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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, 3–10) 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

  2. Registration of adaptive optics corrected retinal nerve fiber layer (RNFL) images

    PubMed Central

    Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

    2014-01-01

    Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM). PMID:24940551

  3. Onset and Progression of Peripapillary Retinal Nerve Fiber Layer (RNFL) Retardance Changes Occur Earlier Than RNFL Thickness Changes in Experimental Glaucoma

    PubMed Central

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

    2013-01-01

    Purpose. Longitudinal measurements of peripapillary RNFL thickness and retardance were compared in terms of time to reach onset of damage and time to reach a specific progression endpoint. Methods. A total of 41 rhesus macaques with unilateral experimental glaucoma (EG) each had three or more weekly baseline measurements in both eyes of peripapillary RNFL thickness (RNFLT) and retardance. Laser photocoagulation was then applied to the trabecular meshwork of one eye to induce chronic elevation of intraocular pressure and weekly imaging continued. Pairwise differences between baseline observations were sampled by bootstrapping to determine the 95% confidence limits of each measurement's repeatability. The first two sequential measurements below the lower confidence limit defined the endpoint for each parameter. Segmented linear and exponential decay functions were fit to each RNFL-versus-time series to determine the time to damage onset. Results. In all, 29 (71%) of the EG eyes reached endpoint by RNFL retardance and 25 (61%) reached endpoint by RNFLT. In total, 33 (80%) reached endpoint by at least one of the RNFL parameters and 21 (51%) reached endpoint by both RNFL parameters. Of the 33 EG eyes reaching any endpoint, a larger proportion reached endpoint first by retardance (n = 26, 79%) than did by RNFLT (n = 7, 21%; P = 0.002). Survival analysis indicated a shorter time to reach endpoint by retardance than by RNFLT (P < 0.001). Of the 21 EG eyes that reached endpoint by both measures, the median duration to endpoint was 120 days for retardance and 223 days for RNFLT (P = 0.003, Wilcoxon test). The time to onset was faster for retardance than that for RNFLT based on either segmented fits (by 31 days; P = 0.008, average R2 = 0.89) or exponential fits (by 102 days; P = 0.01, average R2 = 0.89). Conclusions. The onset of progressive loss of RNFL retardance occurs earlier than the onset of RNFL thinning. Endpoints of progressive loss from baseline also occurred more

  4. Localised wedge shaped defects of the retinal nerve fibre layer in glaucoma.

    PubMed

    Jonas, J B; Schiro, D

    1994-04-01

    Glaucoma can be associated with a diffuse or localised loss of the retinal nerve fibre layer (RNFL). This study evaluated the wedge shaped localised RNFL defects. Red free wide angle RNFL photographs of 421 patients with glaucoma and 193 normal subjects were examined. Localised RNFL defects were described for one eye of the normal group and for 20% of the patients with glaucoma. They were usually located in the inferior temporal and superior temporal fundus regions. Within the glaucoma group, localised RNFL defects occurred most often (p < 0.05) in normal pressure glaucoma, followed by primary open angle glaucoma, and finally secondary open angle glaucoma. They were positively associated with disc haemorrhages. The localised RNFL defects had a high specificity to indicate optic nerve damage. The nerve fibre layer defects occurring more likely in mild rather than advanced glaucoma, they were helpful in the diagnosis of early glaucoma. The association between localised RNFL defects and disc haemorrhages and the varying frequency of localised RNFL defects in different types of glaucoma may be important diagnostically and pathogenetically. PMID:8199115

  5. Prospective Study on Retinal Nerve Fibre Layer Thickness Changes in Isolated Unilateral Retrobulbar Optic Neuritis

    PubMed Central

    Yau, Gordon S. K.; Lee, Jacky W. Y.; Lau, Patrick P. K.; Tam, Victor T. Y.; Wong, Winnie W. Y.; Yuen, Can Y. F.

    2013-01-01

    Purpose. To investigate the retinal nerve fibre layer (RNFL) thickness after unilateral acute optic neuritis using optical coherence tomography (OCT). Patients and Methods. This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis. RNFL thickness and visual acuity (VA) of the attack and normal fellow eye were measured at presentation and 3 months in both the treatment and nontreatment groups. Results. 11 subjects received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eye (P ≥ 0.4). At 3 months, the attack eye had a thinner temporal (P = 0.02) and average (P = 0.05) RNFL compared to the fellow eye. At 3 months, the attack eye had significant RNFL thinning in the 4 quadrants and average thickness (P ≤ 0.0002) compared to baseline. The RNFL thickness between the treatment and nontreatment groups was similar at baseline and 3 months (P ≥ 0.1). Treatment offered better VA at 3 months (0.1 ± 0.2 versus 0.3 ± 0.2 LogMAR, P = 0.04). Conclusion. Generalized RNFL thinning occurred at 3 months after a first episode of acute optic neuritis most significantly in the temporal quadrant and average thickness. Visual improvement with treatment was independent of RNFL thickness. PMID:24459442

  6. Optical Coherence Tomography Assisted Retinal Nerve Fibre Layer Thickness Profile in High Myopia

    PubMed Central

    Malakar, Mousumi; Askari, Syed Nasir; Ashraf, Humayun; Ahuja, Anupam; Asghar, Adil

    2015-01-01

    Introduction: To evaluate the association of high myopia with retinal nerve fibre layer (RNFL) thickness by Fourier domain optical coherence tomography (FD OCT). Materials and Methods: Fifty highly myopic eyes (25 patients) and forty emmetropic eyes (20 Normal subject) were randomly selected after excluding concomitant ophthalmic disorder and RNFL thickness measured using the Fourier domain optical coherence tomography (FD OCT). Results: The overall mean RNFL thickness in the myopic groups and control were 87.89 μm and 111.64 μm respectively. The mean retinal nerve fibre thickness was significantly less in myopic eyes as compared to control group (p =0.0001). Retinal nerve fibre layer thickness shows topographic double hump pattern in both the groups (myopes and emmetropes). Conclusion: Retinal nerve fibre thickness was significantly less in myopic eyes as compared to emmetropic eyes. The retinal nerve fibre layer thinning in high myopes may be confused with open angle glaucoma, a disease also prevalent in high myopes. There is therefore a need to have retinal nerve fibre layer thickness normogram for high myopes of a given population group to avoid wrong interpretation. PMID:25859476

  7. The Humphrey optical coherence tomography scanner: quantitative analysis and reproducibility study of the normal human retinal nerve fibre layer

    PubMed Central

    Jones, A.; Sheen, N.; North, R.; Morgan, J.

    2001-01-01

    BACKGROUND/AIMS—To determine the reproducibility of the Humphrey optical coherence tomography scanner (OCT), software version 5.0, for measurement of retinal nerve fibre layer (RNFL) thickness in normal subjects and to compare OCT measurements with published histological thickness of the human RNFL.
METHODS—Three independent measurements were obtained at each session for one eye from 15 normal subjects with a mean age of 30.8 (SD 10.9) years. Scans were taken in the peripapillary retina using the default setting (1.74 mm radius from centre of the optic disc) and were repeated 1 week later. Additional scans were obtained at the optic nerve head (ONH) margin overlying the scleral rim, for comparison with available histological data on the human RNFL.
RESULTS—For the 1.74 mm circular scan, the mean coefficient of variation (COV) for the global RNFL thickness measurement was 5% (SD 3%). This increased to 8% (3%) for quadrant measurements and to 9% (3%) with further subdivision into 12 segments. Significant differences (p<0.05) between sessions were only found when the data were divided into segments. The mean RNFL thickness for the 1.74 mm scan was 127.87 (9.81) µm. The RNFL was maximal at the superior disc pole, 161.44 µm (14.8), and minimal at the temporal pole, 83.1 (12.8) µm. Peak thickness values occurred superior temporal and inferior temporal to the vertical axis. RNFL thickness for every sector of the disc was greatest at the margin of the optic disc (mean 185.79 µm; SD 32.61). Although the variation in RNFL thickness around the disc follows published histology data, the OCT underestimates RNFL thickness by an average of 37% (SD 11; range 21-48%).
CONCLUSION—The OCT provides reproducible measurement of the retinal structures that are consistent with the properties of the RNFL. However, comparison with available studies of RNFL thickness in the human suggests that in its present form, the OCT underestimates RNFL thickness. Further

  8. 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.

  9. Retinal Nerve Fibre Layer Thinning in Patients with Clinically Isolated Optic Neuritis and Early Treatment with Interferon-Beta

    PubMed Central

    Sühs, Kurt-Wolfram; Hein, Katharina; Pehlke, Jens R.; Käsmann-Kellner, Barbara; Diem, Ricarda

    2012-01-01

    Background Optic neuritis is associated with neurodegeneration leading to chronic impairment of visual functions. Objective This study investigated whether early treatment with interferon beta (IFN-β) slows retinal nerve fibre layer (RNFL) thinning in clinically isolated optic neuritis. Methods Twenty patients with optic neuritis and visual acuity decreased to ≤0.5 (decimal system) were included into this prospective, open-label, parallel group 4-month observation. After methylprednisolone pulse therapy, 10 patients received IFN-β from week 2 onwards. This group was compared to 10 patients free of any disease modifying treatment (DMT). The parameter of interest was change in RNFL thickness assessed at baseline and at weeks 4, 8, and 16. Changes in visual acuity, visual field, and visual evoked potentials (VEPs) served as additional outcome parameters. Results RNFL thinning did not differ between the groups with a mean reduction of 9.80±2.80 µm in IFN-β-treated patients (±SD) vs. 12.44±5.79 µm in patients who did not receive DMT (baseline non-affected eye minus affected eye at week 16; p = 0.67, t-test, 95% confidence interval: −15.77 to 10.48). Parameters of visual function did not show any differences between the groups either. Conclusions In isolated optic neuritis, early IFN-β treatment did not influence RNFL thinning nor had it any effect on recovery of visual functions. PMID:23272128

  10. 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 μm. 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

  11. 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.

  12. Compensation for retinal vessel density reduces the variation of circumpapillary RNFL in healthy subjects.

    PubMed

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

    2015-01-01

    This work intends to assess circumpapillary retinal vessel density (RVD) at a 3.46 mm diameter circle and correlate it with circumpapillary retinal nerve fiber layer (RNFL) thickness measured with Fourier-Domain Optical Coherence Tomography. Furthermore, it aims to evaluate the reduction of intersubject variability of RNFL when considering RVD as a source of information for RNFL distribution. For that, 106 healthy subjects underwent circumpapillary RNFL measurement. Using the scanning laser ophthalmoscope fundus image, thickness and position of retinal vessels were assessed and integrated in a 256-sector RVD profile. The relationship between local RVD value and local RNFL thickness was modeled by linear regression. RNFL was then compensated for RVD variation by regression formulas. A strong statistically significant intrasubject correlation was found for all subjects between RVD and RNFL profiles (mean R = 0.769). In the intersubject regression analysis, 247 of 256 RNFL sectors showed a statistically significant positive correlation with RVD (mean R = 0.423). RVD compensation of RNFL resulted in a relative reduction of up to 20% of the intersubject variance. In conclusion, RVD in a 3.46 mm circle has a clinically relevant influence on the RNFL distribution. RVD may be used to develop more individualized normative values for RNFL measurement, which might improve early diagnosis of glaucoma. PMID:25786232

  13. 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

  14. Comparison of event-based analysis of glaucoma progression assessed subjectively on visual fields and retinal nerve fibre layer attenuation measured by optical coherence tomography.

    PubMed

    Kaushik, Sushmita; Mulkutkar, Samyak; Pandav, Surinder Singh; Verma, Neelam; Gupta, Amod

    2015-02-01

    The purpose is to study the ability of an event-based analysis of retinal nerve fibre layer (RNFL) attenuation measured by Stratus(®) optical coherence tomography (OCT) and to detect progression across the spectrum of glaucoma. Adult glaucoma suspects, ocular hypertensives and glaucoma patients who had undergone baseline RNFL thickness measurement on Stratus OCT and reliable automated visual field examination by Humphrey's visual field analyser prior to March 2007 and had 5-year follow-up data were recruited. Progression on OCT was defined by two criteria: decrease in average RNFL thickness from baseline by at least 10 and 20 µ. Visual field progression was defined by the modified Hodapp-Parrish-Anderson criteria. Absolute and percentage change in RNFL thickness from baseline was compared in progressors and non-progressors on visual fields. Concordance between structural and functional progression was analysed. 318 eyes of 162 patients were analysed. 35 eyes (11 %) progressed by visual fields, 8 (2.5 %) progressed using the 20 µ loss criterion, while 30 eyes (9.4 %) progressed using the 10 µ loss criterion. In glaucoma suspects, mean absolute RNFL attenuation was 8.6 µ (12.1 % of baseline) in those who progressed to glaucoma by visual fields. OCT was more useful to detect progression in early glaucoma, but performed poorly in advanced glaucoma. The 10 µ criterion appears to be closer to visual field progression. However, the ability to detect progression varies considerably between functional and structural tools depending upon the severity of the disease. PMID:25502985

  15. Lack of Correlation Between Diabetic Macular Edema and Thickness of the Peripapillary Retinal Nerve Fibre Layer

    PubMed Central

    Alkuraya, Hisham S.; Al-Gehedan, Saeed M.; Alsharif, Abdulrahman M.; Alasbali, Tariq; Lotfy, Nancy M.; Khandekar, Rajiv

    2016-01-01

    Introduction: We compared the thickness of the peripapillary retinal nerve fiber layer (RNFL) in patients with diabetic macular edema (DME) and/against the thickness in the normal population. Methods: This cross-sectional study compared the RNFL thickness in patients with DME (DME group) using optical coherence tomography (OCT) to a comparable group of healthy (nondiabetic) patients (control group). Measurements were performed in different/the four peripapillary quadrants and in the macula region for the fovea, parafoveal, and perifoveal areas. The mean RNFL thickness was compared between both groups. Results: There were fifty eyes of fifty nonglaucomatous diabetic patients with DME (29 with nonproliferative diabetic retinopathy [PDR] and 21 with PDR), and fifty eyes in the control group. The macular regions were significantly thicker in the DME group compared to the control group. The central foveal thickness was 149 μ thicker in eyes with DME compared to the control group (P < 0.001). The difference in total RNFL thickness between groups was not significant (4.4 μ [95% confidence interval: −3.1 to +12]). The between-group differences in peripapillary RNFL thickness by age group, glycemic control, history of intravitreal treatments, and refractive errors were not statistically significant (P > 0.05, all comparisons). Conclusion: Peripapillary RNFL thickness measurements were not significantly influenced by DME. Hence, OCT parameters could be used to monitor/early detect glaucomatous eyes even in the presence of DME. PMID:27555707

  16. 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).

  17. Study of Retinal Nerve Fibre Layer Thickness in Patients with Diabetes Mellitus Using Fourier Domain Optical Coherence Tomography

    PubMed Central

    Sah, Sonal; Gupta, Neeti

    2016-01-01

    Introduction Diabetic retina undergoes degenerative changes in retinal nerve fiber layer (RNFL) in addition to vascular changes. Loss of RNFL with changes in inner retina and their association with metabolic control have been studied with varied results in diabetic patients. Aim To compare the RNFL thickness between diabetic patients and age matched healthy controls and to correlate the thickness to metabolic control. Materials and Methods One hundred and sixty five patients were enrolled in the study out of which 50 served as controls, 58 patients were diabetic without retinopathy and 57 patients had diabetic retinopathy. Both eyes of all patients underwent optical coherence tomography scans for RNFL and ganglion cell complex. Foveal and parafoveal thickness were also measured. All the parameters were compared to patient’s metabolic control. Results RNFL thinning was observed in superotemporal (p-value = 0.001) and upper nasal sectors (p-value = 0.031) around the optic disc in eyes with diabetic retinopathy. Ganglion cell complex also showed statistically significant thinning in diabetic patients. Creatinine levels showed a weak negative correlation to the RNFL. Conclusion This study positively concluded that neurodegeneration in an early component of diabetic retinopathy.

