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Sample records for fibre layer rnfl

  1. Relating Retinal Ganglion Cell Function and Retinal Nerve Fiber Layer (RNFL) Retardance to Progressive Loss of RNFL Thickness and Optic Nerve Axons in Experimental Glaucoma

    PubMed Central

    Fortune, Brad; Cull, Grant; Reynaud, Juan; Wang, Lin; Burgoyne, Claude F.

    2015-01-01

    Purpose. To relate changes in retinal function and retinal nerve fiber layer (RNFL) retardance to loss of RNFL thickness and optic nerve axon counts in a nonhuman primate (NHP) model of experimental glaucoma (EG). Methods. Bilateral longitudinal measurements of peripapillary RNFL thickness (spectral-domain optical coherence tomography, SDOCT; Spectralis), retardance (GDxVCC), and multifocal electroretinography (mfERG; VERIS) were performed in 39 NHP at baseline (BL; median, 5 recordings; range, 310) and weekly after induction of unilateral EG by laser photocoagulation of the trabecular meshwork. Multifocal ERG responses were high-pass filtered (>75 Hz) to measure high- and low-frequency component (HFC and LFC) amplitudes, including LFC features N1, P1, and N2. High-frequency component amplitudes are known to specifically reflect retinal ganglion cell (RGC) function. Complete (100%) axon counts of orbital optic nerves were obtained in 31/39 NHP. Results. Postlaser follow-up was 10.4 7.9 months; mean and peak IOP were 18 5 and 41 11 mm Hg in EG eyes, 11 2 and 18 6 mm Hg in control (CTL) eyes. At the final available time point, RNFL thickness had decreased from BL by 14 14%, retardance by 20 11%, and the mfERG HFC by 30 17% (P < 0.0001 each). Longitudinal changes in retardance and HFC were linearly related to RNFL thickness change (R2 = 0.51, P < 0.0001 and R2 = 0.22, P = 0.002, respectively); LFC N2 was weakly related but N1 or P2 (N1: R2 = 0.07, P = 0.11; P1: R2 = 0.04, P = 0.24; N2: R2 = 0.13, P = 0.02). At zero change from BL for RNFL thickness (Y-intercept), retardance was reduced by 11% (95% confidence interval [CI]: ?15.3% to ?6.8%) and HFC by 21.5% (95% CI: ?28.7% to ?14.3%). Relative loss of RNFL thickness, retardance, and HFC (EG:CTL) were each related to axon loss (R2 = 0.66, P < 0.0001; R2 = 0.42, P < 0.0001; R2 = 0.42, P < 0.0001, respectively), but only retardance and HFC were significantly reduced at zero relative axon loss (Y-intercept; retardance: ?9.4%, 95% CI: ?15.5% to ?3.4%; HFC: ?10.9%, 95% CI: ?18.6% to ?3.2%; RNFL thickness: +1.8%, 95% CI: ?4.9% to +5.4%). Conclusions. Retinal nerve fiber layer retardance and RGC function exhibit progressive loss from baseline before any loss of RNFL thickness or orbital optic nerve axons occurs in NHP EG. These in vivo measures might serve as potential biomarkers of early-stage glaucomatous damage preceding axon loss and RGC death. PMID:26087359

  2. Imaging of the retinal nerve fibre layer for glaucoma

    PubMed Central

    Townsend, K A; Wollstein, G; Schuman, J S

    2010-01-01

    Background Glaucoma is a group of diseases characterised by retinal ganglion cell dysfunction and death. Detection of glaucoma and its progression are based on identification of abnormalities or changes in the optic nerve head (ONH) or the retinal nerve fibre layer (RNFL), either functional or structural. This review will focus on the identification of structural abnormalities in the RNFL associated with glaucoma. Discussion A variety of new techniques have been created and developed to move beyond photography, which generally requires subjective interpretation, to quantitative retinal imaging to measure RNFL loss. Scanning laser polarimetry uses polarised light to measure the RNFL birefringence to estimate tissue thickness. Optical coherence tomography (OCT) uses low-coherence light to create high-resolution tomographic images of the retina from backscattered light in order to measure the tissue thickness of the retinal layers and intraretinal structures. Segmentation algorithms are used to measure the thickness of the retinal nerve fibre layer directly from the OCT images. In addition to these clinically available technologies, new techniques are in the research stages. Polarisation-sensitive OCT has been developed that combines the strengths of scanning laser polarimetry with those of OCT. Ultra-fast techniques for OCT have been created for research devices. The continued utilisation of imaging devices into the clinic is refining glaucoma assessment. In the past 20 years glaucoma has gone from a disease diagnosed and followed using highly subjective techniques to one measured quantitatively and increasingly objectively. PMID:19028735

  3. Retinal nerve fibre layer loss in hereditary spastic paraplegias is restricted to complex phenotypes

    PubMed Central

    2012-01-01

    Background Reduction of retinal nerve fibre layer (RNFL) thickness was shown as part of the neurodegenerative process in a range of different neurodegenerative pathologies including Alzheimer?s disease (AD), idiopathic Parkinsons disease (PD), spinocerebellar ataxia (SCA) and multiple system atrophy (MSA). To further clarify the specificity of RNFL thinning as a potential marker of neurodegenerative diseases we investigated RNFL thickness in Hereditary Spastic Paraplegia (HSP), an axonal, length-dependent neurodegenerative pathology of the upper motor neurons. Methods Spectral domain optical coherence tomography (OCT) was performed in 28 HSP patients (clinically: pure HSP = 22, complicated HSP = 6; genetic subtypes: SPG4 = 13, SPG5 = 1, SPG7 = 3, genetically unclassified: 11) to quantify peripapillary RNFL thickness. Standardized examination assessed duration of disease, dependency on assistive walking aids and severity of symptoms quantified with Spastic Paraplegia Rating Scale (SPRS). Results HSP patients demonstrated no significant thinning of global RNFL (pglobal = 0.61). Subgroup analysis revealed significant reduction in temporal and temporal inferior sectors for patients with complex (p<0.05) but not pure HSP phenotypes. Two of three SPG7-patients showed severe temporal and temporal inferior RNFL loss. Disease duration, age and severity of symptoms were not significantly correlated with global RNFL thickness. Conclusion Clinically pure HSP patients feature no significant reduction in RNFL, whereas complex phenotypes display an abnormal thinning of temporal and temporal inferior RNFL. Our data indicate that RNFL thinning does not occur unspecifically in all neurodegenerative diseases but is in HSP restricted to subtypes with multisystemic degeneration. PMID:23176075

  4. 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.

  5. Retinal Nerve Fibre Layer and Macular Thicknesses in Adults with Hyperopic Anisometropic Amblyopia

    PubMed Central

    Yakar, Konuralp; Alan, Ayd?n; Alp, Mehmet Hanifi; Ceylan, Tolga

    2015-01-01

    Objectives. This study compared the macular and retinal nerve fibre layer (RNFL) thicknesses and optic nerves of eyes with reduced vision due to anisometropia with the contralateral healthy eyes in adults using optical coherence tomography (OCT). Methods. This cross-sectional study was conducted in Atatrk State Hospital, Sinop, Turkey. Macular and RNFL thicknesses, optic nerve disc area, cup area, and horizontal and vertical cup-to-disc ratios obtained using a NIDEK RS-3000 SLO spectral domain OCT device were compared between the amblyopic and fellow eyes in 30 adults with anisometropic amblyopia 1855 years old who were seen in our clinic with unilateral poor vision. Results. The mean macular thickness was 266.90 23.22?m in the amblyopic eyes and 263.90 22.84?m in the fellow eyes, and the mean RNFL thickness was 111.90 12.9 and 109.70 9.42?m, respectively. The two thicknesses did not differ significantly between the amblyopic and fellow eyes. There were also no significant differences between the eyes in disc area, cup area, and horizontal-vertical cup/disc ratios. Conclusion. There does not seem to be a difference in macular thickness, peripapillary RNFL, or optic disc structures between the amblyopic and fellow eyes in adults. PMID:26064676

  6. How strong is the relationship between glaucoma, the retinal nerve fibre layer, and neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis?

    PubMed

    Jones-Odeh, E; Hammond, C J

    2015-10-01

    Glaucoma is a neurodegenerative disorder with established relationships with ocular structures such as the retinal nerve fibre layer (RNFL) and the ganglion cell layer (GCL). Ocular imaging techniques such as optical coherence tomography (OCT) allow for quantitative measurement of these structures. OCT has been used in the monitoring of glaucoma, as well as investigating other neurodegenerative conditions such as Alzheimer's disease (AD) and multiple sclerosis (MS). In this review, we highlight the association between these disorders and ocular structures (RNFL and GCL), examining their usefulness as biomarkers of neurodegeneration. The average RNFL thickness loss in patients with AD is 11??m, and 7??m in MS patients. Most of the studies investigating these changes are cross-sectional. Further longitudinal studies are required to assess sensitivity and specificity of these potential ocular biomarkers to neurodegenerative disease progression. PMID:26337943

  7. Correlation between the radial peripapillary capillaries and the retinal nerve fibre layer in the normal human retina.

    PubMed

    Yu, Paula K; Cringle, Stephen J; Yu, Dao-Yi

    2014-12-01

    This study aims to provide evidence of the importance of radial peripapillary capillaries (RPCs) by quantitative study of the relationship between the RPCs and retinal nerve fibre layer (RNFL) in normal human donor eyes. The retinal microvasculature in eleven normal human donor eyes was perfused, fixed and labelled after cannulation of the central retinal artery. The retinas were dissected and whole-mounted for confocal microscopy. Six study regions were taken radially from the edge of the optic disc. RPCs from the optic disc edge to a radial distance up to 2.5 mm were imaged and their diameters, inter-capillary distance and volume occupation measured. These were correlated with the study region as well as thickness of the RNFL. It was found that the pooled average diameter of the RPCs in the first 2.5 mm from the optic disk was 8.9 ?m. Significant differences in capillary diameter were present in the six regions, with larger diameter RPCs in the superior, inferior and nasal regions, and significantly smaller diameter in the temporal region. RPCs in the arcuate fibre regions extend the furthest from the optic disc, maintained a close inter-capillary distance for a longer distance than other regions, and have the highest RPCs volume occupancy. The RPCs volume was generally correlated with RNFL thickness. In conclusion, a close correlation between RNFL and RPCs presence has been demonstrated which is supportive of their functional reliance/co-dependence. The significantly smaller temporal RPCs may be a result of the greater presence of RPCs in the two bordering arcuate fibre regions and therefore a richer availability of nutrients diffusing from these two regions. PMID:25447563

  8. Automated method for RNFL segmentation in spectral domain OCT

    NASA Astrophysics Data System (ADS)

    Paranjape, Amit S.; Elmaanaoui, Badr; Dewelle, Jordan; Rylander, H. Grady; Milner, Thomas E.

    2008-02-01

    We introduce a method based on optical reflectivity changes to segment the retinal nerve fiber layer (RNFL) in images recorded using swept source spectral domain optical coherence tomography (OCT). The segmented image is used to determine the RNFL thickness. Simple filtering followed by edge detecting techniques can successfully be applied to segment the RNFL from recorded images and estimate RNFL thickness. The method is computationally more efficient than previously reported approaches. Higher computational efficiency allows faster segmentation and provides the ophthalmologist segmented retinal images that better utilize advantages of spectral domain OCT instrumentation. OCT B-scan and fundus images of the retina are recorded for 5 patients. The segmentation method is applied on B-scan images recorded from all patients. An expert ophthalmologist separately demarcates the RNFL layer in the OCT images from the same patients in each B-scan image. Results from automated image processing software are compared to the boundary demarcated by the expert ophthalmologist. The absolute error between the boundaries demarcated by the expert and the algorithm is expressed in terms of area and is used as an error metric. Ability of the algorithm to accurately segment the RNFL in comparison with an expert ophthalmologist is reported.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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).

  14. 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 stressstrain 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, 43794403) and Holzapfel et al. (Holzapfel et al. 2000 J. Elast. 61, 148). 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

  15. 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

  16. Birefringence and nerve fiber orientation in healthy in vivo primate RNFL with enhanced polarization-sensitive optical coherence tomography (EPS-OCT)

    NASA Astrophysics Data System (ADS)

    Kemp, Nate J.; Zaatari, Haitham N.; Park, Jesung; Milner, Thomas E.; Rylander, H. G., III

    2005-04-01

    Form-birefringent properties of the retinal nerve fiber layer (RNFL) have become increasingly important as investigators strive to provide an improved methodology for glaucoma diagnosis. Techniques such as scanning laser polarimetry (SLP) and polarization-sensitive optical coherence tomography (PS-OCT) are two approaches which directly assess RNFL neurotubules, the sub-cellular structures responsible for form-birefringence and axoplasmic transport in retinal ganglion cell axons. We present a novel algorithm for enhancing the sensitivity of PS-OCT. Enhanced polarization-sensitive OCT (EPS-OCT) is capable of detecting small transformations in polarization typically experienced by light propagating through the thin and weakly birefringent primate RNFL. We report birefringence and nerve fiber orientation measurements for the peripapillary region in healthy in vivo primate RNFL and discuss the implications of the enhanced-sensitivity approach on noninvasive quantification of form-birefringence in glaucoma diagnostics.

  17. 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

  18. 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).

  19. 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

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

    PubMed

    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

  1. Comparative studies of RNFL thickness measured by OCT with global index of visual fields in patients with ocular hypertension and early open angle glaucoma

    PubMed Central

    Taliantzis, Sergios; Papaconstantinou, Dimitris; Koutsandrea, Chrysanthi; Moschos, Michalis; Apostolopoulos, Michalis; Georgopoulos, Gerasimos

    2009-01-01

    Purpose: To compare the functional changes in visual fields with optical coherence tomography (OCT) findings in patients with ocular hypertension, open angle glaucoma, and suspected glaucoma. In addition, our purpose is to evaluate the correlation of global indices with the structural glaucomatous defect, to assess their statistical importance in all the groups of our study, and to estimate their validity to the clinical practice. Methods: One hundred sixty nine eyes (140 patients) were enrolled. The patients were classified in three groups. Group 1 consisted of 54 eyes with ocular hypertension, group 2 of 42 eyes with preperimetric glaucoma, and group 3 of 73 eyes with chronic open angle glaucoma. All of them underwent ophthalmic examination according to a prefixed protocol, OCT exam (Stratus 3000) for retinal nerve fiber layer (RNFL) thickness measurement with fast RNFL thickness protocol and visual fields (VF) examination with Octopus perimeter (G2 program, central 302 threshold strategy). Pearson correlation was calculated between RNFL thickness and global index of VF. Results: A moderate correlation between RNFL thickness and indices mean sensitivity (MS), mean defect (MD) and loss variance (LV) of VF (0.547, ?0.582, ?0.527, respectively; P <0.001) was observed for all patients. Correlations of the ocular hypertension and preperimetric groups are weak. Correlation of RNFL thickness with global indices becomes stronger as the structural alterations become deeper in OCT exam. Correlation of RNFL thickness with the global index of VF, in respective segments around optic disk was also calculated and was found significant in the nasal, inferior, superior, and temporal segments. Conclusion: RNFL average thickness is not a reliable index for early diagnosis of glaucoma and for the follow-up of patients with ocular hypertension. Segmental RNFL thickness seems to be a more reliable index. Deep structural alterations with OCT examination constitute an important indication of early functional changes, even if they are not still detected with achromatic perimetry. The MD index of VF seems to be more sensitive for the follow-up of patients with ocular hypertension. PMID:19668593

  2. High-index-ring three-layer fibresfor mode-locked sub-1.3 {mu}m fibre lasers

    SciTech Connect

    Belanov, A S; Tsvetkov, S V

    2010-02-28

    This paper addresses issues pertaining to the propagation of ultrashort pulses in the cavities of mode-locked sub-1.3 {mu}m fibre lasers. We demonstrate that multimode high-index-ring three-layer optical fibres operating on a single higher order HE{sub 1m} mode are an effective approach to dispersion compensation. We present optimal parameters of the refractive-index profile in such fibres, which ensure zero first- and second-order chromatic dispersion coefficients at 1.06 {mu}m for the HE{sub 12} and HE{sub 13} modes, and analyse their dispersion and power parameters. (optical fibres and waveguides)

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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

  10. Diattenuation and polarization preservation of retinal nerve fiber layer reflectance

    NASA Astrophysics Data System (ADS)

    Huang, Xiang-Run; Knighton, Robert W.

    2003-10-01

    The diattenuation spectrum of the retinal nerve fiber layer (RNFL) reflectance has been predicted to depend strongly on the relative refractive index (m) of light-scattering cylinders. To constrain the values of m, diattenuation of the RNFL reflectance of isolated rat retina was measured with a multispectral imaging micropolarimeter. The RNFL reflection has very weak intrinsic diattenuation at all wavelengths (400-830 nm), which rejects all values of m >= 1.03. Degree of polarization (DOP) for reflection from the RNFL was also measured. DOP was close to unity at all wavelengths, which indicates that the RNFL is a polarization-preserving reflector.

  11. 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.

  12. Theoretical model of the polarization properties of the retinal nerve fiber layer in reflection

    NASA Astrophysics Data System (ADS)

    Huang, Xiang-Run; Knighton, Robert W.

    2003-10-01

    In several optical technologies for glaucoma diagnosis, polarized light is used to assess the retinal nerve fiber layer (RNFL) of the eye. For better understanding of the polarization properties of the RNFL, it was modeled as a thick birefringent slab containing parallel light-scattering cylinders, and the Mueller matrix for reflectance was derived. The model predicts that (1) the RNFL reflectance has weak intrinsic diattenuation; (2) the diattenuation spectrum depends strongly on the relative refractive indices of the cylinders; (3) both scattering and birefringence contribute to retardation; and (4) the RNFL reflectance generally preserves polarization, but depolarization may be detectable for thick RNFL at short wavelengths.

  13. Increment of subcutaneous adipose tissue is associated with decrease of elastic fibres in the dermal layer.

    PubMed

    Ezure, Tomonobu; Amano, Satoshi

    2015-12-01

    Obesity is a significant risk factor for various skin disorders, including pressure ulcer and delayed wound healing. We previously showed that increment of subcutaneous adipose tissue contributes to poor skin condition by decreasing dermal elasticity. Here, we examined the mechanism involved. Histologic observation of abdominal skin from middle-aged females with a wide range of body mass index (BMI), an indicator of subcutaneous fat mass, showed that dermal elastic fibre abundance was significantly decreased with increment of BMI. Concomitantly, adipocytes were significantly enlarged. Adipocyte enlargement was significantly negatively correlated with dermal elastic fibre abundance. We hypothesized that enlarged adipocytes negatively influence dermal elastic fibres, so we investigated elastic fibre-degrading factors in invitro-cultured enlarged adipocytes. MMP9 gene expression and secretion were significantly increased; further, these changes were blocked by extracellular signal-regulated kinase (ERK) inhibitor. Nuclear translocation (activation) of AP-1, a downstream ERK signalling molecule, was also observed in enlarged adipocytes. MMP9 abundance was significantly increased in skin of subjects with high BMI and enlarged adipocytes. These results suggest that increment of subcutaneous adipose tissue leads to adipocyte enlargement together with increased degradation of dermal elastic fibres, mediated at least in part by an ERK signalling-mediated increase of MMP9 in enlarged adipocytes. PMID:26194659

  14. Polarization properties of the retinal nerve fiber layer investigated with multispectral imaging micropolarimetry

    NASA Astrophysics Data System (ADS)

    Huang, Xiangrun

    Evaluation of the retinal nerve fiber layer (RNFL) is valuable in diagnosing glaucoma and other ocular neuropathic diseases. Several optical methods have been developed to assess the RNFL quantitatively. Knowledge about the optical properties of the RNFL and the underlying mechanisms is essential to understand these techniques and improve their assessment ability. Experimental studies show that the RNFL reflectance arises from the scattering of light by cylindrical structures. The measured reflectance spectra of the RNFL suggest that both thin and thick cylinders contribute to the RNFL reflection and experiments with colchicine suggest that microtubules are a likely candidate for the thin cylinders. The RNFL was modeled mathematically as an ensemble of uniformly distributed cylinders assumed to be form birefringent. The Mueller matrix of the RNFL model was derived and decomposed to reveal its polarization properties. The diattenuation of the model was due to the cylindrical scattering properties. The retardance exhibited in the model included the phase changes due to cylindrical scattering and to the RNFL birefringence. Reflection by the RNFL model preserved polarization. A multispectral imaging micropolarimeter was designed and calibrated. It was used to investigate the reflectance and polarization properties of the RNFL of isolated rat retinas. The RNFL retardance measured in transmission was constant over visible wavelengths, which suggested that only one mechanism was involved in the RNFL birefringence and agreed with the assumption of the RNFL being form birefringent. Measurements of diattenuation spectra of the RNFL reflectance revealed that intrinsic diattenuation is small at all wavelengths. The results led to two possible conclusions (1)if the RNFL reflection arises from scattering by spatially separated cylinders, the refractive index of these cylinders is close to that of the surrounding medium and (2)cylindrical structures other than spatially- separated cylinders may dominate the RNFL reflection; axonal membranes are a possible candidate. The reflected light from the RNFL preserved its polarization. Knowledge of the polarization properties of the RNFL reflectance could help to understand the measured signals in some optical techniques, such as optical coherence tomography (OCT) and scanning laser polarimetry (SLP), and therefore improve their assessment ability of the RNFL.

  15. 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

  16. 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

  17. Multimaterial piezoelectric fibres

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

  18. High-Resolution Fibre-Optic Temperature Sensing: A New Tool to Study the Two-Dimensional Structure of Atmospheric Surface-Layer Flow

    NASA Astrophysics Data System (ADS)

    Thomas, Christoph K.; Kennedy, Adam M.; Selker, John S.; Moretti, Ayla; Schroth, Martin H.; Smoot, Alexander R.; Tufillaro, Nicholas B.; Zeeman, Matthias J.

    2012-02-01

    We present a novel approach based on fibre-optic distributed temperature sensing (DTS) to measure the two-dimensional thermal structure of the surface layer at high resolution (0.25 m, ?0.5 Hz). Air temperature observations obtained from a vertically-oriented fibre-optics array of approximate dimensions 8 m 8 m and sonic anemometer data from two levels were collected over a short grass field located in the flat bottom of a wide valley with moderate surface heterogeneity. The objectives of the study were to evaluate the potential of the DTS technique to study small-scale processes in the surface layer over a wide range of atmospheric stability, and to analyze the space-time dynamics of transient cold-air pools in the calm boundary layer. The time response and precision of the fibre-based temperatures were adequate to resolve individual sub-metre sized turbulent and non-turbulent structures, of time scales of seconds, in the convective, neutral, and stable surface layer. Meaningful sensible heat fluxes were computed using the eddy-covariance technique when combined with vertical wind observations. We present a framework that determines the optimal environmental conditions for applying the fibre-optics technique in the surface layer and identifies areas for potentially significant improvements of the DTS performance. The top of the transient cold-air pool was highly non-stationary indicating a superposition of perturbations of different time and length scales. Vertical eddy scales in the strongly stratified transient cold-air pool derived from the DTS data agreed well with the buoyancy length scale computed using the vertical velocity variance and the Brunt-Vaisala frequency, while scales for weak stratification disagreed. The high-resolution DTS technique opens a new window into spatially sampling geophysical fluid flows including turbulent energy exchange.

  19. 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).

  20. Mucosal layers and related nerve fibres in non-chagasic and chagasic human colon--a quantitative immunohistochemical study.

    PubMed

    Jabari, Samir; da Silveira, Alexandre B M; de Oliveira, Enio C; Quint, Karl; Wirries, Andr; Neuhuber, Winfried; Brehmer, Axel

    2014-10-01

    Chagasic megacolon is accompanied by extensive myenteric and, simultaneously, moderate submucosal neuron loss. Here, we examined changes of the innervation pattern of the lamina propria (LP) and muscularis mucosae (MM). Two alternating sets of cryosections were taken from seven non-chagasic colonic and seven chagasic megacolonic specimens (the latter included both the dilated megacolonic and the non-dilated transitional oral and anal zones) and were immunohistochemically triple-stained for smooth-muscle actin (SMA), synaptophysin (SYN) and glial acid protein S100 and, alternatively, for SMA, vasoactive intestinal peptide (VIP) and somatostatin (SOM). Subsequent image analysis and statistical evaluation of nervous tissue profile areas revealed that, in LP, the most extreme differences (i.e. increase in thickness or decrease in nerve, glia and muscle tissue profile area, respectively) compared with control values occurred in the dilated megacolonic zone itself. In contrast, the most extreme differences in the MM were in the anal-to-megacolonic zone (except the profile area of muscle tissue, which was lowest in the megacolonic zone). This parallels our previous results in the external muscle coat. A partial and selective survival of VIP-immunoreactive in contrast to SOM-immunoreactive nerve fibres was observed in both mucosal layers investigated. Thus, VIPergic nerve elements might be crucial for the maintenance of the mucosal barrier. The differential changes of neural tissue parameters in LP and MM might reflect a multifactorial rather than a pure neurogenic development of megacolon in chronic Chagas' disease. PMID:24962547

  1. 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

  2. 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…

  3. Optimized retinal nerve fiber layer segmentation based on optical reflectivity and birefringence for polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Bingqing; Paranjape, Amit S.; Yin, Biwei; Liu, Shuang; Markey, Mia K.; Milner, Thomas E.; Rylander, H. Grady, III

    2011-09-01

    Segmentation of the retinal nerve fiber layer (RNFL) from swept source polarization-sensitive optical coherence tomography (SS-PSOCT) images is required to determine RNFL thickness and calculate birefringence. Traditional RNFL segmentation methods based on image processing and boundary detection algorithms utilize only optical reflectivity contrast information, which is strongly affected by speckle noise. We present a novel approach to segment the retinal nerve fiber layer (RNFL) using SS-PSOCT images including both optical reflectivity and phase retardation information. The RNFL anterior boundary is detected based on optical reflectivity change due to refractive index difference between the vitreous and inner limiting membrane. The posterior boundary of the RNFL is a transition zone composed of birefringent axons extending from retinal ganglion cells and may be detected by a change in birefringence. A posterior boundary detection method is presented that segments the RNFL by minimizing the uncertainty of RNFL birefringence determined by a Levenberg-Marquardt nonlinear fitting algorithm. Clinical results from a healthy volunteer show that the proposed segmentation method estimates RNFL birefringence and phase retardation with lower uncertainty and higher continuity than traditional intensity-based approaches.

