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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

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. PMID:23847322

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

2013-01-01

3

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

4

Retinal nerve fibre layer thickness correlates with brain white matter damage in multiple sclerosis: A combined optical coherence tomography and diffusion tensor imaging study.  

PubMed

We investigated the association of retinal nerve fibre layer thickness (RNFL) with white matter damage assessed by diffusion tensor imaging (DTI). Forty-four MS patients and 30 healthy subjects underwent optical coherence tomography. DTI was analysed with a voxel-based whole brain and region-based analysis of optic radiation, corpus callosum and further white matter. Correlations between RNFL, fractional anisotropy (FA) and other DTI-based parameters were assessed in patients and controls. RNFL correlated with optic radiation FA, but also with corpus callosum and remaining white matter FA. Our findings demonstrate that RNFL changes indicate white matter damage exceeding the visual pathway. PMID:24842962

Scheel, Michael; Finke, Carsten; Oberwahrenbrock, Timm; Freing, Alina; Pech, Luisa-Maria; Schlichting, Jeremias; Sömmer, Carina; Wuerfel, Jens; Paul, Friedemann; Brandt, Alexander U

2014-12-01

5

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

PubMed

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

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

2014-12-01

6

Reproducibility of high-resolution optical coherence tomography measurements of the nerve fibre layer with the new Heidelberg Spectralis optical coherence tomography  

Microsoft Academic Search

AimConventional time-domain OCT technology for detection of retinal nerve fibre layer (RNFL) neurodegeneration suffers from technical inaccuracy owing to a lack of exact scan centring around the optic disc as well as a true follow-up possibility. In this study, the authors evaluated a novel high-resolution spectral-domain OCT device (SD-OCT) with an incorporated eye-tracking feature in its ability to objectively measure

N Serbecic; S C Beutelspacher; F C Aboul-Enein; K Kircher; A Reitner; U Schmidt-Erfurth

2010-01-01

7

Bragg fibres with an intermediate layer  

SciTech Connect

This paper examines the effect of an intermediate layer between the core and periodic cladding of a Bragg fibre on its optical properties. It is shown that any TE{sub 0{kappa}} mode of a standard Bragg fibre can be transformed into the fundamental mode of a Bragg fibre with an intermediate layer by adjusting the thickness of the first cladding layer. Varying the thickness of the intermediate layer, one can tune the mode composition of the transmitted light in a periodic manner. The periodic variation of the optical loss with the thickness of the intermediate layer is due to resonances and antiresonances in this layer. The resonances correspond to two-mode light propagation through the fibre, whereas the antiresonances, to single-mode light propagation.

Kulchin, Yurii N; Zinin, Yu A; Nagornyi, I G

2012-03-31

8

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

9

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

PubMed

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

Wu, Tongfei; Farnood, Ramin

2014-12-19

10

Vision Loss and RNFL Thinning after Internal Carotid Arter Occlusion and Middle Cerebral Artery Infarction  

PubMed Central

Introduction: Ischaemic, traumatic or neoplasmic damage to the optic chiasm, optic tract or lateral geniculate nucleus affects the retinal ganglion cell (RGC) axons, detected as reduced retinal nerve fiber layer (RNFL) thickness around the optic nerve head. We report a case of vision loss and reduced RNFL thickness after internal carotid artery (ICA) occlusion and middle cerebral artery (MCA) infarction. Case report: A 33-year-old woman with a 3-month history of vision loss in right eye and left hemiplegia. The best corrected visual acuity was 1.0 in left eye and there was no light perception in the right eye. Ocular motility, intra-ocular pressure, anterior segments were normal in the both eyes. Her fundus examinations were normal except optic atrophy in the right eye. Visual field test was not performed because of cooperation difficulties. Magnetic resonance imaging (MRI) revealed an infarction of the right MCA. Computed tomographic angiography showed right ICA occlusion. Optical coherence tomography (OCT) demonstrated 6 clock hours of RNFL thinning in the right eye. Average RNFL thickness of the right and left eyes were 53µm, 96 µm respectively. Conclusions: Our findings show that a relatively short period of ICA occlusion and MCA infarction can cause vision loss and thinning of the RNFL.

Gunes, Alime; Demirci, Seden; Umul, Ayse

2014-01-01

11

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. PMID:16849214

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

2005-01-01

12

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

13

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

14

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

15

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

PubMed Central

Introduction: Our aim is to examine the clinical value of spectral-domain optical coherence tomography (Spectralis OCT) to detect retinal nerve fibre layer defects in patients with clinically defined Alzheimer‘s disease (AD). Material and Methods: This cross-sectional study included 22 patients with AD (mean age: 75.9?±?6.1?years) and 22 healthy age- and sex-matched controls. Neuro-ophthalmologic examinations and a series of high-resolution OCT examinations of the peripapillary retinal nerve fiber layer (RNFL) thickness using the Spectralis 3.5-mm circle scan protocol with ART-Modus and eye tracking were obtained, and compared to age- and sex-matched healthy control subjects. Results: Patients with AD showed a significant decrease in RNFL thickness in the nasal superior sector compared to the control group (101.0?±?18.18??m versus 122.8?±?28.08??m; P?RNFL thickness compared to controls was detected. Using the advanced age- and gender-matched measurement model, 32 out of 42 eyes (76.19%) as pathologic with 67 abnormal sectors were detected. Discussion: As examined by spectral-domain OCT, patients with mild to moderate stages of AD showed a significant reduction of RNFL thickness in the nasal superior sector. Nevertheless, successive studies are needed. PMID:24616709

