiments. The results of the new processing were tested by the three-point bend test, the short beam shear test and the impact test to determine the new set of properties so formed in the composite material. Scanning electronic microscopy (SEM) was used to study the fracture surface of the new materials after the mechanical tests were performed. By taking advantages of the

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

    SciTech Connect

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

    2012-09-30

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

  7. IR luminescence in bismuth-doped germanate glasses and fibres

    SciTech Connect

    Pynenkov, A A; Firstov, Sergei V; Panov, A A; Firstova, E G; Nishchev, K N; Bufetov, Igor' A; Dianov, Evgenii M

    2013-02-28

    We have studied the optical properties of lightly bismuth doped ({<=}0.002 mol %) germanate glasses prepared in an alumina crucible. The glasses are shown to contain bismuth-related active centres that have been identified previously only in bismuth-doped fibres produced by MCVD. With increasing bismuth concentration in the glasses, their luminescence spectra change markedly, which is attributable to interaction between individual bismuth centres. (optical fibres)

  8. 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.

  9. 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.

  10. 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

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

    SciTech Connect

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

    2006-01-31

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

  12. Glass fibres: absence of pulmonary hazard in production workers

    PubMed Central

    Hill, J. W.; Whitehead, W. S.; Cameron, J. D.; Hedgecock, G. A.

    1973-01-01

    Hill, J. W., Whitehead, W. S., Cameron, J. D., and Hedgecock, G. A. (1973).British Journal of Industrial Medicine,30, 174-179. Glass fibres: absence of pulmonary hazard in production workers. Seventy fibreglass workers with a mean of 19·85 years in the industry are compared with a control group having no exposure to glass fibre but otherwise matched for age, sex, height, and weight, and residing in the same geographical area. Comparison was made by radiography, the administration of the modified Medical Research Council Short Questionnaire on Respiratory Symptoms (1960), amplified to include a detailed occupational history, and measurement of peak expiratory flow, FEV1, and FVC. Statistical analysis showed the control group to be at a slight disadvantage compared to the subject group in respect of complaints of phlegm and FVC. No evidence of any respiratory hazard due to glass fibre is shown. PMID:4703089

  13. 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.

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

    SciTech Connect

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

    2011-01-24

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

  15. Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos

    PubMed Central

    Beck, E. G.; Holt, P. F.; Manojlović, N.

    1972-01-01

    Beck, E. G., Holt, P. F., and Manojlović, N. (1972).Brit. J. industr. Med.,29, 280-286. Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos. The effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos are compared. Glass fibre behaves like chrysotile in producing an increase in cell membrane permeability in cultured macrophages. This is demonstrable by the increase in lactic dehydrogenase activity in the supernatant fluid. The metabolism, measured by lactate production, is not reduced as it is when quartz is phagocytosed. Glass powder behaves like the inert dust corundum, producing little change in the number of cells stained by erythrosin B and a small increase in lactate dehydrogenase activity, both being in the range of the control. There is an increase in lactate production as a result of higher metabolism due to phagocytosis. Dusts may produce two basic effects, namely a toxic effect and change in cell membrane permeability. A non-specific effect on the cell membrane due to the slow and sometimes incomplete process of ingestion of long fibres is probably a function of the morphology, particularly the length of the fibres. A primary specific effect induced by some dusts immediately follows contact with the cell membrane. Images PMID:4339803

  16. Comparison of effects of glass fibre and glass powder on guinea-pig lungs

    PubMed Central

    Botham, Susan K.; Holt, P. F.

    1973-01-01

    Botham, Susan K., and Holt, P. F. (1973).British Journal of Industrial Medicine,30, 232-236. Comparison of effects of glass fibre and glass powder on guinea-pig lungs. Following 24 hours inhalation by guinea-pigs of powdered glass dust, the pulmonary effects over the succeeding month differed from those previously observed to follow inhalation of glass fibre in that (1) fewer erythrocytes escaped from the capillaries, (2) very few giant cells were produced, (3) erythrocytes and intracellular glass particles were cleared more readily because junctions between respiratory and terminal bronchioles were not blocked by giant cells, (4) intracellular granules containing Perls-positive material did not appreciably increase in number or intensity of staining during the month, and (5) particles were not coated with Perls-positive material during the time that pseudo-asbestos bodies would be formed from glass fibres. The difference between the effects of chemically similar glass powder and fibre during a month in a guinea-pig lung is considered to be due to the morphology of the inhaled particle. Images PMID:4124978

  17. Multilayered Glass Fibre-reinforced Composites In Rotational Moulding

    NASA Astrophysics Data System (ADS)

    Chang, W. C.; Harkin-Jones, E.; Kearns, M.; McCourt, M.

    2011-05-01

    The potential of multiple layer fibre-reinforced mouldings is of growing interest to the rotational moulding industry because of their cost/performance ratio. The particular problem that arises when using reinforcements in this process relate to the fact that the process is low shear and good mixing of resin and reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcing agents segregating out of the powder to lay up on the inner part surface. In this study, short glass fibres were incorporated and distributed into a polymer matrix to produce fibre-reinforced polymer composites using the rotational moulding process and characterised in terms of morphology and mechanical properties.

  18. Multimode supercontinuum generation in chalcogenide glass fibres.

    PubMed

    Kubat, Irnis; Bang, Ole

    2016-02-01

    Mid-infrared supercontinuum generation is considered in chalcogenide fibres when taking into account both polarisations and the necessary higher order modes. In particular we focus on high pulse energy supercontinuum generation with long pump pulses. The modeling indicates that when only a single polarisation in the fundamental mode is considered the obtainable supercontinuum bandwidth is substantially exaggerated compared to when both polarisations are taken into account. Our modeling shows that if the pump pulse is short enough (≤ 10 ps) then higher order modes are not important because of temporal walk-off. In contrast long pump pulses (≥ 40 ps) will efficiently excite higher order modes through Raman scattering, which will deplete the fundamental mode of energy and limit the possibility of obtaining a broadband supercontinuum. PMID:26906826

  19. Mortality experience of glass fibre workers.

    PubMed Central

    Shannon, H S; Hayes, M; Julian, J A; Muir, D C

    1984-01-01

    A historical prospective mortality study was conducted at an insulating wool plant in Ontario, Canada, on 2576 men who had worked for at least 90 days and were employed between 1955 and 1977. Eighty eight deaths were found in the 97.2% of men traced. Mortality was compared by the person-years method with that of the Ontario population. Measurements taken since 1977 show very low fibre concentrations. The overall standardised mortality ratio (SMR) was 78%, significantly below 100. Among plant only employees, seven deaths were attributed to lung cancer compared with 4.22 expected, a non-significant excess (SMR = 166; 95% confidence limits 67 to 342). No confirmed cases of mesothelioma were observed and no other disease was significantly increased in plant workers. PMID:6691934

  20. Extending of flat normal dispersion profile in all-solid soft glass nonlinear photonic crystal fibres

    NASA Astrophysics Data System (ADS)

    Siwicki, Bartłomiej; Kasztelanic, Rafał; Klimczak, Mariusz; Cimek, Jarosław; Pysz, Dariusz; Stępień, Ryszard; Buczyński, Ryszard

    2016-06-01

    The bandwidth of coherent supercontinuum generated in optical fibres is strongly determined by the all-normal dispersion characteristic of the fibre. We investigate all-normal dispersion limitations in all-solid oxide-based soft glass photonic crystal fibres with various relative inclusion sizes and lattice constants. The influence of material dispersion on fibre dispersion characteristics for a selected pair of glasses is also examined. A relation between the material dispersion of the glasses and the fibre dispersion has been described. We determined the parameters which limit the maximum range of flattened all-normal dispersion profile achievable for the considered pair of heavy-metal-oxide soft glasses.

  1. Low Temperature Thermal Conductivity of Woven Fabric Glass Fibre Composites

    SciTech Connect

    Kanagaraj, S.; Pattanayak, S.

    2004-06-28

    Fibre reinforced composites are replacing conventional materials due to its compatible and superior properties at low temperatures. Transverse thermal conductivity of plain fabric E-glass/Epoxy composites with the fibre concentrations of 32.5%, 35.2%, 39.2% and 48.9% has been studied in a GM-refrigerator based experimental setup using guarded hotplate technique. Experiments are carried out with the sets of stability criteria. This paper presents the investigation of the influence of the fibre concentration and temperature on the thermal conductivity of fabric composites from 30 K to 300K. It is observed from the experimental results that thermal conductivity increases with the increase of temperature and also with fibre concentration with different rate in different temperature range. The series model has been used to predict the thermal conductivity and compared with the experimental results. It is observed that below the crossover temperature of the composites, which varies from 150-225K depending upon their fibre concentration, the experimental results are within 10% with that of predicted values. The possible causes of variation are analyzed. The physical phenomenon behind the temperature dependence of thermal conductivity is discussed in detail.

  2. Tensile properties of glass/natural jute fibre-reinforced polymer bars for concrete reinforcement

    NASA Astrophysics Data System (ADS)

    Han, J. W.; Lee, S. K.; Kim, K. W.; Park, C. G.

    2015-12-01

    The tensile performance of glass/natural jute fibre-reinforced polymer (FRP) bar, intended for concrete reinforcement was evaluated as a function of volume fraction of natural jute fibre. Natural jute fibre, mixed at a ratio of 7:3 with vinyl ester, was surface-treated with a silane coupling agent and used to replaced glass fibre in the composite in volume fractions of 0%, 30%, 50%, 70%, and 100%. The tensile load-displacement curve showed nearly linear elastic behaviour up to 50% natural jute fibre, but was partially nonlinear at a proportion of 70%. However, the glass/natural jute FRP bars prepared using 100% natural jute fibre showed linear elastic behaviour. Tensile strength decreased as the natural jute fibre volume fraction increased because the tensile strength of natural jute fibre is much lower than that of glass fibre (about 1:8.65). The degree of reduction was not proportional to the natural jute fibre volume fraction due to the low density of natural jute fibre (1/2 that of glass fibre). Thus, as the mix proportion of natural jute fibre increased, the amount (wt%) and number of fibres used also increased.

  3. Shock Interaction Studies on Glass Fibre Reinforced Epoxy Matrix Composites

    NASA Astrophysics Data System (ADS)

    Reddy, K. P. J.; Jagadeesh, G.; Jayaram, V.; Reddy, B. Harinath; Madhu, V.; Reddy, C. Jaya Rami

    Glass fibre reinforced polymer matrix composites are being extensively used for structural applications both in civil and defense sectors, owing to their high specific strength, stiffness and good energy absorbing capability. Understanding the dynamic response of these composites on shock loading is very essential for effective design of structures resistant to blast loads. In the present study, E- glass/epoxy composite laminate has been fabricated and evaluated for their mechanical properties such as tensile strength, flexural strength and inter laminar shear strength (ILSS). Further, dynamic response of E-glass laminates is presently studied by shock loading. When E-glass composite subjected to peak shock reflected pressure of 7.2 MPa and estimated temperature of about 14000 K for short duration, it underwent surface discolorations and charring of epoxy matrix. Post test analysis of the composite sample was carried out to study the damage analysis using Scanning Electron Microscope (SEM), changes in thermal properties of composites using Dynamic Mechanical Analyzer (DMA) and Thermo-Gravimetric Analyzer (TGA). The results of these investigations are discussed in this paper.

  4. Thermal recycling and re-manufacturing of glass fibre thermosetting composites

    NASA Astrophysics Data System (ADS)

    Fraisse, A.; Beauson, J.; Brøndsted, P.; Madsen, B.

    2016-07-01

    The impact of using thermally recycled glass fibre in re-manufactured composites was investigated. A unidirectional glass fibre thermosetting composite laminate was manufactured. The matrix in one part of the laminate was burnt off to recover the glass fibres. These recycled glass fibres were used to manufacture a new composite laminate with the same fibre architecture as the pristine one. The fibres, the matrix and the composite laminates were thoroughly characterised and analysed. The results show that good materials quality was obtained for both laminates. A difference in fibre packing behaviour was observed in the composites with the pristine and the recycled fibres, which lead to a lower fibre volume fraction in the latter one. The Young's modulus of the composites was not changed by the recycling process, if the lower fibre volume fraction is taken into account. However, a marked drop in the maximum stress of the composites was reported, which was found to be related to the loss in maximum stress of the fibres.

  5. 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.

  6. Glass fibres reinforced polyester composites degradation monitoring by surface analysis

    NASA Astrophysics Data System (ADS)

    Croitoru, Catalin; Patachia, Silvia; Papancea, Adina; Baltes, Liana; Tierean, Mircea

    2015-12-01

    The paper presents a novel method for quantification of the modifications that occur on the surface of different types of gel-coated glass fibre-reinforced polyester composites under artificial UV-ageing at 254 nm. The method implies the adsorption of an ionic dye, namely methylene blue, on the UV-aged composite, and computing the CIELab colour space parameters from the photographic image of the coloured composite's surface. The method significantly enhances the colour differences between the irradiated composites and the reference, in contrast with the non-coloured ones. The colour modifications that occur represent a good indicative of the surface degradation, alteration of surface hydrophily and roughness of the composite and are in good correlation with the ATR-FTIR spectroscopy and optical microscopy results. The proposed method is easier, faster and cheaper than the traditional ones.

  7. Parametric Study of End Milling Glass Fibre Reinforced Composites

    SciTech Connect

    Azmi, Azwan I.; Lin, Richard J. T.; Bhattacharyya, Debes

    2011-01-17

    This paper discusses the application of Taguchi 'Design of Experiment' method to investigate the effects of end milling parameters on machinability characteristics of unidirectional E-glass fibre reinforced polymer (GFRP) composites. A series of milling experiments were conducted using tungsten carbide end milling cutters at various spindle speeds, feed rates and depths of cut. Taguchi analysis was carried out and the signal to noise (S/N) ratio with analysis of variance (ANOVA) was employed to analyse the effects of those parameters on GFRP machinability. Overall, the results of the current investigations present some desirable combinations of the machining parameters that can further enhance the end milling machinability characteristics to suit the final requirements of the finished GFRP products.

  8. Conventional E-glass fibre light guides: self-sensing composite based on sol gel cladding

    NASA Astrophysics Data System (ADS)

    Wang, L.; Kister, G.; Ralph, B.; Talbot, J. D. R.; Fernando, G. F.

    2004-02-01

    The aim of this study was to modify conventional reinforcing E-glass fibres to enable them to act as optical waveguides and subsequently as sensor devices. This required the glass fibres to be coated with a relatively homogeneous coating with a corresponding refractive index that was lower than the E-glass fibre (1.56). Although a range of coating materials are available, this study focused on using materials that are generally used as sizing agents for glass fibres to improve the adhesion to the matrix. Two different methods based on conventional sol gel processing were used to obtain crack-free coatings. In the first method, tetraethoxysilane (TEOS) and polyvinyl alcohol were used as precursors. In the second method, acid-catalysed solutions of TEOS mixed with 3-glycidoxypropyltrimethoxysilane were used as precursors. UV visible transmission results showed that the films had low absorption and high transparency in the visible range. The refractive indices of the films were found to be a function of the molar fractions of the major chemical components. A simple impregnation procedure was used to apply the coating to the E-glass fibre bundles. The light transmission characteristics of the coated fibres along with their mechanical properties were evaluated. The sol gel coatings were shown to be effective in converting the conventional E-glass fibres into light guides.

  9. Research of glass fibre used in the electromagnetic wave shielding and absorption composite material

    NASA Astrophysics Data System (ADS)

    Xu, M.; Jia, F.; Bao, H. Q.; Cui, K.; Zhang, F.

    2016-07-01

    Electromagnetic shielding and absorption composite material plays an important role in the defence and economic field. Comparing with other filler, Glass fibre and its processed product—metal-coated glass fibre can greatly reduce the material's weight and costs, while it still remains the high strength and the electromagnetic shielding effectiveness. In this paper, the electromagnetic absorption mechanism and the reflection mechanism have been investigated as a whole, and the shielding effectiveness of the double-layer glass fibre composite material is mainly focused. The relationship between the shielding effectiveness and the filled glass fibre as well as its metal-coated product's parameters has also been studied. From the subsequent coaxial flange and anechoic chamber analysis, it can be confirmed that the peak electromagnetic shielding effectiveness of this double-layer material can reach -78dB while the bandwidth is from 2GHz to 18GHz.

  10. Optical fibre with a germanate glass core for lasing near 2 {mu}m

    SciTech Connect

    Dvoirin, Vladislav V; Mashinskii, Valerii M; Iskhakova, L D; Dianov, Evgenii M; Yashkov, M V; Khopin, V F; Gur'yanov, Aleksei N

    2011-01-24

    An optical fibre with a core based on thulium-doped germanate glass (45SiO{sub 2} - 55GeO{sub 2}) and a quartz glass cladding is developed for the first time. Lasing on Tm{sup 3+} ions ({lambda} =1.862 {mu}m) with an output power up to 70 mW at a differential efficiency of 37% is obtained in a laser based on this fibre. (letters)

  11. The influence of removing sizing on strength and stiffness of conventional and high modulus E-glass fibres

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Two types of E-glass fibres, a conventional and a high modulus where the last one in the following will be denoted as ECR-glass fibre, were investigated regarding density, diameter, stiffness and strength. The fibres were analysed as pristine and after sizing removal treatments. The sizing was removed by either burning at 565°C or soxhlet extraction with acetone. It was found that the density and the stiffness increased after removing the sizing by the two removal treatments whereas the diameter did not change significantly. The strength of the fibres decreased after burning as the sizing, protecting against water and fibre-fibre damage, had been removed. The strength of the fibres after extraction was not significantly different from the strength of the pristine fibres despite removing the sizing. This indicates that the bonded part of sizing is still protecting the glass fibre surface.

  12. 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.

  13. Cooperative luminescence and absorption in ytterbium doped aluminosilicate glass optical fibres and preforms

    NASA Astrophysics Data System (ADS)

    Ryan, Tom G.; Jackson, Stuart D.

    2007-05-01

    The cooperative luminescence and absorption properties of Yb 3+ doped aluminosilicate glass optical fibres and preforms are investigated in detail. In accordance with previous investigations, both the visible cooperative luminescence and the infrared luminescence decay measurements have been resolved into a single exponential decay component. We show that for a glass with similar Yb 3+ dopant concentration but more Al 3+, the glass emits less visible luminescence. Absorption loss measurements completed on fibre samples revealed a broad absorption in the 350-500 nm range, which we propose is due to a combination of Yb 2+ absorption and cooperative absorption from Yb 3+ ion pairs.

  14. Mechanical, degradation and cytocompatibility properties of magnesium coated phosphate glass fibre reinforced polycaprolactone composites.

    PubMed

    Liu, Xiaoling; Hasan, Muhammad S; Grant, David M; Harper, Lee T; Parsons, Andrew J; Palmer, Graham; Rudd, Chris D; Ahmed, Ifty

    2014-11-01

    Retention of mechanical properties of phosphate glass fibre reinforced degradable polyesters such as polycaprolactone and polylactic acid in aqueous media has been shown to be strongly influenced by the integrity of the fibre/polymer interface. A previous study utilising 'single fibre' fragmentation tests found that coating with magnesium improved the fibre and matrix interfacial shear strength. Therefore, the aim of this study was to investigate the effects of a magnesium coating on the manufacture and characterisation of a random chopped fibre reinforced polycaprolactone composite. Short chopped strand non-woven phosphate glass fibre mats were sputter coated with degradable magnesium to manufacture phosphate glass fibre/polycaprolactone composites. The degradation behaviour (water uptake, mass loss and pH change of the media) of these polycaprolactone composites as well as of pure polycaprolactone was investigated in phosphate buffered saline. The Mg coated fibre reinforced composites revealed less water uptake and mass loss during degradation compared to the non-coated composites. The cations released were also explored and a lower ion release profile for all three cations investigated (namely Na(+), Mg(2+) and Ca(2+)) was seen for the Mg coated composite samples. An increase of 17% in tensile strength and 47% in tensile modulus was obtained for the Mg coated composite samples. Both flexural and tensile properties were investigated and a higher retention of mechanical properties was obtained for the Mg coated fibre reinforced composite samples up to 10 days immersion in PBS. Cytocompatibility study showed both composite samples (coated and non-coated) had good cytocompatibility with human osteosarcoma cell line.

  15. Mechanical properties and fabrication of small boat using woven glass/sugar palm fibres reinforced unsaturated polyester hybrid composite

    NASA Astrophysics Data System (ADS)

    Misri, S.; Leman, Z.; Sapuan, S. M.; Ishak, M. R.

    2010-05-01

    In recent years, sugar palm fibre has been found to have great potential to be used as fibre reinforcement in polymer matrix composites. This research investigates the mechanical properties of woven glass/sugar palm fibres reinforced unsaturated polyester hybrid composite. The composite specimens made of different layer of fibres such as strand mat, natural and hand woven of sugar palm fibres. The composites were fabricated using a compression moulding technique. The tensile and impact test was carried out in accordance to ASTM 5083 and ASTM D256 standard. The fibre glass boat is a familiar material used in boat industry. A lot of research on fabrication process such as lay-up, vacuum infusion mould and resin transfer mould has been conducted. Hybrid material of sugar palm fibre and fibre glass was used in fabricating the boat. This research investigates the method selection for fabrication of small boat application of natural fibre composites. The composite specimens made of different layer of fibres; woven glass fibre, strand mat, natural and hand woven of woven sugar palm fibres were prepared. The small boat were fabricated using a compression moulding and lay up technique. The results of the experiment showed that the tensile strength, tensile modulus, elongation at break value and impact strength were higher than the natural woven sugar palm fibre. The best method for fabricating the small boat was compression moulding technique. As a general conclusion, the usage of glass fibre had improved the tensile properties sugar palm fibre composites and compression moulding technique is suitable to be used in making a small boat application of natural fibre composites.

  16. Lung cancer among glass fibre production workers: a case-control study.

    PubMed Central

    Gardner, M J; Magnani, C; Pannett, B; Fletcher, A C; Winter, P D

    1988-01-01

    A cohort study among 4734 employees at an English glass fibre plant previously reported no excess of lung cancer mortality either overall or when examined in broad occupational groups. To investigate occupation in more detail, and to test the hypothesis that processes producing or using finer (respirable) fibres may be related to a higher risk of lung cancer, a nested case-control study has now been carried out. Included are 73 cases of lung cancer and 506 matched controls, for whom jobs held and processes worked on have been blindly recorded in more detail than for the cohort study. Workers known to have been employed on processes containing respirable fibres had a relative risk of lung cancer of 1.2 (95% confidence interval 0.7-2.0) compared with other workers. There was no evidence of a relationship of lung cancer to fibre diameter, duration of exposure, or time since first exposure. The results by broad occupational group were similar to those of the cohort study, and although some of the many detailed occupational categories examined had significantly raised relative risks, these did not appear to be related to exposure to respirable glass fibre. Although the study has not indicated a differential risk of lung cancer among workers exposed to finer diameter glass fibres, the exposure levels were low and the number of cases small. PMID:3179236

  17. Craniofacial muscle engineering using a 3-dimensional phosphate glass fibre construct.

    PubMed

    Shah, R; Sinanan, A C M; Knowles, J C; Hunt, N P; Lewis, M P

    2005-05-01

    The current technique to replace missing craniofacial skeletal muscle is the surgical transfer of local or free flaps. This is associated with donor site morbidity, possible tissue rejection and limited supply. The alternative is to engineer autologous skeletal muscle in vitro, which can then be re-implanted into the patient. A variety of biomaterials have been used to engineer skeletal muscle with limited success. This study investigated the use of phosphate-based glass fibres as a potential scaffold material for the in vitro engineering of craniofacial skeletal muscle. Human masseter (one of the muscles of mastication)--derived cell cultures were used to seed the glass fibres, which were arranged into various configurations. Growth factors and matrix components were to used to manipulate the in vitro environment. Outcome was determined with the aid of microscopy, time-lapse footage, immunofluorescence imaging and CyQUANT proliferation, creatine kinase and protein assays. A 3-dimensional mesh arrangement of the glass fibres was the best at encouraging cell attachment and proliferation. In addition, increasing the density of the seeded cells and using Matrigel and insulin-like growth factor I enhanced the formation of prototypic muscle fibres. In conclusion, phosphate-based glass fibres can support the in vitro engineering of human craniofacial muscle.

  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. Alkaline composite PEO-PVA-glass-fibre-mat polymer electrolyte for Zn-air battery

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Lin, Sheng-Jen

    An alkaline composite PEO-PVA-glass-fibre-mat polymer electrolyte with high ionic conductivity (10 -2 S cm -1) at room temperature has been prepared and applied to solid-state primary Zn-air batteries. The electrolyte shows excellent mechanical strength. The electrochemical characteristics of the batteries were experimentally investigated by means of ac impedance spectroscopy and galvanostatic discharge. The results indicate that the PEO-PVA-glass-fibre-mat composite polymer electrolyte is a promising candidate for application in alkaline primary Zn-air batteries.

  20. 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.

  1. Mechanical behaviour of degradable phosphate glass fibres and composites-a review.

    PubMed

    Colquhoun, R; Tanner, K E

    2016-02-01

    Biodegradable materials are potentially an advantageous alternative to the traditional metallic fracture fixation devices used in the reconstruction of bone tissue defects. This is due to the occurrence of stress shielding in the surrounding bone tissue that arises from the absence of mechanical stimulus to the regenerating bone due to the mismatch between the elastic modulus of bone and the metal implant. However although degradable polymers may alleviate such issues, these inert materials possess insufficient mechanical properties to be considered as a suitable alternative to current metallic devices at sites of sufficient mechanical loading. Phosphate based glasses are an advantageous group of materials for tissue regenerative applications due to their ability to completely degrade in vivo at highly controllable rates based on the specific glass composition. Furthermore the release of the glass's constituent ions can evoke a therapeutic stimulus in vivo (i.e. osteoinduction) whilst also generating a bioactive response. The processing of these materials into fibres subsequently allows them to act as reinforcing agents in degradable polymers to simultaneously increase its mechanical properties and enhance its in vivo response. However despite the various review articles relating to the compositional influences of different phosphate glass systems, there has been limited work summarising the mechanical properties of different phosphate based glass fibres and their subsequent incorporation as a reinforcing agent in degradable composite materials. As a result, this review article examines the compositional influences behind the development of different phosphate based glass fibre compositions intended as composite reinforcing agents along with an analysis of different potential composite configurations. This includes variations in the fibre content, matrix material and fibre architecture as well as other novel composites designs.

  2. Assessment of solvent capsule-based healing for woven E-glass fibre-reinforced polymers

    NASA Astrophysics Data System (ADS)

    Manfredi, Erica; Cohades, Amaël; Richard, Inès; Michaud, Véronique

    2015-01-01

    Vacuum Assisted Resin Infusion Molding (VARIM) with low vacuum pressure difference was used to manufacture woven glass fibre-reinforced epoxy resin plates, with a fibre volume fraction of approx. 50 vol% and containing ethyl phenylacetate (EPA)-filled capsules for self-healing purposes. Capsules were introduced by functionalising the fabrics through manual dispersion. We investigated the capability of autonomously healing delaminations induced by static loading in Mode I and II. Healing did not take place for composite samples; this was attributed to the presence of bare fibres on the crack plane and to the reduction of EPA diffusion into the matrix in the presence of fibres both of which hinder the swelling mechanism responsible for healing the cracks.

  3. Laser Surface Pre-treatment of Aluminium for Hybrid Joints with Glass Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Heckert, André; Zaeh, Michael F.

    Lightweight construction is a major trend in the automotive industry. Theconnection of fibre reinforced plastics with aluminium is consequently seen as promising prospect. In this regard, thermal joining can be applied for bonding of such hybrid joints. But in order to create a load bearing metal plastic joint, the surface of the metal has to be pre-treated. Recent research has shown that with laser surface pre-treatment high joint strengths are obtained. Yet there are a variety of laser sources and manufacturable surface topographies with structure sizes ranging from macroscopic to nanoscopic profiles. Within this work,macroscopic, microscopic and nanoscopic laser processed structures are created on aluminium and consequently joined to glass fibre reinforced thermoplastics of different fibre length and fibre content. High shear tensile strengths of up to 42 N/mm2 were obtained depending on the allocated material and the surface pre-treatment.

  4. Effect of woven glass fibre reinforcement on the flexural strength of composites.

    PubMed

    Oberholzer, T G; du Preez, I C; Lombard, R; Pitout, E

    2007-10-01

    To measure and compare the flexural strength of composites reinforced with fibres, four groups of specimens (N = 10) were prepared from the combinations: Filtek Flow/Filtek Z250 and Esthet-X flow/Esthet-X dental composite. One group from each combination was reinforced with woven glass fibre (everStick net) and all the specimens subjected to three-point bend flexural testing. The mean and standard deviations for each test group were calculated and compared using one-way analysis of variance (ANOVA) followed by pairwise Bonferroni T-tests at a preset alpha of p < 0.05. It was found that fibre reinforcement significantly (p < 0.001) increased the flexural strength of both types of composites. As the inclusion of only one layer of glass fibre net produced an increase of approximately 30% in the flexural strength of the composite samples, it can be speculated that multiple layers would increase it even more. The use of fibre-reinforcement to strengthen directly placed composite crowns and bridges will enable the clinician to provide a more cost effective service as well as aesthetic dentistry to more patients.

  5. Cytocompatibility, degradation, mechanical property retention and ion release profiles for phosphate glass fibre reinforced composite rods.

    PubMed

    Felfel, R M; Ahmed, I; Parsons, A J; Palmer, G; Sottile, V; Rudd, C D

    2013-05-01

    Fibre reinforced composites have recently received much attention as potential bone fracture fixation applications. Bioresorbable composites based on poly lactic acid (PLA) and phosphate based glass fibre were investigated according to ion release, degradation, biocompatibility and mechanical retention profiles. The phosphate based glass fibres used in this study had the composition of 40P2O5-24MgO-16CaO-16Na2O-4Fe2O3 in mol% (P40). The degradation and ion release profiles for the composites showed similar trends with the amount of sodium and orthophosphate ions released being greater than the other cations and anions investigated. This was attributed to low Dietzal's field strength for the Na(+) in comparison with Mg(2+) and Ca(2+) and breakdown of longer chain polyphosphates into orthophosphate ions. P40 composites exhibited good biocompatibility to human mesenchymal stem cells (MSCs), which was suggested to be due to the low degradation rate of P40 fibres. After 63 days immersion in PBS at 37 °C, the P40 composite rods lost ~1.1% of mass. The wet flexural, shear and compressive strengths for P40 UD rods were ~70%, ~80% and ~50% of their initial dry values after 3 days of degradation, whereas the flexural modulus, shear and compressive strengths were ~70%, ~80%, and ~65% respectively. Subsequently, the mechanical properties remained stable for the duration of the study at 63 days. The initial decrease in mechanical properties was attributed to a combination of the plasticisation effect of water and degradation of the fibre-matrix interface, with the subsequent linear behaviour being attributed to the chemical durability of P40 fibres. P40 composite rods showed low degradation and ion release rates, good biocompatibility and maintained mechanical properties similar to cortical bone for the duration of the study. Therefore, P40 composite rods have huge potential as resorbable intramedullary nails or rods. PMID:23498213

  6. Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry

    NASA Astrophysics Data System (ADS)

    Jafari, S. M.; Alalawi, A. I.; Hussein, M.; Alsaleh, W.; Najem, M. A.; Hugtenburg, R. P.; Bradley, D. A.; Spyrou, N. M.; Clark, C. H.; Nisbet, A.

    2014-11-01

    An investigation has been made of glass beads and optical fibres as novel dosimeters for small-field photon radiation therapy dosimetry. Commercially available glass beads of largest dimension 1.5 mm and GeO2-doped SiO2 optical fibres of 5 mm length and 120 µm diameter were characterized as thermoluminescence dosimeters. Results were compared against Monte-Carlo simulations with BEAMnrc/DOSXYZnrc, EBT3 Gafchromic film, and a high-resolution 2D-array of liquid-filled ionization chambers. Measurements included relative output factors and dose profiles for square-field sizes of 1, 2, 3, 4, and 10 cm. A customized Solid-Water® phantom was employed, and the beads and fibres were placed at defined positions along the longitudinal axis to allow accurate beam profile measurement. Output factors and the beam profile parameters were compared against those calculated by BEAMnrc/DOSXYZnrc. The output factors and field width measurements were found to be in agreement with reference measurements to within better than 3.5% for all field sizes down to 2 cm2 for both dosimetric systems, with the beads showing a discrepancy of no more than 2.8% for all field sizes. The results confirm the potential of the beads and fibres as thermoluminescent dosimeters for use in small photon radiation field sizes.

  7. Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry.

    PubMed

    Jafari, S M; Alalawi, A I; Hussein, M; Alsaleh, W; Najem, M A; Hugtenburg, R P; Bradley, D A; Spyrou, N M; Clark, C H; Nisbet, A

    2014-11-21

    An investigation has been made of glass beads and optical fibres as novel dosimeters for small-field photon radiation therapy dosimetry. Commercially available glass beads of largest dimension 1.5 mm and GeO2-doped SiO2 optical fibres of 5 mm length and 120 µm diameter were characterized as thermoluminescence dosimeters. Results were compared against Monte-Carlo simulations with BEAMnrc/DOSXYZnrc, EBT3 Gafchromic film, and a high-resolution 2D-array of liquid-filled ionization chambers. Measurements included relative output factors and dose profiles for square-field sizes of 1, 2, 3, 4, and 10 cm. A customized Solid-Water® phantom was employed, and the beads and fibres were placed at defined positions along the longitudinal axis to allow accurate beam profile measurement. Output factors and the beam profile parameters were compared against those calculated by BEAMnrc/DOSXYZnrc. The output factors and field width measurements were found to be in agreement with reference measurements to within better than 3.5% for all field sizes down to 2 cm2 for both dosimetric systems, with the beads showing a discrepancy of no more than 2.8% for all field sizes. The results confirm the potential of the beads and fibres as thermoluminescent dosimeters for use in small photon radiation field sizes.

  8. Numerical Modelling of Glass Fibre Reinforced Laminates Subjected to a Low Velocity Impact

    SciTech Connect

    Fan, J. Y.; Guana, Z. W.; Cantwell, W. J.

    2010-05-21

    This paper presents a series of numerical predictions of the perforation behaviour of glass fibre laminates subjected to quasi-static and low-velocity impact loading. Both shear and tensile failure criteria were used in the finite element models to simulate the post-failure processes via an automatic element removal procedure. The appropriate material properties, obtained through a series of uniaxial tension and bending tests on the composites, were used in the numerical models. Four, eight and sixteen ply glass fibre laminates panels were perforated at quasi-static rates and under low-velocity impact loading. Reasonably good correlation was obtained between the numerical simulations and the experimental results, both in terms of the failure modes and the load-deflection relationships before and during the penetration phase. The predicted impact energies of the GFRP panels were compared with the experimental data and reasonable agreement was observed.

  9. Numerical Modelling of Glass Fibre Reinforced Laminates Subjected to a Low Velocity Impact

    NASA Astrophysics Data System (ADS)

    Fan, J. Y.; Guana, Z. W.; Cantwell, W. J.

    2010-05-01

    This paper presents a series of numerical predictions of the perforation behaviour of glass fibre laminates subjected to quasi-static and low-velocity impact loading. Both shear and tensile failure criteria were used in the finite element models to simulate the post-failure processes via an automatic element removal procedure. The appropriate material properties, obtained through a series of uniaxial tension and bending tests on the composites, were used in the numerical models. Four, eight and sixteen ply glass fibre laminates panels were perforated at quasi-static rates and under low-velocity impact loading. Reasonably good correlation was obtained between the numerical simulations and the experimental results, both in terms of the failure modes and the load-deflection relationships before and during the penetration phase. The predicted impact energies of the GFRP panels were compared with the experimental data and reasonable agreement was observed.

  10. Exposure, skin protection and occupational skin diseases in the glass-fibre-reinforced plastics industry.

    PubMed

    Tarvainen, K; Jolanki, R; Forsman-Grönholm, L; Estlander, T; Pfäffli, P; Juntunen, J; Kanerva, L

    1993-09-01

    A total of 100 workers, 86 from the glass-fibre-reinforced plastics (GRP) industry, 11 from polystyrene production and 3 from polyester resin coating manufacture, were examined for occupational skin hazards and for evaluation of skin protection. The workers had been exposed to many chemicals. Those working in the GRP industry had also been exposed to glass fibre and to dust produced by finishing work. 94% used protective gloves. 22 workers, all employed in the GRP industry, had contracted occupational skin disorders. 6 had allergic and 12 irritant contact dermatitis. 4 workers had an accidental injury caused by a peroxide catalyst, fire, hot air and constant mechanical friction. Allergic dermatoses were due to natural rubber (latex) (4 cases) in protective gloves, phenol-formaldehyde resin (1 case) and cobalt naphthenate (1 case). Irritant hand dermatoses (5 cases) were caused by the combined hazardous effect of unsaturated polyester or vinyl ester resins, organic solvents, glass fibre and dust from finishing work on the skin. Other cases of irritant dermatoses (7 cases) were due to the dust, promoted by mechanical friction of clothes. Skin disorders in the GRP industry were common (26%) but the symptoms were mild and only 3 patients had been on sick leave because of occupational skin disease. PMID:8222622

  11. Use of woven glass fibres to reinforce a composite veneer. A fracture resistance and acoustic emission study.

    PubMed

    Vallittu, P K

    2002-05-01

    The aim of this study was to investigate the possibility to reinforce the mechanically interlocked veneer of a porcelain-fused-to-metal (PFM) crown by woven glass fibre. A simulated situation to repair a fractured porcelain veneer was used in the experimental test set-up. A brass jig made into the shape of a framework of PFM maxillary central incisor crown with a retentive area at the palatal side of the incisal edge was used. A veneer were made with a restorative hybrid composite on the brass jig (control group). In the test groups, one or two layers of woven polymer pre-impregnated glass fibres (thickness: 0.06 mm/layer) were used by pressing the fibre weaves to the surface of the brass jig. Restorative hybrid composite was applied on the glass fibre weaves. Five veneers were made for all groups and the veneers were not cemented on the test jig. The veneers were loaded from the incisal edge until fracture occurred. The force was measured simultaneously with an acoustic emission analysis (AE) of the fracture propagation. Fracture force values for control veneers were 121 N and for those reinforced with one layer of glass fibres 399 N and for those reinforced with two layers of glass fibres 744 N ANOVA revealed significant difference between the mean values (P=0.003). The AE analysis showed different fracture propagation for the unreinforced and glass fibre reinforced veneers. The results of this study suggests that by placing two layers of woven glass fibres on the retentively shaped metal framework of the PFM crown before applying the restorative composite, considerably higher fracture resistance for the veneer could be obtained.

  12. The transverse mechanical behaviour of glass fibre reinforced plastics

    NASA Astrophysics Data System (ADS)

    Wells, Garry Michael

    The importance of transverse cracking in composites technology is highlighted by the use of classical lamination theory to predict the sequential damage process in cross-plied laminates. The literature on transverse fibre carposite behaviour is comprehensively reviewed, with particular emphasis on papers which present quantitative theoretical models. No work reviewed has measured the full range of mechanical properties on a single material necessary to allow a complete assessment of all the models of transverse failure. A resin system, based on epoxy/urethane blends, has been identified which allows production of high quality unidirectional composites with a systematic variation in flexibility. A preliminary experimental programme has identified those test specimens which can provide the necessary stress/strain and toughness properties of the range of flexibilised materials and thereby allow a validation of the theoretical models reviewed. In the preliminary experimental programme, transverse cracks are shown to extend with an increasing fracture toughness due to the formation of a 'tied zone' of fracture face bridging 'stringers' behind the crack tip. The influence of this effect on crack stability is discussed. By modelling the balance between fracture and strain energies, the equilibrium state of individual stringers is predicted. Direct observations of equilibrium stringer angles are seen to correspond with these predictions. A quite general model is developed which predicts, with reasonble accuracy, the observed increase of fracture toughness with crack extension and the geometry dependence of this increase. The literature models of stiffness, strength and failure strain are seen to display a dissappointing lack of agreement with the experimental results over the full range of material flexibilities. The influence of matrix Poisson constraint on these properties is discussed. Fracture toughness results indicate that very large critical defects control

  13. PCB glass-fibre laminates: Thermal conductivity measurements and their effect on simulation

    NASA Astrophysics Data System (ADS)

    Sarvar, F.; Poole, N. J.; Witting, P. A.

    1990-12-01

    Accurate values of thermal conductivity are required for the simulation of temperature phenomena in electronic circuits. This paper presents the results of measurements carried out to determine the thermal conductivity along and normal to the plane of fibre glass laminates used in the manufacture of printed circuit boards. It has been found that the reinforced fibre-glass substrates used in PCBs are strongly anisotropic with the conductivity normal to the boards being much smaller than tangential to it. The test samples were type FR4 epoxy/glass laminates. An experiment has been designed which determines the thermal conductivity in-the-plane of the laminates by matching the measured temperature distribution along a heated specimen with a finite difference solution. An electrically heated Lees’ disc apparatus is also used to measure the thermal conductivity of these boards in a direction normal to their plane. The samples tested yielded values of 0.343 W/mK and 1.059 W/mK for thermal conductivity through and along the plane of the boards, respectively.

  14. Controlling X-ray beam trajectory with a flexible hollow glass fibre

    PubMed Central

    Tanaka, Yoshihito; Nakatani, Takashi; Onitsuka, Rena; Sawada, Kei; Takahashi, Isao

    2014-01-01

    A metre-length flexible hollow glass fibre with 20 µm-bore and 1.5 mm-cladding diameters for transporting a synchrotron X-ray beam and controlling the trajectory has been examined. The large cladding diameter maintains a moderate curvature to satisfy the shallow glancing angle of total reflection. The observed transmission efficiency was more than 20% at 12.4 keV. As a demonstration, a wide-area scan of a synchrotron radiation beam was performed to identify the elements for a fixed metal film through its absorption spectra. PMID:24365917

  15. Incorporation of Yb 3+ ions in multicomponent phase-separated fibre glass preforms

    NASA Astrophysics Data System (ADS)

    Oppo, C. I.; Corpino, R.; Ricci, P. C.; Paul, M. C.; Das, S.; Pal, M.; Bhadra, S. K.; Yoo, S.; Kalita, M. P.; Boyland, A. J.; Sahu, J. K.; Ghigna, P.; d'Acapito, F.