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

    PubMed Central

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

    2005-01-01

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

  19. 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

  20. 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 30–2 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

  1. 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

  2. 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).

  3. 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

  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. Physico-chemical properties of organically modified silicates' sol-gel layers for optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Chodkowska, Eliza; Rayss, Jan

    2006-10-01

    The paper concerns the investigation of modified silica gel materials applied in optical fibre sensors. These materials are products of a sol-gel process in which three kinds of alkoxysilanes undergo hydrolysis and condensation and may play a role of the matrices containing transducer's molecules in the active layer of the sensor. In the experiment presented below three different compositions comprising tetraethoxysilane (TEOS), methyltriethoxysilane (MTES) and phenyltriethoxysilane (PhTES) were used. The alkoxysilanes underwent hydrolysis and condensation and the obtained gels were investigated in order to determine their texture, strucuture, composition and chemical properties as far as the dependence of those characteristics on the hydrolysis time and the molar ratio of the ingredients in the initial sols. The methods employed in the experiment were: Atomic Force Microscopy (AFM) which delivered vital information about the gels' textures, contact angles' and surface charge's measurements serving to estimate chemical properties of the gels' surfaces, Nuclear Magnetic Resonance (NMR) which helped to evaluate the hydrolysis' rate and porosimetric measurements enabling a determination of BET surface area and average diametres of the pores. The results may occur important for improving the construction of optical fibre sensors in which organically modified silicates (ORMOSILs)-TEOS layes are used.

  6. 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

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

    PubMed

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

    2015-12-01

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

  8. Advanced fibre optical scanning in thin-layer chromatography for drug identification.

    PubMed

    Ahrens, Björn; Blankenhorn, Dirk; Spangenberg, Bernd

    2002-05-25

    A systematic toxicological analysis procedure using high-performance thin layer chromatography in combination with fibre optical scanning densitometry for identification of drugs in biological samples is presented. Two examples illustrate the practicability of the technique. First, the identification of a multiple intake of analgesics: codeine, propyphenazone, tramadol, flupirtine and lidocaine, and second, the detection of the sedative diphenhydramine. In both cases, authentic urine specimens were used. The identifications were carried out by an automatic measurement and computer-based comparison of in situ UV spectra with data from a compiled library of reference spectra using the cross-correlation function. The technique allowed a parallel recording of chromatograms and in situ UV spectra in the range of 197-612 nm. Unlike the conventional densitometry, a dependency of UV spectra by concentration of substance in a range of 250-1000 ng/spot was not observed. PMID:12016011

  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

    2016-02-14

    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. [The retinal nerve fiber layer in normal and glaucoma eyes].

    PubMed

    Jonas, J B; Schiro, D; Naumann, G O

    1993-12-01

    Glaucoma leads to changes of the retinal nerve fiber layer (RNFL). This study was performed to evaluate glaucomatous alterations of the RNFL and to correlate them with other parameters of glaucomatous optic nerve damage. The study included red-free wide-angle fundus photographs of the RNFL of 453 normal eyes and 609 eyes with glaucoma. We evaluated the visibility of the RNFL in different fundus regions and the occurrence of localized RNFL defects. In the glaucoma eyes, including those with "early" glaucomatous optic nerve damage, the visibility of RNFL was significantly lower than in the normal eyes. The degree of RNFL visibility correlated with other morphological and perimetric parameters. Localized RNFL defects were detected in 20% of the glaucoma eyes. Their frequency increased significantly (P < 0.01) from an "early" glaucoma stage to a subgroup with medium advanced glaucomatous damage and decreased again to a stage with marked glaucomatous changes. They were significantly more common in eyes with normal pressure glaucoma, followed by eyes with primary open-angle glaucoma and finally eyes with secondary open-angle glaucoma. They were significantly associated with optic disk hemorrhages and notches of the neuroretinal rim. The results indicate that the glaucomatous changes of the RNFL are correlated with the optic disk alterations. This holds true also for eyes with "early" glaucomatous damage. It suggests that during every routine ophthalmoscopy the RNFL should be examined. Localized RNFL defects indicate optic nerve damage with a specificity of more than 90%. The contrast between localized and diffuse RNFL loss, the varying frequency of localized RNFL defects in different types of glaucoma and the association between localized RNFL defects and optic disk hemorrhages are diagnostically and pathogenetically important. PMID:8124022

  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. Reduction in retinal nerve fiber layer thickness in young adults with autism spectrum disorders.

    PubMed

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

    2014-04-01

    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 pathophysiology. All subjects underwent high-resolution spectral domain optical coherence tomography to evaluate RNFL thickness. HFA subjects presented with reduced global RNFL thickness compared both to AS subjects and controls. AS subjects showed a reduced nasal quadrant RNFL thickness compared to controls. Verbal-IQ/performance-IQ discrepancy correlated with RNFL thickness. Our data suggest that RNFL evaluation could help in the development of biological markers of autism pathophysiology. PMID:24014196

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

    PubMed Central

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

    2014-01-01

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

  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

  15. 29Si NMR investigation of ORMOSIL layers used as luminophores' sol-gel matrices in a UV optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Chodkowska, Eliza M.; Rayss, Jan

    2007-07-01

    The paper concerns the results of ORMOSIL layer's applied in an optical fibre ultraviolet sensor Nuclear Magnetic Resonance investigation. The layer which substituted for optical fibre's cladding in device's sensing part acted as a matrix for a coumarin's derivative. The dye is able to convert ultraviolet into visible radiation which could be easily detected. Thanks to the fact that the refractive indices of ORMOSIL layers may be controlled and reach a value characteristic for the fused silica glass a satisfying sensitivity of the device can be achieved. However it may be expected that both the structure and the composition of ORMOSIL matrices could influence the organic dye's behaviour. The aim of the experiment presented in the paper was to prove a relation between the sol's condensation time and a composition of the obtained gel's structure. The obtained NMR spectra gave the evidence of non-condensed -Si-O-C IIH 5(H) moieties existence in the solid gels. Moreover, even a 42-days-long process does not lead to the total condensation of ethoxysilanes' molecules. It is probable that the remaining ethoxy or silanol groups interact with transducer's molecules as well as influence the refractive index of the gel layer.

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

    PubMed Central

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

    2016-01-01

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

  17. 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

    2016-01-01

    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

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

    PubMed Central

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

    2016-01-01

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

  19. 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

  20. Macular Ganglion Cell Inner Plexiform Layer Thickness in Glaucomatous Eyes with Localized Retinal Nerve Fiber Layer Defects

    PubMed Central

    Zhang, Chunwei; Tatham, Andrew J.; Abe, Ricardo Y.; Hammel, Na’ama; Belghith, Akram; Weinreb, Robert N.; Medeiros, Felipe A.; Liebmann, Jeffrey M.; Girkin, Christopher A.; Zangwill, Linda M.

    2016-01-01

    Purpose To investigate macular ganglion cell–inner plexiform layer (mGCIPL) thickness in glaucomatous eyes with visible localized retinal nerve fiber layer (RNFL) defects on stereophotographs. Methods 112 healthy and 149 glaucomatous eyes from the Diagnostic Innovations in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES) subjects had standard automated perimetry (SAP), optical coherence tomography (OCT) imaging of the macula and optic nerve head, and stereoscopic optic disc photography. Masked observers identified localized RNFL defects by grading of stereophotographs. Result 47 eyes had visible localized RNFL defects on stereophotographs. Eyes with visible localized RNFL defects had significantly thinner mGCIPL thickness compared to healthy eyes (68.3 ± 11.4 μm versus 79.2 ± 6.6 μm respectively, P<0.001) and similar mGCIPL thickness to glaucomatous eyes without localized RNFL defects (68.6 ± 11.2 μm, P = 1.000). The average mGCIPL thickness in eyes with RNFL defects was 14% less than similarly aged healthy controls. For 29 eyes with a visible RNFL defect in just one hemiretina (superior or inferior) mGCIPL was thinnest in the same hemiretina in 26 eyes (90%). Eyes with inferior-temporal RNFL defects also had significantly thinner inferior-temporal mGCIPL (P<0.001) and inferior mGCIPL (P = 0.030) compared to glaucomatous eyes without a visible RNFL defect. Conclusion The current study indicates that presence of a localized RNFL defect is likely to indicate significant macular damage, particularly in the region of the macular that topographically corresponds to the location of the RNFL defect. PMID:27537107

  1. Structural Alterations of Segmented Macular Inner Layers in Aquaporin4-Antibody-Positive Optic Neuritis Patients in a Chinese Population

    PubMed Central

    Peng, Chunxia; Wang, Wei; Xu, Quangang; Zhao, Shuo; Li, Hongyang; Yang, Mo; Cao, Shanshan; Zhou, Huanfen; Wei, Shihui

    2016-01-01

    Objectives This study aimed to analyse the structural injury of the peripapillary retinal nerve fibre layer (pRNFL) and segmented macular layers in optic neuritis (ON) in aquaporin4-antibody (AQP4-Ab) seropositivity(AQP4-Ab-positiveON) patients and in AQP4-Ab seronegativity (AQP4-Ab-negative ON) patients in order to evaluate their correlations with the best-corrected visual acuity (BCVA) and the value of the early diagnosis of neuromyelitis optica (NMO). Design This is a retrospective, cross-sectional and control observational study. Methods In total, 213 ON patients (291 eyes) and 50 healthy controls (HC) (100 eyes) were recruited in this study. According to a serum AQP4-Ab assay, 98 ON patients (132 eyes) were grouped as AQP4-Ab-positive ON and 115 ON patients (159 eyes) were grouped as AQP4-Ab-negative ON cohorts. All subjects underwent scanning with spectralis optical coherence tomography (OCT) and BCVA tests. pRNFL and segmented macular layer measurements were analysed. Results The pRNFL thickness in AQP4-Ab-positive ON eyes showed a more serious loss during 0–2 months (-27.61μm versus -14.47 μm) and ≥6 months (-57.91μm versus -47.19μm) when compared with AQP4-Ab-negative ON eyes. AQP4-Ab-positive ON preferentially damaged the nasal lateral pRNFL. The alterations in the macular ganglion cell layer plus the inner plexiform layer (GCIP) in AQP4-Ab-positive ON eyes were similar to those in AQP4-Ab-negative ON eyes. AQP4-Ab-positive ON eyes had entirely different injury patterns in the inner nuclear layer (INL) compared with AQP4-Ab-negative ON eyes during the first 6 months after the initial ON attack. These differences were as follows: the INL volume of AQP4-Ab-positive ON eyes had a gradual growing trend compared with AQP4-Ab-negative ON eyes, and it increased rapidly during 0–2 months, reached its peak during 2–4 months, and then decreased gradually. The pRNFL and GCIP in AQP4-Ab-positive ON eyes had positive correlations with BCVA. When the pRNFL

  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. Interface reactions and control of diffusion at the interface between SiC fibres and layer of deposited Fe 9Cr base alloy

    NASA Astrophysics Data System (ADS)

    Levchuk, S.; Lindig, S.; Brendel, A.; Bolt, H.

    2007-08-01

    The ferromagnetic 9Cr steel EUROFER 97 is considered as a structural material for the first wall of future fusion reactors. To solve a problem of limitation of the maximum operation temperature of 550 °C for EUROFER 97, a new metal matrix composite SiC/EUROFER 97 is proposed. To create a thermally stable interface between the SiC fibres and the steel matrix, the following interlayers were tested as a diffusion barrier: Cr, Re, W and Re/W. Samples with these interlayers were investigated before and after annealing at 750 °C which is supposed to be the operation temperature of the composite material. To simplify examination of the coatings using available analysis methods (SEM, IBA and XRD), the fibre/steel system was approximated by planar samples with identical layer structure. The experiments with both SiC fibres and planar substrates revealed W to be an efficient diffusion barrier.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

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

    PubMed Central

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

    2016-01-01

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

  8. Retinal nerve fiber layer thickness in normal Indian pediatric population measured with optical coherence tomography.

    PubMed

    Pawar, Neelam; Maheshwari, Devendra; Ravindran, Meenakshi; Ramakrishnan, Renagappa

    2013-11-11

    Purpose: To measure the peripapillary retinal nerve fiber layer (RNFL) thickness in normal Indian pediatric population. Subjects and Methods: 120 normal Indian children ages 5-17 years presenting to the Pediatric Clinic were included in this observational cross-sectional study. RNFL thickness was measured with stratus optical coherence tomography (OCT). Children with strabismus or amblyopia, with neurological, metabolic, vascular, or other disorders and those with abnormal optic discs were excluded. One eye of each subject was randomly selected for statistical analysis. The effect of age, refraction and gender on RNFL thickness was investigated statistically. Result: OCT measurements were obtained in 120 of 130 (92.3%) subjects. Mean age was 10.8 ± 3.24 years (range 5-17). Average RNFL thickness was (± SD) 106.11 ± 9.5 μm (range 82.26-146.25). The RNFL was thickest inferiorly (134.10 ± 16.16 μm) and superiorly (133.44 ± 15.50 μm), thinner nasally (84.26 ± 16.43 μm), and thinnest temporally (70.72 ± 14.80 μm). In univariate regression analysis, age had no statistical significant effect on RNFL thickness (P = 0.7249) and refraction had a significant effect on RNFL thickness (P = 0.0008). Conclusion: OCT can be used to measure RNFL thickness in children. Refraction had an effect on RNFL thickness. In normal children, variation in RNFL thickness is large. The normative data provided by this study may assist in identifying changes in RNFL thickness in Indian children. PMID:24212231

  9. Correlation of Retinal Nerve Fiber Layer Thickness and Axial Length on Fourier Domain Optical Coherence Tomography

    PubMed Central

    Dhasmana, Renu; Nagpal, R.C.

    2016-01-01

    Introduction The assessment of the peripapillary Retinal Nerve Fiber Layer (RNFL) thickness has been an important tool for evaluating and diagnosing glaucoma and its progression. Literature suggests that myopic eyes are at an increased risk for developing glaucoma. This study gives an insight into the relationship of RNFL thickness to the axial length in normal population. Aim To correlate the RNFL thickness and the axial length in normal individuals with Fourier domain Optical Coherence Tomography (OCT). Materials and Methods In the current study, 298 eyes of 149 normal individuals (10 years or older) with or without refractive error were recruited. The RNFL thickness was measured using Optovue (RTVue) three-dimensional Fourier domain OCT. Results We observed an inverse relationship between average RNFL thickness and increasing axial length(p=0.003). Maximum RNFL thickness was seen in the Infero-Temporal (IT) quadrant and minimum in the Supero-Nasal (SN) quadrant. RNFL thickness did not show any tendency to decline with age using the Pearsons correlation (r=0.07). Females had an increased RNFL thickness in the Supero-Temporal (ST) and Infero-Nasal (IN) quadrant (p-value 0.046 and 0.02) in comparison to males. There was a statistically significant thinning in Ganglion Cell Complex (GCC) with increasing axial length (p-value 0.000) Conclusion The current study suggests that the average RNFL thickness does not decrease with age. The RNFL and GCC thickness shows an inverse correlation with axial length of the eyeball hence observations have to be carefully interpreted in myopic eyes. Clinicians need to keep the anatomical variations in RNFL for better patient management. PMID:27190850

  10. 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.

  11. 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)

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

    PubMed Central

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

    2015-01-01

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

  13. 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

  14. Is it a modacrylic fibre?

    PubMed

    Grieve, M C; Griffin, R M

    1999-01-01

    This study describes the characteristics of modacrylic fibres and includes over 80 samples (previous and current) representing 15 trade names. Fibre morphology was examined using brightfield microscopy. Signs of elongation were determined using polarised light microscopy. Fibre cross sections were also examined. The generic class of fibre was divided into sub groups using polymer composition as determined by FTIR-microscopy. Microscopically, some modacrylic fibres cannot be distinguished from acrylic fibres. Others display unusual optical and morphological features which are a strong indication of their generic class. The infrared spectra provide information about the co-monomer, termonomers added to produced dye sites, the presence of solvent residue, dyes, and additives, e.g. flame retardant material. The infrared spectra should always be recorded before and after any thin layer chromatographic examination of the dye, otherwise peaks attributable to dyes, which may be a valuable comparative feature in casework will be lost. PMID:10795403

  15. Effects of hemodialysis on macular and retinal nerve fiber layer thicknesses in non-diabetic patients with end stage renal failure

    PubMed Central

    Atilgan, Cemile U.; Guven, Dilek; Akarsu, Ozge P.; Sakaci, Tamer; Sendul, Selam Y.; Baydar, Yasemin; Atilgan, Kadir G.; Turker, Ibrahim C.

