Science.gov

Sample records for fibre layer rnfl

  1. Retinal nerve fibre layer thinning is associated with drug resistance in epilepsy

    PubMed Central

    Balestrini, Simona; Clayton, Lisa M S; Bartmann, Ana P; Chinthapalli, Krishna; Novy, Jan; Coppola, Antonietta; Wandschneider, Britta; Stern, William M; Acheson, James; Bell, Gail S; Sander, Josemir W; Sisodiya, Sanjay M

    2016-01-01

    Objective Retinal nerve fibre layer (RNFL) thickness is related to the axonal anterior visual pathway and is considered a marker of overall white matter ‘integrity’. We hypothesised that RNFL changes would occur in people with epilepsy, independently of vigabatrin exposure, and be related to clinical characteristics of epilepsy. Methods Three hundred people with epilepsy attending specialist clinics and 90 healthy controls were included in this cross-sectional cohort study. RNFL imaging was performed using spectral-domain optical coherence tomography (OCT). Drug resistance was defined as failure of adequate trials of two antiepileptic drugs to achieve sustained seizure freedom. Results The average RNFL thickness and the thickness of each of the 90° quadrants were significantly thinner in people with epilepsy than healthy controls (p<0.001, t test). In a multivariate logistic regression model, drug resistance was the only significant predictor of abnormal RNFL thinning (OR=2.09, 95% CI 1.09 to 4.01, p=0.03). Duration of epilepsy (coefficient −0.16, p=0.004) and presence of intellectual disability (coefficient −4.0, p=0.044) also showed a significant relationship with RNFL thinning in a multivariate linear regression model. Conclusions Our results suggest that people with epilepsy with no previous exposure to vigabatrin have a significantly thinner RNFL than healthy participants. Drug resistance emerged as a significant independent predictor of RNFL borderline attenuation or abnormal thinning in a logistic regression model. As this is easily assessed by OCT, RNFL thickness might be used to better understand the mechanisms underlying drug resistance, and possibly severity. Longitudinal studies are needed to confirm our findings. PMID:25886782

  2. Comparison of RNFL thickness and RPE-normalized RNFL attenuation coefficient for glaucoma diagnosis

    NASA Astrophysics Data System (ADS)

    Vermeer, K. A.; van der Schoot, J.; Lemij, H. G.; de Boer, J. F.

    2013-03-01

    Recently, a method to determine the retinal nerve fiber layer (RNFL) attenuation coefficient, based on normalization on the retinal pigment epithelium, was introduced. In contrast to conventional RNFL thickness measures, this novel measure represents a scattering property of the RNFL tissue. In this paper, we compare the RNFL thickness and the RNFL attenuation coefficient on 10 normal and 8 glaucomatous eyes by analyzing the correlation coefficient and the receiver operator curves (ROCs). The thickness and attenuation coefficient showed moderate correlation (r=0.82). Smaller correlation coefficients were found within normal (r=0.55) and glaucomatous (r=0.48) eyes. The full separation between normal and glaucomatous eyes based on the RNFL attenuation coefficient yielded an area under the ROC (AROC) of 1.0. The AROC for the RNFL thickness was 0.9875. No statistically significant difference between the two measures was found by comparing the AROC. RNFL attenuation coefficients may thus replace current RNFL thickness measurements or be combined with it to improve glaucoma diagnosis.

  3. Macular and peripapillary retinal nerve fibre layer thickness in patients with cyanotic congenital heart disease

    PubMed Central

    de Aguiar Remigio, M C; Brandt, C T; Santos, C C L; Arantes, T E; de Aguiar, M I R

    2015-01-01

    Purpose To evaluate macular and retinal nerve fibre layer (RNFL) measurements in patients with cyanotic congenital heart disease (cCHD) using spectral domain optical coherence tomography (OCT). Patients and methods Thirty patients with cCHD (18 females and 12 males, mean age 10.9 years) and 60 healthy controls (35 females and 25 males, mean age 11.2 years) underwent complete ophthalmologic examination and OCT measurements of macular and peripapillary RNFL thickness. Results Patients with cCHD had significantly thinner measurements in all macular subfields compared with healthy controls (P<0.001). There was no significant difference in peripapillary RNFL thickness between the two groups, with the exception of the upper quadrant, for which thickness measurements were higher in patients with cCHD (P=0.021). Conclusions Patients with cCHD showed a significant decrease in macular thickness and a thickened superior quadrant RNFL thickness when compared with healthy controls. This may represent the damage caused by the effect of hypoxia. PMID:25592129

  4. Retinal Nerve Fibre Layer and Macular Thinning in Spinocerebellar Ataxia and Cerebellar Multisystem Atrophy

    PubMed Central

    Pula, John H.; Towle, Vernon L.; Staszak, Victoria M.; Cao, Dingcai; Bernard, Jacqueline T.; Gomez, Christopher M.

    2011-01-01

    The spinocerebellar ataxias, like all neurodegenerative diseases, lack objective disease- and stage-specific biomarkers. Based on reports of clinically evident optic disc atrophy or retinal disease in some ataxia patients, and the discovery that pre-symptomatic retinal thinning occurs in other neurologic diseases such as multiple sclerosis, we tested the hypothesis that subclinical neuronal or axonal loss in the retina could occur in the degenerative ataxias. Spectral domain optical coherence tomography was performed on 29 ataxia patients with genetically proven spinocerebellar ataxia (SCA) 1, 2, 3, or 6, or multisystem atrophy type C (MSA-C) and 27 age-matched normal subjects. Ataxia patients were assessed using the scale for assessment and rating of ataxia. Compared with normal control subjects, retinal nerve fibre layer (RNFL) thickness was reduced for patients with SCA2 and SCA3, and thickness in the macular region was reduced for all SCAs but SCA2. PMID:21866205

  5. Effect of Refractive Status and Axial Length on Peripapillary Retinal Nerve Fibre Layer Thickness: An Analysis Using 3D OCT

    PubMed Central

    Sowmya, V.; Venkataramanan, V.R.

    2015-01-01

    Background Accurate measurement of retinal nerve fiber layer (RNFL) is now possible with the high resolution optical coherence tomography (OCT). Effect of refractive status of the eye on RNFL thickness may be relevant in the diagnosis of glaucoma and other optic nerve diseases. Aim To assess the RNFL thickness and compare its correlation with refractive status and axial length of the eye. Material and Methods Three hundred eyes of 150 patients were included in this study, who underwent RNFL analysis using TOPCON 3D OCT 2000. Analysis of variance has been used to find the significance of study parameters between the study groups. Results The study showed that refractive status/axial length affected the peripapillary RNFL thickness significantly. Conclusion The study suggests that the diagnostic accuracy of OCT may be improved by considering refractive status and axial length of the eye when RNFL is measured. PMID:26500931

  6. Rapid layered manufacturing of short-fibre-reinforced parts

    NASA Astrophysics Data System (ADS)

    Zak, Gennady

    Rapid Prototyping (RP) expedites the transition from the design concept to a physical model. With RP, objects are created from thin layers, i.e., by Layered Manufacturing (LM). The most common LM technique, stereolithography, uses a liquid photopolymer selectively solidified by an ultraviolet laser. Mechanical properties of photopolymers can be improved by the addition of short-glass-fibres. In this thesis, a novel process for Rapid Layered Composites Manufacturing (RLCM) is developed. RLCM overcomes several fabrication problems caused by the introduction of fibres into the photopolymer liquid: (1) thin layer formation from a viscous mixture; (2) fibre settling; and (3) lack of inter-layer fibre penetration. The distinguishing features of the proposed process are: (1) external fibre-resin mixing supply source; (2) precisely controlled liquid deposition from above; and (3) selective solidification by a scanning pattern with layer-to-layer interconnecting features. To arrive at the above process synthesis, first, the basic properties of the constituent materials were experimentally investigated; second, the RLCM process, originally synthesized using the Axiomatic Design Theory, was iteratively improved upon by analysis of the fabricated parts. The constituent materials were studied to evaluate the fibre-photopolymer interaction. The high strength of the fibre-solid photopolymer interface was verified by single-fibre pull-out tests. Fibre-liquid photopolymer interaction was observed through rheological measurements which determined the relationship between the composite liquid's viscosity and (a) the fibre concentration and (b) the fibre aspect ratio. Axiomatic Design Theory was employed for RLCM-process synthesis. The present design resulted from several cycles of evaluation and modification based upon the Independence and Information Axioms. RLCM process output was analyzed in terms of parts' geometric quality and mechanical properties. The geometric quality was assessed by examining individual layers. Fluid-mechanical layer-formation models were employed to interpret layer-to-layer thickness variations. Modelling mechanical properties of the short-fibre composites requires information about the fibre orientation and length. Thus, three-dimensional fibre-orientation distribution was measured with a novel methodology where two closely spaced consecutive cross-sections are examined. The method's novelty lies in accurately calculating the transformation between the cross-sections and additionally estimating the fibre length. Mechanical properties of layered composites are of importance since such parts may directly serve as functional prototypes. These properties were modelled employing modified rule of mixtures. The models matched well the tensile test results, which demonstrated a significant improvement (80%) in modulus with reinforcements.

  7. Cellulose fibre networks reinforced with carboxymethyl cellulose/chitosan complex layer-by-layer.

    PubMed

    Wu, Tongfei; Farnood, Ramin

    2014-12-19

    An eco-friendly and full-polysaccharide polyelectrolyte complex system was developed to enhance the wet and dry tensile strength of cellulose fibre networks. Cellulose fibres were treated by carboxymethyl cellulose (CMC) in pulp suspension. Paper sheets made from CMC-treated fibres were further modified via the layer-by-layer (LbL) deposition of CMC/chitosan (CS) complex. The effect of number of CMC/CS layers on the strength properties of cellulose fibre networks (both under wet and dry conditions) was studied and sample structure was investigated by scanning electron microscopy (SEM). Water vapour transmission rate (WVTR) of CMC/CS-treated samples was also examined. The observed changes in the strength properties of treated samples were explained based on the competition between the rate of diffusion of CS to the fibre-fibre bond areas and the rate of disassociation of fibre-fibre interactions during the LbL deposition process. PMID:25263919

  8. Quantitative RNFL attenuation coefficient measurements by RPE-normalized OCT data

    NASA Astrophysics Data System (ADS)

    Vermeer, K. A.; van der Schoot, J.; Lemij, H. G.; de Boer, J. F.

    2012-03-01

    We demonstrate significantly different scattering coefficients of the retinal nerve fiber layer (RNFL) between normal and glaucoma subjects. In clinical care, SD-OCT is routinely used to assess the RNFL thickness for glaucoma management. In this way, the full OCT data set is conveniently reduced to an easy to interpret output, matching results from older (non- OCT) instruments. However, OCT provides more data, such as the signal strength itself, which is due to backscattering in the retinal layers. For quantitative analysis, this signal should be normalized to adjust for local differences in the intensity of the beam that reaches the retina. In this paper, we introduce a model that relates the OCT signal to the attenuation coefficient of the tissue. The average RNFL signal (within an A-line) was then normalized based on the observed RPE signal, resulting in normalized RNFL attenuation coefficient maps. These maps showed local defects matching those found in thickness data. The average (normalized) RNFL attenuation coefficient of a fixed band around the optic nerve head was significantly lower in glaucomatous eyes than in normal eyes (3.0mm-1 vs. 4.9mm-1, P<0.01, Mann-Whitney test).

  9. Nerve fibre layer loss in diseases of the outer retinal layer.

    PubMed Central

    Newman, N M; Stevens, R A; Heckenlively, J R

    1987-01-01

    We present examples of nerve fibre layer changes in diseases thought to affect primarily the outer retinal layers. These disease processes include cone-rod dystrophies, rod-cone dystrophies, juvenile macular degeneration (Stargardt's disease) and fundus flavimaculatis, vitelliform macular dystrophy, and Leber's congenital amaurosis. All were associated with alterations in the retinal nerve fibre layer, either diffuse or focal. The presence of these nerve fibre layer changes raises the question of transsynaptic degeneration and of possible primary or associated disease of other retinal cells than the receptors-namely, bipolar, amacrine, Mueller, or ganglion cells--in these disease of the outer retinal layer. Involvement of the nerve fibre layer also indicates the need to examine patients with defects in the nerve fibre layer by electroretinograms and other tests for outer retinal layer disease when no obvious optic nerve disease is present. Images PMID:3814566

  10. Hyperelastic modelling of arterial layers with distributed collagen fibre orientations

    PubMed Central

    Gasser, T. Christian; Ogden, Ray W; Holzapfel, Gerhard A

    2005-01-01

    Constitutive relations are fundamental to the solution of problems in continuum mechanics, and are required in the study of, for example, mechanically dominated clinical interventions involving soft biological tissues. Structural continuum constitutive models of arterial layers integrate information about the tissue morphology and therefore allow investigation of the interrelation between structure and function in response to mechanical loading. Collagen fibres are key ingredients in the structure of arteries. In the media (the middle layer of the artery wall) they are arranged in two helically distributed families with a small pitch and very little dispersion in their orientation (i.e. they are aligned quite close to the circumferential direction). By contrast, in the adventitial and intimal layers, the orientation of the collagen fibres is dispersed, as shown by polarized light microscopy of stained arterial tissue. As a result, continuum models that do not account for the dispersion are not able to capture accurately the stress–strain response of these layers. The purpose of this paper, therefore, is to develop a structural continuum framework that is able to represent the dispersion of the collagen fibre orientation. This then allows the development of a new hyperelastic free-energy function that is particularly suited for representing the anisotropic elastic properties of adventitial and intimal layers of arterial walls, and is a generalization of the fibre-reinforced structural model introduced by Holzapfel & Gasser (Holzapfel & Gasser 2001 Comput. Meth. Appl. Mech. Eng. 190, 4379–4403) and Holzapfel et al. (Holzapfel et al. 2000 J. Elast. 61, 1–48). The model incorporates an additional scalar structure parameter that characterizes the dispersed collagen orientation. An efficient finite element implementation of the model is then presented and numerical examples show that the dispersion of the orientation of collagen fibres in the adventitia of human iliac arteries has a significant effect on their mechanical response. PMID:16849214

  11. Photography of the retinal nerve fibre layer: an optimised procedure.

    PubMed Central

    Frisén, L

    1980-01-01

    Normal and abnormal fundi were photographed at various magnifications in one and the same fundus camera, with and without 'red-free' filters and various types of black-and-white and colour films. Colour diapositive films were copied on various black-and-white negative films, with and without filters. The final negatives were evaluated under magnification with regard to resolution and contrast of detail in the nerve fibre layer. Complementary information was obtained by means of conventional resolution measurements at high and low contrast levels. The best overall results were obtained by copying colour slides obtained in unfiltered light on a new high-contrast black-and-white film (Kodak Technical Pan), with a Wratten No. 65 A filter. This simple technique produced negatives with a good definition of the nerve fibre layer, suitable as final records. Images PMID:7426584

  12. Liquid core fibre versus doped sol-gel layered structured fibre for chemical sensing

    NASA Astrophysics Data System (ADS)

    Canning, John; Huyang, George; Åslund, Mattias L.; Naqshbandi, Masood; Stocks, Danial; Crossley, Maxwell J.

    2010-10-01

    We review recent work on evaluating the performance of a simple porphyrin-based acid sensor using structured fibre technology. Specifically, the same sensor in a multimode liquid core is compared to that in a sol-gel coated structured optical fibre. General implications for fibre chemical sensing are discussed.

  13. Embedding metallic jacketed fused silica fibres into stainless steel using additive layer manufacturing technology

    NASA Astrophysics Data System (ADS)

    Maier, Robert R. J.; Havermann, Dirk; MacPherson, William N.; Hand, Duncan P.

    2013-05-01

    Metal clad single mode optical fibres are successfully embedded into stainless steel using a layer by layer based additive manufacturing technology based on selective laser sintering of powered stainless steel material. The single mode fibre has been coated with a protective Ni metal layer to facilitate thermal protection and bonding to the stainless steel matrix. A loss of ~1 dB is observed after embedding which is attributed to micro bending in the embedded section.

  14. Effects of increasing the fibre content of a layer diet.

    PubMed

    Longe, O G

    1984-04-01

    The fibre content of a basal diet fed to laying hens was increased from 149.2 g to between 218.6 and 292.3 g/kg by the inclusion of various fibrous farm wastes and by-products at 200 g/kg diet. The fibrous ingredients lowered the metabolisable energy (ME) of the basal diet from 11.82 to between 9.31 and 11.21 MJ/kg. Utilisation (g food/kg egg) of the basal diet was not significantly different from values for diets containing maize cob, cassava or maize starch residues. The diet containing maize cob supported a performance similar to that of the basal diet, despite a lower energy content (10.08 MJ/kg). Diets containing cowpea shell, cassava peel or sawdust, with lower energy contents, and those containing maize starch residue, palm kernel meal or dried brewers grains, with higher energy contents, were not as good. The diet containing cassava starch residue supported similar egg production to the basal but egg size was less. Inclusion of some of the fibre sources caused slight decreases in yolk cholesterol, although this could not be correlated with dietary fibre content. Additional dietary fibre caused slight increases in gizzard weight but this was also not simply related to dietary fibre content. PMID:6329485

  15. Morphometric evaluation of changes with time in optic disc structure and thickness of retinal nerve fibre layer in chronic ocular hypertensive monkeys.

    PubMed

    Shimazawa, Masamitsu; Tomita, Goji; Taniguchi, Takazumi; Sasaoka, Masaaki; Hara, Hideaki; Kitazawa, Yoshiaki; Araie, Makoto

    2006-03-01

    We examined the time course of changes in optic disc structure by means of a scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT) in ocular hypertensive (experimental glaucoma) monkeys, and clarified the relationships between the histological RNFL thickness and HRT parameters. Further, the time course of changes in retinal nerve fiber layer (RNFL) thickness in individual eyes was measured using a scanning laser polarimeter with fixed corneal polarization compensator (GDx FCC). In the present study, two separate experiments were carried out. A chronic intraocular pressure (IOP) elevation was induced by laser trabeculoplasty in the left eye in 11 cynomolgus monkeys. In Experiment 1, the HRT and GDx parameters were measured 12 weeks after the laser treatment in 10 eyes in five monkeys. In Experiment 2, the time course of changes in the HRT and GDx parameters was examined before and 1, 3, 4, 5, 6, 8, 10, 12, 14, and 16 weeks after the laser treatment in 12 eyes in six monkeys. The retardation values (thickness parameters) obtained from the GDx were used to derive thickness and ratio parameters in the superior, inferior, nasal and temporal quadrants. Ratio parameters were expressed as a ratio of superior and inferior quadrant to nasal quadrant. After the last measurements, each eye was enucleated, and retinal cross sections were prepared for histological analysis. In the left (hypertensive) eyes, IOP was persistently elevated throughout the observation periods in both Experiments 1 and 2. In the HRT measurements in Experiment 1, seven out of eight global topographic parameters (exception, disc area) were statistically different between the hypertensive and control eyes 12 weeks after the laser treatment. In Experiment 2, the HRT parameters changed in a time-dependent manner, but each of them almost plateaued at about 4 weeks after the laser treatment. Significant correlations were seen between the histological mean RNFL thickness at 1.5 disc diameters from the optic disc margin and the HRT parameters in 21 eyes from 11 monkeys in Experiments 1 and 2. Especially good correlations with histological mean RNFL thickness were seen for the rim volume and cup volume. In Experiment 1, good correlations were found between GDx ratio parameters and histological RNFL thickness in individual right control eyes (n=5). In individual left experimental glaucoma eyes of Experiment 2 (n=6), GDx ratio parameters declined in a time-dependent manner alongside the IOP elevation. In conclusion, alongside the IOP elevation, time-related changes in optic disc topography and RNFL thickness were demonstrated in monkey eyes using HRT and GDx. HRT (rim and cup) parameters showed good correlations with histological RNFL thickness, and significant interrelations. PMID:16388801

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    PubMed Central

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

    2015-01-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m−2 h−1 bar−1 for water, and 0.14 to 7.5 L m−2 h−1 bar−1 for acetone, with an unchanged low molecular weight cut off (~250 Da). PMID:26527173

  18. Exploring the room temperature self-assembly of silica nanoparticle layers on optical fibres

    NASA Astrophysics Data System (ADS)

    Canning, John; Lindoy, Lachlan; Huyang, George; Naqshbandi, Masood; Cook, Kevin; Crossley, Maxwell J.; Luo, Yanhua; Peng, Gang-Ding; Glavind, Lars; Kristensen, Martin

    2013-08-01

    The room temperature deposition of self-assembling silica nanoparticles onto D-shaped optical fibres ("D-fibre"), drawn from milled preforms fabricated by modified chemical vapor deposition, is studied and preliminary results reported here. Of various techniques explored, an automated "dip-and-withdraw" approach is found to give the most reproducible layers. Vertical dip-and-withdraw produces tapered layers with one end thicker (surface coverage < 0.85) than the other whilst horizontal dip-and-withdraw produces much more uniform layers over the core region. The problem of induced fracturing is shown to originate from the sides of the D-fibre flat, attributed to an extended, linear "coffee stain effect", and is greatest for horizontal dip-and-withdraw. Under optimal preparation conditions they can be minimised and prevented from extending over the core region. Alternatively, these structures can be made periodic potentially enabling some unique structures to be fabricated since post-deposition of functional species will be highest in these cracks.

  19. Determination of the layer-specific distributed collagen fibre orientations in human thoracic and abdominal aortas and common iliac arteries

    PubMed Central

    Schriefl, Andreas J.; Zeindlinger, Georg; Pierce, David M.; Regitnig, Peter; Holzapfel, Gerhard A.

    2012-01-01

    The established method of polarized microscopy in combination with a universal stage is used to determine the layer-specific distributed collagen fibre orientations in 11 human non-atherosclerotic thoracic and abdominal aortas and common iliac arteries (63 ± 15.3 years, mean ± s.d.). A dispersion model is used to quantify over 37 000 recorded fibre angles from tissue samples. The study resulted in distinct fibre families, fibre directions, dispersion and thickness data for each layer and all vessels investigated. Two fibre families were present for the intima, media and adventitia in the aortas, with often a third and sometimes a fourth family in the intima in the respective axial and circumferential directions. In all aortas, the two families were almost symmetrically arranged with respect to the cylinder axis, closer to the axial direction in the adventitia, closer to the circumferential direction in the media and in between in the intima. The same trend was found for the intima and adventitia of the common iliac arteries; however, there was only one preferred fibre alignment present in the media. In all locations and layers, the observed fibre orientations were always in the tangential plane of the walls, with no radial components and very small dispersion through the wall thickness. A wider range of in-plane fibre orientations was present in the intima than in the media and adventitia. The mean total wall thickness for the aortas and the common iliac artery was 1.39 and 1.05 mm, respectively. For the aortas, a slight thickening of the intima and a thinning of the media in increasingly distal regions were observed. A clear intimal thickening was present distal to the branching of the celiac arteries. All data, except for the media of the common iliac arteries, showed two prominent collagen fibre families for all layers so that two-fibre family models seem most appropriate. PMID:22171063

  20. Effect of transition layers on the electromagnetic properties of composites containing conducting fibres

    NASA Astrophysics Data System (ADS)

    Makhnovskiy, D. P.; Panina, L. V.; Mapps, D. J.; Sarychev, A. K.

    2001-10-01

    The approach to calculating the effective dielectric and magnetic response in bounded composite materials is developed. The method is essentially based on the renormalization of the dielectric matrix parameters to account for the surface polarization and the displacement currents at the interfaces. This makes possible the use of the effective-medium theory developed for unbounded materials, where the spatially dependent local dielectric constant and magnetic permeability are introduced. A detailed mathematical analysis is given for a dielectric layer having conducting fibres with in-plane positions. The surface effects are most essential at microwave frequencies in correspondence to the resonance excitation of fibres. In thin layers (having a thickness of the transition layer), the effective dielectric constant has a dispersion region at much higher frequencies compared to those for unbounded materials, exhibiting a strong dependence on the layer thickness. For the geometry considered, the effective magnetic permeability differs slightly from unity and corresponds to the renormalized matrix parameter. The magnetic effect is due entirely to the existence of the surface displacement currents.

  1. Xylan deposition and lignification in the multi-layered cell walls of phloem fibres in Mallotus japonicus (Euphorbiaceae).

    PubMed

    Nakagawa, Kaori; Yoshinaga, Arata; Takabe, Keiji

    2014-09-01

    Phloem fibres in Mallotus japonicus Mll. Arg. were found to have a multi-layered structure that is S1?+?S2?+?n(G?+?L), where a non-lignified gelatinous layer (G) and a lignified layer (L) are formed alternately and n indicates the number of repetitions of these two layers. The aim of this study was to determine the process of xylan deposition and lignification in the multi-layered cell walls of phloem fibres. The formation process of the multi-layered structure of secondary phloem fibres was examined by light microscopy, ultraviolet microscopy and transmission electron microscopy. The distribution of glucuronoxylan was examined by immunoelectron microscopy. The activity of peroxidase was also determined using metal-enhanced diaminobenzidine substrates. Immunolabelling of glucuronoxylan occurred in lignified cell wall layers, except in the compound middle lamella (CML), i.e., the S1, S2 and L layers but not the G layers. Change in immunolabelling density suggests that xylan deposition in these lignified layers occurs appositionally, i.e., xylan is deposited into the lignified layers directly and not by a penetrative mechanism, and deposition does not occur after the layers are fully deposited. Peroxidase activity was found in CML including cell corners during S2 layer formation, then in developing G layers during G layer formation. Peroxidase activity was also found in the thin L layers that formed recently and was not found in the L layers already present. Xylan labelling was not found in the thin L layers that formed recently but did occur in L layers that developed earlier. Lignification of the S1 and S2 layers continued during the formation of the G layers, whereas in the L layers it finished just after deposition of the L layer. PMID:25151648

  2. Selenium adsorption and speciation with Mg-FeCO? layered double hydroxides loaded cellulose fibre.

    PubMed

    Chen, Ming-Li; An, Myog-Il

    2012-06-15

    A novel adsorbent was developed by coating Mg-FeCO(3) layered double hydroxides (LDHs) on cellulose fibre. The LDHs take up significant amount of selenite and selenate in a wide pH range with similar sorption capacities (pH 3.8-8.0 for selenite and pH 5.8-7.0 for selenate). A mini-column packed with Mg-FeCO(3) LDHs layer coated cellulose fibre particles was incorporated into a sequential injection system for uptake of selenite at pH 6.0. The retained selenite was afterwards collected with 70 ? L of 0.8%(m/v) NaOH as eluent, followed by hydride generation and atomic fluorescence spectrometric detection. Total inorganic selenium was adsorbed at pH 6.0 by the LDHs-cellulose fibre mini-column after selenate was pre-reduced to selenite by 2.0 mol L(-1) HCl at 80C, and selenium speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 13.3 was derived with a detection limit of 11 ng L(-1) within a linear range of 0.04-4.0 ?g L(-1). A relative standard deviation (RSD) of 3.3% (0.5 ?g L(-1), n=11) was achieved. The procedure was validated by analyzing selenium in a certified reference material GBW 10010 (rice), and speciation of inorganic selenium in natural water samples. PMID:22748552

  3. Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance

    NASA Astrophysics Data System (ADS)

    Senokos, E.; Reguero, V.; Palma, J.; Vilatela, J. J.; Marcilla, Rebeca

    2016-02-01

    In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m2 g-1, high electrical conductivity (3.5 × 105 S m-1) and mechanical properties in the high-performance range including toughness (35 J g-1) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg-1 and 14 Wh kg-1, respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V.In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m2 g-1, high electrical conductivity (3.5 × 105 S m-1) and mechanical properties in the high-performance range including toughness (35 J g-1) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg-1 and 14 Wh kg-1, respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07697h

  4. Discrimination of reactively-dyed cotton fibres with thin layer chromatography and UV microspectrophotometry.

    PubMed

    De Wael, K; Van Dijck, K; Gason, F

    2015-12-01

    Reactively-dyed black, navy blue and medium red cotton samples showing metamerism under fluorescent tube illumination were examined. Optical microscopy (bright field, polarization and fluorescence microscopy) was used, followed by microspectrometry in the visible range (MSP Vis), to differentiate the samples in each block of colours. Additionally, the non-discriminated samples were subjected both to microspectrophotometry in the UV-range (MSP UV) and to enzymatic digestion followed by high performance thin layer chromatography (HPTLC) on the digests. While it was found that both methods may potentially result in higher discrimination, preparation of reactively-dyed cotton for HPTLC was found to be a very tedious and time-consuming step and HPTLC only led to a better discrimination than MSP UV for the red cotton samples. The results suggest that in order to increase the discrimination for reactively-dyed cotton fibres, measurement of the UV absorption spectrum (MSP UV) is preferred over HPTLC. PMID:26654077

  5. Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance.

    PubMed

    Senokos, E; Reguero, V; Palma, J; Vilatela, J J; Marcilla, Rebeca

    2016-02-01

    In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m(2) g(-1), high electrical conductivity (3.5 × 10(5) S m(-1)) and mechanical properties in the high-performance range including toughness (35 J g(-1)) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg(-1) and 14 Wh kg(-1), respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V. PMID:26809811

  6. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    SciTech Connect

    Giancardo, Luca; Meriaudeau, Fabrice; Karnowski, Thomas Paul; Li, Yaquin; Tobin Jr, Kenneth William; Chaum, Edward

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

  7. Detection of Retinal Nerve Fiber Layer Defects in Alzheimer’s Disease Using SD-OCT

    PubMed Central

    Kromer, Robert; Serbecic, Nermin; Hausner, Lucrezia; Froelich, Lutz; Aboul-Enein, Fahmy; Beutelspacher, Sven C.

    2014-01-01

    Introduction: Our aim is to examine the clinical value of spectral-domain optical coherence tomography (Spectralis OCT) to detect retinal nerve fibre layer defects in patients with clinically defined Alzheimer‘s disease (AD). Material and Methods: This cross-sectional study included 22 patients with AD (mean age: 75.9 ± 6.1 years) and 22 healthy age- and sex-matched controls. Neuro-ophthalmologic examinations and a series of high-resolution OCT examinations of the peripapillary retinal nerve fiber layer (RNFL) thickness using the Spectralis 3.5-mm circle scan protocol with ART-Modus and eye tracking were obtained, and compared to age- and sex-matched healthy control subjects. Results: Patients with AD showed a significant decrease in RNFL thickness in the nasal superior sector compared to the control group (101.0 ± 18.18 μm versus 122.8 ± 28.08 μm; P < 0.0001). In all other sectors, independently of disease duration, no significant difference in RNFL thickness compared to controls was detected. Using the advanced age- and gender-matched measurement model, 32 out of 42 eyes (76.19%) as pathologic with 67 abnormal sectors were detected. Discussion: As examined by spectral-domain OCT, patients with mild to moderate stages of AD showed a significant reduction of RNFL thickness in the nasal superior sector. Nevertheless, successive studies are needed. PMID:24616709

  8. Remote gaseous acid sensing within a porphyrin-doped TiO2 sol-gel layer inside a structured optical fibre

    NASA Astrophysics Data System (ADS)

    Huyang, George; Canning, John; Åslund, Mattias L.; Naqshbandi, Masood; Stocks, Danial; Crossley, Maxwell J.

    2010-09-01

    A porphyrin containing sol-gel layer has been deposited within the interior of the channels of a silica structured optical fibre. Gaseous HCl detection based on protonation of the porphyrin and observed as a change in the spectrum is demonstrated. This system is compared to previous work based on an acid sensor within a liquid-core fibre. The signal-to- noise of this type of fibre system shows a higher level of sensitivity than the liquid-core and has a forty-fold acid diffusion rate increase due to the different medium for acidification.

  9. Effect of optic nerve sheath fenestration for idiopathic intracranial hypertension on retinal nerve fiber layer thickness.

    PubMed

    Starks, Victoria; Gilliland, Grant; Vrcek, Ivan; Gilliland, Connor

    2016-04-01

    The objective of the study was to evaluate whether optic nerve sheath fenestration in patients with idiopathic intracranial hypertension was associated with improvement in visual field pattern deviation and optical coherence tomography retinal nerve fiber layer thickness.The records of 13 eyes of 11 patients who underwent optic nerve sheath fenestration were reviewed. The subjects were patients of a clinical practice in Dallas, Texas. Charts were reviewed for pre- and postoperative visual field pattern deviation (PD) and retinal nerve fiber layer thickness (RNFL).PD and RNFL significantly improved after surgery. Average PD preoperatively was 8.51 DB and postoperatively was 4.80 DB (p = 0.0002). Average RNFL preoperatively was 113.63 and postoperatively was 102.70 (p = 0.01). The preoperative PD and RNFL did not correlate strongly.Our results demonstrate that PD and RNFL are improved after optic nerve sheath fenestration. The pre- and postoperative RNFL values were compared to the average RNFL value of healthy optic nerves obtained from the literature. Post-ONSF RNFL values were significantly closer to the normal value than preoperative. RNFL is an objective parameter for monitoring the optic nerve after optic nerve sheath fenestration. This study adds to the evidence that OCT RNFL may be an effective monitoring tool for patients with IIH and that it continues to be a useful parameter after ONSF. PMID:26928128

  10. Numerical implementation of constitutive model for arterial layers with distributed collagen fibre orientations.

    PubMed

    Skacel, Pavel; Bursa, Jiri

    2015-01-01

    Several constitutive models have been proposed for the description of mechanical behaviour of soft tissues containing collagen fibres. Some of the commonly used approaches accounting for the dispersion of fibre orientations are based on the summation of (mechanical) contributions of differently oriented fibre families. This leads to the need of numerical integration on the sphere surface, and the related numerical consumption is the main disadvantage of this category of constitutive models. The paper is focused on the comparison of various numerical integration methods applied to a specific constitutive model applicable for arterial walls. Robustness and efficiency of several integration rules were tested with respect to application in finite element (FE) codes. Among all the analysed numerical integration rules, the best results were reached by Lebedev quadrature; the related parameters for the specific constitutive model are presented in the paper. The results were implemented into the commercial FE code ANSYS via user subroutines, and their applicability was demonstrated by an example of FE simulation with non-homogenous stress field. PMID:24168517

  11. Retinal Nerve Fiber Layer Thickness Measurement Comparison Using Spectral Domain and Swept Source Optical Coherence Tomography

    PubMed Central

    Ha, Ahnul; Lee, Seung Hyen; Lee, Eun Ji

    2016-01-01

    Purpose To investigate the retinal nerve fiber layer (RNFL) thickness concordance when measured by spectral domain (SD) and swept source (SS) optical coherence tomography (OCT), and to compare glaucoma-discriminating capability. Methods RNFL thicknesses were measured with the scan circle, centered on the optic nerve head, in 55 healthy, 41 glaucoma suspected, and 87 glaucomatous eyes. The RNFL thickness measured by the SD-OCT (sdRNFL thickness) and SS-OCT (ssRNFL thickness) were compared using the t-test. Bland-Altman analysis was performed to examine their agreement. We compared areas under the receiver operating characteristics curve and examined sdRNFL and ssRNFL thickness for discriminating glaucomatous eyes from healthy eyes, and from glaucoma suspect eyes. Results The average ssRNFL thickness was significantly greater than sdRNFL thickness in healthy (110.0 ± 7.9 vs. 100.1 ± 6.8 µm, p < 0.001), glaucoma suspect (96.8 ± 9.3 vs. 89.6 ± 7.9 µm, p < 0.001), and glaucomatous eyes (74.3 ± 14.2 vs. 69.1 ± 12.4 µm, p = 0.011). Bland-Altman analysis showed that there was a tendency for the difference between ssRNFL and sdRNFL to increase in eyes with thicker RNFL. The area under the curves of the average sdRNFL and ssRNFL thickness for discriminating glaucomatous eyes from healthy eyes (0.984 vs. 0.986, p = 0.491) and glaucoma suspect eyes (0.936 vs. 0.918, p = 0.132) were comparable. Conclusions There was a tendency for ssRNFL thickness to increase, compared with sdRNFL thickness, in eyes with thicker RNFL. The ssRNFL thickness had comparable diagnostic capability compared with sdRNFL thickness for discriminating glaucomatous eyes from healthy eyes and glaucoma suspect eyes. PMID:27051263

  12. Longitudinal Changes in Retinal Nerve Fiber Layer Thickness after Intravitreal Anti-vascular Endothelial Growth Factor Therapy

    PubMed Central

    Jo, Young-Joon; Kim, Woo-Jin; Shin, Il-Hwan

    2016-01-01

    Purpose To determine the effects of intravitreal anti-vascular endothelial growth factor (VEGF) on thickness of the retinal nerve fiber layer (RNFL) in patients with age-related macular degeneration. Methods Twenty eyes of 20 patients diagnosed with age-related macular degeneration who underwent intravitreal anti-VEGF injection were studied. Postinjection RNFL thickness was measured using optical coherence tomography. Average thickness, four-quadrant RNFL thicknesses, and intraocular pressure (IOP) in affected eyes were measured before and 6 and 12 months after anti-VEGF injection for comparison. RNFL thickness and IOP in affected and normal fellow eyes were also compared. Given that macular lesions can affect RNFL thickness, the changes in thickness were evaluated by dividing the 12 clock-hour RNFL into the pathologic areas adjacent to the lesion and the non-pathologic area. Results The mean clock-hour segment in the pathologic area was 4.8 hours. A significantly thicker RNFL was exhibited in temporal quadrants and pathologic areas (p = 0.043 and 0.048, respectively) in affected eyes before injection compared to the baseline RNFL thickness in normal eyes. No significant differences were found in RNFL thickness or IOP between affected and normal eyes after injection. The changes over time in the temporal and pathologic areas were statistically significant at 6 and 12 months after injection compared to baseline data (p < 0.05). No significant differences were displayed in RNFL thickness in the other three quadrants or in non-pathologic areas in either affected or normal eyes. Sequential changes in RNFL thickness in affected eyes were not significant. Conclusions Repeat intravitreal anti-VEGF treatment did not have a significant effect on RNFL thickness. RNFL thickness significantly decreased with time in the pathologic areas and in the temporal segment adjacent to exudative macular lesions. The reduction in RNFL thickness was most likely associated with changes in the macular lesion rather than with anti-VEGF injection. PMID:27051259

  13. Fibre orientation and the conduction of heat by a gas enclosed in ceramic layers

    NASA Astrophysics Data System (ADS)

    Keller, K.; Blumenberg, J.; Tomsik, J.

    1988-08-01

    Fibrous layers are an essential constituent of future heat protection systems. The conduction of heat by a gas enclosed in fibrous layers depends on layer and fiber density, mean fiber diameter and fiber orientation. Consideration of fiber orientation improves the correlation between model predictions and experimental results. It also permits a better explanation of the pressure dependence of convective heat transport.

  14. Near-Surface Motion in the Nocturnal, Stable Boundary Layer Observed with Fibre-Optic Distributed Temperature Sensing

    NASA Astrophysics Data System (ADS)

    Zeeman, Matthias J.; Selker, John S.; Thomas, Christoph K.

    2015-02-01

    The evolution of cold air layers near the surface was investigated for a night with stable conditions near the surface. Spatial air temperature observations at 276 co-located vertical profiles were made using high-resolution fibre-optic based distributed temperature sensing (DTS) in a quasi three-dimensional geometry oriented along a shallow depression in the landscape and analysed for patterns in near-surface flow. Temperature stratification was observed to be interrupted by transient temperature structures on the scale of metres for which the flow direction and velocity could be quantified. The high spatial resolution and large spatial domain of the DTS revealed temperature structures in a level of detail that exceeded the capability of traditional point observations of air temperature at low wind speeds. Further, composition techniques were applied to describe wave-like motions in the opposite direction of the mean flow, at intervals of approximately 200 s (5 mHz). The DTS technique delivered tomography on a scale of tens of metres. The spatial observations at high spatial (fractions of a metre) and temporal (sec) resolution provided new opportunities for detection and quantification of surface-flow features and description of complicated scale interactions. High-resolution DTS is therefore a valuable addition to experimental research on stable and weak-wind boundary layers near the surface.

  15. Correlation of localized glaucomatous visual field defects and spectral domain optical coherence tomography retinal nerve fiber layer thinning using a modified structure–function map for OCT

    PubMed Central

    Wu, H; de Boer, J F; Chen, L; Chen, T C

    2015-01-01

    Purpose To study the correlation between glaucomatous visual field (VF) defects assessed by standard automated perimetry (SAP) and peripapillary retinal nerve fiber layer (RNFL) thinning measured by spectral domain optical coherence tomography (OCT) using a modified OCT-based peripapillary RNFL structure–function map. Patients and methods Perimetric glaucoma patients and age-matched normal control subjects were recruited from a university hospital clinic. All eyes underwent testing with the Spectralis spectral domain OCT and SAP on the same day. An OCT-based correspondence map, which correlated VF areas with peripapillary RNFL sectors was created to evaluate the relationship between glaucomatous RNFL thinning and VF loss in six nerve fiber layer bundle areas. Correlations of RNFL thinning with corresponding VF defects were examined using Spearman rank-order correlations. To demonstrate the association between localized VF defects and RNFL thickness, the theoretical curves were made according to an established log-linear model. The measured RNFL thickness values and VF defects were presented in the same scatterplot for each sector. Results Fifty-six glaucoma patients and 85 normal subjects were included in the study. Significant association between localized VF loss and RNFL thinning was found in corresponding areas. Data from the current study fit well with established log-linear models, which compare RNFL thickness values with VF defects. Conclusion Analysis of RNFL thinning in eyes with localized glaucomatous VF defects showed good structure–function correlation in a new OCT-based structure–function correspondence map. PMID:25633881

  16. Large-deformation analysis of the elastic recoil of fibre layers in a Brinkman medium with application to the endothelial glycocalyx

    NASA Astrophysics Data System (ADS)

    Han, Yuefeng; Weinbaum, Sheldon; Spaan, Jos A. E.; Vink, Hans

    2006-05-01

    There is wide interest in the role of the endothelial surface layer (ESL) in transmitting blood shear stress to the intracellular cytoskeleton of the endothelial cell. However, very little is known about the mechanical properties of the glycocalyx or the flexural rigidity of the core proteins that comprise it. Vink, Duling & Spaan (FASEB J., vol. 13, 1999, p. A 11) measured the time-dependent restoration of the ESL after it had been nearly completely compressed by the passage of a white blood cell (WBC) in a tightly fitting capillary. Using this initial experiment, Weinbaum et al. (Proc. Natl. Acad. Sci. USA, vol. 100, 2003, p. 7988) predicted that the core proteins have a flexural rigidity EI of 700 pN nm(2) , which is ˜1/20 the measured value for an actin filament. However, their analysis assumes small deflections and only the fibre motion is considered. In the present paper we report additional experiments and apply large-deformation theory for ‘elastica’ to describe the restoration of the fibres in a Brinkman medium which absorbs fluid as the ESL expands. We find that there are two phases in the fibre recoil: an initial phase for large compressions where the ESL thickness is <0.36 its undisturbed thickness, and the ends of the fibres overlap and are parallel to the capillary wall; and a second phase where the fibres assume a shape that is close to the solutions for an elastic bar with linearly distributed vertical loading. The predicted time-dependent change in thickness of the ESL provides remarkably good agreement with experiment and yields an estimate of 490 pN nm(2) for the flexural rigidity EI of the core protein fibres, which is unexpectedly close to that predicted by the linear theory in Weinbaum et al. (2003).

  17. Reduction in Retinal Nerve Fiber Layer Thickness in Young Adults with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Emberti Gialloreti, Leonardo; Pardini, Matteo; Benassi, Francesca; Marciano, Sara; Amore, Mario; Mutolo, Maria Giulia; Porfirio, Maria Cristina; Curatolo, Paolo

    2014-01-01

    Recent years have seen an increase in the use of retinal nerve fiber layer (RNFL) evaluation as an easy-to-use, reproducible, proxy-measure of brain structural abnormalities. Here, we evaluated RNFL thickness in a group of subjects with high functioning autism (HFA) or with Asperger Syndrome (AS) to its potential as a tool to study autism

  18. Reduction in Retinal Nerve Fiber Layer Thickness in Young Adults with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Emberti Gialloreti, Leonardo; Pardini, Matteo; Benassi, Francesca; Marciano, Sara; Amore, Mario; Mutolo, Maria Giulia; Porfirio, Maria Cristina; Curatolo, Paolo

    2014-01-01

    Recent years have seen an increase in the use of retinal nerve fiber layer (RNFL) evaluation as an easy-to-use, reproducible, proxy-measure of brain structural abnormalities. Here, we evaluated RNFL thickness in a group of subjects with high functioning autism (HFA) or with Asperger Syndrome (AS) to its potential as a tool to study autism…

  19. Bismuth-ring-doped fibres

    SciTech Connect

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

    2009-11-30

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

  20. Retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in children with obesity

    PubMed Central

    Demir, Selim; Özer, Samet; Alim, Sait; Güneş, Alper; Ortak, Hüseyin; Yılmaz, Resul

    2016-01-01

    AIM To evaluate retinal nerve fiber layer (RNFL) thickness analysis of peripapillary optic nerve head (PONH) and macula as well as ganglion cell-inner plexiform layer (GCIPL) thickness in obese children. METHODS Eighty-five children with obesity and 30 controls were included in the study. The thicknesses of the PONH and macula of each subject's right eye were measured by high-resolution spectral-domain optic coherence tomography (OCT). RESULTS The RNFL thicknesses of central macular and PONH were similar between the groups (all P>0.05). The GCIPL thickness was also similar between the groups. However, the RNFL thickness of temporal outer macula were 261.7±13.7 and 268.9±14.3 µm for the obesity and the control group, respectively (P=0.034). CONCLUSION Obesity may cause a reduction in temporal outer macular RNFL thickness. PMID:27158616

  1. The Relationship between Visual Field Global Indices and Retinal Nerve Fiber Layer Thickness in Healthy Myopes

    PubMed Central

    Yuan, Yuan-zhi; Feng, Chen-li; Li, Bao-yue; Shen, Min-qian; Chen, Xiu-ping; Zhang, Chen-hao; Dong, Chun-qiong; Yuan, Fei

    2014-01-01

    The aim of the current study was to investigate the association between the thickness of the retinal nerve fiber layer (RNFL) and central visual field indices in otherwise healthy myopes. In total, 57 otherwise healthy subjects were cross-sectionally studied. General ophthalmic examinations, refractive measurements, RNFL thickness by spectral domain optical coherence tomography (OCT), and central visual fields were examined. Linear models were used to assess the associations. In this young and mid-aged population, the mean spherical equivalent was −4.79 (SD 1.66) and −4.59 (SD 1.88) diopters in the right and left eyes, respectively. Approximately 7% to 14% of the eyes showed the average RNFL thickness out of the normal range. The temporal RNFL was remarkably thicker, whereas the nasal RNFL was thinner. The higher the refractive error, the thinner the RNFL thickness. A thicker overall RNFL was significantly associated with decreased mean sensitivity and increased mean defect, and further adjustments for age, sex, refractive error, optic disk area, or ocular magnification did not change the association. Although nonpathologic myopia does not significantly affect central visual field global indices, its effects on the RNFL may be linked with performance on the central visual field test. PMID:25436141

  2. Thickness related textural properties of retinal nerve fiber layer in color fundus images.

    PubMed

    Odstrcilik, Jan; Kolar, Radim; Tornow, Ralf-Peter; Jan, Jiri; Budai, Attila; Mayer, Markus; Vodakova, Martina; Laemmer, Robert; Lamos, Martin; Kuna, Zdenek; Gazarek, Jiri; Kubena, Tomas; Cernosek, Pavel; Ronzhina, Marina

    2014-09-01

    Images of ocular fundus are routinely utilized in ophthalmology. Since an examination using fundus camera is relatively fast and cheap procedure, it can be used as a proper diagnostic tool for screening of retinal diseases such as the glaucoma. One of the glaucoma symptoms is progressive atrophy of the retinal nerve fiber layer (RNFL) resulting in variations of the RNFL thickness. Here, we introduce a novel approach to capture these variations using computer-aided analysis of the RNFL textural appearance in standard and easily available color fundus images. The proposed method uses the features based on Gaussian Markov random fields and local binary patterns, together with various regression models for prediction of the RNFL thickness. The approach allows description of the changes in RNFL texture, directly reflecting variations in the RNFL thickness. Evaluation of the method is carried out on 16 normal ("healthy") and 8 glaucomatous eyes. We achieved significant correlation (normals: ρ=0.72±0.14; p≪0.05, glaucomatous: ρ=0.58±0.10; p≪0.05) between values of the model predicted output and the RNFL thickness measured by optical coherence tomography, which is currently regarded as a standard glaucoma assessment device. The evaluation thus revealed good applicability of the proposed approach to measure possible RNFL thinning. PMID:24906911

  3. Thickness, Phase Retardation, Birefringence, and Reflectance of the Retinal Nerve Fiber Layer in Normal and Glaucomatous Non-Human Primates

    PubMed Central

    Dwelle, Jordan; Liu, Shuang; Wang, Bingqing; McElroy, Austin; Ho, Derek; Markey, Mia K.; Milner, Thomas; Rylander, H. Grady

    2012-01-01

    Purpose. We identified candidate optical coherence tomography (OCT) markers for early glaucoma diagnosis. Time variation of retinal nerve fiber layer (RNFL) thickness, phase retardation, birefringence, and reflectance using polarization sensitive optical coherence tomography (PS-OCT) were measured in three non-human primates with induced glaucoma in one eye. We characterized time variation of RNFL thickness, phase retardation, birefringence, and reflectance with elevated intraocular pressure (IOP). Methods. One eye of each of three non-human primates was laser treated to increase IOP. Each primate was followed for a 30-week period. PS-OCT measurements were recorded at weekly intervals. Reflectance index (RI) is introduced to characterize RNFL reflectance. Associations between elevated IOP and RNFL thickness, phase retardation, birefringence, and reflectance were characterized in seven regions (entire retina, inner and outer rings, and nasal, temporal, superior and inferior quadrants) by linear and non-linear mixed-effects models. Results. Elevated IOP was achieved in three non-human primate eyes with an average increase of 13 mm Hg over the study period. Elevated IOP was associated with decreased RNFL thickness in the nasal region (P = 0.0002), decreased RNFL phase retardation in the superior (P = 0.046) and inferior (P = 0.021) regions, decreased RNFL birefringence in the nasal (P = 0.002) and inferior (P = 0.029) regions, and loss of RNFL reflectance in the outer rings (P = 0.018). When averaged over the entire retinal area, only RNFL reflectance showed a significant decrease (P = 0.028). Conclusions. Of the measured parameters, decreased RNFL reflectance was the most robust correlate with glaucomatous damage. Candidate cellular mechanisms are considered for decreased RNFL reflectance, including mitochondrial dysfunction and retinal ganglion cell apoptosis. PMID:22570345

  4. Correlation of Retinal Nerve Fiber Layer Thickness and Visual Fields in Glaucoma: A broken stick model

    PubMed Central

    Alasil, Tarek; Wang, Kaidi; Yu, Fei; Field, Matthew G.; Lee, Hang; Baniasadi, Neda; de Boer, Johannes F.; Coleman, Anne L.; Chen, Teresa C.

    2015-01-01

    Purpose To determine the retinal nerve fiber layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss. Design Retrospective cross-sectional study. Methods Eighty seven healthy and 108 glaucoma subjects (one eye per subject) were recruited from an academic institution. All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey visual field analyzer 750i; Carl Zeiss Meditec, Dublin, CA) and spectral domain optical coherence tomography RNFL scans (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Comparison of RNFL thicknesses values with VF threshold values showed a plateau of VF threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values. A broken stick statistical analysis was utilized to estimate the tipping point at which RNFL thickness values are associated with VF defects. The slope for the association between structure and function was computed for data above and below the tipping point. Results The mean RNFL thickness value that was associated with initial VF loss was 89 μm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 μm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73 μm. The differences between all the slopes above and below the aforementioned tipping points were statistically significant (p<0.001). Conclusions In open angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable. PMID:24487047

  5. Associations between retinal nerve fiber layer abnormalities and optic nerve examination(e–Pub ahead of print)

    PubMed Central

    Cettomai, D.; Hiremath, G.; Ratchford, J.; Venkatesan, A.; Greenberg, B.M.; McGready, J.; Pardo, C.A.; Kerr, D.A.; Frohman, E.; Balcer, L.J.; McArthur, J.C.; Calabresi, P.A.

    2010-01-01

    Objective: Retinal nerve fiber layer (RNFL) abnormalities detected by optical coherence tomography (OCT) are useful markers for axonal loss and visual dysfunction in multiple sclerosis (MS), but their role in routine clinical management is not well-studied. Methods: Clinical and OCT examinations were performed on 240 patients attending a neurology clinic. Using OCT 5th percentile to define abnormal RNFL thickness, we compared eyes classified by neurologists as having optic atrophy to RNFL thickness, and afferent pupillary defect (APD) to RNFL thickness ratios of eye pairs. Results: Mean RNFL thickness was less in eyes classified by neurologists as having optic atrophy (79.4 ± 21 μm; n = 63) vs those without (97.0 ± 15 μm; n = 417; p < 0.001, t test) and in eyes with an APD (84.1 ± 16 μm; n = 44) than without an APD (95.8 ± 17 μm; n = 436; p < 0.001). Physicians' diagnostic accuracy for detecting pallor in eyes with an abnormal RNFL thickness was 79% (sensitivity = 0.56; specificity = 0.82). Accuracy for detecting a RAPD in patients with mean RNFL ratio (affected eye to unaffected eye) <0.90 was 73% (sensitivity = 0.30; specificity = 0.86). Ability to detect visual pathway injury via assessment of atrophy and APD differed between neurologists. Conclusions: OCT reveals RNFL abnormality in many patients in whom eyes are not classified by neurologic examiners as having optic atrophy. Further study is needed to define the role of OCT measures in the context of examinations for optic atrophy and APD by neuroophthalmologists. OCT-measured RNFL thickness is likely to have an important future role in the clinical setting. GLOSSARY APD = afferent pupillary defect; MS = multiple sclerosis; OCT = optical coherence tomography; RNFL = retinal nerve fiber layer. PMID:20810997

  6. Evaluation of the effect of intravitreal ranibizumab injections in patients with neovascular age related macular degeneration on retinal nerve fiber layer thickness using optical coherence tomography

    PubMed Central

    El-Ashry, Mohamed F; Lascaratos, Gerassimos; Dhillon, Baljean

    2015-01-01

    Purpose To evaluate the effect of repeated intravitreal ranibizumab injections for neovascular age related macular degeneration (nAMD) on the retinal nerve fiber layer (RNFL) thickness using optical coherence tomography. Design A prospective observational cohort study of patients with nAMD. Methods Thirty eyes of 30 patients with nAMD were selected. All patients received three ranibizumab injections and underwent scans using the fast RNFL thickness protocol (Stratus optical coherence tomography) before starting the first injection and 1 month after the third injection. The RNFL thickness measurements prior to the injections and after the third injection were used for the analysis. We also evaluated the effect of the lens status as well as the type of choroidal neovascular membrane on RNFL thickness measurements pre- and post-injection. Pre- and post-injection average and individual quadrant RNFL thickness were measured and statistically analyzed. Results The mean (± standard deviation) pre-injection RNFL thickness was 90.8±18. The mean (± standard deviation) post-injection RNFL thickness was 91.03±15. The pre- and post-injection values of the mean RNFL thickness were not statistically significant. Likewise, the pre- and post-injection values for RNFL thickness in the different quadrants were not statistically significant. There was no statistical significance for the lens status or the type of choroidal neovascular membrane on the RNFL thickness. Conclusion Repeated ranibizumab injections in nAMD appear to have no harmful effect on the RNFL thickness in the short term, in spite of the proven neurotrophic effect of vascular endothelial growth factor. Nevertheless, the safety profile of ranibizumab injections in nAMD needs to be further evaluated in a large multicenter trial with special emphasis on the long-term effects on the retina and optic nerve. PMID:26203216

  7. Fibre Models

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Kun, F.

