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1

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

PubMed

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

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-06-01

2

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

PubMed Central

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).

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-01-01

3

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

PubMed Central

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 frequently and earlier for RNFL retardance as compared with RNFLT.

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

2013-01-01

4

Retinal nerve fibre layer imaging compared with histological measurements in a human eye  

Microsoft Academic Search

PurposeA feasibility study comparing retinal nerve fibre layer (RNFL) thickness values obtained with imaging devices against RNFL thickness measurements obtained histologically in a human eye.DesignA single patient scheduled for orbital exenteration, who still possessed a healthy functioning eye.MethodsBefore surgery, the eye was imaged using optical coherence tomography (OCT) and scanning laser polarimetry (SLP). After orbital exenteration, the globe was sectioned,

E Z Blumenthal; R S Parikh; J Pe'er; M Naik; E Kaliner; M J Cohen; S Prabakaran; M Kogan; R Thomas

2009-01-01

5

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

PubMed Central

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.

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

6

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

7

Retinal nerve fibre layer and visual function loss in glaucoma: the tipping point  

PubMed Central

Aims To determine the retinal nerve fibre layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss. Methods In a prospective cross-sectional study, 72 healthy and 40 glaucoma subjects (one eye per subject) recruited from an academic institution had VF examinations and spectral domain optical coherence tomography (SD-OCT) optic disc cube scans (Humphrey field analyser and Cirrus HD-OCT, respectively). Comparison of global mean and sectoral RNFL thicknesses with VF threshold values showed a plateau of threshold values at high RNFL thicknesses and a sharp decrease at lower RNFL thicknesses. A ‘broken stick’ statistical model was fitted to global and sectoral data to estimate the RNFL thickness ‘tipping point’ where the VF threshold values become associated with the structural measurements. The slope for the association between structure and function was computed for data above and below the tipping point. Results The mean RNFL thickness threshold for VF loss was 75.3 ?m (95% CI: 68.9 to 81.8), reflecting a 17.3% RNFL thickness loss from age-matched normative value. Above the tipping point, the slope for RNFL thickness and threshold value was 0.03 dB/?m (CI: ?0.02 to 0.08) and below the tipping point, it was 0.28 dB/?m (CI: 0.18 to 0.38); the difference between the slopes was statistically significant (p<0.001). A similar pattern was observed for quadrant and clock-hour analysis. Conclusions Substantial structural loss (~17%) appears to be necessary for functional loss to be detectable using the current testing methods.

Wollstein, Gadi; Kagemann, Larry; Bilonick, Richard A; Ishikawa, Hiroshi; Folio, Lindsey S; Gabriele, Michelle L; Ungar, Allison K; Duker, Jay S; Fujimoto, James G; Schuman, Joel S

2011-01-01

8

Localised retinal nerve fibre layer defects in chronic experimental high pressure glaucoma in rhesus monkeys  

PubMed Central

AIM—To evaluate prospectively in an experimental model of chronic high pressure glaucoma whether the concept of a mainly diffuse pattern of optic nerve damage holds true for high pressure glaucoma.?METHODS—The study comprised nine eyes of nine rhesus monkeys (Macaca mulatta) with a mean age of 17.7 (SD 3.1) years (range 13-23 years). Experimental glaucoma was produced by multiple applications of argon laser to the trabecular meshwork. Applanation tonometry was regularly performed and fundus photographs, which were taken serially, were used for retinal nerve fibre layer (RNFL) assessment and morphometric optic disc analysis. Six monkeys, in which arterial hypertension and atherosclerosis had additionally been induced several years before elevation of intraocular pressure, did not show any sign of diffuse loss or localised defects of the RNFL before initiation of glaucoma.?RESULTS—Compared with the same eyes at baseline, localised RNFL defects had developed in eight (89%) eyes. It included all three eyes (100%) of the monkeys without arterial hypertension/arteriosclerosis, and five of the six monkeys (83%) with arterial hypertension/arteriosclerosis. Four eyes had multiple localised RNFL defects. In all eyes, diffuse RNFL loss was additionally present.?CONCLUSIONS—Besides diffuse loss of RNFL, localised RNFL defects were present in almost all eyes of monkeys with chronic experimental high pressure glaucoma. Challenging the concept that a mostly diffuse type of optic neuropathy occurs in high pressure glaucoma, the results suggest that, in high pressure glaucoma, at least a mixture of localised and diffuse pattern of optic nerve damage prevails.??

Jonas, J.; Hayreh, S. S.

1999-01-01

9

Retinal nerve fibre layer measurements are reduced in patients with obstructive sleep apnoea syndrome  

Microsoft Academic Search

PurposeTo determine the retinal nerve fibre layer (RNFL) thickness in patients with obstructive sleep apnoea syndrome (OSAS) in order to investigate the possibility of detecting early signs of glaucoma in this population.MethodsA total of 66 consecutive patients admitted for polysomnographic evaluation of suspected OSAS. Patients underwent an overnight sleep study in an effort to diagnose and determine the severity of

S H Kargi; R Altin; M Koksal; L Kart; F Cinar; S H Ugurbas; F Ayoglu

2005-01-01

10

Changes in retinal nerve fibre layer, optic nerve head morphology, and visual field after acute primary angle closure  

PubMed Central

Aims/Purpose To determine and correlate the long-term changes in retinal nerve fibre layer (RNFL) thickness, optic nerve head (ONH) morphology, and visual fields after a single episode of acute primary angle closure (APAC). Methods This was a cross-sectional comparative study of patients at National University Hospital (Singapore) from 2000 to 2006 after an episode of unilateral APAC. The peripapillary and macular RNFL were measured using Stratus optical coherence tomography (OCT) and ONH configuration was assessed using Heidelberg Retina Tomography (HRT)-III. Humphrey perimetry was also performed, and the presence of disc pallor was noted. APAC eyes were compared with fellow eyes as matched controls. Results Twenty-five patients were assessed at a median of 33 months (range, 11–85 months) after APAC. OCT showed that there was a reduction in the peripapillary and outer macular RNFL thickness in APAC eyes compared with controls. Humphrey perimetry revealed significantly reduced mean deviation (P=0.006) and increased pattern standard deviation (P=0.045) in APAC eyes compared with controls. HRT-III showed no difference in mean rim area, rim volume, or cup–disc ratio between APAC eyes and controls. Disc pallor was present in nine APAC eyes (36%) but was absent in fellow eyes (P=0.002), and was associated with peripapillary RNFL thinning, visual field loss, and an increased interval between the onset of symptoms and normalization of intraocular pressure (P=0.023). Conclusion APAC results in peripapillary and outer macular RNFL loss, visual field defects, and optic disc pallor, even in cases in which the ONH configuration remains unchanged.

Sng, C C A; See, J S L; Ngo, C S; Singh, M; Chan, Y-H; Aquino, M C; Tan, A M; Shabana, N; Chew, P T K

2011-01-01

11

Heterogeneous Pattern of Retinal Nerve Fiber Layer in Multiple Sclerosis. High Resolution Optical Coherence Tomography: Potential and Limitations  

Microsoft Academic Search

BackgroundRecently the reduction of the retinal nerve fibre layer (RNFL) was suggested to be associated with diffuse axonal damage in the whole CNS of multiple sclerosis (MS) patients. However, several points are still under discussion. (1) Is high resolution optical coherence tomography (OCT) required to detect the partly very subtle RNFL changes seen in MS patients? (2) Can a reduction

Nermin Serbecic; Fahmy Aboul-Enein; Sven C. Beutelspacher; Martin Graf; Karl Kircher; Wolfgang Geitzenauer; Werner Brannath; Priska Lang; Wolfgang Kristoferitsch; Hans Lassmann; Andreas Reitner; Ursula Schmidt-Erfurth; Christoph Kleinschnitz

2010-01-01

12

Modelling cyclic shear deformation of fibre\\/epoxy layers in fibre metal laminates  

Microsoft Academic Search

Relations for a theoretical model were derived describing the shear deformation of uni-directional fibre\\/epoxy layers in Fibre Metal Laminates. The shear deformation is induced by the cyclic shear stresses at the interface that result from the cyclic load transfer from aluminium to the bridging fibre\\/epoxy layers during fatigue loading of the laminate. With the presented relations the crack opening contribution

René Alderliesten; Gianni Campoli; Rinze Benedictus

2007-01-01

13

Quantitative RNFL attenuation coefficient measurements by RPE-normalized OCT data  

NASA Astrophysics Data System (ADS)

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).

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

2012-02-01

14

Scanning Laser Polarimetry Reveals Status of RNFL Integrity in Eyes with Optic Nerve Head Swelling by OCT  

PubMed Central

Purpose. Optical coherence tomography (OCT) shows retinal nerve fiber layer (RNFL) thickening in optic nerve head (ONH) swelling, but does not provide information on acute axonal disruption. It was hypothesized that scanning laser polarimetry (SLP) compared with OCT might reveal the status of axon integrity and visual prognosis in acute RNFL swelling. Methods. Threshold perimetry, OCT, and SLP were used to prospectively study eyes with papilledema (24), optic neuritis (14), nonarteritic anterior ischemic optic neuropathy (NAION) (21), and ONH swelling (average RNFL value by OCT was above the 95th percentile of controls at presentation). Regional RNFL was judged reduced if the quadrant measurement was below the fifth percentile of controls. Results. At presentation, average RNFL by OCT was similar for eyes with papilledema and NAION (P = 0.97), and reduced for optic neuritis. Average RNFL by SLP was slightly increased for papilledema and optic neuritis, and reduced for NAION (P = 0.02) eyes. The RNFL by SLP was reduced in at least one quadrant in 1 eye with papilledema, 1 eye with optic neuritis, and in 13 eyes with NAION. In NAION eyes, quadrants with reduced SLP had corresponding visual field loss that did not recover. By one month, eyes with NAION showed RNFL thinning by OCT (7/17 eyes) and by SLP (14/16 eyes) in contrast to optic neuritis (by OCT, 0/12, P = 0.006; and by SLP, 1/12, P = 0.0004). Conclusions. OCT and SLP revealed different aspects of RNFL changes associated with ONH swelling. OCT revealed thickening due to edema. SLP revealed a decrease in retardance in eyes with axonal injury associated with visual field loss, which is unlikely to recover.

Kupersmith, Mark J.; Kardon, Randy; Durbin, Mary; Horne, Melissa; Shulman, Julia

2012-01-01

15

Hyperelastic modelling of arterial layers with distributed collagen fibre orientations  

PubMed Central

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

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

2005-01-01

16

Opto-chemical fibre Bragg grating sensors based on evanescent field interaction with specific transducer layers  

NASA Astrophysics Data System (ADS)

Fibre side-polishing technology allows for refractive index measurements using optical fibre Bragg grating sensors. Evanescent field interaction between the guided fibre light mode and the analyte near to the core of the side-polished optical fibre yields a Bragg wavelength shift in dependence on the refractive index of the analyte. This refractometric sensor technique has been extended to opto-chemical measurements with specific sensitivity using transducer layers with selective absorption properties deposited on the side-polished fibre core region. Experimental results are presented for the case of a hydrogen gas sensor (palladium transducer) and a pH sensor (polyaniline transducer).

Ecke, Wolfgang; Schroeder, Kerstin; Bierschenk, Silvio; Willsch, Reinhardt

2005-09-01

17

Heterogeneous Pattern of Retinal Nerve Fiber Layer in Multiple Sclerosis. High Resolution Optical Coherence Tomography: Potential and Limitations  

PubMed Central

Background Recently the reduction of the retinal nerve fibre layer (RNFL) was suggested to be associated with diffuse axonal damage in the whole CNS of multiple sclerosis (MS) patients. However, several points are still under discussion. (1) Is high resolution optical coherence tomography (OCT) required to detect the partly very subtle RNFL changes seen in MS patients? (2) Can a reduction of RNFL be detected in all MS patients, even in early disease courses and in all MS subtypes? (3) Does an optic neuritis (ON) or focal lesions along the visual pathways, which are both very common in MS, limit the predication of diffuse axonal degeneration in the whole CNS? The purpose of our study was to determine the baseline characteristics of clinical definite relapsing-remitting (RRMS) and secondary progressive (SPMS) MS patients with high resolution OCT technique. Methodology Forty-two RRMS and 17 SPMS patients with and without history of uni- or bilateral ON, and 59 age- and sex-matched healthy controls were analysed prospectively with the high resolution spectral-domain OCT device (SD-OCT) using the Spectralis 3.5mm circle scan protocol with locked reference images and eye tracking mode. Furthermore we performed tests for visual and contrast acuity and sensitivity (ETDRS, Sloan and Pelli-Robson-charts), for color vision (Lanthony D-15), the Humphrey visual field and visual evoked potential testing (VEP). Principal Findings All 4 groups (RRMS and SPMS with or without ON) showed significantly reduced RNFL globally, or at least in one of the peripapillary sectors compared to age-/sex-matched healthy controls. In patients with previous ON additional RNFL reduction was found. However, in many RRMS patients the RNFL was found within normal range. We found no correlation between RNFL reduction and disease duration (range 9–540 months). Conclusions RNFL baseline characteristics of RRMS and SPMS are heterogeneous (range from normal to markedly reduced levels).

Beutelspacher, Sven C.; Graf, Martin; Kircher, Karl; Geitzenauer, Wolfgang; Brannath, Werner; Lang, Priska; Kristoferitsch, Wolfgang; Lassmann, Hans; Reitner, Andreas; Schmidt-Erfurth, Ursula

2010-01-01

18

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

19

Fibre optical scanning with high resolution in thin-layer chromatography  

Microsoft Academic Search

In this paper a high-performance thin-layer chromatography (HPTLC) scanner is presented in which a special fibre arrangement is used as HPTLC plate scanning interface. Measurements are taken with a set of 50 fibres at a distance of 400 to 500 ?m above the HPTLC plate. Spatial resolutions on the HPTLC plate of better than 160 ?m are possible. It takes

Bernd Spangenberg; Karl-Friedrich Klein

2000-01-01

20

Design criteria for multi-layered scintillating fibre arrays with inclined columns  

NASA Astrophysics Data System (ADS)

Multi-layered scintillating fibre arrays read-out are commonly used as high resolution charged particle hodoscopes. Fibres of a "column" along the geometrical trajectory of incident particles are typically grouped to one pixel of a multi-channel read-out device. In some applications the incident particles will cross the detection plane with large angles w.r.t. the normal to the layers. Then, the packing of the fibres needs to be adapted to the incident particles and the columns need to be inclined. In this paper possible fibre array geometries are shown, relevant design criteria for detectors are discussed, and the effect of diverging particles incident on fibre arrays was studied using a Monte Carlo simulation.

Achenbach, P.; Nungesser, L.; Pochodzalla, J.

2008-06-01

21

Fibre Optic Strain and Configuration Sensing in Engineering Components Produced by Additive Layer Rapid Manufacturing  

Microsoft Academic Search

Additive layered rapid manufacturing offers the ability to create physical parts with little or no restriction from shape complexity. Modelling and validation of this new technology requires embedded sensors which challenges conventional sensor technology. In this work, fibre Bragg gratings [FBG] have been embedded inside components made from a polymer during the manufacturing process of layer-by-layer additive manufacturing technology by

R. R. J. Maier; W. N. MacPherson; J. S. Barton; M. Carne; M. Swan; J. N. Sharma; S. K. Futter; D. A. Knox; B. J. S. Jones; S. McCulloch

2011-01-01

22

U-bend fibre optic pH sensors using layer-by-layer electrostatic self-assembly technique  

NASA Astrophysics Data System (ADS)

A layer-by-layer assembly technique is used to coat layers of nano-thin-films of pH indicator on a U-bend optical fibre to create an effective sensor, using neutral red as the active element. The experimental results characterizing such a pH sensor shows a wide pH sensing range (from pH5 to pH10) fast response.

Surre, F.; Lyons, W. B.; Sun, T.; Grattan, K. T. V.; O'Keeffe, S.; Lewis, E.; Elosua, C.; Hernaez, M.; Barian, C.

2009-07-01

23

Effects of increasing the fibre content of a layer diet  

Microsoft Academic Search

1. 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.2. The fibrous ingredients lowered the metabolisable energy (ME) of the basal diet from 11·82 to between 9·31 and 11·21 MJ\\/kg.3. Utilisation (g food\\/kg

O. G. Longe

1984-01-01

24

A comparison of optical coherence tomography and retinal nerve fiber layer photography for detection of nerve fiber layer damage in glaucoma  

Microsoft Academic Search

PurposeTo compare optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness measurements with established methods for assessment of glaucomatous damage using RNFL photography and visual field testing.

Linda M Zangwill; Julia Williams; Charles C Berry; Sharon Knauer; Robert N Weinreb

2000-01-01

25

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

PubMed Central

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.

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

2012-01-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2001-10-01

27

Optical fibre temperature sensor based on fluorescein and rhodamine codoped polymer layer  

NASA Astrophysics Data System (ADS)

The article presents the luminescent based optical fiber transducer. The new construction of polymer optical fibre sensor with resonant energy transfer is shown. The idea and fabrication process of low cost optode is presented. The fluorescein and rhodamine B codoped polymethylmethacrylate (PMMA) sensitive layer exhibits the wide range of absorption spectrum ensures high source to optode spectrum alignment. The luminescent response under 430 and 470nm Light Emitting Diode (LED) source is shown. The experimental characteristic of sensor in the range from 293 K to 403 K is shown. The article presents also the potential applications of presented sensor.

Miluski, Piotr; Dorosz, Dominik; Kochanowicz, Marcin; ?mojda, Jacek

2013-10-01

28

Functional LSM–ScSZ\\/NiO–ScSZ dual-layer hollow fibres for partial oxidation of methane  

Microsoft Academic Search

In this study, a functional La0.80Sr0.20MnO3?? (LSM)–Scandia-Stabilized-Zirconia (ScSZ)\\/NiO–ScSZ dual-layer hollow fibre has been developed using a single-step co-extrusion and co-sintering process, and has been employed as a dual-layer hollow fibre membrane reactor for partial oxidation of methane. Oxygen permeation rate between 0.49 and 1.82 ml\\/min and methane conversion between 53.55% and 98.78% have been achieved when operating temperature is elevated from

Zhentao Wu; Bo Wang; Kang Li

2011-01-01

29

Retinal hyperaemia-related blood vessel artifacts are relevant to automated OCT layer segmentation.  

PubMed

A frequently observed local measurement artifact with spectral domain OCT is caused by the void signal of the retinal vasculature. This study investigated the effect of suppression of blood vessel artifacts with and without retinal hyperaemia. Spectral domain OCT scans, centred on the optic nerve head, were performed in 46 healthy subjects (92 eyes). Baseline scans were made during rest, while for the follow-up scan, 23 subjects (50 %) performed strenuous physical exercise. Systemic and retinal hyperaemia were quantified. Quantification of retinal nerve fibre layer (RNFL) thickness was performed with and without suppression of retinal blood vessel artifacts. The potential systematic effect on RNFL thickness measurements was analysed using Bland-Altman plots. At baseline (no retinal hyperaemia), there was a systematic difference in RNFL thickness (3.4 ?m, limits of agreement -0.9 to 7.7) with higher values if blood vessel artifacts were not suppressed. There was significant retinal hyperaemia in the exercise group (p < 0.0001). Baseline thickness increased from 93.18 to 93.83 ?m (p < 0.05) in the exercise group using the algorithm with blood vessel artifact suppression, but no significant changes were observed using the algorithm without blood vessel artifact suppression. Retinal hyperaemia leads to blood vessel artifacts which are relevant to the precision of OCT layer segmentation algorithms. The two algorithms investigated in this study can not be used interchangeably. The algorithm with blood vessel artifact suppression was more sensitive in detecting small changes in RNFL thickness. This may be relevant for the use of OCT in a range of neurodegenerative diseases were only a small degree of retinal layer atrophy have been found so far. PMID:24390200

Balk, L J; Mayer, M; Uitdehaag, B M J; Petzold, A

2014-03-01

30

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

PubMed

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

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

2014-04-01

31

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

PubMed Central

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 ?m (range 82.26-146.25). The RNFL was thickest inferiorly (134.10 ± 16.16 ?m) and superiorly (133.44 ± 15.50 ?m), thinner nasally (84.26 ± 16.43 ?m), and thinnest temporally (70.72 ± 14.80 ?m). 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.

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

2014-01-01

32

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

NASA Astrophysics Data System (ADS)

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

Huang, Xiangrun

33

Direct Lattice Resolution of Layer Planes in Polyacrylonitrile Based Carbon Fibres  

Microsoft Academic Search

THE microstructure of polyacrylonitrile (PAN) based carbon fibres has been investigated by several techniques including high and low angle X-ray diffraction and electron microscopy. The results obtained with high-modulus (400 GNm-2) RAE carbon fibres1,2 and high-modulus Rolls-Royce carbon fibres3 are essentially similar; crystallites, the widths of which have a distribution of values with a mean about 65 Å, enclose sharp-edged

D. J. Johnson

1970-01-01

34

Rates of retinal nerve fibre layer thickness change in glaucoma patients and control subjects  

PubMed Central

Purpose To examine the rates of retinal nerve fibre layer thickness (RNFLT) change in glaucoma patients and healthy, age-similar control subjects with three techniques: scanning laser polarimetry with variable corneal compensation (VCC) and enhanced corneal compensation (ECC), and time-domain optical coherence tomography (OCT). Methods Sixty-one patients and thirty-three controls were examined with each technique and with standard automated perimetry (SAP) every 6 months. Rates of global RNFLT change and SAP mean deviation (MD) change were estimated with linear mixed-effects models. Results The median (interquartile range) baseline age was 64.4 (58.2, 71.0) years for patients and 62.4 (56.3, 70.1) years for controls (P=0.56). There was a median of seven examinations over 3.1 years for patients and six examinations in 3.0 years for controls. Baseline visual field MD and RNFLT for all imaging modalities were significantly lower (P<0.01) in patients compared with controls. Rates of RNFLT change were not significantly different between patients and controls (P?0.19). Mean rates of VCC-measured RNFLT change were ?0.18 and ?0.37??m per year in patients and controls, whereas the respective figures for ECC and OCT were ?0.13 and ?0.31??m per year, and 0.04 and 0.61??m per year. Mean rates of MD change were ?0.20 and 0.03?dB per year in patients and controls, respectively (P=0.01). Conclusion Rates of RNFLT change in glaucoma patients were not statistically different from control subjects for any modality. A significantly negative rate of MD change in patients suggests a genuine, continued deterioration in these patients not reflected by RNFLT changes.

O'Leary, N; Artes, P H; Hutchison, D M; Nicolela, M T; Chauhan, B C

2012-01-01

35

Agreement between Retinal Nerve Fiber Layer Measures from Spectralis and Cirrus Spectral Domain OCT  

PubMed Central

Purpose An assessment of the retinal nerve fiber layer (RNFL) provides important information on the health of the optic nerve. There are several non-invasive technologies, including spectral domain optical coherence tomography (SD-OCT), that can be used for in vivo imaging and quantification of the RNFL, but often there is disagreement in RNFL thickness between clinical instruments. The purpose of this study was to investigate the influence of scan centration, ocular magnification and segmentation on the degree of agreement of RNFL thickness measures by two SD-OCT instruments. Methods RNFL scans were acquired from forty-five normal eyes using two commercially available SD-OCT systems. Agreement between RNFL thickness measures was determined using each instrument's algorithm for segmentation and a custom algorithm for segmentation. The custom algorithm included ocular biometry measures to compute the transverse scaling for each eye. Major retinal vessels were identified and removed from RNFL measures in 1:1 scaled images. Transverse scaling was also used to compute the RNFL area for each scan. Results Instrument derived global RNFL thickness measured from the two instruments correlated well (R2 = 0.70, p<0.01), but with significant differences between instruments (mean of 6.7 µm; 95% limits of agreement of 16.0 µm to ?2.5 µm, ICC = 0.62). For recentered scans with custom RNFL segmentation, the mean difference was reduced to 0.1 µm (95% limits of agreement 6.1 µm to ?5.8 µm, ICC = 0.92). Global RNFL thickness was related to axial length (R2 = 0.24, p<0.01), while global RNFL area measures were not (R2 = 0.004, p = 0.66). Major retinal vasculature accounted for 11.3±1.6% (Cirrus) or 11.8±1.4% (Spectralis) of the RNFL thickness/area measures. Conclusions Sources of disagreement in RNFL measures between SD-OCT instruments can be attributed to the location of the scan path and differences in their retinal layer segmentation algorithms. In normal eyes, the major retinal vasculature accounts for a significant percentage of the RNFL and is similar between instruments. With incorporation of an individual's ocular biometry, RNFL area measures are independent of axial length, with either instrument.

Wheat, Joe L.; Rodriguez, Aldon; Tran, Victoria; Harwerth, Ronald S.

2011-01-01

36

Chemical vapor deposition of titanium nitride on carbon fibres as a protective layer in metal matrix composites  

Microsoft Academic Search

The significance of carbon fibres for reinforcing metals has increased in the last years, because of their excellent mechanical properties. However, to avoid the weakening reaction during MMC fabrication between the fibre and the liquid metal, a protective coating has to be applied. Continuous carbon fibre roving with 6000 filaments were coated with TiN by thermal induced chemical vapour deposition

N Popovska; H Gerhard; D Wurm; S Poscher; G Emig; R. F Singer

1997-01-01

37

Physiological variation of segmented OCT retinal layer thicknesses is short-lasting.  

PubMed

The application of spectral domain optical coherence tomography as a surrogate for neurodegeneration in a range of neurological disorders demands better understanding of the physiological variation of retinal layer thicknesses, which may mask any value of this emerging outcome measure. A prospective study compared retinal layer thicknesses between control subjects (n = 15) and runners (n = 27) participating in a 10-km charity run. Three scans were performed using an eye-tracking function (EBF) and automated scan registration for optimal precision at (1) baseline, (2) directly after the run, and (3) following a rehydration period. Retinal layer segmentation was performed with suppression of axial retinal vessel signal artifacts. Following the run, there was an increase in the relative retinal nerve fibre layer (p = 0.018), the combined inner plexiform/ganglion cell layer (p = 0.038), and the outer nuclear layer (p = 0.018) in runners compared to controls. The initial increase of thickness in the outer nuclear layer of runners (p < 0.0001) was likely related to (noncompliant) rehydration during exercise. Following a period of rest and rehydration, the difference in thickness change for all retinal layers, except the retinal nerve fibre layer (RNFL) (p < 0.05), disappeared between the two groups. There is a quantifiable change in the axial thickness of retinal layersthat which can be explained by an increase in the cellular volume. This effect may potentially be caused by H2O volume shifts. PMID:24101128

Balk, Lisanne; Mayer, Markus; Uitdehaag, Bernard M J; Petzold, Axel

2013-12-01

38

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

39

The attenuation of retinal nerve fiber layer thickness and cognitive deterioration  

PubMed Central

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

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

2013-01-01

40

Characterization of retinal nerve fiber layer thickness changes associated with Leber's hereditary optic neuropathy by optical coherence tomography  

PubMed Central

In the present study, the changes in the retinal nerve fiber layer (RNFL) thickness associated with Leber’s hereditary optic neuropathy (LHON) were examined by Cirrus high definition-optical coherence tomography (OCT), and the correlation between the RNFL thickness and the best corrected visual acuity (BCVA) was evaluated. A cross-sectional study was performed. Sixty-eight eyes from patients with LHON and 30 eyes from healthy individuals were scanned. Affected eyes were divided into 5 groups according to disease duration: Group 1, ?3 months; group 2, 4–6 months; group 3, 7–9 months; group 4, 10–12 months; and group 5, >12 months. The RNFL thickness of the temporal, superior, nasal and inferior quadrants and the 360° average were compared between the LHON groups and the control group. The eyes in groups 1 and 2 were observed to have a thicker RNFL in the superior, nasal and inferior quadrants and a higher 360°-average RNFL thickness compared with those of the control group (P<0.05), the RNFL was observed to be thinner in the temporal quadrant in groups 1 and 2. The eyes in groups 3 and 4 showed a thinner RNFL in the temporal (P=0.001), superior and inferior (both P<0.05) quadrants, and a lower 360°-average RNFL thickness as compared with controls (P=0.001). No significant correlation was identified between BCVA and RNFL thickness. RNFL thickness was observed to undergo a unique process from thickening to thinning in the patients with LHON. Changes in different quadrants occurred at different time periods and the BCVA was not found to be correlated with RNFL thickness.

ZHANG, YIXIN; HUANG, HOUBIN; WEI, SHIHUI; QIU, HUAIYU; GONG, YAN; LI, HONGYANG; DAI, YANLI; JIANG, ZHAOCAI; LIU, ZIHAO

2014-01-01

41

Bismuth-ring-doped fibres  

SciTech Connect

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)

Zlenko, Aleksandr S; Dvoirin, Vladislav V; Bogatyrev, Vladimir A; Firstov, Sergei V [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Akhmetshin, Ural G [Tarusa Department of A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Tarusa, Kaluga region (Russian Federation)

2009-11-30

42

Numerical assessment of delamination in fibre metal laminates  

Microsoft Academic Search

In the present contribution numerical models for delamination in fibre metal laminates are discussed. Fibre metal laminates form a class of materials in which homogeneous aluminium sheets are combined with fibre reinforced prepreg layers. Intensive experimental analyses have been carried out to assess the possible application of new design methods which make use of the layered structure of fibre metal

Frank Hashagen; René de Borst

2000-01-01

43

The correlation between rat retinal nerve fiber layer thickness around optic disc by using optical coherence tomography and histological measurements  

PubMed Central

AIM To explore the correlation between the retinal nerve fiber layer (RNFL) thickness by using optical coherence tomography (OCT) and by histological measurements in normal adult rats and optic nerve transected rats. METHODS The RNFL thickness of 36 rats was scanned in a circle 3.46mm far from the optic disc by OCT. The two experimental groups were the normal group (n=20 rats) and the optic nerve transected group (n=16 rats). The latter group included 4 groups (n=4/group) surviving for 1 day, 3, 5 and 7 days. Then the RNFL thickness of the same retina area was also measured by NF-200 immunohistochemical staining method. Linear regression was used to analyze the correlation between the data obtained from these two methods. RESULTS The RNFL thickness of normal right eyes around optic disc by OCT was 72.35±5.71µm and that of the left eyes was 72.65±5.88µm (P=0.074). The RNFL thickness of the corresponding histological section by immunohistochemistry was 37.54±4.05µm (right eyes) and 37.38±4.23µm (left eyes) (P=0.059). There was a good correlation between the RNFL thickness measured by OCT and that measured by histology (R2=0.8131). After optic nerve transection, the trend of the RNFL thickness was thinner with the prolonged survival time. The correlation of the thickness detected by the above two methods was approximately (R2=0.8265). Value of the RNFL thickness in rats around optic disc measured by OCT was obviously higher than that measured by common histological measurement in normal adult rats and optic nerve transected rats. CONCLUSION The RNFL thickness measured by OCT has a strong correlation with that measured by histological method. Through OCT scanning, we found that the thickness of RNFL gradually becomes thinner in a time-dependent manner.

Huang, Ju-Fang; Yu, Hui-Min; Shang, Lei; Ma, Ruo-Fei; Cynthia, Ngobe Akume; Cao, Yan-Qun; Luo, Jia; Zeng, Le-Ping; Chen, Dan; Xiong, Kun

2013-01-01

44

Characteristics of patients with a localized retinal nerve fiber layer defect and normal optic disc appearance  

PubMed Central

Purpose To investigate the characteristics of patients with a localized retinal nerve fiber layer (RNFL) defect and normal optic disc appearance compared with normal tension glaucoma (NTG) patients. Methods A total of 40 patients with an unchanged RNFL defect for more than 5 years and normal optic disc appearance, who were presumed as non-glaucomatous patients, were enrolled (group A). We recruited 40 age-matched patients with NTG (group B). On the RNFL photographs, we evaluated angles of RNFL defects. Angle ? and ? were the angles made by the line ‘L' from the center of the fovea to the disc center and the lines ‘A' and ‘B' from the disc center to the disc margin where the proximal and the distal border of the defect met, respectively. Angle ? was the angular width of the defect. Angle ? was the angle made by lines ‘L' and ‘R', which divides angle ? into a 2?:?1 ratio from line ‘A' to line ‘B'. We compared systemic diseases, baseline IOP, and location and angles of the RNFL defects between the two groups. Results Systemic diseases and superotemporal RNFL defects in group A were significantly greater than those in group B (P<0.001). Angle ? was greater in group A, but angle ?, ?, and ? were smaller in group A (P<0.05). Conclusion If the patients with a superotemporal RNFL defect and normal optic disc appearance had systemic diseases and distal borders of the defects are closer to the macula, glaucoma is less likely.

Lee, J; Kim, J; Kee, C

2012-01-01

45

Property Optimisation in Fibre Metal Laminates  

Microsoft Academic Search

Fibre Metal Laminates (FMLs) are hybrid materials, which consist of thin metal sheets bonded together with alternating unidirectional fibre layers. This material concept has resulted in superior fatigue characteristics with respect to the metallic counterpart. Several static characteristics (specifically tension, shear, bearing, blunt and sharp notch behaviour) are however negatively influenced due to the fibre addition. This paper investigates the

R. van Rooijen; J. Sinke; T. J. De Vries; S. van der Zwaag

2004-01-01

46

Retinal Nerve Fiber Layer Thickness. The Beijing Eye Study 2011  

PubMed Central

Purpose To measure retinal nerve fiber layer (RNFL) thickness in a population-based setting. Methods In the population-based Beijing Eye Study 2011 with 3468 individuals, RNFL thickness was measured in a subgroup of 1654 (47.7%) study participants by spectral domain optical coherence tomography (iVue SD-OCT). Results Mean RNFL thickness was significantly (P<0.001) higher in the inferior sector (131.4±20.6 µm) than the superior sector (126.1±19.1 µm), where it was higher than in the temporal sector (79.8±12.2 µm;P<0.001), where it was higher than in the nasal sector (75.1±12.6 µm;P<0.001). In multivariate analysis, mean global RNFL thickness (103.2±12.6 µm) increased significantly with younger age (standardized correlation coefficient beta:?0.30;P<0.001), larger neuroretinal rim area (beta:0.26;P<0.001), shorter axial length (beta:?0.21;P<0.001), thicker subfoveal choroidal thickness (beta:0.15;P<0.001), larger optic disc area (beta:0.10;P<0.001), less refractive lens power (beta:0.10;P<0.001), flatter anterior cornea (beta:0.07;P?=?0.01) and female gender (beta:0.05;P?=?0.03). In this population with an age of 50+ years, the age-related decline in RNFL thickness was 0.5 µm per year of life or 0.36% of an original RNFL thickness of 137 µm at baseline of the study at 50 years of age. Mean global RNFL thickness decreased by 2.4 µm for each mm enlargement of axial length. Conclusions The RNFL profile shows a double hump configuration with the thickest part in the inferior sector, followed by the superior sector, temporal sector and nasal sector. Factors influencing global RNFL thickness were younger age, larger neuroretinal rim, shorter axial length, thicker subfoveal choroid, larger optic disc, less refractive lens power, flatter anterior cornea and female gender. Beyond an age of 50+ years, RNFL decreased by about 0.3% per year of life at an age of 50+ years and by 2.4 µm per mm of axial elongation. These findings may be of interest for the knowledge of the normal anatomy of the eye and may be of help to diagnose diseases affecting the RNFL.