    2016-01-01

    Objectives: To evaluate the thicknesses of retinal nerve fiber layer (RNFL) and macula by fourier-domain (FD) optical coherence tomography (OCT) in non-diabetic patients with end-stage-renal-failure (ESRF) undergoing hemodialysis (HD). Methods: This is a prospective and observational study. Both eyes of 20 patients receiving HD (group 1) and 34 control patients (group 2) were evaluated by FD-OCT. Macular and RNFL thicknesses were compared between groups and their correlation with age, duration of HD, and gender were examined. In group 1, macular and RNFL thicknesses were evaluated before and shortly after HD in the first day, first and sixth months. Results: In group 1, pre-HD temporal, inferior, average RNFL thicknesses were thinner than group 2. This thinning did not correlate with duration of HD, age and gender. Pre-HD macular thicknesses were thinner than group 2. These thinnings did not correlate with age, but the thinnings at superior, nasal and average thickness correlated negatively with duration of HD. Nasal, temporal, and average macular thicknesses were thinner in female patients. The thickenings of RNFL and macula that were observed in the after HD first day and first month did not showed consistency in the sixth month except superior quadrant RNFL. Conclusion: Macular and RNFL thicknesses of patients receiving HD were less than the normal population. Age has no effect on these thinnings. The duration of HD affects more than gender. Hemodialysis session causes a consistent increase in superior quadrant RNFL. PMID:27279510

  16. 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 (59±21%) was significantly higher than in sectors without a visible RNFL defect in glaucomatous eyes (15±29%, P<0.001) and higher than in healthy eyes (1±13%, 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

  17. Wavelength-Dependent Change of Retinal Nerve Fiber Layer Reflectance in Glaucomatous Retinas

    PubMed Central

    Huang, Xiang-Run; Zhou, Ye; Knighton, Robert W.; Kong, Wei; Feuer, William J.

    2012-01-01

    Purpose. Retinal nerve fiber layer (RNFL) reflectance is often used in optical methods for RNFL assessment in clinical diagnosis of glaucoma, yet little is known about the reflectance property of the RNFL under the development of glaucoma. This study measured the changes in RNFL reflectance spectra that occurred in retinal nerve fiber bundles with different degrees of glaucomatous damage. Methods. A rat model of glaucoma with laser photocoagulation of trabecular meshwork was used. Reflectance of the RNFL in an isolated retina was measured at wavelengths of 400–830 nm. Cytostructural distribution of the bundles measured optically was evaluated by confocal imaging of immunohistochemistry staining of cytoskeletal components, F-actin, microtubules, and neurofilaments. RNFL reflectance spectra were studied in bundles with normal-looking appearance, early F-actin distortion, and apparent damage of all cytoskeletal components. Changes of RNFL reflectance spectra were studied at different radii (0.22, 0.33, and 0.44 mm) from the optic nerve head (ONH). Results. Bundles in 30 control retinas and 41 glaucomatous retinas were examined. In normal retinas, reflectance spectra were similar along the same bundles. In glaucomatous retinas, reflectance spectra changed along bundles with the spectra becoming flatter as bundle areas approached the ONH. Conclusions. Elevation of intraocular pressure (IOP) causes nonuniform changes in RNFL reflectance across wavelengths. Changes of reflectance spectra occur early in bundles near the ONH and prior to apparent cytoskeletal distortion. Using the ratio of RNFL reflectance measured at different wavelengths can provide early and sensitive detection of glaucomatous damage. PMID:22836775

  18. Fibre typing of intrafusal fibres.

    PubMed

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

    2015-08-01

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

  19. 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

  20. Evaluation of Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer in Primary Craniopharyngioma by Fourier-Domain Optical Coherence Tomography

    PubMed Central

    Yang, Liu; Qu, Yuanzhen; Lu, Wen; Liu, Fengjun

    2016-01-01

    Background The aim of this study was to compare the differences in macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) in child and adult patients with primary craniopharyngioma by Fourier-domain optical coherence tomography (FD-OCT) and to evaluate their significance in the diagnosis of primary craniopharyngioma. Material/Methods Ninety-six participants were divided into 3 groups: 32 in the child craniopharyngioma group (CCG) and 32 in the adult craniopharyngioma group (ACG) who were treated in Beijing Tiantan Hospital between November 2013 and October 2014, and 32 in the normal group (NG). All subjects were scanned by FD-OCT to map GCC and pRNFL thicknesses. Spearman correlation coefficient was used to assess the correlation between GCC and pRNFL thickness, and pRNFL thickness and optic nerve head (ONH) parameters, including horizontal cup-disc ratio (HCDR), vertical cup-disc ratio (VCDR), optic disc area (ODA), and cup area (CA), respectively. Results The correlation between GCC and pRNFL thickness in the CCG was slightly stronger compared with the ACG. A significant difference in GCC thickness was observed among the CCG, ACG, and NG. Although the pRNFL thickness in both the CCG and ACG was significantly higher than that in NG, no significant difference in pRNFL thickness was detected between the 2 craniopharyngioma groups. The average, superior, and inferior pRNFL thicknesses were negatively correlated with VCDR in the CCG (in double eyes) and ACG (only in left eyes). Conclusions GCC was more sensitive than pRNFL in detecting optic nerve damage in the eyes of craniopharyngioma patients. A thinner pRNFL was especially correlated with VCDR in child craniopharyngioma patients. PMID:27372909

  1. Evaluation of Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer in Primary Craniopharyngioma by Fourier-Domain Optical Coherence Tomography.

    PubMed

    Yang, Liu; Qu, Yuanzhen; Lu, Wen; Liu, Fengjun

    2016-01-01

    BACKGROUND The aim of this study was to compare the differences in macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) in child and adult patients with primary craniopharyngioma by Fourier-domain optical coherence tomography (FD-OCT) and to evaluate their significance in the diagnosis of primary craniopharyngioma. MATERIAL AND METHODS Ninety-six participants were divided into 3 groups: 32 in the child craniopharyngioma group (CCG) and 32 in the adult craniopharyngioma group (ACG) who were treated in Beijing Tiantan Hospital between November 2013 and October 2014, and 32 in the normal group (NG). All subjects were scanned by FD-OCT to map GCC and pRNFL thicknesses. Spearman correlation coefficient was used to assess the correlation between GCC and pRNFL thickness, and pRNFL thickness and optic nerve head (ONH) parameters, including horizontal cup-disc ratio (HCDR), vertical cup-disc ratio (VCDR), optic disc area (ODA), and cup area (CA), respectively. RESULTS The correlation between GCC and pRNFL thickness in the CCG was slightly stronger compared with the ACG. A significant difference in GCC thickness was observed among the CCG, ACG, and NG. Although the pRNFL thickness in both the CCG and ACG was significantly higher than that in NG, no significant difference in pRNFL thickness was detected between the 2 craniopharyngioma groups. The average, superior, and inferior pRNFL thicknesses were negatively correlated with VCDR in the CCG (in double eyes) and ACG (only in left eyes). CONCLUSIONS GCC was more sensitive than pRNFL in detecting optic nerve damage in the eyes of craniopharyngioma patients. A thinner pRNFL was especially correlated with VCDR in child craniopharyngioma patients. PMID:27372909

  2. Effect of change in macular birefringence imaging protocol on retinal nerve fiber layer thickness parameters using GDx VCC in eyes with macular lesions.

    PubMed

    Dada, Tanuj; Tinwala, Sana I; Dave, Vivek; Agarwal, Anand; Sharma, Reetika; Wadhwani, Meenakshi

    2014-08-01

    This study evaluates the effect of two macular birefringence protocols (bow-tie retardation and irregular macular scan) using GDx VCC on the retinal nerve fiber layer (RNFL) thickness parameters in normal eyes and eyes with macular lesions. In eyes with macular lesions, the standard protocol led to significant overestimation of RNFL thickness which was normalized using the irregular macular pattern protocol. In eyes with normal macula, absolute RNFL thickness values were higher in irregular macular pattern protocols with the difference being statistically significant for all parameters except for inferior average thickness. This has implications for monitoring glaucoma patients who develop macular lesions during the course of their follow-up. PMID:24469116

  3. 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

  4. 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

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

    PubMed Central

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

    2014-01-01

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

  6. Diurnal changes in retinal nerve fiber layer thickness with obstructive sleep apnea/hypopnea syndrome

    PubMed Central

    Chirapapaisan, Niphon; Likitgorn, Techawit; Pleumchitchom, Mintra; Sakiyalak, Darin; Banhiran, Wish; Saiman, Manatsawin; Chuenkongkaew, Wanicha

    2016-01-01

    AIM To compare the retinal nerve fiber layer (RNFL) thickness in the morning and evening in Thai patients with varying degrees of obstructive sleep apnea/hypopnea syndrome (OSAHS). METHODS In this cross-sectional study, potential OSAHS patients at Siriraj Hospital underwent polysomnography to determine the severity of OSAHS and an eye examination (including best corrected visual acuity, slit-lamp examination, and Goldmann applanation tonometry). RNFL thickness was recorded once in the morning and once in the evening, using spectral domain optical coherence tomography. Thickness was expressed as an average and given for each quadrant. Patients with ocular or systemic diseases that might affect RNFL thickness were excluded. RESULTS Forty-one eyes of 41 patients were classified into 4 OSAHS groups. The average and mean RNFL thickness in most of the four quadrants of the severe OSAHS group trended toward being less than those in the comparable quadrants of the other groups in both the morning and evening. In the moderate OSAHS group, the average RNFL thickness and temporal and superior quadrant thickness in the morning were significantly higher than in the evening (P=0.01, P=0.01, and P=0.03, respectively). In the severe OSAHS group, the inferior quadrant thickness in the morning was significantly higher than in the evening (P=0.03). CONCLUSION The RNFL thickness in the morning was higher than in the evening in moderate OSAHS. PMID:27500104

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  8. 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

  9. 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

  10. Decreased retinal nerve fiber layer thickness in patients with obstructive sleep apnea syndrome

    PubMed Central

    Sun, Cheng-Lin; Zhou, Li-Xiao; Dang, Yalong; Huo, Yin-Ping; Shi, Lei; Chang, Yong-Jie

    2016-01-01

    Abstract Objective: To investigate the changes of retinal nerve fiber layer (RNFL) thickness in obstructive sleep apnea syndrome (OSAS) patients. Methods: Relevant studies were selected from 3 major literature databases (PubMed, Cochrane Library, and EMBASE) without language restriction. Main inclusion criteria is that a case-control study in which RNFL thickness was measured by a commercial available optical coherence tomography (OCT) in OSAS patients. Meta-analysis was performed using STATA 12.0 software. Efficacy estimates were evaluated by weighted mean difference with corresponding 95% confidence intervals (CIs). Primary outcome evaluations were: the average changes of RNFL thickness in total OSAS patients, subgroup analysis of RNFL thickness changes in patients of different OSAS stages, and subgroup analysis of 4-quadrant RNFL thickness changes in total OSAS patients. Results: Of the initial 327 literatures, 8 case-control studies with 763 eyes of OSA patients and 474 eyes of healthy controls were included (NOS scores ≥6). For the people of total OSAS, there had an average 2.92 μm decreased RNFL thickness compared with controls (95% CI: −4.61 to −1.24, P = 0.001). For subgroup analysis of OSAS in different stages, the average changes of RNFL thickness in mild, moderate, severe, and moderate to severe OSAS were 2.05 (95% CI: −4.40 to 0.30, P = 0.088), 2.32 (95% CI: −5.04 to 0.40, P = 0.094), 4.21 (95% CI: −8.36 to −0.06, P = 0.047), and 4.02 (95% CI: −7.65 to −0.40, P = 0.03), respectively. For subgroup analysis of 4-quadrant, the average changes of RNFL thickness in Superior, Nasal, Inferior, and Temporal quadrant were 2.43 (95% CI: −4.28 to −0.57, P = 0.01), 1.41 (95% CI: −3.33 to 0.51, P = 0.151), 3.75 (95% CI: −6.92 to −0.59, P = 0.02), and 0.98 (95% CI: −2.49 to 0.53, P = 0.203), respectively. Conclusion: Our study suggests that RNFL thickness in OSAS patients is much thinner than

  11. Reproducibility of retinal nerve fiber layer measurements across the glaucoma spectrum using optical coherence tomography

    PubMed Central

    Vazirani, Jayesh; Kaushik, Sushmita; Pandav, Surinder Singh; Gupta, Pramod

    2015-01-01

    Purpose: The purpose was to determine intra-session and inter-session reproducibility of retinal nerve fiber layer (RNFL) thickness measurements with the spectral-domain Cirrus optical coherence tomography (OCT)® (SD-OCT) in normal and glaucomatous eyes, including a subset of advanced glaucoma. Materials and Methods: RNFL measurements of 40 eyes of 40 normal subjects and 40 eyes of 40 glaucomatous patients including 14 with advanced glaucoma were obtained on the Cirrus OCT® (Carl Zeiss Meditec, Dublin, CA, USA) five times on 1-day (intra-session) and on five separate days (inter-session). Intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) values were calculated for mean and quadrant RNFL in each group separately. Reproducibility values were correlated with age and stage of glaucoma. Results: For intra-session reproducibility, the ICC, COV, and TRT values for mean RNFL thickness in normal eyes were 0.993, 1.96%, and 4.02 µm, respectively, 0.996, 2.39%, and 3.84 µm in glaucomatous eyes, and 0.996, 2.41%, and 3.70 µm in advanced glaucoma. The corresponding inter-session values in normal eyes were 0.992, 2.16%, and 4.09 µm, 0.995, 2.62%, and 3.98 µm in glaucoma and 0.990, 2.70%, and 4.16 µm in advanced glaucoma. The mean RNFL thickness measurements were the most reproducible while the temporal quadrant had the lowest reproducibility values in all groups. There was no correlation between reproducibility and age or mean deviation on visual fields. Conclusions: Peripapillary RNFL thickness measurements using Cirrus OCT® demonstrated excellent reproducibility in normal and glaucomatous eyes, including eyes with advanced glaucoma. Mean RNFL thickness measurements appear to be the most reproducible and probably represent the best parameter to use for longitudinal follow-up. PMID:26044467

  12. 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

  13. Diurnal Variations in Intraocular Pressure, Central Corneal Thickness, and Macular and Retinal Nerve Fiber Layer Thickness in Diabetics and Normal Individuals

    PubMed Central

    Sharifipour, Farideh; Farrahi, Fereidoun; Moghaddasi, Alireza; Idani, Aida; Yaseri, Mehdi

    2016-01-01

    Purpose: To evaluate diurnal variations in intraocular pressure (IOP), central corneal thickness (CCT), and macular and retinal nerve fiber layer (RNFL) thickness in diabetic patients and normal individuals. Methods: This study included 11 diabetic patients with macular edema and 11 healthy individuals. IOP, CCT, and macular and RNFL thickness were measured every 3 hours on a single day between 9 AM and 6 PM. Diurnal variations in IOP, CCT, total macular volume (TMV), central macular thickness (CMT), average macular thickness (AMT), and RNFL thickness were measured. Results: None of the parameters showed a significant absolute or relative change over the course of the day. However, the following non-significant changes were observed. In the control group, all parameters demonstrated the highest values at 9 AM. The lowest IOP, TMV and AMT occurred at 12 PM; lowest CCT and RNFL at 6 PM; and the lowest CMT at 3 PM. Diabetic subjects had the highest values of RNFL, CMT and TMV at 9 AM, and that for IOP, CCT and AMT at 6 PM. The lowest RNFL and CMT values occurred at 6 PM; lowest IOP at 12 PM; and the lowest CCT, TMV and AMT were observed at 3 PM. In the diabetic group, TMV, CMT, AMT and CCT were significantly higher and RNFL was significantly lower than the control group at all time points (all P- values < 0.05). Conclusion: While there were slight decreases in IOP, RNFL thickness and CMT during the day, these changes were not significant between 9 AM and 6 PM and probably do not affect the interpretation of measurements. PMID:27195084

  14. Effect of Signal Strength and Improper Alignment on the Variability of Stratus Optical Coherence Tomography Retinal Nerve Fiber Layer Thickness Measurements

    PubMed Central

    VIZZERI, GIANMARCO; BOWD, CHRISTOPHER; MEDEIROS, FELIPE A.; WEINREB, ROBERT N.; ZANGWILL, LINDA M.