    2012-02-01

    The local environment around Yb 3+ ions in silica-based optic fibre preforms has been studied in specimens with different composition and submitted to different annealing processes. The formation upon annealing of nano-sized particles of YbPO 4 has been evidenced by X-ray Absorption Spectroscopy whereas optical luminescence present Stark-split states in the anti-Stokes lines, typical of a structurally ordered phase. This evidences the preferential location of Yb in highly coordinated phosphate environment, with remarkable effects of such ordered phase on the optical response of the system. This study confirms and extends analogous observations done in previous literature on Erbium in similar glasses.

  16. Effect of loading rate on tensile properties and failure behavior of glass fibre/epoxy composite

    NASA Astrophysics Data System (ADS)

    Mahato, K. K.; Biswal, M.; Rathore, D. K.; Prusty, R. K.; Dutta, K.; Ray, B. C.

    2016-02-01

    Fibre reinforced polymeric (FRP) composite materials are subjected to different range of loading rates during their service life. Present investigation is focused on to study the effects of variation of loading rates on mechanical behavior and various dominating failure modes of these potential materials when subjected to tensile loading. The results revealed that on the variation of loading rates the ultimate tensile strength varies but the tensile modulus is mostly unaffected. Furthermore, the strain to failure is also increasing with increase in loading rates. Different failure patterns of glass/epoxy composite tested at 1, 10,100, 500 and 1000 mm/min loading rates are identified. Scanning electron micrographs shows various dominating failures modes in the glass/epoxy composite.

  17. Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.

    PubMed

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-01-01

    Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process.

  18. Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.

    PubMed

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-01-01

    Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process. PMID:23122715

  19. Impregnation of glass fibres with polymethylmethacrylate using a powder-coating method

    NASA Astrophysics Data System (ADS)

    Vallittu, Pekka K.

    1995-01-01

    The aim of this study was to evaluate the usefulness of a powder-coating method to impregnate glass fibres with polymethylmethacrylate (PMMA) for dental purposes. The continuous unidirectional E-glass fibres, the surface of which had been treated with precured silane, were powder-coated with spherical PMMA particles. Before the powder-coated prepregs were used, the incorporated PMMA powder was dissolved with methylmethacrylate monomer. The degree of impregnation of the polymerized composite was determined with a scanning electron microscope. The results revealed that the mean degree of impregnation varied from 0.87 to 0.92, being lower in the heat-cured PMMA group (which simulated fabrication of a new denture), and higher in the autopolymerizing group (which simulated the repair of a fractured denture). The means between the two groups did not, however, differ significantly ( p=0.249). The results suggest that, even though the method has some shortcomings in terms of dental laboratory technology, the powder-coating method can be used to fabricate or repair acrylic resin-based dentures.

  20. High-volume sampling of airborne polycyclic aromatic hydrocarbons using glass fibre filters and polyurethane foam

    NASA Astrophysics Data System (ADS)

    Thrane, K. E.; Mikalsen, A.

    A sampling system for collection of polycyclic aromatic hydrocarbons (PAH) in air is described. PAH were collected on glass fibre filters and plugs of polyurethane (PUR) foam by high-volume sampling. The analyses were carried out by high-resolution gas chromatography. The efficiency of these filter media has been investigated, and polyurethane foam seems to be efficient for the collection of selected PAH. The system has been used for PAH measurements in background, suburban and urban areas for average concentrations ranging from 20 to about 1500 ng m -3. A comparison of the profiles of PAH species obtained at the different locations shows that they are similar, and also that the relative concentrations of some of the compounds vary within only a few per cent. The distributions of the gas phase PAH found on the PUR plugs and in the particles collected on the glass fibre filters, correspond well with the results of a study on the gas-aerosol equilibrium made in Belgium.

  1. Helical core optical fibre made of Nd3+/Yb3+-doped oxyfluoride silicate glass

    NASA Astrophysics Data System (ADS)

    Dorosz, D.; Kochanowicz, M.; Zmojda, J.; Dorosz, J.

    2010-05-01

    The properties of helical-core optical fibre made by authors from Nd3+/Yb3+-doped oxyfluoride silicate glass are presented. The construction and forming conditions of the helical-core optical fibre enabled to obtain the helix pitch from several mm and the off-set ranging from 10 μm to 200 μm. The paper also presents optimisation of Nd3+/Yb3+ ratio to enhance the emission bandwidth at 1 μm. In consequence of matching the values of the emission cross-section σem(Nd)and the absorption cross-section σabs(Yb) in the glass doped with 0.15Nd3+:0.45Yb3+ a broad (Δλ = 100nm) luminescence band in the vicinity of 1μm was obtained, which was the result of overlapping emission transitions: 2F5/2-->2F7/2 in ytterbium and 4F3/2-->4I11/2 in neodymium.

  2. Holey Silicon as an Efficient Thermoelectric Material

    SciTech Connect

    Tang, Jinyao; Wang, Hung-Ta; Hyun Lee, Dong; Fardy, Melissa; Huo, Ziyang; Russell, Thomas P.; Yang, Peidong

    2010-09-30

    This work investigated the thermoelectric properties of thin silicon membranes that have been decorated with high density of nanoscopic holes. These ?holey silicon? (HS) structures were fabricated by either nanosphere or block-copolymer lithography, both of which are scalable for practical device application. By reducing the pitch of the hexagonal holey pattern down to 55 nm with 35percent porosity, the thermal conductivity of HS is consistently reduced by 2 orders of magnitude and approaches the amorphous limit. With a ZT value of 0.4 at room temperature, the thermoelectric performance of HS is comparable with the best value recorded in silicon nanowire system.

  3. Comparative study of spectroscopic properties of Er3+/Yb3+-codoped tellurite glass and fibres under 980nm excitation

    NASA Astrophysics Data System (ADS)

    Dai, Shi-Xun; Zhang, Jun-Jie; Li, Shun-Guang; Xu, Shi-Qing; Wang, Guo-Nian; Yang, Jian-Hu; Hu, Li-Li

    2004-12-01

    A tellurite fibre of TeO2-ZnO-La2O3-Li2O glass codoped with 20000 ppm ytterbium and 5000 ppm erbium was fabricated by the suction casting and rod-in-tube technologies. The absorption spectrum of Er3+/Yb3+ -codoped bulk glass has been measured. From the Judd-Ofelt intensity parameters, the spontaneous emission probability and radiative lifetime τrad of Er3+:4I13/2→4I15/2 transition for the bulk glass have been calculated. The emission fluorescence spectra and lifetimes around 1.5μm and subsequent upconversion fluorescence in the range of 500-700nm were measured in fibres and compared with those in bulk glass. The changes in amplified spontaneous emission with fibre length and pumping power was also measured. It was found that the emission spectrum from erbium in fibres is almost twice as broad as the corresponding spectrum in bulk glass when pumped at 980nm.

  4. Flexural strength,water sorption and solubility of a methylmethacrylate-free denture base polymer reinforced with glass fibre reinforcement.

    PubMed

    Mutluay, M M; Tezvergil-Mutluay, A; Vallittu, P; Lassila, L

    2013-12-01

    A methylmethacrylate-free denture base polymer (Eclipse) in comparison to a conventional denture base polymer (Palapress vario) was evaluated after water saturation and Stick glass fibre reinforcement. The data were analysed with ANOVA at a = 0.05. Water-storage caused a decrease in the flexural strength and stiffness of the materials (p > 0.05). Conventional denture base material with fibre reinforcement gave highest flexural strength (201.1 MPa) compared to fibre reinforced Eclipse (79.1 MPa) (p < 0.05). Water sorption after 76 days was 2.08% (Palapress vario) and 1.55% (Eclipse). Fibre-reinforcement of methylmethacrylate-free material was not as successful as conventional denture base and needs to be further optimized.

  5. Polymeric gel electrolytes reinforced with glass-fibre cloth for lithium secondary batteries

    NASA Astrophysics Data System (ADS)

    Park, Ho Cheol; Chun, Jong Han; Kim, Sang Hern; Ko, Jang Myoun; Jo, Soo Ik; Chung, Jae Sik; Sohn, Hun-Joon

    Polymeric gel electrolytes (PGE), based on polyacrylonitrile blended with poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-co-HFP)), which are reinforced with glass-fibre cloth (GFC) to increase the mechanical strength, are prepared for the practical use in lithium secondary batteries. The resulting electrolytes exhibit electrochemical stability at 4.5 V against lithium metal and a conductivity value of (2.0-2.1)×10 -3 S cm -1 at room temperature. The GFC-PGE electrolytes show excellent strength and flexibility when used in batteries even if they contain a plasticiser. A test cell with LiCoO 2 as a positive electrode and mesophase pich-based carbon fibre (MCF) as a negative electrode display a capacity of 110 mAh g -1 based on the positive electrode weight at the 0.2 C rate at room temperature. Over 80% of the initial capacity is retained after 400 cycles. This indicates that GFC is suitable as a reinforcing material to increase the mechanical strength of gel-based electrolytes for lithium secondary batteries.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  7. Foreign body granuloma of the penis caused by occupational glass fibre exposure.

    PubMed Central

    Hinnen, U; Elsner, P; Barraud, M; Burg, G

    1997-01-01

    We report a patient who presented with the suspected diagnosis of syphilis. Clinical findings included a penile ulcer, positive history of syphilis more than 20 years ago, and positive syphilis serology (TPHA, FTA-Abs). A biopsy showed a plasma-cell rich inflammation with granuloma formation. Since a birefractory structure was observed in the biopsy possibly corresponding to a foreign body, the patient's occupational exposure was investigated. Working in the fiber reinforced plastics industry, he was heavily exposed to glass fibre that was even detected on the inside of his underwear. Taking the serological pattern into account that was not consistent with active syphilis, a penile ulcer following a foreign body reaction was diagnosed. This case report demonstrates the difficulties of differentiating foreign body granuloma of the genital region from venereal diseases with granuloma formation. Images PMID:9582491

  8. Fatigue Behaviour of Glass Fibre Reinforced Composites for Ocean Energy Conversion Systems

    NASA Astrophysics Data System (ADS)

    Boisseau, A.; Davies, P.; Thiebaud, F.

    2013-04-01

    The development of ocean energy conversion systems places more severe requirements on materials than similar land-based structures such as wind turbines. Intervention and maintenance at sea are very costly, so for ocean energy supply to become economically viable long term durability must be guaranteed. Cyclic loading is a common feature of most energy conversion devices and composites are widely used, but few data are available concerning the fatigue behaviour in sea water of composite materials. This paper presents the results from an experimental study to fill this gap. The fatigue behavior of composite materials reinforced with different types of glass fibre is characterized in air and in sea water; the influence of testing in sea water rather than air is shown to be small. However, sea water ageing is shown to reduce the fatigue lifetime significantly and strongly depends on matrix formulation.

  9. Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Papadakis, V. M.; Müller, B.; Hagenbeek, M.; Sinke, J.; Groves, R. M.

    2016-04-01

    Nowadays, the application of glass-fibre composites in light-weight structures is growing. Although mechanical characterizations of those structures are commonly performed in testing, chemical changes of materials under stresses have not yet been well documented. In the present work coupon tests and Hyperspectral Imaging (HSI) have been used to categorise possible chemical changes of glass-fibre reinforced polymers (GFRP) which are currently used in the aircraft industry. HSI is a hybrid technique that combines spectroscopy with imaging. It is able to detect chemical degradation of surfaces and has already been successfully applied in a wide range of fields including astronomy, remote sensing, cultural heritage and medical sciences. GFRP specimens were exposed to two different thermal loading conditions. One thermal loading condition was a continuous thermal exposure at 120°C for 24h, 48 h and 96h, i.e. ageing at a constant temperature. The other thermal loading condition was thermal cycling with three different numbers of cycles (4000, 8000, 12000) and two temperature ranges (0°C to 120°C and -25°C to 95°C). The effects of both conditions were measured using both HSI and interlaminar shear (ILSS) tests. No significant changes of the physical properties of the thermally cycled GFRP specimens were detected using interlaminar shear strength tests and optical microscopy. However, when using HIS, differences of the surface conditions were detected. The results showed that the different thermal loading conditions could be successfully clustered in different colours, using the HSI linear unmixing technique. Each different thermal loading condition showed a different chemical degradation level on its surface which was indicated using different colours.

  10. Cytocompatibility and Mechanical Properties of Short Phosphate Glass Fibre Reinforced Polylactic Acid (PLA) Composites: Effect of Coupling Agent Mediated Interface

    PubMed Central

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew; Walker, Gavin; Scotchford, Colin

    2012-01-01

    In this study three chemical agents Amino-propyl-triethoxy-silane (APS), sorbitol ended PLA oligomer (SPLA) and Hexamethylene diisocyanate (HDI) were identified to be used as coupling agents to react with the phosphate glass fibre (PGF) reinforcement and the polylactic acid (PLA) polymer matrix of the composite. Composites were prepared with short chopped strand fibres (l = 20 mm, ϕ = 20 µm) in a random arrangement within PLA matrix. Improved, initial composite flexural strength (~20 MPa) was observed for APS treated fibres, which was suggested to be due to enhanced bonding between the fibres and polymer matrix. Both APS and HDI treated fibres were suggested to be covalently linked with the PLA matrix. The hydrophobicity induced by these coupling agents (HDI, APS) helped to resist hydrolysis of the interface and thus retained their mechanical properties for an extended period of time as compared to non-treated control. Approximately 70% of initial strength and 65% of initial modulus was retained by HDI treated fibre composites in contrast to the control, where only ~50% of strength and modulus was retained after 28 days of immersion in PBS at 37 °C. All coupling agent treated and control composites demonstrated good cytocompatibility which was comparable to the tissue culture polystyrene (TCP) control, supporting the use of these materials as coupling agent’s within medical implant devices. PMID:24955744

  11. Radio frequency shielding behaviour of silane treated Fe2O3/E-glass fibre reinforced epoxy hybrid composite

    NASA Astrophysics Data System (ADS)

    Arun prakash, V. R.; Rajadurai, A.

    2016-10-01

    In this work, radio frequency shielding behaviour of polymer (epoxy) matrixes composed of E-glass fibres and Fe2O3 fillers have been studied. The principal aim of this project is to prepare suitable shielding material for RFID application. When RFID unit is pasted on a metal plate without shielding material, the sensing distance is reduced, resulting in a less than useful RFID system. To improve RF shielding of epoxy, fibres and fillers were utilized. Magnetic behaviour of epoxy polymer composites was measured by hysteresis graphs (B-H) followed by radio frequency identifier setup. Fe2O3 particles of sizes 800, 200 and 100 nm and E-glass fibre woven mat of 600 g/m2 were used to make composites. Particle sizes of 800 nm and 200 nm were prepared by high-energy ball milling, whereas particles of 100 nm were prepared by sol-gel method. To enhance better dispersion of particles within the epoxy matrix, a surface modification process was carried out on fillers by an amino functional coupling agent called 3-Aminopropyltrimethoxysilane (APTMS). Crystalline and functional groups of siliconized Fe2O3 particles were characterized by XRD and FTIR spectroscopy analysis. Variable quantity of E-glass fibre (25, 35, and 45 vol%) was laid down along with 0.5 and 1.0 vol% of 800, 200, and 100 nm size Fe2O3 particles into the matrix, to fabricate the hybrid composites. Scanning electron microscopy and transmission electron microscopy images reveal the shape and size of Fe2O3 particles for different milling times and particle dispersion in the epoxy matrix. The maximum improved sensing distance of 45.2, 39.4 and 43.5 % was observed for low-, high-, and ultra-high radio frequency identifier setup along with shielding composite consist of epoxy, 1 vol% 200 nm Fe2O3 particles and 45 vol% of E-glass fibre.

  12. Glass transitions in native silk fibres studied by dynamic mechanical thermal analysis.

    PubMed

    Guan, Juan; Wang, Yu; Mortimer, Beth; Holland, Chris; Shao, Zhengzhong; Porter, David; Vollrath, Fritz

    2016-07-01

    Silks are a family of semi-crystalline structural materials, spun naturally by insects, spiders and even crustaceans. Compared to the characteristic β-sheet crystalline structure in silks, the non-crystalline structure and its composition deserves more attention as it is equally critical to the filaments' high toughness and strength. Here we further unravel the structure-property relationship in silks using Dynamic Mechanical Thermal Analysis (DMTA). This technique allows us to examine the most important structural relaxation event of the disordered structure the disordered structure, the glass transition (GT), in native silk fibres of the lepidopteran Bombyx mori and Antheraea pernyi and the spider Nephila edulis. The measured glass transition temperature Tg, loss tangent tan δ and dynamic storage modulus are quantitatively modelled based on Group Interaction Modelling (GIM). The "variability" issue in native silks can be conveniently explained by the different degrees of structural disorder as revealed by DMTA. The new insights will facilitate a more comprehensive understanding of the structure-property relations for a wide range of biopolymers. PMID:27320178

  13. The reinforcement effect of polyethylene fibre and composite impregnated glass fibre on fracture resistance of endodontically treated teeth: An in vitro study

    PubMed Central

    Luthria, Archana; Srirekha, A; Hegde, Jayshree; Karale, Rupali; Tyagi, Sanjana; Bhaskaran, Sajeev

    2012-01-01

    Aim: The aim of this study was to evaluate the fracture resistance of endodontically treated maxillary premolars with wide mesio-occluso-distal (MOD) cavities restored with either composite resin, or composite resin reinforced with different types of fibres. Materials and Methods: Fifty human maxillary premolars were selected. Five intact teeth served as positive controls. Endodontic therapy was carried out in the remaining forty-five teeth. Standardized MOD cavities were prepared in all the teeth. The teeth were restored with a nanocomposite using an incremental technique. These forty five teeth were randomly divided into three experimental groups (Group A, B and C) (n = 15). The teeth in Group A did not undergo any further procedures. The teeth in Group B and C were reinforced with composite impregnated glass fibre and polyethylene fibre, respectively. Fracture resistance was measured in Newtons (N). Results: The positive controls showed the highest mean fracture resistance (811.90 N), followed by Group B (600.49N), Group A (516.96N) and Group C (514.64N), respectively. One Way analysis of variance (ANOVA) test revealed a statistically significant difference between all the groups (P = 0.001). Post-hoc Tukey test revealed a moderately significant difference (P = 0.034) between Control and Group B, and a strongly significant difference between Control and Group A (P = 0.002), and Control and Group C (P = 0.001). Conclusions: Endodontic therapy and MOD cavity preparation significantly reduced the fracture resistance of endodontically treated maxillary premolars (P = 0.001). No statistically significant difference was found between the experimental groups (Group A, B and C) (P > 0.1). However, the fracture resistance of the composite impregnated glass fibre reinforced group was much higher than the others. PMID:23112487

  14. Effect of Si and Fe doping on calcium phosphate glass fibre reinforced polycaprolactone bone analogous composites.

    PubMed

    Mohammadi, M Shah; Ahmed, I; Muja, N; Almeida, S; Rudd, C D; Bureau, M N; Nazhat, S N

    2012-04-01

    Reinforcing biodegradable polymers with phosphate-based glass fibres (PGF) is of interest for bone repair and regeneration. In addition to increasing the mechanical properties, PGF can also release bioinorganics, as they are water soluble, a property that may be controllably translated into a fully degradable composite. Herein, the effect of Si and Fe on the solubility of calcium-containing phosphate-based glasses (PG) in the system (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x=0, 5 and 10 mol.%) were investigated. On replacing SiO(2) with Fe(2)O(3), there was an increase in the glass transition temperature and density of the PG, suggesting greater crosslinking of the phosphate chains. This significantly reduced the dissolution rates of degradation and ion release. Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibres and randomly incorporated into polycaprolactone (PCL). Initially, the flexural strength and modulus significantly increased with PGF incorporation. In deionized water, PCL-Fe(5)Si(5) displayed a significantly greater weight loss and ion release compared with PCL-Fe10. In simulated body fluid, brushite was formed only on the surface of PCL-Fe(5)Si(5). Dynamic mechanical analysis in phosphate buffered saline (PBS) at 37°C revealed that the PCL-Fe10 storage modulus (E') was unchanged up to day 7, whereas the onset of PCL-Fe(5)Si(5)E' decrease occurred at day 4. At longer-term ageing in PBS, PCL-Fe(5)Si(5) flexural strength and modulus decreased significantly. MC3T3-E1 preosteoblasts seeded onto PCL-PGF grew up to day 7 in culture. PGF can be used to control the properties of biodegradable composites for potential application as bone fracture fixation devices.

  15. Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50 mol% P2O5

    PubMed Central

    Sharmin, Nusrat; Parsons, Andrew J; Rudd, Chris D

    2014-01-01

    Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P2O5 content less than 50 mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 contents fixed at 40, 45 and 50 mol%, where Na2O was replaced by 5 and 10 mol% B2O3 and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2O3 addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10 mol% B2O3 enabled successful drawing of continuous fibres from glasses with phosphate (P2O5) contents fixed at 40, 45 and 50 mol%. The mechanical properties of the fibres were found to significantly increase with increasing B2O3 content. The highest tensile strength (1200 ± 130 MPa) was recorded for 45P2O5-16CaO-5Na2O-24MgO-10B2O3 glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37℃ for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B2O3-containing glass fibres were found to degrade at a much slower rate as compared to the non-B2O3-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation. PMID:24939962

  16. In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties.

    PubMed

    Chen, Menghao; Parsons, Andrew J; Felfel, Reda M; Rudd, Christopher D; Irvine, Derek J; Ahmed, Ifty

    2016-06-01

    Fully bioresorbable composites have been investigated in order to replace metal implant plates used for hard tissue repair. Retention of the composite mechanical properties within a physiological environment has been shown to be significantly affected due to loss of the integrity of the fibre/matrix interface. This study investigated phosphate based glass fibre (PGF) reinforced polycaprolactone (PCL) composites with 20%, 35% and 50% fibre volume fractions (Vf) manufactured via an in-situ polymerisation (ISP) process and a conventional laminate stacking (LS) followed by compression moulding. Reinforcing efficiency between the LS and ISP manufacturing process was compared, and the ISP composites revealed significant improvements in mechanical properties when compared to LS composites. The degradation profiles and mechanical properties were monitored in phosphate buffered saline (PBS) at 37°C for 28 days. ISP composites revealed significantly less media uptake and mass loss (p<0.001) throughout the degradation period. The initial flexural properties of ISP composites were substantially higher (p<0.0001) than those of the LS composites, which showed that the ISP manufacturing process provided a significantly enhanced reinforcement effect than the LS process. During the degradation study, statistically higher flexural property retention profiles were also seen for the ISP composites compared to LS composites. SEM micrographs of fracture surfaces for the LS composites revealed dry fibre bundles and poor fibre dispersion with polymer rich zones, which indicated poor interfacial bonding, distribution and adhesion. In contrast, evenly distributed fibres without dry fibre bundles or polymer rich zones, were clearly observed for the ISP composite samples, which showed that a superior fibre/matrix interface was achieved with highly improved adhesion.

  17. Glass fibre-reinforced composite post and core used in decayed primary anterior teeth: a case report.

    PubMed

    Verma, Leena; Passi, Sidhi

    2011-01-01

    Aesthetic requirement of severely mutilated primary anterior teeth in the case of early childhood caries has been a challenge to pediatric dentist. Among restorative treatment options, prefabricated crown and biological and resin composite restoration either by means of direct or indirect technique are mentioned in the literature. This paper presents the clinical sequence of rehabilitation of maxillary anterior primary teeth. Endodontic treatment was followed by the placement of a glass fibre-reinforced composite resin post. The crown reconstruction was done with composite restoration. Resin glass fibre post has best properties in elasticity, translucency, adaptability, tenaciousness, and resistance to traction and to impact. Along with ease of application, fiber can be used as an alternative to traditionally used materials in the management of early childhood caries.

  18. Glass Fibre-Reinforced Composite Post and Core Used in Decayed Primary Anterior Teeth: A Case Report

    PubMed Central

    Verma, Leena; Passi, Sidhi

    2011-01-01

    Aesthetic requirement of severely mutilated primary anterior teeth in the case of early childhood caries has been a challenge to pediatric dentist. Among restorative treatment options, prefabricated crown and biological and resin composite restoration either by means of direct or indirect technique are mentioned in the literature. This paper presents the clinical sequence of rehabilitation of maxillary anterior primary teeth. Endodontic treatment was followed by the placement of a glass fibre-reinforced composite resin post. The crown reconstruction was done with composite restoration. Resin glass fibre post has best properties in elasticity, translucency, adaptability, tenaciousness, and resistance to traction and to impact. Along with ease of application, fiber can be used as an alternative to traditionally used materials in the management of early childhood caries. PMID:22567447

  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 monomer composition of polymer matrix on flexural properties of glass fibre-reinforced orthodontic archwire.

    PubMed

    Ohtonen, J; Vallittu, P K; Lassila, L V J

    2013-02-01

    To compare force levels obtained from glass fibre-reinforced composite (FRC) archwires. Specifically, FRC wires were compared with polymer matrices having different dimethacrylate monomer compositions. FRC material (E-glass provided by Stick Tech Ltd, Turku, Finland) with continuous unidirectional glass fibres and four different types of dimethacrylate monomer compositions for the resin matrix were tested. Cross-sectionally round FRC archwires fitting into the 0.3 mm slot of a bracket were divided into 16 groups with six specimens in each group. Glass fibres were impregnated by the manufacturer, and they were initially light-cured by hand light-curing unit or additionally post-cured in light-curing oven. The FRC archwire specimens were tested at 37°C according to a three-point bending test in dry and wet conditions using a span length of 10 mm and a crosshead speed of 1.0 mm/minute. The wires were loaded until final failure. The data were statistically analysed using analysis of variance (ANOVA). The dry FRC archwire specimens revealed higher load values than water stored ones, regardless of the polymer matrix. A majority of the FRC archwires showed higher load values after being post-cured. ANOVA revealed that the polymer matrix, curing method, and water storage had a significant effect (P < 0.05) on the flexural behaviour of the FRC archwire. Polymer matrix composition, curing method, and water storage affected the flexural properties and thus, force level and working range which could be obtained from the FRC archwire. PMID:22058110

  1. Reusing fly ash in glass fibre reinforced cement: a new generation of high-quality GRC composites.

    PubMed

    Payá, J; Bonilla, M; Borrachero, M V; Monzó, J; Peris-Mora, E; Lalinde, L F

    2007-01-01

    New composite materials based on an alkali-resistant glass-fibre reinforced cement (AR-GRC) system are being developed by using fly ash (FA) produced at coal thermoelectric power plants, and fluid catalytic cracking catalyst residue (FC3R) from the petrol industry as cement replacement materials. These wastes are reactive from the pozzolanic viewpoint, and modify the nature and the microstructure of the cement matrix when a part of the Portland cement is replaced in the formulation of GRC. Several microstructural and mechanical aspects are being studied for AR-GRC systems. The behaviour of composites exposed to ageing shows that the pozzolanic activity of the ground FA added in high amounts and its mixture with the FC3R increase the flexural strength and no evidences of strength decay are observed. Additionally, the fibres due to the high alkalinity of the cementing matrix can be deteriorated. Fibres in the control (only Portland cement) and FC3R containing composites were attacked, whereas composites with FA and their mixture with FC3R show that the fibres have not been attacked, due to the pozzolanic activity of replacing materials that reduce the calcium hydroxide content in the cementing matrix. PMID:17512718

  2. Trends in Occupational Exposure to Styrene in the European Glass Fibre-Reinforced Plastics Industry

    PubMed Central

    Van Rooij, J. G. M.; Kasper, A.; Triebig, G.; Werner, P.; Kromhout, H.

    2008-01-01

    Aim: This study presents temporal trends of styrene exposure for workers in the European glass fibre-reinforced plastics (GRP) industry during the period 1966–2002. Methods: Data of personal styrene exposure measurements were retrieved from reports, databases and peer-reviewed papers. Only sources with descriptive statistics of personal measurements were accepted. The styrene exposure data cover personal air samples and biological monitoring data, that is, urinary styrene metabolites (mandelic acid and/or phenylglyoxylic acid) and styrene in blood. Means of series of measurements were categorized by year, country, production process, job and sampling strategy. Linear mixed models were used to identify temporal trends and factors affecting exposure levels. Results: Personal exposure measurements were available from 60 reports providing data on 24145 1–8-h time-weighted average shift personal air samples. Available data of biological exposure indicators included measurements of mandelic acid in post-shift urine (6361 urine samples being analysed). Trend analyses of the available styrene exposure data showed that the average styrene concentration in the breathing zone of open-mould workers in the European GRP industry has decreased on average by 5.3% per year during the period 1966–1990 and by only 0.4% annually in the period after 1990. The highest exposures were measured in Southern Europe and the lowest exposures in Northern Europe with Central Europe in between. Biological indicators of styrene (mandelic acid in post-shift urine) showed a somewhat steeper decline (8.9%), most likely because urine samples were collected in companies that showed a stronger decrease of styrene exposure in air than GRP companies where no biological measurements were carried out. PMID:18550625

  3. The effect of a new formaldehyde-free binder on the dissolution rate of glass wool fibre in physiological saline solution

    PubMed Central

    2013-01-01

    The in-vitro dissolution rate of fibres is a good predictor of the in-vivo behavior and potential health effects of inhaled fibres. This study examines the effect of a new formaldehyde-free carbohydrate-polycarboxylic acid binder on the in-vitro dissolution rate of biosoluble glass fibres. Dissolution rate measurements in pH 7.4 physiological saline solution show that the presence of the binder on wool insulation glass fibres has no effect on their dissolution. There is no measurable difference between the dissolution rates of continuous draw fibres before and after binder was applied by dipping. Nor is there a measurable difference between the dissolution rates of a production glass wool sample with binder and that same sample after removal of the binder by low-temperature ashing. Morphological examination shows that swelling of the binder in the solution is at least partially responsible for the development of open channels around the glass-binder interface early in the dissolution. These channels allow fluid to reach the entire glass surface under the binder coating. There is no evidence of any delay in the dissolution rate as a result of the binder coating. PMID:23587247

  4. Effect of phosphate-based glass fibre surface properties on thermally produced poly(lactic acid) matrix composites.

    PubMed

    Mohammadi, Maziar Shah; Ahmed, Ifty; Muja, Naser; Rudd, Christopher D; Bureau, Martin N; Nazhat, Showan N

    2011-12-01

    Incorporation of soluble bioactive glass fibres into biodegradable polymers is an interesting approach for bone repair and regeneration. However, the glass composition and its surface properties significantly affect the nature of the fibre-matrix interface and composite properties. Herein, the effect of Si and Fe on the surface properties of calcium containing phosphate based glasses (PGs) in the system (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x = 0, 5 and 10 mol.%) were investigated. Contact angle measurements revealed a higher surface energy, and surface polarity as well as increased hydrophilicity for Si doped PG which may account for the presence of surface hydroxyl groups. Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibres and randomly incorporated into poly(lactic acid) (PLA) produced by melt processing. The ageing in deionised water (DW), mechanical property changes in phosphate buffered saline (PBS) and cytocompatibility properties of these composites were investigated. In contrast to Fe10 and as a consequence of the higher surface energy and polarity of Fe5Si5, its incorporation into PLA led to increased inorganic/organic interaction indicated by a reduction in the carbonyl group of the matrix. PLA chain scission was confirmed by a greater reduction in its molecular weight in PLA-Fe5Si5 composites. In DW, the dissolution rate of PLA-Fe5Si5 was significantly higher than that of PLA-Fe10. Dissolution of the glass fibres resulted in the formation of channels within the matrix. Initial flexural strength was significantly increased through PGF incorporation. After PBS ageing, the reduction in mechanical properties was greater for PLA-Fe5Si5 compared to PLA-Fe10. MC3T3-E1 preosteoblasts seeded onto PG discs, PLA and PLA-PGF composites were evaluated for up to 7 days indicating that the materials were generally cytocompatible. In addition, cell alignment along the PGF

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  6. Production and characterization of polypropylene composites filled with glass fibre recycled from pyrolysed waste printed circuit boards.

    PubMed

    Li, Shenyong; Sun, Shuiyu; Liang, Haifeng; Zhong, Sheng; Yang, Fan

    2014-01-01

    Waste printed circuit boards (WPCBs) are composed of nearly 70% non-metals, which are generally recycled as low-value filling materials or even directly dumped in landfills. In this study, polypropylene (PP) composites reinforced by recycled pure glass fibres (RGF) from pyrolysed WPCBs were successfully produced. The manufacturing process, mechanical properties and thermal behaviour of the composites were investigated. The results showed that the appropriate addition of RGF in the composites can significantly improve the mechanical properties and thermal behaviour. When the added content of RGF was 30%, the maximum increment of tensile strength, impact strength, flexural strength and flexural modulus of the glass fibre (GF)/PP composites are 25.93%, 41.38%, 31.16% and 68.42%, respectively, and the vicat softening temperature could rise by 4.6°C. Furthermore, leaching of the GF/PP composites was also investigated. The GF/PP composites exhibited high performance and non-toxicity, offering a promising method to recycle RGF from pyrolysed WPCBs with high-value applications. PMID:25176309

  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. Cytocompatibility, mechanical and dissolution properties of high strength boron and iron oxide phosphate glass fibre reinforced bioresorbable composites.

    PubMed

    Sharmin, Nusrat; Hasan, Muhammad S; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

    2016-06-01

    In this study, Polylactic acid (PLA)/phosphate glass fibres (PGF) composites were prepared by compression moulding. Fibres produced from phosphate based glasses P2O5-CaO-MgO-Na2O (P45B0), P2O5-CaO-MgO-Na2O-B2O3 (P45B5), P2O5-CaO-MgO-Na2O-Fe2O3 (P45Fe3) and P2O5-CaO-MgO-Na2O-B2O3-Fe2O3 (P45B5Fe3) were used to reinforce the bioresorbable polymer PLA. Fibre mechanical properties and degradation rate were investigated, along with the mechanical properties, degradation and cytocompatibility of the composites. Retention of the mechanical properties of the composites was evaluated during degradation in PBS at 37°C for four weeks. The fibre volume fraction in the composite varied from 19 to 23%. The flexural strength values (ranging from 131 to 184MPa) and modulus values (ranging from 9.95 to 12.29GPa) obtained for the composites matched those of cortical bone. The highest flexural strength (184MPa) and modulus (12.29GPa) were observed for the P45B5Fe3 composite. After 28 days of immersion in PBS at 37°C, ~35% of the strength profile was maintained for P45B0 and P45B5 composites, while for P45Fe3 and P45B5Fe3 composites ~40% of the initial strength was maintained. However, the overall wet mass change of P45Fe3 and P45B5Fe3 remained significantly lower than that of the P45B0 and P45B5 composites. The pH profile also revealed that the P45B0 and P45B5 composites degraded quicker, correlating well with the degradation profile. From SEM analysis, it could be seen that after 28 days of degradation, the fibres in the fractured surface of P45B5Fe3 composites remain fairly intact as compared to the other formulations. The in vitro cell culture studies using MG63 cell lines revealed both P45Fe3 and P45B5Fe3 composites maintained and showed higher cell viability as compared to the P45B0 and P45B5 composites. This was attributed to the slower degradation rate of the fibres in P45Fe3 and P45B5Fe3 composites as compared with the fibres in P45B0 and P45B5 composites.

  9. 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.

  10. Synthesis and Modification of Holey Graphene for Energy Storage

    NASA Technical Reports Server (NTRS)

    Lin, Yi; Kim, Jae-Woo; Connell, John W.

    2015-01-01

    Porous graphene materials have recently drawn significant interest for energy storage applications due to the effective use of the graphitic surface area provided by the pores. Holey graphene is a type of porous graphene with pores in the form of physical through thickness holes. This type of porous graphene provides a unique morphology that allows for effective transport of molecular species through the graphene plane. Therefore, as we recently demonstrated, holey graphene could be advantageous in the preparation of electrodes in supercapacitors with high volumetric performance.1 We have developed methodologies to scalably prepare holey graphene materials with or without the use of catalysts (Figure 1).1,2 In this presentation, we will discuss the choice of synthetic strategies and experimental conditions on the morphology and physical properties of holey graphene (Figure 2) and the effect on their electrochemical properties. We will also present the results on the further modification of holey graphene to study their physical and chemical properties, especially with regard to the stability and chemical reactivity of carbons located around the edges of the holes.

  11. The use of an interphase to improve the transverse properties of unidirectional glass fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Ellis, Keith

    The aim of the project was to improve the transverse mechanical properties of unidirectional glass fibre reinforced plastics (G.R.P.)* In addition it was intended that the longitudinal mechanical properties should not be Significantly a result of the transverse improvement The scientific and commercial literature were consulted to determine the most feasible means of improving the transverse properties. Four possible methods were identified, the most promising of which was interfacial modification. Interfacial modification involves the introduction of a third material ("the interphase" ) at the interface between the fibre and the matrix. For this project the interphase material was selected to be compliant or rubbery in nature. The Kies model for predicting the magnification of strain in the resin between fibres was extended to include an interphase. The model was developed for two modes of applied stress. The first was pure tension acting transverse to the fibre axis. The second was shear in the plane transverse to the fibre axis. A novel apparatus was constructed to manufacture composites with a compliant interphase. The apparatus combined a self-regulating coating technique with filament winding to give a continuous production facility. A range of mechanical tests were performed on composites both with and without an interphase. Presence of an interphase improved the following properties: transverse flexural strength, interlaminar and intralaminar shear strength , and transverse fiexural fracture energy. No improvement was noted for pure transverse tension. These results indicated that the interphase acted beneficially only when the composite was stressed in a predominantly shear mode. Conclusions from mechanical test results were supported by S.E.M. fractography. Considerable deformation of the interphase was found in composite tested in shear. This deformation was absent in composite tested in tension. It was postulated that these differences between behaviour

  12. An exploration of the relationship of chemical and physical parameters in the micromechanical characterisation of the apparent interfacial strength in glass fibre epoxy systems

    NASA Astrophysics Data System (ADS)

    Thomason, J. L.; Yang, L.; Bryce, D.; Minty, R.

    2016-07-01

    This paper focuses on the cure shrinkage and the thermomechanical properties of an amine cured epoxy resin system and its adhesion to glass fibre. The fibre-matrix interfacial shear strength (IFSS) was characterized using the microbond test over a range of test temperatures and a range of amine:epoxy ratios. The apparent IFSS in this glass-epoxy system was shown to be strongly dependent on the testing temperature and the matrix stoichiometry. High levels of cure shrinkage were measured in the IFSS microdroplets which resulted in internal stresses causing significant levels of droplet deformation. The results presented here can be interpreted as providing further support for the hypothesis that a significant fraction of the interfacial stress transfer capability in epoxy composites can be attributed to a combination of residual radial compressive stress and static friction at the fibre-matrix interface.

  13. Shaper-assisted phase optimization of a broad "holey" spectrum.

    PubMed

    Zhi, Miaochan; Wang, Kai; Hua, Xia; Strycker, Benjamin D; Sokolov, Alexei V

    2011-11-01

    We develop a technique for optimizing the phase of broad spectrally-separated frequency sidebands-a "holey" spectrum. We use a source of multiple-order coherent Raman sidebands, obtained by crossing femtosecond pump and Stokes beams in synthetic single-crystal diamond. We combine the sidebands into a single beam and show the phase coherence among the sidebands by investigating the interference between them in groups of three while varying one sideband phase by an acousto-optics pulse shaper. We then show how we optimize the broad "holey" spectrum by overcoming the limited temporal shaping window of the pulse shaper. We also explore how the resultant second harmonic/sum frequency generation of the full combined broadband spectrum varies as we vary different sideband phases. This step-by-step phase optimization of the "holey" spectrum can be applied to sidebands with similar structure to synthesize arbitrary optical waveforms.

  14. Effect of ferrule height and glass fibre post length on fracture resistance and failure mode of endodontically treated teeth.

    PubMed

    Abdulrazzak, Shurooq S; Sulaiman, Eshamsul; Atiya, Basim K; Jamaludin, Marhazlinda

    2014-08-01

    The purpose of this study was to evaluate the combined effect of ferrule height and post length on fracture resistance and failure mode of endodontically treated teeth restored with glass fibre posts, composite resin cores and crowns. Ninety human maxillary central incisors were endodontically treated and divided into three groups (n = 30) according to the ferrule heights: 4, 2 and 0 mm, respectively. Post spaces in each group were prepared at 2/3, 1/2 and 1/3 of the root length (n = 10). The specimens were received fibre posts, composite resin core build up and cast metal crowns. After thermocycling, compressive static load was applied at an angle of 135° to the crowns. Two-way analysis of variance showed significant differences in the failure load in the ferrule height groups, no significant differences in post length groups and no significant interaction between ferrule heights and post lengths. More restorable failure modes were observed. PMID:24118334

  15. Effect of post-space treatments on the push-out bond strength and failure modes of glass fibre posts.

    PubMed

    Arisu, Hacer Deniz; Kivanç, Bağdagül Helvacioğlu; Sağlam, Baran C; Şimşek, Eser; Görgül, Güliz

    2013-04-01

    The aim of this study was to evaluate the effect of different post-space treatments on the push-out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push-out test. Data were statistically analysed with anova (P = 0.05). After push-out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.

  16. Enhanced Terahertz Imaging of Small Forced Delamination in Woven Glass Fibre-reinforced Composites with Wavelet De-noising

    NASA Astrophysics Data System (ADS)

    Dong, Junliang; Locquet, Alexandre; Citrin, D. S.

    2016-03-01

    Terahertz (THz) reflection imaging is applied to characterize a woven glass fibre-reinforced composite laminate with a small region of forced delamination. The forced delamination is created by inserting a disk of 25- μ m-thick Upilex film, which is below the THz axial resolution, resulting in one featured echo with small amplitude in the reflected THz pulses. Low-amplitude components of the temporal signal due to ambient water vapor produce features of comparable amplitude with features associated with the THz pulse reflected off the interfaces of the delamination and suppress the contrast of THz C- and B-scans. Wavelet shrinkage de-noising is performed to remove water-vapor features, leading to enhanced THz C- and B-scans to locate the delamination in three dimensions with high contrast.