Wang, Ya Xing; Pan, Zhe; Zhao, Liang; You, Qi Sheng; Xu, Liang; Jonas, Jost B.

2013-01-01

47

Delamination buckling of fibre–metal laminates  

Microsoft Academic Search

A fibre–metal laminate is a composite of metal and fibre-reinforced prepreg layers. An example of such a material is Glare. It consists of alternating layers of aluminium and glass-fibre-reinforced prepreg. The material can be sensitive to delamination buckling, which occurs when a partially delaminated panel is subjected to a compressive force. The interaction of local buckling and extension of the

J. J. C. Remmers; R. de Borst

2001-01-01

48

Interfacial reaction and strength of SiC fibres coated with aluminium alloys  

Microsoft Academic Search

Silicon carbide fibres (Nicalon) were coated with pure aluminium and aluminium alloys containing silicon. The coated fibres were annealed to produce an interfacial reaction zone between the coated layer and the fibre. The effect of this reaction zone on the tensile strength of the fibre was investigated. During the early stages of growth the reaction zone of the fibre is

H. Liu; U. Madaleno; T. Shinoda; Y. Mishima; T. Suzuki

1990-01-01

49

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

PubMed Central

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

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

2010-01-01

50

Greater attenuation of retinal nerve fiber layer thickness in Alzheimer's disease patients.  

PubMed

Thinning of retinal nerve fiber layer (RNFL) may reflect neurodegeneration of the central nervous system, which has been reported as part of the neuropathogenesis of Alzheimer's disease (AD). Specifically, AD patients have thinner RNFL as compared to age-matched normal controls. However, whether reduction of RNFL over time can predict those at higher risk to develop cognitive deterioration remains unknown. We therefore set out a prospective clinical investigation to determine both the reduction of RNFL thickness and the deterioration of cognitive function over a period of 25 months in 78 participants (mean age 72.31 ± 3.98 years, 52% men). The participants were categorized as stable participants whose cognitive status remained unchanged (n = 60) and converted participants whose cognitive status deteriorated, which was diagnosed by DSM-VI (for AD) and Petersen's definition (for mild cognitive impairment) (n = 18). Here we show for the first time that the converted participants had greater reduction of RNFL thickness than the stable participants. Specifically, the reduction in the thickness of the inferior quadrant RNFL in the converted participants was greater than that in stable participants [-11.0 ± 12.8 (mean ± standard deviation) ?m versus 0.4 ± 15.7 ?m, p = 0.009]. These data showed that greater reduction in the inferior quadrant of RNFL thickness might indicate a higher risk for the old adults to develop cognitive deterioration. These findings have established a system to embark on a larger scale study to further test whether changes in RNFL thickness can serve as a biomarker of AD. PMID:24413621

Shi, Zhongyong; Wu, Yujie; Wang, Meijuan; Cao, Jing; Feng, Wei; Cheng, Yan; Li, Chunbo; Shen, Yuan

2014-01-01

51

Retinal nerve fiber layer thickness profiles associated with ocular laterality and dominance.  

PubMed

Although human anatomy is arranged symmetrically based on a central vertical axis, the majority of persons will use one side of their body more readily than the other. Interestingly, these lateral body dominances including ocular dominance are all rightward. The asymmetry in retinal nerve fiber layer (RNFL) thickness between the right and left eyes in healthy subjects has been reported in several studies, and the reason for this structural difference between right and left eyes is unclear. In the manuscript, we hypothesized that the characteristics of ocular dominance are reflected in the RNFL profile and may be related to inter-ocular structural differences between right and left eyes. In this study, ocular dominance occurred mostly in right eyes (right vs. left: 78.77% vs. 21.22%; P<0.001). According to ocular dominance and laterality, different relationships between the inferior and superior RNFLs were observed. The right eyes had a thicker RNFL, except in the superior quadrant, than the left eyes. Regardless of laterality, inferior RNFL was thicker than superior RNFL in the dominant eyes. To our knowledge, this paper is the first report demonstrating the RNFL characteristics associated with ocular dominance. PMID:24240009

Choi, Jin A; Kim, Jung-Sub; Park, Hae-Young Lopilly; Park, Hana; Park, Chan Kee

2014-01-13

52

Bragg fibre for sensing applications  

NASA Astrophysics Data System (ADS)

In this work, we propose to take advantage of properties of a Bragg fibre for optical sensing. The Bragg fibre exhibits three concentric high refractive index layers embedded in pure silica and surrounding a 35?m diameter core. A short (0.3 m long) piece of Bragg fibre slightly multimode, is used to elaborate an intermodal interferometer, the spectral response of which exhibits a fringe pattern that depends on the operating wavelength, which can therefore be used as a sensor. The two modes considered were found to be the fundamental LP01 and the high-order mode LP02. The sensor has been characterized in strain and temperature and presents a sensitivity of - 1.09 pm/?? and 14.1 pm/°C respectively. The sensor demonstrated insensitivity to curvature thanks to well known Bragg fibre properties.

Frazão, O.; Baptista, J. M.; Santos, J. L.; Roy, P.; Jamier, R.; Février, S.

2010-04-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2002-01-01

54

Comparisons of Retinal Nerve Fiber Layer Thickness after Indocyanine Green, Brilliant Blue G, or Triamcinolone Acetonide-Assisted Macular Hole Surgery  

PubMed Central

Purpose. To compare the postoperative changes of the retinal nerve fiber layer (RNFL) thickness in patients with macular holes (MHs) treated with vitrectomy with indocyanine green- (ICG-), brilliant blue G- (BBG-), or triamcinolone acetonide- (TA-)assisted internal limiting membrane (ILM) peeling. Methods. Sixty-one eyes of 61 consecutive patients with MHs were studied. Each eye was randomly selected to undergo either ICG- (n = 18), BBG- (n = 21), or TA-assisted (n = 22) ILM peeling. The circumferential retinal nerve fiber layer (RNFL) thickness was determined by spectral-domain optical coherence tomography (SD-OCT) before and 1, 3, 6, 9, and 12 months postoperatively. The mean overall and the sectoral thicknesses of the RNFL were obtained for each group. Results. A transient increase of the RNFL thickness was seen in the mean overall and sectoral thicknesses except for the nasal/inferior sector at 1 month after surgery for the three groups. Then, the thickness gradually decreased and returned to the baseline level in all sectors except for the nasal/inferior sector. The differences in the RNFL thickness among the groups were not significant for at least 12 months postoperatively. Conclusions. The degree of change of the RNFL thickness was not significantly related to the type of vital stain used during MH surgery.

Toba, Yoshiharu; Machida, Shigeki; Kurosaka, Daijiro

2014-01-01

55

Relationship Between Visual Field Sensitivity and Retinal Nerve Fiber Layer Thickness Measured by Scanning Laser Polarimetry and Optical Coherence Tomography in Normal, Ocular Hypertensive and Glaucomatous Eyes  

PubMed Central

Purpose To evaluate the correlation between automated achromatic perimetry (AAP) and the output of two retinal nerve fiber layer (RNFL) analysers: scanning laser polarimetry (GDx-VCC) and optical coherence tomography (OCT). Methods Quantitative RNFL measurements with GDx-VCC and Stratus-OCT were obtained in one eye from 52 healthy subjects, 38 ocular hypertensive (OHT) patients and 94 glaucomatous patients. All patients underwent a complete examination, including AAP using the Swedish interactive threshold algorithm (SITA). The relationship between RNFL measurements and SITA visual field global indices were assessed by means of the following methods: analysis of variance, bivariate Pearson's correlation coefficient, multivariate linear regression techniques and nonlinear regression models, and the coefficient of determination (r2) was calculated. Results RNFL thickness values were significantly lower in glaucomatous eyes than in healthy and ocular hypertensive eyes for both nerve fiber analysers (P?0.001), except for the inferior 120° average thickness in GDx-VCC. Linear regression models constructed for GDx-VCC measurements and OCT-derived RNFL thickness with SITA visual field global indices demonstrated that, for the mean deviation, the only predictor in the model was the nerve fiber indicator for GDx-VCC (r2=0.255), and for the pattern standard deviation, the predictors in the model were the nerve fiber indicator for GDx-VCC (r2=0.246) and the maximum thickness in the superior quadrant for Stratus-OCT (r2=0.196). The best curvilinear fit was obtained with the cubic model. Conclusions Quantitative measurements of RNFL thickness using either GDx-VCC or OCT correlate moderately with visual field global indices in moderate glaucoma patients. We did not find a correlation between visual field global indices and RNFL thickness in early glaucoma patients. Further study is needed to develop new analytical methods that will increase RNFL analyser's sensitivity in early glaucoma patients.

Lleo-Perez, Antonio; Ortuno-Soto, Amparo; Rahhal, M.S.; Sanchis-Gimeno, Juan A.

2010-01-01

56

Comparison of localized retinal nerve fiber layer defects in highly myopic, myopic, and non-myopic patients with normal-tension glaucoma: a retrospective cross-sectional study  

PubMed Central

Background The purpose of this study was to evaluate the relationship between patterns of localized retinal nerve fiber layer (RNFL) defects and the degree of myopia in patients with normal-tension glaucoma (NTG). Methods We retrospectively reviewed medical records of patients with high myopia (42 eyes; spherical equivalent [SE]?RNFL defects. On RNFL photographs, the proximity of the RNFL defect to the center of the fovea (angle I) and the sum of the angular width of the defects (angle II) were determined. The patterns of localized RNFL defects were then compared with respect to differences in angles I and II. Results Angle I was significantly smaller in the high myopia group than in the low to moderate myopia group (p?=?0.028) and the emmetropia group (p?=?0.044), while angle II was significantly larger in the high myopia group compared with the low to moderate myopia group and the emmetropia group (p?RNFL defects are wider and closer to the fovea in eyes with high myopia than those with low to moderate myopia or emmetropia.

2013-01-01

57

A review: Fibre metal laminates, background, bonding types and applied test methods  

Microsoft Academic Search

During the past decades, increasing demand in aircraft industry for high-performance, lightweight structures have stimulated a strong trend towards the development of refined models for fibre-metal laminates (FMLs). Fibre metal laminates are hybrid composite materials built up from interlacing layers of thin metals and fibre reinforced adhesives. The most commercially available fibre metal laminates (FMLs) are ARALL (Aramid Reinforced Aluminium

Tamer Sinmazçelik; Egemen Avcu; Mustafa Özgür Bora; Onur Çoban

2011-01-01

58

COST-EFFECTIVE APPROACH FOR THE MANUFACTURE OF FIBRE METAL LAMINATES (FML)  

Microsoft Academic Search

The present work discusses an improved process for the manufacture of fibre metal laminates. Fibre metal laminates are super composite materials combining several properties of fibre and metal layers that constitute them and having potential applications in engineering industry and general purpose industrial applications. Literature information available for preparation of fibre metal laminate are expensive and require huge investment for

B. S. Sugun; RMVGK Rao; D V Venkatasubramanyam

2008-01-01

59

Peripapillary retinal nerve fiber layer thickness distribution in Chinese with myopia measured by 3D-optical coherence tomography  

PubMed Central

AIM To assess the effect of myopia on the thickness of retinal nerve fiber layer (RNFL) measured by 3D optical coherence tomography (3D-OCT) in a group of nonglaucomatous Chinese subjects. METHODS Two hundred and fifty-eight eyes of 258 healthy Chinese myopic individuals were recruited and four groups were classified according to their spherical equivalent (SE): low myopia (n=42, -0.5DRNFL thickness profile including superior, nasal, inferior and temporal quadrant and each of the 12 clock-hour thicknesses were measured by 3D-OCT. The RNFL thicknesses among four sample groups were performed by one-way analysis of variance (one-way ANOVA) and least significant difference test (LSD test). Correlations between RNFL thickness and axial length/spherical equivalent were performed by linear regression analysis. RESULTS The overall RNFL parameters shown significant differences between groups excluding 7, 9, 10, 11 o'clock hour thickness. The RNFL thickness of superior, nasal, inferior, average and 1, 2, 3, 4, 5, 6, 12 o'clock sectors were decreased with the increasing axial length and higher degree of myopia. In contrast, as axial length and the degree of myopia increased, the temporal and 8, 9 o'clock sectors thicknesses were increased. A considerable proportion of myopic eyes were classified as outside the normal limits. Six o'clock was the most notable of the total, which 43.4% were outside the normal limits. CONCLUSION On the measurement of RNFL, the characteristics of RNFL with the change of the degree of myopia were observed. As the degree of myopia increases, the RNFL thickness measured by 3D-OCT including the average and superior, nasal, inferior sectors decreases. And due to the change of RNFL thickness, it should be considered when using OCT to access for the damage of glaucoma especially people with myopia.

Zhao, Jing-Jing; Zhuang, Wen-Juan; Yang, Xue-Qiu; Li, Shan-Shan; Xiang, Wei

2013-01-01

60

Fatigue initiation in fibre metal laminates  

Microsoft Academic Search

It is assumed that fatigue crack initiation in Fibre Metal Laminates is determined by the stress cycles in the metal layers only. It is further assumed that if the stress cycles in the metal layers are known, the fatigue initiation life can be established using S–N data available for the given metal alloy.The internal stresses in the aluminium layers of

J. J. Homan

2006-01-01

61

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

PubMed Central

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.

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

2014-01-01

62

Optical coherence tomography, frequency-doubling technology, and colour Doppler imaging in ocular hypertension  

Microsoft Academic Search

PurposeTo study in ocular hypertension (OH) the retinal nerve fibre layer (RNFL) with optical coherence tomography (OCT) and the neuronal function with frequency-doubling technology (FDT) to assess which of the two methods was more sensitive in detecting early glaucomatous damage. Furthermore, a colour Doppler imaging (CDI) of the optic nerve was carried out to highlight any correlation with RNFL thickness

M Cellini; B Bernabini; M Carbonelli; E Zamparini; E C Campos

2007-01-01

63

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

Microsoft Academic Search

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

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

2007-01-01

64

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

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

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

65

Opening up optical fibres.  

PubMed

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

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

2007-09-17

66

Use of Fourier-domain OCT to detect retinal nerve fiber layer degeneration in Parkinson's disease patients  

PubMed Central

Purpose To demonstrate axonal loss in the retinal nerve fiber layer (RNFL) of patients with Parkinson's disease (PD) and to evaluate the ability of Fourier-domain optical coherence tomography (OCT) to detect RNFL degeneration and retinal thinning in these patients. Methods PD patients (n=100) and healthy subjects (n=100) were included in the study and underwent visual acuity, color vision, and OCT examinations using two next-generation Fourier-domain devices (Spectralis and Cirrus). Differences in the RNFL thicknesses were compared between patients and controls. Results RNFL thicknesses were significantly reduced in PD patients compared with healthy subjects, especially those obtained using the Spectralis OCT, in the inferotemporal quadrant (155.6±16.5??m in healthy eyes vs 142.1±24.9??m in patients, P=0.040) and in the superotemporal quadrant (142.6±20.9??m in healthy eyes vs 132.77±18.6??m in PD patients, P=0.046). Significant differences were observed between controls and patients in relation to mean macular thickness (P=0.031), foveal thickness (P=0.030), and inferior outer thickness (P=0.019). Conclusion PD is associated with RNFL loss and retinal thinning, which is detectable by Fourier-domain OCT measurements.

Satue, M; Garcia-Martin, E; Fuertes, I; Otin, S; Alarcia, R; Herrero, R; Bambo, M P; Pablo, L E; Fernandez, F J

2013-01-01

67

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

PubMed Central

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.

Park, Yi-Ryeung

2014-01-01

68

Photonic crystal fibres  

Microsoft Academic Search

Photonic crystal fibres have wavelength-scale morphological microstructure running down their length. This structure enables light to be controlled within the fibre in ways not previously possible or even imaginable. Our understanding of what an optical fibre is and what it does is changing because of the development of this new technology, and a broad range of applications based on these

Jonathan C. Knight

2003-01-01

69

CW bismuth fibre laser  

Microsoft Academic Search

A new fibre laser based on a bismuth-doped aluminosilicate glass fibre is proposed and fabricated. CW lasing is obtained in the spectral region between 1150 and 1300 nm. The fibres are fabricated by the method of modified chemical vapour deposition. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text

Evgenii M. Dianov; V. V. Dvoyrin; V. M. Mashinsky; A. A. Umnikov; M. V. Yashkov; A. N. Gur'yanov

2005-01-01

70

Retinal Nerve Fiber Layer Thinning in CADASIL: An Optical Coherence Tomography and MRI Study  

Microsoft Academic Search

Background and Purpose: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is considered a genetic form of small-vessel disease causing subcortical dementia. A relevant role of axonal injury was recently proposed to explain disability and cognitive decline in this disease. The retinal nerve fiber layer (RNFL) is the only part of the brain where unmyelinated axons can be

Alessandra Rufa; Elena Pretegiani; Paolo Frezzotti; Nicola De Stefano; Gabriele Cevenini; Maria Teresa Dotti; Antonio Federico

2011-01-01

71

Delamination Resistance of Post-Stretched Fibre Metal Laminates  

Microsoft Academic Search

Fibre Metal Laminates (FML) consist of bonded alternating thin aluminium and fibre\\/epoxy layers. Post-stretching of FML after curing is accompanied by plastic deformation which causes a reversal of the internal stresses due to curing which is favourable for their fatigue properties. The influence of this post-stretching on the delamination resistance was studied. The GI, of FML with aramid fibre (ARALL)

A. Vlot; J. W. Van Ingen

1998-01-01

72

Blood Vessel Contributions to Retinal Nerve Fiber Layer Thickness Profiles Measured With Optical Coherence Tomography  

PubMed Central

Purpose To understand better the influence of retinal blood vessels (BVs) on the interindividual variation in the retinal nerve fiber layer (RNFL) thickness measured with optical coherence tomography (OCT). Subjects and Methods RNFL thickness profiles were measured by OCT in 16 control individuals and 16 patients. The patients had advanced glaucoma defined by abnormal disc appearance, abnormal visual fields, and a mean visual field deviation worse than ? 10 dB. Results In general, the OCT RNFL thickness profiles showed 4 local maxima, with the peak amplitudes in the superior and inferior regions occurring in the temporal (peripapillary) disc region. There was considerable variability among individuals in the location of these maxima. However, the 4 maxima typically fell on, or near, a major BV with the temporal and inferior peaks nearly always associated with the main temporal branches of the superior and inferior veins and arteries. In the patients’ hemifields with severe loss (mean visual field deviation worse than ? 20 dB), the signals associated with the major BVs were in the order of 100 to 150 µm. Conclusions The variation in the local peaks of the RNFL profiles of controls correlates well with the location of the main temporal branches of the superior and inferior veins and arteries. This correspondence is, in part, due to a direct BV contribution to the shape of the OCT RNFL and, in part, due to the fact that BVs develop along the densest regions of axons. Although the overall BV contribution was estimated to be relatively modest, roughly 13% of the total peripapillary RNFL thickness in controls, their contribution represents a substantial portion locally and increases in importance with disease progression.

Hood, Donald C.; Fortune, Brad; Arthur, Stella N.; Xing, Danli; Salant, Jennifer A.; Ritch, Robert; Liebmann, Jeffrey M.

2010-01-01

73

Retinal Nerve Fiber Layer Thickness in Children with Optic Pathway Gliomas  

PubMed Central

Purpose To determine the relation of high-contrast visual acuity (VA) and low-contrast letter acuity with retinal nerve fiber layer (RNFL) thickness in children with optic pathway gliomas. Design Cross-sectional convenience sample, with prospective data collection, from a tertiary care children’s hospital of patients with optic pathway gliomas associated with Neurofibromatosis type 1, sporadic OPG and Neurofibromatosis type 1 without OPG. Methods Patients performed best corrected VA testing using surrounded HOTV optotypes and low-contrast letter acuity (5%, 2.5% and 1.25% low contrast Sloan letter charts). Mean RNFL thickness (microns) was measured by a Stratus optical coherence tomography (Carl Zeiss Meditec, Dublin, CA) using the fast RNFL thickness protocol. Eyes were classified as having abnormal vision if they had high-contrast VA > 0.1 logMAR or visual field loss. The association of subject age, glioma location and RNFL thickness with both VA and low-contrast letter acuity scores was evaluated by one-way analysis of variance and linear regression, using the generalized estimating equation approach to account for within-patient intereye correlations. Results Eighty-nine eyes of patients with optic pathway gliomas were included and 41 were classified as having abnormal VA or visual field loss. Reduced RNFL thickness was significantly associated with higher logMAR scores for both VA (P < 0.001) and all low-contrast letter acuity charts (P < 0.001) when accounting for age and glioma location. Conclusions Eyes of most children with optic pathway gliomas and decreased RNFL thickness had abnormal visual acuity or visual field loss.

Avery, Robert A.; Liu, Grant T.; Fisher, Michael J.; Quinn, Graham E.; Belasco, Jean B.; Phillips, Peter C.; Maguire, Maureen G.; Balcer, Laura J.

2010-01-01

74

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

Microsoft Academic Search

GLARE laminates are an advanced hybrid material system consisting of alternating layers of thin aluminium sheets and unidirectional or biaxial reinforced high strength glass fibre\\/epoxy composite layers. The unique combination of ductile aluminium layers with high strength composite layers results in a unique fibre-metal laminate (FML) having light weight, outstanding fatigue resistance, excellent impact resistance, flame resistance and corrosion properties.

Guocai Wu; Jenn-Ming Yang

2005-01-01

75

Retinal nerve fiber layer evaluation in multiple sclerosis with spectral domain optical coherence tomography  

PubMed Central

Purpose: Histopathologic studies have reported retinal nerve fiber layer (RNFL) thinning in various neurodegenerative diseases. Attempts to quantify this loss in vivo have relied on time-domain optical coherence tomography (TDOCT), which has low resolution and requires substantial interpolation of data for volume measurements. We hypothesized that the significantly higher resolution of spectral-domain optical coherence tomography (SDOCT) would better detect RNFL changes in patients with multiple sclerosis, and that RNFL thickness differences between eyes with and without optic neuritis might be identified more accurately. Methods: In this retrospective case series, patients with multiple sclerosis were recruited from the Judith Jaffe Multiple Sclerosis Center at Weill Cornell Medical College in New York. Patients with a recent clinical diagnosis of optic neuritis (less than three months) were excluded. Eyes with a history of glaucoma, optic neuropathy (other than multiple sclerosis-related optic neuritis), age-related macular degeneration, or other relevant retinal and/or optic nerve disease were excluded. Both eyes of each patient were imaged with the Heidelberg Spectralis® HRA + OCT. RNFL and macular thickness were measured for each eye using the Heidelberg OCT software. These measurements were compared with validated published normal values, and were modeled as linear functions of duration of disease. The odds of an optic neuritis diagnosis as a function of RNFL and macular thickness were calculated. Results: Ninety-four eyes were prospectively evaluated using OCT. Ages of patients ranged from 26 to 69 years, with an average age of 39 years. Peripapillary RNFL thinning was demonstrated in multiple sclerosis patients; mean RNFL thickness was 88.5 ?m for individuals with multiple sclerosis compared with a reported normal value of 97 ?m (P < 0.001). Eyes with a history of optic neuritis had more thinning compared with those without optic neuritis (83.0 ?m versus 90.5 ?m, respectively, P = 0.02). No significant differences were observed in macular thickness measurements between eyes with and without optic neuritis, nor were macular thickness measurements significantly different from normal values. As a function of multiple sclerosis duration and controlling for age, RNFL thickness was decreased in patients with a duration of multiple sclerosis greater than five years compared with those with a duration less than or equal to one year (P = 0.008). Conclusions: Patients with a history of multiple sclerosis had RNFL thinning that was detectable on SDOCT. Decreasing RNFL thickness in eyes with optic neuritis was found, and the odds of having optic neuritis were increased significantly with decreasing RNFL thickness. Average RNFL thinning with increasing duration of disease was an excellent predictor of a reported history of optic neuritis. SDOCT retinal imaging may represent a high-resolution, objective, noninvasive, and easily quantifiable in vivo biomarker of the presence of optic neuritis and severity of multiple sclerosis.

Khanifar, Aziz A; Parlitsis, George J; Ehrlich, Joshua R; Aaker, Grant D; D'Amico, Donald J; Gauthier, Susan A; Kiss, Szilard

2010-01-01

76

Fibre optics: Forty years later  

SciTech Connect

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)

Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2010-01-31

77

Towards application of fibre metal laminates in large aircraft  

Microsoft Academic Search

Fibre metal laminates were developed at Delft University during the last two decades as a family of new hybrid materials consisting of bonded thin metal sheets and fibre\\/adhesive layers. This laminated structure provides the material with excellent fatigue, impact and damage tolerance characteristics and a low density. While the 20 per cent weight reduction was the prime driver behind the

A. Vlot; L. B. Vogelesang; T. J. de Vries

1999-01-01

78

Developments in hollow fibre-based, liquid-phase microextraction  

Microsoft Academic Search

The demand for automation in analytical liquid-liquid extraction (LLE) combined with organic solvent reduction or elimination has led to the recent development of liquid-phase microextraction (LPME) based on disposable hollow fibres. In this concept, analytes of interest are extracted from aqueous samples, through a thin layer of organic solvent immobilized within the pores of a porous hollow fibre, and into

Knut Einar Rasmussen; Stig Pedersen-Bjergaard

2004-01-01

79

Dual-band spectral-domain optical coherence tomography for in vivo imaging the spectral contrasts of the retinal nerve fiber layer.  

PubMed

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 (<560 nm) is reduced much more than that at long wavelength, which provides spectral contrast for imaging the earliest damage to the RNFL. To image the spectral contrast we built a dual-band spectral-domain optical coherence tomography (SD-OCT) centered at 808 nm (NIR) and 415 nm (VIS). The light at the two bands was provided by the fundamental and frequency-doubled outputs of a broadband Ti:Sapphire laser. The depth resolution of the NIR and VIS OCT systems are 4.7 µm and 12.2 µm in the air, respectively. The system was applied to imaging the rat retina in vivo. Significantly different appearances between the OCT cross sectional images at the two bands were observed. The ratio of the light reflected from the RNFL over that reflected from the entire retina at the two bands were quantitatively compared. The experimental results showed that the dual-band OCT system is feasible for imaging the spectral contrasts of the RNFL. PMID:21996906

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

2011-09-26

80

Dual-band spectral-domain optical coherence tomography for in vivo imaging the spectral contrasts of the retinal nerve fiber layer  

PubMed Central

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 contrast for imaging the earliest damage to the RNFL. To image the spectral contrast we built a dual-band spectral-domain optical coherence tomography (SD-OCT) centered at 808nm (NIR) and 415nm (VIS). The light at the two bands was provided by the fundamental and frequency-doubled outputs of a broadband Ti:Sapphire laser. The depth resolution of the NIR and VIS OCT systems are 4.7µm and 12.2µm in the air, respectively. The system was applied to imaging the rat retina in vivo. Significantly different appearances between the OCT cross sectional images at the two bands were observed. The ratio of the light reflected from the RNFL over that reflected from the entire retina at the two bands were quantitatively compared. The experimental results showed that the dual-band OCT system is feasible for imaging the spectral contrasts of the RNFL.

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

2011-01-01

81

Genetic Contributions to Glaucoma: Heritability of Intraocular Pressure, Retinal Nerve Fiber Layer Thickness, and Optic Disc Morphology  

Microsoft Academic Search

PURPOSE. The genetic etiology of primary open-angle glaucoma (POAG) is still largely unknown, because of its complexity and disparities in its classification. This study was undertaken to determine the genetic contribution to various early, continu- ous markers of POAG by assessing the heritability of intraocular pressure (IOP), retinal nerve fiber layer (RNFL) thickness, and neuroretinal rim and optic disc parameters

Leonieke M. E. van Koolwijk; Dominiek D. G. Despriet; Cornelia M. van Duijn; Luba M. Pardo Cortes; Johannes R. Vingerling; Yurii S. Aulchenko; Ben A. Oostra; Caroline C. W. Klaver; Hans G. Lemij

2007-01-01

82

Track reconstruction with a central two-shell scintillating fibre tracker (SFT)  

Microsoft Academic Search

We present a track reconstruction algorithm designed for the scintillating fibre tracker (SFT), having in view the upgrade of the L3 detector for LEP-II. This algorithm can also be applied for particle tracking at future hadron colliders. The tracking elements are polystyrene fibres of 60 mum diameter, which are arranged as fused coherent bundles into fibre layers. We study in

F. Anselmo; F. Block; Luisa Cifarelli; C. D'Ambrosio; Thierry Gys; G. La Commare; H. Leutz; M. Marino; S. Qian

1994-01-01

83

Effect of oral isotretinoin treatment on retinal nerve fiber layer thickness.  

PubMed

Background:Oral isotretinoin treatment can cause ocular side effects.Objective:This study was performed to detect possible toxic effects of oral isotretinoin treatment on the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL).Methods:The study population consisted of 54 eyes of 27 patients with nodulocystic acne who used oral isotretinoin (Roaccutane) treatment. Macular GCL and peripapillary RNFL thickness measurements were performed using spectral domain optical coherence tomography (OCT) before and after therapy.Results:Before and after treatment, a complete ophthalmologic examination was normal in all eyes. However, posttreatment lower temporal (TL) values were significantly lower (76.80 ± 16.31) than pretreatment TL values (84.96 ± 24.83) (p ?=? .02). There was no statistically significant difference in the other OCT values, upper temporal, superotemporal, superonasal, upper nasal, lower nasal, inferonasal, and inferotemporal (p ?=? .35, p ?=? .40, p ?=? .56, p ?=? .95, p ?=? .94, p ?=? .93, p ?=? .61, respectively). Also, there was no statistically significant difference between the right and left eyes and between genders for all parameters (p > .05).Conclusion:The use of oral isotretinoin treatment has increased in recent years. In addition, oral isotretinoin treatment has a broad adverse effect potential on the ocular system. The measurement of RNFL thickness, especially TL thickness, by OCT may be useful for detecting the possible toxic effect of oral isotretinoin therapy on RNFL. PMID:24518137

Ucak, Haydar; Aykut, Veysel; Ozturk, Savas; Cicek, Demet; Erden, Ilker; Demir, Betul

2014-01-01

84

Evaluation of Inner Retinal Layers in Patients with Multiple Sclerosis or Neuromyelitis Optica Using Optical Coherence Tomography  

PubMed Central

Purpose To evaluate the thickness of the inner retinal layers in the macula using frequency domain-optical coherence tomography (fd-OCT) in patients with demyelinating diseases. Design Cross sectional study Participants 301 eyes of 176 subjects were evaluated. Subjects were divided in 5 different groups: controls, neuromyelitis optica (NMO), longitudinally extensive transverse myelitis (LETM), multiple sclerosis with (MS-ON) and without (MS non-ON) history of optic neuritis, respectively. Methods The individual layers from macular fd-OCT cube scans were segmented with an automated algorithm, and then manually hand-corrected. For each scan, we determined the thickness of the retinal nerve fiber layer (RNFL), the combined retinal ganglion cell and inner plexiform layers (RGCL+), and the inner nuclear layer (INL). Main outcome measures Macular RNFL, RGCL+ and INL thickness Results The RNFL was significantly thinner than controls for all patient groups (p?0.01). Macular RGCL+ thickness was significantly thinner than controls for the NMO, MS-ON and MS non-ON (p<0.001 for the 3 groups). The INL thickness was significantly thicker than controls for the NMO (p=0.003) and LETM (p=0.006) patients but not for MS-ON or MS non-ON. While the RNFL and RGCL+ were not significantly different between the NMO and MS-ON groups, the NMO patients had a significantly thicker INL than the MS-ON (p=0.02) patients. Conclusion Macular RNFL and RGCL+ demonstrate axonal and neural loss in MS, either with or without ON, and in NMO patients. In addition, the INL thickening occurs in NMO and LETM patients and study of this layer may hold promise for differentiating between NMO and MS.

Fernandes, Danilo B.; Raza, Ali S.; Nogueira, Rafael; Wang, Diane; Callegaro, Dagoberto; Hood, Donald C.; Monteiro, Mario L. R.

2012-01-01

85

Retinal nerve fiber layer and ganglion cell layer thickness in patients receiving systemic isotretinoin therapy.  

PubMed

To evaluate the effect of oral isotretinoin therapy on retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness by spectral domain optical coherence tomography (OCT). This prospective study included newly diagnosed nodulocystic acne patients about to receive isotretinoin treatment. Macular average GCL thickness and peripapillary average, temporal, nasal, inferior, and superior quadrant RNFL thickness were measured by OCT before and after isotretinoin treatment. Pre- and post-treatment measurements were compared with paired t test. Fifty-six eyes of 28 patients were included. The mean duration of the treatment was 6.5 ± 1.3 months. The mean average GCL thickness was 90.04 ± 5.87 (80-96) ?m at baseline and 90.75 ± 6.34 (81-96) ?m after treatment. The mean average RNFL thickness was 93.25 ± 6.06 ?m (84-107) before treatment and 93.05 ± 5.54 ?m (82-106) after treatment. There were no statistically significant differences between pre- and post-treatment values (all p > 0.05). A 6-month course of systemic isotretinoin therapy seems to have no unfavorable effect on retinal ganglion cells; however, larger studies with longer follow-up periods are needed to be conclusive. PMID:23338233

Sekeryapan, Berrak; D?lek, Nursel; Oner, Veysi; Turky?lmaz, Kemal; Aslan, Mehmet Gokhan

2013-10-01

86

Impact Damage Resistance of Various Fibre Metal Laminates  

Microsoft Academic Search

The impact damage resistance of Fibre Metal Laminates (FML) is studied. FML is a new family of laminated materials which consist of thin aluminium layers bonded together by intermediate fibrelepoxy layers. Different glass fibre FML variants are compared with A1 2024-T3, and carbodPEI composites. The effect of the relative glasslepoxy content in FML is determined. FML shows an equal to

A. Vlot; M. Krull

1997-01-01

87

Agreement of Two Different Spectral Domain Optical Coherence Tomography Instruments for Retinal Nerve Fiber Layer Measurements  

PubMed Central

Purpose To determine the agreement between Spectralis and Cirrus spectral domain optical coherence tomography (SD-OCT) measurements of peripapillary retinal nerve fiber layer (RNFL) thickness. Methods Suspected or confirmed cases of glaucoma who met the inclusion criteria underwent peripapillary RNFL thickness measurement using both the Spectralis and Cirrus on the same day within a few minutes. Results Measurements were performed on 103 eyes of 103 patients with mean age of 50.4±17.7 years. Mean RNFL thickness was 89.22±15.87 versus 84.54±13.68 µm using Spectralis and Cirrus, respectively. The difference between measurements and the average of paired measurements with the two devices showed a significant linear relationship. Bland-Altman plots demonstrated that Spectralis thickness values were systematically larger than that of Cirrus. Conclusion Spectralis OCT generates higher peripapillary RNFL thickness readings as compared to Cirrus OCT; this should be kept in mind when values obtained with different instruments are compared during follow-up.

Faghihi, Hooshang; Hajizadeh, Fedra; Hashemi, Hassan; Khabazkhoob, Mehdi

2014-01-01

88

Endometrial nerve fibre density in patients undergoing IVF: a pilot study.  