  4. Physicochemical properties of hull-less barley fibre-rich fractions varying in particle size and their potential as functional ingredients in two-layer flat bread.

    PubMed

    Izydorczyk, M S; Chornick, T L; Paulley, F G; Edwards, N M; Dexter, J E

    2008-05-15

    The performance of barley fibre-rich fractions (FRF), as high dietary fibre ingredients, in two-layer flat bread was investigated. In addition, the effects of particle size reduction by pin milling on functional properties of FRF were studied. FRF enriched in non-starch polysaccharides (?-glucans and arabinoxylans) were obtained by roller milling of hull-less barley. Pin milling (PM) of FRF significantly reduced their particle size, slightly increased the solubility of ?-glucans and arabinoxylans, and increased the viscosity of water slurries containing FRF. The addition of 20% of barley FRF to wheat flour significantly increased dough water absorption and weakened the dough properties, as indicated by farinograph mixing curves, but the FRF-enriched doughs exhibited good handling characteristics at the dividing and sheeting stages. The appearance, diameter, layer separation, crumb, and aroma of the FRF-enriched flat breads were comparable to that of the control. The PM of FRF did not significantly affect the dough handling or the quality characteristics of flat breads. The addition of 20% of barley FRF to wheat flour flat bread provided substantial health benefits by significantly increasing the total and soluble dietary fibre contents and by decreasing starch digestibility. PMID:26059134

  5. 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)

  6. Analysis of birefringent image in the retinal nerve fiber layer by polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Park, Jesung; Kemp, Nate J.; Zaatari, Hatham N.; Milner, Thomas E.; Rylander, H. G., III

    2004-07-01

    Phase retardation per unit depth (PR/UD) is a physiologically significant parameter which correlates with the orderly arrangement of neurons and neurofibrils within the retinal nerve fiber layer (RNFL) and can vary in glaucoma. The objective of this study is to use Polarization Sensitive Optical Coherence Tomography (PSOCT), to detect both RNFL thickness and depth-resolved birefringence and produce thickness and PR/UD maps of the primate RNFL. RNFL thickness is obtained from the PSOCT intensity image with boundary detection using imaging processing methods. Analysis of PR/UD begins with calculating the Stokes parameters from the horizontal magnitude, vertical magnitude and relative phase difference in the interference fringes of light back scattered from the retina. Computed Stokes parameters are used to determine the fast axis in the RNFL and local phase retardation. PR/UD is calculated by dividing local birefringence by the corresponding RNFL thickness. A three-dimensional map of PR/UD and RNFL thickness is constructed by combining registered B-scans. Three-dimensional maps of thickness and PR/UD from the primate RNFL show that PSOCT is can be used for detecting thickness and PR/UD of the peripapillary RNFL and a very effective modality to diagnose glaucoma.

  7. Detection of glaucomatous retinal nerve fiber layer damage by scanning laser polarimetry with custom corneal compensation

    NASA Astrophysics Data System (ADS)

    Zhou, Qienyuan; Reed, Jerry; Betts, Ryan W.; Trost, Peter K.; Lo, Pak-Wai; Wallace, Charles; Bienias, Richard H.; Li, Guoqiang; Winnick, Ross; Papworth, William A.; Sinai, Michael

    2003-07-01

    Glaucoma causes damage in the retinal nerve fiber layer (RNFL). Scanning laser polarimetry (SLP) assesses the integrity of the RNFL, a birefringent tissue, by measuring the total retardation in the light reflected from the retina. However, the anterior segment of the eye, mainly the cornea, is also birefringent, and its magnitude and axis vary over a wide range across the population. To accurately assess the RNFL retardation, Laser Diagnostic Technologies, Inc. has developed a new SLP system, GDx NFA, with custom corneal compensation (CCC). The GDx NFA system has an imaging field of 40 1/4 (H) by 20 1/4 (V), covering both the peripapillary region and the macular region. CCC consists of two identical linear retarders; its magnitude and axis are both adjustable. Anterior segment birefringence of an examined eye is determined from the retardation distributions of the macula with the CCC set to a null retardance; then the magnitude and axis of the CCC are adjusted to null the anterior segment birefringence and the RNFL retardation image is obtained. A normative database is developed for the GDx NFA system to provide an assessment of the RNFL health at a single visit, and a neural network trained with both healthy RNFL patterns and glaucomatous RNFL patterns is provided to assist clinicians to detect RNFL damage. The anterior segment birefringence can be determined accurately from the macular retardation image. With CCC, glaucomatous RNFL damage, both focal defect and diffuse defect, are readily identified. RNFL damages prior to visual field loss are observed in the early stages of glaucoma. There is a good correlation between the RNFL assessment by the GDx NFA and visual function test results.

  8. The Evaluation of Retinal Nerve Fiber Layer Thickness in Patients with Obstructive Sleep Apnea Syndrome

    PubMed Central

    Adam, Mehmet; Bozkurt, Banu; Kerimo?lu, Hrkan; Turan, Meydan

    2013-01-01

    Aim. To evaluate the retinal nerve fiber layer (RNFL) thickness in patients with obstructive sleep apnea syndrome (OSAS) by optical coherence tomography (OCT). Materials and Method. We studied 43 new diagnosed OSAS patients and 40 healthy volunteers. Patients underwent an overnight sleep study in an effort to diagnose and determine the severity of OSAS. RNFL analyses were performed using Stratus OCT. The average and the four-quadrant RNFL thickness were evaluated. Results. There was no difference between the average and the four-quadrant RNFL thickness in OSAS and control groups. There was no correlation between apnea-hypopnea index and intraocular pressure. Body mass index of patients with moderate and severe OSAS was significantly higher in patients with mild OSAS. Conclusion. Mean RNFL thickness did not differ between the healthy and the OSAS subjects, however, the parameters were more variable, with a larger range in OSAS patients compared to controls. PMID:24369492

  9. Degradation in the degree of polarization in human retinal nerve fiber layer

    NASA Astrophysics Data System (ADS)

    Yin, Biwei; Wang, Bingqing; Rylander, Henry G.; Milner, Thomas E.

    2014-01-01

    Using a fiber-based swept-source (SS) polarization-sensitive optical coherence tomography (PS-OCT) system, we investigate the degree of polarization (DOP) of light backscattered from the retinal nerve fiber layer (RNFL) in normal human subjects. Algorithms for processing data were developed to analyze the deviation in phase retardation and intensity of backscattered light in directions parallel and perpendicular to the nerve fiber axis (fast and slow axes of RNFL). Considering superior, inferior, and nasal quadrants, we observe the strongest degradation in the DOP with increasing RNFL depth in the temporal quadrant. Retinal ganglion cell axons in normal human subjects are known to have the smallest diameter in the temporal quadrant, and the greater degradation observed in the DOP suggests that higher polarimetric noise may be associated with neural structure in the temporal RNFL. The association between depth degradation in the DOP and RNFL structural properties may broaden the utility of PS-OCT as a functional imaging technique.

  10. Retinal nerve fiber layer thickness in prematurity is correlated with stage of retinopathy of prematurity.

    PubMed

    Park, K-A; Oh, S Y

    2015-12-01

    PurposeTo compare retinal nerve fiber layer (RNFL) thickness profiles between preterm and full-term children and to investigate factors affecting the RNFL distribution in preterm children.MethodsWe performed Spectral domain optical coherence tomography (SD-OCT) peripapillary RNFL circular scan centered on the optic disc in 50 premature and 58 full-term children. RNFL thickness profiles were compared between preterm and full-term children using a linear regression model. Among preterm patients in this study, 20 patients previously received laser treatment for severe retinopathy of prematurity (ROP).ResultsGlobal average, nasal, and superior disc RNFL thickness profiles were significantly smaller in preterm children (92.7016.57??m, 56.0217.04??m, and 108.7427.36??m, respectively) compared with full-term children (101.639.21??m, P=0.006, 69.1414.15??m, P<0.001, and superior, 129.1118.14??m, P<0.001, respectively). Multivariable analysis revealed that ROP stage was inversely correlated with nasal RNFL thickness (P=0.010).ConclusionsOur SD-OCT data demonstrate decreased global average, nasal, and superior disc RNFL thicknesses in preterm children. ROP stage was inversely correlated with nasal RNFL thickness. Further studies are needed to better understand the association between these structural changes and visual functions in preterm children. PMID:26403327

  11. Analysis of the Retinal Nerve Fiber Layer in Retinitis Pigmentosa Using Optic Coherence Tomography

    PubMed Central

    Y?ld?r?m, Medine Asl?; Erden, Burak; Tetiko?lu, Mehmet; Kuru, zlem; Elio?lu, Mustafa

    2015-01-01

    Aim. To evaluate the peripapillary retinal nerve fiber layer (RNFL) changes in retinitis pigmentosa (RP) patients using spectral domain optic coherence tomography (Sd-OCT). Methods. We retrospectively examined medical records of forty-four eyes of twenty-two RP patients. The results were also compared with those of previously reported forty-four eyes of twenty-two normal subjects (controls). Records of average and four quadrants peripapillary RNFL thickness measurements using Sd-OCT were assessed. Results. In RP patients the mean RNFL thickness was 97.57 3.21??m. The RNFL in the superior, temporal, nasal, and inferior quadrants was 119.18 4.47??m, 84.68 2.31??m, 75.09 3.34??m, and 113.88 4.25??m, respectively. While the thinning of RNFL was predominantly observed in the inferior quadrant, the thickening was mostly noted in temporal quadrant. The differences between mean, superior, and nasal quadrant RNFL thicknesses were not statistically significant when compared with control group. The RP patients had thinner inferior quadrant and thicker temporal quadrant than control group (p < 0.05). Conclusion. Sd-OCT is highly sensitive and effective instrument to detect RNFL changes in RP patients. RNFL measurements can provide information about the progression of retinitis pigmentosa and may provide prognostic indices for future treatment modalities. PMID:26351569

  12. Retinal Nerve Fiber Layer Thickness in Women with Polycystic Ovary Syndrome

    PubMed Central

    Demir, Mehmet; Guven, Dilek; Koc, Arzu; Ozdemir, Savas; Can, Efe

    2013-01-01

    Aim. To compare the retinal nerve fiber layer (RNFL) thickness between women with polycystic ovary syndrome (PCOS) and healthy women. Materials and Methods. The study included 88 eyes of 44 women (group 1) with PCOS and 84 eyes of 42 healthy women (group 2). In all subjects, the RNFL and ganglion cell complex (GCC) thicknesses were measured by optical coherence tomography (OCT). In addition, visual acuity (VA), intraocular pressure (IOP), refractive errors, central macular thickness (CMT), central corneal thickness (CCT), and excavation of optic disc were evaluated in all subjects. Results. Mean values of GCC, IOP, VA, CMT, CCT, and refractive errors were similar between the 2 groups. The average RNFL, superior average RNFL, and inferior average RNFL thicknesses were higher in subjects with PCOS than in healthy subjects (P = 0.003, P = 0.012, and P = 0.009), respectively. Conclusion. The average RNFL, superior average RNFL, and inferior average RNFL thicknesses in women with PCOS were significantly higher than in healthy women. PMID:24377044

  13. 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

  14. Depth-resolved birefringence imaging of the primate retinal nerve fiber layer using polarization-sensitive OCT

    NASA Astrophysics Data System (ADS)

    Kemp, Nathaniel J.; Park, Jesung; Marsack, Jason D.; Dave, Digant P.; Parekh, Sapun H.; Milner, Thomas E.; Rylander, Henry G., III

    2002-06-01

    Imaging the optical phase retardation per unit depth (OPR/UD) in the retinal nerve fiber layer (RNFL) may aid in glaucoma diagnosis. Polarization Sensitive Optical Coherence Tomography (PSOCT) was used to record in vivo high-resolution images of the RNFL in two cynomologous monkeys. The depth variation in the Stokes vector of reflected light was used to calculate the OPR/UD as a function of RNFL position. OPR/UD decreased from 35 degree(s)/100 micrometers near the optic nerve to 5 degree(s)/100 micrometers at a location 600 micrometers superior to the optic nerve. Variation of OPR/UD in the RNFL with retinal position demonstrates a change in birefringence for different densities of ganglion cell axons. PSOCT may be useful for noninvasive determination of RNFL thickness and fiber density.

  15. Reflectance Decreases before Thickness Changes in the Retinal Nerve Fiber Layer in Glaucomatous Retinas

    PubMed Central

    Zhou, Ye; Kong, Wei; Knighton, Robert W.

    2011-01-01

    Purpose. Glaucoma damages the retinal never fiber layer (RNFL). RNFL thickness, measured with optical coherence tomography (OCT), is often used in clinical assessment of the damage. In this study the relation between the RNFL reflectance and thickness at early stages of glaucoma was investigated. Methods. A rat model of glaucoma was used that involved laser photocoagulation of the trabecular meshwork. The reflectance of the RNFL in an isolated retina was measured, followed by immunohistochemical staining of the axonal cytoskeleton. RNFL thickness was measured by confocal fluorescence imaging. RNFL reflectance was calculated for bundle areas located at radii of 0.22, 0.33, and 0.44 mm from the optic nerve head (ONH) center. Linear regression was used to study the relation between reflectance and thickness. For glaucomatous eyes, only those bundles with no apparent structural damage were used. Results. Bundles in 11 control retinas and 10 treated retinas were examined. Bundle thickness of both groups at each radius was similar (P = 0.89). The reflectance of the bundles at radii of 0.33 and 0.44 mm was found to be similar in both control and treated retinas (P > 0.5). However, the reflectance of the bundles at the 0.22-mm radius decreased significantly in the treated group (P = 0.005). Conclusions. Elevation of intraocular pressure causes decrease in RNFL reflectance for bundles near the ONH. Change in RNFL reflectance precedes thinning of the RNFL. The results suggest that a decrease in RNFL reflectance near the ONH is an early sign of glaucomatous damage. PMID:21730345

  16. 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

  17. Physiological variation of retinal layer thickness is not caused by hydration: a randomised trial.

    PubMed

    Balk, Lisanne J; Oberwahrenbrock, Timm; Uitdehaag, Bernard M J; Petzold, Axel

    2014-09-15

    There is evidence for physiological variation of retinal thicknesses as determined by optical coherence tomography (OCT). We tested if such changes could be explained by hydration and would exceed what may be expected from normal ageing. Subjects (n=26) of a previous study were re-assessed and were randomised to 3 groups of a hydration escalation trial (no hydration, 1 hydration, 2 hydration). Automated retinal layer segmentations were performed for the macular retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL) and outer nuclear layer (ONL). The averaged volumes were calculated for the central foveola, 3 mm and 6 mm circles of the ETDRS grid. Following oral hydration there were no significant differences of retinal layer thicknesses between the three randomised groups in any of the ETDRS regions at any time-point. Ageing related changes were significant over an 18 month period for the GCL. The negative outcome of this trial implies that, until the causes for the observed variation are resolved, investigators may need to accept, and include into trial power calculations, a small degree of variation (<1%) of quantitative SD-OCT imaging either due to human physiology or instrument/software related factors. PMID:25005893

  18. 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 90.818. The mean ( standard deviation) post-injection RNFL thickness was 91.0315. 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

  19. 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

  20. 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

  1. Retinal nerve fiber layer thickness in vitiligo patients

    PubMed Central

    rnek, Nurgl; Onaran, Zafer; Koak, Mukadder; rnek, Kemal

    2013-01-01

    Background: This study was designed to investigate the effect of vitiligo on the retinal nerve fiber layer (RNFL) thickness. Materials and Methods: This prospective study was conducted in the Department of Ophthalmology at K?r?kkale University during 2010 and 2011. Sixty eight eyes of 34 vitiligo patients were included in the study. Eighty four eyes were served as control. RNFL thickness was measured by scanning laser polarimetry (Nerve Fiber Analyzer, GDx VCC: 5.3.3; Laser Diagnostic Technologies, San Diego, CA, USA). Results: The mean duration of vitiligo was found to be 9.8 2.3 years. The mean average RNFL thickness outside the disc margin was significantly lower in the right eyes of vitiligo group in comparison to the controls (P = 0.02). The mean average thickness of RNFL beneath the measuring ellipse in the superior sector of both eyes were significantly lower than the controls (P = 0.004, P = 0.008, respectively). The topographical distributions of RNFL thickness in superior, inferior, nasal and temporal quadrants were similar for two groups. Conclusion: RNFL thickness seems to be unaffected in vitiligo patients. PMID:24174946

  2. Estimated retinal ganglion cell counts in glaucomatous eyes with localized retinal nerve fiber layer defects

    PubMed Central

    Tatham, Andrew J.; Weinreb, Robert N.; Zangwill, Linda M.; Liebmann, Jeffrey M.; Girkin, Christopher A.; Medeiros, Felipe A.

    2013-01-01

    Purpose To estimate retinal ganglion cell (RGC) losses associated with visible glaucomatous localized retinal nerve fiber layer (RNFL) defects. Design Observational cross-sectional study. Methods A multicenter study of 198 normal eyes (138 subjects) and 66 glaucomatous eyes (55 subjects) recruited from the Diagnostic Innovations in Glaucoma Study and African Descent and Glaucoma Evaluation Study. All eyes had standard automated perimetry (SAP), spectral domain optical coherence tomography (SD-OCT) and fundus stereophotographs within 6 months. Glaucomatous eyes were included if localized RNFL defects were detected by masked grading of stereophotographs. The number of RGCs in each sector of a structure-function map was estimated using a previously published model combining RGC estimates from SAP and SD-OCT. The estimated percentage loss of RGCs (combined structure function index) was calculated. Results In glaucomatous eyes there were 136 sectors with visible RNFL defects and 524 sectors without visible RNFL defects. The commonest sectors with visible RNFL defects were inferior and inferotemporal sectors, followed by superior and superotemporal sectors. Eyes with visible RNFL defects had a mean estimated RGC count of 657,172 cells versus 968,883 cells in healthy eyes (P<0.001). The average combined structure function index in sectors with a visible RNFL defect (5921%) was significantly higher than in sectors without a visible RNFL defect in glaucomatous eyes (1529%, P<0.001) and higher than in healthy eyes (113%, P<0.001). Conclusions Although visible localized RNFL defects are often considered an early sign of glaucoma this study indicates that they are likely to be associated with large neuronal losses. PMID:23746612

  3. 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 ?m) 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 ?m, 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.

  4. 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

  5. Retinal nerve fiber layer thickness map determined from optical coherence tomography images

    NASA Astrophysics Data System (ADS)

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

    2005-11-01

    We introduce a method to determine the retinal nerve fiber layer (RNFL) thickness in OCT images based on anisotropic noise suppression and deformable splines. Spectral-Domain Optical Coherence Tomography (SDOCT) data was acquired at 29 kHz A-line rate with a depth resolution of 2.6 ?m and a depth range of 1.6 mm. Areas of 9.6x6.4 mm2 and 6.4x6.4 mm2 were acquired in approximately 6 seconds. The deformable spline algorithm determined the vitreous-RNFL and RNFL-ganglion cell/inner plexiform layer boundary, respectively, based on changes in the reflectivity, resulting in a quantitative estimation of the RNFL thickness. The thickness map was combined with an integrated reflectance map of the retina and a typical OCT movie to facilitate clinical interpretation of the OCT data. Large area maps of RNFL thickness will permit better longitudinal evaluation of RNFL thinning in glaucoma.

  6. 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

  7. 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

  8. Reproducibility of retinal nerve fiber layer measurements with manual and automated centration in healthy subjects using spectralis spectral-domain optical coherence tomography.

    PubMed

    Lange, Alex P; Sadjadi, Reza; Costello, Fiona; Guber, Ivo; Traboulsee, Anthony L

    2012-01-01

    Objective. The aim of this study was to test the reproducibility of the Heidelberg Spectralis SD-OCT and to determine if provided software retest function for follow-up exam is superior to manual centration. Design. Prospective, cross-sectional study. Participants. 20 healthy subjects. Methods. All subjects underwent SD-OCT testing to determine retinal nerve fiber layer (RNFL) measurements sequentially on two different days and with two different centration techniques. Within-subject standard deviation, coefficient of variation, and intraclass correlation coefficient were used to assess reproducibility. Results. RNFL measurements showed high reproducibility, low within-subject standard deviation (1.3), low coefficient of variation (0.63%), and low intra-class correlation coefficient (0.98 (95% CI 0.97-0.99)) in the automated centration and manual centration groups for average RNFL Thickness. Quadrants showed slightly higher variability in the manual group compared to the automated group (within-subject standard deviation 2.5-5.3 versus 1.1-2.4, resp.). Conclusions. SD-OCT provides high-resolution RNFL measurements with high reproducibility and low variability. The re-test function allows for easier recentration for longitudinal examinations with similar results in average RNFL, but less variability in quadrant RNFL. SD-OCT high reproducibility and low variability is a promising fact and should be further evaluated in longitudinal studies of RNFL. PMID:24558593

  9. Retinal Blood Vessel Distribution Correlates With the Peripapillary Retinal Nerve Fiber Layer Thickness Profile as Measured With GDx VCC and ECC

    PubMed Central

    Resch, Hemma; Pereira, Ivania; Weber, Stephanie; Holzer, Stephan; Fischer, Georg

    2015-01-01

    Purpose: Aim of the present study was to evaluate whether there is a correlation between retinal blood vessel density (RVD) and the peripapillary retinal nerve fiber layer (RNFL) thickness profile. Methods: RNFL thickness of 106 healthy subjects was measured using scanning laser polarimetry, GDx variable corneal compensation (VCC), and GDx enhanced corneal compensation (ECC). A proprietary software was developed in MATLAB to measure the peripapillary retinal vessels using scanning laser ophthalmoscopy fundus images, centered on the optic disc measured by Cirrus spectral domain optical coherence tomography. The individual retinal vessel positions and thickness values were integrated in a 64-sector RVD profile and intrasubject and intersubject correlations were calculated. Results: The mean R valueSD for intrasubject correlation between RVD and RNFL thickness measured with GDx VCC and GDx ECC was 0.7140.157 and 0.6290.140, with 105 of 106 subjects presenting significant correlations. In the intersubject linear regression analysis for GDx VCC, 33 of 64 (52%) sectors presented a significant Pearson correlation coefficient between RNFL thickness and RVD values, with a mean R value of 0.1870.135 (P<0.05). Conclusions: Peripapillary RNFL thickness profiles correlate with the RVD over 50% of the sectors and might explain up to 26% of the interindividual variance of the peripapillary RNFL thickness values as measured with GDx VCC. To our opinion, taking into account RVD might reduce interindividual variation in peripapillary RNFL thickness profiles measured with scanning laser polarimetry. PMID:25719231

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. Imaging of the optic disc and retinal nerve fiber layer: the effects of age, optic disc area, refractive error, and gender

    NASA Astrophysics Data System (ADS)

    Bowd, Christopher; Zangwill, Linda M.; Blumenthal, Eytan Z.; Vasile, Cristiana; Boehm, Andreas G.; Gokhale, Parag A.; Mohammadi, Kourosh; Amini, Payam; Sankary, Timothy M.; Weinreb, Robert N.

    2002-01-01

    We cross-sectionally examined the relationship between age, optic disc area, refraction, and gender and optic disc topography and retinal nerve fiber layer (RNFL) measurements, using optical imaging techniques. One eye from each of 155 Caucasian subjects (age range 23.0-80.8 y) without ocular pathology was included. Measurements were obtained by using the Heidelberg Retina Tomography (HRT), the GDx Nerve Fiber Analyzer, and the Optical Coherence Tomograph (OCT). The effects of age were small (R2<17%) and were limited to specific HRT, GDx, and OCT parameters. Disc area was significantly associated with most HRT parameters and isolated GDx and OCT parameters. Refraction and gender were not significantly associated with any optic disc or RNFL parameters. Although effects of age on the optic disc and RNFL are small, they should be considered in monitoring ocular disease. Optic disc area should be considered when cross-sectionally evaluating disc topography and, to a lesser extent, RNFL thickness.