  17. Interface shear strength and fracture behaviour of porous glass-fibre-reinforced composite implant and bone model material.

    PubMed

    Nganga, Sara; Ylä-Soininmäki, Anne; Lassila, Lippo V J; Vallittu, Pekka K

    2011-11-01

    Glass-fibre-reinforced composites (FRCs) are under current investigation to serve as durable bone substitute materials in load-bearing orthopaedic implants and bone implants in the head and neck area. The present form of biocompatible FRCs consist of non-woven E-glass-fibre tissues impregnated with varying amounts of a non-resorbable photopolymerisable bifunctional polymer resin with equal portions of both bis-phenyl-A-glycidyl dimethacrylate (BisGMA) and triethyleneglycol dimethacrylate (TEGDMA). FRCs with a total porosity of 10-70 vol% were prepared, more than 90 vol% of which being functional (open pores), and the rest closed. The pore sizes were greater than 100 μm. In the present study, the push-out test was chosen to analyse the shear strength of the interface between mechanically interlocked gypsum and a porous FRC implant structure. Gypsum was used as a substitute material for natural bone. The simulative in vitro experiments revealed a significant rise of push-out forces to the twofold level of 1147 ± 271 N for an increase in total FRC porosity of 43%. Pins, intended to model the initial mechanical implant fixation, did not affect the measured shear strength of the gypsum-FRC interface, but led to slightly more cohesive fracture modes. Fractures always occurred inside the gypsum, it having lower compressive strength than the porous FRC structures. Therefore, the largest loads were restricted by the brittleness of the gypsum. Increases of the FRC implant porosity tended to lead to more cohesive fracture modes and higher interfacial fracture toughness. Statistical differences were confirmed using the Kruskal-Wallis test. The differences between the modelled configuration showing gypsum penetration into all open pores and the real clinical situation with gradual bone ingrowth has to be considered. PMID:22098879

  18. Interface shear strength and fracture behaviour of porous glass-fibre-reinforced composite implant and bone model material.

    PubMed

    Nganga, Sara; Ylä-Soininmäki, Anne; Lassila, Lippo V J; Vallittu, Pekka K

    2011-11-01

    Glass-fibre-reinforced composites (FRCs) are under current investigation to serve as durable bone substitute materials in load-bearing orthopaedic implants and bone implants in the head and neck area. The present form of biocompatible FRCs consist of non-woven E-glass-fibre tissues impregnated with varying amounts of a non-resorbable photopolymerisable bifunctional polymer resin with equal portions of both bis-phenyl-A-glycidyl dimethacrylate (BisGMA) and triethyleneglycol dimethacrylate (TEGDMA). FRCs with a total porosity of 10-70 vol% were prepared, more than 90 vol% of which being functional (open pores), and the rest closed. The pore sizes were greater than 100 μm. In the present study, the push-out test was chosen to analyse the shear strength of the interface between mechanically interlocked gypsum and a porous FRC implant structure. Gypsum was used as a substitute material for natural bone. The simulative in vitro experiments revealed a significant rise of push-out forces to the twofold level of 1147 ± 271 N for an increase in total FRC porosity of 43%. Pins, intended to model the initial mechanical implant fixation, did not affect the measured shear strength of the gypsum-FRC interface, but led to slightly more cohesive fracture modes. Fractures always occurred inside the gypsum, it having lower compressive strength than the porous FRC structures. Therefore, the largest loads were restricted by the brittleness of the gypsum. Increases of the FRC implant porosity tended to lead to more cohesive fracture modes and higher interfacial fracture toughness. Statistical differences were confirmed using the Kruskal-Wallis test. The differences between the modelled configuration showing gypsum penetration into all open pores and the real clinical situation with gradual bone ingrowth has to be considered.

  19. Effect of Endodontic Irrigating Solutions on the Micro Push-out Bond Strength of a Fibre Glass Dowel

    PubMed Central

    Crispim da Silveira, Olimpia; Bras da Silva, Rodivan; Dametto, Fabio Roberto; Machado, Claudia Tavares; Souza dos Santos, Alex Jose

    2014-01-01

    Purpose To evaluate the effect of different endodontic irrigating solutions on the micro push-out bond strength of a fiber glass dowel. Material and Methods Seventy 16-mm long root segments of bovine incisors were prepared and randomly assigned to 7 groups (n=10) according to the type of irrigating solution used prior to the cementation of the intra-radicular fiber glass dowels: G1: 5.25% NaOCl + 17% EDTA; G2: 5.25% NaOCl; G3: 17% EDTA; G4: 2% chlorhexidine gel; G5: 70% alcohol; G6: 11.5% polyacrylic acid; and G7: saline (control). After treatment of intracanal dentin, the glass fibre dowels were cemented with self-adhesive resin cement (RelyX Unicem). Six slices with the thickness of 1.00 ± 0.05 mm were obtained from each tooth at the coronal, middle and apical root thirds (2 slices per third) using a low-speed saw. Micro push-out tests were performed at a crosshead speed of 0.5mm/min and the data (MPa) were analyzed statistically by ANOVA and Tukey’s and Dunnett’s tests. Results There were statistically significant differences (p<0.0001) among the irrigating solutions, but no significant difference (p=0.0591) was found among the root thirds. G5 presented the highest bond strength mean of all groups (p<0.0001). The use of 70% alcohol increased the adhesion values by 53% compared to the group control. Conclusion The use of 70% alcohol increased the bond strength of the fiber glass dowel to the dentin walls. However, the push-out bond strength between the dowel and the root dentin was not affected by the root third (coronal, middle and apical). PMID:27688347

  20. Effect of Endodontic Irrigating Solutions on the Micro Push-out Bond Strength of a Fibre Glass Dowel

    PubMed Central

    Crispim da Silveira, Olimpia; Bras da Silva, Rodivan; Dametto, Fabio Roberto; Machado, Claudia Tavares; Souza dos Santos, Alex Jose

    2014-01-01

    Purpose To evaluate the effect of different endodontic irrigating solutions on the micro push-out bond strength of a fiber glass dowel. Material and Methods Seventy 16-mm long root segments of bovine incisors were prepared and randomly assigned to 7 groups (n=10) according to the type of irrigating solution used prior to the cementation of the intra-radicular fiber glass dowels: G1: 5.25% NaOCl + 17% EDTA; G2: 5.25% NaOCl; G3: 17% EDTA; G4: 2% chlorhexidine gel; G5: 70% alcohol; G6: 11.5% polyacrylic acid; and G7: saline (control). After treatment of intracanal dentin, the glass fibre dowels were cemented with self-adhesive resin cement (RelyX Unicem). Six slices with the thickness of 1.00 ± 0.05 mm were obtained from each tooth at the coronal, middle and apical root thirds (2 slices per third) using a low-speed saw. Micro push-out tests were performed at a crosshead speed of 0.5mm/min and the data (MPa) were analyzed statistically by ANOVA and Tukey’s and Dunnett’s tests. Results There were statistically significant differences (p<0.0001) among the irrigating solutions, but no significant difference (p=0.0591) was found among the root thirds. G5 presented the highest bond strength mean of all groups (p<0.0001). The use of 70% alcohol increased the adhesion values by 53% compared to the group control. Conclusion The use of 70% alcohol increased the bond strength of the fiber glass dowel to the dentin walls. However, the push-out bond strength between the dowel and the root dentin was not affected by the root third (coronal, middle and apical).

  1. Ballistic phonon transport in holey silicon.

    PubMed

    Lee, Jaeho; Lim, Jongwoo; Yang, Peidong

    2015-05-13

    When the size of semiconductors is smaller than the phonon mean free path, phonons can carry heat with no internal scattering. Ballistic phonon transport has received attention for both theoretical and practical aspects because Fourier's law of heat conduction breaks down and the heat dissipation in nanoscale transistors becomes unpredictable in the ballistic regime. While recent experiments demonstrate room-temperature evidence of ballistic phonon transport in various nanomaterials, the thermal conductivity data for silicon in the length scale of 10-100 nm is still not available due to experimental challenges. Here we show ballistic phonon transport prevails in the cross-plane direction of holey silicon from 35 to 200 nm. The thermal conductivity scales linearly with the length (thickness) even though the lateral dimension (neck) is as narrow as 20 nm. We assess the impact of long-wavelength phonons and predict a transition from ballistic to diffusive regime using scaling models. Our results support strong persistence of long-wavelength phonons in nanostructures and are useful for controlling phonon transport for thermoelectrics and potential phononic applications.

  2. Holey buckets! Monitoring plot-scale runoff

    NASA Astrophysics Data System (ADS)

    Rupp, D. E.; Stewart, R. D.; Abou Najm, M. R.; Selker, J. S.; Selker, F.; Van De Giesen, N.

    2011-12-01

    Measurement of plot-scale surface runoff is commonly achieved by diverting flow through a flume or tipping bucket system, or into a storage tank, such as bucket. The principle advantages of the "bucket method" are relative simplicity and low cost. The principle drawback is that the bucket requires frequent emptying during heavy runoff, unless the bucket volume is very large. As a solution to the problem of emptying the bucket while still retaining the properties of simplicity and economy, we used a holey bucket. Our "bucket" is vertical 4"-diameter ABS pipe, sealed at the bottom, and with holes along the side of the pipe. A screen in the pipe catches debris that could block the holes. The holes' diameters and locations were chosen to capture both low (<1 L min-1) and high (>100 L min-1) flows. Runoff is diverted into the top of the pipe. The runoff rate is determined from the water level and the rate of change in water level: the water level gives the flow rate out of the submerged holes (using Torricelli's Law) and the change in water level gives the rate of change in storage in the pipe. The runoff is calculated as the sum of the hole discharge and the rate of change in storage. A calibration parameter is applied to account for departures from assumptions of the theory. The design is currently being utilized to monitor runoff from experimental plots on a rural hillslope in Chile.

  3. Searching For Planets in "Holey Debris Disks"

    NASA Astrophysics Data System (ADS)

    Meshkat, Tiffany; Bailey, Vanessa P.; Su, Kate Y. L.; Kenworthy, Matthew A.; Mamajek, Eric E.; Hinz, Philip; Smith, Paul S.

    2015-01-01

    Directly imaging planets provides a unique opportunity to study young planets in the context of their formation and evolution. It examines the underlying semi-major axis exoplanet distribution and enables the characterization of the planet itself with spectroscopic examination of its emergent flux. However, only a handful of planets have been directly imaged, and thus the stars best suited for planet imaging are still a subject of debate. The "Holey Debris Disk" project was created in order to help determine if debris disks with gaps are signposts for planets. These gaps may be dynamically caused by planets accreting the debris material as they form. We present the results from our survey with VLT/NACO and the apodized phase plate coronagraph. We demonstrate that these disks with holes are good targets for directly detecting planets with the discovery of a planet around two of our targets, HD 95086 and HD 106906, at L'-band. Our non-detection of HD 95086 b in H-band demonstrates the importance of thermal infrared observations. The detected planets shepherd the outer cool debris belt. The relatively dust-free gap in these disks implies the presence of one or more closer-in planets. We discuss our new constraints on planets around other targets in our survey as well as disk properties of these targets and describe how future instruments will find the inner planets.

  4. Fibre-matrix bond strength studies of glass, ceramic, and metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grande, D. H.; Mandell, J. F.; Hong, K. C. C.

    1988-01-01

    An indentation test technique for compressively loading the ends of individual fibers to produce debonding has been applied to metal, glass, and glass-ceramic matrix composites; bond strength values at debond initiation are calculated using a finite-element model. Results are correlated with composite longitudinal and interlaminar shear behavior for carbon and Nicalon fiber-reinforced glasses and glass-ceramics including the effects of matrix modifications, processing conditions, and high-temperature oxidation embrittlement. The data indicate that significant bonding to improve off-axis and shear properties can be tolerated before the longitudinal behavior becomes brittle. Residual stress and other mechanical bonding effects are important, but improved analyses and multiaxial interfacial failure criteria are needed to adequately interpret bond strength data in terms of composite performance.

  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. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Spun microstructured optical fibresfor Faraday effect current sensors

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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 ~70% that of an ideal fibre, in good agreement with theoretical predictions.

  7. Up-conversion luminescence in germanate glass and double-clad optical fibre co-doped with Yb3+/Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Kochanowicz, M.; Zmojda, J.; Ragin, T.; Miluski, P.; Jelen, P.

    2016-09-01

    In the paper the analysis of up-conversion (UC) luminescence in 0.5Yb2O3/(0.25-1)Eu2O3 (mol.%) co-doped germanate glass and optical fibre has been investigated. Up-conversion emission of bands at 591, 616, 652, 701 nm to which correspond Eu3+: 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, 5D0 → 7F4 transitions, respectively was obtained as a result of cooperative energy transfer between Yb3+ and Eu3+ ions. The highest up-conversion emission (Yb3+ → Eu3+ energy transfer efficiency η = 24%) was obtained in 0.5Yb2O3/0.75Eu2O3 co-doped glass. Comparison of up-conversion and down-conversion luminescence spectra of bulk glass, glass fibre and different length double-clad optical fibre (up to 5 m) showed subtle differences in shape of the spectrum. In comparison to down - conversion emission (λexc = 405 nm) main UC luminescence band is red-shifted by 2 nm and is characterized by 5 nm greater full - width half - maximum (FWHM).

  8. Bulk preparation of holey graphene via controlled catalytic oxidation

    NASA Astrophysics Data System (ADS)

    Lin, Yi; Watson, Kent A.; Kim, Jae-Woo; Baggett, David W.; Working, Dennis C.; Connell, John W.

    2013-08-01

    Structural manipulation of the two dimensional graphene surface has been of significant interest as a means of tuning the properties of the nanosheets for enhanced performance in various applications. In this report, a straightforward and highly scalable method is presented to prepare bulk quantities of ``holey graphenes'', which are graphene sheets with holes ranging from a few to tens of nm in average diameter. The approach to their preparation takes advantage of the catalytic properties of silver (Ag) nanoparticles toward the air oxidation of graphitic carbon. In the procedure, Ag nanoparticles were first deposited onto the graphene sheet surface in a facile, controllable, and solvent-free process. The catalyst-loaded graphene samples were then subjected to thermal treatment in air. The graphitic carbons in contact with the Ag nanoparticles were selectively oxidized into gaseous byproducts, such as CO or CO2, leaving holes in the graphene surface. The Ag was then removed by refluxing in diluted nitric acid to obtain the final holey graphene products. The average size of the holes on the graphene was found to correlate with the size of the Ag nanoparticles, which could be controlled by adjusting the silver precursor concentration. In addition, the temperature and time of the air oxidation step, and the catalyst removal treatment conditions were found to strongly affect the morphology of the holes. Characterization results of the holey graphene products suggested that the hole generation might have started from defect-rich regions present on the starting graphene sheets. As a result, the remaining graphitic carbon structures on the holey graphene sheets were highly crystalline, with no significant increase of the overall defect density despite the presence of structural holes. Preliminary experiments are also presented on the use of holey graphene sheets as fillers for polymeric composites. The results indicated that these sheets might be better reinforcing

  9. Antimicrobial activity of submicron glass fibres incorporated as a filler to a dental sealer.

    PubMed

    Esteban-Tejeda, L; Cabal, B; Torrecillas, R; Prado, C; Fernandez-Garcia, E; López-Piriz, R; Quintero, F; Pou, J; Penide, J; Moya, J S

    2016-01-01

    Two types of antimicrobial glass fibers containing ZnO and CaO, with diameters ranging from tens of nanometers to 1 µm, were successfully fabricated by a laser spinning technique. The antimicrobial performance was corroborated according to ISO 20743:2013, by using gram-negative (Escherichia coli) and gram-positive (Streptococcus oralis, Streptococcus mutans and Staphylococcus aureus) bacteria, and yeast (Candida krusei) (more than 3 logs of reduction). The metabolic activity and endosomal system of eukaryotic cells were not altered by using eluents of CaO glass submicrometric fibers and ZnO fibers at 1 : 10 dilution as cellular media (viability rates over 70%). A dental material was functionalized by embedding ZnO nanofibers above the percolation threshold (20% wt), creating a three-dimensional (3D) fiber network that added an antimicrobial profile. This new ZnO glass fiber composite is proved non-cytotoxic and preserved the antimicrobial effect after immersion in human saliva. This is the first time that a fiber-reinforced liner with strong antimicrobial-activity has been created to prevent secondary caries. The potential of developing new fiber-reinforced composites (FRCs) with antimicrobial properties opens up an extensive field of dental applications where most important diseases have an infectious origin. PMID:27509353

  10. Combined technique with glass-fibre-reinforced composite post and original fragment in restoration of traumatized anterior teeth--a case report.

    PubMed

    Altun, Ceyhan; Guven, Gunseli

    2008-12-01

    Dentoalveolar trauma is frequently encountered by dental practitioners. In some instances, saving a child's traumatized permanent teeth can create difficulties for the child, the parents and the dentist. Reattachment of a crown fragment is a conservative treatment that should be considered for crown fractures of anterior teeth. This case describes the clinical reattachment of an original tooth fragment. A 10-year-old male presented at the Department of Pediatric Dentistry with a complex crown fracture of the left maxillary central incisor 1 day after the trauma occurred. Following endodontic treatment, a glass-fibre-reinforced composite root canal post (FRC Postec; Ivoclar Vivadent AG, Schaan, Liechtenstein) was inserted to increase retention and distribute stress along the root. The dental restoration was completed using the original fragment and a dual-cured resin composite (Variolink II; Ivoclar Vivadent AG). Clinical and radiographic examinations at 1-year recall showed the glass-fibre-reinforced composite root canal post and restoration to be in place, indicating the success of the treatment in maintaining the fractured tooth. Thus, we conclude that reattachment of a tooth fragment using a dual-cured resin composite and a glass-fibre-reinforced composite root canal post is an alternative method for the rehabilitation of fractured teeth that offers satisfactory aesthetic and functional outcomes.

  11. Bone attachment to glass-fibre-reinforced composite implant with porous surface.

    PubMed

    Mattila, R H; Laurila, P; Rekola, J; Gunn, J; Lassila, L V J; Mäntylä, T; Aho, A J; Vallittu, P K

    2009-06-01

    A method has recently been developed for producing fibre-reinforced composites (FRC) with porous surfaces, intended for use as load-bearing orthopaedic implants. This study focuses on evaluation of the bone-bonding behaviour of FRC implants. Three types of cylindrical implants, i.e. FRC implants with a porous surface, solid polymethyl methacrylate (PMMA) implants and titanium (Ti) implants, were inserted in a transverse direction into the intercondular trabeculous bone area of distal femurs and proximal tibias of New Zealand White rabbits. Animals were sacrificed at 3, 6 and 12 weeks post operation, and push-out tests (n=5-6 per implant type per time point) were then carried out. At 12 weeks the shear force at the porous FRC-bone interface was significantly higher (283.3+/-55.3N) than the shear force at interfaces of solid PMMA/bone (14.4+/-11.0 N; p<0.001) and Ti/bone (130.6+/-22.2N; p=0.001). Histological observation revealed new bone growth into the porous surface structure of FRC implants. Solid PMMA and Ti implants were encapsulated mostly with fibrous connective tissue. Finite element analysis (FEA) revealed that porous FRC implants had mechanical properties which could be tailored to smooth the shear stress distribution at the bone-implant interface and reduce the stress-shielding effect. PMID:19268643

  12. Prediction of Damage Factor in end Milling of Glass Fibre Reinforced Plastic Composites Using Artificial Neural Network

    NASA Astrophysics Data System (ADS)

    Erkan, Ömer; Işık, Birhan; Çiçek, Adem; Kara, Fuat

    2013-08-01

    Glass fibre reinforced plastic (GFRP) composites are an economic alternative to engineering materials because of their superior properties. Some damages on the surface occur due to their complex cutting mechanics in cutting process. Minimisation of the damages is fairly important in terms of product quality. In this study, a GFRP composite material was milled to experimentally minimise the damages on the machined surfaces, using two, three and four flute end mills at different combinations of cutting parameters. Experimental results showed that the damage factor increased with increasing cutting speed and feed rate, on the other hand, it was found that the damage factor decreased with increasing depth of cut and number of the flutes. In addition, analysis of variance (ANOVA) results clearly revealed that the feed rate was the most influential parameter affecting the damage factor in end milling of GFRP composites. Also, in present study, Artificial Neural Network (ANN) models with five learning algorithms were used in predicting the damage factor to reduce number of expensive and time-consuming experiments. The highest performance was obtained by 4-10-1 network structure with LM learning algorithm. ANN was notably successful in predicting the damage factor due to higher R2 and lower RMSE and MEP.

  13. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    NASA Astrophysics Data System (ADS)

    Kruszka, Leopold; Moćko, Wojciech; Fenu, Luigi; Cadoni, Ezio

    2015-09-01

    Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  14. Interfibre Failure Characterisation of Unidirectional and Triax Glass Fibre Non-Crimp Fabric Reinforced Epoxy Laminates

    NASA Astrophysics Data System (ADS)

    Laustsen, S.; Lund, E.; Kühlmeier, L.; Thomsen, O. T.

    2015-02-01

    The in-plane failure envelopes of unidirectional (UD) laminae in a UD and a Triax (0°, ±45°) laminate configuration have been investigated. The two laminate configurations have been characterised by testing off-axis specimens in uniaxial tension and compression at different angles relative to the fibre direction and further by Iosipescu shear tests. Strain gauge and Digital Image Correlation (DIC) measurements were used to measure the deformation states during loading, and to record the stress-strain responses to identify the initiation of failure and investigate the heterogeneity of the material and possible parasitic effects. A novel analysis methodology to determine the so-called `failure initiation strength' based on the second derivative of the stresses with respect to the strains has been adopted. The experimentally determined `failure initiation stresses' were compared with predictions from the commonly applied Maximum Stress, Tsai-Wu, and Puck failure criteria. From this work, a thorough comparison of the UD and Triax failure envelopes has been facilitated. It is shown that failure prediction for the Triax laminate based on the failure envelope derived from UD lamina tests may be too conservative in comparison with fitting a failure criterion directly to the Triax laminate test data. The latter approach implies that the Triax laminate is considered as a single lamina with homogenised properties, which in principle violates the theoretical background of the considered failure criteria, since these are established to predict failure for a UD lamina. However, the simple homogenisation is shown to be a useful design oriented approach for providing a simple estimation of the onset of failure in laminate configurations composed of e.g., multiple layers of Triax. Thus, a reliable and efficient approach is offered for the structural integrity assessment, which takes the non-crimp fabric configurations directly or `as delivered' into account.

  15. Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

    NASA Technical Reports Server (NTRS)

    Watson, Kent (Inventor); Lin, Yi (Inventor); Ghose, Sayata (Inventor); Connell, John (Inventor)

    2015-01-01

    A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO.sub.2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

  16. Holey graphene frameworks for highly efficient capacitive energy storage

    NASA Astrophysics Data System (ADS)

    Xu, Yuxi; Lin, Zhaoyang; Zhong, Xing; Huang, Xiaoqing; Weiss, Nathan O.; Huang, Yu; Duan, Xiangfeng

    2014-08-01

    Supercapacitors represent an important strategy for electrochemical energy storage, but are usually limited by relatively low energy density. Here we report a three-dimensional holey graphene framework with a hierarchical porous structure as a high-performance binder-free supercapacitor electrode. With large ion-accessible surface area, efficient electron and ion transport pathways as well as a high packing density, the holey graphene framework electrode can deliver a gravimetric capacitance of 298 F g-1 and a volumetric capacitance of 212 F cm-3 in organic electrolyte. Furthermore, we show that a fully packaged device stack can deliver gravimetric and volumetric energy densities of 35 Wh kg-1 and 49 Wh l-1, respectively, approaching those of lead acid batteries. The achievement of such high energy density bridges the gap between traditional supercapacitors and batteries, and can open up exciting opportunities for mobile power supply in diverse applications.

  17. Toward Edge-Defined Holey Boron Nitride Nanosheets

    NASA Technical Reports Server (NTRS)

    Lin, Yi; Liao, Yunlong; Chen, Zhongfan; Connell, John W.

    2015-01-01

    "Holey" two-dimensional (2D) nanosheets with well-defined holy morphology and edge chemistry are highly desirable for applications such as energy storage, catalysis, sensing, transistors, and molecular transport/separation. For example, holey grapheme is currently under extensive investigation for energy storage applications because of the improvement in ion transport due to through the thickness pathways provided by the holes. Without the holes, the 2D materials have significant limitations for such applications in which efficient ion transport is important. As part of an effort to apply this approach to other 2D nanomaterials, a method to etch geometrically defined pits or holes on the basal plane surface of hexagonal boron nitride (h-BN) nanosheets has been developed. The etching, conducted via heating in ambient air using metal nanoparticles as catalysts, was facile, controllable, and scalable. Starting h-BN layered crystals were etched and subsequently exfoliated into boron nitride nanosheets (BNNSs). The as-etched and exfoliated h-BN nanosheets possessed defined pit and hole shapes that were comprised of regulated nanostructures at the edges. The current finding are the first step toward the bulk preparation of holey BNNSs with defined holes and edges.

  18. Bulk preparation of holey graphene via controlled catalytic oxidation.

    PubMed

    Lin, Yi; Watson, Kent A; Kim, Jae-Woo; Baggett, David W; Working, Dennis C; Connell, John W

    2013-09-01

    Structural manipulation of the two dimensional graphene surface has been of significant interest as a means of tuning the properties of the nanosheets for enhanced performance in various applications. In this report, a straightforward and highly scalable method is presented to prepare bulk quantities of "holey graphenes", which are graphene sheets with holes ranging from a few to tens of nm in average diameter. The approach to their preparation takes advantage of the catalytic properties of silver (Ag) nanoparticles toward the air oxidation of graphitic carbon. In the procedure, Ag nanoparticles were first deposited onto the graphene sheet surface in a facile, controllable, and solvent-free process. The catalyst-loaded graphene samples were then subjected to thermal treatment in air. The graphitic carbons in contact with the Ag nanoparticles were selectively oxidized into gaseous byproducts, such as CO or CO2, leaving holes in the graphene surface. The Ag was then removed by refluxing in diluted nitric acid to obtain the final holey graphene products. The average size of the holes on the graphene was found to correlate with the size of the Ag nanoparticles, which could be controlled by adjusting the silver precursor concentration. In addition, the temperature and time of the air oxidation step, and the catalyst removal treatment conditions were found to strongly affect the morphology of the holes. Characterization results of the holey graphene products suggested that the hole generation might have started from defect-rich regions present on the starting graphene sheets. As a result, the remaining graphitic carbon structures on the holey graphene sheets were highly crystalline, with no significant increase of the overall defect density despite the presence of structural holes. Preliminary experiments are also presented on the use of holey graphene sheets as fillers for polymeric composites. The results indicated that these sheets might be better reinforcing fillers

  19. 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.

  20. 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.

  1. 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.

  2. Green up-conversion in Yb 3+-Tb 3+ and Yb 3+-Tm 3+-Tb 3+ doped fluoro-germanate bulk glass and fibre

    NASA Astrophysics Data System (ADS)

    Scarnera, V.; Richards, B.; Jha, A.; Jose, G.; Stacey, C.

    2010-12-01

    Yb 3+-Tb 3+ and Yb 3+-Tm 3+-Tb 3+ doped fluoro-germanate glass samples were fabricated in bulk and fibre form. Bright up-conversion has been obtained by exciting the samples with a 975 nm laser source, and the power dependence of the up-conversion intensities with respect to the excitation power has been characterised. Two mechanisms must be taken into account to explain the population of the 5D 4 level of the terbium ions in these experiments; namely multi excited state absorption (MESA) and cooperative up-conversion (CU). While in the Yb 3+-Tm 3+-Tb 3+ samples both MESA and CU contribute simultaneously to the 5D 4:Tb 3+ population, in the Yb 3+-Tb 3+ case a pure CU mechanism is responsible for the 5D 4:Tb 3+ population. In the fibre geometry, the re-absorption effect has been observed. The detrimental role of the re-absorption has been explained by characterising the up-conversion spectrum at different fibre lengths.

  3. Holey Graphene as a Weed Barrier for Molecules.

    PubMed

    Gethers, Matthew L; Thomas, John C; Jiang, Shan; Weiss, Nathan O; Duan, Xiangfang; Goddard, William A; Weiss, Paul S

    2015-11-24

    We demonstrate the use of "holey" graphene as a mask against molecular adsorption. Prepared porous graphene is transferred onto a Au{111} substrate, annealed, and then exposed to dilute solutions of 1-adamantanethiol. In the pores of the graphene lattice, we find islands of organized, self-assembled molecules. The bare Au in the pores can be regenerated by postdeposition annealing, and new molecules can be self-assembled in the exposed Au region. Graphene can serve as a robust, patternable mask against the deposition of self-assembled monolayers. PMID:26426746

  4. Holey Graphene as a Weed Barrier for Molecules.

    PubMed

    Gethers, Matthew L; Thomas, John C; Jiang, Shan; Weiss, Nathan O; Duan, Xiangfang; Goddard, William A; Weiss, Paul S

    2015-11-24

    We demonstrate the use of "holey" graphene as a mask against molecular adsorption. Prepared porous graphene is transferred onto a Au{111} substrate, annealed, and then exposed to dilute solutions of 1-adamantanethiol. In the pores of the graphene lattice, we find islands of organized, self-assembled molecules. The bare Au in the pores can be regenerated by postdeposition annealing, and new molecules can be self-assembled in the exposed Au region. Graphene can serve as a robust, patternable mask against the deposition of self-assembled monolayers.

  5. Quasi-static Load Sharing Model in the Case of Moulded Glass Fibre Reinforced Polyamide 6 Gears

    NASA Astrophysics Data System (ADS)

    Cathelin, Julien; Guingand, Michèle; de Vaujany, Jean-Pierre; Chazeau, Laurent; Adrien, Jérôme

    2015-08-01

    This paper presents a fast and efficient computational method to predict the mechanical behaviour of plastic cylindrical gears made of fibre reinforced polyamide 6. Based on this method, an investigation on the relation between the fibre orientation and the gear behaviour is done. The numerical method uses a viscoelastic model accounting for the temperature, humidity and rotational speed dependence of the gear. This model is developed under the assumption that the material is stressed in its linear domain. The method is performed in three steps: the first one consists of defining the fibre orientation from simulation and experimental results. The second step characterises the viscoelastic behaviour of the material. The third step consists in calculating the load sharing with local meshing, which integrates the viscoelastic model over the entire surface of the tooth. This model permits computation of the load sharing between instantaneously engaged teeth and provides results such as contact pressure, tooth root stress and transmission error. Three fibre orientation models with an increasing complexity are compared. Simulation results show a limited influence of the fibre orientation on the contact pressure and tooth root stress, nevertheless difference up to 10 % are observed on the transmission error amplitude.

  6. Review of doped silica glass optical fibre: their TL properties and potential applications in radiation therapy dosimetry.

    PubMed

    Bradley, D A; Hugtenburg, R P; Nisbet, A; Abdul Rahman, Ahmad Taufek; Issa, Fatma; Mohd Noor, Noramaliza; Alalawi, Amani

    2012-12-01

    Review is made of dosimetric studies of Ge-doped SiO(2) telecommunication fibre as a 1-D thermoluminescence (TL) system for therapeutic applications. To-date, the response of these fibres has been investigated for UV sources, superficial X-ray beam therapy facilities, a synchrotron microbeam facility, electron linear accelerators, protons, neutrons and alpha particles, covering the energy range from a few eV to several MeV. Dosimetric characteristics include, reproducibility, fading, dose response, reciprocity between TL yield and dose-rate and energy dependence. The fibres produce a flat response to fixed photon and electron doses to within better than 3% of the mean TL distribution. Irradiated Ge-doped SiO(2) optical fibres show limited signal fading, with an average loss of TL signal of ~0.4% per day. In terms of dose response, Ge-doped SiO(2) optical fibres have been shown to provide linearity to x and electron doses, from a fraction of 1 Gy up to 2 kGy. The dosimeters have also been used in measuring photoelectron generation from iodinated contrast media; TL yields being some 60% greater in the presence of iodine than in its absence. The review is accompanied by previously unpublished data.

  7. 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)

  8. An Evaluation of Fracture Strength of Zirconium Oxide Posts Fabricated Using CAD-CAM Technology Compared with Prefabricated Glass Fibre Posts.

    PubMed

    Dayalan, Malathi; Jairaj, Abhishek; Nagaraj, K R; Savadi, Ravindra C

    2010-12-01

    Post and core therapy is regarded as the treatment of choice for restoring severely damaged endodontically treated teeth. Critical control of endodontic materials in the coronal third of the canal and pulp chamber is essential in order to maintain its colour and translucency. In addition to this, the duplication of the optical characteristics of an intact tooth, including shade translucency and fluorescence is often made difficult by the use of metal infrastructures. As a result of this tooth colored posts have gained popularity especially in aesthetic areas. Besides aesthetics, the post is also responsible for transmitting the occlusal forces to the remaining tooth structure making the mechanical properties of the post critical. However, there is no clear consensus regarding an ideal system as far as strength of the post is concerned. Hence this study aims to analyses and compares the fracture strength of traditional prefabricated glass fibre posts with zirconium oxide posts constructed using CAD CAM technology. PMID:22131666

  9. Sea Water Ageing of Composites for Ocean Energy Conversion Systems: Influence of Glass Fibre Type on Static Behaviour

    NASA Astrophysics Data System (ADS)

    Boisseau, Amélie; Davies, Peter; Thiebaud, Frédéric

    2012-06-01

    Composite material components will be an essential part of ocean energy recovery devices, and their long term durability in sea water must be guaranteed. Despite extensive experience for boat structures and wind turbines few data exist to design structures subjected to a combination of mechanical loads and sea water immersion. This paper presents the first results from an experimental study, performed jointly with fibre manufacturers, and a resin supplier, to fill this gap. The experimental study is completed by numerical modelling to simulate the coupling between water absorption and mechanical behaviour. Sea water ageing is shown to result in a drop in quasi-static mechanical properties and a change in flexural mode from compression to tension at longer ageing times, which is consistent with results from the numerical simulations.

  10. Broad spectral range measurement of chromatic dispersion of polarization modes in holey fibers using spectral interferometry

    NASA Astrophysics Data System (ADS)

    Hlubina, P.; Ciprian, D.; Martynkien, T.; Mergo, P.; Urbańczyk, W.

    2011-05-01

    Chromatic dispersion of polarization modes in holey fibers is measured over a broad spectral range (e.g. 500-1600 nm) using two white-light spectral interferometric techniques. First, a technique employing an unbalanced Mach-Zehnder interferometer with a fiber in the test arm is used to measure the wavelength dependence of the differential group effective index, or equivalently the chromatic dispersion of one polarization mode supported by the fiber. Second, a technique employing a tandem configuration of a Michelson interferometer and the optical fiber under test is used to measure the group modal birefringence in the fiber. From these measurements, the chromatic dispersion of the other polarization mode supported by the fiber is retrieved. We measured by these techniques the chromatic dispersion of polarization modes in four air-silica holey fibers and revealed the dependence of zero-dispersion wavelength on the geometry of the holey fiber.

  11. Effect of Matrix Modification on Interlaminar Shear Strength of Glass Fibre Reinforced Epoxy Composites at Cryogenic Temperature

    NASA Astrophysics Data System (ADS)

    Wu, Zhixiong; Li, Jingwen; Huang, Chuanjun; Li, Laifeng

    In order to investigate the effect of the matrix variability on the interlaminar shear strength (ILSS) of glass fiber reinforced composites at 77K, three kinds of modifiers were employed to diethyl toluene diamine (DETD) cured diglycidyl ether of bisphenol F (DGEBF) epoxy resin system. The woven glass fiber reinforced composites were fabricated by vacuum pressure impregnation (VPI). The ILSS at 77 K was studied and the results indicated that introduction of modifiers used in this study can enhance the ILSS of composite at 77 K. A maximum of 14.87% increase was obtained by addition of 10 wt% IPBE into the epoxy matrix. Furthermore, scanning electron microscopy (SEM) was used to investigate the fracture mechanism and strengthening effect.

  12. Polarization splitter based on dual core liquid crystal-filled holey fiber

    NASA Astrophysics Data System (ADS)

    Wang, Er-Lei; Jiang, Hai-Ming; Xie, Kang; Chen, Chun; Hu, Zhi-Jia

    2016-09-01

    Through filling the liquid crystal into the air holes of a dual-core holey fiber with a simple structure, the transmission mechanism of the fiber is changed from total internal reflection to photonic bandgap (PBG), and a polarization splitter based on the liquid crystal-filled dual-core PBG holey fiber is investigated. The results demonstrate that, by setting appropriate geometrical parameters, the polarization splitter possesses a short length of 890.5 μm, and its wide bandwidth of ˜150 nm almost covers all the S, C, and L communication bands. Besides, it has an excellent electro-interference-resistance property and certain sensitivity to temperature.

  13. In Vitro and In Vivo Evaluations of Nano-Hydroxyapatite/Polyamide 66/Glass Fibre (n-HA/PA66/GF) as a Novel Bioactive Bone Screw

    PubMed Central

    Su, Bao; Peng, Xiaohua; Jiang, Dianming; Wu, Jun; Qiao, Bo; Li, Weichao; Qi, Xiaotong

    2013-01-01

    In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications. PMID:23861888

  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. Holey tungsten oxynitride nanowires: novel anodes efficiently integrate microbial chemical energy conversion and electrochemical energy storage.

    PubMed

    Yu, Minghao; Han, Yi; Cheng, Xinyu; Hu, Le; Zeng, Yinxiang; Chen, Meiqiong; Cheng, Faliang; Lu, Xihong; Tong, Yexiang

    2015-05-20

    Holey tungsten oxynitride nanowires with superior conductivity, good biocompatibility, and good stability achieve excellent performance as anodes for both asymmetric supercapacitors and microbial fuel cells. Moreover, an innovative system is devised based on these as-prepared tungsten oxynitride anodes, which can simultaneously realize both energy conversion from chemical to electric energy and its storage. PMID:25854325

  16. Hole-y Debris Disks, Batman! Where are the planets?

    NASA Astrophysics Data System (ADS)

    Bailey, V.; Meshkat, T.; Hinz, P.; Kenworthy, M.; Su, K. Y. L.

    2014-03-01

    Giant planets at wide separations are rare and direct imaging surveys are resource-intensive, so a cheaper marker for the presence of giant planets is desirable. One intriguing possibility is to use the effect of planets on their host stars' debris disks. Theoretical studies indicate giant planets can gravitationally carve sharp boundaries and gaps in their disks; this has been seen for HR 8799, β Pic, and tentatively for HD 95086 (Su et al. 2009, Lagrange et al. 2010, Moor et al. 2013). If more broadly demonstrated, this link could help guide target selection for next generation direct imaging surveys. Using Spitzer MIPS/IRS spectral energy distributions (SEDs), we identify several dozen systems with two-component and/or large inner cavity disks (aka Hole-y Debris Disks). With LBT/LBTI, VLT/NaCo, GeminiS/NICI, MMT/Clio and Magellan/Clio, we survey a subset these SEDselected targets (~20). In contrast to previous disk-selected planet surveys (e.g.: Janson et al. 2013, Wahhaj et al. 2013) we image primarily in the thermal IR (L'-band), where planet-to-star contrast is more favorable and background contaminants less numerous. Thus far, two of our survey targets host planet-mass companions, both of which were discovered in L'-band after they were unrecognized or undetectable in H-band. For each system in our sample set, we will investigate whether the known companions and/or companions below our detection threshold could be responsible for the disk architecture. Ultimately, we will increase our effective sample size by incorporating detection limits from surveys that have independently targeted some of our systems of interest. In this way we will refine the conditions under which disk SED-based target selection is likely to be useful and valid.

  17. High-Nonlinearity Dispersion-Shifted Lead-Silicate Holey Fibers for Efficient 1-µm Pumped Supercontinuum Generation

    NASA Astrophysics Data System (ADS)

    Leong, J. Y. Y.; Petropoulos, P.; Price, J. H. V.; Ebendorff-Heidepriem, Heike; Asimakis, S.; Moore, R. C.; Frampton, K. E.; Finazzi, V.; Feng, X.; Monro, T. M.; Richardson, D. J.

    2006-01-01

    This paper reports on the recent progress in the design and fabrication of high-nonlinearity lead-silicate holey fibers (HFs). First, the fabrication of a fiber designed to offer close to the maximum possible nonlinearity per unit length in this glass type is described. A value of gamma = 1860 W-1 · km-1 at a wavelength of 1.55 µm is achieved, which is believed to be a record for any fiber at this wavelength. Second, the design and fabrication of a fiber with a slightly reduced nonlinearity but with dispersion-shifted characteristics tailored to enhance broadband supercontinuum (SC) generation when pumped at a wavelength of 1.06 µm-a wavelength readily generated using Yb-doped fiber lasers-are described. SC generation spanning more than 1000 nm is observed for modest pulse energies of sim 100 pJ using a short length of this fiber. Finally, the results of numerical simulations of the SC process in the proposed fibers are presented, which are in good agreement with the experimental observations and highlight the importance of accurate control of the zero-dispersion wavelength (ZDW) when optimizing such fibers for SC performance.

  18. Holey carbon micro-arrays for transmission electron microscopy: a microcontact printing approach.

    PubMed

    Chester, David W; Klemic, James F; Stern, Eric; Sigworth, Fred J; Klemic, Kathryn G

    2007-08-01

    We have used a microcontact printing approach to produce high quality and inexpensive holey carbon micro-arrays. Fabrication involves: (1) micromolding a poly(dimethylsiloxane) (PDMS) elastomer stamp from a microfabricated master that contains the desired array pattern; (2) using the PDMS stamp for microcontact printing a thin sacrificial plastic film that contains an array of holes; (3) floating the plastic film onto TEM grids; (4) evaporating carbon onto the plastic film and (5) removing the sacrificial plastic film. The final holey carbon micro-arrays are ready for use as support films in TEM applications with the fidelity of the original microfabricated pattern. This approach is cost effective as both the master and the stamps have long-term reusability. Arbitrary array patterns can be made with microfabricated masters made through a single-step photolithographic process.