PubMed

The presence of nerve fibres in the functional layer of the endometrium has been strongly associated with endometriosis. Presence of nerve fibres in the endometrium of women undergoing IVF has not been previously assessed. This prospective pilot study assessed the presence of nerve fibres in endometrium of women undergoing IVF due to various causes and examined the correlation between the presence of nerve fibres and IVF success. A total of 32 IVF patients underwent endometrial biopsy during days 21-23 of the menstrual cycle. Nerve fibres were identified by immunohistochemical staining. Correlations between the presence and density of nerve fibres and aetiology of infertility and IVF success were measured. Nerve fibres were identified in the endometrium of 10/31 (32.3%) women with a satisfactory biopsy. Presence of nerve fibres was not correlated with cause of infertility. Clinical pregnancy was achieved in 12/32 (37.5%) patients, without correlation to presence of nerve fibres in the endometrium. Nerve fibres were identified in a substantial percentage of women undergoing IVF, possibly reflecting underdiagnosis of endometriosis in this population. The presence of nerve fibres does not appear to interfere with implantation. The significance of nerve fibres in the endometrium of IVF patients warrants further research. The presence of nerve fibres in the functional layer of the endometrium has been strongly associated with endometriosis. The presence of nerve fibres in the endometrium of women undergoing IVF has not been previously assessed. Our aim was to assess the presence of nerve fibres in endometrium of women with various causes of infertility undergoing IVF and to examine the association between the presence of nerve fibres in the endometrium and IVF success. In a prospective study, 32 IVF patients underwent endometrial biopsy during days 21-23 of the menstrual cycle. Nerve fibres were identified by immunohistochemical staining. Associations between the presence and density of nerve fibres and the aetiology of infertility and IVF success were measured. Nerve fibres were identified in the endometrium of 10/31 (32.3%) women with a satisfactory biopsy. No association was found between the presence of nerve fibres and the cause of infertility. Clinical pregnancy was achieved in 12/32 (37.5%) patients, without association with the presence of nerve fibres in the endometrium. Nerve fibres can be identified in a substantial percentage of women undergoing IVF, possibly reflecting underdiagnosis of endometriosis in this population. Their presence does not interfere with embryo implantation. The significance of nerve fibres in the endometrium of IVF patients warrants further research. PMID:24745833

Wand, Suzanna; Weissman, Ariel; Sagiv, Ron; Schreiber, Letizia; Boaz, Mona; Horowitz, Eran; Ravhon, Amir; Seadia, Sarit; Barkat, Jonathan; Golan, Abraham; Lavran, David

2014-06-01

89

The MICE scintillating-fibre tracker  

NASA Astrophysics Data System (ADS)

The international Muon Ionization Cooling Experiment (MICE) collaboration will carry out a systematic investigation of the ionization cooling of a muon beam. An ionization cooling channel is required to compress the phase-space volume occupied by the muon beam prior to acceleration in the baseline conceptual designs for both the Neutrino Factory and the Muon Collider. Muons entering and leaving the cooling channel will be measured in two solenoidal spectrometers, each of which is instrumented with a scintillating-fibre tracker. Each tracker is composed of five planar scintillating fibre stations, each station being composed of three planar layers of 350 micron scintillating fibres. The devices will be read out using the Visible Light Photon Counters (VLPCs) developed for use in the D0 experiment at the Tevatron. The design of the system will be presented along with the status of the tracker-construction project. The expected performance of prototypes of the full tracker will be summarised.

Matsushita, T.

2008-06-01

90

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

PubMed Central

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 ?m thicker than the left on the standard scan (SD 4.7, 95% CI 0.4–2.2, P = .004) and 1.2 ?m 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 ?m with the standard scan algorithm and ?10.6 and +11.7 ?m 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 ?m, 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.

Budenz, Donald L.

2008-01-01

91

Cellulose Fibre Concrete.  

National Technical Information Service (NTIS)

In this investigation concretes and mortars containing different kinds of cellulose fibers were developed. The aim was to select suitable types of fibers for various kinds of concrete products. Four types of cellulose fibres and three manufacturing method...

S. Vares L. Sarvaranta M. Lanu

1997-01-01

92

Fibre laser directions  

NASA Astrophysics Data System (ADS)

Nature Photonics spoke to Anatoly Grudinin, founder of the fibre laser company Fianium, to gain insight into the vicissitudes in the industry over the past decade and future challenges that academia can help solve.

2013-11-01

93

Ultrafast fibre lasers  

NASA Astrophysics Data System (ADS)

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

Fermann, Martin E.; Hartl, Ingmar

2013-11-01

94

Fibre Centred Tensor Faces  

Microsoft Academic Search

In this paper we present a reformulation of the tensorface analysis method and produce a model that is simpler (i.e. has fewer parameters), is more compact (i.e. has tighter distributions) and is less ambiguous (i.e. no 2 sets of parameters synthesise the same data vector). This is achieved by simply subtracting the fibre (row, column, etc) mean from each fibre

Bernard Tiddeman; Meng Yu; David Hunter

2007-01-01

95

The Relationship between Visual Field and Retinal Nerve Fiber Layer Measurements in Patients with Multiple Sclerosis  

PubMed Central

Purpose To investigate the relationship between visual function, measured by standard automated perimetry (SAP), and retinal nerve fiber layer (RNFL) thickness, measured by optical coherence tomography (OCT), in patients with multiple sclerosis (MS). Methods SAP and RNFL thickness were measured in patients with MS in 28 eyes with the last optic neuritis (ON) ?6 months prior (ON group) and 33 eyes without ON history (non-ON group). Abnormal overall or quadrant RNFL thickness was defined by measured values below 5% of the norm. A whole visual field or a sector of the field was classified as abnormal by using cluster criteria on total-deviation plots. Agreement between SAP and OCT results in classifying eyes/sectors was presented as a percentage of observed agreement, along with the AC1 statistic, which corrects for chance agreement. Regression analyses were performed relating several SAP parameters and RNFL thickness in the ON group. Results ON eyes showed more loss of visual sensitivity (MD, P = 0.02) and more loss of RNFL thickness (P < 0.0001) than did non-ON eyes. SAP and OCT agreed in 86% (AC1 = 0.78) of eyes and 69% (AC1 = 0.38) of sectors in the ON group and 61% (AC1 = 0.33) of eyes and 66% (AC1 = 0.48) of sectors in the non-ON group. Overall RNFL thickness was related to MD (dB) by a simple exponential function (R2 = 0.48), supporting a linear relationship between these measures when both are expressed on linear scales. Absolute Pearson correlation coefficients for overall RNFL thickness and several SAP parameters ranged from 0.51 to 0.69. Conclusions Good agreement between SAP and OCT was found in ON eyes but not in non-ON eyes or in individual sectors in either group. The findings in this study provide further support for the utility of combining structural and functional testing in clinical research on patients with MS, as well as in future neuroprotection trials for which the anterior visual pathways in patients with MS and optic neuritis may be used as a model.

Cheng, Han; Laron, Michal; Schiffman, Jade S.; Tang, Rosa A.; Frishman, Laura J.

2010-01-01

96

Inner Nuclear Layer Thickening Is Inversley Proportional to Retinal Ganglion Cell Loss in Optic Neuritis  

PubMed Central

Aim To examine the relationship between retinal ganglion cell loss and changes in the inner nuclear layer (INL) in optic neuritis (ON). Methods 36 multiple sclerosis (MS) patients with a history of ON and 36 age and sex-matched controls underwent Optical Coherence Tomography. The paramacular retinal nerve fiber layer (RNFL), combined ganglion cell and inner plexiform layers (GCL/IPL) and inner nuclear layer (INL) thickness were measured at 36 points around the fovea. To remove inter-subject variability, the difference in thickness of each layer between the ON and fellow eye of each patient was calculated. A topographic analysis was conducted. Results The INL of the ON patients was thicker than the controls (42.9µm versus 39.6µm, p=0.002). ON patients also had a thinner RNFL (27.8µm versus 32.2µm, p<0.001) and GCL/IPL (69.3µm versus 98.1µm, p<0.001). Among the controls, there was no correlation between RNFL and GCL/IPL as well as RNFL and INL, but a positive correlation was seen between GCL/IPL and INL (r=0.65, p<0.001). In the ON group, there was a positive correlation between RNFL and GCL/IPL (r=0.80, p<0.001) but a negative correlation between RNFL and INL (r=-0.61, p<0.001) as well as GCL/IPL and INL (r=-0.44, p=0.007). The negative correlation between GCL/IPL and INL strengthened in the ON group when inter-subject variability was removed (r=-0.75, p<0.001). Microcysts within the INL were present in 5 ON patients, mainly in the superior and infero-nasal paramacular regions. While patients with microcysts lay at the far end of the correlation curve between GCL/IPL and INL (i.e. larger INL and smaller GCL/IPL compared to other patients), their exclusion did not affect the correlation (r= -0.76, p<0.001). Conclusions INL enlargement in MS-related ON is associated with the severity of GCL loss. This is a continuous relationship and patients with INL microcysts may represent the extreme end of the scale.

Kaushik, Megha; Wang, Chen Yu; Barnett, Michael H.; Garrick, Raymond; Parratt, John; Graham, Stuart L.; Sriram, Prema; Yiannikas, Con; Klistorner, Alexandr

2013-01-01

97

Reproducibility of Optical Coherence Tomography Retinal Nerve Fiber Layer Thickness Measurements Before and After Pupil Dilation  

PubMed Central

Purpose To evaluate the intra- and interobserver reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness measurements before and after pupil dilation using spectral-domain optical coherence tomography (SD-OCT). Methods In this observational case series, 44 eyes of 44 healthy subjects were scanned by two trained operators on the same day, using Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA, USA). Three scans were obtained before and after pupil dilation by each operator. Mean ± standard deviation (SD) and coefficient of variation (CV) were used for description of results and variation of measurements respectively. Intraclass correlation coefficients (ICC) and Bland-Altman plots were used to evaluate validation and limits of agreement. Results Overall, 23 female and 21 male subjects with mean age of 36.9±8.8 (range, 20 to 50) years were enrolled. Mean RNFL thickness before pupil dilation was 92.6±7.2 (CV, 7.8%) and 92.4±6.8 (CV, 7.4%) µm by operator one and two, respectively. After pupil dilation, mean RNFL thickness was 92.7±7.9 (CV, 8.5%) and 92.0±7.5 (CV=8.2%) µm by observer one and two, respectively. ICCs ranged from 0.900 to 0.996. Mean absolute error of the two operators was less than 4.1µm. There were no significant differences in quadrant thicknesses before and after dilation. Interestingly, mean signal strength was not significantly affected by pupil dilation. Conclusion In normal subjects with clear media, peripapillary RNFL thickness measurements using Cirrus SD-OCT have high inter- and intraobserver reproducibility before and after pupil dilation. Pupil dilation may not be necessary in all subjects to obtain reproducible RNFL thickness measurements.

Alizadeh, Yousef; Panjtanpanah, Mohammad Reza; Mohammadi, Mohammad Javad; Behboudi, Hassan; Kazemnezhad Leili, Ehsan

2014-01-01

98

Perimetric and retinal nerve fiber layer findings in patients with Parkinson's disease  

PubMed Central

Background Visual dysfunction is common in Parkinson’s disease (PD). It remains, however, unknown whether it is related to structural alterations of the retina. The aim of this study is to compare visual field (VF) findings and circumpapillary retinal nerve fiber layer (RNFL) thickness in a series of PD patients and normal controls, in order to assess possible retinal anatomical changes and/or functional damage associated with PD. Methods PD patients and controls were recruited and underwent VF testing with static automated perimetry and RNFL examination with optical coherence tomography (OCT). Cognitive performance using Mini Mental State Examination (MMSE), PD staging using modified Hoehn and Yahr (H-Y) scale and duration of the disease was recorded in PD patients. Results One randomly selected eye from each of 24 patients and 24 age-matched controls was included. OCT RNFL thickness analysis revealed no difference in the inferior, superior, nasal or temporal sectors between the groups. The average peripapillary RNFL was also similar in the two groups. However, perimetric indices of generalized sensitivity loss (mean deviation) and localized scotomas (pattern standard deviation) were worse in patients with PD compared to controls (p?RNFL thickness.

2012-01-01

99

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

SciTech Connect

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)

Kurkov, Andrei S; Karpov, V I; Medvedkov, O I; Dianov, Evgenii M; Vasil'ev, Sergei A; Paramonov, Vladimir M; Protopopov, V N [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Laptev, A Yu; Gur'yanov, A N; Umnikov, A A; Vechkanov, N I [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Artyushenko, V G; Frahm, J [Advanced Photonic Systems, APhS GmbH, Berlin (Germany)

1999-06-30

100

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

101

Evaluation of peripapillary retinal nerve fiber layer, macula and ganglion cell thickness in amblyopia using spectral optical coherence tomography  

PubMed Central

AIM To investigate peripapillary retinal nerve fiber layer (RNFL), macula and ganglion cell layer thicknesses (GCC) in amblyopic eyes with spectral domain optical coherence tomography (SD-OCT). METHODS Thirty six patients with a history of unilateral amblyopia and thirty two children who had emmetropia without amblyopia were included in this study. In this institutional study, 36 eyes of 36 patients with amblyopia (AE), 36 fellow eyes without amblyopia (FE), and 32 eyes of 32 normal subjects (NE) were included. RNFL, GCC and macular thickness measurements were performed with RS-3000 OCT Retina Scan (Nidek Inc CA. USA). RESULTS The mean global thicknesses of the RNFL were 113.22±21.47, 111.57±18.25, 109.96±11.31µm in the AE, FE, and NE, respectively. There was no statistically significant difference for mean global RNFL thickness among the eyes (P=0.13). The mean thicknesses of the macula were 258.25±18.31, 258.75±19.54, 248.62±10.57µm in the AE, FE and NE, respectively. There was no statistically significant difference for thickness of macula among the eyes (P=0.06). The GCC was investigated into two parts: superior and inferior. The mean thicknesses of superior GCC were 102.57±13.32, 103.32±10.64, 100.52±5.88µm in the AE, FE, and NE, respectively. The mean thicknesses of inferior GCC were 103.82±12.60, 107.82±12.33, 105.86±10.79µm in the AE, FE and NE, respectively. There was no statistically significant difference for thickness of superior and inferior GCC between the eyes (P=0.63, P=0.46). CONCLUSION The macular thicknesses of AE and FE were greater than the NE, although it was not statistically significant. Amblyopia does not seem to have a profound effect on the RNFL, macula and GCC.

Firat, Penpe Gul; Ozsoy, Ercan; Demirel, Soner; Cumurcu, Tongabay; Gunduz, Abuzer

2013-01-01

102

Myocardial fibre calcification.  

PubMed Central

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

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

1981-01-01

103

Features of the fine structure of aramid fibres  

Microsoft Academic Search

The fine structure of the aramid fibres Armos, SVM, and VMN was investigated by x-ray diffraction. It was found that the fine\\u000a structure of Armos, SVM, and VMN fibres is characterized by rigorous longitudinal ordering due to simultaneous shifting of\\u000a the neighboring macromolecules and the formation of unusual layers as a result. A new methodological approach to the quantitative\\u000a x-ray

A. E. Zavadskii; I. M. Zakharova; Z. N. Zhukova

1998-01-01

104

Numerical Modelling of Fibre Metal Laminates Subjected to Blast Loading  

Microsoft Academic Search

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

Z. W. Guan; W. J. Cantwell

2010-01-01

105

Dietary fibres, fibre analogues, and glucose tolerance: importance of viscosity  

Microsoft Academic Search

To define the type of dietary fibre of fibre analogue with the greatest potential use in diabetic treatment, groups of four to six volunteers underwent 50-g glucose tolerance tests (GTT) with and without the addition of either guar, pectin, gum tragacanth, methylcellulose, wheat bran, or cholestyramine equivalent to 12 g fibre. The addition of each substance significantly reduced blood glucose

D J Jenkins; T M Wolever; A R Leeds; M A Gassull; P Haisman; J Dilawari; D V Goff; G L Metz; K G Alberti

1978-01-01

106

Optic Disc and Nerve Fiber Layer Imaging To Detect Glaucoma  

PubMed Central

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

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

2007-01-01

107

Radioluminescence of some optical fibres.  

PubMed

Measurement of radiation fields with small scintillators as detectors for radiation dose is an attractive method provided that the scintillator luminescence can be discriminated against other unwanted signals. In diagnostic radiology radioluminescence of the optical fibres required for a transmission of the luminescence to an optical detector is the only source for such an impairment of the signal. To find fibres with low radioluminosity a survey of ten commercial fibres including polystyrene (PS), polystyrene wavelength shifting fibres, poly-methylmetacrylate (PMMA) and silica as fibre core material was made. Measurements were made with two photomultipliers of different spectral response and a clinical x-ray unit. Lowest radioluminosity was obtained with PMMA fibres. Depending on spectral sensitivity of the multiplier clear PS fibres give five to ten times the luminescence of PMMA. From the silica fibres only one high-OH fibre gave comparable results for wavelength up to 520 nm. Wavelength shifting fibres and silica fibres with low OH-content show strong fluorescence and are not suitable fibre materials. PMID:17264357

Nowotny, R

2007-02-21

108

Should we eat more fibre?  

PubMed

Controversy continues over the role of dietary fibre in health, and whether or not a standard fibre intake should be recommended for the UK. In this review an attempt is made to consider the evidence for and against making such a recommendation. In doing so, it is clear that many problems exist in studies examining the role of fibre in disease, such as the inherent inadequacies of epidemiological studies and distrust of such studies by some circles, or the lack of uniformity in definition of dietary fibre and in its chemical analysis. The effect of fibre on faecal bulking is given as an example of experimental verification of epidemiological findings which has led to the widespread use of fibre in treating diverticular disease and constipation. Evidence of beneficial effects for cancer of the colon and ischaemic heart disease are far less convincing. Few harmful effects of fibre have been documented, apart from continuing disagreement regarding fibre and mineral balance, a question which remains to be solved. On weighing the evidence, it is suggested that recommending higher-fibre intakes in the UK is a favourable guideline. The type of fibre to be recommended is discussed, based on new evidence of the mode of action of different types of fibre in the gastrointestinal tract, and the amount of fibre considered, in relation to intakes in other countries and in the past in the UK. PMID:6279729

Stephen, A M

1981-12-01

109

Fibring Logics with Topos Semantics  

Microsoft Academic Search

Abstract The concept of fibring is extended to higher-order logics with arbitrary modalities and binding operators. A general completeness theorem is established for such logics including HOL and with the meta-theorem of deduction. As a corollary, completeness is shown to be preserved when fibring such rich logics. This result is extended to weaker logics in the cases where fibring preserves

Marcelo E. Coniglio; Amílcar Sernadas; Cristina Sernadas

2003-01-01

110

Changes in retinal nerve fiber layer thickness following mechanical microkeratome-assisted versus femtosecond laser-assisted LASIK  

PubMed Central

Purpose To study the influence of the transient elevation of intraocular pressure during suction in laser-assisted in situ keratomileusis (LASIK) on the retinal nerve fiber layer (RNFL) thickness both in microkeratome assisted and femotsecond (FS) LASIK. Patients and methods An interventional case series that included 40 eyes suffering from myopia who were candidates for LASIK. All underwent Wave Front Guided LASIK by the same surgeon using the VisX CustomVue platform. A corneal flap was created in 20 eyes using a mechanical microkeratome Moria M2 (MMK), while the IFS IntraLase™ was used in the remaining 20 eyes. Mean suction time was recorded from “Suction ON” to “Suction OFF” time. Optic cube and RNFL thickness analysis using Spectral Domain Optical Coherence Tomography (SD-OCT) Cirrus-HD was completed before, and 1 month after LASIK. Results The study included 40 eyes of 20 patients. All were females with mean age 33.5 ± 6.4 years. Mean preoperative spherical equivalent was ?3.62 ± 2.31D. Average preoperative RNFL thickness was 94.6 ± 12.1?m in MMK group while the postoperative average thickness was 95.1 ± 11.9 um with no statistically significant difference (P-value: 0.37). Average preoperative RNFL thickness was 108.28 ± 8.4 ?m in FS group compared to 108.38 ± 11.2 ?m in the postoperative average with no statistically significant difference (P-value: 0.94). Mean “Suction ON” to “Suction OFF” time was 22 seconds in the MMK group compared to 41 seconds in the FS group. Conclusion The rise of intraocular pressure during application of suction ring in LASIK surgery does not affect the RNFL thickness as measured by SD-OCT, whether the flap is created by MMK or FS.

Hosny, Mohamed; Zaki, Rania M; Ahmed, Rania A; Khalil, Noha; Mostafa, Hoda M

2013-01-01

111

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

PubMed Central

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

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

2014-01-01

112

SpaceFibre Discussion  

NASA Technical Reports Server (NTRS)

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

Rakow, Glenn

2007-01-01

113

Development of Fibre Metal Laminates: concurrent multi-scale modeling and testing  

Microsoft Academic Search

Fibre Metal Laminates (FML) represent a family of hybrid materials, consisting of alternating layers of thin metal sheets\\u000a and fibre reinforced epoxies. The concept, invented in the late 1970s, has resulted in laminates like ARALL and GLARE. The\\u000a first material is made of aluminum alloys, aramid fibres and an epoxy resin, GLARE laminates use similar constituents except\\u000a for the aramid

J. Sinke

2006-01-01

114

Comparison of relation between visual function index and retinal nerve fiber layer structure by optical coherence tomography among primary open angle glaucoma and primary angle closure glaucoma eyes  

PubMed Central

Purpose: To compare the visual field index (VFI) in primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) eyes, and to study the correlation with disc variables on optical coherence tomography (OCT) in all stages of severity. Materials and Methods: Thirty POAG and PACG underwent Humphrey visual field 24-2 along with detailed examination. They also underwent stratus OCT imaging of the optic nerve and retinal nerve fiber layer (RNFL). The correlation of VFI with RNFL thickness was compared in POAG and PACG. Results: The VFI significantly differed between POAG and PACG, with POAG eyes apparently having a better VFI at all severities of glaucoma. There were statistically significant differences in the superior max (Smax) and inferior max (Imax) in early and moderate POAG and PACG eyes. In early and moderate glaucoma, multivariate regression showed that maximum correlation of the VFI was seen with the mean deviation (b = 1.7, P < 0.001), average and superior RNFL thickness (b = 2.1, P < 0.001 and b = 1.8, P = 0.03, respectively), and age (b = 0.7, P = 0.04); while no correlation was seen with intraocular pressure (IOP), axial length, sex, or other clinical variables. VFI did not correlate well with RNFL thickness or other disc variables on OCT in severe glaucoma. Conclusion: VFI may not serve as a useful indicator of visual function in severe glaucoma. More useful indicators are required to monitor glaucoma patients with severe damage.

Rao, Aparna

2014-01-01

115

Numerical Modelling of Fibre Metal Laminates Subjected to Blast Loading  

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

116

A comparison of the mechanical properties of phenol formaldehyde composites reinforced with banana fibres and glass fibres  

Microsoft Academic Search

Composites were fabricated using banana fibre and glass fibre with varying fibre length and fibre loading. The analysis of tensile, flexural and impact properties of these composites revealed that the optimum length of fibre required for banana fibre and glass fibre are different in phenol formaldehyde resole matrix. Both banana fibre and glass fibre reinforced composites show a regular trend

Seena Joseph; M. S Sreekala; Z Oommen; P Koshy; Sabu Thomas

2002-01-01

117

The fibre pull-out energy of misaligned short fibre composites  

Microsoft Academic Search

A theoretical study on the fibre pull-out energy has been carried out for short fibre-reinforced composites. Two probability\\u000a density functions were introduced for modelling the fibre-length distribution and the fibre-orientation distribution. By taking\\u000a into account the effect of snubbing friction between fibres and matrix at the fibre exit point during fibre pull-out, and\\u000a that of the fracture stress of fibres

SHAO-YUN FU; BERND LAUKE

1997-01-01

118

Predicting the effects of geometry on the behaviour of fibre metal laminate joints  

Microsoft Academic Search

The effects of geometry on the bearing response of fibre metal laminate (FML) joints are numerically investigated. Specimens designed to fail in bearing, net-tension and shear-out are analysed using a continuum damage mechanics approach. Plasticity in the aluminium layers, fibre and matrix damage in the composite plies and, importantly, delamination between the plies of the laminate are accounted for. The

R. M. Frizzell; C. T. McCarthy; M. A. McCarthy

2011-01-01

119

On the development of a strength prediction methodology for fibre metal laminates in pin bearing  

Microsoft Academic Search

The development of Fibre Metal Laminates (FMLs) for application into aerospace structures represents a paradigm shift in airframe and material technology. By consolidating both monolithic metallic alloys and fibre reinforced composite layers, a new material structure is born exhibiting desired qualities emerging from its heterogeneous constituency. When mechanically fastened via pins, bolts and rivets, these laminated materials develop damage and

Peter Panagiotis Krimbalis

2009-01-01

120

Understanding the behaviour of fibre metal laminates subjected to localised blast loading  

Microsoft Academic Search

This paper examines the behaviour of fibre metal laminates (FML’s) subjected to localised explosive blast loading. Experiments are conducted on samples of varying thickness and material distribution. Plastic deformation, debonding, delamination, fibre fracture and matrix cracking have all been identified as energy absorption mechanisms. Widespread debonding is particularly evident between layers. Comparison between different plates of similar overall thickness shows

S. L. Lemanski; G. N. Nurick; G. S. Langdon; M. S. Simmons; W. J. Cantwell; G. K. Schleyer

2006-01-01

121

Peripapillary retinal nerve fiber layer and foveal thickness in hypermetropic anisometropic amblyopia  

PubMed Central

Purpose To evaluate whether there was a difference in peripapillary retinal nerve fiber layer (RNFL) and foveal thickness between amblyopic and normal individuals with optical coherence tomography. Materials and methods Sixty patients, 30 patients with hypermetropic anisometropic amblyopia and 30 normal emmetropic subjects, were enrolled in this study. The eyes of the participants were divided into three groups: 30 eyes of 30 patients with amblyopia (A), 30 fellow eyes of the amblyopic patients (B), and 30 eyes of 30 normal subjects (C). Emmetropic normal subjects included cases with normal visual acuity and unremarkable ocular examinations. After routine ophthalmic examination, peripapillary retinal nerve fiber layer and foveal thickness measurements were measured by time-domain optical coherence tomography and compared among the three groups. Results The difference in RNFL thickness between amblyopic eyes, fellow eyes of the amblyopic patients, and normal eyes of the emmetropic subjects was not clinically significant. However, the mean foveal thickness was significantly thicker in amblyopic eyes versus the fellow eyes and normal subjects’ eyes. Conclusion Our results suggest that amblyopia seems to have an effect on the foveal thickness, but not on the RNFL thickness.

Yalcin, Elvan; Balci, Ozlem

2014-01-01

122

Properties of nanocomposite PP fibres  

NASA Astrophysics Data System (ADS)

PP-based nanocomposite fibres were prepared by direct polymer melt intercalation. With the intention to determine the size and dispersion of nanoparticles in the polymer matrix, fibres were plasma etched and SEM observations were performed. The influence of nanofiller content and coupling agent on electrokinetic properties was studied. PP monofilament fibres exhibit hydrophobe character with negative zeta potential value. The zeta potential value of co-polymer PP fibre decreases with increasing PPAA content and the isoelectric point IEP of co-polymer samples shifts towards acid region. Addition of modified montmorillonite due to the particles electropositive character, affects the reduction of zeta potential value and a slight shift of IEP towards neutral region is observed. Nano-particles content influences electrokinetic fibres properties, i.e. ZP value is changed, however IE point is not significantly changed by different concentrations of nanofiller. In addition to, mechanical properties of nanocomposite fibres were determined.

Smole, Majda S.; Stakne, Kristina; Svetec, Diana G.; Kleinschek, Karin S.; Ribitsch, Volker

2005-06-01

123

Modelling bird impacts on an aircraft wing – Part 1: Material modelling of the fibre metal laminate leading edge material with continuum damage mechanics  

Microsoft Academic Search

In a collaborative research project, aircraft wing leading edge structures with a glass-based Fibre Metal Laminate (FML) skin have been designed, built, and subjected to bird strike tests that have been modelled with finite element analysis. Fibre Metal Laminates have layers of aluminium alloy and high strength glass fibre composite and have been reported to possess excellent impact properties. In

M. A. McCarthy; J. R. Xiao; N. Petrinic; A. Kamoulakos; V. Melito

2005-01-01

124

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

PubMed

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

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

2014-07-01

125

Retinal nerve fiber layer thickness map  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

126

The exploitation of thin film coatings for fibre sensors for the application of chemical sensing  

NASA Astrophysics Data System (ADS)

We report on the use of thin film coatings, both single and multi-layered, deposited on the flat side of a lapped, D-shaped fibre to enhance the sensitivity of two kinds of surface plasmon resonance based optical fibre sensors. The first kind involves the use of a tilted Bragg grating inscribed within the fibre core, prior to fibre coating, while the second relies on a surface relief grating photoinscribed after the fibre has been coated. Some of the devices operate in air with high coupling efficiency in excess of 40dB and an estimated index sensitivity of ??/?n = 90nm from 1 to 1.15 index range showing potential for gas sensing. Other sensors produced index sensitivities (??/?n) ranging from 6790nm to 12500nm in the aqueous index regime. The materials used for these fibre optical devices are germanium, silica, silver, gold and palladium.

Allsop, T.; Neal, R.; Kalli, K.; Davies, E. M.; Rehman, S.; Maier, R. R. J.; Barton, J.; Jones, J. D.; Webb, D. J.; Bennion, I.

2009-05-01

127

Sulphur-doped silica fibres  

SciTech Connect

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)

Gerasimova, V I; Rybaltovskii, A O; Chernov, P V [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Mashinsky, V M; Sazhin, O D; Medvedkov, O I; Rybaltovsky, A A; Khrapko, R R [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2003-01-31

128

ATLAS ALFA—measuring absolute luminosity with scintillating fibres  

NASA Astrophysics Data System (ADS)

ALFA is a high-precision scintillating fibre tracking detector under construction for the absolute determination of the LHC luminosity at the ATLAS interaction point. This detector, mounted in so-called Roman Pots, will track protons elastically scattered under ?rad angles at IP1.In total there are four pairs of vertically arranged detector modules which approach the LHC beam axis to mm distance. Each detector module consists of ten layers of two times 64 scintillating fibres each (U and V planes). The fibres are coupled to 64 channels Multi-Anodes PhotoMultipliers Tubes read out by compact front-end electronics. Each detector module is complemented by so-called overlap detectors: Three layers of two times 30 scintillating fibres which will be used to measure the relative positioning of two vertically arranged main detectors. The total number of channels is about 15000. Conventional plastic scintillator tiles are mounted in front of the fibre detectors and will serve as trigger counter. The extremely restricted space inside the pots makes the coupling to the read out devices very challenging. Several technologies have been tested in a beam at DESY and a cosmic-ray setup at CERN. A possible upgrade of the photo detection could consist in the replacement of the PMT by Geiger-mode avalanche photodiodes. Preliminary tests are being performed comparing the performance of these devices with the ones of the PMTs.

Franz, S.; Barrillon, P.

2009-10-01

129

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

NASA Astrophysics Data System (ADS)

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

Trindade, M. A.; Benjeddou, A.

2011-07-01

130

Anatomy and lignin distribution in reaction phloem fibres of several Japanese hardwoods  

PubMed Central

Background and Aims Although tension wood formation and the structure of gelatinous fibres (G-fibres) have been widely investigated, studies of the influence of the reaction phenomenon on phloem fibres have been few and incomplete in comparison with those of xylem wood fibres. This study was undertaken to clarify the influence of stem inclination on phloem fibres using several Japanese hardwood species that produce different G-fibre types in tension wood. Methods Eight hardwood species were inclined at 30–45° at the beginning of April. Specimens were collected in July and December. The cell-wall structure and lignin distribution of phloem fibres on both the tension and opposite sides were compared by light microscopy, ultraviolet microscopy, confocal laser scanning microscopy after staining with acriflavine, and transmission electron microscopy after staining with potassium permanganate. Key Results Three types of changes were found in tension-side phloem fibres: (1) increases in the proportion of the syringyl unit in lignin in the S1 and S2 layers and compound middle lamella (Cercidiphyllum japonicum), (2) formation of unlignified gelatinous layers (Melia azedarach and Acer rufinerve) and (3) increases in the number of layers (n) in the multi-layered structure of S1 + S2 + n (G + L) (Mallotus japonicus). Other species showed no obvious change in cell-wall structure or lignin distribution. Conclusions Phloem fibres of the tree species examined in our study showed three types of changes in lignin distribution and cell-wall structure. The reaction phenomenon may vary with tree species and may not be closely related to G-fibre type in tension wood.

Nakagawa, Kaori; Yoshinaga, Arata; Takabe, Keiji

2012-01-01

131

High-power fibre lasers  

NASA Astrophysics Data System (ADS)

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.

Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

2013-11-01

132

Post-stretching induced stress redistribution in Fibre Metal Laminates for increased fatigue crack growth resistance  

Microsoft Academic Search

Post-stretching is a potential method to change the unfavorable residual stress system in fibre metal laminates (FMLs). During post-stretching of the material, the metal layers will be strained into the plastic region of the stress–strain curve, while the fibre layers remain elastic. After unloading, the residual stress system due to curing will be reduced or even reversed dependent on the

S. U. Khan; R. C. Alderliesten; R. Benedictus

2009-01-01

133

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

NASA Astrophysics Data System (ADS)

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

Bhatt, Mittal G.; Rao, Navalgund

2005-04-01

134

Fibre laser based on tellurium-doped active fibre  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

135

Why animals have different muscle fibre types  

Microsoft Academic Search

Animals have different muscle fibre types: slow fibres with a low maximum velocity of shortening ( Vmax) and fast fibres with a high Vmax. An advantage conferred by the use of different fibre types during locomotion1 has been proposed solely on the basis of their in vitro properties. Isolated muscle experiments show that force generation, mechanical power production and efficiency

Lawrence C. Rome; Roel P. Funke; R. Mcneill Alexander; Gordon Lutz; Hugh Aldridge; Frank Scott; Marvin Freadman

1988-01-01

136

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

Microsoft Academic Search

We cross-sectionally examined the relationship between age, optic disc area, refraction, and gender and optic disc topography and retinal nerve fiber layer (RNFL) measurements, using optical imaging techniques. One eye from each of 155 Caucasian subjects (age range 23.0-80.8 y) without ocular pathology was included. Measurements were obtained by using the Heidelberg Retina Tomography (HRT), the GDx Nerve Fiber Analyzer,

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

2002-01-01

137

Use of fibre wastes from production of acetate fibres  

SciTech Connect

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.

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

1995-07-01

138

Structure and chemistry of fibre-matrix interfaces in silicon carbide fibre-reinforced glass-ceramic composites: an electron microscopy study  

Microsoft Academic Search

Silicon carbide continuous fibre-reinforced glass and glass-ceramic matrix composites showing high strength and fracture toughness have been studied using thin-foil transmission electron microscopy and scanning transmission electron microscopy (AEM). The outstanding mechanical behaviour of these materials is directly correlated with the formation of a cryptocrystalline carbon (graphite) reaction-layer interface between the fibres and the matrix. A solid-state reaction involving relatively

R. F. Cooper; K. Chyung

1987-01-01

139

G-fibres in storage roots of Trifolium pratense (Fabaceae): tensile stress generators for contraction.  