    2007-12-01

    Fibre models have been introduced as simple models to describe failure. They are based on the probability distribution of broken fibres. The load redistribution after a fibre yields can be global or local and the first case can often be solved analytically. We will present an interpolation between these the local and the global case and apply it to experimental situations like the compression of granular packings. Introducing viscoelastic fibres allows to describe the creep of wood. It is even possible to deal analytically with a gradual degradation of fibres and consider damage as well as healing. In this way Basquin's law of fatigue can be reproduced and new universalities concerning the histograms of bursts and waiting times can be uncovered.

  8. Dietary fibre, diabetes and obesity.

    PubMed

    Smith, U

    1987-01-01

    An increased intake of dietary fibre appears to be useful for the treatment of both obesity and diabetes mellitus. Fibre-rich food is usually satisfying without being calorically dense. Supplementing a normal diet with gel-forming fibres, such as guar gum, leads to an increased satiation probably due to a slower gastric emptying. Recent long-term studies have confirmed the usefulness of viscous fibres as an adjunct to regular dietary treatment of obesity. Apart from a beneficial effect during caloric restriction, dietary fibre may improve some of the metabolic aberrations seen in obesity. Gel-forming fibres are particularly effective in reducing elevated LDL-cholesterol without changing the HDL-fraction. Impaired glucose tolerance or manifest diabetes is also improved. These effects are probably in part associated with the gelling property of the fibre which leads to an increased viscosity of the unstirred layer thereby delaying the absorption process. Other sources of dietary fibre with a high content of viscous gums, such as oats, have been shown to reduce LDL-cholesterol. Increased intake of viscous fibre leads to a gradual reduction in fasting glucose levels in diabetics. The reason for this is unclear but it cannot readily be explained by a delayed absorption process. Since insulin levels are also reduced these findings suggest that insulin resistance is alleviated. Recent studies with the euglycemic clamp technique support this possibility. Glucose uptake by isolated fat cells and both insulin sensitivity and responsiveness are also increased. PMID:3032822

  9. Fibre typing of intrafusal fibres

    PubMed Central

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

    2015-01-01

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

  10. Co-extrusion of electrolyte/anode functional layer/anode triple-layer ceramic hollow fibres for micro-tubular solid oxide fuel cells-electrochemical performance study

    NASA Astrophysics Data System (ADS)

    Li, Tao; Wu, Zhentao; Li, K.

    2015-01-01

    In this study, the effects of an anode functional layer (AFL) with controlled thickness on physical and electrochemical properties of a micro-tubular SOFC have been systematically studied. A series of electrolyte/AFL/anode triple-layer hollow fibres with controllable AFL thicknesses (16.9-52.7 μm) have been fabricated via a single-step phase-inversion assisted co-extrusion technique. Both robustness of the cell and gas-tightness of the electrolyte layer are considerably improved by introducing the AFL of this type. The fracture force of the sample with the thickest AFL (9.67 N) almost doubles when compared to the electrolyte/anode dual-layer counterpart (5.24 N). Gas-tightness of the electrolyte layer is also considerably increased as AFL contributes to better-matched sintering behaviours between different components. Moreover, the formation of an AFL simultaneously with electrolyte and anode significantly improves the cell performances. The sample with the thinnest AFL (approximately 16.9 μm, 6% of the total anode thickness) leads to a 30% (from 0.89 to 1.21 W cm-2) increase in maximum power density, due to increased triple-phase boundaries (TPB). However, further increase in TPB from a thicker AFL is less effective for improving the cell performance, due to the substantially increased fuel diffusion resistance and subsequently higher concentration polarization. This indicates that the control over the AFL thickness is critically important in avoiding offsetting the benefits of extended TPB and consequently decreased cell performances.

  11. Wall modified photonic crystal fibre capillaries as porous layer open tubular columns for in-capillary micro-extraction and capillary chromatography.

    PubMed

    Kazarian, Artaches A; Sanz Rodriguez, Estrella; Deverell, Jeremy A; McCord, James; Muddiman, David C; Paull, Brett

    2016-01-28

    Wall modified photonic crystal fibre capillary columns for in-capillary micro-extraction and liquid chromatographic separations is presented. Columns contained 126 internal parallel 4 μm channels, each containing a wall bonded porous monolithic type polystyrene-divinylbenzene layer in open tubular column format (PLOT). Modification longitudinal homogeneity was monitored using scanning contactless conductivity detection and scanning electron microscopy. The multichannel open tubular capillary column showed channel diameter and polymer layer consistency of 4.2 ± 0.1 μm and 0.26 ± 0.02 μm respectively, and modification of 100% of the parallel channels with the monolithic polymer. The modified multi-channel capillaries were applied to the in-capillary micro-extraction of water samples. 500 μL of water samples containing single μg L(-1) levels of polyaromatic hydrocarbons were extracted at a flow rate of 10 μL min(-1), and eluted in 50 μL of acetonitrile for analysis using HPLC with fluorescence detection. HPLC LODs were 0.08, 0.02 and 0.05 μg L(-1) for acenaphthene, anthracene and pyrene, respectively, with extraction recoveries of between 77 and 103%. The modified capillaries were also investigated briefly for direct application to liquid chromatographic separations, with the retention and elution of a standard protein (cytochrome c) under isocratic conditions demonstrated, proving chromatographic potential of the new column format, with run-to-run retention time reproducibility of below 1%. PMID:26755132

  12. Evaluation of Retinal Nerve Fiber Layer and Ganglion Cell Complex in Patients with Optic Neuritis or Neuromyelitis Optica Spectrum Disorders Using Optical Coherence Tomography in a Chinese Cohort

    PubMed Central

    Tian, Guohong; Li, Zhenxin; Zhao, Guixian; Feng, Chaoyi; Li, Mengwei; Huang, Yongheng; Sun, Xinghuai

    2015-01-01

    We evaluate a cohort of optic neuritis and neuromyelitis optica (NMO) spectrum disorders patients in a territory hospital in China. The peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) were measured using spectral-domain OCT after 6 months of acute onset. The results showed that both the peripapillary RNFL and macular GCC were significantly thinner in all optic neuritis subtypes compared to controls. In addition, the recurrent optic neuritis and NMO groups showed more severe damage on the RNFL and GCC pattern. PMID:26649191

  13. Meta-analysis of the relationship of peripheral retinal nerve fiber layer thickness to Alzheimer’s disease and mild cognitive impairment

    PubMed Central

    WANG, Meijuan; ZHU, Yinbo; SHI, Zhongyong; LI, Chunbo; SHEN, Yuan

    2015-01-01

    Background Previous studies report that the thickness of the peripheral retinal nerve fiber layer (RNFL) in individuals with Alzheimer's disease (AD) and mild cognitive impairment (MCI) is significantly thinner than in normal controls (NC), but RNFL thickness in different quadrants of the optic nerve remains unclear. Aim Conduct a systematic review of studies that assess peripheral RNFL thickness in AD and MCI. Methods Based on pre-defined criteria, studies in English or Chinese were identified from PubMed, Embase, ISI web of knowledge, Ovid/Medline, Science Direct, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Chongqing VIP database, WANFANG DATA, and the China BioMedical Literature Service System (SinoMed). Review Manager 5.3 was used for analysis. Results The 19 cross-sectional studies identified had a pooled sample of 1455 individuals. There was substantial heterogeneity between studies that compared RNFL in AD or MCI to normal controls, but this heterogeneity was primarily restricted to low-quality studies. Combining 6 high-quality studies (n=578) indicated that total RNFL thickness and the thickness of superior and inferior RNFL quadrants in AD were significantly thinner than in normal controls. Similarly, combining 5 high-quality studies (n=541) indicated significantly thinner total RNFL thickness in MCI than in controls. Six studies (n=589) found thinner RNFL in the superior and inferior quadrants in MCI than in controls;and 6 studies (n=487) found thinner RNFL in the temporal quadrant in MCI than in controls. Finally, 7 studies (n=432) indicated that total RNFL was thinner in AD than in MCI, and 6 studies (n=364) indicated thinner RNFL in the superior and inferior quadrants in AD than in MCI. Conclusion Much of the heterogeneity in results from previous studies may be due to poor methodology. Peripheral RNFL thicknesses, particularly in the superior and inferior quadrants, becomes progressively thinner as cognitive function declines, so this could be a candidate biomarker for early identification of AD. Methodologically rigorous studies in large population-based cohort studies that follow elderly individuals over time and that simultaneously collect information on potential mediating factors (such as blood pressure, blood glucose, and lipid levels) are needed to confirm or disprove the potential predictive value of RNFL. PMID:26977124

  14. Comparison of the nerve fiber layer of type 2 diabetic patients without glaucoma with normal subjects of the same age and sex

    PubMed Central

    Takis, Alexandros; Alonistiotis, Dimitrios; Panagiotidis, Dimitrios; Ioannou, Nikolaos; Papaconstantinou, Dimitris; Theodossiadis, Panagiotis

    2014-01-01

    Background The retinal nerve fiber layer (RNFL) thickness in patients with diabetes mellitus type 2 was compared to normal subjects of similar age and sex, having first excluded any risk factors for glaucoma. The correlation between the RNFL thickness and the severity of diabetic retinopathy was investigated at its primary stages and with other ocular and diabetic parameters. Methods A prospective, case series study was carried out. Twenty-seven diabetic patients without diabetic retinopathy, 24 diabetic patients with mild retinopathy, and 25 normal, age-matched subjects underwent a complete ophthalmological examination and imaging with scanning laser polarimetry for the evaluation of the RNFL. Multivariate analysis was applied in order to investigate the correlation between RNFL and diabetic parameters, such as age, duration of diabetes, insulin therapy, levels of glycosylated hemoglobin; and ocular parameters, such as cup to disc ratio, levels of normal intraocular pressure, and central corneal thickness. Results The mean inferior average of RNFL and the temporal-superior-nasal-inferior-temporal standard deviation were statistically significantly lower in both diabetic groups, and the nerve fiber index was higher (P=0.04) compared to the normal group. There was no statistically significant difference between the diabetic groups. The factor analysis showed no significant correlation between the RNFL and the previously mentioned diabetic and ocular parameters. Conclusion The existence of diabetes should be seriously considered in evaluating the results of scanning laser polarimetry. Multivariate analysis for RNFL was used for the first time. PMID:24596452

  15. The attenuation of retinal nerve fiber layer thickness and cognitive deterioration

    PubMed Central

    Shen, Yuan; Shi, Zhongyong; Jia, Renbao; Zhu, Yikang; Cheng, Yan; Feng, Wei; Li, Chunbo

    2013-01-01

    Thinner retinal nerve fiber layer (RNFL) has been reported in Alzheimer’s disease (AD) patient. However, whether changes in RNFL thickness can predict the cognitive deterioration remains unknown. We therefore set out a prospective clinical investigation to determine the potential association between the attenuation of RNFL thickness and the deterioration of cognitive function over a period of 25 months. We assessed cognitive function using the Repeatable Battery for the Assessment of Neuropsychological Status and measured RNFL thickness employing optical coherence tomography in 78 participants (mean age 72.31 ± 3.98 years, 52% men). The participants were categorized as stable participants whose cognitive status remained no change (N = 60) and converted participants whose cognitive status deteriorated (N = 18). We found that there was an association between the attenuation of superior quadrant RNFL thickness and the deterioration of cognitive function in the stable participants. In the converted participants, however, there was an inverse association between the reduction of inferior quadrant RNFL thickness and decline of cognitive functions [scores of list recall (R = -0.670, P = 0.002), adjusted (R = -0.493, P = 0.031)]. These data showed that less reduction in the inferior quadrant of RNFL thickness might indicate a higher risk for the patients to develop cognitive deterioration. These findings have established a system to embark a larger scale study to further test whether changes in RNFL thickness can serve as a biomarker of AD, and would lead to mechanistic studies to determine the cellular mechanisms of cognitive deterioration. PMID:24065883

  16. Longitudinal Study of Vision and Retinal Nerve Fiber Layer Thickness in MS

    PubMed Central

    Talman, Lauren S.; Bisker, Esther R.; Sackel, David J.; Long, David A.; Galetta, Kristin M.; Ratchford, John N.; Lile, Deacon J.; Farrell, Sheena K.; Loguidice, Michael J.; Remington, Gina; Conger, Amy; Frohman, Teresa C.; Jacobs, Dina A.; Markowitz, Clyde E.; Cutter, Gary R.; Ying, Gui-Shuang; Dai, Yang; Maguire, Maureen G.; Galetta, Steven L.; Frohman, Elliot M.; Calabresi, Peter A.; Balcer, Laura J.

    2010-01-01

    Objective Cross-sectional studies of optical coherence tomography (OCT) show that retinal nerve fiber layer (RNFL) thickness is reduced in multiple sclerosis (MS) and correlates with visual function. We determined how longitudinal changes in RNFL thickness relate to visual loss. We also examined patterns of RNFL thinning over time in MS eyes with and without a prior history of acute optic neuritis (ON). Methods Patients underwent OCT measurement of RNFL thickness at baseline and at 6-month intervals during a mean follow-up of 18 months at three centers. Low-contrast letter acuity (2.5%, 1.25% contrast) and visual acuity (VA) were assessed. Results Among 299 patients (593 eyes) with ≥6 months follow-up, eyes with visual loss showed greater RNFL thinning compared to eyes with stable vision (low-contrast acuity, 2.5%: p<0.001; VA: p=0.005). RNFL thinning increased over time, with average losses of 2.9 μm at 2-3 years and 6.1 μm at 3-4.5 years (p<0.001 vs. 0.5-1-year follow-up interval). These patterns were observed for eyes with or without prior history of ON. Proportions of eyes with RNFL loss greater than test-retest variability (≥6.6 μm) increased from 11% at 0-1 year to 44% at 3-4.5 years (p<0.001). Interpretation Progressive RNFL thinning occurs as a function of time in some patients with MS, even in the absence of ON, and is associated with clinically significant visual loss. These findings are consistent with sub-clinical axonal loss in the anterior visual pathway in MS and support the use of OCT and low-contrast acuity as methods to evaluate the effectiveness of putative neuroprotection protocols. PMID:20517936

  17. Retinal Nerve Fiber Layer Thickness in Myopic, Emmetropic, and Hyperopic Children

    PubMed Central

    Lee, Jacky W.Y.; Yau, Gordon S.K.; Woo, Tiffany T.Y.; Yick, Doris W.F.; Tam, Victor T.Y.; Lai, Jimmy S.M.

    2015-01-01

    Abstract The purpose of this study was to investigate the peripapillary retinal nerve fiber layer (RNFL) thickness in myopic, emmetropic, and hyperopic children using optical coherence tomography. Two-hundred one right eyes of subjects aged 4 to 18 years were divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<−1.0 D), emmetropes (≥−1.0 to ≤+1.0 D), and hyperopes (>+1.0 D). The RNFL was correlated with age, spherical equivalent, and axial length. The RNFL was compared between the 3 groups before and after age adjustment. The RNFL was thickest in the hyperopic group (107.2 ± 10.13 μm, n = 73), followed by the emmetropic group (102.5 ± 9.2 μm, n = 61), and then the myopic group (95.7 ± 10.3, n = 67) (all P < 0.0001). The myopic group (9.6 ± 3.9 years) was significantly older than the emmetropic (6.9 ± 2.7 years) and hyperopic (6.5 ± 1.9 years) groups (both P < 0.0001). When adjusted for age, myopes had a thinner RNFL than the other 2 groups (all P < 0.0001), but there was no RNFL thickness difference between the emmetropic and hyperopic groups (P > 0.05). A thinner RNFL was associated with an older age (r = −0.4, P < 0.0001), a more myopic spherical equivalent (r = 0.5, P < 0.0001), and a longer axial length (r = −0.4, P < 0.0001) on Pearson correlation analysis. The apparently thicker RNFL in hyperopic and emmetropic children was attributed to their younger age as compared with their myopic counterparts. When adjusted for age, only myopia was associated with a thinner RNFL, with emmetropic and hyperopic children having equal RNFL thicknesses. Advancing age, a more myopic spherical equivalent, and a longer axial length were associated with a thinner RNFL in children. PMID:25816043

  18. Macular ganglion cell-inner plexiform layer thinning in patients with visual field defect that respects the vertical meridian.

    PubMed

    Shin, Hye-Young; Park, Hae-Young Lopilly; Choi, Jin-A; Park, Chan Kee

    2014-09-01

    The aim of this work is to compare the thinning patterns of the ganglion cell inner-plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (pRNFL) as measured using Cirrus high-definition optical coherence tomography (HD-OCT) in patients with visual field (VF) defects that respect the vertical meridian. Twenty eyes of 11 patients with VF defects that respect the vertical meridian were enrolled retrospectively. The thicknesses of the macular GCIPL and pRNFL were measured using Cirrus HD-OCT. The 5 and 1% thinning area index (TAI) was calculated as the proportion of abnormally thin sectors at the 5 and 1% probability level within the area corresponding to the affected VF. The 5 and 1% TAI were compared between the GCIPL and pRNFL measurements. The color-coded GCIPL deviation map showed a characteristic vertical thinning pattern of the GCIPL, which is also seen in the VF of patients with brain lesions. The 5 and 1% TAI were significantly higher in the GCIPL measurements than in the pRNFL measurements (all p < 0.01). Macular GCIPL analysis clearly visualized a characteristic topographic pattern of retinal ganglion cell (RGC) loss in patients with VF defects that respect the vertical meridian, unlike pRNFL measurements. Macular GCIPL measurements provide more valuable information than pRNFL measurements for detecting the loss of RGCs in patients with retrograde degeneration of the optic nerve fibers. PMID:25104464

  19. Retinal nerve fiber layer reflectometry must consider directional reflectance.

    PubMed

    Huang, Xiang-Run; Knighton, Robert W; Feuer, William J; Qiao, Jianzhong

    2016-01-01

    Recent studies reveal that measurements of retinal nerve fiber layer (RNFL) reflectance provide more sensitive detection of glaucomatous damage than RNFL thickness, but most do not consider directional reflectance of the RNFL, an important source of variability. This study quantitatively compared RNFL directional reflectance, represented by an angular spread function (ASF), measured at different scattering angles, different wavelengths and different distances from the optic nerve head (ONH) and for bundles with different thicknesses (T). An ASF was characterized by its amplitude (A) and width (W). Internal reflectance of a bundle was expressed as A/T. The study found that A varied significantly with scattering angle and wavelength and that A/T was different among bundles but constant along the same bundle, indicating that the internal structure of axons may vary among bundles but does not change with distance. This study also found that W was larger near the ONH and at longer wavelengths, but did not depend on scattering angle or T. Because a 4.3° change in incident angle can change reflected intensity by a factor of 2.7, accounting for directional reflectance should improve the accuracy and reproducibility of RNFL reflectance measurements. PMID:26819814

  20. Retinal nerve fiber layer reflectometry must consider directional reflectance

    PubMed Central

    Huang, Xiang-Run; Knighton, Robert W.; Feuer, William J.; Qiao, Jianzhong

    2015-01-01

    Recent studies reveal that measurements of retinal nerve fiber layer (RNFL) reflectance provide more sensitive detection of glaucomatous damage than RNFL thickness, but most do not consider directional reflectance of the RNFL, an important source of variability. This study quantitatively compared RNFL directional reflectance, represented by an angular spread function (ASF), measured at different scattering angles, different wavelengths and different distances from the optic nerve head (ONH) and for bundles with different thicknesses (T). An ASF was characterized by its amplitude (A) and width (W). Internal reflectance of a bundle was expressed as A/T. The study found that A varied significantly with scattering angle and wavelength and that A/T was different among bundles but constant along the same bundle, indicating that the internal structure of axons may vary among bundles but does not change with distance. This study also found that W was larger near the ONH and at longer wavelengths, but did not depend on scattering angle or T. Because a 4.3° change in incident angle can change reflected intensity by a factor of 2.7, accounting for directional reflectance should improve the accuracy and reproducibility of RNFL reflectance measurements. PMID:26819814

  1. Fibre-reinforced materials.

    PubMed

    Brown, D

    2000-11-01

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

  2. The anterior fibres of the levator ani muscle in man.

    PubMed Central

    Ayoub, S F

    1979-01-01

    The anatomy of the anterior portion of the levator ani muscle in studied in 26 adult human cadavers of both sexes. This portion of the muscle is found to consist of three layers of muscle fibres. The three layers are: 1. The pelvic layer. Its fibres (1) are attached to the capsule of the prostate or adventitia of the lateral wall of vagina, (2) intermingle with and supplement the longitudinal muscle layer of the anal canal, and (3) are continuous with the fibres of the opposite side behind the recto-anal junction. 2. The middle layer. The most anterior fibres are twisted on themselves to form the round free border of the muscle that bounds the levator hiatus. The majority of the muscle fibres of this layer proceed backwards to cover and blend with the deep part of the external anal shincter, partly joining the anococcygeal ligament. 3. The perineal layer. These fibres surround the superficial part of the external anal sphincter. A respectable bundle of muscles fibres unites with that of the opposite side in from of the lower part of the anal canal. Remaining fibres terminate in perianal skin or anococcygeal ligament. The role of the anterior portion of the levator ani in fixation and prevention of prolapse of the pelvic viscera is stressed. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 PMID:468708

  3. The Correlation of Retinal Nerve Fiber Layer Thickness With Blood Pressure in a Chinese Hypertensive Population

    PubMed Central

    Gangwani, Rita A.; Lee, Jacky W.Y.; Mo, H.Y.; Sum, Rita; Kwong, Alfred S.K.; Wang, Jenny H.L.; Tsui, Wendy W.S.; Chan, Jonathan C.H.; Lai, Jimmy S.M.

    2015-01-01

    Abstract To investigate the association between retinal nerve fiber layer (RNFL) thickness and blood pressure (BP) in subjects with systemic hypertension. Subjects with systemic hypertension on anti-hypertensive medications were screened by fundus photography and referred for glaucoma work-up if there was enlarged vertical cup-to-disc (VCDR) ratio ≥0.6, VCDR asymmetry ≥0.2, or optic disc hemorrhage. Workup included a complete ophthalmological examination, Humphrey visual field test, and RNFL thickness measurement by optical coherence tomography. The intraocular pressure (IOP) and RNFL thicknesses (global and quadrant) were averaged from both eyes and the means were correlated with: the systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) using Pearson correlation. Among 4000 screened hypertensive subjects, 133 were referred for glaucoma workup and 110 completed the workup. Of the 4000 screened subjects, 1.3% had glaucoma (0.9% had normal tension glaucoma [NTG], 0.2% had primary open angle glaucoma, and 0.2% had primary angle closure glaucoma), whereas 0.3% were NTG suspects. The SBP was negatively correlated with the mean superior RNFL thickness (P = 0.01). The DBP was negatively correlated with the mean global (P = 0.03), superior (P = 0.02), and nasal (P = 0.003) RNFL thickness. The MAP was negatively correlated with the mean global (P = 0.01), superior (P = 0.002), and nasal (P = 0.004) RNFL thickness while positively correlated with the mean IOP (P = 0.02). In medically treated hypertensive subjects, glaucoma was present in 1.3%, with NTG being most prevalent. MAP control may help with IOP lowering and RNFL preservation, although future prospective studies will be needed. PMID:26061324

  4. 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. PMID:25788541

  5. Polycystic ovary syndrome: aggressive or protective factor for the retina? Evaluation of macular thickness and retinal nerve fiber layers using high-definition optical coherence tomography.

    PubMed

    de Souza-Júnior, José Edvan; Garcia, Carlos Alexandre de Amorim; Soares, Elvira Maria Mafaldo; Maranhão, Técia Maria Oliveira; Lemos, Telma Maria Araújo Moura; Azevedo, George Dantas

    2015-01-01

    Objective. To compare macular thickness (MT) and retinal nerve fiber layers (RNFL) between women with polycystic ovary syndrome (PCOS) and healthy women. Materials and Methods. The study included 45 women with PCOS and 47 ovulatory women undergoing clinical-gynecological and ophthalmic evaluations, including measurement of MT, RNFL, and optic disc parameters using optical coherence tomography. Results. The superior RNFL around the optic nerve was significantly thicker in PCOS than in healthy volunteers (P = 0.036). After stratification according to insulin resistance, the temporal inner macula (TIM), the inferior inner macula (IIM), the nasal inner macula (NIM), and the nasal outer macula (NOM) were significantly thicker in PCOS group than in control group (P < 0.05). Both the presence of obesity associated with insulin resistance (P = 0.037) and glucose intolerance (P = 0.001) were associated with significant increase in the PC1 mean score, relative to MT. A significant increase in the PC2 mean score occurred when considering the presence of metabolic syndrome (P < 0.0001). There was a significant interaction between obesity and inflammation in a decreasing mean PC2 score relative to macular RNFL thickness (P = 0.034). Conclusion. Decreased macular RNFL thickness and increased total MT are associated with metabolic abnormalities, while increased RNFL thickness around the optic nerve is associated with hormonal changes inherent in PCOS. PMID:25763280

  6. Polycystic Ovary Syndrome: Aggressive or Protective Factor for the Retina? Evaluation of Macular Thickness and Retinal Nerve Fiber Layers Using High-Definition Optical Coherence Tomography

    PubMed Central

    de Souza-Júnior, José Edvan; Garcia, Carlos Alexandre de Amorim; Soares, Elvira Maria Mafaldo; Maranhão, Técia Maria Oliveira; Lemos, Telma Maria Araújo Moura; Azevedo, George Dantas

    2015-01-01

    Objective. To compare macular thickness (MT) and retinal nerve fiber layers (RNFL) between women with polycystic ovary syndrome (PCOS) and healthy women. Materials and Methods. The study included 45 women with PCOS and 47 ovulatory women undergoing clinical-gynecological and ophthalmic evaluations, including measurement of MT, RNFL, and optic disc parameters using optical coherence tomography. Results. The superior RNFL around the optic nerve was significantly thicker in PCOS than in healthy volunteers (P = 0.036). After stratification according to insulin resistance, the temporal inner macula (TIM), the inferior inner macula (IIM), the nasal inner macula (NIM), and the nasal outer macula (NOM) were significantly thicker in PCOS group than in control group (P < 0.05). Both the presence of obesity associated with insulin resistance (P = 0.037) and glucose intolerance (P = 0.001) were associated with significant increase in the PC1 mean score, relative to MT. A significant increase in the PC2 mean score occurred when considering the presence of metabolic syndrome (P < 0.0001). There was a significant interaction between obesity and inflammation in a decreasing mean PC2 score relative to macular RNFL thickness (P = 0.034). Conclusion. Decreased macular RNFL thickness and increased total MT are associated with metabolic abnormalities, while increased RNFL thickness around the optic nerve is associated with hormonal changes inherent in PCOS. PMID:25763280

  7. Polymer optical fibres: conventional and microstructured fibres

    NASA Astrophysics Data System (ADS)

    Argyros, Alexander; Leon-Saval, Sergio G.; Lwin, Richard; Provo, Richard; Murdoch, Stuart G.; Harvey, John D.; Anthony, Jessienta; Leonhardt, Rainer; Tuniz, Alessandro; Kuhlmey, Boris T.; Fleming, Simon C.

    2012-02-01

    Polymer optical fibres (POF) have historically focused on applications in data transmission over short distances, using highly multimode step-index or graded-index fibre designs. This paper will focus on a qualitatively different type of polymer fibres - microstructured polymer optical fibres (mPOF) - which allow a wider variety of fibre designs and optical properties to be achieved. Fibres with similar properties to conventional step- and graded-index POF can be made for data transmission applications, as well as single-mode fibres which can be used for grating inscription and gratingbased sensing. The use of microstructures can also be extended to longer wavelengths for the transmission of THz radiation, and both solid-core and hollow-core mPOF-based THz waveguides have been demonstrated. Finally, the development and extension of mPOF to form metal-dielectric structures for the manufacture of metamaterials using fibre-drawing methods will be discussed. Such drawn-metamaterials with electric and magnetic responses at THz frequencies have been demonstrated.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  9. Soft glass photonic crystal fibres and their applications

    NASA Astrophysics Data System (ADS)

    Buczyński, Ryszard; Klimczak, Mariusz; Pysz, Dariusz; Stepniewski, Grzegorz; Siwicki, Bartłomiej; Cimek, Jarosław; Kujawa, Ireneusz; Piechal, Bernard; Stepień, Ryszard

    2015-05-01

    Most of the research work related to photonic crystal fibres has to date been focused on silica based fibres. Only in the recent years has there been a fraction of research devoted to fibres based on soft glasses, since some of them offer interesting properties as significantly higher nonlinearity than silica glass and wide transparency in the infrared range. On the other hand, attenuation in those glasses is usually one or more orders of magnitude higher that in silica glass, which limits their application area due to limited length of the fibres, which can be practically used. We report on the development of single-mode photonic crystal fibres made of highly nonlinear lead-bismuth-gallate glass with a zero dispersion wavelength at 1460 nm and flat anomalous dispersion. A two-octave spanning supercontinuum in the range 700-3000 nm was generated in 2 cm of the fibre. In contrast to the silica glass, various oxide based soft glasses with large refractive index difference can jointly undergo multiple thermal processing steps without degradation. The use of two soft glasses gives additional degrees of freedom in the design of photonic crystal fibres. As a result, highly nonlinear fibres with unique dispersion characteristics can be obtained. Soft glass allow also development of fibres with complex subwavelength refractive index distribution inside core of the fibre. A highly birefringent fibre with anisotropic core composed of subwavelength glass layers ordered in a rectangular structure was developed and is demonstrated

  10. Relationship between Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography and Visual Field Severity Indices

    PubMed Central

    Kang, Eun Min; Hong, Samin; Kim, Chan Yun

    2015-01-01

    Purpose Though there are many reports regarding the structure-function relationship in glaucoma, they are too complicated to apply to the routine clinical setting. The aim of this study was to investigate the direct relationship between peripapillary retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and visual field (VF) severity indices computed by standard automated perimetry. Methods This cross-sectional comparative study included 104 glaucomatous patients and 59 healthy subjects. Peripapillary RNFL thickness was measured by spectral domain (SD) and time domain (TD) OCTs. Four glaucoma VF severity indices, including mean deviation (MD), pattern standard deviation (PSD), Collaborative Initial Glaucoma Treatment Study (CIGTS) VF score, and Advanced Glaucoma Intervention Study (AGIS) VF score, were calculated using standard automated perimetry. The Pearson's correlation coefficients (r) between the average and quadrants of peripapillary RNFL thicknesses and the four VF severity indices were calculated. Results In glaucomatous eyes, the r value between the average RNFL thickness measured by SD OCT and each VF severity index were 0.562, -0.514, -0.577, and -0.567 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Among each quadrant, the inferior RNFL thickness showed the largest r value; 0.587, -0.552, -0.613, and -0.598 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Measurements by TD OCT showed similar strengths of association with SD OCT. Conclusions Moderate correlation was identified between peripapillary RNFL thicknesses measured by SD/TD OCT and glaucoma VF severity indices. Among each quadrant, the inferior RNFL thickness showed the greatest association with glaucoma VF severity indices. There was no significant difference according to the type of VF severity index or the type of OCTs. PMID:26240511

  11. Rates of retinal nerve fiber layer thinning in glaucoma suspect eyes

    PubMed Central

    Miki, Atsuya; Medeiros, Felipe A.; Weinreb, Robert N.; Jain, Sonia; He, Feng; Sharpsten, Lucie; Khachatryan, Naira; Hammel, Na’ama; Liebmann, Jeffrey M.; Girkin, Christopher A.; Sample, Pamela A.; Zangwill, Linda M.

    2015-01-01

    Purpose To compare the rates of retinal nerve fiber layer (RNFL) loss in patients suspect of having glaucoma who developed visual field damage (VFD) to those who did not develop VFD, and to determine whether the rate of RNFL loss can be used to predict who will develop VFD.. Design Prospective observational cohort study Participants Glaucoma suspects, defined as having glaucomatous optic neuropathy or ocular hypertension (Intraocular pressure (IOP)>21 mmHg) without repeatable VFD at baseline from the Diagnostic Innovations in Glaucoma Study, and the African Descent and Glaucoma Evaluation Study. Methods Global and quadrant RNFL thickness (RNFLT) were measured with the Spectralis spectral-domain optical coherence tomography (SD-OCT). VFD was defined as having 3 consecutive abnormal visual fields. The rate of RNFL loss in eyes developing VFD was compared with eyes not developing VFD using multivariable linear mixed-effects models. A joint longitudinal survival model utilized the estimated RNFLT slope to predict the risk of developing VFD, while adjusting for potential confounding variables. Main Outcome Measures The rate of RNFL thinning and the probability of developing VFD. Results Four hundred and fifty-four eyes of 294 glaucoma suspects were included. The average number of SD-OCT examinations was 4.6 (range, 2–9) with median follow-up time of 2.2 (0.4–4.1) years. Forty eyes (8.8%) developed VFD. The estimated mean rate of global RNFL loss was significantly faster in eyes developing VFD compared with eyes that did not (−2.02μm/year vs. −0.82μm/year, P<0.001). The joint longitudinal survival model showed that each 1μm/year faster rate of global RNFL loss corresponded to a 2.05 times higher risk of developing VFD (Hazards Ratio (HR)=2.05, 95% Confidence Interval (CI): 1.14–3.71; p=0.017). Conclusions The rate of global RNFL loss was more than twice as fast in eyes developing VFD compared with eyes that did not develop them. Joint longitudinal survival model showed that a 1μm/year faster rate of RNFLT loss corresponded to a 2.05 times higher risk of developing VFD. These results suggest that measuring the rate of SD-OCT RNFL loss may be a useful tool to help identify patients who are at a high risk of developing visual field loss. PMID:24629619

  12. Size of the Optic Nerve Head and Its Relationship with the Thickness of the Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer in Patients with Primary Open Angle Glaucoma

    PubMed Central

    Enomoto, Nobuko; Anraku, Ayako; Ishida, Kyoko; Takeyama, Asuka; Yagi, Fumihiko; Tomita, Goji

    2015-01-01

    Purpose. To evaluate the relationships among the optic nerve head (ONH) area, macular ganglion cell complex (mGCC) thickness, circumpapillary retinal nerve fiber layer (cpRNFL) thickness, and visual field defects in patients with primary open angle glaucoma (POAG). Methods. This retrospective study included 90 eyes of 90 patients with POAG. The ONH area, rim area, mGCC thickness, and cpRNFL thickness were measured using optical coherence tomography. Mean deviation (MD) was measured using standard automated perimetry. The relationships among clinical factors including age, refraction, the ONH area, the rim area, the mGCC thickness, the cpRNFL thickness, and MD were evaluated using correlation coefficients and multiple regression analyses. Results. The significant correlation of the ONH area with refraction (r = 0.362, P < 0.001), the mGCC thickness (r = 0.225, P = 0.033), and the cpRNFL thickness (r = 0.253, P = 0.016) was found. Multiple regression analysis showed that the ONH area, rim area, and MD were selected as significant contributing factors to explain the mGCC thickness and cpRNFL thickness. No factor was selected to explain MD. Conclusions. The ONH area, in other words, the disc size itself may affect the mGCC thickness and cpRNFL thickness in POAG patients. PMID:26339503

  13. 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

  14. 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)

  15. New optical fibres for high-capacity optical communications.

    PubMed

    Richardson, D J

    2016-03-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing. PMID:26809569

  16. 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

  17. 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.

  18. Baseline Retinal Nerve Fiber Layer Thickness and Macular Volume Quantified by OCT in the North American Phase 3 Fingolimod Trial for Relapsing–Remitting Multiple Sclerosis

    PubMed Central

    Winges, Kimberly M.; Werner, John S.; Harvey, Danielle J.; Cello, Kimberly E.; Durbin, Mary K.; Balcer, Laura J.; Calabresi, Peter A.; Keltner, John L.

    2014-01-01

    Background Patients with multiple sclerosis (MS) demonstrate thinning of peripapillary retinal nerve fiber layer (RNFL) and decreased macular volume as measured by optical coherence tomography (OCT). To our knowledge, there are no previous reports from a large MS OCT database with strict quality control measures that quantitate RNFL and macula in patients with relapsing–remitting multiple sclerosis. Methods The University of California Davis OCT Reading Center gathered OCT data at baseline as part of the North American phase 3 trial of fingolimod (Gilenya). Average RNFL thickness (RNFLT) and macular volume (TMV) were measured using time domain OCT (TD-OCT). RNFL quadrants, clock hours, and macular subfields were included. With strict quality control and accounting for signal strength differences, scans were categorized as “reduced” or “not reduced” for each field, based on being less than 5th percentile for age-matched controls derived from the normative database in the scanner software. Patients were deemed “abnormal” if at least 1 eye had reduced values for a given parameter. Patients with abnormalities in corresponding RNFL and macular subfields were compared by cross-tabulation. Results The TD-OCT data were prospectively collected from 939 of the 1,083 trial patients, 712 of whom met all final quality and data inclusion criteria. Of the final cohort, 242 (34.0%) demonstrated reduced (less than 5th percentile) average RNFLT in at least 1 eye. One hundred seventy-eight (25.0%) patients had reduced TMV. One hundred twenty-eight (18.0%) demonstrated both reduced TMV and RNFLT in the same eye, whereas 42 (5.8%) had reduced TMV and RNFLT in both eyes. Of the 242 patients with reduced average RNFL thickness, 128 (52.9%) also had reduced TMV. Fifty patients had reduced TMV in the absence of reduced RNFLT in at least 1 eye, a cohort prevalence of 7.0%. Quadrant and subfield analysis showed a predominance of temporal and inferior RNFL thinning, with inferior macular thinning corresponding best to RNFL thinning. Conclusion RNFL and macular thinning/volume loss is common at baseline in relapsing–remitting multiple sclerosis, as measured by TD-OCT. When the RNFL is thin, the macular volume is reduced in more than half of the patients. There is a population of reduced TMV without any reduction in RNFLT. Documenting the prevalence and distribution of these structural abnormalities supports recent reports and suggests new retinal areas to probe for functional vision changes in MS. PMID:24051419

  19. Changes in retinal nerve fiber layer and optic disc algorithms by optical coherence tomography in glaucomatous Arab subjects

    PubMed Central

    Zeried, Ferial M; Osuagwu, Uchechukwu L

    2013-01-01

    Purpose To assess the difference in retinal nerve fiber layer (RNFL) and optic disc algorithms between glaucomatous and normal Arab subjects using optical coherence tomography (OCT). Methods RNFL thickness and optic disc parameters were obtained in 65 patients aged 50.1 ± 7.7 years. Percentage differences in all parameters were calculated and analyzed between groups. Results The mean RNFL thickness around the disc and at all quadrants was significantly thinner in glaucomatous eyes than in normal eyes (P < 0.01). The greatest decrease in RNFL thickness was observed at the inferior (39.5%) and superior (39.3%) quadrants and at 1 o’clock (43%) and 5 o’clock (40%) hour sectors. Significant differences were observed between glaucomatous and control eyes in all disc parameters (P < 0.005) assessed. The disc area, cup area, mean cup/disc ratio, and vertical and horizontal cup/disc ratios were significantly larger (P < 0.01), whereas the vertical integrated rim area, horizontal integrated rim width, and rim area were significantly smaller (P < 0.001) in glaucomatous eyes than in normal eyes. Conclusion Stratus OCT is still a valuable tool in the diagnosis of early glaucoma changes and, as such, its use should be encouraged in glaucoma clinics in Saudi Arabia. The best OCT parameters for detecting early glaucoma change were RNFL thickness in the inferior, superior, and 1 o’clock hour sector; the cup area; and the vertical integrated rim area of the optic disc. PMID:24109175

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  1. Fibre Flocculation in Papermaking

    NASA Astrophysics Data System (ADS)

    Kerekes, R. J.

    1998-11-01

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

  2. Pure chiral optical fibres.

    PubMed

    Poladian, L; Straton, M; Docherty, A; Argyros, A

    2011-01-17

    We investigate the properties of optical fibres made from chiral materials, in which a contrast in optical activity forms the waveguide, rather than a contrast in the refractive index; we refer to such structures as pure chiral fibres. We present a mathematical formulation for solving the modes of circularly symmetric examples of such fibres and examine the guidance and polarisation properties of pure chiral step-index, Bragg and photonic crystal fibre designs. Their behaviour is shown to differ for left- and right-hand circular polarisation, allowing circular polarisations to be isolated and/or guided by different mechanisms, as well as differing from equivalent non-chiral fibres. The strength of optical activity required in each case is quantified. PMID:21263635

  3. Fibre and enteral nutrition.

    PubMed Central

    Silk, D B

    1989-01-01

    The recent launch of a number of fibre enriched polymeric diet in the United States and Europe has stimulated considerable interest in the topic of fibre and enteral nutrition, and several commercial concerns appear to be under considerable pressures from their consumers to produce similar products. As a means of identifying areas of potential application of fibre to enteral nutrition some of the recent knowledge gained about the physical properties of dietary fibre and the processes involved in the intestinal assimilation of fibre has been reviewed. Two areas of interest are identifiable. The first relates to the bulking properties of fibre and the application of this to the regulation of bowel function in enterally fed patients. It is clear from the clinical studies that have been reviewed that there remains a paucity of controlled data, and a great deal more research is needed before widespread use of fibre supplemented diets can be supported. Perhaps of greater interest academically is the potentially beneficial effects that appear to be exerted by the VFA's, liberated as a consequence of colonic bacterial fermentation of fibre, on morphology and function of ileal and colonic mucosa. Although there are a number of potential applications of fibre supplemented enteral diets in this area, more research is required before any firm recommendations can be made about recommending their use. The one exception concerns patients with the nutritionally inadequate short bowel syndrome. There does seem to be sufficient experimental evidence to suggest that clinical studies should be commenced using a pectin supplemented predigested 'elemental' diet in these patients. Overall therefore, one is forced to conclude that the increasing interest and use of fibre supplemented enteral diets is being driven more by market than scientific forces. Nevertheless, the promotion of these diets has already provided a powerful stimulus to the scientific community, and it remains entirely possible that many of the potential applications of these diets will be realised in the near future. PMID:2539312

  4. 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

  5. Peripapillary retinal nerve fiber layer thickness in patients with iron deficiency anemia

    PubMed Central

    Cikmazkara, Ipek; Ugurlu, Seyda Karadeniz

    2016-01-01

    Purpose: To evaluate the effect of iron deficiency anemia (IDA) on peripapillary retinal nerve fiber layer (RNFL) thickness with optical coherence tomography (OCT). Materials and Methods: 102 female patients who had IDA (hemoglobin <12 g/dl, serum transferrin saturation <15%, serum iron <50 μg/dl, and serum ferritin <15 μg/dl) were enrolled in the study. Optic disc and RNFL parameters obtained by Cirrus high-definition OCT 4000 were compared with those of 49 age and sex-matched nonanemic individuals. The time between blood analysis and OCT measurements was 3.14 ± 5.6 (range, 0–28) days in the anemia group, and 3.5 ± 6.7 (range, 0–27) days in the control group (P = 0.76). Results: Average ages of 102 patients and 49 control subjects were 35.76 ± 10.112 (range, 18–66) years, and 36.08 ± 8.416 (range, 19–57) years (P = 0.850), respectively. The average RNFL thickness was 94.67 ± 9.380 in the anemia group, and 100.22 ± 9.12 in the control group (P = 0.001). Temporal, nasal, and lower quadrant average RNFL thicknesses of IDA group were thinner than the control group (P = 0.001, P = 0.013, P = 0.008). Upper quadrant RNFL thicknesses in IDA and control groups were similar. Correlation analysis revealed positive correlation between mean RNFL thickness and hemoglobin (r = 0.273), iron (r = 0.177), ferritin (r = 0.163), and transferrin saturations (r = 0.185), while a negative correlation was found between total iron binding capacity (r = −0.199) and mean RNFL thickness. Conclusions: Peripapillary RNFL thickness measured by OCT is thinner in adult female patients with IDA. It may have a significant influence on the management of many disorders such as glaucoma and neuro-ophthalmological diseases. PMID:27146929

  6. Retinal nerve fiber layer thickness in glaucomatous Nepalese eyes and its relation with visual field sensitivity

    PubMed Central

    Khanal, Safal; Thapa, Madhu; Racette, Lyne; Johnson, Richard; Davey, Pinakin Gunvant; Joshi, Mahesh Raj; Shrestha, Gauri Shankar

    2014-01-01

    Background To evaluate peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous Nepalese eyes using spectral domain optical coherence tomography (SD-OCT) and study its relationship with visual field sensitivity. Methods A total of 120 eyes comprising primary open angle glaucoma (POAG), glaucoma suspects (GS), normal tension glaucoma (NTG) and healthy subjects (n = 30 cases in each group) underwent a complete ophthalmic examination, including optic nerve head (ONH) evaluation and standard automated perimetry (SAP). RNFL thickness measurements around the optic disk were taken with circular spectral domain optical coherence tomography (SD-OCT) scans. Analysis of variance (ANOVA) was used for comparison of RNFL parameters among various study groups. The relationship of RNFL parameters with visual field (VF) global indices was evaluated with regression analysis. Results The mean pRNFL thickness was significantly less in the POAG (64.30 ± 14.45 μm, p < 0.01), NTG (85.43 ± 9.79 μm, p < 0.001) and GS (102.0 ± 9.37 μm, p < 0.001) groups than in the healthy group (109.8 ± 8.32 μm). The RNFL was significantly thinner across all quadrants in all study group pairs (p < 0.05) except for normal vs. GS (only superior and inferior quadrant, significant). Linear regression plots with RNFL thickness as a predictor of MD and LV demonstrated a strong and statistically significant degree of determination in the POAG group (R2 = 0.203 and 0.175, p = 0.013 and 0.021). Conclusion The RNFL thickness measurements with SD-OCT are lower in glaucomatous eyes as compared to age-matched GS and normal eyes in the Nepalese population. A high resolution SD-OCT could aid significantly in the early diagnosis of glaucoma in Nepal. PMID:25323643

  7. Investigation of the optimal collagen fibre orientation in human iliac arteries

    PubMed Central

    Qi, Nan; Gao, Hao; Ogden, Raymond W.; Hill, Nicholas A.; Holzapfel, Gerhard A.; Han, Hai-Chao; Luo, Xiaoyu

    2016-01-01

    The distribution of collagen fibres plays a significant role in the mechanical behaviour of artery walls. Experimental data show that in most artery wall layers there are two (or more) in-plane symmetrically disposed families of fibres. However, a recent investigation revealed that some artery wall layers have only one preferred fibre direction, notably in the medial layer of human common iliac arteries. This paper aims to provide a possible explanation for this intriguing phenomenon. An invariant-based constitutive model is utilized to characterize the mechanical behaviour of tissues. We then use three different hypotheses to determine the ‘optimal fibre angle’ in an iliac artery model. All three hypotheses lead to the same result that the optimal fibre angle in the medial layer of the iliac artery is close to the circumferential direction. The axial pre-stretch, in particular, is found to play an essential role in determining the optimal fibre angle. PMID:26195342

  8. Investigation of the optimal collagen fibre orientation in human iliac arteries.

    PubMed

    Qi, Nan; Gao, Hao; Ogden, Raymond W; Hill, Nicholas A; Holzapfel, Gerhard A; Han, Hai-Chao; Luo, Xiaoyu

    2015-12-01

    The distribution of collagen fibres plays a significant role in the mechanical behaviour of artery walls. Experimental data show that in most artery wall layers there are two (or more) in-plane symmetrically disposed families of fibres. However, a recent investigation revealed that some artery wall layers have only one preferred fibre direction, notably in the medial layer of human common iliac arteries. This paper aims to provide a possible explanation for this intriguing phenomenon. An invariant-based constitutive model is utilized to characterize the mechanical behaviour of tissues. We then use three different hypotheses to determine the 'optimal fibre angle' in an iliac artery model. All three hypotheses lead to the same result that the optimal fibre angle in the medial layer of the iliac artery is close to the circumferential direction. The axial pre-stretch, in particular, is found to play an essential role in determining the optimal fibre angle. PMID:26195342

  9. New generation of optical fibres

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  10. Measuring residual stresses in metallic components manufactured with fibre Bragg gratings embedded by selective laser melting

    NASA Astrophysics Data System (ADS)

    Havermann, Dirk; Mathew, Jinesh; MacPherson, William N.; Hand, Duncan P.; Maier, Robert R. J.

    2015-09-01

    Metal clad single mode optical fibres containing Fibre Bragg Gratings are embedded in stainless steel components using bespoke laser based Selective Laser Melting technology (SLM). Significant residual stresses can be created in SLM manufactured components through the strong thermal gradients during the build process. We demonstrate the ability to monitor these internal stresses through embedded optical fibres with FBGs on a layer to layer basis, confirming estimates from models for residual stresses in additive manufactured components.

  11. Optical coherence tomography assessed retinal nerve fiber layer thickness in patients with Alzheimer's disease: a meta-analysis

    PubMed Central

    He, Xue-Fei; Liu, Yi-Ting; Peng, Cheng; Zhang, Fan; Zhuang, Shi; Zhang, Jin-Song

    2012-01-01

    AIM To investigate the difference of retinal nerve fiber layer (RNFL) thickness between Alzheimer's disease patients and normal people, so as to provide clue for the early diagnosis of Alzheimer's disease. METHODS The articles on the association of RNFL thickness and Alzheimer's disease were retrieved by searching international and national databases. The qualified articles were assessed by meta analysis with Stata11.0 software. The results were pooled using weighted mean difference (WMD) with a corresponding 95% confidence interval (CI). RESULTS Totally 7 studies enrolled 324 eyes were included in the meta-analysis. The results of meta analysis showed that in AD patients, there was a significant average RNFL thickness reduction compared with the control group [WMD=-17.561, 95%CI: (-23.971, -11.151)]. There were significant differences in superior, inferior, nasal and temporal RNFL thickness between the two groups. WMD with a 95%CI were [-18.829, 95%CI:(-25.915, -11.743); P<0.05], [-25.775, 95%CI:(-34.304, -17.247); P<0.05], [-16.877, 95%CI: (-29.141, -4.613); P<0.001] and [-14.565, 95%CI:(-28.002, -1.128); P<0.001] respectively. Begg's test and Egger's test did not show significant difference, funnel plot was basically symmetrical, indicating that there was no publication bias existed. CONCLUSION There are significant differences in the RNFL thickness in all quadrants between the two groups. RNFL thickness is reduced in AD patients compared with the control group. PMID:22773997

  12. Macular Ganglion Cell/Inner Plexiform Layer Measurements with Spectral Domain Optical Coherence Tomography for Detection of Early Glaucoma and Comparison to Retinal Nerve Fiber Layer Measurements

    PubMed Central

    Nouri-Mahdavi, Kouros; Nowroozizadeh, Sara; Nassiri, Nariman; Cirineo, Nila; Knipping, Shane; Giaconi, JoAnn; Caprioli, Joseph

    2013-01-01

    Purpose To evaluate the performance of ganglion cell/inner plexiform layer (GC/IPL) measurements with spectral-domain optical coherence tomography (Cirrus HD-OCT) for detection of early glaucoma and to compare results to retinal nerve fiber layer (RNFL) measurements. Design Cross-sectional prospective diagnostic study. Methods Fifty-nine glaucoma eyes (47 subjects) (mean deviation >–6.0dB) and 91 normal eyes (52 subjects) were enrolled. Patients underwent biometry and peripapillary and macular OCT imaging. Performance of the GC/IPL and RNFL algorithms was evaluated with area under receiver operating characteristic curves (AUC), likelihood ratios, and sensitivities/specificities adjusting for covariates. Combination of best parameters was explored. Results Average (SD) mean deviation in the glaucoma group was –2.5 (1.9) dB. On multivariate analyses, age (p<0.001) and axial length (p=0.03) predicted GC/IPL measurements in normal subjects. No significant correlation was found between average or regional GC/IPL thickness and respective outer retina (OR) thickness measurements (p>0.05). Average RNFL thickness performed better than average GC/IPL measurements for detection of glaucoma (AUC=0.964 vs. 0.937; p=0.04). The best regional measures from each algorithm (inferior quadrant RNFL vs. minimum GC/IPL) had comparable performances (p=0.78). Entering GCIPL/OR ratio into prediction models did not enhance performance of the GC/IPL measures. Combining the best parameters from each algorithm improved detection of glaucoma (p=0.04). Conclusions Regional GC/IPL measures derived from Cirrus HD-OCT performed as well as regional RNFL outcomes for detection of early glaucoma. Using GCIPL/OR ratio did not enhance the performance of GC/IPL parameters. Combining the best measures from the two algorithms improved detection of glaucoma. PMID:24075422

  13. Respiratory monitoring using fibre long period grating sensors

    NASA Astrophysics Data System (ADS)

    Allsop, T.; Reeves, R.; Webb, D. J.; Bennion, I.; Earthrowl, T.; Jones, B.; Miller, M.

    2005-08-01

    We demonstrate the use of a series of in-line fibre long period grating curvature sensors on a garment, used to monitor the thoracic and abdominal volumetric tidal movements of a human subject. These results are used to obtain volumetric tidal changes of the human torso showing reasonable agreement with a spirometer used simultaneously to record the volume at the mouth during breathing. The curvature sensors are based upon long period gratings written in a progressive three layered fibre that are insensitive to refractive index changes. The sensor platform consists of the long period grating laid upon a carbon fibre ribbon, which is encapsulated in a low temperature curing silicone rubber.

  14. Is Retinal Nerve Fiber Layer Thickness Change Related to Headache Lateralization in Migraine?

    PubMed Central

    Demirci, Seden; Tok, Levent; Tok, Ozlem; Demirci, Serpil; Kutluhan, Süleyman

    2016-01-01

    Purpose To evaluate retinal nerve fiber layer (RNFL) thickness in migraine patients with unilateral headache. Methods A total of 58 patients diagnosed with migraine headache consistently occurring on the same side and 58 age- and sex-matched healthy subjects were evaluated in this cross-sectional study. RNFL thickness was measured using spectral-domain optical coherence tomography, and the side with the headache was com-pared with the contralateral side as well as with the results of healthy subjects. Results The mean patient age was 33.05 ± 8.83 years, and that of the healthy subjects was 31.44 ± 8.64 years (p = 0.32). The mean duration of disease was 10.29 ± 9.03 years. The average and nasal RNFL thicknesses were significantly thinner on the side of headache and on the contralateral side compared to control eyes (p < 0.05, for all). Thinning was higher on the side of the headache compared to the contralateral side; however, this difference was not statistically significant. Conclusions The RNFL thicknesses were thinner on the side of the headache compared to the contralateral side in the migraine patients with unilateral headache, but this difference was not statistically significant. PMID:27051262

  15. Bruch’s Membrane Opening-Minimum Rim Width and Retinal Nerve Fibre Layer Thickness in a Normal White Population. A Multi-centre Study

    PubMed Central

    Chauhan, Balwantray C.; Danthurebandara, Vishva M.; Sharpe, Glen P.; Demirel, Shaban; Girkin, Christopher A.; Mardin, Christian Y.; Scheuerle, Alexander F.; Burgoyne, Claude F.