  19. Self-assembled monolayers improve protein distribution on holey carbon cryo-EM supports

    PubMed Central

    Meyerson, Joel R.; Rao, Prashant; Kumar, Janesh; Chittori, Sagar; Banerjee, Soojay; Pierson, Jason; Mayer, Mark L.; Subramaniam, Sriram

    2014-01-01

    Poor partitioning of macromolecules into the holes of holey carbon support grids frequently limits structural determination by single particle cryo-electron microscopy (cryo-EM). Here, we present a method to deposit, on gold-coated carbon grids, a self-assembled monolayer whose surface properties can be controlled by chemical modification. We demonstrate the utility of this approach to drive partitioning of ionotropic glutamate receptors into the holes, thereby enabling 3D structural analysis using cryo-EM methods. PMID:25403871

  20. Simultaneous Thermoelectric Property Measurement and Incoherent Phonon Transport in Holey Silicon.

    PubMed

    Lim, Jongwoo; Wang, Hung-Ta; Tang, Jinyao; Andrews, Sean C; So, Hongyun; Lee, Jaeho; Lee, Dong Hyun; Russell, Thomas P; Yang, Peidong

    2016-01-26

    Block copolymer patterned holey silicon (HS) was successfully integrated into a microdevice for simultaneous measurements of Seebeck coefficient, electrical conductivity, and thermal conductivity of the same HS microribbon. These fully integrated HS microdevices provided excellent platforms for the systematic investigation of thermoelectric transport properties tailored by the dimensions of the periodic hole array, that is, neck and pitch size, and the doping concentrations. Specifically, thermoelectric transport properties of HS with a neck size in the range of 16-34 nm and a fixed pitch size of 60 nm were characterized, and a clear neck size dependency was shown in the doping range of 3.1 × 10(18) to 6.5 × 10(19) cm(-3). At 300 K, thermal conductivity as low as 1.8 ± 0.2 W/mK was found in HS with a neck size of 16 nm, while optimized zT values were shown in HS with a neck size of 24 nm. The controllable effects of holey array dimensions and doping concentrations on HS thermoelectric performance could aid in improving the understanding of the phonon scattering process in a holey structure and also in facilitating the development of silicon-based thermoelectric devices.

  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. Fibres, Blood and Broken Glass

    ERIC Educational Resources Information Center

    Tomlinson, Bob; Peacock, Alan

    2005-01-01

    Crime Scene Investigators (CSIs) are the bridge between the police and forensic science specialists. Their job is to recover physical evidence from the scene of a crime, and try to make sense of it to interpret and explain what probably happened--which is just what scientists also do. They recover many things: objects, photographs of the crime…

  3. 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

  4. Holey graphene/polypyrrole nanoparticle hybrid aerogels with three-dimensional hierarchical porous structure for high performance supercapacitor

    NASA Astrophysics Data System (ADS)

    He, Yibo; Bai, Yonglong; Yang, Xiaofan; Zhang, Jinyang; Kang, Liping; Xu, Hua; Shi, Feng; Lei, Zhibin; Liu, Zong-Huai

    2016-06-01

    Holey graphene/polypyrrole hybrid aerogels (HGPAs) with three-dimensional (3D) hierarchical structure have been fabricated by freeze-drying holey graphene/polypyrrole hydrogels, which are assembled by using holey graphene (HG) nanosheets and polypyrrole (PPy) nanoparticles as assembling primitives. The as-prepared HGPAs materials show an interconnected and stable 3D porous network, and PPy nanoparticles uniformly embedded in the aerogel prevent the restacking of holey graphene (HG) nanosheets. The unique hierarchical porous structure and synergistic effect between PPy nanoparticles and HG nanosheets make HGPA hybrid aerogel electrode with a mass ratio of PPy/HGO = 0.75 exhibits high specific capacitance (418 F g-1) at a current density of 0.5 A g-1, extremely outstanding rate capability (80%) at various current densities from 0.5 to 20 A g-1 and good cycling performance (74%) after 2000 cycles in 1.0 M KOH aqueous electrolyte. Moreover, the effect of the PPy nanoparticle sizes in HGPAs on their electrochemical properties is also investigated, and PPy nanoparticles with relatively larger sizes are favorable of the good capacitive performance for the obtained electrodes. The facile and efficient preparation method for HGPAs electrodes may be developed for preparing other holey graphene-based hybrid aerogels with structure-controllable nanostructures.

  5. Measurement of chromatic dispersion of polarization modes in holey fibers by white-light spectral interferometric techniques

    NASA Astrophysics Data System (ADS)

    Kadulová, M.; Hlubina, P.; Ciprian, D.; Martynkien, T.; Mergo, P.; Urbańczyk, W.

    2011-05-01

    We present two white-light spectral interferometric techniques for measurement of the chromatic dispersion of polarization modes in holey fibers over a broad spectral range (e.g. 500-1600 nm). First, a technique employing an unbalanced Mach-Zehnder interferometer with a fiber in the test arm is used to measure the wavelength dependence of the differential group effective index, or equivalently the chromatic dispersion of one polarization mode supported by the fiber. Second, a technique employing a tandem configuration of a Michelson interferometer and the optical fiber under test is used to measure the group modal birefringence in the fiber. From these measurements, the chromatic dispersion of the other polarization mode supported by the fiber is retrieved. We measured by these techniques the chromatic dispersion of polarization modes in three air-silica holey fibers and revealed the dependence of zero-dispersion wavelength on the geometry of the holey fiber.

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

    PubMed

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

    2013-12-16

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

  7. 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

  8. Highly efficient Raman distributed feedback fibre lasers.

    PubMed

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

    2012-02-27

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

  9. Holey Au-Ag alloy nanoplates with built-in hotspots for surface-enhanced Raman scattering.

    PubMed

    Wei, Xinyu; Fan, Qikui; Liu, Hongpo; Bai, Yaocai; Zhang, Lei; Zheng, Haoquan; Yin, Yadong; Gao, Chuanbo

    2016-08-25

    Plasmonic noble metal nanocrystals with interior nanogaps have attracted great attention in surface-enhanced Raman scattering (SERS) applications due to the presence of built-in hotspots. Herein, we report a synthesis route to holey Au-Ag alloy nanoplates by controlled galvanic replacement with Ag nanoplates as the sacrificial template, a sulfite-coordinated Au(i) salt as the Au source, and polyvinylpyrrolidone (PVP) as the capping agent. PVP helps regulate the anisotropic growth of nanopores on the Ag nanoplates to afford a highly holey nanostructure, and the monovalent Au(i) salt plays a critical role in stabilizing these holey nanoplates by rapidly enriching Au in the alloy nanostructures. Numerical simulations and experimental results suggest that these holey Au-Ag alloy nanoplates possess enormous internal hotspots for high sensitivity in the SERS analysis, and high stability for excellent reliability of the analysis under many harsh conditions. We believe that this strategy is potentially applicable to the synthesis of many other types of plasmonic nanostructures with inherent nanogaps for many sensing and imaging applications. PMID:27524663

  10. Holey graphene frameworks for highly selective post-combustion carbon capture

    NASA Astrophysics Data System (ADS)

    Chowdhury, Shamik; Balasubramanian, Rajasekhar

    2016-02-01

    Atmospheric CO2 concentrations continue to rise rapidly in response to increased combustion of fossil fuels, contributing to global climate change. In order to mitigate the effects of global warming, development of new materials for cost-effective and energy-efficient CO2 capture is critically important. Graphene-based porous materials are an emerging class of solid adsorbents for selectively removing CO2 from flue gases. Herein, we report a simple and scalable approach to produce three-dimensional holey graphene frameworks with tunable porosity and pore geometry, and demonstrate their application as high-performance CO2 adsorbents. These holey graphene macrostructures exhibit a significantly improved specific surface area and pore volume compared to their pristine counterparts, and can be effectively used in post-combustion CO2 adsorption systems because of their intrinsic hydrophobicity together with good gravimetric storage capacities, rapid removal capabilities, superior cycling stabilities, and moderate initial isosteric heats. In addition, an exceptionally high CO2 over N2 selectivity can be achieved under conditions relevant to capture from the dry exhaust gas stream of a coal burning power plant, suggesting the possibility of recovering highly pure CO2 for long-term sequestration and/or utilization for downstream applications.

  11. Holey graphene frameworks for highly selective post-combustion carbon capture

    PubMed Central

    Chowdhury, Shamik; Balasubramanian, Rajasekhar

    2016-01-01

    Atmospheric CO2 concentrations continue to rise rapidly in response to increased combustion of fossil fuels, contributing to global climate change. In order to mitigate the effects of global warming, development of new materials for cost-effective and energy-efficient CO2 capture is critically important. Graphene-based porous materials are an emerging class of solid adsorbents for selectively removing CO2 from flue gases. Herein, we report a simple and scalable approach to produce three-dimensional holey graphene frameworks with tunable porosity and pore geometry, and demonstrate their application as high-performance CO2 adsorbents. These holey graphene macrostructures exhibit a significantly improved specific surface area and pore volume compared to their pristine counterparts, and can be effectively used in post-combustion CO2 adsorption systems because of their intrinsic hydrophobicity together with good gravimetric storage capacities, rapid removal capabilities, superior cycling stabilities, and moderate initial isosteric heats. In addition, an exceptionally high CO2 over N2 selectivity can be achieved under conditions relevant to capture from the dry exhaust gas stream of a coal burning power plant, suggesting the possibility of recovering highly pure CO2 for long-term sequestration and/or utilization for downstream applications. PMID:26879393

  12. Holey graphene frameworks for highly selective post-combustion carbon capture.

    PubMed

    Chowdhury, Shamik; Balasubramanian, Rajasekhar

    2016-02-16

    Atmospheric CO2 concentrations continue to rise rapidly in response to increased combustion of fossil fuels, contributing to global climate change. In order to mitigate the effects of global warming, development of new materials for cost-effective and energy-efficient CO2 capture is critically important. Graphene-based porous materials are an emerging class of solid adsorbents for selectively removing CO2 from flue gases. Herein, we report a simple and scalable approach to produce three-dimensional holey graphene frameworks with tunable porosity and pore geometry, and demonstrate their application as high-performance CO2 adsorbents. These holey graphene macrostructures exhibit a significantly improved specific surface area and pore volume compared to their pristine counterparts, and can be effectively used in post-combustion CO2 adsorption systems because of their intrinsic hydrophobicity together with good gravimetric storage capacities, rapid removal capabilities, superior cycling stabilities, and moderate initial isosteric heats. In addition, an exceptionally high CO2 over N2 selectivity can be achieved under conditions relevant to capture from the dry exhaust gas stream of a coal burning power plant, suggesting the possibility of recovering highly pure CO2 for long-term sequestration and/or utilization for downstream applications.

  13. Holey graphene frameworks for highly selective post-combustion carbon capture.

    PubMed

    Chowdhury, Shamik; Balasubramanian, Rajasekhar

    2016-01-01

    Atmospheric CO2 concentrations continue to rise rapidly in response to increased combustion of fossil fuels, contributing to global climate change. In order to mitigate the effects of global warming, development of new materials for cost-effective and energy-efficient CO2 capture is critically important. Graphene-based porous materials are an emerging class of solid adsorbents for selectively removing CO2 from flue gases. Herein, we report a simple and scalable approach to produce three-dimensional holey graphene frameworks with tunable porosity and pore geometry, and demonstrate their application as high-performance CO2 adsorbents. These holey graphene macrostructures exhibit a significantly improved specific surface area and pore volume compared to their pristine counterparts, and can be effectively used in post-combustion CO2 adsorption systems because of their intrinsic hydrophobicity together with good gravimetric storage capacities, rapid removal capabilities, superior cycling stabilities, and moderate initial isosteric heats. In addition, an exceptionally high CO2 over N2 selectivity can be achieved under conditions relevant to capture from the dry exhaust gas stream of a coal burning power plant, suggesting the possibility of recovering highly pure CO2 for long-term sequestration and/or utilization for downstream applications. PMID:26879393

  14. CW room temperature operation of praseodymium-doped fluorozirconate glass fibre lasers in the blue-green, green and red spectral regions

    NASA Astrophysics Data System (ADS)

    Smart, R. G.; Carter, J. N.; Tropper, A. C.; Hanna, D. C.; Davey, S. T.; Carter, S. F.; Szebesta, D.

    1991-11-01

    We report room temperature, continuous-wave oscillation of Pr 3+-doped fluorozirconate fibre lasers at around 491 nm, 520 nm, 605 nm, 635 nm and 715 nm. An output power of 250 mW has been obtained 635 nm for 800 mW of pump power from an argon ion laser operating at 476.5 nm. Tunable operation of the red transitions has been investigated, with output powers in excess of 30 mW being obtained. Q-switched pulses of 75 ns (fwhm) and 20 W peak power at 635 nm have also been generated.

  15. 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)

  16. Measurement of chromatic dispersion of polarization modes in optical fibres using white-light spectral interferometry

    NASA Astrophysics Data System (ADS)

    Hlubina, P.; Ciprian, D.; Kadulová, M.

    2010-04-01

    We report on a white-light interferometric technique for a broad spectral range measurement (e.g. 500-1600 nm) of chromatic dispersion of polarization modes in short-length optical fibres. The technique utilizes an unbalanced Mach-Zehnder interferometer with a fibre under test of known length inserted in one of the interferometer arms and the other arm with adjustable path length. We record a series of spectral interferograms by VIS-NIR and NIR fibre-optic spectrometers to measure the equalization wavelength as a function of the path length difference, or equivalently the differential group index dispersion of one polarization mode. The differential group dispersion of the other polarization mode is obtained from measurement of the group modal birefringence dispersion. We verify the applicability of the method by measuring the chromatic dispersion of polarization modes in a birefringent holey fibre. We apply a five-term power series fit to the measured data and confirm by its differentiation that the chromatic dispersion agrees well with that specified by the manufacturer. We also measure by this technique the chromatic dispersion of polarization modes in an elliptical-core fibre.

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

    SciTech Connect

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

    2015-05-22

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  19. Self referenced Yb-fiber-laser frequency comb using a dispersion micromanaged tapered holey fiber.

    PubMed

    Pal, Parama; Knox, Wayne H; Hartl, Ingmar; Fermann, Martin E

    2007-09-17

    We demonstrate a fully stabilized frequency comb in the 1mum spectral region based on an Yb-fiber oscillator and a cladding pumped chirped pulse Yb-fiber amplifier whose output is spectrally broadened in a dispersion micromanaged holey fiber. The dispersion micromanaged fiber is used to generate efficient, low noise spectral components at 523nm which are heterodyned with the second harmonic of the amplifier output for standard f-to-2f self-referenced carrier envelope offset frequency detection. For comb stabilization we phase-lock this offset frequency and the oscillator repetition frequency simultaneously to an RF reference by feedback controlling the oscillator pump diode current and the driving voltage of an intracavity piezo-electric fiber stretcher respectively. PMID:19547582

  20. Nitrogen-Doped Holey Graphene Film-Based Ultrafast Electrochemical Capacitors.

    PubMed

    Zhou, Qinqin; Zhang, Miao; Chen, Ji; Hong, Jong-Dal; Shi, Gaoquan

    2016-08-17

    The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering are usually the largest components in the electronic circuits because of their low specific capacitances and bulky sizes. Herein, nitrogen-doped holey graphene (NHG) films were prepared by thermal annealing the composite films of polyvinylpyrrolidone (PVP), graphene oxide (GO), and ferric oxide (Fe2O3) nanorods followed by chemical etching with hydrochloride acid. The typical electrochemical capacitor with NHG electrodes exhibited high areal and volumetric specific capacitances of 478 μF cm(-2) and 1.2 F cm(-3) at 120 Hz, ultrafast frequency response with a phase angle of -81.2° and a resistor-capacitor time constant of 203 μs at 120 Hz, as well as excellent cycling stability. Thus, it is promising to replace conventional AEC for AC line-filtering in miniaturized electronics.

  1. Nitrogen-Doped Holey Graphene Film-Based Ultrafast Electrochemical Capacitors.

    PubMed

    Zhou, Qinqin; Zhang, Miao; Chen, Ji; Hong, Jong-Dal; Shi, Gaoquan

    2016-08-17

    The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering are usually the largest components in the electronic circuits because of their low specific capacitances and bulky sizes. Herein, nitrogen-doped holey graphene (NHG) films were prepared by thermal annealing the composite films of polyvinylpyrrolidone (PVP), graphene oxide (GO), and ferric oxide (Fe2O3) nanorods followed by chemical etching with hydrochloride acid. The typical electrochemical capacitor with NHG electrodes exhibited high areal and volumetric specific capacitances of 478 μF cm(-2) and 1.2 F cm(-3) at 120 Hz, ultrafast frequency response with a phase angle of -81.2° and a resistor-capacitor time constant of 203 μs at 120 Hz, as well as excellent cycling stability. Thus, it is promising to replace conventional AEC for AC line-filtering in miniaturized electronics. PMID:27453989

  2. 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'.

  3. 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

  4. Anti-Stokes luminescence in bismuth-doped aluminoand phosphosilicate fibres under two-step IR excitation

    NASA Astrophysics Data System (ADS)

    Firstov, S. V.; Riumkin, K. E.; Khopin, V. F.; Alyshev, S. V.; Firstova, E. G.; Mel'kumov, M. A.; Gur'yanov, A. N.; Dianov, E. M.

    2016-07-01

    We have studied the luminescence properties of optical fibres with a bismuth-doped alumino- and phosphosilicate glass core under two-step excitation and obtained new experimental data on the properties of luminescence centres in such fibres.

  5. 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.

  6. 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

  7. Microwave Enabled One-Pot, One-Step Fabrication and Nitrogen Doping of Holey Graphene Oxide for Catalytic Applications.

    PubMed

    Patel, Mehulkumar; Feng, Wenchun; Savaram, Keerthi; Khoshi, M Reza; Huang, Ruiming; Sun, Jing; Rabie, Emann; Flach, Carol; Mendelsohn, Richard; Garfunkel, Eric; He, Huixin

    2015-07-15

    The unique properties of a holey graphene sheet, referred to as a graphene sheet with nanoholes in its basal plane, lead to wide range of applications that cannot be achieved by its nonporous counterpart. However, the large-scale solution-based production requires graphene oxide (GO) or reduced GO (rGO) as the starting materials, which take hours to days for fabrication. Here, an unexpected discovery that GO with or without holes can be controllably, directly, and rapidly (tens of seconds) fabricated from graphite powder via a one-step-one-pot microwave assisted reaction with a production yield of 120 wt% of graphite is reported. Furthermore, a fast and low temperature approach is developed for simultaneous nitrogen (N) doping and reduction of GO sheets. The N-doped holey rGO sheets demonstrate remarkable electrocatalytic capabilities for the electrochemical oxygen reduction reaction. The existence of the nanoholes provides a "short cut" for efficient mass transport and dramatically increases edges and surface area, therefore, creates more catalytic centers. The capability of rapid fabrication and N-doping as well as reduction of holey GO can lead to development of an efficient catalyst that can replace previous coin metals for energy generation and storage, such as fuel cells and metal-air batteries. PMID:25683019

  8. Microwave Enabled One-Pot, One-Step Fabrication and Nitrogen Doping of Holey Graphene Oxide for Catalytic Applications.

    PubMed

    Patel, Mehulkumar; Feng, Wenchun; Savaram, Keerthi; Khoshi, M Reza; Huang, Ruiming; Sun, Jing; Rabie, Emann; Flach, Carol; Mendelsohn, Richard; Garfunkel, Eric; He, Huixin

    2015-07-15

    The unique properties of a holey graphene sheet, referred to as a graphene sheet with nanoholes in its basal plane, lead to wide range of applications that cannot be achieved by its nonporous counterpart. However, the large-scale solution-based production requires graphene oxide (GO) or reduced GO (rGO) as the starting materials, which take hours to days for fabrication. Here, an unexpected discovery that GO with or without holes can be controllably, directly, and rapidly (tens of seconds) fabricated from graphite powder via a one-step-one-pot microwave assisted reaction with a production yield of 120 wt% of graphite is reported. Furthermore, a fast and low temperature approach is developed for simultaneous nitrogen (N) doping and reduction of GO sheets. The N-doped holey rGO sheets demonstrate remarkable electrocatalytic capabilities for the electrochemical oxygen reduction reaction. The existence of the nanoholes provides a "short cut" for efficient mass transport and dramatically increases edges and surface area, therefore, creates more catalytic centers. The capability of rapid fabrication and N-doping as well as reduction of holey GO can lead to development of an efficient catalyst that can replace previous coin metals for energy generation and storage, such as fuel cells and metal-air batteries.

  9. The hygroscopic behavior of plant fibres: a review

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  10. 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).

  11. Understanding and Improving the Elastic Compressive Modulus of Fibre Reinforced Soy-Based Polyurethane Foams

    NASA Astrophysics Data System (ADS)

    Hussain, Sadakat

    Soy-based polyurethane foams (PUFs) were reinforced with fibres of different aspect ratios to improve the compressive modulus. Each of the three fibre types reinforced PUF differently. Shorter micro-crystalline cellulose fibres were found embedded inside the cell struts of PUF and reinforced them. The reinforcement was attributed to be stress transfer from the matrix to the fibre by comparing the experimental results to those predicted by micro-mechanical models for short fibre reinforced composites. The reinforced cell struts increased the overall compressive modulus of the foam. Longer glass fibres (470 microns, length) provided the best reinforcement. These fibres were found to be larger than the cell diameters. The micro-mechanical models could not predict the reinforcement provided by the longer glass fibres. The models predicted negligible reinforcement because the very low modulus PUF should not transfer load to the higher modulus fibres. However, using a finite element model, it was determined that the fibres were providing reinforcement through direct fibre interaction with each other. Intermediate length glass fibres (260 microns, length) were found to poorly reinforce the PUF and should be avoided. These fibres were too short to interact with each other and were on average too large to embed and reinforce cell struts. In order to produce natural fibre reinforced PUFs in the future, a novel device was invented. The purpose of the device is to deliver natural fibres at a constant mass flow rate. The device was found to consistently meter individual loose natural fibre tufts at a mass flow rate of 2 grams per second. However, the device is not robust and requires further development to deliver a fine stream of natural fibre that can mix and interact with the curing polymeric components of PUF. A design plan was proposed to address the remaining issues with the device.

  12. Amplifying properties of heavily erbium-doped active fibres

    SciTech Connect

    Plotskii, A Yu; Kurkov, Andrei S; Yashkov, M Yu; Bubnov, M M; Likhachev, M E; Sysolyatin, A A; Dianov, Evgenii M; Gur'yanov, A N

    2005-06-30

    The relative concentration of erbium ions undergoing nonradiative relaxation from the metastable to the ground level is measured in aluminosilicate glass fibres doped with erbium ions at concentration between 3x10{sup 18} and 10{sup 20} cm{sup -3}. The dependence of the fraction of such ions on the Er{sup 3+} concentration is determined for fibres containing different amounts of aluminium oxide in a core. It is shown that the fraction of erbium ions not involved in amplification substantially decreases with increasing the Al{sub 2}O{sub 3} concentration. It is found that clustering leads to a considerable decrease in the gain in heavily Er{sup 3+}-doped active fibres. The dependence of the quantum efficiency of a fibre amplifier on the erbium ion concentration is obtained based on the measurements performed. This dependence can be used for optimising the parameters of erbium-doped fibre amplifiers. (fibres. integrated-optic waveguides)

  13. Dry Pressed Holey Graphene Composites for Li-air Battery Cathodes

    NASA Astrophysics Data System (ADS)

    Lacey, Steven; Lin, Yi; Hu, Liangbing

    Graphene is considered an ``omnipotent'' material due to its unique structural characteristics and chemical properties. By heating graphene powder in an open-ended tube furnace, a novel compressible carbon material, holey graphene (hG), can be created with controlled porosity and be further decorated with nanosized catalysts to increase electrocatalytic activity. All hG-based materials were characterized using various microscopic and spectroscopic techniques to obtain morphological, topographical, and chemical information as well as to identify any disordered/crystalline phases. In this work, an additive-free dry press method was employed to press the hG composite materials into high mass loading mixed, sandwich, and double-decker Li-air cathode architectures using a hydraulic press. The sandwich and double-decker (i.e. Big Mac) cathode architectures are the first of its kind and can be discharged for more than 200 hours at a current density of 0.2 mA/cm2. The scalable, binderless, and solventless dry press method and unique Li-air cathode architectures presented here greatly advance electrode fabrication possibilities and could promote future energy storage advancements. Support appreciated from the NASA Internships Fellowships Scholarships (NIFS) Program.

  14. 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.

  15. Surface, interphase and tensile properties of unsized, sized and heat treated basalt fibres

    NASA Astrophysics Data System (ADS)

    Förster, T.; Sommer, G. S.; Mäder, E.; Scheffler, C.

    2016-07-01

    Recycling of fibre reinforced polymers is in the focus of several investigations. Chemical and thermal treatments of composites are the common ways to separate the reinforcing fibres from the polymer matrices. However, most sizings on glass and basalt fibre are not designed to resist high temperatures. Hence, a heat treatment might also lead to a sizing removal, a decrease of mechanical performance and deterioration in fibre-matrix adhesion. Different basalt fibres were investigated using surface analysis methods as well as single fibre tensile tests and single fibre pull-out tests in order to reveal the possible causes of these issues. Heat treatment in air reduced the fibre tensile strength in the same level like heat treatment in nitrogen atmosphere, but it influenced the wetting capability. Re-sizing by a coupling agent slightly increased the adhesion strength and reflected a decreased post-debonding friction.

  16. 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

  17. 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)

  18. Gain-switched holmium-doped fibre laser.

    PubMed

    Wu, Ka S; Ottaway, David; Munch, Jesper; Lancaster, David G; Bennetts, Shayne; Jackson, Stuart D

    2009-11-01

    We demonstrate the first gain-switched, singly doped, single-mode holmium-doped silicate glass fibre laser that operates at 2.106 microm. Using a gain-switched 1.909-microm thulium-doped fibre laser as the pump source, output pulses of energy 3.2 microJ and pulse duration of 150 ns were generated at 80 kHz and slope efficiency of 44%. Pulse stacking within the holmium-doped fibre laser resulted in significantly shorter 70 ns pulses.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. FRD in optical fibres at low temperatures: investigations for Gemini's Wide-field Fibre Multi-Object Spectrograph

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. C.; de Oliveira, L. S.; Dos Santos, J. B.; Arruda, M. V.; Dos Santos, L. G. C.; Rodrigues, F.; de Castro, F. L. F.

    2011-06-01

    While there is no direct evidence for the deterioration in Focal Ratio Degradation (FRD) of optical fibres in severe temperature gradients, the fibre ends inserted into metallic containment devices such as steel ferrules can be a source of stress, and hence increased FRD at low temperatures. In such conditions, instruments using optical fibres may suffer some increase in FRD and consequent loss of system throughput when they are working in environments with significant thermal gradients, a common characteristic of ground-based observatories. In this paper we present results of experiments with optical fibres inserted in different materials as a part of our prototyping study for Gemini's Wide-field Multi-Object Spectrograph (WFMOS) project. Thermal effects and the use of new holding techniques will be discussed in the context of Integral Field Units and multi-fibres systems. In this work, we have used careful methodologies that give absolute measurements of FRD to quantify the advantages of using epoxy-based composites rather than metals as support structures for the fibre ends. This is shown to be especially important in minimizing thermally induced stresses in the fibre terminations. Not only is this important for optimizing fibre spectrograph performance but the benefits of using such materials are demonstrated in the minimization of positional variations and the avoidance of metal-to-glass delamination. Furthermore, by impregnating the composites with small zirconium oxide particles the composite materials supply their own fine polishing grit which aids significantly to the optical quality of the finished product.

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

    PubMed Central

    Aalto, M.; Heppleston, A. G.

    1984-01-01

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

  3. 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

  4. Oxide glasses for mid-infrared lasers

    NASA Astrophysics Data System (ADS)

    Richards, Billy D. O.; Jha, Animesh; Jose, Gin; Jiang, Xin

    2011-06-01

    We present an overview of rare-earth doped heavy metal oxide and oxy-fluoride glasses which show promise as host materials for lasers operating in the 2-5 μm spectral region for medical, military and sensing applications. By engineering glass composition and purity, tellurite and germanate glasses can support transmission up to and beyond 5 μm and can have favourable thermal, mechanical and environmental stability compared to fluoride glasses. We discuss techniques for glass purification and water removal for enhanced infrared transmission. By comparing the material properties of the glass, and spectroscopic performance of selected rare-earth dopant ions we can identify promising compositions for fibre and bulk lasers in the mid-infrared. Tellurite glass has recently been demonstrated to be a suitable host material for efficient and compact lasers in the {2 μm spectral region in fibre and bulk form and the next challenge is to extend the operating range further into the infrared region where silica fibre is not sufficiently transparent, and provide an alternative to fluoride glass and fibre.

  5. 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.

  6. 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.

  7. An Historic Overview of the Development of Fibre Metal Laminates

    NASA Astrophysics Data System (ADS)

    Vermeeren, C. A. J. R.

    2003-07-01

    In this paper a brief overview of the history of Fibre Metal Laminates Arall and Glare is given as background information for the other, technical articles in this journal. The story of the development of Fibre Metal Laminates is rather a unique story in the history of aircraft materials: A university laboratory invented, developed and certified an aircraft material. Many parties were involved naturally, yet the very heart of the activity was the Structures and Materials Laboratory of the Faculty of Aerospace Engineering of Delft University of Technology in The Netherlands. At the break of the world's largest passenger transport aircraft, the Airbus A380, in which a substantial part of the fuselage will be made of Glare, the glass fibre-aluminium version of Fibre Metal Laminates, it is a good moment to tell some of its history.

  8. Tissue ablation via optical fibre delivery of UV laser radiation

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    We report the use of an ultraviolet (UV) laser and optical fibre arrangement capable of precise and controllable tissue ablation. The 5th (213nm) and 4th (266nm) harmonics of a Nd:YAG laser were launched into optical fibres using a hollow glass taper to concentrate the beam. Standard and modified silica/silica optical fibres were used, all commercially available. The available energy and fluence, as a function of optical fibre length, were evaluated and maximised. Single 5ns pulses were used to ablate both fresh porcine retina and in vivo rat trabecular meshwork. Fluences of 0.4 to 4.0 J/cm2 of 266nm and 0.2 to 1.0 J/cm2 of 213nm were used respectively. Thus demonstrating the potential use of this system for intraocular surgical applications.

  9. Luminescence and photoinduced absorption in ytterbium-doped optical fibres

    NASA Astrophysics Data System (ADS)

    Rybaltovsky, A. A.; Aleshkina, S. S.; Likhachev, M. E.; Bubnov, M. M.; Umnikov, A. A.; Yashkov, M. V.; Gur'yanov, Aleksei N.; Dianov, Evgenii M.

    2011-12-01

    Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al2O3 : SiO2, Al2O3 : Yb2O3 : SiO2, and P2O5 : Yb2O3 : SiO2. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role in photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb3+ ions to Yb2+. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb3+ ions.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  12. 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)

  13. 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

  14. Fabrication of fibre reinforced nickel aluminide matrix composites by reactive processing

    SciTech Connect

    Downing, M.; Horsfall, I.

    1994-12-31

    This paper describes the fabrication by reactive processing of short, and continuous, alumina fibre reinforced nickel aluminide matrix composites. The fibre is introduced into the aluminide system to increase toughness and high temperature strength. The short fibre reinforced nickel aluminide is formed by squeeze casting a porous preform containing nickel powder and SAFFIL fibre with an aluminium or aluminium alloy melt. The continuous fibre reinforced nickel aluminide is formed by squeeze casting a jig containing nickel coated ALMAX fibre. The short fibre reinforced composite (containing 10% and 20% volume fibre) reacted during infiltration with an aluminium melt to form a single phase intermetallic. Using an aluminium-copper melt the intermetallic formation was inhibited and a multi-phase composite was obtained. A preliminary study into reactive processing of this system by utilising a hot isostatic pressing (HIP) cycle is presented. HIP was required to prevent the formation of porosity due to an imbalance in the diffusive mobility of the various components. It was found that HIP was only effective on canned samples, the preferred encapsulation material being glass. The continuous fibre reinforced composite did not react to an intermetallic phase when infiltrated with an aluminum melt. Use of an aluminum-copper melt resulted in partial nickel-melt reaction producing various nickel-aluminum (-copper) phases. HIP was then used to form a two phase intermetallic matrix with no evidence of fibre damage.

  15. 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.

  16. Fire Retardancy of Natural Fibre Reinforced Sheet Moulding Compound

    NASA Astrophysics Data System (ADS)

    Hapuarachchi, T. D.; Ren, G.; Fan, M.; Hogg, P. J.; Peijs, T.

    2007-07-01

    Due to environmental awareness and economical considerations, natural fibre reinforced polymer composites seem to present a viable alternative to synthetic fibre reinforced polymer composites such as glass fibres. This is a feasibility study to asses the potential application of natural fibre reinforced sheet moulding compound materials (NF-SMC) for the use in building applications, with particular emphases to their reaction to fire. The reinforcing fibres in this study were industrial hemp fibres. The cone calorimeter which asses the fire hazard of materials by Heat Release Rate (HRR) was used, radiant heat fluxes of 25 and 50 kW/m2 were utilised to simulate an ignition source and fully developed room fire conditions respectively. The results acquired here demonstrate that the NF-SMC can compete with current building materials in terms of their fire behaviour. The peak heat release value for the fire retardant (FR) NF-SMC was 176 kW/m2 conversely for a non-FR NF-SMC was 361 kW/m2.

  17. In Situ Grown TiO2 Nanospindles Facilitate the Formation of Holey Reduced Graphene Oxide by Photodegradation.

    PubMed

    Peng, Guiming; Ellis, James E; Xu, Gang; Xu, Xueqing; Star, Alexander

    2016-03-23

    Titanium dioxide (TiO2) nanostructures and TiO2/graphene nanocomposites are intensively studied materials for energy conversion, energy storage, and organic contaminant photodegradation. However, for TiO2/graphene composites, impermeability across the graphitic basal plane for electrolytes, metal ions, and gas molecules hinders their practical applications. Herein we report a simple, environmentally friendly synthetic route for mesoporous anatase TiO2 nanospindles, and successfully apply this method to obtain in situ grown TiO2 nanospindles/graphene oxide composite. After a thermal reduction at 400 °C, holes are created in the reduced graphene oxide (RGO) sheets through a photocatalytic oxidation mechanism. The formation of holes in RGO is promoted by photogenerated hydroxyl radicals that oxidize and subsequently decarboxylate the graphitic surface of RGO. The proposed mechanism was supported by photocatalytic electrochemical properties of the nanomaterials. The resulting TiO2/holey RGO composites may overcome the original impermeability of graphene sheets and find applications in catalysis, energy conversion/storage devices, and sensors. PMID:26929979

  18. Novel synthesis of holey reduced graphene oxide (HRGO) by microwave irradiation method for anode in lithium-ion batteries

    PubMed Central

    Alsharaeh, Edreese; Ahmed, Faheem; Aldawsari, Yazeed; Khasawneh, Majdi; Abuhimd, Hatem; Alshahrani, Mohammad

    2016-01-01

    In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure. The HRGO were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), and Raman spectroscopy. These novel HRGO exhibited high rate capability with excellent cycling stability as an anode material for lithium-ion batteries. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA/g). The cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA/g) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure (2–5 nm pores) and high surface area (457 m2/g), providing numerous active sites for Li+ insertion, high electrical conductivity, low charge-transfer resistance across the electrolyte–electrode interface, and improved structural stability against the local volume change during Li+ insertion–extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization. PMID:27457356

  19. Novel synthesis of holey reduced graphene oxide (HRGO) by microwave irradiation method for anode in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Alsharaeh, Edreese; Ahmed, Faheem; Aldawsari, Yazeed; Khasawneh, Majdi; Abuhimd, Hatem; Alshahrani, Mohammad

    2016-07-01

    In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure. The HRGO were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), and Raman spectroscopy. These novel HRGO exhibited high rate capability with excellent cycling stability as an anode material for lithium-ion batteries. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA/g). The cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA/g) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure (2–5 nm pores) and high surface area (457 m2/g), providing numerous active sites for Li+ insertion, high electrical conductivity, low charge-transfer resistance across the electrolyte–electrode interface, and improved structural stability against the local volume change during Li+ insertion–extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization.

  20. Novel synthesis of holey reduced graphene oxide (HRGO) by microwave irradiation method for anode in lithium-ion batteries.

    PubMed

    Alsharaeh, Edreese; Ahmed, Faheem; Aldawsari, Yazeed; Khasawneh, Majdi; Abuhimd, Hatem; Alshahrani, Mohammad

    2016-01-01

    In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure. The HRGO were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), and Raman spectroscopy. These novel HRGO exhibited high rate capability with excellent cycling stability as an anode material for lithium-ion batteries. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA/g). The cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA/g) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure (2-5 nm pores) and high surface area (457 m(2)/g), providing numerous active sites for Li(+) insertion, high electrical conductivity, low charge-transfer resistance across the electrolyte-electrode interface, and improved structural stability against the local volume change during Li(+) insertion-extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization. PMID:27457356

  1. Novel synthesis of holey reduced graphene oxide (HRGO) by microwave irradiation method for anode in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Alsharaeh, Edreese; Ahmed, Faheem; Aldawsari, Yazeed; Khasawneh, Majdi; Abuhimd, Hatem; Alshahrani, Mohammad

    2016-07-01

    In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure. The HRGO were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), and Raman spectroscopy. These novel HRGO exhibited high rate capability with excellent cycling stability as an anode material for lithium-ion batteries. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA/g). The cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA/g) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure (2-5 nm pores) and high surface area (457 m2/g), providing numerous active sites for Li+ insertion, high electrical conductivity, low charge-transfer resistance across the electrolyte-electrode interface, and improved structural stability against the local volume change during Li+ insertion-extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization.

  2. Two-photon absorption in SiO{sub 2}- and (SiO{sub 2} + GeO{sub 2})-based fibres at a wavelength of 349 nm

    SciTech Connect

    Chunaev, D S; Karasik, A Ya

    2014-06-30

    The nonlinear two-photon light absorption coefficients have been measured in an optical fibre with a quartz glass (SiO{sub 2}) core and in a fibre with a germanosilicate glass (SiO{sub 2} + GeO{sub 2}) core. The two-photon absorption coefficient β measured at a wavelength of 349 nm in the (SiO{sub 2} + GeO{sub 2})-based fibre (13.7 cm TW{sup -1}) multiply exceeds that for the pure quartz glass optical fibre (0.54 cm TW{sup -1}). (nonlinear optical phenomena)

  3. Indirect aesthetic adhesive restoration with fibre-reinforced composite resin.

    PubMed

    Corona, S A M; Garcia, P P N S; Palma-Dibb, R G; Chimello, D T

    2004-10-01

    This paper describes the restoration of an endodontically treated upper first molar with a fibre-reinforced onlay indirect composite resin restoration. The clinical and radiographic examination confirmed that the tooth had suffered considerable loss of structure. Therefore, an indirect restoration was indicated. First, a core was built with resin-modified glass ionomer cement, followed by onlay preparation, mechanical/chemical gingival retraction and impression with addition-cured silicone. After the laboratory phase, the onlay was tried in, followed by adhesive bonding and occlusal adjustment. It can be concluded that fibre-reinforced aesthetic indirect composite resin restoration represented, in the present clinical case, an aesthetic and conservative treatment option. However, the use of fibres should be more extensively studied to verify the real improvement in physical and mechanical properties.

  4. Metal clad active fibres for power scaling and thermal management at kW power levels.

    PubMed

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

    2016-08-01

    We present a new approach to high power fibre laser design, consisting of a polymer-free all-glass optical fibre waveguide directly overclad with a high thermal conductivity metal coating. This metal clad active fibre allows a significant reduction in thermal resistance between the active fibre and the laser heat-sink as well as a significant increase in the operating temperature range. In this paper we show the results of a detailed thermal analysis of both polymer and metal coated active fibres under thermal loads typical of kW fibre laser systems. Through several different experiments we present the first demonstration of a cladding pumped aluminium-coated fibre laser and the first demonstration of efficient operation of a cladding-pumped fibre laser at temperatures of greater than 400 °C. Finally, we highlight the versatility of this approach through operation of a passively (radiatively) cooled ytterbium fibre laser head at an output power of 405 W in a compact and ultralight package weighing less than 100 g. PMID:27505822

  5. Laser recrystallization and inscription of compositional microstructures in crystalline SiGe-core fibres

    PubMed Central

    Coucheron, David A.; Fokine, Michael; Patil, Nilesh; Breiby, Dag Werner; Buset, Ole Tore; Healy, Noel; Peacock, Anna C.; Hawkins, Thomas; Jones, Max; Ballato, John; Gibson, Ursula J.

    2016-01-01

    Glass fibres with silicon cores have emerged as a versatile platform for all-optical processing, sensing and microscale optoelectronic devices. Using SiGe in the core extends the accessible wavelength range and potential optical functionality because the bandgap and optical properties can be tuned by changing the composition. However, silicon and germanium segregate unevenly during non-equilibrium solidification, presenting new fabrication challenges, and requiring detailed studies of the alloy crystallization dynamics in the fibre geometry. We report the fabrication of SiGe-core optical fibres, and the use of CO2 laser irradiation to heat the glass cladding and recrystallize the core, improving optical transmission. We observe the ramifications of the classic models of solidification at the microscale, and demonstrate suppression of constitutional undercooling at high solidification velocities. Tailoring the recrystallization conditions allows formation of long single crystals with uniform composition, as well as fabrication of compositional microstructures, such as gratings, within the fibre core. PMID:27775066

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

    PubMed

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

    2013-02-25

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

  7. Humidity insensitive step-index polymer optical fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Woyessa, G.; Fasano, A.; Stefani, A.; Markos, C.; Nielsen, K.; Rasmussen, H. K.; Bang, O.

    2015-09-01

    We have fabricated and characterised a humidity insensitive step index(SI) polymer optical fibre(POF) Bragg grating sensors. The fibre was made based on the injection molding technique, which is an efficient method for fast, flexible and cost effective preparation of the fibre preform. The fabricated SIPOF has a core made from TOPAS with a glass transition temperature of 134°C and a cladding from ZEONEX with a glass transition temperature of 138°C. The main advantages of the proposed SIPOF are the low water absorption and good chemical resistance compared to the conventional poly-methyl-methacrylate (PMMA) based SIPOFs. The fibre has a minimum loss of ~6dB/m at 770nm.