PubMed

Root contraction has been described for many species within the plant kingdom for over a century, and many suggestions have been made for mechanisms behind these contractions. To move the foliage buds deeper into the soil, the proximal part of the storage root of Trifolium pratense contracts by up to 30%. Anatomical studies have shown undeformed fibres next to strongly deformed tissues. Raman imaging revealed that these fibres are chemically and structurally very similar to poplar (Populus) tension wood fibres, which are known to generate high tensile stresses and bend leaning stems or branches upright. Analogously, an almost pure cellulosic layer is laid down in the lumen of certain root fibres, on a thin lignified secondary cell wall layer. To reveal its stress generation capacities, the thick cellulosic layer, reminiscent of a gelatinous layer (G-layer) in tension wood, was selectively removed by enzymatic treatment. A substantial change in the dimensions of the isolated wood fibre bundles was observed. This high stress relaxation indicates the presence of high tensile stress for root contraction. These findings indicate a mechanism of root contraction in T. pratense (red clover) actuated via tension wood fibres, which follows the same principle known for poplar tension wood. PMID:20030750

Schreiber, Nicole; Gierlinger, Notburga; Pütz, Norbert; Fratzl, Peter; Neinhuis, Christoph; Burgert, Ingo

2010-03-01

140

Linear stability of free shear flows of fibre suspensions  

NASA Astrophysics Data System (ADS)

A linear stability analysis of the mixing layer in the presence of fibre additives is presented. Using a formulation based on moments of the probability distribution function to determine the particle orientation, we extend the classical linear stability theory and derive a modified Orr Sommerfeld equation. It is found that, for large Reynolds numbers, the flow instability is governed by two parameters: a dimensionless group H, analogous to a reciprocal Reynolds number representing the importance of inertial forces versus viscous forces associated with the anisotropic elongational viscosity of the suspension; and a coefficient CI that accounts for inter-particle hydrodynamic interactions. A parametric study reveals that both parameters can induce an important attenuation of the flow instability. Furthermore, we show that the stabilizing effects arise from the orientation diffusion due to hydrodynamic interactions, and not from the anisotropy induced by the presence of fibres in the flow, as speculated before. The examination of profile contours of different perturbation terms and the analysis of the rate of production of enstrophy show clearly that the main factor behind the reduction of the flow instability is associated with the fibre shear stress disturbance. This disturbance acts as a dissipative term as the fibres, due to the orientational diffusivity arising from hydrodynamic interactions, deviate from the fully aligned anisotropic orientation. On the other hand, fibre normal stresses act as a destabilizing factor and are important only in the absence of hydrodynamic interactions.

Azaiez, J.

2000-02-01

141

Mesothelial proliferation due to asbestos and man-made fibres. Experimental studies on rat omentum.  

PubMed

The intraperitoneal test in rats has proven to be an appropriate method controlling fibrogenicity and carcinogenicity of asbestos fibres and other fibrous dusts. We analyzed the reaction patterns of mesothelial cover layer to different natural mineral fibres (crocidolite, chrysotile, actinolite, erionite, wollastonite) and man-made mineral and synthetic fibres (glass fibres 104/475, polypropylene, aramide fibres). The injection of doses between 0.01 and 100 mg dust suspended in saline solution led to a continued repairing proliferation of submesothelial connective tissue cells and focal submesothelial fibrosis. These changes were never observed after application of granular dusts as mine dust and quartz. After 15 to 28 months we often found an association of fibrosis and local reactive hyperplasia of partly atypical proliferation of rat omentum mesothelium. These changes were also demonstrated in cases without macroscopically visible tumors. In later stages the underlying fibrosis was often infiltrated and dissolved by mesotheliomas. PMID:2156241

Friemann, J; Müller, K M; Pott, F

1990-02-01

142

Evaluation of the Macular, Peripapillary Nerve Fiber Layer and Choroid Thickness Changes in Beh?et's Disease with Spectral-Domain OCT  

PubMed Central

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

Atas, Mustafa; Yuvac?, Isa; Demircan, Suleyman; Guler, Emel; Altunel, Orhan; Pangal, Emine; Goktas, Altan; Sutbeyaz, Serap; Zarars?z, Gokmen

2014-01-01

143

Wetting of flexible fibre arrays.  

PubMed

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

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

2012-02-23

144

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

PubMed Central

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

Martinez-Gamero, Bertha O.; Mohamed-Noriega, Jibran; Cavazos-Adame, Med. Humberto; Mohamed-Hamsho, Med. Jesus

2014-01-01

145

Enhancing the Fibre Matrix Adhesion of Natural Fibre Reinforced Polypropylene by Electron Radiation Analyzed with the Single Fibre Fragmentation Test  

Microsoft Academic Search

The effects of electron radiation on natural fibre reinforced polypropylene have been analyzed with the single fibre fragmentation test. Specimens of single hemp, flax, ramie and cotton fibres\\/fibre bundles embedded in a polypropylene sheet were irradiated with electron radiation of 10 MeV with intensities of 5, 15 and 33 kGy. The radiation led to a strain reduction of the polypropylene

Tim Huber; Udo Biedermann; Jörg Müssig

2010-01-01

146

Behaviour of fibre–metal laminates subjected to localised blast loading: Part I—Experimental observations  

Microsoft Academic Search

This two-part article examines the behaviour of aluminium alloy–glass fibre-reinforced polypropylene-based fibre–metal laminates (FMLs) subjected to localised explosive blast loading. Part I presents observations from the experiments on samples of varying thickness and material distribution, and investigates the influence of stacking configuration. This extensive study examines panels which have between two and five layers of aluminium, and up to eight

G. S. Langdon; S. L. Lemanski; G. N. Nurick; M. C. Simmons; W. J. Cantwell; G. K. Schleyer

2007-01-01

147

The Development of a Continuum Damage Model for Fibre Metal Laminate Structures  

Microsoft Academic Search

Fibre Metal Laminates (FMLs) are a family of materials consisting of alternating layers of thin metal sheets and fibre-reinforced\\u000a plastic. Glass composite based FMLs, commercially available under the name GLARE, have recently found application in the aircraft\\u000a industry due to their excellent fatigue performance and impact properties. This work aims to develop a computational damage\\u000a model for GLARE for use

Ronan M. Frizzell; Conor T. McCarthy; Daire Cronin; Michael A. McCarthy; Ronan M. O’Higgins

148

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

149

Residual strain measurement and impact response of optical fibre Bragg grating sensors in fibre metal laminates  

Microsoft Academic Search

Recently, optical fibre Bragg gratings have attracted a significant amount of attention as optical fibre sensors for measuring strain in composite structures. Indeed, the growth of optical fibre technology has spurred the development of smart composites capable of measuring real-time internal strain within structures and an assortment of measurands such as temperature, pressure and chemical. In this paper, optical fibre

K. S. C. Kuang; R. Kenny; M. P. Whelan; W. J. Cantwell; P. R. Chalker

2001-01-01

150

In-fibre Bragg grating sensors  

Microsoft Academic Search

In-fibre Bragg grating (FBG) sensors are one of the most exciting developments in the field of optical fibre sensors in recent years. Compared with conventional fibre-optic sensors, FBG sensors have a number of distinguishing advantages. Significant progress has been made in applications to strain and temperature measurements. FBG sensors prove to be one of the most promising candidates for fibre-optic

Yun-Jiang Rao

1997-01-01

151

Automatically building or repairing composite fibre structures  

Microsoft Academic Search

Purpose – This paper sets out to report on the developments in the evolution of advanced composite fibre structure production systems, to highlight advanced equipment already in production and to examine efforts to extend automated technology to assessing damage and automatically repairing composite fibre structures. Design\\/methodology\\/approach – Leading companies in design and construction of advanced composite fibre production machinery are

Richard Bloss

2007-01-01

152

Tunnel monitoring using multicore fibre displacement sensor  

Microsoft Academic Search

In this paper, we report the first demonstration of multiplexed fibre Bragg grating strain sensors in a multicore fibre for shape measurement and their application to structural monitoring. Sets of gratings, acting as strain gauges, are co-located in the multicore fibre such that they enable the curvature to be determined via differential strain measurement. Multiple sets of these gratings allow

W. N. MacPherson; M. Silva-Lopez; J. S. Barton; A. J. Moore; J. D. C. Jones; D. Zhao; L. Zhang; I. Bennion; N. Metje; D. N. Chapman; C. D. F. Rogers

2006-01-01

153

Carbon Fibres of High Young's Modulus  

Microsoft Academic Search

WE report some preliminary results from a study of the effects of irradiation and the addition of boron on carbon fibres derived from polyacrylonitrile. Both treatments caused significant increases in the Young's modulus of the fibres, and in some cases increased the fibre strength.

S. Allen; G. A. Cooper; R. M. Mayer

1969-01-01

154

Dietary fibre, nuts and cardiovascular diseases  

Microsoft Academic Search

Dietary fibre has a range of metabolic health benefits. Through a variety of mechanisms, dietary fibre, and the viscous variety in particular, slows down gastric emptying and intestinal transit, decreases the rate of intestinal carbohydrate absorption, and increases faecal bile acid excretion. Therefore, consumption of some types of soluble fibre can enhance satiety, which is associated with a lower BMI,

Jordi Salas-Salvadó; Mónica Bulló; Ana Pérez-Heras; Emilio Ros

2006-01-01

155

Skeletal muscle fibre types in the dog.  

PubMed Central

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

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

1993-01-01

156

Fibres for wound dressings based on mixed carbohydrate polymer fibres  

Microsoft Academic Search

Polysaccharide-based dressings have increasingly become viable alternatives to somewhat incompatible and often problematic cotton or viscose gauzes traditionally used for wound dressings. Abundant availability of alginates and their relative ease of reversible solubility in particular have been instrumental in their development into fibres and lately their application as vehicles for delivering drugs. This paper reports on the spinning efficiency of

M. Miraftab; Q. Qiao; J. F. Kennedy; S. C. Anand; M. R. Groocock

2003-01-01

157

Atomic force microscopy analysis of wool fibre surfaces in air and under water  

Microsoft Academic Search

Wool fibre surfaces have been treated by solvent cleaning which leaves the native covalently bound surface lipid layer intact, and by alcoholic alkali which removes the lipid layer. The resultant surfaces have been analysed by atomic force microscopy (AFM), with particular emphasis on force–distance (F–d) methods. Methodologies were developed for investigation in situ in water of both the surface topography

J. A. A. Crossley; C. T. Gibson; L. D. Mapledoram; M. G. Huson; S. Myhra; D. K. Pham; C. J. Sofield; P. S. Turner; G. S. Watson

2000-01-01

158

A method for estimating the fibre length in fibre-PLA composites.  

PubMed

Wood pulp fibres are an important component of environmentally sound and renewable fibre-reinforced composite materials. The high aspect ratio of pulp fibres is an essential property with respect to the mechanical properties a given composite material can achieve. The length of pulp fibres is affected by composite processing operations. This thus emphasizes the importance of assessing the pulp fibre length and how this may be affected by a given process for manufacturing composites. In this work a new method for measuring the length distribution of fibres and fibre fragments has been developed. The method is based on; (i) dissolving the composites, (ii) preparing the fibres for image acquisition and (iii) image analysis of the resulting fibre structures. The image analysis part is relatively simple to implement and is based on images acquired with a desktop scanner and a new ImageJ plugin. The quantification of fibre length has demonstrated the fibre shortening effect because of an extrusion process and subsequent injection moulding. Fibres with original lengths of >1 mm where shortened to fibre fragments with length of <200 ?m. The shortening seems to be affected by the number of times the fibres have passed through the extruder, the amount of chain extender and the fraction of fibres in the polymer matrix. PMID:23339585

Chinga-Carrasco, G; Solheim, O; Lenes, M; Larsen, A

2013-04-01

159

Fibre Forms in Animal Hairs  

Microsoft Academic Search

UNDER the above title Mr. H. J. Woods1 proposes three alternatives to the `weathering' hypothesis tentatively advanced by me2 to account for supernormal curvature in the apical region of certain guard hairs. Of the opposing evidence, it will suffice to point out that, in the light of a previous communication by Woods3, the fibres should, if his views are correct,

R. O. Hall

1935-01-01

160

REVIEW ARTICLE: Fibre optic gyroscopes  

Microsoft Academic Search

The fibre optic gyroscope (FOG) offers the potential of a low cost, high performance strap down inertial navigational instrument. In this article, the principles of the FOG are reviewed and the factors which limit the performance of the system are discussed. The basic Sagnac interferometer is shown to be susceptible to polarisation effects, optically induced nonlinearities and both spatial and

B. Culshaw; I. P. Giles

1983-01-01

161

Fibre reinforced composite dental bridge  

Microsoft Academic Search

This experimental investigation aims at revealing the mechanical behaviour and failure pattern of direct fibre-reinforced resin-bonded dental bridge with various designs. To evaluate the overall effects of some newly developed dental materials, in the experiment, genuine composite dental bridge specimens are prepared and tested. The ultimate load, stiffness and mode at the failure of the bridges are measured and compared

W. Li; M. V. Swain; Q. Li; J. Ironside; G. P. Steven

2004-01-01

162

Mineral fibre sampling and size selection.  

PubMed

Potential health hazards due to fibre inhalation are only evaluated in a limited way by simple optical microscopy examination of the membrane filters on which the fibres have been collected. One must consider the amount of fibres deposited and persisting in the most vulnerable organ compartments. Exposure evaluated in this way must take account of the deposition efficiency and relative clearance efficiency of different regions of the respiratory tract, which depends mainly on the diameter and length distribution of the fibres. The fibre diameter roughly indicates the deposition site in the respiratory tract, while the length is mainly connected with toxicity. For these reasons, at international level, special samplers have been recently proposed, capable of distinguishing the fibre sizes, in order to separate the so-called 'thoracic fraction' (the total fibres which penetrate beyond the larynx) and the 'respirable fraction' (only the fibres reaching the non ciliated respiratory area), which represent the most interesting sizes as far as health effects are concerned. Our purpose in this context is to explore the feasibility of using the Inertial Spectrometer (INSPEC) as a sampler that separates the fibres according to their aerodynamic diameter. The optical and electron microscope observations of the samples demonstrate a satisfactory size separation of the fibres and alignment along the flow lines. Therefore, INSPEC is successful in restricting the microscopic analyses to the potentially noxious fibres and in assessing specific concentrations for each diameter interval. PMID:10206040

Morigi, M P; Giacomelli, G M; Prodi, V

1999-02-01

163

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

PubMed Central

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.

Ishizuka, Hisao

2012-01-01

164

Stress in elastic plates reinforced by fibres lying in concentric circles  

NASA Astrophysics Data System (ADS)

W E CONSIDER fibre-reinforced elastic plates with the reinforcement continuously distributed in concentric circles ; such a material is locally transversely isotropic, with the circumferential direction as the preferred direction. For an annulus bounded by concentric circles, the exact solution of the traction boundary value problem is obtained. When the extension modulus in the fibre direction is large compared to other extension and shear moduli, the material is strongly anisotropic. For this case a simpler approximate solution is obtained by treating the material as inextensible in the fibre direction. It is shown that the exact solution reduces to the inextensible solution in the appropriate limit. The inextensible theory predicts the occurrence of stress concentration layers in which the direct stress is infinite ; for materials with small but finite extensibility these layers correspond to thin regions of high stress and high stress gradient. A boundary layer theory is developed for these regions. For a typical carbon fibre-resin composite, the combined boundary layer and inextensible solutions give an excellent approximation to the exact solution. The theory is applied to the problem of an isotropic plate, under uniform stress at infinity, containing a circular hole which is strengthened by the addition of an annulus of fibre-reinforced material.

Belfield, A. J.; Rogers, T. G.; Spencer, A. J. M.

165

Wavelength-scalable hollow optical fibres with large photonic bandgaps for CO2 laser transmission  

NASA Astrophysics Data System (ADS)

Conventional solid-core optical fibres require highly transparent materials. Such materials have been difficult to identify owing to the fundamental limitations associated with the propagation of light through solids, such as absorption, scattering and nonlinear effects. Hollow optical fibres offer the potential to minimize the dependence of light transmission on fibre material transparency. Here we report on the design and drawing of a hollow optical fibre lined with an interior omnidirectional dielectric mirror. Confinement of light in the hollow core is provided by the large photonic bandgaps established by the multiple alternating submicrometre-thick layers of a high-refractive-index glass and a low-refractive-index polymer. The fundamental and high-order transmission windows are determined by the layer dimensions and can be scaled from 0.75 to 10.6µm in wavelength. Tens of metres of hollow photonic bandgap fibres for transmission of carbon dioxide laser light at 10.6µm wavelength were drawn. The transmission losses are found to be less than 1.0dBm-1, orders of magnitude lower than those of the intrinsic fibre material, thus demonstrating that low attenuation can be achieved through structural design rather than high-transparency material selection.

Temelkuran, Burak; Hart, Shandon D.; Benoit, Gilles; Joannopoulos, John D.; Fink, Yoel

2002-12-01

166

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

PubMed

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

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

2013-02-25

167

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

168

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

Microsoft Academic Search

Composites made of plant fibres offer a new, environmentally attractive supplement to traditional glass fibre composite materials. Plant fibre composites may have similar mechanical properties as conventional (e.g. glass fibre) composites, with a lower impact strength. Since plant fibre composites constitute a relatively new group of materials, the limitations imposed on the mechanical performance due to flaws are not well

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

1999-01-01

169

Evaluation of keratin fibre damages  

Microsoft Academic Search

This paper investigated the effect of three different treatments, namely: (i) sunlight (simulated by Xenon light) exposures,\\u000a (ii) bleaching and (iii) perming on the damage of keratin fibre (with the use human hair). Four different testing methods\\u000a were applied to quantify the hair damages. On evaluating the test results, it was concluded that the bleaching process imparted\\u000a the most severe

C. W. M. Yuen; C. W. Kan; S. Y. Cheng

2007-01-01

170

Supergravity on Principal Fibre Bundle  

NASA Astrophysics Data System (ADS)

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

Kakazu, K.; Matsumoto, S.

1987-10-01

171

Impurity effects in carbon fibres  

Microsoft Academic Search

Outgassing experiments have been performed on a variety of polyacrylonitrile- and rayon-based carbon yarns. Major residual impurities, as well as those introduced from surface treatments, have been identified. Sulphur has been shown to be a major impurity of rayon-based carbon fibres, with concentrations up to 3110 ppm by weight having been determined by neutron-activation analyses. Removal of this contaminant as

M. L. Lieberman; G. T. Noles

1972-01-01

172

Fabrication of intrinsic fibre Fabry Perot cavities in silica optical fibres via F2-laser ablation  

Microsoft Academic Search

This paper reports on a technique for fabricating intrinsic fibre Fabry-Perot cavities in fused silica optical fibres. An F2-excimer laser was used to micromachine parallel walled cavities through the diameter of optical fibres. A custom-designed beam delivery and target alignment system was used to enable the production of high aspect-ratio cavities in fibres. The optical response of the micro-cavities ablated

V. R. Machavaram; R. A. Badcock; G. F. Fernando

2007-01-01

173

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

SciTech Connect

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)

Kurkov, Andrei S; Grukh, Dmitrii A; Medvedkov, O I; Paramonov, Vladimir M; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2005-04-30

174

Strength variability of single flax fibres  

Microsoft Academic Search

Due to the typical large variability in the measured mechanical properties of flax fibres, they are often employed only in\\u000a low grade composite applications. The present study aims to investigate the reasons for the variability in tensile properties\\u000a of flax fibres. It is found that an inaccuracy in the determination of the cross-sectional area of the fibres is one major

Mustafa Aslan; Gary Chinga-Carrasco; Bent F. Sørensen; Bo Madsen

175

Plastic shrinkage of steel fibre reinforced concrete  

Microsoft Academic Search

The paper presents the results of an experimental investigation on the plastic shrinkage of steel fibre reinforced concrete\\u000a (SFRC). Tests were carried out on mixes with cement content ranging between 370 and 468 kg m?3. Four types of steel fibres were used: melt extract, hooked, crimped and Harex. The volume of, fibres ranged between 0 and\\u000a 4.47% of the mix

P. S. Mangat; M. M. Azari

1990-01-01

176

Impact loading on fibre metal laminates  

Microsoft Academic Search

Static identation and low and high velocity impact tests are conducted on specimens with a circular clamped test area. Monolithic A1 2024-T3 and 7075-T6, various grades of Fibre Metal Laminates (FML), and composites are tested. The energy to create the first crack for FML with aramid and carbon fibres is comparable to fibre reinforced composite materials and is relatively low

A. Vlot

1996-01-01

177

Tropical fibre sources for pigs—digestibility, digesta retention and estimation of fibre digestibility in vitro  

Microsoft Academic Search

The digestibility of high-fibre diets and digesta passage was measured in growing pigs and attempts were made to predict the in vivo digestibility from in vitro data. In Experiment 1, six diets were formulated to measure digestibility using low-fibre cassava starch, fish meal and soya bean meal in combination with six locally available fibre sources. Four green plants: banana sheaths

Nguyen Nhut Xuan Dung; Luu Huu Manh; Peter Udén

2002-01-01

178

The failure of fibre composites and adhesively bonded fibre composites under high rates of test  

Microsoft Academic Search

The failure of fibre composites and adhesively bonded fibre composites under high rates of test, up to rates of about 15 m s-1 were studied in detail. The present paper. Part I of the series, considers the experimental aspects of the mode I fracture of the fibre composite materials and joints. Part II will analyse the dynamic effects which are

B. R. K. Blackman; J. P. Dear; A. J. Kinloch; H. MacGillivray; Y. Wang; J. G. Williams; P. Yayla

1995-01-01

179

FIBRE REINFORCED CONCRETE AND HIGH PERFORMANCE FIBRE REINFORCED CEMENTITIOUS COMPOSITES: AN OVERVIEW  

Microsoft Academic Search

This article gives an overview on the recent developments in the area of fibre reinforced concrete (FRC) and high performance fibre reinforced cementitious composites (HPFRCC). It is divided into two main sections. The first section focuses on the definition, fibre classification and applications of FRC, whereas the next section discusses the concepts of HPFRCC, which is a product from the

Sudharshan N. Raman; Hilmi Bin Mahmud; Muhammad Fauzi Mohd

180

The sizing of fibres using optical scattering.  

PubMed

The light scattering pattern from absorbing cylinders has been shown to be adequately described by Fraunhofer diffraction for cylinders with diameters as small as 4 micrometers for light of wavelength 632.8 nm. A simple inversion procedure based on a Fourier transform of the scattering pattern may be used to obtain the size distribution of fibre widths. For fibres of diameter less than 4 micrometers the same inversion procedure may be used when an electron micrograph of the fibres becomes the scattering object. The size distribution for aligned and unaligned fibres may be obtained directly, and no initial calibration is required. PMID:7239675

Somerford, D J; Powers, S R

1980-01-01

181

Two-axis accelerometer based on multicore fibre Bragg gratings  

NASA Astrophysics Data System (ADS)

We report an accelerometer based upon a simple fibre cantilever constructed from a short length of multicore fibre (MCF) containing fibre Bragg gratings (FBGs). Two-axis measurement is demonstrated up to 3 kHz.

Fender, Amanda; MacPherson, William N.; Maier, Robert R. J.; Barton, James S.; George, David S.; Howden, Robert I.; Smith, Graham W.; Jones, Ben J. S.; McCulloch, Scott; Chen, Xianfeng; Suo, Rui; Zhang, Lin; Bennion, Ian

2007-07-01

182

Polymorphism of myofibrillar proteins of rabbit skeletal-muscle fibres. An electrophoretic study of single fibres.  

PubMed Central

Rabbit predominantly fast-twitch-fibre and predominantly slow-twitch-fibre skeletal muscles of the hind limbs, the psoas, the diaphragm and the masseter muscles were fibre-typed by one-dimensional polyacrylamide-gel electrophoresis of the myofibrillar proteins of chemically skinned single fibres. Investigation of the distribution of fast-twitch-fibre and slow-twitch-fibre isoforms of myosin light chains and the type of myosin heavy chains, based on peptide 'maps' published in Cleveland. Fischer, Kirschner & Laemmli [(1977) J. Biol. Chem. 252, 1102-1106], allowed a classification of muscle fibres into four classes, corresponding to histochemical types I, IIA, IIB and IIC. Type I fibres with a pure slow-twitch-type of myosin were found to be characterized by a unique set of isoforms of troponins I, C and T, in agreement with the immunological data of Dhoot & Perry [(1979) Nature (London) 278, 714-718], by predominance of the beta-tropomyosin subunit and by the presence of a small amount of an additional tropomyosin subunit, apparently dissimilar from fast-twitch-fibre alpha-tropomyosin subunit. The myofibrillar composition of type IIB fast-twitch white fibres was the mirror image of that found for slow-twitch fibres in that the fast-twitch-fibre isoforms only of the troponin subunits were present and the alpha-tropomyosin subunit predominated. Type IIA fast-twitch red fibres showed a troponin subunit composition identical with that of type IIB fast-twitch white fibres. On the other hand, a unique type of myosin heavy chains was found to be associated with type IIA fibres. Furthermore, the myosin light-chain composition of these fibres was invariably characterized by a small amount of LC3F light chain and by a pattern that was either a pure fast-twitch-fibre light-chain pattern or a hybrid LC1F/LC2F/LC3F/LC1Sb light-chain pattern. By these criteria type IIA fibres could be distinguished from type IIC intermediate fibres, which showed coexistence of fast-twitch-fibre and slow-twitch-fibre forms of myosin light chains and of troponin subunits. Images Fig. 1. Fig. 2. Fig. 3. Fig. 5. Fig. 6. Fig. 7. Fig. 8.

Salviati, G; Betto, R; Danieli Betto, D

1982-01-01

183

Glass fibre versus non-glass fibre splinting bandages.  

PubMed

We have assessed the current range of synthetic splinting bandages, comparing glass with non-glass fabrics and plaster-of-Paris. Physical and mechanical tests have been carried out and the opinions of patients, volunteers and orthopaedic staff were recorded. Modern bandages have some better properties than standard plaster bandage but do not conform as well, are more expensive and potentially more hazardous. However, non-glass bandages are lighter, less brittle, more radiolucent and less hazardous than glass fibre bandages and are preferred by both patients and applicators. PMID:1572703

Wytch, R; Ross, N; Wardlaw, D

1992-01-01

184

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

PubMed

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

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

2011-06-01

185

Simulation of complex phenomena in optical fibres  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

186

TEM\\/FE-SEM studies on tension wood fibres of Acer spp., Fagus sylvatica L. and Quercus robur L  

Microsoft Academic Search

Tension wood (TW) fibres from maple, beech and oak were analysed with special emphasis on the cell wall fine structure and\\u000a deposition of aromatic compounds within the gelatinous layer (GL). For this purpose, transmission electron microscopy (TEM)\\u000a was applied after section staining with potassium permanganate. There was evidence for the occurrence of aromatic compounds\\u000a in the GLs of fibres of

Christian Lehringer; Geoffrey Daniel; Uwe Schmitt

2009-01-01

187

Preparation of PDMS vi–Al 2O 3 composite hollow fibre membranes for VOC recovery from waste gas streams  

Microsoft Academic Search

A new PDMSvi–Al2O3 composite hollow fibre membrane has been developed by coating a PDMSvi-oligo film on the outer surface of an Al2O3 hollow fibre porous substrate prepared by a dry\\/wet phase inversion method. Microstructures of the composite membranes were examined using scanning electron microscopy (SEM), displaying a uniform PDMSvi-oligo coating layer, free of defects with a thickness of around 15?m.

Shaomin Liu; W. K. Teo; Xiaoyao Tan; K. Li

2005-01-01

188

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

SciTech Connect

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)

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

2012-09-30

189

Correlation between macular changes and the peripapillary nerve fiber layer in primary open angle glaucoma  

PubMed Central

Glaucoma is a leading cause of blindness and the early diagnosis is crucial for treatment and follow-up in the progression of the disease. Objective: To evaluate the changes in mean macular thickness and volume and compare them with the mean thickness of the peripapillary nerve fiber layer in primary open angle glaucoma, using Time Domain (TD) optical coherence tomography ( OCT). Method: The examinations were conducted on 275 eyes of 138 patients, as it follows: 203 eyes of 102 patients diagnosed with primary open angle glaucoma in various stages of evolution, representing the study group, and 72 normal eyes from 36 patients, representing the control group. The study was conducted from March 2010 to December 2012. All the patients gave their consent, in accordance with the Helsinki Declaration. The study group showed a decrease in mean macular thickness and volume, as well as mean thickness of the peripapillary nerve fiber layer (RNFL) compared to the control group. According to the OCT measurements, the results of the study have shown that the decrease of the mean thickness of the RNFL is a better differentiator between glaucomatous and normal eyes compared to the decrease of the mean macular thickness and volume.

Manasia, D; Voinea, L; Vasinca, ID; Alexandrescu, C

2014-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

191

Amphibole fibres in Chinese chrysotile asbestos.  

PubMed

Ten chrysotile bulk samples originating from six Chinese chrysotile mines were studied for amphibole fibres. Five of the mines operate on ultramafic rocks whereas one exploits a dolomite-hosted deposit. The asbestos fibre content in lung tissue was examined from seven deceased workers of the Shenyang asbestos plant using these raw materials. The bulk samples were pretreated with acid/alkali-digestion, and thereafter, scanning and transmission electron microscopy, X-ray microanalysis, selected area electron diffraction and X-ray powder diffractometry were used to identify the minerals. Sample preparation of lung tissue involved drying and low-temperature ashing. All of the bulk samples contained amphibole fibres as an impurity. The amphibole asbestos contents were between 0.002 and 0.310 w-%. Tremolite fibres were detected in every sample but anthophyllite fibres were present only in the sample originating from the dolomite-hosted deposit. In comparison, anthophyllite (71%), tremolite (9%) and chrysotile (10%) were the main fibre types in the lung tissue samples indicating faster pulmonary clearance of chrysotile fibres. The total levels ranged from 2.4 to 148.3 million fibres (over 1 microm in length) per gram of dry tissue, and they were consistent with heavy occupational exposure to asbestos. PMID:11182428

Tossavainen, A; Kotilainen, M; Takahashi, K; Pan, G; Vanhala, E

2001-03-01

192

Carbon fibre reinforced plastic slotted waveguide antenna  

Microsoft Academic Search

Ten-slot slotted waveguide antennas manufactured from aluminium and carbon fibre reinforced plastic were designed, manufactured and tested. The carbon fibre reinforced plastic was commercially available aerospace grade prepreg tape and metallic lining was not used in the waveguides. The antennas operated at X-band with uniform aperture distribution a uniform aperture distribution. The only difference in antenna performance was an additional

Derek Gray; Kelvin Nicholson; Kamran Ghorbani; Paul Callus

2010-01-01

193

Blending of Jute with Different Natural Fibres  

Microsoft Academic Search

Cotton, jute, flax, ramie, hemp, sisal, manila hemp, wool, and silk are some of the major natural fibres, which are widely being used throughout the world. Apart from these, a large number of fibres grown in much smaller quantities in different parts of the world have local economic importance and are mostly consumed locally. Jute is the second most important

Gautam Basu; Alok Nath Roy

2008-01-01

194

Fibre-reinforced caissons for offshore applications  

Microsoft Academic Search

Steel caissons currently used on offshore platforms for the uplift of seawater onto platform topsides, for example, are susceptible to corrosion, and some operators have had to replace corroded caissons during service. The use of fibre reinforced plastics (FRP), in particular glass-fibre (GRP), has been explored by a number of offshore operators as an alternative to steel, principally due to

P. J. Boothby; C. D. Johnstone

1997-01-01

195

Friction measurements on carbon fibre tows  

Microsoft Academic Search

Friction plays an important role in the production of fibre reinforced composite products. The fibrous tows deform during the forming phase. Friction is regarded as a dominant phenomenon in tow deformation mechanisms. The coefficient of friction is a material-interface characteristic which gives a relation between applied deformation loads and frictional forces. A capstan experiment has been performed with carbon fibre

B. Cornelissen; L. Warnet; R. Akkerman

2010-01-01

196

Characterisation and properties of oriented PVC fibres  

Microsoft Academic Search

Drawn PVC fibres were investigated using birefringence, DSC and TMA techniques, and their tenacity was measured. An increase in fibre draw ratio (DR) for heat set samples produced an increase in tenacity, birefringence and X-ray intensity. The linearity of a tenacity\\/birefringence plot suggested that tenacity was a good indicator of molecular orientation. An ‘undrawn’ filament was substantially amorphous. Drawing without

Hwan C. Kim; Marianne Gilbert

2004-01-01

197

Development of a ferromagnetic fibre metal laminate  

Microsoft Academic Search

This study introduces the concept of a multifunctional fibre metal laminate (FML), specifically, one which utilises ferromagnetic foil in combination with carbon fibre reinforced epoxy to produce a FML which is magnetically functional and structurally efficient. The aim is to develop such a material\\/structure for use in future high output, low mass, electrical machines and embedded actuation. The work presented

G. P. McCombe; J. A. Etches; P. H. Mellor; I. P. Bond

2011-01-01

198

Magnetostrictive actuation of fibre \\/ polymer composites  

Microsoft Academic Search

Despite substantial research into smart materials and structures technology, the integration of magnetostrictive materials into fibre reinforced laminated structures to provide capabilities such as vibration suppression has been limited to date. In this work, magnetostrictive Terfenol-D is inserted into unidirectional glass and carbon fibre reinforced polymer laminates. The strain developed in the laminates due to the magnetostriction of the Terfenol-D

G. P. McCombe; J. A. Etches; I. P. Bond; P. H. Mellor

199

Bicomponent Meltblown Nonwovens and Fibre Splitting  

Microsoft Academic Search

Side-by-side bicomponent meltblown fibre webs are produced on Reicofil® bicomponent (bico) meltblown line at TANDEC using polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA), polytrimethylene terephthalate (PTT), polylactide (PLA), etc. In this study, fibre splitting of the bico meltblown webs is investigated by several approaches, including hydroentanglement, hot water treatment, benzoic acid treatment, and alkali treatment.

Dong Zhang; Yanbo Liu; Jihua Xiao

2004-01-01

200

Optical fibre sensors sensitized by phenyl-modified porous silica prepared by sol–gel  

Microsoft Academic Search

Porous silica and phenyl-modified porous silica were prepared by sol–gel method as cladding for optical fibres and tested for the chemical detection of aromatic and alkane vapours. The refractive indices and optical attenuation of the layers have been determined from the measured angular distributions of the output optical power. For this purpose, a model based on geometrical optics has been

F Abdelmalek; J. M Chovelon; M Lacroix; N Jaffrezic-Renault; V Matejec

1999-01-01

201

Matrix flow and densification during the consolidation of matrix coated fibres  

Microsoft Academic Search

The consolidation of titanium alloy metal matrix composites from matrix coated fibres has been modelled using a continuum finite element approach. Predictions of time to achieve full density are in good agreement with experimental data. The predicted matrix flow has been compared with metallographic sections from samples containing novel yttria marker layers, to allow measurements of actual flow during densification.