  17. Phase retardation measurement of retinal nerve fiber layer using polarization-sensitive spectral domain optical coherence tomography and scanning laser polarimetry

    NASA Astrophysics Data System (ADS)

    Yamanari, Masahiro; Miura, Masahiro; Makita, Shuichi; Yatagai, Toyohiko; Yasuno, Yoshiaki

    2007-07-01

    Phase retardation of retinal nerve fiber layer (RNFL) is measured by polarization-sensitive spectral domain optical coherence tomography (PS-SD-OCT) and scanning laser polarimetry (SLP). In PS-SD-OCT, birefringence of the optical fiber and the cornea is compensated by Jones matrix based analysis. Three-dimensional phase retardation map around the optic nerve head and en face phase retardation map of the RNFL are shown. It is shown that the phase retardation curves around the optic nerve head measured by PS-SD-OCT and SLP have similar values. PS-SD-OCT can measure the cumulative phase retardation of RNFL as well as SLP and has a possibility to evaluate RNFL for glaucomatous eyes.

  18. 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

  19. Retinal nerve fiber layer and optic disc measurements by spectral domain OCT: normative values and associations in young adults

    PubMed Central

    Tariq, Y M; Li, H; Burlutsky, G; Mitchell, P

    2012-01-01

    Purpose To determine normative values and associations of retinal nerve fiber layer (RNFL) and optic disc parameters in normal eyes measured by spectral domain optical coherence tomography (OCT). Methods In a population-based setting, 1521 young adults were examined as part of the Sydney Adolescent Vascular and Eye Study (SAVES). Their mean age was 17.30.6 years. RNFL and optic disc parameter measurements were made using Cirrus HD-OCT 4000. Results The average RNFL was found to be 99.49.6??m. RNFL thickness was least for the temporal quadrant (69.911.2??m), followed by the nasal (74.312.8??m), superior (124.715.7??m) and inferior (128.817.1??m) quadrants. The mean disc area in this population was 1.980.38?mm2 with a mean rim area of 1.500.30?mm2 and a mean cup/disc ratio of 0.440.18. Multivariate-adjusted RNFL thickness was marginally greater in East Asian than in white participants (100.1??m vs 99.5??m; P=0.0005). The RNFL was thinner with greater axial length (P<0.0001), less positive spherical equivalent refractions (P<0.0001), smaller disc area and rim area (P<0.0001). Conclusion This study documents normative values for the RNFL and optic disc measured using Cirrus HD-OCT in young adults. The values and associations reported in this study can inform clinicians on the normal variation in RNFL and optic disc parameters. PMID:23079750

  20. Light Scattering from a Tenuous Cylindrical Matrix and the Reflectance of the Retinal Nerve Fiber Layer

    NASA Astrophysics Data System (ADS)

    Zhou, Qienyuan

    1994-01-01

    Evaluation of the retinal nerve fiber layer (RNFL) is used in the diagnosis of glaucoma and other optic nerve diseases which cause visual loss by damaging optic nerve fibers. Various optical methods are being developed to assess the RNFL directly as aids to diagnosis, and interpreting them requires a means to predict reflectance of the RNFL from a knowledge of its structure. Experimental studies show that light reflected by the RNFL has the geometry of light scattered by cylinders. Anatomical data were obtained from electron micrographs of cross-sections of amphibian RNFL and possible cylindrical scattering structures (axonal membranes, microtubules, and neurofilaments) were modeled as arrays of parallel thin fibers. Microtubules and neurofilaments are already thin fibers, and axonal membranes were decomposed into arrays of adjacent parallel fibers. A numerical method was developed to estimate the scattered field of the RNFL based on the simplified model. For an incident wave polarized parallel to the cylinder axis (TM mode), the internal field of each fiber was chosen equal to the incident field based on the Born approximation. For an incident wave polarized perpendicular to the cylinder axis (TE mode), the internal fields of microtubules and neurofilaments were also determined by the Born approximation, but the internal fields were assigned to each axonal membrane fiber by means of the modified Born approximation that depended on membrane orientation. Far field scattering was then calculated by field summation. Calculated scattering was much larger from axonal membranes than from microtubules or neurofilaments. Calculated spectra showed increased scattering at shorter wavelengths, which was consistent with the general tendency of measured spectra. Calculated backscattering from axonal membranes was approximately equal for the TM mode and the TE mode, but from microtubules TE mode scattering was less than TM mode. Calculated backscattering from the RNFL was proportional to its volume. Form birefringence of the RNFL was estimated statistically with the structural data obtained and the approximations for the internal field. A limitation of the model is that it regards the RNFL as a matrix of parallel cylinders. The existing misalignment in the actual RNFL should be considered in the future.

  1. Stress strain modelling and analysis of a piezo-coated optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Al-Raweshidy, H.; Ali, H.; Obayya, S. S. A.; Langley, R.; Batchelor, J.

    2005-02-01

    A finite element model, using commercially available software, is presented to simulate the piezoelectrically induced stresses and strains in an optical fibre to be used as antenna. These stresses and strains are generated by a layer of piezoelectric polymer deposited on the cladding of a short fibre sample. The theoretical basis for the work is briefly explained and the modelling process is emphasised. Two types of fibre are investigated - circular fibre and D-fibre, and the results compared, analysed and discussed. It is shown that in the D-fibre, the stress and displacement increased by 1.46 and 115 times, respectively, in comparison with the circular fibre.

  2. 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

  3. Opening up optical fibres.

    PubMed

    Cox, Felicity M; Lwin, Richard; Large, Maryanne C J; Cordeiro, Cristiano M B

    2007-09-17

    A unique optical fibre design is presented in this work: a laterally accessible microstructured optical fibre, in which one of the cladding holes is open to the surrounding environment and the waveguide core exposed over long lengths of fibre. Such a fibre offers the opportunity of real-time chemical sensing and biosensing not previously possible with conventional microstructured optical fibres, as well as the ability to functionalize the core of the fibre without interference from the cladding. The fabrication of such a fibre using PMMA is presented, as well as experimental results demonstrating the use of the fibre as a evanescent wave absorption spectroscopy pH sensor using the indicator Bromothymol Blue. PMID:19547546

  4. 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-Jnior, Jos Edvan; Garcia, Carlos Alexandre de Amorim; Soares, Elvira Maria Mafaldo; Maranho, Tcia Maria Oliveira; Lemos, Telma Maria Arajo 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

  5. 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

  6. Dyestuff-fibre interactions.

    PubMed

    Lewis, D M

    1996-06-01

    Synopsis The strength and nature of dye-fibre interactions vary according to fibre type and dye type. In the case of acid dyes for polyamide fibres, cationic dyes for acrylic fibres, disperse dyes for hydrophobic fibres, and direct dyes for cellulosic fibres, these interactions may be classified as non-covalent, a classification which includes van der Waals (VDW), electrostatic, induction, solvophobic and charge-transfer interactions. Reactive dyes are a notable exception to the above, since the interaction which is responsible for their excellent wet fastness is the dye-fibre covalent bond, however, these dyes are increasingly viewed as environmentally unfriendly due to high salt usage and residual unfixed colour. This situation may be improved by either incorporating amine sites in the cellulose or by reversing the system to incorporate reactive residues in the fibre and nucleophilic sites in the dye. Nonionic disperse dyes are valuable for hydrophobic fibres such as polyester but have made little impact on hydrophilic fibres such as silk, wool and cotton. Experiments to develop simple treatments to render the latter fibres disperse dyeable are described and the combined role of solvophobic and - interactions discussed. PMID:19245462

  7. 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

  8. 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

  9. Ultrafast fibre laser sources: Examples of recent developments

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. 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

  11. 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)

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. Developmental Changes in Cell Wall Structure of Phloem Fibres of the Bamboo Dendrocalamus asper

    PubMed Central

    GRITSCH, CRISTINA SANCHIS; KLEIST, GUNNAR; MURPHY, RICHARD J.

    2004-01-01

    Background and aims Bamboo culms have excellent physical and mechanical properties, which mainly depend on their fibre content and anatomical structure. One of the features which is known to contribute to the high tensile strength in bamboo is the multilayered structure of the fibre cell wall. The aim of this study was to characterize the development of the layered structure in fibre cell walls of developing and maturing culms of Dendrocalamus asper. Methods Cell wall development patterns were investigated in phloem fibre caps of vascular bundles in the inner culm wall areas of Dendrocalamus asper of three different age classes (<6 months old, 1 year old, 3 years old). A combination of light microscopy and image analysis techniques were employed to measure cell wall thickness and to determine number of cell wall layers, as well as to describe the layering structure of fibre walls. Two-dimensional maps showing the distribution pattern of fibres according to the number of cell wall layers were produced. Key results The cell walls of fibres in phloem fibre caps located in the inner part of the culm wall of D. asper developed rapidly during the first year of growth. Six different fibre types could be distinguished based upon their cell wall layering and all were already present in the young, 1-year-old culm. In the mature stage (3 years of age) the multilayering was independent of the cell wall thickness and even the thinner-walled fibres could have a large number of wall layers. The multilayered nature of cell wall structure varied considerably between individual cells and was not exclusively related to the cell wall thickness. Nevertheless, fibres at the periphery of the fibre bundles and immediately adjacent to the phloem elements exhibited a consistent and high degree of layering in their cell walls. Conclusions The multilayered structure of fibre cell walls was formed mainly during the first year of growth by the deposition of new wall layers of variable thickness, resulting in a high degree of heterogeneity in the layering patterns amongst individual fibres. A degree of order in the distribution of multilayered fibres within the caps does exist, however, with multilayered cell walls common in fibres adjacent to phloem elements and around the edge of the fibre cap. These findings confirm the observations, primarily in Phyllostachys viridi-glaucescens. The layering structure was not found to be specifically related to the thickness of the cell wall. PMID:15319227

  1. 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.

  2. 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.

  3. 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

  4. Ultrafast fibre lasers

    NASA Astrophysics Data System (ADS)

    Fermann, Martin E.; Hartl, Ingmar

    2013-11-01

    Ultrafast fibre lasers are fundamental building blocks of many photonic systems used in industrial and medical applications as well as for scientific research. Here, we review the essential components and operation regimes of ultrafast fibre lasers and discuss how they are instrumental in a variety of applications. In regards to laser technology, we discuss the present state of the art of large-mode-area fibres and their utilization in high-power, chirped-pulse amplification systems. In terms of commercial applications, we introduce industrial micromachining and medical imaging, and describe emerging applications in the mid-infrared and extreme-ultraviolet spectral regions, as facilitated by frequency shifting induced by fibre frequency combs.

  5. The Relationship Between Retinal Nerve Fiber Layer Thickness and Optic Nerve Head Neuroretinal Rim Tissue in Glaucoma

    PubMed Central

    Patel, Nimesh B.; Sullivan-Mee, Michael; Harwerth, Ronald S.

    2014-01-01

    Purpose. The purpose of this study was to determine the relationship between optical coherence tomography (OCT) measures of retinal nerve fiber layer (RNFL) and neuroretinal rim (NRR) in a nonhuman primate experimental glaucoma model, and in a population of clinical patients. Methods. For nonhuman primates, normative data were collected from 44 healthy monkeys, and nine animals with unilateral experimental glaucoma that were followed longitudinally. Cross-sectional human subjects data were collected from 89 healthy, 74 glaucoma suspects, and 104 glaucoma patients. Individualized transverse scaling for OCT scans was calculated using a schematic eye that incorporated optical ocular biometry. Custom algorithms were used to quantify RNFL thickness with and without vessels removed, scaled minimum rim width (sMRW), and neural rim volume (NRV). Results. For the experimental glaucoma group, NRR parameters showed the first changes with increased cumulative IOP. The data for both NRR and RNFL measures were best fit by an exponential rise model (NRV, R2 = 0.79, P < 0.01, sMRW, R2 = 0.74, P < 0.01). The major retinal vascular thickness contribution to the RNFL decreased (0.03 ?m/?m, P < 0.01) with RNFL loss, but the percent vascular contribution increased (?0.1%/?m, P < 0.01) with disease progression. Overall, the findings for the cross-sectional human data were similar to those of the experimental model. Conclusions. The findings illustrate a nonlinear relationship between NRR and RNFL measures and provide support for the use of multiple OCT scaled morphological measures for the diagnosis and management of primary open angle glaucoma in humans. PMID:25249610

  6. Bruchs 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, Bruchs 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 (2090 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 m/y and ?0.21 m/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

  7. Fibre Bragg grating sensors in polymer optical fibres

    NASA Astrophysics Data System (ADS)

    Webb, David J.

    2015-09-01

    This review paper summarizes the current state of research into polymer optical fibre grating sensors. The properties of polymers are explored to identify situations where polymers offer potential advantages over more conventional silica fibre sensing technology. Photosensitivity is discussed and the sensitivities of polymer fibre gratings to strain, temperature and water are described. Finally, applications are reported which utilize the unique properties of polymer fibres.

  8. [Damage of macular ganglion cell complex and peripapillary retinal nerve fiber layer in multiple sclerosis].

    PubMed

    Davydovskaia, M V; Tsysar', M A; Bo?ko, A N; Akopian, V S; Semenova, N S; Filonenko, I V; Fomin, A V; Gusev, E I

    2012-01-01

    The aim of this study was to evaluate macular ganglion cell complex (GCC) characteristics and peripapillary retinal nerve fiber layer (RNFL) thickness in patients with multiple sclerosis (MS) and to investigate the associations between these parameters and clinical characteristics of patients for evaluation perspectives of using this method for monitoring of disability and neurodegenerative processes. We examined a total of 113 participants (analysis of 211 eyes), divided into three groups: 1. 48 MS patients (66 eyes) with a history of optic neuritis (ON); 2. 35 MS patients (70 eyes) without a history of ON; 3. 30 disease-free control subjects (45 eyes). The estudy included anamnesis collection, neurological examination with assessment of EDSS scores. Refracted visual acuity prior to optical coherence tomography (OCT) was tested. RTVue-100 ??? system was used to assess peripapillary RNFL thickness and macular inner parameter (protocol GCC). The strongly correlated decline of the most RNFL and GCC indices was characteristic of all groups of MS patients with and without ON compared to controls. The damage of GCC was greater in patients with ON. The inverse correlation was found between the indices studied and the level of patient's disability. The study of GCC and RNFL thickness can be used to describe and characterize the level of axonal damage in MS and for objectification of neurodegenerative process in studies on neuroprotection and neuroreparation. PMID:22677679

  9. Manufacture of carbon fibres

    SciTech Connect

    Bailly-Lacresse, J.G.; Bonzom, A.; Crepaux, A.P.; Thomas, P.G.

    1980-04-08

    The invention relates to a process for the manufacture of carbon and/or graphite fibres from natural organic fibres, obtained particularly from the distillation residues of coal or petroleum, by irradiation by microwaves. The process according to the invention consists in subjecting the fibres to a preparatory thermal treatment up to a temperature of between 300/sup 0/ and 1500/sup 0/C in an inert atmosphere, for example of nitrogen, argon, helium or hydrogen and then irradiating them with microwaves. The microwaves may have frequencies between 900 and 30,000 mhz and preferably between 2000 and 15,000 mhz and use a power of between 10w and 30kw and preferably between 50w and 10kw. The irradiation is preferably also in an inert atmosphere, for a period ranging from 10 seconds to 15 minutes. The fibres may be oxidized for example in an atmosphere of oxygen, ozone or air up to a temperature of between 100 and 250/sup 0/C before the preparatory thermal treatment. The carbon and/or graphite fibres thus obtained, having an improved breaking strength, are used particularly for the reinforcement of plastic materials.

  10. Dynamically reconfigurable fibre optical spanner.

    PubMed

    Kolb, Thorsten; Albert, Sahradha; Haug, Michael; Whyte, Graeme

    2014-03-21

    In this paper we describe a pneumatically actuated fibre-optic spanner integrated into a microfluidic Lab-on-a-Chip device for the controlled trapping and rotation of living cells. The dynamic nature of the system allows interactive control over the rotation speed with the same optical power. The use of a multi-layer device makes it possible to rotate a cell both in the imaging plane and also in a perpendicular plane allowing tomographic imaging of the trapped living cell. The integrated device allows easy operation and by combining it with high-resolution confocal microscopy we show for the first time that the pattern of rotation can give information regarding the sub-cellular composition of a rotated cell. PMID:24493284

  11. Fibre gratings and their applications

    SciTech Connect

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

    2005-12-31

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

  12. 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

  13. 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

  14. 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

  15. Sensing with microstructured optical fibres

    NASA Astrophysics Data System (ADS)

    Monro, Tanya M.; Belardi, Walter; Furusawa, Kentaro; Baggett, Joanne C.; Broderick, N. G. R.; Richardson, D. J.

    2001-07-01

    The optical and geometrical properties of microstructured optical fibres present new alternatives for a range of sensing applications. We present the design criteria for achieving significant overlap between the light guided in the fibre and the air holes and hence for producing efficient evanescent field devices. In addition, the novel dispersive properties combined with the tight mode confinement possible in holey fibres make ultra-broadband single-mode sources and new source wavelengths a possibility. Microstructuring technology can be readily extended to form multiple-core fibres, which have applications in bend/deformation sensing. Finally, fibre-based atom waveguides could ultimately be used for rotational or gravitational sensing.

  16. 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.

  17. Numerical Modelling of Fibre Metal Laminates Subjected to Blast Loading

    NASA Astrophysics Data System (ADS)

    Guan, Z. W.; Cantwell, W. J.

    2010-05-01

    In this paper, finite element models were developed to simulate fibre metal laminates subjected to various blast loadings with typical pressure-time patterns. The aluminium (alloy grade 2024-0) layer was modelled as an isotropic elasto-plastic material up to the on-set of post failure stage, followed by shear failure and tensile failure to simulate its failure mechanism. The glass fibre laminate (woven glass-fibre/polypropylene matrix composite) layer was modelled as an orthotropic material up to its on-set of damage, followed by damage initiation and evolution using the Hashin criterion. The damage initiation was controlled by failure tensile and compressive stresses within the lamina plane which were primarily determined by tests. The damage evolution was controlled by tensile/compressive fracture energies combined both fibre and matrix. Discussions were given to cover difficulties faced during development of the modelling. The FE models developed for 2/1 and 3/2 fibre metal laminates with different GFPP layer thicknesses were validated against the corresponding experimental results. Good correlation was obtained in terms of failure modes and permanent displacements. Using validated models, parametric studies may be further carried out to cover FMLs made with various stack sequences and layer thicknesses.

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

    NASA Astrophysics Data System (ADS)

    Cense, Barry; Chen, Teresa C.; Park, Boris H.; Pierce, Mark C.; de Boer, Johannes F.

    2003-07-01

    We present 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 real-time images of the human retina in vivo, co-registered with video images of the location of PS-OCT scans on the retina. Preliminary measurements of a healthy volunteer showed that the double-pass phase retardation per unit depth of the RNFL varies with location with values in between 0.18 and 0.37 / um. A trend in the preliminary measurements shows that thicker nerve fiber layer tissue is more birefringent than thin nerve fiber layer tissue.

  19. 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

  20. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

    Pour faire face la crise conomique la conception de papier valeur ajoute est dveloppe par les industries papetires. Le but de se projet est l'amlioration des techniques actuelles de rticulation des fibres lignocellulosiques de la pte papier visant produire un papier plus rsistant. En effet, lors des ractions de rticulation traditionnelles, de nombreuses liaisons intra-fibres se forment ce qui affecte ngativement l'amlioration anticipe des proprits physiques du papier ou du matriau produit. Pour viter la formation de ces liaisons intra-fibres, un greffage sur les fibres de groupements ne pouvant pas ragir entre eux est ncessaire. La rticulation des fibres par une raction de click chemistry appele cycloaddition de Huisgen entre un azide et un alcyne vrai, catalyse par du cuivre (CuAAC) a t l'une des solutions trouve pour remdier ce problme. De plus, une adaptation de cette raction en milieux aqueux pourrait favoriser son utilisation en milieu industriel. L'tude que nous dsirons entreprendre lors de ce projet vise optimiser la raction de CuAAC et les ractions intermdiaires (propargylation, tosylation et azidation) sur la pte kraft, en milieu aqueux. Pour cela, les ractions ont t adaptes en milieu aqueux sur la cellulose microcristalline afin de vrifier sa faisabilit, puis transfre la pte kraft et l'influence de diffrents paramtres comme le temps de raction ou la quantit de ractifs utilise a t tudie. Dans un second temps, une tude des diffrentes proprits confres au papier par les ractions a t ralise partir d'une srie de tests papetiers optiques et physiques. Mots Cls Click chemistry, Huisgen, CuAAC, propargylation, tosylation, azidation, cellulose, pte kraft, milieu aqueux, papier.

  1. Relationship between birefringence and neurotubule density in the primate retinal nerve fiber layer

    NASA Astrophysics Data System (ADS)

    Aranibar, R. G.; Kemp, N. J.; Dwelle, J. C.; Byers, S. E.; Markey, M. K.; Milner, T. E.; Rylander, H. G.

    2007-02-01

    The relationship between retinal nerve fiber layer (RNFL) birefringence (?n) and neurotubule density (NTD, retinal ganglion cell (RGC) neurotubules per unit RNFL area) was investigated by correlating measurements of these two parameters in 1 eye of a healthy cynomolgus monkey. Phase retardation per unit depth (PR/UD, proportional to ?n) was measured at 5.6-15 intervals around the optic nerve head (ONH) with an enhanced polarization-sensitive optical coherence tomography (EPS-OCT) instrument. Transverse tissue sections containing 3 RGC nerve fiber bundles from each peripapillary RNFL octant were imaged with a transmission electron microscope (TEM). Morphological measurements taken in TEM images were used by a novel algorithm to estimate NTD. Registered PR/UD and NTD data were then correlated using single- and multi-level models, yielding correlation coefficients in the range 0.49 <= r <= 0.61 (0.06 <= P <= 0.11). It was found that in order for the single-level correlation coefficient (r = 0.61) to be statistically significant (P <= 0.05) and powerful (Power >= 80%), NTD measurements in at least 16, rather than 8, RNFL sectors were needed. Interestingly, a single-level correlation coefficient of r = 0.81 (P = 0.01) was calculated between octant-averaged PR/UD and RGC axoplasmic area (A x, axon area less non-cytoskeletal organelle area) mode. A x represents a RGC axon's neurotubule-inhabitable area. Intuitively, a strong relationship should exist between A x and neurotubule number if neurotubules provide the primary structural support for RGC axons and structural requirements are the same in all RGC axons. If this relationship exists, error resulting from NTD estimation methods or preservation artifacts may have caused lower observed correlations of PR/UD with NTD than with A x mode, and more accurate methods of measuring in vivo NTD may be required to determine an accurate relationship between RNFL birefringence and NTD.

  2. 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.

  3. Abnormal climbing fibre-Purkinje cell synaptic connections in the essential tremor cerebellum

    PubMed Central

    Lin, Chi-Ying; Louis, Elan D.; Faust, Phyllis L.; Koeppen, Arnulf H.; Vonsattel, Jean-Paul G.

    2014-01-01

    Structural changes in Purkinje cells have been identified in the essential tremor cerebellum, although the mechanisms that underlie these changes remain poorly understood. Climbing fibres provide one of the major excitatory inputs to Purkinje cells, and climbing fibre-Purkinje cell connections are essential for normal cerebellar-mediated motor control. The distribution of climbing fibre-Purkinje cell synapses on Purkinje cell dendrites is dynamically regulated and may be altered in disease states. The aim of the present study was to examine the density and distribution of climbing fibre-Purkinje cell synapses using post-mortem cerebellar tissue of essential tremor cases and controls. Using vesicular glutamate transporter type 2 immunohistochemistry, we labelled climbing fibre-Purkinje cell synapses of 12 essential tremor cases and 13 age-matched controls from the New York Brain Bank. Normally, climbing fibres form synapses mainly on the thick, proximal Purkinje cell dendrites in the inner portion of the molecular layer, whereas parallel fibres form synapses on the thin, distal Purkinje cell spiny branchlets. We observed that, compared with controls, essential tremor cases had decreased climbing fibre-Purkinje cell synaptic density, more climbing fibres extending to the outer portion of the molecular layer, and more climbing fibre-Purkinje cell synapses on the thin Purkinje cell spiny branchlets. Interestingly, in essential tremor, the increased distribution of climbing fibre-Purkinje cell synapses on the thin Purkinje cell branchlets was inversely associated with clinical tremor severity, indicating a close relationship between the altered distribution of climbing fibre-Purkinje cell connections and tremor. These findings suggest that abnormal climbing fibre-Purkinje cell connections could be of importance in the pathogenesis of essential tremor. PMID:25273997

  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 12.2?m and 4.7?m 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. Cross-Sectional Study of the Retinal Nerve Fiber Layer Thickness at 7 Years After an Acute Episode of Unilateral Primary Acute Angle Closure

    PubMed Central

    Lee, Jacky W.Y.; Woo, Tiffany T.Y.; Yau, Gordon S.K.; Yip, Stan; Yick, Doris W.F.; Wong, Jasper; Wong, Raymond L.M.; Wong, Ian Y.H.