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

2014-01-01

16

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

Microsoft Academic Search

A systematic toxicological analysis procedure using high-performance thin layer chromatography in combination with fibre optical scanning densitometry for identification of drugs in biological samples is presented. Two examples illustrate the practicability of the technique. First, the identification of a multiple intake of analgesics: codeine, propyphenazone, tramadol, flupirtine and lidocaine, and second, the detection of the sedative diphenhydramine. In both cases,

Björn Ahrens; Dirk Blankenhorn; Bernd Spangenberg

2002-01-01

17

Modelling the normal retinal nerve fibre layer thickness as measured by Stratus optical coherence tomography  

Microsoft Academic Search

Background  The variation in retinal nerve fibre layer thickness (RNFLT) as measured by Stratus optical coherence tomography (OCT) in healthy subjects may be reduced when the effect on RNFLT measurements of factors other than disease is corrected for, and this may improve the diagnostic accuracy in glaucoma. With this perspective we evaluated the isolated and combined effects of factors potentially affecting

Jesper Leth Hougaard; Carl Ostenfeld; Anders Heijl; Boel Bengtsson

2006-01-01

18

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. PMID:22171063

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

2012-01-01

19

Peripapillary Retinal Nerve Fiber Layer Thickening Associated with Vitreopapillary Traction.  

PubMed

Abstract Purpose: To report two cases of retinal nerve fiber layer (RNFL) thickening as measured by Cirrus high-definition spectral-domain optical coherence tomography (OCT) associated with vitreopapillary traction. Methods: Consecutive peripapillary RNFL thickness assessments were performed using OCT in eyes with glaucoma and ocular hypertension. Results: OCT measurements revealed RNFL thickening when compared with the prior examination. A vitreopapillary traction to the thickened side of the RNFL was noted in a cross-sectional image of the optic nerve head obtained by OCT. Conclusion: Given that RNFL thickening can mask glaucomatous changes of the RNFL, caution is needed in glaucoma evaluation in eyes with vitreopapillary traction to the RNFL. PMID:24171792

Hwang, Young Hoon; Kim, Yong Yeon

2013-10-30

20

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

21

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

22

Korean normative database for time domain optical coherence tomography to detect localized retinal nerve fiber layer defects (preliminary study)  

Microsoft Academic Search

Purpose  To establish a Korean normative database of retinal nerve fiber layer (RNFL) thickness.\\u000a \\u000a \\u000a \\u000a Methods  Data was collected from 103 healthy volunteers. Total ophthalmologic examinations, including fast RNFL thickness analysis\\u000a by time domain optical coherence tomography (STRATUS OCT) were performed. The RNFL thickness of 64 glaucoma patients with\\u000a localized RNFL defects and 48 independent healthy subjects were collected. The RNFL thickness of

Shin Hee Kang; Ki Ho Park; Joon Mo Kim; Jong Mo Seo; Dong Myung Kim

2010-01-01

23

Detection in situ and characterization of lignin in the G -layer of tension wood fibres of Populus deltoides  

Microsoft Academic Search

The occurrence of lignin in the additional gelatinous ( G-) layer that differentiates in the secondary wall of hardwoods during tension wood formation has long been debated. In the present work, the ultrastructural distribution of lignin in the cell walls of normal and tension wood fibres from poplar ( Populus deltoides Bartr. ex Marshall) was investigated by transmission electron microscopy

Jean-Paul Joseleau; Takanori Imai; Katsushi Kuroda; Katia Ruel

2004-01-01

24

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

SciTech Connect

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

Giancardo, Luca [ORNL] [ORNL; Meriaudeau, Fabrice [ORNL] [ORNL; Karnowski, Thomas Paul [ORNL] [ORNL; Li, Yaquin [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Tobin Jr, Kenneth William [ORNL] [ORNL; Chaum, Edward [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK)

2011-01-01

25

Comparison of constitutive models of arterial layers with distributed collagen fibre orientations.  

PubMed

Several constitutive models have been proposed for description of mechanical behaviour of soft tissues containing collagen fibres. The model with aligned fibres is modified in this paper to take the dispersion of fibre orientations into account through angular integration and it is compared with the model that is defined through generalized structure tensor. The paper is focused on the effect of fibre dispersion on the resulting stress-strain behaviour predicted by both models analyzed. Analytical calculations are used for the comparison of the mechanical behaviour under a specific biaxial tension mode. The two models have been implemented into commercial finite element code ANSYS via user subroutines and used for numerical simulation resulting in a non-homogeneous stress field. The effects of the fibre dispersion predicted by both models being compared differ significantly, e.g., the resulting stress difference between both models is lower than 10% only in the case of extremely small dispersion of collagen fibres orientation (?< (0.01 to 0.03)). These results are consistent with those of other related literature. The applicability of the model defined through the generalized structure tensor is discussed. PMID:25308192

Skacel, Pavel; Bursa, Jiri

2014-01-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

27

Bruno Clair . Bernard Thibaut . Junji Sugiyama On the detachment of gelatinous layer in tension wood fibre  