S. Schueler; B. Derby; M. Wood; C. Ward-Close

2000-01-01

202

Experimental synthesis of fibre Bragg gratings index profiles: comparison of two inverse scattering algorithms  

NASA Astrophysics Data System (ADS)

In this paper we use inverse scattering algorithms to synthesize the index profiles of fibre Bragg gratings from low coherence interferometry measurements. We compare two algorithms, the layer peeling and an iterative solution of the Gel'fand-Levitan-Marchenko coupled equations, and show that the former is more efficient.

Leduc, D.; Chapeleau, X.; Lupi, C.; Lopez Gejo, F.; Douay, M.; LeNy, R.; Boisrobert, C.

2007-01-01

203

Experimental characterization and numerical simulations of a syntacticfoam\\/glass-fibre composite sandwich  

Microsoft Academic Search

This note presents the main results of an experimental and numerical investigation on the mechanical behaviour of a composite sandwich primarily designed for naval engineering applications. The skins of the sandwich are made of glass-fibre\\/polymer-matrix composites; their interior layers are connected with interwoven threads called piles which cross the sandwich core. Such core consists of a syntactic foam made by

Alberto Corigliano; Egidio Rizzi; Enrico Papa

2000-01-01

204

Simulation of the response of fibre–metal laminates to localised blast loading  

Microsoft Academic Search

The response of Fibre–Metal Laminates (FML) to localised blast loading is studied numerically in order to interpret the deformation mechanism due to highly localised pressure pulses causing permanent deformations and damage observed experimentally in FML panels comprising different numbers of aluminium alloy layers and different thickness blocks of GFPP material [Langdon GS, Lemanski SL, Nurick GN, Simmons MS, Cantwell WJ,

D. Karagiozova; G. S. Langdon; G. N. Nurick; S. Chung Kim Yuen

2010-01-01

205

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

Microsoft Academic Search

BACKGROUND: Understanding the evolutionary genetics of modern crop phenotypes has a dual relevance to evolutionary biology and crop improvement. Modern upland cotton (Gossypium hirsutum L.) was developed following thousands of years of artificial selection from a wild form, G. hirsutum var. yucatanense, which bears a shorter, sparser, layer of single-celled, ovular trichomes ('fibre'). In order to gain an insight into

Ryan A Rapp; Candace H Haigler; Lex Flagel; Ran H Hovav; Joshua A Udall; Jonathan F Wendel

2010-01-01

206

Supercontinuum generation in thulium-doped fibres  

SciTech Connect

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)

Kurkov, Andrei S; Kamynin, V A; Tsvetkov, V B; Sadovnikova, Ya E; Marakulin, A V; Minashina, L A

2012-09-30

207

EDITORIAL: Optical Fibre Sensors 18 (OFS-18)  

NASA Astrophysics Data System (ADS)

The International Conference on Optical Fibre Sensors (OFS-18) was held in October 2006 in Cancún, Mexico, under the general chairmanship of Dr Alexis Mendez (MCH Engineering LLC, USA) and Dr Fernando Mendoza (Centro de Investigaciones en Optica, Mexico). 'OFS', as it has become known, is firmly established as the leading international conference for the optical fibre sensor community. Since its inception, in London in 1983, and under the leadership of an international steering committee independent of any learned society or professional institution, it has been held approximately every eighteen months. The venue nominally rotates from Europe, to the Americas, and thence to Asia and the Pacific. OFS-18 demonstrated the continuing vigour of the community, with some 250 papers presented, plus two workshops, with attendance as international as ever. In recent years, it has become a tradition to publish a post-conference special issue in the journal Measurement Science and Technology, and these special issues offer a representative sample of the current status of the field. In the nearly 25 years since OFS began, many of the early ideas and laboratory-based proof-of-principle experiments have led to highly developed instrumentation systems, and to successful commercial products. Perhaps the most mature of all of these technologies is the optical fibre gyroscope, with the fibre hydrophone a close second—originally developed for defence applications for which it is now established, but with increasing relevance to the oil and gas industry; electromagnetic sensors based on the Faraday and electro-optic effects are of growing significance in the power generation and distribution industry; whilst in-fibre grating-based sensors occupy an expanding niche in structural monitoring, especially in civil engineering. It is therefore appropriate that the first day of OFS was devoted to workshops on structural health monitoring, and to commemorate the 30th anniversary of the fibre optic gyroscope, conventionally taken to date from the first experimental demonstration by V Vali and R W Shorthill (1976 'Fibre ring interferometer' Appl. Opt. 15 1099-100). It is an indication of the health of the community that the successful maturity of some applications is complemented by the new technologies that will be the basis of the future development of the field, and here the content of this special issue is an interesting indication of likely areas of growth. Essentially all current fibre optic systems are based on solid, doped fused silica fibres, which are the basis of the world's telecommunications industry. However, over the last decade an exciting development has been micro-structured fibres, whose waveguiding properties owe as much to the structure of the fibre as to the materials from which they are made. The significance for sensing applications is considerable, with opportunities to achieve properties for dispersion, environmental sensitivity, wavelength range and power-handling quite different from the capabilities of conventional fibre. Thus it is not surprising that several of the papers in the issue (by Cordeiro, Martynkien, Bock, Wolinski, Michie, Digonnet and Kilic) are devoted to applications of such fibres—photonic crystal fibres (PCF), as they are often called. Digonnet's contribution is especially interesting, being concerned with the use of hollow-core photonic bandgap fibre to form a gyroscope, hence avoiding the many subtle non-linear optical effects that can degrade the performance of a conventional fibre gyroscope. PCF are not the only special fibres to feature in the issue: polymer fibres are of increasing interest for sensing applications (O'Keeffe, Kiesel, Kalli and Ashley), not least for their ability to withstand high levels of strain. In-fibre gratings continue to be a very important area in the field, and are well represented in the issue (Ni, González-Segura, Chen, Falate, Kamikawachi, Wang and Correia). We hope that this special issue helps to further developments in the field of optical fibre sensors and we w

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

2007-10-01

208

Erbium-doped aluminophosphosilicate optical fibres  

SciTech Connect

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)

Likhachev, M E; Bubnov, M M; Zotov, K V; Medvedkov, O I [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Lipatov, D S; Yashkov, M V; Gur'yanov, Aleksei N [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2010-09-10

209

Tunnel monitoring using multicore fibre displacement sensor  

NASA Astrophysics Data System (ADS)

In this paper, we report the first demonstration of multiplexed fibre Bragg grating strain sensors in a multicore fibre for shape measurement and their application to structural monitoring. Sets of gratings, acting as strain gauges, are co-located in the multicore fibre such that they enable the curvature to be determined via differential strain measurement. Multiple sets of these gratings allow the curvature to be measured at several points along the fibre. In this paper, the multicore fibre is configured to measure the deflection of a simple mechanical beam arising from the displacement of concrete tunnel sections. Laboratory tests are presented in which the system was demonstrated capable of displacement measurement with a resolution of ±0.1 mm over a range of several millimetres.

MacPherson, W. N.; Silva-Lopez, M.; Barton, J. S.; Moore, A. J.; Jones, J. D. C.; Zhao, D.; Zhang, L.; Bennion, I.; Metje, N.; Chapman, D. N.; Rogers, C. D. F.

2006-05-01

210

Fibre-Matrix Interaction in Soft Tissue  

NASA Astrophysics Data System (ADS)

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.

Guo, Zaoyang

2010-05-01

211

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)

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

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

2014-01-01

212

A modified technique for direct, fibre-reinforced, resin-bonded bridges: clinical case reports.  

PubMed

This article presents new modifications to the clinical technique of fabricating directly applied resin-bonded fibre-reinforced bridges. Torsional and flexural strength is achieved by means of a reinforced polyethylene fibre ribbon substructure surrounded by laminated layers of microhybrid and microfilled resins. The modifications provide a simple method for creating a better pontic-ridge relation and improved overall esthetics. Early clinical experience suggests that this technique has the potential to give patients a relatively conservative, esthetic and periodontally noninvasive alternative for anterior tooth replacement. PMID:10946494

van Wijlen, P

2000-01-01

213

Hygrothermal Aging and Fracture of Glass Fibre-Epoxy Composites.  

National Technical Information Service (NTIS)

Fractographic data for composites of unidirectionally aligned glass fibres in epoxy were obtained for two failure parameters: fibre debond length and fibre pull-out length, which are distances over which intact fibres debond and pull out of a cracked matr...

P. D. Anstice P. W. R. Beaumont

1983-01-01

214

Diffractive beam shaping elements for high power fibre coupling  

Microsoft Academic Search

In this paper, we discuss the design and fabrication of diffractive elements for coupling applications involving multiple fibres. We present a diffractive beam homogeniser for coupling to a fibre bundle. The flexibility of diffractive optics for fibre coupling is demonstrated by elements combining homogenising and beam splitting functions for coupling to two or four individually mounted fibres. The two way

M. J. Thomson; M. R. Taghizadeh

2003-01-01

215

LFZ fibre texture modification induced by electrical polarization  

Microsoft Academic Search

Preliminary results of electric current flux application during LFZ growth of BSCCO fibres show a dramatic effect on fibre texture. The solute electromigration modifies the ionic transport and consequently the phase development, inducing a randomly crystal orientation on the as-grown fibres. After heat treatment, fibres grown with reverse electric current are three times more resistive at room temperature than those

F. M. Costa; M. F. Carrasco; N. Ferreira; R. F. Silva; J. M. Vieira

2004-01-01

216

Deterministic and Probabilistic Tractography Based on Complex Fibre Orientation Distributions  

Microsoft Academic Search

We propose an integral concept for tractography to describe crossing and splitting fibre bundles based on the fibre orientation distribution function (ODF) estimated from high angular resolution diffusion imaging (HARDI). We show that in order to perform accurate probabilistic tractography, one needs to use a fibre ODF estimation and not the diffusion ODF. We use a new fibre ODF estimation

Maxime Descoteaux; Rachid Deriche; Thomas R. Knösche; Alfred Anwander

2009-01-01

217

Coherent Beam Combination of Two Polarization Maintaining Ytterbium Fibre Amplifiers  

Microsoft Academic Search

We investigate coherent beam combination of fibre laser beams by phase locking. Phase noise of a polarization maintaining ytterbium fibre amplifier is inspected with a fibre interferometer. In a feed back control loop, two fibre polarization maintaining ytterbium amplifiers are phase locked and coherent combined when the phase noise is properly controlled by a LiNO3 phase modulator.

Jing Hou; Rui Xiao; Zong-Fu Jiang; Xiang-Ai Cheng; Bai-Hong Shu; Jin-Bao Chen; Ze-Jin Liu

2005-01-01

218

Delamination, fibre bridging and toughness of ceramic matrix composites  

SciTech Connect

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

Kaute, D.A.W.; Shercliff, H.R.; Ashby, M.F. (Cambridge Univ., Cambridge (United Kingdom). Engineering Dept.)

1993-07-01

219

Cleaving of microstructured polymer optical fibres  

NASA Astrophysics Data System (ADS)

The issue of how best to cleave PMMA microstructured polymer optical fibres (mPOF) is addressed. The impact of the following parameters on the cleaving process is considered: (i) temperature of the cutting blade, (ii) temperature of the platen holding the fibre, (iii) time allowed for thermal equilibration between fibre and platen, (iv) blade speed, and (v) blade condition. The strong influence of a temperature-dependent phase transition in the polymer on the cleaving process is established. Optically acceptable mPOF end-faces can be achieved but only over a limited range of cleavage conditions.

Law, S. H.; Harvey, J. D.; Kruhlak, R. J.; Song, M.; Wu, E.; Barton, G. W.; van Eijkelenborg, M. A.; Large, M. C. J.

2006-02-01

220

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

221

Influence of Fibre Taper on the Interfacial Shear Stress in Fibre-Reinforced Composite Materials during Elastic Stress Transfer  

Microsoft Academic Search

The paper is concerned with finite element (FE) analysis of stress transfer from an elastic matrix to an elastic fibre, which need not be a uniform cylinder, in a fibre-reinforced composite material. Axisymmetric models of fibres embedded in co-axial cylindrical matrices were investigated by the FE method. Fibre shapes investigated were cylindrical, ellipsoidal, paraboloidal taper and conical taper. The effects

K. L. Goh; J. R. Meakin; D. W. L. Hukins

2010-01-01

222

In situ self-sensing fibre reinforced composites  

Microsoft Academic Search

This paper discusses the development of a novel composite system in which some of the reinforcing fibres act as the light guide. The reinforcing fibre light guide was made by applying an appropriate cladding material onto commercially available 9 0964-1726\\/6\\/4\\/007\\/img1m diameter silica fibres. The resultant light guide was termed a `self-sensing' fibre. The self-sensing fibres were embedded within a 16-ply

S. Hayes; T. Liu; D. Brooks; S. Monteith; B. Ralph; S. Vickers; G. F. Fernando

1997-01-01

223

Significance of fibre length in the clearance of asbestos fibres from the lung.  

PubMed Central

Rats were exposed by inhalation to radioactive anthophyllite asbestos. Animals were then killed serially over a period of 205 days and the fibre content of the lungs measured radiometrically. The lungs were subjected to selective bronchopulmonary lavage and the mean fibre content determined of free cells recovered from the alveolar spaces. The length distributions of fibres recovered from the lungs by lavage, and of those remaining in the lungs following lavage, were measured. Short (less than 5 micrometer) fibres are cleared from the lung via the conducting airways more efficiently than longer fibres and fibres exceeding 50 micrometer in length are not removed from the lungs by this route. Although fibres of about 200 micrometer in length were present in all the lungs examined, the longest which could be recovered by lavage, once fibre deposited in the airways had been cleared, was only about 100 micrometer decreasing to 60-70 micrometer after 205 days. It is suggested that long fibres are more liable than short to penetrate the alveolar wall as they tend to bridge the alveolar ducts and alveoli. Images

Morgan, A; Talbot, R J; Holmes, A

1978-01-01

224

Modelling microstructure effects on the conduction in fibrous materials with fibre fibre interface barriers  

NASA Astrophysics Data System (ADS)

Conduction in fibrous materials made of highly conductive fibres and immerged in a poorly conductive matrix is modelled above the percolation threshold. Firstly, limits of discrete approaches generally used to tackle this problem are determined on elementary fibrous microstructures by comparing discrete solutions with full finite element calculations. Then, more complex 3D fibrous microstructures are numerically generated and a discrete element code is used to analyse the influence of the fibre content, aspect ratio, orientation as well as the quality of fibre-fibre contacts on the effective conductivity tensor. Lastly, a semi-empirical analytical expression is proposed to model numerical results.

Vassal, J.-P.; Orgéas, L.; Favier, D.

2008-04-01

225

Fibre communications: Time-reversed twin  

NASA Astrophysics Data System (ADS)

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.

Ip, Ezra; Kahn, Joseph M.

2013-07-01

226

Synaptic plasticity at hippocampal mossy fibre synapses.  

PubMed

The dentate gyrus provides the main input to the hippocampus. Information reaches the CA3 region through mossy fibre synapses made by dentate granule cell axons. Synaptic plasticity at the mossy fibre-pyramidal cell synapse is unusual for several reasons, including low basal release probability, pronounced frequency facilitation and a lack of N-methyl-D-aspartate receptor involvement in long-term potentiation. In the past few years, some of the mechanisms underlying the peculiar features of mossy fibre synapses have been elucidated. Here we describe recent work from several laboratories on the various forms of synaptic plasticity at hippocampal mossy fibre synapses. We conclude that these contacts have just begun to reveal their many secrets. PMID:16261180

Nicoll, Roger A; Schmitz, Dietmar

2005-11-01

227

Optical Fibre Angle Sensor Used in MEMS  

NASA Astrophysics Data System (ADS)

There is a need for displacement and angle measurements in many movable MEMS structures. The use of fibre optical sensors helps to measure micrometre displacements and small rotation angles. Advantages of this type of transducers are their simple design, high precision of processing, low costs and ability of a non-contact measurement. The study shows an analysis of a fibre-optic intensity sensor used for MEMS movable structure rotation angle measurement. An intensity of the light in the photodetector is basically dependent on a distance between a reflecting surface and a head surface of the fibre transmitting arm, and the deflection angle. Experimental tests were made for PMMA 980/1000 plastic fibres, ?NA=33°. The study shows both analytical and practical results. It proves that calculated and experimental characteristics for the analysed transducers are similar.

Golebiowski, J.; Milcarz, Sz; Rybak, M.

2014-04-01

228

Temperature independent highly birefringent photonic crystal fibre.  

PubMed

A highly birefringent photonic crystal fibre has been characterised as a function of temperature. The modal birefringence has been found to be independent of temperature from -25 to 800 degrees C. PMID:19484072

Michie, Andrew; Canning, John; Lyytikäinen, Katja; Aslund, Mattias; Digweed, Justin

2004-10-18

229

Recent progress in polymer optical fibre gratings  

NASA Astrophysics Data System (ADS)

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.

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

2008-06-01

230

Amphibole fibres in Chinese chrysotile asbestos  

Microsoft Academic Search

Ten chrysotile bulk samples originating from six Chinese chrysotile mines were studied for amphibole fibres. Five of the mines operate on ultramafic rocks whereas one exploits a dolo- mite-hosted deposit. The asbestos fibre content in lung tissue was examined from seven deceased workers of the Shenyang asbestos plant using these raw materials. The bulk samples were pretreated with acid\\/alkali-digestion, and

ANTTI TOSSAVAINEN; MIA KOTILAINEN; KEN TAKAHASHI; GUOWEI PAN; ESA VANHALA

2001-01-01

231

Sorption of Water Vapors by Armos Fibre  

Microsoft Academic Search

The extremely slow kinetics of absorption of water vapors by Armos fibre can be explained by notions concerning its cross-linked structure, which consists of units of the crystallite type and liquid-crystalline or amorphous crosslinks and has a relatively high density. Sorption of water vapors by the initial Armos fibre not treated with heat is much higher than for the heat-treated

L. Ya. Konovalova; M. M. Iovleva; G. S. Negodyaeva; G. A. Budnitskii; N. N. Machalaba

2003-01-01

232

Photonic crystal fibres in biomedical investigations  

SciTech Connect

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)

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

2011-04-30

233

Fibre optic biosensors with immobilized bioluminescence enzymes  

Microsoft Academic Search

A fibre optic biosensor involving immobilized bioluminescence enzymes associated with a glass fibre bundle has been designed. The firefly luciferase fromPhotinus pyralis, as well as the bacterial luciferase-oxidoreductase system from eitherVibrio fischeri orVibrio harveyi, have been immobilized on preactivated polyamide membranes. First, the validity of the approach is demonstrated by performing the microdetermination of adenosine triphosphate (ATP) and sodium dehydrogenase

L. J. Blum; S. M. Gautier; P. R. Coulet

1991-01-01

234

Dietary fibre in foods: a review  

Microsoft Academic Search

Dietary fibre is that part of plant material in the diet which is resistant to enzymatic digestion which includes cellulose,\\u000a noncellulosic polysaccharides such as hemicellulose, pectic substances, gums, mucilages and a non-carbohydrate component lignin.\\u000a The diets rich in fibre such as cereals, nuts, fruits and vegetables have a positive effect on health since their consumption\\u000a has been related to decreased

Devinder Dhingra; Mona Michael; Hradesh Rajput; R. T. Patil

235

Simulation of single muscle fibre action potentials  

Microsoft Academic Search

Using the volume conductor model, a single muscle fibre action potential can be expressed as a convolution of the transmembrane\\u000a current and a weighting function. By simplifying the weighting function, the line source model is derived. We have developed\\u000a similar expressions to compute the single muscle fibre action potential using simple models and physical considerations without\\u000a any mathematical complexity. The

S. D. Nandedkar

1983-01-01

236

Statistical Comparison of Cardiac Fibre Architectures  

Microsoft Academic Search

In this paper, a statistical atlas of DT-MRIs based on a population of nine ex vivo normal canine hearts is compared with a human cardiac DT-MRI and with a synthetic model of the fibre orientation. The aim\\u000a of this paper is to perform a statistical inter-species comparison of the cardiac fibre architecture and to assess the quality\\u000a of a synthetic

Jean-marc Peyrat; Maxime Sermesant; Xavier Pennec; Hervé Delingette; Chenyang Xu; Elliot R. Mcveigh; Nicholas Ayache

2007-01-01

237

Oxidation protection for carbon fibre composites  

Microsoft Academic Search

Carbon fibre-reinforced ceramic matrix composites are promising candidate materials for high-temperature structural applications such as gas turbine blades. In oxidizing environments at temperatures above 400°C, however, carbon fibres are rapidly oxidized. There is, therefore, a need to coat the composite in order to protect it against oxidation. This review identifies the requirements of an effective oxidation protection system for carbon

M. E. Westwood; J. D. Webster; R. J. Day; F. H. Hayes; R. Taylor

1996-01-01

238

Fibre-optic sensors in health care  

NASA Astrophysics Data System (ADS)

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.

Grazia Mignani, Anna; Baldini, Francesco

1997-05-01

239

Synthesis of continuous silicon carbide fibre  

Microsoft Academic Search

The polycarbosilane (PC-470) synthesized by thermal decomposition of polydimethylsilane was melt-spun. The conversion process of the fibre into silicon carbide fibre was investigated by chemical analysis, TG-DTA and infra-red spectrum analysis, and measurements of the mechanical properties and densities. The conversion process of polycarbosilane (PC-TMS) synthesized by Fritz was examined and compared with the conversion process of PC-470. It is

Y. Hasegawa; M. Iimura; S. Yajima

1980-01-01

240

Reinforcing of Cement Composites by Estabragh Fibres  

NASA Astrophysics Data System (ADS)

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.

Merati, A. A.

2014-06-01

241

Relevance Vector Machine and Support Vector Machine Classifier Analysis of Scanning Laser Polarimetry Retinal Nerve Fiber Layer Measurements  

PubMed Central

Purpose To classify healthy and glaucomatous eyes using relevance vector machine (RVM) and support vector machine (SVM) learning classifiers trained on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry (SLP). Methods Seventy-two eyes of 72 healthy control subjects (average age = 64.3 ± 8.8 years, visual field mean deviation =?0.71 ± 1.2 dB) and 92 eyes of 92 patients with glaucoma (average age = 66.9 ± 8.9 years, visual field mean deviation =?5.32 ± 4.0 dB) were imaged with SLP with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, San Diego, CA). RVM and SVM learning classifiers were trained and tested on SLP-determined RNFL thickness measurements from 14 standard parameters and 64 sectors (approximately 5.6° each) obtained in the circumpapillary area under the instrument-defined measurement ellipse (total 78 parameters). Tenfold cross-validation was used to train and test RVM and SVM classifiers on unique subsets of the full 164-eye data set and areas under the receiver operating characteristic (AUROC) curve for the classification of eyes in the test set were generated. AUROC curve results from RVM and SVM were compared to those for 14 SLP software-generated global and regional RNFL thickness parameters. Also reported was the AUROC curve for the GDx VCC software-generated nerve fiber indicator (NFI). Results The AUROC curves for RVM and SVM were 0.90 and 0.91, respectively, and increased to 0.93 and 0.94 when the training sets were optimized with sequential forward and backward selection (resulting in reduced dimensional data sets). AUROC curves for optimized RVM and SVM were significantly larger than those for all individual SLP parameters. The AUROC curve for the NFI was 0.87. Conclusions Results from RVM and SVM trained on SLP RNFL thickness measurements are similar and provide accurate classification of glaucomatous and healthy eyes. RVM may be preferable to SVM, because it provides a Bayesian-derived probability of glaucoma as an output. These results suggest that these machine learning classifiers show good potential for glaucoma diagnosis.

Bowd, Christopher; Medeiros, Felipe A.; Zhang, Zuohua; Zangwill, Linda M.; Hao, Jiucang; Lee, Te-Won; Sejnowski, Terrence J.; Weinreb, Robert N.; Goldbaum, Michael H.

2010-01-01

242

Development of high-power holmium-doped fibre amplifiers  

NASA Astrophysics Data System (ADS)

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 ?m. 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 ?m. This monolithic all-fibre system is able to address a wide range of remote sensing, scientific, medical and defence applications.

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

2014-03-01

243

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

PubMed Central

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.

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

2014-01-01

244

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

PubMed Central

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.

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

2013-01-01

245

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

NASA Astrophysics Data System (ADS)

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.

Butylina, Svetlana; Martikka, Ossi; Kärki, Timo

2011-04-01

246

Spun microstructured optical fibres for Faraday effect current sensors  

SciTech Connect

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)

Chamorovsky, Yury K; Starostin, Nikolay I; Morshnev, Sergey K; Gubin, Vladimir P; Ryabko, Maksim V; Sazonov, Aleksandr I; Vorob'ev, Igor' L [Kotel'nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino, Moscow Region (Russian Federation)

2009-11-30

247

The abrasive wear behaviour of continuous fibre polymer composites  

Microsoft Academic Search

The dry abrasive-dominant wear behaviour of several composite materials consisting of uni-directional continuous fibres and polymer matrices was investigated. Seven materials were examined: neat epoxy (3501-6), carbon fibre epoxy (AS4\\/3501-6), glass fibre\\/epoxy (E-glass\\/ 3501-6), aramid fibre\\/epoxy (K49\\/3501-6), neat polyetheretherketone (PEEK), carbon fibre\\/PEEK (APC2) and aramid fibre\\/PEEK (K49\\/PEEK). The wear behaviour of the materials was characterized by experimentally determining the friction

M. Cirino; R. B. Pipes; K. Friedrich

1987-01-01

248

A new constitutive model for multi-layered collagenous tissues  

Microsoft Academic Search

Collagenous tissues such as the aneurysmal wall or the aorta are multi-layered structures with the mean fibre alignments distinguishing one layer from another. A constitutive representation of the multiple collagen layers is not yet developed, and hence the aim of the present study. The proposed model is based on the constitutive theory of finite elasticity and is characterized by an

Martin Kroon; Gerhard A. Holzapfel

2008-01-01

249

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

NASA Astrophysics Data System (ADS)

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

Wu, Guocai; Yang, Jenn-Ming

2005-04-01

250

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

PubMed

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

Zhao, Yucheng; Li, Yahua; Jackson, Stuart

2004-08-23

251

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

NASA Astrophysics Data System (ADS)

Pumped by a narrow band Nd3+-doped fibre laser, a grating-free three-wavelength Raman fibre laser has been demonstrated. More than 1.3W output power at the third Stokes line of 1230 nm, a bandwidth of 1.8nm and a slope efficiency of ~28% was measured. A four-wavelength Raman fibre laser was also demonstrated using a different resonator that consisted of a 4% fibre end reflector, a dielectric mirror and a single fibre Bragg grating. This method is simple, versatile and cheap compared with conventional methods employing fibre Bragg gratings used to resonate all Stokes wavelengths.

Zhao, Yucheng; Li, Yahua; Jackson, Stuart D.

2004-08-01

252

Microarray Analysis of Developing Flax Hypocotyls Identifies Novel Transcripts Correlated with Specific Stages of Phloem Fibre Differentiation  

PubMed Central

Background and Aims Hypocotyls are a commonly used model to study primary growth in plants, since post-germinative hypocotyls increase in size by cell elongation rather than cell division. Flax hypocotyls produce phloem fibres in bundles one to two cell layers thick, parallel to the protoxylem poles of the stele. Cell wall deposition within these cells occurs rapidly at a well-defined stage of development. The aim was to identify transcripts associated with distinct stages of hypocotyl and phloem fibre development. Methods Stages of flax hypocotyl development were defined by analysing hypocotyl length in relation to fibre secondary wall deposition. Selected stages of development were used in microarray analyses to identify transcripts involved in the transition from elongation to secondary cell wall deposition in fibres. Expression of specific genes was confirmed by qRT-PCR and by enzymatic assays. Key Results Genes enriched in the elongation phase included transcripts related to cell-wall modification or primary-wall deposition. Transcripts specifically enriched at the transition between elongation and secondary wall deposition included ?-galactosidase and arabinogalactan proteins. Later stages of wall development showed an increase in secondary metabolism-related transcripts, chitinases and glycosyl hydrolases including KORRIGAN. Microarray analysis also identified groups of transcription factors enriched at one or more stages of fibre development. Subsequent analysis of a differentially expressed ?-galactosidase confirmed that the post-elongation increase in ?-galactosidase enzyme activity was localized to phloem fibres. Conclusions Transcripts were identified associated with specific stages of hypocotyl development, in which phloem fibre cells were undergoing thickening of secondary walls. Temporal and spatial regulation of ?-galactosidase activity suggests a role for this enzyme in remodelling of flax bast fibre cell walls during secondary cell wall deposition.

Roach, Melissa J.; Deyholos, Michael K.

2008-01-01

253

Ca²+ sorption on regenerated cellulose fibres.  

PubMed

High calcium content in cellulose materials can cause considerable problems in pulp processing, textile chemical treatment and consumer use, e.g. dyeing operations or household laundry. The Ca(2+) binding capacity of cellulose also is of relevance in food and medical applications. Through their carboxyl group content regenerated cellulose fibres can act as weak anion exchangers, thus all types of regenerated cellulose fibres such as lyocell, viscose and modal fibres, show a distinct ability to bind Ca(2+) ions. The binding capacity is limited by the carboxyl group content, which was determined with 15 mmol/kg for lyocell fibres and 20 mmol/kg for viscose fibres, using the Methylene Blue sorption method. The presence of bound Ca(2+) also was demonstrated by complex formation with alizarin. The molar ratio between carboxylic group content and bound Ca(2+) ions was one Ca(2+) ion for a single carboxyl group. As a result of Ca(2+) sorption a positive net charge of the cellulose results and another anion has to be bound as counter ion for reasons of charge neutralisation. Results of potentiometric titrations indicate HCO(3)(-) to be present as counter ion in the Ca(2+) cellulose system. Thus under the experimental conditions studied, bound Ca(2+) is proposed to be present in the form COO(-)Ca(2+)HCO(3)(-). PMID:22840023

Fitz-Binder, Christa; Bechtold, Thomas

2012-10-01

254

Are Fibre Channel SANs a Commodity?  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

255

Flexible, fibre-addressable surface-plasmon-resonance chip  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) sensors exploit optical coupling to surface plasmons, light waves bound to a metal surface. In the most common configuration, a SPR sensor is used with an external light source, optical components to polarize incident light and guide light to and from a metal surface, a coupling device to convert free-space light into surface plasmons and back into free-space light, and a light detector. The light source, the optical components, and the light detector are external to the SPR device, and the coupling structure is often integrated directly with the surface-plasmon-sustaining metal surface. The requirement of several external components restricts the miniaturization of SPR devices and prohibits low-cost implementation. To address these limitations, we design, fabricate, and test a new SPR device chip that is fibre-addressable, does not require a discrete coupling structure, and integrates light delivery, light polarization control, surface plasmon coupling onto a thin, flexible substrate. Our SPR chip is constructed from a thin gold layer deposited on top of a clear plastic sheet, which is then optically connected from the bottom surface onto a plastic linear polarizer sheet. Two cleaved fibres, one to input light and the other to collect reflected light, are then optically attached to SPR device. We experimentally characterize the SPR device and find good agreement between our measurements and a theoretical model based on transfer matrix formalism.

Chowdhury, Faqrul; Chau, Kenneth J.

2012-02-01

256

UV curing of optical fibre coatings using excimer lamps  

NASA Astrophysics Data System (ADS)

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

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

2002-01-01

257

TEM investigations of the fibre\\/matrix interface in SCS6 SiC\\/Ti–25Al–10Nb–3V–1Mo composites  

Microsoft Academic Search

Interfacial reactions in SCS-6 SiC\\/Ti–25Al–10Nb–3V–1Mo composites processed by fibre coating with matrix material, hot isostatic pressing and thermal treating for simulation of service conditions were studied by analytical transmission electron microscopy. In the as-processed specimen three reaction layers were observed. Adjacent to C coating of the SCS-6 fibre no mixture of TiC and Ti5Si3 was found reported in literature [Rhodes,

Y. Q. Yang; H. J. Dudek; J. Kumpfert

1998-01-01

258

Realization of the strength of Armos fibres with different acidity in epoxy plastics  

Microsoft Academic Search

The acidity of Armos fibres significantly affects the strength of the fibre in a microplastic as a function of the moisture content of the starting fibre. There is an optimum moisture content at which maximum realization of the fibre strength in the microplastic is attained for each fibre pH. The highest strength of the adhesive bond of Armos fibre is

S. V. Kotomin; A. A. Basharov; V. G. Bova; E. M. Sapozhnikov

1996-01-01

259

The study of polyacrylonitrile-based activated carbon fibres for water purification: Part I  

Microsoft Academic Search

Activated carbon fibres in a tow, fabric or felt form have received increasing attention in recent years as an adsorbent, filter, etc., for filtering automobile gasoline, deodorizing tobacco smoke, recovering solvents, purifying water, etc. Activated carbon fibre is produced by carbonizing a raw material such as polyacrylonitrile (PAN) fibre, cellulosic fibre, phenol resin fibre or pitch fibre and subsequently activating

Tse-Hao Ko; P. Chiranairadul; Chung-Hua Lin

1992-01-01

260

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

261

Uv-written in-fibre Bragg gratings  

Microsoft Academic Search

The techniques for fabrication and the properties of periodic and aperiodic fibre Bragg gratings produced by UV exposure in photosensitive optical fibres are reviwwed with an emphasis on applications.

I. Bennion; J. A. R. Williams; L. Zhang; K. Sugden; N. J. Doran

1996-01-01

262

Nanostructured fibre tip for trapping of nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

263

Porous Materials Reinforced by Statistically Oriented Fibres  

NASA Astrophysics Data System (ADS)

Hydrated soft biological tissues, such as articular cartilage, are well represented by a porous matrix saturated by a fluid and reinforced by a network of statistically oriented, impermeable collagen fibres. A previously developed homogenisation method for porous fibre-reinforced materials with an isotropic matrix, under small deformations, was capable of correctly predicting some specific aspects of the anisotropy and inhomogeneity of the permeability in the tissue. The aim of this work is to generalise this model to the case of large deformations. This is achieved by means of a rescaled pull-back of the structure tensor describing fibre orientation, and directional averaging methods allowing to account for the statistical distribution of the orientation. The resulting permeability tensor contains an integral term that must be implemented numerically, because of the explicit presence of the deformation in the integrand function.

Federico, Salvatore; Grillo, Alfio

2010-09-01

264

On the topology of chromatin fibres  

PubMed Central

The ability of cells to pack, use and duplicate DNA remains one of the most fascinating questions in biology. To understand DNA organization and dynamics, it is important to consider the physical and topological constraints acting on it. In the eukaryotic cell nucleus, DNA is organized by proteins acting as spools on which DNA can be wrapped. These proteins can subsequently interact and form a structure called the chromatin fibre. Using a simple geometric model, we propose a general method for computing topological properties (twist, writhe and linking number) of the DNA embedded in those fibres. The relevance of the method is reviewed through the analysis of magnetic tweezers single molecule experiments that revealed unexpected properties of the chromatin fibre. Possible biological implications of these results are discussed.