    2015-01-01

    Objective Conventional optic disc margin-based neuroretinal rim measurements lack a solid anatomical and geometrical basis. An optical coherence tomography (OCT) index, Bruch’s membrane opening minimum rim width (BMO-MRW), addresses these deficiencies and has higher diagnostic accuracy for glaucoma. We characterized BMO-MRW and peripapillary retinal nerve fiber layer thickness (RNFLT) in a normal population. Design Multi-centred cross-sectional study. Participants Normal White subjects. Methods Approximately equal number of subjects in each decade group (20–90 years) was enrolled in 5 centers. Subjects had normal ocular and visual field examinations. We obtained OCT images of the optic nerve head (24 radial scans) and peripapillary retina (1 circular scan). The angle between the fovea and BMO center (FoBMO), relative to the horizontal axis of the image frame, was first determined and all scans were acquired and analyzed relative to this eye-specific FoBMO axis. Variation of BMO-MRW and RNFLT was analyzed with respect to age, sector and BMO shape. Main Outcome Measures Age-related decline and between-subject variability in BMO-MRW and RNFLT. Results There were 246 eyes of 246 subjects with a median age of 52.9 (range, 19.8 to 87.3) years. The median FoBMO angle was −6.7° (range, 2.5° to −17.5°). BMO was predominantly vertically oval with a median area of 1.74 mm2 (range, 1.05 to 3.40 mm2). Neither FoBMO angle nor BMO area was associated with age or axial length. Both global mean BMO-MRW and RNFLT declined with age at a rate of −1.34 µm/y and −0.21 µm/y, equivalent to 4.0% and 2.1% loss per decade of life, respectively. Sectorally, the most rapid decrease occurred inferiorly and the least temporally, however, the age association was always stronger with BMO-MRW than with RNFLT. There was a modest relationship between mean global BMO-MRW and RNFLT (r = 0.35), while sectorally the relationship ranged from moderate (r = 0.45, inferotemporal) to non-existent (r = 0.01, temporal). Conclusions There was significant age-related loss of BMO-MRW in healthy subjects and notable differences between BMO-MRW and RNFLT in their relationship with age and between each other. Adjusting BMO-MRW and RNFLT for age and sector is important in ensuring optimal diagnostics for glaucoma. PMID:26198806

  16. CONDUCTION IN NERVE FIBRES

    PubMed Central

    Blair, H. A.

    1934-01-01

    Data by E. A. Blair and Erlanger on the voltage-capacity curves and the nerve impulse velocities of each of several fibres in the same nerve trunk are related to Rashevsky's equation for the velocity of transmission in nerve. The results lend support to Rashevsky's analysis. Other empirical relations between the velocity and the parameters of the excitation equations indicate the correctness of the hypothesis that the action current is the primary factor in transmission, which process is carried on by the electrical excitation of successive regions of the nerve fibre by means of its action current according to the ordinary laws of electrical excitation. PMID:19872822

  17. Details of Glaucomatous Damage Are Better Seen on OCT En Face Images Than on OCT Retinal Nerve Fiber Layer Thickness Maps

    PubMed Central

    Hood, Donald C.; Fortune, Brad; Mavrommatis, Maria A.; Reynaud, Juan; Ramachandran, Rithambara; Ritch, Robert; Rosen, Richard B.; Muhammad, Hassan; Dubra, Alfredo; Chui, Toco Y. P.

    2015-01-01

    Purpose High-resolution images of glaucomatous damage to the retinal nerve fiber layer (RNFL) were obtained with an adaptive optics-scanning light ophthalmoscope (AO-SLO) and used as a basis for comparisons between en face slab images and thickness maps derived from optical coherence tomography (OCT) scans. Methods Wide-field (9 × 12 mm) cube scans were obtained with swept-source OCT (DRI-OCT) from six eyes of six patients. All eyes had a deep defect near fixation as seen on a 10-2 visual field test. Optical coherence tomography en face images, based on the average reflectance intensity, were generated (ATL 3D-Suite) from 52-μm slabs just below the vitreal border of the inner limiting membrane. The RNFL thickness maps were generated from the same OCT data. Both were compared with the AO-SLO peripapillary images that were previously obtained. Results On AO-SLO images, three eyes showed small regions of preserved and/or missing RNFL bundles within the affected region. Details in these regions were seen on the OCT en face images but not on the RNFL thickness maps. In addition, in the healthier hemi-retinas of two eyes, there were darker, arcuate-shaped regions on en face images that corresponded to abnormalities seen on AO-SLO. These were not seen on RNFL thickness maps. Conclusions Details of local glaucomatous damage, missing or easily overlooked on traditional OCT RNFL thickness analysis used in clinical OCT reports, were seen on OCT en face images based on the average reflectance intensity. While more work is needed, it is likely that en face slab imaging has a role in the clinical management of glaucoma. PMID:26426403

  18. Effects of vitamin D on retinal nerve fiber layer in vitamin D deficient patients with optic neuritis: Preliminary findings of a randomized, placebo-controlled trial

    PubMed Central

    Salari, Mehri; Janghorbani, Mohsen; Etemadifar, Masoud; Dehghani, Alireza; Razmjoo, Hassan; Naderian, Gholamali

    2015-01-01

    Background: There is accumulating evidence for a possible protective role of vitamin D in the development and disease course of multiple sclerosis. Whether vitamin D is also effective in treating patients with optic neuritis (ON) is not known. The aim of this study was to evaluate the effect of oral vitamin D on the thickness of retinal nerve fiber layer (RNFL) in vitamin D deficient patients with ON by optical coherence tomography. Materials and Methods: A Phase II placebo-controlled randomized clinical trial conducted between July 2011 and November 2012 included 52 patients with confirmed unilateral ON aged 15-38 years and low serum 25-hydroxyvitamin D levels. The main outcome measures were changes in thickness of RNFL and macula 6 months after treatment. Patients were randomly allocated to receive 6 months of treatment with adding either 50,000 IU/week vitamin D or placebo. Results: In the 27 patients treated with vitamin D, the mean (standard deviation [SD]) thickness of RNFL decreased from 111.3 (18.9) μm at baseline to 91.4 (13.3) at the end of study period (P < 0.001). Correspondingly, in the 25 patients treated with placebo, the mean (SD) thickness of RNFL decreased from 113.7 (21.5) μm at baseline to 96.1 (12.3) at the end of study period (P < 0.01). In both groups, the mean thickness of the macula did not changed (P > 0.05). Average thickness of RNFL at the end of trial did not differ between groups. Conclusion: Adding vitamin D to routine disease therapy had no significant effect on the thickness of RNFL or macula in patients with ON. This trial is registered on www.clinicaltrials.gov (ID NCT01465893). PMID:26109993

  19. Effect of suction on macular thickness and retinal nerve fiber layer thickness during LASIK used femtosecond laser and Moria M2 microkeratome

    PubMed Central

    Zhang, Jing; Zhou, Yue-Hua

    2015-01-01

    AIM To compare the effect of suction on the macular thickness and retinal nerve fiber layer (RNFL) thickness during laser in situ keratomileusis (LASIK) used Ziemer FEMTO LDV femtosecond laser (Ziemer group) and Moria M2 automated microkeratome (Moria group) for flap creation. METHODS Fourier-domain optical coherence tomography (FD-OCT) was used to measure macular thickness, ganglion cell complex thickness and (RNFL) thickness of 204 eyes of 102 patients with the Ziemer femtosecond laser (102 eyes) and the Moria M2 microkeratome (102 eyes) before surgery and 30min; 1, 3d; 1wk; 1, 3mo; 1y after surgery. RESULTS The average foveal thickness and parafoveal retinal thickness 30min after the surgery were statistically more than that before surgery (Ziemer P<0.001, P=0.003 and Moria P=0.001, P=0.006) and the effect was less in the Ziemer group than that in the Moria group (P all<0.05). The ganglion cell complex thickness was not significantly changed in both groups (P all>0.05). The RNFL thickness was statistically less 30min after surgery in both groups (P=0.014, P<0.001), but the influence was less in Ziemer group than that in Moria group (P=0.038). However, the RNFL thickness had recovered to the preoperative level only 1d after surgery. CONCLUSION The suction of femtosecond laser and mechanical microkeratome led to the increase in macular central fovea thickness and the decrease in RNFL thickness values at the early stage after LASIK. The effect of suction on macular and the RNFL thicknesses in Ziemer group is smaller than that in Moria group. PMID:26309879

  20. A study of black fleece garments: Can fleece fibres be recognized and how variable are they?

    PubMed

    Lunstroot, K; Ziernicki, D; Vanden Driessche, T

    2016-05-01

    Fleece garments are very popular nowadays. This is reflected in forensic fibre cases where fleece garments and especially black colored items are frequently encountered. For this study 201 black and dark colored fleece garments were collected from co-workers, friends, family and shops. The constituent fibres were analyzed with common methods used in forensic fibre analyses: microscopy (bright field, polarized light, fluorescence); microspectrophotometry (MSP-visible range); infrared spectroscopy (FTIR) and comparison microscopy. Almost all fleece fabrics were made of 100% polyester fibres. The most abundant fibre type involved polygonal polyester fibres. The appearance of typical fleece-features was explored. It was found that fleece fibres would shed easily, resulting in many long polyester fibres. In many cases these fleece fibres showed typical "mushroom-ends" and in some cases a few thicker fibres that originated from the inner "base layer" of the fleece fabric were also found providing a second fibre type that can be lost from fleece fabrics. Most of the black fleece fabrics could be discriminated with the analytical techniques, the discriminating power DP was found to be 0.9985. This was despite the fact that most of the absorption spectra showed similar features in the visible range. They were denominated as TYPE 1 MSP-spectra and displayed 2 absorption bands at 450nm and 600nm. PMID:27162014

  1. SpaceFibre Discussion

    NASA Technical Reports Server (NTRS)

    Rakow, Glenn

    2007-01-01

    This viewgraph presentation discusses the future use of SpaceFibre, a high speed optical extension to the SpaceWire, for NASA and DOD missions. NASA, and US industries would like to work with the European developers currently working on this standard.

  2. Perimetric and retinal nerve fiber layer findings in patients with Parkinson’s disease

    PubMed Central

    2012-01-01

    Background Visual dysfunction is common in Parkinson’s disease (PD). It remains, however, unknown whether it is related to structural alterations of the retina. The aim of this study is to compare visual field (VF) findings and circumpapillary retinal nerve fiber layer (RNFL) thickness in a series of PD patients and normal controls, in order to assess possible retinal anatomical changes and/or functional damage associated with PD. Methods PD patients and controls were recruited and underwent VF testing with static automated perimetry and RNFL examination with optical coherence tomography (OCT). Cognitive performance using Mini Mental State Examination (MMSE), PD staging using modified Hoehn and Yahr (H-Y) scale and duration of the disease was recorded in PD patients. Results One randomly selected eye from each of 24 patients and 24 age-matched controls was included. OCT RNFL thickness analysis revealed no difference in the inferior, superior, nasal or temporal sectors between the groups. The average peripapillary RNFL was also similar in the two groups. However, perimetric indices of generalized sensitivity loss (mean deviation) and localized scotomas (pattern standard deviation) were worse in patients with PD compared to controls (p < 0.01). 73% of eyes of PD patients had glaucomatous-like asymmetrical hemifield defects with abnormal Glaucoma Hemifield Test and various combinations of arcuate defects (n = 12), nasal steps (n = 11) and paracentral scotomas (n = 16). Bilateral defects were found in 14 patients (58%). No correlation was found between VF indices and MMSE or H-Y scores. Conclusion PD patients may demonstrate glaucomatous-like perimetric defects even in the absence of decreased RNFL thickness. PMID:23031247

  3. Multifunctional conducting fibres with electrically controlled release of ciprofloxacin.

    PubMed

    Esrafilzadeh, Dorna; Razal, Joselito M; Moulton, Simon E; Stewart, Elise M; Wallace, Gordon G

    2013-08-10

    We hereby present a new method of producing coaxial conducting polymer fibres loaded with an antibiotic drug that can then be subsequently released (or sustained) in response to electrical stimulation. The method involves wet-spinning of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) fibre, which served as the inner core to the electropolymerised outer shell layer of polypyrrole (Ppy). Ciprofloxacin hydrochloride (Cipro) was selected as the model drug and as the dopant in the Ppy synthesis. The release of Cipro in phosphate buffered saline (PBS) from the fibres was controlled by switching the redox state of Ppy.Cipro layer. Released Cipro under passive and stimulated conditions were tested against Gram positive (Streptococcus pyogenes) and Gram negative (Escherichia coli) bacteria. Significant inhibition of bacterial growth was observed against both strains tested. These results confirm that Cipro retains antibacterial properties during fibre fabrication and electrochemically controlled release. In vitro cytotoxicity testing utilising the neural B35 cell line confirmed the cytocompatibility of the drug loaded conducting fibres. Electrical conductivity, cytocompatibility and tuning release profile from this flexible fibre can lead to promising bionic applications such as neuroprosthetics and localised drug delivery. PMID:23379995

  4. Association between retinal nerve fiber layer thickness and magnetic resonance imaging findings and intelligence in patients with multiple sclerosis

    PubMed Central

    Ashtari, Fereshteh; Emami, Parisa; Akbari, Mojtaba

    2015-01-01

    Background: Multiple Sclerosis (MS) is a neurological disease in which demyelination and axonal loss leads to progressive disability. Cognition impairment is among the most common complication. Studying axonal loss in the retina is a new marker for MS. The main goal of our study is to search for correlations between magnetic resonance imaging (MRI) findings and the retinal nerve fiber layer (RNFL) thickness at the macula and head of the optic nerve and Wechsler Adult Intelligence Scale-Revised (WAIS-R) Scores that assess multiple domains of intelligence, and to explore the relationship between changes in the RNFL thickness with intellectual and cognitive dysfunction. Materials and Methods: A prospective cross-sectional study was conducted at the University Hospital of Kashani, Isfahan, Iran, from September to December 2013. All patients were assessed with a full-scale intelligence quotient (IQ) on the WAIS-R. An optical coherence tomography study and brain MRI were performed in the same week for all the patients. Statistical analysis was conducted by using a bivariate correlation, by utilizing SPSS 20.0. A P value ≤ 0.05 was the threshold of statistical significance. Results: Examination of a 100 patients showed a significant correlation between the average RNFL thickness of the macula and the verbal IQ (P value = 0.01) and full IQ (P value = 0.01). There was a significant correlation between brain atrophy and verbal IQ. Conclusion: The RNFL loss was correlated with verbal IQ and full IQ. PMID:26682201

  5. Visible light optical coherence tomography for in vivo imaging the spectral contrasts of the retinal nerve fiber layer

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyang; Hu, Jianming; Knighton, Robert W.; Huang, Xiang-Run; Puliafito, Carmen A.; Jiao, Shuliang

    2012-01-01

    The ultimate goal of the study is to provide an imaging tool to detect the earliest signs of glaucoma before clinically visible damage occurs to the retinal nerve fiber layer (RNFL). Studies have shown that the optical reflectance of the damaged RNFL at short wavelength (<560nm) is reduced much more than that at long wavelength, which provides spectral contrasts for imaging the earliest damage to the RNFL. To image the spectral contrasts we built a dual-band spectral-domain optical coherence tomography (SD-OCT) with centered wavelength of 415nm (VIS) and 808nm (NIR), respectively. The light at the two bands was provided by the fundamental and frequency-doubled outputs of a broadband Ti: Sapphire laser. The depth resolutions of the VIS and NIR OCT systems are 12.2μm and 4.7μm in the air. The system was applied to imaging the rat retina in vivo. Significantly different appearances between the OCT cross sectional images at the two bands are observed. The experimental results showed that the dual-band OCT system is feasible for imaging the spectral contrasts of the RNFL.

  6. 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.

  7. Optic Disc and Nerve Fiber Layer Imaging To Detect Glaucoma

    PubMed Central

    Badalà, Federico; Nouri-Mahdavi, Kouros; Raoof, Duna A.; Leeprechanon, Narakorn; Law, Simon K.; Caprioli, Joseph

    2007-01-01

    Purpose To compare optic disc and retinal nerve fiber layer (RNFL) imaging methods to discriminate eyes with early glaucoma from normal eyes. Design Retrospective, cross-sectional study. Methods Setting: Tertiary care academic glaucoma center. Ninety-two eyes of 92 subjects (46 with early perimetric open-angle glaucoma and 46 controls) were studied. Diagnostic performance of optical coherence tomography (StratusOCT), scanning laser polarimetry (GDx-VCC), confocal laser ophthalmoscopy (Heidelberg Retinal Tomograph III), and qualitative assessment of stereoscopic optic disc photographs were compared. Outcome measures were areas under receiver operator characteristic curves (AUC) and sensitivities at fixed specificities. Classification and Regression Trees (CART) analysis was used to evaluate combinations of quantitative parameters. Results The average (±SD) visual field mean deviation for glaucomatous eyes was −4.0±2.5 dB. Parameters with largest AUCs (±SE) were: average RNFL thickness for StratusOCT (0.96±0.02), nerve fiber indicator for GDx-VCC (0.92±0.03), FSM discriminant function for HRT III (0.91±0.03), and 0.97±0.02 for disc photograph evaluation. At 95% specificity, sensitivity of disc photograph evaluation (90%) was greater than GDx-VCC (p=0.05) and HRT III (p=0.002), but not significantly different than that of StratusOCT (p>0.05). Combination of StratusOCT average RNFL thickness and HRT III cup/disc area with CART produced a sensitivity of 91% and specificity of 96% Conclusions StratusOCT, GDx-VCC, and HRT III performed as well as, but not better than, qualitative evaluation of optic disc stereophotographs for detection of early perimetric glaucoma. The combination of StratusOCT average RNFL thickness and HRT III cup/disc area ratio provided a high diagnostic precision. PMID:17868631

  8. Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography

    PubMed Central

    Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K. W.; Yoshimura, Nagahisa

    2016-01-01

    Purpose To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. Methods The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Results Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. Conclusions The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction. PMID:26814541

  9. 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

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

    PubMed Central

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

    2014-01-01

    The collagenous structure of the knee menisci is integral to the mechanical integrity of the tissue and the knee joint. The tie-fibre structure of the tissue has largely been neglected, despite previous studies demonstrating its correlation with radial stiffness. This study has evaluated the structure of the tie-fibres of bovine menisci using 2D and 3D microscopy techniques. Standard collagen and proteoglycan (PG) staining and 2D light microscopy techniques were conducted. For the first time, the collagenous structure of the menisci was evaluated using 3D, second harmonic generation (SHG) microscopy. This technique facilitated the imaging of collagen structure in thick sections (50–100 μm). Imaging identified that tie-fibres of the menisci arborize from the outer margin of the meniscus toward the inner tip. This arborization is associated with the structural arrangement of the circumferential fibres. SHG microscopy has definitively demonstrated the 3D organization of tie-fibres in both sheets and bundles. The hierarchy of the structure is related to the organization of circumferential fascicles. Large tie-fibre sheets bifurcate into smaller sheets to surround circumferential fascicles of decreasing size. The tie-fibres emanate from the lamellar layer that appears to surround the entire meniscus. At the tibial and femoral surfaces these tie-fibre sheets branch perpendicularly into the meniscal body. The relationship between tie-fibres and blood vessels in the menisci was also observed in this study. Tie-fibre sheets surround the blood vessels and an associated PG-rich region. This subunit of the menisci has not previously been described. The size of tie-fibre sheets surrounding the vessels appeared to be associated with the size of blood vessel. These structural findings have implications in understanding the mechanics of the menisci. Further, refinement of the complex structure of the tie-fibres is important in understanding the consequences of injury and disease in the menisci. The framework of meniscus architecture also defines benchmarks for the development of tissue-engineered replacements in the future. PMID:24617800

  11. An investigation into the persistence of textile fibres on buried carcasses.

    PubMed

    DeBattista, Roslyn; Tidy, Helen; Thompson, Tim J U; Robertson, Peter

    2014-07-01

    A significant amount of research has been carried out on fibres to aid the forensic scientist in determining the significance of these when found on a victim or suspect. This work has focused on open-air environments, and as such no research has been undertaken to examine the persistence of fibres on bodies in the burial environment. Wool and cotton fibres, known to fluoresce under ultraviolet (UV) light, were transferred onto the skin of four porcine (Sus scrofa) carcasses (two carcasses per fibre type). The number of fibres transferred was recorded from images taken under UV light. The remains were subsequently placed in four burial sites and left interred for 14 days. After this period the carcasses were excavated and lightly brushed down to remove the soil layer that had adhered to the skin. Once again photography under UV light was used to record the number of fibres which persisted on the skin. Results showed that after 14 days, wool and cotton fibres remain on the surface of the buried carcasses. In no circumstance was there a total loss of fibres suggesting that in such scenarios, the likelihood of finding fibres is high but the initial number of fibres transferred would be strongly diminished. This has important implications for both the excavation protocol for buried remains and the subsequent analysis for physical evidence. PMID:25002046

  12. Dissolution behaviour of model basalt fibres studied by surface analysis methods

    NASA Astrophysics Data System (ADS)

    Frster, T.; Scheffler, C.; Mder, E.; Heinrich, G.; Jesson, D. A.; Watts, J. F.

    2014-12-01

    New concepts of surface modifications aimed at the enhancement of alkali resistance of basalt fibres require research work on chemical composition of interacting surface layers as well as knowledge about fundamental processes of basaltic glass dissolution. Therefore, two model basalt fibres manufactured out of subalkaline and alkaline rock material were leached in NaOH solution at a temperature of 80 C for up to 11 days. The formation of a corrosion shell was observed in both cases and was analyzed by SEM/EDX. The model fibres out of subalkaline rocks show dissolution kinetic, which is two-staged, whereas the more alkaline fibre reflects a linear one. The complex composition of basalt fibre is detected by EDX and XPS. The surface of basalt fibres is rich in Si and Al. XPS high resolution spectra provide information on oxidation state of iron.

  13. Reduced retinal nerve fiber layer and macular thickness in patients with multiple sclerosis with no history of optic neuritis identified by the use of spectral domain high-definition optical coherence tomography.

    PubMed

    Fjeldstad, Cecilie; Bemben, Michael; Pardo, Gabriel

    2011-11-01

    Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system (CNS), with both inflammatory and degenerative components. The visual system is frequently involved, often in the form of visual loss from optic neuritis (ON). Retinal nerve fiber layer (RNFL) loss has been demonstrated in individuals with MS, not only in those with previous ON but also in absence of historical evidence of previous acute inflammation/demyelination of the optic nerve. Peripapillary RNFL measurements of all quadrants, central macular thickness, and average macular thickness were performed in 32 eyes of healthy volunteers and 60 eyes of individuals with a diagnosis of relapsing remitting MS using high definition spectral domain optical coherence tomography (HD-OCT). Both the Macular Cube 512 × 128 scan and RNFL measurement by the Optic Disc Cube 200 × 200 protocol were performed on all eyes. Eyes of individuals with MS with no previous ON had significantly decreased overall RNFL thickness (89.1 μm) compared to controls (98.0 μm) (p < 0.05). MS mainly affected the temporal quadrant (56.6 μm versus [vs.] 67.8 μm) (p < 0.05), and inferior quadrant (117.9 μm vs. 132.1 μm) (p < 0.05), respectively. Also, the patients with MS demonstrated significantly decreased average macular thickness (280 μm) compared to the control group (287 μm) (p < 0.05). A significant correlation between RNFL and average macular thickness was also found in eyes of patients with MS (r = 0.69, p < 0.01). HD-OCT is a quick, inexpensive and promising tool to detect subclinical changes in RNFL and macular thickness in individuals with MS. Longitudinal studies should be encouraged to examine disease progression over time in individuals with MS. PMID:21917458

  14. Compressive failure of fibre composites

    NASA Astrophysics Data System (ADS)

    Budiansky, B.; Fleck, N. A.

    1993-01-01

    A REVIEW OF experimental data and elementary theoretical formulas for compressive failure of polymer matrix fibre composites indicates that the dominant failure mode is by plastic kinking. Initial local fibre misalignment plays a central role in the plastic kinking process. Theoretical analyses and numerical results for compressive kinking are presented, encompassing effects of strain-hardening, kink inclination, and applied shear stress. The assumption of rigid fibres is assessed critically, and the legitimacy of its use for polymer matrix composites is established.

  15. FIBRE OPTICS. OPTICAL FIBRES: A 1.65-μm fibre Raman amplifier

    NASA Astrophysics Data System (ADS)

    Kurkov, Andrei S.; Paramonov, Vladimir M.; Egorova, O. N.; Medvedkov, O. I.; Dianov, Evgenii M.; Zalevskii, I. D.; Goncharov, S. E.

    2002-08-01

    A fibre Raman amplifier operating at a wavelength of 1.65-μm is fabricated. A two-stage phosphosilicate fibre Raman converter of 1.53-μm radiation for pumping the Raman amplifier is designed and tested. The amplifier pumped by a phosphosilicate fibre Raman converter can operate with a maximum of the gain band ranging from 1.6 to 1.7 μm. A fibre with a core of a high (25%) molecular content of GeO2 serves as an active medium for the Raman amplifier. The gain obtained for different powers of the input signal is 22 — 25 dB. Our calculations show that the use of a standard telecommunication fibre (with a lower content of GeO2) allows one to increase the gain in this scheme by reducing fibre splicing losses.

  16. Normative spectral domain optical coherence tomography data on macular and retinal nerve fiber layer thickness in Indians

    PubMed Central

    Appukuttan, Bindu; Giridhar, Anantharaman; Gopalakrishnan, Mahesh; Sivaprasad, Sobha

    2014-01-01

    Aim: To provide the normative data of macular and retinal nerve fiber layer (RNFL) thickness in Indians using spectral domain OCT (Spectralis OCT, Heidelberg Engineering, Germany) and to evaluate the effects of age, gender, and refraction on these parameters. Design: Observational, cross-sectional study. Materials and Methods: The eyes of 105 healthy patients aged between 20-75 years, with no ocular disease and best corrected visual acuity of 20/20, were scanned using standard scanning protocols by a single examiner. Exclusion criteria included glaucoma, retinal diseases, diabetes, history of prior intraocular surgery or laser treatment. The mean macular and RNFL thickness were recorded, and the effects of age, gender, and refraction on these parameters were evaluated. This data was compared with published literature on Caucasians to assess the ethnic variations of these parameters. Results: The normal central foveal thickness in healthy Indian eyes measured using Spectralis OCT was 260.1 ± 18.19 μm. The nasal inner quadrant showed maximum retinal thickness (338.88 ± 18.17 μm). The mean RNFL thickness was 101.43 ± 8.63 μm with maximum thickness in the inferior quadrant. The central foveal thickness showed a gender-based difference (P = 0.005) but did not correlate significantly with age (P = 0.134), whereas the parafoveal, perifoveal thickness, macular volume, and RNFL thickness showed significant negative correlation with age. Conclusions: Our study provides the normative database for Indians on Spectralis OCT. It also suggests that age should be considered while interpreting the macular thickness and RNFL, whereas gender should also be given consideration in central foveal thickness. PMID:24008793

  17. Population-Based Evaluation of Retinal Nerve Fiber Layer, Retinal Ganglion Cell Layer, and Inner Plexiform Layer as a Diagnostic Tool For Glaucoma

    PubMed Central

    Springelkamp, Henriët; Lee, Kyungmoo; Wolfs, Roger C. W.; Buitendijk, Gabriëlle H. S.; Ramdas, Wishal D.; Hofman, Albert; Vingerling, Johannes R.; Klaver, Caroline C. W.; Abràmoff, Michael D.; Jansonius, Nomdo M.

    2014-01-01

    Purpose. We determined the glaucoma screening performance of regional optical coherence tomography (OCT) layer thickness measurements in the peripapillary and macular region, in a population-based setting. Methods. Subjects (n = 1224) in the Rotterdam Study underwent visual field testing (Humphrey Field Analyzer) and OCT of the macula and optic nerve head (Topcon 3-D OCT-1000). We determined the mean thicknesses of the retinal nerve fiber layer (RNFL), retinal ganglion cell layer (RGCL), and inner plexiform layer for regions-of-interest; thus, defining a series of OCT parameters, using the Iowa Reference Algorithms. Reference standard was the presence of glaucomatous visual field loss (GVFL); controls were subjects without GVFL, an intraocular pressure (IOP) of 21 mm Hg or less, and no positive family history for glaucoma. We calculated the area under the receiver operating characteristics curve (AUCs) and the sensitivity at 97.5% specificity for each parameter. Results. After excluding 23 subjects with an IOP > 21 mm Hg and 73 subjects with a positive family history for glaucoma, there were 1087 controls and 41 glaucoma cases. Mean RGCL thickness in the inferior half of the macular region showed the highest AUC (0.85; 95% confidence interval [CI] 0.77–0.92) and sensitivity (53.7%; 95% CI, 38.7–68.0%). The mean thickness of the peripapillary RNFL had an AUC of 0.77 (95% CI, 0.69–0.85) and a sensitivity of 24.4% (95% CI, 13.7–39.5%). Conclusions. Macular RGCL loss is at least as common as peripapillary RNFL abnormalities in population-based glaucoma cases. Screening for glaucoma using OCT-derived regional thickness identifies approximately half of those cases of glaucoma as diagnosed by perimetry. PMID:25414193

  18. Galactans and cellulose in flax fibres: putative contributions to the tensile strength.

    PubMed

    Girault, R; Bert, F; Rihouey, C; Jauneau, A; Morvan, C; Jarvis, M

    1997-08-01

    The proton spin-spin relaxation time, T2, measured from solid-state NMR, indicates a greater rigidity for cellulose than for the adhesive matrix between the microfibrils of flax ultimate fibres. Cytochemical and biochemical analyses allow the identification of: (1) EDTA-soluble RG I-polymers in the primary walls and cell junctions of fibres; (2) long 1 --> 4-beta-D-galactan chains between primary and secondary wall layers; and (3) arabinogalactan-proteins throughout the secondary walls. These polymers in the adhesive matrix between microfibrils and/or cellulose layers ensure that cracks propagate along the matrix rather than across the fibres and play an important role in allowing flax fibres to approach the tensile strength of advanced synthetic fibres like carbon and Kevlar. PMID:9283034

  19. The Effect of Pattern Scan Laser Photocoagulation on Peripapillary Retinal Nerve Fiber Layer Thickness and Optic Nerve Morphology in Diabetic Retinopathy

    PubMed Central

    Lee, Dong Eik; Lee, Ju Hyang; Lim, Han Woong; Kang, Min Ho; Cho, Hee Yoon

    2014-01-01

    Purpose To evaluate the effect of pattern scan laser (PASCAL) photocoagulation on peripapillary retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), and optic nerve morphology in patients with diabetic retinopathy. Methods Subjects included 35 eyes for the PASCAL group and 49 eyes for a control group. Peripapillary RNFL thickness, cup-disc area ratio and CMT were measured before PASCAL photocoagulation and at 2 and 6 months after PASCAL photocoagulation in the PASCAL or control groups. Results The average RNFL thickness had increased by 0.84 µm two months after and decreased by 0.4 µm six months after PASCAL photocoagulation compared to baseline, but these changes were not significant (p = 0.83, 0.39). The cup-disc area ratio was unchanged after PASCAL photocoagulation. CMT increased by 18.11 µm (p = 0.048) at two months compared to baseline thickness, and partially recovered to 11.82 µm (p = 0.11) at six months in the PASCAL group. Conclusions PASCAL photocoagulation may not cause significant change in the peripapillary RNFL thickness, CMT, and optic nerve morphology in patients with diabetic retinopathy. PMID:25276083

  20. The long-term effect of intravitreal ranibizumab on retinal nerve fiber layer thickness in exudative age-related macular degeneration.

    PubMed

    Parlak, Melih; Oner, F Hakan; Saatci, A Osman

    2015-08-01

    The aim of this study was to evaluate the long-term effect of intravitreal ranibizumab on the retinal nerve fiber layer (RNFL) in exudative age-related macular degeneration (AMD). Patients with treatment naive neovascular AMD in one eye were enrolled into the study. Following 3 monthly intravitreal ranibizumab injections, the patients were evaluated according to disease activity and re-injections were performed according to "treat and extend" protocol. During the follow-up, peripapillary nerve fiber layer thickness measurements were compared with normal fellow eyes. Forty-four eyes of 11 women and 11 men with the mean age of 66.3 8.8 years (50-80) were enrolled into the study. All patients had completed at least 12 months of follow-up time. Patients received an average of 4.7 (3-11 injections) intravitreal injections. At baseline, no significant difference was observed between two groups for RNFL thickness, which was assessed as quadrants (p = 0.250-0.944) and globally (p = 0.814). In each group, there was a significant RNFL thinning (p = 0.009 and 0.022) after the third month, whereas no significant difference was observed between treated and untreated eyes. Patients were also classified according to the number of injections, and RNFL thickness showed no difference between eyes treated with less or more than five intravitreal injections (p = 0.757-0.973). Although there was no statistically significant difference in RNFL thickness between study and control eyes during 12 months of follow-up, a significant thinning was recorded in both groups compared with baseline values. Cross-sectional images with higher resolutions and precise segmentation opportunities are needed to investigate the hypothesis "VEGF neutralization and inhibition of cell maintenance" in detail. PMID:25059401

  1. Optical coherence tomography versus visual evoked potential in multiple sclerosis patients

    PubMed Central

    Fatehi, Farzad; Mehr, Lida Kiani; Dehghani, Alireza

    2012-01-01

    Background Optical coherence tomography (OCT) is a non-invasive instrument, which can be used to estimate the thickness of the retinal nerve fibre layer (RNFL) and provides an indirect measurement of axonal destruction in multiple sclerosis (MS). The main aim of this study was to find out any correlations between P100 latency in visual evoked potential (VEP) and RNFL thickness. Methods The patients with the definite history of optic neuritis regardless of the diagnosis of MS were included. The eyes with the history of blurred vision and increased VEP latency (> 115 milliseconds) were considered as cases and the eyes with normal latency were regarded as controls. RNFL thickness was compared between two groups of cases and controls. In addition, the correlation between VEP P100 latency and RNFL thickness in four quadrants of superior, nasal, inferior and temporal fields was estimated by spearman correlation coefficient. RNFL thickness between the patients with history of clinically isolated syndrome (CIS) was also compared to other two subgroups of RRMS and SPMS. Results There was significant negative correlation between VEP P100 latency and RNFL. In all four quadrants, with increasing VEP latency, RNFL thickness decreased. Furthermore, there was significant correlation between P100 latencies and mean RNFL thickness [Pearson correlation coefficient = -0.527, P < 0.001; RNFL (mean) = (-0.44 ± 0.087) × P100 + (153.6 ± 10.94)]. Comparing RNFL thickness between three groups of CIS, RRMS, and SPSM, no significant difference was detected in RNFL thickness (P > 0.05). Power analysis demonstrated that RNFL average had the highest area under curve. Conclusion OCT does have good correlations with P100 latency, indicating retinal non-myelinated axonal involvement in early stages in addition to the myelinated axonal involvement. However, it cannot be used as the sole test in evaluating visual pathway in optic neuritis and complementary tests as VEPs are recommended. PMID:24250852

  2. Retinal nerve fiber layer thickness map

    NASA Astrophysics Data System (ADS)

    Mujat, Mircea; Chan, Raymond C.; Cense, Barry; Park, Hyle; Joo, Chulmin; Chen, Teresa C.; de Boer, Johannes F.

    2006-02-01

    Spectral-Domain Optical Coherence Tomography (SDOCT) allows for in-vivo video-rate investigation of biomedical tissue depth structure with the purpose of non-invasive optical diagnostics. In ophthalmic applications, it has been suggested that Optical Coherence Tomography (OCT) can be used for diagnosis of glaucoma by measuring the thickness of the Retinal Nerve Fiber Layer (RNLF). We present here an automated method for determining the RNFL thickness map from a 3-D dataset. Boundary detection has been studied since the early days of computer vision and image processing, and different approaches have been proposed. The procedure described here is based on edge detection using a deformable spline (snake) algorithm. As the snake seeks to minimize its overall energy, its shape will converge on the image contour, the boundaries of the nerve fiber layer. In general, the snake is not allowed to travel too much, and therefore, proper initialization is required. The snake parameters, elasticity, rigidity, viscosity, and external force weight are set to allow the snake to follow the boundary for a large number of retinal topographies. The RNFL thickness map is combined with an integrated reflectance map of the retina and retinal cross-sectional images (OCT movie), to provide the ophthalmologist with a familiar image for interpreting the OCT data. The video-rate capabilities of our SDOCT system allow for mapping the true retinal topography since the motion artifacts are significantly reduced as compared to slower time-domain systems.

  3. Birefringence measurement of the retinal nerve fiber layer by swept source polarization sensitive optical coherence tomography

    PubMed Central

    Elmaanaoui, Badr; Wang, Bingqing; Dwelle, Jordan C.; McElroy, Austin B.; Liu, Shuang S.; Rylander, Henry G.; Milner, Thomas E.

    2011-01-01

    A Swept Source Polarization-Sensitive Optical Coherence Tomography (SS-PS-OCT) instrument has been designed, constructed, and verified to provide high sensitivity depth-resolved birefringence and phase retardation measurements of the retinal nerve fiber layer. The swept-source laser had a center wavelength of 1059 nm, a full-width-half-max spectral bandwidth of 58 nm and an A-line scan rate of 34 KHz. Power incident on the cornea was 440 µW and measured axial resolution was 17 µm in air. A multiple polarization state nonlinear fitting algorithm was used to measure retinal birefringence with low uncertainty. Maps of RNFL phase retardation in a subject measured with SS-PS-OCT compare well with those generated using a commercial scanning laser polarimetry instrument. Peak-to-valley variation of RNFL birefringence given here is less than values previously reported at 840nm. PMID:21643283

  4. Random distributed feedback fibre lasers

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors-random distributed feedback fibre laser-was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (˜0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the generation of a stationary near-Gaussian beam with a narrow spectrum. A random distributed feedback fibre laser has efficiency and performance that are comparable to and even exceed those of similar conventional fibre lasers. The key features of the generated radiation of random distributed feedback fibre lasers include: a stationary narrow-band continuous modeless spectrum that is free of mode competition, nonlinear power broadening, and an output beam with a Gaussian profile in the fundamental transverse mode (generated both in single mode and multi-mode fibres). This review presents the current status of research in the field of random fibre lasers and shows their potential and perspectives. We start with an introductory overview of conventional distributed feedback lasers and traditional random lasers to set the stage for discussion of random fibre lasers. We then present a theoretical analysis and experimental studies of various random fibre laser configurations, including widely tunable, multi-wavelength, narrow-band generation, and random fibre lasers operating in different spectral bands in the 1-1.6 μm range. Then we discuss existing and future applications of random fibre lasers, including telecommunication and distributed long reach sensor systems. A theoretical description of random lasers is very challenging and is strongly linked with the theory of disordered systems and kinetic theory. We outline two key models governing the generation of random fibre lasers: the average power balance model and the nonlinear Schrödinger equation based model. Recently invented random distributed feedback fibre lasers represent a new and exciting field of research that brings together such diverse areas of science as laser physics, the theory of disordered systems, fibre optics and nonlinear science. Stable random generation in optical fibre opens up new possibilities for research on wave transport and localization in disordered media. We hope that this review will provide background information for research in various fields and will stimulate cross-disciplinary collaborations on random fibre lasers.

  5. 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)

  6. The Association Between Macular Thickness and Peripapillary Retinal Nerve Fiber Layer Thickness in Chinese Children

    PubMed Central

    Lee, Jacky W.Y.; Yau, Gordon S.K.; Woo, Tiffany T.Y.; Lai, Jimmy S.M.

    2015-01-01

    Abstract To investigate the association between macular thickness and peripapillary retinal nerve fiber layer (RNFL) thickness in Chinese children. This cross-sectional study recruited consecutive cases of healthy pediatric subjects aged 4 to 18 from Caritas Medical Centre in Hong Kong Special Administrative Region, China, from 2013 to 2014. Subjects with only eye, ocular tumors, congenital glaucoma, congenital cataract, congenital nystagmus, microphthalmos, optic nerve or retinal disease, active ocular infections, corneal scars, and severe visual impairment of any cause were excluded. Peripapillary RNFL thickness and macular thickness at 1-mm-diameter fovea center (C1), 3-mm-diameter temporal quadrant (T3), and 3-mm- diameter nasal quadrant (N3) were measured with optical coherence tomography. Best-corrected visual acuity, axial length, and cycloplegic refraction were also recorded. Spearman correlation was used to analyze the association between T3, C1, and N3 with each of the following: average and quadrant RNFL thickness, axial length, and spherical equivalent. In 179 subjects, the mean age was 7.9 ± 3.6 years. There were 90 male and 89 female subjects, all of Chinese ethnicity. The mean spherical equivalent was −0.1 ± 3.1 D and mean axial length was 22.9 ± 1.4 mm. There were significant and positive correlations of the average (T3: r = 0.20, P = 0.04; N3: r = 0.2, P = 0.005), superior (T3: r = 0.20, P = 0.03; N3: r = 0.2, P = 0.03), and inferior (T3: r = 0.20, P = 0.02; N3: r = 0.2, P = 0.01) peripapillary RNFL thicknesses with the T3 and N3 macular thicknesses but not C1. The nasal peripapillary RNFL thickness was also positively correlated with T3 (r = 0.20, P = 0.01). There were no significant associations between the macular thickness (T3, C1, N3) with neither the spherical equivalent (P > 0.2) nor the axial length (P > 0.3). The macular thickness was positive correlated with the peripapillary RNFL thickness in a population of healthy Chinese children. PMID:25715254

  7. Filament winding of SiC{sub fibre}/Si{sub 3}N{sub 4} composites - process and control of fibre distribution

    SciTech Connect

    Kristoffersson, A.; Laarz, E.; Carlsson, R.; Lundberg, R.

    1995-12-01

    Filament winding of a model system of SiC{sub fibre}Si{sub 3}N{sub 4} has been studied with regard to the microstructure. Processing parameters such as speed, fibre roving tension and spacing, together with slurry properties have been varied. Fibre rovings were completely impregnated in the immersion step but voids formed in the winding step. Fewer voids formed for the water-based slurries compared with slurries with petroleum spirit. Layered structures were formed when a low winding speed was used as the surface dried before the next roving was applied. This type of inhomogeneity can be quantified using image analysis.

  8. 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)

  9. Fibre in nutrition.

    PubMed

    Southgate, D A

    1975-01-01

    The physical properties and the chemical variety of the substances which make up the plant cell wall are inadequately described by any one term such as "fibre". It would seem that an understanding of the role of the unavailable carbohydrates and lignin in the diet in the functioning of the gastro-intestinal tract and on possible pathological process must be based on a better knowledge of the chemical and physical properties of these substances as they occur in foods than is at present available. It is suggested that this knowledge can come from a synthesis of the findings of the plant anatomists, plant biochemists and structural organic chemists and the application of this synthesis to studies in man. PMID:237503

  10. Ultrasonic assembly of anisotropic short fibre reinforced composites.

    PubMed

    Scholz, M-S; Drinkwater, B W; Trask, R S

    2014-04-01

    We report the successful manufacture of short fibre reinforced polymer composites via the process of ultrasonic assembly. An ultrasonic device is developed allowing the manufacture of thin layers of anisotropic composite material. Strands of unidirectional reinforcement are, in response to the acoustic radiation force, shown to form inside various matrix media. The technique proves suitable for both photo-initiator and temperature controlled polymerisation mechanisms. A series of glass fibre reinforced composite samples constructed in this way are subjected to tensile loading and the stress-strain response is characterised. Structural anisotropy is clearly demonstrated, together with a 43% difference in failure stress between principal directions. The average stiffnesses of samples strained along the direction of fibre reinforcement and transversely across it were 17.66±0.63MPa and 16.36±0.48MPa, respectively. PMID:24360815

  11. Multilayered Glass Fibre-reinforced Composites In Rotational Moulding

    SciTech Connect

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

    2011-05-04

    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.

  12. Comparison of the Abilities of SD-OCT and SS-OCT in Evaluating the Thickness of the Macular Inner Retinal Layer for Glaucoma Diagnosis

    PubMed Central

    Lee, Kyoung Min; Lee, Eun Ji; Kim, Tae-Woo; Kim, Hyunjoong

    2016-01-01

    Purpose To compare the abilities of spectral-domain optical coherence tomography (OCT) (SD-OCT; Spectralis, Heidelberg Engineering) and swept-source OCT (SS-OCT; DRI-OCT1 Atlantis system, Topcon) for analyzing the macular inner retinal layers in diagnosing glaucoma. Methods The study included 60 patients with primary open-angle glaucoma (POAG) and 60 healthy control subjects. Macular cube area was scanned using SD-OCT and SS-OCT on the same day to assess the thicknesses of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer plus inner plexiform layer (GCIPL), and total retinal layer in nine subfields defined by the Early Treatment Diabetic Retinopathy Study (ETDRS). The abilities of the parameters to discriminate between the POAG and control groups were assessed using areas under the receiver operating characteristic curves (AUCs). Results Glaucoma-associated mRNFL and GCIPL thinning was more common in the outer zones than inner zones for both SD-OCT and SS-OCT. The mRNFL and GCIPL measurements showed distinct pattern differences between SD-OCT and SS-OCT in each ETDRS subfield. Although the glaucoma-diagnosis ability was comparable between SD-OCT and SS-OCT for most of the parameters, AUC was significantly larger for SD-OCT measurements of the GCIPL thickness in the outer temporal zones (p = 0.003) and of the mRNFL thickness in the outer nasal zones (p = 0.001), with the former having the largest AUC for discriminating POAG from healthy eyes (AUC = 0.894). Conclusion Spectralis SD-OCT and DRI SS-OCT have similar glaucoma-diagnosis abilities based on macular inner layer thickness analysis. However, Spectralis SD-OCT was potentially superior to DRI SS-OCT in detecting GCIPL thinning in the outer temporal zone, where the glaucomatous damage predominantly occurs. PMID:26812064

  13. Effect of Signal Intensity on Measurement of Ganglion Cell Complex and Retinal Nerve Fiber Layer Scans in Fourier-Domain Optical Coherence Tomography

    PubMed Central

    Zhang, Xinbo; Iverson, Shawn M.; Tan, Ou; Huang, David

    2015-01-01

    Purpose We determined the effect of Fourier-domain optical coherence tomography (OCT) signal strength index (SSI) and cropping on retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) scan repeatability and measurement thickness. Methods Eyes were enrolled in the longitudinal Advanced Imaging for Glaucoma Study. At each visit, three repeat scans from the optic nerve head and macular protocols were obtained. Each measurement was associated with an SSI value from 0 to 100. Measurements with similar SSI scores were grouped to calculate repeatability defined as pooled standard deviation. Within-visit analysis was used to determine how measured thickness changed in relation to change in SSI level. Results The study included 1130 eyes of 569 patients. Cropped images yielded significantly worse repeatability and they were excluded from subsequent analyses. The within-visit repeatability for RNFL and GCC measurements were significantly better with higher signal strength, and optimal cutoffs were SSI ≥ 37 and ≥ 44, respectively. The coefficient of variation was <1.8% for RNFL scans with SSI ≥ 37 and < 2% for GCC with SSI ≥ 44. For scans above the cutoff SSI, higher SSI's were correlated with thicker RNFL among normal (slope = 0.056 μm/SSI unit, P < 0.001) eyes and glaucoma suspect and perimetric glaucoma (GSPPG) eyes (slope = 0.060 μm/SSI unit, P < 0.001), but not for perimetric glaucoma (PG) eyes. No significant correlation was found for GCC. Conclusion Repeatability of RNFL and GCC thickness measurements may be improved by excluding images with cropped anatomic features and weak signal strength below recommended SSI cutoffs. Translational Relevance Measurement precision and image quality of inner eye structure by advanced imaging modality are important for clinical diagnosis and tracking of glaucoma disease. PMID:26448900

  14. Mechanical properties of SiC long fibre reinforced copper

    NASA Astrophysics Data System (ADS)

    Brendel, A.; Paffenholz, V.; Köck, Th.; Bolt, H.

    2009-04-01

    SiC fibre reinforced copper is a potential novel heat sink material for the divertor of future fusion reactors to reinforce the zone between plasma facing material (W) and heat sink material (CuCrZr). The metal matrix composite (MMC) should be able to withstand heat loads up to 15 MW/m 2 at operating temperatures of up to 550 °C. SCS6 fibres were coated by magnetron sputtering with a titanium interlayer and the copper matrix was deposited by electroplating. The composite was consolidated by hot-isostatic pressing. The average ultimate tensile strength of composite samples with 20% fibre reinforcement is 640 MPa and for the Young's modulus 162 GPa was determined. The Young's modulus decreases with increasing temperature and reaches 113 GPa at 550 °C. Fracture area analysis after tensile tests show the failure of the SCS 6 fibres at the interface between the two outer carbon layers. Titanium as interlayer led to an improved bonding between the outer carbon coating of the SiC fibres and the copper matrix.

  15. 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 the fibre prestressed composites were a linear, increasing function of the prestressing level. Furthermore, a new method was introduced to measure the shrinkage of the polymeric resins. By the use of this method, the shrinkage of the epoxy resin was measured for the three curing temperatures, previously used to fabricate the samples. The tests were carried out on the un-reinforced polymer. In the next step, some experiments were arranged to investigate the contribution of the resin shrinkage to the formation of the residual stresses in the reinforced polymer. To achieve this goal, a bi-layer composite-neat polymer bar was made. The residual strain of the polymer was calculated by the measurement of the deflection of the bar. Comparison of the residual strain of the polymer in the bi-layer sample with the shrinkage of the polymer in the un-reinforced sample revealed that only 3.3% of the shrinkage of the resin contributes to form the residual stresses in the bi-layer sample. The stress free temperature of the bi-layer sample, the temperature at which the deflection of the sample disappeared, was determined by re-heating the sample and measuring the deflection of the sample at the same time. This temperature was the point below which the stresses were formed in the composite. The stress free temperature was found to be much lower than the curing temperature which usually was taken as stress free temperature.

  16. Fabrication of high-quality SNOM probes by pre-treating the fibres before chemical etching.

    PubMed

    Yang, Jing; Zhang, Jiasen; Li, Zhi; Gong, Qihuang

    2007-10-01

    A new method to fabricate high-quality fibre probes for scanning near-field optical microscopes by pre-treating the fibre before chemical etching was proposed and implemented. In the pre-treating process, the diameter of the fibre is reduced to a range of 7 -20 mum by etching one end of the fibre in the HF solution and a taper angle is formed simultaneously. Then the tapered part of the fibre is coated with a thick layer of plastic film and etched in the HF solution again. High-quality probes are obtained with an apex diameter as low as approximately 20 nm and a large cone angle. PMID:17910696

  17. Ganglion Cell Layer–Inner Plexiform Layer Thickness and Vision Loss in Young Children With Optic Pathway Gliomas

    PubMed Central

    Gu, Sherry; Glaug, Natalie; Cnaan, Avital; Packer, Roger J.; Avery, Robert A.

    2014-01-01

    Purpose. To determine if measures of macular ganglion cell layer–inner plexiform layer (GCL-IPL) thickness can discriminate between children with and without vision loss (visual acuity or field) from their optic pathway glioma (OPG) using spectral-domain optical coherence tomography (SD-OCT). Methods. Children with OPGs (sporadic or secondary to neurofibromatosis type 1) enrolled in a prospective study of SD-OCT were included if they were cooperative for vision testing and macular SD-OCT images were acquired. Manual segmentation of the macular GCL-IPL and macular retinal nerve fiber layer (RNFL) was performed using elliptical annuli with diameters of 1.5, 3.0, and 4.5 mm. Logistic regression assessed the ability of GCL-IPL and RNFL thickness measures (micrometers) to differentiate between the normal and abnormal vision groups. Results. Forty-seven study eyes (normal vision = 31, abnormal vision = 16) from 26 children with OPGs were included. Median age was 5.3 years (range, 2.5–12.8). Thickness of all GCL-IPL and RNFL quadrants differed between the normal and abnormal vision groups (P < 0.01). All GCL-IPL measures demonstrated excellent discrimination between groups (area under the curve [AUC] > 0.90 for all diameters). Using the lower fifth percentile threshold, the number of abnormal GCL-IPL inner macula (3.0 mm) quadrants achieved the highest AUC (0.989) and was greater than the macula RNFL AUCs (P < 0.05). Conclusions. Decreased GCL-IPL thickness (layer thickness could be used as a surrogate marker of vision in children with OPGs. PMID:24519429

  18. Electrical percolation of fibre mixtures

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  19. Sex-specific differences in retinal nerve fiber layer thinning after acute optic neuritis

    PubMed Central

    Hodge, William; Pan, Y. Irene; Burton, Jodie M.; Freedman, Mark S.; Stys, Peter K.; Trufyn, Jessie; Kardon, Randy

    2012-01-01

    Objective: The primary objective of this study was to explore the potential influence of gender on recovery from optic neuritis (ON) by determining whether differences in retinal nerve fiber layer (RNFL) thickness can be detected between men and women 6 months after an ON event. Methods: In this prospective cohort study, 39 men and 105 women with acute ON underwent repeat visual and optical coherence tomography (OCT) testing. The main outcome measures were change in RNFL measurements for male and female patients 6 months after ON. Results: Men were older (mean age = 39 years) than women (35 years) (p = 0.05) in this study, and more men (62%) than women (41%) had a diagnosis of relapsing-remitting multiple sclerosis (MS) (p = 0.02). Because age and MS subtype were 2 significant covariates, both variables were controlled for in multiple regression analyses. Other covariates controlled for in the multivariate regression included disease duration (years), use of disease-modifying therapy (yes/no), and use of high-dose corticosteroids for acute ON (yes/no). After 6 months, mean RNFL values were lower in men (74 ?m) than women (91 ?m) (p < 0.001). Men showed more apparent change in RNFL thickness in their ON eyes from baseline to 6 months after ON than women (p = 0.003). Conclusions: There may be differences in recovery between men and women after ON, which can be difficult to detect with conventional visual testing. Our findings raise interesting questions about the potential influence of gender in MS, which may be explored in future studies. PMID:23077012

  20. Reproducibility of Circumpapillary Retinal Nerve Fiber Layer Measurements Using Handheld Optical Coherence Tomography in Sedated Children

    PubMed Central

    Avery, Robert A.; Cnaan, Avital; Schuman, Joel S.; Chen, Chieh-Li; Glaug, Natalie C.; Packer, Roger J.; Quinn, Graham E.; Ishikawa, Hiroshi

    2014-01-01

    Purpose To determine the intra- and intervisit reproducibility of circumpapillary retinal nerve fiber layer (RNFL) measures using handheld optical coherence tomography (OCT) in sedated children. Design Prospective cross-sectional and longitudinal study Methods Children undergoing sedation for a clinically indicated MRI for an optic pathway glioma and or Neurofibromatosis type 1 (NF1) had multiple 6 × 6 mm volumes (isotropic 300×300 or non-isotropic 1000×100 samplings) acquired over the optic nerve. Children with two handheld OCT sessions within 6 months were included in the intervisit cohort. The intra- and inter-visit coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated for the average and anatomic quadrant circumpapillary RNFL thickness. Results Fifty-nine subjects (mean age 5.1 years, range 0.8–13.0 years) comprised the intravisit cohort and 29 subjects (mean age 5.7 years, range 1.8–12.7 years) contributed to the intervisit cohort. Forty-nine subjects had an optic pathway glioma and 10 subjects had NF1 without an optic pathway glioma. The CV was comparable regardless of imaging with an isotropic and non-isotropic volume in both the intra- and intervisit cohorts. The average circumpapillary RNFL demonstrated the lowest CV and highest ICC compared to the quadrants. For the intervisit cohort, the average ICC was typically higher while the CV was typically lower, but not statistically different compared to the other quadrants. Discussion Circumpapillary RNFL measures acquired with handheld OCT during sedation demonstrate good intra- and intervisit reproducibility. Handheld OCT has the potential to monitor progressive optic neuropathies in young children who have difficulty cooperating with traditional OCT devices. PMID:24983792

  1. In vivo depth-resolved birefringence measurements of the human retinal nerve fiber layer by polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Cense, Barry; Chen, Teresa C.; Park, B. Hyle; Pierce, Mark C.; de Boer, Johannes F.