    2015-01-01

    Abstract The purpose of this article is to investigate the long-term retinal nerve fiber layer (RNFL) status and determinants of RNFL thinning after an episode of unilateral primary acute angle closure (AAC). This cross-sectional study analyzed the medical records of consecutive patients with a single episode of unilateral AAC from 1999 to 2009 in Hong Kong. The peripapillary RNFL thickness was correlated with age, gender, presenting intraocular pressure (IOP), time to laser iridotomy, time to cataract extraction, follow-up duration, as well as the last IOP, vertical cup-to-disc ratio (CDR), and vision. The fellow uninvolved eye was used as a proxy comparison of RNFL loss in the attack eye. In 40 eligible patients, the mean age was 68.3??8.7 years with a male-to-female ratio of 1:7. The mean presenting IOP was 49.2??14.0 mm Hg and the time from presentation to laser iridotomy was 6.7??6.9 days. Forty percent of subjects received a cataract extraction at 3.2??2.9 years after the attack. The last IOP, CDR, and LogMAR vision were 16.0??3.8 mm Hg, 0.6??0.2, and 0.6??0.6 LogMAR units, respectively, at 7.9??2.4 years. The RNFL thickness in the attack eye (69.2??19.1??m) was 25.2??17.9% thinner than the fellow eye (93.0??17.8??m) at 7.5??2.9 years post-AAC. Using univariate analysis, the last vertical CDR (odds ratio [OR]?=?17.2, P?=?0.049) and LogMAR visual acuity (VA) (OR?=?6.6, P?=?0.03) were the only significant predictors for RNFL thinning whereas none of the other covariates showed significant associations (P?>?0.1). At 7.5 years following unilateral AAC, the RNFL thickness was 25% thinner than the fellow eye. CDR enlargement and poor VA were the only significant predictors for RNFL loss. PMID:25590844

  7. 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

  8. 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

  9. Distributed ultrafast fibre laser.

    PubMed

    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. 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

  11. 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.

  12. 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.

  13. Sulphur-doped silica fibres

    SciTech Connect

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

    2003-01-31

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

  14. 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 ?m) compared to controls (98.0 ?m) (p < 0.05). MS mainly affected the temporal quadrant (56.6 ?m versus [vs.] 67.8 ?m) (p < 0.05), and inferior quadrant (117.9 ?m vs. 132.1 ?m) (p < 0.05), respectively. Also, the patients with MS demonstrated significantly decreased average macular thickness (280 ?m) compared to the control group (287 ?m) (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

  15. 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

  16. 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

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

    NASA Astrophysics Data System (ADS)

    Cense, Barry; Chen, Teresa; Park, Boris H.; Pierce, Mark C.; de Boer, Johannes F.

    2003-07-01

    We present 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 real-time images of the human retina in vivo, co-registered with video images of the location of PS-OCT scans on the retina. Preliminary measurements of a healthy volunteer showed that the double-pass phase retardation per unit depth of the RNFL varies with location with values in between 0.18 and 0.37/?m. A trend in the preliminary measurements shows that thicker nerve fiber layer tissue is more birefringent than thin nerve fiber layer tissue.

  18. Finite element homogenization technique for the characterization of d15 shear piezoelectric macro-fibre composites

    NASA Astrophysics Data System (ADS)

    Trindade, M. A.; Benjeddou, A.

    2011-07-01

    A finite element homogenization method for a shear actuated d15 macro-fibre composite (MFC) made of seven layers (Kapton, acrylic, electrode, piezoceramic fibre and epoxy composite, electrode, acrylic, Kapton) is proposed and used for the characterization of its effective material properties. The methodology is first validated for the MFC active layer only, made of piezoceramic fibre and epoxy, through comparison with previously published analytical results. Then, the methodology is applied to the seven-layer MFC. It is shown that the packaging reduces significantly the shear stiffness of the piezoceramic material and, thus, leads to significantly smaller effective electromechanical coupling coefficient k15 and piezoelectric stress constant e15 when compared to the piezoceramic fibre properties. However, it is found that the piezoelectric charge constant d15 is less affected by the softer layers required by the MFC packaging.

  19. 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

  20. 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.

  1. 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

  2. High-power fibre lasers

    NASA Astrophysics Data System (ADS)

    Jauregui, Cesar; Limpert, Jens; Tnnermann, Andreas

    2013-11-01

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

  3. 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

  4. Speciality optical fibres for astronomy

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  5. 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 W and measured axial resolution was 17 m 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

  6. 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.

  7. Compressive strength of fibre composites with random fibre waviness

    NASA Astrophysics Data System (ADS)

    Liu, D.; Fleck, N. A.; Sutcliffe, M. P. F.

    2004-07-01

    The compressive strength of unidirectional long fibre composites is predicted for plastic microbuckling from a random two-dimensional distribution of fibre waviness. The effect of the physical size of waviness is addressed by using couple stress theory, with the fibre bending resistance scaling with the fibre diameter d. The predicted statistical distribution of compressive strength is found using a Monte Carlo method. An ensemble of fibre waviness profiles is generated from an assumed spectral density of waviness and the compressive strength for each such realisation is calculated directly by the finite element method. The average predicted strength agrees reasonably with practical values, confirming the hypothesis that microbuckles can be initiated by fibre misalignment. It is found that the probability distribution of strength is well matched by a Weibull fit, and the dependence of the Weibull parameters upon the spectral density of waviness is determined. For the practical range of fibre distributions considered, it is concluded that the strength depends mainly upon the root mean square amplitude of fibre misalignment, with the shape of the power spectral density function playing only a minor role. An engineering model for predicting the compressive strength is proposed, akin to weakest link theory for materials containing flaws. A specimen containing randomly distributed waviness is examined to locate regions of high-fibre misalignment. The strength of each of these weak regions is estimated from a look-up table derived from calculations with idealised circular or elliptical patches of waviness. The strength of the composite is given by the failure stress associated with the weakest such patch. For random distributions of waviness, the predictions using this engineering approach are in good agreement with the direct calculations of strength using the finite element method.

  8. 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)

  9. 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

  10. Peripapillary Retinal Nerve Fiber Layer Changes in Preclinical Diabetic Retinopathy: A Meta-Analysis

    PubMed Central

    Chen, Xiaofei; Nie, Chuang; Gong, Yan; Zhang, Ying; Jin, Xin; Wei, Shihui; Zhang, Maonian

    2015-01-01

    Background Diabetic retinopathy is a microvascular neurodegenerative disorder in diabetic patients. Peripapillary retinal nerve fiber layer changes have been described in patients with preclinical diabetic retinopathy, but study results have been inconsistent. Objective To assess changes in peripapillary retinal nerve fiber layer thickness in diabetic patients with preclinical diabetic retinopathy. Methods A literature search was conducted through PubMed, EMBASE, Web of Science and Cochrane Library. Case-control studies on RNFL thickness in preclinical diabetic retinopathy patients and healthy controls were retrieved. A meta-analysis of weighted mean difference and a sensitivity analysis were performed using RevMan 5.2 software. Results Thirteen case-control studies containing 668 diabetic patients and 556 healthy controls were selected. Peripapillary RNFL thickness was significantly reduced in patients with preclinical diabetic retinopathy compared to healthy controls in studies applying Optical Coherence Tomography (-2.88?m, 95%CI: -4.44 to -1.32, P = 0.0003) and in studies applying Scanning Laser Polarimeter (-4.21?m, 95%CI: -6.45 to -1.97, P = 0.0002). Reduction of RNFL thickness was significant in the superior quadrant (-3.79?m, 95%CI: -7.08 to -0.50, P = 0.02), the inferior quadrant (-2.99?m, 95%CI: -5.44 to -0.54, P = 0.02) and the nasal quadrant (-2.88?m, 95%CI: -4.93 to -0.82, P = 0.006), but was not significant in the temporal quadrant (-1.22?m, 95%CI: -3.21 to 0.76, P = 0.23), in diabetic patients. Conclusion Peripapillary RNFL thickness was significantly decreased in preclinical diabetic retinopathy patients compared to healthy control. Neurodegenerative changes due to preclinical diabetic retinopathy need more attention. PMID:25965421

  11. 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)

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. Evaluation of the Macular, Peripapillary Nerve Fiber Layer and Choroid Thickness Changes in Behet's Disease with Spectral-Domain OCT

    PubMed Central

    Ata?, Mustafa; Yuvac?, ?sa; Demircan, Sleyman; Gler, Emel; Altunel, Orhan; Pangal, Emine; Gkta?, Altan; Stbeyaz, Serap; Zarars?z, Gkmen

    2014-01-01

    Purpose. To assess the macular, choroid, and peripapillary nerve fiber layer thickness (RNFL) in Behet's disease (BD) patients with and without ocular involvement by means of optical coherence tomography (OCT) and compare these findings with healthy controls. Design. Eighty patients with BD and 40 healthy controls who were followed up at the Uveitis and Retina Clinic of the Kayseri Research and Education Hospital in Turkey were enrolled in this prospective study. Subjects and Controls. The patients with BD were divided into two groups according to the presence of ocular involvement. Group 1 consisted of 40 eyes of 40 patients with ocular involvement and group 2 consisted of 40 eyes of 40 patients without ocular involvement. Methods. All of the patients and controls underwent macular, choroid, and peripapillary nerve fiber layer thickness analysis with Spectralis domain OCT (Spectralis OCT Heidelberg Engineering, Dossenheim, Germany). Main Outcome Measures. The differences in macular, choroid, and peripapillary nerve fiber layer thicknesses between groups were analyzed statistically. Results. Macular thickness was thinner in patients with BD than in the control group; this result was statistically significant (P = 0.05). There was no statistically significant difference in thickness between RNFL analysis of the patients with BD and control subjects. However, the BD patients with ocular involvement had statistically significant thinning in RNFL compared with BD patients without ocular involvement. Although the choroid was thicker in patients with BD than in the control group, it did not reach a statistically significant level (P = 0.382). Conclusions. BD with ocular involvement may be associated with decreased macular and RNFL thickness measured with spectral-domain OCT. PMID:24868459

  20. 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

  1. 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.

  2. Analysis of nerve fiber layer measurements obtained from scanning laser polarimetry for glaucoma detection

    NASA Astrophysics Data System (ADS)

    Bhatt, Mittal G.; Rao, Navalgund

    2005-04-01

    New analysis tools to address the problem of early detection of the eye blinding disease glaucoma are presented. The thickness maps of the Retinal Nerve Fiber Layer (RNFL) corresponding to 184 eyes (92 Normal and 92 Glaucoma Patients) were obtained from a Scanning Laser Polarimeter (Gdx-VCC). The two dimensional data was used to draw features as opposed to the circular band one-dimensional data in previous approaches. Fourier analysis was performed on the 90 projection of the thickness map data to emphasize the shape contained in the RNFL. Different parameters from the Fourier Coefficients were drawn and tested for their ability to detect glaucoma. Significant differences were found in the shape measures of the projections and the ROC curve analysis was done to measure the separability of the sample set with those features. Another approach was to analyze the shape of the entire 2 dimensional thickness map through a 2D Fourier Transform. A circular ring band (10 pixel wide) data at a radius of 20 pixels was analyzed for this 2D FT. Principal Component Analysis was performed on this data for dimension reduction of feature space. Finally Fisher"s linear discriminant function (LDF) was used as a classifier. The evaluation of different parameters obtained through the Fourier analysis of the thickness map image of RNFL was found to be a useful tool as an analysis strategy for glaucoma detection.

  3. 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

  4. The Utilization of Retinal Nerve Fiber Layer Thickness to Predict Cognitive Deterioration.

    PubMed

    Shi, Zhongyong; Zhu, Yingbo; Wang, Meijuan; Wu, Yujie; Cao, Jing; Li, Chunbo; Xie, Zhongcong; Shen, Yuan

    2015-10-01

    Our previous studies have shown that longitudinal reduction in retinal nerve fiber layer (RNFL) thickness is associated with cognitive deterioration. However, whether the combination of longitudinal reduction in RNFL thickness with baseline episodic memory performance can better predict cognitive deterioration remains unknown. Therefore, we set out to re-analyze the data obtained from our previous studies with 78 elderly adults (mean age 74.4 3.83 years, 48.7% male) in the community over a 25-month period. The participants were categorized as either stable participants whose cognitive status did not change (n?=?60) or converted participants whose cognitive status deteriorated (n?=?18). A logistic regression analysis was applied to determine a conversion score for predicting the cognitive deterioration in the participants. We found that the area under the receiver operating characteristic curve (AUC) for the multivariable model was 0.854 (95% CI 0.762-0.947) using baseline story recall as a predictor, but the AUC increased to 0.915 (95% CI 0.849-0.981) with the addition of the longitudinal reduction of RNFL thickness in the inferior quadrant. The conversion score was significantly higher for the converted participants than the stable participants (0.59 0.30 versus 0.12 0.19, p?< ?0.001). Finally, the optimal cutoff value of the conversion score (0.134) was determined by the analysis of receiver operating characteristic curve, and this conversion score generated a sensitivity of 0.944 and a specificity of 0.767 in predicting the cognitive deterioration. These findings have established a system to perform a larger scale study to further test whether the longitudinal reduction in RNFL thickness could serve as a biomarker of Alzheimer's disease. PMID:26484909

  5. The Anterior Chamber Depth and Retinal Nerve Fiber Layer Thickness in Children

    PubMed Central

    Lee, Jacky W. Y.; Yau, Gordon S. K.; Woo, Tiffany T. Y.; Yick, Doris W. F.; Tam, Victor T. Y.; Yuen, Can Y. F.

    2014-01-01

    Purpose. To investigate the correlation of anterior chamber depth (ACD) with the peripapillary retinal nerve fiber layer (RNFL) thickness, age, axial length (AL), and spherical equivalent in children. Subjects. Consecutive subjects aged 4 to 18 were recruited. Visually disabling eye conditions were excluded. Only the right eye was included for analysis. The ACD was correlated with RNFL thickness, age, spherical equivalent, and AL for all subjects. Subjects were then divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (+1.0 D). The ACD was compared among the 3 groups before and after age adjustment. Results. In 200 subjects (mean age 7.6 3.3 years), a deeper ACD was correlated with thinner global RNFL (r = ?0.2, r2 = 0.06, P = 0.0007), older age (r = 0.4, r2 = 0.1, P < 0.0001), myopic spherical equivalent (r = ?0.3, r2 = 0.09, P < 0.0001), and longer AL (r = 0.5, r2 = 0.2, P < 0.0001). The ACD was deepest in myopes (3.5 0.4?mm, n = 67), followed by emmetropes (3.4 0.3, n = 60) and then hyperopes (3.3 0.2, n = 73) (all P < 0.0001). After age adjustment, myopes had a deeper ACD than the other 2 groups (all P < 0.0001). Conclusions. In children, a deeper ACD was associated with thinner RNFL thickness, older age, more myopic spherical equivalent, and longer AL. Myopes had a deeper ACD than emmetropes and hyperopes. PMID:25431789

  6. 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

  7. 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 ?m.

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

    SciTech Connect

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

    2004-09-30

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

  9. 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

  10. Multifunctional, supramolecular, continuous artificial nacre fibres

    NASA Astrophysics Data System (ADS)

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-10-01

    Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized ``brick-and-mortar'' (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance.

  11. 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

  12. Optical fibre modulator based on electrostatic attraction

    NASA Astrophysics Data System (ADS)

    de Matos, C. J. S.; Margulis, W.

    2001-04-01

    A fibre-based electrostatic deflector is described that enables modulating the optical signal in fibre systems. A 2.5-cm long fibre length was gold coated and deflected through the application of voltage between the fibre and an external electrode. Static measurements showed that the device is suitable for e-field sensing, and 100% power modulation was obtained for resonant frequencies 1 kHz. A peak voltage as low as 2 V gave a 15% modulation depth with 65 ?m diameter fibre, and the maximum frequency measured for a 65 ?m fibre was 40 kHz. In a proof-of-principle experiment, a 1.61-?m wavelength Er 3+/Yb 3+ fibre laser was Q-switched by placing the electrostatic fibre modulator inside the cavity, generating pulses of 4-?s duration.

  13. 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)

  14. 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

  15. 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

  16. Segmentation of retinal layers in volumetric OCT scans of normal and glaucomatous subjects

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Volumetric scans of current SD-OCT devices can contain on the order of 50 million pixels. Due to this size and because quantitative measurements in these scans are often needed, automatic segmentation of these scans is required. In this paper, a fully automatic retinal layer segmentation algorithm is presented, based on pixel-classification. First, each pixel is augmented by intensity and gradient data from a local neighborhood, thereby producing a feature vector. These feature vectors are used as inputs for a support vector machine, which classifies each pixel as above or below each interface. Finally, a level set method regularizes the result, producing a smooth surface within the three-dimensional space. Volumetric scans of 10 healthy and 8 glaucomatous subjects were acquired with a Spectralis OCT. Each scan consisted of 193 B-scans, 512 A-lines per B-scan (5 times averaging) and 496 pixels per A-line. Two B-scans of each healthy subject were manually segmented and used to train the support vector machine. One B-scan of each glaucomatous subjects was manually segmented and used only for performance assessment of the algorithm. The root-mean-square errors for the normal eyes were 3.7, 15.4, 15.0 and 5.5 ?m for the vitreous/retinal nerve fiber layer (RNFL), RNFL/ganglion cell layer, inner plexiform layer/inner nuclear layer and retinal pigment epithelium/choroid interfaces, respectively, and 5.5, 11.5, 9.5 and 6.2 ?m for the glaucomatous eyes. Based on the segmentation, retinal and RNFL thickness maps and blood vessel masks were produced.

  17. 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.

  18. 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 ...

  19. Ultrastructure of Fibre and Parenchyma Cell Walls During Early Stages of Culm Development in Dendrocalamus asper

    PubMed Central

    GRITSCH, CRISTINA SANCHIS; MURPHY, RICHARD J.

    2005-01-01

    Background and Aims The anatomy of bamboo culms and the multilayered structure of fibre cell walls are known to be the main determinant factors for its physical and mechanical properties. Studies on the bamboo cell wall have focussed mainly on fully elongated and mature fibres. The main aim of this study was to describe the ultrastructure of primary and secondary cell walls in culm tissues of Dendrocalamus asper at different stages of development. Methods The development of fibre and parenchyma tissues was classified into four stages based on light microscopy observations made in tissues from juvenile plants. The stages were used as a basis for transmission electron microscopy study on the ultrastructure of the cell wall during the process of primary and early secondary cell wall formation. Macerations and phloroglucinolHCl staining were employed to investigate fibre cell elongation and fibre cell wall lignification, respectively. Key Results The observations indicated that the primary wall is formed by the deposition of two distinct layers during the elongation of the internode and that secondary wall synthesis may begin before the complete cessation of internode and fibre elongation. Elongation was followed by a maturation phase characterized by the deposition of multiple secondary wall layers, which varied in number according to the cell type, location in the culm tissue and stage of shoot development. Lignification of fibre cell walls started at the period prior to the cessation of internode elongation. Conclusions The structure of the primary cell wall was comprised of two layers. The fibre secondary cell wall began to be laid down while the cells were still undergoing some elongation, suggesting that it may act to cause the slow-down and eventual cessation of cell elongation. PMID:15665037

  20. 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

  1. Mineral fibre persistence and carcinogenicity.

    PubMed

    McDonald, J C

    1998-10-01

    Epidemiological research during the past 40 years has demonstrated with increasing clarity that amphibole asbestos fibres--crocidolite, amosite and tremolite--are more carcinogenic than chrysotile. A smaller number of well-controlled studies using lung burden analyses, while adding to the specificity of this conclusion, have shown that amphibole fibres also differ from chrysotile in being far more durable and biopersistent in lung tissue. Analyses of mesothelioma and lung cancer in a large cohort of Canadian chrysotile miners and millers have recently shown that the low-level presence of fibrous tremolite in these mines, rather than the chrysotile, may well be responsible. The high risk of lung cancer, but not of mesothelioma, in the chrysotile textile industry remains anomalous and cannot be explained in this way. These various findings are directly relevant to the choice of the experimental methods which should be used for screening man-made fibres for industrial use. Although it is clear that biopersistence is a major determinant of cancer risk in animals, and perhaps also in man, other factors affecting the biological activity of mineral fibres may also be important. PMID:9810152

  2. 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)

  3. Light-scattering from a tenuous cylindrical matrix and the reflectance of the retinal nerve fiber layer

    NASA Astrophysics Data System (ADS)

    Zhou, Qienyuan; Knighton, Robert W.

    1994-06-01

    Evaluation of the retinal nerve fiber layer (RNFL) is important in the diagnosis of glaucoma and other optic nerve diseases. To aid understanding of the mechanism of RNFL reflectance, anatomical data were obtained from electron micrographs of cross- sections of amphibian RNFL and possible and possible scattering structures (axonal membranes, microtubules, and neurofilaments) were modeled as arrays of parallel thin fibers. Microtubules and neurofilaments are already thin fibers, and axonal membranes were decomposed into arrays of adjacent parallel fibers. Internal fields were assigned to each fiber by means of Born approximation or according to rules that depended on membrane orientation. Far field scattering was then calculated by field summation. Calculated scattering was much larger from axonal membranes than from microtubules or neurofilaments. Calculated spectra from 400- 700 nm showed increased scattering at shorter wavelengths for both axonal membranes and microtubules. Calculated backscattering from axonal membranes was approximately equal for incident light polarized parallel (TM mode) and perpendicular (TE mode) to the cylinder axis, but from microtubules TE mode scattering was less than TM mode.

  4. 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, Maurcio 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

  5. 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

  6. Surface electrical properties of stainless steel fibres: An AFM-based study

    NASA Astrophysics Data System (ADS)

    Yin, Jun; D'Haese, Ccile; Nysten, Bernard

    2015-03-01

    Atomic force microscopy (AFM) electrical modes were used to study the surface electrical properties of stainless steel fibres. The surface electrical conductivity was studied by current sensing AFM and I-V spectroscopy. Kelvin probe force microscopy was used to measure the surface contact potential. The oxide film, known as passivation layer, covering the fibre surface gives rise to the observation of an apparently semiconducting behaviour. The passivation layer generally exhibits a p-type semiconducting behaviour, which is attributed to the predominant formation of chromium oxide on the surface of the stainless steel fibres. At the nanoscale, different behaviours are observed from points to points, which may be attributed to local variations of the chemical composition and/or thickness of the passivation layer. I-V curves are well fitted with an electron tunnelling model, indicating that electron tunnelling may be the predominant mechanism for electron transport.

  7. Optical Coherence Tomography, Scanning Laser Polarimetry and Confocal Scanning Laser Ophthalmoscopy in Retinal Nerve Fiber Layer Measurements of Glaucoma Patients

    PubMed Central

    Fanihagh, Farsad; Kremmer, Stephan; Anastassiou, Gerasimos; Schallenberg, Maurice

    2015-01-01

    Purpose: To determine the correlations and strength of association between different imaging systems in analyzing the retinal nerve fiber layer (RNFL) of glaucoma patients: optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO). Materials and Methodology: 114 eyes of patients with moderate open angle glaucoma underwent spectral domain OCT (Topcon SD-OCT 2000 and Zeiss Cirrus HD-OCT), SLP (GDx VCC and GDx Pro) and CSLO (Heidelberg Retina Tomograph, HRT 3). Correlation coefficients were calculated between the structural parameters yielded by these examinations. The quantitative relationship between the measured RNFL thickness globally and for the four regions (superior, inferior, nasal, temporal) were evaluated with different regression models for all used imaging systems. Results: The strongest correlation of RNFL measurements was found between devices using the same technology like GDx VCC and GDx Pro as well as Topcon OCT and Cirrus OCT. In glaucoma patients, the strongest associations (R) were found between RNFL measurements of the two optical coherence tomography devices Topcon OCT and Cirrus OCT (R = 0.513) and between GDx VCC and GDx Pro (R = 0.451). The results of the OCTs and GDX Pro also had a strong quantitative relationship (Topcon OCT R = 0.339 and Cirrus OCT R = 0.347). GDx VCC and the OCTs showed a mild to moderate association (Topcon OCT R = 0.207 and Cirrus OCT R = 0.258). The confocal scanning laser ophthalmoscopy (HRT 3) had the lowest association to all other devices (Topcon OCT R = 0.254, Cirrus OCT R = 0.158, GDx Pro R = 0.086 and GDx VCC R = 0.1). Conclusion: The measurements of the RNFL in glaucoma patients reveal a high correlation of OCT and GDx devices because OCTs can measure all major retinal layers and SLP can detect nerve fibers allowing a comparison between the results of this devices. However, CSLO by means of HRT topography can only measure height values of the retinal surface but it cannot distinguish between different retinal layers. This may explain the rather poor correlations and associations between CSLO measurements and those of all other imaging devices which makes it difficult to compare HRT 3 nerve fiber data. These correlations are important in clinical routine especially when different techniques are used in the follow-up of glaucoma patients. PMID:25926903

  8. Acoustic longitudinal mode coupling in w-shaped Al/Ge Co-doped fibre

    NASA Astrophysics Data System (ADS)

    Li, Hong-Liang; Zhang, Wei; Huang, Yi-Dong; Peng, Jiang-De

    2011-10-01

    This paper proposes a novel fibre structure aiming at distributed temperature and strain sensing. Utilizing Al2O3 and GeO2 as dopants to form a w-shaped acoustic waveguide, it realizes modal coupling between longitudinal acoustic modes of its inner and outer core layers, leading to a dual-peak or multi-peak Brillouin gain spectrum. The relationship between the acoustic mode coupling properties and the fibre materials, doping concentrations and structural parameters are investigated, showing that the positions of mode coupling points in acoustic dispersion curves and the coupling intensities can be designed flexibly. A specific fibre design for the discriminative sensing of temperature and strain under a pump wavelength of 1.55 ?m is given. The responses of its Brillouin gain properties on temperature and strain are analysed theoretically, demonstrating its potential for distributed fibre Brillouin sensing.