Barbi, Maria; Mozziconacci, Julien; Victor, Jean-Marc; Wong, Hua; Lavelle, Christophe

2012-01-01

265

Distributed crystal fibre sensing for extreme environments  

NASA Astrophysics Data System (ADS)

Distributed sensing of temperature can be achieved by using time-correlated two-photon excited fluorescence (TPF). To assess the extension of this technique to crystal fibres for high temperature applications, various aspects are considered including the two-photon absorption cross-section (?), dopant density and the geometry of single crystal fibres. By comparing the fluorescence yield for two-photon excitation with that for single-photon excitation of the same transition, ? for ruby was measured over the 0.8-1.2 ?m range with maximum room temperature values of 5.9 × 10-3 GM for epolarisation and 4.6 × 10-3 GM for o-polarisation at 840 nm. It is shown that values of this magnitude are adequate for a practical TPF based crystal fibre sensor to be realised.

Dalzell, Craig J.; Han, Thomas P. J.; Ruddock, Ivan S.

2010-09-01

266

Classification of Wood Pulp Fibre Cross-Sectional Shapes  

NASA Astrophysics Data System (ADS)

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

Yamakawa, Asuka; Chinga-Carrasco, Gary

267

Fibre function and perception during cutaneous nerve block.  

PubMed

In awake human subjects, neural responses in radial nerves to electrical stimulation were recorded with intrafascicular tungsten microelectrodes. Changes in the activity of individual fibre groups during blocking procedures were recorded and correlated with simultaneous alterations in the perception of standardized stimuli. Light touch sensibility in hairy skin appeared to depend on the integrity of A-beta-gamma fibres, cold and pinprick on A-delta fibres, and warmth and dull pain on C fibres. PMID:1185225

Mackenzie, R A; Burke, D; Skuse, N F; Lethlean, A K

1975-09-01

268

Fibre function and perception during cutaneous nerve block.  

PubMed

In awake human subjects, neural responses in cutaneous nerves to electrical stimulation were recorded with intrafascicular tungsten micro-electrodes. Changes in the activity of individual fibre groups during blocking procedures were recorded and correlated with simultaneous alterations in the perception of standardized stimuli. Light touch sensibility in hairy skin was mediated by A-beta-gamma fibres, cold and pinprick by A-delta fibres and warmth and dull pain by C fibres. PMID:1215398

Mackenzie, R A; Burke, D; Skuse, N F; Lethlean, A K

1975-01-01

269

Cellulose fibre-supported pH-sensitive hydrogels  

Microsoft Academic Search

pH-sensitive cellulose fibre-supported hydrogels were prepared by ozone-induced graft polymerization of acrylic acid using cotton linters and wood pulp fibre substrates. An average amount of grafting of 60% was achieved on to the ozonized wood pulp fibres after only 1 min of graft polymerization. Grafted polyacrylic acid completely covered the cellulose fibre surfaces, as determined with electron spectroscopy for chemical

J. O. Karlsson; P. Gatenholm

1999-01-01

270

Chemical fibres — An important factor in economic development  

Microsoft Academic Search

1997 set a record for the past 20 years in the growth rate of world production of chemical fibres and filaments. In comparison\\u000a to 1996, this figure, was 11%, primarily due to synthetic fibres, where polyester fibres still occupy the leading position\\u000a (approximately 15 million tons). Production of cellulose (viscose, acetate, cuprammonium) fibres and filaments dropped, especially\\u000a for industrial applications.

E. M. Aizenshtein

1998-01-01

271

Optical and electrochemical measurements for optical fibre corrosion sensing techniques  

Microsoft Academic Search

The feasibility of an optical fibre corrosion sensor (OFCS) was studied. A multi-mode fibre was metallised by physical vacuum deposition and electroplating of a Fe–C alloy film on a 1–2cm uncladded section of an optical fibre. The shift of light power transmitted through the fibre was registered with corrosion. Microanalysis was carried out to show the formation of metallised film.

Saying Dong; Yanbiao Liao; Qian Tian; Yanan Luo; Zhigang Qiu; Shizhe Song

2006-01-01

272

Improvement of fibre and composites for new markets  

Microsoft Academic Search

Plant fibres have decisive advantages compared with synthetic fibres. One great advantage of plant fibres is their optimized\\u000a strength to weight ratio. Others are their better workability as a result of optimum fibre length and cell wall thickness,\\u000a their high anisotropic qualities and their good ion exchange capacity. The natural products are readily biodegradable and\\u000a renewable.

Marcel Toonen; Michel Ebskamp; Robert Kohler

2006-01-01

273

On non-Hookean behaviour of carbon fibres in bending  

Microsoft Academic Search

The deformation characteristics of a range of single, large diameter pitch-based carbon fibres, and some PAN- and rayon-based fibres, were studied in elastica loop bending experiments. In pitch-based fibres, non-Hookean behaviour was found to occur at lower strains the greater the fibre anisotropy. Only elastic deformation to failure, at strains of 3%, was found for low-modulus, nearly isotropic pitch- and

H. M. Hawthorne

1993-01-01

274

Presynaptic Calcium Signalling in Cerebellar Mossy Fibres  

PubMed Central

Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX)-sensitive fast Na+ spike faithfully followed repetitive depolarizing pulses with little change in spike duration or amplitude, while a strong outward rectification dominated responses to long-lasting depolarizations. High-threshold calcium spikes were uncovered following addition of potassium channel blockers. Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1?s affected burst firing in mossy fibres; this paired-pulse depression was reduced by GABA B antagonists. While our results indicated that a presynaptic rosette electrophysiologically functioned as a unit, topical GABA application showed that calcium signals in the branches of complex rosettes could be modulated locally, suggesting that cerebellar glomeruli may be dynamically sub-compartmentalized due to ongoing inhibition mediated by Golgi cells. This could provide a fine-grained control of mossy fibre-granule cell information transfer and synaptic plasticity within a mossy fibre rosette.

Thomsen, Louiza B.; Jorntell, Henrik; Midtgaard, Jens

2009-01-01

275

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

PubMed

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

Baker; Grant; Jenkins

1999-11-01

276

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

PubMed

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

Blank, Britta; Schlecht, Eva; Susenbeth, Andreas

2012-04-01

277

Fibre-optic current sensor exploiting Sagnac interferometer with Lyot-type fibre depolarizers  

NASA Astrophysics Data System (ADS)

A Sagnac interferometer-type fibre-optic current sensor using single-mode fibre was proposed. To prevent non-reciprocal phase error, depolarizers are used in the Sagnac coil. This configuration makes the current sensor less costly and rather accurate. We fabricated the current sensor for an electric power substation by using the proposed technique and confirmed its characteristics. The dynamic range of 50 dB and ratio error within ±0.2% were satisfied. These results have demonstrated that the Sagnac interferometer-type current sensor using a single-mode fibre is suitable as an instrument for electric power plants.

Kostritskii, S. M.; Dikevich, A. A.; Korkishko, Yu N.; Fedorov, V. A.

2013-03-01

278

Wavelength-shifting-fibre-based neutron image detector with a fibre-optic taper to increase the spatial resolution  

NASA Astrophysics Data System (ADS)

The effective pixel size of a two-dimensional wavelength-shifting-fibre (WLS-fibre)-based neutron image detector was improved from 0.5 to 0.16 mm by including a fibre-optic taper (FOT) between the scintillator screen and the WLS fibre. The WLS-fibre-based detector consisted of a thin ZnS/ 6LiF screen, a FOT and WLS ribbons crossed in the x and y directions. The demonstrator detector had 16 fibre channels in each direction, and the light signals in each fibre were read out individually. The FOT was constructed from fine glass fibres with a taper ratio of 3.1 and served as an image magnifier. The prototype detector equipped with the FOT exhibited a spatial resolution of 0.3 mm, compared to the spatial resolution of 0.8 mm of the original detector without the FOT.

Nakamura, T.; Katagiri, M.; Toh, K.; Sakasai, K.; Ebine, M.; Birumachi, A.; Soyama, K.

2009-06-01

279

A highly flexible polymer fibre battery  

NASA Astrophysics Data System (ADS)

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

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

280

Fabrication of thin oxide coatings on ceramic fibres by a sol-gel technique  

Microsoft Academic Search

Various metal oxides are potential reaction barriers in titanium\\/silicon carbide composites. A sol-gel process utilizing metal alkoxides was developed to coat silicon carbide fibres with relatively thick, crack-free, adherent layers of yttrium and calcium oxide. A multiple-dip technique was employed in order to avoid cracking due to large residual thermal and drying stresses produced in the film. The influence of

D. B. Gundel; P. J. Taylor; F. E. Wawner

1994-01-01

281

Object-oriented stochastic finite element analysis of fibre metal laminates  

Microsoft Academic Search

This paper deals with issues arising from the stochastic simulation of fibre metal laminates. The elasticity modulus of the composite layer is assumed to be a random process. An object-oriented computational framework is proposed, which can be integrated with an existing object-oriented deterministic infrastructure. This framework is utilized to implement a spectral stochastic version of the solid-like shell element. Modelling

Doo Bo Chung; Miguel A. Gutiérrez; René de Borst

2005-01-01

282

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

Microsoft Academic Search

Structural impact tests were first presented to cover typical fibre metal laminates (FMLs) subjected a low velocity projectile\\u000a impact, which produced the corresponding load-displacement traces and deformation\\/failure modes for the validation of numerical\\u000a models. Finite element (FE) models were then developed to simulate the impact behaviour of FMLs tested. The aluminium (alloy\\u000a grade 2024-0) layer was modelled as an isotropic

Jiying Fan; Zhongwei Guan; W. J. Cantwell

2011-01-01

283

Fracture Micromechanisms of Fibre-Metal Laminates: In-Situ SEM Observations  

Microsoft Academic Search

The monotonic fracture micromechanisms of an aramid-aluminum laminate were studied using very small single edge bend specimens, SE(B) tested in a small-instrumented testing machine inside a scanning electron microscope. Thefracture process was followed by simultaneous observation of the sample and recording the loading variables. The instability fracture toughness was strongly dependent on the fibre-reinforced epoxy layer and the crack-growth in

E. M. Castrodeza; F. L. Bastian; A. Yawny; J. E. Perez Ipiña

2002-01-01

284

Preparation of divinyl-PDMS\\/PVDF composite hollow fibre membranes for BTX removal  

Microsoft Academic Search

Microporous polyvinylidene fluoride (PVDF) hollow fibre membranes spun using the dry–wet phase inversion method were coated with cross-linkable divinyl-terminated silicone rubber, divinyl-polydimethylsiloxane (divinyl-PDMS). Cross-sectional structure of the composite membranes formed was examined using scanning electron microscopy (SEM), displaying a uniform coating thickness of approximately 5–7?m. Oxygen\\/nitrogen selectivity over 2.24 was obtained, indicating successful formation of selective coating layer. Removal of

M. L. Yeow; R. W. Field; K. Li; W. K. Teo

2002-01-01

285

Electrokinetic approach of adhesion between polyester fibres and latex matrices  

Microsoft Academic Search

The adhesive interaction between salt-treated polyester fibres and elastomeric matrices has been studied. Two types of approaches have been used to predict the impact of the salt treatment on the interaction between both jointing partners. First of all ?-potential measurements have been used to characterize the interactions between fibre and matrix. Changes in the surface composition of salt-treated fibres were

C Campagne; E Devaux; A Perwuelz; C Cazé

2002-01-01

286

Relations between cadmium and magnesium and aronia fractional dietary fibre  

Microsoft Academic Search

The aim of this investigation was to analyse the composition of dietary fibre from aronia pomace preparations and to evaluate its influence on cadmium and magnesium binding. The authors wanted also to estimate to what extent additional enzymatic processing could affect the sorption capacity of the aronia fibre.Fibre preparations of aronia pomace possessed poor cadmium-binding capacity and desorbed magnesium, which

Bozena Borycka; Jadwiga Stachowiak

2008-01-01

287

All-fibre OPO system for visible wavelengths  

Microsoft Academic Search

An all-fibre PCF-based optical parametric oscillator at 718 nm, spliced to and synchronously pumped by an all-fibre Yb-doped MOPA, reaches an average in-fibre pump-to-anti-Stokes power conversion efficiency of 10.3% at a frequency-shift of 140 THz.

Gys J. Van der Westhuizen; Johan Nilsson

2011-01-01

288

Fatigue crack propagation in polypropylene reinforced with short glass fibres  

Microsoft Academic Search

Fatigue crack propagation (FCP) behaviour of polypropylene composites reinforced with short glass fibres has been investigated as a function of fibre content and frequency of the sinusoidal applied load. The FCP resistance of the composites was found to improve as the fibre weight fraction increased. Results for all composites showed a dramatic decrease in the crack growth rate per cycle

Alessandro Pegoretti

1999-01-01

289

Mechanical properties of sisal fibre at elevated temperatures  

Microsoft Academic Search

Sisal fibres extracted from the leaves of Agava sisalana plants 3, 5, 7 and 9 years old were tested at different temperatures for tensile strength, elongation, toughness and modulus. The tensile strength, modulus and toughness values of sisal fibre decreased with increase in temperature. The effect of plant age on tensile strength, tensile modulus and toughness of sisal fibre became

Navin Chand; S. A. R. Hashmi

1993-01-01

290

Optical fibre sensors for monitoring of welding residual stresses  

Microsoft Academic Search

Transient and residual strains in the heat affected zone (HAZ) of a TIG arc welded aluminium–magnesium alloy test plate have been measured on line using fibre Bragg grating sensors. The optical fibre sensor operates as a reflection filter: when a light beam travelling along the fibre optic reaches the Bragg grating, only a certain wavelength will be reflected. The reflected

J. C Suárez; B Remart??nez; J. M Menéndez; A Güemes; F Molleda

2003-01-01

291

Unreinforced and carbon fibre reinforced hydroxyapatite: resistance against microabrasion  

Microsoft Academic Search

Hot pressing (1000–1150 °C, 25 MPa, 15 min, argon atmosphere) was used to process unreinforced and carbon short fibre reinforced hydroxyapatite (20% fibre volume fraction). Due to the selected processing parameters, a fine grained crystalline calcium hydroxyapatite matrix without any decomposition products and a close contact between the slightly curved surface of the carbon fibres and the hydroxyapatite was realized. The

Annett Dorner-Reisel; Karl Berroth; Rainer Neubauer; Klaus Nestler; Günter Marx; Magdalena Scislo; Eberhard Müller; Anna Slosarcyk

2004-01-01

292

Femtosecond soliton supercontinuum generation in anisotropic microstructure fibre  

Microsoft Academic Search

The polarization anisotropy of microstructure fibre may be introduced especially to provide more possibilities to control the supercontinuum production. Thus polarization degree of freedom should be incorporated to the numerical model. In this paper we analyze numerically the supercontinuum generation in the microstructure fibres with periodically modulated holes ellipticity. Femtosecond pulse propagation in single mode microstructure fibre was described by

Yulia Mazhirina; Leonid Melnikov; Andrey Konukhov

2009-01-01

293

Solvent Retention and Fibre Chemistry.  

National Technical Information Service (NTIS)

The aim of this study was to understand in which way different chemical and physical treatments affect the solvent retention properties of pulps used in the middle layer of folding boxboard. The solvent retention properties of the treated pulps were exami...

M. Rantanen

2003-01-01

294

Evaluation of Protein Immobilisation Techniques on Optical Fibre Tirf Sensor  

NASA Astrophysics Data System (ADS)

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

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

2000-12-01

295

Fabrication of intrinsic fibre Fabry–Perot cavities in silica optical fibres via F2-laser ablation  

Microsoft Academic Search

This paper reports on a technique for fabricating intrinsic fibre Fabry–Perot cavities in fused silica optical fibres. An F2-excimer laser was used to micromachine parallel walled cavities through the diameter of optical fibres. A custom-designed beam delivery and target alignment system was used to enable the production of high aspect-ratio cavities in fibres. The optical response of the micro-cavities ablated

V R Machavaram; R A Badcock; G F Fernando

2007-01-01

296

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

PubMed Central

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

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

2013-01-01

297

Simulating damage and delamination in fibre metal laminate joints using a three-dimensional damage model with cohesive elements and damage regularisation  

Microsoft Academic Search

This paper investigates the capability of a three-dimensional finite element model with damaging material behaviour, cohesive elements and damage regularisation to simulate complex damage patterns in fibre metal laminate (FML) joints. The model incorporates a three-dimensional continuum damage mechanics approach for the composite plies, a plasticity model for the aluminium layers, and a delamination model between layers. A nonlocal averaging

R. M. Frizzell; C. T. McCarthy; M. A. McCarthy

2011-01-01

298

Fibre Break Failure Processes in Unidirectional Composites. Part 3: Unidirectional Plies Included in Laminates  

NASA Astrophysics Data System (ADS)

The purpose of these three papers is not to just revisit the modelling of unidirectional composites. It is to provide a robust framework based on physical processes that can be used to optimise the design and long term reliability of internally pressurised filament wound structures. The results given in paper Parts 1 and 2 concerning the behaviour of unidirectional composites, such as carbon fibre reinforced epoxy resin, are, here, extended to the behaviour of cross-plied composites consisting of unidirectional plies orientated at different angles with respect to the loading direction. In these laminates the plies orientated parallel to the loading direction (at 0?) control the ultimate failure of the composite. This paper shows that the development of fibre breaks in analogous to that seen in the studies described in Part 1 and 2. Clustering of fibre breaks, shown by the development of 32-plets, preceedes failure just before specimen loaded monotonically break but develop in a more stable manner when subjected to steady high level loads. The effect of separating the 0? plies into thinner layers impedes the development of fibre breaks clusters and increases ultimate lifetimes.

Thionnet, A.; Chou, H. Y.; Bunsell, A.

2014-05-01

299

Self Healing Fibre-reinforced Polymer Composites: an Overview  

NASA Astrophysics Data System (ADS)

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

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

300

Process monitoring of aluminum-foam sandwich structures based on thermoplastic fibre–metal laminates using fibre Bragg gratings  

Microsoft Academic Search

This paper reports the use of fibre Bragg gratings (FBGs) for monitoring the fabrication process in a novel sandwich structure based on thermoplastic fibre–metal laminate (FML) skins and an aluminum-foam core. The FBG sensors were embedded between two plies of glass fibre reinforced polypropylene within the FML and the shift in the Bragg wavelength was recorded during the fabrication cycle

K. S. C. Kuang; L. Zhang; W. J. Cantwell; I. Bennion

2005-01-01

301

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

NASA Astrophysics Data System (ADS)

Reinforced plastic materials are widely used in high sophisticated applications. The length distribution of the fibres influences the mechanical properties of the final product. A method for automatic determination of this length distribution was developed. After separating the fibres out of the composite material without any damage, and preparing them for microscopical analysis, a mosaic of microscope pictures is taken. After image processing and analysis with mathematical methods, a complete statistic of the fibre length distribution could be determined. A correlation between fibre length distribution and mechanical properties, measured e.g. with material test methods, like tensile and impact tests, was found. This is a method to optimize the process and selection of material for the plastic parts. In result this enhances customer satisfaction and, maybe much more important, reduces costs for the manufacturer.

Hartwich, Mark R.; Höhn, Norbert; Mayr, Helga; Sandau, Konrad; Stengler, Ralph

2009-06-01

302

Conductive wood microfibres for smart paper through layer-by-layer nanocoating  

Microsoft Academic Search

A layer-by-layer (LbL) self-assembly of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) on lignocellulose wood microfibres was used to make conductive fibres and paper. Polycations such as poly(allylamine hydrochloride) (PAH), and poly(ethyleneimine) (PEI) were used in alternate deposition with anionic conductive polythiophene (PEDOT-PSS) to construct the multilayer nanofilms on wood microfibres. Current-voltage characterization was measured on single fibres using a Keithley probe measurement system after

Mangilal Agarwal; Yuri Lvov; Kody Varahramyan

2006-01-01

303

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

NASA Astrophysics Data System (ADS)

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

Konidakis, Ioannis; Konstantaki, Maria; Pissadakis, Stavros

2014-03-01

304

The failure of fibre composites and adhesively bonded fibre composites under high rates of test  

Microsoft Academic Search

The failure of fibre composites under high rates of test was studied in detail, using a fracture mechanics approach to determine values of the fracture energies. The present paper, Part III of the series, considers the fracture of two different fibre composite materials under mixed-mode tensile and shear (i.e. mixed-mode I\\/II) and shear (i.e. mode II) loadings. Part I considered

B. R. K. Blackman; J. P. Dear; A. J. Kinloch; H. MacGillivray; Y. Wang; J. G. Williams; P. Yayla

1996-01-01

305

Regenerated fibre Bragg grating fabricated on high germanium concentration photosensitive fibre for sensing at high temperature  

NASA Astrophysics Data System (ADS)

A Regenerated Fibre Bragg Grating (RFBG), with repeatable high temperature response between 400 °C-1200 °C, has been demonstrated using a hydrogen-loaded, highly germanium-doped, photosensitive fibre. A wavelength shifts of as much as 20 nm is attained during temperature calibration up to 1300 °C. A large temperature response of 17 pm/°C is obtained from the RFBG, with very good repeatability.

Chong, S. S.; Chong, W. Y.; Harun, S. W.; Ahmad, H.

2012-06-01

306

Structure, composition and mechanical properties of the silk fibres of the egg case of the Joro spider, Nephila clavata (Araneae, Nephilidae).  

PubMed

The silk egg case and orb web of spiders are elaborate structures that are assembled from a number of components. We analysed the structure, the amino acid and fibre compositions, and the tensile properties of the silk fibres of the egg case of Nephila clavata. SEM shows that the outer and inner covers of the egg case consist of thick, medium and thin silk fibres. The silk fibres of the outer cover of the egg case are probably produced by the major and minor ampullate glands. The silk fibres of the inner cover of the egg case from cylindrical glands appears to be distinct from the silk fibres of the major ampullate glands based on their micro-morphology, mole percent amino acid composition and types, and tensile behaviour and properties. Collectively, our investigations show that N. clavata uses silk fibres from relatively few glands in varying combinations to achieve different physical and chemical properties (e.g., color, diameter, morphology and amino acid composition) and functional and mechanical properties in the different layers of the egg case. PMID:22116288

Jiang, Ping; Guo, Cong; Lv, Taiyong; Xiao, Yonghong; Liao, Xinjun; Zhou, Bing

2011-12-01

307

Activated carbon fibre materials for VOC removal  

Microsoft Academic Search

Activated carbon material has been used for many years in air cleaning applications. Powder form activated carbon has been gradually replaced by activate carbon fibre, which allows much smaller pores - specific area of such material may reach up to 2000 m2\\/g. An experimental dynamic volatile organic compound (VOC) generation system has been developed in order to test new types

P Navarri; D Marchal; A Ginestet

2001-01-01

308

Metal-insulator-semiconductor optoelectronic fibres  

Microsoft Academic Search

The combination of conductors, semiconductors and insulators with well-defined geometries and at prescribed length scales, while forming intimate interfaces, is essential in most functional electronic and optoelectronic devices. These are typically produced using a variety of elaborate wafer-based processes, which allow for small features, but are restricted to planar geometries and limited coverage area. In contrast, the technique of fibre

Mehmet Bayindir; Fabien Sorin; Ayman F. Abouraddy; Jeff Viens; Shandon D. Hart; John D. Joannopoulos; Yoel Fink

2004-01-01

309

Two-frequency fibre Raman laser  

SciTech Connect

A new scheme of a fibre Raman laser emitting at two wavelengths is proposed. The scheme uses a one-stage Raman converter with the output Bragg grating with the reflectivity above 99%. Lasing at two wavelengths is achieved due to the overlap of the output emission spectrum with the reflection spectrum of the output Bragg grating. (lasers)

Paramonov, Vladimir M; Kurkov, Andrei S; Medvedkov, O I; Grukh, Dmitrii A; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2004-03-31

310

Left ventricular fibre architecture in man  

Microsoft Academic Search

In order to investigate the possibility of regional variation of ventricular structure, 25 normal postmortem human hearts were studied by inspection of cavity shape and subepicardial fibre orientation, by dissection, and by the histology of sections in two orthogonal planes. Ventricular architecture was complex. Inlet and outlet long axes were separated by 30 degrees in the left ventricle. In the

R. A. Greenbaum; S. Y. Ho; D. G. Gibson; A. E. Becker; R. H. Anderson

1981-01-01

311

Refractory Period in Human Sensory Nerve Fibres  

Microsoft Academic Search

Relative and absolute refractory periods were determined in sensory fibres of 24 median nerves and in 19 sural nerves of 30 volunteers aged 20–60 years, who had no sign of a neuromuscular disorder. The critical interval of conduction (absolute refractory period) was found to be about 0.7 msec. In median as well as in sural nerve the relative refractory periods

W. Tackmann; H. J. Lehmann

1974-01-01

312

Development of novel nanostructured conducting polypyrrole fibres  

Microsoft Academic Search

Polypyrrole (PPy) as a conducting polymer has potential applications in electrical and electronic devices because of its high electrical conductivity, environmental stability and redox activity. There have been many attempts to endow electrically PPy with processibility. Although some success has been achieved via synthesising soluble PPy, there have remained difficulties to fabricate this material through fibre spinning due to its

Javad Foroughi

2009-01-01

313

Chemical Vapour Deposition for Optical Fibre Technology  

Microsoft Academic Search

At the beginning of the seventies, a break-through took place in the telecommunication research. The introduction of Chemical Vapour Deposition technology in the manufacture of optical fibres allowed both technical quality and economical convenience to realise optical networks, thus beginning the telecommunication revolution. Since that moment, a great development of the CVD techniques has been performed, introducing several methods to

L. Cognolato

1995-01-01

314

Multiscale analyses of fibre metal laminates  

Microsoft Academic Search

The advance of composites used in aerospace, civil and biomechanical engineering and other technology branches over the last decades has led to a substantial increase in the application of these materials. In addition, the search for new and improved materials in aerospace industry has stimulated the development of hybrid materials partly made out of composites, such as Fibre-Metal Laminates (FMLs).

M. V. Cid Alfaro

2008-01-01

315

Static Properties of Fibre Metal Laminates  

Microsoft Academic Search

In this article a brief overview of the static properties of Fibre Metal Laminates is given. Starting with the stress-strain relation, an effective calculation tool for uniaxial stress-strain curves is given. The method is valid for all Glare types. The Norris failure model is described in combination with a Metal Volume Fraction approach leading to a useful tool to predict

M. Hagenbeek; C. van Hengel; O. J. Bosker; C. A. J. R. Vermeeren

2003-01-01

316

The zeta potential of mineral fibres.  

PubMed

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

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

2014-07-15

317

Fibre optic grating sensors for biofuels  

NASA Astrophysics Data System (ADS)

Biofuels will have more intense impact on the energetic grid of the planet, because known fossil fuels reserves are being exhausted. The biofuel production relies on the transformation process of some organic material in the desired hydrocarbon product. Because of the natural characteristics of the related processes, fibre optic sensors appear to be adequate candidates to be used.

Muller, M.; Fabris, J. L.; Kalinowski, H. J.

2010-09-01

318

Layers and Layers  

NSDL National Science Digital Library

This lesson has students create their own rock layers by slowly adding and observing how different types of sediment interact when layered upon each other. This lesson is meant to illustrate how we can use these layers to discover the relative age of an object found in that layer by utilizing the Law of Superposition.

Tremarco, Cheri

2011-10-07

319

Optical fibre-based detection of DNA hybridization.  

PubMed

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

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

2009-04-01

320

Sensing properties of germanate and tellurite glass optical fibres  

NASA Astrophysics Data System (ADS)

Strain and thermal sensitivities of germanate and tellurite glass fibres were measured using a fibre Fabry-Perot (FFP) interferometer and fibre Bragg gratings (FBG). The strain phase sensitivity for germanate and tellurite fibre were 5900×103 rad/m and 5600×103 rad/m respectively at a central wavelength of 1540nm using FFP interferometer, which is consistent with the value of 1.22pm/?? obtained for a germanate fibre FBG. The Young's modulus for germanate and tellurite fibre were also measured to be 58GPa and 37GPa. The thermal responses of germanate fibre were examined as 24.71 and 16.80 pm/°C at 1540nm and 1033nm wavelength using the FBG.

Li, Hongxia; Lousteau, Joris; Suo, Rui; Jiang, Xin; MacPherson, William N.; Bookey, Henry T.; Barton, James S.; Kar, Ajoy K.; Zhang, Lin; Jha, Animesh; Bennion, Ian

2009-10-01

321

Sapphire-derived all-glass optical fibres  

NASA Astrophysics Data System (ADS)

As performance demands continue to grow, many optical fibre systems are operating at progressively higher power levels. However, Brillouin scattering restricts continued power scaling in narrow-linewidth systems. Optical fibres with engineered Brillouin properties that are manufactured using industry-accepted methods would be of great practical benefit. Here, we show all-glass optical fibres derived from sapphire that have alumina concentrations of up to ~55 mol%, which is considerably greater than conventionally possible and enables a series of useful properties. Specifically, a Brillouin gain coefficient of 3.1 × 10-13 m W-1, a value nearly 100 times lower than commercial fibre, was measured for a fibre with an average alumina concentration of 54 mol%. Furthermore, a fibre with ~38 mol% alumina was found to be athermal, with a Brillouin frequency that was insensitive to changes in temperature. Such optical fibres may be beneficial in realizing enhanced telecommunication, sensor and high-energy laser systems.

Dragic, P.; Hawkins, T.; Foy, P.; Morris, S.; Ballato, J.

2012-09-01

322

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

324

Respirable fibres: surfactant coated fibres release more Fe3+ than native fibres at both pH 4.5 and 7.2.  

PubMed

Exposure to asbestos is associated with several lung diseases. The carcinogenic action of asbestos is not fully understood but oxidative stress is considered to play a role. Iron on the surface can lead to Fenton chemistry and the Haber Weiss reaction producing free radicals such as the hydroxyl radical, which is likely to be important. Little is known of the pathogenic action of man-made fibres. This study involved the use of a panel of man-made fibres, some of which were shown to be pathogenic and others shown to be non-pathogenic in recent animal studies. A short term assay measuring Fe3+ release from the fibres over a 20 hour time period, and also a longer study of 12 week, found that pathogenic and non-pathogenic fibres could not be differentiated according to Fe3+ release only. Iron release from native fibres was compared with that from surfactant-coated fibres, and in all cases surfactant coated fibres released more Fe3+ inferring that in vivo lung lining fluid coats native fibres and therefore affects the fibre surface chemistry and hence reactivity. PMID:9729922

Fisher, C E; Brown, D M; Shaw, J; Beswick, P H; Donaldson, K

1998-07-01

325

Fibre type-specific gene expression activated by chronic electrical stimulation of adult mouse skeletal muscle fibres in culture  

PubMed Central

Fast-twitch skeletal muscle fibres were enzymatically dissociated from adult mouse flexor digitorum brevis (FDB) muscles and maintained in culture without or with chronic low frequency stimulation (one 5 s train of 5 Hz pulses per minute) for up to 6 days. Single fibre reverse transcriptase-polymerase chain reaction was conducted to coamplify ?-myosin heavy chain (?-MHC) and ?-skeletal actin mRNA from the same fibre.Chronic low frequency electrical stimulation of FDB fibres in culture increased the level of mRNA for ?-MHC. In unstimulated fibres there was a slight decline in the ?-MHC mRNA level. As an internal control there was no increase in the level of mRNA for ?-actin in the identical individual stimulated or unstimulated fibres.Neither the percentage of fibres exhibiting ?-MHC protein nor the Ca2+ transients recorded from individual fibres subjected to the same pattern of stimulation showed any difference between stimulated and unstimulated fibres over the period in culture.This system provides a convenient in vitro model system for studying activity-dependent control of fibre type-specific gene expression in adult skeletal muscle fibres in culture.

Liu, Yewei; Schneider, Martin F

1998-01-01

326

Multifocal VEP and OCT in optic neuritis: a topographical study of the structure–function relationship  

Microsoft Academic Search

Purpose To investigate topographical relationship between amplitude of multifocal visual evoked potentials (mfVEP) and retinal nerve\\u000a fibre layer (RNFL) thickness following acute optic neuritis (ON). Patients and Methods Fifty patients with a clinical diagnosis of acute unilateral ON between 6 and 36 months prior to the study and 25 age-matched\\u000a controls underwent mfVEP testing (Accumap V 2.1, ObjectiVision Pty Ltd, Sydney,

Alexander Klistorner; H. Arvind; T. Nguyen; R. Garrick; M. Paine; S. Graham; J. O’Day; C. Yiannikas

2009-01-01

327

A comparison of the effects of fibre alignment of smooth and textured fibres in electrospun membranes on fibroblast cell adhesion.  

PubMed

A polyester polycaprolactone-based polyurethane elastomer (PU) and poly-(l-lactide) (PLLA), two common biomaterials, were electrospun to produce membranes with fibres either randomly orientated or aligned. PU was used to produce membranes consisting of smooth fibres. PLLA was used to prepare fibres with a textured surface. Contact angle measurements of the PU and PLLA cast films reveal that they were both below 90 degrees and fully wetted in less than 60 s. These membranes were investigated for the effect of fibre topography and fibre alignment on cell adhesion, using mouse L929 fibroblasts. It was found that the alignment of electrospun fibres controls the directional spreading of fibroblast independent of fibre being smooth or textured. PMID:20308775

Truong, Yen B; Glattauer, Veronica; Lang, Gregor; Hands, Karen; Kyratzis, Ilias L; Werkmeister, Jerome A; Ramshaw, John A M

2010-04-01

328

Composites for bone repair: phosphate glass fibre reinforced PLA with varying fibre architecture.  

PubMed

Internal fixation for bone fractures with rigid metallic plates, screws and pins is a proven operative technique. However, refracture's have been observed after rigid internal fixation with metal plates and plate fixation has been known to cause localised osteopenia under and near the plate. In the present study, resorbable composites comprising a PLA matrix reinforced with iron doped phosphate glass fibres were investigated. Non-woven random mat laminates of approximately 30% and 45% fibre volume fraction (V(f)) were produced, along with unidirectional and 0°-90° samples of approximately 20% V(f). The non-woven composite laminates achieved maximum values of 10 GPa modulus and 120 MPa strength. The 0-90º samples showed unexpectedly low strengths close to matrix value (~50 MPa) although with a modulus of 7 GPa. The UD specimens exhibited values of 130 MPa and 11.5 GPa for strength and modulus respectively. All the modulus values observed were close to that expected from the rule of mixtures. Samples immersed in deionised water at 37°C revealed rapid mechanical property loss, more so for the UD and 0-90º samples. It was suggested that continuous fibres wicked the degradation media into the composite plates which sped up the deterioration of the fibre-matrix interface. The effect was less pronounced in the non-woven random mat laminates due to the discontinuous arrangement of fibres within the composite, making it less prone to wicking. Random mat composites revealed a higher mass loss than the UD and 0°-90° specimens, it was suggested this was due to the higher fibre volume fractions of these composites and SEM studies revealed voidage around the fibres by day 3. Studies of pH of the degradation media showed similar profiles for all the composites investigated. An initial decrease in pH was attributed to the release of phosphate ions into solution followed by a gradual return back to neutral. PMID:21671001

Ahmed, I; Jones, I A; Parsons, A J; Bernard, J; Farmer, J; Scotchford, C A; Walker, G S; Rudd, C D

2011-08-01

329

Acoustical model of a Shoddy fibre absorber  

NASA Astrophysics Data System (ADS)

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

Manning, John Peter

330

Optical fibre hydrogen sensors based on palladium coatings  

NASA Astrophysics Data System (ADS)

Optical fibre sensors for Hydrogen detection at low concentrations has become a growing research area using Palladium as an active medium. Palladium is widely used in hydrogen sensing as it show a high and selective affinity for hydrogen. This metal is capable to absorb hydrogen up to 900 times its own volume which permits that during the expansion mechanical forces are applied in the fibre modifying the optical response. Several optical fibre hydrogen sensor heads coated with Palladium are presented and compared using different working principles: interferometric, intensity and fiber grating-based sensors. These principles were applied in Fabry-Perot cavities, fibre Bragg gratings written in fibre SMF28 with etching in the cladding, multimode interferometers and fibre end micro-mirrors. Palladium thin film coatings over the fibre surface and with thicknesses from 10nm to 350nm were produced by using the sputtering RF technique. These studies were performed in a Hydrogen/Nitrogen atmosphere with Hydrogen concentrations from 0% to 4% (lower limit explosion). The Bragg grating inscribed in a fibre with reduced cladding diameter appears to be one of the best approaches for a fibre optic sensing head for Hydrogen detection. Future work will continue the investigation of other fibre optic structures with Hydrogen sensing capabilities and their application in specific field situations will be assessed.