    2010-01-01

    PURPOSE To evaluate the effect of signal strength and improper scan alignment on retinal nerve fiber layer (RNFL) thickness measurement variability. DESIGN Retrospective, longitudinal clinical study. METHODS All eyes of healthy subjects with at least 2 fast RNFL scan sessions were selected from the Diagnostic Innovations in Glaucoma Study. The chronological first scan was considered to be the baseline. Absolute differences in signal strength and RNFL thickness measurements between baseline and subsequent scans were calculated. Regression analysis was conducted to assess whether signal strength and scan shifts along the horizontal (nasal–temporal) but not the vertical (superior–inferior) axis affect average RNFL thickness measurements. RESULTS Ninety-four eyes of 94 subjects were included. All eyes were tested twice or more on the same visit, whereas 30 eyes were followed up longitudinally for 32.4 ± 13.3 months (1 scan per annual follow-up). For quadrants, absolute differences from baseline were greater than for average RNFL thickness and were significantly larger for scans acquired on separate visits. Average RNFL thickness increased only when the difference between the nasal and temporal quadrants increased (R2 = 0.16; P < .0001), suggesting it may be affected by horizontal but not vertical scan shifts. Differences in signal strength were associated with differences in average RNFL thickness (R2 = 0.19; P < .0001). CONCLUSIONS Even under optimal testing conditions, scan quality can adversely effect the ability to detect change over time. Therefore, caution is warranted when detecting glaucomatous progression using scan series of different quality. Careful overall assessment of quadrants and average RNFL thickness measurements is suggested to help identify scan misalignment. PMID:19427621

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

    PubMed

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

    2015-01-01

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

  16. 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

  17. Influence of LASIK on scanning laser polarimetric measurement of the retinal nerve fibre layer with fixed angle and customised corneal polarisation compensation

    PubMed Central

    Holló, G; Katsanos, A; Kóthy, P; Kerek, A; Süveges, I

    2003-01-01

    Background/aim: Retinal nerve fibre layer thickness (RNFLT), as measured with scanning laser polarimetry using the fixed angle corneal polarisation compensator (SLP-F), has been found to be reduced after uncomplicated laser assisted in situ keratomileusis (LASIK) compared to the pre-LASIK measurement. Since this virtual RNFLT thinning is attributed to the corneal changes induced by the LASIK, the authors investigated whether customised corneal polarisation compensation (SLP-C), which compensates for the actual corneal polarisation during each measurement, can avoid the LASIK induced, virtual changes of the polarimetric RNFLT values. Methods: Scanning laser polarimetry using both the SLP-F and SLP-C methods (GDx-Access, software version 5.0) was performed on 15 consecutive healthy subjects with no eye disease who underwent LASIK for ametropia correction. The SLP measurements were performed before the surgery, then on day 1 and day 6 after LASIK. Thickness data from images of one randomly selected eye per subject were analysed using the ANOVA and Scheffe multiple comparison tests. Results: Superior maximum, inferior maximum, normalised superior area, and normalised inferior area (SLP parameters representing the RNFLT at the superior and inferior poles of the optic nerve head) remained unchanged with SLP-C (ANOVA, p>0.05) but decreased (superior maximum, normalised superior area, Scheffe test, p<0.05) or tended to decrease (inferior maximum) after LASIK, when measured using SLP-F. In contrast, certain other parameters—namely, superior ratio and inferior ratio (representing the ratios between the superior or the inferior sector and the temporal sector), maximal modulation, and ellipse modulation decreased with SLP-C (Scheffe test, p<0.05), but remained stable with SLP-F (ANOVA, p>0.05) after LASIK. Superior to nasal ratio, symmetry of the superior and inferior RNFLT as well as the parameter showing the probability of having glaucoma (called “the number”) remained

  18. Rare-earth doped fibre optic devices and asymmetric fibre couplers

    NASA Astrophysics Data System (ADS)

    Sanaei, Farin

    The objective of the work reported in this thesis was to improve the quality and range of rare-earth doped fibre optic devices and asymmetric fibre couplers which can be fabricated for all-optical systems. This objective has been realised by improvements to the existing fibre fabrication processes and fused tapered coupler machine and by the generation of new fabrication techniques. An improved Flash-Condensation technique for the deposition of multi-layer highly-doped cladding fibre has been developed and tested. As a result a highly Yb-doped cladding fibre has been fabricated and characterised. It has been shown that up to 7wt% phosphorous pentoxide together with up to 1.4wt% lanthanide oxide can be doped into a multi-layer cladding fibre successfully. As far as it is known, no previous work on doping a thick cladding with Yb 3+ ions has been reported. We have shown experimentally that a 94% efficient superfluorescent fibre source in the 950-1150nm range using a highly doped cladding fibre can be designed and fabricated. This is the highest superfluorescent efficiency ever reported in the literature. By taking advantage of the superfluorescence of a large Yb-cladding doped fibre, we have demonstrated a singlemode fibre laser with a linewidth of 0.3nm and a slope efficiency of 79%. This means that by using a high pump power we can achieve many watts of laser power in the fibre very easily. Again, this is the highest slope efficiency ever reported. For the purpose of making application specific couplers, we have designed and improved the equipment control system for the fabrication of fused tapered fibre devices, and have developed various procedures for making better couplers. We have also successfully fabricated and analysed asymmetric fused fibre couplers, with the highest reported asymmetric coupling of 24:1. Using eight of these low loss asymmetric couplers, a prototype passive all-optical fibre data bus was constructed and analysed. Such data buses are very

  19. Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome: one year follow-up results

    PubMed Central

    Zengin, Mehmet Ozgur; Tuncer, Ibrahim; Karahan, Eyyup

    2014-01-01

    AIM To investigate the retinal nerve fiber layer (RNFL) thickness changes in patients with obstructive sleep apnea syndrome (OSAS) for one year follow-up. To discuss the possibility of detecting tendency of glaucoma in this population by using spectral domain optical coherence tomography (3D-OCT-2000 Spectral domain). METHODS After polysomnographic study, all subjects (64 OSAS patients and 40 controls) underwent detailed ophthalmological examination. After these examinations, patients with glaucoma and patients who had ophthalmological and/or systemic disease were excluded from the study. Totally, 20 patients in OSAS group and five patients in controls were excluded from the study in the first examination and follow-up period. The RNFL thickness was assessed with OCT. Forty-four OSAS patients and 35 control subjects were followed up 12mo. RNFL thickness change and OSAS patients were evaluated for severity of disease by Apnea-Hypopnea Index (AHI). RESULTS Forty-four OSAS patients and 35 controls were enrolled in the study. Statistically significance was found between OSAS patients and controls at the 12th mo. Average RNFL thickness was found to be significantly lower in last measurements in OSAS patients when compared with first measurements and control subjects (P<0.001, 0.002, respectively). There was a statistically significant correlation among AHI, and RNFL thickness (P<0.05). CONCLUSION The results suggest that the patients with OSAS were related with a proportional decrease in the RNFL thickness. These patients should be followed up regularly for glaucomatous changes. Detecting more RNFL thinning in severe OSAS was important. PMID:25161947

  20. Optical coherence tomographic assessment of retinal nerve fiber layer thickness changes before and after glaucoma filtration surgery

    PubMed Central

    Sarkar, Kumaresh Chandra; Das, Palash; Pal, Ranabir; Shaw, Chattaranjan

    2014-01-01

    Background: Glaucomatous Optic Neuropathy (GON) is very common in the glaucoma patients, and impaired effect of glaucoma is measured by the Retinal Nerve Fiber Layer (RNFL) thickness. Objective: The study was conducted to find out the mean RNFL thickness, RNFL thickness in different quadrants, Intra-Ocular Pressure (IOP) changes, and visual field changes after filtration surgery in different ages and genders using Optical Coherence Tomography (OCT). Materials and Methods: The study was an interventional case-series conducted at the Glaucoma Clinic at the Regional Institute of Ophthalmology at Kolkata from March 2009 to August 2010. Fifty-one eyes of 43 open angle glaucoma patients had been selected for clinical and ophthalmologic evaluation. All the eyes of glaucoma patients who fulfilled the inclusion criteria were registered in the study population. The glaucoma filtration surgery was done in these patients. The RNFL thickness, IOP, visual field changes were measured before and after intervention of filtration surgery. Pre-operative OCT images of RNFL were obtained 0 to 120 days before surgery, and post-operative images were obtained from 60 to 120 days after surgery. Data collected in a standard data collection form included schedule. Results: Paired t-test was used. RNFL thickness was (pre-operative: 52.56 ± 17.40, post-operative: 58.48 ± 20.20, P < 0.0001) significantly increased after filtration surgery measured by OCT with significant reduction of IOP (r = - 0.38, P = 0.005) irrespective of age and gender. Conclusions: An increase in RNFL thickness was observed after glaucoma filtration surgery that correlated with IOP reduction. PMID:24799793

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  2. 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

  3. Changes in Peripapillary Retinal Nerve Fiber Layer Thickness after Pattern Scanning Laser Photocoagulation in Patients with Diabetic Retinopathy

    PubMed Central

    Park, Yi-Ryeung

    2014-01-01

    Purpose To examine the effects of panretinal photocoagulation (PRP) using a pattern scanning laser (PASCAL) system on the retinal nerve fiber layer (RNFL) thickness in patients with diabetic retinopathy. Methods This retrospective study included 105 eyes with diabetic retinopathy, which consisted of three groups: the PASCAL group that underwent PRP with the PASCAL method (33 eyes), the conventional group that underwent conventional PRP treatment (34 eyes), and the control group that did not receive PRP (38 eyes). The peripapillary RNFL thickness was measured by optical coherence tomography before, six months, and one year after PRP to evaluate the changes in peripapillary RNFL. Results The RNFL thickness in the PASCAL group did not show a significant difference after six months (average 3.7 times, p = 0.15) or one year after the PRP (average 3.7 times, p = 0.086), whereas that in the conventional group decreased significantly after six months (average 3.4 times, p < 0.001) and one year after PRP (average 3.4 times, p < 0.001). Conclusions The results of this study suggest that the PASCAL system may protect against RNFL loss by using less energy than conventional PRP. PMID:24882955

  4. 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 value±SD for intrasubject correlation between RVD and RNFL thickness measured with GDx VCC and GDx ECC was 0.714±0.157 and 0.629±0.140, 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 0.187±0.135 (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

  5. Damage patterns of retinal nerve fiber layer in acute and chronic intraocular pressure elevation in primary angle closure glaucoma

    PubMed Central

    Liu, Xing; Li, Mei; Zhong, Yi-Min; Xiao, Hui; Huang, Jing-Jing; Kong, Xiang-Yun

    2010-01-01

    AIM To observe the differences of damage patterns of retinal nerve fiber layer (RNFL) between acute and chronic intraocular pressure (IOP) elevation in primary angle closure glaucoma (PACG) using optical coherence tomography (OCT). METHODS Twenty-four patients (48 eyes) with unilateral acute PACG (APACG) attack in the 6 months after admission and 36 patients (64 eyes) with chronic PACG (CPACG) were included in this prospective study. For all cases, IOP has been controlled under 21mmHg after treatment. Using stratus OCT, the RNFL thickness was assessed in eyes with PACG within 3 days, 2 weeks, 1, 3 and 6 months after IOP was controlled. Repeated measures ANOVA was used to examine the changes of RNFL thickness at different time after IOP being controlled in both acute attack eyes and unaffected fellow eyes of APACG and eyes with CPACG. RESULTS The mean RNFL thickness for the APACG-attacked eyes increased significantly within 3 days (121.49±23.84)µm after acute onset and then became thinner along with time [(107.22±24.72)µm at 2 weeks,(93.58±18.37)µm at 1 month, (84.10±19.89)µm at 3 months and (78.98±19.17)µm at 6 months]. In APACG-attacked eyes, there were significant differences of average RNFL thickness at 5 different times after IOP was controlled (P<0.001). In the APACG unaffected fellow eyes and CPACG eyes, there were no significant differences in mean RNFL thickness at 5 different times(F=0.450, P=0.104 in APACG unaffected fellow eyes and F=1.558, P=0.200 in CPACG eyes). There was significant difference for interaction between time periods and groups (F=1.912, P=0.003). CONCLUSION RNFL damage patterns are different under different IOP elevated courses. In APACG, RNFL was found to be swollen and thickening right after acute attack and then becomes thinning and atrophy along with the time, while RNFL was found to be diffused thinness in CPACG. PMID:22553541

  6. Association Between Progressive Retinal Nerve Fiber Layer Loss and Longitudinal Change in Quality of Life in Glaucoma

    PubMed Central

    Gracitelli, Carolina P. B.; Abe, Ricardo Y.; Tatham, Andrew J.; Rosen, Peter N.; Zangwill, Linda M.; Boer, Erwin R.; Weinreb, Robert N.; Medeiros, Felipe A.

    2015-01-01

    IMPORTANCE Evaluation of structural optic nerve damage is a fundamental part of diagnosis and management of glaucoma. However, the relationship between structural measurements and disability associated with the disease is not well characterized. Quantification of this relationship may help validate structural measurements as markers directly relevant to quality of life. OBJECTIVE To evaluate the relationship between rates of retinal nerve fiber layer (RNFL) loss and longitudinal changes in quality of life in glaucoma. DESIGN, SETTING, AND PARTICIPANTS Observational cohort study including 260 eyes of 130 patients with glaucoma followed up for a mean (SD) of 3.5 (0.7) years. All patients had repeatable visual field defects on standard automated perimetry (SAP) at baseline. The 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was performed annually, and spectral-domain optical coherence tomography and SAP were performed at 6-month intervals. A joint model was used to investigate the association between change in NEI VFQ-25 Rasch-calibrated scores and change in RNFL thickness, adjusting for confounding socioeconomic and clinical variables. MAIN OUTCOMES AND MEASURES Association between change in binocular RNFL thickness (RNFL thickness in the better eye at each point) and change in NEI VFQ-25 scores. RESULTS Progressive binocular RNFL thickness loss was associated with worsening of NEI VFQ-25 scores over time. In a multivariable model adjusting for baseline disease severity and the rate of change in binocular SAP sensitivity, each 1-μm-per-year loss of RNFL thickness was associated with a decrease of 1.3 units (95% CI, 1.02–1.56) per year in NEI VFQ-25 scores (P < .001). After adjusting for the contribution from SAP, 26% (95% CI, 12%–39%) of the variability of change in NEI VFQ-25 scores was associated uniquely with change in binocular RNFL thickness. The P value remained less than .001 after adjusting for potential confounding factors

  7. Fibre optics: Forty years later

    SciTech Connect

    Dianov, Evgenii M

    2010-01-31

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

  8. 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

  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 μ 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

    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

  11. 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

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

    PubMed Central

    Cikmazkara, Ipek; Ugurlu, Seyda Karadeniz

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    SciTech Connect

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

    2015-08-28

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

  15. Fibre Flocculation in Papermaking

    NASA Astrophysics Data System (ADS)

    Kerekes, R. J.