E-print Network

Bruno Clair . Bernard Thibaut . Junji Sugiyama On the detachment of gelatinous layer in tension published in volume 51(2) 2005 1 Abstract The detachment of gelatinous layer (G-layer), often observed properties. Key-words Wood cell wall, cutting effect, gelatinous layer (G-layer), growth stress, tension wood

Paris-Sud XI, UniversitƩ de

28

Relationship Between Optic Nerve Appearance and Retinal Nerve Fiber Layer Thickness as Explored with Spectral Domain Optical Coherence Tomography  

PubMed Central

Purpose To study the relationship between the appearance of the optic nerve and the retinal nerve fiber layer (RNFL) thickness determined by spectral domain optical coherence tomography (OCT). Methods Records from patients with spectral domain-OCT imaging in a neuro-ophthalmology practice were reviewed. Eyes with glaucoma/glaucoma suspicion, macular/optic nerve edema, pseudophakia, and with refractive errors > 6D were excluded. Optic nerve appearance by slit lamp biomicroscopy was related to the RNFL thickness by spectral domain-OCT and to visual field results. Results Ninety-one patients (176 eyes; mean age: 49 ± 15 years) were included. Eighty-three eyes (47%) showed optic nerve pallor; 89 eyes (50.6%) showed RNFL thinning (sectoral or average peripapillary). Average peripapillary RNFL thickness in eyes with pallor (mean ± SD = 76 ± 17 ?m) was thinner compared to eyes without pallor (91 ± 14 ?m, P < 0.001). Optic nerve pallor predicted RNFL thinning with a sensitivity of 69% and a specificity of 75%. Optic nerve appearance predicted RNFL thinning (with a sensitivity and specificity of 81%) when RNFL had thinned by ? 40%. Most patients with pallor had RNFL thinning with (66%) or without (25%) visual field loss; the remainder had normal RNFL and fields (5%) or with visual field abnormalities (4%). Conclusions Optic nerve pallor as a predictor of RNFL thinning showed fair sensitivity and specificity, although it is optimally sensitive/specific only when substantial RNFL loss has occurred. Translational Relevance Finding an acceptable relationship between the optic nerve appearance by ophthalmoscopy and spectral domain-OCT RNFL measures will help the clinician's interpretation of the information provided by this technology, which is gaining momentum in neuro-ophthalmic research. PMID:25374773

Aleman, Tomas S.; Huang, Jiayan; Garrity, Sean T.; Carter, Stuart B.; Aleman, Wendy D.; Ying, Gui-shuang; Tamhankar, Madhura A.

2014-01-01

29

The Retinal Nerve Fiber Layer Thickness in Ocular Hypertensive, Normal, and Glaucomatous Eyes With Optical Coherence Tomography  

Microsoft Academic Search

Objective: To quantitatively assess and compare the thickness of the retinal nerve fiber layer (RNFL) in ocu- lar hypertensive eyes with normal and glaucomatous eyes using the Optical Coherence Tomograph (OCT 2000, soft- ware version A4X1; Humphrey Instruments, San Lean- dro, Calif). Methods: The mean RNFL thickness of ocular hyper- tensive (n = 28) eyes was compared with age-matched normal

Christopher Bowd; Robert N. Weinreb; Julia M. Williams; Linda M. Zangwill

30

Multimaterial piezoelectric fibres  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

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. PMID:24817744

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

2014-01-01

32

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

PubMed

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. PMID:24212231

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

2013-11-11

33

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

34

The evaluation of retinal nerve fiber layer thickness in patients with obstructive sleep apnea syndrome.  

PubMed

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

Adam, Mehmet; Okka, Mehmet; Yosunkaya, Sebnem; Bozkurt, Banu; Kerimo?lu, Hürkan; Turan, Meydan

2013-01-01

35

Retinal Nerve Fiber Layer Thickness in Women with Polycystic Ovary Syndrome  

PubMed Central

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

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

2013-01-01

36

Factors Affecting the Ability of the Spectral Domain Optical Coherence Tomograph to Detect Photographic Retinal Nerve Fiber Layer Defects  

PubMed Central

Purpose To evaluate the ability of normative database classification (color-coded maps) of spectral domain optical coherence tomograph (SDOCT) in detecting wedge shaped retinal nerve fiber layer (RNFL) defects identified on photographs and the factors affecting the ability of SDOCT in detecting these RNFL defects. Methods In a cross-sectional study, 238 eyes (476 RNFL quadrants) of 172 normal subjects and 85 eyes (103 RNFL quadrants with wedge shaped RNFL defects) of 66 glaucoma patients underwent RNFL imaging with SDOCT. Logistic regression models were used to evaluate the factors associated with false positive and false negative RNFL classifications of the color-coded maps of SDOCT. Results False positive classification at a p value of <5% was seen in 108 of 476 quadrants (22.8%). False negative classification at a p value of <5% was seen in 16 of 103 quadrants (15.5%). Of the 103 quadrants with RNFL defects, 64 showed a corresponding VF defect in the opposite hemisphere and 39 were preperimetric. Higher signal strength index (SSI) of the scan was less likely to have a false positive classification (odds ratio: 0.97, p?=?0.01). Presence of an associated visual field defect (odds ratio: 0.17, p?=?0.01) and inferior quadrant RNFL defects as compared to superior (odds ratio: 0.24, p?=?0.04) were less likely to show false negative classifications. Conclusions Scans with lower signal strengths were more likely to show false positive RNFL classifications, and preperimetric and superior quadrant RNFL defects were more likely to show false negative classifications on color-coded maps of SDOCT. PMID:25536188

Rao, Harsha L.; Addepalli, Uday K.; Yadav, Ravi K.; Choudhari, Nikhil S.; Senthil, Sirisha; Garudadri, Chandra S.