  9. 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.

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

    PubMed

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

    2013-02-25

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

  11. 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.

  12. 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 (0.150.07). 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

  13. Nanostructured optical fibre sensors for breathing airflow monitoring

    NASA Astrophysics Data System (ADS)

    Kang, Y.; Ruan, H.; Wang, Y.; Arregui, F. J.; Matias, I. R.; Claus, R. O.

    2006-05-01

    A nanostructured optical fibre-based thin film sensor was designed for non-invasive, fast and reliable monitoring of respiratory airflow. Molecular-level self-assembly processing method was used to form multi-layered inorganic nanocluster and polymer thin films on the distal ends of optical fibres to form such sensors. In order to optimize the sensing performance, an analytical model based on the condensation of exhaled water vapour on the coating surface was established for the breathing analysis. By varying thin film chemistry the physically small sensors offer high sensitivity to breathing air in terms of variations in the reflected optical power. Moreover, the sensor performances in comparison with a medical nasal thermistor suggest such a thin film sensor is an excellent device for advanced breathing airflow monitoring.

  14. 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)

  15. Supergravity on Principal Fibre Bundle

    NASA Astrophysics Data System (ADS)

    Kakazu, K.; Matsumoto, S.

    1987-10-01

    Introducing Weil polynomials and ``generalized commutators'', we formulate on-shell N=1 supergravity on a principal fibre bundle; this formalism is quite similar to the group manifold one. The ``cochains'' in group manifold formalism are constructed in terms of Weil polynomials and ``generalized commutators''. It is shown that the approach of MacDowell and Mansouri has a close relationship to the group manifold formalism in OSp(1, 4) supergravity.

  16. 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

  17. Electrospun cerium nitrate/polymer composite fibres: synthesis, characterization and fibre-division model

    NASA Astrophysics Data System (ADS)

    Li, Meng-Meng; Long, Yun-Ze; Yin, Hong-Xing; Zhang, Zhi-Ming

    2011-04-01

    Cerium (III) nitrate/poly(vinylpyrrolidone) (Ce(NO3)3/PVP) composite fibres have been prepared by electrospinning. After calcining the composite fibres in air at 500 C, CeO2 nanowires were obtained. The characterizations of the as-spun composite fibres and resultant nanowires have been carried out by a scanning electron microscope (SEM), an infrared spectrometer, an x-ray diffractometer and a fluorescence spectrophotometer. Interestingly, some unusual ribbon-like or twin fibres were observed besides the common fibres with circular or elliptic cross sections. We developed a fibre-division model resulting from Coulomb repulsion and solvent vaporization to interpret the formation of the ribbons or twin fibres, which has been confirmed by the SEM studies. Our results also indicate that the formation of the ribbons or twin fibres is less dependent on operation voltage and work distance.

  18. 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.

  19. 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.

  20. Behaviour of Disc Oedema During and After Amiodarone Optic Neuropathy: Case Report

    PubMed Central

    Martnez-Gamero, Bertha O.; Mohamed-Noriega, Jibran; Cavazos-Adame, Med. Humberto; Mohamed-Hamsho, Med. Jess

    2014-01-01

    A 73-year-old woman with atrial fibrillation treated with Amiodarone presented with Optic Disc oedema in right eye (OD). Using Optical Coherence Tomography (OCT) we describe the impact of this neuropathy on Retinal Nerve Fibre Layer (RNFL). At diagnosis RNFL average was of 188 ?m OD and 77 ?m in the left eye (OS), six months after discontinuation of the drug decreased to 40 ?m in OD and 76 ?m in OS. The RNFL average of OD presented a transient increase during the acute oedema that returned to normal levels during the first month after discontinuation of the drug and fell dramatically to 44 ?m at the second month and 40 ?m at the sixth month. We show there is axonal loss after amiodarone-associated optic neuropathy measured with OCT. The OCT may be used in these patients to document changes in RNFL in the follow-up. PMID:24959500

  1. Optical coherence tomography findings in Huntington's disease: a potential biomarker of disease progression.

    PubMed

    Kersten, Hannah M; Danesh-Meyer, Helen V; Kilfoyle, Dean H; Roxburgh, Richard H

    2015-11-01

    Previous reports of ocular abnormalities in Huntington's disease (HD) have detailed eye movement disorders. The objective of this case-control study was to investigate optic nerve and macular morphology in HD using optical coherence tomography (OCT). A total of 26 HD patients and 29 controls underwent a thorough ophthalmic examination including spectral domain OCT scans of the macula and peripapillary retinal nerve fibre layer (RNFL). Genetic testing results, disease duration, HD disease burden scores and Unified HD Rating Scale motor scores were acquired for HD patients. Temporal RNFL thickness was significantly reduced in the HD group (62.3 vs. 69.8 ?m, p = 0.005), and there was a significant negative correlation between temporal RNFL thickness and disease duration (R (2) = -0.51, p = 0.04). Average peripapillary RNFL thickness was not significantly different between the HD and control groups. There was a significant negative correlation between macular volume and disease duration (R (2) = -0.71, p = 0.002), and motor scores (R (2) = -0.56, p = 0.01). Colour vision was significantly poorer in the HD group. Temporal RNFL is preferentially thinned in HD patients, possibly implicating mitochondrial dysfunction as the temporal RNFL is reduced in the patients with some mitochondrial disorders, including Leber's hereditary optic neuropathy. The correlation between the decrease in macular volume and temporal RNFL, and increasing disease severity suggests that OCT may be a useful biomarker for disease progression in HD. Larger, longitudinal studies are required. PMID:26233693

  2. 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

  3. 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

  4. 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

  5. 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

  6. Structure development in electrospun fibres of gelatin

    NASA Astrophysics Data System (ADS)

    Elliott, Delyth E.; Davis, Fred J.; Mitchell, Geoffrey R.; Olley, Robert H.

    2009-08-01

    Gelatin fibres have been successfully electrospun from water by heating a gelatin solution above the sol-gel transition temperature, and allowing cooling in a controlled environment as the fibres are produced. The development of structure with in these fibres is monitored using wide angle x-ray scattering, in this way the presence of the triple helix structure, which provides the physical cross-linkages in the gel could be probed. There is clear evidence that these structures are obtained in gelatin electrospun from aqueous solutions. In contrast fibres electrospun from a solution of gelatin in glacial acetic acid, showed no evidence of the triple helix structure.

  7. Towards the Knittability of Graphene Oxide Fibres

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  8. A 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.

  9. 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.

  10. 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.

  11. 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%.

  12. 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

  13. 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 ?m and 3 ?m, respectively. Results: Classic glaucomatous ONH and RNFL structural changes were seen in SDOCT images. An SDOCT reference plane 139 ?m 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

  14. Characterisation of birefringence in optical fibres

    NASA Astrophysics Data System (ADS)

    Schuh, R. E.

    1998-12-01

    Polarisation mode dispersion has now become one of the main limiting factors in land based systems, and continues to be an issue in the design of submarine systems. This thesis describes a theoretical and experimental investigation of linear and twist induced circular birefringence and polarisation mode dispersion in single mode optical transmission fibre. The main original contributions described in this thesis are: (1) An analytical solution has been obtained for the differential group delay (DGD) in the presence of elastic twist. This solution is in excellent agreement with the extensive set of DGD measurements reported here, and it allows the prediction of the optimum twist rate needed to minimise the DGD in an optical fibre. (2) The DGD of different types of fibres: standard-step index fibres (S- SMFs), dispersion shifted fibres (DSFs), spun DSFs, erbium doped fibres (EDFs) and distributed EDFs (DEDFs) have been measured as a function of twist. Spun fibre showed the lowest initial DGD while the first reported measurements on DEDFs showed unacceptably large DGD values for high bit-rate soliton transmission. (3) From simulation and measurement, an empirical equation has been obtained for commercial spun fibre manufactured with sinusoidal spin, which allows the determination of the minimum spin (RMS value) required to obtain a fibre with low DGD. (4) A conventional OTDR has been modified to a polarimetric OTDR to analyse the backscattered SOP, and from this the birefringence characteristics are obtained along the fibre. A matrix-vector description has been developed to analyse POTDR data from fibres with twist. The developed theory has been verified by detailed experimental results, and it large error in the estimated is shown that if twist is ignored when present, it can lead to a values of birefringence and DGD obtained from such measurements.

  15. 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.

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

    SciTech Connect

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

    2012-09-30

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

  17. Structural behaviour of fibre metal laminates subjected to a low velocity impact

    NASA Astrophysics Data System (ADS)

    Fan, JiYing; Guan, ZhongWei; Cantwell, W. J.

    2011-06-01

    Structural impact tests were first presented to cover typical fibre metal laminates (FMLs) subjected a low velocity projectile impact, which produced the corresponding load-displacement traces and deformation/failure modes for the validation of numerical models. Finite element (FE) models were then developed to simulate the impact behaviour of FMLs tested. The aluminium (alloy grade 2024-0) layer was modelled as an isotropic elasto-plastic material up to the on-set of post failure stage, followed by shear failure and tensile failure to simulate its failure mechanisms. The glass fibre laminate (woven glass-fibre reinforced composite) layer was modelled as an orthotropic material up to its on-set of damage, followed by damage initiation and evolution using the Hashin criterion. The damage initiation was controlled by failure tensile and compressive stresses within the lamina plane which were primarily determined by tests. The damage evolution was controlled by tensile/compressive fracture energies combined with both fibre and matrix. The FE models developed for the 2/1, 3/2 and 4/3 FMLs plates made with 4-ply and 8-ply glass fibre laminate cores were validated against the corresponding experimental results. Good correlation was obtained in terms of load-displacement traces, deformation and failure modes. The validated models were ready to be used to undertake parametric studies to cover FMLs plates made with various stack sequences and composite cores.

  18. 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

  19. DESIGN NOTE: Birefringence monitoring of a Hi-Bi fibre under chemical etching through a fibre loop mirror

    NASA Astrophysics Data System (ADS)

    Frazo, O.; Guerreiro, A.; Santos, J. L.; Baptista, J. M.

    2007-12-01

    Birefringence monitoring of a Hi-Bi fibre under chemical etching is conducted. The Hi-Bi fibre (a bow-tie type) was inserted in a fibre loop mirror and the optical spectral response was measured while chemical etching of the Hi-Bi fibre was taking place. The birefringence of the bow-tie fibre has decreased due to the etching and the wavelength spacing of the fringe minima of the fibre loop mirror has increased.

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

    PubMed

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernndez-Blzquez, 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

  1. 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

  2. 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.

  3. 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

  4. New design of hip prosthesis using carbon fibre reinforced composite.

    PubMed

    Shirandami, R; Esat, I I

    1990-01-01

    We present a new design for a hip prosthesis using polyethylene-hydroxyapatite, a composite material with layered stiffness and good bone compatibility. In order to overcome the low stiffness of the matrix, carbon fibre reinforcement is suggested. This new collarless prosthesis was designed to give maximum stiffness at the core and lower stiffness at the bone-implant interface. For this design a 2D finite element analysis was undertaken; its results were compared with those for a titanium alloy prosthesis. The effect of the variation in the collar stiffness was also analysed. PMID:2296163

  5. 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)

  6. 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 Cancn, 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 secondoriginally 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 fibresphotonic 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, Gonzlez-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 w

  7. 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)

  8. 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

  9. Fibre-Matrix Interaction in Soft Tissue

    NASA Astrophysics Data System (ADS)

    Guo, Zaoyang

    2010-05-01

    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.

  10. Fibre-Matrix Interaction in Soft Tissue

    SciTech Connect

    Guo, Zaoyang

    2010-05-21

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

  11. Fibre-optically lit laryngoscope.

    PubMed

    Arthurs, G J

    1999-09-01

    The light from a battery-powered laryngoscope with a fibreoptic blade is limited by the 3-V battery and deteriorates with use, as the optic fibres break. A laryngoscope handle is described in which the bulb is replaced by a fibreoptic cable connecting to a mains, halogen light source. This laryngoscope gives 6000 Cd.m(-2) light at the centre of the field compared with 800 Cd.m(-2) for the battery. The field of illumination is also improved from 1600 Cd.m(-2) 20 mm from the centre compared with 120 Cd.m(-2) for the battery handle. The fibre optic cable is attached at the side of the handle and does not interfere with intubation. The mains-powered light source has the advantages of being reliable with the ability to switch immediately to a second bulb; low running costs; improved light for intubation and it makes it possible to use a dental mirror for indirect laryngoscopy in difficult intubations. PMID:10460559

  12. Automated segmentation by pixel classification of retinal layers in ophthalmic OCT images

    PubMed Central

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

    2011-01-01

    Current OCT devices provide three-dimensional (3D) in-vivo images of the human retina. The resulting very large data sets are difficult to manually assess. Automated segmentation is required to automatically process the data and produce images that are clinically useful and easy to interpret. In this paper, we present a method to segment the retinal layers in these images. Instead of using complex heuristics to define each layer, simple features are defined and machine learning classifiers are trained based on manually labeled examples. When applied to new data, these classifiers produce labels for every pixel. After regularization of the 3D labeled volume to produce a surface, this results in consistent, three-dimensionally segmented layers that match known retinal morphology. Six labels were defined, corresponding to the following layers: Vitreous, retinal nerve fiber layer (RNFL), ganglion cell layer & inner plexiform layer, inner nuclear layer & outer plexiform layer, photoreceptors & retinal pigment epithelium and choroid. For both normal and glaucomatous eyes that were imaged with a Spectralis (Heidelberg Engineering) OCT system, the five resulting interfaces were compared between automatic and manual segmentation. RMS errors for the top and bottom of the retina were between 4 and 6 ?m, while the errors for intra-retinal interfaces were between 6 and 15 ?m. The resulting total retinal thickness maps corresponded with known retinal morphology. RNFL thickness maps were compared to GDx (Carl Zeiss Meditec) thickness maps. Both maps were mostly consistent but local defects were better visualized in OCT-derived thickness maps. PMID:21698034

  13. Benign Multiple Sclerosis is Associated with Reduced Thinning of the Retinal Nerve Fiber and Ganglion Cell Layers in Non-Optic-Neuritis Eyes

    PubMed Central

    Fredrikson, Mats; Link, Hans

    2015-01-01

    Background and Purpose It is exceedingly difficult to differentiate benign multiple sclerosis (BMS) from relapsing-remitting multiple sclerosis (RRMS) based on clinical characteristics, neuroimaging, and cerebrospinal fluid tests. Optical coherence tomography (OCT) allows quantification of retinal structures, such as the retinal nerve fiber layer (RNFL) thickness, at the optic disc and the ganglion cell layer (GCL) at the macula, on a micrometer scale. It can also be used to trace minor alterations and the progression of neurodegeneration, help predict BMS, and influence the choice of therapy. To utilize OCT to detect the extent of changes of the optic disk and macular microstructure in patients with BMS and RRMS compared to healthy controls (HCs), with special focus on changes related to the presence/absence of optic neuritis (ON). Methods Spectral-domain OCT was applied to examine eyes from 36 patients with multiple sclerosis (MS), comprising 11 with BMS and 25 with RRMS, and 34 HCs. Results The RNFL and GCL were significantly thinner in eyes previously affected by ON, irrespective of the type of MS (i.e., BMS or RRMS), than in HCs. Significant thinning of the GCL was also observed in non-ON RRMS (and not non-ON BMS) compared to HCs. Correspondingly, a significant association between disease duration and thinning rates of the RNFL and GCL was observed only in non-ON RRMS (-0.540.24 and -0.430.21 m/year, meanSE; p<0.05 for both), and not in non-ON BMS (-0.110.27 and -0.240.24 m/year). Conclusions The RNFL and GCL were thinner in both ON- and non-ON MS, but the change was more pronounced in ON MS, irrespective of the MS subtype studied herein. GCL thinning and the thinning rate of both the GCL and RNFL were less pronounced in non-ON BMS than in non-ON RRMS. These findings may help to predict the course of BMS. PMID:26022460

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    Changes in retinal nerve fiber layer thickness and birefringence may both precede clinically detectable glaucomatous vision loss. Early detection of retinal nerve fiber layer changes may enable treatment to prevent permanent loss of vision. Polarization sensitive optical coherence tomography (PS-OCT) can provide objective information on retinal nerve fiber layer thickness and birefringence. PS-OCT scans around the optic nerve head (ONH) of two healthy young volunteers were made using 10 concentric circles of increasing radius. Both the mean retinal nerve fiber layer thickness and mean retinal nerve fiber birefringence for each of 48 sectors on a circle were determined with data analysis. Birefringence of healthy RNFL is constant as a function of scan radius but varies as a function of position around the ONH, with higher values occurring superior and inferior to the ONH. Measured double pass phase retardation per unit depth values around the ONH range between 0.10 and 0.35 /?m, equivalent to birefringence values of 1.210-4 and 4.110-4 respectively, measured at a wavelength of 840 nm. Consequently, conversion of phase retardation measurements (as obtained with scanning laser polarimetry) to RNFL thickness measurements, assuming a constant birefringence value, will yield thickness values that are incorrect.

  15. 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.

  16. Process for the production of carbon fibres from petroleum pitch

    SciTech Connect

    Fug, G.

    1984-02-14

    A method of producing carbon or graphite fibres from a pitch obtained from a steam cracking residue of a petroleum fraction which pitch has a b resin content of from 2 to 40% by weight, comprises spinning the pitch into fibres at a temperature higher than the softening point, the fibres being treated to render them infusible and then subjecting the fibres to carbonization by heating, followed by graphitization if desired, characterized in that the treatment to infusibilize the fibres is controlled such that the resin content of the fibres does not exceed 30% by weight. The invention includes carbon and graphite fibres produced by the process.

  17. Delamination, fibre bridging and toughness of ceramic matrix composites

    SciTech Connect

    Kaute, D.A.W.; Shercliff, H.R.; Ashby, M.F. . Engineering Dept.)

    1993-07-01

    Delamination cracks in long-fibre reinforced ceramic matrix composites are found to be bridged by fibres which span the crack wake at a shallow angle. The in situ observation of bridging fibres reveals that these are subject to considerable tensile forces, giving rise to a substantial crack closure force. The overall crack closure force is determined by the number of bridging fibres, steadily reduced by fibre failure caused by high bending moments at the root of each fibre. This leads to a model for crack closing forces combining simple mechanics and Weibull statistics. The model relates these forces to the properties of fibres, matrix and their interface.

  18. 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.

  19. Influence of slip on the PlateauRayleigh instability on a fibre

    PubMed Central

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

    2015-01-01

    The PlateauRayleigh 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 solidliquid interface. Here we revisit the PlateauRayleigh instability of a liquid coating a fibre by varying the hydrodynamic boundary condition at the fibreliquid interface, from no slip to slip. Although the wavelength is not sensitive to the solidliquid 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

  20. Toward the implementation of flexible sensing sheet with fibre Bragg grating sensing elements

    NASA Astrophysics Data System (ADS)

    Yan, Chunxiao; Ferraris, Eleonora; Reynaerts, Dominiek

    2012-04-01

    Optical sensing sheets, based on Fibre Bragg Grating (FBG) sensing elements embedded in exible polydimethyl- siloxane (PDMS), are produced and tested. The device shows promise in pressure mapping and tactile applications, in fields such as robotics and rehabilitation. FBGs inscribed in highly-birefringent photonic crystal fibres, reflecting two Bragg peaks, are used, and the potential to discriminate pressure and temperature is explored. The prototypes were produced by moulding technology and PDMS was cured at room temperature. One sample with FBGs embedded in the middle layer of a 2 mm thick PDMS sheet exhibited a linear pressure sensitivity of about 2:6 pm/kPa over the range of 0 - 250 kPa. Another sample was proposed and tested for temperature insensitive measurements, by realising local stress concentration at FBG sections of the embedded fibre.

  1. Synthetic fibre granuloma of the conjunctiva.

    PubMed

    Mak, S T; Lui, Y H; Li, Kenneth K W

    2015-02-01

    Synthetic fibre granuloma of the conjunctiva, sometimes known as 'teddy bear granuloma', results from granulomatous foreign body reaction of the conjunctiva to synthetic fibres. It is often an incidental finding, most commonly found in children, is unilateral, and occurs in the lower eyelid. We present here, what we believe is the first reported case of synthetic fibre conjunctival granuloma in Hong Kong, together with a review of the condition. An awareness of this clinical entity allows early and accurate diagnosis and early treatment. PMID:25686707

  2. 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

  3. 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.

  4. Automated 3D segmentation of intraretinal layers from optic nerve head optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Antony, Bhavna J.; Abrmoff, Michael D.; Lee, Kyungmoo; Sonkova, Pavlina; Gupta, Priya; Kwon, Young; Niemeijer, Meindert; Hu, Zhihong; Garvin, Mona K.

    2010-03-01

    Optical coherence tomography (OCT), being a noninvasive imaging modality, has begun to find vast use in the diagnosis and management of ocular diseases such as glaucoma, where the retinal nerve fiber layer (RNFL) has been known to thin. Furthermore, the recent availability of the considerably larger volumetric data with spectral-domain OCT has increased the need for new processing techniques. In this paper, we present an automated 3-D graph-theoretic approach for the segmentation of 7 surfaces (6 layers) of the retina from 3-D spectral-domain OCT images centered on the optic nerve head (ONH). The multiple surfaces are detected simultaneously through the computation of a minimum-cost closed set in a vertex-weighted graph constructed using edge/regional information, and subject to a priori determined varying surface interaction and smoothness constraints. The method also addresses the challenges posed by presence of the large blood vessels and the optic disc. The algorithm was compared to the average manual tracings of two observers on a total of 15 volumetric scans, and the border positioning error was found to be 7.25 +/- 1.08 ?m and 8.94 +/- 3.76 ?m for the normal and glaucomatous eyes, respectively. The RNFL thickness was also computed for 26 normal and 70 glaucomatous scans where the glaucomatous eyes showed a significant thinning (p < 0.01, mean thickness 73.7 +/- 32.7 ?m in normal eyes versus 60.4 +/- 25.2 ?m in glaucomatous eyes).

  5. 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

  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. The role of 18-methyleicosanoic acid in the structure and formation of mammalian hair fibres.

    PubMed

    Jones, L N; Rivett, D E

    1997-12-01

    Although branched chain fatty acids perform many functions in biological systems, the importance of the anteiso 18 methyleicosanoic acid (MEA) has only recently been recognized. In this first review on MEA its role and distribution is explored. MEA has been found in minor amounts in the fatty acid components of a wide range of biological materials, but the current interest results from it being the major covalently bound fatty acid in mammalian hair fibres, a finding which is unusual because protein-bound fatty acids are typically straight-chain, even-numbered acids (C14-C18). MEA is released by surface restricted reagents indicating that it is located exclusively in or on the surface of the cuticle cells, a conclusion that has been verified by analysis of isolated cuticle cells, X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectroscopy (SIMS) studies support these results in that they show the surface of the cuticle to be predominantly hydrocarbon. When either neutral hydroxylamine or acidic chlorine solutions are applied to hair and wool fibres fatty acids are liberated, indicating the presence of thioester bonds. Calculations, based on fatty acid and amino acid analysis, indicate that approximately one residue in 10 of the cuticular membrane protein is a fatty acid thioester of cysteine. Removal of this covalently linked fatty acid renders the fibre hydrophilic, thus offering a chemical explanation for many technological and cosmetic treatments of mammalian fibres. Examination of the fibre surface and that of isolated cuticle cells by transmission electron microscopy (TEM) confirms the presence of a thin non-staining continuous layer surrounding the cuticle cells. Alkaline treatments which remove the bound fatty acids were found to disrupt this layer. TEM examination of developing hair fibres has indicated that the fatty acid layer on the upper surface and scale edges of the cuticle cell differs from that of the underside of the cell. Similar structural studies of hair from patients with maple syrup urine disease (MSUD) support the findings that thioester-bound MEA is limited to the upper surface of fibre cuticle cells. The current model proposed for the boundary layer consists of crosslinked protein with surface thioester-linked fatty acids, forming a continuous hydrophobic layer on the upper surface and scale edges of the cells. PMID:9519472

  8. Fibre reinforced ceramic matrix composite fabrication by electrophoretic infiltration

    SciTech Connect

    Kooner, S.; Campaniello, J.J.; Pickering, S.; Bullock, E.