    2002-09-01

    To our knowledge, this is the first demonstration of in vivo depth-resolved birefringence measurements of the human retinal nerve fiber layer (RNFL) by use of polarization-sensitive optical coherence tomography (PS-OCT). Because glaucoma causes nerve fiber layer damage, which may cause loss of retinal birefringence, PS-OCT is a potentially useful technique for the early detection of glaucoma. We built a fiber-based PS-OCT setup that produces quasi-real-time images of the human retina in vivo. Preliminary measurements of a healthy volunteer showed that the double-pass phase retardation per unit depth of the RNFL near the optic nerve head is 39 +/- 6°/100 μm.

  2. Wetting of flexible fibre arrays.

    PubMed

    Duprat, C; Protière, S; Beebe, A Y; Stone, H A

    2012-02-23

    Fibrous media are functional and versatile materials, as demonstrated by their ubiquity both in natural systems such as feathers and adhesive pads and in engineered systems from nanotextured surfaces to textile products, where they offer benefits in filtration, insulation, wetting and colouring. The elasticity and high aspect ratios of the fibres allow deformation under capillary forces, which cause mechanical damage, matting self-assembly or colour changes, with many industrial and ecological consequences. Attempts to understand these systems have mostly focused on the wetting of rigid fibres or on elastocapillary effects in planar geometries and on a fibre brush withdrawn from an infinite bath. Here we consider the frequently encountered case of a liquid drop deposited on a flexible fibre array and show that flexibility, fibre geometry and drop volume are the crucial parameters that are necessary to understand the various observations referred to above. We identify the conditions required for a drop to remain compact with minimal spreading or to cause a pair of elastic fibres to coalesce. We find that there is a critical volume of liquid, and, hence, a critical drop size, above which this coalescence does not occur. We also identify a drop size that maximizes liquid capture. For both wetting and deformation of the substrates, we present rules that are deduced from the geometric and material properties of the fibres and the volume of the drop. These ideas are applicable to a wide range of fibrous materials, as we illustrate with examples for feathers, beetle tarsi, sprays and microfabricated systems. PMID:22358841

  3. Central Glaucomatous Damage of the Macula Can Be Overlooked by Conventional OCT Retinal Nerve Fiber Layer Thickness Analyses

    PubMed Central

    Wang, Diane L.; Raza, Ali S.; de Moraes, Carlos Gustavo; Chen, Monica; Alhadeff, Paula; Jarukatsetphorn, Ravivarn; Ritch, Robert; Hood, Donald C.

    2015-01-01

    Purpose To assess the extent to which glaucomatous damage of the macula can be detected using the summary statistics of a commercial report based upon the circumpapillary retinal nerve fiber layer (cpRNFL) thickness obtained with frequency domain optical coherence tomography (fdOCT). Methods One hundred forty-three eyes of 143 open-angle glaucoma patients and suspects (56.4 ± 13.8 years) had 10-2 visual fields (VFs) and fdOCT macular and disc cube scans. RNFL and retinal ganglion cell plus inner plexiform layer thickness and probability maps were generated and combined with 10-2 VF information in a single-page, custom report previously described. Three graders evaluated these reports and classified each eye as “abnormal macula” or “normal macula.” Commercially available fdOCT reports for cpRNFL thickness were generated using the automatic segmentation algorithm and norms from the machine. The ability of the reports to detect macular damage was analyzed in three ways: temporal quadrant (TQ) < 5%; TQ < 5% or clock hour 7 < 1% (TQ + CH7); and clock hours 7 through 10 with two sectors < 5% or one sector < 1% (CH7−10). Results Sixty-one (43%) eyes were classified “abnormal macula” and 41 (29%) as “normal macula”; the 10-2 VFs and OCT probability maps did not agree in the remaining eyes. Of the 61 abnormal eyes, the TQ criterion missed 47 (77%); TQ + CH7 missed 24 (39%); and CH7−10 missed 22 (36%). Conclusions Conventional cpRNFL analyses on commercial OCT reports can miss macular (central field) damage. Translational Relevance To detect glaucomatous damage of the macula, additional tests, such as macular cube scans and/or 10-2 VFs, should be performed. PMID:26644964

  4. 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

  5. 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.

  6. Moderate-power cw fibre lasers

    SciTech Connect

    Kurkov, Andrei S; Dianov, Evgenii M

    2004-10-31

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

  7. Fibre and bowel transit times.

    PubMed

    Gear, J S; Brodribb, A J; Ware, A; Mann, J I

    1981-01-01

    1. Bowel transit time has been investigated in vegetarians and non-vegetarians and related to dietary fibre intake and the presence of diverticular disease. 2. Vegetarians who have less diverticular disease than non-vegetarians have more rapid transit times. 3. Subjects with total dietary fibre intake of more than 30 g/d all had transit times of less than 75 h whereas 38% of those eating less had transit times exceeding 75 h and varying up to 124 h. 4. Individuals with diverticular disease were found to have faster transit times than those without the disease. 5. The colon may respond to a fibre-depleted diet either by becoming hyperactive and prone to diverticular disease or by becoming hypoactive leading to constipation. PMID:6258626

  8. Dietary fibre and colonic neoplasia.

    PubMed Central

    Freeman, H J

    1979-01-01

    Dietary plant fibre, or plantix, is thought to play a significant role in the pathogenesis of colon cancer in humans. It is a complex polymeric substance that has several distinct components resistant to hydrolysis by the digestive enzymes of humans. These components include cellulose, hemicelluloses, pectins, lignin, gums, mucilages and, in certain instances, algal polysaccharides. These polymers have different physicochemical properties, and recent evidence from experimental studies in animals treated with carcinogens suggests that some may exert protective effects in the intestine and others may enhance colon carcinogenesis. This review synthesizes information on the chemical composition, methods of analysis and physicochemical properties of dietary plant fibre and reviews available studies examining the role of fibre in colonic neoplasia in animals and humans. PMID:466603

  9. Dietary fibre and cardiovascular health.

    PubMed

    Snchez-Muniz, F J

    2012-01-01

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

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

    PubMed

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

    2015-04-01

    Fibre is an important nutrient for rabbit health, and, on commercial pet rabbit packaging, it is labelled as crude fibre (CF). In several species, it is considered that CF is not an accurate representation of the fibre content in feedstuffs. The objective of this study was to compare the CF stated on the label (CFL) with laboratory analysis of CF (CFA) and the analysed content of total dietary fibre (TDF) in different commercial pet rabbit feeds. We selected 15 commercial diets and analysed CF and TDF. A mixed model was used to evaluate differences between CFL, CFA and TDF, and linear regression was performed to study the correlation between CFL and CFA with TDF. CFA and CFL were not significantly different (p = 0.836) in the feeds studied, and both were lower than TDF (p < 0.001). The correlations between TDF and both CFA and CFL were significant (p < 0.001 and p = 0.02, respectively), but the correlation was better with CFA (R = 0.86) than with CFL (R = 0.53). As expected, TDF content was higher than CF content, an average of two times. These results suggest that the CF content in rabbit diets reported on the label is not an appropriate indicator of their total fibre content, although further work with a larger sample size is required to confirm these results. PMID:25865419

  11. Coherent combining of fibre lasers

    NASA Astrophysics Data System (ADS)

    Desfarges-Berthelemot, Agnès; Kermène, Vincent; Sabourdy, David; Boullet, Johan; Roy, Philippe; Lhermite, Jerôme; Barthélémy, Alain

    2006-03-01

    Recent development of fibre lasers makes them good candidates to supplant bulk lasers especially for high power applications. A solution for power scaling consists in combining several standard fibre lasers emitting moderate power. Coherent combining techniques can be classified in two broad classes: aperture-filling methods and collinear interferometric summation methods. For the first, the phase-locking of the different emitters leads to a power combining only in the far field, whereas for the second, the power combining is obtained in both near field and far field. To cite this article: A. Desfarges-Berthelemot et al., C. R. Physique 7 (2006).

  12. 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.

  13. DEVELOPING STANDARDS TO JUDGE FLAX FIBRE QUALITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Unlike cotton, flax and other bast fibres do not have objective standards for testing or classification. Flax fibres are evaluated and graded within countries or individual companies, but only one test method (ISO 2370 for flax fibre fineness) is recognized on an international level. Marketing of ...

  14. Friction and wear of human hair fibres

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  15. Correlation between the ganglion cell complex and structural measures of the optic disc and retinal nerve fiber layer in glaucoma.

    PubMed

    Bresciani-Battilana, Erica; Teixeira, Ivan C; Barbosa, Diego T Q; Caixeta-Umbelino, Cristiano; Paolera, Maurício D; Kasahara, Niro

    2015-10-01

    To correlate the ganglion cell complex (GCC) parameters with structural measures of the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) as evaluated by Fourier-Domain optic coherence tomography (OCT). This retrospective study included patients with glaucoma, ocular hypertensive patients and glaucoma suspects who had previously undergone OCT examination with the RTVue-100. The parameters of GCC (average, superior, inferior, focal loss volume [FLV], global loss volume [GLV]) were correlated with the values of the ONH (cup volume, cup area, horizontal cup-to-disk ratio, vertical cup-to-disk ratio, and rim area) and RNFL (average, superior, and inferior) using Pearson's correlation coefficient. The sample included 74 eyes of 37 patients. All correlations between GCC parameters and RNFL were strong (r > 0.60). The correlation between GCC parameters and ONH were good for most parameters, except that for FLV and cup volume (r = 0.13), GLV and cup volume (r = 0.09), and GLV and cup area (r = 0.21). The GCC parameters can be used as structural measures of the glaucomatous optic neuropathy. PMID:25183459

  16. Effects of timing of vitrectomy performed for open-globe injury patients on the thickness of retinal nerve fiber layer

    PubMed Central

    Chen, Xiaoming; Zhu, Yanni; Hu, Shuqiong; Zhu, Yanhua

    2015-01-01

    Objective: To study the effects of timing of vitrectomy performed for open-globe injury patients on the thickness of retinal nerve fiber layer (RNFL). Methods: A total of 120 patients with traumatic optic neuropathy (TON) were selected and divided into a treatment group and a control group by random draw (n=60). Vitrectomy was performed within one week upon injury for treatment group and after one week for control group. The thickness of RNFL was observed by optical coherence tomography. Results: All surgeries were conducted successfully, without severe complications. The best corrected visual acuity of treatment group surpassed that of control group one month after surgery, and treatment group had an obviously higher overall effective rate (95.0%) than control group did (81.7%). The incidence rate of postoperative complications in treatment group (6.7%) was significantly lower than that of control group (28.3%) (P<0.05). Logistic multivariate regression analysis showed that vitrectomy timing and postoperative complications were independent risk factors of prognosis (P<0.05). Both groups had significantly thinner RNFLs one week after surgery (P<0.05), and treatment group almost recovered within one month (P>0.05). Conclusion: Early vitrectomy effectively augmented the visual acuity of patients with TON, decreased complications, affected RNFL thickness reversibly, and improved prognosis. PMID:25878623

  17. 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)

  18. Microcystic Inner Nuclear Layer Changes and Retinal Nerve Fiber Layer Defects in Eyes with Glaucoma

    PubMed Central

    Hasegawa, Tomoko; Akagi, Tadamichi; Yoshikawa, Munemitsu; Suda, Kenji; Yamada, Hiroshi; Kimura, Yugo; Nakanishi, Hideo; Miyake, Masahiro; Unoki, Noriyuki; Ikeda, Hanako Ohashi; Yoshimura, Nagahisa

    2015-01-01

    Objective To examine microcystic inner nuclear layer (INL) changes in glaucomatous eyes and to determine associated factors. Design Retrospective, cross-sectional, observational study. Methods Two hundred seventeen eyes of 133 patients with primary open angle glaucoma (POAG), 41 eyes of 32 patients with preperimetric glaucoma and 181 normal eyes of 117 subjects were ultimately included. Microcystic INL lesions were examined with infrared fundus images and with 19 vertical spectral domain optical coherence tomography (SD-OCT) images in the macular area. Results Microcystic INL changes were observed in 6.0% of eyes with POAG, but none of the normal eyes or eyes with preperimetric glaucoma showed microcystic INL changes. The proportion of eyes with advanced glaucoma was significantly larger (P = 0.013) in eyes with microcystic lesions than without. The visual field mean deviation (MD) slope was also significantly worse (P = 0.027) in eyes with microcystic lesions. No significant differences were observed in age, sex, refraction, axial length, intraocular pressure, or MD value between eyes with and without microcystic INL lesions. In several cases, microcystic INL lesions occurred along with glaucomatous visual field progression. The retinal nerve fiber layer (RNFL) thickness (P = 0.013) and ganglion cell layer (GCL) + inner plexiform layer thickness (P = 0.023) were significantly lower in areas with microcystic lesions than without. The INL was also significantly thicker (P = 0.002) in areas with microcystic lesions. Conclusions Microcystic INL lesions in glaucomatous eyes are closely associated with RNFL and GCL thinning and correlated with worse MD slope. These INL lesions may indicate focal and progressive damage in glaucoma. PMID:26066021

  19. Helvacioglu reproducibility index: a new algorithm to evaluate the effects of misalignments on the measurements of retinal nerve fiber layer by spectral-domain OCT

    PubMed Central

    Helvacioglu, Firat; Uyar, Osman Murat; Sencan, Sadik; Tunc, Zeki; Kapran, Ziya

    2015-01-01

    AIM To evaluate the effect of misalignment on the measurements of retinal nerve fiber layer (RNFL) by spectral-domain optical coherence tomography (OCT). METHODS A total of 42 eyes from 21 healthy young subjects underwent RNFL measurements with RTVue spectral-domain OCT (Optovue Inc., Fremont, California, USA). Two baseline measurements with perfectly aligned central circle to the borders of the optic nerve and four misaligned measurements which were misaligned towards to four quadrants were taken. The differences in RNFL between the baseline and misaligned measurements were analyzed with a new algorithm called Helvacioglu reproducibility index (HRI) which is designed to measure the reproducibility of the scans by evaluating the RNFL changes in the four main quadrants. RESULTS The average RNFL scores of the first two baseline measurements have good correlation (c=0.930) and good reproducibility scores (0.15±0.07). Superior misaligned measurements had significantly lower superior quadrant score and higher inferior quadrant score, similar nasal and little higher temporal scores (P1, P2<0.001, P3=0.553, P4=0.001). Inferior misaligned measurements had significantly higher superior quadrant score and lower inferior quadrant score with similar temporal and little lower nasal scores (P1, P2<0.001, P3=0.315, P4=0.016). Nasal misaligned measurements had significantly higher temporal quadrant score and lower nasal quadrant score with little lower superior and inferior scores (P1, P2, P4<0.001, P3=0.005). Temporal misaligned measurements had significantly higher nasal quadrant score and lower temporal quadrant score with similar superior and little higher inferior scores (P1, P2<0.001, P3=0.943, P4=0.001). CONCLUSION Good alignment of the central circle to the borders of optic nerve is crucial to have correct and repeatable RNFL measurements. Misalignment to a quadrant resulted in falsely low readings at that quadrant and falsely high readings at the opposite quadrant. PMID:26558218

  20. A colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell

    NASA Astrophysics Data System (ADS)

    Zhang, Zhitao; Guo, Kunping; Li, Yiming; Li, Xueyi; Guan, Guozhen; Li, Houpu; Luo, Yongfeng; Zhao, Fangyuan; Zhang, Qi; Wei, Bin; Pei, Qibing; Peng, Huisheng

    2015-04-01

    The emergence of wearable electronics and optoelectronics requires the development of devices that are not only highly flexible but can also be woven into textiles to offer a truly integrated solution. Here, we report a colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell (PLEC). The fibre-shaped PLEC is fabricated using all-solution-based processes that can be scaled up for practical applications. The design has a coaxial structure comprising a modified metal wire cathode and a conducting aligned carbon nanotube sheet anode, with an electroluminescent polymer layer sandwiched between them. The fibre shape offers unique and promising advantages. For example, the luminance is independent of viewing angle, the fibre-shaped PLEC can provide a variety of different and tunable colours, it is lightweight, flexible and wearable, and it can potentially be woven into light-emitting clothes for the creation of smart fabrics.

  1. Palladium coated ball lens for optical fibre refractometry based hydrogen sensing

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sahar A.; Correia, Ricardo; Francis, Daniel; Brooks, Simon J.; Jones, Ben J. S.; Thompson, Alexander W. J.; Hodgkinson, Jane; Tatam, Ralph P.

    2014-05-01

    An optical fibre refractometer using a ball lens as a sensor head has been developed and characterised. Light from a superluminescent diode is directed to an optical fibre sensor head and the intensity of the returned beam gives a measure of the refractive index of the medium at the ball lens fibre tip. A second beam is used to reference the intensity measurements. The system is capable of detecting changes in refractive index with a resolution of 0.003 RIU. The ball lenses have been coated with an 80nm thick layer of palladium and the potential use of this system as a micromirror hydrogen sensor is demonstrated. This technique offers a simple sensor head arrangement, with a large signal sampling area compared with that of a bare fibre.

  2. Muscle-spindle distribution in relation to the fibre-type composition of masseter in mammals.

    PubMed Central

    Rowlerson, A; Mascarello, F; Barker, D; Saed, H

    1988-01-01

    The various parts of the masseter muscle complex (pars superficialis, pars profunda, zygomaticomandibularis, maxillomandibularis) in the rat, guinea-pig, rabbit, cat and macaque monkey were examined to discover whether they showed any relationship between the distribution of muscle spindles and extrafusal fibre types. Intrafusal (spindle) and extrafusal fibre types in masseter were compared with those in limb muscles and were identified by a combination of standard histochemical methods and indirect immunoperoxidase staining with antibodies specific for the various isoforms of myosin characteristic of fibre types in mammalian muscle. In general, the fibre-type properties of intrafusal fibres in masseter resembled those in limb muscle spindles, but the extrafusal fibre-type composition was unlike that in most limb muscles. In the rat masseter, most of the spindles were clustered together in a few very restricted areas. Extensive fusion of the external capsules of adjacent spindles, resulting in the formation of giant spindles, was seen in the cat and monkey masseter; this was sometimes accompanied by the enclosure of extrafusal fibres within the fused spindles. Common to all species, but strongest of all in the rat, was a close association between the distributions of muscle spindles and extrafusal Type I (slow twitch) fibres within the masseter complex. Muscle spindles and Type I fibres were either absent or rarest in the superficial part of masseter, but were most common in the deep layer (pars profunda) or zygomaticomandibularis. The functional significance of these observations is discussed. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 PMID:2978294

  3. Optical temperature switch based on microstructured fibre filled with different chemical mixtures

    NASA Astrophysics Data System (ADS)

    Marc, P.; Piliszek, P.; Murawski, M.; Szymanski, M.; Nasilowski, T.; Jaroszewicz, L. R.

    2012-04-01

    Size, shape and location of the air holes allow to tailor microstructured fibre (MSF) parameters in a very wide range way beyond classical fibres what opens up many possibilities for various applications. Additionally, the propagation parameters of MSF can be actively tuned when the air-holes are filled with different gases, liquids (e.g., liquid crystals) or solid materials (e.g., polymers). The mode confinement in such a filled MSF can be affected by temperature dependent refractive index of material filling the fibre. This idea puts forward a new type of components for creating novel fibre devices such as switches, attenuators and others. Variable optical attenuators (VOAs) play an important role in optical communications as equalizers for dynamic channel power and wavelength division multiplexing in a transmission system. Controlling and monitoring of optical power are also necessary in sensing applications, and especially, in optical systems which require high power laser operation or critical temperature threshold monitoring. Various types of VOA have been developed based on different mechanisms, such as bending loss control, light leaking from the fibre cladding, temperature tuning of the polymer incorporated into the tapered microstructured fibre or electrical tuning of the liquid crystal layers. In this paper we would like to discuss the highly dynamic VOA based on a tuneable microstructured fibre filled with different chemical mixtures used as an on/off temperature switch. Furthermore, the technology of low loss coupling and splicing of the applied MSF with a standard single mode fibre has been developed. Therefore, in the proposed application an optical signal can be transmitted to and from the switch by a standard telecom fibre which considerably reduces transmission losses and allows for the use of standard off-the-shelf components reducing costs of the overall system.

  4. 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)

  5. Influence of fibre distribution and grain size on the mechanical behaviour of friction stir processed Mg–C composites

    SciTech Connect

    Mertens, A.; Simar, A.; Adrien, J.; Maire, E.; Montrieux, H.-M.; Delannay, F.; Lecomte-Beckers, J.

    2015-09-15

    Short C fibres–Mg matrix composites have been produced by friction stir processing sandwiches made of a layer of C fabric stacked between two sheets of Mg alloy AZ31B or AZ91D. This novel processing technique can allow the easy production of large-scale metal matrix composites. The paper investigates the microstructure of FSPed C fibre–Mg composites in relation with the fragmentation of the C fibres during FSP and their influence on the tensile properties. 3D X-ray tomography reveals that the fibres orient like onion rings and are more or less fragmented depending on the local shear stress during the process. The fibre volume fraction can be increased from 2.3% to 7.1% by reducing the nugget volume, i.e. by using a higher advancing speed in AZ31B alloy or a stronger matrix alloy, like AZ91D alloy. A higher fibre volume fraction leads to a smaller grain size which brings about an increase of the composite yield strength by 15 to 25%. However, a higher fibre volume fraction also leads to a lower fracture strain. Fracture surface observations reveal that damage occurs by fibre/matrix decohesion along fibres oriented perpendicularly to the loading direction. - Graphical abstract: Display Omitted - Highlights: • C–Mg MMCs were produced by FSP sandwiches made of a C fabric between Mg sheets. • Fibre fragmentation and erosion is larger when the temperature reached during FSP is lower. • A lower advancing speed brings a lower fibre volume fraction and a lower grain size. • X-ray tomography reveals that fibres orient along the FSP material flow. • The fibres and grain size reduction increase the yield strength by 15 to 25%.

  6. Gene expression in developing fibres of Upland cotton (Gossypium hirsutum L.) was massively altered by domestication

    PubMed Central

    2010-01-01

    Background Understanding the evolutionary genetics of modern crop phenotypes has a dual relevance to evolutionary biology and crop improvement. Modern upland cotton (Gossypium hirsutum L.) was developed following thousands of years of artificial selection from a wild form, G. hirsutum var. yucatanense, which bears a shorter, sparser, layer of single-celled, ovular trichomes ('fibre'). In order to gain an insight into the nature of the developmental genetic transformations that accompanied domestication and crop improvement, we studied the transcriptomes of cotton fibres from wild and domesticated accessions over a developmental time course. Results Fibre cells were harvested between 2 and 25 days post-anthesis and encompassed the primary and secondary wall synthesis stages. Using amplified messenger RNA and a custom microarray platform designed to interrogate expression for 40,430 genes, we determined global patterns of expression during fibre development. The fibre transcriptome of domesticated cotton is far more dynamic than that of wild cotton, with over twice as many genes being differentially expressed during development (12,626 versus 5273). Remarkably, a total of 9465 genes were diagnosed as differentially expressed between wild and domesticated fibres when summed across five key developmental time points. Human selection during the initial domestication and subsequent crop improvement has resulted in a biased upregulation of components of the transcriptional network that are important for agronomically advanced fibre, especially in the early stages of development. About 15% of the differentially expressed genes in wild versus domesticated cotton fibre have no homology to the genes in databases. Conclusions We show that artificial selection during crop domestication can radically alter the transcriptional developmental network of even a single-celled structure, affecting nearly a quarter of the genes in the genome. Gene expression during fibre development within accessions and expression alteration arising from evolutionary change appears to be 'modular' - complex genic networks have been simultaneously and similarly transformed, in a coordinated fashion, as a consequence of human-mediated selection. These results highlight the complex alteration of the global gene expression machinery that resulted from human selection for a longer, stronger and finer fibre, as well as other aspects of fibre physiology that were not consciously selected. We illustrate how the data can be mined for genes that were unwittingly targeted by aboriginal and/or modern domesticators during crop improvement and/or which potentially control the improved qualities of domesticated cotton fibre. See Commentary: http://www.biomedcentral.com/1741-7007/8/137 PMID:21078138

  7. Sensitivity improvement of an all-fibre computerized optical fluorescence setup using dual fibre probes

    NASA Astrophysics Data System (ADS)

    Patel, A.; Bogomolny, E.; Cheng, M.; Swift, S.; Vanholsbeeck, F.

    2013-06-01

    We investigate different fibre probes for fluorescence measurements. Our design shows a threefold sensitivity improvement compared to a single fibre probe allowing bacteria concentration as low as 1 CFU/ml to be measured.

  8. Seeing through chaos in multimode fibres

    NASA Astrophysics Data System (ADS)

    Plöschner, Martin; Tyc, Tomáš; Čižmár, Tomáš

    2015-08-01

    In a similar fashion to diffusers or other highly scattering media, multimode fibres deliver coherent light signals in the form of apparently random speckled patterns. In contrast to other optically random environments, multimode fibres feature remarkably faithful cylindrical symmetry. Our experimental studies challenge the commonly held notion that classifies multimode fibres as unpredictable optical systems. Instead, we demonstrate that commercially available multimode fibres are capable of performing as extremely precise optical components. We show that, with a sufficiently accurate theoretical model, light propagation within straight or even significantly deformed segments of multimode fibres may be predicted up to distances in excess of hundreds of millimetres. Harnessing this newly discovered predictability in imaging, we demonstrate the unparalleled power of multimode fibre-based endoscopes, which offer exceptional performance both in terms of resolution and instrument footprint. These results thus pave the way for numerous exciting applications, including high-quality imaging deep inside motile organisms.

  9. Single nucleotide polymorphism for animal fibre identification.

    PubMed

    Subramanian, Selvi; Karthik, T; Vijayaraaghavan, N N

    2005-03-16

    Animal fibres are highly valuable industrial products often adulterated during marketing. Currently, there is no precise method available to identify and differentiate the fibres. In this study, a PCR-RFLP technique was exploited to differentiate cashmere and wool fibres derived from goat and sheep, respectively. The presence of DNA in animal hair shafts has enabled the isolation of DNA from scoured cashmere and wool fibres. The mitochondrial cytochrome b sequences of both species were amplified by PCR using primers designed from conserved regions. The polymorphism observed between the two species was detected by restricting the amplified product by endonucleases viz., BamH1 and Ssp1. The RFLP profile clearly distinguishes the cashmere and wool fibres and this technique can also be exploited to test adulteration in animal fibres qualitatively. PMID:15664079

  10. Photonic crystal fibres for lasers and amplifiers

    NASA Astrophysics Data System (ADS)

    Roy, Philippe; Leproux, Philippe; Février, Sébastien; Pagnoux, Dominique; Auguste, Jean-Louis; Blondy, Jean-Marc; Hilaire, Stéphane; Lavoute, Laure; Jamier, Raphael; Desfarges-Berthelemot, Agnès; Kermène, Vincent; Restoin, Christine

    2006-03-01

    Air Silica microstructure fibres, often improperly named Photonic Crystal Fibres (PCFs), offer singular propagation properties because of the multiple possible interactions between the guided fields and the heterogeneous structure. We propose a short review of the various PCFs fields of applications while showing, through various examples of fibre structures, how these properties are exploited and which are the most significant results. To cite this article: Ph. Roy et al., C. R. Physique 7 (2006).

  11. Scintillating Fibre Tracking at High Luminosity Colliders

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    PubMed

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

    2015-09-01

    Damage to nociceptor nerve fibres may give rise to peripheral neuropathies, some of which are pain free and some are painful. A hallmark of many peripheral neuropathies is the loss of small nerve fibres in the epidermis, a condition called small-fibre neuropathy (SFN) when it is predominantly the small nerve fibres that are damaged. Historically, SFN has been very difficult to diagnose as clinical examination and nerve conduction studies mainly detect large nerve fibres, and quantitative sensory testing is not sensitive enough to detect small changes in small nerve fibres. However, taking a 3-mm punch skin biopsy from the distal leg and quantification of the nerve fibre density has proven to be a useful method to diagnose SFN. However, the correlation between the nerve fibre loss and other test results varies greatly. Recent studies have shown that it is possible not only to extract information about the nerve fibre density from the biopsies but also to get an estimation of the nerve fibre length density using stereology, quantify sweat gland innervation and detect morphological changes such as axonal swelling, all of which may be additional parameters indicating diseased small fibres relating to symptoms reported by the patients. In this review, we focus on available tests to assess structure and function of the small nerve fibres, and summarize recent advances that have provided new possibilities to more specifically relate structural findings with symptoms and function in patients with SFN. PMID:25546653

  13. 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.

  14. Modelling skeletal muscle fibre orientation arrangement.

    PubMed

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

    2011-12-01

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

  15. Fibre optic modal interferometry for sensing applications

    NASA Astrophysics Data System (ADS)

    Santos, J. L.; Ferreira, L. A.; Araújo, F. M.; Frazão, O.

    2010-10-01

    Fibre optic modal interferometry has been around for long as a sensing concept. Initially mainly supported on the utilization of standard Hi-Bi fibres associated to polarimetric modal interferometry, later this sensing approach evolved to modal interference based on spatial modes propagating in the core, and on spatial modes propagating in the core and in the cladding, with coupling performed by fibre devices such as long period gratings and tapers. More recently the outcome of Photonic Crystal Fibres (PCF) originated a burst of activity around the concept of modal interferometry for sensing. The reasons for that viewed in a historic perspective are presented in this work.

  16. 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

  17. Towards the Knittability of Graphene Oxide Fibres.

    PubMed

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

    2015-01-01

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

  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. 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.

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

    SciTech Connect

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

    2013-12-15

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

  1. Assessment of Macular Peripapillary Nerve Fiber Layer and Choroidal Thickness Changes in Pregnant Women with Gestational Diabetes Mellitus, Healthy Pregnant Women, and Healthy Non-Pregnant Women

    PubMed Central

    Acmaz, Gokhan; Atas, Mustafa; Gulhan, Ahmet; Acmaz, Banu; Atas, Fatma; Aksoy, Huseyin; Zararsiz, Gokmen; Gokce, Gokcen

    2015-01-01

    Background Gestational diabetes mellitus (GDM) is a risk factor for the development of type II diabetes and it causes maternal and child morbidity. Screening for diabetic retinopathy (DR) is important because patients who develop DR have no symptoms until macular edema and/or proliferative diabetic retinopathy (PDR) are already present. The aim of this study was to determine the early retinal findings of GDM. Material/Methods This study was conducted in a tertiary research center. We conducted a prospective cross-sectional study with 3 groups: Group 1 consisted of 36 pregnant women with GDM, Group 2 consisted of 24 healthy pregnant women, and Group 3 consisted of 38 healthy non-pregnant women of reproductive age. Spectralis optical coherence tomography (OCT) was used for the assessment. Macular, choroid, and retinal nerve fiber layer (RNFL) thicknesses were evaluated in patients with GDM and comparisons were made among pregnant women with GDM, healthy pregnant women, and healthy non-pregnant women for these parameters. Results The nasal part of the RNFL was significantly thinner in the GDM group than in the healthy pregnant group. None of the patients had retinopathy or macular edema at the time of examination. Conclusions Decreased nasal part of RNFL thickness may be the first retinal change in patients with GDM. Our study suggests that OCT should be performed for the patients with GDM for detection of early retinal changes associated with GDM. PMID:26084958

  2. Investigations of plasma induced effects on the surface properties of lignocellulosic natural coir fibres

    NASA Astrophysics Data System (ADS)

    Praveen, K. M.; Thomas, Sabu; Grohens, Yves; Mozetič, Miran; Junkar, Ita; Primc, Gregor; Gorjanc, Marija

    2016-04-01

    The development of lignocellulosic natural-fibre-reinforced polymers composites are constrained by two limitations: the upper temperature at which the fibre can be processed and the significant differences between the surface energy of the fibre and the polymer matrix. Since the fibres and matrices are chemically different, strong adhesion at their interface is needed for the effective transfer of stress and bond distribution throughout the interface. The present study investigated the plasma induced effects on the surface properties of natural coir fibres. Weakly ionized oxygen plasma was created in two different discharge chambers by an inductively coupled radiofrequency (RF) discharge. The water absorption studies showed an increase of water sorption from 39% to 100%. The morphological study using scanning electron microscopy (SEM) analysis also confirmed the surface changes which were observed after the plasma treatment. The topographic measurements and phase imaging done using atomic force microscopy (AFM) indicated difference in topographic features and etching of coir wall, which points to the removal of the first layer of coir fibre. X-ray photoelectron spectroscopy (XPS) analysis revealed that the oxygen content measured for samples treated at 50 Pa increased from initial 18% to about 32%.

  3. Spectral Domain Optical Coherence Tomography in Glaucoma: Qualitative and Quantitative Analysis of the Optic Nerve Head and Retinal Nerve Fiber Layer (An AOS Thesis)

    PubMed Central

    Chen, Teresa C.

    2009-01-01

    Purpose: To demonstrate that video-rate spectral domain optical coherence tomography (SDOCT) can qualitatively and quantitatively evaluate optic nerve head (ONH) and retinal nerve fiber layer (RNFL) glaucomatous structural changes. To correlate quantitative SDOCT parameters with disc photography and visual fields. Methods: SDOCT images from 4 glaucoma eyes (4 patients) with varying stages of open-angle glaucoma (ie, early, moderate, late) were qualitatively contrasted with 2 age-matched normal eyes (2 patients). Of 61 other consecutive patients recruited in an institutional setting, 53 eyes (33 patients) met inclusion/exclusion criteria for quantitative studies. Images were obtained using two experimental SDOCT systems, one utilizing a superluminescent diode and the other a titanium:sapphire laser source, with axial resolutions of about 6 μm and 3 μm, respectively. Results: Classic glaucomatous ONH and RNFL structural changes were seen in SDOCT images. An SDOCT reference plane 139 μm above the retinal pigment epithelium yielded cup-disc ratios that best correlated with masked physician disc photography cup-disc ratio assessments. The minimum distance band, a novel SDOCT neuroretinal rim parameter, showed good correlation with physician cup-disc ratio assessments, visual field mean deviation, and pattern standard deviation (P values range, .0003–.024). RNFL and retinal thickness maps correlated well with disc photography and visual field testing. Conclusions: To our knowledge, this thesis presents the first comprehensive qualitative and quantitative evaluation of SDOCT images of the ONH and RNFL in glaucoma. This pilot study provides basis for developing more automated quantitative SDOCT-specific glaucoma algorithms needed for future prospective multicenter national trials. PMID:20126502

  4. A comparative study of supercapacitive performances of nickel cobalt layered double hydroxides coated on ZnO nanostructured arrays on textile fibre as electrodes for wearable energy storage devices.

    PubMed

    Trang, Nguyen Thi Hong; Ngoc, Huynh Van; Lingappan, Niranjanmurthi; Kang, Dae Joon

    2014-02-21

    We demonstrated an efficient method for the fabrication of novel, flexible electrodes based on ZnO nanoflakes and nickel-cobalt layered double hydroxides (denoted as ZnONF/NiCoLDH) as a core-shell nanostructure on textile substrates for wearable energy storage devices. NiCoLDH coated ZnO nanowire (denoted as ZnONW/NiCoLDH) flexible electrodes are also prepared for comparison. As an electrode for supercapacitors, ZnONF/NiCoLDH exhibits a high specific capacitance of 1624 F g(-1), which is nearly 1.6 times greater than ZnONW/NiCoLDH counterparts. It also shows a maximum energy density of 48.32 W h kg(-1) at a power density of 27.53 kW kg(-1), and an excellent cycling stability with capacitance retention of 94% and a Coulombic efficiency of 93% over 2000 cycles. We believe that the superior performance of the ZnONF/NiCoLDH hybrids is due primarily to the large surface area of the nanoflake structure and the open spaces between nanoflakes, both of which provide a large space for the deposition of NiCoLDH, resulting in reduced internal resistance and improved capacitance performance. Our results are significant for the development of electrode materials for high-performance wearable energy storage devices. PMID:24441593

  5. 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.

  6. Absolute refractory period of human nerve fibres during postnatal myelination.

    PubMed

    Duron, B; Khater-Boidin, J

    1991-01-01

    In order to study the absolute refractory period of a given group of nerve fibres during development we measured absolute refractory periods and conduction velocities of motor fibres and the most excitable fibres in the human ulnar nerve of newborns, children and adults. In each group of nerve fibres absolute refractory period was not correlated to conduction velocity (i.e. fibre diameters) and was rather constant during development. However, absolute refractory period of the most excitable fibres was smaller than absolute refractory period of motor fibres independently of the subject's age. Thus, it appears that already at birth, absolute refractory period is characteristic for a given group of nerve fibres. PMID:2014765

  7. A comparative study of supercapacitive performances of nickel cobalt layered double hydroxides coated on ZnO nanostructured arrays on textile fibre as electrodes for wearable energy storage devices

    NASA Astrophysics Data System (ADS)

    Trang, Nguyen Thi Hong; Ngoc, Huynh Van; Lingappan, Niranjanmurthi; Kang, Dae Joon

    2014-01-01

    We demonstrated an efficient method for the fabrication of novel, flexible electrodes based on ZnO nanoflakes and nickel-cobalt layered double hydroxides (denoted as ZnONF/NiCoLDH) as a core-shell nanostructure on textile substrates for wearable energy storage devices. NiCoLDH coated ZnO nanowire (denoted as ZnONW/NiCoLDH) flexible electrodes are also prepared for comparison. As an electrode for supercapacitors, ZnONF/NiCoLDH exhibits a high specific capacitance of 1624 F g-1, which is nearly 1.6 times greater than ZnONW/NiCoLDH counterparts. It also shows a maximum energy density of 48.32 W h kg-1 at a power density of 27.53 kW kg-1, and an excellent cycling stability with capacitance retention of 94% and a Coulombic efficiency of 93% over 2000 cycles. We believe that the superior performance of the ZnONF/NiCoLDH hybrids is due primarily to the large surface area of the nanoflake structure and the open spaces between nanoflakes, both of which provide a large space for the deposition of NiCoLDH, resulting in reduced internal resistance and improved capacitance performance. Our results are significant for the development of electrode materials for high-performance wearable energy storage devices.We demonstrated an efficient method for the fabrication of novel, flexible electrodes based on ZnO nanoflakes and nickel-cobalt layered double hydroxides (denoted as ZnONF/NiCoLDH) as a core-shell nanostructure on textile substrates for wearable energy storage devices. NiCoLDH coated ZnO nanowire (denoted as ZnONW/NiCoLDH) flexible electrodes are also prepared for comparison. As an electrode for supercapacitors, ZnONF/NiCoLDH exhibits a high specific capacitance of 1624 F g-1, which is nearly 1.6 times greater than ZnONW/NiCoLDH counterparts. It also shows a maximum energy density of 48.32 W h kg-1 at a power density of 27.53 kW kg-1, and an excellent cycling stability with capacitance retention of 94% and a Coulombic efficiency of 93% over 2000 cycles. We believe that the superior performance of the ZnONF/NiCoLDH hybrids is due primarily to the large surface area of the nanoflake structure and the open spaces between nanoflakes, both of which provide a large space for the deposition of NiCoLDH, resulting in reduced internal resistance and improved capacitance performance. Our results are significant for the development of electrode materials for high-performance wearable energy storage devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04764d

  8. 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

  9. Comparison of direct and indirect methods of measuring airborne chrysotile fibre concentration.

    PubMed

    Eypert-Blaison, Celine; Veissiere, Sylvie; Rastoix, Olivier; Kauffer, Edmond

    2010-01-01

    Transmission electron microscopy observations most frequently form a basis for estimating asbestos fibre concentration in the environment and in buildings with asbestos-containing materials. Sampled fibres can be transferred to microscope grids by applying either a direct [ISO (1995) Draft International ISO/DIS 10312. Ambient air. Determination of asbestos fibres. Direct transfer transmission electron microscopy procedure. Geneva, Switzerland: International Standardization Organization] or an indirect [AFNOR (1996) Détermination de la concentration en fibres d'amiante par microscopie électronique à transmission-Méthode indirecte. Cedex, France: AFNOR, p. 42; ISO (1997) Draft International ISO/DIS 13794. Ambient air. Determination of asbestos fibres. Indirect-transfer transmission electron microscopy procedure. Geneva, Switzerland: International Standardization Organization] method. In the latter case, ISO Standard 13794 recommends filtering calcination residues either on a polycarbonate (PC) filter (PC indirect method) or on a cellulose ester (CE) membrane (CE indirect method). The PC indirect method requires that fibres deposited on a PC filter be covered by a carbon layer, whereas in the CE indirect method, the CE membrane has to be directly processed using a method described in ISO Standard 10312. The purpose of this study was to compare results obtained using, on the one hand, direct preparation methods and, on the other hand, PC indirect or CE indirect methods, for counting asbestos fibres deposited on filters as a result of liquid filtration or air sampling. In direct method-based preparation, we observed that an etching time of 6-14 min does not affect the measured densities, except for fibres <1 microm deposited by liquid filtration. Moreover, in all cases, the direct method gives higher densities than the PC indirect method because of possible fibre disappearance when using the carbon evaporator implemented in the PC indirect method. The CE membrane used for sample preparation in the CE indirect method is collapsed prior to passing it through the carbon evaporator, so the fibres are less likely to disappear at this stage. We then note that the resulting fibre densities for chrysotile-loaded filters prepared using the direct method are close to those obtained with filters prepared using the CE indirect method. Our study therefore shows that, under the implemented experimental conditions, the PC and CE indirect preparation methods described in ISO Standard 13794 are not equivalent. PMID:19812231

  10. Macroscopic CNT fibres inducing non-epitaxial nucleation and orientation of semicrystalline polymers

    NASA Astrophysics Data System (ADS)

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernández-Blázquez, Juan P.; Llorca, Javier; Vilatela, Juan J.

    2015-11-01

    In the presence of macroscopic fibres of carbon nanotubes (CNT), various semicrystalline polymers are shown to present accelerated crystallisation through the formation of a transcrystalline (TC) layer perpendicular to the fibre axis. From differential scanning calorimetry, polarized optical microscopy and X-ray diffraction we establish this to be due to much faster nucleation rates at the fibre surface. The formation of a TC layers is demonstrated for polyvinyldene fluoride, isotactic polypropylene and poly(lactic acid) in spite of the large differences in their chemistry and structure unit cells, suggesting that epitaxy in terms of lattice type or size matching is not a prerequisite. For the three polymers as well as poly(ether ether ketone), the TC layer is identically oriented with the chain axis in the lamella parallel to the CNTs, as observed by wide and small angle X-ray scattering. These results point to polymer chain orientation at the point of adsorption and the formation of a mesomorphic layer as possible steps in the fast nucleation of oriented lamella, with wetting of the CNT fibre surface by the molten semi-crystalline polymer a key condition for heterogeneous nucleation to take place.

  11. Macroscopic CNT fibres inducing non-epitaxial nucleation and orientation of semicrystalline polymers.

    PubMed

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernández-Blázquez, Juan P; Llorca, Javier; Vilatela, Juan J

    2015-01-01

    In the presence of macroscopic fibres of carbon nanotubes (CNT), various semicrystalline polymers are shown to present accelerated crystallisation through the formation of a transcrystalline (TC) layer perpendicular to the fibre axis. From differential scanning calorimetry, polarized optical microscopy and X-ray diffraction we establish this to be due to much faster nucleation rates at the fibre surface. The formation of a TC layers is demonstrated for polyvinyldene fluoride, isotactic polypropylene and poly(lactic acid) in spite of the large differences in their chemistry and structure unit cells, suggesting that epitaxy in terms of lattice type or size matching is not a prerequisite. For the three polymers as well as poly(ether ether ketone), the TC layer is identically oriented with the chain axis in the lamella parallel to the CNTs, as observed by wide and small angle X-ray scattering. These results point to polymer chain orientation at the point of adsorption and the formation of a mesomorphic layer as possible steps in the fast nucleation of oriented lamella, with wetting of the CNT fibre surface by the molten semi-crystalline polymer a key condition for heterogeneous nucleation to take place. PMID:26578104

  12. Macroscopic CNT fibres inducing non-epitaxial nucleation and orientation of semicrystalline polymers

    PubMed Central

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernández-Blázquez, Juan P.; Llorca, Javier; Vilatela, Juan J.

    2015-01-01

    In the presence of macroscopic fibres of carbon nanotubes (CNT), various semicrystalline polymers are shown to present accelerated crystallisation through the formation of a transcrystalline (TC) layer perpendicular to the fibre axis. From differential scanning calorimetry, polarized optical microscopy and X-ray diffraction we establish this to be due to much faster nucleation rates at the fibre surface. The formation of a TC layers is demonstrated for polyvinyldene fluoride, isotactic polypropylene and poly(lactic acid) in spite of the large differences in their chemistry and structure unit cells, suggesting that epitaxy in terms of lattice type or size matching is not a prerequisite. For the three polymers as well as poly(ether ether ketone), the TC layer is identically oriented with the chain axis in the lamella parallel to the CNTs, as observed by wide and small angle X-ray scattering. These results point to polymer chain orientation at the point of adsorption and the formation of a mesomorphic layer as possible steps in the fast nucleation of oriented lamella, with wetting of the CNT fibre surface by the molten semi-crystalline polymer a key condition for heterogeneous nucleation to take place. PMID:26578104

  13. The use of carbon fibres in radiotherapy.

    PubMed

    de Mooy, L G

    1991-10-01

    In this paper we discuss some of the properties of carbon fibres. Use can be made of this strong, rigid and light material for applications during radiotherapy. Some processing methods and a short description of some accessories made of carbon fibre, which are in clinical use in our department, are given. PMID:1957004

  14. Pathways associated with lignin biosynthesis in lignomaniac jute fibres.

    PubMed

    Chakraborty, Avrajit; Sarkar, Debabrata; Satya, Pratik; Karmakar, Pran Gobinda; Singh, Nagendra Kumar

    2015-08-01

    We generated the bast transcriptomes of a deficient lignified phloem fibre mutant and its wild-type jute (Corchorus capsularis) using Illumina paired-end sequencing. A total of 34,163 wild-type and 29,463 mutant unigenes, with average lengths of 1442 and 1136 bp, respectively, were assembled de novo, ~77-79 % of which were functionally annotated. These annotated unigenes were assigned to COG (~37-40 %) and GO (~22-28 %) classifications and mapped to 189 KEGG pathways (~19-21 %). We discovered 38 and 43 isoforms of 16 and 10 genes of the upstream shikimate-aromatic amino acid and downstream monolignol biosynthetic pathways, respectively, rendered their sequence similarities, confirmed the identities of 22 of these candidate gene families by phylogenetic analyses and reconstructed the pathway leading to lignin biosynthesis in jute fibres. We also identified major genes and bast-related transcription factors involved in secondary cell wall (SCW) formation. The quantitative RT-PCRs revealed that phenylalanine ammonia-lyase 1 (CcPAL1) was co-down-regulated with several genes of the upstream shikimate pathway in mutant bast tissues at an early growth stage, although its expression relapsed to the normal level at the later growth stage. However, cinnamyl alcohol dehydrogenase 7 (CcCAD7) was strongly down-regulated in mutant bast tissues irrespective of growth stages. CcCAD7 disruption at an early growth stage was accompanied by co-up-regulation of SCW-specific genes cellulose synthase A7 (CcCesA7) and fasciclin-like arabinogalactan 6 (CcFLA6), which was predicted to be involved in coordinating the S-layers' deposition in the xylan-type jute fibres. Our results identified CAD as a promising target for developing low-lignin jute fibres using genomics-assisted molecular approaches. PMID:25724692

  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. 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)

  17. 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.

  18. Dietary fibre, nuts and cardiovascular diseases.

    PubMed

    Salas-Salvad, Jordi; Bull, Mnica; Prez-Heras, Ana; Ros, Emilio

    2006-11-01

    Dietary fibre has a range of metabolic health benefits. Through a variety of mechanisms, dietary fibre, and the viscous variety in particular, slows down gastric emptying and intestinal transit, decreases the rate of intestinal carbohydrate absorption, and increases faecal bile acid excretion. Therefore, consumption of some types of soluble fibre can enhance satiety, which is associated with a lower BMI, and reduce blood cholesterol and the postprandial glucose response. Surprisingly, the consumption of insoluble fibre from whole grains, though metabolically inert, has been associated with a reduction in the risk of developing coronary heart disease and diabetes in epidemiological studies. The likely reason is that whole grains, like nuts, legumes and other edible seeds, contain many bioactive phytochemicals and various antioxidants. After cereals, nuts are the vegetable foods that are richest in fibre, which may partly explain their benefit on the lipid profile and cardiovascular health. PMID:17125533

  19. 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.

  20. Controllable spatiotemporal nonlinear effects in multimode fibres

    NASA Astrophysics Data System (ADS)

    Wright, Logan G.; Christodoulides, Demetrios N.; Wise, Frank W.

    2015-05-01

    Multimode fibres are of interest for next-generation telecommunications systems and the construction of high-energy fibre lasers. However, relatively little work has explored nonlinear pulse propagation in multimode fibres. Here, we consider highly nonlinear ultrashort pulse propagation in the anomalous-dispersion regime of a graded-index multimode fibre. Low modal dispersion and strong nonlinear coupling between the fibre's many spatial modes result in interesting behaviour. We observe spatiotemporal effects reminiscent of nonlinear optics in bulk mediaself-focusing and multiple filamentationat a fraction of the usual power. By adjusting the spatial initial conditions, we generate on-demand, megawatt, ultrashort pulses tunable between 1,550 and 2,200?nm dispersive waves over one octave; intense combs of visible light; and a multi-octave-spanning supercontinuum. Our results indicate that multimode fibres present unique opportunities for observing new spatiotemporal dynamics and phenomena. They also enable the realization of a new type of tunable, broadband fibre source that could be useful for many applications.

  1. Commercial optical fibre as TLD material.

    PubMed

    Espinosa, G; Golzarri, J I; Bogard, J; García-Macedo, J

    2006-01-01

    This work presents a study of commercial SiO2 optical fibre thermoluminescence (TL) properties as part of the efforts within the Dosimetric Application Project at the Physics Institute of the University of Mexico to develop new radiation detection materials and technologies. The SiO2 commercial optical fibre studied demonstrates useful TL properties and is an excellent candidate for use in TL dosimetry of ionising radiation. The optical fibre's glow curve was observed between 30 and 400 degrees C after exposure to 60Co gamma radiation. One very well-defined glow peak has a maximum at 230 degrees C. The TL response between 100 and 350 degrees C increases monotonically over a wide dose range, from 0.1 Gy to several kGy. It is linear in the range 0.1-3 Gy, which is important for clinical high dose or accident dosimetry. The optical fibre demonstrated high data reproducibility, low residual signal and almost no fading in our study. Moreover, the optical fibre can be re-used several times, after thermal annealing, without any detriment in the dose-response. All these TL characteristics, plus the small size of the 150 microm diameter SiO2 optical fibre, the high flexibility, easy handling and low cost compared with other TL materials, make the commercial optical fibre a very promising TL material for use in research, medicine, industry, reactors, and a variety of other applications. PMID:16709711

  2. Microcystic Changes in the Retinal Internal Nuclear Layer Associated with Optic Atrophy: A Prospective Study

    PubMed Central

    Wolff, Benjamin; Azar, Georges; Vasseur, Vivien; Sahel, José-Alain; Vignal, Catherine; Mauget-Faÿsse, Martine

    2014-01-01

    Purpose. This study aimed at assessing the prevalence of pathologies presenting retinal inner nuclear layer (RINL) microcystic perimacular changes associated with optic nerve atrophy (OA). The charts of patients presenting a significant defect of the Retinal Nerve Fiber Layer (RNFL) were included prospectively in this study. Patients were classified according to the etiology of the RNFL defect. Two hundred and one eyes of 138 patients were enrolled in this analysis. Retinal images obtained showed the typical hyporeflective perifoveal crescent-shaped lesion composed of small round hyporeflective microcysts confined to the RINL in 35.3% of the eyes. Those findings were found in 75% of eyes presenting hereditary OA, 50% of eyes presenting ischemic optic neuritis, 50% of eyes with drusen of the optic nerve (ON), 44.4% of eyes presenting a compressive OA, 32% of eyes presenting inflammatory optic neuropathy from multiple sclerosis, 18.5% of eyes presenting OA from undetermined origin, and 17.6% of eyes having primary open-angle glaucoma. This study demonstrates that microcystic changes in RINL are not specific to a disease but are found in OA of various etiologies. Moreover, their incidence was found to be dependent upon the cause of OA, with the highest incidence occurring in genetic OA. PMID:24701345

  3. Effect of degumming time on silkworm silk fibre for biodegradable polymer composites

    NASA Astrophysics Data System (ADS)

    Ho, Mei-po; Wang, Hao; Lau, Kin-tak

    2012-02-01

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre's properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment.

  4. Fibre-reinforced composites in restorative dentistry.

    PubMed

    Butterworth, Chris; Ellakwa, Ayman E; Shortall, Adrian

    2003-01-01

    Restorative dentistry is constantly evolving as a result of innovative treatment solutions based on new materials, treatment techniques and technologies, with composite materials being a prime example. The advent of fibre reinforcement has further increased the potential uses of composites within restorative dentistry. This paper discusses fibre types, structure and the physical properties of fibre-reinforced composites, in addition to outlining some of the potential clinical applications of this exciting group of materials, thus updating the reader on the new treatment possibilities offered by these developments. PMID:12955951

  5. Electrochromatic carbon nanotube/polydiacetylene nanocomposite fibres

    NASA Astrophysics Data System (ADS)

    Peng, Huisheng; Sun, Xuemei; Cai, Fangjing; Chen, Xuli; Zhu, Yinchao; Liao, Guipan; Chen, Daoyong; Li, Qingwen; Lu, Yunfeng; Zhu, Yuntian; Jia, Quanxi

    2009-11-01

    Chromatic materials such as polydiacetylene change colour in response to a wide variety of environmental stimuli, including changes in temperature, pH and chemical or mechanical stress, and have been extensively explored as sensing devices. Here, we report the facile synthesis of carbon nanotube/polydiacetylene nanocomposite fibres that rapidly and reversibly respond to electrical current, with the resulting colour change being readily observable with the naked eye. These composite fibres also chromatically respond to a broad spectrum of other stimulations. For example, they exhibit rapid and reversible stress-induced chromatism with negligible elongation. These electrochromatic nanocomposite fibres could have various applications in sensing.

  6. 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.; Fernndez-Lafuente, R.; Jaffrezic-Renault, N.; Kuncov, 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 (ORMOCERsORMOCER: Trademark of Fraunhofer-Gesellschaft zur Frderung 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.

  7. Enhanced all-optical modulation in a graphene-coated fibre with low insertion loss

    PubMed Central

    Zhang, Haojie; Healy, Noel; Shen, Li; Huang, Chung Che; Hewak, Daniel W.; Peacock, Anna C.