2014-01-01

37

Depth and Area of Retinal Nerve Fiber Layer Damage and Visual Field Correlation Analysis  

PubMed Central

Purpose To evaluate the relationship between the structural damage as assessed by time-domain optical coherence tomography (OCT) and functional changes in glaucoma. Methods In total, 190 patients with normal tension glaucoma or primary open angle glaucoma were included in this study. The thickness of retinal nerve fiber layer (RNFL) around the optic disc and the area of RNFL defect were determined using OCT scans. The relationships between the RNFL thickness or area of the defect and visual field (VF) indices were assessed using the Lowess function, regression analysis and partial Spearman correlation. The differences between these associations depending on the stage of VF damage were further analyzed. Age, optic disc size, refraction, central corneal thickness and the presence of systemic disease were corrected for in order to exclude confounding factors. Results A logarithmic scale of RNFL thickness showed a negative linear relationship with VF indices. The area of the RNFL defect showed a weak correlation with the pattern of standard deviation, whereas the remnant RNFL thickness was moderately correlated with the pattern of standard deviation (partial Spearman correlation coefficient, 0.39, -0.47, respectively; p < 0.0001). Many outliers were detected in the Lowess-plotted graphs. Multiplication of the area and the inverted RNFL thickness showed a moderately correlated logarithmic relationship with the VF indices (partial Spearman correlation coefficient, 0.46; 95% confidence interval, 0.34 to 0.57; p < 0.0001). In the severe stage of VF damage, correlation between the area of the RNFL defect and mean deviation was significantly greater than in other stages (partial Spearman correlation coefficient, -0.66; p = 0.02). Conclusions The thickness of the RNFL had a negative logarithmic correlation with the VF indices and was more relevant to the VF indices than the area of the RNFL defect, as measured by OCT. PMID:25120341

Suh, Wool; Lee, Jung Min

2014-01-01

38

Transient increase of retinal nerve fiber layer thickness after macular hole surgery.  

PubMed

We studied the changes in the thickness of the retinal nerve fiber layer (RNFL) after surgery for idiopathic macular hole (MH) using spectral-domain optical coherence tomography (SD-OCT). Twenty eyes of 20 consecutive patients who underwent vitrectomy to close a MH were studied. The peripapillary RNFL thickness was measured by SD-OCT before and at 1, 3, and 6 months after surgery. The mean overall thickness, the thickness of the four quadrants, and the thickness of each of the 12 clock hours of the RNFL were analyzed. The mean overall RNFL thickness before surgery was 93.3 ± 9.6 lm,and it increased significantly to 98.7 ± 7.4 lm at 1 month after surgery (P\\0.05). The mean overall thickness then returned to the pre-surgery level at three and 6 months. The transient increase of RNFL thickness at 1 month after surgery was statistically significant in the superior, nasal, and inferior quadrants. The increase in the thickness of the nasal quadrants was maintained for up to 6 months. When the thickness of the individual 12 clock hours were analyzed, the transient increase of RNFL thickness at 1 month after surgery was significant at each of the 0–5 o’clock positions. The transient increase in the RNFL thickness after MH surgery may be caused by mild edema of the inner retinal layers caused by the MH surgery. PMID:24077720

Hibi, Nobuaki; Kondo, Mineo; Ishikawa, Kohei; Ueno, Shinji; Komeima, Keiichi; Terasaki, Hiroko

2014-06-01

39

Optical properties of Bragg fibres  

SciTech Connect

The electrodynamic problem of propagation of light in a fibre with a cladding made of coaxial dielectric layers with alternating values of the refractive index is solved. The fibre core is a dielectric, in particular, air with the lowest permittivity in the fibre structure. A method is described for determining the structure of the multilayer cladding of a fibre having the minimal optical loss of the guided radiation for a particular mode. Losses in a fibre with a cladding with quasi-periodic layer thicknesses are calculated and the dispersion properties of the fibre are analysed. The analysis is performed for the lowest TE and TM modes and for the lowest hybrid mode. (invited paper)

Biryukov, A S; Bogdanovich, D V; Gaponov, D A; Pryamikov, A D [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2008-07-31

40

Retinal nerve fiber layer thickness in vitiligo patients  

PubMed Central

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

Örnek, Nurgül; Onaran, Zafer; Koēak, Mukadder; Örnek, Kemal

2013-01-01

41

Dietary fibre.  