    1998-11-01

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

  16. 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 μm/μm, P < 0.01) with RNFL loss, but the percent vascular contribution increased (−0.1%/μm, 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

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

    PubMed Central

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

    2012-01-01

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

  18. Determination of Axial Length Requiring Adjustment of Measured Circumpapillary Retinal Nerve Fiber Layer Thickness for Ocular Magnification

    PubMed Central

    Hirasawa, Kazunori; Shoji, Nobuyuki; Yoshii, Yukako; Haraguchi, Shota

    2014-01-01

    Purpose To determine the axial length requiring adjustment of measured circumpapillary retinal nerve fiber layer (cpRNFL) thickness to account for ocular magnification during spectral-domain optical coherence tomography (SD-OCT). Methods In this prospective study, 148 eyes of 148 healthy student volunteers were imaged by two examiners using three-dimensional SD-OCT. In 54 randomly selected eyes, total cpRNFL thickness was measured with and without adjustment for ocular magnification to establish intra-examiner and inter-examiner measurement error. The 148 eyes were then divided into three groups according to the error values: control group (difference in the corrected and uncorrected total cpRNFL thickness was within the measurement error range), thinner group (the corrected total cpRNFL thickness was less than the uncorrected one), and thicker group (the corrected total cpRNFL thickness was more than the uncorrected one). The cutoff values of axial length between the control and the other groups were calculated by receiver operating characteristic analysis. Results Measurement error ranged from 4.2 to 5.3 µm; the threshold value was defined as 5.3 µm. The cutoff values of axial length between the thinner and the control groups and between the control and the thicker groups were 23.60 (area under the curve [AUC] = 0.959) and 25.55 (AUC = 0.944) mm, respectively. Conclusions Axial lengths shorter than 23.60 mm and longer than 25.55 mm require adjustment of measured cpRNFL thickness to account for ocular magnification during SD-OCT. Clinical Trial Registration UMIN Clinical Trials Registry (http://www.umin.ac.jp/) under unique trial number UMIN000013248 (date of registration: 02/24/2014) PMID:25215521

  19. 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.

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

    PubMed Central

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

    2016-01-01

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

  1. 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.

  2. Morphometric Analysis of Peripapillary Thickness in Hypertensives and Normotensives using Optical Coherence Tomography (OCT)

    PubMed Central

    Bhandary, Sulatha V.; Rao, Lavanya G.; Kapoor, Smita

    2016-01-01

    Introduction Hypotension following antihypertensive treatment is associated with retinal nerve fibre loss. There are studies that have reported the changes in RNFL in hypertensives. Aim To compare the Retinal Nerve Fibre Layer (RNFL) thickness using Optical Coherence Tomography (OCT) in hypertensive and normotensive individuals. Materials and Methods The cross-sectional study was conducted from October 2012 to September 2014 to compare the RNFL thickness using SD OCT in hypertensive {no other ocular or systemic co-morbidity, vision better or equal to 6/9 (n=30)} and normotensive (n=30) individuals. Results Statistically significant RNFL loss was detected in hypertensives (98.31 ± 7.01) when compared to the normotensives (102.51 ± 8.72) p=0.001. Conclusion Significant loss of RNFL in hypertensives point towards the altered autoregulation and warrants larger studies to assess the clinical relevance.

  3. Fibres get functional

    NASA Astrophysics Data System (ADS)

    Graham-Rowe, Duncan

    2011-02-01

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

  4. Binding of bile salts to fibre-enriched wheat fibre.

    PubMed

    Florén, C H; Nilsson, A

    1987-01-01

    A commercial product of fibre-enriched wheat fibre (Fiberform R) was tested for its binding of bile salts in vitro. The wheat fibre preparation was standardized and through enzymatic digestion of protein and starch contained 78 per cent fibre (w/w). Fibre-enriched wheat fibre bound with high capacity both conjugated and unconjugated bile salts. Binding was saturable, reversible and showed no specificity towards tauro- or glycine-conjugated bile salts. Binding was rapid, dependent on pH, was enhanced by the presence of high salt concentrations and partially inhibited by 6 M urea. This indicated that binding was a combination of hydrophobic and hydrophilic interactions. PMID:2820035

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

    SciTech Connect

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

    1999-06-30

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

  6. Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

    NASA Astrophysics Data System (ADS)

    Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

    2016-07-01

    Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

  7. Symmetry Between the Right and Left Eyes of the Normal Retinal Nerve Fiber Layer Measured with Optical Coherence Tomography (An AOS Thesis)

    PubMed Central

    Budenz, Donald L.

    2008-01-01

    Purpose To determine the limits of the normal amount of interocular symmetry in retinal nerve fiber layer (RNFL) thickness measurements obtained with third-generation time domain optical coherence tomography (OCT3). Methods Both eyes of normal volunteers were scanned using the peripapillary standard and fast RNFL algorithms of OCT3. Results A total of 108 volunteers were included in the analysis. The mean ± standard deviation (SD) of age of the volunteers was 46.0 ± 15.0 years (range 20–82). Forty-two participants (39%) were male and 66 (61%) were female. Mean RNFL thickness correlated extremely well, with intraclass correlation coefficients of 0.89 for both algorithms (95% confidence interval [CI], 0.84–0.93). The mean RNFL thickness of the right eye measured 1.3 μm thicker than the left on the standard scan (SD 4.7, 95% CI 0.4–2.2, P = .004) and 1.2 μm on the fast scan (SD 5.2, 95% CI 0.1–2.2, P = .026). The 95% tolerance limits on the difference between the mean RNFL thicknesses of right minus left eye was −10.8 and +8.9 μm with the standard scan algorithm and −10.6 and +11.7 μm with the fast scan algorithm. Conclusions Mean RNFL thickness between the 2 eyes of normal individuals should not differ by more than approximately 9 to 12 μm, depending on which scanning algorithm of OCT3 is used and which eye measures thicker. Differences beyond this level suggest statistically abnormal asymmetry, which may represent early glaucomatous optic neuropathy. PMID:19277241

  8. 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

  9. Respiratory monitoring using fibre long period grating sensors

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

  10. Simulation of inertial fibre orientation in turbulent flow

    NASA Astrophysics Data System (ADS)

    Njobuenwu, Derrick O.; Fairweather, Michael

    2016-06-01

    The spatial and orientational behaviour of fibres within a suspension influences the rheological and mechanical properties of that suspension. An Eulerian-Lagrangian framework to simulate the behaviour of fibres in turbulent flows is presented. The framework is intended for use in simulations of non-spherical particles with high Reynolds numbers, beyond the Stokesian regime, and is a computationally efficient alternative to existing Stokesian models for fibre suspensions in turbulent flow. It is based on modifying available empirical drag correlations for the translation of non-spherical particles to be orientation dependent, accounting for the departure in shape from a sphere. The orientational dynamics of a particle is based on the framework of quaternions, while its rotational dynamics is obtained from the solution of the Euler equation of rotation subject to external torques on the particle. The fluid velocity and turbulence quantities are obtained using a very high-resolution large eddy simulation with dynamic calibration of the sub-grid scale energy containing fluid motions. The simulation matrix consists of four different fibre Stokes numbers (St = 1, 5, 25, and 125) and five different fibre aspect ratios (λ = 1.001, 3, 10, 30, and 50), with results considered at four distances from a channel wall (in the viscous sub-layer, buffer, and fully turbulent regions), which are taken as a measure of the flow velocity gradient, all at a constant fibre to fluid density ratio (ρp/ρ = 760) and shear Reynolds number Reτ = 150. The simulated fibre orientation, concentration, and streakiness confirm previous experimentally observed characteristics of fibre behaviour in turbulence, and that of direct numerical simulations of fibres in Stokesian, or creeping flow, regimes. The fibres exhibit translational motion similar to spheres, where they tend to accumulate in the near-wall (viscous sub-layer and buffer) region and preferentially concentrate in regions of low

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

  12. 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

  13. 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)

  14. Histochemical and functional fibre typing of the rabbit masseter muscle.

    PubMed Central

    Bredman, J J; Weijs, W A; Moorman, A F; Brugman, P

    1990-01-01

    The fibre-type distribution of the masseter muscle of the rabbit was studied by means of the myosin-ATPase and succinate dehydrogenase reactions. Six different fibre types were found and these were unequally distributed between and within the anatomical compartments of the muscle. Most of the masseter consists of slow- and fast-twitch oxidative fibres. The slow fibres increase in numbers in the deeper and more anterior regions of the muscle. Fast-twitch glycolytic fibres were almost exclusively found in the most posterior portions of the superficial and deep masseter. The fibre composition within the sagittally orientated anatomical compartments was found to be correlated with maximal contraction speeds during natural mastication as estimated from a mechanical model. However, the differences in fibre composition between the anatomical compartments (and hence between superficial and deep layers) appeared not to be correlated with contraction speed. The regional and compartmental specialisation within the masseter permits the muscle to perform many different functional roles in the generation and control of the jaw movements, jaw position and bite forces. Images Fig. 2 Fig. 4 Fig. 6 PMID:2139021

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

    PubMed

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

    2016-05-01

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

  16. 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

  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. 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.

  19. 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

  20. Photosensitivity of germanosilicate fibres and preforms doped with nitrogen inhomogeneously over the cross section

    SciTech Connect

    Yatsenko, Yu P; Mashinsky, V M; Medvedkov, O I; Sazhin, O D; Dianov, Evgenii M; Khopin, V F; Vechkanov, N N; Gur'yanov, A N

    2003-03-31

    The effect of the inhomogeneous distribution of nitrogen impurity on the photosensitivity of germanosilicate fibres is studied. For this purpose, single-mode fibres with different alternations of the core layers sintered in nitrogen and oxygen atmospheres were specially prepared by the MCVD technique. Photoinduced variations in the quadratic nonlinear susceptibility and refractive index of these fibres were recorded. It is shown that the recording efficiency depends on the radial distribution of germanium oxygen-deficient centres, which can be controlled at the stage of sintering through a nonuniform doping by nitrogen over the cross-section. (fibre optics)

  1. Fibre-optical microendoscopy.

    PubMed

    Gu, M; Bao, H; Kang, H

    2014-04-01

    Microendoscopy has been an essential tool in exploring micro/nano mechanisms in vivo due to high-quality imaging performance, compact size and flexible movement. The investigations into optical fibres, micro-scanners and miniature lens have boosted efficiencies of remote light delivery to sample site and signal collection. Given the light interaction with materials in the fluorescence imaging regime, this paper reviews two classes of compact microendoscopy based on a single fibre: linear optical microendoscopy and nonlinear optical microendoscopy. Due to the fact that fluorescence occurs only in the focal volume, nonlinear optical microendoscopy can provide stronger optical sectioning ability than linear optical microendoscopy, and is a good candidate for deep tissue imaging. Moreover, one-photon excited fluorescence microendoscopy as the linear optical microendoscopy suffers from severe photobleaching owing to the linear dependence of photobleaching rate on excitation laser power. On the contrary, nonlinear optical microendoscopy, including two-photon excited fluorescence microendoscopy and second harmonic generation microendoscopy, has the capability to minimize or avoid the photobleaching effect at a high excitation power and generate high image contrast. The combination of various nonlinear signals gained by the nonlinear optical microendoscopy provides a comprehensive insight into biophenomena in internal organs. Fibre-optical microendoscopy overcomes physical limitations of traditional microscopy and opens up a new path to achieve early cancer diagnosis and microsurgery in a minimally invasive and localized manner. PMID:24593142

  2. 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

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

    NASA Astrophysics Data System (ADS)

    Förster, T.; Scheffler, C.; Mäder, 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.

  4. Fibre constituents of some foods.

    PubMed

    Rani, B; Kawatra, A

    1994-06-01

    Some plant foods viz. bottlegourd, carrot, cauliflower, cabbage, green bengalgram, pea, apple, plum, guava, karonda, blackgram husk and lentil husk were analysed for their dietary fibre components. The total dietary fibre contents of these foods varied from 14.68 to 78.21 percent on dry matter basis. As compared to fruits and vegetables, the husks had higher amount of total dietary fibre. Cellulose represented as the major fibre constituent in most of the foods whereas, husks were observed to be good sources of hemicellulose. All foods were low in pectin and lignin contents except guava. PMID:7971775

  5. Sulphur-doped silica fibres

    SciTech Connect

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

    2003-01-31

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

  6. New insights into the nature of the wool fibre surface.

    PubMed

    Huson, Mickey; Evans, David; Church, Jeff; Hutchinson, Sally; Maxwell, Jane; Corino, Gary

    2008-08-01

    Wool fibres have been treated to remove the covalently bound lipid and characterised using lipid analysis, wettability and scanning probe microscopy. A model substrate consisting of alternating stripes of hydrophobic (predominantly CH(3) terminated molecules) and hydrophilic (COOH terminated molecules) surfaces, micro-printed onto a gold-coated mica surface was assessed using the SPM techniques of adhesion, friction and phase imaging and showed that SPM can easily distinguish these surfaces. When KOH/methanol treated wool fibres were examined, SPM showed an increase in coefficient of friction and a decrease in adhesion as the lipid is removed. The increased friction is consistent with studies on the model surface and confirms the hypothesis that the lipid layer decreases the surface friction of fibres. The decreased adhesion is consistent with results in the literature on hair, but is at odds with the results on the model surface. The strong contrast shown between the methyl and carboxylic acid surfaces in the friction image of the micro-patterned surface, and the complete absence of any such contrast developing with time of treatment of the wool fibres strongly suggests that the surface lipid is not present as a discrete outer layer on the fibre. A new model is proposed in which the lipid is intimately associated with the surface proteins and allows for changes in lipid concentration at the surface in response to changes in environmental conditions. PMID:18565763

  7. Effect of Photorefractive Keratectomy on Optic Nerve Head Topography and Retinal Nerve Fiber Layer Thickness Measured by Heidelberg Retina Tomograph 3

    PubMed Central

    Nilforushan, Naveed; Azadi, Pejvak; Soudi, Reza; Shaheen, Yahya; Sheibani, Kourosh

    2016-01-01

    Purpose: To determine whether photorefractive keratectomy (PRK) has a significant effect on optic nerve head (ONH) parameters and peripapillary retinal nerve fiber layer (RNFL) thickness measured by the Heidelberg Retina Tomograph 3 (Heidelberg Engineering GmbH, Heidelberg, Germany) in eyes with low to moderate myopia. Methods: This prospective, interventional case series, includes 43 consecutive myopic eyes which were assessed on the day of PRK and 3 months postoperatively using the HRT3. Among the stereometric parameters, we compared disc area, linear cup disc ratio, cup shape measure, global rim area, global rim volume, RNFL height variation contour and mean RNFL thickness; out of the Glaucoma Probability Score (GPS) we assessed changes in global value, rim steepness temporal/superior, and temporal/inferior, as well as cup size and cup depth before and after PRK. Results: Mean refractive error before and after PRK were −3.24 ± 1.31 and −0.20 ± 0.42 diopters, respectively. No significant change occurred in disc area, linear cup disc ratio, cup shape measure, rim area and rim volume among the stereometric parameters; and in rim steepness temporal/superior and rim steepness temporal/inferior in the GPS before and after PRK using the default average keratometry. However, RNFL height variation contour, mean RNFL thickness, and cup size and depth were significantly altered after PRK (P < 0.05). Conclusion: PRK can affect some HRT3 parameters. Although the most important stereometric parameters for differentiating normal, suspect or glaucomatous patients such as rim and cup measurements in stereometric parameters were not changed. PMID:27413492

  8. 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

  9. High-power fibre lasers

    NASA Astrophysics Data System (ADS)

    Jauregui, Cesar; Limpert, Jens; Tünnermann, 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.

  10. Speciality optical fibres for astronomy

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  11. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

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

  12. 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

  13. 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), emmetropes (≥−1.0 to ≤+1.0 D), and hyperopes (>+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

  14. Multilayered Glass Fibre-reinforced Composites In Rotational Moulding

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  15. Use of fibre wastes from production of acetate fibres

    SciTech Connect

    Askarov, M.I.; Tashpulatova, A.B.