    2016-01-01

    Graphene is a highly versatile two-dimensional material platform that offers exceptional optical and electrical properties. Of these, its dynamic conductivity and low effective carrier mass are of particular interest for optoelectronic applications as they underpin the material’s broadband nonlinear optical absorption and ultra-fast carrier mobility, respectively. In this paper, we utilize these phenomena to demonstrate a high-speed, in-fibre optical modulator developed on a side-polished optical fibre platform. An especially low insertion loss (<1 dB) was achieved by polishing the fibre to a near atomically smooth surface (<1 nm RMS), which minimized scattering and ensured excellent contact between the graphene film and the fibre. In order to enhance the light-matter interaction, the graphene film is coated with a high index polyvinyl butyral layer, which has the added advantage of acting as a barrier to the surrounding environment. Using this innovative approach, we have fabricated a robust and stable all-fibre device with an extinction ratio as high as 9 dB and operation bandwidth of 0.5 THz. These results represent a key step towards the integration of low-dimensional materials within standard telecoms networks. PMID:27001353

  8. Enhanced all-optical modulation in a graphene-coated fibre with low insertion loss.

    PubMed

    Zhang, Haojie; Healy, Noel; Shen, Li; Huang, Chung Che; Hewak, Daniel W; Peacock, Anna C

    2016-01-01

    Graphene is a highly versatile two-dimensional material platform that offers exceptional optical and electrical properties. Of these, its dynamic conductivity and low effective carrier mass are of particular interest for optoelectronic applications as they underpin the material's broadband nonlinear optical absorption and ultra-fast carrier mobility, respectively. In this paper, we utilize these phenomena to demonstrate a high-speed, in-fibre optical modulator developed on a side-polished optical fibre platform. An especially low insertion loss (<1 dB) was achieved by polishing the fibre to a near atomically smooth surface (<1 nm RMS), which minimized scattering and ensured excellent contact between the graphene film and the fibre. In order to enhance the light-matter interaction, the graphene film is coated with a high index polyvinyl butyral layer, which has the added advantage of acting as a barrier to the surrounding environment. Using this innovative approach, we have fabricated a robust and stable all-fibre device with an extinction ratio as high as 9 dB and operation bandwidth of 0.5 THz. These results represent a key step towards the integration of low-dimensional materials within standard telecoms networks. PMID:27001353

  9. Enhanced all-optical modulation in a graphene-coated fibre with low insertion loss

    NASA Astrophysics Data System (ADS)

    Zhang, Haojie; Healy, Noel; Shen, Li; Huang, Chung Che; Hewak, Daniel W.; Peacock, Anna C.

    2016-03-01

    Graphene is a highly versatile two-dimensional material platform that offers exceptional optical and electrical properties. Of these, its dynamic conductivity and low effective carrier mass are of particular interest for optoelectronic applications as they underpin the material’s broadband nonlinear optical absorption and ultra-fast carrier mobility, respectively. In this paper, we utilize these phenomena to demonstrate a high-speed, in-fibre optical modulator developed on a side-polished optical fibre platform. An especially low insertion loss (<1 dB) was achieved by polishing the fibre to a near atomically smooth surface (<1 nm RMS), which minimized scattering and ensured excellent contact between the graphene film and the fibre. In order to enhance the light-matter interaction, the graphene film is coated with a high index polyvinyl butyral layer, which has the added advantage of acting as a barrier to the surrounding environment. Using this innovative approach, we have fabricated a robust and stable all-fibre device with an extinction ratio as high as 9 dB and operation bandwidth of 0.5 THz. These results represent a key step towards the integration of low-dimensional materials within standard telecoms networks.

  10. 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.

  11. Differences of Intrasession Reproducibility of Circumpapillary Total Retinal Thickness and Circumpapillary Retinal Nerve Fiber Layer Thickness Measurements Made with the RS-3000 Optical Coherence Tomograph

    PubMed Central

    Kita, Yoshiyuki; Hollό, Gábor; Kita, Ritsuko; Horie, Daisuke; Inoue, Makoto; Hirakata, Akito

    2015-01-01

    Purpose To evaluate the intrasession reproducibility of various thickness parameters used to diagnose and follow-up glaucoma, in particular circumpapillary total retinal thickness (cpTR) provided by the RS-3000 optical coherence tomograph (OCT). Methods Fifty-three healthy eyes of 28 subjects underwent three consecutive imaging with the RS-3000 Advance OCT (NIDEK, Aichi,Japan) to evaluate the intrasession reproducibility of circumpapillary total retinal thickness (cpTR), circumpapillary retinal nerve fiber layer thickness (cpRNFL), macular ganglion cell complex thickness (mGCC) and macular total retina thickness (mTR) measurements. Intraclass correlation (ICC), coefficient of variation (CV) and reproducibility coefficient (RC) were calculated for each parameter. Results The ICC and CV values for mean cpTR and cpRNFL were 0.987 and 0.897, and 0.60% and 2.81%, respectively. The RC values for the mean cpTR and cpRNFL were 5.95 μm and 9.04 μm, respectively. For all cpTR parameters the ICC values were higher and both the CV and RC values were lower than those for the corresponding cpRNFL parameters. The ICC and CV values for superior mGCC, inferior mGCC, superior mTR and inferior mTR were 0.983, 0.980, 0.983 and 0.988, and 0.84%, 0.98%, 0.48% and 0.43%, respectively. The RC values for superior mGCC, inferior mGCC, superior mTR and inferior mTR were 2.86 μm, 3.12 μm, 4.41μm and 4.43 μm, respectively. Conclusions Intrasession reproducibility of cpTR, mGCC and mTR measurements made on healthy eyes was high. Repeatability of cpTR measurements was better than that of the corresponding cpRNFL measurements. These results suggest that future clinical investigations addressing detection of glaucoma and glaucomatous progression with the RS-3000 OCT may benefit from focusing on the cpTR parameters. PMID:26657805

  12. Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats

    PubMed Central

    Abbott, Carla J.; Choe, Tiffany E.; Burgoyne, Claude F.; Cull, Grant; Wang, Lin; Fortune, Brad

    2014-01-01

    Purpose To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. Method IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. Results Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77–80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75–95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). Conclusion Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age. PMID:25501362

  13. Effect of Mesh Distribution on Impact Resistance Performance of Kenaf Fibre Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Thiruchelvam, Sivadass; Syamsir, Agusril; Sheng, Chiam Yung; Beddu, Salmia; Nasharuddin Mustapha, Kamal; Usman, Fathoni; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the mesh distribution on the impact performance of kenaf fibre mesh reinforced concrete (KFMRC) for the concrete slab of 300mm × 300mm size reinforced with varied thickness and mesh diameter subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.40 m height has been used in this research work. The objective of this research is to study the effect of the mesh distribution on the impact resistance kenaf fibre mesh concrete for various slab thickness and mesh diameter. 2-layers one Top and one Bottom mesh distribution kenaf mesh is the most efficient in the ability to control crack formation and propagation against impact energy followed by 1-layer Middle mesh distribution and lastly the 1-layer Top mesh distribution is the least effective.

  14. SpaceFibre Demonstrator (Demonstration and Testing)

    NASA Astrophysics Data System (ADS)

    Helfers, T.; Rastetter, P.; Papadas, C.; Parkes, S.

    2014-08-01

    Currently Astrium GmbH and ISD S.A. are planning the development of a demonstrator for SpaceFibre. The SpaceFibre demonstrator will be used to execute functional performance tests and EMC (Electro Magnetic Compatibility) tests. University of Dundee is program prime contractor and provides Astrium with the SpaceFibre IP core. The work is shared between the two partners in the following way: • Astrium: Prime Contractor and Technical Coordination; FPGA Design; EMC Testing • ISD: Development of Demonstrator Board including housing, development of test bed and functional performance testing. The driving requirements for this development are: • SpaceFibre performance, while implementing it into space equivalent components • Design and MAIT of the demonstrator in such a way that representative EMC testing is possible.

  15. Photonic Technologies Integrated into Optical Fibres

    NASA Astrophysics Data System (ADS)

    Martelli, Cicero; Canning, John

    2008-10-01

    Structured optical fibres are numerically and experimentally assessed with focus on technology integration. Three main areas are considered: Fresnel waveguiding, molecular photonics and photo-diffractive gratings. Results lead to new opportunities for sensors and devices.

  16. 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

  17. Towards a super-strainable paper using the Layer-by-Layer technique.

    PubMed

    Marais, Andrew; Utsel, Simon; Gustafsson, Emil; Wågberg, Lars

    2014-01-16

    The Layer-by-Layer technique was used to build a polyelectrolyte multilayer on the surface of pulp fibres. The treated fibres were then used to prepare paper sheets and the mechanical properties of these sheets were evaluated as a function of the number of bi-layers on the fibres. Two different systems were studied: polyethyleneimine (PEI)/nanofibrillated cellulose (NFC), and polyallylamine hydrochloride (PAH)/hyaluronic acid (HA). Model experiments using dual polarization interferometry and SiO₂ surfaces showed that the two systems gave different thicknesses for a given number of layers. The outer layer was found to be a key parameter in the PEI/NFC system, whereas it was less important in the PAH/HA system. The mechanical properties of the sheets made from the PAH/HA treated fibres were significantly greater than those made from untreated fibres, reaching 70 Nm/g in tensile index and 6.5% in strain at break. Such a modification could be very useful for 3D forming of paper, opening new perspectives in for example the packaging industry, with a renewable and biodegradable product as a potential substitute for some of the traditional oil-based plastics. PMID:24188857

  18. 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.

  19. Simulating Fibre Suspensions: Lagrangian versus Statistical Approach

    NASA Astrophysics Data System (ADS)

    Zhao, L. H.; Andersson, H. I.; Gillissen, J. J. J.; Boersma, B. J.

    Fibre suspensions exhibit complex dynamical flow phenomena and are at the same time of immense practical importance, notably in the pulp and paper industries. NTNU and TU Delft have in a collaborative research project adopted two alternative strategies in the simulation of dilute fibre suspensions, namely a statistical approach [2] and a Lagrangian particle treatment [4]. The two approaches have their own advantages and disadvantages. In this paper we aim for the first time to compare the performance of the two.

  20. Photonic crystal fibres in biomedical investigations

    SciTech Connect

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

    2011-04-30

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

  1. 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. PMID:25533626

  2. Reinforcing of Cement Composites by Estabragh Fibres

    NASA Astrophysics Data System (ADS)

    Merati, A. A.

    2014-04-01

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

  3. 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.

  4. Fibre positioning algorithms for the WEAVE spectrograph

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  5. Two-dimensional optical fibre cantilever accelerometer

    NASA Astrophysics Data System (ADS)

    Li, Jun; Sun, J. N.; Miliar, M. M.; Dong, F. Z.; Maier, R. R. J.; Hand, D. P.; MacPherson, W. N.

    2015-09-01

    Focused Ion Beam (FIB) machining has been demonstrated to be capable of fabricating nano and micro scale elements onto optical fibres. In this paper we exploit FIB to fabricate core aligned 45 mirrors at the end of multi-core fibres (MCF). The resulting fibre is used as a component in a two dimensional optical fibre accelerometer. The mirror is produced using a two step process: first a scanning process is used to make a rough cut to define the overall mirror structure. This is followed by a polishing process to create an optical surface finish. The machined 45 mirror can be accurately aligned with optical fibre core, which avoids issues associated with the alignment of external turning mirror components. Proof-of-concept tests demonstrate the use of such a fibre as a two axis acceleration sensor that is interrogated interferometrically. The sensor operated between 0.5g and 4.5g with a cross talk of -24.3dB between axes.

  6. Detection of preperimetric glaucoma using Bruch membrane opening, neural canal and posterior pole asymmetry analysis of optical coherence tomography

    PubMed Central

    Hua, Rui; Gangwani, Rita; Guo, Lei; McGhee, Sarah; Ma, Xiaoli; Li, Jun; Yao, Kai

    2016-01-01

    We analysed retinal nerve fibre layer (RNFL) defects in eyes with normal circumpapillary RNFL (cpRNFL) thickness using posterior pole asymmetry analysis (PPAA) and investigated the parameters of Bruch membrane opening (BMO) and neural canals using enhanced depth imaging spectral domain optical coherence tomography (EDI-SDOCT). A total of 112 preperimetric glaucomatous eyes of 92 patients were examined to obtain cpRNFL thickness using SD-OCT. Posterior pole asymmetry analysis (PPAA) and central cross-sectional images of the optic nerve head (ONH) were obtained using EDI-SDOCT. Minimal and horizontal distances between the BMO and ONH surfaces (BMOM, BMOH) and the terminal of retinal pigment epithelium (RPE) and ONH surfaces (RPEM, RPEH) were measured. The distribution of the absolute black cells in PPAA was more concentrated in eyes with “U”-shaped neural canals (p < 0.0001). The area under the receiver operating characteristic curve of the ratio of RPEM to RPEH (RPE-R, 0.771 ± 0.08) was significantly larger than the ratio of BMOM to BMOH (BMO-R, 0.719 ± 0.009) for PPAA results. A U-shaped neural canal, lower ratio of RPEM to RPEH, and lower ratio of BMOM to BMOH were considered early indicators of RNFL defects in preperimetric glaucomatous eyes with normal cpRNFL. PMID:26883374

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

    PubMed

    Smith, Caren E; Tucker, Katherine L

    2011-06-01

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

  8. Studies of the AZ91 magnesium alloy / SiO2-coated carbon fibres composite microstructure

    NASA Astrophysics Data System (ADS)

    Olszówka-Myalska, A.; Botor-Probierz, A.

    2010-02-01

    The microstructure of magnesium matrix composite reinforced with SiO2nano-layer coated carbon fibres, deposited by sol-gel method was characterized. The composite was obtained by infiltration method and the effect of SiO2 on the composite microstructure was analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM+EDS) and transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (TEM+EDS) methods. Good wettability of fibres by the magnesium alloy AZ91 (Al 9 wt%, Zn 0.3 wt%) was confirmed since fibres were closely surrounded with alloy and pulling-out effect was not visible. The interface region was evidently with aluminium enriched. Near carbon fibre surface a regular layer of SiOX oxide enriched with Al was detected by high angle annular dark field image (HAADF) combined with energy-dispersive X-ray spectroscopy (EDS). The plate or needle shaped very fine particles of Al12Mg17 were identified near the AZ91 matrix zone by bright field (BF) and selected area electron diffraction (SADP).

  9. 3D Non-Woven Polyvinylidene Fluoride Scaffolds: Fibre Cross Section and Texturizing Patterns Have Impact on Growth of Mesenchymal Stromal Cells

    PubMed Central

    Schellenberg, Anne; Ross, Robin; Abagnale, Giulio; Joussen, Sylvia; Schuster, Philipp; Arshi, Annahit; Pallua, Norbert; Jockenhoevel, Stefan; Gries, Thomas; Wagner, Wolfgang

    2014-01-01

    Several applications in tissue engineering require transplantation of cells embedded in appropriate biomaterial scaffolds. Such structures may consist of 3D non-woven fibrous materials whereas little is known about the impact of mesh size, pore architecture and fibre morphology on cellular behavior. In this study, we have developed polyvinylidene fluoride (PVDF) non-woven scaffolds with round, trilobal, or snowflake fibre cross section and different fibre crimp patterns (10, 16, or 28 needles per inch). Human mesenchymal stromal cells (MSCs) from adipose tissue were seeded in parallel on these scaffolds and their growth was compared. Initial cell adhesion during the seeding procedure was higher on non-wovens with round fibres than on those with snowflake or trilobal cross sections. All PVDF non-woven fabrics facilitated cell growth over a time course of 15 days. Interestingly, proliferation was significantly higher on non-wovens with round or trilobal fibres as compared to those with snowflake profile. Furthermore, proliferation increased in a wider, less dense network. Scanning electron microscopy (SEM) revealed that the MSCs aligned along the fibres and formed cellular layers spanning over the pores. 3D PVDF non-woven scaffolds support growth of MSCs, however fibre morphology and mesh size are relevant: proliferation is enhanced by round fibre cross sections and in rather wide-meshed scaffolds. PMID:24728045

  10. 3D non-woven polyvinylidene fluoride scaffolds: fibre cross section and texturizing patterns have impact on growth of mesenchymal stromal cells.

    PubMed

    Schellenberg, Anne; Ross, Robin; Abagnale, Giulio; Joussen, Sylvia; Schuster, Philipp; Arshi, Annahit; Pallua, Norbert; Jockenhoevel, Stefan; Gries, Thomas; Wagner, Wolfgang

    2014-01-01

    Several applications in tissue engineering require transplantation of cells embedded in appropriate biomaterial scaffolds. Such structures may consist of 3D non-woven fibrous materials whereas little is known about the impact of mesh size, pore architecture and fibre morphology on cellular behavior. In this study, we have developed polyvinylidene fluoride (PVDF) non-woven scaffolds with round, trilobal, or snowflake fibre cross section and different fibre crimp patterns (10, 16, or 28 needles per inch). Human mesenchymal stromal cells (MSCs) from adipose tissue were seeded in parallel on these scaffolds and their growth was compared. Initial cell adhesion during the seeding procedure was higher on non-wovens with round fibres than on those with snowflake or trilobal cross sections. All PVDF non-woven fabrics facilitated cell growth over a time course of 15 days. Interestingly, proliferation was significantly higher on non-wovens with round or trilobal fibres as compared to those with snowflake profile. Furthermore, proliferation increased in a wider, less dense network. Scanning electron microscopy (SEM) revealed that the MSCs aligned along the fibres and formed cellular layers spanning over the pores. 3D PVDF non-woven scaffolds support growth of MSCs, however fibre morphology and mesh size are relevant: proliferation is enhanced by round fibre cross sections and in rather wide-meshed scaffolds. PMID:24728045

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  13. Fibre laser with an intracavity polariser based on a long-period fibre grating

    SciTech Connect

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

    2001-05-31

    An all-fibre Er-doped laser emitting linearly polarised radiation is built. The laser uses a long-period fibre grating as a polarisation-dependent absorbing filter. The use of such an intracavity filter provides the degree of polarisation of output radiation as high as 98 % for a differential lasing efficiency of 45 %. (lasers and amplifiers)

  14. 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

  15. Radiation-resistant erbium-doped silica fibre

    SciTech Connect

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

    2007-10-31

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

  16. The role of dietary fibre in the human colon.

    PubMed

    Cummings, J H; Stephen, A M

    1980-12-01

    Several effects of dietary fibre on colonic function have been documented by experiment or deduced from epidemiologic observation. The magnitude of these changes depends on the source and the physical and chemical composition of the fibre used, and on the individual response of the subjects. Three theories of the mode of action of fibre are discussed; they relate to the water-holding capacity of fibre, the production of short-chain fatty acids from fibre in the colon and the alteration by fibre of the colonic microflora. PMID:6257366

  17. 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)

  18. High Reliability Splicing Of Single Mode Fibres

    NASA Astrophysics Data System (ADS)

    Robertson, A. J.; Leach, J. S.; Gurton, P.; Jones, S. R.

    1985-08-01

    Splicing of optical fibres is a key aspect of the manufacture and installation of both landline and submerged optical fibre systems. In many landline applications the splices are housed in large cable joints and are not subjected to any strain in service. A number of techniques have been described in the literature (refs. 1-3) that are suitable for these relatively benign environments. They generally employ solvents and/or mechanical methods to remove the fibre primary and secondary coatings before cleaving and aligning the fibre ends in a splicing machine. Some of these techniques are also suitable for use in submarine cable systems where a cable joint housing is used between lengths of optical cable (ref.4). However, for efficient cable manufacture and lay it is desirable that the cable should be produced in repeater section lengths. Since fibre is not yet produced in such lengths it is necessary to splice sections together and to reinstate the primary and secondary coatings over the splice with the same diameter as the parent fibre coating. As these splices will be incorporated directly into a cable they will be subjected to the same manufacturing and service strains as the fibre and must therefore have high strength. Submarine systems must also be extremely reliable, which demands high reliability from the splices over the 25-year design life of the system. This paper describes the process developed to produce high strength splices reliably and the results of dynamic and static fatigue testing are given. The process is now in production at STC-Submarine Systems Ltd.

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

    PubMed Central

    Hotte, Naomi SC; Deyholos, Michael K

    2008-01-01

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

  20. Retinal nerve fiber layer retardation measurements using a polarization-sensitive fundus camera.

    PubMed

    Fukuma, Yasufumi; Okazaki, Yoshio; Shioiri, Takashi; Iida, Yukio; Kikuta, Hisao; Shirakashi, Motohiro; Yaoeda, Kiyoshi; Abe, Haruki; Ohnuma, Kazuhiko

    2011-07-01

    To measure the retardation distribution of the optic retinal nerve fiber layer (RNFL) from a single image, we have developed a new polarization analysis system that is able to detect the Stokes vector using a fundus camera. The polarization analysis system is constructed with a CCD area image sensor, a linear polarizing plate, a microphase plate array, and a circularly polarized light illumination unit. In this system, the Stokes vector expressing the whole state of polarization is detected, and the influence of the background scattering in the retina and of the retardation caused by the cornea are numerically eliminated. The measurement method is based on the hypothesis that the retardation process of the eye optics can be quantified by a numerical equation that consists of a retardation matrix of all the polarization components. We show the method and the measurement results for normal eyes. Our results indicate that the present method may provide a useful means for the evaluation of retardation distribution of the RNFL. PMID:21806278

  1. Grating-free nth order cascaded Raman fibre lasers using highly Ge-doped low loss fibre.

    PubMed

    Zhao, Yucheng; Li, Yahua; Jackson, Stuart

    2004-08-23

    Pumped by a narrow band Nd(3+)-doped fibre laser, a grating-free three-wavelength Raman fibre laser has been demonstrated. More than 1.3W output power at the third Stokes line of 1230 nm, a bandwidth of 1.8nm and a slope efficiency of ~28% was measured. A four-wavelength Raman fibre laser was also demonstrated using a different resonator that consisted of a 4% fibre end reflector, a dielectric mirror and a single fibre Bragg grating. This method is simple, versatile and cheap compared with conventional methods employing fibre Bragg gratings used to resonate all Stokes wavelengths. PMID:19483946

  2. Modelling non-symmetric collagen fibre dispersion in arterial walls.

    PubMed

    Holzapfel, Gerhard A; Niestrawska, Justyna A; Ogden, Ray W; Reinisch, Andreas J; Schriefl, Andreas J

    2015-05-01

    New experimental results on collagen fibre dispersion in human arterial layers have shown that the dispersion in the tangential plane is more significant than that out of plane. A rotationally symmetric dispersion model is not able to capture this distinction. For this reason, we introduce a new non-symmetric dispersion model, based on the bivariate von Mises distribution, which is used to construct a new structure tensor. The latter is incorporated in a strain-energy function that accommodates both the mechanical and structural features of the material, extending our rotationally symmetric dispersion model (Gasser et al. 2006 J. R. Soc. Interface 3, 15-35. (doi:10.1098/rsif.2005.0073)). We provide specific ranges for the dispersion parameters and show how previous models can be deduced as special cases. We also provide explicit expressions for the stress and elasticity tensors in the Lagrangian description that are needed for a finite-element implementation. Material and structural parameters were obtained by fitting predictions of the model to experimental data obtained from human abdominal aortic adventitia. In a finite-element example, we analyse the influence of the fibre dispersion on the homogeneous biaxial mechanical response of aortic strips, and in a final example the non-homogeneous stress distribution is obtained for circumferential and axial strips under fixed extension. It has recently become apparent that this more general model is needed for describing the mechanical behaviour of a variety of fibrous tissues. PMID:25878125

  3. Modelling non-symmetric collagen fibre dispersion in arterial walls

    PubMed Central

    Holzapfel, Gerhard A.; Niestrawska, Justyna A.; Ogden, Ray W.; Reinisch, Andreas J.; Schriefl, Andreas J.

    2015-01-01

    New experimental results on collagen fibre dispersion in human arterial layers have shown that the dispersion in the tangential plane is more significant than that out of plane. A rotationally symmetric dispersion model is not able to capture this distinction. For this reason, we introduce a new non-symmetric dispersion model, based on the bivariate von Mises distribution, which is used to construct a new structure tensor. The latter is incorporated in a strain-energy function that accommodates both the mechanical and structural features of the material, extending our rotationally symmetric dispersion model (Gasser et al. 2006 J. R. Soc. Interface 3, 15–35. (doi:10.1098/rsif.2005.0073)). We provide specific ranges for the dispersion parameters and show how previous models can be deduced as special cases. We also provide explicit expressions for the stress and elasticity tensors in the Lagrangian description that are needed for a finite-element implementation. Material and structural parameters were obtained by fitting predictions of the model to experimental data obtained from human abdominal aortic adventitia. In a finite-element example, we analyse the influence of the fibre dispersion on the homogeneous biaxial mechanical response of aortic strips, and in a final example the non-homogeneous stress distribution is obtained for circumferential and axial strips under fixed extension. It has recently become apparent that this more general model is needed for describing the mechanical behaviour of a variety of fibrous tissues. PMID:25878125

  4. Are Fibre Channel SANs a Commodity?

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  5. Decreased Retinal Ganglion Cell Layer Thickness in Patients with Type 1 Diabetes

    PubMed Central

    Verbraak, Frank D.; Kok, Pauline H. B.; Garvin, Mona K.; Sonka, Milan; Lee, Kyungmoo; DeVries, J. Hans; Michels, Robert P. J.; van Velthoven, Mirjam E. J.; Schlingemann, Reinier O.; Abràmoff, Michael D.

    2010-01-01

    Purpose. To determine which retinal layers are most affected by diabetes and contribute to thinning of the inner retina and to investigate the relationship between retinal layer thickness (LT) and diabetes duration, diabetic retinopathy (DR) status, age, glycosylated hemoglobin (HbA1c), and the sex of the individual, in patients with type 1 diabetes who have no or minimal DR. Methods. Mean LT was calculated for the individual retinal layers after automated segmentation of spectral domain-optical coherence tomography scans of patients with diabetes and compared with that in control subjects. Multiple linear regression analysis was used to determine the relationship between LT and HbA1c, age, sex, diabetes duration, and DR status. Results. In patients with minimal DR, the mean ganglion cell layer (GCL) in the pericentral area was 5.1 μm thinner (95% confidence interval [CI], 1.1–9.1 μm), and in the peripheral macula, the mean retinal nerve fiber layer (RNFL) was 3.7 μm thinner (95% CI, 1.3–6.1 μm) than in the control subjects. There was a significant linear correlation (R = 0.53, P < 0.01) between GCL thickness and diabetes duration in the pooled group of patients. Multiple linear regression analysis (R = 0.62, P < 0.01) showed that DR status was the most important explanatory variable. Conclusions. This study demonstrates GCL thinning in the pericentral area and corresponding loss of RNFL thickness in the peripheral macula in patients with type 1 diabetes and no or minimal DR compared with control subjects. These results support the concept that diabetes has an early neurodegenerative effect on the retina, which occurs even though the vascular component of DR is minimal. PMID:20130282

  6. 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.

  7. Crystalline silicon core fibres from aluminium core preforms.

    PubMed

    Hou, Chong; Jia, Xiaoting; Wei, Lei; Tan, Swee-Ching; Zhao, Xin; Joannopoulos, John D; Fink, Yoel

    2015-01-01

    Traditional fibre-optic drawing involves a thermally mediated geometric scaling where both the fibre materials and their relative positions are identical to those found in the fibre preform. To date, all thermally drawn fibres are limited to the preform composition and geometry. Here, we fabricate a metre-long crystalline silicon-core, silica-cladded fibre from a preform that does not contain any elemental silicon. An aluminium rod is inserted into a macroscopic silica tube and then thermally drawn. The aluminium atoms initially in the core reduce the silica, to produce silicon atoms and aluminium oxide molecules. The silicon atoms diffuse into the core, forming a large phase-separated molten silicon domain that is drawn into the crystalline silicon core fibre. The ability to produce crystalline silicon core fibre out of inexpensive aluminium and silica could pave the way for a simple and scalable method of incorporating silicon-based electronics and photonics into fibres. PMID:25697119

  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 fibre optic gyroscope, conventionally taken to date from the first experimental demonstration by V Vali and R W Shorthill (1976 'Fibre ring interferometer' Appl. Opt. 15 1099-100). It is an indication of the health of the community that the successful maturity of some applications is complemented by the new technologies that will be the basis of the future development of the field, and here the content of this special issue is an interesting indication of likely areas of growth. Essentially all current fibre optic systems are based on solid, doped fused silica fibres, which are the basis of the world's telecommunications industry. However, over the last decade an exciting development has been micro-structured fibres, whose waveguiding properties owe as much to the structure of the fibre as to the materials from which they are made. The significance for sensing applications is considerable, with opportunities to achieve properties for dispersion, environmental sensitivity, wavelength range and power-handling quite different from the capabilities of conventional fibre. Thus it is not surprising that several of the papers in the issue (by Cordeiro, Martynkien, Bock, Wolinski, Michie, Digonnet and Kilic) are devoted to applications of such fibres—photonic crystal fibres (PCF), as they are often called. Digonnet's contribution is especially interesting, being concerned with the use of hollow-core photonic bandgap fibre to form a gyroscope, hence avoiding the many subtle non-linear optical effects that can degrade the performance of a conventional fibre gyroscope. PCF are not the only special fibres to feature in the issue: polymer fibres are of increasing interest for sensing applications (O'Keeffe, Kiesel, Kalli and Ashley), not least for their ability to withstand high levels of strain. In-fibre gratings continue to be a very important area in the field, and are well represented in the issue (Ni, González-Segura, Chen, Falate, Kamikawachi, Wang and Correia). We hope that this special issue helps to further developments in the field of optical fibre sensors and we would like to thank all the contributing authors and reviewers for making this special issue possible. We would also like to thank the staff at IOP Publishing for their support and in ensuring timely publication. OFS-19 will be held in Perth, Australia, on 14-18 April 2008, with the intention of publishing a further special issue next year.

  9. Theoretical aspects of fibre laser cutting

    NASA Astrophysics Data System (ADS)

    Mahrle, A.; Beyer, E.

    2009-09-01

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

  10. Nanostructured fibre tip for trapping of nanoparticles

    NASA Astrophysics Data System (ADS)

    Tinguely, Jean-Claude; Ding, Ming; Brambilla, Gilberto; Hohenau, Andreas; Krenn, Joachim R.; Hellesø, Olav G.

    2014-02-01

    We propose to optically trap nanoparticles utilizing a single nanostructured glass-fiber tip. 3D translation of optically trapped nanoparticles - nano tweezers - presents vast application possibilities and has not yet been shown. The input end of the fibre probe is a standard fibre, providing easy coupling to a light source. The output end is tapered down and covered with gold, with a nanoaperture fabricated on the tip. The nanoaperture provides the strong field gradient necessary for trapping of nanoparticles. We discuss probe geometries supported by numerical simulations. The fabrication procedure for the fibre probe, using a focused ion beam, is described. A set-up for the experiments has been made and preliminary trapping results are presented.

  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. Fibre in the prevention and management of chronic disease.

    PubMed

    Potter, J D

    1982-04-01

    Some of the evidence of the role of dietary fibre in the prevention and treatment of disease is reviewed and the heterogeneous nature of fibre is considered. The relationships between various fibre fractions and colonic disorders, including cancer, diabetes mellitus, hypercholesterolaemia and obesity are discussed. It is concluded that an increase of dietary fibre constituents is only one part of a programme of dietary modification relevant to chronic diseases of a Western industrialised society. PMID:6287986

  13. Classification of Wood Pulp Fibre Cross-Sectional Shapes

    NASA Astrophysics Data System (ADS)

    Yamakawa, Asuka; Chinga-Carrasco, Gary

    This work presents a comparison of two statistical approaches for automatic classification of fibre shapes, i.e. Canonical Discriminant Analysis (CDA) and Mahalanobis Discriminant Analysis (MLDA). The discriminant analyses were applied to identify and classify several fibre cross-sectional shapes, including e.g. intact, collapsed, touching and fibrillated fibres. The discriminant analyses perform differently, giving clear indications of their suitability for classifying a given group of fibre elements. Compared to CDA, MLDA was more reliable and relatively stable.

  14. Highly Strong and Elastic Graphene Fibres Prepared from Universal Graphene Oxide Precursors

    PubMed Central

    Huang, Guoji; Hou, Chengyi; Shao, Yuanlong; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang; Zhu, Meifang

    2014-01-01

    Graphene fibres are continuously prepared from universal graphene oxide precursors by a novel hydrogel-assisted spinning method. With assistance of a rolling process, meters of ribbon-like GFs, or GRs with improved conductivity, tensile strength, and a long-range ordered compact layer structure are successfully obtained. Furthermore, we refined our spinning process to obtained elastic GRs with a mixing microstructure and exceptional elasticity, which may provide a platform for electronic skins and wearable electronics, sensors, and energy devices. PMID:24576869

  15. The response of SiC fibres to vacuum plasma spraying and vacuum hot pressing during the fabrication of titanium matrix composites

    PubMed

    Baker; Grant; Jenkins

    1999-11-01

    Vacuum plasma spraying (VPS) and vacuum hot pressing (VHP) have been used to fabricate Ti-6Al-4V matrix composite material reinforced longitudinally with DERA Sigma C coated SiC 1140+ fibres. VPS of Ti-6Al-4V onto Sigma 1140+ SiC fibres caused no fibre/matrix interfacial reaction. During VHP a fibre/matrix reaction occurred, producing a mixture of fine (< 50 nm) TiCx (x fibre coating and coarse-grained (0.3-0.5 &mgr;m) equiaxed TiCx adjacent to the Ti matrix. A decrease in C concentration with increasing distance from the C coating is proposed, and is consistent with the evidence presented. A similar thickness and morphology of reaction product arose from conventional foil-fibre foil processing, but the matrix coated fibre/hot isostatic pressing process led to a slightly thicker reaction layer. The TiCx reaction product acted as a diffusion barrier, inhibiting further reaction more effectively than in experiments on earlier SiC fibres having a C coating. Surface damage was shown to be a factor in lowering 1140+ SiC fibre failure stress. Surface damage to 1140+ fibres resulted from both VPS and VHP, the former causing a slight reduction in mean ultimate tensile strength (UTS), and a large reduction in the bend strain to failure Weibull modulus. This damage was caused by both fibre winding and by deposition of metal during VPS, giving rise to coating flaws, and is not in itself considered to be a major problem. Surface damage increased after VHP, reducing the mean UTS and tensile Weibull modulus, and the mean bend strain to failure. This damage arose from bending and flattening of the rough monotapes, and from the fibre/matrix reaction caused by thermal exposure. The level of damage to 1140+ SiC fibre from VHP was reduced by modification of the process path. Increasing the VHP temperature and lowering the pressure ramp rate reduced fibre damage sufficiently to enable a macroscopic composite UTS of 95% of the theoretical maximum to be achieved. PMID:10540269

  16. Use of silver nanowires to determine thresholds for fibre length-dependent pulmonary inflammation and inhibition of macrophage migration in vitro

    PubMed Central

    2012-01-01

    Background The objective of this study was to examine the threshold fibre length for the onset of pulmonary inflammation after aspiration exposure in mice to four different lengths of silver nanowires (AgNW). We further examined the effect of fibre length on macrophage locomotion in an in vitro wound healing assay. We hypothesised that exposure to longer fibres causes both increased inflammation and restricted mobility leading to impaired clearance of long fibres from the lower respiratory tract to the mucociliary escalator in vivo. Methods Nine week old female C57BL/6 strain mice were exposed to AgNW and controls via pharyngeal aspiration. The dose used in this study was equalised to fibre number and based on 50 μg/ mouse for AgNW14. To examine macrophage migration in vitro a wound healing assay was used. An artificial wound was created in a confluent layer of bone marrow derived macrophages by scraping with a pipette tip and the number of cells migrating into the wound was monitored microscopically. The dose was equalised for fibre number and based on 2.5 μg/cm2 for AgNW14. Results Aspiration of AgNW resulted in a length dependent inflammatory response in the lungs with threshold at a fibre length of 14 μm. Shorter fibres including 3, 5 and 10 μm elicited no significant inflammation. Macrophage locomotion was also restricted in a length dependent manner whereby AgNW in the length of ≥5 μm resulted in impaired motility in the wound closure assay. Conclusion We demonstrated a 14 μm cut-off length for fibre-induced pulmonary inflammation after aspiration exposure and an in vitro threshold for inhibition of macrophage locomotion of 5 μm. We previously reported a threshold length of 5 μm for fibre-induced pleural inflammation. This difference in pulmonary and pleural fibre- induced inflammation may be explained by differences in clearance mechanism of deposited fibres from the airspaces compared to the pleural space. Inhibition of macrophage migration at long fibre lengths could account for their well-documented long term retention in the lungs compared to short fibres. Knowledge of the threshold length for acute pulmonary inflammation contributes to hazard identification of nanofibres. PMID:23199075

  17. Diagnostic Ability of Macular Ganglion Cell Inner Plexiform Layer Measurements in Glaucoma Using Swept Source and Spectral Domain Optical Coherence Tomography

    PubMed Central

    Yang, Zhiyong; Tatham, Andrew J.; Weinreb, Robert N.; Medeiros, Felipe A.; Liu, Ting; Zangwill, Linda M.

    2015-01-01

    Purpose To evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements. Methods The study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes. Results Mean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements. Conclusion Assessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection. PMID:25978420

  18. Effect of dietary fibre on nitrogen retention and fibre associated threonine losses in growing pigs.

    PubMed

    Blank, Britta; Schlecht, Eva; Susenbeth, Andreas

    2012-04-01

    Apart from being an energy source, dietary fibre is also discussed to act as anti-nutritional factor reducing apparent precaecal protein and amino acid (AA) digestibility due to reduced absorption or increased endogenous secretion or both. However, the amounts of protein and AA of endogenous origin determined at the terminal ileum in cannulated animals do not represent the total losses associated with endogenous secretion. A high proportion of secreted protein is reabsorbed and does not reach the terminal ileum, and losses occur during synthesis of endogenous protein. Therefore, the present study used an alternative indirect approach, taking the reduction of nitrogen (N) retention in a threonine (Thr) limited diet as a sensitive indicator for fibre-associated Thr losses. Two experiments were conducted with 12 castrated male pigs each between 37 and 75 kg body weight to measure the effect of the intake of Thr and 150 and 300 g/d fibre from wheat bran (Exp. 1), or 150 g/d fibre from rape seed, cassava leaves, and cassava root peels, respectively (Exp. 2), on N retention. During two (Exp. 1) and three (Exp. 2) balance periods the animals were subjected to the dietary treatments according to a cross-over design. All animals received 1350 g/d of a wheat-soybean-based diet supplemented with free AA to ensure Thr being the first-limiting AA. To determine the effect of Thr on N retention, intake of the basal diet was reduced to 1150 g/d and supplemented with corn starch to reach equal energy intake and an unchanged AA pattern. With increasing BW additional starch was added to all diets to ensure a constant energy intake of 1.25 MJ ME/kg BW(0.75). Since the fibre sources contained small amounts of Thr, N retentions were corrected for precaecal digestible Thr intake originating from the fibre sources according to the Thr effect on N retention as determined in experiment 1. Corrected N retentions were affected by fibre level (p = 0.007) and source (p < 0.001). Fibre-associated Thr losses amounted to 3.3, 3.2, 1.2, and 1.1 g/kg fibre from wheat bran, rapeseed, cassava leaf, and cassava root peel, respectively. It is concluded that Thr losses per gram of dietary fibre depend on the fibre source and that fibre concentration and source in pig diets should be considered as a factor affecting Thr requirement. PMID:22641922

  19. Fibre-based imaging: new challenges

    NASA Astrophysics Data System (ADS)

    Plöschner, Martin; Straka, Branislav; Dholakia, Kishan; Čižmár, TomáÅ.¡

    2015-03-01

    A novel minimally invasive micro-endoscopes utilizing disordered light within a standard multimode optical fibre have been introduced recently. The two most important limitations of this exciting technology are (i) the lack of bending flexibility (transformation matrix is only valid as long as the fibre remains stationary) and (ii) high demands on computational power, making the performance of such systems slow. Here we discuss possible routes to address the later one: We introduce a GPU toolbox to make this powerful technique faster and more accessible to bio-medical researchers.

  20. Fibre Laser Texturing for Surface Functionalization

    NASA Astrophysics Data System (ADS)

    Demir, A. G.; Maressa, P.; Previtali, B.

    Textured surfaces exhibit improved properties in terms of tribological, biological, optical, or wetting performance once the texture is opportunely tailored for purpose. Fibre lasers provide a flexible solution for texturing different materials with different surface structures. In this work, the use of a Q-switched fiber laser for surface texturing for tribological, adhesion and biomedical applications is demonstrated. The required surface pattern of the application is investigated along with the processing conditions to realize the pattern. Results show the adaptability of the ns pulsed fibre laser to achieve various patterns with high productivity and industrial robustness.

  1. A highly flexible polymer fibre battery

    NASA Astrophysics Data System (ADS)

    Wang, Jiazhao; Too, Chee O.; Wallace, Gordon G.

    The development of highly flexible fibre batteries based on conducting polymers is described. The performance of cells with polypyrrole-hexafluorophosphate (PPy/PF 6) and polypyrrole-polystyrenesulfonate (PPy/PSS) is evaluated. Based on the results, fibre batteries consisting of a PPy/PF 6 cathode and a PPy/PSS anode are fabricated and tested in an electrolyte of 1 M LiPF 6 in a mixture of ethylene carbonate and dimethyl carbonate. Capacities in the order of 10 mAh g -1 over 30 cycles were observed.

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

    PubMed Central

    Smith, Caren E.; Tucker, Katherine L.

    2011-01-01

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

  3. [INVITED] Developments in optical fibre sensors for industrial applications

    NASA Astrophysics Data System (ADS)

    Alwis, L.; Sun, T.; Grattan, K. T. V.

    2016-04-01

    It can be seen that optical fibre sensing technology has huge potential to address industrial applications. They offer various advantages over the conventional electrical systems and are increasingly becoming cost effective. Different types of fibre structure and configurations can be utilised to tailor specific applications. The paper aims to highlight the developments in optical fibre sensors for industrial applications.

  4. Evaluation of Protein Immobilisation Techniques on Optical Fibre Tirf Sensor

    NASA Astrophysics Data System (ADS)

    Tedeschi, L.; Domenici, C.; Ahluwalia, A.; Baldini, F.; Mencaglia, A.

    2000-12-01

    The efficiency of optical immunosensors is highly dependent on the sensitivity of active protein layers anchored to the optical surface. In order to optimise the performance of the sensors, a comparative study of different immobilisation techniques of antibodies on optical surface has been carried out. In particular, experiments of different covalent immobilisation methods on planar quartz surfaces were conducted to enable a choice of the most suitable technique. The two methods resulting in higher surface densities of active sites were selected for further experiments on a fibre optic TIRF immunosensor. In both cases, the antibody coatings gave satisfactory responses to changes in fluorescent analyte concentrations for the tested range (~10-8 M). The capacity of polar organic solvents to dissociate the antigen-antibody complex and hence to regenerate the immunosensor surface has also been evaluated, indicating that DMSO can be used as a regenerating agent.

  5. Gbit/s data transmission on carbon fibres

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  6. Pectin methylesterase and pectin remodelling differ in the fibre walls of two gossypium species with very different fibre properties.

    PubMed

    Liu, Qinxiang; Talbot, Mark; Llewellyn, Danny J

    2013-01-01

    Pectin, a major component of the primary cell walls of dicot plants, is synthesized in Golgi, secreted into the wall as methylesters and subsequently de-esterified by pectin methylesterase (PME). Pectin remodelling by PMEs is known to be important in regulating cell expansion in plants, but has been poorly studied in cotton. In this study, genome-wide analysis showed that PMEs are a large multi-gene family (81 genes) in diploid cotton (Gossypium raimondii), an expansion over the 66 in Arabidopsis and suggests the evolution of new functions in cotton. Relatively few PME genes are expressed highly in fibres based on EST abundance and the five most abundant in fibres were cloned and sequenced from two cotton species. Their significant sequence differences and their stage-specific expression in fibres within a species suggest sub-specialisation during fibre development. We determined the transcript abundance of the five fibre PMEs, total PME enzyme activity, pectin content and extent of de-methylesterification of the pectin in fibre walls of the two cotton species over the first 25-30 days of fibre growth. There was a higher transcript abundance of fibre-PMEs and a higher total PME enzyme activity in G. barbadense (Gb) than in G. hirsutum (Gh) fibres, particularly during late fibre elongation. Total pectin was high, but de-esterified pectin was low during fibre elongation (5-12 dpa) in both Gh and Gb. De-esterified pectin levels rose thereafter when total PME activity increased and this occurred earlier in Gb fibres resulting in a lower degree of esterification in Gb fibres between 17 and 22 dpa. Gb fibres are finer and longer than those of Gh, so differences in pectin remodelling during the transition to wall thickening may be an important factor in influencing final fibre diameter and length, two key quality attributes of cotton fibres. PMID:23755181

  7. Pectin Methylesterase and Pectin Remodelling Differ in the Fibre Walls of Two Gossypium Species with Very Different Fibre Properties

    PubMed Central

    Liu, Qinxiang; Talbot, Mark; Llewellyn, Danny J.

    2013-01-01

    Pectin, a major component of the primary cell walls of dicot plants, is synthesized in Golgi, secreted into the wall as methylesters and subsequently de-esterified by pectin methylesterase (PME). Pectin remodelling by PMEs is known to be important in regulating cell expansion in plants, but has been poorly studied in cotton. In this study, genome-wide analysis showed that PMEs are a large multi-gene family (81 genes) in diploid cotton (Gossypium raimondii), an expansion over the 66 in Arabidopsis and suggests the evolution of new functions in cotton. Relatively few PME genes are expressed highly in fibres based on EST abundance and the five most abundant in fibres were cloned and sequenced from two cotton species. Their significant sequence differences and their stage-specific expression in fibres within a species suggest sub-specialisation during fibre development. We determined the transcript abundance of the five fibre PMEs, total PME enzyme activity, pectin content and extent of de-methylesterification of the pectin in fibre walls of the two cotton species over the first 25–30 days of fibre growth. There was a higher transcript abundance of fibre-PMEs and a higher total PME enzyme activity in G. barbadense (Gb) than in G. hirsutum (Gh) fibres, particularly during late fibre elongation. Total pectin was high, but de-esterified pectin was low during fibre elongation (5–12 dpa) in both Gh and Gb. De-esterified pectin levels rose thereafter when total PME activity increased and this occurred earlier in Gb fibres resulting in a lower degree of esterification in Gb fibres between 17 and 22 dpa. Gb fibres are finer and longer than those of Gh, so differences in pectin remodelling during the transition to wall thickening may be an important factor in influencing final fibre diameter and length, two key quality attributes of cotton fibres. PMID:23755181

  8. Self Healing Fibre-reinforced Polymer Composites: an Overview

    NASA Astrophysics Data System (ADS)

    Bond, Ian P.; Trask, Richard S.; Williams, Hugo R.; Williams, Gareth J.

    Lightweight, high-strength, high-stiffness fibre-reinforced polymer composite materials are leading contenders as component materials to improve the efficiency and sustainability of many forms of transport. For example, their widespread use is critical to the success of advanced engineering applications, such as the Boeing 787 and Airbus A380. Such materials typically comprise complex architectures of fine fibrous reinforcement e.g. carbon or glass, dispersed within a bulk polymer matrix, e.g. epoxy. This can provide exceptionally strong, stiff, and lightweight materials which are inherently anisotropic, as the fibres are usually arranged at a multitude of predetermined angles within discrete stacked 2D layers. The direction orthogonal to the 2D layers is usually without reinforcement to avoid compromising in-plane performance, which results in a vulnerability to damage in the polymer matrix caused by out-of-plane loading, i.e. impact. Their inability to plastically deform leaves only energy absorption via damage creation. This damage often manifests itself internally within the material as intra-ply matrix cracks and inter-ply delaminations, and can thus be difficult to detect visually. Since relatively minor damage can lead to a significant reduction in strength, stiffness and stability, there has been some reticence by designers for their use in safety critical applications, and the adoption of a `no growth' approach (i.e. damage propagation from a defect constitutes failure) is now the mindset of the composites industry. This has led to excessively heavy components, shackling of innovative design, and a need for frequent inspection during service (Richardson 1996; Abrate 1998).

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

    PubMed

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

    2016-05-01

    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

  10. 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

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

    NASA Astrophysics Data System (ADS)

    Bledzki, Andrzej K.; Faruk, Omar

    2003-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Konidakis, Ioannis; Konstantaki, Maria; Pissadakis, Stavros

    2014-03-01

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

  13. Sensitivity of a fibre scattered-light interferometer to external phase perturbations in an optical fibre

    NASA Astrophysics Data System (ADS)

    Alekseev, A. E.; Gorshkov, B. G.; Potapov, V. T.

    2015-10-01

    Sensitivity of a fibre scattered-light interferometer to external phase perturbations is studied for the first time. An expression is derived for an average power of a useful signal at the interferometer output under external harmonic perturbations in a signal fibre of the interferometer. It is shown that the maximum sensitivity of the scattered-light interferometer depends on the dispersion of the interferogram intensity. An average signal-to-noise ratio is determined theoretically and experimentally at the output of the interferometer at different amplitudes of external perturbations. Using the measured dependences of the signal-to-noise ratio, the threshold sensitivity of the fibre scattered-light interferometer to external phase perturbations is found. The results obtained can be used to optimise characteristics of optical time-domain reflectometers and to design individual phase-sensitive fibre-optic sensors.

  14. Influence of Fibre Orientation on Friction and Sliding Wear Behaviour of Jute Fibre Reinforced Polyester Composite

    NASA Astrophysics Data System (ADS)

    Dwivedi, U. K.; Chand, Navin

    2009-04-01

    Jute fibre reinforced polyester composites were developed and characterized for friction and sliding wear properties. Effect of fibre orientation and applied load on tribological behaviour of jute fibre reinforced polyester composites were determined. It is found that wear resistance was maximum in TT sample, where fibres were normal to sliding direction. Wear rate under sliding mode follows this trend; WTT < WLT

  15. FASEP ultra-automated analysis of fibre length distribution in glass-fibre-reinforced products

    NASA Astrophysics Data System (ADS)

    Hartwich, Mark R.; Hhn, 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.

  16. FRD and scrambling properties of recent non-circular fibres

    NASA Astrophysics Data System (ADS)

    Avila, Gerardo

    2012-09-01

    Optical fibres with octagonal, square and rectangular core shapes have been proposed as alternative to the circular fibres to link the telescopes to spectrographs in order to increase the accuracy of radial velocity measurements. Theoretically they offer better scrambling properties than their circular counterparts. First commercial octagonal fibres provided good near field scrambling gains. Unfortunately the far field scrambling did not show important figures. This article shows test results on new fibres from CeramOptec. The measurements show substantial improvements of the far field scrambling gains. In addition, evaluation of their focal ratio degradation (FRD) shows much better performances than previous fibres.

  17. Anthracene Crystals Doped with Dibenzoterrylene Molecules in Optical Fibre Microcavities

    NASA Astrophysics Data System (ADS)

    Major, K. D.; Hinds, E. A.; Clark, Alex S.; Polliseni, C.; Grandi, S.; Lien, Y. H.; Quantum Nanophotonics, CentreCold Matter, Quantum Optics; Laser Science Group Team

    2015-03-01

    Dibenzoterrylene molecules placed in an anthracene crystal are stable emitters resistant to photobleaching and with a high quantum efficiency and low phonon coupling. Placing dibenzoterrylene doped anthracene crystals within a optical fibre microcavity can lead to enhanced emission of radiation into the modes of the optical cavity. The optical fibre microcavities are already coupled to a optical fibres and by selecting the correct cavity mirror reflectivities, the emission can be preferentially directed down the optical fibres. Excitation of the dibenzoterrylene molecules leads to the emission of single photons and can then be used as a micron-scale fibre coupled single photon source.

  18. Post-microbuckling of fibre bridging kink bands under compression

    NASA Astrophysics Data System (ADS)

    Yueguang, Wei; Wei, Yang

    1993-02-01

    Surface originated kink bands consist of an important failure mode for fibre-reinforced composites under compression. The mechanical behavior of the fibre bridging kink bands is explored herein in the context of the post-microbuckling theory. Expressions of bridging force are obtained for the entire postbuckling process of the fibres exhibiting weak or strong hardening. The postbuckling formulation of the fibres is applied to yield the toughness increment due to the advancing kink bands, and consequently leads to a quantitative prediction on the overall compressive stress strain curves of the fibre-reinforced composites.

  19. The tensile properties of single sugar palm (Arenga pinnata) fibre

    NASA Astrophysics Data System (ADS)

    Bachtiar, D.; Sapuan, S. M.; Zainudin, E. S.; Khalina, A.; Dahlan, K. Z. M.

    2010-05-01

    This paper presents a brief description and characterization of the sugar palm fibres, still rare in the scientific community, compared to other natural fibres employed in polymeric composites. Sugar palm fibres are cellulose-based fibres extracted from the Arenga pinnata plant. The characterization consists of tensile test and the morphological examination. The average tensile properties results of fibres such as Young's modulus is equal to 3.69 GPa, tensile strength is equal to 190.29 MPa, and strain at failure is equal to 19.6%.

  20. 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.

  1. WEAVE MOS fibre bundle test plan

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  2. The zeta potential of mineral fibres.

    PubMed

    Pollastri, Simone; Gualtieri, Alessandro F; Gualtieri, Magdalena Lassinantti; Hanuskova, Miriam; Cavallo, Alessandro; Gaudino, Giovanni

    2014-07-15

    For the first time, the zeta (ξ) potential of pathogenic mineral fibres (chrysotiles, amphiboles and erionite) was systematically investigated to shed light on the relationship between surface reactivity and fibre pathogenicity. A general model explaining the zeta potential of chrysotile, amphiboles and erionite has been postulated. In double distilled water, chrysotiles showed positive values while crocidolite and erionite showed negative values. In contact with organic solutions, all fibres exhibited negative values of zeta potential. The decrease of the surface potential is deemed to be a defensive chemical response of the macrophage cells to minimize hemolytic damage. Negatively charged surfaces favour the binding of collagen and redox activated Fe-rich proteins, to form the so-called asbestos bodies and prompt the formation of HO via the reaction with peroxide (H2O2+e(-)→HO+HO(-)). An additional mechanism accounting for higher carcinogenicity is possibly related to the Ca(2+) sequestration by the fibres with surface negative potential, impairing the mitochondrial apoptotic pathway. It was also found that with a negative zeta potential, the attractive forces prevailed over repulsions and favoured processes such as agglomeration responsible of a tumorigenic chronic inflammation. PMID:24929786

  3. Review Of Fibre Optic Gas Sensors

    NASA Astrophysics Data System (ADS)

    Dakin, J. P.

    1989-02-01

    This short review presents an outline of recent work on optical-fibre-based sensors for the detection of gases. Emphasis will be placed on aspects related to the detection of flammable gases in general and of methane in particular, in view of the importance of explosion hazards in many industrial workplaces, particularly from naturally occuring methane gas.

  4. 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.

  5. 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.

  6. Dietary fibre, glycaemic response, and diabetes.

    PubMed

    Brennan, Charles S

    2005-06-01

    The much publicised global trend in rising levels of obesity and diabetes has refuelled interest in the dietary intake of the macronutrients (fat, protein, and carbohydrates) necessary to maintain the state of normalcy (good health) of an individual. Both scientific and public attention have focused on the dietary mediation of chronic health syndromes, either through use of dietary supplements, or a review of the whole diet situation. Dietary supplements have been used extensively both as pharmacological supplements, food ingredients, in processed foods to aid weight control, and the regulation of glucose control for diabetic patients. Particular interest has focused on the use of dietary fibres, especially soluble dietary fibres (such as guar gum, locust bean gum, and psyllium fibres), resistant starch, and slowly digestible carbohydrates. These have been shown to alter food structure, texture, and viscosity, and hence the rate of starch degradation during digestion. Research has also illustrated an association between the rate of carbohydrate degradation during digestion, and the regulation of postprandial blood sugar and insulin levels. The current paper explores the potential use of dietary fibres in the treatment of obesity and diabetes. PMID:15926145

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

    PubMed

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

    2016-04-25

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

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

    PubMed Central

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

    1996-01-01

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

  9. 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).

  10. Effect of TiN nano-coating on the interface microstructure of carbon fibres-AZ91 alloy composite

    NASA Astrophysics Data System (ADS)

    Olszówka-Myalska, A.; Botor-Probierz, A.