PubMed

Currently and after 30 years of research, dietary fibre is part of what is considered a healthy diet. There is no single definition yet comprising the different components of dietary fibre and its functions. The main factors of fibre are complex carbohydrates and lignin, although new products may be included in the future within the concept of fibre. Dietary fibres reach the large bowel and are attacked by colonic microflora, yielding short chain fatty acids, hydrogen, carbon dioxide, and methane as fermentation products. Short chain fatty acids represent a way of recovering energy and they are also implicated in other beneficial functions for the human organism. Although there are no yet conclusive data on recommendations of different types of fibre, it is still appropriate to indicate a diet providing 20-35 g/day of fibre from different sources. There is a consensus to recommend a mixture of fibres or fibre like soybean polysaccharide for constipation. There are few conclusive data, still, on the benefit of fibre on prevention of colorectal cancer and cardiovascular disease. However, a fibre-rich diet is recommended from early years of life since it is often associated to a lifestyle that in the long term helps controlling other risk factors. PMID:16771074

Escudero Alvarez, E; Gonzįlez Sįnchez, P

2006-05-01

42

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  

Microsoft Academic Search

PurposeTo 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).

Antonio Lleó-Pérez; Amparo Ortuńo-Soto; M. S. Rahhal; Juan A. Sanchis-Gimeno

2009-01-01

43

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

PubMed

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

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

2014-08-01

44

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

PubMed Central

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

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

2014-01-01

45

15-March 2007 1 A Scintillating Fibre TrackerA Scintillating Fibre Tracker  

E-print Network

SFT 1SFT 1 SFT 2SFT 2 Weilin Yu, DPG FrĆ¼hjahrstagung,GieĆ?en #12;15-March 2007 11 Scintillating Fibre Tracker(SFT) Built by JLU Giessen 2 cylinders of 2 X 2 layers, 100 stereo angle 1 mm Kuraray fibres Scintillating Fibre Tracker(SFT) Momentum measured in full azimuthal angle and reconstructed by bending 1 Tesla

46

Comparative Diagnostic Accuracy of Ganglion Cell-Inner Plexiform and Retinal Nerve Fiber Layer Thickness Measures by Cirrus and Spectralis Optical Coherence Tomography in Relapsing-Remitting Multiple Sclerosis  

PubMed Central

Objective. To estimate sensitivity and specificity of several optical coherence tomography (OCT) measurements for detecting retinal thickness changes in patients with relapsing-remitting multiple sclerosis (RRMS), such as macular ganglion cell-inner plexiform layer (GCIPL) thickness measured with Cirrus (OCT) and peripapillary retinal nerve fiber layer (pRNFL) thickness measured with Cirrus and Spectralis OCT. Methods. Seventy patients (140 eyes) with RRMS and seventy matched healthy subjects underwent pRNFL and GCIPL thickness analysis using Cirrus OCT and pRNFL using Spectralis OCT. A prospective, cross-sectional evaluation of sensitivities and specificities was performed using latent class analysis due to the absence of a gold standard. Results. GCIPL measures had higher sensitivity and specificity than temporal pRNFL measures obtained with both OCT devices. Average GCIPL thickness was significantly more sensitive than temporal pRNFL by Cirrus (96.34% versus 58.41%) and minimum GCIPL thickness was significantly more sensitive than temporal pRNFL by Spectralis (96.41% versus 69.69%). Generalised estimating equation analysis revealed that age (P = 0.030), optic neuritis antecedent (P = 0.001), and disease duration (P = 0.002) were significantly associated with abnormal results in average GCIPL thickness. Conclusion. Average and minimum GCIPL measurements had significantly better sensitivity to detect retinal thickness changes in RRMS than temporal pRNFL thickness measured by Cirrus and Spectralis OCT, respectively. PMID:25313352

Gonzįlez-López, Julio J.; Rebolleda, Gema; Leal, Marina; Oblanca, Noelia; Muńoz-Negrete, Francisco J.; Costa-Frossard, Lucienne; Įlvarez-Cermeńo, José C.

2014-01-01

47

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

PubMed Central

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

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

2014-01-01

48

Analysis of peripapilary retinal nerve fiber layer thickness of healthy Chinese from northwestern Shanghai using Cirrus HD-OCT  

PubMed Central

AIM To investigate peripapillary retinal nerve fiber layer (RNFL) thickness of healthy Chinese individuals from northwestern Shanghai using Cirrus HD-OCT (Carl Zeiss Meditec, Inc. Dublin, CA, USA). METHODS The peripapillary RNFL thickness of 720 eyes from 360 healthy Chinese participants were measured using the Optic Disc Cube 200×200 protocol. Each eye was scanned 3 times. Global and each quadrant's RNFL thickness around the optic nerve were compared between genders, and interocular differences were analyzed. The correlation between global RNFL thickness and age were also assessed in this study. RESULTS The mean global, superior, nasal, inferior and temporal RNFL thickness of all the eyes were 96.04±7.40 µm, 118.36±13.52 µm, 67.63±8.60 µm, 125.17±13.48 µm, 72.49±10.70 µm, respectively. When analyzing between genders, the mean nasal RNFL thickness of male and female were 68.29±8.44 µm and 66.97±8.70 µm, with statistically significant difference (P=0.038), while the data of global, superior, inferior and temporal quadrant showed no significant difference (all P>0.05). When analyzing interocular differences, the mean RNFL thickness of all the right eyes and all the left eyes were 116.46±13.17 µm and 120.27±13.61 µm in superior quadrant (P<0.001); 68.74±8.80 µm and 66.52±8.25 µm in nasal quadrant (P<0.001); 73.16±10.95 and 71.83±10.41 in temporal quadrant (P<0.001), all having statistically significant differences. There were no statistically significant interocular differences of global and inferior RNFL thickness (both P>0.05). There was a significantly negative correlation (r=-0.618, P<0.001) between the mean global RNFL thickness and the age. CONCLUSION In healthy Chinese from northwestern Shanghai, there were no significant differences detected interocular difference and between genders in the mean global RNFL thickness. Nevertheless, significant difference existed in the nasal quadrant between genders, and interocular differences existed in the superior, nasal and temporal quadrants. The RNFL thickness appeared to gradually decrease with age. PMID:25161937