  8. Reversible changes in the reflectivity of different types of fibre Bragg gratings

    SciTech Connect

    Gnusin, P I; Vasil'ev, Sergei A; Medvedkov, O I; Dianov, Evgenii M

    2010-12-09

    We have studied strain- and temperature-induced reversible changes in the reflectivity of different types of fibre Bragg gratings. The results demonstrate that the strain sensitivity of the reflectivity of type I and IIa Bragg gratings is mainly due to the photoinduced reduction in the elasto-optic coefficient p{sub 12} of the core glass and that its temperature sensitivity results from the increase in the thermo-optic coefficient of the glass. UV exposure of fibres loaded with molecular hydrogen has an insignificant effect on these material coefficients. We also analyse the effects of UV fluence and germanium concentration in the fibre core on the reversible changes in the reflectivity of the grating. (optical fibres)

  9. High-energy pulsed fibre laser based on a two-fibre assembly

    SciTech Connect

    Kobtsev, Sergey M; Kukarin, S V; Fedotov, Yu S

    2009-05-31

    We demonstrate for the first time a relatively simple fibre laser system with a passively Q-switched master oscillator and a polarised output pulse energy of up to 110 {mu}J at 1080 nm. The system is pumped by a single 12-W multimode cw source at 980 nm. Depending on the pump power, the pulse duration varies from 280 ns to 1.8 {mu}s and the pulse repetition rate, from 45 to 140 kHz. The maximum average output power is 5 W. The system has been tested for its performance in metal and glass processing. (lasers and amplifiers)

  10. Optical cochlear implant: evaluation of insertion forces of optical fibres in a cochlear model and of traumata in human temporal bones.

    PubMed

    Balster, Sven; Wenzel, Gentiana I; Warnecke, Athanasia; Steffens, Melanie; Rettenmaier, Alexander; Zhang, Kaiyin; Lenarz, Thomas; Reuter, Guenter

    2014-02-01

    Optical stimulation for hearing restoration is developing as an alternative therapy to electrical stimulation. For a more frequency-specific activation of the auditory system, light-guiding fibres need to be inserted into the coiled cochlea. To enable insertion with minimal trauma, glass fibres embedded in silicone were used as models. Thus, glass fibres of varying core/cladding diameter with and without silicon coating (single as well as in bundles) were inserted into a human scala tympani (ST) model. Insertion cochlear model force measurements were performed, and the thinner glass fibres that showed low insertion forces in the model were inserted into cadaveric human temporal bones. Silicone-coated glass fibres with different core/cladding diameters and bundle sizes could be inserted up to a maximum depth of 20 mm. Fibres with a core/cladding diameter of 50/55 μm break during insertion deeper than 7-15 mm into the ST model, whereas thinner fibres (20/25 μm) could be inserted in the model without breakage and in human temporal bones without causing trauma to the inner ear structures. The insertion forces of silicone-coated glass fibres are comparable to those measured with conventional cochlear implant (CI) electrodes. As demonstrated in human temporal bones, a minimal traumatic implantation of an optical CI may be considered feasible.

  11. Glasses for seeing beyond visible.

    PubMed

    Zhang, XiangHua; Bureau, Bruno; Lucas, Pierre; Boussard-Pledel, Catherine; Lucas, Jacques

    2008-01-01

    Conventional glasses based on oxides have a transparency limited by phonon absorption in the near IR region and have a limited interest for analyzing information located far beyond the visible. The IR spectral domain is nevertheless of prime interest, since it covers fundamental wavelength ranges used for thermal imaging as well as molecular vibrational signatures. Besides spectacular advances in the field of IR detectors, the main significant progresses are related to the development of IR glass optics, such as lenses or IR optical fibres. The field of IR glasses is almost totally dominated by glasses formed from heavy atoms such as the chalcogens S, Se and Te. Their transparency extends up to 12, 16 and 28 microm for sulfide-, selenide- and the new generation of telluride-based glasses, respectively. They cover the atmospheric transparency domains, 3-5 and 8-13 microm, respectively, at which the IR radiation can propagate allowing thermal imaging and night-vision operations through thick layers of atmosphere. The development of new glass compositions will be discussed on the basis of structural consideration with the objective of moulding low-cost lenses for IR cameras used, for instance, in car-driving assistance. Additionally, multimode, single-index, optical fibres operating in the 3 to 12 microm window developed for in situ remote evanescent-wave IR spectroscopy will also be mentioned. The detection of molecular IR signatures is applied to environmental monitoring for investigating the pollution of underground water with toxic molecules. The extension of this technique to the investigation of biomolecules in three different studies devoted to liver tissues analysis, bio-film formation, and cell metabolism will also be discussed. Finally we will mention the developments in the field of single-mode fibres operating around 10 mum for the Darwin space mission, which is aiming at discovering, signs of biological life in telluric earth-like exoplanets throughout

  12. 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

  13. 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.

  14. Second-order Bragg gratings in single-mode chalcogenide fibres

    SciTech Connect

    Bernier, M; Asatryan, K E; Vallee, R; Galstian, T M; Vasil'ev, Sergei A; Medvedkov, O I; Plotnichenko, V G; Gnusin, P I; Dianov, Evgenii M

    2011-05-31

    Bragg gratings with a second-order resonance wavelength in the near-IR spectral region have been inscribed into single-mode chalcogenide (As{sub 2}S{sub 3}) glass fibre by a He - Ne laser beam using a configuration typical of Bragg grating fabrication in germanosilicate fibre, with the use of a phase mask that ensures effective diffraction of the writing light into the +1 and -1 orders. The spectra of the inscribed gratings show no resonances due to cladding mode excitation because the cladding material is photosensitive. (fibre optics)

  15. Effect of the active-ion concentration on the lasing dynamics of holmium fibre lasers

    SciTech Connect

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

    2010-12-09

    The lasing dynamics of fibre lasers with a core based on quartz glass doped with holmium ions to concentrations in the range of 10{sup 19}-10{sup 20} cm{sup -3} is investigated. It is shown that fibre lasers with a high concentration of active holmium ions generate pulses, but a decrease in the holmium concentration changes the lasing from pulsed to cw regime. At the same time, a decrease in the active-ion concentration and the corresponding increase in the fibre length in the cavity reduce the lasing efficiency. (lasers)

  16. Luminescence and photoinduced absorption in ytterbium-doped optical fibres

    SciTech Connect

    Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E; Bubnov, M M; Umnikov, A A; Yashkov, M V; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-12-31

    Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role in photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.

  17. 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.

  18. Binding of environmental carcinogens to asbestos and mineral fibres.

    PubMed Central

    Harvey, G; Pagé, M; Dumas, L

    1984-01-01

    A rapid method has been developed for measuring the binding capacity of asbestos and other mineral fibres for environmental carcinogens. Benzo(alpha)pyrene (B(alpha)P), nitrosonornicotine (NNN), and N-acetyl-2-aminofluorene (NAAF) were assayed in the presence of Canadian grade 4T30 chrysotile, chrysotile A, amosite, crocidolite, glass microfibres, glasswool, attapulgite, and titanium dioxide. Chrysotile binds significantly more carcinogens than the other mineral fibres. This binding assay is reproducible with coefficients of variation of less than 8% and 6% respectively for inter and intra assay. The influence of pH was also studied, and there is good correlation between the carcinogen binding and the charge of the tested mineral fibres. The in vitro cytotoxicity on macrophage like cell line P388D1 and the haemolytic activity of various mineral fibres were also measured; a good correlation was found between the binding capacity and the cytotoxicity of tested mineral fibres on P388D1 cells. These results give some explanations for the reported synergism between exposure to asbestos and the smoking habits of workers. PMID:6331497

  19. Porous glasses for optical sensors

    NASA Astrophysics Data System (ADS)

    Dorosz, Dominik; Procyk, Bernadeta

    2006-03-01

    Microporous glasses from the Na II0-B II0 3-Si0 II system can be obtained by appropriate thermal and chemical treatment. During the thermal treatment the separation of the borate phase from the silicon skeleton has been occurred. The borates are in the form small drops joined to each other. In the course of chemical treatment the borates become leached in water, water solutions of acids or basis and the glass becomes porous. Microporous glasses may find application in many branches of science and engineering. The applications depend on the internal arrangement, size and shape of pores. These parameters may be in a wide range modified by a change of the chemical composition. The received porous glass was used as an element in optical fibre NO II sensor. The specific coloration reaction between organic reagents and NO II in the pores was occurred. It is possible to detection of 10-50 ppm NO II level.

  20. Optical Fibre Sensor For Measuring pH In Physiological Range

    NASA Astrophysics Data System (ADS)

    Golunski, Witold; Hypszer, Ryszard; Plucinski, Jerzy

    1990-01-01

    The principle of fibre optic pH sensor operation is given in this paper. PH measurement in 7.0-7.5 range is based on changing of optical property of a indicator. The indicator is sensitive to the hydrogen ion concentration in the water solution. Microspheres of the polymer XAD-2 (a styrene-divinylbenzene copolymer) containing bound phenol red were used as a indicator. Such prepared indicator was inserted in optrode. The optrode was connected with transmitter and receiver by a bundle of glass fibres (multicomponent glass). Transmitter was done by using green LED while receiver construction was based on pin photodiode.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  6. Glass sealing

    SciTech Connect

    Brow, R.K.; Kovacic, L.; Chambers, R.S.

    1996-04-01

    Hernetic glass sealing technologies developed for weapons component applications can be utilized for the design and manufacture of fuel cells. Design and processing of of a seal are optimized through an integrated approach based on glass composition research, finite element analysis, and sealing process definition. Glass sealing procedures are selected to accommodate the limits imposed by glass composition and predicted calculations.

  7. 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

  8. 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

  9. 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.

  10. PRAXIS: low thermal emission high efficiency OH suppressed fibre spectrograph

    NASA Astrophysics Data System (ADS)

    Content, Robert; Bland-Hawthorn, Joss; Ellis, Simon; Gers, Luke; Haynes, Roger; Horton, Anthony; Lawrence, Jon; Leon-Saval, Sergio; Lindley, Emma; Min, Seong-Sik; Shortridge, Keith; Staszak, Nick; Trinh, Christopher; Xavier, Pascal; Zhelem, Ross

    2014-07-01

    PRAXIS is a second generation instrument that follows on from GNOSIS, which was the first instrument using fibre Bragg gratings for OH suppression to be deployed on a telescope. The Bragg gratings reflect the NIR OH lines while being transparent to the light between the lines. This gives in principle a much higher signal-noise ratio at low resolution spectroscopy but also at higher resolutions by removing the scattered wings of the OH lines. The specifications call for high throughput and very low thermal and detector noise so that PRAXIS will remain sky noise limited even with the low sky background levels remaining after OH suppression. The optical and mechanical designs are presented. The optical train starts with fore-optics that image the telescope focal plane on an IFU which has 19 hexagonal microlenses each feeding a multi-mode fibre. Seven of these fibres are attached to a fibre Bragg grating OH suppression system while the others are reference/acquisition fibres. The light from each of the seven OH suppression fibres is then split by a photonic lantern into many single mode fibres where the Bragg gratings are imprinted. Another lantern recombines the light from the single mode fibres into a multi-mode fibre. A trade-off was made in the design of the IFU between field of view and transmission to maximize the signal-noise ratio for observations of faint, compact objects under typical seeing. GNOSIS used the pre-existing IRIS2 spectrograph while PRAXIS will use a new spectrograph specifically designed for the fibre Bragg grating OH suppression and optimised for 1.47 μm to 1.7 μm (it can also be used in the 1.09 μm to 1.26 μm band by changing the grating and refocussing). This results in a significantly higher transmission due to high efficiency coatings, a VPH grating at low incident angle and optimized for our small bandwidth, and low absorption glasses. The detector noise will also be lower thanks to the use of a current generation HAWAII-2RG detector

  11. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors.

    PubMed

    Krishnamurthy, Sriram; Badcock, Rodney A; Machavaram, Venkata R; Fernando, Gerard F

    2016-01-01

    Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from -600 µε (conventional processing without pre-stress) to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to "neutralising" the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E-glass composites.

  12. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors

    PubMed Central

    Krishnamurthy, Sriram; Badcock, Rodney A.; Machavaram, Venkata R.; Fernando, Gerard F.

    2016-01-01

    Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from −600 µε (conventional processing without pre-stress) to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to “neutralising” the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E-glass composites. PMID

  13. 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)

  14. 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

  15. Ultraviolet radiation (UVR) dosimetry system and the use of Ge-doped silica optical fibres

    NASA Astrophysics Data System (ADS)

    Abdul Rahman, Ahmad Taufek; Abu Bakar, Noor Khairunnisa; Chandra Paul, Mukul; Bradley, D. A.

    2014-11-01

    Previous studies have shown that over exposure to ultraviolet radiation (UVR), either from sunlight or artificial sources, can cause severe biological effects including cataracts, photokeratitis and skin cancer. In this respect, there exists the need to introduce a sensitive UV dosimetric material capable of measuring radiation dose to high accuracy in order to deliver UVR safely and efficiently. Present study has focussed on the investigation of the potential thermoluminescent (TL) sensitivity of commercially available germanium (Ge)-doped silica (SiO2) optical fibres subjected to UVR. The main interest of this study is to find out whether these doped SiO2 optical fibres can be used as a sensible integrator of environmental UV exposures. In the present study, commercially available Ge-doped SiO2 optical fibres have been used with a core diameter of 11 μm (CorActive, Canada), 23 μm (Central Glass and Ceramic Research Institute Kolkata, India) and 50 μm (Central Glass and Ceramic Research Institute Kolkata, India) and a cladding diameter of 125±0.1 μm, irradiated over a wide range of UV dose. Results have shown that these fibres exhibit a linear dose response (with correlation coefficient better than 0.9852). The 50 μm fibre produces greater TL response than that obtained for 11- and 23 μm fibres. The TL results are compared with that of the well-established TL dosimeter material lithium fluoride.

  16. 20-Gb/s QPSK transmission over 4km-long holey fiber using a wavelength tunable quantum dot light laser in T-band

    NASA Astrophysics Data System (ADS)

    Murano, Akihiro; Yamada, Shoko; Kanno, Atsushi; Yamamoto, Naokatsu; Sotobayashi, Hideyuki

    2016-02-01

    We successfully demonstrate 10-Gbbaud quadrature phase-shift keying signal transmission over a 4-km-long endlessly single-mode holey fiber using a wavelength-tunable semiconductor quantum dot (QD) laser. The transmission is carried out in the waveband of 1040.72-1070.02 nm with a bandwidth of 7.89 THz, which is broader than conventional wavebands such as the C and L bands. In the study, a QD laser notable for its wavelength stability and tunability is employed for its broad bandwidth availability on the transmission. Observed bit error rates are within a forward error correction limit of 2×10-3 under homodyne coherent detection configuration with offline digital signal processing. The abundant frequency resources in this T band (1000-1260 nm) help increase the capacity of a transmission link using a large number of wavelength channels by the QD laser.

  17. Characterisation of CorGlaes(®) Pure 107 fibres for biomedical applications.

    PubMed

    Colquhoun, Ross; Gadegaard, Nikolaj; Healy, David M; Tanner, K Elizabeth

    2016-10-01

    A degradable ultraphosphate (55 mol % P2O5) quinternary phosphate glass composition has been characterised in terms of its chemical, mechanical and degradation properties both as a bulk material and after drawing into fibres. This glass formulation displayed a large processing window simplifying fibre drawing. The fibres displayed stiffness and strength of 65.5 ± 20.8 GPa and 426±143 MPa. While amorphous discs of the glass displayed a linear dissolution rate of 0.004 mg cm(-2) h(-1) at 37 °C, in a static solution with a reduction in media pH. Once drawn into fibres, the dissolution process dropped the pH to <2 in distilled water, phosphate buffer saline and corrected-simulated body fluid, displaying an autocatalytic effect with >90 % mass loss in 4 days, about seven times faster than anticipated for this solution rate. Only cell culture media was able to buffer the pH taking over a week for full fibre dissolution, however, still four times faster dissolution rate than as a bulk material. However, at early times the development of a HCA layer was seen indicating potential bioactivity. Thus, although initial analysis indicated potential orthopaedic implant applications, autocatalysis leads to accelerating degradation in vitro. PMID:27582069

  18. Durability of waste glass flax fiber reinforced mortar

    SciTech Connect

    Aly, M.; Hashmi, M. S. J.; Olabi, A. G.; Messeiry, M.

    2011-01-17

    The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performance of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.

  19. 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)

  20. 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.

  1. Multimode fibres: a pathway towards deep-tissue fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Plöschner, Martin; Tyc, TomáÅ.¡; Čižmár, TomáÅ.¡

    2015-12-01

    Fluorescence microscopy has emerged as a pivotal platform for imaging in the life sciences. In recent years, the overwhelming success of its different modalities has been accompanied by various efforts to carry out imaging deeper inside living tissues. A key challenge of these efforts is to overcome scattering and absorption of light in such environments. Multiple strategies (e.g. multi-photon, wavefront correction techniques) extended the penetration depth to the current state-of-the-art of about 1000μm at the resolution of approximately 1μm. The only viable strategy for imaging deeper than this is by employing a fibre bundle based endoscope. However, such devices lack resolution and have a significant footprint (1mm in diameter), which prohibits their use in studies involving tissues deep in live animals. We have recently demonstrated a radically new approach that delivers the light in/out of place of interest through an extremely thin (tens of microns in diameter) cylindrical glass tube called a multimode optical fibre (MMF). Not only is this type of delivery much less invasive compared to fibre bundle technology, it also enables higher resolution and has the ability to image at any plane behind the fibre without any auxiliary optics. The two most important limitations of this exciting technology are (i) the lack of bending flexibility and (ii) high demands on computational power, making the performance of such systems slow. We will discuss how to overcome these limitations.

  2. 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)

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

    SciTech Connect

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

    2012-09-30

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

  4. Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    SciTech Connect

    Rybaltovsky, A A; Sokolov, V O; Plotnichenko, V G; Lanin, Aleksei V; Semenov, S L; Dianov, Evgenii M; Gur'yanov, A N; Khopin, V F

    2007-04-30

    The photoinduced room-temperature-stable increase in the refractive index by {approx}5x10{sup -4} at a wavelength of 1.55 {mu}m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms with a phosphosilicate glass core and optical fibres fabricated from them are studied in a broad spectral range from 150 to 5000 nm. The intense induced-absorption band ({approx}800 cm{sup -1}) at 180 nm is found, which strongly affects the formation of the induced refractive index. The quantum-chemical model of a defect related to this band is proposed. (optical fibres)

  5. Hierarchical analysis of the degradation of fibre-reinforced polymers under the presence of void imperfections.

    PubMed

    Liebig, Wilfried V; Schulte, Karl; Fiedler, Bodo

    2016-07-13

    The subject of this work is the investigation of the influence of voids on the mechanical properties of fibre-reinforced polymers (FRPs) under compression loading. To specify the damage accumulation of FRPs in the presence of voids, the complex three-dimensional structure of the composite including voids was analysed and a reduced mechanical model composite was derived. The hierarchical analysis of the model composite on a micro-scale level implies the description of the stress and strain behaviour of the matrix using the photoelasticity technique and digital image correlation technology. These studies are presented along with an analytical examination of the stability of a single fibre. As a result of the experimental and analytical studies, the stiffness of the matrix and fibre as well as their bonding, the initial fibre orientation and the fibre diameter have the highest impact on the failure initiation. All these facts lead to a premature fibre-matrix debonding with ongoing loss of stability of the fibre and followed by kink-band formation. Additional studies on the meso-scale of transparent glass FRPs including a unique void showed that the experiments carried out on the model composites could be transferred to real composites. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242296

  6. Fibre optic sensors for temperature and pressure monitoring in laser ablation: experiments on ex-vivo animal model

    NASA Astrophysics Data System (ADS)

    Tosi, Daniele; Saccomandi, Paola; Schena, Emiliano; Duraibabu, Dinesh B.; Poeggel, Sven; Adilzhan, Abzal; Aliakhmet, Kamilla; Silvestri, Sergio; Leen, Gabriel; Lewis, Elfed

    2016-05-01

    Optical fibre sensors have been applied to perform biophysical measurement in ex-vivo laser ablation (LA), on pancreas animal phantom. Experiments have been performed using Fibre Bragg Grating (FBG) arrays for spatially resolved temperature detection, and an all-glass Extrinsic Fabry-Perot Interferometer (EFPI) for pressure measurement. Results using a Nd:YAG laser source as ablation device, are presented and discussed.

  7. Optical fibres based on natural biological minerals - sea sponge spicules

    SciTech Connect

    Kulchin, Yu N; Voznesenskii, S S; Galkina, A N; Mal'tseva, T L; Nagornyi, I G; Bukin, O A; Gnedenkov, S V; Kuryavyi, V G; Sinebryukhov, S L; Cherednichenko, A I; Drozdov, A L

    2008-01-31

    A complex study of spicules of glass sponges Hyalonema sieboldi and Pheronema sp. is performed. It is shown that skeletal spicules represent a bundle of composite fibres cemented with silicon dioxide, which imparts a high mechanical strength to spicules. The presence of a layered organosilicon structure at the nanometre scale in the spicule cross section gives rise to a periodic spatial modulation of the permittivity of the spicule material, which allows one to treat spicules as one-dimensional photonic crystals. Upon excitation of basal spicules by second-harmonic pulses from a Nd:YAG laser, we observed a considerable increase in the fluorescence intensity in the long-wavelength region with a maximum at 770 nm, saturation and anomalously large fluorescence lifetimes. (fibre optics)

  8. The MANIFEST fibre positioning system for the Giant Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Lawrence, Jon S.; Brown, David M.; Brzeski, Jurek; Case, Scott; Colless, Matthew; Farrell, Tony; Gers, Luke; Gilbert, James; Goodwin, Michael; Jacoby, George; Hopkins, Andrew M.; Ireland, Michael; Kuehn, Kyler; Lorente, Nuria P. F.; Miziarski, Stan; Muller, Rolf; Nichani, Vijay; Rakman, Azizi; Richards, Samuel; Saunders, Will; Staszak, Nick F.; Tims, Julia; Vuong, Minh; Waller, Lew

    2014-08-01

    MANIFEST is a fibre feed system for the Giant Magellan Telescope that, coupled to the seeing-limited instruments GMACS and G-CLEF, offers qualitative and quantitative gains over each instrument's native capabilities in terms of multiplex, field of view, and resolution. The MANIFEST instrument concept is based on a system of semi-autonomous probes called "Starbugs" that hold and position hundreds of optical fibre IFUs under a glass field plate placed at the GMT Cassegrain focal plane. The Starbug probes feature co-axial piezoceramic tubes that, via the application of appropriate AC waveforms, contract or bend, providing a discrete stepping motion. Simultaneous positioning of all Starbugs is achieved via a closed-loop metrology system.

  9. Glass Artworks

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Several NASA technologies have played part in growth and cost containment of studio glass art, among them a foam type insulation developed to meet a need for lightweight material that would reduce flame spread in aircraft fire. Foam comes in several forms and is widely used by glass artists, chiefly as an insulator for the various types of ovens used in glass working. Another Spinoff is alumina crucibles to contain molten glass. Before alumina crucibles were used, glass tanks were made of firebrick which tended to erode under high temperatures and cause impurities; this not only improved quality but made the process more cost effective. One more NASA technology that found its way into glass art working is a material known as graphite board, a special form of graphite originally developed for rocket motor applications. This graphite is used to exact compound angles and creates molds for poured glass artworks of dramatic design.

  10. Glass Research

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.

    1985-01-01

    Research efforts span three general areas of glass science: glass refining, gel-derived glasses, and nucleation and crystallization of glasses. Gas bubbles which are present in a glass product are defects which may render the glass totally useless for the end application. For example, optical glasses, laser host glasses, and a variety of other specialty glasses must be prepared virtually defect free to be employable. Since a major mechanism of bubble removal, buoyant rise, is virtually inoperative in microgravity, glass fining will be especially difficult in space. On the other hand, the suppression of buoyant rise and the ability to perform containerless melting experiments in space allows the opportunity to carry out several unique bubble experiments in space. Gas bubble dissolution studies may be performed at elevated temperatures for large bubbles with negligible bubble motion. Also, bubble nucleation studies may be performed without the disturbing feature of heterogeneous bubble nucleation at the platinum walls. Ground based research efforts are being performed in support of these potential flight experiments.

  11. Crack Detection in Fibre Reinforced Plastic Structures Using Embedded Fibre Bragg Grating Sensors: Theory, Model Development and Experimental Validation

    PubMed Central

    Pereira, G. F.; Mikkelsen, L. P.; McGugan, M.

    2015-01-01

    In a fibre-reinforced polymer (FRP) structure designed using the emerging damage tolerance and structural health monitoring philosophy, sensors and models that describe crack propagation will enable a structure to operate despite the presence of damage by fully exploiting the material’s mechanical properties. When applying this concept to different structures, sensor systems and damage types, a combination of damage mechanics, monitoring technology, and modelling is required. The primary objective of this article is to demonstrate such a combination. This article is divided in three main topics: the damage mechanism (delamination of FRP), the structural health monitoring technology (fibre Bragg gratings to detect delamination), and the finite element method model of the structure that incorporates these concepts into a final and integrated damage-monitoring concept. A novel method for assessing a crack growth/damage event in fibre-reinforced polymer or structural adhesive-bonded structures using embedded fibre Bragg grating (FBG) sensors is presented by combining conventional measured parameters, such as wavelength shift, with parameters associated with measurement errors, typically ignored by the end-user. Conjointly, a novel model for sensor output prediction (virtual sensor) was developed using this FBG sensor crack monitoring concept and implemented in a finite element method code. The monitoring method was demonstrated and validated using glass fibre double cantilever beam specimens instrumented with an array of FBG sensors embedded in the material and tested using an experimental fracture procedure. The digital image correlation technique was used to validate the model prediction by correlating the specific sensor response caused by the crack with the developed model. PMID:26513653

  12. Crack Detection in Fibre Reinforced Plastic Structures Using Embedded Fibre Bragg Grating Sensors: Theory, Model Development and Experimental Validation.

    PubMed

    Pereira, G F; Mikkelsen, L P; McGugan, M

    2015-01-01

    In a fibre-reinforced polymer (FRP) structure designed using the emerging damage tolerance and structural health monitoring philosophy, sensors and models that describe crack propagation will enable a structure to operate despite the presence of damage by fully exploiting the material's mechanical properties. When applying this concept to different structures, sensor systems and damage types, a combination of damage mechanics, monitoring technology, and modelling is required. The primary objective of this article is to demonstrate such a combination. This article is divided in three main topics: the damage mechanism (delamination of FRP), the structural health monitoring technology (fibre Bragg gratings to detect delamination), and the finite element method model of the structure that incorporates these concepts into a final and integrated damage-monitoring concept. A novel method for assessing a crack growth/damage event in fibre-reinforced polymer or structural adhesive-bonded structures using embedded fibre Bragg grating (FBG) sensors is presented by combining conventional measured parameters, such as wavelength shift, with parameters associated with measurement errors, typically ignored by the end-user. Conjointly, a novel model for sensor output prediction (virtual sensor) was developed using this FBG sensor crack monitoring concept and implemented in a finite element method code. The monitoring method was demonstrated and validated using glass fibre double cantilever beam specimens instrumented with an array of FBG sensors embedded in the material and tested using an experimental fracture procedure. The digital image correlation technique was used to validate the model prediction by correlating the specific sensor response caused by the crack with the developed model. PMID:26513653

  13. Crack Detection in Fibre Reinforced Plastic Structures Using Embedded Fibre Bragg Grating Sensors: Theory, Model Development and Experimental Validation.

    PubMed

    Pereira, G F; Mikkelsen, L P; McGugan, M

    2015-01-01

    In a fibre-reinforced polymer (FRP) structure designed using the emerging damage tolerance and structural health monitoring philosophy, sensors and models that describe crack propagation will enable a structure to operate despite the presence of damage by fully exploiting the material's mechanical properties. When applying this concept to different structures, sensor systems and damage types, a combination of damage mechanics, monitoring technology, and modelling is required. The primary objective of this article is to demonstrate such a combination. This article is divided in three main topics: the damage mechanism (delamination of FRP), the structural health monitoring technology (fibre Bragg gratings to detect delamination), and the finite element method model of the structure that incorporates these concepts into a final and integrated damage-monitoring concept. A novel method for assessing a crack growth/damage event in fibre-reinforced polymer or structural adhesive-bonded structures using embedded fibre Bragg grating (FBG) sensors is presented by combining conventional measured parameters, such as wavelength shift, with parameters associated with measurement errors, typically ignored by the end-user. Conjointly, a novel model for sensor output prediction (virtual sensor) was developed using this FBG sensor crack monitoring concept and implemented in a finite element method code. The monitoring method was demonstrated and validated using glass fibre double cantilever beam specimens instrumented with an array of FBG sensors embedded in the material and tested using an experimental fracture procedure. The digital image correlation technique was used to validate the model prediction by correlating the specific sensor response caused by the crack with the developed model.

  14. Holey topological thermoelectrics

    NASA Astrophysics Data System (ADS)

    Tretiakov, O. A.; Abanov, Ar.; Sinova, Jairo

    2011-09-01

    We study the thermoelectric properties of three-dimensional topological insulators with many holes (or pores) in the bulk. We show that at high density of these holes, the thermoelectric figure of merit, ZT, can be large due to the contribution of the conducting surfaces and the suppressed phonon thermal conductivity. The maximum efficiency can be tuned by an induced gap in the surface states dispersion through tunneling or external magnetic fields. The large values of ZT, much higher than unity for reasonable parameters, make this system a strong candidate for applications in heat management of nanodevices, especially at low temperatures.

  15. Vegetable fibres from agricultural residues as thermo-mechanical reinforcement in recycled polypropylene-based green foams.

    PubMed

    Ardanuy, Mònica; Antunes, Marcelo; Velasco, José Ignacio

    2012-02-01

    Novel lightweight composite foams based on recycled polypropylene reinforced with cellulosic fibres obtained from agricultural residues were prepared and characterized. These composites, initially prepared by melt-mixing recycled polypropylene with variable fibre concentrations (10-25 wt.%), were foamed by high-pressure CO(2) dissolution, a clean process which avoids the use of chemical blowing agents. With the aim of studying the influence of the fibre characteristics on the resultant foams, two chemical treatments were applied to the barley straw in order to increase the α-cellulose content of the fibres. The chemical composition, morphology and thermal stability of the fibres and composites were analyzed. Results indicate that fibre chemical treatment and later foaming of the composites resulted in foams with characteristic closed-cell microcellular structures, their specific storage modulus significantly increasing due to the higher stiffness of the fibres. The addition of the fibres also resulted in an increase in the glass transition temperature of PP in both the solid composites and more significantly in the foams.

  16. 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)

  17. A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings

    NASA Astrophysics Data System (ADS)

    Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

    2015-03-01

    Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  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. 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.

  4. Engineering rare-earth-doped heavy metal oxide glasses for 2-5 μm lasers

    NASA Astrophysics Data System (ADS)

    Richards, Billy D. O.; Jha, Animesh; Dorofeev, Vitaly; Manzur, Tariq

    2010-04-01

    The electronic states in trivalent rare-earth ions offer an excellent opportunity for designing efficient fibre and bulk lasers for atmospheric remote sensing and LIDAR technology. The first part of this review article focuses on engineering passive fibres for 2-5 μm transmission. The fabrication of single-mode tungsten tellurite optical fibres from high purity bulk glass rods is described. Fibres with a numerical aperture of 0.1 and core diameter of 10+/-2 μm have been drawn using suction and rod-in-tube techniques of fibre preform fabrication. Losses of 2.3 dBm-1 at 974 nm have been measured. These fibres are of interest for use as passive transmission fibre or active fibres for lasing in the 2-5 μm spectral region. The use of heavy metal oxides in the fabrication of glass leads to extended infrared transmission. In the 2nd part of the review we compare the slope efficiencies of Tm3+ and Tm3+/Ho3+ doped glasses and fibres for 1950-2080 nm lasers using a range of pumping schemes in tellurite and germanium oxide hosts. We also explain the importance of choosing 1950-2080 nm tunable lasers as a pump source for stimulated emission at longer wavelengths.

  5. Optical fibre communications and sensing system experiments for undergraduate photonics laboratories

    NASA Astrophysics Data System (ADS)

    Wild, Graham; Swan, Geoff I.

    2011-12-01

    Experiments in photonics tend to be reserved for postgraduate laboratories, where suitable equipment and resources are available. Simple optical fibre experiments may be included in some undergraduate programs, possibly utilising polymer optical fibres with LEDs and phototransistors, or with the use of bulk optical components and glass optical fibre elements. However, real optical fibre communication systems and optical fibre sensing systems utilise more complex devices, such as optical fibre Bragg gratings. With the availability of optical components in the 850nm wavelength range, a variety of practical systems can be realised using industry standard components. We show how to mitigate a large portion of the cost associated with the implementation of experiments utilising these 850nm components. The limiting factor associated with the implementation of 1550nm based systems is the cost associated with spectral measurements in this wavelength range. Given a bench top optical spectrum analyser costs $10,000s; this is not something that can be made available to students in undergraduate laboratories in bulk. The solution was to make use of the new low cost USB based spectrometers, available from a number of manufacturers. In combination with devices such as couplers, circulators, isolators, wavelength division multiplexing filters, and Bragg gratings, all operating in the 850nm, a number of different sensing and communications systems can be realised.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  7. Compressive and Tensile Behaviours of PLLA Matrix Composites Reinforced with Randomly Dispersed Flax Fibres

    NASA Astrophysics Data System (ADS)

    Roussière, Fabrice; Baley, Christophe; Godard, Grégory; Burr, Dominique

    2012-04-01

    Nowadays, the ecological footprint of a material is becoming tremendously important. The Poly l-Lactide Acid (PLLA) matrix composites reinforced by randomly scattered flax fibres have mechanical properties similar to polyester/glass composites [1], lower environmental impacts and can be compost at the end of their lives. In this study, the mechanical characterization of biocomposites has been pushed further with the determination of the compressive and tensile properties. Furthermore, the mechanical properties of single flax fibres have been measured and implemented in a micro-mechanical estimation of the composite elastic modulus. Tensile and compressive stiffness determined by the mechanical analyses show very good correlations with the mathematical estimation.

  8. 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

  9. 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.

  10. Friction and wear of human hair fibres

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  11. Mutagenesis by man-made mineral fibres in the lung of rats.

    PubMed

    Topinka, J b; Loli, P; Dusinská, M; Hurbánková, M; Kováciková, Z; Volkovová, K; Kazimírová, A; Barancoková, M; Tatrai, E; Wolff, T; Oesterle, D; Kyrtopoulos, S A; Georgiadis, P

    2006-03-20

    The potential of two asbestos substitute mineral fibres--rock (stone) wool RW1 and glass wool MMVF10--to induce gene mutations, DNA strand breaks, inflammation and oxidative stress has been studied in rats. Male homozygous lamda-lacI transgenic F344 rats were intratracheally instilled with single doses of 1 and 2 mg/animal of fibres or with multiple doses of 2 mg/animal administered weekly on four consecutive weeks (8 mg in total). Exposure to RW1 fibres for 16 weeks significantly increased mutant frequency (MF) in the lung in a dose-dependent manner, while MMVF10 fibres did not exhibit any increase of MF at any dose. RW1 fibres gave a significant increase of MF at a dose of 1 mg. Four weeks after instillation, neither the single nor the multiple doses significantly increased MF for both fibre types. To investigate mechanisms for induction of mutations, other genotoxicity markers and parameters of inflammatory and oxidative damage were determined in relation to MF. A weak correlation of mutagenicity data with other genotoxicity parameters studied was observed. DNA strand breaks as measured by comet assay were increased in alveolar macrophages and lung epithelial cells of RW1 and MMVF10 treated rats. RWl fibres caused more extensive lung inflammation as measured by release of neutrophils into broncho-alveolar lavage fluid than MMVF10 fibres. The effects were observed 16 weeks post-exposure, indicating a persistence of the pathogenic process during the exposure period. Only minor differences in the extent of inflammatory processes were observed between the doses of 2 mg and 4 x 2 mg, suggesting that any threshold for inflammation lies below the dose of 2 mg. With the exception of the highest dose of MMVF10 fibres after 16 weeks of exposure, no significant increase of oxidative damage as measured by levels of malondialdehyde in lung tissue was observed. MMVF10 fibres caused weaker inflammation in the lung of rats and did not exhibit any mutagenic effect. We conclude

  12. Mutagenesis by man-made mineral fibres in the lung of rats.

    PubMed

    Topinka, J b; Loli, P; Dusinská, M; Hurbánková, M; Kováciková, Z; Volkovová, K; Kazimírová, A; Barancoková, M; Tatrai, E; Wolff, T; Oesterle, D; Kyrtopoulos, S A; Georgiadis, P

    2006-03-20

    The potential of two asbestos substitute mineral fibres--rock (stone) wool RW1 and glass wool MMVF10--to induce gene mutations, DNA strand breaks, inflammation and oxidative stress has been studied in rats. Male homozygous lamda-lacI transgenic F344 rats were intratracheally instilled with single doses of 1 and 2 mg/animal of fibres or with multiple doses of 2 mg/animal administered weekly on four consecutive weeks (8 mg in total). Exposure to RW1 fibres for 16 weeks significantly increased mutant frequency (MF) in the lung in a dose-dependent manner, while MMVF10 fibres did not exhibit any increase of MF at any dose. RW1 fibres gave a significant increase of MF at a dose of 1 mg. Four weeks after instillation, neither the single nor the multiple doses significantly increased MF for both fibre types. To investigate mechanisms for induction of mutations, other genotoxicity markers and parameters of inflammatory and oxidative damage were determined in relation to MF. A weak correlation of mutagenicity data with other genotoxicity parameters studied was observed. DNA strand breaks as measured by comet assay were increased in alveolar macrophages and lung epithelial cells of RW1 and MMVF10 treated rats. RWl fibres caused more extensive lung inflammation as measured by release of neutrophils into broncho-alveolar lavage fluid than MMVF10 fibres. The effects were observed 16 weeks post-exposure, indicating a persistence of the pathogenic process during the exposure period. Only minor differences in the extent of inflammatory processes were observed between the doses of 2 mg and 4 x 2 mg, suggesting that any threshold for inflammation lies below the dose of 2 mg. With the exception of the highest dose of MMVF10 fibres after 16 weeks of exposure, no significant increase of oxidative damage as measured by levels of malondialdehyde in lung tissue was observed. MMVF10 fibres caused weaker inflammation in the lung of rats and did not exhibit any mutagenic effect. We conclude

  13. Metallic glasses.

    PubMed

    Greer, A L

    1995-03-31

    Amorphous metallic alloys, relative newcomers to the world of glasses, have properties that are unusual for solid metals. The metallic glasses, which exist in a very wide variety of compositions, combine fundamental interest with practical applications. They also serve as precursors for exciting new nanocrystalline materials. Their magnetic (soft and hard) and mechanical properties are of particular interest.

  14. 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)

  15. Three-dimensional nitrogen doped holey reduced graphene oxide framework as metal-free counter electrodes for high performance dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Mei; Zhang, Jindan; Li, Songmei; Meng, Yanbing; Liu, Jianhua

    2016-03-01

    Three-dimensional nitrogen doped holey reduced graphene oxide framework (NHGF) with hierarchical porosity structure was developed as high-performance metal-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). With plenty of exposed active sites, efficient electron and ion transport pathways as well as a high surface hydrophilicity, NHGF-CE exhibits good electrocatalytic performances for I- /I3- redox couple and a low charge transfer resistance (Rct). The Rct of NHGF-CE is 1.46 Ω cm2, which is much lower than that of Pt-CE (4.02 Ω cm2). The DSSC with NHGF-CE reaches a power conversion efficiency of 5.56% and a fill factor of 65.5%, while those of the DSSC with Pt-CE are only 5.45% and 62.3%, respectively. The achievement of the highly efficient 3D structure presents a potential way to fabricate low-cost and metal-free counter electrodes with excellent performance.

  16. 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.

  17. Cyclic fatigue behaviour of fibre reinforced rubber-toughened nylon composite materials

    NASA Astrophysics Data System (ADS)

    Pinot, L.; Gomina, M.; Jernot, J.-P.; Moreau, R.; Nakache, E.

    2005-03-01

    The effects of the amount of rubber, the concentration of fibres and the state of the fibre/matrix interface upon the mechanical behaviour of glass fibre/rubber-toughened nylon ternary blends are checked. First, monotonic tensile tests were carried out on different intermediate materials and then on the ternary blends to derive the stress-strain curves and document the damage mechanisms. Cyclic fatigue tests were implemented on tensile specimens and the results were analysed in terms of the reduction of the Young's modulus, the increase of the hysteresis energy rate in the stress-strain diagram and the temperature rise. These findings were correlated to fractographic observations to assess the role of the different constituents.

  18. Photodarkening study of gratings written into rare-earth doped optical fibres using a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Åslund, Mattias L.; Jovanovic, Nemanja; Groothoff, Nathaniel; Canning, John; Marshall, Graham D.; Jackson, Stuart D.; Fuerbach, Alex; Withford, Michael J.

    2007-12-01

    A well-known side-effect from fibre Bragg grating UV-fabrication is short wavelength attenuation, where irradiation with laser light, usually in the UV, generates both defect-induced absorption and scattering. These losses are especially problematic for high power optical fibre lasers operating at shorter wavelengths where resonant assisted coupling into the glass matrix through the rare earth ions can take place (e.g. Yb 3+). In this, work we present a study of the relative magnitude of short wavelength attenuation in gratings written by the point-by-point method using a Ti-sapphire femtosecond laser operating at 800 nm. Such gratings are very stable and have been used as the feedback elements in fibre lasers with powers exceeding 100 W. We show that the scattering properties responsible for the attenuation are analogous to those associated with type II gratings written with UV lasers.

  19. Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats.