    1995-12-01

    Electrophoretic infiltration is a novel technique for the fabrication of fibre reinforced composites. The fibres are arranged as one of the electrodes such that deposition of the colloidal ceramic occurs in the fibre preform. This method has been investigated for the composite system of carbon fibre reinforced Si{sub 3}N{sub 4} and has produced green composite microstructures with good infiltration uniformity and fibre distribution and few macro defects.

  9. 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

  10. 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

  11. Biological durability and oxidative potential of a stonewool mineral fibre compared to crocidolite asbestos fibres.

    PubMed

    Hippeli, S; Dornisch, K; Kaiser, S; Drger, U; Elstner, E F

    1997-01-01

    Experiments are described concerning the differences in redox properties and biodurability of natural asbestos fibres and an experimental stonewool fibre incubated in Gamble solution and reconstructed surfactant fluid. Crocidolite exhibits a significantly higher oxidative potential compared to the tested stonewool fibres. The oxidative activity of both types of fibres is not constant during incubation over several weeks, but rather shows a sinoidal curve including reactivities much higher than those at the beginning of the incubation. A continuous loss of mass is concluded not to be definitively connected with a continuous loss of toxicity. PMID:9248633

  12. 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.

  13. Optical Fibre Pressure Sensors in Medical Applications.

    PubMed

    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

  14. 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

  15. 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

  16. 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 (50.98.1 m, p<0.05) vs. baseline (46.42.4 m), then 7% thinning at 2-weeks (43.07.2 m, p>0.05) and 3-weeks (43.54.4 m, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.94.1 m) vs. baseline (49.25.3 m), but progression to 22% thinning at 2-weeks (38.03.7 m, p<0.01) and 3-weeks (40.06.6 m, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 7780% loss of dynamic range and a severe transport deficit. Optic nerves showed 7595% 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

  17. 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)

  18. Fibre-optic sensors in health care.

    PubMed

    Mignani, A G; Baldini, F

    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. PMID:9172270

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Fourier-Domain Optical Coherence Tomography and Adaptive Optics Reveal Nerve Fiber Layer Loss and Photoreceptor Changes in a Patient With Optic Nerve Drusen

    PubMed Central

    Choi, Stacey S.; Zawadzki, Robert J.; Greiner, Mark A.; Werner, John S.; Keltner, John L.

    2008-01-01

    Background New technology allows more precise definition of structural alterations of all retinal layers although it has not been used previously in cases of optic disc drusen. Methods Using Stratus and Fourier domain (FD) optical coherence tomography (OCT) and adaptive optics (AO) through a flood-illuminated fundus camera, we studied the retinas of a patient with long-standing optic disc drusen and acute visual loss at high altitude attributed to ischemic optic neuropathy. Results Stratus OCT and FD-OCT confirmed severe thinning of the retinal nerve fiber layer (RNFL). FD-OCT revealed disturbances in the photoreceptor layer heretofore not described in optic disc drusen patients. AO confirmed the FD-OCT findings in the photoreceptor layer and also showed reduced cone density at retinal locations associated with reduced visual sensitivity. Conclusions Based on this study, changes occur not only in the RNFL but also in the photoreceptor layer in optic nerve drusen complicated by ischemic optic neuropathy. This is the first reported application of FD-OCT and the AO to this condition. Such new imaging technology may in the future allow monitoring of disease progression more precisely and accurately. PMID:18562844

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

    NASA Astrophysics Data System (ADS)

    Olszwka-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).

  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. 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

  9. 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

  10. Reduction in retinal nerve fiber layer thickness in migraine patients.

    PubMed

    Gipponi, Stefano; Scaroni, Niccol; Venturelli, Elisabetta; Forbice, Eliana; Rao, Renata; Liberini, Paolo; Padovani, Alessandro; Semeraro, Francesco

    2013-06-01

    Migraine is a common disorder and its pathogenesis remains still unclear. Several hypotheses about the mechanisms involved in the pathogenesis of migraine have been proposed, but the issue is still far from being fully clarified. Neurovascular system remains one of the most important mechanisms involved in the pathogenesis of migraine and it could be possible that hypoperfusion might involve other areas besides brain, including the retina. This is, for example, of particular interest in a form of migraine, the retinal migraine, which has been associated with hypoperfusion and vasoconstriction of the retinal vasculature. Although vasoconstriction of cerebral and retinal blood vessels is a transient phenomenon, the chronic nature of the migraine might cause permanent structural abnormalities of the brain and also of the retina. On this basis, a few studies have evaluated whether retina is involved in migraine patients: Tan et al. have not found differences in retinal nerve fiber layer (RNFL) thickness between migraine patients and healthy subjects, while Martinez et al. have shown that RNFL in the temporal retinic quadrant of migraineurs is thinner than in normal people. The aim of our study was to analyze if there are differences in retinal nerve fiber layer thickness between migraine patients and normal subjects by studying 24 consecutive migraine patients who presented at the Headache Center of our Neurological Department. Migraine diagnosis has been made according to the International Classification of Headache disorder (ICHD-II). Patients have been recruited according to strict inclusion criteria; then patients have undergone a complete ophthalmological examination at the Ophthalmological Department. All patients and controls who met the ophthalmological criteria have been examined with ocular coherence tomography spectral domain (OCT-SD) after pupillary dilation. OCT-SD is an optical system designed to acquire the retinal layer images simultaneously with fundus confocal images. The statistical analysis has been performed using the Statistical Package for Social Sciences program. The Student's t test has been used to compare numeric variables between migraine and control groups. p value >0.05 has been considered not significant. We have analyzed 40 female subjects, 24 included in the study group and 16 included in the control group. Two migraine patients have been excluded. No differences have been found in the visual acuity between the two groups. Comparing RNFLs of a single eye per person in the two groups, we have found that migraine patients showed significant reduction in the superior quadrants (p < 0.005). Also evaluating both eyes per person there was a significant difference in the same quadrant between the two groups (p < 0.05). The result of this present study show that migraine patients have RNFL thickness reduction in the superior retinal quadrant compared with normal subjects. It is important to underline that RNFL thickness measurement could be a new interesting technique to evaluate the evolution of migraine and perhaps to study if prophylactic treatment could reduce retinal abnormalities seen in migraine patients. OCT-SD is a simple exam that could be repeated and then used for evaluation of headache progression during the time. Our study shows that RNFLs thickness does not depend on illness duration and frequency. PMID:22535509

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

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

  12. 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)

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Butylina, Svetlana; Martikka, Ossi; Krki, 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.

  15. 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

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

    PubMed

    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?RNFL defects in preperimetric glaucomatous eyes with normal cpRNFL. PMID:26883374

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

    PubMed Central

    Ishizuka, Hisao

    2012-01-01

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

  18. Mechanical properties of continuous carbon fibre reinforced silicon nitride: Influence of fibre coatings

    SciTech Connect

    Sabouret, E.; Veyret, J.B.; Bullock, E.

    1995-12-01

    The entrainment of long carbon fibres into a Si{sub 3}N{sub 4} ceramic matrix improves the fracture toughness and wear properties of the ceramic but introduces a chemical and physical instability resulting from interaction between the fibre and matrix phases. The mechanisms of toughening rely largely upon the formation of weak interphase bonding along the fibre-matrix interface and upon the residual thermal stresses arising from processing. From this, improved failure behaviour may be engineered by mechanical and chemical modification of the interface, achieved most effectively by the choice of reinforcement phase and by pre-coating of the fibres prior to fabrication of the composite. Flexural testing and microstructural T.E.M analysis were used to compare the effect of the various fibre and coating interlayers (SiC, C/SiC).

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

    SciTech Connect

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

    2003-08-31

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

  20. 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)

  1. 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

  2. Analytical modelling and numerical simulation of the nonlinear deformation of hybrid fibre metal laminates

    NASA Astrophysics Data System (ADS)

    Wu, Guocai; Yang, Jenn-Ming

    2005-04-01

    GLARE laminates are an advanced hybrid material system consisting of alternating layers of thin aluminium sheets and unidirectional or biaxial reinforced high strength glass fibre/epoxy composite layers. The unique combination of ductile aluminium layers with high strength composite layers results in a unique fibre-metal laminate (FML) having light weight, outstanding fatigue resistance, excellent impact resistance, flame resistance and corrosion properties. This paper investigates the nonlinear tensile response and fracture behaviour of GLARE 4 and GLARE 5 laminates under in-plane loading. Both an analytical constitutive model based on a modified classical lamination theory, which incorporates the elasto-plastic behaviour of the aluminium alloy, and a numerical simulation based on finite element modelling are used to predict the stress-strain response and deformation behaviour of GLARE laminates. Good agreement is obtained between the model predictions and experimental results. The validated model can be used to optimize the microstructure including the metal type and thickness, the fibre type, orientation and volume fraction and the properties of the FMLs.

  3. Voronoi cells, fractal dimensions and fibre composites.

    PubMed

    Summerscales, J.; Guild, F. J.; Pearce, N. R. L.; Russell, P. M.

    2001-02-01

    The use of fibre-reinforced polymer matrix composite materials is growing at a faster rate than the gross domestic product (GDP) in many countries. An improved understanding of their processing and mechanical behaviour would extend the potential applications of these materials. For unidirectional composites, it is predicted that localized absence of fibres is related to longitudinal compression failure. The use of woven reinforcements permits more effective manufacture than for unidirectional fibres. It has been demonstrated experimentally that compression strengths of woven composites are reduced when fibres are clustered. Summerscales predicted that clustering of fibres would increase the permeability of the reinforcement and hence expedite the processing of these materials. Commercial fabrics are available which employ this concept using flow-enhancing bound tows. The net effect of clustering fibres is to enhance processability whilst reducing the mechanical properties. The effects reported above were qualitative correlations. To improve the design tools for reinforcement fabrics we have sought to quantify the changes in the micro/meso-structure of woven reinforcement fabrics. Gross differences in the appearance of laminate sections are apparent for different weave styles. The use of automated image analysis is essential for the quantification of subtle changes in fabric architecture. This paper considers Voronoi tessellation and fractal dimensions for the quantification of the microstructures of woven fibre-reinforced composites. It reviews our studies in the last decade of the process-property-structure relationships for commercial and experimental fabric reinforcements in an attempt to resolve the processing vs. properties dilemma. A new flow-enhancement concept has been developed which has a reduced impact on laminate mechanical properties. PMID:11207917

  4. 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

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Thickness and birefringence of retinal nerve fiber layer of healthy and glaucomatous subjects measured with polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    Changes in retinal nerve fiber layer thickness and birefringence may both precede clinically detectable glaucomatous vision loss. Early detection of retinal nerve fiber layer changes may enable treatment to prevent permanent loss of vision. Polarization sensitive optical coherence tomography (PS-OCT) can provide objective information on retinal nerve fiber layer thickness and birefringence. PS-OCT scans around the optic nerve head (ONH) of two healthy young volunteers were made using 10 concentric circles of increasing radius. Both the mean retinal nerve fiber layer thickness and mean retinal nerve fiber birefringence for each of 48 sectors on a circle were determined with data analysis. Birefringence of healthy RNFL is constant as a function of scan radius but varies as a function of position around the ONH, with higher values occurring superior and inferior to the ONH. Measured double pass phase retardation per unit depth values around the ONH range between 0.10 and 0.35/?m, equivalent to birefringence values of 1.210-4 and 4.110-4 respectively, measured at a wavelength of 840 nm. Consequently, conversion of phase retardation measurements (as obtained with scanning laser polarimetry) to RNFL thickness measurements, assuming a constant birefringence value, will yield thickness values that are incorrect.

  7. 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

  8. UV curing of optical fibre coatings using excimer lamps

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Ying; Windall, Gaelle; Boyd, Ian W.

    2002-01-01

    In this paper, UV curing of optical fibre coatings using excimer lamp radiation has been demonstrated for the first time. These layers were prepared on silicon and quartz substrates by conventional spin coating and subsequently exposed to 172, 222 nm or 308 nm light from different excimer lamp sources. Ellipsometry, Fourier transform infrared (FTIR) spectroscopy and ultraviolet spectrophotometry have been used to characterise any modifications to the coatings and to generally monitor the evolution of the curing process. The absorption coefficient and photon penetration depth, as well as the intensity profiles in the coating, of each of the different wavelengths have been measured and calculated. The FTIR spectra revealed that the coatings were cured in less than 1 s under the 308 nm excimer lamp while the 222 nm excimer lamp was found to be extremely inefficient for the curing of the optical fibre coatings. After curing with the 172 nm excimer lamp, the surface of the coatings became cracked, irregular and milky in appearance. Such features are not observed when irradiating with 222 and 308 nm. The different UV curing effects of these three wavelengths will be discussed.

  9. 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.

  10. Nanoporous ultrahigh specific surface polyacrylonitrile fibres

    NASA Astrophysics Data System (ADS)

    Zhang, Lifeng; Hsieh, You-Lo

    2006-09-01

    The concept of phase separation was coupled with electrospinning to generate polyacrylonitrile (PAN) and poly(ethylene oxide) (PEO) bicomponent fibres that, upon removal of the phase-separated PEO domains, became nanoporous. Electrospinning of PAN (150 kDa) with 15-50% w/w PEO (10 kDa) at a 8% w/w total concentration in N,N-dimethylformamide produced fibres with decreasing averaged diameters from 390 to 130 nm. Evidence of phase separation between PAN and PEO in the bicomponent fibres was indicated by the characteristic PAN and PEO peaks by Fourier transform infrared (FTIR) spectroscopy and solid-state nuclear magnetic resonance (NMR) imaging, and confirmed by the co-existence of PAN cyclization and PEO melting by differential scanning calorimetry (DSC) and the presence of PEO crystalline diffraction by wide-angle x-ray scattering (WAXS). Removal of PEO by dissolution in water was confirmed by the matched mass loss to PEO fraction and the absence of PEO by FTIR and DSC. The water-treated bicomponent fibres appeared slightly larger in diameter and contained internal pores of nanometre scale. The nanoporous fibres generated from 50/50 PAN/PEO bicomponent precursor contained internal pores of a few nanometres to tens of nanometres in size and had 50% higher pore volume and 2.5-fold higher specific surface.

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. Highly strong and elastic graphene fibres prepared from universal graphene oxide precursors.

    PubMed

    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

  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. Nanostructured fibre tip for trapping of nanoparticles

    NASA Astrophysics Data System (ADS)

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

  16. Fibre optic sensors based on D-shaped elliptical core fibres

    NASA Astrophysics Data System (ADS)

    Chandani, Sameer M.

    Optical fibre-based sensors have gained much attention over the past three decades and are gaining acceptance in many industries such as the aerospace, automotive, chemical processing, biological sensing, and medical industries. The work presented here demonstrates the use of D-shaped fibres as intensity-based fibre optic sensors. The fibres are etched to gain access to their evanescent optical fields and are operated in their "leaky", regimes, i.e., the regime in which optical power leaks out of their cores. The optical power transmission through the etched D-fibre, which constitutes the sensor head, depends on the refractive index of the measurand placed on the sensor head. Thus by using materials whose refractive indices depend on the desired measurands, intensity-based sensors can be realised. A "non-destructive" process for determining the etched cladding thickness of the D-fibre is also developed. Once calibrated for a specific fibre or fibre batch, only one thermo-optic oil, three temperature measurements and a mathematical fitting routine are required to determine the etched cladding thickness with an accuracy better than 0.3 mum. Four types of sensor are demonstrated. A refractive index sensor with a high resolution region and a low resolution region, both of which can be shifted by changing the operating wavelength, is demonstrated with a maximum resolution on the order of 10-6 refractive index units. Naturally, this leads to the development of a temperature sensor with an adjustable dynamic range and resolution that uses thermo-optic oils. Proof of principle is demonstrated for an electric field sensor using chiral smectic A liquid crystals. A continuous liquid level sensor (that can also be implemented as a discrete level sensor) is also demonstrated using only one optical source, one optical detector and a single length of fibre.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. Fibre-based imaging: new challenges

    NASA Astrophysics Data System (ADS)

    Plschner, Martin; Straka, Branislav; Dholakia, Kishan; ?imr, Tom.

    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.

  2. On orderability of fibred knot groups

    NASA Astrophysics Data System (ADS)

    Perron, Bernard; Rolfsen, Dale

    2003-07-01

    It is known that knot groups are right-orderable, and that many of them are not bi-orderable. Here we show that certain fibred knots in S(3) (or in a homology sphere) do have bi-orderable fundamental groups. In particular, this holds for fibred knots, such as 4_1, for which the Alexander polynomial has all roots real and positive. This is an application of the construction of orderings of groups, which are moreover invariant with respect to a certain automorphism.

  3. 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

  4. [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.

  5. 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

  6. 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).

  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. 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.

  9. Synchronously pumped picosecond all-fibre Raman laser based on phosphorus-doped silica fibre.

    PubMed

    Kobtsev, Sergey; Kukarin, Sergey; Kokhanovskiy, Alexey

    2015-07-13

    Reported for the first time is picosecond-range pulse generation in an all-fibre Raman laser based on P?O?-doped silica fibre. Employment of phosphor-silicate fibre made possible single-cascade spectral transformation of pumping pulses at 1084 nm into 270-ps long Raman laser pulses at 1270 nm. The highest observed fraction of the Stokes component radiation at 1270 nm in the total output of the Raman laser amounted to 30%. The identified optimal duration of the input pulses at which the amount of Stokes component radiation in a ~16-m long phosphorus-based Raman fibre converter reaches its maximum was 140-180 ps. PMID:26191913

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Force measurements in skinned muscle fibres

    PubMed Central

    Hellam, D. C.; Podolsky, R. J.

    1969-01-01

    1. Isometric force was measured in skinned segments of frog semitendinosus muscle fibres exposed to solutions in which the calcium ion concentration was controlled with EGTA. 2. The threshold for force development, calculated from an apparent stability constant for the CaEGTA complex of 106.69 M-1 at pH 70, was generally close to pCa 75. Maximum force was reached at about pCa 60. 3. Maximum force is proportional to the cross-sectional area of the fibres. 4. The rate of force development was slower than that expected from simple diffusion of a substance from the bathing solution into the fibre. The delay appears to be due to slow equilibration of the EGTA buffer system during calcium uptake by the sarcoplasmic reticulum. 5. Addition of deoxycholate (DOC) to the bathing solution produced a reversible increase in the rate of force development. The steady force was also increased for values of pCa that gave less than maximum force, which shifted the forcepCa relation toward lower calcium concentrations by about 05 pCa unit. 6. The lengthforce relation in partially activated preparations is similar to that reported for electrically activated intact fibres. This result suggests that in the region of myofilament overlap the affinity of the binding sites for calcium is uniform along the length of the calciumbinding myofilament. PMID:5765859

  16. WEAVE MOS fibre bundle test plan

    NASA Astrophysics Data System (ADS)

    Sayde, Frdric; 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.

  17. Photonic crystal fibres with resonant coatings

    NASA Astrophysics Data System (ADS)

    Kuhlmey, Boris T.; McPhedran, Ross C.

    2007-05-01

    Using a multipole method, we numerically analyze photonic crystal fibres with silicon carbide coated holes. We demonstrate resonances resulting from combined geometrical and material effects similar to resonances predicted in the static case by Nicorovici et al. [Phys. Rev. B 14 (1994) 10851], with holes appearing larger than they are or coating effectively disappearing.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. A multi-purpose optical fibre sensor design for fibre reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Fernando, G. F.; Liu, T.; Crosby, P.; Doyle, C.; Martin, A.; Brooks, D.; Ralph, B.; Badcock, R.

    1997-10-01

    This paper reports on the evaluation of a multi-functional extrinsic Fabry - Prot optical fibre-based sensor design. The sensor was constructed using multimode and single mode optical fibres and a precision bore capillary tube. Fusion joints were used to secure the optical fibres into the capillary tube. The separation between the cleaved end-faces of the optical fibres defined the cavity length for the Fabry - Prot sensor and the distance between the fusion joints defined the gauge length for this strain and temperature sensor. The sensor design was modified to: (i) monitor the progress of cure in an epoxy/amine resin system; (ii) detect the ingress of moisture in a cured epoxy/amine resin system; (iii) monitor the vibration characteristics of a pre- and post-impact damaged carbon fibre reinforced epoxy panel; and (iv) discriminate between strain and temperature measurements. The feasibility of using this type of sensor for cure monitoring, strain, temperature, residual stress measurements and damage detection in advanced fibre reinforced composites is demonstrated.

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

    NASA Astrophysics Data System (ADS)

    Olszwka-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.

  4. Analytical sensitivity and reflected power through a D-shape optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Ubeid, M. F.; Shabat, M. M.

    2014-09-01

    In this paper, the reflection properties and sensitivity of a D-shape optical fibre sensor are investigated theoretically and numerically with the emphasis on the metal layer [gold (Au), silver (Ag), copper (Cu), and aluminum (Al)]. Maxwell's equations are used to determine the electric and magnetic fields of the incident waves at each layer. Snell's law is applied and the boundary conditions are imposed at each layer interface to calculate the reflected power and sensitivity of the sensor. In the numerical results, the mentioned power is computed and illustrated as a function of wavelength, angle of incidence, metal layer thickness and refractive index of the external medium when the metal layer changes. The variation of sensitivity with the wavelength of the incident radiations is also proposed for some of the given metals.

  5. 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.

  6. 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).

  7. 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.

  8. 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.

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

    PubMed

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

    2015-12-01

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

  10. 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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Ortiz-Neria, D. I.; Martinez-Pin, 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 15?m 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.

  13. 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

  14. Modified glass fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Cao, Yumei

    A high ratio of strength to density and relatively low-cost are some of the significant features of glass fibre reinforced polymer composites (GFRPCs) that made them one of the most rapidly developed materials in recent years. They are widely used as the material of construction in the areas of aerospace, marine and everyday life, such as airplane, helicopter, boat, canoe, fishing rod, racket, etc. Traditionally, researchers tried to raise the mechanical properties and keep a high strength/weight ratio using all or some of the following methods: increasing the volume fraction of the fibre; using different polymeric matrix material; or changing the curing conditions. In recent years, some new techniques and processing methods were developed to further improve the mechanical properties of glass fibre (GF) reinforced polymer composite. For example, by modifying the surface condition of the GF, both the interface strength between the GF and the polymer matrix and the shear strength of the final composite can be significantly increased. Also, by prestressing the fibre during the curing process of the composite, the tensile, flexural and the impact properties of the composite can be greatly improved. In this research project, a new method of preparing GFRPCs, which combined several traditional and modern techniques together, was developed. This new method includes modification of the surface of the GF with silica particles, application of different levels of prestressing on the GF during the curing process, and the change of the fibre volume fraction and curing conditions in different sets of experiments. The results of the new processing were tested by the three-point bend test, the short beam shear test and the impact test to determine the new set of properties so formed in the composite material. Scanning electronic microscopy (SEM) was used to study the fracture surface of the new materials after the mechanical tests were performed. By taking advantages of the traditional and modern techniques at the same time, the newly developed modified glass fibre reinforced epoxy matrix composites (MGFRECs) have much improved comprehensive properties. The flexural strength, the flexural modulus, the shear modulus and the impact energy (Izod impact test) of the composites were improved up to 87%, 74%, 30% and 89% respectively when modified samples were compared to the samples made by the traditional methods.

  15. Acoustical model of a Shoddy fibre absorber

    NASA Astrophysics Data System (ADS)

    Manning, John Peter

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

  16. 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

  17. 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 (0100%), and proposed an equation to depict the relationship. PMID:24196491

  18. Tapered optical fibre sensor for detection of hydrocarbon spills in seawater

    NASA Astrophysics Data System (ADS)

    Snchez Martn, J. A.; Bernabeu, E.; Rodrguez Aramenda, A.; Villalba, A.; Cruzado, E.; Pardo de Santayana, M.

    2014-05-01

    Three devices based on tapered optical fibres are used to determine the presence of pollutants in water, through the measure of their spectral transmittance. Tapered optical silica fibres, coated (or not) with metallic and dielectric layers (Al or Cu and TiO2) are employed. It is found that, with our experimental arrangement, the presence of products derived from gasoline spills can be determined when we use the coated tapers. A complete characterization of the three different tapers is made in a wide spectral range (1300-1650 nm) and the wavelengths most suitable to detect and discern the hydrocarbons measured are identified. The results obtained show that these devices can be used for the early detection of oil spills in seawater in an industrial environment as simple and versatile sensors that can be self-cleaned with the movement of seawater.

  19. 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.

  20. 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.

  1. 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

  2. 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)

  3. 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.