    1995-07-01

    The rational use of production wastes is an important part of the Fergana Chemical Fibre Plant in Russia. This recycling reduces the negative effect of the technological process on the environment, increases the economy of production, and produces additional consumer goods. Consumer goods began to be produced at the plant in 1978 with processing of amide-acetate textured fibres into yarn for hand knitting. The need to increase the volumes and expand the variety of goods for the market predetermined an important increase in production of this product. Production of consumer goods has increased since 1990, and both fibre wastes and untreated low-grade fibres and filaments have been used as the starting material. Technological processes for processing wastes and low-grade figured, textured polyamide-acetate fibres into knitting yarn, haberdashery cord, and finishing tape and fringe were created and introduced in subsequent years. The primary technological formulation for production of these materials is well known and is used in light industry. However, production of each type of product in the plant was preceded by research related to selection of the optimum linear density of the filaments used, composition of blends, and the structure of figured fibres, as well as the concrete technological parameters and operating regimes of the equipment to produce articles of the required quality. Development and testing of new decorative textiles are continuing. Low grade and nonstandard acetate semifinished fibre from spinning machines and low grade, bulk dyed acetate fibres have been selected as the raw material for fabrication of these articles.

  16. 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.

  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

    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. 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

  19. Quantification of the CBD-FITC conjugates surface coating on cellulose fibres

    PubMed Central

    Pinto, Ricardo; Amaral, António L; Ferreira, Eugénio C; Mota, Manuel; Vilanova, Manuel; Ruel, Katia; Gama, Miguel

    2008-01-01

    Background Cellulose Binding Domains (CBD) were conjugated with fluorescein isothiocyanate (FITC). The surface concentration of the Binding Domains adsorbed on cellulose fibres was determined by fluorescence image analysis. Results For a CBD-FITC concentration of 60 mg/L, a coating fraction of 78% and 110% was estimated for Portucel and Whatman fibres, respectively. For a saturating CBD concentration, using Whatman CF11 fibres, a surface concentration of 25.2 × 10-13 mol/mm2 was estimated, the equivalent to 4 protein monolayers. This result does not imply the existence of several adsorbed protein layers. Conclusion It was verified that CBDs were able to penetrate the fibres, according to confocal microscopy and TEM-immunolabelling analysis. The surface concentration of adsorbed CBDs was greater on amorphous fibres (phosphoric acid swollen) than on more crystalline ones (Whatman CF11 and Sigmacell 20). PMID:18184429

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  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. 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 μm 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 μm for the glaucomatous eyes. Based on the segmentation, retinal and RNFL thickness maps and blood vessel masks were produced.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  5. 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)

  6. 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.

  7. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  9. 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)

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

    PubMed Central

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

    2015-01-01

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

  11. LHCb Upgrade: Scintillating Fibre Tracker

    NASA Astrophysics Data System (ADS)

    Tobin, Mark

    2016-07-01

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

  12. Dietary fibre and cardiovascular health.

    PubMed

    Sánchez-Muniz, F J

    2012-01-01

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

  13. Liquid crystal assisted optical fibres.

    PubMed

    Wahle, M; Kitzerow, H-S

    2014-01-13

    Microstructured fibres which consist of a circular step index core and a liquid crystal inclusion running parallel to this core are investigated. The attenuation and electro-optic effects of light coupled into the core are measured. Coupled mode theory is used to study the interaction of core modes with the liquid crystal inclusion. The experimental and theoretical results show that these fibres can exhibit attenuation below 0.16 dB cm(-1) in off-resonant wavelength regions and still have significant electro-optic effects which can lead to a polarisation extinction of 6 dB cm(-1). PMID:24514987

  14. 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.

  15. Friction and wear of human hair fibres

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  16. A fibre channel RAID supporting multiple protocol disk interfaces

    NASA Astrophysics Data System (ADS)

    Liu, Ruifang; Xie, Changsheng; Dong, Xiaoming

    2005-09-01

    The paper describes a kind of fibre channel RAID that support multiple protocol disk interfaces. It can manage many kinds of disk storage devices with different physical interfaces in the same time, and it can bind different kinds of disks in one logical RAID group. The interfaces can be parallel SCSI, SATA, FC, SAS, iSCSI and etc. So it can help to consolidate enterprise storage, and reduce storage management cost. The fibre channel RAID comprises of SCSI target, SCSI initiator, RAID kernel and management modules. It implements target-mode fibre channel protocol that decides the host interface type of RAID in SCSI target module. The SCSI initiator module includes SCSI initiator mid-layer(SIML), SCSI front-end initiator drivers(FEIDs). There are many kinds of disk interfaces, but the disk devices using different protocol can understand the same block level access protocol such as the traditional parallel SCSI. So we encapsulate all the common processing operations of SCSI commands and responses in one SIML. And we implement specific SCSI transport protocol in one FEID, which supports a specified kind of disk interface. In the SCSI initiator module, there can be more than one FEID. It can bring SATA, parallel SCSI, fibre channel and other kind of disks into SAN environment in the same time. It can accelerate storage consolidation, and reduce storage management cost.

  17. Intrafusal muscle fibre types in frog spindles.

    PubMed Central

    Diwan, F H; Ito, F

    1989-01-01

    Muscle spindles from bullfrog semitendinosus, iliofibularis and sartorius muscles were examined with light and electron microscopy. Four types of intrafusal muscle fibre were identified according to their diameter, central nucleation and reticular zone arrangement: a large nuclear bag fibre, a medium nuclear bag fibre, and two types of small nuclear chain fibres with and without a reticular zone, respectively. It is suggested that they are comparable to the nuclear bag1, bag2 and chain fibres in mammalian muscle spindles. Images Fig. 7 PMID:2532636

  18. Muscle fibre type changes in hypothyroid myopathy.

    PubMed Central

    McKeran, R O; Slavin, G; Andrews, T M; Ward, P; Mair, W G

    1975-01-01

    Changes in muscle fibre type in hypothyroid myopathy were studied by serial percutaneous needle biopsy of vastus lateralis before and during treatment with L-thyroxine. A type II fibre atrophy and loss was found, which correlated with the clinical and biochemical evidence of a myopathy. The type II fibre atrophy was corrected by L-thyroxine but type II fibre loss was still apparent in severely myopathic patients up to two years after starting treatment. The pathogenesis and significance of type II fibre atrophy and loss are discussed in relation to prognosis. PMID:1184764

  19. 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)

  20. Muscle fibre types in the human vastus lateralis muscles: do symmetrical sites differ in their composition?

    PubMed

    Erzen, I; Pernus, F; Sirca, A

    1990-01-01

    Muscle samples obtained from distinct symmetrical sites of left and right vastus lateralis muscles from 10 young healthy males were analysed. A computer-aided system was applied for the determination of muscle fibre types I, IIA, IIB and IIC and for their quantitative analysis. No statistically significant differences were established regarding percentage and surface area of all the four fibre types studied. In 2 cases of IIA and in one case of IIB fibre type significantly different diameters were measured between the left and right muscle. Regarding percentage and surface area no differences were proved between superficial and deep layers of the muscles observed. Fibre diameter but differed significantly in many muscles, there was no rule about whether it was larger in superficial or in deep muscle layers. One biopsy sample can not represent the whole muscle, especially as far as the relative number and surface area of the type IIA and IIB fibres are concerned. A slight asymmetry in fibre diameters of biopsy samples from both legs does not indicate any pathological change and can still be taken for normal. PMID:2403213

  1. 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.

  2. 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.

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

    PubMed

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

    2013-02-25

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

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

    PubMed Central

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

    1988-01-01

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

  5. 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

  6. Longitudinal time-domain optic coherence study of retinal nerve fiber layer in IFNβ-treated and untreated multiple sclerosis patients

    PubMed Central

    PUL, REFIK; SAADAT, MEHDI; MORBIDUCCI, FRANCO; SKRIPULETZ, THOMAS; PUL, ÜNSAL; BROCKMANN, DOROTHEE; SÜHS, KURT-WOLFRAM; SCHWENKENBECHER, PHILIPP; KAHL, KAI GÜNTER; PARS, KAWEH; STANGEL, MARTIN; TREBST, CORINNA

    2016-01-01

    Quantification of the retinal nerve fiber layer (RNFL) by optical coherence tomography (OCT) has been proposed to provide an indirect measure for retinal axonal loss. The aim of the present study was to determine whether interferon beta (IFNβ) treatment impedes retinal axonal loss in multiple sclerosis (MS) patients. A total of 48 patients with MS (24 IFNβ-1b-treated and 24 untreated subjects) and 12 healthy controls were enrolled in a prospective longitudinal OCT study. OCT measurements were performed for both eyes of each subject at baseline, and at 3-, 6-, and 12-month follow-up examinations using a time-domain OCT. At each visit, we additionally recorded full-field visual evoked potential (VEP) responses and performed the paced auditory serial addition test (PASAT), in addition to expanded disability status scale (EDSS) scoring. Generalized estimation equation (GEE) was used to account for repeated measurements and paired-data. The model-based approach predicted a monthly reduction in the RNFL thickness by 0.19 µm in the eyes of the MS subjects. The reduction was estimated to be 0.17 µm in case of IFNβ-treatment and 0.16 µm in case of no treatment. Treatment duration and group allocation were not significantly associated with the RNFL thickness. Inclusion of further longitudinal data (EDSS, two and three second PASAT) in each of our models did not result in any significant association. In summary, over a period of one year no significant association between IFNβ-1b treatment and RNFL thinning was identified in patients with MS. PMID:27347038

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

    SciTech Connect

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

    2008-01-31

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

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

    SciTech Connect

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

    2015-09-15

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

  9. Polymeric fibre optic sensor based on a SiO2 nanoparticle film for humidity sensing on wounds

    NASA Astrophysics Data System (ADS)

    Gomez, David; Morgan, Stephen P.; Hayes Gill, Barrie R.; Korposh, Serhiy

    2016-05-01

    Optical fibre sensors have the potential to be incorporated into wound dressings to monitor moisture and predict healing without the need to remove the dressing. A low cost polymeric optical fibre humidity sensor based on evanescent wave absorption is demonstrated for skin humidity measurement. The sensor is fabricated by coating the fibre with a hydrophilic film based on bilayers of Poly(allylamine hydrochloride) (PAH) and SiO2 mesoporous nanoparticles. The Layer-by-Layer method was used for the deposition of the layers. Multimode polymeric optical fibre with a cladding diameter of 250μm was covered by 7 layers of PAH/SiO2 film on the central region of an unclad fibre with a diameter of 190μm. The length of the sensitive region is 30mm. Experiment results show a decrease in light intensity when relative humidity increases due to refractive index changes of the fibre coating. The sensitivity obtained was 200mV/%RH and the sensor was demonstrated to provide a faster response to changes in the humidity of the skin microenvironment than a commercial sensor.

  10. Elastic fibres in the vesicourethral junction and urethra of the guinea pig: quantification with computerised image analysis

    PubMed Central

    DASS, NARINDER; McMURRAY, GORDON; BRADING, ALISON F.

    1999-01-01

    Elastic fibres, which are intimately associated with collagen, a major component of the urethra, have been assumed to contribute to the resting urethral closure pressure. The Miller stain for elastin was used to demonstrate elastic fibres in cryostat sections of guinea pig bladder base, vesicourethral junction (VUJ) and urethra. Computerised image analysis was employed to objectively quantify these fibres. Both male and female guinea pigs showed significantly greater amounts of circularly disposed elastic fibres in the VUJ than in the other 2 regions examined. This particular disposition of fibres may be responsible for imparting resiliency and plasticity to the VUJ, allowing it to distend and recoil repeatedly in response to urine outflow. Furthermore, the elastic fibres may be partly responsible for the passive occlusive force in this region. Elastic fibres in the distal urethra were not quantified because of their relative paucity. Sagittal sections of the urethra revealed a mass of longitudinally arranged elastic fibres localised almost exclusively within the mucosa, submucosa and longitudinal smooth muscle layer. Functionally, this arrangement may exist to facilitate urethral length changes that occur in micturition. PMID:10580860

  11. Ytterbium-doped fibre laser with a Bragg grating reflector written in a multimode fibre

    SciTech Connect

    Kurkov, Andrei S; Grukh, Dmitrii A; Medvedkov, O I; Paramonov, Vladimir M; Dianov, Evgenii M

    2005-04-30

    An efficient cladding-pumped Yb-doped fibre laser with a Bragg grating written in a multimode graded-index fibre is fabricated for the first time. The laser emits one transverse mode with a slope efficiency of 60%. The resonator design proposed in the paper can be used for the development of high-power fibre lasers with an increased fibre core diameter. (lasers)

  12. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Polarisation reflectometry of anisotropic optical fibres

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  13. Scintillating Fibre Tracking at High Luminosity Colliders

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  14. 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

  15. Local dynamics for fibred holomorphic transformations

    NASA Astrophysics Data System (ADS)

    Ponce, Mario

    2007-12-01

    Fibred holomorphic dynamics are skew-product transformations F(θ, z) = (θ + α, fθ(z)) over an irrational rotation, such that fθ is holomorphic for every θ. In this paper we study such a dynamics in a neighbourhood of an invariant curve. We obtain some results analogous to the results in the non-fibred case. In particular, we prove a fibred version of the folklore result stating that Lyapounov stability is equivalent to linearization around a fixed point. We also obtain a fibred version of the Pérez-Marco continua.

  16. Towards the Knittability of Graphene Oxide Fibres

    PubMed Central

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

    2015-01-01

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

  17. A compact polymer optical fibre ultrasound detector

    NASA Astrophysics Data System (ADS)

    Broadway, Christian; Gallego, Daniel; Pospori, Andreas; Zubel, Michal; Webb, David J.; Sugden, Kate; Carpintero, Guillermo; Lamela, Horacio

    2016-03-01

    Polymer optical fibre (POF) is a relatively new and novel technology that presents an innovative approach for ultrasonic endoscopic applications. Currently, piezo electric transducers are the typical detectors of choice, albeit possessing a limited bandwidth due to their resonant nature and a sensitivity that decreases proportionally to their size. Optical fibres provide immunity from electromagnetic interference and POF in particular boasts more suitable physical characteristics than silica optical fibre. The most important of these are lower acoustic impedance, a reduced Young's Modulus and a higher acoustic sensitivity than single-mode silica fibre at both 1 MHz and 10 MHz. POF therefore offers an interesting alternative to existing technology. Intrinsic fibre structures such as Bragg gratings and Fabry-Perot cavities may be inscribed into the fibre core using UV lasers. These gratings are a modulation of the refractive index of the fibre core and provide the advantages of high reflectivity, customisable bandwidth and point detection. We present a compact in fibre ultrasonic point detector based upon a POF Bragg grating (POFBG) sensor. We demonstrate that the detector is capable of leaving a laboratory environment by using connectorised fibre sensors and make a case for endoscopic ultrasonic detection through use of a mounting structure that better mimics the environment of an endoscopic probe. We measure the effects of water immersion upon POFBGs and analyse the ultrasonic response for 1, 5 and 10 MHz.

  18. 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.

  19. 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

  20. FIBRE OPTICS: Optical fibres based on natural biological minerals — sea sponge spicules

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

    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.

  1. 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.

  2. 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.

  3. Fibre-optic coupling to high-resolution CCD and CMOS image sensors

    NASA Astrophysics Data System (ADS)

    van Silfhout, R. G.; Kachatkou, A. S.

    2008-12-01

    We describe a simple method of gluing fibre-optic faceplates to complementary metal oxide semiconductor (CMOS) active pixel and charge coupled device (CCD) image sensors and report on their performance. Cross-sectional cuts reveal that the bonding layer has a thickness close to the diameter of the individual fibres and is uniform over the whole sensor area. Our method requires no special tools or alignment equipment and gives reproducible and high-quality results. The method maintains a uniform bond layer thickness even if sensor dies are mounted at slight angles with their package. These fibre-coupled sensors are of particular interest to X-ray imaging applications but also provide a solution for compact optical imaging systems.

  4. 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.

  5. 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%.