    PubMed

    Topinka, J; Loli, P; Hurbáková, M; Kováciková, Z; Volkovová, K; Wolff, T; Oesterle, D; Kyrtopoulos, S A; Georgiadis, P

    2006-03-20

    In an attempt to examine the interaction of man-made mineral fibres with benzo[a]pyrene (B[a]P), homozygous X-lacI transgenic F344 rats were intratracheally treated with rock (stone) wool RWI and glass wool MMVF 10 fibres together with B[a]P. To analyze the induction of gene mutations by fibres and B[a]P in lung, single doses of 1 and 2 mg fibres/animal or multiple doses of 2 mg fibres/animal were administered weekly on 4 consecutive weeks (total dose 8 mg/animal). B[a]P (10 mg/animal) was administered either simultaneously with fibres (for single dose treatment with fibres) or together with the last fiber treatment (for multiple dose treatment with fibres). Animals were scarified 4 weeks after the last treatment. Benzo[a]pyrene administered simultaneously with RW1 fibres exhibited a strong synergistic effect on mutagenicity, the observed mutant frequency (MF) being more than three-fold higher than the net sum of the MF induced after separate administration of both agents. Our data suggest that DNA adducts induced by simultaneous B[a]P and fiber treatment lead to a strong increase in mutatant frequencies. PMID:16375931

  20. Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats.

    PubMed

    Topinka, J; Loli, P; Hurbáková, M; Kováciková, Z; Volkovová, K; Wolff, T; Oesterle, D; Kyrtopoulos, S A; Georgiadis, P

    2006-03-20

    In an attempt to examine the interaction of man-made mineral fibres with benzo[a]pyrene (B[a]P), homozygous X-lacI transgenic F344 rats were intratracheally treated with rock (stone) wool RWI and glass wool MMVF 10 fibres together with B[a]P. To analyze the induction of gene mutations by fibres and B[a]P in lung, single doses of 1 and 2 mg fibres/animal or multiple doses of 2 mg fibres/animal were administered weekly on 4 consecutive weeks (total dose 8 mg/animal). B[a]P (10 mg/animal) was administered either simultaneously with fibres (for single dose treatment with fibres) or together with the last fiber treatment (for multiple dose treatment with fibres). Animals were scarified 4 weeks after the last treatment. Benzo[a]pyrene administered simultaneously with RW1 fibres exhibited a strong synergistic effect on mutagenicity, the observed mutant frequency (MF) being more than three-fold higher than the net sum of the MF induced after separate administration of both agents. Our data suggest that DNA adducts induced by simultaneous B[a]P and fiber treatment lead to a strong increase in mutatant frequencies.

  1. Glass microspheres

    SciTech Connect

    Day, D.E.; Ehrhardt, G.J.

    1988-12-06

    This patent describes a glass microsphere having a diameter of about 54 micrometers or less and adapted for radiation therapy of a mammal. The glass consists of essentially an yttrium oxide-aluminosilicate glass composition lying substantially within a quadrilateral region of the ternary composition diagram of the yttria-alumina-silica system, the quadrilateral region being defined by its four corners having the following combination of weight proportions of the components: 20% silica, 10% alumina, 70% yttria; 70% silica, 10% alumina, 20% yttria; 70% silica, 20% alumina, 10% yttria; and 20% silica, 45% alumina, 35% yttria, the glass having a chemical durability such that subsequent to irradiation and administration of the microsphere to the mammal, the mircosphere will not release a significant amount of yttrium-90 into the mammal's system.

  2. Glass electrolytes

    SciTech Connect

    Not Available

    1984-06-25

    The objective of this research is a glass electrolyte for use in sodium/sulfur batteries that has a low resistivity (100 ohm-cm at 300/sup 0/C) and is stable in the cell environment. Experiments in this program are focussed on glasses in the quaternary system: soda, alumina, zirconia and silica. The FY 1983 research on glass analogs of NASICON, parallel thermodynamic calculations, and a review of the literature in the areas of glass conductivity and corrosion resistance led to selection of this system for more detailed investigation. The main program elements are: (1) conductivity measurements at 300 to 500/sup 0/C; (2) differential thermal analysis for determination of glass-transition and crystallization temperatures; (3) static corrosion tests at 400/sup 0/C using Na, Na/sub 2/S/sub 4/, and S; (4) mechanical strength and fracture toughness measurements; and (5) sodium/sulfur cell tests at 350/sup 0/C. Elements (1) and (2) are nearly completed; element (3) is being initiated using the glasses prepared for (1) and (2), and elements (4) and (5) will begin in the first and second quarters of FY 1985, respectively. Fourteen quaternary glasses having a broad range of compositions have been made. The resistivities of these glasses at 300/sup 0/C extended from 130 to 3704 ohm-cm; the activation energies for conduction extended from 0.488 to 0.684 eV, and the glass transition temperatures extended from 397 to 685/sup 0/C. Through a multiple linear regression analysis of these data response surfaces were generated for resistivity, activation energy for conduction, and glass transition temperature over the composition region within the quaternary system that is bounded by SiO/sub 2/, Na/sub 2/O/sub 3/, Na/sub 2/AlO/sub 4/ and Na/sub 2/ZrO/sub 3/. These response surfaces indicated a new region of high conductivity and high glass transition temperature in the neighborhood of 42% soda, 31% silica and 27% alumina plus zirconia.

  3. 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.

  4. Numerical rate equation modelling of a 1.61 μm pumped ~2 μm Tm 3+-doped tellurite fibre laser

    NASA Astrophysics Data System (ADS)

    Richards, Billy D. O.; Evans, Craig A.; Ikonić, Zoran; Harrison, Paul; Tsang, Yuen H.; Binks, David J.; Lousteau, Joris; Jha, Animesh

    2008-04-01

    Near- and mid-infrared fibre lasers find many applications in areas such as remote and chemical sensing, lidar and medicine, and tellurite fibres offer advantages over other common fibre glasses such a lower phonon energy and higher rare-earth ion solubility than silicate glasses, and greater chemical and environmental stability than fluoride glasses. Rate equation modelling is a very useful tool for the characterisation and performance prediction of new rare earth transitions in these novel fibre materials. We present the numerical rate equation modelling results for a ~2 μm Tm 3+-doped tellurite fibre laser when pumped with a 1.6 μm Er 3+/Yb 3+-doped double-clad silica fibre laser. A maximum slope efficiency of 76% with respect to launched pump power was achieved in the experimental fibre laser set up with a 32 cm long fibre. The high slope efficiency is very close to the Stokes efficiency limit of ~82% which is due to the in-band pumping scheme employed and the lack of pump excited state absorption. The two-level rate equations involving absorption and emission between the Tm 3+: 3H 6 and 3F 4 levels have been solved iteratively using a fourth-order Runge-Kutta algorithm and the results compared with the experimental results. For the 32 cm fibre with output coupler reflectivities of 12%, 50%, 70% and 90%, the respective theoretical slope efficiencies of 73%, 64%, 53% and 29% are in very good agreement with the experimentally measured values of 76%, 60%, 48% and 33%.

  5. Role of oxygen hole centres in the photodarkening of ytterbium-doped phosphosilicate fibre

    SciTech Connect

    Rybaltovsky, A A; Bobkov, K K; Likhachev, M E; Bubnov, M M; Dianov, E M; Umnikov, A A; Lipatov, D S; Gur'yanov, A N; Romanov, A N; Sulimov, V B

    2013-11-30

    We have studied the photodarkening in active fibres with an ytterbium-doped phosphosilicate glass core under IR irradiation with a pump source (920 nm) and UV irradiation (193 nm). Analysis of absorption and luminescence spectra suggests that such irradiations produce phosphorus – oxygen – hole centres (P-OHCs) in the core glass network and lead to the reduction of the ytterbium ions to a divalent state (Yb{sup 2+}). The photoinduced optical loss in the fibres in the visible range (400 – 700 nm) is mainly due to absorption by the P-OHCs. A quantum-mechanical model is proposed for P-OHC and Yb{sup 2+} formation. (nonlinear optical phenomena)

  6. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications.

    PubMed

    Ward, Jonathan M; Yang, Yong; Nic Chormaic, Síle

    2016-01-01

    We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated. PMID:27121151

  7. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications

    NASA Astrophysics Data System (ADS)

    Ward, Jonathan M.; Yang, Yong; Nic Chormaic, Síle

    2016-04-01

    We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated.

  8. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications

    PubMed Central

    Ward, Jonathan M.; Yang, Yong; Nic Chormaic, Síle

    2016-01-01

    We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated. PMID:27121151

  9. 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.

  10. 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

  11. Models for guidance in kagome-structured hollow-core photonic crystal fibres.

    PubMed

    Pearce, G J; Wiederhecker, G S; Poulton, C G; Burger, S; St J Russell, P

    2007-10-01

    We demonstrate by numerical simulation that the general features of the loss spectrum of photonic crystal fibres (PCF) with a kagome structure can be explained by simple models consisting of thin concentric hexagons or rings of glass in air. These easily analysed models provide increased understanding of the mechanism of guidance in kagome PCF, and suggest ways in which the high-loss resonances in the loss spectrum may be shifted.

  12. Nanostructured optical fibre arrays for high-density biochemical sensing and remote imaging.

    PubMed

    Deiss, F; Sojic, N; White, D J; Stoddart, P R

    2010-01-01

    Optical fibre bundles usually comprise a few thousand to tens of thousands of individually clad glass optical fibres. The ordered arrangement of the fibres enables coherent transmission of an image through the bundle and therefore enables analysis and viewing in remote locations. In fused bundles, this architecture has also been used to fabricate arrays of various micro to nano-scale surface structures (micro/nanowells, nanotips, triangles, etc.) over relatively large areas. These surface structures have been used to obtain new optical and analytical capabilities. Indeed, the imaging bundle can be thought of as a "starting material" that can be sculpted by a combination of fibre drawing and selective wet-chemical etching processes. A large variety of bioanalytical applications have thus been developed, ranging from nano-optics to DNA nanoarrays. For instance, nanostructured optical surfaces with intrinsic light-guiding properties have been exploited as surface-enhanced Raman scattering (SERS) platforms and as near-field probe arrays. They have also been productively associated with electrochemistry to fabricate arrays of transparent nanoelectrodes with electrochemiluminescent imaging properties. The confined geometry of the wells has been loaded with biosensing materials and used as femtolitre-sized vessels to detect single molecules. This review describes the fabrication of high-density nanostructured optical fibre arrays and summarizes the large range of optical and bioanalytical applications that have been developed, reflecting the versatility of this ordered light-guiding platform.

  13. Self-Sensing Composites: In-Situ Detection of Fibre Fracture

    PubMed Central

    Malik, Shoaib A.; Wang, Liwei; Curtis, Paul T.; Fernando, Gerard F.

    2016-01-01

    The primary load-bearing component in a composite material is the reinforcing fibres. This paper reports on a technique to study the fracture of individual reinforcing fibres or filaments in real-time. Custom-made small-diameter optical fibres with a diameter of 12 (±2) micrometres were used to detect the fracture of individual filaments during tensile loading of unreinforced bundles and composites. The unimpregnated bundles were end-tabbed and tensile tested to failure. A simple technique based on resin-infusion was developed to manufacture composites with a negligible void content. In both cases, optical fibre connectors were attached to the ends of the small-diameter optical fibre bundles to enable light to be coupled into the bundle via one end whilst the opposite end was photographed using a high-speed camera. The feasibility of detecting the fracture of each of the filaments in the bundle and composite was demonstrated. The in-situ damage detection technique was also applied to E-glass bundles and composites; this will be reported in a subsequent publication. PMID:27136555

  14. 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)

  15. 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.

  16. 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)

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Pinhole Glasses

    NASA Astrophysics Data System (ADS)

    Colicchia, Giuseppe; Hopf, Martin; Wiesner, Hartmut; Zollman, Dean

    2008-01-01

    Eye aberrations are commonly corrected by lenses that restore vision by altering rays before they pass through the cornea. Some modern promoters claim that pinhole glasses are better than conventional lenses in correcting all kinds of refractive defects such as myopia (nearsighted), hyperopia (farsighted), astigmatisms, and presbyopia. Do pinhole glasses really give better vision? Some ways to use this question for motivation in teaching optics have been discussed. For this column we include a series of experiments that students can complete using a model of the eye and demonstrate issues related to pinhole vision correction.

  4. Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

    SciTech Connect

    Bobkov, K K; Rybaltovsky, A A; Vel'miskin, V V; Likhachev, M E; Bubnov, M M; Dianov, E M; Umnikov, A A; Gur'yanov, A N; Vechkanov, N N; Shestakova, I A

    2014-12-31

    We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicate glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)

  5. Mechanisms of optical losses in Bi:SiO2 glass fibers.

    PubMed

    Zlenko, Alexander S; Mashinsky, Valery M; Iskhakova, Ludmila D; Semjonov, Sergey L; Koltashev, Vasiliy V; Karatun, Nikita M; Dianov, Evgeny M

    2012-10-01

    The mechanisms of optical losses in bismuth-doped silica glass (Bi:SiO(2)) and fibers were studied. It was found that in the fibers of this composition the up-conversion processes occur even at bismuth concentrations lower than 0.02 at.%. Bi:SiO(2) core holey fiber drawn under oxidizing conditions was investigated. The absorption spectrum of this fiber has no bands of the bismuth infrared active center. Annealing of this fiber under reducing conditions leads to the formation of the IR absorption bands of the bismuth active center (BAC) and to the simultaneous growth of background losses. Under the realized annealing conditions (argon atmosphere, T(max) = 1100°C, duration 30 min) the BAC concentration reaches its maximum and begins to decrease in the process of excessive Bi reduction, while the background losses only increase. It was shown that the cause of these background losses is the absorption of light by nanoparticles of metallic bismuth formed in bismuth-doped glasses as a result of reduction of a part of the bismuth ions to Bi(0) and their following aggregation. The growth of background losses occurs owing to the increase of the concentration and the size of the metallic bismuth nanoparticles.

  6. 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.

  7. Voltage clamp experiments on ventricular myocardial fibres

    PubMed Central

    Beeler, G. W.; Reuter, H.

    1970-01-01

    1. A voltage clamp method utilizing a sucrose gap and glass microelectrodes was developed and used to study dog ventricular myocardial fibre bundles. The limitations and the reliability of this method are demonstrated by a series of tests. 2. A dynamic sodium current, excited at membrane potentials more positive than -65 mV, was measured. The equilibrium potential for this large, rapid inward current depends directly on [Na]o, shifting 29·0 ± 2·3 mV (± S.E. of mean), as opposed to a theoretically expected value of 30·6 mV, when [Na]o is reduced to 31% of normal. 3. Sodium current is inactivated by conditioning depolarizations. Complete inactivation occurs with conditioning potentials more positive than -45 mV, and 50% inactivation occurs at about -55 mV. The location of the inactivation curve shifts along the voltage axis, when [Ca]o is varied between 0·2 and 7·2 mM. 4. A second, much smaller and slower net inward current, with a threshold around -30 mV, and an equilibrium potential above +40 mV was also observed. 5. The `steady-state' current—voltage relationship (after 300-600 msec) exhibits inward-going (anomalous) rectification with negative slope between -50 and -25 mV. 6. A small, very slowly developing component of outward current was observed at inside positive potentials. The equilibrium potential for this current, although slightly dependent on [K]o, is neither identical with the potassium equilibrium potential nor with the resting potential in normal Tyrode solution. 7. Anatomical limitations, primarily resistance in the extracellular space within the bundle, prevent complete characterization of the rapid, large sodium current, but do not limit the application of the clamp method to the study of other, smaller and slower currents. The evidence for this is discussed extensively in the Appendix. PMID:5503866

  8. 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)

  9. Pinhole Glasses

    ERIC Educational Resources Information Center

    Colicchia, Giuseppe; Hopf, Martin; Wiesner, Hartmut; Zollman, Dean

    2008-01-01

    Eye aberrations are commonly corrected by lenses that restore vision by altering rays before they pass through the cornea. Some modern promoters claim that pinhole glasses are better than conventional lenses in correcting all kinds of refractive defects such as myopia (nearsighted), hyperopia (farsighted), astigmatisms, and presbyopia. Do pinhole…

  10. 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).

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors.

    PubMed

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-07-13

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry-Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2-10 nm/kPa and a resolution of better than ΔP = 10 Pa protect (0.1 cm H2O). A static pressure test in 38 cm H2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k = 10.7 pm/K, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes.

  17. Long Fibre Composite Modelling Using Cohesive User's Element

    NASA Astrophysics Data System (ADS)

    Kozák, Vladislav; Chlup, Zdeněk

    2010-09-01

    The development glass matrix composites reinforced by unidirectional long ceramic fibre has resulted in a family of very perspective structural materials. The only disadvantage of such materials is relatively high brittleness at room temperature. The main micromechanisms acting as toughening mechanism are the pull out, crack bridging, matrix cracking. There are other mechanisms as crack deflection etc. but the primer mechanism is mentioned pull out which is governed by interface between fibre and matrix. The contribution shows a way how to predict and/or optimise mechanical behaviour of composite by application of cohesive zone method and write user's cohesive element into the FEM numerical package Abaqus. The presented results from numerical calculations are compared with experimental data. Crack extension is simulated by means of element extinction algorithms. The principal effort is concentrated on the application of the cohesive zone model with the special traction separation (bridging) law and on the cohesive zone modelling. Determination of micro-mechanical parameters is based on the combination of static tests, microscopic observations and numerical calibration procedures.

  18. Optical fibre biosensors using enzymatic transducers to monitor glucose

    NASA Astrophysics Data System (ADS)

    Scully, P. J.; Betancor, L.; Bolyo, J.; Dzyadevych, S.; Guisan, J. M.; Fernández-Lafuente, R.; Jaffrezic-Renault, N.; Kuncová, G.; Matejec, V.; O'Kennedy, B.; Podrazky, O.; Rose, K.; Sasek, L.; Young, J. S.

    2007-10-01

    The construction and performance of a novel enzyme based optical sensor for in situ continuous monitoring of glucose in biotechnological production processes is presented. Sensitive optical coatings are formed from inorganic-organic hybrid polymers (ORMOCER®sORMOCER®: Trademark of Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. in Germany.) combined with a flurophore (ruthenium complex) and an enzyme, and applied to lenses, declad polymer optical fibre (POF) and polymer clad silica fibre (PCS). The enzyme, glucose oxidase, catalyzes oxidization of glucose to gluconic acid by depleting oxygen. Oxygen consumption is determined by measuring the fluorescence lifetime of metal organic ruthenium complexes which are quenched by oxygen. The coatings developed were designed to adhere to glass and polymer surfaces, to be compatible with enzymes and ruthenium complexes, and were demonstrated both as double- and single-layer structures. The sensor response to gaseous oxygen, dissolved oxygen and dissolved glucose was measured via fluorescence lifetime changes. A best detection limit of 0.5% (vol) has been determined for gaseous O2 with selected ORMOCER® sensing layers. Glucose concentrations were measured to a detection limit of 0.1 mmol L-1 over a range up to 30 mmol L-1. The sensor was usable for 30 days in a bioreactor. The opto-electronic instrumentation and performance in laboratory bioreactors and in an industrial reactor are evaluated.

  19. Long Fibre Composite Modelling Using Cohesive User's Element

    SciTech Connect

    Kozak, Vladislav; Chlup, Zdenek

    2010-09-30

    The development glass matrix composites reinforced by unidirectional long ceramic fibre has resulted in a family of very perspective structural materials. The only disadvantage of such materials is relatively high brittleness at room temperature. The main micromechanisms acting as toughening mechanism are the pull out, crack bridging, matrix cracking. There are other mechanisms as crack deflection etc. but the primer mechanism is mentioned pull out which is governed by interface between fibre and matrix. The contribution shows a way how to predict and/or optimise mechanical behaviour of composite by application of cohesive zone method and write user's cohesive element into the FEM numerical package Abaqus. The presented results from numerical calculations are compared with experimental data. Crack extension is simulated by means of element extinction algorithms. The principal effort is concentrated on the application of the cohesive zone model with the special traction separation (bridging) law and on the cohesive zone modelling. Determination of micro-mechanical parameters is based on the combination of static tests, microscopic observations and numerical calibration procedures.

  20. Obsidianus lapis rugosity and hardness determination: fibre laser craftsmanship

    NASA Astrophysics Data System (ADS)

    Aguilar-Morales, A. I.; Velazquez-Gonzalez, J. S.; Marrujo-García, S.; Reyes-Sanchez, J. I.; Alvarez-Chávez, J. A.

    2014-05-01

    Obsidianus lapis is a volcanic rock that has been worked into tools for cutting or weaponry by Teotihuacan people for hundreds of years. Currently it is used in jewelry or for house decorative items such as elaborated sculptures. From the physico-chemical properties point of view, obsidianus lapis is considered a glass as its composition is 80% silicon dioxide. In México there are different kinds of obsidianus lapis according to its colour: rainbow, black, brown, red, silver, golden and snowflake. The traditional grinding process for working with obsidianus lapis includes fixed grinders and sandpaper for the polishing process, where the craftsman grinds the rock manually obtaining a variety of shapes. Laser processing of natural stones is a relatively new topic. We propose the use of an Yb3+-doped fibre laser for cutting and ablating obsidianus lapis into spherical, rectangular and oval shapes. By means of a theoretical analysis of roughness and hardness, which affect the different surfaces and final shapes, and considering the changes in material temperature during laser interaction, this work will focus on parameter determination such as: laser fluence, incidence angle, laser average power and peak pulse energy, from the proposed Q-switched fibre laser design. Full optical, hardness and rugosity, initial and final, characterization will be included in the presentation.

  1. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors

    PubMed Central

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-01-01

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry–Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2–10 nmkPa and a resolution of better than ΔP = 10 Pa (0.1 cm H2O). A static pressure test in 38 cmH2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k=10.7 pmK, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes. PMID:26184331

  2. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors.

    PubMed

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-01-01

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry-Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2-10 nm/kPa and a resolution of better than ΔP = 10 Pa protect (0.1 cm H2O). A static pressure test in 38 cm H2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k = 10.7 pm/K, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes. PMID:26184331

  3. 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.

  4. Children's Glasses

    NASA Astrophysics Data System (ADS)

    Akerskog, Gunnar; Soderlund, Jan

    1980-07-01

    There is a common opinion among eye specialists and opticians that children's glasses often are not shaped for optimal fitting. A fundamental reason for this is the lack of data for the shaping of the bows, with the result that most children's glasses are reduced copies of adult's glasses. This report describes a photogrammetric method for collection of primary data for manufac-turing bows for children. An ordinary amateur camera was equipped with a stereo-adapter. With a few arrangements, such as projecting a pattern on the face and keeping the hair away from the ears, 600 children were photographed. A calibration photograph was exposed at the beginning and end of each film or when the equipment had been transported or otherwise disturbed. The photographs were measured in a stereocomparator and the coordinates analytically corrected for distortion. After determination of model coordinates the requested geometric information, such as pupillar distance, eye-ear distance, location of the bridge of the nose etc, was calculated. The shapes of average noses were presented as profile plots.

  5. The dependence of membrane potential on extracellular chloride concentration in mammalian skeletal muscle fibres.

    PubMed Central

    Dulhunty, A F

    1978-01-01

    1. The steady-state intracellular membrane potential of fibres in thin bundles dissected from mouse extensor digitorum longus or soleus muscles or rat sternomastoid muscles was measured with 3 M-KCl glass micro-electrodes. The steady-state membrane potential was found to depend on the extracellular concentrations of Na, K and Cl ions. 2. The resting membrane potential (3.5 mM-[K]o, 160 mM-[Cl]o) was -74 +/- 1 mV (mean +/- S.E.) and a reduction in [Cl]o to 3.5 mM caused a reversible steady-state hyperpolarization to -94 +/- 1 mV (mean +/- S.E.). 3. The steady-state membrane potentials recorded in fibres exposed to different [K]o and zero [Cl]o were consistent with potentials predicted by the Goldman, Hodgkin & Katz (GHK) equation for Na and K. The results of similar experiments done with Cl as the major external anion could not be fitted by the same equation. 4. The GHK equation for Na, K and Cl did fit data obtained from fibres in solutions containing different [K]o with Cl as the major external anion if the intracellular Cl concentration was allowed to be out of equilibrium with the steady-state membrane potential. 5. It is suggested that an active influx of Cl ions controls the intracellular Cl concentrations in these fibres and hence maintains the Cl equilibrium potential at a depolarized value with respect to the resting membrane potential. 6. The steady-state membrane potential of rat diaphragm fibres was independent of [Cl]o and it seems likely that the intracellular Cl concentration of these fibres is not controlled by active Cl transport. PMID:650497

  6. Interganglionic segregation of distinct vagal afferent fibre phenotypes in guinea-pig airways.

    PubMed Central

    Ricco, M M; Kummer, W; Biglari, B; Myers, A C; Undem, B J

    1996-01-01

    1. The present study addressed the hypothesis that jugular and nodose vagal ganglia contain the somata of functionally and anatomically distinct airway afferent fibres. 2. Anatomical investigations were performed by injecting guinea-pig airways with the neuronal tracer Fast Blue. The animals were killed 7 days later, and the ganglia were removed and immunostained with antisera against substance P (SP) and neurofilament protein (NF). In the nodose ganglion, NF-immunoreactive neurones accounted for about 98% of the Fast Blue-labelled cells while in the jugular ganglion they accounted for approximately 48%. SP and NF immunoreactivity was never (n = 100) observed in the same cell suggesting that the antisera labelled distinct populations. 3. Electrophysiological investigations were performed using an in vitro guinea-pig tracheal and bronchial preparation with intact afferent vagal pathways, including nodose and jugular ganglia. Action potentials arriving from single airway afferent nerve endings were monitored extracellularly using a glass microelectrode positioned near neuronal cell bodies in either ganglion. 4. The nodose ganglion contained the somata of mainly fast-conducting tracheal A delta fibres whereas the jugular ganglion contained equal numbers of C fibre and A delta fibre tracheal afferent somata. The nodose A delta neurones adapted rapidly to mechanical stimulation, had relatively low mechanical thresholds, were not activated by capsaicin and adapted rapidly to a hyperosmotic stimulus. By contrast, jugular A delta and C fibres adapted slowly to mechanical stimulation, were often activated by capsaicin, had higher mechanical thresholds and displayed a slow adaptation to a hyperosmotic stimulus. 5. The anatomical, physiological and pharmacological data provide evidence to support the contention that the vagal ganglionic source of the fibre supplying the airways ultimately dictates its neurochemical and physiological phenotype. Images Figure 1 PMID:8910234

  7. 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

  8. 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.

  9. Surface Resistance of Jute Fibre/Polylactic Acid Biocomposite to Wet Heat

    NASA Astrophysics Data System (ADS)

    Zandvliet, Clio; Bandyopadhyay, N. R.; Ray, Dipa

    2016-04-01

    Jute fibre/polylactic acid (PLA) composite is of special interest because both resin and reinforcement come from renewable resources. Thus, it could be a more eco-friendly alternative to glass fibre composite [1] and to conventional wood-based panels made with phenol-formaldehyde resin which present many drawbacks for the workers and the environment [2]. Yet the water affinity of the natural fibres, the susceptibility of PLA towards hydrolysis and the low glass transition of the PLA raise a question about the surface resistance of such composites to wet heat in service condition for a furniture application [3]. In this work, the surface resistance of PLA/jute composite alone and with two different varnishes are investigated in regard to an interior application following the standard test method in accordance to BS EN 18721:2009: "Furniture: assessment of surface resistance to wet heat". It is compared to two common wood based panels, plywood and hardboard. After test, the composite material surface is found to be more affected than plywood and hardboard, but it becomes resistant to wet heat when a layer of biosourced varnish or petrol-based polyurethane varnish are applied on the surface.

  10. Observation and modelling of barrel droplets on vertical fibres subjected to gravitational and drag forces.

    PubMed

    Mullins, Benjamin J; Braddock, Roger D; Agranovski, Igor E; Cropp, Roger A

    2006-08-15

    Extensive experimental investigation of the wetting processes of fibre/liquid systems during air filtration (when drag and gravitational forces are acting) has shown many important features, including droplet extension, oscillatory motion, and detachment or flow of drops from fibres as airflow velocity increases. A detailed experimental study of the aforementioned processes was conducted using glass filter fibres and H(2)O aerosol, which coalesce on the fibre to form barrel droplets with small contact angles. The droplets were predominantly observed in the Reynolds transition (or unsteady laminar) flow region. The droplet oscillation appears to be induced by the onset of vortexes in the flow field around the droplet as the increasing droplet size increases the Reynolds number. Flow in this region is usually modelled using the classical two-dimensional Karman vortex street, and there exist no 3D equivalents. Therefore to model such oscillation it was necessary to create a new conceptual model to account for the forces both inducing and inhibiting such oscillation. The agreement between the model and experimental results is acceptable for both the radial and transverse oscillations. PMID:16777127

  11. Fibre reinforcement in a structurally compromised endodontically treated molar: a case report

    PubMed Central

    de Ataide, Ida de Noronha; Fernandes, Marina; Lambor, Rajan

    2016-01-01

    The reconstruction of structurally compromised posterior teeth is a rather challenging procedure. The tendency of endodontically treated teeth (ETT) to fracture is considerably higher than vital teeth. Although posts and core build-ups followed by conventional crowns have been generally employed for the purpose of reconstruction, this procedure entails sacrificing a considerable amount of residual sound enamel and dentin. This has drawn the attention of researchers to fibre reinforcement. Fibre-reinforced composite (FRC), designed to replace dentin, enables the biomimetic restoration of teeth. Besides improving the strength of the restoration, the incorporation of glass fibres into composite resins leads to favorable fracture patterns because the fibre layer acts as a stress breaker and stops crack propagation. The following case report presents a technique for reinforcing a badly broken-down ETT with biomimetic materials and FRC. The proper utilization of FRC in structurally compromised teeth can be considered to be an economical and practical measure that may obviate the use of extensive prosthetic treatment. PMID:27200283

  12. Do insulation products of man-made vitreous fibres still cause skin discomfort?

    PubMed Central

    Lundgren, Lennart; Moberg, Cecilia; Lidén, Carola

    2014-01-01

    Background Man-made vitreous fibres (MMVFs) are used in products for insulation and as reinforcement in materials. Contamination of the skin may arise through direct or indirect contact, and from the deposition of airborne fibres. The scientific basis regarding the effects on skin of MMVFs dates from 1970–1980. Objectives To investigate whether currently used insulation MMVF products still cause skin discomfort. Methods Focus group interviews and structured interviews were performed among workers engaged in insulation tasks and among do-it-yourself consumers with a recent experience of MMVF products. Results A majority of interviewees experienced skin discomfort when handling MMVF products. Complaints caused by traditional (yellow) glass fibre products were more severe than those caused by products of rock or slag wool fibres. The wrists, forearms, neck and face were the locations where the skin was most affected. The situations causing problems varied between occupational tasks, but working with the hands over the head or in narrow spaces were described as the worst situations. Building construction apprentices performed insulation tasks more often than senior workers. Conclusions MMVF insulation products do still cause skin discomfort. Updated knowledge about people’s experiences of work with such products should influence legislation. PMID:24684557

  13. Development of epoxidized soybean oil and soy fibre composites with Polyhedral Oligomeric Silsesquioxane (POSS) nano reinforcement

    NASA Astrophysics Data System (ADS)

    de Boer, Ryan Sietze

    Soy fibre and soybean oil were utilized to produce a bio-composite targeted as a substitute for conventional petroleum-based materials. The study was divided into two parts; the first was the development of a bio-epoxy that consisted of conventional epoxy, epoxidized soybean oil, and two types of functionalized POSS. The second part of the study involved blending of the bio-epoxy with titanate treated soy fibre. Combined incorporation of epoxide and amine functionalized POSS in the bio-epoxy matrix resulted in a 29% impact strength improvement compared to the petroleum-based epoxy. Incorporation of the epoxide functionalized POSS resulted in improvements in tensile strength by 8%, tensile modulus by 2%, and an increase in the glass transition temperature by 4% compared to the petroleum-based epoxy and epoxidized soybean oil hybrid. The coupling of titanate to soy fibre in comparison to the soy fibre without titanate treatment resulted in an impact strength improvement of 37%. Furthermore, the coupling of titanate increased the tensile strength and tensile modulus by 24% and 22% respectively, and reduced the water absorption by 70%.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Nanofibre fabrication by femtosecond laser ablation of silica glass

    NASA Astrophysics Data System (ADS)

    Venkatakrishnan, Krishnan; Vipparty, Dheeraj; Tan, Bo

    2011-08-01

    : This article presents a fabrication technique for generating densely populated and randomly oriented silica nanofibres by direct ablation of silica glass using a femtosecond laser with 12.4 MHz repetition rate and a pulse width of 214 fs, under ambient conditions. Four types of nanofibres with diameters ranging from a few tens of nanometers to a few hundreds of nanometers were formed. Some fibers reach lengths of 10 mm. The possible mechanisms for fibre formation have been explored.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Modification et caractérisation de la surface de fibres de verre pour son insertion postérieure dans des matériaux cimentaires

    NASA Astrophysics Data System (ADS)

    Bismarck, A.; Ajuriagojeaskoa, E. E.; Springer, J.; Habel, W. R.

    1999-07-01

    Optical fibres are widely used as physical and mechanical sensors in various matrices. Those commercial available fibres are mostly coated with different polymers (e.g. polyimide). The problem of using such coatings is the undefined adhesion and the stress transmission from the matrix material into the fibre as well as the alkaline attack from the cementitious environments onto the glass surface. Therefore the known silanisation process with alkylsilanes for surface modification was studied. To achieve a silane film onto the fibre surface as close as possible a fibre pre-treatment in oxygen plasma was applied. The wetting behaviour of the oxygen plasma treated fibres as well as the silanized fibres were studied using the Wilhelmy-method. The influence of the silane concentration and the time of the pre-treatment on the wetting properties was investigated. By scanning electron microscopy, changes of the surface morphology were detected. Additionally, the mechanical properties of the oxygen plasma treated fibres, and silanized fibres exposed to a highly alkaline pore solution were measured. For selected fibre samples (decoated and untreated as well as silanized fibres) the adhesion to a concrete matrix was studied using the indention test. Les fibres optiques sont de plus en plus utilisées comme capteurs des propriétés physiques et mécaniques de nombreuses matrices. Ces fibres commerciales sont généralement enrobées avec différents polymères (par exemple polyimide). Les problèmes dus à l'enrobage des fibres optiques sont une adhésion et une transmission de charge de la matrice du béton à la fibre non définies. Un autre problème majeur est l'alcalinité du béton et son influence sur la surface de la fibre. Nous avons utilisé le procédé de silanisation. Pour obtenir un film de silane le plus homogène possible sur la surface, les fibres sont pré-traitées par le plasma d?oxygène. Le mouillage de fibres traitées par le plasma d?oxygène, ainsi que

  8. 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

  9. Impact Strength of Glass and Glass Ceramic

    NASA Astrophysics Data System (ADS)

    Bless, Stephan; Tolman, John

    2009-06-01

    Bar impact tests, using the techniques described elsewhere in this symposium, were used to measure compressive and tensile strengths of borosilicate glass, soda lime glass, and glass ceramic. The glass ceramic was 25% crystalline spinel, furnished by Corning, Inc. There are two measures of compressive strength: the peak stress that can be transmitted in unconfined compression and the steady-state strength. For both glasses, these values were similar, being about 1.8 and 1.5 GPa, respectively. The glass ceramic was almost 50% stronger. Tensile failure in the glass and glass ceramic takes places via surface flaws, and thus tensile strength is an extrinsic---as opposed to intrinsic---property.

  10. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  11. 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

  12. IMPACT STRENGTH OF GLASS AND GLASS CERAMIC

    SciTech Connect

    Bless, S.; Tolman, J.

    2009-12-28

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  13. Impact Strength of Glass and Glass Ceramic

    NASA Astrophysics Data System (ADS)

    Bless, S.; Tolman, J.

    2009-12-01

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  14. Fatigue damage observed non-destructively in fibre composite coupon test specimens by X-ray CT

    NASA Astrophysics Data System (ADS)

    Jespersen, K. M.; Mikkelsen, L. P.

    2016-07-01

    This study presents a method for monitoring the 3D fatigue damage progression on a micro-structural level in a glass fibre/polymer coupon test specimen by means of laboratory X-ray Computed Tomography (CT). A modified mount and holder made for the standard test samples to fit into the X-ray CT scanner along with a tension clamp solution is presented. Initially, the same location of the test specimen is inspected by ex-situ X-ray CT during the fatigue loading history, which shows the damage progression on a micro-structural level. The openings of individual uni-directional (UD) fibre fractures are seen to generally increase with the number of cycles, and new regions of UD fibre fractures also appear. There are some UD fibre fractures that are difficult to detect since their opening is small. Therefore, the effect of tension on the crack visibility is examined afterwards using a tension clamp solution. With applied tension some additional cracks become visible and the openings of fibre fractures increases, which shows the importance of applied tension during the scan.

  15. 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.

  16. 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.

  17. The mechanical reliability of optical fibre for long-term applications

    NASA Astrophysics Data System (ADS)

    El-Shazly, Y. M. S.; Kukureka, S. N.

    2006-04-01

    Optical fibre is often required for long-term applications in harsh environments, eg. underwater cables or aerial cables in snowy areas. However, stress corrosion or the growth of cracks present on the surface of the glass results in the failure of the fibres, especially if they are to be deployed in humid areas and bearing a static stress. The presence of a fatigue limit, a stress under which the crack does not grow has not been established in pure silica glass, in contrast to borosilicate and the soda-lime glasses. A method to check the presence of a fatigue limit was developed by Gupta1 by studying the relation between the power and exponential laws of crack growth. Here, dynamic fatigue tests were carried out to estimate the fatigue parameters. The limiting stress is found and is compared to static fatigue results from tests carried out under hot water to accelerate the corrosion process. The extrapolation of the static fatigue stress for a time of 25 years predicts a failure stress that is higher than the fatigue limit.

  18. Interlaminar Fracture toughness in Glass-Cellulose Reinforced Epoxy hybrid composites

    NASA Astrophysics Data System (ADS)

    Uppin, Vinayak S.; Ashok; AnanthJoshi; Sridhar, I.; Shivakumar Gouda, P. S.

    2016-09-01

    Laminates of fibre reinforced compositesare weak in through thicknessbut strong in fibre direction, this lead to development of hybridizationconcept in polymer composites. In this work a new method of disperssing cellulose micro particleson unidirectional (UD) Glass fibre epoxy composite using semi-automated draw down coating technique was adopted to enhance fracture toughness.Test results show that by adding cellulose increases the load carrying competency by 32% in mode-I as compare to Glass- Epoxy composite samples. Imrovement in interlaminar critical energy release rates (GiC and GnC) up to 55% in Mode -I and 19 %in Mode -II respectively was also observed. This enahancement in fracture toughnees is due to the amount of fiber bridging seen during crack initiation and propagation.

  19. 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)

  20. 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

  1. Chemical Principles Revisited: The Chemistry of Glass.

    ERIC Educational Resources Information Center

    Kolb, Doris; Kolb, Kenneth E.

    1979-01-01

    Presents a detailed discussion on the chemistry of glass. Topics discussed include: natural glass, early history, modern glass composition, raw materials for glass melting, chemically modified glasses, modern glass forming, glass ceramics, and new developments in glass research. (BT)

  2. 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

  3. On singular fibres in F-theory

    NASA Astrophysics Data System (ADS)

    Braun, Andreas P.; Watari, Taizan

    2013-07-01

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

  4. Repairing cracked glass

    NASA Technical Reports Server (NTRS)

    Helman, D. D.; Holt, J. W.; Smiser, L. V.

    1979-01-01

    Filing procedure consisting of machined lightweight fused-silica tiles coated with thin-layer of borosilicate glass produces homogeneous seal in thin glass. Procedure is useful in repairing glass envelopes, X-ray tub windows, Dewar flasks, and similar thin glass objects.

  5. Inverted glass harp

    NASA Astrophysics Data System (ADS)

    Quinn, Daniel B.; Rosenberg, Brian J.

    2015-08-01

    We present an analytical treatment of the acoustics of liquid-filled wine glasses, or "glass harps." The solution is generalized such that under certain assumptions it reduces to previous glass harp models, but also leads to a proposed musical instrument, the "inverted glass harp," in which an empty glass is submerged in a liquid-filled basin. The versatility of the solution demonstrates that all glass harps are governed by a family of solutions to Laplace's equation around a vibrating disk. Tonal analyses of recordings for a sample glass are offered as confirmation of the scaling predictions.

  6. Inverted glass harp.

    PubMed

    Quinn, Daniel B; Rosenberg, Brian J

    2015-08-01

    We present an analytical treatment of the acoustics of liquid-filled wine glasses, or "glass harps." The solution is generalized such that under certain assumptions it reduces to previous glass harp models, but also leads to a proposed musical instrument, the "inverted glass harp," in which an empty glass is submerged in a liquid-filled basin. The versatility of the solution demonstrates that all glass harps are governed by a family of solutions to Laplace's equation around a vibrating disk. Tonal analyses of recordings for a sample glass are offered as confirmation of the scaling predictions. PMID:26382336

  7. Glass-silicon column

    DOEpatents

    Yu, Conrad M.

    2003-12-30

    A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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)

  17. Buckling of a holey column.

    PubMed

    Pihler-Puzović, D; Hazel, A L; Mullin, T

    2016-09-14

    We report the results from a combined experimental and numerical investigation of buckling in a novel variant of an elastic column under axial load. We find that including a regular line of centred holes in the column can prevent conventional, global, lateral buckling. Instead, the local microstructure introduced by the holes allows the column to buckle in an entirely different, internal, mode in which the holes are compressed in alternate directions, but the column maintains the lateral reflection symmetry about its centreline. The internal buckling mode can be accommodated within a smaller external space than the global one; and it is the preferred buckling mode over an intermediate range of column lengths for sufficiently large holes. For very short or sufficiently long columns a modification of the classical, global, lateral buckling is dominant. PMID:27501288

  18. 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.

  19. Amplifications in the S-, C- and L-bands using RE-ion doped short tellurite fibres with 980 nm and 800 nm excitation sources

    NASA Astrophysics Data System (ADS)

    Jha, Animesh; Shen, Shaoxiong; Joshi, P.