    2012-03-01

    Magnesium matrix composites reinforced with carbon fibres, Cf, without surface modification and coated with TiN nanolayer, (Cf)TiN, were investigated. AZ91 magnesium alloy and carbon fibres of T300B (Toray) PAN type were chosen as components. In the experiment infiltration in vacuum as a method of component consolidation and chemical vapour deposition (CVD) for carbon fibres surface modification were applied. Structural investigations were performed in the Hitachi 3200S field-emission scanning electron microscope (FE-SEM) and on a FEI Tecnai G2 FEG high-resolution transmission electron microscope (TEM) equipped with energy-dispersive X-ray spectrometer (EDS) and high angle annular dark field (HAADF) detectors. SEM observations revealed that at the interface of AZ91-Cf composite destructive phases were formed. An application of TiN nano-coating as a surface modification ensured proper wettability of carbon fibres by liquid metal and protection against the destructive products formation. The microstructure of AZ91-(Cf)TiN composite interface was multilayered. TEM investigation revealed a continuous layer of mixed alumina and magnesia just at the carbon surface, followed by a layer with a dominant concentration of titanium, enriched with Al, O, Mg and C and subsequently a layer of nano-sized Al12Mg17 crystals in the magnesium matrix. Therefore, an applied TiN nano-coating can be classified as an active barrier in AZ91-Cf system.

  11. 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

  12. 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.

  13. Optical fibre-based detection of DNA hybridization.

    PubMed

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

    2009-04-01

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

  14. Developing new active optical fibres with broadband emissions

    NASA Astrophysics Data System (ADS)

    Peng, Gang-Ding; Zhang, Jianzhong; Luo, Yanhua; Sathi, Zinat; Zareanborji, Amirhassan; Canning, John

    2013-09-01

    Broadband emission sources such as super luminous diodes and rare earth doped fibre for ASE sources have wide applications in optical fibre measurement and sensing systems. Recent intensive research has shown broadband luminescence in the range of 1100 to 1500 nm, across O, E and S bands of the telecommunications window from glasses or materials with Bi-doping and Bi/Er codoping. The broadband luminescence of active optical fibres in this wavelength range is particularly interesting for fibre amplifiers, lasers and ASE sources for optical communication and sensing applications. Here we report our recent development of Bi/Er/Al codoped phosphogermanosilicate optical fibre with ultra-broadband luminescence between 1000 to 1570 nm, covering O-, E-, S-, C-, and L-bands, when pumped by 532, 808, or 980 nm lasers. The new material composition of this optical fibres are potentially useful as gain media for ultrabroadband ASE sources, tunable fibre lasers or amplifiers.

  15. Analysis on fibre orientation of thermal bonded nonwoven

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  16. Physiological effects of FMRFamide-related peptides and classical transmitters on dispersed muscle fibres of the turbellarian, Procerodes littoralis.

    PubMed

    Moneypenny, C G; Kreshchenko, N; Moffett, C L; Halton, D W; Day, T A; Maule, A G

    2001-04-01

    The physiological effects of selected classical transmitters and FMRFamide-related peptides (FaRPs) on dispersed muscle fibres from the marine turbellarian, Procerodes littoralis have been examined. Confocal scanning laser microscopy coupled with fluorescein isothiocyanate (FITC) or tetramethylrhodamine (TRITC)-labelled phalloidin revealed a highly developed body wall muscle system with circular, longitudinal and diagonal layers of muscle fibres. Dispersed muscle fibres contracted when depolarized by exposure to extracellular media with elevated K+ (15-100 mM) in a concentration-dependent manner, with a maximal response of 87% achieved at > or = 75 mM. 5-Hydroxytryptamine (5-HT) induced concentration-dependent muscle contraction between 0.01 and 1000 microM, with 10 microM producing a near maximal contraction response of 75%. Acetylcholine (ACh) had less pronounced excitatory effects (0.01-1000 microM), inducing contraction of only 32% of the fibres at 100 microM. The flatworm FMRFamide-related peptides (FaRPs), GYIRFamide, YIRFamide and GNFFRFamide each had concentration-dependent myocontractile effects, indicating the occurrence of at least 1 FaRP receptor on P. littoralis muscle fibres. At 10 microM peptide, GNFFRFamide induced contractions in < 40% of the muscle fibres examined, whereas YIRFamide and GYIRFamide induced contraction in 70 and 75% of muscle fibres, respectively. The order of potency of the peptides was: GYIRFamide > YIRFamide > GNFFRFamide. Pre-incubation of the muscle fibres in 5 microM 5-HT significantly reduced the responses to GYIRFamide, YIRFamide and 5-HT, while the responses to high K+ remained unaltered. Muscle fibres pre-incubated in GYIRFamide (0.1 microM) were also less responsive to 5-HT but not to ACh and high-K+. The GYIRFamide analogue, GYIRDFamide, did not induce muscle contraction (0.01-100 microM) per se, but when co-applied with the myoactive peptides GYIRFamide, YIRFamide or GNFFRFamide, it significantly blocked their ability to elicit contractions. This suggests that the peptides tested may act via a common muscle-based neuropeptide receptor. GYIRDFamide did not alter the contractile effects of high K+, 5-HT or ACh. Collectively, these results indicate that FaRPs, 5-HT and ACh all have the potential to cause muscle contraction in flatworms and that 5-HT and FaRPs alter muscle sensitivity to each other, but do not influence the ability of flatworm muscle fibres to contract. PMID:11315178

  17. U-shaped evanescent wave optical fibre sensor based on a porphyrin anchored nanoassembled thin film for high sensitivity ammonia detection

    NASA Astrophysics Data System (ADS)

    Korposh, S.; Okuda, H.; Wang, T.; James, S. W.; Lee, S.-W.

    2015-07-01

    A layer-by-layer (LbL) approach was used for the deposition of coatings with a nano-meter thickness onto a multimode optical fibre that was bent into a U-shape with the aim of demonstrating a fibre-optic ammonia sensor. The film was composed of alternate layers of tetrakis(4-sulfophenyl)porphine, TSPP, and poly(diallyldimethylammonium chloride), PDDA, deposited using the LbL electrostatic self-assembly process. Exposure of the assembled film to ammonia induced a change in its absorption spectrum, which could be observed in the transmission spectrum of the coated U-shaped optical fibre. The sensor showed a linear sensitivity (77.7 mV/ppm) to ammonia in the concentration range 1-100 ppm.

  18. Fabrication of a submicron-channel organic field-effect transistor using a controllable electrospun single fibre as a shadow mask

    NASA Astrophysics Data System (ADS)

    Ishii, Y.; Sakai, H.; Murata, H.

    2011-05-01

    We demonstrate a simple and versatile method for the fabrication of a submicron channel for an organic field-effect transistor (OFET) using a single electrospun fibre as a shadow mask. A single electrospun fibre is produced by an alternative switching electrospinning method and is stretched 2.5-fold. The average diameter of the stretched fibres is 302 nm. The stretched fibre is placed on ultrathin dielectric layers of aluminium oxide and a self-assembled monolayer (SAM). During electrode deposition the fibre acts as a very small shadow mask. After removing the fibre, electrodes with very narrow gaps of around 350 nm and with high uniformity are easily obtained. We fabricate an OFET by depositing pentacene as an active layer onto the electrodes. The OFET is operable at low voltages, with a threshold voltage of - 1.1 V and a subthreshold swing of 0.27 V decade - 1, values which are one order of magnitude lower than those obtained with a channel length of 75 µm.

  19. Patient Characteristics Associated with Artifacts in Spectralis Optical Coherence Tomography Imaging of the Retinal Nerve Fiber Layer in Glaucoma

    PubMed Central

    Liu, Yingna; Simavli, Huseyin; Que, Christian; Rizzo, Jennifer L.; Tsikata, Edem; Maurer, Rie; Chen, Teresa

    2015-01-01

    Purpose To determine patient factors and eye conditions associated with artifacts in Spectralis optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) scans. Design Retrospective cross-sectional study. Methods The prevalence of twelve artifact types were described in this review of 2313 eye scans from 1188 patients who underwent a complete eye exam with Spectralis OCT scanning during the period of September 2009 to July 2013. Generalized estimating equations model was utilized to analyze associations between increased artifact prevalence and 10 patient characteristics, which included age, sex, race, visual acuity, refractive error, astigmatism, cataract status, glaucoma staging, visual field reliability, and glaucoma diagnosis. Results A total of 1070 or 46.3% of the 2313 eye scans had at least one artifact. De-centration error was the most common artifact (27.8%), followed by posterior vitreous detachment artifacts (14.4%). Visual acuity of less than 20/40 (p<0.0001), presence of moderate to severe cataracts (p<0.0001), advanced stage of glaucoma (p<0.0001), and a diagnosis of open angle glaucoma (p=0.0003) were associated with increased prevalence of artifacts. Conclusions Clinicians should first assess scans for artifacts before making therapeutic decisions based on RNFL thickness measurements. PMID:25498118

  20. Detecting the Progression of Eye Disease: CUSUM Charts for Assessing the Visual Field and Retinal Nerve Fiber Layer Thickness

    PubMed Central

    Ledolter, Johannes; Kardon, Randy

    2013-01-01

    Purpose The cumulative sum (CUSUM) is proposed and tested in a group of glaucoma patients and healthy subjects as a method for monitoring disease progression and for identifying clinically significant step changes in visual structure or function. Methods The CUSUM procedure is the recommended method for the timely detection of small step changes in manufacturing process control. The CUSUM procedure is discussed and compared with traditional approaches for the detection of change in the status of the visual system over time. The CUSUM approach is used to monitor over time visual field (VF) mean deviations and optical coherence tomography (OCT) measurements of retinal nerve fiber layer (RNFL) thickness in 53 healthy subjects and 103 patients with glaucoma. Results The CUSUM method detects VF progression for 35 of the 103 glaucoma patients (34.0%), and OCT RNFL reductions for 20 of the 103 glaucoma patients (19.4%). Conclusions The CUSUM method is effective in detecting small level changes. This method can be used to monitor the progression of disease and it benefits the clinician who must decide, on the basis of a time series of variable data, whether a change has occurred. Translational Relevance A cumulative sum chart helps the clinician decide whether a step change has taken place, and it does so as quickly as possible. This approach is particularly effective for detecting small step changes, which very likely are unnoticed with currently used change detection approaches. PMID:24083087

  1. Ectopic release of glutamate contributes to spillover at parallel fibre synapses in the cerebellum.

    PubMed

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

    2014-04-01

    In the rat cerebellar molecular layer, spillover of glutamate between parallel fibre synapses can lead to activation of perisynaptic receptors that mediate short- and long-term plasticity. This effect is greatest when clusters of fibres are stimulated at high frequencies, suggesting that glutamate clearance mechanisms must be overwhelmed before spillover can occur. However, parallel fibres can also release transmitter directly into the extracellular space, from 'ectopic' release sites. Ectopic transmission activates AMPA receptors on the Bergmann glial cell processes that envelop parallel fibre synapses, but the possible contribution of this extrasynaptic release to intersynaptic communication has not been explored. We exploited long-term depression of ectopic transmission, and selective pharmacology, to investigate the impact of these release sites on the time course of Purkinje neuron excitatory postsynaptic currents (EPSCs). Depletion of ectopic release pools by activity-dependent long-term depression decreased EPSC decay time, revealing a 'late' current that is present when fibres are stimulated at low frequencies. This effect was enhanced when glutamate transporters were inhibited, and reduced when extracellular diffusion was impeded. Blockade of N-type Ca(2+) channels inhibited ectopic transmission to Bergmann glia and decreased EPSC decay time. Similarly, perfusion of the Ca(2+) chelator EGTA-AM into the slice progressively eliminated ectopic transmission to glia and decreased EPSC decay time with closely similar time courses. Collectively, this evidence suggests that ectopically released glutamate contributes to spillover transmission, and that ectopic release therefore degrades the spatial precision of synapses that fire infrequently, and may make them more prone to exhibit plasticity. PMID:24421351

  2. High-intensity fibre laser design for micro-machining applications

    NASA Astrophysics Data System (ADS)

    Ortiz-Neria, D. I.; Martinez-Piñón, F.; Hernandez-Escamilla, H.; Alvarez-Chavez, J. A.

    2010-11-01

    This work is focused on the design of a 250W high-intensity continuous-wave fibre optic laser with a 15μm spot size beam and a beam parameter product (BPP) of 1.8 for its use on Laser-assisted Cold Spray process (LCS) in the micro-machining areas. The metal-powder deposition process LCS, is a novel method based on Cold Spray technique (CS) assisted by laser technology. The LCS accelerates metal powders by the use of a high-pressure gas in order to achieve flash welding of particles over substrate. In LCS, the critical velocity of impact is lower with respect with CS while the powder particle is heated before the deposition by a laser beam. Furthermore, LCS does not heat the powder to achieve high temperatures as it happens in plasma processes. This property puts aside cooling problems which normally happen in sintered processes with high oxygen/nitrogen concentration levels. LCS will be used not only in deposition of thin layers. After careful design, proof of concept, experimental data, and prototype development, it should be feasible to perform micro-machining precise work with the use of the highintensity fibre laser presented in this work, and selective deposition of particles, in a similar way to the well-known Direct Metal Laser Sintering process (DMLS). The fibre laser consists on a large-mode area, Yb3+-doped, semi-diffraction limited, 25-m fibre laser cavity, operating in continuous wave regime. The fibre shows an arguably high slope-efficiency with no signs of roll-over. The measured M2 value is 1.8 and doping concentration of 15000ppm. It was made with a slight modification of the traditional MCVD technique. A full optical characterization will be presented.

  3. Intraeye retinal nerve fiber layer and macular thickness asymmetry measurements for the discrimination of primary open-angle glaucoma and normal tension glaucoma

    PubMed Central

    Khanal, Safal; Davey, Pinakin Gunvant; Racette, Lyne; Thapa, Madhu

    2015-01-01

    Purpose The aim of this study was to evaluate the diagnostic capability of intraeye retinal nerve fiber layer (RNFL) thickness and macular thickness (MT) asymmetry measurements for the discrimination of normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) using spectral domain optical coherence tomography (SD-OCT). Methods A total of 90 subjects were enrolled including 30 consecutive healthy subjects, 30 consecutive subjects with POAG, and 30 consecutive subjects with NTG. RNFL thicknesses around the optic disc as well as MT measurements were taken with circular and radial SD-OCT scans. Intraeye retinal and MT asymmetry were calculated as the absolute difference between superior and inferior hemispheres of the eye using posterior pole asymmetry analysis protocol. Analysis of variance was used for comparison and areas under the receiver operating characteristic (AROC) were obtained for different parameters among the three diagnostic groups. Results There was a significant difference in MT asymmetry for all comparison groups (normal-NTG, p < 0.05; normal-POAG, p < 0.001; and NTG-POAG, p < 0.001). Intraeye retinal nerve fiber thickness asymmetry measurements were not different between the groups (normal-NTG, p < 0.187; normal-POAG, p < 0.056; and NTG-POAG, p < 0.837). The area under ROC curves exceeded 0.800 for all the studied parameters, including the MT asymmetry except for intraeye RNFL thickness asymmetry which had the lowest AROC as well as the least sensitivity for identifying subjects with NTG from normal (AROC = 0.626, sensitivity = 30%); POAG from normal (AROC = 0.644, sensitivity = 37%) and NTG from POAG (AROC = 0.533, sensitivity = 13%). Conclusion The intraeye MT asymmetry holds significant potential as a distinguishing parameter for NTG and POAG. PMID:26652244

  4. Biological durability and oxidative potential of man-made vitreous fibres as compared to crocidolite asbestos fibres.

    PubMed

    Hippeli, S; Dornisch, K; Wiethege, T; Gillissen, A; Müller, K M; Elstner, E F

    2001-01-01

    In this study we investigated relationships between redox properties and biodurability of crocidolite asbestos fibres and three different man-made vitreous fibres (MMVF): traditional stone wool fibres (MMVF 21), glass fibres (MMVF 11) and refractory ceramic fibres (RCF). Each fibre type was incubated up to 22 weeks in four different incubation media: gamble solution (GS) pH 5.0 and pH 7.4, representing blood plasma without proteins, and surfactant-like solution (SLS) pH 5.0 and pH 7.4. During incubation time aliquots of incubation mixtures were removed and analysed in a biochemical model reaction, mimicking activated phagocytes. In addition, changes of fibre morphology and chemical composition were examined using SEM- and EDX-technology. In the presence of crocidolite asbestos fibres and MMVF 21 the formation of OH*-radicals according to the Haber-Weiss sequence could be demonstrated, whereas MMVF 11 and RCF showed no reactivity. Crocidolite asbestos fibres exhibited a significant higher activity compared with the stone wool fibres at the onset of incubation. The oxidative capacities of these fibre types were shown to depend on both specific surface area and iron content. The oxidative potentials of crocidolite asbestos fibres as well as MMVF 21 were not constant during incubation over several weeks in each incubation medium. The reactivities showed sinoidal curves including reactivities much higher than those at the onset of incubation time. These irregular changes of oxidative capacity may be explained by changes of the redox state of fibre surface-complexed iron. Furthermore our results showed clear differences between incubation of fibres in GS and SLS, respectively, indicating that phospholipids play an important part in fibre dissolution behaviour and oxidative reactivity. In conclusion we suggest, that biodurability testing procedures should not exclusively concentrate on dissolution rates of fibres. They should include fibre characteristics concerning known pathogenic mechanisms to evaluate the real toxic potential of the fibre type looking at. Secondly we suggest, that phospholipids should be constituents of incubation liquids used for standardised fibre biodurability test procedures thus representing more realistic incubation conditions. PMID:11531101

  5. 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. PMID:23887033

  6. A novel cryogenic fibre maker for continuous extrusion

    NASA Astrophysics Data System (ADS)

    Aliaga-Rossel, R.; Bayley, J.

    1997-05-01

    The results of a cryogenics fibre maker which extrudes fibres continuously are presented. The fibre maker is based on a simple concept of differential temperature. Two reservoirs are connected in cascade and are kept at different temperatures. The first reservoir is connected to an external gas line supply (the gas that will made the fibre) and is used to liquefy the gas. The second reservoir is colder that the first and the liquid that comes from the first reservoir is frozen and later is used to form the fibre. The pressure of external gas supply in the first reservoir is used to extrude the fibre. The system is cooled by a two stage closed cycle refrigerator, which uses liquid helium as a working fluid. The nozzles used to extrude the fibre are made of stainless steel capillary with diameters between 50 μm and 250 μm, with a length of 2 mm. The use of a system with two independent temperatures, permits to control the extrusion rate of the fibres and to produce the fibres continuously. Using this system, hydrogen deuterium, nitrogen and argon fibres of various diameters were extruded.

  7. Comparison of cytotoxicity of man-made vitreous fibres.

    PubMed

    Luoto, K; Holopainen, M; Sarataho, M; Savolainen, K

    1997-01-01

    The purpose of the study was to compare the cytotoxicity of man-made vitreous fibres (MMVFs): four refractory ceramic fibres (RCFs 1-4), two glasswool fibres (MMVF 10 and 11), a rockwool fibre (MMVF 21) and a slagwool fibre (MMVF 22). The ability of the fibres to induce haemolysis in sheep erythrocytes, to release lactate dehydrogenase (LDH) from rat alveolar macrophages (AM) and to increase the production of reactive oxygen metabolites (ROMs) in human polymorphonuclear leukocytes (PML) was studied. To assess the relative cytotoxicity of MMVFs, their toxicity was compared with that induced by quartz, chrysotile or titanium dioxide. MMVFs induced a modest, but dose-dependent, increase of haemolysis at doses of 0.5, 2.5 and 5.0 mg ml-1. The amount of haemolysis and LDH release induced by MMVFs was generally similar to that induced by titanium dioxide. Glasswool fibre MMVF 10 induced less LDH release from rat AM than rockwool MMVF 21 or slagwool MMVF 22 fibres, whereas glasswool fibre MMVF 11 induced less LDH release than slagwool fibre MMVF 22 (P < 0.05). All fibres also dose-dependently increased the production of ROMs at doses between 25 and 500 micrograms ml-1. The shapes of the time-courses of MMVF-induced production of ROMs suggest that the mechanisms whereby the different fibres induce ROM production may exhibit similar features. There are clear-cut differences in the potency of various MMVFs to induce cytotoxicity and oxidative burst. The present results also emphasize the importance of using several measures of toxicity when assessing the biological activity of various fibres in vitro. PMID:9072949

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

    NASA Astrophysics Data System (ADS)

    Stevens, G.; Robertson, A.

    2014-05-01

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

  9. Relationships between quantitative spinal cord MRI and retinal layers in multiple sclerosis

    PubMed Central

    Sotirchos, Elias S.; Saidha, Shiv; Whetstone, Anna; Chen, Min; Newsome, Scott D.; Zackowski, Kathy; Balcer, Laura J.; Frohman, Elliot; Prince, Jerry; Diener-West, Marie; Reich, Daniel S.

    2015-01-01

    Objective: To assess relationships between spinal cord MRI (SC-MRI) and retinal measures, and to evaluate whether these measures independently relate to clinical disability in multiple sclerosis (MS). Methods: One hundred two patients with MS and 11 healthy controls underwent 3-tesla brain and cervical SC-MRI, which included standard T1- and T2-based sequences and diffusion-tensor and magnetization-transfer imaging, and optical coherence tomography with automated segmentation. Clinical assessments included visual acuity (VA), Expanded Disability Status Scale, MS functional composite, vibration sensation threshold, and hip-flexion strength. Regions of interest circumscribing SC cross-sections at C3-4 were used to obtain cross-sectional area (CSA), fractional anisotropy (FA), perpendicular diffusivity (λ⊥), and magnetization transfer ratio. Multivariable regression assessed group differences and SC, retinal, and clinical relationships. Results: In MS, there were correlations between SC-CSA, SC-FA, SC-λ⊥, and peripapillary retinal nerve fiber layer (pRNFL) (p = 0.01, p = 0.002, p = 0.001, respectively) after adjusting for age, sex, prior optic neuritis, and brain atrophy. In multivariable clinical models, when SC-CSA, pRNFL, and brain atrophy were included simultaneously, SC-CSA and pRNFL retained independent relationships with low-contrast VA (p = 0.04, p = 0.002, respectively), high-contrast VA (p = 0.06, p = 0.008), and vibration sensation threshold (p = 0.01, p = 0.05). SC-CSA alone retained independent relationships with Expanded Disability Status Scale (p = 0.001), hip-flexion strength (p = 0.001), and MS functional composite (p = 0.004). Conclusions: In this cross-sectional study of patients with MS, correlations exist between SC-MRI and retinal layers, and both exhibit independent relationships with clinical dysfunction. These findings suggest that the SC and optic nerve reflect ongoing global pathologic processes that supplement measures of whole-brain atrophy, highlighting the importance of combining measures from unique compartments to facilitate a thorough examination of regional and global disease processes that contribute to clinical disability in MS. PMID:25609766

  10. Macroscopic assembled, ultrastrong and H2SO4-resistant fibres of polymer-grafted graphene oxide

    PubMed Central

    Zhao, Xiaoli; Xu, Zhen; Zheng, Bingna; Gao, Chao

    2013-01-01

    Nacre realizes strength and toughness through hierarchical designs with primary “brick and mortar” structures of alternative arrangement of nanoplatelets and biomacromolecules, and these have inspired the fabrication of nanocomposites for decades. However, to simultaneously solve the three critical problems of phase separation, low interfacial strength and random orientation of nanofillers for nanocomposites is a great challenge yet. Here we demonstrate that polymer-grafted graphene oxide sheets are exceptional building blocks for nanocomposites. Their liquid crystalline dispersions can be wet-spun into continuous fibres. Because of well-ordering and efficient load transfer, the composites show remarkable tensile strength (500 MPa), three to four times higher than nacre. The uniform layered microstructures and strong interlayer interactions also endow the fibres good resistance to chemicals including 98% sulfuric acid. We studied the enhancing effect of nanofillers with fraction in a whole range (0–100%), and proposed an equation to depict the relationship. PMID:24196491

  11. Influence of slip on the Plateau–Rayleigh instability on a fibre

    PubMed Central

    Haefner, Sabrina; Benzaquen, Michael; Bäumchen, Oliver; Salez, Thomas; Peters, Robert; McGraw, Joshua D.; Jacobs, Karin; Raphaël, Elie; Dalnoki-Veress, Kari

    2015-01-01

    The Plateau–Rayleigh instability of a liquid column underlies a variety of fascinating phenomena that can be observed in everyday life. In contrast to the case of a free liquid cylinder, describing the evolution of a liquid layer on a solid fibre requires consideration of the solid–liquid interface. Here we revisit the Plateau–Rayleigh instability of a liquid coating a fibre by varying the hydrodynamic boundary condition at the fibre–liquid interface, from no slip to slip. Although the wavelength is not sensitive to the solid–liquid interface, we find that the growth rate of the undulations strongly depends on the hydrodynamic boundary condition. The experiments are in excellent agreement with a new thin-film theory incorporating slip, thus providing an original, quantitative and robust tool to measure slip lengths. PMID:26068033

  12. Macroscopic assembled, ultrastrong and H2SO4-resistant fibres of polymer-grafted graphene oxide

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoli; Xu, Zhen; Zheng, Bingna; Gao, Chao

    2013-11-01

    Nacre realizes strength and toughness through hierarchical designs with primary ``brick and mortar'' structures of alternative arrangement of nanoplatelets and biomacromolecules, and these have inspired the fabrication of nanocomposites for decades. However, to simultaneously solve the three critical problems of phase separation, low interfacial strength and random orientation of nanofillers for nanocomposites is a great challenge yet. Here we demonstrate that polymer-grafted graphene oxide sheets are exceptional building blocks for nanocomposites. Their liquid crystalline dispersions can be wet-spun into continuous fibres. Because of well-ordering and efficient load transfer, the composites show remarkable tensile strength (500 MPa), three to four times higher than nacre. The uniform layered microstructures and strong interlayer interactions also endow the fibres good resistance to chemicals including 98% sulfuric acid. We studied the enhancing effect of nanofillers with fraction in a whole range (0-100%), and proposed an equation to depict the relationship.

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

    SciTech Connect

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

    2005-05-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  15. 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)

  16. 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

  17. 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.

  18. Fibre Steering Of Composite Space Panels

    NASA Astrophysics Data System (ADS)

    Paalberends, Wilem Jelle; Bakker, Robbert

    2012-07-01

    Airborne invested in an automated tape placement system and it is developing tow steering capabilities for this system. Future use of the tow steering capabilities will make better use of the high orthogonal nature of composite materials. The increase in effectiveness can be used to design composites structures for specific uses with lower mass or higher specifications than conventional designs. Airborne already manufactures composite sandwich panel structures for satellite arrays therefore a typical solar panel was used as a case study in a project together with the TU-Delft[1]. The goal was to design and manufacture a fibre steered sandwich panel with a higher critical eigenfrequency for the same mass. Improvements as much as 43.6% are found and the design methodology is verified by manufacturing and testing of a conventional and fibre steered panel.

  19. Contractile properties and protein isoforms of single fibres from the chicken pectoralis red strip muscle.

    PubMed Central

    Reiser, P J; Greaser, M L; Moss, R L

    1996-01-01

    1. The contractile properties of single muscle fibres of the red strip region of adult chicken pectoralis major (PM) muscle, some of which are known to express an embryonic isoform of myosin heavy chain (MHC), were determined and compared with the properties of the fast white fibres of the PM and the slow tonic fibres of the anterior latissimus dorsi (ALD) muscle. 2. The red strip fibres could be classified into two groups, fast and slow. The mean velocity of unloaded shortening (Vmax) in fast red strip fibres was approximately half the Vmax of fast white fibres. Vmax of slow red strip fibres was less than 20% of the value for fast red strip fibres and was not different from Vmax of ALD fibres. 3. The tension-generating ability, i.e. the maximal isometric tension/fibre cross-sectional area (P0/CSA), was the same in fast red strip fibres and fast white fibres. P0/CSA was approximately 30% lower in slow red strip fibres compared with fast red strip fibres but was 70% greater in slow red strip fibres compared with ALD fibres. 4. The tension-pCa relation of fast red strip fibres was shifted to lower pCa values, indicating a lower calcium sensitivity compared with fast white fibres, and this difference was associated with a difference in troponin T isoform composition. The tension-pCa relation of slow red strip fibres was not different from that in ALD fibres. 5. The difference in Vmax between fast red strip fibres and fast white fibres was associated with different MHC compositions of these fibres. 6. The myofibrillar protein isoform composition of slow red strip fibres was identical to that of the slow tonic fibres of ALD muscle and these two groups of fibres had very similar contractile properties. Images Figure 4 Figure 5 Figure 6 PMID:8782116

  20. Fibre optic sensors for mine hazard detection

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

  1. Fibre tracking: probabilistic approach and preliminary results

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

  2. 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

  3. 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

  4. Chronological ageing of human hair keratin fibres.

    PubMed

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

    2010-12-01

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

  5. First-principles studies of peptide fibres

    NASA Astrophysics Data System (ADS)

    Zheng, Z.; Liu, N.; Lu, Ning

    2013-02-01

    The electronic properties of a single Gly, Cys and Trp peptide fibres (PFs), in separated and closely spaced forms, are studied with ab initio calculations. By decreasing the distance between separated Gly and Cys PFs, respectively, the energy gap between highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of separated fibres tends to narrow down and we investigate the smallest HOMO-LUMO gap for the separated Trp PFs of 3.36 eV, without any electronic states between the gap. The band gap of closely spaced Trp and Gly PFs is predicted to be 0.26 and 3.31 eV, indicating an organic semiconductor character. Series of deep electronic bands (DEBs) in the band gap are found for the closely spaced Cys PFs, helping recombination in the system with the largest DEB gap of 2.26 eV. The electronic properties of all three fibres are mainly decided by the peptide bonds and the functional side chains. The results show that design of the side chains on the PF backbone is a promising method for the application of organic semiconductor and biological compatible devices.

  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 m 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. Fibre-optic focus-detection system for non-contact, high-resolution thickness measurement of transparent tissues

    NASA Astrophysics Data System (ADS)

    Ziebarth, Noël; Manns, Fabrice; Parel, Jean-Marie

    2005-08-01

    A low-cost, high-resolution, fibre optic system for non-contact thickness measurement of ocular tissues in cadaver eyes was developed. The optical system uses direct modulation at 100 kHz of a 670 nm laser diode delivered to a single-mode fibre coupler. The output of the fibre coupler is focused onto the tissue using a high numerical aperture aspheric lens mounted on a motorized translation stage. Light reflected from the sample is collected by the fibre coupler and sent to a photoreceiver. Peaks in the power signal are detected when the focal point of the aspheric lens coincides with the tissue boundaries. The thickness is proportional to the distance between successive peaks. The optical system has a sensitivity of 52 dB, which corresponds to a detectable change in the refractive index of 0.005 at a boundary-assuming specular reflection. With a focusing numerical aperture of 0.68, the resolution is 4.0 µm and the precision is ± 0.2 µm. The optical system was used to measure the corneal layers and lens capsule thickness of cadaver monkeys eyes. The system was able to measure the thickness of the epithelium, stroma and Descemet's membrane of the cornea, as well as the lens capsule and lens epithelial cell layer.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  11. 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%.

  12. Quick, Low Skill Fibre Cable Repair System In Hostile Environments

    NASA Astrophysics Data System (ADS)

    Allos, T. I.; Warnes, C. M.; Lee, P. J.

    1985-08-01

    As the expansion of fibre optic systems continues and the amount of installed single and multiway ruggedised fibre cable increases there has been a growing interest in "IN-SITU" fibre cable repair systems. Until recently, fibre cable repairs have been centred around conventional techniques (1, 2 & 3) i.e. termination and fusion splicing. The repair conditions dictated by these techniques requires the utilisation of the following facilities and materials:- 1. Epoxy resin systems and their applicators. 2. Good polishing facilities. 3. Passive hand held tools: e.g. cable strippers, wire cutters, fibre cleaver etc. 4. Active tools (electrically powered); e.g. Arc fusion splicer, heat gun, heat curing fixtures etc. 5. Connectors for terminated fibres. 6. Completed internal and external splice protection (for fusion splicing). 7. Visual inspection (microscopes).

  13. Micro-Mechanical Parameters in Short Fibre Composite

    NASA Astrophysics Data System (ADS)

    Ioannis, Ioannou; Alma, Hodzic; Inna, Gitman; Costas, Soutis; Almaadeed, M. A.

    2014-02-01

    The aim of this paper is to analyse the contribution of micro-mechanical parameters, on the macroscopic behaviour of a short fibre reinforced thermoplastic composites (SFRTC). By developing an algorithm to provide a representative random micro-structure, a comparative analysis of different micro-mechanical parameters, such as aspect ratio (AR) and fibre orientation (FO), was conducted and compared with the existing analytical models. A study of different aspect ratios and different fibre orientations has been carried out in order to examine their effect on the linear elastic properties of SFRTC. Aspect ratios from one to ten have been analysed for the cases of fully oriented 0 fibres, miss-oriented fibres and randomly oriented fibres. A representative volume element (RVE) was used to investigate the effect of the representative size. Results were analysed statistically through X 2 test, and the subsequent representative realisations were compared with the theoretical predictions.

  14. 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)

  15. Bizarre repetitive discharges recorded with single fibre EMG.

    PubMed Central

    Trontelj, J; Stålberg, E

    1983-01-01

    Single fibre EMG was used to record bizarre repetitive discharges in patients with chronic denervation or muscle disorders. The low variability of intervals between individual spike components on successive discharges suggests that the bizarre repetitive discharges are based on ephaptic impulse transmission from the muscle fibre starting the discharge (principal pacemaker) to the adjacent muscle fibres. The low variability of the interdischarge intervals is explained by ephaptic reactivation of the principal pacemaker by one of the fibres participating in the previous discharge (a co-pacemaker). Secondary activator fibres may spread activity to more fibres. The bizarre repetitive discharge stops when either the principal pacemaker or the co-pacemaker become sufficiently subnormal to block. The co-pacemaker may be missing in cases of low frequency bizarre repetitive discharges, particularly in those with irregular interdischarge intervals. PMID:6842243

  16. 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

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

    PubMed

    Chen, Lei; Bird, David M

    2011-03-28

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

  18. Core-index determination of a thick fibre using lens-fibre interference (LFI) technique

    NASA Astrophysics Data System (ADS)

    Hamza, A. A.; Mabrouk, M. A.; Ramadan, W. A.; Wahba, H. H.

    2004-08-01

    In this paper, we used lens-fibre interference technique, proposed by Ramadan (J Opt A: Pure and appl Opt 2 (2000) 234) to determine the refractive index of the step-index fibre core with radius of the order of 0.85 mm. A mathematical expression for the optical path length has been derived and used to estimate the obtained experimental interference fringes. A comparison between the experimental and theoretical fringes provides the refractive index of the fibre-core material. This comparison has been done with the aid of computer image processing to increase the accuracy of our measurements. The accuracy in the measured refractive index is of the order of ±8×10 -4.

  19. Preparation of hollow-fibre and composite hollow-fibre carbon membranes

    SciTech Connect

    Linkov, V.M.; Sanderson, R.D.; Jacobs, E.P.

    1994-12-31

    Interest in carbon membranes world-wide has increased remarkably since Softer et al. introduced, in 1983, hollow-fibre carbon membranes produced by the pyrolysis of commercial cellulose membranes. The scientific community was attracted by the high permselectivities of these membranes and their stability at high temperatures. Scientific organizations in Japan, France, Germany and other countries have made efforts to prepare mechanically stable carbon hollow fibres by various techniques. Materials other than cellulose, such as phenolic resins and polyacrylonitrile (PAN), were used for this purpose. Although some Positive results have been reported in the literature, mechanically strong and flexible carbon hollow-fibre membranes with high porosity and highly asymmetrical structure have not yet been produced. Here, the production of hollow-fiber carbon membranes, the modification of their porous structure, and the investigation into various techniques for coating them with inorganic and organic materials, are presented.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. Optical fibre sensors based on multi-mode fibres and MIMO signal processing: an experimental approach

    NASA Astrophysics Data System (ADS)

    Ahrens, Andreas; Sandmann, Andre; Bremer, Kort; Roth, Bernhard; Lochmann, Steffen

    2015-09-01

    In this paper multiple-input multiple-output (MIMO) signal processing is investigated for fibre optic sensor applications. A (2 2) MIMO implementation is realized by using lower-order and higher-order mode groups of a graded-index (GI) multi-mode fibre (MMF) as separate transmission channels. A micro-bending pressure sensor changes these separate transmission characteristics and introduces additional crosstalk. By observing the weight-factors of the MIMO system the amount of load applied was determined. Experiments verified a good correlation between the change of the MIMO weight coefficients and the load applied to the sensor and thus verified that MIMO signal processing can beneficially be used for fibre optic sensor applications.

  2. Rheology of Carbon Fibre Reinforced Cement-Based Mortar

    SciTech Connect

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

    2008-07-07

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

  3. 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)

  4. The hygroscopic behavior of plant fibres: a review

    NASA Astrophysics Data System (ADS)

    Clino, 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.

  5. Fibre Optic Temperature Sensors Using Fluorescent Phenomena.

    NASA Astrophysics Data System (ADS)

    Selli, Raman Kumar

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

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

    PubMed

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

    2014-08-01

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

  7. Scanning probe microscopy examination of the surface properties of keratin fibres.

    PubMed

    Maxwell, J M; Huson, M G

    2005-01-01

    A Scanning Probe Microscope (SPM) was used to investigate the mechanical properties of the surface of hair and wool fibres. Using stiff cantilevers, penetration was achieved on the fibres under ambient conditions and at increased relative humidity (RH). The Young's modulus of the exocuticle was estimated to be 2.1GPa under ambient conditions, decreasing to 0.6GPa at 96% RH. Contrary to findings by other authors [Crossley, J.A.A., Gibson, C.T., Mapledoram, L.D. , Huson, M.G., Myhra, S., Pham, D.K., Sofield, C.J., Turner, P.S., Watson, G.S., 2000. Atomic force microscopy analysis of wool fibre surfaces in air and under water. Micron 31, 659-667; Gibson, C.T., Watson, G.S., Mapledoram, L.D., Kondo, H., Myhra, S., 1999. Characterisation of organic thin films by atomic force microscopy-application of force vs. distance analysis and other modes. Applied Surface Science 144-145, 618-622; Blach, J., Loughlin, W., Watson, G.S., Myhra, S., 2001. Surface characterization of human hair by atomic force microscopy in the imaging and f-d modes. Journal of Cosmetic Science 23, 165-174], the surface lipid layer could not be penetrated using soft cantilevers in force-distance (f-d) mode in water. Attempts were made to remove the lipid layer from the surface both physically and chemically so as to examine the influence of the lipid on f-d measurements. Using both techniques, it was not possible to remove lipid without damaging the fibre, suggesting that the lipid is an integral part of the surface rather than a discrete surface layer. Adhesion measurements on the surface of wool, nylon and polyethylene, showed that in water and at high RH, the surface of keratin fibres is more akin to a polyamide. At low RH and in liquid paraffin, the surface is more akin to a hydrocarbon, suggesting it is capable of altering its structure in response to different environments. PMID:15629644

  8. 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.

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

    PubMed

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

    2007-08-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  11. Photothermal modeling of thulium fibre laser-tissue interactions

    NASA Astrophysics Data System (ADS)

    Warnaby, Catherine E.; Coleman, Daniel J.; King, Terence A.

    2003-10-01

    A one-dimensional finite difference model has been used to investigate the temperature distribution within thulium fibre laser-irradiated tissue. Temperature-time and temperature-depth profiles are presented for various laser stimulus parameters in the 2 micron region. These current calculations are aimed at determining theoretical temperature distributions in the application of relatively low power fibre lasers for thermal stimulation of cutaneous nerves in human pain processing. Theoretical skin surface temperatures are compared with those from thermal camera measurements during thulium fibre laser irradiation. The effectiveness of the thulium fibre laser for thermally stimulating cutaneous nerves is confirmed.

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

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

  13. Muscle fibre size and number following immobilisation atrophy.

    PubMed Central

    Nicks, D K; Beneke, W M; Key, R M; Timson, B F

    1989-01-01

    Muscle fibre number and cross sectional area were studied in the response to immobilisation atrophy of the long head of the triceps brachii. Following eight weeks of immobilisation, fibre number of the muscle from the immobilised limb was compared to that of the contralateral control limb in six rats. Mean fibre cross sectional area of the LHT from the immobilised limb was compared to that of the contralateral control for another six animals. Atrophy, as estimated by a decrease in wet muscle weight, was 38.0% for the group used for fibre number estimations and 45.7% for the group used for fibre area. Fibre counts revealed no difference between muscles from immobilised and control limbs. Mean fibre area was 42.1% less for the muscle from the immobilised limb compared to the control limb. The results of this study indicate that atrophy of the LHT produced by immobilisation of the forelimb is the result of atrophy of the muscle fibres without a decrease in muscle fibre number. PMID:2558097

  14. Hole inflation and tapering of stock photonic crystal fibres.

    PubMed

    Wadsworth, W; Witkowska, A; Leon-Saval, S; Birks, T

    2005-08-22

    We report controlled hole expansion in photonic crystal fibres (PCFs) by heating the fibre while the holes were pressurised. This was done by post-processing an existing fibre, not during fibre fabrication. Small holes in an endlessly single-mode (ESM) PCF were inflated to become large holes. The large-hole PCF was then tapered to produce a "cobweb" PCF with a small highly-nonlinear core, interfaced to the ESM PCF at both ends by gradual transitions. The loss was less than 0.4 dB in the complete structure, which was used to demonstrate supercontinuum generation when pumped with a fs Ti:sapphire laser. PMID:19498669

  15. Hole inflation and tapering of stock photonic crystal fibres

    NASA Astrophysics Data System (ADS)

    Wadsworth, W. J.; Witkowska, A.; Leon-Saval, S. G.; Birks, T. A.

    2005-08-01

    We report controlled hole expansion in photonic crystal fibres (PCFs) by heating the fibre while the holes were pressurised. This was done by post-processing an existing fibre, not during fibre fabrication. Small holes in an endlessly single-mode (ESM) PCF were inflated to become large holes. The large-hole PCF was then tapered to produce a "cobweb" PCF with a small highly-nonlinear core, interfaced to the ESM PCF at both ends by gradual transitions. The loss was less than 0.4 dB in the complete structure, which was used to demonstrate supercontinuum generation when pumped with a fs Ti:sapphire laser.

  16. Relativistic corrections for time and frequency transfer in optical fibres

    NASA Astrophysics Data System (ADS)

    Gerl, J.; Delva, P.; Wolf, P.

    2015-08-01

    We derive relativistic corrections for one-way and two-way time and frequency transfer over optical fibres neglecting no terms that exceed 1 ps in time and 10-18 in fractional frequency, and estimate their magnitude in typical fibre links. We also provide estimates of the uncertainties in the evaluation of the relativistic corrections due to imperfect knowledge of parameters like the coordinates of the fibre and stations, Earth rotation, or thermal effects of the fibre index and length. The links between Teddington(UK) and Paris(F) as well as Braunschweig(D) and Paris(F), that are currently under construction, are studied as specific examples.

  17. Multiphase modelling of the effect of fluid shear stress on cell yield and distribution in a hollow fibre membrane bioreactor.

    PubMed

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

    2015-04-01

    We present a simplified two-dimensional model of fluid flow, nutrient transport and cell distribution in a hollow fibre membrane bioreactor, with the aim of exploring how fluid flow can be used to control the distribution and yield of a cell population which is sensitive to both fluid shear stress and nutrient concentration. The cells are seeded in a scaffold in a layer on top of the hollow fibre, only partially occupying the extracapillary space. Above this layer is a region of free-flowing fluid which we refer to as the upper fluid layer. The flow in the lumen and upper fluid layer is described by the Stokes equations, whilst the flow in the porous fibre membrane is assumed to follow Darcy's law. Porous mixture theory is used to model the dynamics of and interactions between the cells, scaffold and fluid in the cell-scaffold construct. The concentration of a limiting nutrient (e.g. oxygen) is governed by an advection-reaction-diffusion equation in each region. Through exploitation of the small aspect ratio of each region and asymptotic analysis, we derive a coupled system of partial differential equations for the cell volume fraction and nutrient concentration. We use this model to investigate the effect of mechanotransduction on the distribution and yield of the cell population, by considering cases in which cell proliferation is either enhanced or limited by fluid shear stress and by varying experimentally controllable parameters such as flow rate and cell-scaffold construct thickness. PMID:25212097

  18. 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 states. Thus, the present study suggests that fibre-matrix and fibre-fibre interactions should be considered in the constitutive law when the model addresses questions concerning the stress field of the annulus fibrosus. PMID:24361932

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

    PubMed Central

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

    2015-01-01

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

  20. Termination areas of corticobulbar and corticospinal fibres in the rat.

    PubMed

    Antal, M

    1984-01-01

    Solution of the cobaltic lysine complex compound injected into the bulbar pyramid was taken up by pyramidal tract (PT) fibres and intraaxonally transported as far rostral as the internal capsule, and as far caudal as segment C4 of the spinal cord. With sulfide-precipitation of the cobalt and silver-intensification of the CoS, terminal branches of corticobulbar and corticospinal fibres could be shown in the following structures: In the pons the medial, ventral and the medial part of the lateral pontine nuclei are supplied with collaterals of PT fibres. The medial pontine nucleus receives contralateral PT fibres as well. The nucleus raphe magnus receives PT fibre collaterals from both sides. In the reticular formation contralateral fibres terminate in n. reticularis pontis caudalis, n. gigantocellularis, n. paramedianus, n. reticularis ventralis and dorsalis. Ipsilateral fibers terminate in the n. gigantocellularis and n. reticularis ventralis. The inferior olive receives both ipsilateral and contralateral PT fibres. All parts of the central gray substance are supplied by ipsi-and contralateral fibres which emerge from the PT at the level of the pyramidal decussation. The caudal nucleus of the spinal nucleus of the trigeminus receives a strong bundle of crossing PT fibres which terminate in the subnucleus magnocellularis. The dorsal column nuclei are virtually outlined by the numerous terminals of PT fibres. An oval area at ventrolateral aspect of the cuneate nucleus is innervated by PT fibres. The neurones of this area send their axons to the dorsal white column. In the spinal cord PT fibre terminals delineate four areas of termination. The first is the internal basilar nucleus which is the most richly supplied. The second lies lateral and ventral to this nucleus including segments of laminae V, VI, and VII. The third area extends into the ventral horn including a small zone of the ventral part of lamina VII. Thin PT fibre collaterals may establish here direct contacts with motoneurone dendrites. The fourth area includes laminae III and IV and receives individual terminal formations of thicker PT fibres. Findings which corroborate and which extend previous results are discussed. A few notes are made on the functional significance of some of these fibre connections. PMID:6526991

  1. Realisation de composants tout-fibre passifs bases sur des fibres optiques a deux coeurs

    NASA Astrophysics Data System (ADS)

    Jacob Poulin, Anne C.

    2002-01-01

    Les composants passifs tout-optique sont des elements de choix dans les systemes de communications optiques. Cette these presente l'utilisation experimentale de fibres a deux coeurs dissimilaires pour la realisation de filtres passe-bande. Les fibres a deux coeurs ont la particularite de favoriser un couplage d'un coeur a l'autre a intervalles reguliers lorsque les coeurs sont exactement identiques. Dans le cas ou une legere difference apparait, ce couplage est rapidement reduit a zero. La premiere partie de la these montre comment, par l'emploi d'une geometrie de fibre appropriee, il est possible de compenser cette desyntonisation et de fabriquer des coupleurs 100%. Les filtres obtenus ayant toutefois une largeur de bande trop grande pour les besoins du marche des communications optiques, il est montre dans la deuxieme partie de la these comment, en alliant la technologie des reseaux de Bragg avec celle des coupleurs, il est possible de realiser des filtres operant en transmission et possedant d'excellentes caracteristiques spectrales, toujours avec ces memes fibres a deux coeurs.

  2. 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.

  3. Sandwiched polymer fibre in fibrin matrices for the dictation of endothelial cells undergoing angiogenesis

    NASA Astrophysics Data System (ADS)

    Sukmana, I.; Djuansjah, J. R. P.

    2013-04-01

    We present here a three-dimensional (3D) sandwich system made by poly(ethylene terephthalate) (PET) fibre and fibrin extracellular matrix (ECM) for endothelial cell dictation and angiogenesis guidance. In this three-dimensional system, Human Umbilical Vein Endothelial cells (HUVECs) were firstly cultured for 2 (two) days to cover the PET fibre before sandwiched in two layer fibrin gel containing HUVECs. After 4 (four) days of culture, cel-to-cel connection, tube-like structure and multi-cellular lumen formation were then assessed and validated. Phase contrast and fluorescence imaging using an inverted microscope were used to determine cell-to-cell and cell-ECM interactions. Laser scanning confocal microscopy and histological techniques were used to confirm the development of tube-like structure and multi-cellular lumen formation. This study shows that polymer fibres sandwiched in fibrin gel can be used to dictate endothelial cells undergoing angiogenesis with potential application in cancer and cardiovascular study and tissue engineering vascularisation.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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.

  5. Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes

    PubMed Central

    Ara, Mirian; Ferreras, Antonio; Pajarin, Ana B.; Calvo, Pilar; Figus, Michele; Frezzotti, Paolo

    2015-01-01

    Objective. To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. Methods. One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. Results. ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. Conclusions. The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression. PMID:26185762

  6. 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.

  7. Type number and rigidity of fibred surfaces

    SciTech Connect

    Markov, P E

    2001-02-28

    Infinitesimal l-th order bendings, 1{<=}l{<=}{infinity}, of higher-dimensional surfaces are considered in higher-dimensional flat spaces (for l={infinity} an infinitesimal bending is assumed to be an analytic bending). In terms of the Allendoerfer type number, criteria are established for the (r,l)-rigidity (in the terminology of Sabitov) of such surfaces. In particular, an (r,l)-infinitesimal analogue is proved of the classical theorem of Allendoerfer on the unbendability of surfaces with type number {>=}3 and the class of (r,l)-rigid fibred surfaces is distinguished.

  8. 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)

  9. Changes in workplace concentrations of airborne respirable fibres in the European ceramic fibre industry 1987 1996.

    PubMed

    Miller, B G; Cherrie, J W; Groat, S; Kauffer, E

    2007-08-01

    As part of a wider epidemiological research programme, an occupational hygiene study was carried out during 1995-1996 to assess workers' current exposures to airborne materials in six European refractory ceramic fibre (RCF) plants. These plants had also participated in a cross-sectional occupational hygiene survey in 1987. The sampling strategy focussed principally on personal shift-average exposures of workers, by occupation, to respirable fibres. Monitoring was undertaken in two integrated phases: a 1-week cross-sectional survey followed by a prospective, and ongoing, programme by the RCF industry. Statistical (analysis of variance) analyses to identify patterns of variability by plant, occupational group (OG) and occupations within group were based on 464 individual shift samples, the greatest amount of data being available for production occupations. Concentrations of respirable fibres showed marked differences between plants and between OGs. Average respirable fibre concentrations among Primary and Secondary Production and Ancillary workers ranged from <0.1 f ml(-1) to up to 0.4 f ml(-1), depending on OG and plant. Individual shift-average measurements were almost invariably <1 f ml(-1). Within Secondary Conversion and Finishing, plant-specific averages ranged from 0.3 f ml(-1) to 1.25 f ml(-1). Respirable fibre concentrations were, in some plants, less than half those found in 1987. In other plants, mainly those where concentrations had been relatively low in 1987, the dust exposure had remained essentially unchanged or increased slightly. An ongoing programme of sampling is being carried out by the participating companies, generating additional information that could assist research in the long term and in improving control. PMID:17625218

  10. Development of tailor-made silica fibres for TL dosimetry

    NASA Astrophysics Data System (ADS)

    Bradley, D. A.; Abdul Sani, Siti F.; Alalawi, Amani I.; Jafari, S. M.; Noor, Noramaliza M.; Hairul Azhar, A. R.; Mahdiraji, Ghafour Amouzad; Tamchek, Nizam; Ghosh, S.; Paul, M. C.; Alzimami, Khalid S.; Nisbet, A.; Maah, M. J.

    2014-11-01

    The Ge dopant in commercially available silica optical fibres gives rise to appreciable thermoluminscence (TL), weight-for-weight offering sensitivity to MV X-rays several times that of the LiF dosimeter TLD100. The response of these fibres to UV radiation, X-rays, electrons, protons, neutrons and alpha particles, with doses from a fraction of 1 Gy up to 10 kGy, have stimulated further investigation of the magnitude of the TL signal for intrinsic and doped SiO2 fibres. We represent a consortium effort between Malaysian partners and the University of Surrey, aimed at production of silica fibres with specific TL dosimetry applications, utilizing modified chemical vapour deposition (MCVD) doped silica-glass production and fibre-pulling facilities. The work is informed by defect and dopant concentration and various production dependences including pulling parameters such as temperature, speed and tension; the fibres also provide for spatial resolutions down to <10 μm, confronting many limitations faced in use of conventional (TL) dosimetry. Early results are shown for high spatial resolution (~0.1 mm) single-core Ge-doped TL sensors, suited to radiotherapy applications. Preliminary results are also shown for undoped flat optical fibres of mm dimensions and Ge-B doped flat optical fibres of sub-mm dimensions, with potential for measurement of doses in medical diagnostic applications.

  11. Filter media properties of mineral fibres produced by plasma spray.

    PubMed

    Prasauskas, Tadas; Matulevicius, Jonas; Kliucininkas, Linas; Krugly, Edvinas; Valincius, Vitas; Martuzevicius, Dainius

    2016-06-01

    The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)). PMID:26583905

  12. REVIEW ARTICLE Blue extension of optical fibre supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Travers, J. C.

    2010-11-01

    Supercontinuum generation in optical fibres pumped with high power pulse sources in the modulation instability regime is reviewed. The physical mechanisms and supercontinuum dynamics are described in detail. Routes to optimized output in terms of spectral flatness and particularly blue and ultraviolet spectral extent are presented, including the use of cascaded and tapered photonic crystal fibres.

  13. 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.

  14. Inhibition of cytokinesis by asbestos and synthetic fibres.

    PubMed

    Jensen, C G; Watson, M

    1999-01-01

    Using high-resolution timelapse microscopy, we have followed individual phagocytized fibres through the later stages of division in MeT-5A human mesothelial cells and LLC-MK(2)monkey epithelial cells. The fibres used were crocidolite and chrysotile asbestos, fibrous glass (MMVF), and refractory ceramic fibres (RCF). Long fibres (15-80 microm) trapped within the cleavage furrow can partially or completely block cytokinesis. Cells proceed in one of three ways: (1) eventual completion of cytokinesis; (2) incomplete cytokinesis, resulting in two cells joined by a fibre-containing intercellular channel; or (3) failure of cytokinesis, resulting in a binucleate or trinucleate cell. Two factors associated with fibre-induced bi/trinucleation are: (1) an initial association between the fibre and the forming daughter nuclei, which is sometimes lost over time, and (2) disintegration of the midbody. The studies suggest that delay of cytokinesis by interzonal fibres can result in bi/trinucleation through the loss of midbody/intercellular bridge proteins that are required for completion of cytokinesis. PMID:10772757

  15. Quantitative non-destructive characterisation (NDC) of plant fibre composites

    NASA Astrophysics Data System (ADS)

    Rheinländer, Jørgen; Cendre, Emmanuelle; Debel, Christian; Borum, Kaj K.; Lilholt, Hans

    1999-12-01

    Composites made of plant fibres offer a new, environmentally attractive supplement to traditional glass fibre composite materials. Plant fibre composites may have similar mechanical properties as conventional (e.g. glass fibre) composites, with a lower impact strength. Since plant fibre composites constitute a relatively new group of materials, the limitations imposed on the mechanical performance due to flaws are not well known. The subject of this article is the investigation of the structure, the homogeneity and the mechanical properties of jute fibre based composites, and the correlation to quantitative data derived from X-radiography and ultrasonic scanning. The results indicates that parameters such as fibre orientation and fibre volume fraction are very important concerning sample tensile strength. These parameters can be assessed by the considered QNDC techniques. It is also shown that the samples are relatively homogeneous, and that the limitation on mechanical performance cannot by the considered techniques be related to a single defect. From the results it may be further concluded that the NDC techniques can provide quantitative data for an assessment of important manufacturing variables.