Qu, Shen; Sun, Xiao-Ting; Xu, Wei; Rong, Ao

2014-01-01

49

Evaluation of retinal nerve fiber layer thickness in migraine  

PubMed Central

Background Headache is one of the most disturbing symptoms with common neurological signs. Variations in optic nerve perfusion quality or retinal microcirculation may end up in ganglion cell damage in patients with migraine. Methods Sixty patients diagnosed with migraine and thirty normal individuals were evaluated in groups including migraine with aura, migraine without aura and controls. Retinal nerve fiber layer (RNFL) thickness was measured using stratus optical coherence tomography (OCT™) and then was compared in case and control groups. Results RNFL thickness was only significantly thinner in nasal quadrant in migraineurs compared to the control group. Other parameters showed no difference between the two groups and besides there was no statistically difference between the two migraine subgroups. Conclusion Given the significant difference in nasal quadrant RNFL thickness between the migraineurs and normal individuals, we might be able to defend the retinal blood flow decrease theory in migraine; however, multicentre studies with larger samples seem mandatory. PMID:24250902

Sorkhabi, Rana; Mostafaei, Somaiyeh; Ahoor, Mohammadhosein

2013-01-01

50

Blue-on-yellow visual field and retinal nerve fiber layer in ocular hypertension and glaucoma 1 1 The authors have no proprietary interest in any of the materials used in this study  

Microsoft Academic Search

Background and objectiveIt has been suggested that the clinically detectable changes of the blue-on-yellow (B\\/Y) visual field and retinal nerve fiber layer (RNFL) may precede standard white-on-white (W\\/W) visual field defects in the progression of glaucoma. The aim of this study was to test the relationship between the results of B\\/Y visual fields and semiquantitative RNFL evaluation in corresponding areas

Pait Teesalu; P. Juhani Airaksinen; Anja Tuulonen

1998-01-01

51

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. PMID:24967097

Toba, Yoshiharu; Machida, Shigeki; Kurosaka, Daijiro

2014-01-01

52

Comparisons of retinal nerve fiber layer thickness after indocyanine green, brilliant blue g, or triamcinolone acetonide-assisted macular hole surgery.  

PubMed

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. PMID:24967097

Toba, Yoshiharu; Machida, Shigeki; Kurosaka, Daijiro

2014-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

54

Multimaterial Piezoelectric Fibres  

E-print Network

Fibre materials span a broad range of applications ranging from simple textile yarns to complex modern fibre-optic communication systems. Throughout their history, a key premise has remained essentially unchanged: fibres ...

Egusa, S.

55

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

PubMed Central

Abstract. 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. PMID:24390374

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

2014-01-01

56

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. PMID:24799793

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

2014-01-01

57

Peripapillary retinal nerve fiber layer thickness in normal Japanese eyes measured with optical coherence tomography  

Microsoft Academic Search

Purpose  To measure peripapillary retinal nerve fiber layer (RNFL) thickness in healthy Japanese individuals using optical coherence\\u000a tomography (OCT).\\u000a \\u000a \\u000a \\u000a Methods  OCT was used to measure the eyes of 460 healthy Japanese volunteers aged 20 to 84. One eye of each individual was selected\\u000a for the statistical analysis.\\u000a \\u000a \\u000a \\u000a Results|The average circumpapillary (cp) RNFL thickness of all eyes was 111.8 ± 10.0 ?m. A

Makoto Kanno; Michi Nagasawa; Michiro Suzuki; Hidetoshi Yamashita

2010-01-01

58

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. PMID:24882955

Park, Yi-Ryeung

2014-01-01

59

Reduced Cortical Thickness in Primary Open-Angle Glaucoma and Its Relationship to the Retinal Nerve Fiber Layer Thickness  

PubMed Central

Objectives To examine possible changes in cortical thickness and their relationship to retinal nerve fiber layer (RNFL) thickness in patients with primary open-angle glaucoma (POAG). Materials and Methods Thirty-six patients with POAG and 40 matched healthy controls were enrolled in this study. All subjects underwent a comprehensive ophthalmologic examination and a high resolution structural magnetic resonance scan. Cortical thickness analysis was used to assess the changes between patients and controls. Correlations between the thickness of the visual cortex and RNFL thickness were also analyzed. Finally, the relationship between the severity of changes in the visual cortex and RNFL thickness was evaluated by comparing patients with mild and severe groups. Results POAG patients showed significant bilateral cortical thinning in the anterior half of the visual cortex around the calcarine sulci (left BA 17 and BA 18, right BA17) and in some smaller regions located in the left middle temporal gyrus (BA37) and fusiform gyrus (BA19). The thickness of the visual cortex correlated positively with RNFL thickness (left, r = 0.44, p = 0.01; right, r = 0.38, p = 0.03). Significant differences between mild and severe groups were observed with regard to both RNFL thickness and the thickness of bilateral visual cortex (p < 0.05). Conclusion Our findings indicate that cortical thickness analysis may be sufficiently sensitive to detect cortical alterations in POAG and that the measurement has great potential for clinical application. PMID:24019910