    2006-02-01

    We report the results of emission and amplification in Tm 3+- and Er 3+-fibres for signal gain in the 1420 nm to 1600 nm wavelength range, which covers S-, C- and L-bands of silica fibre optical communication networks. The paper explains the mechanism for alleviating the pump excited state absorption (ESA) in Er-doped tellurite fibres for maximizing the pump inversion efficiency at 980 nm using the Ce-ions as a co-dopant and via the structural modification of TeO II glass using B IIO 3. The spectroscopic data and gain bandwidth of Er-doped fibres are reported in the C- and L-bands. Methods for enhancing gain in the S-band using the co-dopants (Tb 3+, Yb 3+) with 800 nm and 980 nm pumping schemes are also explained. The measured maximum relative gain in short fibres of 5 to 10 cm in length in C- and L-bands are: 30 dB and 15 dB, respectively. By comparison the internal gain in a 20 cm long Tm/Yb ion co-doped fibre pumped with a 980 nm source was 7 dB.

  20. On the mechanism of photoinduced refractive index changes in phosphosilicate glass

    SciTech Connect

    Larionov, Yu V; Sokolov, V O; Plotnichenko, V G

    2010-05-26

    The photoinduced growth of the refractive index of phosphosilicate glass during Bragg grating inscription and the thermal decay of the grating have a number of unusual features. The observed index variations are interpreted in terms of a new model for photoinduced glass network rearrangement. The model assumes the formation of photoinduced voids (nanopores) in the glass network near point defects. The nanopores may migrate through the network via bond switching when the network is in a 'soft' state. The photoinduced variations in network density lead to index variations. (fibres)

  1. Nanocomposites of silver nanoparticles embedded in glass nanofibres obtained by laser spinning.

    PubMed

    Cabal, Belén; Quintero, Félix; Díaz, Luís Antonio; Rojo, Fernando; Dieste, Oliver; Pou, Juan; Torrecillas, Ramón; Moya, José Serafín

    2013-05-01

    Nanocomposites made of non-woven glass fibres with diameters ranging from tens of nanometers up to several micrometers, containing silver nanoparticles, were successfully fabricated by the laser spinning technique. Pellets of a soda-lime silicate glass containing silver nanoparticles with varying concentrations (5 and 10 wt%) were used as a precursor. The process followed to obtain the silver nanofibres did not agglomerate significantly the metallic nanoparticles, and the average particle size is still lower than 50 nm. This is the first time that glass nanofibres containing silver nanoparticles have been obtained following a process different from electrospinning of a sol-gel, thus avoiding the limitations of this method and opening a new route to composite nanomaterials. Antibacterial efficiency of the nanosilver glass fibres, tested against one of the most common gram negative bacteria, was greater than 99.99% compared to the glass fibres free of silver. The silver nanoparticles are well-dispersed not only on the surface but are also embedded into the uniform nanofibres, which leads to a long lasting durable antimicrobial effect. All these novel characteristics will potentially open up a whole new range of applications.

  2. Nanocomposites of silver nanoparticles embedded in glass nanofibres obtained by laser spinning

    NASA Astrophysics Data System (ADS)

    Cabal, Belén; Quintero, Félix; Díaz, Luís Antonio; Rojo, Fernando; Dieste, Oliver; Pou, Juan; Torrecillas, Ramón; Moya, José Serafín

    2013-04-01

    Nanocomposites made of non-woven glass fibres with diameters ranging from tens of nanometers up to several micrometers, containing silver nanoparticles, were successfully fabricated by the laser spinning technique. Pellets of a soda-lime silicate glass containing silver nanoparticles with varying concentrations (5 and 10 wt%) were used as a precursor. The process followed to obtain the silver nanofibres did not agglomerate significantly the metallic nanoparticles, and the average particle size is still lower than 50 nm. This is the first time that glass nanofibres containing silver nanoparticles have been obtained following a process different from electrospinning of a sol-gel, thus avoiding the limitations of this method and opening a new route to composite nanomaterials. Antibacterial efficiency of the nanosilver glass fibres, tested against one of the most common Gram negative bacteria, was greater than 99.99% compared to the glass fibres free of silver. The silver nanoparticles are well-dispersed not only on the surface but are also embedded into the uniform nanofibres, which leads to a long lasting durable antimicrobial effect. All these novel characteristics will potentially open up a whole new range of applications.

  3. Mechanical behavior of glass fiber polyester hybrid composite filled with natural fillers

    NASA Astrophysics Data System (ADS)

    Gupta, G.; Gupta, A.; Dhanola, A.; Raturi, A.

    2016-09-01

    Now-a-days, the natural fibers and fillers from renewable natural resources offer the potential to act as a reinforcing material for polymer composite material alternative to the use of synthetic fiber like as; glass, carbon and other man-made fibers. Among various natural fibers and fillers like banana, wheat straw, rice husk, wood powder, sisal, jute, hemp etc. are the most widely used natural fibers and fillers due to its advantages like easy availability, low density, low production cost and reasonable physical and mechanical properties This research work presents the effect of natural fillers loading with 5%, 10% and 15% on mechanical behavior of polyester based hybrid composites. The result of test depicted that hybrid composite has far better properties than single fibre glass reinforced composite under impact and flexural loads. However it is found that the hybrid composite have better strength as compared to single glass fibre composites.

  4. 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.

  5. Picture Wall (Glass Structures)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Photo shows a subway station in Toronto, Ontario, which is entirely glass-enclosed. The all-glass structure was made possible by a unique glazing concept developed by PPG Industries, Pittsburgh, Pennsylvania, one of the largest U.S. manufacturers of flat glass. In the TVS glazing system, transparent glass "fins" replace conventional vertical support members used to provide support for wind load resistance. For stiffening, silicone sealant bonds the fins to adjacent glass panels. At its glass research center near Pittsburgh, PPG Industries uses the NASTRAN computer program to analyze the stability of enclosures made entirely of glass. The company also uses NASTRAN to simulate stresses on large containers of molten glass and to analyze stress effects of solar heating on flat glass.

  6. Reaction cured glass and glass coatings

    NASA Technical Reports Server (NTRS)

    Goldstein, H. E.; Leiser, D. B.; Katvala, V. W. (Inventor)

    1978-01-01

    The invention relates to reaction cured glass and glass coatings prepared by reacting a compound selected from the group consisting of silicon tetraboride, silicon hexaboride, other boron silicides, boron and mixtures with a reactive glass frit composed of a porous high silica borosilicate glass and boron oxide. The glassy composites of the present invention are useful as coatings on low density fibrous porous silica insulations used as heat shields and for articles such as reaction vessels that are subjected to high temperatures with rapid heating and cooling and that require resistance to temperature and repeated thermal shock at temperatures up to about 1482C (2700PF).

  7. 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.

  8. GlassForm

    2011-09-16

    GlassForm is a software tool for generating preliminary waste glass formulas for a given waste stream. The software is useful because it reduces the number of verification melts required to develop a suitable additive composition. The software includes property models that calculate glass properties of interest from the chemical composition of the waste glass. The software includes property models for glass viscosity, electrical conductivity, glass transition temperature, and leach resistance as measured by the 7-daymore » product consistency test (PCT).« less

  9. 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)

  10. 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.

  11. 6. Looking glass aircraft in the project looking glass historic ...

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

    6. Looking glass aircraft in the project looking glass historic district. View to north. - Offutt Air Force Base, Looking Glass Airborne Command Post, Looking Glass Avenue between Comstat Drive & Nightwatch Avenue, Offutt Air Force Base, Bellevue, Sarpy County, NE

  12. Oxynitride glass fibers

    NASA Technical Reports Server (NTRS)

    Patel, Parimal J.; Messier, Donald R.; Rich, R. E.

    1991-01-01

    Research at the Army Materials Technology Laboratory (AMTL) and elsewhere has shown that many glass properties including elastic modulus, hardness, and corrosion resistance are improved markedly by the substitution of nitrogen for oxygen in the glass structure. Oxynitride glasses, therefore, offer exciting opportunities for making high modulus, high strength fibers. Processes for making oxynitride glasses and fibers of glass compositions similar to commercial oxide glasses, but with considerable enhanced properties, are discussed. We have made glasses with elastic moduli as high as 140 GPa and fibers with moduli of 120 GPa and tensile strengths up to 2900 MPa. AMTL holds a U.S. patent on oxynitride glass fibers, and this presentation discusses a unique process for drawing small diameter oxynitride glass fibers at high drawing rates. Fibers are drawn through a nozzle from molten glass in a molybdenum crucible at 1550 C. The crucible is situated in a furnace chamber in flowing nitrogen, and the fiber is wound in air outside of the chamber, making the process straightforward and commercially feasible. Strengths were considerably improved by improving glass quality to minimize internal defects. Though the fiber strengths were comparable with oxide fibers, work is currently in progress to further improve the elastic modulus and strength of fibers. The high elastic modulus of oxynitride glasses indicate their potential for making fibers with tensile strengths surpassing any oxide glass fibers, and we hope to realize that potential in the near future.

  13. Cost-efficient hermetic fibre pigtailed laser module utilizing passive device alignment on an LTCC substrate

    NASA Astrophysics Data System (ADS)

    Keränen, K.; Ollila, J.; Mäkinen, J.-T.; Kautio, K.; Korhonen, P.; Heikkinen, V.; Väätäinen, O.; Heilala, J.; Karioja, P.

    2006-04-01

    A hermetic fibre pigtailed laser module utilizing passive device alignment on a low temperature co-fired ceramics (LTCC) substrate is demonstrated. The 3-dimensional shape of the laminated and fired ceramic substrate provides the necessary alignment structures including holes, grooves and cavities for the laser to fibre coupling. The achieved passive alignment accuracy allows high coupling efficiency realizations of multi-mode fibre pigtailed laser modules. The ceramic substrate is intrinsically hermetic and it opens up a possibility to produce cost efficient hermetic packaging. In our concept hermetic sealing is produced by utilizing Kovar frame, which is soldered to an LTCC substrate. Kovar frame has a hole for fibre feed-trough and a hermetic glass-metal sealing between fibre and frame is processed using glass preform. The heart of the module is a power laser diode chip, which can produce several watts of continuous power. The module, however, can be finally used as a transmitter in a laser pulse time-of-flight distance sensor and in this application it can be overdriven by a factor of 10. This means that the peak optical power in the pulses can be several tens of watts. The laser chip allows this kind of overdriving due to the fact that the duty factor in the operation is only 0.0001 at 2 kHz pulsing frequency. Optical coupling efficiency of the multi-mode laser system was simulated using optical systems simulation software. The nominal coupling efficiency between 210 μm x 1μm stripe laser and 200/220 μm step index fibre (NA=0.22) was 0.65. The simulated coupling efficiency was verified by prototype realization and characterization. The measured average coupling efficiency of the hermetically sealed prototypes was 0.39. The coupling efficiencies of prototypes varied from 0.14 to 0.64. Leak rate of 1 x 10 -7 [atm x cm 3/s] was measured in the helium leak tests for the final prototype module, when the module was tested according to MIL-STD-883D method 1014

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. Ultrahigh-Temperature Regeneration of Long Period Gratings (LPGs) in Boron-Codoped Germanosilicate Optical Fibre

    PubMed Central

    Liu, Wen; Cook, Kevin; Canning, John

    2015-01-01

    The regeneration of UV-written long period gratings (LPG) in boron-codoped germanosilicate “W” fibre is demonstrated and studied. They survive temperatures over 1000 °C. Compared with regenerated FBGs fabricated in the same type of fibre, the evolution curves of LPGs during regeneration and post-annealing reveal even more detail of glass relaxation. Piece-wise temperature dependence is observed, indicating the onset of a phase transition of glass in the core and inner cladding at ~500 °C and ~250 °C, and the melting of inner cladding between 860 °C and 900 °C. An asymmetric spectral response with increasing and decreasing annealing temperature points to the complex process dependent material system response. Resonant wavelength tuning by adjusting the dwell temperature at which regeneration is undertaken is demonstrated, showing a shorter resonant wavelength and shorter time for stabilisation with higher dwell temperatures. All the regenerated LPGs are nearly strain-insensitive and cannot be tuned by applying loads during annealing as done for regenerated FBGs. PMID:26307991

  19. Glass tube splitting tool

    NASA Technical Reports Server (NTRS)

    Klein, J. A.; Murray, C. D.; Stein, J. A.

    1971-01-01

    Tool accurately splits glass tubing so cuts are aligned 180 deg apart and reassembled tube forms low pressure, gastight enclosure. Device should interest industries using cylindrical closed glass containers.

  20. Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing.

    PubMed

    Shabahang, Soroush; Tao, Guangming; Kaufman, Joshua J; Qiao, Yangyang; Wei, Lei; Bouchenot, Thomas; Gordon, Ali P; Fink, Yoel; Bai, Yuanli; Hoy, Robert S; Abouraddy, Ayman F

    2016-06-23

    Polymer cold-drawing is a process in which tensile stress reduces the diameter of a drawn fibre (or thickness of a drawn film) and orients the polymeric chains. Cold-drawing has long been used in industrial applications, including the production of flexible fibres with high tensile strength such as polyester and nylon. However, cold-drawing of a composite structure has been less studied. Here we show that in a multimaterial fibre composed of a brittle core embedded in a ductile polymer cladding, cold-drawing results in a surprising phenomenon: controllable and sequential fragmentation of the core to produce uniformly sized rods along metres of fibre, rather than the expected random or chaotic fragmentation. These embedded structures arise from mechanical-geometric instabilities associated with 'neck' propagation. Embedded, structured multimaterial threads with complex transverse geometry are thus fragmented into a periodic train of rods held stationary in the polymer cladding. These rods can then be easily extracted via selective dissolution of the cladding, or can self-heal by thermal restoration to re-form the brittle thread. Our method is also applicable to composites with flat rather than cylindrical geometries, in which case cold-drawing leads to the break-up of an embedded or coated brittle film into narrow parallel strips that are aligned normally to the drawing axis. A range of materials was explored to establish the universality of this effect, including silicon, germanium, gold, glasses, silk, polystyrene, biodegradable polymers and ice. We observe, and verify through nonlinear finite-element simulations, a linear relationship between the smallest transverse scale and the longitudinal break-up period. These results may lead to the development of dynamical and thermoreversible camouflaging via a nanoscale Venetian-blind effect, and the fabrication of large-area structured surfaces that facilitate high-sensitivity bio-detection. PMID:27281223

  1. Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing

    NASA Astrophysics Data System (ADS)

    Shabahang, Soroush; Tao, Guangming; Kaufman, Joshua J.; Qiao, Yangyang; Wei, Lei; Bouchenot, Thomas; Gordon, Ali P.; Fink, Yoel; Bai, Yuanli; Hoy, Robert S.; Abouraddy, Ayman F.

    2016-06-01

    Polymer cold-drawing is a process in which tensile stress reduces the diameter of a drawn fibre (or thickness of a drawn film) and orients the polymeric chains. Cold-drawing has long been used in industrial applications, including the production of flexible fibres with high tensile strength such as polyester and nylon. However, cold-drawing of a composite structure has been less studied. Here we show that in a multimaterial fibre composed of a brittle core embedded in a ductile polymer cladding, cold-drawing results in a surprising phenomenon: controllable and sequential fragmentation of the core to produce uniformly sized rods along metres of fibre, rather than the expected random or chaotic fragmentation. These embedded structures arise from mechanical-geometric instabilities associated with ‘neck’ propagation. Embedded, structured multimaterial threads with complex transverse geometry are thus fragmented into a periodic train of rods held stationary in the polymer cladding. These rods can then be easily extracted via selective dissolution of the cladding, or can self-heal by thermal restoration to re-form the brittle thread. Our method is also applicable to composites with flat rather than cylindrical geometries, in which case cold-drawing leads to the break-up of an embedded or coated brittle film into narrow parallel strips that are aligned normally to the drawing axis. A range of materials was explored to establish the universality of this effect, including silicon, germanium, gold, glasses, silk, polystyrene, biodegradable polymers and ice. We observe, and verify through nonlinear finite-element simulations, a linear relationship between the smallest transverse scale and the longitudinal break-up period. These results may lead to the development of dynamical and thermoreversible camouflaging via a nanoscale Venetian-blind effect, and the fabrication of large-area structured surfaces that facilitate high-sensitivity bio-detection.

  2. Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing

    NASA Astrophysics Data System (ADS)

    Shabahang, Soroush; Tao, Guangming; Kaufman, Joshua J.; Qiao, Yangyang; Wei, Lei; Bouchenot, Thomas; Gordon, Ali P.; Fink, Yoel; Bai, Yuanli; Hoy, Robert S.; Abouraddy, Ayman F.

    2016-06-01

    Polymer cold-drawing is a process in which tensile stress reduces the diameter of a drawn fibre (or thickness of a drawn film) and orients the polymeric chains. Cold-drawing has long been used in industrial applications, including the production of flexible fibres with high tensile strength such as polyester and nylon. However, cold-drawing of a composite structure has been less studied. Here we show that in a multimaterial fibre composed of a brittle core embedded in a ductile polymer cladding, cold-drawing results in a surprising phenomenon: controllable and sequential fragmentation of the core to produce uniformly sized rods along metres of fibre, rather than the expected random or chaotic fragmentation. These embedded structures arise from mechanical–geometric instabilities associated with ‘neck’ propagation. Embedded, structured multimaterial threads with complex transverse geometry are thus fragmented into a periodic train of rods held stationary in the polymer cladding. These rods can then be easily extracted via selective dissolution of the cladding, or can self-heal by thermal restoration to re-form the brittle thread. Our method is also applicable to composites with flat rather than cylindrical geometries, in which case cold-drawing leads to the break-up of an embedded or coated brittle film into narrow parallel strips that are aligned normally to the drawing axis. A range of materials was explored to establish the universality of this effect, including silicon, germanium, gold, glasses, silk, polystyrene, biodegradable polymers and ice. We observe, and verify through nonlinear finite-element simulations, a linear relationship between the smallest transverse scale and the longitudinal break-up period. These results may lead to the development of dynamical and thermoreversible camouflaging via a nanoscale Venetian-blind effect, and the fabrication of large-area structured surfaces that facilitate high-sensitivity bio-detection.

  3. Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

    NASA Astrophysics Data System (ADS)

    Bobkov, K. K.; Rybaltovsky, A. A.; Vel'miskin, V. V.; Likhachev, M. E.; Bubnov, M. M.; Dianov, E. M.; Umnikov, A. A.; Gur'yanov, A. N.; Vechkanov, N. N.; Shestakova, I. A.

    2014-12-01

    We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb2+ ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb2+ ions and aluminium - oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicate glass, has been identified: photoinduced Yb3+ charge-transfer state excitation.

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

    PubMed

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

    2016-11-20

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

  5. A peptide hormone gene, GhPSK promotes fibre elongation and contributes to longer and finer cotton fibre.

    PubMed

    Han, Jie; Tan, Jiafu; Tu, Lili; Zhang, Xianlong

    2014-09-01

    Cotton fibres, the single-celled trichomes derived from the ovule epidermis, provide the most important natural material for the global textile industry. A number of studies have demonstrated that regulating endogenous hormone levels through transgenic approaches can improve cotton fibre qualities. Phytosulfokine-α (PSK-α) is a novel peptide hormone in plants that is involved in regulating cell proliferation and elongation. However, its potential applications in crop genetic improvement have not been evaluated. In this study, we describe how exogenous PSK-α application promotes cotton fibre cell elongation in vitro. Chlorate, an effective inhibitor of peptide sulfation, suppressed fibre elongation in ovule culture. Exogenously applied PSK-α partly restored the chlorate-induced suppression. A putative PSK gene (GhPSK) was cloned from Gossypium hirsutum. Expression pattern analysis revealed that GhPSK is preferentially expressed in rapidly elongating fibre cells (5-20 days postanthesis). Overexpression of GhPSK in cotton increased the endogenous PSK-α level and promoted cotton fibre cell elongation, resulting in longer and finer fibres. Further results from electrophysiological and physiological analyses suggest that GhPSK affects fibre development through regulation of K(+) efflux. Digital gene expression (DGE) profile analysis of GhPSK overexpression lines indicates that PSK signalling may regulate the respiratory electron-transport chain and reactive oxygen species to affect cotton fibre development. These results imply that peptide hormones are involved in cotton fibre growth and suggest a new strategy for the biotechnological improvement of cotton fibre quality.

  6. Technique for Machining Glass

    NASA Technical Reports Server (NTRS)

    Rice, S. H.

    1982-01-01

    Process for machining glass with conventional carbide tools requires a small quantity of a lubricant for aluminum applied to area of glass to be machined. A carbide tool is then placed against workpiece with light pressure. Tool is raised periodically to clear work of glass dust and particles. Additional lubricant is applied as it is displaced.

  7. Glass in Class

    ERIC Educational Resources Information Center

    Greaves, Neville

    2005-01-01

    Glass is reviewed from fabrication to application, laying emphasis on the wide-ranging physics involved. This begins with liquids and solids and the way in which glasses are defined and can be demonstrated in the classroom. At the atomic level the regular structure of crystals and their irregular counterparts in glasses are explained through…

  8. Acoustical model of a Shoddy fibre absorber

    NASA Astrophysics Data System (ADS)

    Manning, John Peter

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

  9. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  10. Oxynitride glass production procedure

    DOEpatents

    Weidner, Jerry R.; Schuetz, Stanley T.; O'Brien, Michael H.

    1991-01-01

    The invention is a process for the preparation of high quality oxynitride glasses without resorting to high pressures. Nitrogen-containing compounds such as Si.sub.3 N.sub.4 are first encapsulated in a low melting temperature glass. Particles of the encapsulated nitrogen-containing compound are mixed with other oxide glass-formers and melted in an atmosphere of flowing nitrogen and in the presence of buffering gas to form the oxynitride glass. Glasses containing up to 15 at % nitrogen have been prepared by this method.

  11. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru; Watson, E. Bruce; Acocella, John

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  12. In vitro bacterial fermentation of tropical fruit fibres.

    PubMed

    Vong, M H; Stewart, M L

    2013-09-01

    Tropical fruits such as mango, papaya, pineapple and banana are rich sources of dietary fibre. However, few studies have examined the potential physiological effects of fibre from these tropical fruits. The aim of this study was to characterise the fermentability of dietary fibre found in banana, papaya, pineapple and mango as an estimate of the physiological effects of consuming these fruits. Freeze-dried fruit was subjected to in vitro digestion to remove digestible carbohydrates. Digestion residues were freeze-dried prior to fermentation. In vitro fermentation was carried for 24 h under anaerobic conditions to simulate conditions in the large intestine. Gas volume, pH and short chain fatty acids (SCFAs) concentration were measured at 0, 4, 8, 12, and 24 h. SCFAs were analysed by gas chromatography. There was no gas production from 0 to 8 h time points for all samples. Mango fibre resulted in more gas at 12 and 24 h than pineapple, papaya and banana fibres. The slurry pH was significantly lower for mango fibre at 12 and 24 h compared to other samples. Mango fibre resulted in significantly more propionate at 8 h compared to papaya and pineapple fibres. Butyrate concentrations were only significantly different at 4 h. At 24 h total and individual SCFA production did not differ among samples. All fruit fibres were fermentable, with mango fibre being the most rapidly fermented. Additional work is necessary to confirm a benefit on digestive health.

  13. Dietary fibre intakes of individuals with different eating patterns.

    PubMed

    Davies, G J; Crowder, M; Dickerson, J W

    1985-04-01

    This study was undertaken to provide evidence of the variation in the diet necessary to incorporate a high fibre content. Food intakes were measured for seven days by 51 subjects who were either omnivores, vegetarians or vegans. Omnivores consumed the least fibre (23 g), vegetarians significantly more (37 g) and vegans the most (47 g). Men had higher intakes (44 g) than women (30.5 g). Vegans ate the most cereal fibre, but high intake of fibre by both vegetarian groups were due to their preference for unrefined foods, particularly bread. Higher intakes of vegetable fibre by both vegetarian groups were due to high consumption of pulses. Total dietary fibre was significantly related to cereal fibre. As the percentage of fibre increased, the percentage of energy derived from protein decreased. Fat contributed less energy (34 per cent) to the vegan than to the omnivore diet (41 per cent). This study showed that high fibre intake can be achieved on an omnivorous diet and the observation that high fibre diets are possible when the energy content is low, is of relevance to slimming regimes.

  14. Chalcogenide Glass Optical Waveguides for Infrared Biosensing

    PubMed Central

    Anne, Marie-Laure; Keirsse, Julie; Nazabal, Virginie; Hyodo, Koji; Inoue, Satoru; Boussard-Pledel, Catherine; Lhermite, Hervé; Charrier, Joël; Yanakata, Kiyoyuki; Loreal, Olivier; Le Person, Jenny; Colas, Florent; Compère, Chantal; Bureau, Bruno

    2009-01-01

    Due to the remarkable properties of chalcogenide (Chg) glasses, Chg optical waveguides should play a significant role in the development of optical biosensors. This paper describes the fabrication and properties of chalcogenide fibres and planar waveguides. Using optical fibre transparent in the mid-infrared spectral range we have developed a biosensor that can collect information on whole metabolism alterations, rapidly and in situ. Thanks to this sensor it is possible to collect infrared spectra by remote spectroscopy, by simple contact with the sample. In this way, we tried to determine spectral modifications due, on the one hand, to cerebral metabolism alterations caused by a transient focal ischemia in the rat brain and, in the other hand, starvation in the mouse liver. We also applied a microdialysis method, a well known technique for in vivo brain metabolism studies, as reference. In the field of integrated microsensors, reactive ion etching was used to pattern rib waveguides between 2 and 300 μm wide. This technique was used to fabricate Y optical junctions for optical interconnections on chalcogenide amorphous films, which can potentially increase the sensitivity and stability of an optical micro-sensor. The first tests were also carried out to functionalise the Chg planar waveguides with the aim of using them as (bio)sensors. PMID:22423209

  15. Gene Expression Changes and Early Events in Cotton Fibre Development

    PubMed Central

    Lee, Jinsuk J.; Woodward, Andrew W.; Chen, Z. Jeffrey

    2007-01-01

    Background Cotton is the dominant source of natural textile fibre and a significant oil crop. Cotton fibres, produced by certain species in the genus Gossypium, are seed trichomes derived from individual cells of the epidermal layer of the seed coat. Cotton fibre development is delineated into four distinct and overlapping developmental stages: fibre initiation, elongation, secondary wall biosynthesis and maturation. Scope Recent advances in gene expression studies are beginning to provide new insights into a better understanding of early events in cotton fibre development. Fibre cell development is a complex process involving many pathways, including various signal transduction and transcriptional regulation components. Several analyses using expressed sequence tags and microarray have identified transcripts that preferentially accumulate during fibre development. These studies, as well as complementation and overexpression experiments using cotton genes in arabidopsis and tobacco, indicate some similar molecular events between trichome development from the leaf epidermis and fibre development from the ovule epidermis. Specifically, MYB transcription factors regulate leaf trichome development in arabidopsis and may regulate seed trichome development in cotton. In addition, transcript profiling and ovule culture experiments both indicate that several phytohormones and other signalling pathways mediate cotton fibre development. Auxin and gibberellins promote early stages of fibre initiation; ethylene- and brassinosteroid-related genes are up-regulated during the fibre elongation phase; and genes associated with calmodulin and calmodulin-binding proteins are up-regulated in fibre initials. Additional genomic data, mutant and functional analyses, and genome mapping studies promise to reveal the critical factors mediating cotton fibre cell development. PMID:17905721

  16. Acoustics of glass harmonicas

    NASA Astrophysics Data System (ADS)

    Rossing, Thomas D.

    2001-05-01

    Glass musical instruments are probably as old as glassmaking. At least as early as the 17th century it was discovered that wine glasses, when rubbed with a wet finger, produced a musical tone. A collection of glasses played in this manner is called a glass harp. Another type of glass harmonica, called the armonica by its inventor Benjamin Franklin, employs glass bowls or cups turned by a horizontal axle, so the performer need only touch the rim of the bowls as they rotate to set them into vibration. We discuss the modes of vibration of both types of glass harmonica, and describe the different sounds that are emitted by rubbing, tapping, or bowing them. Rubbing with a wet finger tends to excite only the (2,0) mode and its harmonics through a ``stick-slip'' process, while tapping excites the other modes as well.

  17. Frequency stabilisation of a fibre-laser comb using a novel microstructured fibre.

    PubMed

    Locke, C R; Ivanov, E N; Light, P S; Benabid, F; Luiten, A N

    2009-03-30

    There is great interest in developing high performance optical frequency metrology based around mode-locked fibre lasers because of their low cost, small size and long-term turnkey operation when compared to the solid-state alternative. We present a method for stabilising the offset frequency of a fibre-based laser comb using a 2 f - 3 f technique based around a unique fibre that exhibits strong resonant dispersive wave emission. This fibre requires lower power than conventional highly non-linear fibre to generate a suitable signal for offset frequency stabilisation and this in turn avoids the complexity of additional nonlinear steps. We generate an offset frequency signal from the mixing of a wavelength-shifted second harmonic comb with a third harmonic of the comb. Additionally, we have stabilised the repetition rate of the laser to a level better than 10(-14)/ radicaltau , limited by the measurement system noise floor.We present the means for complete and precise measurement of the transfer function of the laser frequency controls.

  18. Distribution of fibre types and fibre sizes in the tibialis cranialis muscle of beagle dogs.

    PubMed Central

    Newsholme, S J; Lexell, J; Downham, D Y

    1988-01-01

    The percentages of Type I muscle fibres were measured systematically in ATPase-stained, transverse cryostat sections of whole tibialis cranialis muscles from 8 young, adult beagles. The distance of the section from the origin of the muscle does not significantly affect the mean percentage. There are no identifiable differences in mean percentages between right and left muscles. Differences in mean percentages between individuals are significant when sexes are combined (P less than 0.01) and within sexes (males: P less than 0.01; females: P less than 0.05). Within sections, the percentage tends to be lowest at the superficial (craniolateral) border and to vary less from site to site deeper within the muscle. Fibre cross sectional areas were measured systematically in the same sections of the right muscle from 3 males and 3 females. Mean areas for each section were greater for Type II than for Type I fibres. Mean areas for each fibre-type varied moderately and non-systematically between the sample sites within sections. A needle biopsy taken from deep within this muscle should provide a more consistent and reliable estimate of fibre-type proportion in the whole muscle than a superficial specimen. Proportions are not affected by the distance of the sample site from the muscle origin, and left or right muscles are suitable for sequential samples. PMID:3253248

  19. Fibre-Reinforced Adhesive for Structure Anchoring

    NASA Astrophysics Data System (ADS)

    Barnat, J.; Bajer, M.

    2015-11-01

    The topic of this paper is the glue-concrete interface of bonded anchors loaded by tension force. The paper is closely focused on bond strength experiments using high strength concrete up to class C50/60 or higher together with pure epoxy resin and fibre-reinforced resin. The goal of this research is to find the limits of the effective use of such glue types in high performance concrete, and also to verify the most commonly used design methods for bonded anchors. The presented research includes experimental analysis of the glue-concrete interface and the influence of its parameters on anchor behaviour. The presented analysis shows some problems of the 'separated failure modes' approach and also presents experimentally verified bond strength values obtained for the currently most widespread glue types. Results of fibre reinforced epoxy resin are also presented in this paper.

  20. Retention of Cationic Starch onto Cellulose Fibres

    NASA Astrophysics Data System (ADS)

    Missaoui, Mohamed; Mauret, Evelyne; Belgacem, Mohamed Naceur

    2008-08-01

    Three methods of cationic starch titration were used to quantify its retention on cellulose fibres, namely: (i) the complexation of CS with iodine and measurement of the absorbency of the ensuing blue solution by UV-vis spectroscopy; (ii) hydrolysis of the starch macromolecules followed by the conversion of the resulting sugars to furan-based molecules and quantifying the ensuing mixture by measuring their absorbance at a Ι of 490 nm, using the same technique as previous one and; finally (iii) hydrolysis of starch macromolecules by trifluoro-acetic acid and quantification of the sugars in the resulting hydrolysates by high performance liquid chromatography. The three methods were found to give similar results within the range of CS addition from 0 to 50 mg per g of cellulose fibres.

  1. Fibre Optic Sensors for Selected Wastewater Characteristics

    PubMed Central

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

    2013-01-01

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

  2. The optical frequency comb fibre spectrometer

    PubMed Central

    Coluccelli, Nicola; Cassinerio, Marco; Redding, Brandon; Cao, Hui; Laporta, Paolo; Galzerano, Gianluca

    2016-01-01

    Optical frequency comb sources provide thousands of precise and accurate optical lines in a single device enabling the broadband and high-speed detection required in many applications. A main challenge is to parallelize the detection over the widest possible band while bringing the resolution to the single comb-line level. Here we propose a solution based on the combination of a frequency comb source and a fibre spectrometer, exploiting all-fibre technology. Our system allows for simultaneous measurement of 500 isolated comb lines over a span of 0.12 THz in a single acquisition; arbitrarily larger span are demonstrated (3,500 comb lines over 0.85 THz) by doing sequential acquisitions. The potential for precision measurements is proved by spectroscopy of acetylene at 1.53 μm. Being based on all-fibre technology, our system is inherently low-cost, lightweight and may lead to the development of a new class of broadband high-resolution spectrometers. PMID:27694981

  3. Novel ultrahigh resolution optical fibre temperature sensor

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  4. The optical frequency comb fibre spectrometer

    NASA Astrophysics Data System (ADS)

    Coluccelli, Nicola; Cassinerio, Marco; Redding, Brandon; Cao, Hui; Laporta, Paolo; Galzerano, Gianluca

    2016-10-01

    Optical frequency comb sources provide thousands of precise and accurate optical lines in a single device enabling the broadband and high-speed detection required in many applications. A main challenge is to parallelize the detection over the widest possible band while bringing the resolution to the single comb-line level. Here we propose a solution based on the combination of a frequency comb source and a fibre spectrometer, exploiting all-fibre technology. Our system allows for simultaneous measurement of 500 isolated comb lines over a span of 0.12 THz in a single acquisition; arbitrarily larger span are demonstrated (3,500 comb lines over 0.85 THz) by doing sequential acquisitions. The potential for precision measurements is proved by spectroscopy of acetylene at 1.53 μm. Being based on all-fibre technology, our system is inherently low-cost, lightweight and may lead to the development of a new class of broadband high-resolution spectrometers.

  5. 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.

  6. Towards woven logic from organic electronic fibres

    NASA Astrophysics Data System (ADS)

    Hamedi, Mahiar; Forchheimer, Robert; Inganäs, Olle

    2007-05-01

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

  7. 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.

  8. Spectroscopy gas sensing based on hollow fibres

    NASA Astrophysics Data System (ADS)

    Rodrigues, A.; Lange, V.; Kühlke, D.

    2011-05-01

    We demonstrate gas sensing in a relatively compact sensor unit in particular for weakly absorbing gases in real time. As a proof-of-concept, we built an oxygen sensor for the A-Band at 760 nm. A VCSEL laser was used as a laser source due to its mode stability and reduced cost compared to DFB lasers and Fabry-Perot lasers. In order to reduce as much as possible the sensor size, a hollow waveguide is used to guide the light and the gas to be analysed in a long path to enhance the sensitivity of the sensor. Two different types of hollow fibres were characterised with respect to their suitability for gas sensing, a photonic crystal fibre, also known as micro-structured optical fibre, and hollow metal-coated capillaries. Characteristics as attenuation, spectral transmission properties and filling time were analysed. At the end, a sensor device with coupling and detection unit was developed. The main advantage of our set-up is the possibility of using the same design for different gases by changing solely the laser, the detector and the coupling lens.

  9. Nerve fibre proliferation in interstitial cystitis.

    PubMed

    Christmas, T J; Rode, J; Chapple, C R; Milroy, E J; Turner-Warwick, R T

    1990-01-01

    The aetiology of pain in interstitial cystitis is not understood, although it has been reported to be due to release of mediators from mast cell granules. Cystolysis and intravesical instillation of dimethyl sulphoxide have been shown to relieve pain in this condition. We have studied the nerve population within the bladder wall using immunohistochemical stains for protein gene product 9.5. A group of 18 cases of chronic interstitial cystitis and 12 controls; neuropathic bladder (n = 1), chronic bacterial cystitis (n = 3), systemic lupus erythematosus cystitis (n = 2) and normals (n = 6), were investigated. There were significantly more nerve fibres within the sub-urothelial and detrusor muscle layers in chronic interstitial cystitis than there were in normals. Patients with chronic cystitis of other aetiology did not have a significant increase in nerve fibre density within the bladder wall suggesting a specific association between nerve fibre proliferation and interstitial cystitis. Cystolysis is shown to deplete selectively the submucosal nerve plexuses without altering the nerve density within detrusor muscle. This finding explains the desensitisation of the bladder without impairment of detrusor function after this procedure.

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2015-09-01

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

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

    PubMed

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

    2015-05-27

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

  13. Sugar palm (Arenga pinnata): Its fibres, polymers and composites.

    PubMed

    Ishak, M R; Sapuan, S M; Leman, Z; Rahman, M Z A; Anwar, U M K; Siregar, J P

    2013-01-16

    Sugar palm (Arenga pinnata) is a multipurpose palm species from which a variety of foods and beverages, timber commodities, biofibres, biopolymers and biocomposites can be produced. Recently, it is being used as a source of renewable energy in the form of bio-ethanol via fermentation process of the sugar palm sap. Although numerous products can be produced from sugar palm, three products that are most prominent are palm sugar, fruits and fibres. This paper focuses mainly on the significance of fibres as they are highly durable, resistant to sea water and because they are available naturally in the form of woven fibre they are easy to process. Besides the recent advances in the research of sugar palm fibres and their composites, this paper also addresses the development of new biodegradable polymer derived from sugar palm starch, and presents reviews on fibre surface treatment, product development, and challenges and efforts on properties enhancement of sugar palm fibre composites. PMID:23121967

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

    SciTech Connect

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

    2015-04-24

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

  15. Effects of chemical treatments on hemp fibre structure

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    PubMed

    Chen, Lei; Bird, David M

    2011-03-28

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

  17. Random pinning glass model.

    PubMed

    Karmakar, Smarajit; Parisi, Giorgio

    2013-02-19

    Glass transition, in which viscosity of liquids increases dramatically upon decrease of temperature without any major change in structural properties, remains one of the most challenging problems in condensed matter physics despite tremendous research efforts in past decades. On the other hand, disordered freezing of spins in magnetic materials with decreasing temperature, the so-called "spin glass transition," is understood relatively better. A previously found similarity between some spin glass models and the structural glasses inspired development of theories of structural glasses based on the scenario of spin glass transition. This scenario, although it looks very appealing, is still far from being well established. One of the main differences between standard spin systems and molecular systems is the absence of quenched disorder and the presence of translational invariance: it often is assumed that this difference is not relevant, but this conjecture still needs to be established. The quantities, which are well-defined and characterized for spin models, are not easily calculable for molecular glasses because of the lack of quenched disorder that breaks the translational invariance in the system. Thus the characterization of the similarity between spin and the structural glass transition remains an elusive subject. In this study, we introduced a model structural glass with built-in quenched disorder that alleviates this main difference between the spin and molecular glasses, thereby helping us compare these two systems: the possibility of producing a good thermalization at rather low temperatures is one of the advantages of this model. PMID:23382186

  18. Low frequency noise distributed-feedback ytterbium fibre laser

    SciTech Connect

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

    2009-10-31

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

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

    PubMed

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

    2011-03-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  1. Distribution of elastic system fibres in human fetal liver.

    PubMed Central

    Monte, A; Costa, A; Porto, L C

    1996-01-01

    Elastic system fibres are extracellular matrix components found in different organs for which they provide elasticity and some mechanical resistance. Oxytalan, elaunin and elastic fibres, which possess graduated amounts of elastin, are the 3 forms of elastic system fibres that are identifiable by their tinctorial and ultrastructural features. The distribution of these fibres in adult human liver is well-established but little, if anything, is known about them in fetal liver. The distribution of elastic system fibres was therefore investigated in human fetal liver, and the process of elastogenesis characterised. Specimens of liver from 24 human fetuses ranging in age from 13 to 38 wk postfertilisation were studied. The results are presented in relation to gestational age and the size of the portal tracts. Portal tracts exhibited a network of oxytalan fibres at 13 wk; elaunin fibres appeared later after 20 wk postfertilisation. Elastogenesis occurred more rapidly in venous than in arterial walls, and in veins it was more evident in the adventitia. A microfibrillar network of oxytalan fibres was observed around biliary ducts from the outset of their development. Elastogenesis follows the sequence oxytalan, elaunin and elastic fibres, but the elastogenetic process only completes its maturation in arterial walls, thus leading to the internal elastic lamina. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8763481

  2. Semiconductor optical fibres for infrared applications: A review

    NASA Astrophysics Data System (ADS)

    Peacock, Anna C.; Healy, Noel

    2016-10-01

    Over the last decade a new class of optical fibre has emerged that incorporates semiconductor materials within the core. These fibres are rich in optoelectronic functionality and offer extended transmission bands across the infrared spectral region so that their application potential is vast. Various fabrication methods have been developed to produce fibres with a range of unary and compound semiconductor core materials, which can be either amorphous or crystalline in form. This review discusses the main fabrication procedures and the infrared optical properties of the semiconductor fibres that have been fabricated to date, then takes a look at the future prospects of this exciting new technology.

  3. Integrated fibres for self-monitored optical transport

    NASA Astrophysics Data System (ADS)

    Bayindir, Mehmet; Shapira, Ofer; Saygin-Hinczewski, Dursen; Viens, Jeff; Abouraddy, Ayman F.; Joannopoulos, John D.; Fink, Yoel

    2005-11-01

    The ability to integrate distinct functional elements into a single device structure enables the realization of systems with higher-level functionality. Here we report on the design and fabrication of a fibre device structure that contains integrated optical, electrical and thermal elements for self-monitored optical transport. The fibre transmission element uses a hollow-core multilayer cylindrical photonic bandgap structure designed to guide high-power radiation at 10.6 μm along the fibre axis. Multiple thermal-detection elements are placed in the vicinity of the hollow core for the purpose of temperature monitoring along the entire fibre length. Metal wires bridged by a semiconductor layer extend along the length of the fibre and deliver an electrical response to the fibre ends on change in the fibre temperature. The multimaterial fibre is drawn at high speeds from a single preform to produce extended lengths of optically and thermally functional fibres. The exponential dependence on temperature of the electrical conductivity of the semiconducting material allows for the discrimination, in real time, between normal transmission conditions and those that are indicative of localized defect formation, thus enabling a self-monitoring high-power optical transmission line for failure prediction and prevention.