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

    PubMed

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

    2009-03-30

    There is great interest in developing high performance optical frequency metrology based around mode-locked fibre lasers because of their low cost, small size and long-term turnkey operation when compared to the solid-state alternative. We present a method for stabilising the offset frequency of a fibre-based laser comb using a 2 f - 3 f technique based around a unique fibre that exhibits strong resonant dispersive wave emission. This fibre requires lower power than conventional highly non-linear fibre to generate a suitable signal for offset frequency stabilisation and this in turn avoids the complexity of additional nonlinear steps. We generate an offset frequency signal from the mixing of a wavelength-shifted second harmonic comb with a third harmonic of the comb. Additionally, we have stabilised the repetition rate of the laser to a level better than 10(-14)/ radicaltau , limited by the measurement system noise floor.We present the means for complete and precise measurement of the transfer function of the laser frequency controls. PMID:19333360

  5. 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)

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

    PubMed Central

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

    1988-01-01

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

  7. 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

  8. 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.

  9. Multiphoton absorption in amyloid protein fibres

    NASA Astrophysics Data System (ADS)

    Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

    2013-12-01

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

  10. Retention of Cationic Starch onto Cellulose Fibres

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  11. 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

  12. 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.

  13. In-situ process and condition monitoring of advanced fibre-reinforced composite materials using optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Doyle, C.; Martin, A.; Liu, T.; Wu, M.; Hayes, S.; Crosby, P. A.; Powell, G. R.; Brooks, D.; Fernando, G. F.

    1998-04-01

    This paper presents a general overview of a number of optical fibre sensor systems which have been developed and used in advanced fibre-reinforced composites for in-situ process and condition monitoring. The in-situ process monitoring techniques were optical-fibre-based evanescent wave spectroscopy, transmission near-infrared spectroscopy and refractive index monitoring. The optical fibre sensors were successful in tracking the cure reaction. The condition monitoring of advanced fibre-reinforced composites was carried out using two intensity-based optical fibre sensor systems: an extrinsic multi-mode Fabry-Prot sensor and Bragg gratings. In addition to this, the feasibility of using the reinforcing fibre as a light guide was demonstrated. These sensor systems were evaluated under quasi-static, impact and fatigue loading. The test specimens consisted of prepreg-based carbon-fibre-reinforced epoxy and glass-fibre-reinforced epoxy filament-wound tubes. Excellent correlation was obtained between surface-mounted strain gauges and the embedded optical fibre sensors. The feasibility of using these sensor systems for the detection of impact damage and stiffness reduction in the composite due to fatigue damage was successfully demonstrated.

  14. 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

  15. 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

  16. 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 fibrescells with important mechanical functions and a widely used raw materialare 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 1.21.5 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

  17. 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.

  18. Fluoride Glass Fibre Lasers And Amplifiers

    NASA Astrophysics Data System (ADS)

    France, Paul W.; Brierley, Michael C.

    1990-02-01

    The initial discovery of fluorozirconate glasses at the University of Rennes, France in 1974 [1] followed an attempt to fabricate large pieces of ZrF4 crystals doped with Nd (NdZrF7) for laser applications. One of the samples prepared at the University turned out to be vitreous rather than crystalline and the fluorozirconate glasses had been discovered. Initial interest in these materials was as improved glasses for high energy fusion lasers and in 1978, in a joint publication with the University of Rennes, Weber concluded that the glasses should be considered as candidates for laser materials [2]. A further significance of these new glasses was soon recognised when it was proposed that they might have applications for low loss IR fibres, with intrinsic losses below those in silica, and a considerable amount of work is now underway in an attempt to reach these targets [3]. These two interests were amalgamated in 1987 when the first fluoride fibre laser was demonstrated by Brierley and France [4], doped with Nd and lasing at 1.05 um. Following this work many new dopants have been investigated and many different lasing lines have been reported. This paper reviews these recent developments in fluoride fibre lasers and amplifiers from several laboratories throughout the world and includes some of the latest results on semiconductor diode pumping close to 0.8 um.

  19. 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)

  20. 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).

  1. 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.

  2. 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%.

  3. 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

  4. 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%.

  5. 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

  6. 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.

  7. Influence of chemical treatments on adhesion properties of hemp fibres.

    PubMed

    Le Trodec, M; Rachini, A; Peyratout, C; Rossignol, S; Max, E; Kaftan, O; Fery, A; Smith, A

    2011-04-01

    In addition to be an environmentally friendly material, hemp fibres are also inexpensive reinforcements in thermoplastics or concrete composites, due to their intrinsic mechanical, thermal and acoustic properties. The morphology of hemp fibres has been chemically modified in order to enhance the matrix/fibre interface and has been examined by Scanning Electron Microscopy (SEM). In this paper, Gas Chromatography (GC) and Atomic Force Microscopy (AFM) were used to investigate the influence of treatments on the composition of hemp fibres and also on the micro-adhesive interactions between a silica colloidal probe and the surface of the fibres using Chemical Force Microscopy (CFM). Microscopy studies and chemical analysis showed that each treatment tends to lead to a morphology of interconnected web-like structure of hemp fibres. It was found that on an average, the adhesion force, contribution of capillary force and Van der Waals' forces, is higher in the case of NaOH treatment. PMID:21255789

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Diameter-dependent melting behaviour in electrospun polymer fibres

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Barber, Asa H.

    2010-06-01

    The melting temperature of individual electrospun polyethylene oxide (PEO) fibres was found using atomic force microscopy (AFM) topography imaging and nanomechanical measurements. The melting temperature of electrospun PEO fibres was observed to decrease with decreasing fibre diameter. A model predicting the size-dependent melting temperature in polymers based on surface area showed a good fit with our experimental data, indicating surface-mediated thermal behaviour.

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

    PubMed

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

    2013-12-16

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

  14. 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)

  15. 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

  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. 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

  18. 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.

  19. 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.

  20. 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.

  1. Design and Construction Elements for Scintillating Fibre Tracking Detectors

    NASA Astrophysics Data System (ADS)

    Sharpe, Jason Ray

    In many nuclear and particle physics experiments, it is necessary to ascertain precise information about a particle's trajectory, or its position at specific locations (as a means for then determining angle or momentum). A common way to determine this information is by using a scintillating fibre tracker, a device that relies on scintillation light from ionizing charged particles (such as electrons or protons) within scintillating fibres, and guiding the produced scintillation light through standard fibre optics to determine which scintillating fibre detected the particle. This thesis discusses, and presents results for technical issues associated with designing and constructing such a detector: (1) adjacent scintillating fibre-to-fibre cross-talk, and (2) the effect on light transmission of the combination of different fibre-end finishes and clear-to-scintillating fibre optical couplants. These results will be directly incorporated into the construction of a scintillating fibre coordinate detector to be built for future experiments at Jefferson Lab's Hall A in Newport News, VA, USA.

  2. High power resonantly pumped holmium-doped fibre sources

    NASA Astrophysics Data System (ADS)

    Hemming, Alexander; Simakov, Nikita; Haub, John; Carter, Adrian

    2014-03-01

    Holmium-doped fibres provide a power scalable gain-medium capable of operation at wavelengths beyond 2.05 ?m. We discuss and review our approach to the power scaling of pulsed and CW laser sources at 2.1 ?m using holmium-doped fibres. This paper outlines experiments which demonstrate the wavelength region accessible using holmium-doped silica fibres, as well as a linearly polarised pulsed master-oscillator power amplifier and high average power CW laser and amplifier systems. These devices demonstrate the applicability of holmium fibre lasers to a range of scientific, medical, industrial and defence applications.

  3. 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.

  4. The myelin sheath aqueous layers improve the membrane properties of simulated chronic demyelinating neuropathies.

    PubMed

    Stephanova, D I; Krustev, S M; Negrev, N; Daskalova, M

    2011-03-01

    Recently, patients with chronic demyelinating neuropathies have demonstrated significant abnormalities in their multiple nerve excitability properties measured by a non-invasive threshold tracking technique. In order to expand our studies on the possible mechanisms underlying these abnormalities, which are not yet well understood, we investigate the contributions of the aqueous layers within the myelin sheath on multiple membrane properties of simulated fibre demyelinations. Four degrees of systematic paranodal demyelinations (two mild demyelinations termed PSD1 and PSD2, without/with aqueous layers respectively, and two severe demyelinations termed PSD3 and PSD4, with/without aqueous layers, respectively) are simulated using our previous multi-layered model of human motor nerve fibre. We studied the following parameters of myelinated axonal function: potentials (intracellular action, electrotonic-reflecting the propagating and accommodative fibre processes, respectively) and strength-duration time constants, rheobases, recovery cycles (reflecting the adaptive fibre processes). The results show that each excitability parameter is markedly potentiated when the aqueous layers within their paranodally demyelinated sheaths are taken into account. The effect of the aqueous layers is significantly higher on the propagating processes than on the accommodative and adaptive processes in the fibres. The aqueous layers restore the action potential propagation, which is initially blocked when they are not taken into account. The study provides new and important information on the mechanisms of chronic demyelinating neuropathies, such as chronic inflammatory demyelinating polyneuropathy (CIDP). PMID:21425485

  5. Damage detection in glass fibre-reinforced plastic composites using self-sensing E-glass fibres

    NASA Astrophysics Data System (ADS)

    Kister, Guillaume; Ralph, Brian; Fernando, Gerard F.

    2004-10-01

    The detection of damage in fibre-reinforced composite materials is important in areas where these materials are used for load-bearing applications. This paper reports on the use of conventional reinforcing E-glass fibres that were made to act as light guides. These reinforcing fibre light guides were used to detect damage induced in the composite by impact, indentation and flexure. The E-glass fibres were converted into light guides by applying an appropriate cladding material. The coating resins used in this study were an epoxy- and a polyurethane-based resin system. These self-sensing fibres or reinforcing fibre light guides were surface mounted and also embedded at two specified locations within 16-ply glass fibre-reinforced epoxy prepreg composites. The data generated in this study demonstrated that the self-sensing concept could be used to study in situ and in real time the failure processes in glass fibre-reinforced composites. A detailed study was also undertaken to characterize the various failure modes observed when the composites with the self-sensing light guides were subjected to impact, indentation and flexural loading. The damaged areas in the composite were easily located by means of the 'bleeding' light emanating from the broken self-sensing E-glass fibres.

  6. Effects of the initial chirp and fibre loss on the soliton mechanism of picosecond pulse compression in optical fibres

    SciTech Connect

    Yang Xingyu; Yang Guangqiang

    2001-08-31

    The effect of the initial chirp and fibre loss on the efficiency of soliton-effect picosecond pulse compression are analysed by simulating numerically the transmission of picosecond pulse in fibres by the split-step Fourier method. Analysis of changes in the compression factor, the optimum fibre length, and the compression efficiency showed that the initial chirp and fibre loss affect the compression of a picosecond pulse in opposite ways. A further study revealed that an additional properly created initial chirp provides good pulse compression. (nonlinear optical phenomena)

  7. The influence of fibre placement and position on the efficiency of reinforcement of fibre reinforced composite bridgework.

    PubMed

    Ellakwa, A E; Shortall, A C; Shehata, M K; Marquis, P M

    2001-08-01

    The effect of placement of ultra-high molecular weight polyethylene (UHMWPE) fibres on the flexural properties and fracture resistance of a direct dental composite was investigated. The UHMWPE fibres are increasingly being used for the reinforcement of laboratory fabricated resin composite crown and bridgework. The aim of this study was to assess the effect of a commonly used laboratory fabrication variable on the in vitro strength of beam shaped specimen simulating a three-unit fixed bridge. Four groups (10 specimens per group) of Herculite XRV were prepared for flexural modulus and strength testing after reinforcement with UHMWPE fibres. Two groups of control specimens were prepared without any fibre reinforcement. Half the specimen groups were stored in distilled water and the other groups were stored dry, both at 37 degrees C for 2 weeks before testing. The results of this study showed that placement of fibre at or slightly away from the tensile side improved the flexural properties of the composite in comparison with the unreinforced control specimen groups whilst the mode of failure differed according to fibre position. Scanning electron microscope (SEM) investigation revealed that placement of the fibre slightly away from the tensile side favoured crack development and propagation within the resin bridging the interfibre spaces in addition to debonding parallel to the direction of fibre placement. Laboratory fabrication variables may effect the strength of fibre reinforced bridgework significantly. PMID:11556961

  8. Morphological and chemical characterization of microfabricated fibres for biological applications.

    PubMed

    Gold, J; Kasemo, B

    1997-05-01

    Monodisperse fibres and particulates of different materials with controllable three-dimensional shape, size and chemical composition are of interest in research on toxic respirable fibres as well as wear debris around orthopaedic implants. We have previously demonstrated the production of well-controlled, metal and oxide microfabricated fibres having dimensions 0.1 to 10 microm. While our previous results focused on how controlled fibres can be prepared by microfabrication methods, this paper evaluates property-production relationships for microfabricated fibres. Here we have briefly reviewed the production of 0.1 microm x 0.5 microm x 10 microm microfabricated fibres made by electron beam lithography from evaporated titanium or silicon oxide films using a double lift-off method. We have also analysed the properties of these fibres with respect to morphology and chemical composition, and how they are affected by variations in the production process. Two different solution types have been used to place fibres into liquid suspension and to clean and sterilize them for biological testing. One method involves the use of organic solvents; the other a hydroxide solution and water. While fibre dimensions appear to be material-specific, differences can be corrected for by compensation of the size of the lithographic pattern. Similarly the crystallinity of fibres is material-specific, as is to be expected of evaporated thin films, but should be possible to modify by varying deposition parameters or heat treating, for example. Of the cleaning methods used, the one using an aqueous hydroxide solution is preferred over solvent cleaning, as it is easier to perform and appears to be more effective at removing resist from the fibre suspension. PMID:15348746

  9. Human cutaneous C fibres activated by cooling, heating and menthol.

    PubMed

    Campero, M; Baumann, T K; Bostock, H; Ochoa, J L

    2009-12-01

    Differential A-fibre block of human peripheral nerves changes the sensation evoked by innocuous cooling (approximately 24 degrees C) of the skin from 'cold' to 'hot' or 'burning', and this has been attributed to activity in unidentified unmyelinated fibres that is normally masked or inhibited by activity in Adelta cold fibres. Application of the TRPM8 agonist menthol to the skin evokes 'burning/stinging' as well as 'cold', and the unpleasant sensations are also enhanced by A-fibre block. In this study we used microneurography to search for C fibres in human skin activated by cooling and menthol, which could be responsible for these phenomena. Afferent C fibres were classified by activity-dependent slowing as Type 1A (polymodal nociceptor), Type 1B (mechanically insensitive nociceptor) or Type 2 (cold sensitive), and their responses to heating and cooling ramps were measured before and after topical application of menthol preparations (2-50%). The only C fibres activated by menthol were the Type 2 fibres, which discharged vigorously with innocuous cooling and were strongly activated and sensitized to cooling by menthol. Unlike an Adelta cold fibre, they continued to discharge at skin temperatures down to 0 degrees C, and most (13/15) were also activated by heating. We propose that the Type 2 C fibres, although resembling Adelta cold fibres in their responses to innocuous cooling and menthol, have a more complex sensory function, colouring with a 'hot-burning' quality the perceptions of low and high temperatures. Their bimodal thermoreceptive properties may help account for several puzzling psychophysical phenomena, such as 'innocuous cold nociception', 'paradoxical heat' and the thermal grill illusion, and also for some neuropathic pains. PMID:19822550

  10. Processing with kW fibre lasers: advantages and limits

    NASA Astrophysics Data System (ADS)

    Kratky, A.; Schucker, D.; Liedl, G.

    2008-10-01

    Up-to-date fibre lasers produce multi-kw radiation with an excellent beam quality. Compared to CO2-lasers, fibre lasers have relatively low operational costs and offer a very high flexibility in production due to the beam delivery with process fibres. As a consequence, fibre lasers have attracted more and more attention. On the other hand, their use in industrial applications especially in the automotive industry is still limited to a certain extent and fibre lasers haven't replaced all other laser sources till now as it could be expected. In laser cutting, the small kerf width produced by fibre lasers should be advantageous since the heated volume is smaller compared to CO2-lasers. In fact, cutting velocities are usually much higher which is also caused by the higher absorption coefficient of most metals at the wavelength emitted by fibre lasers. Nevertheless, cutting with fibre lasers of some metals - e.g. stainless steels - is restricted to a small thicknesses of approx. 5mm. The reason for this is that the surface roughness of the edges increases dramatically with the thickness of the work piece. Applications of fibre lasers include e.g. remote welding or even remote cutting of a large variety of materials with usually excellent results. Due to the excellent beam quality the aspect ratio of the weld seam in relation to the penetration depth is quite good. In the case of thin sheet metal welding such a small beam waist is beneficial - but with thicker sheet metals it is very often disadvantageous since the preparation of samples is more complicated, costs increase and requirements on clamping devices rise. In this paper, advantages and disadvantages of fibre lasers are discussed briefly. Applications of a 1.5 kW fibre laser are presented and compared to classical laser systems.

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. Enteric co-innervation of striated muscle fibres in human oesophagus.

    PubMed

    Kallmnzer, B; Srensen, B; Neuhuber, W L; Wrl, J

    2008-06-01

    Oesophageal striated muscle of several mammalian species receives dual innervation from both vagal motor fibres originating in the brain stem and enteric nerve fibres originating in myenteric ganglia. The aim of this study was to investigate this so-called enteric co-innervation in the human oesophagus. Histochemical and immunohistochemical methods combined with confocal laser scanning microscopy were utilized to study innervation of 14 oesophagi obtained from body donors (age range 47-95 years). In addition, the distribution of striated and smooth muscle in longitudinal and circular layers of the tunica muscularis was studied semiquantitatively. The upper half of the oesophagus was built up of both muscle types with a predominance (>50-60%) of striated muscle, whereas the lower half consisted of smooth muscle only. The majority of motor endplates was compact and ovoid. Enteric nerve fibres on approximately 17% of motor endplates stained for neuronal nitric oxide synthase, vasoactive intestinal polypeptide, galanin and neuropeptide Y and were completely separated from vagal cholinergic nerve terminals. There was remarkable variability of co-innervation rates between striated muscle bundles with some reaching almost 50%. Myenteric neurons representing the putative source of enteric co-innervating nerve fibres, stained for all these markers, which were almost completely colocalized with NADPH-diaphorase. Our study provides evidence for enteric co-innervation of striated muscle in human oesophagus. From these and recent functional results in various rodent species, we suggest that this innervation component represents an integral part of an intramural reflex mechanism for local most likely inhibitory modulation of oesophageal motility. PMID:18221249

  17. Evaluation of the macula, retinal nerve fiber layer and choroid thickness in postmenopausal women and reproductive-age women using spectral-domain optical coherence tomography

    PubMed Central

    Ata?, Mustafa; Aksoy, Hseyin; Demircan, Sleyman; Gkta?, Altan; Arifo?lu, Hasan Basri; Zarars?z, Gkmen

    2014-01-01

    Objective Menopause is a physiological life period that potentially affects various organs and systems. Therefore, a wide spectrum of signs and symptoms of eyes may be clinically observed in the postmenopausal period. Aim of the study To evaluate the macular, retinal nerve fiber layer (RNFL) and choroidal thickness alterations by using spectral-domain optical coherence tomography (SD-OCT) in postmenopausal women and compare with healthy reproductive-age women controls. Material and methods The study population included a healthy reproductive-age control group (n = 72) and postmenopausal study group (n = 72). Retinal thickness parameters were measured by SD-OCT. Peripapillary RNFL thickness parameters, macular thickness and choroidal thickness were evaluated. Results Superior inner macula, temporal inner macula, inferior inner macula, nasal inner macula, inferior outer macula and choroid thickness were significantly thinner in the postmenopausal study group than the healthy reproductive-age control group (p = 0.007, p = 0.037, p = 0.027, p = 0.006, p = 0.016, p < 0.001, respectively). After adjusting for age, only choroid thickness was significantly thinner in the postmenopausal study group than controls (p = 0.005). Conclusions This study revealed that choroidal thickness measured by SD-OCT was significantly thinner in postmenopausal women than healthy reproductive-age women. We can speculate that the decrease in choroidal thickness in postmenopausal women may indicate a reduced estrogen-dependent vasodilatory effect in ophthalmic artery secondary to menopausal estrogen deficiency. PMID:26327827

  18. The mechanical and thermal properties of frog slow muscle fibres

    PubMed Central

    Floyd, K.; Smith, I. C. H.

    1971-01-01

    1. A study has been made of the mechanical behaviour and the heat production of frog slow muscle fibres in iliofibularis nervemuscle preparations at 20 C. 2. The slow fibre isometric tension and its rate of development increase with stimulation frequency, the increases beyond 30 Hz being relatively small. Relaxation rate also increases with stimulation frequency. The tensionlength curve and maximum isometric tension (250 mN.mm-2) are similar to those of twitch fibres. The maximum shortening velocity is estimated to be 011 tonus bundle lengths per second. 3. For contractions up to 60 sec at 30-50 Hz the slow fibre heat rate is steady at 6 mJ.g-1.sec-1. Slow fibres produce aerobic recovery heat with a time course similar to that of twitch fibres. 4. The accuracy of the results is discussed, and a comparison is made with the properties of twitch fibres. It is concluded that the tension-producing reactions are thirty times slower in the slow fibres. PMID:5551404

  19. Fibres Optiques En Therapie Laser Au Contact Du Tissu

    NASA Astrophysics Data System (ADS)

    Lenz, P.; Sabben, G.; Lambert, R.; Berger, F.

    1984-03-01

    Les fibres en quartz, non protegees par un courant de gaz et placees au contact du tissu, peuvent etre utilisees pratiquement indefiniment grace a un "autonettoyage" et une "regenera-tion". Elles provoquent des lesions tissulaires semblables a celles obtenues avec les fibres conventionnelles.

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

    PubMed

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

    2016-06-01

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

  1. 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 ?m, 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Rheinlnder, Jrgen; 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.

  4. 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.

  5. Dietary fibre and health in children and adolescents.

    PubMed

    Edwards, Christine A; Xie, Chengru; Garcia, Ada L

    2015-08-01

    The role of dietary fibre in promoting sustained health has been studied for several decades and in adults there is good evidence that diets rich in high-fibre foods reduce the risk of chronic diseases, including CVD and cancer. Research in this area, however, has been hampered by uncertainties about the definition of dietary fibre which has resulted in many studies measuring fibre in different ways. There is also a wide range of properties and actions of different fibres in the human body, depending on their solubility, viscosity and fermentability by the colonic microbiota. This review considers the epidemiological evidence for dietary fibre and health in children and the current dietary recommendations and measured intakes in several countries using national surveys. In children and adolescents, there is a particular lack of relevant research on which to formulate appropriate dietary fibre recommendations and these are often based on extrapolation from adult data. However, children are not little adults and have differing physiology and nutritional needs as they grow. The dietary recommendations in different countries are based on varying premises and daily amounts. Intakes vary from country to country and on the whole do not meet recommendations. Much more research is needed in children to fully understand the impact of dietary fibre on growth and health in the young to allow more appropriate recommendations to be made. PMID:26186674

  6. 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.

  7. 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

  8. Comparison of Surface Plasmon Resonance and Localized Surface Plasmon Resonance-based optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Cao, J.; Galbraith, E. K.; Sun, T.; Grattan, K. T. V.

    2011-08-01

    In this work, two of surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR)-based optical fibre sensors have been successfully developed and cross-compared. With one SPR sensor being coated with a thin layer of gold film and the other gold-nanorods (GNRs), forming a LSPR sensor, both sensors are subjected to various refractive index changes. As a result their sensitivities are measured in the form of resonance wavelength shift as a function of refractive index variation. The results demonstrate that the thin-film coated SPR sensor has much higher sensitivity than that of GNRs coated LSPR sensor but with worse linearity.

  9. 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

  10. 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??m 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.

  11. 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.

  12. 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 ?m/330 ?m, 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 ?m wavelength can be achieved at 2.75 ?m operating wavelength with Er3+ ion concentrations of 60,000 ppm.

  13. Modelling Small Angle Neutron Scattering Data from Electrospun Fibres

    NASA Astrophysics Data System (ADS)

    Mohan, Saeed D.; Fred; Davis, J.; Olley, Robert H.; Mitchell, Geoffrey R.

    2010-10-01

    Electrospinning is a technique employed to produce nanoscale to microscale sized fibres by the application of a high voltage to a spinneret containing a polymer solution. Here we examine how small angle neutron scattering data can be modelled to analyse the polymer chain conformation. We prepared 1:1 blends of deuterated and hydrogenated atactic-polystyrene fibres from solutions in N, N-Dimethylformamide and Methyl Ethyl Ketone. The fibres themselves often contain pores or voiding within the internal structure on the length scales that can interfere with scattering experiments. A model to fit the scattering data in order to obtain values for the radius of gyration of the polymer molecules within the fibres has been developed, that includes in the scattering from the voids. Using this model we find that the radius of gyration is 20% larger than in the bulk state and the chains are slightly extended parallel to the fibre axis.