Yin, Xuntao; Liang, Minglong; Evans, Alan C.; Wang, Jian; Dai, Chao

2013-01-01

60

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

61

Reproducibility of Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography in Pseudophakic Eyes  

PubMed Central

Purpose To assess the reproducibility of circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurement (measurement agreement) and its color-coded classification (classification agreement) by Cirrus spectral domain optical coherence tomography (OCT) in pseudophakic eyes. Methods Two-hundred five participants having glaucoma or glaucoma suspected eyes underwent two repeated Cirrus OCT scans to measure cpRNFL thickness (optic disc cube 200 × 200). After classifying participants into three different groups according to their lens status (clear media, cataract, and pseudophakic), values of intra-class coefficient (ICC), coefficient of variance, and test-retest variability were compared between groups for average retinal nerve fiber layer (RNFL) thicknesses and that corresponding to four quadrant maps. Linear weighted kappa coefficients were calculated as indicators of agreement of color code classification in each group. Results ICC values were all excellent (generally defined as 0.75 to 1.00) for the average and quadrant RNFL thicknesses in all three groups. ICC values of the clear media group tended to be higher than those in the cataract and pseudophakic groups for all quadrants and average thickness. Especially in the superior and nasal quadrants, the ICC value of the cataract group was significantly lower than that of the clear media and pseudophakic groups. For average RNFL thickness, classification agreement (kappa) in three groups did not show a statistically significant difference. For quadrant maps, classification agreement (kappa) in the clear media group was higher than those in the other two groups. Conclusions Agreement of cpRNFL measurement and its color code classification between two repeated Cirrus OCT scans in pseudophakic eyes was as good as that in eyes with clear crystalline lens. More studies are required to ascertain the effect of lens status on the reproducibility of Cirrus OCT according to different stages of glaucoma patients. PMID:24688256

Kim, Gyu Ah; Lee, Jun Mo; Park, Kyoung Soo

2014-01-01

62

Alumina Fibre FP  

Microsoft Academic Search

A new experimental inorganic fibre currently under development at the Du Pont Company is a continuous filament, polycrystalline alpha -alumina yarn designated Fibre FP. This fibre is suitable for reinforcing a variety of materials, especially non-ferrous metal castings because of a combination of properties such as high strength and modulus, stability at elevated temperatures, composite castability and potentially low cost.

A. K. Dhingra

1980-01-01

63

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

64

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

PubMed Central

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

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

2014-01-01

65

Ultrafast fibre laser sources: Examples of recent developments  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

66

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

67

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

68

Retinal nerve fiber layer and ganglion cell complex thickness in patients with type 2 diabetes mellitus  

PubMed Central

Aim: The aim of the following study is to evaluate the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness in patients with type 2 diabetes mellitus (DM). Materials and Methods: Average, inferior, and superior values of RNFL and GCC thickness were measured in 123 patients using spectral domain optical coherence tomography. The values of participants with DM were compared to controls. Diabetic patients were collected in Groups 1, 2 and 3. Group 1 = 33 participants who had no diabetic retinopathy (DR); Group 2 = 30 participants who had mild nonproliferative DR and Group 3 = 30 participants who had moderate non-proliferative DR. The 30 healthy participants collected in Group 4. Analysis of variance test and a multiple linear regression analysis were used for statistical analysis. Results: The values of RNFL and GCC in the type 2 diabetes were thinner than controls, but this difference was not statistically significant. Conclusions: This study showed that there is a nonsignificant loss of RNFL and GCC in patients with type 2 diabetes. PMID:25005202

Demir, Mehmet; Oba, Ersin; Sensoz, Hakan; Ozdal, Erhan

2014-01-01

69

SDOCT Thickness Measurements of Various Retinal Layers in Patients with Autosomal Dominant Optic Atrophy due to OPA1 Mutations  

PubMed Central

Purpose. To specify thickness values of various retinal layers on macular spectral domain Optical Coherence Tomography (SDOCT) scans in patients with autosomal dominant optic atrophy (ADOA) compared to healthy controls. Methods. SDOCT volume scans of 7 patients with ADOA (OPA-1 mutation) and 14 healthy controls were quantitatively analyzed using manual grading software. Mean thickness values for the ETDRS grid subfields 5–8 were calculated for the spaces neurosensory retina, retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), a combined space of inner plexiform layer/outer plexiform layer/inner nuclear layer (IPL+INL+OPL), and a combined space of outer nuclear layer/photoreceptor layers (ONL+PL). Results. ADOA patients showed statistically significant lower retinal thickness values than controls (P < 0.01). RNFL (P < 0.001) and GCL thicknesses (P < 0.001) were significantly lower in ADOA patients. There was no difference in IPL+INL+OPL and in ONL+PL thickness. Conclusion. Manual subanalysis of macular SDOCT volume scans allowed detailed subanalysis of various retinal layers. Not only RNFL but also GCL thicknesses are reduced in the macular area of ADOA patients whereas subjacent layers are not involved. Together with clinical findings, macular SDOCT helps to identify patients with suspicion for hereditary optic neuropathy before genetic analysis confirms the diagnosis. PMID:24024178

Schild, Andrea M.; Fricke, Julia; Neugebauer, Antje; Kirchhof, Bernd; Sadda, Srinivas R.