Coelho, L.; Silva, S. F. O.; Tafulo, Paula A. R.; Santos, J. L.; Frazão, O.; Malcata, F. X.

2011-05-01

331

Localized Retinal Nerve Fiber Layer Defects Detected by Optical Coherence Tomography: The Beijing Eye Study  

PubMed Central

Objective To assess the prevalence of localized retinal nerve fiber layer defects (LRNFLD) and associated factors in adult Chinese. Methods The population-based Beijing Eye Study 2011 included 3468 individuals (mean age: 64.6±9.8 years (range: 50–93 years)). The study participants underwent a detailed ophthalmological examination including spectral-domain optical coherence tomography (SpectralisR-OCT) assisted measurement of the RNFL. A LRNFLD was defined as a sector in which the RNFL contour line dipped into the red zone for a length of <180°. Results Readable OCT images were available for 3242 (93.5%) subjects. LRNFLDs were detected in 640 eyes (9.9±0.4%) of 479 subjects (14.8±0.6%). In the age groups of 50–59 years, 60–69 years, 70–79 years, and 80+ years, the prevalence of LRNFLD per person increased from 9.9±0.9%, 11.6±1.0% and 20.6±1.4% to 33.0±3.2%, respectively. In multivariate analysis, prevalence of LRNFLDs was significantly associated with older age (P?=?0.001; Odds Ratio (OR): 1.03; 95% Confidence Interval (CI): 1.01,1.05), myopic refractive error (P<0.001;OR:0.79;95%CI:0.74,0.85), larger beta zone of parapapillary atrophy (P<0.001; OR:1.34;95%CI:1.20,1.50), presence of glaucomatous optic neuropathy (P<0.001;OR:7.02;95%CI:3.87,12.7), presence of non-glaucomatous optic nerve damage (P?=?0.001;OR:43.3;95%CI:8.24,227.1), and presence of diabetic retinopathy (P?=?0.003;OR:2.79;95%CI:1.43,5.44). Conclusions OCT-defined LRNFLDs were present in a prevalence of 14.8±0.6% in a population-based study sample of subjects aged 50+ years. Prevalence of LRNFLDs increased with higher age, myopic refractive error, and larger parapapillary beta zone. Major ocular diseases associated with LRNFLs were glaucoma, non-glaucomatous optic nerve damage and diabetic retinopathy. These data may be helpful for a semiautomatic assessment of the RNFL.

Zhao, Liang; Wang, Ya Xing; Zhang, Wei; Zhang, Jing Shang; Chen, Chang Xi; Xu, Liang; Jonas, Jost B.

2013-01-01

332

Fibre laser component technology for 2-micron laser systems  

NASA Astrophysics Data System (ADS)

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

Stevens, G.; Robertson, A.

2014-05-01

333

Matrix flow and densification during the consolidation of matrix coated fibres  

SciTech Connect

The consolidation of titanium alloy metal matrix composites from matrix coated fibres has been modeled using a continuum finite element approach. Predictions of time to achieve full density are in good agreement with experimental data. The predicted matrix flow has been compared with metallographic sections from samples containing novel yttria marker layers, to allow measurements of actual flow during densification. These results are also in good agreement with the predictions of the model. Densification is shown to be strongly influenced by temperature and pressure consistent with the matrix constitutive law used. However, densification is almost independent of fibre volume fraction in the range 10--50% by volume. Densification is most rapid when a uniform densifying pressure is applied, any increase in deviatoric component for the same mean pressure leads to a decrease in densification rate.

Schueler, S.; Derby, B.; Wood, M.; Ward-Close, C.

2000-04-03

334

Mixing properties of fibre-enriched wheat bread doughs: A response surface methodology study  

Microsoft Academic Search

Fibre-enriched baked goods have increasingly become a convenient carrier for dietary fibre. However, the detrimental effect of fibres on dough rheology and bread quality continuously encourages food technologists to look for new fibres. The effect of several fibres (Fibruline, Fibrex, Exafine and Swelite) from different sources (chicory roots, sugar beet and pea) on dough mixing properties when added singly or

C. M. Rosell; E. Santos; C. Collar

2006-01-01

335

Carbon fibre compressive strength and its dependence on structure and morphology  

Microsoft Academic Search

The axial compressive strength of carbon fibres varies with the fibre tensile modulus and precursor material. While the development of tensile modulus and strength in carbon fibres has been the subject of numerous investigations, increasing attention is now being paid to the fibre and the composite compressive strength. In the present investigation, pitch- and PAN-based carbon fibres with wide-ranging moduli

S. Kumar; D. P. Anderson; A. S. Crasto

1993-01-01

336

Fibre Bragg grating acoustic emissions and transmission sensor in carbon fibre composites  

NASA Astrophysics Data System (ADS)

Acoustic sensors are used in Structural Health Monitoring (SHM) for the detection of impacts and strain. However, secondary damage may result from the initial damage. This secondary damage, such as delamination or cracking, may not be detectable by the SHM system. This is a significant problem for passive sensing systems, such as those based on fibre optics, where signals cannot be actively generated to interrogate the structure. The integration of NDE by robotic agents into a SHM sensor network enables the detection and monitoring of a wider variety of damage. Communicating via acoustic transmissions represents a wireless communication method for robotic agents to communicate to the SHM system without the addition of extra hardware, as piezoelectric transducers are commonly used in NDE. The effect of Carbon Fibre Composites (CFC) on the ability to use acoustic transmission needs to be determined. We present results for the detection of Acoustic Emissions and Transmissions (AET) in a CFC laminate. The optical fibre AET detector was a Fibre Bragg Grating (FBG). Two FBG AET sensors were compared, one coupled to the surface of the carbon fibre sheet, and one embedded within the lay-up. Results compare the transfer function, frequency response, and transient response of the sensors. The embedded FBG receiver was also used to detect an actively generated acoustic transmission. A piezoelectric receiver was also used for comparison. The embedded FBG was found to give significantly better performance in all of the parameters considered for the surface coupled FBG.

Wild, Graham; Hinckley, Steven

2008-12-01

337

Perpendicular fibre tracking for neural fibre bundle analysis using diffusion MRI.  

PubMed

Information on the directionality and structure of axonal fibres in neural tissue can be obtained by analysing diffusion-weighted MRI data sets. Several fibre tracking algorithms have been presented in the literature that trace the underlying field of principal orientations of water diffusion, which correspond to the local primary eigenvectors of the diffusion tensor field. However, the majority of the existing techniques ignore the secondary and tertiary orientations of diffusion, which contain significant information on the local patterns of diffusion. In this paper, we introduce the idea of perpendicular fibre tracking and present a novel dynamic programming method that traces surfaces, which are locally perpendicular to the axonal fibres. This is achieved by using a cost function, with geometric and fibre orientation constraints, that is evaluated dynamically for every voxel in the image domain starting from a given seed point. The proposed method is tested using synthetic and real DW-MRI data sets. The results conclusively demonstrate the accuracy and effectiveness of our method. PMID:24449694

Ray, S; O'Dell, W; Barmpoutis, Angelos

2014-01-01

338

Polymerizing the fibre between bacteria and host cells: the biogenesis of functional amyloid fibres  

PubMed Central

Summary Amyloid fibres are proteinaceous aggregates associated with several human diseases, including Alzheimer’s, Huntington’s and Creutzfeldt Jakob’s. Disease-associated amyloid formation is the result of proteins that misfold and aggregate into ? sheet-rich fibre polymers. Cellular toxicity is readily associated with amyloidogenesis, although the molecular mechanism of toxicity remains unknown. Recently, a new class of ‘functional’ amyloid fibres was discovered that demonstrates that amyloids can be utilized as a productive part of cellular biology. These functional amyloids will provide unique insights into how amyloid formation can be controlled and made less cytotoxic. Bacteria produce some of the best-characterized functional amyloids, including a surface amyloid fibre called curli. Assembled by enteric bacteria, curli fibres mediate attachment to surfaces and host tissues. Some bacterial amyloids, like harpins and microcinE492, have exploited amyloid toxicity in a directed and functional manner. Here, we review and discuss the functional amyloids assembled by bacteria. Special emphasis will be paid to the biology of functional amyloid synthesis and the connections between bacterial physiology and pathology.

Epstein, Elisabeth Ashman; Chapman, Matthew R.

2009-01-01

339

Multiphoton absorption in amyloid protein fibres  

NASA Astrophysics Data System (ADS)

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

Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

2013-12-01

340

Retention of Cationic Starch onto Cellulose Fibres  

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

341

Fibre Optic Sensors for Selected Wastewater Characteristics  

PubMed Central

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

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

2013-01-01

342

Understanding incomplete scrambling in fibres: experimental investigations  

NASA Astrophysics Data System (ADS)

Recent advances in detection and characterization of exo-planets have led to increasing standards for repeatability of spectral-line detection of novel high-resolution spectrographs. This is important for exo-planet research but also has its impact on astroseismology and the study of variable stars. For these purposes optical fibres bear a huge advantage due to their improved scrambling ability - but this is subject to fundamental limits. This investigation gives experimental support for the theoretical proposals made in a companion paper which uses a ray-tracing approach. We will concentrate on the mechanisms that cause incomplete scrambling in order to gain insight in the true nature of scrambling, unlike previous mainly phenomenological studies. We describe the experimental setup that will be used to determine the fibre response to input beam parameters like focal ratio, tilt and offset. Preliminary experimental results are consistent with the theoretical predictions made and thus motivating a further exploration of these phenomena.

Lemke, U.; Allington-Smith, J. R.; Stürmer, J.

2012-09-01

343

Electrically conductive glass fibre reinforced epoxy resin  

Microsoft Academic Search

The research on an industrially manufactured, electrically conductive glass fibre reinforced epoxy prepreg for aviation applications\\u000a is reported. In a co-operative effort between Technical University Hamburg-Harburg (TUHH) and Daimler-Benz Aerospace Airbus\\u000a (DASA) a new glass-epoxy composite with both electrical and good mechanical properties was successfully developed. The electrical\\u000a conductivity was achieved adding carbon black as a conductive filler into the

M. Kupke; Hans-Peter Wentzel; Karl Schulte

1998-01-01

344

Fibre tracking: probabilistic approach and preliminary results  

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

345

Optical fibre Bragg sensor torque transducer  

NASA Astrophysics Data System (ADS)

The benefits of an Optical Torque Transducer (OTT) based on optical fibre Bragg sensors for applications in any environment prone to electro-magnetic and temperature influences are outlined. By using an optical Rotation Coupler (RC) the transducer avoids slip rings or telemetry systems. The OTT enables the measurement of both torque and temperature free from electro-magnetic interference (EMI) in situations conventionally very difficult to make these measurements. OTT torque measurements compare favorably with that of a dynamometer.

van Wyk, A. J.; Snyman, M. C. S.

2007-07-01

346

First-principles studies of peptide fibres  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

347

Photonic sensor of liquids based on suspended-core fibres  

NASA Astrophysics Data System (ADS)

The small size of the core (about 1 ?m) of the suspended-core optical fibres gives rise to evanescent wave in the surrounding channels. That process allows efficient coupling between light and liquid introduced into the channels and application of the fibre for analytic purposes. In the presented work, the channels of a suspended-core fibre were filled with water and aqueous solutions of oxazine 725 perchlorate and their absorption spectra were measured. While the spectra of the water-filled fibre were consistent with the Lambert-Beer law, the absorptivity of the fibre filled with oxazine 725 perchlorate solution demonstrated an increased sensitivity caused by aggregation of the oxazine molecules, independent on the fibre length.

Wajnchold, Barbara; Grabka, Michal; Pustelny, Szymon; Gawlik, Wojciech; Mergo, Pawel

2012-05-01

348

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

NASA Astrophysics Data System (ADS)

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

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

2004-08-01

349

Ultimate low loss of hollow-core photonic crystal fibres  

Microsoft Academic Search

Hollow-core photonic crystal fibres have excited interest as potential ultra-low loss telecommunications fibres because light propagates mainly in air instead of solid glass. We propose that the ultimate limit to the attenuation of such fibres is determined by surface roughness due to frozenin capillary waves. This is confirmed by measurements of the surface roughness in a HC-PCF, the angular distribution

P. J. Roberts; F. Couny; H. Sabert; B. J. Mangan; D. P. Williams; L. Farr; M. W. Mason; A. Tomlinson; T. A. Birks; J. C. Knight; P. St. J. Russell

2005-01-01

350

Thermal dependence of passive electrical properties of lizard muscle fibres.  

PubMed

1. The thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (IF) muscle of Anolis cristatellus (15-35 degrees C) and Sceloporus occidentalis (15-40 degrees C), and for twitch fibres from the white (15-45 degrees C) and red (15-40 degrees C) regions of the IF of Dipsosaurus dorsalis. These species differ in thermal ecology, with Anolis being the least thermophilic and Dipsosaurus the most thermophilic. 2. Iliofibularis fibres from the three species reacted similarly to changing temperature. As temperature was increased, input resistance (Rin) decreased (average R10 = 0.7), length constant (L) decreased (average R10 = 0.9), time constant (tau) decreased (average R10 = 0.8), sarcoplasmic resistivity (Rs) decreased (average R10 = 0.8) and apparent membrane resistance (Rm) decreased (average R10 = 0.7). In contrast, apparent membrane capacitance (Cm) increased with increasing temperature (average R10 = 1.3). 3. Rin, L, tau and apparent Rm were lowest in fibres from Anolis (the least thermophilic species) and highest in fibres from Dipsosaurus (the most thermophilic species). Anolis had the largest and Dipsosaurus the smallest diameter fibres (126 and 57 micron, respectively). Apparent Cm was highest in fibres from Sceloporus, which had fibres of intermediate diameter (101 micron). Rs did not differ significantly among species. 4. The effect of temperature on the passive electrical properties of these lizard fibres was similar to that reported for muscle fibres from other ectothermic animals (crustaceans, insects, fish and amphibians) but qualitatively different from that reported for some mammalian (cat tenuissimus, goat intercostal) fibres. The changes that occur in the passive electrical properties render the fibres less excitable as temperature increases. PMID:3430113

Adams, B A

1987-11-01

351

Gravity spinning of polycaprolactone fibres for applications in tissue engineering  

Microsoft Academic Search

Poly(?-caprolactone) (PCL) fibres have been produced by wet spinning from solutions in acetone under low shear (gravity flow) conditions. The tensile strength and stiffness of as-spun fibres were highly dependent on the concentration of the spinning solution. Use of a 6%w\\/v solution resulted in fibres having strength and stiffness of 1.8MPa and 0.01GPa, respectively, whereas these values increased to 9.9MPa

Matthew R. Williamson; Allan G. A. Coombes

2004-01-01

352

Antibacterial and absorbent acrylonitrile-vinylidene chloride copolymer fibres  

Microsoft Academic Search

A series of antibacterial and absorbent acrylonitrile (AN)-vinylidene chloride (VDC) copolymer fibres were fabricated by adding micro- or nano-sized silver-impregnated activated carbon (Ag-AC) powders in AN-VDC copolymer-dimethylformamide (DMF) solution, and then extruded through a spinneret into a coagulation bath of DMF-water. The fibres containing less than 25 wt% of Ag-AC were spun smoothly. The structure and properties of the fibres

C. Chen; H. Zhang; X. X. Zhang; X. C. Wang

2010-01-01

353

Rheology of Carbon Fibre Reinforced Cement-Based Mortar  

SciTech Connect

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

Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John [School of the Built Environment, Heriot-Watt University, Edinburgh, EH14 4AS (United Kingdom)

2008-07-07

354

Rheology of Carbon Fibre Reinforced Cement-Based Mortar  

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

355

Mechanical and structural characterization of the Nicalon silicon carbide fibre  

Microsoft Academic Search

The Nicalon SiC fibre offers the possibility of the development of composite materials for use above 1000 C. This study has\\u000a compared two types of Nicalon fibre, one which was shown to be amorphous and the other microcrystalline with a SiC grain radius\\u000a of 1.7 nm. Both fibres behaved in a brittle manner when tested in air and in argon

G. Simon; A. R. Bunsell

1984-01-01

356

Carbon fibre composites with ceramic and glass matrices  

Microsoft Academic Search

The fabrication, microstructure and some of the mechanical and thermal properties of a series of composites are described. The systems investigated were magnesia, alumina, soda-lime glass, borosilicate glass and a lithia alumino-silicate glass-ceramic incorporating high modulus, chopped carbon fibres and magnesia containing chopped, stabilized zirconia fibres. Fracture strengths were increased when the fibres were partially aligned, but decreased when the

R. A. J. Sambell; D. H. Bowen; D. C. Phillips

1972-01-01

357

A novel fibre-optic system for methane detection  

Microsoft Academic Search

A novel fibre-optic methane detection system was proposed, which involved sampled fibre grating and improved differential absorption detection technique. By this method, near-infrared equal-spaced multi absorption line of methane was detected simultaneously, and that gas weak absorption detection theory was developed. Using the comb shaped filter characteristic of sampled fibre grating, R2, R3 and R4 line of molecule absorption spectrum

Xijun Wu; Yutian Wang; Leilei Chen; Xinyan Huang

2007-01-01

358

Fibre optic sensors with nano-structured coatings  

Microsoft Academic Search

A review of optical fibre devices employing nano-structured coatings is presented. Active and passive coatings, deposited using the Langmuir–Blodgett and electro-static self-assembly techniques, have been utilised to influence the transmission spectrum of optical fibres, with the aim of developing sensor elements and in-line components for telecommunications systems. Coupled waveguide, fibre grating and miniature Fabry–Perot cavities are described.

Stephen W. James; Ralph P. Tatam

2006-01-01

359

Fibre Optic Temperature Sensors Using Fluorescent Phenomena.  

NASA Astrophysics Data System (ADS)

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

Selli, Raman Kumar

360

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

PubMed

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

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

2014-08-01

361

High power resonantly pumped holmium-doped fibre sources  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

362

Stick-slip during fibre pull-out  

SciTech Connect

It has long been recognized that the mechanics associated with interfacial sliding and debonding is of paramount importance in determining the toughness of fibre-reinforced brittle-matrix composites. As a crack advances through such a composite it will be straddled by fibres. If the fibres are fairly ductible then a number of energy-absorbing mechanisms may be important: debonding and sliding of the interface, and deformation and possible failure of the fibres. In a composite reinforced with brittle fibres only the energy lose when the debonded fibres slide against the matrix can have any significant influence on the toughness. The mechanics of delamination and pull-out can most easily be studied by investigating a model system consisting of a single fibre embedded in a matrix. Although both the initial delamination process and the stick-slip behaviour associated with fibre pull-out have been frequently noted before they have not been investigated in detail. Recent advances in the data collection capabilities of testing machines have now made it possible to explore the details associated with both these processes. This paper present some initial findings of the phenomena that occur during fibre pull-out.

Cook, R.F.; Thouless, M.C.; Clarke, D.R.; Kroll, M.C. (IBM Research Div., Yorktown Heights, NY (USA))

1989-10-01

363

Microstructured fibres: a positive impact on defence technology?  

NASA Astrophysics Data System (ADS)

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

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

2006-10-01

364

Laser micromachining of optical fibre: an instrumentation enabler  

NASA Astrophysics Data System (ADS)

The use of lasers to process optical fibre at INO goes back in the early ’90 when a team developed a CO 2 laser-based process to anneal fibre-end surface allowing the lowest back reflection-loss connectors commercially available at that time. Since then, INO has developed several processes for stripping, cleaving, polishing, end-shaping, machining, bending, welding, soldering and packaging optical fibres. More recently, INO has used laser micromachining of optical fibres in order to enable innovative instrumentation in the field of chemical sensors, flow cytometry and gas chromatography.

Galarneau, Pierre; Levesque, Marc; Beaulieu, René; Caron, Serge; Cournoyer, Alain; Fortin, Michel; Proulx, Antoine

365

Coupling light into optical fibres near the diffraction limit  

NASA Astrophysics Data System (ADS)

The burgeoning field of astrophotonics explores the interface between astronomy and photonics. Important applications include photonic OH suppression at near-infrared wavelengths, and integrated photonic spectroscopy. These new photonic mechanisms are not well matched to conventional multi-mode fibre bundles, and are best fed with single or few-mode fibres. We envisage the largest gains in astrophotonics will come from instruments that operate with single or few mode fibres in the diffraction limited or near diffraction limited regime. While astronomical instruments have largely solved the problem of coupling light into multi-mode fibres, this is largely unexplored territory for few-mode and single-mode fibres. Here we describe a project to explore this topic in detail, and present initial results on coupling light into single and few-mode fibres at the diffraction limit. We find that fibres with as few as ~ 5 guided modes have qualitatively different behaviour to single-mode fibres and share a number of the beneficial characteristics of multi-mode fibres.

Horton, Anthony J.; Bland-Hawthorn, Joss

2006-06-01

366

Effect of gamma irradiation on crude fibre NDF, ADF, and ADL of some Syrian agricultural residues.  

National Technical Information Service (NTIS)

The effects of 150 KGy of gamma irradiation on crude fibre and its main components (cellulose, hemicellulose-cellulose and lignin) and on neutral detergent fibre (NDF), acid detergent lignin (ADL), and acid detergent fibre (ADF) were investigated. The res...

M. R. Al-Masri, M. Zarkawi

1992-01-01

367

Fibre optical sensor for C 2H 2 gas using gas-filled photonic bandgap fibre reference cell  

Microsoft Academic Search

We present results from the first optical fibre correlation spectroscopy gas sensor which uses no lenses other than in the measurement gas cell. The sensor measures acetylene (C2H2) gas concentration. A 1-m length of photonic bandgap fibre (PBGF) was filled with acetylene at atmospheric pressure, then fusion spliced to standard, solid-core, single-mode SMF-28 fibre to form a compact, coilable, reference

Ed Austin; Adriaan van Brakel; Marco N. Petrovich; David J. Richardson

2009-01-01

368

Post-processing of photonic crystal fibres using a CO2 laser beam: a step towards miniature compact fibre devices  

Microsoft Academic Search

Post processing of photonic crystal fibres with a CO2 laser is a very powerful and versatile method for fabricating miniature compact fibre devices including structural long period gratings and rocking filters. A compact Mach-Zehnder interferometer was made from two consecutive structural rocking filters in a highly birefringent photonic crystal fibre. Each rocking filter had 6 complete twist periods of 0.6

G. Kakarantzas; T. A. Birks; P.St.J. Russell

2003-01-01

369

Comparative flexural performance evaluation of steel fibre-reinforced concretes acoording to ASTM C1018 shows importance of fibre parameters  

Microsoft Academic Search

The flexural performance of steel fibre-reinforced beams with varying amounts and types of fibre is evaluated in terms of\\u000a toughness parameters and residual strength factors determined in accordance with ASTM Standard C1018-89. Five types of steel\\u000a fibre in amounts from 30 to 105 kg m?3, and two matrix strength levels, were examined in a program of 117 tests using beams

C. D. Johnston; Å. Skarendahl

1992-01-01

370

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

NASA Astrophysics Data System (ADS)

Spectral-Domain Optical Coherence Tomography (SDOCT) allows for in-vivo video-rate investigation of biomedical tissue depth structure intended for non-invasive optical diagnostics. It has been suggested that OCT can be used for di-agnosis of glaucoma by measuring the thickness of the Retinal Nerve Fiber Layer (RNLF). We present an automated method for determining the RNFL thickness from a 3-D dataset based on edge detection using a deformable spline algo-rithm. The RNFL thickness map is combined with an integrated reflectance map and retinal cross-sectional images to provide the ophthalmologist with a familiar image for interpreting the OCT data. The video-rate capabilities of our SDOCT system allow for mapping the true retinal topography since motion artifacts are significantly reduced as com-pared to slower time-domain systems. Combined with Doppler Velocimetry, SDOCT also provides information on retinal blood flow dynamics. We analyzed the pulsatile nature of the bidirectional flow dynamics in an artery-vein pair for a healthy volunteer at different locations and for different blood vessel diameters. The Doppler phase shift is determined as the phase difference at the same point of adjacent depth profiles, and is integrated over the area delimited by two circles corresponding to the blood vessels location. Its temporal evolution clearly shows the blood flow pulsatile nature, the cardiac cycle, in both artery and vein. The artery is identified as having a stronger variation of the integrated phase shift. We observe that artery pulsation is always easily detectable, while vein pulsation seems to depend on the veins diameter.

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

2006-03-01

371

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

SciTech Connect

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

Yang Xingyu; Yang Guangqiang [Department of Physics, Inner Mongolia University, Huhhot (China)

2001-08-31

372

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

PubMed

A method of securing carbon fibre-reinforced epoxy bone plates with carbon fibre polysulphone expanding rivets was investigated. Six carbon fibre-reinforced epoxy bone plates were secured to rods with carbon fibre polysulphone rivets and six were secured with standard cortical stainless steel screws. These constructions were then subjected to pure torsional load to failure. The carbon fibre expandable rivets failed at a greater torsional moment. PMID:2720038

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

1989-04-01

373

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

NASA Astrophysics Data System (ADS)

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

Jacob Poulin, Anne C.

2002-01-01

374

Short Fibre Polymer Composites: a Fracture-Based Theory of Fibre Reinforcement  

Microsoft Academic Search

The interphase between reinforcing fibers and polymers is brittle, and does not behave in the way it was assumed to when the standard theory for composite strength was developed. Futhermore, this theory predicts curved stress-strain plots for aligned short fibre composites, yet the evidence for this is unconvincing, and there is much new evidence that these stress-strain curves are straight.

Michael R. Piggott

1994-01-01

375

A New Helical Crossed-Fibre Structure of ?-Keratin in Flight Feathers and Its Biomechanical Implications  

PubMed Central

The feather aerofoil is unequalled in nature. It is comprised of a central rachis, serial paired branches or barbs, from which arise further branches, the barbules. Barbs and barbules arise from the significantly thinner lateral walls (the epicortex) of the rachis and barbs respectively, as opposed to the thicker dorsal and ventral walls (the cortex). We hypothesized a microstructural design of the epicortex that would resist the vertical or shearing stresses. The microstructures of the cortex and epicortex of the rachis and barbs were investigated in several bird species by microbe-assisted selective disassembly and conventional methods via scanning electron microscopy. We report, preeminent of the finds, a novel system of crossed fibres (ranging from ?100–800 nm in diameter), oppositely oriented in alternate layers of the epicortex in the rachis and barbs. It represents the first cross-fibre microstructure, not only for the feather but in keratin per se. The cortex of the barbs is comprised of syncitial barbule cells, definitive structural units shown in the rachidial cortex in a related study. The structural connection between the cortex of the rachis and barbs appears uninterrupted. A new model on feather microstructure incorporating the findings here and in the related study is presented. The helical fibre system found in the integument of a diverse range of invertebrates and vertebrates has been implicated in profound functional strategies, perhaps none more so potentially than in the aerofoil microstructure of the feather here, which is central to one of the marvels of nature, bird flight.

Lingham-Soliar, Theagarten; Murugan, Nelisha

2013-01-01

376

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

PubMed

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

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

2007-08-01

377

The design and performance of a scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers  

NASA Astrophysics Data System (ADS)

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons are increasingly being exploited for the non-destructive assay of shielded containers in a wide range of applications. One such application is the characterisation of legacy nuclear waste materials stored within industrial containers. The design, assembly and performance of a prototype muon tomography system developed for this purpose are detailed in this work. This muon tracker comprises four detection modules, each containing orthogonal layers of Saint-Gobain BCF-10 2 mm-pitch plastic scintillating fibres. Identification of the two struck fibres per module allows the reconstruction of a space point, and subsequently, the incoming and Coulomb-scattered muon trajectories. These allow the container content, with respect to the atomic number Z of the scattering material, to be determined through reconstruction of the scattering location and magnitude. On each detection layer, the light emitted by the fibre is detected by a single Hamamatsu H8500 MAPMT with two fibres coupled to each pixel via dedicated pairing schemes developed to ensure the identification of the struck fibre. The PMT signals are read out to standard charge-to-digital converters and interpreted via custom data acquisition and analysis software.

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Staines, C.; Yang, G.; Zimmerman, C.

2014-05-01

378

Swelling of Armos Fibre in Active Liquid Media  

Microsoft Academic Search

The study of swelling of Armos fibres showed that they can act as polyelectrolytes. The degree of swelling in some liquid media is greater than 1000%. The characteristics of swelling of Armos fibre suggest that its structure has units in the form of crystallites and sections between them of amorphous or liquid-crystalline structure.

M. M. Iovleva; V. N. Smirnova; N. N. Machalaba; G. A. Budnitskii

2001-01-01

379

Genesis of the Surface Structure of Armos Fibre  

Microsoft Academic Search

Formation of folds positioned perpendicular to the axis of the fibre onthe surfade of Armos fibre in the first stage of spinning was demonstrated by scanning electron microscopy. In the intermediate stages of spinning, the transverse folds are transformed into longitudinal intersecting grooves. The formation of transverse folds is not a funcito nof the nature and composition fo the precipitant.

S. I. Banduryan; M. M. Iovleva; A. I. Zhuravleva; A. M. Shchetinin; N. N. Machalaba; G. A. Budnitskii

2002-01-01

380

Semiconductor disk laser-pumped subpicosecond holmium fibre laser  

SciTech Connect

The first passively mode-locked holmium fibre laser has been demonstrated, with a semiconductor saturable absorber mirror (SESAM) as a mode locker. Semiconductor disk lasers have been used for the first time to pump holmium fibre lasers. We obtained 830-fs pulses at a repetition rate of 34 MHz with an average output power of 6.6 mW.

Chamorovskiy, A Yu; Marakulin, A V; Leinonen, T; Kurkov, Andrei S; Okhotnikov, Oleg G

2012-01-31

381

Temperature dependence of PMD in optical fibres and cables  

Microsoft Academic Search

Polarization mode dispersion (PMD) is a major limitation to upgrade of existing optical fiber plant with higher capacity equipment. This paper presents results of experiments aimed at establishing dependence of PMD with temperature and aging, primarily for tight-buffered fibres used in indoor cables and certain optical ground wires (OPGW). Fibres in standard 0.9 mm tight buffers and cables with such

Krzysztof Borzycki

2005-01-01

382

Damage Mechanisms in Components for Fibre Lasers and Amplifiers  

Microsoft Academic Search

In this paper we review the damage mechanisms that need to be considered when building high power fibre lasers. More specifically we look at thermal issues, optically induced coating damage, bulk and surface damage thresholds of the host glass. We also discuss the reliability of tapered fibre bundles and Bragg gratings at these power densities.

A. Carter; B. Samson; K. Tankala; D. P. Machewirth; V. Khitrov; U. H. Manyam; F. Gonthier; F. Seguin

383

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

NASA Astrophysics Data System (ADS)

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

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

1999-12-01

384

Ultrastructural observation of single-crystal apatite fibres.  

PubMed

Hydroxyapatite (HAp) has been widely used as a biomaterial for substituting human hard tissues such as bone. By altering the morphology of HAp crystals, novel properties may be produced by controlling the orientation of the crystal planes. Apatite fibres were successfully synthesized by precipitation from aqueous solutions containing Ca(NO(3))(2), (NH(4))(2)HPO(4), urea and HNO(3). The products were composed of carbonate-containing apatite fibres with preferred orientation along the {h00} planes. Examination of individual fibres using transmission electron microscopy showed that the as-synthesized apatite fibres were highly strained single crystals with the c-axis orientation parallel to the long axis of the fibre. The crushed fibres consisted of domains that were preferentially oriented with the c-axis parallel to the long axis of the fibres. When the apatite fibres were heated to 800, 1000 and 1200 degrees C for 1h, the domains were removed and grain boundaries, dislocations and voids were formed. PMID:15621231

Aizawa, Mamoru; Porter, Alexandra E; Best, Serena M; Bonfield, William

2005-06-01

385

Fibre Types and End-uses: A Perceptual Study  

Microsoft Academic Search

This study has used verbal descriptors generated by consumers in the form of semantic differential grids to study perceptions of different types of textile fibres as they are used for different purposes. The fibres studied were silk, cotton, polyester and nylon; the end-uses were sportshirts and underslips. No actual fabrics were used. The study was concerned solely with perceived properties.The

M. S. Byrne; A. P. W. Gardner; Anne M. Fritz

1993-01-01

386

Glass fibre reinforced plastic (GFRP) rebars for concrete structures  

Microsoft Academic Search

The study described is a part of a large-scale experimental and theoretical programme on the application of fibre reinforced plastic (frp) reinforcement for concrete structures initiated at the Université de Sherbrooke (Sherbrooke, Canada). The programme is being carried out to gain an insight into the flexural behaviour of concrete beams reinforced with glass fibre reinforced plastic (gfrp) rebars. Results of

B. Benmokrane; O. Chaallal; R. Masmoudi

1995-01-01

387

High-temperature compatibility of carbon fibres with nickel  

Microsoft Academic Search

A study has been made of the elevated temperature degradation of a number of carbon fibre types coated with nickel by a variety of methods (electroless, electrolytic, carbonyl and physical vapour deposition). At high temperatures, Ni-coated fibres undergo a transformation of structure to crystalline graphite with a consequent loss of strength and elastic modulus. Resistance to this recrystallization is related

R. Warren; C. H. Anderson; M. Carlsson

1978-01-01

388

Muscle fibre types of fishes; structural and functional specialization  

Microsoft Academic Search

Muscles of fishes are active in a variety of movements that differ in velocity, duration and excursion length. To investigate how muscles meet the, often conflicting, demands imposed upon them by these movements, the fibre type composition of several muscles was determined. The ultrastructural and contractile properties of some of the obtained fibre types were measured and compared with their

H. A. Akster

1984-01-01

389

56—THERMODYNAMIC FUNCTIONS OF A REVERSIBLY CONTRACTILE ?-KERATOSE FIBRE  

Microsoft Academic Search

A ?-keratose fibre, prepared by oxidizing a purified horse hair and extracting the ?- and ?- keratoses with ammonia solution, increases in length approximately 50% when taken from an acid buffer solution into an alkaline buffer solution. The length increase is accompanied by a similar increase in diameter, and the dimensional changes are reversible without hysteresis. A ?-keratose fibre mounted

P. T. Speakman

1960-01-01

390

Application of nonlinear oscillator theory to multimode fibres  

Microsoft Academic Search

By returning to the ray path equations and using mathematical methods taken over from the theory of nonlinear oscillators, we derive a new formalism for calculating transit times in power-law fibres with small additional refractive index profile perturbations. The formalism has the following important attributes: the structure is simple, the unperturbed fibre analytic result plus a separate term explicitly related

A. Ankiewicz; C. Pask

1983-01-01

391

Electromechanical effects of caffeine in isolated human atrial fibres.  