  14. Nanoimprinted optical fibres: Biotemplated nanostructures for SERS sensing.

    PubMed

    Kostovski, G; White, D J; Mitchell, A; Austin, M W; Stoddart, P R

    2009-01-01

    Optical fibre surface-enhanced Raman scattering (SERS) sensors offer a potential solution for monitoring low chemical concentrations in remote or in situ sensing scenarios. The SERS effect relies on the interaction of analyte molecules with nanostructured metal surfaces. We demonstrate a nanoscale biotemplating approach to fabricating these sensors, using nanoimprint lithography to replicate cicada wing antireflective nanostructures onto the end faces of standard silica optical fibres. These SERS-compatible nanoarrays are coated with silver to make them SERS active, and thiophenol and rhodamine 6G are used as test analytes, from which strong SERS spectra are collected using both direct endface illumination and through-fibre interrogation. This combination of biological templates with nanoscale replication and optical fibres demonstrates a high-resolution, low-cost approach to fabricating high-performance optical fibre SERS sensors. PMID:19084390

  15. Experimental Determination of the Transversal and Longitudinal Fibre Bundle Permeability

    NASA Astrophysics Data System (ADS)

    Schell, J. S. U.; Siegrist, M.; Ermanni, P.

    2007-03-01

    In the resin transfer moulding process, fabrics are very often used as reinforcement. These fabrics consist of fibre bundles. In this context, both the permeability of the macroscopic fabric and the permeability of the fibre bundle are the key parameters to accurately predict the impregnation of the fabrics, the impregnation time and resulting void content. The fibre bundle permeability can be either predicted theoretically or experimentally. Whereas the theoretical determination lacks on accuracy as the realistic packing of the fibres in the bundles is not integrated in the models. In this work, we present an experimental setup to measure the longitudinal and transversal permeability of fibre bundles. The results are compared to model predictions.

  16. 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.

  17. 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.

  18. Soft x-ray spectromicroscopy of wood fibre composites

    NASA Astrophysics Data System (ADS)

    Michette, A. G.; Phanopoulos, C.; Newell, R. J.; McFaul, C.; Pfauntsch, S. J.; Pans, G.; Wirick, S.

    2009-09-01

    Understanding the structural properties of wood fibre composites, widely used in building and other applications, is an important area of research in devising robust new materials for a range of environmental conditions, including those encountered in developing countries. Wood fibre composites are prepared by mixing fibres with prescribed amounts of glue, but exactly where the glue distributes in relation to the fibre components is unclear. Characterisation of the bonding conditions has largely been a matter of trial and error, which is time consuming and imprecise. In soft x-ray spectromicroscopy experiments carried out at the NSLS, a range of wood fibre composites, with different glues and glue loadings, was studied in order to attempt to quantify the relative glue content in different components of the composite.

  19. 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

  20. 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.

  1. Sugarcane fibre may prevents hairball formation in cats.

    PubMed

    Loureiro, Bruna A; Sembenelli, Guilherme; Maria, Ana P J; Vasconcellos, Ricardo S; S, Fabiano C; Sakomura, Nilva K; Carciofi, Aulus C

    2014-01-01

    Hair ingested by licking during cat grooming can eventually coalesce into solid masses in cat gastrointestinal tract. It is believed that dietary fibre might reduce formation of these trichobezoars (hairballs). The effects of two insoluble fibre sources added to kibble diets were evaluated with respect to trichobezoar faecal excretion. Thirty-two cats and four diets were used in a randomised block design: a control diet without additional fibre, 10% added sugarcane fibre, 20% added sugarcane fibre or 10% added cellulose. Animals were fed for 42d and during three separate periods (days 15-17, 25-27 and 40-42), the cats were housed individually in metabolic cages and their faeces were totally collected. The faeces were evaluated and the trichobezoars were isolated and classified into small (<1cm), medium (11-2cm) or large (>21cm). Means were evaluated by repeated measures ANOVA and contrasts (P<005). Cats fed sugarcane fibre shown a linear reduction of small and medium trichobezoar excretion (number per cat per day; P=0004) as well as a reduction in trichobezoar mass excretion (mg per cat per day; P<001). The control group showed increased faecal excretion of large trichobezoars (P=0003), which were not present in the high sugarcane fibre group (P<0006). No effect of cellulose was observed for any evaluated trait. Therefore, long fibres (sugarcane fibre) may cause greater peristaltic stimulation, increasing the propulsion of hair through the gut, but further research is needed to validate this mechanism. In conclusion, sugarcane fibre reduced faecal hairball elimination in cats, which may have clinical applications for the prevention of health problems related to trichobezoars. PMID:26101589

  2. 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.

  3. 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)

  4. 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 elastichydrodynamic 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

  5. 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

  6. Spiders spinning electrically charged nano-fibres.

    PubMed

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland-duct-spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. PMID:25631231

  7. Auto-inhibition of rat parallel fibrePurkinje cell synapses by activity-dependent adenosine release

    PubMed Central

    Wall, Mark J; Dale, Nicholas

    2007-01-01

    Adenosine is an important signalling molecule involved in a large number of physiological functions. In the brain these processes are as diverse as sleep, memory, locomotion and neuroprotection during episodes of ischaemia and hypoxia. Although the actions of adenosine, through cell surface G-protein-coupled receptors, are well characterized, in many cases the sources of adenosine and mechanisms of release have not been defined. Here we demonstrate the activity-dependent release of adenosine in the cerebellum using a combination of electrophysiology and biosensors. Short trains of electrical stimuli delivered to the molecular layer in vitro, release adenosine via a process that is both TTX and Ca2+ sensitive. As ATP release cannot be detected, adenosine must either be released directly or rapidly produced by highly localized and efficient extracellular ATP breakdown. Since adenosine release can be modulated by receptors that act on parallel fibrePurkinje cell synapses, we suggest that the parallel fibres release adenosine. This activity-dependent adenosine release exerts feedback inhibition of parallel fibrePurkinje cell transmission. Spike-mediated adenosine release from parallel fibres will thus powerfully regulate cerebellar circuit output. PMID:17347275

  8. 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

  9. 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

  10. 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

  11. 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.

  12. Retinal nerve fiber layer thickness map and blood flow pulsation measured with SDOCT

    NASA Astrophysics Data System (ADS)

    Mujat, Mircea; Chan, Raymond C.; Cense, Barry; Pierce, Mark; 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 intended for non-invasive optical diagnostics. It has been suggested that OCT can be used for di-agnosis of glaucoma by measuring the thickness of the Retinal Nerve Fiber Layer (RNLF). We present an automated method for determining the RNFL thickness from a 3-D dataset based on edge detection using a deformable spline algo-rithm. The RNFL thickness map is combined with an integrated reflectance map and retinal cross-sectional images 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 motion artifacts are significantly reduced as com-pared to slower time-domain systems. Combined with Doppler Velocimetry, SDOCT also provides information on retinal blood flow dynamics. We analyzed the pulsatile nature of the bidirectional flow dynamics in an artery-vein pair for a healthy volunteer at different locations and for different blood vessel diameters. The Doppler phase shift is determined as the phase difference at the same point of adjacent depth profiles, and is integrated over the area delimited by two circles corresponding to the blood vessels location. Its temporal evolution clearly shows the blood flow pulsatile nature, the cardiac cycle, in both artery and vein. The artery is identified as having a stronger variation of the integrated phase shift. We observe that artery pulsation is always easily detectable, while vein pulsation seems to depend on the veins diameter.

  13. 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.

  14. 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.

  15. Fibre intake and incident colorectal cancer depending on fibre source, sex, tumour location and Tumour, Node, Metastasis stage.

    PubMed

    Vulcan, Alexandra; Brndstedt, Jenny; Manjer, Jonas; Jirstrm, 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 Malm 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

  16. 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.

  17. Focussed ion beam machining of an in-fibre 45 mirror for fibre end sensors

    NASA Astrophysics Data System (ADS)

    Li, J.; Sun, J. N.; Miliar, M. M.; Ritchie, J. M.; Luo, X.; Maier, R. R. J.; Hand, D. P.; MacPherson, W. N.

    2013-05-01

    Focussed Ion Beam (FIB) machining has been demonstrated to be capable of fabricating nano and micro-structure elements. In this paper we demonstrate techniques to design and fabricate a 45 mirror on the end of both conventional single mode and multi-core fibres (MCF) using FIB processing. The mirror is finished by a two step process: first a scanning process is used to make a rough cut 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 that the fabricated structure is capable of measuring two axis displacements interferometrically with a maximum displacement up to 1.0mm and an rms error of ~50nm.

  18. [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

  19. 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

  20. Electron beam irradiation in natural fibres reinforced polymers (NFRP)

    NASA Astrophysics Data System (ADS)

    Kechaou, B.; Salvia, M.; Fakhfakh, Z.; Juv, D.; Boufi, S.; Kallel, A.; Trheux, D.

    2008-11-01

    This study focuses on the electric charge motion in unsatured polyester and epoxy composites reinforced by natural fibres of Alfa type, treated by different coupling agents. The electric charging phenomenon is studied by scanning electron microscopy mirror effect (SEMME) coupled with the induced current method (ICM). Previously, using the same approach, glass fibre reinforced epoxy (GFRE) was studied to correlate mechanical [B. Kchaou, C. Turki, M. Salvia, Z. Fakhfakh, D. Trheux, Composites Science and Technology 64 (2004) 1467], or tribological [B. Kchaou, C. Turki, M. Salvia, Z. Fakhfakh, D. Trheux, Dielectric and friction behaviour of unidirectionalglass fibre reinforced epoxy (GFRE), Wear, 265 (2008) 763.] properties and dielectric properties. It was shown that the dielectric properties of the fibre-matrix interfaces play a significant role in the optimization of the composite. This result seems to be the same for natural fibre composites: the fibre-matrix interfaces allow a diffusion of the electric charges which can delocalize the polarization energy and consequently delay the damage of the composite. However, a non-suited sizing can lead to a new trapping of electric charges along these same interfaces with, as a consequence, a localization of the polarisation energy. The optimum composite is obtained for one sizing which helps, at the same time, to have a strong fibre-matrix adhesion and an easy flow of the electric charges along the interface.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Temperature-dependent characterization of optical fibres for distributed temperature sensing in hot geothermal wells

    NASA Astrophysics Data System (ADS)

    Reinsch, Thomas; Henninges, Jan

    2010-09-01

    This study was performed in order to select a proper fibre for the application of a distributed temperature sensing system within a hot geothermal well in Iceland. Commercially available high temperature graded index fibres have been tested under in situ temperature conditions. Experiments have been performed with four different polyimide-coated fibres, a fibre with an aluminium coating and a fibre with a gold coating. To select a fibre, the relationship between attenuation, temperature and time has been analysed together with SEM micrographs. Based on these experiments, polyimide fibres have been chosen for utilization. Further tests in ambient and inert atmosphere have been conducted with two polyimide-coated fibres to set an operating temperature limit for these fibres. SEM micrographs, together with coating colour changes have been used to characterize the high temperature performance of the fibres. A novel cable design has been developed, a deployment strategy has been worked out, and a suitable well for deployment has been selected.

  7. 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.

  8. Carbon fibre-reinforced silicon nitride composites by slurry infiltration

    SciTech Connect

    Grenet, C.; Plunkett, L.; Veyret, J.B.; Bullock, E.

    1995-12-01

    The present paper reports on the fabrication of long-carbon fibre reinforced silicon nitride matrix composites by liquid infiltration of an aqueous Si{sub 3}N{sub 4} slurry followed by hot-pressing. A methodology for the maximum volume and uniform infiltration of preforms has been developed by optimising slurry rheology and fibre wetting conditions. Fully infiltrated green forms of 55% theoretical density are achieved with some 40% volume fraction of fibres. The quality of the composites has been assessed by microstructural analysis and mechanical characterization.

  9. 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.

  10. Single fibre EMG findings in polyneuropathies of different aetiology.

    PubMed Central

    Thiele, B; Stlberg, E

    1975-01-01

    Single fibre electromyography was carried out in patients with polyneuropathy due to uraemia, diabetes, and alcohol. In the two former groups the fibre density within the motor unit and the impulse transmission were mainly normal. In the latter group the fibre density was significantly increased as signs of reinnervation. Impulse transmission was impaired in a number of the action potential complexes, which is typical of active reinnervation. The results may indicate that the diabetic and uraemic polyneuropathies are characterized in the main by demyelination, whereas the alcoholic type is dominated by axonal lesion even at an early stage. PMID:171347

  11. Laser structured fibre Bragg gratings as enhanced force sensors

    NASA Astrophysics Data System (ADS)

    Marchi, G.; Stephan, V.; Huber, H.; Roths, J.

    2015-09-01

    The production and characterisation of a micro-structured FBG force sensor is described. Employing femtosecond laser micro machinery a circumferential ditch of about 30 ?m depth and 40 ?m width is engraved in the clad of an optical fibre at the centre of a 3 mm long type I fibre Bragg grating (FBG). The purpose of the structure is the enhancement of the force sensitivity characteristics for the measurement of sub-mN forces. Phase-shift spectra occur when axial stress is applied to the fibre. Exploiting this phenomenon experimental tests show a 10% improvement in the sensitivity performance when compared to an unstructured FBG.

  12. 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)

  13. 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.

  14. Comparison of surface functionalization processes for optical fibre biosensing applications

    NASA Astrophysics Data System (ADS)

    Franois, Alexandre; Ebendorff-Heidepriem, Heike; Monro, Tanya M.

    2009-10-01

    Optical fibres are a platform of interest for biosensing due to their low cost, high robustness and long interaction length with their surroundings. However, the sensitivity of these techniques lags behind chemiluminescence and other techniques. Here we explore opportunities for improving the sensitivity of fibre-based biosensors by investigating the process by which biomolecules are immobilized onto the glass. Two immobilization technologies are compared: the well-known silane technology and the emerging polyelectrolyte method. This was done using a specific interaction model based on biotin-streptavidin. The number of specific binding sites as well as the induced losses within a microstructured fibre has been characterized.

  15. 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

  16. 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

  17. Biaxial extension of knitted steel fibre fabrics

    NASA Astrophysics Data System (ADS)

    Vanclooster, K.; Eshghyar, A.; Lomov, S. V.

    2011-05-01

    In this paper knitted steel fibre fabrics will be tested in biaxial extension. An in-house developed biaxial extension machine is used to apply a variety of strain conditions, which allows investigating the coupling between the wale and course direction of the fabrics and the degree of anisotropy in the fabric. Prior to testing a pretension level, to compensate the slack nature of the fabric, is determined by using a laser-measuring device. The strain inside the fabric is measured using a CCD camera technique. The results show the non-linear behaviour of the fabric and the coupling between the wale and the course direction. This will lead to a test protocol that can be used to evaluate the biaxial response of different types of knitted fabrics.

  18. Annular nanoantenna on fibre micro-axicon.

    PubMed

    Grosjean, T; Fahys, A; Suarez, M; Charraut, D; Salut, R; Courjon, D

    2008-02-01

    In this paper, we propose to extend the concept of loop antenna to the optical domain. The aim is to develop a new generation of optical nanocollectors that are sensitive to specific electric or magnetic vectorial field components. For validating our approach, a preliminary one-micron-diameter gold nanoring is micromachined on the apex of a cone lens obtained from a tapered optical fibre. It is shown that such a nano-object behaves as a nano-antenna able to detect the longitudinal electric field from a Bessel beam in radial polarization and the longitudinal magnetic component from a Bessel beam in azimuthal polarization. In the latter case, the annular nano-antenna exhibits the properties of an optical inductance. PMID:18304097

  19. Controlled disassembly of peptide amphiphile fibres.

    PubMed

    Lwik, Dennis W P M; Meijer, Joris T; Minten, Inge J; van Kalkeren, Henri; Heckenmller, Lisa; Schulten, Ines; Sliepen, Kwinten; Smittenaar, Peter; van Hest, Jan C M

    2008-02-01

    In this paper, the introduction of both a methionine residue and a nitrobenzyl derivative as a labile linker between the peptide part and the hydrophobic alkyl chain of a peptide amphiphile are presented. These modifications are shown not to inhibit the formation of structured assemblies that analogous peptide amphiphiles lacking the linkers are able to form. Moreover, the introduction of either labile linker allows removal of the peptide amphiphile's stabilizing hydrophobic moieties to initiate a controlled disassembly of fibre aggregates. This is achieved by either treatment with CNBr or UV irradiation, respectively. These disassembly mechanisms could be the starting point for methodology that allows further manipulation of self-assembled peptide amphiphile architectures. PMID:18044820

  20. Multimode supercontinuum generation in chalcogenide glass fibres.

    PubMed

    Kubat, Irnis; Bang, Ole

    2016-02-01

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

  1. 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.

  2. Structuring of glass fibre surfaces by laser-induced front side etching

    NASA Astrophysics Data System (ADS)

    Lorenz, Pierre; Ehrhardt, Martin; Zimmer, Klaus

    2014-05-01

    The fabrication of sub-?m structures on glass fibre surfaces poses a big challenge for the laser processing. However, the laser-induced front side etching (LIFE) method has a great potential for the fast, nm-precision, and cost-effective production of surface structures. LIFE is a method for laser etching of transparent materials using thin absorber layers with a high absorption coefficient like metal layers. The LIFE process of the front surface of a fused silica wafer as well as of a glass fibre is studied in dependence on the laser parameters. A KrF excimer laser with a wavelength of 248 nm and a pulse duration of 25 ns was used. The resultant structures were analysed with microscopic methods (white light interferometry, scanning electron microscopy (SEM)). The analysing of the surface structures presented that the LIFE methods allow the fabrication of well-defined periodic sub-?m structures. Furthermore, the structuring process was simulated by a thermodynamic equation including an approach of the laser-plasma interaction. The theoretically predicted results presented a good agreement with the experimental results.

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

    SciTech Connect

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

    2010-09-10

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

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

    SciTech Connect

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

    2011-01-24

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

  5. Theoretical modelling of magnetoelectric effects in multi-push-pull mode Metglas/piezo-fibre laminates

    NASA Astrophysics Data System (ADS)

    Li, M.; Hasanyan, D.; Wang, Y.; Gao, J.; Li, J.; Viehland, D.

    2012-09-01

    A theoretical model is presented for magnetoelectric (ME) effects in multi-push-pull mode magnetostrictive/piezo-fibre laminate composites. Analytical solutions for the ME coefficient (?ME) were derived. The effects of thickness ratio of the magnetostrictive phase, Kapton and multiple layers of epoxy on the value of ?ME were discussed. Experimental results agreed well with the theoretical analysis. When the thickness ratio of the magnetostrictive phase was v = 0.63, ?ME was found to have a maximum value of 25.6 V cm-1 Oe-1. For thinner Kapton and epoxy layers, the values of ?ME became higher. This model presents theoretical guidelines by which one can achieve higher values of ?ME.

  6. Failure modes of vacuum plasma spray tungsten coating created on carbon fibre composites under thermal loads

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Bekris, N.; Coad, J. P.; Grisolia, C.; Linke, J.; Maier, H.; Matthews, G. F.; Philipps, V.; Wessel, E.

    2009-07-01

    Vacuum plasma spray tungsten (VPS-W) coating created on a carbon fibre reinforced composite (CFC) was tested under two thermal load schemes in the electron beam facility to examine the operation limits and failure modes. In cyclic ELM-like short transient thermal loads, the VPS-W coating was destroyed sub-layer by sub-layer at 0.33 GW/m 2 for 1 ms pulse duration. At longer single pulses, simulating steady-state thermal loads, the coating was destroyed at surface temperatures above 2700 C by melting of the rhenium containing multilayer at the interface between VPS-W and CFC. The operation limits and failure modes of the VPS-W coating in the thermal load schemes are discussed in detail.

  7. 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; Garca-Ruiz, Mximo; Jimnez-Rodrguez, Jos 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

  8. 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.

  9. 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

  10. Nondestructive identification of engineering properties of metal fibre composites

    NASA Astrophysics Data System (ADS)

    Vala, J.; Hork, M.

    2012-09-01

    Macroscopic homogeneity of metal fibre composites, namely those used for building structures, characterized by constant volume fraction of randomly oriented fibre particles, as well as their isotropy, or, alternatively, prescribed orientation of fibres, determines their mechanical, thermal, etc. properties, consequently their long-time behaviour, reliability and range of user applications. Destructive tests are available under laboratory conditions, but frequently impossible in situ, thus the development of reliable nondestructive approaches is required. This paper presents the physical and mathematical background of two classes of such tests, based i) on the planar radiographic images, analyzed with help of the fast Fourier transform, ii) on the magnetic properties of materials, using the Hall effect and properties of solutions of the Laplace equation. Practical results with fibre concrete samples from Brno University of Technology demonstrate the advantages and drawbacks of both approaches and sketch the possibilities of their future generalization.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Coherent Fibre-Bundle Wavefront Sensor - Oral Paper

    NASA Astrophysics Data System (ADS)

    Vohnsen, B.; Iglesias, I.; Artal, P.

    2008-01-01

    A novel wavefront sensor based on a coherent bundle of single-mode fibres is proposed. Such a sensor holds potential for fast registration and does not require a collinear design. The pros and cons of it, as compared to more conventional sensor designs, is examined in order to evaluate its potential and to identify possible areas of application. The concept is illustrated with wavefront measurements that have been performed for simplicity with an individual fibre scanned across the wavefront of interest. We find that the tiny core of current single-mode fibres is ill suited for general purpose wavefront sensing, but future developments may make a fibre-based design a liable alternative to current techniques.

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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)-?-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)-?-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

  5. 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

  6. 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)

  7. Casting preforms for microstructured polymer optical fibre fabrication

    NASA Astrophysics Data System (ADS)

    Zhang, Yani; Li, Kang; Wang, Lili; Ren, Liyong; Zhao, Wei; Miao, Runcai; Large, Maryanne C. J.; van Eijkelenborg, Martijn A.

    2006-06-01

    A monolithic structured polymer preform was formed by in-situ chemical polymerization of high-purity MMA monomer in a home-made mould. The conditions for fabrication of the preforms were optimized and the preform was drawn to microstructured polymer optical fibre. The optical properties of the resultant elliptical-core fibre were measured. This technique provides advantages over alternative preform fabrication methods such as drilling and capillary stacking, which are less suitable for mass production.

  8. 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)

  9. Global chromatin fibre compaction in response to DNA damage

    PubMed Central

    Hamilton, Charlotte; Hayward, Richard L.; Gilbert, Nick

    2011-01-01

    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 (?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 ?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. PMID:22020103

  10. Light distribution in the fibre with a spherical output surface

    NASA Astrophysics Data System (ADS)

    Dorosz, Jan; Dybczynski, Wladyslaw

    2006-03-01

    We have discussed transmission of the luminous flux through the optical fibre with a flat input surface and a spherical output surface. In this discussion we have considered the basic losses of the luminous flux.: Fresnel reflections, absorption of the core material on the optical path, and imperfections of the internal reflection. The curves of luminous intensity of the solids of light distribution in the optical fibre mating with a halogen bulb have been given as well.

  11. Combining regenerated gratings and optical fibre Fabry-Prot cavities for dual sensing of ultra-high temperature and strain

    NASA Astrophysics Data System (ADS)

    Cook, Kevin; Ran, Zengling; Gong, Yuan; Rao, Yunjiang; Canning, John

    2015-07-01

    The successful regeneration of fibre Bragg gratings (FBGs) inscribed in an inline fibre etalon is demonstrated. The etalon is formed by UV-micromaching of the fibre end-face to form a cylindrical hole, the fibre is then fusion spliced to seal the cavity. Such a fibre device has excellent potential for the simultaneous measurement of ultra-high temperatures and strain.

  12. 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)

  13. Preparation of reactive fibre interfaces using multifunctional cellulose derivatives.

    PubMed

    Vega, Beatriz; Wondraczek, Holger; Bretschneider, Leonore; Nreoja, 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

  14. 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

  15. 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

  16. Advances in fibre-optic sensing in medicine and biology

    NASA Astrophysics Data System (ADS)

    Rolfe, Peter; Scopesi, Fabio; Serra, Giovanni

    2007-06-01

    This paper presents a review of medical and biological applications of optical fibres, which span a wide range from light-pipes and pressure or displacement sensors through to complex chemical sensors. Coherent fibre bundles are needed for endoscopic imaging whilst single fibres may be used in both near infrared tomography and optical coherence tomography. Delivery of light to tissues, for example to activate targeted chemo-therapeutic agents (PDT), is also achieved conveniently with fibres. Chemical sensing can simply be achieved by transporting light to and from a measurement site with a plain fibre light guide for spectrophotometric or fluorimetry analysis. A further family of fibre-optic chemical sensors has either surface attached molecular recognition sites or a reaction chamber for achieving specific molecular detection. These chemical sensors may be based on the principles of surface plasmon resonance, interferometry, spectrophotometry or fluorimetry. Biological recognition with enzymes or antigen-antibody binding are used to achieve high specificity. The range of potential target molecules has increased rapidly over recent years from simple gases and ions through to large molecules such as DNA.

  17. 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.

  18. 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.

  19. 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

  20. 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