  6. Simulation of complex phenomena in optical fibres

    NASA Astrophysics Data System (ADS)

    Allington-Smith, Jeremy; Murray, Graham; Lemke, Ulrike

    2012-12-01

    Optical fibres are essential for many types of highly multiplexed and precision spectroscopy. The success of the new generation of multifibre instruments under construction to investigate fundamental problems in cosmology, such as the nature of dark energy, requires accurate modellization of the fibre system to achieve their signal-to-noise ratio (SNR) goals. Despite their simple construction, fibres exhibit unexpected behaviour including non-conservation of etendue (focal ratio degradation, FRD) and modal noise. Furthermore, new fibre geometries (non-circular or tapered) have become available to improve the scrambling properties that, together with modal noise, limit the achievable SNR in precision spectroscopy. These issues have often been addressed by extensive tests on candidate fibres and their terminations, but these are difficult and time-consuming. Modelling by ray tracing and wave analysis is possible with commercial software packages, but these do not address the more complex features, in particular FRD. We use a phase-tracking ray-tracing method to provide a practical description of FRD derived from our previous experimental work on circular fibres and apply it to non-standard fibres. This allows the relationship between scrambling and FRD to be quantified for the first time. We find that scrambling primarily affects the shape of the near-field pattern but has negligible effect on the barycentre. FRD helps to homogenize the near-field pattern but does not make it completely uniform. Fibres with polygonal cross-section improve scrambling without amplifying the FRD. Elliptical fibres, in conjunction with tapering, may offer an efficient means of image slicing to improve the product of resolving power and throughput, but the result is sensitive to the details of illumination. We also investigated the performance of fibres close to the limiting numerical aperture since this may affect the uniformity of the SNR for some prime focus fibre instrumentation.

  7. 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)

  8. Analysis of Retinal Layer Thicknesses and Their Clinical Correlation in Patients with Traumatic Optic Neuropathy

    PubMed Central

    Lee, Ju-Yeun; Cho, Kyuyeon; Park, Kyung-Ah; Oh, Sei Yeul

    2016-01-01

    The aims of this study were 1) To evaluate retinal nerve fiber layer (fRNFL) thickness and ganglion cell layer plus inner plexiform layer (GCIPL) thickness at the fovea in eyes affected with traumatic optic neuropathy (TON) compared with contralateral normal eyes, 2) to further evaluate these thicknesses within 3 weeks following trauma (defined as “early TON”), and 3) to investigate the relationship between these retinal layer thicknesses and visual function in TON eyes. Twenty-nine patients with unilateral TON were included. Horizontal and vertical spectral-domain optical coherence tomography (SD-OCT) scans of the fovea were taken in patients with unilateral TON. The main outcome measure was thickness of the entire retina, fRNFL, and GCIPL in eight areas. Thickness of each retinal layer was compared between affected and unaffected eyes. The correlation between the thickness of each retinal layer and visual function parameters, including best corrected visual acuity, color vision, P100 latency, and P100 amplitude in visual evoked potential (VEP), mean deviation (MD) and visual field index (VFI) in Humphrey visual field analysis in TON eyes was analyzed. Thicknesses of the entire retina, fRNFL, and GCIPL in SD-OCT were significantly thinner (3–36%) in all measurement areas of TON eyes compared to those in healthy eyes (all p<0.05). Whereas, only GCIPL in the outer nasal, superior, and inferior areas was significantly thinner (5–10%) in the early TON eyes than that in the control eyes (all p<0.01). A significant correlation was detected between retinal layer thicknesses and visual function parameters including color vision, P100 latency and P100 amplitude in VEP, MD, and VFI (particularly P100 latency, MD, and VFI) (r = -0.70 to 0.84). Among the retinal layers analyzed in this study, GCIPL (particularly in the superior and inferior areas) was most correlated with these five visual function parameters (r = -0.70 to 0.71). Therefore, evaluation of morphological

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  11. 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.

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

    PubMed Central

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

    2015-01-01

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

  13. Progress in reliability of silica optical fibres

    NASA Astrophysics Data System (ADS)

    Severin, Irina; Poulain, M.; El Abdi, R.

    2008-04-01

    Silica optical fibres that were developed for telecommunication networks extend their use for sensors and smart structures. Their reliability and expected lifetime has appeared as a major concern. Series of experiments were implemented in order to assess fibre behaviour in different environmental conditions, including chemical corrosion and mechanical stress. Optical fibres were aged in water under controlled stress overlapping microwave energy for different durations. Fibre samples were wound on different diameter mandrels applying consequently a non-uniform tensile, respectively compression stress in function of the fibre's section. Different experimental combinations were implemented in order to separate aging factor effects. Then, these aged / stretched fibres were dynamic tensile tested at different strain rates and results were statistically treated using Weibull theory. In certain cases and testing conditions, comparison with as received fibres has revealed strength increase with a generally mono-modal defect distribution on the fibre surface. Base on previous and current results, the structural relaxation phenomenon at the silica cladding - polymer coating interface might be evidenced.

  14. Image analysis of insulation mineral fibres.

    PubMed

    Talbot, H; Lee, T; Jeulin, D; Hanton, D; Hobbs, L W

    2000-12-01

    We present two methods for measuring the diameter and length of man-made vitreous fibres based on the automated image analysis of scanning electron microscopy images. The fibres we want to measure are used in materials such as glass wool, which in turn are used for thermal and acoustic insulation. The measurement of the diameters and lengths of these fibres is used by the glass wool industry for quality control purposes. To obtain reliable quality estimators, the measurement of several hundred images is necessary. These measurements are usually obtained manually by operators. Manual measurements, although reliable when performed by skilled operators, are slow due to the need for the operators to rest often to retain their ability to spot faint fibres on noisy backgrounds. Moreover, the task of measuring thousands of fibres every day, even with the help of semi-automated image analysis systems, is dull and repetitive. The need for an automated procedure which could replace manual measurements is quite real. For each of the two methods that we propose to accomplish this task, we present the sample preparation, the microscope setting and the image analysis algorithms used for the segmentation of the fibres and for their measurement. We also show how a statistical analysis of the results can alleviate most measurement biases, and how we can estimate the true distribution of fibre lengths by diameter class by measuring only the lengths of the fibres visible in the field of view. PMID:11106965

  15. 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

  16. 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)

  17. 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)

  18. Self-sensing E-glass fibres

    NASA Astrophysics Data System (ADS)

    Kister, G.; Wang, L.; Ralph, B.; Fernando, G. F.

    2003-02-01

    The primary aims of this study were to demonstrate that conventional reinforcing E-glass fibres could be converted to act as waveguides. This was achieved by selecting and applying appropriate cladding material onto the glass fibre bundle. Three classes of cladding materials were evaluated: epoxy, polyurethane and sol-gel. The light transmission characteristics through the E-glass waveguides was evaluated and compared. The epoxy and polyurethane cladding were found to be superior compared to the sol-gel coated fibres in terms of the quality of the coating and the light transmission intensity over specified lengths. The effect of fibre-end preparation on the light transmission characteristic was also investigated. The feasibility of conducting in situ tensile tests where the light transmission intensity was passed through the E-glass fibres was demonstrated successfully. This in situ technique was capable of highlighting differences in the macroscopic tensile failure modes obtained using the various cladding materials.

  19. All-fibre pulsed digital holography

    NASA Astrophysics Data System (ADS)

    Schedin, Staffan; Pedrini, Giancarlo; Tiziani, Hans J.; Santoyo, Fernando Mendoza

    1999-07-01

    An all-fibre optic system was used to record pulsed digital holograms of objects undergoing static and dynamic deformations. Light from a pulsed ruby laser was divided in two beams, each launched through different optical fibres. One fibre carried the object beam illumination and the other conveyed the reference beam towards the detector of a CCD camera. Laser light scattered from the object surface was collected with a lens-optical fibre endoscope arrangement and combined at the CCD detector with the reference beam. The holograms thus formed were digitally recorded for static and dynamic conditions. For data evaluation the Fourier transform method was used. Results show phase maps that may be evaluated for static and dynamic object deformation. With the use of a pulsed laser, the all-fibre system presented here may find a number of useful applications outside the laboratory in areas such as micromechanics, microelectronics and medical endoscopy, where access to objects of interest is otherwise difficult.

  20. Highly efficient Raman distributed feedback fibre lasers.

    PubMed

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

    2012-02-27

    We demonstrate highly efficient Raman distributed feedback (DFB) fibre lasers for the first time with up to 1.6 W of continuous wave (CW) output power. The DFB Bragg gratings are written directly into two types of commercially available passive germano-silica fibres. Two lasers of 30 cm length are pumped with up to 15 W of CW power at 1068 nm. The threshold power is ~2 W for a Raman-DFB (R-DFB) laser written in standard low-NA fibre, and only ~1 W for a laser written in a high-NA fibre, both of which oscillate in a narrow linewidth of <0.01 nm at ~1117 nm and ~1109 nm, respectively. The slope efficiencies are ~74% and ~93% with respect to absorbed pump power in the low-NA fibre and high-NA fibre respectively. Such high conversion efficiency suggests that very little energy is lost in the form of heat through inefficient energy transfer. Our results are supported by numerical simulations, and furthermore open up for the possibility of having narrow linewidth all-fibre laser sources in wavelength bands not traditionally covered by rare-earth doped silica fibres. Simulations also imply that this technology has the potential to produce even shorter R-DFB laser devices at the centimetre-level and with mW-level thresholds, if Bragg gratings formed in fibre materials with higher intrinsic Raman gain coefficient than silica are used. These materials include for example tellurite or chalcogenide glasses. Using glasses like these would also open up the possibility of having narrow linewidth fibre sources with DFB laser oscillating much further into the IR than what currently is possible with rare-earth doped silica glasses. PMID:22418313

  1. 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.

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

    PubMed Central

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

    2014-01-01

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

  3. 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

  4. Optic Disc, Macula, and Retinal Nerve Fiber Layer Measurements Obtained by OCT in Thyroid-Associated Ophthalmopathy.

    PubMed

    Sayın, Osman; Yeter, Volkan; Arıtürk, Nurşen

    2016-01-01

    Aim. To compare the measurements of retinal nerve fiber layer (RNFL), macula and optic disc parameters obtained by optical coherence tomography (OCT), and intraocular pressure (IOP) between the patients with thyroid-associated ophthalmopathy (TAO) and healthy controls. Methods. One hundred and thirty-two eyes of 66 patients with TAO and 72 eyes of 36 healthy controls were included in the study. Proptosis level was determined by Hertel exophthalmometer. Optic disc, peripapillary retinal nerve fiber layer, and macula parameters were measured by OCT. All measurements of the patients were compared with those of age- and sex-matched healthy controls. Results. No statistically significant difference was found between the patients with TAO and control group in terms of demographic characteristics (P > 0.05). Exophthalmometer measurements and IOP were higher in TAO group (P < 0.05). Mean macula thicknesses in TAO and control groups were 239.3 ± 29.8 μm and 246.6 ± 31.8 μm, respectively, and the difference between the groups was statistically significant (P = 0.000). TAO group had thinner inferior RNFL thickness and macular thicknesses (superior, inferior, temporal, and nasal) and higher disc area and C/D ratio when compared with the control group (P < 0.05). Conclusion. IOP, disc area, and C/D area ratio were higher in the patients with TAO and the thicknesses of macula and inferior RNFL were thinner when compared with healthy controls. This trial is registered with registration number at clinicaltrials.gov NCT02766660. PMID:27493796

  5. Optic Disc, Macula, and Retinal Nerve Fiber Layer Measurements Obtained by OCT in Thyroid-Associated Ophthalmopathy

    PubMed Central

    Sayın, Osman; Arıtürk, Nurşen

    2016-01-01

    Aim. To compare the measurements of retinal nerve fiber layer (RNFL), macula and optic disc parameters obtained by optical coherence tomography (OCT), and intraocular pressure (IOP) between the patients with thyroid-associated ophthalmopathy (TAO) and healthy controls. Methods. One hundred and thirty-two eyes of 66 patients with TAO and 72 eyes of 36 healthy controls were included in the study. Proptosis level was determined by Hertel exophthalmometer. Optic disc, peripapillary retinal nerve fiber layer, and macula parameters were measured by OCT. All measurements of the patients were compared with those of age- and sex-matched healthy controls. Results. No statistically significant difference was found between the patients with TAO and control group in terms of demographic characteristics (P > 0.05). Exophthalmometer measurements and IOP were higher in TAO group (P < 0.05). Mean macula thicknesses in TAO and control groups were 239.3 ± 29.8 μm and 246.6 ± 31.8 μm, respectively, and the difference between the groups was statistically significant (P = 0.000). TAO group had thinner inferior RNFL thickness and macular thicknesses (superior, inferior, temporal, and nasal) and higher disc area and C/D ratio when compared with the control group (P < 0.05). Conclusion. IOP, disc area, and C/D area ratio were higher in the patients with TAO and the thicknesses of macula and inferior RNFL were thinner when compared with healthy controls. This trial is registered with registration number at clinicaltrials.gov NCT02766660. PMID:27493796

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

    PubMed Central

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

    2016-01-01

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

  7. 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 < 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

  8. Surface plasmon resonance based fibre optic chemical sensor for the detection of cocaine

    NASA Astrophysics Data System (ADS)

    Nguyen, T. Hien; Sun, Tong; Grattan, Kenneth T. V.

    2016-05-01

    A surface plasmon based fibre-optic chemical sensor for the detection of cocaine has been developed using a molecularly imprinted polymer (MIP) film with embedded gold nanoparticles as the recognition element. The MIP was formed on the layer of gold thin film which was deposited on the surface of a fibre core. The sensing was based on swelling of the MIP film induced by analyte binding that shifted the resonance spectrum toward a shorter wavelength. The sensor exhibited a response to cocaine in the concentration range of 0 - 400 μM in aqueous acetonitrile mixtures. Selectivity for cocaine over other drugs has also been demonstrated.

  9. Vortex shedding fluid flowmeter using optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Lyle, J. H.; Pitt, C. W.

    1981-03-01

    An optical fibre flowmeter is described which uses a single fibre mounted transversely to the fluid flow within the pipe. The fibre is vibrated by the natural phenomenon of vortex shedding, causing phase modulation of the optical carrier within. The modulation is detected at the fibre exit by the fibredyne technique, and the flow rate determined from the vibration frequency.

  10. Small fibre function in primary autonomic failure.

    PubMed

    Baron, R; Feldmann, R; Lindner, V

    1993-12-01

    A case of primary autonomic failure (AF) with uncomplicated Parkinson's disease is presented with clinical and neurophysiological data. Special emphasis is placed on new methods of examining impairment of unmyelinated sympathetic and afferent C-fibres. Sympathetic vasoconstrictor responses in the skin induced by deep inspiration were examined quantitatively with laser Doppler flowmetry. The vasoconstriction was markedly depressed in primary AF compared with healthy controls and similar to secondary forms of AF. Peripheral nociceptive C-fibre function was quantitatively assessed by measurement of axon reflex vasodilatation induced by histamine iontophoresis. The axon reflex vasodilatation was completely intact in primary AF in contrast to patients with secondary peripheral small fibre neuropathy. The results indicate that sympathetic C-fibres are considerably affected by the degenerative disease, whereas the afferent C-fibres seem to be totally preserved. Modern neurophysiological methods of testing sympathetic and afferent small fibre function in combination with other neurophysiological tests, e.g. brain-stem auditory evoked potentials, might help to diagnose and differentiate primary AF in early stages and make it easier to distinguish between secondary autonomic neuropathies of unknown origin that often also involve unmyelinated afferent fibres. PMID:8138830

  11. Chalcogenide-tellurite composite microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Kohoutek, T.; Duan, Z.; Kawashima, H.; Yan, X.; Suzuki, T.; Matsumoto, M.; Misumi, Takashi; Ohishi, Y.