PubMed

Effects of caffeine on the action potential and contractile force of human atrial fibres obtained at cardiac surgery were studied with standard microelectrode technique. In 4 mmol . litre-1 [K]o, the only significant action produced by 0.3 to 3 mmol . litre-1 caffeine on the electro-mechanical activity of relatively normal atrial fibres was a slight shortening of the action potential duration at 50% repolarisation. When the fibres were depolarised in 27 mmol . litre-1 [K]o or in atrial fibres showing slow responses in 4 mmol . litre-1 [K]o, however, caffeine could increase the upstroke of slow response and the force. In 18% of atrial fibres showing slow responses in 4 mmol . litre-1 [K]o, caffeine induced spontaneous discharges and potentiated afterdepolarisations. The positive inotropic and the arrhythmogenic effects of caffeine could be diminished by pretreating the fibres with propranolol or Ca antagonists (diltiazem and verapamil). In fibres beating spontaneously in normal [K]o, caffeine accelerated spontaneous rhythms initially and then depressed them. Propranolol potentiated the later depression but did not block the initial acceleration. The results suggest that caffeine increases the transmembrane Ca influx and enhances the release of Ca from the intracellular stores in human atrial fibres. As a consequence, caffeine could induce arrhythmias in atria from certain individuals. PMID:4084929

Lin, C I; Chiu, T H; Chiang, B N; Cheng, K K

1985-12-01

392

FIBRE FRACTIONATION FOR HIGH POROSITY SACK KRAFT PAPER  

Microsoft Academic Search

High performance sack kraft paper must be both strong, with high Tensile Energy Absorption (TEA), and also be porous. Refining increases pulp strength but simultaneously decreases porosity, limiting the available strength increase. Fibre fractionation can increase porosity by removing some of the fines and short fibres, enabling the pulp to be refined to a higher strength. In this study, two

James Olson; Bruce Allison; Tim Friesen; Christine Peters

393

An Historic Overview of the Development of Fibre Metal Laminates  

Microsoft Academic Search

In this paper a brief overview of the history of Fibre Metal Laminates Arall and Glare is given as background information for the other, technical articles in this journal. The story of the development of Fibre Metal Laminates is rather a unique story in the history of aircraft materials: A university laboratory invented, developed and certified an aircraft material. Many

C. A. J. R. Vermeeren

2003-01-01

394

Numerical assessment of failure mechanisms in fibre metal laminates  

Microsoft Academic Search

In this contribution numerical models are discussed for describing failure mechanisms in fibre metal laminates. Fibre metal laminates form a new class of materials which are considered for a possible application to the fuselage of future aircraft generations. The intensive experimental analyses of these materials are focused on the assessment of their residual strength and on the assessment of new

F. Hashagen; R. De Borst

1998-01-01

395

Characterisation of fibre metal laminates under thermomechanical loadings  

Microsoft Academic Search

Fibre metal laminates, such as Arall or Glare, can offer improved properties compared to monolithic materials. Glare for example shows improved fatigue, residual strength, burn-through, impact and corrosion properties with respect to aluminium 2024, together with a considerable weight reduction and competitive costs. A large research program has proven the technological readiness of Glare and the fibre metal laminate has

M. Hagenbeek

2005-01-01

396

Crop physiology of fibre hemp (Cannabis sativa L.)  

Microsoft Academic Search

Fibre hemp ( Cannabis sativa L.) may be an alternative to wood as a raw material for the production of paper pulp. The effects of enviromnental factors and cultural measures on the functioning, yield and quality of fibre hemp crops in the Netherlands were investigated.Until flowering (generally in August), the radiation use efficiency (RUE, above-ground dry matter accumulated per unit

Werf van der H

1994-01-01

397

[Lateral mechanics of muscle fibres and its role in signaling].  

PubMed

Different aspects of the lateral mechanics of muscle fibres have been considered. The current data on the transverse stiffness of intact muscle cells, demenbranized muscle fibres, and isolated myofibrils under various conditions and at different stages of the differentiation of myofibers. The signaling role of cytoskeleton proteins and possible mechanisms of their involvement in the structural basis of transverse stiffness are dissussed. PMID:19569516

Ogneva, I V; Lebedev, D V; Shenkman, B S

2009-01-01

398

Performance of asbestos fibre counting laboratories by transmission electron microscopy  

Microsoft Academic Search

In France, the owners of buildings have been obliged since February 1996 to ascertain whether asbestos has been incorporated into surfacing materials, insulation products or false ceilings. In certain circumstances, there is also a requirement to measure the airborne asbes- tos fibre concentration. Three years (1996-1998) of asbestos fibre count reporting are evalu- ated for the proficiency testing scheme organized

E. Kauffer; M. MARTINE; M. GRZEBYK; J. C. VIGNERON; J. P. SANDINO

2001-01-01

399

Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders  

Microsoft Academic Search

Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based on analytical work, numerical work and experimental work, which together show a complete picture of the tube axial crush

J. L. C. G. De Kanter

2006-01-01

400

Modification of mechanical properties of Kevlar fibre by polymer infiltration  

Microsoft Academic Search

While high-performance organic fibres such as poly (para phenylene benzobisthiazole) and Kevlar possess excellent mechanical properties under axial tension, their strength under compression is generally poor. This study focuses on a polymer infiltration approach to modify the mechanical properties of the Kevlar 49 fibre in tension as well as compression, in which various polymeric resins are infiltrated in an opened

A. Mathur; A. N. Netravali

1996-01-01

401

Effect of dietary fibre on dough rheology and bread quality  

Microsoft Academic Search

Dietary fibre is a common and important ingredient of a new generation of healthy food products demanded more each day by customers. Dietary fibre increases the nutritional value of bread but usually at the same time alters rheological properties of dough and, finally, the quality and sensorial properties of bread. The present work investigates the effect of some purified dietary

Manuel Gómez; Felicidad Ronda; Carlos A. Blanco; Pedro A. Caballero; Arancha Apesteguía

2003-01-01

402

Fibre-optic techniques for broadband access networks  

Microsoft Academic Search

The fast growth in capacity demand in access networks, driven by the increasing thirst for service bandwidths, service variety and number of service providers, asks for ever further penetration of fibre towards the end user residences. A number of key technologies are discussed for broadband service delivery through fibre access nework infrastructures, encompassing multiple access techniques exploiting the time, the

TON KOONEN

2005-01-01

403

The effect of two root canal sealers on the retentive strength of glass fibre endodontic posts.  

PubMed

This study was undertaken to examine the effect of eugenol-containing and non-eugenol-containing root canal sealers on the retention strength of glass fibre endodontic posts (ParaPost Fibre White) luted with a resin cement (ParaPost cement). We also examined the mode of failure that occurred visually by using scanning electron microscopy. Seventy-two single rooted, recently extracted, premolar teeth were root canal treated and randomly divided into two groups. Group 1 was obturated with gutta percha and a calcium hydroxide-based sealer (Sealapex, Kerr). Group 2 was obturated with gutta percha and a eugenol-based sealer (Tubli-Seal Kerr). The teeth were stored for 1 week in distilled water at 37 degrees C and then prepared for 9 mm posts with a 1.40-mm drill. The matching glass fibre post was luted with a resin cement following the manufacturer's instructions. The samples were stored for 1 week and thermocycled. The posts were removed from the root canals using a calibrated testing machine in tensile mode. The mean dislodging force for group 1 was 190.46 N and for group 2 was 183.8 N, with standard deviations of 54.9 and 56.0 N respectively. The t-test indicated no significant difference between the two groups. Failure of the posts occurred mainly within the resin layer. This study showed that under experimental conditions there was no statistically significant difference between Sealapex sealer and Tubli-Seal sealer on the retention of glass fibre posts using a resin cement. PMID:17518983

Davis, S T; O'Connell, B C

2007-06-01

404

Flexible ceramic-reinforced polyurethane composite coatings on synthetic fibres: Process of continuous liquid film coating and its influence on the coating thickness  

Microsoft Academic Search

A concept for the realisation of composite layers on the surface of synthetic fibres by continuous liquid film coating of spread roving or monofilaments with a slurry containing ceramic particles and a polymeric binder is successfully demonstrated. Polyamide 6 monofilaments were coated with alumina particles and a polyurethane elastomer based binder system to achieve higher abrasion resistance. Under frictional load,

Felix A. Reifler; Felipe A. L. Sánchez; Frank J. Clemens; Ksenija Varga; Rudolf Hufenus

2010-01-01

405

Chrysotile and tremolite asbestos fibres in the lungs and parietal pleura of Corsican goats  

PubMed Central

Methods: Ten goats from areas with asbestos outcrops and two from other areas were slaughtered. Fibre content of lung and parietal pleural samples was determined by analytical transmission electron microscopy. Results: Both chrysotile and tremolite fibres were detected. In the exposed goats, the geometric mean concentrations of asbestos fibres longer than 1 µm were 0.27 x 106 fibres/g dry lung tissue and 1.8 x 106 fibres/g dry pleural tissue. Asbestos fibres were not detected in the lungs of the two control goats. Chrysotile fibres shorter than 5 µm were predominant in the parietal pleura. Tremolite fibres accounted for 78% and 86% of the fibres longer than 5 µm in lung and parietal pleural samples, respectively. Conclusions: Environmental exposure in northeast Corsica results in detectable chrysotile and tremolite fibre loads in the lung and parietal pleura of adult goats. Tremolite fibres of dimensions with a high carcinogenic potency are detected in the parietal pleura.

Dumortier, P; Rey, F; Viallat, J; Broucke, I; Boutin, C; De Vuyst, P

2002-01-01

406

Three-dimensional spectral domain optical coherence tomography in X linked foveal retinoschisis.  

PubMed

Spectral domain optical coherence tomography (SD-OCT) was performed in two cases of bilateral X linked foveal retinoschisis of different age groups. On fundus examination spoke wheel and honeycomb pattern of cysts were observed along with retinal nerve fibre layer (RNFL) defects. On SD-OCT, schisis was observed in the outer plexiform layer. External limiting membrane disruption was observed in the subfoveal area, along with disruption of outer nuclear layer (ONL) and inner-outer segment junction. Elevation of ONL due to tractional pull of central palisade was a novel observation. Retinoschisis extended beyond the optic disc up to the nasal region. Extracted RNFL tomogram presented an unprecedented visualisation of schisis along 360° of the optic disc. Tractional elevation in the foveal area and schisis involving nasal region, not observed upon clinical examination, was highlighted on SD-OCT. This investigative modality is an important adjunct in the assessment of foveal retinoschisis. PMID:23563673

Saxena, Sandeep; Manisha; Meyer, Carsten H

2013-01-01

407

The development of a finite element model for simulating the stamp forming of fibre–metal laminates  

Microsoft Academic Search

A finite element model for simulating the stamp forming of fibre–metal laminate material systems will encompass many aspects of both thermoplastic composite forming and metal stamp forming as well as interaction phenomenon between the laminate layers. This paper investigates the composite–metal interaction by studying the crystallisation behaviour of the interlayer adhesive and its shear stress transfer characteristics using lap-shear apparatus.

Luke Mosse; Paul Compston; Wesley J. Cantwell; Michael Cardew-Hall; Shankar Kalyanasundaram

2006-01-01

408

Fourier Analysis of Optical Coherence Tomography and Scanning Laser Polarimetry Retinal Nerve Fiber Layer Measurements in the Diagnosis of Glaucoma  

Microsoft Academic Search

Methods: We obtained RNFL thickness estimates from 1 eye of 38 healthy individuals and 42 patients with early glaucomatous visual field loss using the OCT and GDx devices. The shape of the RNFL double-hump pattern was assessed using Fourier analysis, and values were en- tered into a linear discriminant analysis. Receiver oper- ating characteristic (ROC) curves were used to compare

Edward A. Essock; Michael J. Sinai; Christopher Bowd; Linda M. Zangwill; Robert N. Weinreb

2003-01-01

409

BIOMIMETIC INTEREST AND POSSIBILITIES FOR REPLACEMENT OF GLASS FIBRES WITH PLANT FIBRES IN COMPOSITE MATERIALS: THE CASE OF IMPACT DAMAGE  

Microsoft Academic Search

In this paper, the sense and importance of a biomimetic approach to materials is discussed, highlighting the most characteristic aspects of this philosophy. In particular, attention is brought then on the possibility for improvement of plant fibres for composite materials reinforcement with the aim of looking at them as a substitute for E-glass fibres, presenting benefits in terms of environmental

C. SANTULLI

410

Multicomponent strain development in superconducting magnet coils using optical fibre grating sensors fabricated in highly linearly birefringent fibre  

Microsoft Academic Search

The manufacturing and commissioning of superconducting magnet coils was monitored using embedded optical fibre Bragg grating sensors (FBG) fabricated in highly linearly birefringent (HiBi) fibre. Strain developed in the coils was monitored from the resin impregnation and curing process, through cool down of the magnet in a helium cryostat from room temperature to 4 K, to energising the coils. The

Edmon Chehura; Stephen W. James; Andrew Twin; Fred Domptail; R. P. Tatam

2009-01-01

411

Multicomponent strain development in superconducting magnet coils monitored using fibre Bragg grating sensors fabricated in highly linearly birefringent fibre  

Microsoft Academic Search

The commissioning of superconducting magnet coils was monitored using embedded optical fibre Bragg grating sensors (FBG) fabricated in highly linearly birefringent (HiBi) fibre. The HiBi FBG sensors monitored the internal strain developed in the coils during the energization of the coils. The development of multiple components of strain in the coils when the magnet was energized and quenched was monitored,

Edmon Chehura; Stephen J Buggy; Stephen W James; Adam Johnstone; M’hamed Lakrimi; Fred Domptail; Andrew Twin; Ralph P Tatam

2011-01-01

412

The Effect of Breed Type, Fibre Length, and Fibre Diameter on the Efficiency of Dehairing Cashmere in Sample Test Dehairers  

Microsoft Academic Search

A modified Shirley Analyser has been shown previously to be effective in removing guard hair from down-bearing goat fleeces. The technique used was shown to be capable of dehairing fleeces of both cashmere and Angora x cashmere types. The latter fleece type is characterized by the increased length and fibre diameter of down fibres. This paper reports an investigation of

R. C. Couchman

1989-01-01

413

Finite element analysis of the effect of fibre shape on stresses in an elastic fibre surrounded by a plastic matrix  

Microsoft Academic Search

The finite element (FE) method was used to calculate the axial and radial stress distributions as a function of axial distance, z, from the centre, and radius, r, in an elastic fibre surrounded by a plastic matrix. Plastic deformation of the matrix was considered to exert a uniform interfacial stress, t, along half the length of the fibre. Axisymmetric models

K. L. Goh; K. J. Mathias; R. M. Aspden; D. W. L. Hukins

2000-01-01

414

Biochemical sensor based on a novel all-fibre cavity ring down spectroscopy technique incorporating a tilted fibre Bragg grating  

Microsoft Academic Search

A novel all-fibre cavity ring down spectroscopy technique is proposed where a tilt fibre Bragg grating (TFBG) or long-period grating (LPG) in the cavity provides sensitivity to surrounding medium. Such configuration with an LPG as the representative was theoretically analyzed. Two spectral bands were identified employable for sensing of surrounding refractive index for a weak LPG while only one band

Kaiming Zhou; David Webb; Mark Farries; Neil Hayes; Lin Zhang; Ian Bennion

2009-01-01

415

Damage monitoring in aluminum-foam sandwich structures based on thermoplastic fibre-metal laminates using fibre Bragg gratings  

Microsoft Academic Search

This paper reports the use of fibre Bragg gratings (FBGs) as sensors for structural integrity assessment by monitoring the reduction in the flexural stiffness of a novel sandwich structure based on thermoplastic fibre-metal laminate (FML) skins and an aluminum-foam core. By monitoring the reduction in the structural flexural stiffness, the technique demonstrated its potential for detecting damage initiation in these

K. S. C. Kuang; W. J. Cantwell; L. Zhang; I. Bennion; M. Maalej; S. T. Quek

2005-01-01

416

Fibre reinforced composites in aircraft construction  

NASA Astrophysics Data System (ADS)

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

Soutis, C.

2005-02-01

417

Hydrodynamics of diatom chains and semiflexible fibres.  

PubMed

Diatoms are non-motile, unicellular phytoplankton that have the ability to form colonies in the form of chains. Depending upon the species of diatoms and the linking structures that hold the cells together, these chains can be quite stiff or very flexible. Recently, the bending rigidities of some species of diatom chains have been quantified. In an effort to understand the role of flexibility in nutrient uptake and aggregate formation, we begin by developing a three-dimensional model of the coupled elastic-hydrodynamic system of a diatom chain moving in an incompressible fluid. We find that simple beam theory does a good job of describing diatom chain deformation in a parabolic flow when its ends are tethered, but does not tell the whole story of chain deformations when they are subjected to compressive stresses in shear. While motivated by the fluid dynamics of diatom chains, our computational model of semiflexible fibres illustrates features that apply widely to other systems. The use of an adaptive immersed boundary framework allows us to capture complicated buckling and recovery dynamics of long, semiflexible fibres in shear. PMID:24789565

Nguyen, Hoa; Fauci, Lisa

2014-07-01

418

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

PubMed

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

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

2011-03-01

419

Non Hookean Behaviour in the Fibre Direction of Carbon-Fibre Composites and the Influence of Fibre Waviness on the Tensile Properties  

Microsoft Academic Search

In the literature the tensile behaviour in the fibre direction of unidirec tional carbon fibre reinforced plastic (c.f.r.p.) is assumed to be linearly elastic up to failure.Some authors distinguish a primary and a secondary part in the stress- strain curve each showing Hookean behaviour.The experimental results of this paper show that Young's modulus of laminates increases proportionally with the tensile

Wim H. M. Van Dreumel; John L. M. Kamp

1977-01-01

420

Asbestos fibres and man made mineral fibres: induction and release of tumour necrosis factor-alpha from rat alveolar macrophages.  

PubMed Central

OBJECTIVES--Mounting evidence suggests that asbestos fibres can stimulate alveolar macrophages to generate the potent inflammatory and fibrogenic mediator, tumour necrosis factor-alpha (TNF-alpha), and that this may play an important part in the onset and development of airway inflammation and lung fibrosis due to asbestos fibre inhalation. Little is known, however, about the ability of other mineral fibres to initiate formation and release of TNF-alpha by alveolar macrophages. Therefore the effects of different fibres (crocidolite, chrysotile A, chrysotile B, two man made mineral fibres (MMVF 21 and MMVF 22), a ceramic fibre (RCF 1), and a silicon carbide whisker fibre (SiCwh)) on formation and release of TNF-alpha by rat alveolar macrophages were examined. METHODS--Cells were isolated and incubated at 37 degrees C with the different fibres, or with culture medium alone (controls), and the amounts of TNF-alpha messenger RNA (mRNA) in the cells and TNF-alpha bioactivity released into the culture medium were measured at different time points. RESULTS--Significantly (P < 0.05 v control) increased amounts of TNF-alpha mRNA were found in cells exposed to crocidolite, chrysotile A, chrysotile B, MMVF 21, RCF 1, or SiCwh for 90 minutes, and significantly (P < 0.05 v control) increased activities of TNF-alpha were found in the medium of macrophages exposed to crocidolite, chrysotile A, chrysotile B, or MMVF 21 for four hours. CONCLUSION--These observations suggest that not only natural mineral fibres but also certain man made mineral fibres are able to induce the formation and release of TNF-alpha by alveolar macrophages in vitro. Images Figure 1 Figure 3

Ljungman, A G; Lindahl, M; Tagesson, C

1994-01-01

421

Achievement of broadband uniform modal birefrigence in an index-guiding holey fibre using a novel circular hollow ring defect structure  

NASA Astrophysics Data System (ADS)

A novel silica index-guiding holey fibre (IGHF) design is proposed utilizing a new defect structure that is composed of a three-layered defect with a central air hole germanosilicate ring and silica clad, based on a hollow optical fibre (HOF). Effects of these parameters on birefringence were numerically analysed using the plane wave expansion method. The proposed IGHF showed unique modal properties such as uniform birefringence and differential group delay in 1.55 µm optical communication windows that have not been achieved in prior arts.

Kim, Soan; Jung, Y.; Oh, K.

2006-05-01

422

The porous structure of pulp fibres with different yields and its influence on paper strength  

Microsoft Academic Search

The porous structure of the interior of papermaking fibres is a well-known important property of the fibres. Changes of this structure will influence tensile and burst strength of paper formed from the fibres and a change in pore size of the pores within the fibre wall is also important for the ability of molecules to diffuse in and out of

Bo Andreasson; Jennie Forsström; Lars Wågberg

2003-01-01

423

A study of chemoreceptor and baroreceptor A and C-fibres in the cat carotid nerve  

PubMed Central

1. 149 A-fibres and 52 C-fibres from the cat carotid nerve were studied in vivo with single-unit recording techniques. These units subserved chemoreceptor and baroreceptor modalities. In addition, half of the C-fibres were determined to be efferent in origin. The estimated fibre diameter spectrum for chemoreceptor and baroreceptor A-fibres is described. 2. The discharge pattern of chemoreceptor A and C-fibres was characteristically irregular both at rest and during activation. However, about 5% of the chemoreceptor A-fibre population exhibited a very regular discharge pattern, even at low rates of firing. 3. In comparing A and C-fibres, it was found that chemoreceptor and baroreceptor A-fibres had lower thresholds, shorter response latencies, more rapid acceleration of discharge and higher discharge frequencies than their C-fibre counterparts. 4. During strong chemoreceptor or baroreceptor stimulation, interaction of the `spontaneous' whole nerve activity with the evoked A and C-fibre compound action potentials provided a method of estimating the relative proportions of chemoreceptors and baroreceptors in the A and C-fibre populations of the carotid nerve. The A-fibre population was found to be comprised of approximately 2/3 chemoreceptors, 1/3 baroreceptors. The reverse was true for the C-fibre population, i.e. 2/3 baroreceptors, 1/3 chemoreceptors. 5. A stepwise C-fibre response is described which may arise from the several C-fibres within a single Schwann cell.

Fidone, S. J.; Sato, A.

1969-01-01

424

Optical fibres in biomedical applications: Effect of a biological medium on static fatigue  

Microsoft Academic Search

Summary Optical fibres are finding expanding applications in medicine. This work presents time-to-failure measurements of optical fibres under static stress in a simulated bodily fluid; intended for use in the development of medical fibre optic devices. Keywords-optical fibre, static fatigue, biological media

William G. A. Brown; Christopher D. Easton; Andrea R. Leong; Catherine M. Wade; Paul R. Stoddart; Scott A. Wade

2010-01-01

425

Calcium sensitivity and myofibrillar protein isoforms of rat skinned skeletal muscle fibres  

Microsoft Academic Search

We investigated the calcium sensitivity for tension generation of different fibre types and the possible correlation between calcium sensitivity and the presence of distinct regulatory protein and myosin light chain (MLC) isoforms in rat skinned skeletal muscle fibres. Fibre types 1, 2A and 2B were identified by electrophoretic analysis of myosin heavy chain (MHC) isoforms. Fibres showing more than one

D. Danieli-Betto; R. Betto; M. Midrio

1990-01-01

426

5—THE USE OF BANANA-PLANT FIBRE AS A SUBSTITUTE FOR JUTE  

Microsoft Academic Search

Banana-plant fibre (Musa sapientum) is strong, soft, and coarse, and a technique developed for processing the fibre on standard jute machinery after stapling it to 20 cm is reported. In some trials, the fibre was blended with jute and mesta. A disadvantage was that the yarn was hairy, but hessian and sacking fabrics woven with banana-fibre yarn as weft or

M. K. Sinha

1974-01-01

427

Adhesion strength study between plasma treated polyester fibres and a rubber matrix  

Microsoft Academic Search

In this work, the adhesion strength between poly(ethylene terephthalate) (PET) fibres and styrene-butadiene rubber (SBR) was studied. The effects of atmospheric plasma treatment, used to increase adhesion strength between PET fibres and the rubber matrix, were investigated and compared. It was confirmed that lubricants on the fibres caused a decrease in adhesion strength between the plasma treated reinforcing PET fibres

H. Krump; M. Šimor; I. Hudec; M. Jasso; A. S. Luyt

2005-01-01

428

Preparation techniques of metal clad fibres for corrosion monitoring of steel materials  

Microsoft Academic Search

To fabricate metal clad optical fibres for corrosion sensing, we investigated and compared three techniques of preparing metal cladding on the surface of fibres with cladding removed. The first technique directly deposits iron on the fibre surface by physical vacuum deposition (PVD). The second technique uses nickel on the fibre under the control of a magnetic field in a vacuum

Saying Dong; Gangding Peng; Yanan Luo

2007-01-01

429

Bismuth-doped telecommunication fibres for lasers and amplifiers in the 1400-1500-nm region  

SciTech Connect

Bismuth-doped optical fibres fully compatible with standard telecommunication fibres are developed. Lasers based on such fibres emitting in the spectral range 1430-1500 nm with an efficiency of up to 7.6% at room temperature and up to 10.5% at a temperature of -65{sup 0}C are fabricated. (waveguides. optical fibres)

Dvoirin, V V; Mashinskii, V M; Medvedkov, O I; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Umnikov, A A; Gur'yanov, Aleksei N [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2009-06-30

430

Damage accumulation during cyclic loading of a continuous alumina fibre reinforced aluminium composite  

Microsoft Academic Search

Fibres fracture gradually during the fatigue cycling of continuous alumina fibre reinforced aluminium. The number of fibre breaks increases linearly with the logarithmic cycle number, depends on the maximum stress and the stress ratio, and agrees with published data for the fatigue of bare fibres.

B. Moser; L. Weber; A. Mortensen

2005-01-01

431

Evidence for Direct Physical Bonding between the Collagen Fibres and Apatite Crystals in Bone  

Microsoft Academic Search

THE exact relationship between the mineral crystals and the collagen fibres in bone has not been determined. While the present consensus is that the collagen fibres initiate mineralization1,2, and that the initial crystallites have a specific spatial relationship to the collagen fibres3, evidence of the exact physical relationship between the fibres and crystals is lacking. This question pertains chiefly to

A. A. Marino; R. O. BECKER

1967-01-01

432

Electron beam irradiation in natural fibres reinforced polymers (NFRP)  

NASA Astrophysics Data System (ADS)

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

Kechaou, B.; Salvia, M.; Fakhfakh, Z.; Juvé, D.; Boufi, S.; Kallel, A.; Tréheux, D.

2008-11-01

433

Neonatal myosin in bovine and pig tensor tympani muscle fibres.  

PubMed Central

In previous studies of middle ear muscles, the classification of fibre types by histochemical methods was particularly difficult in the bovine and porcine tensor tympani muscle, suggesting the presence of immature fibres. We therefore reexamined the tensor tympani from pigs and cattle of various ages immunohistochemically, using a panel of antimyosin antibodies, including one (anti-NE) specific for neonatal and embryonic myosins. Fibres positive to anti-NE were found in tensor tympani in both species in all ages examined; only a few of these fibres reacted exclusively with this antibody; some also contained slow myosin and the majority also contained adult fast (type IIA) myosin. Furthermore, although the remaining fibres included some of the classical types I and IIA, the majority of them showed a mismatch between their histochemical and immunohistochemical profiles. The morphological appearance of the muscle, the widespread presence of neonatal myosin (often together with another myosin in the same fibre) and the persistence of this composition from birth to adulthood, could be explained by an incomplete development of the muscle fibres, resulting in a 'muscle' much better suited to the role of a ligament. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5

Scapolo, P A; Rowlerson, A; Mascarello, F; Veggetti, A

1991-01-01

434

Recycling of carbon fibre reinforced polymeric waste for the production of activated carbon fibres  

Microsoft Academic Search

Composite waste composed of carbon fibres and polybenzoxazines resin has been pyrolysed in a fixed bed reactor at temperatures of 350, 400, 450, 500 and 700°C. Solid residues of between 70 and 83.6wt%, liquid yields 14 and 24.6wt% and gas yields 0.7 and 3.8wt% were obtained depending on pyrolysis temperature. The derived pyrolysis liquids contained aniline in high concentration together

Mohamad Anas Nahil; Paul T. Williams

2011-01-01

435

Global chromatin fibre compaction in response to DNA damage  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Robust KAP1 phosphorylation in response to DNA damage in HCT116 cells. Black-Right-Pointing-Pointer DNA repair foci are found in soluble chromatin. Black-Right-Pointing-Pointer Biophysical analysis reveals global chromatin fibre compaction after DNA damage. Black-Right-Pointing-Pointer DNA damage is accompanied by rapid linker histone dephosphorylation. -- Abstract: DNA is protected by packaging it into higher order chromatin fibres, but this can impede nuclear processes like DNA repair. Despite considerable research into the factors required for signalling and repairing DNA damage, it is unclear if there are concomitant changes in global chromatin fibre structure. In human cells DNA double strand break (DSB) formation triggers a signalling cascade resulting in H2AX phosphorylation ({gamma}H2AX), the rapid recruitment of chromatin associated proteins and the subsequent repair of damaged sites. KAP1 is a transcriptional corepressor and in HCT116 cells we found that after DSB formation by chemicals or ionising radiation there was a wave of, predominantly ATM dependent, KAP1 phosphorylation. Both KAP1 and phosphorylated KAP1 were readily extracted from cells indicating they do not have a structural role and {gamma}H2AX was extracted in soluble chromatin indicating that sites of damage are not attached to an underlying structural matrix. After DSB formation we did not find a concomitant change in the sensitivity of chromatin fibres to micrococcal nuclease digestion. Therefore to directly investigate higher order chromatin fibre structures we used a biophysical sedimentation technique based on sucrose gradient centrifugation to compare the conformation of chromatin fibres isolated from cells before and after DNA DSB formation. After damage we found global chromatin fibre compaction, accompanied by rapid linker histone dephosphorylation, consistent with fibres being more regularly folded or fibre deformation being stabilized by linker histones. We suggest that following DSB formation, although there is localised chromatin unfolding to facilitate repair, the bulk genome becomes rapidly compacted protecting cells from further damage.

Hamilton, Charlotte [Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom)] [Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom); Hayward, Richard L. [Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom) [Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom); Breakthrough Research Unit, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom); Gilbert, Nick, E-mail: Nick.Gilbert@ed.ac.uk [Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom) [Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom); Breakthrough Research Unit, The University of Edinburgh, Edinburgh EH4 2XR (United Kingdom)

2011-11-04

436

The Friction of Polyester Staple Fibres: The Effects of Speed, Processing, Spin Finish, Humidity, and Counterface-surface Roughness  

Microsoft Academic Search

Experiments are described in which a capstan method was used to measure the fibre\\/metal and fibre\\/fibre coefficients of friction of single polyester staple fibres. Tests were conducted on fibres carrying the manufacturer's spin finish, before and after partial processing into yarn, and on cleaned fibres. The cleaned fibres were tested against stainless-steel pins of roughness 0.08, 0.11, and 0.28 ?m

Margaret M. Robins; R. W. Rennell; R. D. Arnell

1988-01-01

437

Auger spectroscopy study of MgLi melt affected carbon/pyrocarbon fibres  

NASA Astrophysics Data System (ADS)

Mg-12wt.% Li matrix composite reinforced with T300 carbon fibres coated with pyrolytic carbon (˜100 nm) was manufactured by the infiltration of the carbon fibre bundle with MgLi melt. The fibre/matrix chemistry was studied by means of in situ Auger electron spectroscopy of the fibre jacket and the fibre cross-fracture in ultra-high vacuum broken composite bars. The fibre bulk attack with lithium is concluded wherein C(KVV) lineshape indicates that lithium carbide is the only reaction product, and its distribution in the fibre bulk is quite uniform. Magnesium penetrates also the fibre bulk but its role in the fibre attack is marginal. It is assumed that lithium carbide is formed as a dispersed minor phase in the fibre bulk via decomposition of intermediate lithium intercalation products.

Kúdela, S.; John, A.; Baunack, S.; Kúdela, S.; Wetzig, K.

2001-07-01

438

Super-hydrophobic surfaces of layer-by-layer structured film-coated electrospun nanofibrous membranes  

NASA Astrophysics Data System (ADS)

We have recently fabricated super-hydrophobic membrane surfaces based on the inspiration of self-cleaning silver ragwort leaves. This biomimetic super-hydrophobic surface was composed of fluoroalkylsilane (FAS)-modified layer-by-layer (LBL) structured film-coated electrospun nanofibrous membranes. The rough fibre surface caused by the electrostatic LBL coating of TiO2 nanoparticles and poly(acrylic acid) (PAA) was used to imitate the rough surface of nanosized grooves along the silver ragwort leaf fibre axis. The results showed that the FAS modification was the key process for increasing the surface hydrophobicity of the fibrous membranes. Additionally, the dependence of the hydrophobicity of the membrane surfaces upon the number of LBL coating bilayers was affected by the membrane surface roughness. Moreover, x-ray photoelectron spectroscopy (XPS) results further indicated that the surface of LBL film-coated fibres absorbed more fluoro groups than the fibre surface without the LBL coating. A (TiO2/PAA)10 film-coated cellulose acetate nanofibrous membrane with FAS surface modification showed the highest water contact angle of 162° and lowest water-roll angle of 2°.

Ogawa, Tasuku; Ding, Bin; Sone, Yuji; Shiratori, Seimei

2007-04-01

439

Multimode fibre as a light mode convertor: principles and applications  

NASA Astrophysics Data System (ADS)

Holographic control of randomized light opens up new ways for imaging and manipulation. We present a powerful approach towards understanding of light propagation through multimode optical fibres and control of the signal at the fibre output. We introduce an experimental geometry allowing analysis of the light transmission through the multimode fibre and subsequent beam-shaping. We show how to generate arbitrary output optical fields within the accessible field of view and range of spatial frequencies. We also show that this technology has applications in biophotonics. As an example, we demonstrate the manipulation of colloidal microparticles.

?ižmár, Tomáš; Dholakia, Kishan

2012-10-01

440

All-fibre ytterbium laser tunable within 45 nm  

SciTech Connect

A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Kurkov, A S [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2007-12-31

441

Electrostriction mechanism of Bragg grating formation in germanosilicate fibres  

SciTech Connect

An electrostriction model is proposed for the photorefractive effect observed during the writing of Bragg gratings in germanosilicate fibres. Electrostriction is caused by a spatial charge grating formed upon the exposure to UV radiation. According to our estimate, the contribution of electrostriction to the photorefractive effect under real writing conditions is comparable with the contribution from colour centres and exceeds the contribution from the electrooptical effect by more than an order of magnitude. The electrostriction model explains the production of the IIA type Bragg grating in fibres with a high content of germanium in the core, as well as a number of effects that could not be explained earlier. (optical fibres)