  16. Optic fibre as a transducer of tendomuscular forces.

    PubMed

    Komi, P V; Belli, A; Huttunen, V; Bonnefoy, R; Geyssant, A; Lacour, J R

    1996-01-01

    Direct in vivo tendon force measurements open up new possibilities for understanding of muscle-tendon loads during natural locomotion. The present report presents a new optic fibre method for such applications. The method is based on light intensity modulation by mechanical modification of the geometric properties of the optic fibre. A special optic fibre with a plastic covering buffer and with a total diameter of either 265 microns or 500 microns was carefully prepared at both ends for receiving and transmitting light. The fibre was inserted through the rabbit common calcaneal tendon with a 20 gauge needle. By removing the needle the optic fibre remained in situ. Static loading demonstrated that the voltage output of the optic fibre transducer showed a good linear fit of r = .999 with added loads. In dynamic loading conditions the optic fibre followed well the response of a strain gauge transducer, which was also attached to the tendon. The optic fibre method seems suitable for many applications for tensile and possibly ligament force measurements. PMID:8820899

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  18. Different types of extrafusal muscle fibres in snake costocutaneous muscles.

    PubMed

    Ridge, R M

    1971-09-01

    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 C(m) = 1 muF/cm(2) and R(m) = 40,000 Omega cm(2).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 C(m), R(m) or lambda was found between faster and slow twitch fibres. Values were approximately 3-4 muF/cm(2), 3000-4000 Omega cm(2) and 2 mm respectively. PMID:5097606

  19. Protein, fibre and blood pressure: potential benefit of legumes.

    PubMed

    Lee, Ya Ping; Puddey, Ian B; Hodgson, Jonathan M

    2008-04-01

    1. Prevention of hypertension and improved blood pressure control can be achieved through dietary modification. In particular, population studies and randomised controlled trials have indicated a beneficial effect of both dietary protein and dietary fibre on level of blood pressure. 2. A large population study indicates that an increase in 37 g/day of protein leads to a decrease in mean systolic and diastolic blood pressure by approximately 3 and 2.5 mmHg, respectively. This protective effect is independent of the source of dietary protein. 3. Meta-analysis suggests that a fibre increase of approximately 17 g/day will decrease systolic blood pressure by 1.15 mmHg and diastolic blood pressure by 1.65 mmHg, with soluble fibre showing a stronger effect than insoluble fibre. 4. Protein and dietary fibre may have additive effects to lower blood pressure. One feasible approach to increasing both protein and fibre in the daily diet could be through the incorporation of legumes, a protein- and fibre-rich food. 5. This review assesses the evidence for effects of protein and fibre to reduce blood pressure and the potential of incorporation of legumes into the daily diet as a feasible approach to achieving such benefits for blood pressure. PMID:18307744

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

    PubMed

    Sharma, Y; Phillion, A B; Martinez, D M

    2015-12-01

    A novel algorithm has been developed and validated to isolate individual papermaking fibres in micro-computed tomographic images of paper handsheets as a first step to characterize the structure of the paper. The three-step fibre segmentation algorithm segments the papermaking fibres by (i) tracking the hollow inside the fibres via a modified connected component methodology, (ii) extracting the fibre walls using a distance transform and (iii) labelling the fibres through collapsed sections by a final refinement step. Furthermore, postprocessing algorithms have been developed to calculate the length and coarseness of the segmented fibres. The fibre segmentation algorithm is the first ever reported method for the automated segmentation of the tortuous three-dimensional morphology of papermaking fibres within microstructural images of paper handsheets. The method is not limited to papermaking fibres, but can be applied to any material consisting of tortuous and hollow fibres. PMID:26301453

  1. 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.

  2. Design of erbium doped double clad ZBLAN Fibre laser

    NASA Astrophysics Data System (ADS)

    Oladeji, A.; Phillips, A.; Lamrini, S.; Scholle, K.; Fuhrberg, P.; Seddon, A. B.; Benson, T. M.; Sujecki, S.

    2015-06-01

    A high powered octagonal double clad ZBLAN (33 μm/330 μm, NA=0.13) glass fibre for mid-infrared light generation is studied using a one dimensional rate equation model. The fibre laser design employs the concept of cascade lasing and includes up-conversion phenomena. The results obtained demonstrate that efficient cascade lasing may be achieved in practice without the need for fibre grating fabrication, as a sufficient level of feedback for laser action is provided by Fresnel light reflection at ZBLAN glass fibre air interfaces. Further enhancement of the laser efficiency can be achieved by terminating one of the fibre ends with a mirror. Simulation results show that the laser operation with 20 W of pump power at 0.98 μm wavelength can be achieved at 2.75 μm operating wavelength with Er3+ ion concentrations of 60,000 ppm.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  5. 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.

  6. 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)

  7. Phosphocreatine as a marker of contractile activity in single muscle fibres.

    PubMed

    Conjard, A; Pette, D

    1999-08-01

    ATP and phosphocreatine (PCr) were measured in randomly selected single fibres from control, 1- and 8-day low-frequency-stimulated rabbit tibialis anterior muscles. The fibres were classified according to their myosin heavy chain (MHC) complement as type I, IIA or IID. In 1-day stimulated muscle, which has previously been shown to exhibit a steep decline in force output, two fibre populations could be distinguished according to either normal or markedly depressed PCr levels. The fibre population exhibiting normal PCr levels encompassed a major fraction (65%) of type IID fibres and a minor fraction (35%) of IIA fibres. The population with reduced PCr levels comprised type I fibres (@50% reduced), the majority of type IIA fibres (@80% reduced), and a minor fraction of type IID fibres (@70% reduced). Levels of ATP were unaltered in type I and IIA fibres, but were @ 20% reduced in those IID fibres that exhibited low PCr levels. Assuming that those fibres that displayed reduced PCr levels were contracting, the IID and IIA fibres with normal PCr levels were regarded as metabolically recovering, non-contracting fibres. As previously shown, these fibres are transiently refractory during the early phase of low-frequency stimulation. After 8 days of chronic low-frequency stimulation, when force was shown to rise again, most fibres appeared more uniform with regard to reduced PCr and ATP levels. Our results suggest that PCr can be used as a sensitive measure of the degree of activity in single-fibre studies. PMID:10398856

  8. Histomorphometric analysis of collagen and elastic fibres in the cranial and caudal fold of the porcine glottis.

    PubMed

    Lang, A; Koch, R; Rohn, K; Gasse, H

    2015-06-01

    The porcine glottis differs from the human glottis in its cranial and caudal vocal folds (CraF, CauF). The fibre apparatus of these folds was studied histomorphometrically in adult minipigs. For object definition and quantification, the colour-selection tools of the Adobe-Photoshop program were used. Another key feature was the subdivision of the cross-sections of the folds into proportional subunits. This allowed a statistical analysis irrespective of differences in thickness of the folds. Both folds had a distinct, dense subepithelial layer equivalent to the basement membrane zone in humans. The subsequent, loose layer was interpreted - in principle - as being equivalent to Reinke's space of the human vocal fold. The next two layers were not clearly separated. Due to this, the concept of a true vocal ligament did not appear applicable to neither CauF nor CraF. Instead, the body-cover model was emphasized by our findings. The missing vocalis muscle in the CraF is substituted by large collagen fibre bundles in a proportional depth corresponding to the position of the muscle of the CauF. The distribution of elastic fibres made the CraF rather than the CauF more similar to the human vocal fold. We suggest that these data are useful for those wishing to use the porcine glottis as a model for studying oscillatory properties during phonation. PMID:24995486

  9. Control of interfaces in Al-C fibre composites

    NASA Technical Reports Server (NTRS)

    Warrier, S. G.; Blue, C. A.; Lin, R. Y.

    1993-01-01

    The interface of Al-C fiber composite was modified by coating a silver layer on the surface of carbon fibres prior to making composites, in an attempt to improve the wettability between molten aluminum and carbon fibers during infiltration. An electroless plating technique was adopted and perfected to provide a homogeneous silver coating on the carbon fiber surface. Al-C fiber composites were prepared using a liquid infiltration technique in a vacuum. It was found that silver coating promoted the wetting between aluminum and carbon fibers, particularly with polyacrylonitrile-base carbon fibers. However, due to rapid dissolution of silver in molten aluminum, it was believed that the improved infiltration was not due to the wetting behavior between molten aluminum and silver. The cleaning of the fiber surface and the preservation of the cleaned carbon surface with silver coating was considered to be the prime reason for the improved wettability. Interfacial reactions between aluminum and carbon fibers were observed. Amorphous carbon was found to react more with aluminum than graphitic carbon. This is believed to be because of the inertness of the graphitic basal planes.

  10. Ocular Dominance Is Associated with the Ganglion Cell-Inner Plexiform Layer Thickness Profile in the Macula

    PubMed Central

    Choi, Jin A.; Kim, Jung-Sub; Jeong, Hyun Jin; Lee, Jin Ah; Park, Chan Kee

    2016-01-01

    Purpose To investigate the characteristics of macular ganglion cell-inner plexiform layer (GCIPL) thickness profiles associated with ocular dominance. Setting Private practice, Seoul, Republic of Korea. Design Comparative case-control study. Methods Both eyes of 199 participants with no ophthalmic abnormalities were included. Participants were imaged by spectral-domain optical coherence tomography, and underwent dominant eye testing using a hole-in-a-card test (sighting dominance) at the same visit. Macular GCIPL, as well as circumpapillary retinal nerve fiber layer (RNFL) thickness were compared for individual patients, according to ocular dominance. Results Ocular dominance occurred predominantly in the right eye (right vs. left: 72.36 vs. 27.60%; P < 0.001). In the comparison of macular GCIPL thickness, the average (81.27±5.01 μm vs. 80.66±6.31 μm in dominant vs. non-dominant eyes), inferonasal (81.39±5.47μm vs. 80.33±6.82μm, and inferior sectors (77.95±6.05μm vs. 76.97±8.15μm) were significantly different between dominant and non-dominant eyes (P = 0.040, 0.005, and 0.032, respectively). Significant predictors of average GCIPL thickness were spherical equivalent (β = 1.37, P<0.001), astigmatic power (β = 1.44, P = 0.009), disc area (β = 3.90, P < 0.001), average RNFL thickness (β = 0.22, P<0.001), average cup-to-disc ratio (β = 5.74, P = 0.002), difference between the inferior and superior quadrant RNFL thicknesses (β = 0.08, P = 0.024), and ocular dominance (β = 2.10, P = 0.020). On multivariate regression analysis, ocular dominance was correlated with average GCIPL thickness after adjusting for potential confounders (β = 1.63, P = 0.048). Conclusions Dominant eyes accompanied significantly thicker average macular GCIPL. This information suggests that macular GCIPL thickness may provide an indicator of the relative dominance of an eye. PMID:26918335

  11. Spiders spinning electrically charged nano-fibres

    PubMed Central

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland–duct–spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. PMID:25631231

  12. Quantum cryptography on multiuser optical fibre networks

    NASA Astrophysics Data System (ADS)

    Townsend, Paul D.

    1997-01-01

    To establish a secure communication channel, it is necessary to distribute between two users a key which allows safe encryption and decryption of messages. But because decryption is a simple task for any key holder, it is crucial that the key remains secret during distribution. Secrecy cannot be guaranteed if distribution occurs on the basis of classical physical mechanisms, as it is impossible to know whether the key has been intercepted during transmission. Quantum cryptography1-3 provides a fundamental solution to this problem. When quantum-mechanical processes are used to establish the key, any eavesdropping during transmission leads to an unavoidable and detectable disturbance in the received key information. Quantum cryptography has been demonstrated using standard telecommunication fibres linking single pairs of users4-8, but practical implementations will require communication networks with many users9. Here I introduce a practical scheme for multi-user quantum cryptography, and demonstrate its operation on an optical fibre network. The scheme enables a single controller on the network to establish, and regularly update, a distinct secret key with each network user. These keys can then be used to securely encrypt conventional data transmissions that are broadcast on the network.

  13. Hydrodynamics of diatom chains and semiflexible fibres

    PubMed Central

    Nguyen, Hoa; Fauci, Lisa

    2014-01-01

    Diatoms are non-motile, unicellular phytoplankton that have the ability to form colonies in the form of chains. Depending upon the species of diatoms and the linking structures that hold the cells together, these chains can be quite stiff or very flexible. Recently, the bending rigidities of some species of diatom chains have been quantified. In an effort to understand the role of flexibility in nutrient uptake and aggregate formation, we begin by developing a three-dimensional model of the coupled elastic–hydrodynamic system of a diatom chain moving in an incompressible fluid. We find that simple beam theory does a good job of describing diatom chain deformation in a parabolic flow when its ends are tethered, but does not tell the whole story of chain deformations when they are subjected to compressive stresses in shear. While motivated by the fluid dynamics of diatom chains, our computational model of semiflexible fibres illustrates features that apply widely to other systems. The use of an adaptive immersed boundary framework allows us to capture complicated buckling and recovery dynamics of long, semiflexible fibres in shear. PMID:24789565

  14. 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.

  15. 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

  16. 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.

  17. Modified sensing element of a fibre-optic current sensor based on a low-eigenellipticity spun fibre

    SciTech Connect

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P

    2014-10-31

    We have proposed and investigated a modified sensing element of a spun fibre current sensor for the case when the beat length of the built-in linear birefringence of the fibre is equal to or less than the spin pitch of its helical structure. The proposed configuration makes it possible to restore the interferometer contrast reduced because of the decrease in the ellipticity of the wavelength-averaged polarisation state of radiation propagating in such spun fibre. The modified sensing element contains two polarisation state converters: one, located at the spun fibre input, produces polarisation with ellipticity equal to the eigenellipticity of the fibre, and the other ensures conversion of the elliptical polarisation to an orthogonal one through mirror reflection at the fibre output. We have also demonstrated that the magneto-optical sensitivity decreases slightly for the analysed spectrum-averaged parameters of the polarisation state of radiation in the spun fibre. Experimental data lend support to the theoretical predictions. (fibre-optic sensors)

  18. Determining the fibrillar orientation of bast fibres with polarized light microscopy: the modified Herzog test (red plate test) explained

    PubMed Central

    HAUGAN, E; HOLST, B

    2013-01-01

    The identification of bast fibre samples, in particular, bast fibres used in textiles, is an important issue in archaeology, criminology and other scientific fields. One of the characteristic features of bast fibres is their fibrillar orientation, referred to as Z- or S twist (or alternatively right- and left-handed fibres). An empirical test for determining the fibrillar orientation using polarized light microscopy has been known in the community for many years. It is referred to as the modified Herzog test or red plate test. The test has the reputation for never producing false results, but also for occasionally not working. However, so far, no proper justification has been provided in the literature that the no false results assumption is really correct and it has also not been clear up till now, why the method sometimes does not work. In this paper, we present an analytical model for the modified Herzog test, which explains why the test never gives a false result. We also provide an explanation for why the Herzog test sometimes does not work: According to our model, the Herzog test will not work if none of the three distinct layers in the secondary cell wall is significantly thicker than the others. PMID:24020614

  19. The Application of Fibre Optics in Fibre Distributed Data Interface (FDDI) 100Mb/s Local Area Networks (LANs)

    NASA Astrophysics Data System (ADS)

    King, Timothy; Roworth, Don

    1987-09-01

    The Fibre Distributed Data Interface (FDDI) is a flexible, high-speed token-passing twin ring network which is being specified by ANSI to provide synchronous and asynchronous data transmission, as well as isochronous channels for real-time digitised speech and video. Unlike existing open standard LANs, where fibre optic variants have been introduced following successful implementation on conductive media, FDDI has been designed from the start as a fibre optic network. This has involved issues of standardisation in such areas as duplex optical connectors, fibre characteristics, optical bandwidth, bypass relays and keyed cable assemblies. This paper gives an overview of the fibre optics aspects of the development, including the overall optical design, special component requirements, and practical issues of application.

  20. The Effect of Axial Length on the Thickness of Intraretinal Layers of the Macula

    PubMed Central

    Szigeti, Andrea; Tátrai, Erika; Varga, Boglárka Enikő; Szamosi, Anna; DeBuc, Delia Cabrera; Nagy, Zoltán Zsolt; Németh, János; Somfai, Gábor Márk

    2015-01-01

    Purpose The aim of this study was to evaluate the effect of axial length (AL) on the thickness of intraretinal layers in the macula using optical coherence tomography (OCT) image analysis. Methods Fifty three randomly selected eyes of 53 healthy subjects were recruited for this study. The median age of the participants was 29 years (range: 6 to 67 years). AL was measured for each eye using a Lenstar LS 900 device. OCT imaging of the macula was also performed by Stratus OCT. OCTRIMA software was used to process the raw OCT scans and to determine the weighted mean thickness of 6 intraretinal layers and the total retina. Partial correlation test was performed to assess the correlation between the AL and the thickness values. Results Total retinal thickness showed moderate negative correlation with AL (r = -0.378, p = 0.0007), while no correlation was observed between the thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCC), retinal pigment epithelium (RPE) and AL. Moderate negative correlation was observed also between the thickness of the ganglion cell layer and inner plexiform layer complex (GCL+IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and AL which were more pronounced in the peripheral ring (r = -0.402, p = 0.004; r = -0.429, p = 0.002; r = -0.360, p = 0.01; r = -0.448, p = 0.001). Conclusions Our results have shown that the thickness of the nuclear layers and the total retina is correlated with AL. The reason underlying this could be the lateral stretching capability of these layers; however, further research is warranted to prove this theory. Our results suggest that the effect of AL on retinal layers should be taken into account in future studies. PMID:26544553

  1. Stimulated Brillouin Scattering: its Generation and Applications in Optical Fibre

    NASA Astrophysics Data System (ADS)

    Culverhouse, David

    1992-01-01

    Available from UMI in association with The British Library. In the work presented in this thesis, the generation of stimulated Brillouin scattering and its applications in optical fibres is theoretically and experimentally investigated. The study pursues three special cases: (i) Backward stimulated Brillouin scattering in long fibre lengths; (ii) Backward stimulated Brillouin scattering in high finesse all fibre ring resonators; (iii) Forward stimulated Brillouin scattering in dual moded single core fibres. Stimulated Brillouin scattering (SBS) occurs for relatively low input powers in monomode optical fibres, as the power density is very high because of the relatively small core size. For applications such as optical communications, SBS is seen as a potentially deleterious effect because it can limit the maximum optical power transmitted by the fibre and hence decrease the distance between repeaters. SBS, however, can also be used to advantage in optical fibres, for example to produce amplification. In this thesis the comprehensive study of SBS in relation to other non-linear scattering mechanisms in optical fibres leads to the derivation of explicit definitions for the Brillouin gain and the Brillouin threshold. The study of SBS in high finesse all fibre ring resonators also demonstrates how threshold powers can be reduced, typically, from milliwatts observed in long fibre lengths to microwatts. Because Brillouin scattering is primarily a result of the interaction of the incident optical beam with spontaneously generated (thermal) fluctuations in the density of the medium, the spectral features show a considerable variation with temperature thus providing a mechanism with sufficient sensitivity to realise tunable microwave generation and frequency shifting devices. Finally, the observation of stimulated Brillouin scattering in a forward direction (FSBS) in dual moded single-core fibre is also reported. Frequency shifts in the order of 17MHz are observed in optical fibre supporting LP_ {01} and LP_{11} modes at 514.5nm. The phenomenon is examined here in detail and the governing differential equations of the three wave parametric process (involving pump/laser, Brillouin signal and acoustic flexural wave phonon) is derived and solved. FSBS is possible because, although the overlap integral between a fibre flexural mode and the light is small, the phonon lifetime is much longer than in conventional SBS. FSBS may also be the first example of a non-linear effect which is enhanced by increasing the optical mode area at constant pump power.

  2. Chronic inhalation studies of man-made vitreous fibres: characterization of fibres in the exposure aerosol and lungs.

    PubMed

    Hesterberg, T W; Miiller, W C; Thevenaz, P; Anderson, R

    1995-10-01

    Inhalation studies were conducted to determine the chronic biological effects in rodents of respirable fractions of different man-made vitreous fibres (MMVFs), including refractory ceramic fibre (RCF), fibrous glass, rock (stone) wool and slag wool. Animals were exposed nose-only, 6 h per day, 5 days per week, for 18 months (hamsters) or 24 months (rats). Exposure to 10 mg m-3 of crocidolite or chrysotile asbestos induced pulmonary fibrosis, lung tumours and mesothelioma in rats, thus validating the inhalation model with known human carcinogenic fibres. Exposure of rats to 30 mg m-3 of refractory ceramic fibres (RCF) also resulted in pulmonary fibrosis as well as significant increases in lung tumours and mesothelioma. In hamsters, 30 mg m-3 of RCF induced a 41% incidence of mesotheliomas. Exposure of rats to 30 mg m-3 of fibre glasses (MMVF 10 or 11) or of slag wool (MMVF 22) was associated with an inflammatory response, but no mesotheliomas or significant increase in the lung tumours were observed. Rock wool (stone wool: MMVF 21) at the same exposure level resulted in minimal lung fibrosis, but no mesotheliomas or significant increase in the lung tumours were observed. Fibre numbers (WHO fibres) and dimensions in the aerosols and lungs of exposed animals were comparable in this series of inhalation studies. Differences in lung fibre burdens and lung clearance rates could not explain the differences observed in the toxicologic effects of the MMVFs. These findings indicate that dose, dimension and durability may not be the only determinants of fibre toxicity. Chemical composition and the surface physico-chemical properties of the fibres may also play an important role. PMID:8526395

  3. Fibre intake and incident colorectal cancer depending on fibre source, sex, tumour location and Tumour, Node, Metastasis stage.

    PubMed

    Vulcan, Alexandra; Brändstedt, Jenny; Manjer, Jonas; Jirström, Karin; Ohlsson, Bodil; Ericson, Ulrika

    2015-09-28

    Studies on fibre intake and incident colorectal cancer (CRC) indicate inverse associations. Differences by tumour stage have not been examined. We examined associations between fibre intake and its sources, and incidental CRC. Separate analyses were carried out on the basis of sex, tumour location and the Tumour, Node, Metastasis (TNM) classification. The Malmö Diet and Cancer Study is a population-based cohort study, including individuals aged 45-74 years. Dietary data were collected through a modified diet history method. The TNM classification was obtained from pathology/clinical records and re-evaluated. Among 27 931 individuals (60% women), we found 728 incident CRC cases during 428 924 person-years of follow-up. Fibre intake was inversely associated with CRC risk (P(trend) = 0.026). Concerning colon cancer, we observed borderline interaction between fibre intake and sex (P = 0.052) and significant protective association restricted to women (P(trend) = 0.013). Intake of fruits and berries was inversely associated with colon cancer in women (P(trend) = 0.022). We also observed significant interactions between intakes of fibre (P = 0.048) and vegetables (P = 0.039) and sex on rectal cancer, but no significant associations were seen between intake of fibre, or its sources, in either of the sexes. Except for inverse associations between intake of fibre-rich cereal products and N0- and M0-tumours, we did not observe significant associations with different TNM stages. Our findings suggest different associations between fibre intake and CRC depending on sex, tumour site and fibre source. High fibre intake, especially from fruits and berries, may, above all, prevent tumour development in the colon in women. No clear differences by TNM classification were detected. PMID:26281852

  4. Numerical modelling of a fibre reflection filter based on a metal-dielectric diffraction structure with an increased optical damage threshold

    NASA Astrophysics Data System (ADS)

    Terentyev, V. S.; Simonov, V. A.

    2016-02-01

    Numerical modelling demonstrates the possibility of fabricating an all-fibre multibeam two-mirror reflection interferometer based on a metal-dielectric diffraction structure in its front mirror. The calculations were performed using eigenmodes of a double-clad single-mode fibre. The calculation results indicate that, using a metallic layer in the structure of the front mirror of such an interferometer and a diffraction effect, one can reduce the Ohmic loss by a factor of several tens in comparison with a continuous thin metallic film.

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

    NASA Astrophysics Data System (ADS)

    Kernen, K.; Ollila, J.; Mkinen, J.-T.; Kautio, K.; Korhonen, P.; Heikkinen, V.; Vtinen, 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 ?m x 1?m stripe laser and 200/220 ?m 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 1014.9 specification. Leak rate for the module using a buffer stripper fibre without a rubber guard tube was 3 x 10 -9 [atm x cm 3/s]. The background helium level before and after the tests was less than 3 x 10 -10 [atm x cm 3/s]. This clearly higher leak rate in the final module leak measurement is mainly due to the absorbed helium to the fibre polymer buffer layer and rubber guard tube in the pressurization process. Measurements show that the implemented module is hermetic. Cost-of-ownership modelling was performed starting from low production volume up to production of 10 million good modules per year. Module production cost was estimated through COO modelling. Modelling forecasted that the module production can be lower than 10 EUR in high volume production.

  6. Merging porphyrins and structured optical fibres: future technology for chemical sensors

    NASA Astrophysics Data System (ADS)

    Martelli, Cicero; Canning, John; Crossley, Maxwell J.; Stocks, Danial; Sintic, Maxine

    2008-04-01

    Spectroscopic characterisation of water soluble porphyrins using a structured optical fibre are presented and discussed. Porphyrin thin-films were also fabricated inside the holes of structured fibres. The thin-films self-assemble inside the fibres leading to energy coupling between the molecules. These are the first steps towards future chemically tailored optical fibre sensors for molecular detection.

  7. Auditory nerve fibre responses to salicylate revisited.

    PubMed

    Müller, Marcus; Klinke, Rainer; Arnold, Wolfgang; Oestreicher, Elmar

    2003-09-01

    Ototoxicity of salicylate is accompanied by a temporary hearing loss and tinnitus and has therefore been used to study tinnitus in animal models. Salicylate induced elevated central auditory activity has been interpreted as a correlate of tinnitus. Whether this elevated activity in the central auditory system is due to an increased activity in the auditory nerve is still under discussion. To explore this issue, we recorded the activity of single auditory nerve fibres in anaesthetised gerbils following systemic injection of salicylic acid. Firstly, compound action potential (CAP) thresholds were determined at 5-0 min intervals. Fifteen to 30 min after 200 mg/kg salicylic acid, threshold loss developed in the high frequency range. At 2 h CAP threshold loss reached a plateau amounting to 15-20 dB above 16 kHz, 0-5 dB below 2 kHz. An almost immediate start of threshold loss was observed after 400 mg/kg salicylic acid. A plateau of threshold loss was reached after 1.5 h with values of 25 dB in the high, 5-10 dB in the low frequency range. Secondly, responses of single auditory nerve fibres were studied after administration of 200 mg/kg salicylic acid. Frequency tuning curves and rate intensity (RI) functions at characteristic frequency (CF) were measured. Two hours and more after application, single fibre thresholds were elevated by about 20 dB at all CFs. Sharpness of tuning was reduced. Mean spontaneous rate was significantly reduced at CFs below 5 kHz (mean: 44 vs 28 AP/s). At CFs above 5 kHz mean spontaneous rate remained unchanged. In RI functions no change in maximum discharge rate was observed. The altered response properties can be interpreted by the known effects of salicylate on the prestin mediated active process of the outer hair cells. The elevated activity in the central auditory system after salicylate intoxication thus cannot be caused by cochlear nerve hyperactivity. PMID:13679136

  8. Review on hygroscopic aging of cellulose fibres and their biocomposites.

    PubMed

    Mokhothu, Thabang H; John, Maya Jacob

    2015-10-20

    This review presents critical literature on effects of humidity and temperature on the properties of natural fibres and its composites. The drawback of moisture absorption on the mechanical properties of natural fibre and its composites is evaluated. Numerous researchers have been working to address the moisture absorption issue, with specific attention paid to the surface treatment of fibres and refining the fibre-matrix interface. Because of the natural fibre's positive commercial and environmental outcomes, as well as their desirable properties such as high specific strength, natural fibre reinforced composites are displaying a good potential to be used in various applications such as automotive, aerospace and packaging. This review addresses a comprehensive survey on hygroscopic factors (long term environmental aging) affecting natural fibres and their performance as reinforcement in polymer composites. The effects of cellulose surface chemistry and topography on hydrophobicity are addressed. Furthermore, the review also addresses the progress in the development of superhydrophobic materials based on cellulose material for better moisture resistance. In addition, recent investigations dealing with bio-based coatings prepared from renewable resources are also discussed. PMID:26256193

  9. Structured spheres generated by an in-fibre fluid instability.

    PubMed

    Kaufman, Joshua J; Tao, Guangming; Shabahang, Soroush; Banaei, Esmaeil-Hooman; Deng, Daosheng S; Liang, Xiangdong; Johnson, Steven G; Fink, Yoel; Abouraddy, Ayman F

    2012-07-26

    From drug delivery to chemical and biological catalysis and cosmetics, the need for efficient fabrication pathways for particles over a wide range of sizes, from a variety of materials, and in many different structures has been well established. Here we harness the inherent scalability of fibre production and an in-fibre Plateau-Rayleigh capillary instability for the fabrication of uniformly sized, structured spherical particles spanning an exceptionally wide range of sizes: from 2 mm down to 20 nm. Thermal processing of a multimaterial fibre controllably induces the instability, resulting in a well-ordered, oriented emulsion in three dimensions. The fibre core and cladding correspond to the dispersed and continuous phases, respectively, and are both frozen in situ on cooling, after which the particles are released when needed. By arranging a variety of structures and materials in a macroscopic scaled-up model of the fibre, we produce composite, structured, spherical particles, such as core-shell particles, two-compartment 'Janus' particles, and multi-sectioned 'beach ball' particles. Moreover, producing fibres with a high density of cores allows for an unprecedented level of parallelization. In principle, 10(8) 50-nm cores may be embedded in metres-long, 1-mm-diameter fibre, which can be induced to break up simultaneously throughout its length, into uniformly sized, structured spheres. PMID:22810590

  10. REVIEW ARTICLE Fibre optic devices produced by arc discharges

    NASA Astrophysics Data System (ADS)

    Rego, G.

    2010-11-01

    We present an overview of the applications of the electric arc technique related to optical fibre technology. The use of arc discharges ranges from the well-known fibre splicing, going through the fabrication of basic devices such as fibre tapers and microspheres, to tailoring the spectra of UV-induced gratings such as in the apodization of fibre Bragg gratings and also in the fabrication of phase-shifted and sampled fibre Bragg gratings. However, in the past decade a topic more intensively investigated was probably long-period fibre gratings. Therefore, some devices based on arc-induced gratings, namely, phase-shifted and step-changed gratings and bandpass filters are discussed. We also present an electrically insulated thermocouple assembled in situ using arc discharges. This sensor is very useful in the determination of the temperature attained by the fibre during an arc discharge, this property being fundamental for the discussion of the mechanisms of formation and for the understanding of the thermal properties of arc-induced devices.

  11. A novel wireless mobile platform integrated with optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Bochao; Yang, Shuo; Sun, Tong; Grattan, Kenneth T. V.

    2014-05-01

    This paper presents a novel design of wireless mobile platform which enables effective integration of a number of optical fibre sensors with an advanced mobile wireless sensor network (WSN) and allows for potential applications such as monitoring in remote and harsh environments and tracking, exploiting fully the advantages offered both by mobile WSN and by advanced optical fibre sensing technologies. The platform which was designed and implemented consists of an optical fibre sensor module and a smart mobile WSN module, which shows important advantages for mobile sensing and tracking and mesh networking. In this study, a fibre Bragg grating (FBG)-based temperature sensor was specially designed and integrated successfully into the optical fibre sensor module as an exemplar to investigate the performance of the integrated system based on the mobile WSN platform. The positive experimental results obtained have confirmed the functionality of the platform designed and demonstrated its capacity for real-time optical fibre sensor data monitoring, processing and wireless transmission. The successful creation of this type of wireless mobile platform with optical fibre sensors would be expected to make an important impact on many sectors, where either conventional optical sensor designs or WSNs alone cannot meet the systems requirements.

  12. Electron microscope characteristics of inhaled chrysotile asbestos fibre

    PubMed Central

    Pooley, F. D.

    1972-01-01

    Pooley, F. D. (1972).Brit. J. industr. Med.,29, 146-153. Electron microscope characteristics of inhaled chrysotile asbestos fibre. Specimens from 300 lungs have been examined under the electron microscope to determine the morphology and diffraction characteristics of any chrysotile asbestos they contained. In 120 cases, material was prepared by alkali digestion and the residual dust was examined. In all cases standard 6-micron histological slides were partially ashed before the residue was transferred to the electron microscope grids. Of the 300 specimens examined, 20 came from men with prolonged industrial exposure to chrysotile, 87 from cases of mesothelioma, and the remainder from control groups drawn from rural and industrial populations. Chrysotile fibres were readily identified by the characteristic polycrystalline diffraction pattern. The hollow appearance of the single fibres and their shape and arrangement also help in the identification. Specimens from men without industrial exposure contained either single short fibres or aggregates scattered throughout the lungs. In specimens from industrially exposed men, fibres were very numerous and found as strands of single fibres mainly grouped together in discrete locations. Ferruginous bodies were found rarely and only on straight fibre bundles of over several micrometers in length. Images PMID:5021995

  13. [Pleural lymphatics and pleural diseases related to fibres].

    PubMed

    Fleury Feith, J; Jaurand, M-C

    2013-12-01

    It is now well established that some pleural diseases, pleural plaques and malignant mesothelioma are related to asbestos fibre exposure although the mechanism of action of asbestos fibres is not fully understood. The development of artificial mineral fibres and carbon nanotubes, which share some morphological characteristics similar to asbestos fibres, is a present concern in the context of pleural diseases. Pleural plaques develop only in the parietal pleura, and in the 1990s, clinical observations have shown that the early development of mesothelioma also occurred on the parietal pleura. The peculiarity of the parietal pleura in contrast to the visceral pleura is the presence of "stomas" which are communication holes between the pleural cavity and the parietal pleura lymphatics. Morphological observations by thoracoscopy and experimental studies have shown that inhaled fibres translocate to the pleural space and, in human, are present in the parietal pleura at specific anthracotic areas (blackspots). Fibres accumulate on the stomas, up to block and locally induce an inflammatory reaction with cytokines release, that can be the bed of mesothelioma. However, despite the experimental data and observations in human pathology, the mechanisms of fibre translocation into the pleura is not yet clearly established. PMID:24210155

  14. Reflex discharge patterns of cardiac vagal efferent fibres

    PubMed Central

    Kunze, Diana Lee

    1972-01-01

    1. Unit activity was recorded from single and few fibre preparations in a cardiac branch of the right vagus nerve of the cat. 2. Increases in blood pressure mediated solely by the right carotid sinus nerve produced bradycardia when all other nerves to the heart had been cut. Myelinated fibres in the cardiac branch of the right vagus nerve were reflexly activated by the same procedure. 3. The fibres were silent when blood pressure was below 140-150 mm Hg. As the pressure began to rise, they discharged phasically with the cardiac cycle. At pressures greater than 180 mm Hg, the discharge was continuous attaining maximum rates of 40/sec. 4. Stimulation of carotid body chemoreceptors also reflexly excited these fibres, as did stimulation of baroreceptors in both the left carotid sinus and aortic arch. Afferent fibres in the left vagus discharging in response to changes in blood pressure reflexly excited the cardiac efferent fibres. Increases in phrenic motoneurone discharge coincided with inhibition of these fibres. Electrical stimulation of the glossopharyngeal nerve also produced inhibition. PMID:4338691

  15. Global chromatin fibre compaction in response to DNA damage

    SciTech Connect

    Hamilton, Charlotte; Hayward, Richard L.; Breakthrough Research Unit, The University of Edinburgh, Edinburgh EH4 2XR ; Gilbert, Nick; Breakthrough Research Unit, The University of Edinburgh, Edinburgh EH4 2XR

    2011-11-04

    Highlights: Black-Right-Pointing-Pointer Robust KAP1 phosphorylation in response to DNA damage in HCT116 cells. Black-Right-Pointing-Pointer DNA repair foci are found in soluble chromatin. Black-Right-Pointing-Pointer Biophysical analysis reveals global chromatin fibre compaction after DNA damage. Black-Right-Pointing-Pointer DNA damage is accompanied by rapid linker histone dephosphorylation. -- Abstract: DNA is protected by packaging it into higher order chromatin fibres, but this can impede nuclear processes like DNA repair. Despite considerable research into the factors required for signalling and repairing DNA damage, it is unclear if there are concomitant changes in global chromatin fibre structure. In human cells DNA double strand break (DSB) formation triggers a signalling cascade resulting in H2AX phosphorylation ({gamma}H2AX), the rapid recruitment of chromatin associated proteins and the subsequent repair of damaged sites. KAP1 is a transcriptional corepressor and in HCT116 cells we found that after DSB formation by chemicals or ionising radiation there was a wave of, predominantly ATM dependent, KAP1 phosphorylation. Both KAP1 and phosphorylated KAP1 were readily extracted from cells indicating they do not have a structural role and {gamma}H2AX was extracted in soluble chromatin indicating that sites of damage are not attached to an underlying structural matrix. After DSB formation we did not find a concomitant change in the sensitivity of chromatin fibres to micrococcal nuclease digestion. Therefore to directly investigate higher order chromatin fibre structures we used a biophysical sedimentation technique based on sucrose gradient centrifugation to compare the conformation of chromatin fibres isolated from cells before and after DNA DSB formation. After damage we found global chromatin fibre compaction, accompanied by rapid linker histone dephosphorylation, consistent with fibres being more regularly folded or fibre deformation being stabilized by linker histones. We suggest that following DSB formation, although there is localised chromatin unfolding to facilitate repair, the bulk genome becomes rapidly compacted protecting cells from further damage.

  16. Exposure to refractory ceramic fibres in the metal industry.

    PubMed

    Linnainmaa, Markku; Kangas, Juhani; Mäkinen, Milja; Metsärinne, Sirpa; Tossavainen, Antti; Säntti, Jaakko; Veteli, Marika; Savolainen, Heikki; Kalliokoski, Pentti

    2007-08-01

    Refractory ceramic fibres (RCF) are used in thermal isolation in the metal industry where high temperatures are regularly employed. Asbestos materials were earlier commonly used for these purposes. In this work, two Finnish steel plants, three foundries and a repair shop were studied for the ceramic fibre exposure of their workers under normal production and during the replacement of oven insulation. Personal and stationary sampling was used together with a novel nasal lavage sampling for the evaluation of personal exposure. Fibres were counted with optical and electron microscopy and they were identified using an energy-dispersive X-ray analyser. Ceramic fibres were found in most production phases [range <0.01-0.29 fibres per cubic centimetre (f cm(-3))]. Considerably higher fibre counts were obtained during the maintenance work (range <0.01-14.2 f cm(-3)). Nasal sampling was found to correlate with the airborne fibre concentrations at the group level. The mean fibre concentrations varied from 34 to 6680 f ml(-1) of lavage liquid. Use of personal respiratory protectors diminished the exposure on the average as analysed in the lavage specimens, but the effect of respirator use did not appear clearly in the results. Because of the heat conditions, the workers used the respirators for a strict minimum period. A considerable exposure to RCF occurs in the studied plants. Its risk should be evaluated and managed more closely in view that the material is carcinogenic. Use of personal respiratory protectors should be encouraged. Their effective use could be verified by the nasal sampling for fibres after the work shift. PMID:17607019

  17. Relation Between Macular Retinal Ganglion Cell/Inner Plexiform Layer Thickness and Multifocal Electroretinogram Measures in Experimental Glaucoma

    PubMed Central

    Luo, Xunda; Patel, Nimesh B.; Rajagopalan, Lakshmi P.; Harwerth, Ronald S.; Frishman, Laura J.

    2014-01-01

    Purpose. We investigated relations between macular retinal ganglion cell plus inner plexiform layer (RGC+IPL) thickness and macular retinal function revealed by multifocal electroretinonography (mfERG) in a nonhuman primate model of experimental glaucoma. Methods. Retinal ganglion cell (RGC) structure and function were followed with spectral-domain optical coherence tomography (SD-OCT) and ERGs in five macaques with unilateral experimental glaucoma. Linear regression was used to study correlations in control (Con) and experimental (Exp) eyes between peripapillary retinal nerve fiber layer (RNFL) thickness, macular RGC+IPL thickness, multifocal photopic negative response (mfPhNR) and high-frequency multifocal oscillatory potentials (mfOP) in slow-sequence mfERG, and low-frequency component (mfLFC) in global-flash mfERG. We used ANOVA and paired t-tests to compare glaucoma-related mfERG changes between superior and inferior hemifields, foveal hexagon, inner three rings, and four quadrants of macula. Results. Average macular RGC+IPL and temporal RNFL thickness were strongly correlated (r2 = 0.90, P < 0.001). In hexagon-by-hexagon analysis, all three mfERG measures were correlated (P < 0.001) with RGC+IPL thickness for Con (r2, 0.33–0.51) and Exp eyes (r2, 0.17–0.35). The RGC structural and functional metrics decreased as eccentricity increased. The reduction in amplitude of mfERG measures in Exp eyes relative to Con eyes was proportionally greater, in general, than the relative thinning of RGC+IPL at the same location for eyes in which structural loss was not evident, or mild to moderate. Although not statistically significant, percent amplitude reduction of mfERG measures was greatest in the inferior temporal quadrant. Conclusions. Macular RGC+IPL thickness and mfERG measures of RGC function can be complementary tools in assessing glaucomatous neuropathy. PMID:24970256

  18. Spraying asymmetry into functional membranes layer-by-layer.

    PubMed

    Krogman, Kevin C; Lowery, Joseph L; Zacharia, Nicole S; Rutledge, Gregory C; Hammond, Paula T

    2009-06-01

    As engineers strive to mimic the form and function of naturally occurring materials with synthetic alternatives, the challenges and costs of processing often limit creative innovation. Here we describe a powerful yet economical technique for developing multiple coatings of different morphologies and functions within a single textile membrane, enabling scientists to engineer the properties of a material from the nanoscopic level in commercially viable quantities. By simply varying the flow rate of charged species passing through an electrospun material during spray-assisted layer-by-layer deposition, individual fibres within the matrix can be conformally functionalized for ultrahigh-surface-area catalysis, or bridged to form a networked sublayer with complimentary properties. Exemplified here by the creation of selectively reactive gas purification membranes, the myriad applications of this technology also include self-cleaning fabrics, water purification and protein functionalization of scaffolds for tissue engineering. PMID:19377464

  19. Spraying asymmetry into functional membranes layer-by-layer

    NASA Astrophysics Data System (ADS)

    Krogman, Kevin C.; Lowery, Joseph L.; Zacharia, Nicole S.; Rutledge, Gregory C.; Hammond, Paula T.

    2009-06-01

    As engineers strive to mimic the form and function of naturally occurring materials with synthetic alternatives, the challenges and costs of processing often limit creative innovation. Here we describe a powerful yet economical technique for developing multiple coatings of different morphologies and functions within a single textile membrane, enabling scientists to engineer the properties of a material from the nanoscopic level in commercially viable quantities. By simply varying the flow rate of charged species passing through an electrospun material during spray-assisted layer-by-layer deposition, individual fibres within the matrix can be conformally functionalized for ultrahigh-surface-area catalysis, or bridged to form a networked sublayer with complimentary properties. Exemplified here by the creation of selectively reactive gas purification membranes, the myriad applications of this technology also include self-cleaning fabrics, water purification and protein functionalization of scaffolds for tissue engineering.

  20. Estimation of axial stiffness of plant fibres from compaction of non-woven mats

    NASA Astrophysics Data System (ADS)

    Gamstedt, E. K.; Bommier, E.; Madsen, B.

    2014-03-01

    Plant fibres are known to show a large variability in stiffness, which makes it time-consuming to experimentally characterize this property by conventional tensile testing. In this work, an alternative method is used, where the average fibre stiffness is back-calculated from compaction tests of in-plane randomly oriented fibre mats. The model by Toll is used to relate the load-displacement curve from the test to the Young modulus of the fibre, taking into account the natural variability in fibre cross section. Several tests have been performed on hemp fibre mats and compared with results from single-fibre tensile testing. The average back-calculated Young's modulus of the fibres was 45 GPa, whereas the average value from tensile testing ranged from 30 to 60 GPa. The straightforward compaction test can be useful in ranking of fibre stiffness, provided that the mat is composed of well-separated fibres and not of twisted yarns.

  1. Epigenetic control of skeletal muscle fibre type.

    PubMed

    Baar, K

    2010-08-01

    Adult muscle is extremely plastic. However, the muscle precursor cells associated with those fibres show stable and heritable differences in gene expression indicative of epigenetic imprinting. Epigenetic processes in the development of skeletal muscle have been appreciated for over a decade; however, there are a paucity of studies looking at whether epigenetics determines the phenotype of adult and/or ageing skeletal muscle. This review presents the evidence that epigenetics plays a role in determining adult muscle function and a series of unanswered questions that would greatly increase our understanding of how epigenetics works in adult muscle. With the increased interest in epigenetics, over the next few years this field will begin to unfold in unimaginable directions. PMID:20345412

  2. Cephalic tetanus studied with single fibre EMG.

    PubMed Central

    Fernandez, J M; Ferrandiz, M; Larrea, L; Ramio, R; Boada, M

    1983-01-01

    In a case of cephalic tetanus with left facial spasms and trismus, the repetitive stimulation of the left facial nerve at 3, 10 and 20 Hz showed no facilitation or decrement. The amplitudes of the blink reflex were 50% lower on the affected side. The silent period of the masseter muscles was shortened. Concentric needle examination of the masseters and left facial EMG of the left frontalis muscle showed increased jitter and blocking in a significant proportion of the recorded potentials. Both jitter and blocking improved on higher innervation rates. All electrophysiological findings were normal on the second examination when the patient was asymptomatic. The single fibre EMG findings point to a presynaptic defect in the neuromuscular transmission in human tetanus. PMID:6311990

  3. Fibre bundle framework for quantum fault tolerance

    NASA Astrophysics Data System (ADS)

    Zhang, Lucy Liuxuan; Gottesman, Daniel

    2014-03-01

    We introduce a differential geometric framework for describing families of quantum error-correcting codes and for understanding quantum fault tolerance. In particular, we use fibre bundles and a natural projectively flat connection thereon to study the transformation of codewords under unitary fault-tolerant evolutions. We'll explain how the fault-tolerant logical operations are given by the monodromy group for the bundles with projectively flat connection, which is always discrete. We will discuss the construction of the said bundles for two examples of fault-tolerant families of operations, the string operators in the toric code and the qudit transversal gates. This framework unifies topological fault tolerance and fault tolerance based on transversal gates, and is expected to apply for all unitary quantum fault-tolerant protocols.

  4. Unmyelinated fibres and Schwann cells of sural nerve in neuropathy.

    PubMed

    Behse, F; Buchthal, F; Carlsen, F; Knappeis, G G

    1975-09-01

    Electron micrographs of 45 sural nerves from patients with acquired (22) or heredodegenerative neuropathy (23) were analysed with respect to the number of unmyelinated nerve fibres, 37 nerves with respect to the number of Schwann cell sub-units and of structures connected with Schwann cells. Findings were compared with those in 6 nerves from control subjects and referred to the total number rather than to the number per mm2 to eliminate error due to increase in the transverse endoneurial area, present in more than half the diseased nerves. Ninety-one per cent of the diseased nerves showed one or several abnormalities in unmyelinated fibres of their Schwann cells. The best indicator of fibre loss was an increase in the number of Schwann cell sub-units devoid of axons, found in more than half the nerves. This was the only abnormality related with decrease in number of myelinated fibres. The increase in number of empty Schwann cell sub-units was due both to loss of unmyelinated nerve fibres and to proliferation of Schwann cells. Proliferation was indicated by the higher incidence of Schwann cell nuclei in cross-sections of diseased nerves than in controls. The earliest sign of involvement was an increase in number of profiles and of small isolated Schwann cell projections, observed in 33 of 37 diseased nerves, as the only abnormality in 7 nerves. The number of unmyelinated nerve fibres by itself was of little value to indicate loss of fibres, since regeneration often replaced or more than replaced degenerated fibres. Regeneration was indicated by an increase in number or incidence of small unmyelinated fibres, present in nearly half of 45 diseased nerves; and by an increased in the total number, present in a third of the nerves. An increase in the number of collagen pockets and of fibres undergoing degeneration (loss of organelles) and a decrease in the number of unmyelinated fibres per Schwann cell sub-units was present in only a quarter to a third of diseased nerves and was not related to other criteria of loss of fibres or of regneration. PMID:171027

  5. Diagnostics of the thick carbon fibre z-pinch

    SciTech Connect

    Davies, H.; Lorenz, A.; Kravarik, J.; Kubes, P.

    1997-05-05

    Results of a recent experiment on the IMP generator (11 kJ, 600 kV) at Imperial College are presented 360 {mu}m carbon fibres were used. The plasma was diagnosed with time resolved (from PIN diodes) and time integrated (pinhole camera) x-ray diagnostics, and time resolved optical emission diagnostics. The plasma was found to expand little during the main current pulse. Fragments of fibre recovered from the machine indicated that <1% of the fibre had been ionised. The x-ray diagnostics revealed a low-temperature, narrow diameter coronal plasma.

  6. Electrostriction mechanism of Bragg grating formation in germanosilicate fibres

    SciTech Connect

    Neustruev, V B

    2001-11-30

    An electrostriction model is proposed for the photorefractive effect observed during the writing of Bragg gratings in germanosilicate fibres. Electrostriction is caused by a spatial charge grating formed upon the exposure to UV radiation. According to our estimate, the contribution of electrostriction to the photorefractive effect under real writing conditions is comparable with the contribution from colour centres and exceeds the contribution from the electrooptical effect by more than an order of magnitude. The electrostriction model explains the production of the IIA type Bragg grating in fibres with a high content of germanium in the core, as well as a number of effects that could not be explained earlier. (optical fibres)

  7. FT Raman microscopy of untreated natural plant fibres

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Farwell, D. W.; Webster, D.

    1997-11-01

    The application of FT-Raman microscopy to the non-destructive analysis of natural plant fibres is demonstrated with samples of flax, jute, ramie, cotton, kapok, sisal and coconut fibre. Vibrational assignments are proposed and characteristic features of each material are presented. Samples were not pre-treated chemically before analysis and were used directly from their respective storage collection; the adaptation of the Raman microscopic technique to the identification of specimens of natural fibres in archaeological burial sites is explored for its forensic potential.

  8. All-fibre ytterbium laser tunable within 45 nm

    SciTech Connect

    Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S; Kurkov, A S

    2007-12-31

    A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

  9. Luminescent optical fibre sensor for UV-A detection

    NASA Astrophysics Data System (ADS)

    Miluski, Piotr; Dorosz, Dominik; Kochanowicz, Marcin; Zmojda, Jacek; Dorosz, Jan

    2014-11-01

    The article presents polymer optical fibre with sensitive luminescence cladding used for ultraviolet detection. The construction of polymethyl metacrylate (PMMA) fibre coated by organic dye doped polyurethane film is presented. The Tinopal (fluorescent optical brightener) incorporated into the polyurethane coating was used as UV indicator. The chosen dye allowed to direct UV-A detection with luminescence emission in visible range. The construction and fabrication process of UV sensitive polymer fibre is shown. The experimentally obtained characteristic using Nd: YAG (355nm) is presented. The high relative sensitivity up to 0.27mW-1 was obtained. It has been pointed potential applications of fabricated senor.

  10. Assessing assumptions of a combined structure-function index

    PubMed Central

    Swanson, William H; Horner, Douglas G

    2015-01-01

    Purpose Medeiros et al. developed a combined structure-function index for glaucoma by combining two ganglion cell models developed by Harwerth et al. The current study assessed assumptions of the Medeiros combined structure-function index by evaluating whether the two Harwerth models gave similar distributions of ganglion cells in an independent dataset. Methods The Harwerth models were applied to our previously published data for retinal nerve fibre layer (RNFL) thickness (Stratus OCT 3.4) and visual field sensitivities (24-2 SITA Standard) from one eye each of 51 patients with glaucoma and 62 age-similar control subjects free of eye disease. RNFL thicknesses and perimetric sensitivities were converted to ganglion cell numbers using the Harwerth model for perimetry and the Harwerth model for RNFL. These two estimates of ganglion cell number were compared for the inferior temporal (IT) and superior temporal (ST) sectors of the optic disc and the corresponding visual field locations. Comparisons were made with 14 visual field locations per sector (including a point in the macula for the inferior temporal sector) and with 13 locations (no point in the macula). Data for controls and patients were analysed separately, comparing mean values for RNFL perimetry models. Bonferroni correction was applied to control for repeated tests of significance. The difference between mean values for the RNFL and perimetry models was quantified by equating the means for controls through reduction of the assumed axon diameter used by the RNFL model. Results For the control group, the Harwerth RNFL model yielded smaller mean number of retinal ganglion cells than the Harwerth perimetry model, 23–47% lower (t > 13, p < 0.0001). This corresponded to mean axon diameters from 0.48 to 0.69 μm, with the smallest axons when the 14th location in the macula was included. With these new axon diameters, estimates of ganglion cell numbers for patients were still lower than for the RNFL model, by 19–28% (t > 6.5, p < 0.0001). Conclusions The Harwerth RNFL model consistently gave lower ganglion cell numbers than the Harwerth perimetry model, and this discordance persisted in patients even after reducing assumed axon diameter for controls. This finding contradicts the assumptions of the Medeiros structure-function index. PMID:25604956

  11. Nitroxide radicals. Controlled release from and transport through biomimetic and hollow fibre membranes.

    PubMed

    Kocherginsky, N M; Grishchenko, A B; Osipov, A N; Koh, S N

    2001-03-01

    Stable nitroxide radicals have found wide applications in chemistry and biology and they have some potential applications in medicine due to their antioxidant properties. Nitrocellulose filters impregnated with lipid-like substances are used as an imitation of biomembranes and could be used as a controlled drug release vehicle, while experiments with hollow fibres can be useful in the modelling of a drug delivery via blood vessels. This paper describes mechanisms of the nitroxide transport in four different model systems, i.e. a) exit of nitroxide into aqueous solution from porous nitrocellulose filters, impregnated with organic solvents, b) transport of nitroxides through the impregnated membrane from one into another aqueous solution, c) transport of nitroxides from bulk phase of organic solvents through the impregnated membrane into aqueous phase with ascorbic acid, and d) transport of nitroxides from liquid organic phase into aqueous solution through porous hollow fibres. The results are analysed in terms of mass transfer resistance of a membrane, organic and aqueous phase, based on nitroxide diffusion and distribution coefficients. Ascorbic acid reduced nitroxides in water and enhanced the rate of their transfer due to the decrease of transport resistance of unstirred aqueous layers. It is demonstrated that in the case of biomembranes the rate limiting step could be the transport through unstirred aqueous layers and membrane/water interface. PMID:11264901

  12. Effects of high intensity canoeing training on fibre area and fibre type in the latissimus dorsi muscle.

    PubMed Central

    Baker, S J; Hardy, L

    1989-01-01

    A high intensity short duration exercise training programme was undertaken by nine subjects on three occasions each week for nine weeks. Muscle samples from the latissimus dorsi were taken by needle biopsy, at rest, before and after training. The results revealed that there was no change in either Type I or Type II muscle fibre distribution following training. Type I fibre area did not alter significantly as a result of the training stress. Mean cross-sectional area of Type II fibres was 82 per cent greater post-training than pre-training. Images Figure 1 Figure 2 PMID:2730995

  13. Synthesis and characterization of copper, polyimide and TIPS-pentacene layers for the development of a solution processed fibrous transistor

    NASA Astrophysics Data System (ADS)

    Van Genabet, B.; Schwarz, A.; Bruneel, E.; Rambausek, L.; Van Driessche, I.; Van Langenhove, L.