    2012-02-01

    We report on fabrication a composite microstructured optical fibre composed of highly nonlinear chalcogenide Ge-Ga- Sb-S glass core and tellurite TeO2-ZnO-Li20-Bi2O3 glass clad. We aimed at obtaining more flattened chromatic dispersion for pumping chalcogenide glass based optical fibre by a pulse laser at current telecommunication wavelengths, i.e. λ = 1.35 - 1.7 μm, which is difficult to achieve by using a single material chalcogenide fibers due to their high refractive index (n > 2.1). A fibre design exploiting a composite of two glasses and one ring of the air holes brings similar options for tuning the fibre dispersion such as use of complex multi rings of air-holes approach. A good choice of glasses, allows for fabricating a composite chalcogenide-tellurite optical fibre benefiting from high nonlinearity of chalcogenide core glass but exploiting a tellurite glass technology and fibre drawing. In the paper, we discuss some aspects of CMOF design concerning current chalcogenide and tellurite glass choice. Also, we show the supercontinuum spectra recorded from current chalcogenide-tellurite CMOF pumped with a custom made femtosecond fibre laser at λ = 1.55 μm with the pulse duration of 400 fs.

  12. A unique cross section through the skin of the dinosaur Psittacosaurus from China showing a complex fibre architecture

    PubMed Central

    Lingham-Soliar, Theagarten

    2008-01-01

    This paper reports on a unique preservation of soft tissues in the ventrolateral region of the plant-eating dinosaur Psittacosaurus from the Jehol biota of China. The preservation is of a deep cross section through the dermis, which includes multiple layers of collagenous fibres in excess of 25, among the highest recorded in vertebrates, with a further 15 more layers (poorly preserved) estimated for the entire height of the section. Also, for the first time in a dinosaur two fibre layers parallel to the skin surface are preserved deep within the dermis at the base of the cross section. These fibre layers comprise regularly disposed fibres arranged in left- and right-handed geodesic helices, matching the pattern at the surface and reasonably inferred for the entire section. As noted from the studies on modern-day animals, this fibre structure plays a critical part in the stresses and strains the skin may be subjected to and is ideally suited to providing support and protection. Psittacosaurus gives a remarkable, unprecedented understanding of the dinosaur skin. PMID:18182372

  13. 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.

  14. Influence of slip on the Plateau-Rayleigh instability on a fibre.

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    PubMed

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

    2016-10-01

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

  17. 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

  18. Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres

    NASA Astrophysics Data System (ADS)

    Jülich, Florian; Aulbach, Laura; Wilfert, Andre; Kratzer, Peter; Kuttler, Rolf; Roths, Johannes

    2013-09-01

    Gauge factors of fibre Bragg grating (FBG)-based strain sensors that had been inscribed into three different types of optical fibres, which differ in core diameters and doping concentrations, were determined at room temperature with high accuracy. Repeated measurements were carried out with several samples of each type of fibre to allow statistical evaluations. For each type, the gauge factors were measured in two configurations: when the bare fibres were glued on a specimen at the location of the FBG and when they were vertically suspended and not bonded to any structure at the location of the FBG. By combining the results of both configurations, the strain transfer ratio of the gluing process and the strain-optic coefficient, peff, of the different types of fibres were determined. The strain-optic coefficient was found to vary up to 1.5% for the different types of optical fibres. The strain transfer ratio was obtained to be close to unity (>99%), showing the high quality of the gluing technique employed. The investigations demonstrate that highly accurate strain sensing is possible with fibre-optic strain sensors. The results are important for the development of accurate and reliable attaching techniques for coated sensor fibres and fibre-optic sensor patches.

  19. 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.

  20. 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

  1. Fibre communications: Time-reversed twin

    NASA Astrophysics Data System (ADS)

    Ip, Ezra; Kahn, Joseph M.

    2013-07-01

    Co-propagating a signal with its phase conjugate along an optical fibre link makes it possible to mitigate unwanted nonlinear distortions and improve the signal-to-noise ratio in long-haul optical communication systems.

  2. Recent progress in polymer optical fibre gratings

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Carroll, K.; Webb, D. J.; Bennion, I.; Kalli, K.; Emiliyanov, G.; Bang, O.; Kjær, E.; Peng, G. D.

    2008-04-01

    We describe our recent progress in polymer fibre Bragg grating technology, including the writing of the first FBGs in TOPAS cyclic olefin copolymer, enhancements to photosensitivity brought about by dopants and studies on grating annealing.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  4. 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.

  5. Fibre Bragg grating for flood embankment monitoring

    NASA Astrophysics Data System (ADS)

    Markowski, Konrad; Nevar, Stanislau; Dworzanski, Adam; Hackiewicz, Krzysztof; Jedrzejewski, Kazimierz

    2014-11-01

    In this article we present the preliminary studies for the flood embankment monitoring system based on the fibre Bragg gratings. The idea of the system is presented. The Bragg resonance shift is transformed to the change of the power detected by the standard InGaAs photodiode. The discrimination of the received power was executed by another fibre Bragg grating with different parameters. The project of the fully functional system is presented as well.

  6. 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)

  7. 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.

  8. Folded fibre bus interconnects with distributed amplification

    NASA Astrophysics Data System (ADS)

    Lorenzo, Raul Hernandez; Urquhart, Paul; Lopez-Amo, Manuel

    1998-06-01

    An optical fibre network for application as an interconnect within major nodes is investigated theoretically. The network is configured as a folded bus in which the spine consists of erbium doped fibre to overcome the power division at the couplers. It is argued that high received powers with a narrow dynamic range can be obtained simultaneously with bit rates in the order of 10 Gbit/s and bit error rates of 10 -12 or less.

  9. 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.

  10. 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.

  11. Dewatering of fibre suspensions by pressure filtration

    NASA Astrophysics Data System (ADS)

    Hewitt, Duncan R.; Paterson, Daniel T.; Balmforth, Neil J.; Martinez, D. Mark

    2016-06-01

    A theoretical and experimental study of dewatering of fibre suspensions by uniaxial compression is presented. Solutions of a one-dimensional model are discussed and asymptotic limits of fast and slow compression are explored. Particular focus is given to relatively rapid compression and to the corresponding development of spatial variations in the solidity and velocity profiles of the suspension. The results of complementary laboratory experiments are presented for nylon or cellulose fibres suspended in viscous fluid. The constitutive relationships for each suspension were measured independently. Measurements of the load for different fixed compression speeds, together with some direct measurements of the velocity profiles using particle tracking velocimetry, are compared with model predictions. The comparison is reasonable for nylon, but poor for cellulose fibres. An extension to the model, which allows for a strain-rate-dependent component in the network stress, is proposed, and is found to give a dramatic improvement in the model predictions for cellulose fibre suspensions. The reason for this improvement is attributed to the microstructure of cellulose fibres, which, unlike nylon fibres, are themselves porous.

  12. Conduction in regenerating dorsal root fibres.

    PubMed

    Feasby, T E; Bostock, H; Sears, T A

    1981-03-01

    Rat dorsal roots were crushed and recordings of compound action potentials and single fibre longitudinal currents were made 12-85 days later from the regenerating portions. Maximum conduction velocities rose from 1.3 m/s at day 10 to 25.7 m/s by day 41 and single fibre velocities varied from 1.2 m/s at 12 days postcrush to 23.8 m/s at 85 days. Many fibres appeared to conduct continuously in the early stages, although the resolution of the technique was insufficient to exclude saltatory conduction over short internodes. Two fibres showed internodes of about 200 microns at 9 and 13 days of regeneration, suggesting that "nodal" regions may be formed before significant myelination. At 27 days post-crush and later, internodes were 300-425 microns in length. Many regenerating fibres had branches, both retrograde and orthograde. Reduced conduction velocities in rostral portions of regenerating fibres suggested tapering. PMID:6260903

  13. Knowledge about dietary fibre: a fibre study framework.

    PubMed

    Guiné, Raquel P F; Ferreira, Manuela; Correia, Paula; Duarte, João; Leal, Marcela; Rumbak, Ivana; Barić, Irena C; Komes, Drazenka; Satalić, Zvonimir; Sarić, Marijana M; Tarcea, Monica; Fazakas, Zita; Jovanoska, Dijana; Vanevski, Dragoljub; Vittadini, Elena; Pellegrini, Nicoletta; Szűcs, Viktória; Harangozó, Júlia; El-Kenawy, Ayman; El-Shenawy, Omnia; Yalçın, Erkan; Kösemeci, Cem; Klava, Dace; Straumite, Evita

    2016-09-01

    The objective of this work was to study the degree of knowledge about dietary fibre (DF), as influenced by factors such as gender, level of education, living environment or country. For this, a descriptive cross-sectional study was undertaken on a non-probabilistic sample of 6010 participants from 10 countries in different continents (Europe, Africa and America). The results showed that the participants revealed on average a positive but still low global level of knowledge, which alerts for the need to take some actions to further inform the population about DF and its role as a component of a healthy diet. The results also indicated differences between genders, levels of education, living environments and countries. The highest level of knowledge was revealed by the participants from female gender, with higher education and living in urban areas. Concerning the country, the best informed were the participants from Romania, followed by those from Portugal and Turkey while the least informed were from Egypt. PMID:27263981

  14. Development of high-power holmium-doped fibre amplifiers

    NASA Astrophysics Data System (ADS)

    Hemming, Alexander; Simakov, Nikita; Davidson, Alan; Oermann, Michael; Corena, Len; Stepanov, Dmitrii; Carmody, Neil; Haub, John; Swain, Robert; Carter, Adrian

    2014-03-01

    Resonantly pumped holmium fibre lasers present a range of opportunities for the development of novel fibre laser and amplifier devices due to the availability of mature, efficient high power thulium fibre pump lasers. In this paper we describe the operation of a large mode area holmium-doped fibre amplifier. The master-oscillator is an all-fibre linearly polarised, core pumped single mode laser operating at 27 W at 2.11 μm. This laser was amplified in a large mode area fibre producing up to 265 W of output power. This system is the first demonstration of a resonantly pumped holmiumdoped fibre amplifier. It is also the highest power fibre amplifier that is capable of operating in an atmospheric transmission window <2.05 μm. This monolithic all-fibre system is able to address a wide range of remote sensing, scientific, medical and defence applications.

  15. 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

  16. 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

  17. 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

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Butylina, Svetlana; Martikka, Ossi; Kärki, Timo

    2011-04-01

    This study examined the effect of type of wood fibre source on the physical and mechanical properties of wood fibre-polypropylene composites. Wood flour, fibres of heat-treated wood and pellets were used as sources of wood fibres in the manufacturing process. All studied wood fibre-polypropylene composites were made from 75% wood, 22% recycled polypropylene (PP) and 3% maleated polypropylene (MAPP). Wood fibre-polypropylene composites were compounded in a conical twin-screw extruder. Water absorption and thickness swelling were studied. Mechanical properties of the composites were characterised by tensile, flexural, and impact testing. Micromechanical deformation processes were investigated using scanning electron microscopy done on the fractured surfaces of broken samples. The durability of composites exposed to three accelerated cycles of water immersion, freezing and thawing was examined. The results showed that the density of the composites was a key factor governing water absorption and thickness swelling. A significant improvement in tensile strength, flexural strength, and Charpy impact strength was observed for composites reinforced with heat-treated fibre compared to composites reinforced with pellets and especially to wood flour reinforced composites. The flexural strength and dimensional stability performance reduced after exposure to freeze-thaw cycling for all composites, but the degree of these changes was dependent on the wood fibre source.

  1. 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

  2. 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

  3. Yb-, Er-Yb-, and Nd-doped fibre lasers based on multi-element first cladding fibres

    SciTech Connect

    Bufetov, Igor' A; Bubnov, M M; Mel'kumov, Mikhail A; Dudin, V V; Shubin, Aleksei V; Semenov, S L; Kravtsov, K S; Dianov, Evgenii M; Gur'yanov, A N; Yashkov, M V

    2005-04-30

    Single-mode cw Yb-, Er-Yb, and Nd-doped fibre lasers are fabricated by using fibres of a complicated structure (a few silica fibres in optical contact with each other are surrounded by a polymer jacket). Such a structure allows the coupling of radiation from several pump sources into one active fibre, providing an increase in the output power of the fibre laser. The Yb-doped fibre lasers with the output power above 50 W and efficiency {approx}65% and the 1.608-{mu}m Er-Yb-doped fibre laser pumped to the absorption band of Yb are fabricated and studied. The Nd-doped fibre lasers based on such fibres and emitting at 0.92 and 1.06 {mu}m are manufactured for the first time. (lasers)

  4. 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)

  5. Photosensitivity of optical fibres doped with different impurities

    SciTech Connect

    Larionov, Yu V; Rybaltovsky, A A; Semenov, S L; Vartapetov, Sergei K; Kurzanov, M A; Obidin, Aleksei Z

    2004-02-28

    Photosensitivities of hydrogen-loaded silica fibres doped with germanium, phosphorus, antimony, and aluminium are estimated and compared. It is shown that although all the fibres can be pre-exposed, the degree of this effect is noticeably different for different fibres because the induction of the refractive index is determined by a combined contribution from a one-step photochemical reaction and a two-step reaction responsible for pre-exposure. One-step reactions dominate in more photosensitive optical fibres, while two-step reactions dominate in less photosensitive fibres. (optical fibres)

  6. Spun microstructured optical fibres for Faraday effect current sensors

    SciTech Connect

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

    2009-11-30

    We report a simple design of spun holey fibres and the first experimental study of the magneto-optical response of spun microstructured fibres with high built-in birefringence. Such fibres enable the Faraday-effect-induced phase shift to effectively accumulate in a magnetic field even at very small coiling diameters. For example, the magneto-optical sensitivity of a 5-mm-diameter fibre coil consisting of 100 turns is {approx}70% that of an ideal fibre, in good agreement with theoretical predictions. (optical fibres and fibreoptic sensors)

  7. 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)

  8. Effect of different lay-ups on the microstructure, mechanical properties and neutron transmission of neutron shielding fibre metal laminates

    NASA Astrophysics Data System (ADS)

    Fu, Xuelong; Tang, Xiaobin; Hu, Yubing; Li, Huaguan; Tao, Jie

    2016-07-01

    A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups, composed of stacking layers of AA6061 plates, neutron shielding composite and carbon fibre reinforced polyimide (CFRP), were fabricated using hot molding process in atmospheric environments. The microstructure, mechanical properties and neutron transmission of the NSFMLs were evaluated, respectively. The results indicated that the NSFMLs possessed good mechanical properties owing to the good interfacial adhesion of the components. Tensile strength and elastic modulus of the NSFMLs increased with the numbers of lay-ups, while the elongation to fracture exhibited obvious declining tendency. Flexural strength and modulus of the NSFMLs were improved obviously with the increasing of stacking layers. Neutron transmission of the NSFMLs decreased obviously with increasing the number of lay-ups, owing to the increase of 10B areal density. Besides, the effect of carbon fibres on the neutron shielding performance of the NSFMLs was also taken into consideration.

  9. 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

  10. Somatostatin-14-like immunoreactive neurons and fibres in the human olfactory bulb.

    PubMed

    Ohm, T G; Braak, E; Probst, A

    1988-01-01

    This study describes the morphological features and the distribution pattern of neurons in the human olfactory bulb which are immunoreactive for an antiserum against the neuropeptide somatostatin-14. Immunoreactive nerve cell bodies were mainly found in the white matter surrounding the cell clusters of the anterior olfactory nucleus. Some immunoreactive neurons were also found scattered throughout the anterior olfactory nucleus and the deeper parts of the inner granule cell layer. Only a few immunoreactive neurons were localized in the glomerular layer and the outer granule cell layer. Immunoreactive fibres were found in all layers of the olfactory bulb. In addition, an impressive number of coiled and kinked immunoreactive fibres were localized within the anterior olfactory nucleus forming a dense plexus. Accumulations of twisted and coiled branches of immunoreactive fibres were rarely found either surrounding or within the olfactory glomerula. The characteristics of somatostatin-14 immunoreactive neurons as seen in the combined pigment-Nissl preparation were studied after decolourizing the chromogen and restaining the preparations with aldehydefuchsin in order to demonstrate the lipofuscin pigment and gallocyanin chrome alum for Nissl material. About 90% of the immunoreactive neurons studied in this manner turned out to be devoid of lipofuscin granules. The remaining 10% displayed different patterns of pigmentation. These findings suggest the presence of different types of somatostatin-14-like immunoreactive neurons in the olfactory bulb of the human adult. PMID:2906788