  4. New optical fibres for high-capacity optical communications.

    PubMed

    Richardson, D J

    2016-03-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing.

  5. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  7. Giant muscle fibres in pigs with different Ryr1 genotype.

    PubMed

    Fazarinc, G; Candek-Potokar, M; Ursic, M; Vrecl, M; Pogacnik, A

    2002-12-01

    This study examined the frequency, morphological and immunohistochemical characteristics of the giant fibres in the longissimus muscle of local Krsko polje pigs with different Ryr1 genotypes. Giant fibres were round-shaped and had significantly increased cross-sectional area compared with normal muscle fibres. Only fast-twitch glycolytic fibres were affected, usually showing enhanced succinate dehydrogenase activity. On the ultrastructural level, the dilation of the sarcoplasmic reticulum, swelling of mitochondria and destruction of myofilaments was observed. The incidence of giant fibres was the highest in Ryr1 dimutant pigs (Ryr1 nn), which also exhibited lower muscle pH1 than heterozygous (Ryr1 Nn) or pigs with the wild Ryr1 gene (Ryr1 NN). However, the giant fibres were also present in pigs free of Ryr1 gene mutation. Our results suggest that the giant fibre syndrome depends mostly upon the rate and intensity of early post-mortem glycolysis, which results in acidity of muscle tissue. We suppose that the giant fibre formation is a result of excessive intracellular lactate accumulation in some fast-twitch glycolytic fibres. This process could also explain the ultrastructural alterations and the consequent changes in the oxidative enzymes and myofibrillar ATPase staining pattern observed in our and some previous studies.

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

    NASA Astrophysics Data System (ADS)

    Davinson, Ian

    1984-08-01

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

  9. New optical fibres for high-capacity optical communications

    PubMed Central

    Richardson, D. J.

    2016-01-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing. PMID:26809569

  10. Liquid Glass: A Facile Soft Replication Method for Structuring Glass.

    PubMed

    Kotz, Frederik; Plewa, Klaus; Bauer, Werner; Schneider, Norbert; Keller, Nico; Nargang, Tobias; Helmer, Dorothea; Sachsenheimer, Kai; Schäfer, Michael; Worgull, Matthias; Greiner, Christian; Richter, Christiane; Rapp, Bastian E

    2016-06-01

    Liquid glass is a photocurable amorphous silica nanocomposite that can be structured using soft replication molds and turned into glass via thermal debinding and sintering. Simple polymer bonding techniques allow the fabrication of complex microsystems in glass like microfluidic chips. Liquid glass is a step toward prototyping of glass microstructures at low cost without requiring cleanroom facilities or hazardous chemicals. PMID:27060964

  11. Liquid Glass: A Facile Soft Replication Method for Structuring Glass.

    PubMed

    Kotz, Frederik; Plewa, Klaus; Bauer, Werner; Schneider, Norbert; Keller, Nico; Nargang, Tobias; Helmer, Dorothea; Sachsenheimer, Kai; Schäfer, Michael; Worgull, Matthias; Greiner, Christian; Richter, Christiane; Rapp, Bastian E

    2016-06-01

    Liquid glass is a photocurable amorphous silica nanocomposite that can be structured using soft replication molds and turned into glass via thermal debinding and sintering. Simple polymer bonding techniques allow the fabrication of complex microsystems in glass like microfluidic chips. Liquid glass is a step toward prototyping of glass microstructures at low cost without requiring cleanroom facilities or hazardous chemicals.

  12. Specimen specific parameter identification of ovine lumbar intervertebral discs: On the influence of fibre-matrix and fibre-fibre shear interactions.

    PubMed

    Reutlinger, Christoph; Bürki, Alexander; Brandejsky, Vaclav; Ebert, Lars; Büchler, Philippe

    2014-02-01

    Numerical models of the intervertebral disc, which address mechanical questions commonly make use of the difference in water content between annulus and nucleus, and thus fluid and solid parts are separated. Despite this simplification, models remain complex due to the anisotropy and nonlinearity of the annulus and regional variations of the collagen fibre density. Additionally, it has been shown that cross-links make a large contribution to the stiffness of the annulus. Because of this complex composite structure, it is difficult to reproduce several sets of experimental data with one single set of material parameters. This study addresses the question to which extent the ultrastructure of the intervertebral disc should be modelled so that its moment-angle behaviour can be adequately described. Therefore, a hyperelastic constitutive law, based on continuum mechanical principles was derived, which does not only consider the anisotropy from the collagen fibres, but also interactions among the fibres and between the fibres and the ground substance. Eight ovine lumbar intervertebral discs were tested on a custom made spinal loading simulator in flexion/extension, lateral bending and axial rotation. Specimen-specific geometrical models were generated using CT images and T2 maps to distinguish between annulus fibrosus and nucleus pulposus. For the identification of the material parameters the annulus fibrosus was described with two scenarios: with and without fibre-matrix and fibre-fibre interactions. Both scenarios showed a similar behaviour on a load displacement level. Comparing model predictions to the experimental data, the mean RMS of all specimens and all load cases was 0.54±0.15° without the interaction and 0.54±0.19° when the fibre-matrix and fibre-fibre interactions were included. However, due to the increased stiffness when cross-links effects were included, this scenario showed more physiological stress-strain relations in uniaxial and biaxial stress

  13. Specimen specific parameter identification of ovine lumbar intervertebral discs: On the influence of fibre-matrix and fibre-fibre shear interactions.

    PubMed

    Reutlinger, Christoph; Bürki, Alexander; Brandejsky, Vaclav; Ebert, Lars; Büchler, Philippe

    2014-02-01

    Numerical models of the intervertebral disc, which address mechanical questions commonly make use of the difference in water content between annulus and nucleus, and thus fluid and solid parts are separated. Despite this simplification, models remain complex due to the anisotropy and nonlinearity of the annulus and regional variations of the collagen fibre density. Additionally, it has been shown that cross-links make a large contribution to the stiffness of the annulus. Because of this complex composite structure, it is difficult to reproduce several sets of experimental data with one single set of material parameters. This study addresses the question to which extent the ultrastructure of the intervertebral disc should be modelled so that its moment-angle behaviour can be adequately described. Therefore, a hyperelastic constitutive law, based on continuum mechanical principles was derived, which does not only consider the anisotropy from the collagen fibres, but also interactions among the fibres and between the fibres and the ground substance. Eight ovine lumbar intervertebral discs were tested on a custom made spinal loading simulator in flexion/extension, lateral bending and axial rotation. Specimen-specific geometrical models were generated using CT images and T2 maps to distinguish between annulus fibrosus and nucleus pulposus. For the identification of the material parameters the annulus fibrosus was described with two scenarios: with and without fibre-matrix and fibre-fibre interactions. Both scenarios showed a similar behaviour on a load displacement level. Comparing model predictions to the experimental data, the mean RMS of all specimens and all load cases was 0.54±0.15° without the interaction and 0.54±0.19° when the fibre-matrix and fibre-fibre interactions were included. However, due to the increased stiffness when cross-links effects were included, this scenario showed more physiological stress-strain relations in uniaxial and biaxial stress

  14. Diamond turning of glass

    SciTech Connect

    Blackley, W.S.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

  15. Containerless processing of glass

    NASA Technical Reports Server (NTRS)

    Happe, R. A.

    1981-01-01

    Ground-based research on the containerless melting of glass and experiments performed during a flight on the SPAR 6 are described. Experiments leading to selection of the flight sample composition, a silica-modified gallia/calcia glass, and the preparation of a one quarter inch diameter flight sample are described. During the flight experiment, a sample of the glass was containerless melted and cooled to a clear glass in a single axis acoustic positioning apparatus. The functioning of the flight experimental hardware was evaluated. The evaluation of the sample is presented.

  16. Drugstore Reading Glasses

    NASA Astrophysics Data System (ADS)

    Erlichson, Herman

    2006-03-01

    The occasion for this paper was my reading of a paper in the February 2005 issue of TPT. As one gets older the near point of the eye begins to recede.2 This is called presbyopia.3 An alternative to purchasing glasses from an optometrist is to purchase an inexpensive pair of reading glasses in a pharmacy. The pharmacy has these glasses ordered by diopters corresponding to the strength of the lens needed for a particular presbyopic eye. The glasses are, of course, not available for myopic eyes.

  17. Glass--Sand + Imagination

    NASA Astrophysics Data System (ADS)

    Kolb, Kenneth E.; Kolb, Doris K.

    2000-07-01

    Glass is older than recorded history, and yet it is as new as tomorrow! How, when, or where man first learned to make glass is not known, but we do know that the ancient Egyptians were making glass articles as early as 2,600 B.C.E. (The making of glass beads may have begun as much as 3000 years earlier.) They used it to make jewelry and luxury items, such as decorative bowls and perfume bottles, available only to the wealthy.

  18. Apollo 15 green glasses.

    NASA Technical Reports Server (NTRS)

    Ridley, W. I.; Reid, A. M.; Warner, J. L.; Brown, R. W.

    1973-01-01

    The samples analyzed include 28 spheres, portions of spheres, and angular fragments from soil 15101. Emerald green glasses from other soils are identical to those from 15101. The composition of the green glass is unlike that of any other major lunar glass group. The Fe content is comparable to that in mare basalts, but Ti is much lower. The Mg content is much higher than in most lunar materials analyzed to date, and the Cr content is also high. The low Al content is comparable to that of mare basalt glasses.

  19. Variability of muscle fibre composition and fibre size in the horse gluteus medius: an enzyme-histochemical and morphometric study.

    PubMed Central

    López-Rivero, J L; Serrano, A L; Diz, A M; Galisteo, A M

    1992-01-01

    To determine the variability in fibre types and fibre sizes in the equine gluteus medius muscle, biopsy specimens were removed from 5 sites, at 4 different depths, within the right and left muscles of 3 Andalusian stallions. The percentage, lesser fibre diameter and cross-sectional area of the various fibre types were measured systematically in myosin ATPase and NADH-tetrazolium reductase-stained, serial cryostat sections of these multiple samples. Significant differences in muscle fibre type composition were recorded, with a lower percentage of type I fibres (high myosin ATPase activity at pH 4.5) being observed towards superficial regions of the muscle and a greater percentage towards the deep areas. Type II B fibres (moderate myosin ATPase activity at pH 4.5), including both II B nonoxidative (low NADH-TR activity) and II B oxidative (moderate NADH-TR activity), displayed the opposite tendency, and the percentage of type II A fibres (low myosin ATPase activity at pH 4.5) did not change with depth. Types I and II A fibres in the deep regions were larger than superficially, whereas the II B fibres in the deep regions were smaller than in the superficial parts of the muscle. The results also imply that type I fibres tend to be larger than type II fibres in the deep regions. The size of type I fibres is more homogeneous in the deep parts than in the superficial regions of the muscle, while II B fibres vary more in size in the peripheral portions than in deep regions. A single biopsy taken from the gluteus medius muscle of the horse is therefore a poor representative of the whole muscle and care should be exercised in sampling and interpreting data obtained from limited biopsy of this muscle. The pattern of variation in fibre types and fibre sizes between the different depths of the muscle probably reflect different functional demands on the gluteus medius muscle. Images Fig. 1 PMID:1284127

  20. Using a fibre-optic cable as Distributed Acoustic Sensor for Vertical Seismic Profiling - Overview of various field tests

    NASA Astrophysics Data System (ADS)

    Götz, Julia; Lüth, Stefan; Henninges, Jan; Reinsch, Thomas

    2015-04-01

    Fibre-optic Distributed Acoustic Sensing (DAS) or Distributed Vibration Sensing (DVS) is a technology, where an optical fibre cable is used as a sensor for acoustic signals. An ambient seismic wavefield, which is coupled by friction or pressure to the optical fibre, induces dynamic strain changes along the cable. The DAS/DVS technology offers the possibility to record an optoelectronic signal which is linearly related to the time dependent local strain. The DAS/DVS technology is based on the established technique of phase-sensitive optical time-domain reflectometry (phi-OTDR). Coherent laser pulses are launched into the fibre to monitor changes in the resulting elastic Rayleigh backscatter with time. Dynamic strain changes lead to small displacements of the scattering elements (non-uniformities within the glass structure of the optical fibre), and therefore to variations of the relative phases of the backscattered photons. The fibre behaves as a series of interferometers whose output is sensitive to small changes of the strain at any point along its length. To record the ground motion not only in space but also in time, snapshots of the wavefield are created by repeatedly firing laser pulses into the fibre at sampling frequencies much higher than seismic frequencies. DAS/DVS is used e.g. for continuous monitoring of pipelines, roads or borders and for production monitoring from within the wellbore. Within the last years, the DAS/DVS technology was further developed to record seismic data. We focus on the recording of Vertical Seismic Profiling (VSP) data with DAS/DVS and present an overview of various field tests published between 2011 and 2014. Here, especially CO2 storage pilot sites provided the opportunity to test this new technology for geophysical reservoir monitoring. DAS/DVS-VSP time-lapse measurements have been published for the Quest CO2 storage site in Canada. The DAS/DVS technology was also tested at the CO2 storage sites in Rousse (France), Citronelle

  1. Asbestos as reference material for fibre-induced cancer.

    PubMed

    Muhle, H; Pott, F

    2000-06-01

    The objective of this paper is to review published data on the carcinogenicity of asbestos fibres with regard to the elucidation of a potential risk originating from exposure to man-made vitreous fibres (MMVF). Steps in the comparison of the two fibre classes are characterization of the fibres, pulmonary deposition, biodurability and biopersistence and a review of the cancer risk from asbestos fibres after inhalation in rats and humans. Various dust samples of chrysotile, crocidolite, and amosite were used as reference materials in studies with experimental animals. These fibres are normally thinner and shorter than MMVF. These differences in dimensions cause differences in the deposition in the airways. In addition, significant dissimilarities exist in the deposition pattern between rats and humans. Data from biopersistence studies show that focusing only on fibres longer than 20 microm and using weighted half-time for a characterization of risk may be misleading. Inhalation experiments with rats need fibre exposure concentrations over 100 times higher to match the lung cancer risk of asbestos workers, and about 1,000 times higher to reach the same mesothelioma risk. Also, the striking difference between the low lung burden of amphibole fibres of asbestos workers with mesothelioma and the more than 1,000 times higher lung burden of rats with a low mesothelioma risk demonstrates the low sensitivity of the inhalation test model for the carcinogenic potency even of crocidolite fibres. It can be concluded that the rat inhalation model is also not sensitive enough to predict the cancer risk of other fibre types for humans.

  2. Beads, beaded-fibres and fibres: Tailoring the morphology of poly(caprolactone) using pressurised gyration.

    PubMed

    Hong, Xianze; Edirisinghe, Mohan; Mahalingam, Suntharavathanan

    2016-12-01

    This work focuses on forming bead on string poly(caprolactone) (PCL) by using gyration under pressure. The fibre morphology of bead on string is an interesting feature that falls between bead-free fibres and droplets, and it could be effectively controlled by the rheological properties of spinning dopes and the major processing parameters of the pressurised gyration system which are working pressure and rotating speed. Bead products were not always spherical in shape and tended to be more elliptical, therefore both their width and length were measured. The average bead width and length produced spanned a range 145-660μm and 140-1060μm, respectively. The average distance between two adjacent beads (i.e. inter-bead distance) and the bead size (width and length) are shown to be a function of processing parameters and polymer concentration. An interesting morphology i.e. beads with short fibre was observed when using a high polymer concentration. Bead on string structure agglomeration was promoted by a low polymer concentration. Formation of droplets or agglomerated bead on string is promoted below 5wt% polymer concentration, and beads with short fibre were present in the microstructure beyond a polymer concentration of 20wt%. PMID:27612839

  3. 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.

  4. Polarisation-Insensitive Optical Fibre Phase Modulator

    NASA Astrophysics Data System (ADS)

    Kreit, Darran; Youngquist, Robert C.; Giles, Ian P.

    1987-10-01

    An acoustic fibre phase modulator, operating up to a few MHz, is described which employs a piezoelectric plate in a squeezing action. A novel construction using two machined brass v-grooves results in a much reduced sensitivity to optical polarisation and the optimum groove angle is independent of the level of friction on the walls of each groove. A normalised birefringence of 0.04 was achieved at 1.5MHz, with a modulation efficiency of approximately 0.23 rad/Vrms., for a 2cm long device.

  5. Holmium fibre laser with record quantum efficiency

    SciTech Connect

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

    2011-06-30

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

  6. Single fibre electromyographic jitter in multiple sclerosis.

    PubMed Central

    Weir, A; Hansen, S; Ballantyne, J P

    1979-01-01

    Recent histological and electrophysiological reports have given evidence for peripheral nervous system (PNS) involvement in multiple sclerosis. We have applied the single fibre electromyography (SFEMG) technique to 15 patients with multiple sclerosis. Six patients had clearly abnormal jitter and two of these had previously undiagnosed coexistent peripheral neuropathy. A further five patients had borderline abnormalities of SFEMG. The mean jitter for each patient was abnormal in 10 patients. This was clear evidence for PNS involvement in this disease. Theoretically, the site of the abnormality could be in the terminal nerve network or at the neuromuscular junction, but this technique cannot distinguish between these sites. PMID:533854

  7. Investigating the use of coupling agents to improve the interfacial properties between a resorbable phosphate glass and polylactic acid matrix.

    PubMed

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew J; Rudd, Chris D; Walker, Gavin S; Scotchford, Colin A

    2013-09-01

    Eight different chemicals were investigated as potential candidate coupling agents for phosphate glass fibre reinforced polylactic acid composites. Evidence of reaction of the coupling agents with phosphate glass and their effect on surface wettability and glass degradation were studied along with their principle role of improving the interface between glass reinforcement and polymer matrix. It was found that, with an optimal amount of coupling agent on the surface of the glass/polymer, interfacial shear strength improved by a factor of 5. Evidence of covalent bonding between agent and glass was found for three of the coupling agents investigated, namely: 3-aminopropyltriethoxysilane; etidronic acid and hexamethylene diisocyanate. These three coupling agents also improved the interfacial shear strength and increased the hydrophobicity of the glass surface. It is expected that this would provide an improvement in the macroscopic properties of full-scale composites fabricated from the same materials which may also help to retain these properties for the desired length of time by retarding the breakdown of the fibre/matrix interface within these composites.

  8. Investigating the use of coupling agents to improve the interfacial properties between a resorbable phosphate glass and polylactic acid matrix.

    PubMed

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew J; Rudd, Chris D; Walker, Gavin S; Scotchford, Colin A

    2013-09-01

    Eight different chemicals were investigated as potential candidate coupling agents for phosphate glass fibre reinforced polylactic acid composites. Evidence of reaction of the coupling agents with phosphate glass and their effect on surface wettability and glass degradation were studied along with their principle role of improving the interface between glass reinforcement and polymer matrix. It was found that, with an optimal amount of coupling agent on the surface of the glass/polymer, interfacial shear strength improved by a factor of 5. Evidence of covalent bonding between agent and glass was found for three of the coupling agents investigated, namely: 3-aminopropyltriethoxysilane; etidronic acid and hexamethylene diisocyanate. These three coupling agents also improved the interfacial shear strength and increased the hydrophobicity of the glass surface. It is expected that this would provide an improvement in the macroscopic properties of full-scale composites fabricated from the same materials which may also help to retain these properties for the desired length of time by retarding the breakdown of the fibre/matrix interface within these composites. PMID:22781920

  9. Tunable fibre-coupled multiphoton microscopy with a negative curvature fibre.

    PubMed

    Sherlock, Ben; Yu, Fei; Stone, Jim; Warren, Sean; Paterson, Carl; Neil, Mark A A; French, Paul M W; Knight, Jonathan; Dunsby, Chris

    2016-07-01

    Negative curvature fibre (NCF) guides light in its core by inhibiting the coupling of core and cladding modes. In this work, an NCF was designed and fabricated to transmit ultrashort optical pulses for multiphoton microscopy with low group velocity dispersion (GVD) at 800 nm. Its attenuation was measured to be <0.3 dB m(-1) over the range 600-850 nm and the GVD was -180 ± 70 fs(2)  m(-1) at 800 nm. Using an average fibre output power of ∼20 mW and pulse repetition rate of 80 MHz, the NCF enabled pulses with a duration of <200 fs to be transmitted through a length of 1.5 m of fibre over a tuning range of 180 nm without the need for dispersion compensation. In a 4 m fibre, temporal and spectral pulse widths were maintained to within 10% of low power values up to the maximum fibre output power achievable with the laser system used of 278 mW at 700 nm, 808 mW at 800 nm and 420 mW at 860 nm. When coupled to a multiphoton microscope, it enabled imaging of ex vivo tissue using excitation wavelengths from 740 nm to 860 nm without any need for adjustments to the set-up.

  10. Measurement of fibre-fibre contact in three-dimensional images of fibrous materials obtained from X-ray synchrotron microtomography

    NASA Astrophysics Data System (ADS)

    Malmberg, F.; Lindblad, J.; Östlund, C.; Almgren, K. M.; Gamstedt, E. K.

    2011-05-01

    A series of wood-fibre mats was investigated using high-resolution phase-contrast microtomography at the beamline ID 19 of the European Synchrotron Radiation Facility in Grenoble, France. A method for data reduction to quantify the degree of fibre-fibre contact has been derived. The degree of fibre-fibre contact and bonding plays a fundamental role in the mechanical properties of cellulose-fibre mats, paper materials and cellulose-fibre composites. The proposed computerised automated method consists of two parts. First, fibre lumens are segmented using a watershed based method. This information is then used to identify fibre-fibre contacts in projections along the z-axis of the material. The method is tested on microtomographic images of mats made of wood pulp fibres, and is shown to successfully detect differences in the amount of fibre-fibre contact between samples. The degree of fibre-fibre contact correlates well with measured out-of-plane strength of the fibrous material.

  11. Nano-Raman mapping of a porous glass-ceramic SERS substrate in collection mode.

    PubMed

    Zavalin, A; Cricenti, A; Generosi, R; Luce, M; Morgan, S; Piston, D

    2008-03-01

    Porous glass-ceramics is an extremely important material to be used in combination with metallic nanolayers as a Surface-Enhanced Raman Scattering (SERS) substrate for biological and chemical analysis, demonstrating excellent biocompatibility and chemical inertness. These materials show their own Raman background signal lateral distribution, mostly from crystalline skeleton, which has to be considered. A nano-Raman setup using the optical fibre of a Scanning Near-Field Optical Microscope (SNOM), working in collection mode, is described and applied for mapping of such glass-ceramic. The collected Raman signal of Ti and P containing phase distribution in this near-field geometry reaches spatial resolution around 50 nm.

  12. An improved method for using the DTL fibre in electroretinography.

    PubMed

    Thompson, D A; Drasdo, N

    1987-01-01

    An improved method using DTL fibre for electroretinography is described. The DTL fibre is comfortable and easy to apply. Corneal anaesthesia is unnecessary. The DTL fiber does not interfere with the retinal image and has been used successfully to record both pattern and flash electroretinograms from subjects of all ages.

  13. Initial research of dual wavelength fibre optic perimeter sensor

    NASA Astrophysics Data System (ADS)

    Zyczkowski, M.; Kondrat, M.; Ciurapinski, W.

    2005-10-01

    The dual wavelength fibre optic perimeter sensor bases on input signals measurements in an arrangement of fibre optic Michelson and Sagnac interferometers with a 3 × 3 coupler and two semiconductor lasers. For 3 km long sensor we obtained 20-50m resolution of determination of disturbance point.

  14. 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.

  15. Semiconductor disk laser-pumped subpicosecond holmium fibre laser

    SciTech Connect

    Chamorovskiy, A Yu; Marakulin, A V; Leinonen, T; Kurkov, Andrei S; Okhotnikov, Oleg G

    2012-01-31

    The first passively mode-locked holmium fibre laser has been demonstrated, with a semiconductor saturable absorber mirror (SESAM) as a mode locker. Semiconductor disk lasers have been used for the first time to pump holmium fibre lasers. We obtained 830-fs pulses at a repetition rate of 34 MHz with an average output power of 6.6 mW.

  16. Different types of extrafusal muscle fibres in snake costocutaneous muscles

    PubMed Central

    Ridge, R. M. A. P.

    1971-01-01

    1. Tonic and twitch muscle fibres were identified physiologically in m. costocutanei superiores and inferiores of garter snakes and grass snakes. 2. Tonic fibres were multiterminally innervated and showed s.j.p.s in response to nerve stimulation. They did not show propagated A.P.s. They were innervated by motor axons with lower conduction velocities than those to twitch fibres, and often gave a contraction and developed tension in response to a single shock to the nerve. Intracellular square pulse analysis showed that Cm = 1 μF/cm2 and Rm = 40,000 Ω cm2. 3. Twitch fibres showed a conducted action potential in response to nerve stimulation, and focal, as opposed to diffuse, innervation. They showed a variety of isometric twitch contraction times (times-to-peak of about 30-65 msec). Groups of similar motor units contained fibres of approximately similar contraction times. Slow twitch (and tonic) fibres often appeared silvery under dark field illumination, while faster twitch fibres appeared clear. No difference in Cm, Rm or λ was found between faster and slow twitch fibres. Values were approximately 3-4 μF/cm2, 3000-4000 Ω cm2 and 2 mm respectively. ImagesFig. 6 PMID:5097606

  17. Cable analysis in quiescent and active sheep Purkinje fibres.

    PubMed

    Pressler, M L

    1984-07-01

    Cable properties of sheep cardiac Purkinje fibres were studied under resting and paced conditions. Standard micro-electrode techniques were used to apply intracellular current pulses and record the resultant voltage changes at various distances from the current input. In a parallel set of experiments, fibre dimensions were measured after freezing and serial sectioning. Fibres selected on the basis of a cylindrical appearance had approximately uniform cross-sectional diameters which varied +/- 12% along their length. Electrotonic potentials recorded at rest and in diastole (under conditions that minimized diastolic depolarization) adhered quite closely to the behaviour expected for a unidimensional cable provided voltages were recorded greater than or equal to one fibre diameter from the current source. The unidimensional space constant, input resistance, and membrane time constant were significantly larger during quiescence than in diastole. These differences were accounted for by a 90% increase in membrane resistance at rest. There was no significant change in internal longitudinal resistance nor membrane capacitance associated with activity. The voltage distribution close to the current input (i.e. within one fibre diameter) strongly deviated from the theoretical three-dimensional voltage decay expected for a homogeneous cylinder. This finding suggests that the transverse resistance to current flow is much greater than the longitudinal resistance. The anisotropic behaviour within the cardiac Purkinje fibre may explain several previous observations: (i) the lack of a relationship between conduction velocity and fibre diameter; and (ii) the much shorter liminal length for excitation in Purkinje fibres than for point-stimulated squid axons.

  18. Mutations in TPM2 and congenital fibre type disproportion.

    PubMed

    Clarke, Nigel F; Waddell, Leigh B; Sie, Lilian T L; van Bon, Bregje W M; McLean, Catriona; Clark, Damian; Kornberg, Andrew; Lammens, Martin; North, Kathryn N

    2012-11-01

    The main diagnostic feature of congenital fibre type disproportion is that type 1 fibres are consistently smaller than type 2 fibres in the absence of other histological abnormalities. Mutations in the TPM3, RYR1 and ACTA1 genes are the most common established genetic causes. There has been one previous report of congenital fibre type disproportion due to a mutation in TPM2, although some atypical histological features were present. We present two cases in which novel de novo missense mutations in TPM2 are associated with marked fibre size disproportion. The finding of typical histological changes of congenital fibre type disproportion in association with a p.Ser61Pro mutation confirms that TPM2 can cause typical congenital fibre type disproportion. Although not seen on light microscopy studies, protein inclusions typical of small 'caps' were found on electron microscopy in a second patient with a p.Ala155Val mutation in TPM2. This case emphasises the importance of electron microscopy in patients with presumed congenital fibre type disproportion, to exclude the presence of caps, nemaline bodies or minicores, which, if present, may be very helpful in guiding genetic analysis. PMID:22832343

  19. Dietary fibre and health in children and adolescents.

    PubMed

    Edwards, Christine A; Xie, Chengru; Garcia, Ada L

    2015-08-01

    The role of dietary fibre in promoting sustained health has been studied for several decades and in adults there is good evidence that diets rich in high-fibre foods reduce the risk of chronic diseases, including CVD and cancer. Research in this area, however, has been hampered by uncertainties about the definition of dietary fibre which has resulted in many studies measuring fibre in different ways. There is also a wide range of properties and actions of different fibres in the human body, depending on their solubility, viscosity and fermentability by the colonic microbiota. This review considers the epidemiological evidence for dietary fibre and health in children and the current dietary recommendations and measured intakes in several countries using national surveys. In children and adolescents, there is a particular lack of relevant research on which to formulate appropriate dietary fibre recommendations and these are often based on extrapolation from adult data. However, children are not little adults and have differing physiology and nutritional needs as they grow. The dietary recommendations in different countries are based on varying premises and daily amounts. Intakes vary from country to country and on the whole do not meet recommendations. Much more research is needed in children to fully understand the impact of dietary fibre on growth and health in the young to allow more appropriate recommendations to be made.

  20. Filter media properties of mineral fibres produced by plasma spray.

    PubMed

    Prasauskas, Tadas; Matulevicius, Jonas; Kliucininkas, Linas; Krugly, Edvinas; Valincius, Vitas; Martuzevicius, Dainius

    2016-01-01

    The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)).

  1. Fibre operating lengths of human lower limb muscles during walking

    PubMed Central

    Arnold, Edith M.; Delp, Scott L.

    2011-01-01

    Muscles actuate movement by generating forces. The forces generated by muscles are highly dependent on their fibre lengths, yet it is difficult to measure the lengths over which muscle fibres operate during movement. We combined experimental measurements of joint angles and muscle activation patterns during walking with a musculoskeletal model that captures the relationships between muscle fibre lengths, joint angles and muscle activations for muscles of the lower limb. We used this musculoskeletal model to produce a simulation of muscle–tendon dynamics during walking and calculated fibre operating lengths (i.e. the length of muscle fibres relative to their optimal fibre length) for 17 lower limb muscles. Our results indicate that when musculotendon compliance is low, the muscle fibre operating length is determined predominantly by the joint angles and muscle moment arms. If musculotendon compliance is high, muscle fibre operating length is more dependent on activation level and force–length–velocity effects. We found that muscles operate on multiple limbs of the force–length curve (i.e. ascending, plateau and descending limbs) during the gait cycle, but are active within a smaller portion of their total operating range. PMID:21502124

  2. Getting Started with Glass

    ERIC Educational Resources Information Center

    White, Heather

    2007-01-01

    The metamorphosis of glass when heated is a magical process to students, yet teachers are often reluctant to try it in class. The biggest challenge in working with glass in the classroom is to simplify procedures just enough to ensure student success while maintaining strict safety practices so no students are injured. Project concepts and safety…

  3. Glasses and Contact Lenses

    MedlinePlus

    ... Here's Help White House Lunch Recipes Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A Text Size What's ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  4. Surface Conductive Glass.

    ERIC Educational Resources Information Center

    Tanaka, John; Suib, Steven L.

    1984-01-01

    Discusses the properties of surface-conducting glass and the chemical nature of surface-conducting stannic (tin) oxide. Also provides the procedures necessary for the preparation of surface-conducting stannic oxide films on glass substrates. The experiment is suitable for the advanced inorganic chemistry laboratory. (JN)

  5. Physicochemical characterization of oil palm mesocarp fibre treated with glycerol

    NASA Astrophysics Data System (ADS)

    Nor Hamizah M., A.; Roila, A.; Rahimi M., Y.

    2015-09-01

    Lignocellulose has been identified as another source for conversion into value added products. In the present work, physicochemical features from the oil palm mesocarp fibre treated by using pure glycerol with 2% (w/w) NaOH catalyst and crude glycerol have been studied. Treatment was conducted at temperatures 150 °C for 60 min. Fibre treated by crude glycerol resulted in high percentages of holocellulose and lower content of insoluble lignin. These results suggest that crude glycerol can be used as an alternative solvent for pretreatment process. The characterization treated fibre by means of FTIR and TGA has shown significant differences compared to untreated fibre. It was revealed that treated fibre successful eliminated hemicellulose and reduce of lignin content.

  6. Dual hollow-core anti-resonant fibres

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  7. Design and construction of the fibre system for FMOS

    NASA Astrophysics Data System (ADS)

    Murray, Graham J.; Dodsworth, George N.; Content, Robert; Tamura, Naoyuki

    2008-07-01

    A consortium of Japanese, Australian and UK groups has developed a fibre-fed near IR (J & H band) multi-object spectrographic facility (FMOS) for the Subaru telescope. In this second-generation instrument, a novel prime focus 400-fibre multi-object positioning system, ECHIDNA, is optically linked via twin cables to dual IR spectrographs. The spectrographs are located some distance away, on a dedicated platform two levels above Nasmyth. The Centre for Advanced Instrumentation at Durham University oversaw the design and construction of the optical fibre system linking ECHIDNA to the spectrographs. A modularised connector within the cable scheme and an integral back illumination unit additionally featured as part of the Durham work-package. At the time of writing (mid 2008) FMOS, including the fibre system, is installed and functional on-telescope, with commissioning currently underway. This paper provides an overview of the design and construction of the optical fibre system.

  8. Advanced materials and techniques for fibre-optic sensing

    NASA Astrophysics Data System (ADS)

    Henderson, Philip J.

    2014-06-01

    Fibre-optic monitoring systems came of age in about 1999 upon the emergence of the world's first significant commercialising company - a spin-out from the UK's collaborative MAST project. By using embedded fibre-optic technology, the MAST project successfully measured transient strain within high-performance composite yacht masts. Since then, applications have extended from smart composites into civil engineering, energy, military, aerospace, medicine and other sectors. Fibre-optic sensors come in various forms, and may be subject to embedment, retrofitting, and remote interrogation. The unique challenges presented by each implementation require careful scrutiny before widespread adoption can take place. Accordingly, various aspects of design and reliability are discussed spanning a range of representative technologies that include resonant microsilicon structures, MEMS, Bragg gratings, advanced forms of spectroscopy, and modern trends in nanotechnology. Keywords: Fibre-optic sensors, fibre Bragg gratings, MEMS, MOEMS, nanotechnology, plasmon.

  9. Use of Spun optical fibres in current sensors

    SciTech Connect

    Gubin, Vladimir P; Isaev, Victor A; Morshnev, Sergey K; Sazonov, Aleksandr I; Starostin, Nikolay I; Chamorovsky, Yury K; Oussov, Aleksey I

    2006-03-31

    The polarisation properties of a Spun optical fibre are studied in connection with their applications in fibreoptic current sensors based on the Faraday effect. A model of this fibre is proposed which represents it as an anisotropic medium with the spiral structure of the fast and slow birefringence axes. A sensor is developed based on an all-fibre low-coherence linear interferometer with a threshold sensitivity of 70 mA Hz{sup -1/2}, a maximum measured current of 3000 A, and a scale-factor reproducibility of {+-}0.6%. It is found that for a given diameter of the fibre contour, the normalised sensitivity is independent of the fibre length. The experimental results confirm the theory. (laser applications and other topics in quantum electronics)

  10. Glass leaching performance

    SciTech Connect

    Chick, L.A.; Turcotte, R.P.

    1983-05-01

    Current understanding of the leaching performance of high-level nuclear waste (HLW) glass is summarized. The empirical model of waste glass leaching behavior developed shows that at high water flow rates the glass leach rate is kinetically limited to a maximum value. At intermediate water flow rates, leaching is limited by the solution concentration of silica and decreases with decreasing water flow rates. Release of soluble elements is controlled by silica dissolution because silica forms the binding network of the glass. At low water flow rates, mass loss rates reach values controlled by formation rates of alteration minerals, or by diffusion of dissolution products through essentially stagnant water. The parameters reviewed with respect to their quantifiable influence on leaching behavior include temperature, pH, leachant composition, glass composition, thermal history, and radiation. Of these, temperature is most important since the rate of mass loss approximately doubles with each 10/sup 0/C increase in dilute solutions. The pH has small effects within the 4 to 10 range. The chemical composition of the leachant is most important with regard to its influence on alteration product formation. Glass composition exhibits the largest effects at high flow rates where improved glasses leach from ten to thirty times slower than glass 76 to 68. The effects of the thermal history (devitrification) of the glass are not likely to be significant. Radiation effects are important primarily in that radiolysis can potentially drive pH values to less than 4. Radiation damage to the glass causes insignificant changes in leaching performance.

  11. Chrysotile and tremolite asbestos fibres in the lungs and parietal pleura of Corsican goats

    PubMed Central

    Dumortier, P; Rey, F; Viallat, J; Broucke, I; Boutin, C; De Vuyst, P

    2002-01-01

    Methods: Ten goats from areas with asbestos outcrops and two from other areas were slaughtered. Fibre content of lung and parietal pleural samples was determined by analytical transmission electron microscopy. Results: Both chrysotile and tremolite fibres were detected. In the exposed goats, the geometric mean concentrations of asbestos fibres longer than 1 µm were 0.27 x 106 fibres/g dry lung tissue and 1.8 x 106 fibres/g dry pleural tissue. Asbestos fibres were not detected in the lungs of the two control goats. Chrysotile fibres shorter than 5 µm were predominant in the parietal pleura. Tremolite fibres accounted for 78% and 86% of the fibres longer than 5 µm in lung and parietal pleural samples, respectively. Conclusions: Environmental exposure in northeast Corsica results in detectable chrysotile and tremolite fibre loads in the lung and parietal pleura of adult goats. Tremolite fibres of dimensions with a high carcinogenic potency are detected in the parietal pleura. PMID:12205241

  12. Alignement automatise de fibres optiques amorces monomodes

    NASA Astrophysics Data System (ADS)

    St-Amant, Yves

    Cette these jette les bases necessaires au developpement d'algorithmes a base de modele pour l'automatisation de l'alignement de fibres amorces monomodes. A partir de la methode de l'integrale de recouvrement et de deux solutions approximatives existantes, un modele analytique d'efficacite de couplage optique permettant d'estimer la puissance transmise entre un composant et une fibre amorce monomode est d'abord formule. Avec celui-ci, sept proprietes pouvant etre utiles au developpement d'algorithmes a base de modele sont ensuite identifiees et validees. Enfin, a l'aide de ces proprietes, une strategie d'alignement a base de modele est developpee et validee experimentalement. Les resultats obtenus demontrent clairement la repetitivite, la robustesse, la precision et la rapidite de la strategie proposee. Ils demontrent aussi qu'il est possible de realiser un alignement complet sans l'utilisation de systemes auxiliaires tels des systemes de vision, des cameras infrarouges, des capteurs de contact ou des systemes de fixation hautement precis.

  13. Hydrodynamics of diatom chains and semiflexible fibres.

    PubMed

    Nguyen, Hoa; Fauci, Lisa

    2014-07-01

    Diatoms are non-motile, unicellular phytoplankton that have the ability to form colonies in the form of chains. Depending upon the species of diatoms and the linking structures that hold the cells together, these chains can be quite stiff or very flexible. Recently, the bending rigidities of some species of diatom chains have been quantified. In an effort to understand the role of flexibility in nutrient uptake and aggregate formation, we begin by developing a three-dimensional model of the coupled elastic-hydrodynamic system of a diatom chain moving in an incompressible fluid. We find that simple beam theory does a good job of describing diatom chain deformation in a parabolic flow when its ends are tethered, but does not tell the whole story of chain deformations when they are subjected to compressive stresses in shear. While motivated by the fluid dynamics of diatom chains, our computational model of semiflexible fibres illustrates features that apply widely to other systems. The use of an adaptive immersed boundary framework allows us to capture complicated buckling and recovery dynamics of long, semiflexible fibres in shear. PMID:24789565

  14. Spiders spinning electrically charged nano-fibres.

    PubMed

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland-duct-spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders.

  15. Spiders spinning electrically charged nano-fibres.

    PubMed

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland-duct-spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. PMID:25631231

  16. Multifunctional, supramolecular, continuous artificial nacre fibres

    NASA Astrophysics Data System (ADS)

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-10-01

    Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized ``brick-and-mortar'' (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance.

  17. Multifunctional, supramolecular, continuous artificial nacre fibres

    PubMed Central

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-01-01

    Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized “brick-and-mortar” (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance. PMID:23097689

  18. 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.

  19. Defense HLW Glass Degradation Model

    SciTech Connect

    D. Strachan

    2004-10-20

    The purpose of this report is to document the development of a model for calculating the release rate for radionuclides and other key elements from high-level radioactive waste (HLW) glasses under exposure conditions relevant to the performance of the repository. Several glass compositions are planned for the repository, some of which have yet to be identified (i.e., glasses from Hanford and Idaho National Engineering and Environmental Laboratory). The mechanism for glass dissolution is the same for these glasses and the glasses yet to be developed for the disposal of DOE wastes. All of these glasses will be of a quality consistent with the glasses used to develop this report.

  20. Prediction of the reflected spectra from chirped fibre Bragg gratings embedded within cracked crossply laminates

    NASA Astrophysics Data System (ADS)

    Palaniappan, J.; Wang, H.; Ogin, S. L.; Thorne, A.; Reed, G. T.; Tjin, S. C.; McCartney, L. N.

    2006-06-01

    Matrix cracking damage is a generic type of damage that develops under load in the off-axis plies of laminated composites and is generally the precursor of more serious damage mechanisms, particularly delamination. Hence, it is important to identify and if possible locate this type of damage. Chirped fibre Bragg grating sensors have been embedded in a transparent glass fibre reinforced plastic crossply laminate and changes to the reflected spectra as a consequence of crack development have been studied. An approximately sinusoidal variation of the intensity of the reflected spectrum occurs at the position of the crack, enabling both crack development and crack position to be identified. A simulation of a reflected spectrum, incorporating a stress transfer model to predict the strains and an optical model to predict the reflected spectrum, is in reasonable agreement with the experimental results. This article was presented at the 13th International Conference on Sensors and Their Applications, held in Chatham, Kent, on 6-7 September 2005.