    2011-12-01

    A study was performed for the development of a flexible organic field effect transistor starting from a polyester fibre as substrate material. Focus of subsequent layer deposition was on low temperature soluble processes to allow upscaling. Gate layer consists out of a pyrrole polymerization and copper coating step. Polyimide dielectric layer was deposited using dipcoating. Gold electrodes were vacuum evaporated and patterned via mask fibre shadowing. The active layer consisted of a soluble p-type TIPS-pentacene organic semiconductor. Different deposition techniques have been examined. Considerable progress in development of a transistor has been made.

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

    PubMed

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

    2015-04-01

    We demonstrate a spray pyrolysis method to grow carbon nanotubes (CNTs) with high degree of crystallinity, aspect ratio and degree of alignment on a variety of different substrates, such as conventional steel, carbon fibres (CF) and ceramics. The process consists in the chemical vapour deposition of both a thin SiO2 layer and CNTs that subsequently grow on this thin layer. After CNT growth, increases in specific surface by factors of 1000 and 30 for the steel and CF samples, respectively, are observed. CNTs growth on ceramic surfaces results in a surface resistance of 37.5 Ohm/sq. When using conventional steel as a rector tube, we observed CNTs growth rates of 0.6 g/min. Details of nanotube morphology and the growth mechanism are discussed. Since the method discussed here is highly versatile, it opens up a wide variety of applications in which specific substrates could be used in combination with CNTs. PMID:26353505

  15. The role of dietary fibre in inflammatory bowel disease.

    PubMed

    Pituch-Zdanowska, Aleksandra; Banaszkiewicz, Aleksandra; Albrecht, Piotr

    2015-01-01

    The aetiology of inflammatory bowel diseases (IBD), which are primarily Crohn's disease and ulcerative colitis, still remains unclear, while the incidence of IBD is constantly increasing, especially in the industrialised countries. Among genetic, environmental, and immunological factors, changes in the composition of the intestinal microflora and diet are indicated as very important in initiating and sustaining inflammation in patients with IBD. Above all nutrients dietary fibre is an especially important component of diet in the context of IBD. A potentially protective effect of high-fibre diet on intestinal disorders was described as early as in 1973. Several trials performed in animal models of IBD and human studies have reported that supplementation of some types of dietary fibre can prolong remission and reduce lesions of the intestinal mucosa during the course of the disease. This paper presents the current state of knowledge on the effects of dietary fibre in IBD. PMID:26516378

  16. Propagation of light in a circular array of elliptical fibres

    NASA Astrophysics Data System (ADS)

    Alexeyev, C. N.; Milione, G.; Pogrebnaya, A. O.; Yavorsky, M. A.

    2016-02-01

    We have studied transformation of discrete light beams in circular arrays of elliptical fibres, in which the orientation of ellipses' axes linearly depends on the angular position of the fibre in the array and makes an half-integer number p of full rotations while tracing along its contour. We have derived analytical expressions for the spectra and supermodes that allow for evanescent coupling between the fibres in the next-neighbour approximation. We have studied the transformative properties of such an array and shown that it can generate cylindrical vector beams (CVBs) of TE and TM types. We have shown that the type of generated beam depends on the orientation of linear polarization of the incident beam. In this way, the circular array of strongly elliptical fibres enables polarization control over the type of the generated CVB. We have also shown that such arrays can change the topological charge of an incoming discrete optical vortex by the doubled array's index p.

  17. Applications of optical fibres at Lublin University of Technology

    NASA Astrophysics Data System (ADS)

    Kacejko, Piotr; Wójcik, Waldemar

    2015-12-01

    The article contains a brief history and present days of research and education in application of optical fibres at Lublin University of Technology. It also presents the potential of research groups working at the University.

  18. The Formation and Binding of Gold Nanoparticles onto Wool Fibres

    NASA Astrophysics Data System (ADS)

    Johnston, James H.; Burridge, Kerstin A.; Kelly, Fern M.

    2009-07-01

    This paper presents the novel use of nanosize gold with different plasmon resonance colours, as stable colourfast colourants on wool fibres for use in high quality fabrics and textiles. The gold nanoparticles are synthesised by the controlled reduction of Au3+ in the AuCl4- complex to Au0 onto the surface of the wool where they attach to the S in the cystine amino acids in wool keratin proteins. Scanning electronmicroscopy shows the nanoparticles are present on the cuticles of the fibre surface and are concentrated at the edges of these cuticles. EDS analysis shows a strong correlation of Au with S and X-ray photoelectron spectroscopy suggests Au-S bond formation. Hence the nanogold colourants are chemically bound to the wool fibre surface and do not fade as traditional organic dyes do. A range of coloured fibres have been produced.

  19. Meniscus on a shaped fibre: singularities and hodograph formulation

    PubMed Central

    Alimov, Mars M.; Kornev, Konstantin G.

    2014-01-01

    Using the method of matched asymptotic expansions, the problem of the capillary rise of a meniscus on the complex-shaped fibres was reduced to a nonlinear problem of determination of a minimal surface. This surface has to satisfy a special boundary condition at infinity. The proposed formulation allows one to interpret the meniscus problem as a problem of flow of a fictitious non-Newtonian fluid through a porous medium. As an example, the shape of a meniscus on a fibre of an oval cross section was analysed employing Chaplygin's hodograph transformation. It was discovered that the contact line may form singularities even if the fibre has a smooth profile: this statement was illustrated with an oval fibre profile having infinite curvature at two endpoints. PMID:25104910

  20. Dietary fibre in the management of diabetes mellitus: a review.

    PubMed

    Sels, J P; Postmes, T J; Wolffenbuttel, B H; Nieuwenhuijzen Kruseman, A C

    1991-06-01

    The role of nutritional habits in the emergence of certain diseases in the western world enhanced the interest in nutrition. As a consequence, the importance of what is now called dietary fibre has changed from an unnecessary constituent of plant food to an essential element of healthy nutrition. Several diabetes associations now advise including a defined amount of dietary fibre in an up-to-date dietary treatment of diabetes mellitus. However, there are still many controversies and unanswered questions. This paper reviews briefly the problems of definition and determination of dietary fibre. The possible mechanisms of action are discussed, and a survey of data in the literature that deal with the effect of long-term ingestion of increased amounts of dietary fibre on carbohydrate and lipid metabolism, safety and applicability is presented. PMID:1656288

  1. Conduction velocity in myelinated nerve fibres of Xenopus laevis

    PubMed Central

    Hutchinson, N. A.; Koles, Z. J.; Smith, R. S.

    1970-01-01

    1. The relationship between conduction velocity and nerve diameter in single myelinated nerve fibres from Xenopus laevis was measured and was found to be linear. 2. The relationship between conduction velocity and temperature in nerve fibres of various diameters was measured over the range 15-30° C and was found to be linear for each fibre. 3. The slope of the conduction velocity—temperature relationship was directly proportional to the diameter of the nerve fibre. 4. The form of the conduction velocity—temperature relationship was determined by numerical solution of the Frankenhaeuser—Huxley equations for the case of a propagated action potential. The computation predicted that conduction velocity is a linear function of temperature over the range studied. PMID:5500723

  2. 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.

  3. Graphene chiral liquid crystals and macroscopic assembled fibres

    NASA Astrophysics Data System (ADS)

    Xu, Zhen; Gao, Chao

    2011-12-01

    Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles.

  4. Acetylation of banana fibre to improve oil absorbency.

    PubMed

    Teli, M D; Valia, Sanket P

    2013-01-30

    Oil spill leaves detrimental effects on the environment, living organisms and economy. In the present work, an attempt is made to provide an efficient, easily deployable method of cleaning up oil spills and recovering of the oil. The work reports the use of banana fibres which were acetylated for oil spill recovery. The product so formed was characterized by FT-IR, TG, SEM and its degree of acetylation was also evaluated. The extent of acetylation was measured by weight percent gain. The oil sorption capacity of the acetylated fibre was higher than that of the commercial synthetic oil sorbents such as polypropylene fibres as well as un-modified fibre. Therefore, these oil sorption-active materials which are also biodegradable can be used to substitute non-biodegradable synthetic materials in oil spill cleanup. PMID:23218302

  5. Adaptive dynamic FBG interrogation utilising erbium-doped fibre

    NASA Astrophysics Data System (ADS)

    John, R. N.; Read, I.; MacPherson, W. N.

    2013-04-01

    A dynamic fibre Bragg grating interrogation scheme is investigated using two-wave mixing in erbium-doped fibre, capable of adapting to quasistatic strain and temperature drifts. An interference pattern set up in the erbium-doped fibre creates, due to the photorefractive effect, a dynamic grating capable of wavelength demodulating the FBG signal. The presence of a dynamic grating was verified and then dynamic strain signals from a fibre stretcher were measured. The adaptive nature of the technique was successfully demonstrated by heating the FBG while it underwent dynamic straining leading to detection unlike an alternative arrayed waveguide grating system which simultaneously failed detection. Two gratings were then wavelength division multiplexed with the signal grating receiving approximately 30dB greater signal showing that there was little cross talk in the system.

  6. The role of dietary fibre in inflammatory bowel disease

    PubMed Central

    Banaszkiewicz, Aleksandra; Albrecht, Piotr

    2015-01-01

    The aetiology of inflammatory bowel diseases (IBD), which are primarily Crohn's disease and ulcerative colitis, still remains unclear, while the incidence of IBD is constantly increasing, especially in the industrialised countries. Among genetic, environmental, and immunological factors, changes in the composition of the intestinal microflora and diet are indicated as very important in initiating and sustaining inflammation in patients with IBD. Above all nutrients dietary fibre is an especially important component of diet in the context of IBD. A potentially protective effect of high-fibre diet on intestinal disorders was described as early as in 1973. Several trials performed in animal models of IBD and human studies have reported that supplementation of some types of dietary fibre can prolong remission and reduce lesions of the intestinal mucosa during the course of the disease. This paper presents the current state of knowledge on the effects of dietary fibre in IBD. PMID:26516378

  7. Exploiting multimode waveguides for pure fibre-based imaging

    PubMed Central

    Čižmár, Tomáš; Dholakia, Kishan

    2012-01-01

    There has been an immense drive in modern microscopy towards miniaturization and fibre-based technology. This has been necessitated by the need to access hostile or difficult environments in situ and in vivo. Strategies to date have included the use of specialist fibres and miniaturized scanning systems accompanied by ingenious microfabricated lenses. Here we present a novel approach for this field by utilizing disordered light within a standard multimode optical fibre for lensless microscopy and optical mode conversion. We demonstrate the modalities of bright- and dark-field imaging and scanning fluorescence microscopy at acquisition rates that allow observation of dynamic processes such as Brownian motion of mesoscopic particles. Furthermore, we show how such control can realize a new form of mode converter and generate various types of advanced light fields such as propagation-invariant beams and optical vortices. These may be useful for future fibre-based implementations of super-resolution or light-sheet microscopy. PMID:22929784

  8. The Formation and Binding of Gold Nanoparticles onto Wool Fibres

    SciTech Connect

    Johnston, James H.; Burridge, Kerstin A.; Kelly, Fern M.

    2009-07-23

    This paper presents the novel use of nanosize gold with different plasmon resonance colours, as stable colourfast colourants on wool fibres for use in high quality fabrics and textiles. The gold nanoparticles are synthesised by the controlled reduction of Au{sup 3+} in the AuCl{sub 4}{sup -} complex to Au{sup 0} onto the surface of the wool where they attach to the S in the cystine amino acids in wool keratin proteins. Scanning electronmicroscopy shows the nanoparticles are present on the cuticles of the fibre surface and are concentrated at the edges of these cuticles. EDS analysis shows a strong correlation of Au with S and X-ray photoelectron spectroscopy suggests Au-S bond formation. Hence the nanogold colourants are chemically bound to the wool fibre surface and do not fade as traditional organic dyes do. A range of coloured fibres have been produced.

  9. Dietary fibre and colon cancer: epidemiologic and experimental evidence.

    PubMed Central

    Reddy, B S

    1980-01-01

    Epidemiologic studies have identified two dietary factors, a relatively high intake of fat and a relatively low intake of fibre, that are associated with colon cancer in humans. However, a recent study has shown a low risk of large bowel cancer in a rural Finnish population with a high dietary intake of fat, but also a high intake of fibre. Observations in humans and studies in animals have indicated that dietary fibre may protect against colon carcinogenesis by binding bile acids in the intestinal tract, by a direct effect on the colonic mucosa and by an indirect effect on the metabolism of carcinogens. The strength of protection varies with the type of fibre. PMID:6254626

  10. Desquamative interstitial pneumonia associated with chrysotile asbestos fibres.

    PubMed

    Freed, J A; Miller, A; Gordon, R E; Fischbein, A; Kleinerman, J; Langer, A M

    1991-05-01

    The drywall construction trade has in the past been associated with exposure to airborne asbestos fibres. This paper reports a drywall construction worker with 32 years of dust exposure who developed dyspnoea and diminished diffusing capacity, and showed diffuse irregular opacities on chest radiography. He did not respond to treatment with corticosteroids. Open lung biopsy examination showed desquamative interstitial pneumonia. Only a single ferruginous body was seen on frozen section, but tissue examination by electron microscopy showed an extraordinary pulmonary burden of mineral dust with especially high concentrations of chrysotile asbestos fibres. This report emphasises the need to consider asbestos fibre as an agent in the aetiology of desquamative interstitial pneumonia. The coexistent slight interstitial fibrosis present in this case is also considered to have resulted from exposure to mineral dust, particularly ultramicroscopic asbestos fibres. PMID:1645584

  11. 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.

  12. Small fibre pathology in patients with fibromyalgia syndrome.

    PubMed

    Üçeyler, Nurcan; Zeller, Daniel; Kahn, Ann-Kathrin; Kewenig, Susanne; Kittel-Schneider, Sarah; Schmid, Annina; Casanova-Molla, Jordi; Reiners, Karlheinz; Sommer, Claudia

    2013-06-01

    Fibromyalgia syndrome is a clinically well-characterized chronic pain condition of high socio-economic impact. Although the pathophysiology is still unclear, there is increasing evidence for nervous system dysfunction in patients with fibromyalgia syndrome. In this case-control study we investigated function and morphology of small nerve fibres in 25 patients with fibromyalgia syndrome. Patients underwent comprehensive neurological and neurophysiological assessment. We examined small fibre function by quantitative sensory testing and pain-related evoked potentials, and quantified intraepidermal nerve fibre density and regenerating intraepidermal nerve fibres in skin punch biopsies of the lower leg and upper thigh. The results were compared with data from 10 patients with monopolar depression without pain and with healthy control subjects matched for age and gender. Neurological and standard neurophysiological examination was normal in all patients, excluding large fibre polyneuropathy. Patients with fibromyalgia syndrome had increased scores in neuropathic pain questionnaires compared with patients with depression and with control subjects (P < 0.001 each). Compared with control subjects, patients with fibromyalgia syndrome but not patients with depression had impaired small fibre function with increased cold and warm detection thresholds in quantitative sensory testing (P < 0.001). Investigation of pain-related evoked potentials revealed increased N1 latencies upon stimulation at the feet (P < 0.001) and reduced amplitudes of pain-related evoked potentials upon stimulation of face, hands and feet (P < 0.001) in patients with fibromyalgia syndrome compared to patients with depression and to control subjects, indicating abnormalities of small fibres or their central afferents. In skin biopsies total (P < 0.001) and regenerating intraepidermal nerve fibres (P < 0.01) at the lower leg and upper thigh were reduced in patients with fibromyalgia syndrome compared with control subjects. Accordingly, a reduction in dermal unmyelinated nerve fibre bundles was found in skin samples of patients with fibromyalgia syndrome compared with patients with depression and with healthy control subjects, whereas myelinated nerve fibres were spared. All three methods used support the concept of impaired small fibre function in patients with fibromyalgia syndrome, pointing towards a neuropathic nature of pain in fibromyalgia syndrome. PMID:23474848

  13. SOLITONS: Nonreciprocal dynamics of pulses in a nonlinear inhomogeneous fibre

    NASA Astrophysics Data System (ADS)

    Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.

    2007-08-01

    The conditions, under which the nonreciprocity of the frequency modulation rate and pulse duration as well as the spectral nonreciprocity in fibres with different types of inhomogeneity of nonlinearity and group-velocity dispersion appear, are studied for the Gaussian and hyperbolic secant frequency-modulated pulses. Strong compression nonreciprocity is found in fibres with an alternating group-velocity dispersion periodically changing over its length.

  14. 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)

  15. Measurement of magnetic field using Rayleigh backscattering in optical fibres

    SciTech Connect

    Wuilpart, M.; Caucheteur, C.; Goussarov, A.; Aerssens, M.; Massaut, V.; Megret, P.

    2011-07-01

    In this paper, we investigate the use of optical reflectometry in optical fibres for the measurement of magnetic field. The dedicated application concerns the measurement of plasma current in the fusion reactor. The measurement is based on the rotation of the polarization state of the Rayleigh backscattered signal when an optical pulse is launched in the fibre. Particular care has been undertaken to evaluate the impact of linear birefringence on the measurement performance. (authors)

  16. G-fibre cell wall development in willow stems during tension wood induction

    PubMed Central

    Gritsch, Cristina; Wan, Yongfang; Mitchell, Rowan A. C.; Shewry, Peter R.; Hanley, Steven J.; Karp, Angela

    2015-01-01

    Willows (Salix spp.) are important as a potential feedstock for bioenergy and biofuels. Previous work suggested that reaction wood (RW) formation could be a desirable trait for biofuel production in willows as it is associated with increased glucose yields, but willow RW has not been characterized for cell wall components. Fasciclin-like arabinogalactan (FLA) proteins are highly up-regulated in RW of poplars and are considered to be involved in cell adhesion and cellulose biosynthesis. COBRA genes are involved in anisotropic cell expansion by modulating the orientation of cellulose microfibril deposition. This study determined the temporal and spatial deposition of non-cellulosic polysaccharides in cell walls of the tension wood (TW) component of willow RW and compared it with opposite wood (OW) and normal wood (NW) using specific antibodies and confocal laser scanning microscopy and transmission electron microscopy. In addition, the expression patterns of an FLA gene (SxFLA12) and a COBRA-like gene (SxCOBL4) were compared using RNA in situ hybridization. Deposition of the non-cellulosic polysaccharides (1–4)-β-D-galactan, mannan and de-esterified homogalacturonan was found to be highly associated with TW, often with the G-layer itself. Of particular interest was that the G-layer itself can be highly enriched in (1–4)-β-D-galactan, especially in G-fibres where the G-layer is still thickening, which contrasts with previous studies in poplar. Only xylan showed a similar distribution in TW, OW, and NW, being restricted to the secondary cell wall layers. SxFLA12 and SxCOBL4 transcripts were specifically expressed in developing TW, confirming their importance. A model of polysaccharides distribution in developing willow G-fibre cells is presented. PMID:26220085

  17. G-fibre cell wall development in willow stems during tension wood induction.

    PubMed

    Gritsch, Cristina; Wan, Yongfang; Mitchell, Rowan A C; Shewry, Peter R; Hanley, Steven J; Karp, Angela

    2015-10-01

    Willows (Salix spp.) are important as a potential feedstock for bioenergy and biofuels. Previous work suggested that reaction wood (RW) formation could be a desirable trait for biofuel production in willows as it is associated with increased glucose yields, but willow RW has not been characterized for cell wall components. Fasciclin-like arabinogalactan (FLA) proteins are highly up-regulated in RW of poplars and are considered to be involved in cell adhesion and cellulose biosynthesis. COBRA genes are involved in anisotropic cell expansion by modulating the orientation of cellulose microfibril deposition. This study determined the temporal and spatial deposition of non-cellulosic polysaccharides in cell walls of the tension wood (TW) component of willow RW and compared it with opposite wood (OW) and normal wood (NW) using specific antibodies and confocal laser scanning microscopy and transmission electron microscopy. In addition, the expression patterns of an FLA gene (SxFLA12) and a COBRA-like gene (SxCOBL4) were compared using RNA in situ hybridization. Deposition of the non-cellulosic polysaccharides (1-4)-β-D-galactan, mannan and de-esterified homogalacturonan was found to be highly associated with TW, often with the G-layer itself. Of particular interest was that the G-layer itself can be highly enriched in (1-4)-β-D-galactan, especially in G-fibres where the G-layer is still thickening, which contrasts with previous studies in poplar. Only xylan showed a similar distribution in TW, OW, and NW, being restricted to the secondary cell wall layers. SxFLA12 and SxCOBL4 transcripts were specifically expressed in developing TW, confirming their importance. A model of polysaccharides distribution in developing willow G-fibre cells is presented. PMID:26220085

  18. Time Course of Macular and Peripapillary Inner Retinal Thickness in Non-arteritic Anterior Ischaemic Optic Neuropathy Using Spectral-Domain Optical Coherence Tomography

    PubMed Central

    Goto, Katsutoshi; Miki, Atsushi; Araki, Syunsuke; Mizukawa, Kenichi; Nakagawa, Masaki; Takizawa, Go; Ieki, Yoshiaki; Kiryu, Junichi

    2016-01-01

    ABSTRACT To report a time course of the ganglion cell complex (GCC) and circumpapillary retinal nerve fibre layer (cpRNFL) thicknesses using spectral-domain optical coherence tomography in patients with non-arteritic anterior ischaemic optic neuropathy (NAION), five patients with unilateral NAION were studied (the average age of 66.8 ± 7.8 years old). Forty-one age-matched normal controls were also enrolled. The GCC and cpRNFL thicknesses were measured at the initial visit and at 1, 3, 6, and 12 months using RTVue-100. The GCC thickness and the cpRNFL thickness of the patients were compared with those of the normal controls. The GCC thickness in the NAION patients was 96.49 μm at the initial visit, 84.28 μm at 1 month, 74.26 μm at 3 months, 71.23 μm at 6 months, and 69.51 μm at 12 months. The values at 1, 3, 6, and 12 months were significantly reduced (p < 0.01). The cpRNFL thickness at the initial visit was significantly increased, whereas the values at 6 and 12 months were significantly reduced (p < 0.01). The GCC thickness is more useful for the detection of retinal ganglion cell loss at an early stage than the cpRNFL thickness, because the GCC thickness is unaffected by optic disc swelling at the initial visit, unlike the cpRNFL thickness. PMID:27110047

  19. Induction of nuclear translocation of NF-kappaB in epithelial cells by respirable mineral fibres.

    PubMed

    Brown, D M; Beswick, P H; Donaldson, K

    1999-10-01

    A panel of mineral fibres has been studied for their ability to cause translocation of the transcription factor NF-kappaB to the nucleus in A549 lung epithelial cells. On the basis of inhalation studies, three fibres were designated as being carcinogenic-amosite asbestos, silicon carbide and refractory ceramic fibre 1 (RCF1)-or non-carcinogenic-man-made vitreous fibre (MMVF10), Code 100/475 glass fibre, and RCF4. The experiments were carried out at equal fibre number. It was hypothesized that carcinogenic fibres have greater free radical activity than non-carcinogenic fibres and that an oxidative stress produced in the lung after inhalation of fibres could cause translocation of the transcription factor NF-kappaB to the nucleus, where transcription of pro-inflammatory genes such as cytokines could occur. It was demonstrated that a simple oxidant, hydrogen peroxide, caused translocation in a time- and dose-dependent manner. The three carcinogenic fibres produced a significant dose-dependent translocation of NF-kappaB to the nucleus, whereas the non-carcinogenic fibres did not. Silicon carbide fibres were the most potent of the pathogenic fibres. MMVF10 was the most potent of the non-pathogenic fibres, causing significant nuclear translocation of NF-kappaB at high fibre number. Using three antioxidants, curcumin, pyrrolidine dithiocarbamate, and Nacystelin, translocation caused by carcinogenic fibres could be significantly reduced. The present study shows that a short-term in vitro assay can discriminate between pathogenic and non-pathogenic fibres in terms of a key pro-inflammatory event in epithelial cells. The mechanism of the activation of NF-kappaB by pathogenic fibres and its general applicability to other fibre types remain to be determined. PMID:10547584

  20. Endogenously triggered electrospun fibres for tailored and controlled antibiotic release.

    PubMed

    Dave, Rachna; Jayaraj, Prithi; Ajikumar, Puthuparampil K; Joshi, Hiren; Mathews, Tom; Venugopalan, Vayalam P

    2013-01-01

    The study was aimed at assessing the potential of enzyme-embedded antibiotic-releasing polycaprolactone (PCL)-based electrospun fibres for tunable drug delivery. This was attempted by incorporation of gentamicin sulphate (GS) in the biocompatible polymer (PCL) matrix, with the degradation of the matrix being ensured by co-impregnating a polymer-degrading enzyme (lipase). Single phase solutions were obtained by hydrophobic ion pairing of GS and surfactant coating of lipase with an anionic surfactant, docusate sodium salt Aerosol OT (AOT). By electrospinning the solution, we could produce PCL fibres containing 11% (w/w) GS-AOT and 28 U (w/w) lipase-AOT. However, sustained release of GS was not obtained. FESEM analysis showed that the fibres did not undergo the expected degradation. Subsequent experiments with unmodified lipase gave satisfactory results; the polymer underwent degradation displaying characteristic perforations in the fibres, suggestive of 'endo-attack'. By modulating the concentrations of lipase (1 to 28 U, w/w), we could obtain GS release rates that varied from 0.53 to 32 mg/ml/d. Accordingly, the lifetime of the fibres could be tuned (10 h to 25 days). The fibres showed excellent antibacterial activity against Staphylococcus aureus throughout their lifetime. PMID:23796032

  1. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    SciTech Connect

    Chamorovskiy, A Yu; Okhotnikov, Oleg G

    2012-11-30

    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  2. Structural study on methacrylamide-grafted Tussah silk fibroin fibres.

    PubMed

    Pavoni, Eleonora; Tozzi, Silvia; Tsukada, Masuhiro; Taddei, Paola

    2016-07-01

    Tussah silk fibroin fibres were modified by grafting with methacrylamide (MAA), with weight gains ranging between 2.6% and 71.4%. Raman and IR spectroscopic analyses showed that upon grafting the fibres underwent slight conformational changes towards a more unordered state, due to the covalent and hydrogen bonds interactions occurring between the polymer (polyMAA) and the amorphous domains of silk fibres. To test the stability towards alkaline hydrolysis, the untreated and MAA-grafted silk fibres (weight gain of 71.4%) were immersed in NaOH 5% at 50°C for different times; the IR and Raman spectroscopic techniques were utilized to elucidate the degradation mechanism as well as the rearrangements of the fibres induced by the treatment. Upon hydrolysis, both the untreated and grafted fibres underwent an enrichment in β-sheet conformation, due to the preferential removal of the unordered domains. As a result of the covalent interactions with silk fibroin, the polymer increased its stability towards alkaline hydrolysis, since its complete solubilization was avoided and the transformation of its CONH2 groups into COO(-) and COOH was delayed. Vibrational spectroscopy proved to be a valid technique to investigate the mechanism and the effects of the hydrolytic attack, which are both fundamental to design new-generation silk-based materials. PMID:27032490

  3. Investigation of Mechanical Properties of Steel Fibre- Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Ryabchikov, A.; Tamme, V.; Laurson, M.

    2015-11-01

    Steel fibre-reinforced concrete (SFRC) is widely used in the structural elements of buildings: industrial floors, slabs, walls, foundation, etc. When a load is applied to a fibre- reinforced composite consisting of a low-modulus matrix reinforced with high-strength, high- modulus fibres, the plastic flow of the matrix under stress transfers the load to the fibre; this results in high-strength, high-modulus material which determines the stiffness and stress of the composite. In this study the equivalent flexural strength, equivalent flexural ratio Re,3 and the compressing strength of SFRC are investigated. Notched test specimens with five different dosages of steel fibres (20, 25, 30, 35, 40 kg/m3) were prepared using industrial concrete. Determination of flexural tension strength was carried out according to the EU norm EVS-EN 14651:2005+A1:2007. The equivalent flexural strength and subsequent equivalent flexural ratio Re,3 of SFRC with a dosage of 20, 25, 30, 35 kg/m3 similar to their average values and with a dosage of 40 kg/m3 were 31% higher than their average values. The compressive strength of the steel fibre-reinforced concrete was slightly higher compared to plain concrete, except specimens with the dosage of 40 kg/m3 where the increase was 30%.

  4. Preparation of reactive fibre interfaces using multifunctional cellulose derivatives.

    PubMed

    Vega, Beatriz; Wondraczek, Holger; Bretschneider, Leonore; Näreoja, Tuomas; Fardim, Pedro; Heinze, Thomas

    2015-11-01

    Cellulose fibres have poor reactivity and limited potential for surface engineering with advanced chemical functionalization in water. In this work, cellulose fibres were decorated with azide functions by charge-directed self-assembly of a novel water-soluble multifunctional cellulose derivative yielding reactive fibres. Propargylamine and 1-ethynylpyrene were utilized as a proof of concept that alkyne molecules may react with the azide functions of the reactive fibres via copper(I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAc) reaction in mild conditions. Chemical characterization of the fibres was carried out using classical techniques such as Raman-, fluorescence-, and UV-vis spectroscopy. Among other techniques, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray spectroscopy (XPS), two-photon microscopy (TPM), and inductively coupled plasma mass spectrometry (ICP-MS) were useful tools for additional characterization of the fibres decorated with amino- or photoactive groups. The information gathered in this work might contribute to the basis for the preparation of reactive cellulose-based interfaces with potential application in CuAAc reactions. PMID:26256349

  5. Dietary fibre as an important constituent of the diet.

    PubMed

    Maćkowiak, Kalina; Torlińska-Walkowiak, Natalia; Torlińska, Barbara

    2016-01-01

    The intake of fibre in the diet of a child or an adult, through various foods (such as wholegrain foods, nuts, fruits and vegetables), plays an important role in reducing the risk and lowering the incidence of numerous diseases. The interest of researchers and consumers in the role of diet in the prevention or treatment of many illnesses, and maintaining the general and oral health, has been growing lately. The aim of our study was to underline the role of dietary fibre through its effects on many aspects of the human body and metabolism. Evidence has been found that dietary fibre from whole foods or supplements may reduce the risk of cardiovascular disease by improving serum lipids and reducing serum total and low-density lipoprotein (LDL) cholesterol concentrations in adults and children. Increased fibre content decreases the glycaemic index of foods, which leads to a significant improvement in glycaemic response. High fibre intake is associated with reduced risk of colorectal and breast cancer. In contemporary children, the reluctance to chew raw, hard plant foods may result in a risk of malocclusion and a lack of tooth wear, which cause the need for orthodontic intervention. Fibre consumption is associated with high nutritional value and antioxidant status of the diet, enhancing the effects on human health. PMID:26943307

  6. 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.

  7. Dietary fibre, complex carbohydrate and coronary artery disease.

    PubMed

    Anderson, J W

    1995-10-01

    Animal studies indicate that viscous, soluble fibres such as psyllium, oat gum, guar gum and pectin have substantial hypocholesterolemic effects. Epidemiologic data suggest that the intake of complex carbohydrate and dietary fibre is associated in an inverse manner to risk for coronary artery disease (CAD). Two long term clinical trials indicate that increasing soluble fibre intake as part of a low fat, low cholesterol diet reduces serum cholesterol concentration from 3 to 5% below that for the low fat, low cholesterol diet. Short term, controlled clinical trials indicate that oat bran or beans, in a metabolic ward setting, decrease serum cholesterol concentrations of hypercholesterolemic individuals by 10 to 12%. Studies of free-living hypercholesterolemic individuals document that incorporation of oat products, psyllium or guar gum into the diet decreases serum cholesterol by 6 to 8%. Other studies suggest that increased fibre intake may decrease blood pressure slightly, assist in weight management, alter blood clotting factors, and increase insulin sensitivity. Intake of dietary fibre and complex carbohydrate appear to have a protective role for CAD. Further controlled clinical trials are required to examine the role of fibre and complex carbohydrate in prevention or regression of CAD. PMID:7585294

  8. Nano zinc oxide-sodium alginate antibacterial cellulose fibres.

    PubMed

    Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Seo, Jongchul

    2016-01-01

    In the present study, antibacterial cellulose fibres were successfully fabricated by a simple and cost-effective procedure by utilizing nano zinc oxide. The possible nano zinc oxide was successfully synthesized by precipitation technique and then impregnated effectively over cellulose fibres through sodium alginate matrix. XRD analysis revealed the 'rod-like' shape alignment of zinc oxide with an interplanar d-spacing of 0.246nm corresponding to the (101) planes of the hexagonal wurtzite structure. TEM analysis confirmed the nano dimension of the synthesized zinc oxide nanoparticles. The presence of nano zinc oxide over cellulose fibres was evident from the SEM-EDS experiments. FTIR and TGA studies exhibited their effective bonding interaction. The tensile stress-strain curves data indicated the feasibility of the fabricated fibres for longer duration utility without any significant damage or breakage. The antibacterial studies against Escherichia coli revealed the excellent bacterial devastation property. Further, it was observed that when all the parameters remained constant, the variation of sodium alginate concentration showed impact in devastating the E. coli. In overall, the fabricated nano zinc oxide-sodium alginate cellulose fibres can be effectively utilized as antibacterial fibres for biomedical applications. PMID:26453887

  9. 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.

  10. Fibre systems for future astronomy: anomalous wavelength-temperature effects

    NASA Astrophysics Data System (ADS)

    Poppett, C. L.; Allington-Smith, J. R.

    2007-07-01

    Focal ratio degradation is an important property of optical fibres that determines the design and cost of instruments using fibres. Motivated by the importance of fibres in feeding instruments on Extremely Large Telescopes, the need for cryogenic-cooling to reduce thermal background and the desire for broad-band performance, we have studied the dependency of focal ratio degradation (FRD) on both temperature and wavelength. This shows a small but significant reduction in performance when cooled as expected from previous work. We also find an increase in FRD with wavelength broadly consistent with theory at room temperature but this dependency reverses in sign when the fibres are cooled to 77K, contrary to existing theory. We parameterize the wavelength dependency by an ad hoc extension to an existing model but it is clear that existing theory does not provide a good description of the operation of fibres in astronomical systems. This unexpected behaviour, which may relate to frozen-in stress from the manufacturing process, will need to be taken into account when designing future fibre systems.

  11. Plantain fibre bundles isolated from Colombian agro-industrial residues.

    PubMed

    Gañán, Piedad; Zuluaga, Robin; Restrepo, Adriana; Labidi, Jalel; Mondragon, Iñaki

    2008-02-01

    Comestible fruit production from Musaceas plants is an important economical activity in developing countries like Colombia. However, it generates a large amount of agro-industrial residues. Some of them are a potential resource of natural fibres, which can be used as reinforcement for composite materials. In this work, a series of commercial plantain (Musa AAB, cv "Dominico Harton") fibre bundles extracted from pseudostem, leaf sheath and rachis agricultural wastes were analyzed. Mechanical decortication and biological retting processes were used during fiber extraction. No significant differences in composition of vascular bundles were observed for both extraction processes. Gross morphological characteristics and mechanical behavior have been evaluated. Conducting tissues with spiral-like arrangement are observed attached to fibre bundles. This fact suggests a big amount of these tissues in commercial plantain plants. Both used extraction methods are not enough to remove them. Pseudostem fibre bundles have higher specific strength and modulus and lower strain at break than leaf sheath and rachis fibre bundles, having values comparable to other lignocellulosic fibres bundles. PMID:17350832

  12. Raman studies of gluten proteins aggregation induced by dietary fibres.

    PubMed

    Nawrocka, Agnieszka; Szymańska-Chargot, Monika; Miś, Antoni; Kowalski, Radosław; Gruszecki, Wiesław I

    2016-03-01

    Interactions between gluten proteins and dietary fibre preparations are crucial in the baking industry. The addition of dietary fibre to bread causes significant reduction in its quality which is influenced by changes in the structure of gluten proteins. Fourier transform Raman spectroscopy was applied to determine changes in the structure of gluten proteins modified by seven dietary fibres. The commercially available gluten proteins without starch were mixed with the fibres in three concentrations: 3%, 6% and 9%. The obtained results showed that all fibres, regardless of their origin, caused the same kind of changes i.e. decrease in the α-helix content with a simultaneous increase in the content of antiparallel-β-sheet. The results indicated that presence of cellulose was the probable cause of these changes, and lead to aggregation or abnormal folding of the gluten proteins. Other changes observed in the gluten structure concerning β-structures, conformation of disulphide bridges, and aromatic amino acid environment, depended on the fibres chemical composition. PMID:26471530

  13. A simplified immunohistochemical classification of skeletal muscle fibres in mouse.

    PubMed

    Kammoun, M; Cassar-Malek, I; Meunier, B; Picard, B

    2014-01-01

    The classification of muscle fibres is of particular interest for the study of the skeletal muscle properties in a wide range of scientific fields, especially animal phenotyping. It is therefore important to define a reliable method for classifying fibre types. The aim of this study was to establish a simplified method for the immunohistochemical classification of fibres in mouse. To carry it out, we first tested a combination of several anti myosin heavy chain (MyHC) antibodies in order to choose a minimum number of antibodies to implement a semi-automatic classification. Then, we compared the classification of fibres to the MyHC electrophoretic pattern on the same samples. Only two anti MyHC antibodies on serial sections with the fluorescent labeling of the Laminin were necessary to classify properly fibre types in Tibialis Anterior and Soleus mouse muscles in normal physiological conditions. This classification was virtually identical to the classification realized by the electrophoretic separation of MyHC. This immunohistochemical classification can be applied to the total area of Tibialis Anterior and Soleus mouse muscles. Thus, we provide here a useful, simple and time-efficient method for immunohistochemical classification of fibres, applicable for research in mouse. PMID:24998919

  14. Seven-core active fibre for application in telecommunication satellites

    NASA Astrophysics Data System (ADS)

    Filipowicz, Marta; Napierała, Marek; Murawski, Michał; Ostrowski, Łukasz; Szostkiewicz, Łukasz; Szymański, Michał; Tenderenda, Tadeusz; Anders, Krzysztof; Piramidowicz, Ryszard; Wójcik, Grzegorz; Makara, Mariusz; Poturaj, Krzysztof; Mergo, Paweł; Nasiłowski, Tomasz

    2015-12-01

    The use of optical elements and other photonic components makes it possible to overcome telecommunication satellite's bottleneck problems such as size and weight reduction. Despite the unquestionable potential of such elements, nowadays they are not widely used in systems operating in space. This is due to many factors, including the fact that space radiation has disruptive influence on optical fibre. Namely it introduces additional radiation induced attenuation (RIA) that significantly lowers efficiency of optical fibre based systems. However, there is a possibility to produce radiation-hardened (rad-hard) components. One of them is seven core erbium-doped active fibre (MC-EDF) for fibre amplifiers in satellites that we have been developing. In this paper we present a detailed description of seven core structure design as well as experimental results. We report that average gain of 20 dB in C-band with noise figure of 5.8 dB was obtained. We also confirmed that low crosstalk value for a multicore fibre amplifier based on our fibre can be achieved.

  15. A simple model to predict the effect of volume fraction, diameter, and length of fibres on strength of fibre reinforced brittle matrix composites

    NASA Astrophysics Data System (ADS)

    Kundu, T.; Jang, H. S.; Cha, Y. H.; Desai, C. S.

    2000-06-01

    A simplified model is presented to predict the strength variations of brittle matrix composites, reinforced by steel fibres, with the variations of fibre parameters - length, diameter and volume fraction. This model predicts that its tensile and flexural strength increase non-linearly with the fibre volume fraction. It also predicts that similar non-linear behaviour should be observed with the reduction of the fibre diameter when other parameters are kept constant. The experimental results support both these theoretical predictions. It is also explained why an increase in the fibre length does not always significantly increase the fracture toughness. The objective of this paper is not to explain and understand in great detail the science of all phenomena responsible for the strength increase of fibre reinforced brittle matrix composites, but to provide a simple engineering explanation as to why its strength increases with the fibre addition, and how this increase can be quantitatively related to the variations in fibre parameters - fibre volume fraction, fibre length and diameter. These simplifying steps are needed to provide a tool that the practicing engineers can use to predict the brittle matrix strength variation with the fibre parameters. In the area of geomechanics, the results presented here can be used to assess and predict the behaviour of fibre-reinforced earth.

  16. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

    McCool, Rauri; Murphy, Adrian; Wilson, Ryan; Jiang Zhenyu; Price, Mark

    2011-05-04

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available thermoplastic based composite laminate is investigated followed by post processed part characterization. Key findings include an optimized composite processing window, and the influence of raw material blank forming temperature and mould tool temperature on part crystallinity and flexural strength. This process study forms one element of a major project structure which has been designed to address the gap between design, analysis and manufacturing, using at its core, a digital framework for the creation and management of performance parameters related to the lifecycle performance of thermoplastic composite structures.

  17. Q-switching of a thulium-doped fibre laser using a holmium-doped fibre saturable absorber

    SciTech Connect

    Sadovnikova, Ya E; Kamynin, V A; Kurkov, A S; Medvedkov, O I; Marakulin, A V; Minashina, L A

    2014-01-31

    We have proposed and demonstrated a new passively Q-switched thulium-doped fibre laser configuration. A distinctive feature of this configuration is the use of a heavily holmium-doped fibre for Q-switching. Lasing was obtained at 1.96 μm, with a pulse energy of 3 μJ and pulse duration of 600 ns. The highest pulse repetition rate was 80 kHz. (control of laser radiation parameters)

  18. Modelling of wicking and moisture interactions of flax and viscose fibres.

    PubMed

    Stuart, T; McCall, R D; Sharma, H S S; Lyons, G

    2015-06-01

    Methods for assessing the wicking properties of individual fibre bundles have been developed from models based on the original Washburn equation (WE) and the modified Washburn equation (MWE), which also accounts for swelling. Both models gave indication of differences in wicking properties of flax and the viscose fibres, though MWE gave additional information that could be interpreted in terms of the physical model. Wicking of the viscose fibres is mainly via inter-fibre capillaries while that of flax is a combination of inter-fibre capillaries and lumen present in some elementary fibres. The degree of swelling and associated rotation of flax fibre in a vapour pressure range of 1-6torr were monitored using an environmental scanning electron microscope (ESEM). Viscose fibre exhibited swelling under the same conditions but did not rotate. The two techniques highlighted different mechanisms of wicking which can be used for monitoring moisture uptake/swelling of treated fibres for fabrication of composites. PMID:25843869

  19. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    PubMed Central

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-01-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay. PMID:26490424

  20. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    NASA Astrophysics Data System (ADS)

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-10-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay.

  1. Transmission spectra of a double-clad fibre structure under bending

    SciTech Connect

    Zlodeev, I V; Ivanov, Oleg V

    2013-06-30

    We have studied a fibre-optic structure whose operation relies on conversion of core and cladding modes that are coupled across the interface between two fibres differing in refractive index profile. The structure contains a section of an SM630 double-clad, small-core, single-mode fibre inserted between two SMF-28 standard fibres. We have measured the transmission spectrum of the structure when the SM630 fibre was bent and analysed the mode structure of the double-clad fibre and the origin of dips in its transmission spectrum. The resonance dips have been found to shift to longer wavelengths with increasing fibre curvature. We have evaluated the shift as a function of the length of the inserted fibre, its bend direction and the nature of the input fibre. (fiber optics)

  2. Effect of Surface Roughness on the Steel Fibre Bonding in Ultra High Performance Concrete (UHPC)

    NASA Astrophysics Data System (ADS)

    Stengel, T.

    Micro steel fibres are currently added to UHPC to improve ductility. In UHPC under load, the high fibre strength is only utilised partly when the fibres are pulled out of the UHPC matrix. Using steel fibres with a nano- and micro-roughened surface is one measure to enhance the bond between the UHPC matrix and the fibre. In this contribution the effect of surface roughness on the bond behavior of steel fibres is shown. Single fibre pull-out tests were performed to investigate the bond behavior. Aim is to improve the bond behavior so that fibre pull-out takes place under a high load level with respect to the fibre strength.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  4. 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.

  5. Chirality measurements using optical fibre long period gratings fabricated in high birefringent fibre

    NASA Astrophysics Data System (ADS)

    Korposh, S.; Tatam, R. P.; James, S. W.; Lee, S.-W.

    2015-07-01

    A Long period grating (LPG) with a period of 111 μm was fabricated in the highly birefringent (Hi-Bi) optical fibre with the aim of developing a sensor for chirality measurements. The LPG sensor was exposed to different concentrations of glucose D(+) and fructose D(-) in water, which have similar structures but exhibit opposite optical rotations, i.e. chirality. The behaviour of the resonance bands of the submodes corresponding to the two orthogonal polarization states was different depending on the chirality of the compound, thus allowing discrimination between two compounds.

  6. 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)

  7. The design and performance of a scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

    NASA Astrophysics Data System (ADS)

    Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.; Zimmerman, C.

    2014-05-01

    Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons are increasingly being exploited for the non-destructive assay of shielded containers in a wide range of applications. One such application is the characterisation of legacy nuclear waste materials stored within industrial containers. The design, assembly and performance of a prototype muon tomography system developed for this purpose are detailed in this work. This muon tracker comprises four detection modules, each containing orthogonal layers of Saint-Gobain BCF-10 2 mm-pitch plastic scintillating fibres. Identification of the two struck fibres per module allows the reconstruction of a space point, and subsequently, the incoming and Coulomb-scattered muon trajectories. These allow the container content, with respect to the atomic number Z of the scattering material, to be determined through reconstruction of the scattering location and magnitude. On each detection layer, the light emitted by the fibre is detected by a single Hamamatsu H8500 MAPMT with two fibres coupled to each pixel via dedicated pairing schemes developed to ensure the identification of the struck fibre. The PMT signals are read out to standard charge-to-digital converters and interpreted via custom data acquisition and analysis software. The design and assembly of the detector system are detailed and presented alongside results from performance studies with data collected after construction. These results reveal high stability during extended collection periods with detection efficiencies in the region of 80% per layer. Minor misalignments of millimetre order have been identified and corrected in software. A first image reconstructed from a test configuration of materials has been obtained using software based on the Maximum Likelihood Expectation Maximisation algorithm. The results highlight the high spatial resolution provided by the detector system. Clear discrimination between the low, medium and high-Z materials assayed is also observed.

  8. Evaluation of Central Macular Thickness and Retinal Nerve Fiber Layer Thickness using Spectral Domain Optical Coherence Tomography in a Tertiary Care Hospital

    PubMed Central

    Saini, VK; Gupta, Saroj; Sharma, Anjali

    2014-01-01

    ABSTRACT Purpose: To evaluate the normative data of macular thickness and retinal nerve fiber layer thickness (RNFL) among normal subjects using spectral domain optical coherence tomography (OCT). Materials and methods: Normal subjects presenting to a tertiary medical hospital were included in the study. All patient underwent clinical examination followed by study of macular thickness and RN FL thick ness by spectral domain Topc on OCT. The data was collected and analyzed for variations in gender and age. The data was also compared with available literature. Results: Total numbers of patients enrolled in the study were 154 (308 eyes). Numbers of males were 79 (158 eyes) and numbers of females were 75 (150 eyes). The mean age among males was 42.67 ± 12.15 years and mean age among females was 42.88 ± 11.73 years. Overall the mean mac ular thickness (central 1 mm zone) with SD - OCT was 241.75 ± 17.3 microns. The mean macular volume was 7.6 cu. mm ± 0.33. On analysis of the RNFL thickness, we observed that the RNFL was thickest in the inferior quadrant (138.58) followed by superior (122.30) nasal (116.32) and temporal quadrant (73.04). Gender-wise comparison of the data revealed no statistically significant difference for age, macular thickness parameters, volume and RFNL values except outer temporal thickness among males and females. No age-related difference was noted in the above parameters. On comparison with available norma tive data from India and elsewhere, we found significant variations with different machines. Conclusion: The study is the first to provide normative data using SD-OCT from central India. The data from spectral domain OCT correlated well with the values obtained from similar studies with SD - OCT. Values obtained from time domain OCT machines are different and are not comparable. How to cite this article: Agarwal P, Saini VK, Gupta S, Sharma A. Evaluation of Central Macular Thickness and Retinal Nerve Fiber Layer Thickness using Spectral Domain Optical Coherence Tomography in a Tertiary Care Hospital. J Curr Glaucoma Pract 2014;8(2):75-81.

  9. The optical properties of birefringence signals from single muscle fibres.

    PubMed

    Baylor, S M; Oetliker, H

    1977-01-01

    1. The optical retardation of single muscle fibres at rest and the optical properties of the large, early birefringence signal detectable during a twitch (Baylor & Oetliker, 1975, 1977a) were investigated. 2. The resting birefringence, B, which is the factor relating resting retardation, R, to the light path length through the fibre, L, was found to be 2.25 x 10-3 (i.e. R = 2.25 X 10-3 X L) and to be independent of wavelength ( lambda = 480-660 nm). 3. When the angle of incidence, psi, of the crossed polarizers with respect to the fibre axis was varied, the resting light intensity and large, early change in light intensity were related by the function sin2 psi-cos2psi. When the net phase shift, phi lambda, of a narrow longitudinal strip of fibre plus compensator was varied, the resting light intensity was described by the function (1-cos phi lambda), whereas the early change in light intensity followed sin phi lambda. These results make it likely that the optical mechanism underlying the early birefringence signal is a change in retardation. 4. When a narrow longitudinal strip of fibre was illuminated by monochromatic light in the range 480-690 nm, the magnitude of the signal varied approximately as expected if the retardation change is independent of wave-length. 5. The spatial characteristics of the signal were examined by moving a small slit of light across the fibre width as well as by measuring the signal collected from the entire fibre width as a function of wave-length. The results from both experiments support the idea that the large, early change in retardation is due to a volume-related rather than surface-related structure. 6. Under the assumption that the retardation change is distributed as fibre volume, its average magnitude was calculated. For fibres in normal Ringer the peak of the early retardation change compared with resting is about 1.7 x 10-3, and for fibres in D2O Ringer about 0.7 x 10-3. PMID:300107

  10. A fabry-perot fibre-optic hydrophone for the characterisation of ultrasound fields

    NASA Astrophysics Data System (ADS)

    Morris, Paul

    This thesis documents the development of a novel fibre optic hydrophone, for the characterisation of medical ultrasound transducers and the measurement of ultrasound induced temperature rises. The transduction mechanism of the hydrophone is based on the detection of acoustically and thermally induced changes in the optical thickness of a Fabry-Perot interferometer deposited at the tip of a single mode optical fibre. The interferometer comprises a layer of Parylene-C sandwiched between two thin gold mirrors. The design of the sensor was optimised using a numerical model of the interferometer transfer function. Through the use of vacuum deposition techniques, a fabrication procedure has been developed which enables batch production of the sensors. A self contained sensor interrogation system has also been developed. The system uses a rapidly tuneable laser developed originally for the telecoms industry to interrogate the sensor and make acoustic and thermal measurements. Control of the system is achieved via a PC using software written in Labview 8.0. The acoustic performance of the sensors was characterised using a substitution calibration. The frequency response, directivity and sensitivity of the sensor were all investigated. It was found that whilst the sensor offers a wide bandwidth (>50 MHz), the frequency response is significantly non uniform. Using a finite difference model (AFiDS), it was found that diffraction at the sensor tip is the main cause of resonances in the response. The thermal measurement performance of the sensor was investigated in the presence of an ultra sound field. By comparing the temperature measurements from the hydrophone with those obtained from a thin-film thermocouple, it was found that the fibre-optic hydrophone is immune to viscoelastic heating artefacts. Finally, a novel tracking algorithm was developed, allowing the hydrophone to be used to make simultaneous measurements of both acoustic pressures and ultrasound induced temperature rises.

  11. Wave kinetics of random fibre lasers

    NASA Astrophysics Data System (ADS)

    Churkin, D. V.; Kolokolov, I. V.; Podivilov, E. V.; Vatnik, I. D.; Nikulin, M. A.; Vergeles, S. S.; Terekhov, I. S.; Lebedev, V. V.; Falkovich, G.; Babin, S. A.; Turitsyn, S. K.

    2015-02-01

    Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example—random fibre laser—we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics.

  12. Wave kinetics of random fibre lasers.

    PubMed

    Churkin, D V; Kolokolov, I V; Podivilov, E V; Vatnik, I D; Nikulin, M A; Vergeles, S S; Terekhov, I S; Lebedev, V V; Falkovich, G; Babin, S A; Turitsyn, S K

    2015-01-01

    Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example-random fibre laser-we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics. PMID:25645177

  13. Fibre optics improving deepwater rov pipeline inspection

    SciTech Connect

    McGregor, D.

    1983-09-01

    Pipeline inspection is a complex test requiring a variety of sensors. The trend in recent times has been to fit, simultaneously, all of the above sensors to a vehicle in order to maximise data collection from the pipeline in a single pass. This data is then processed in real time as the ROV travels the pipeline. Thus, a chart representing all the available data can be made available shortly after completion of a dive. The current generation of ROVs uses umbilicals containing various combinations of power conductors, co-axia and twisted pairs to carry the sensor data. These umbilicals, however, have inherent disadvantages which become apparent as sensor data increase in quantity and complexity. This disadvantage is the incompatibility of required high quality-data being transmitted to the surface and the large amounts of electrical energy demanded by the vehicle. Another disadvantage is the incompatibility between sensor signals in terms of frequency and power. However, to eliminate these problems, and to provide for future developments in ROV technology, the new generation of ROVs utilise fibre-optic conductors, the advantages being that they are immune from electro-magnetic interference, they offer wider band-widths with lower power losses (typically 5 dB or less per km) than conventional copper conductors, and are easier to handle as umbilicals lengthen due to demand for vehicles to reach greater depths. Typically, these new umbilicals will be 1.5 km in length.

  14. Wave kinetics of random fibre lasers

    PubMed Central

    Churkin, D V.; Kolokolov, I V.; Podivilov, E V.; Vatnik, I D.; Nikulin, M A.; Vergeles, S S.; Terekhov, I S.; Lebedev, V V.; Falkovich, G.; Babin, S A.; Turitsyn, S K.

    2015-01-01

    Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example—random fibre laser—we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics. PMID:25645177

  15. Smart Structures with Fibre-Optic Technologies

    SciTech Connect

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-08

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  16. A multiphase model for chemically- and mechanically- induced cell differentiation in a hollow fibre membrane bioreactor: minimising growth factor consumption.

    PubMed

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

    2016-06-01

    We present a simplified two-dimensional model of fluid flow, solute transport, and cell distribution in a hollow fibre membrane bioreactor. We consider two cell populations, one undifferentiated and one differentiated, with differentiation stimulated either by growth factor alone, or by both growth factor and fluid shear stress. Two experimental configurations are considered, a 3-layer model in which the cells are seeded in a scaffold throughout the extracapillary space (ECS), and a 4-layer model in which the cell-scaffold construct occupies a layer surrounding the outside of the hollow fibre, only partially filling the ECS. Above this is a region of free-flowing fluid, referred to as the upper fluid layer. Following previous models by the authors (Pearson et al. in Math Med Biol, 2013, Biomech Model Mechanbiol 1-16, 2014a, we employ porous mixture theory to model the dynamics of, and interactions between, the cells, scaffold, and fluid in the cell-scaffold construct. We use this model to determine operating conditions (experiment end time, growth factor inlet concentration, and inlet fluid fluxes) which result in a required percentage of differentiated cells, as well as maximising the differentiated cell yield and minimising the consumption of expensive growth factor. PMID:26276678

  17. 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