2013-01-01

70

Fluidic fibre dye lasers  

NASA Astrophysics Data System (ADS)

We report the demonstration of compact fluidic fibre lasers based on capillary tubes and photonic crystal fibres, featuring single channel and multiple laterally integrated fluidic lasers respectively. Their preparation was based on capillary action and lasing occurred without the need for external mirrors or lithographically defined microstructures. The fibre lasers were found to be tunable by varying the chromophore density in the liquid core and a functional wavelength selectivity mechanism inherent in both types of lasers provided a long free spectral range that does not correspond to the length of the fibres. The enhanced mode spacing is attributed to a Vernier resonant effect.

Vasdekis, A. E.; Town, G. E.; Turnbull, G. A.; Samuel, I. D. W.

2007-04-01

71

Fibre Flocculation in Papermaking  

NASA Astrophysics Data System (ADS)

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

Kerekes, R. J.

1998-11-01

72

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. PMID:23031247

2012-01-01

73

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. PMID:24982730

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

2014-01-01

74

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

75

Gravity spun polycaprolactone fibres for soft tissue engineering: interaction with fibroblasts and myoblasts in cell culture.  

PubMed

Poly(epsilon-caprolactone) (PCL) fibres were produced by wet spinning from solutions in acetone under low shear (gravity flow) conditions. As-spun PCL fibres exhibited a mean strength and stiffness of 7.9 MPa and 0.1 GPa, respectively and a rough, porous surface morphology. Cold drawing to an extension of 500% resulted in increases in fibre strength (43 MPa) and stiffness (0.3 GPa) and development of an oriented, fibrillar surface texture. The proliferation rate of Swiss 3T3 mouse fibroblasts and C2C12 mouse myoblasts on as-spun, 500% cold-drawn and gelatin-modified PCL fibres was determined in cell culture to provide a basic measure of the biocompatibility of the fibres. Proliferation of both cell types was consistently higher on gelatin-coated fibres relative to as-spun fibres at time points below 7 days. Fibroblast growth rates on cold-drawn PCL fibres exceeded those on as-spun fibres but myoblast proliferation was similar on both substrates. After 1 day in culture, both cell types had spread and coalesced on the fibres to form a cell layer, which conformed closely to the underlying topography. The high fibre compliance combined with a potential for modifying the fibre surface chemistry with cell adhesion molecules and the surface architecture by cold drawing to enhance proliferation of fibroblasts and myoblasts, recommends further investigation of gravity-spun PCL fibres for 3-D scaffold production in soft tissue engineering. PMID:16054685

Williamson, Matthew Richard; Adams, Eric F; Coombes, Allan G A

2006-03-01

76

The UA2 scintillating fibre detector  

NASA Astrophysics Data System (ADS)

The UA2 experiment at CERN is currently upgrading its apparatus to take advantage of the higher accelerator luminosity to be provided from November 1987. The first large particle tracking detector using scintillating optical fibres will form a major part of this upgrade. The detector is built by the Cambridge, CERN and Saclay groups. The Scintillating Fibre Detector is a cylinder of radius 38 to 44 cm, composed of 60000 plastic optical fibres of length over 2 m. The 1 mm diameter fibres are optically clad and aluminised, and are arranged in 24 layers. The detector will be used to track charged particles produced in pp interactions, and also contains a lead converter to cause neutral and charged electromagnetic particles to shower. The signals from the fibres are amplified, multiplexed and digitised by 32 readout chains. These consist of: —A large aperture, de-magnifying image intensifier, providing a gain of ˜ 40000. Extremely fast phosphors are employed for the three stages, to match the short time (4 ps) between particle interactions; —Charge-coupled devices (CCDs) converting the optical image into a single train of electrical pulses for 2000 fibres. A novel use of the anti-blooming electrode of the CCD enables unwanted images to be cleared in <1 ps; —A Fastbus digitiser, which processes the video signal, providing a large degree of data reduction. A full-scale prototype of 960 fibres with readout has been tested in a particle beam. It has demonstrated a good spatial resolution of the tracks (< 0.20 mm), and an excellent discrimination between electrons and hadrons based on the light detected after the converter.

Ansorge, R. E.; Anrouet, C.; Bareyre, P.; Bonamy, P.; Booth, C. N.; Bouchard, M.; Bourdinaud, M.; Cordier, M.; Crittenden, J.; Dewolf, R. S.; Dupont, J.; Dupraz, J.; Einsweiler, K.; Engster, C.; Fabre, J.-P.; Gaillard, J.-M.; Garavel, J.-L.; Hultqvist, K.; Jeanney, C.; Katvars, S. G.; Lefebvre, M.; Linssen, L.; McCluskey, B.; Merkel, B.; Meyer, J.-P.; Munday, D. J.; Nappey, P.; Pentney, J. M.; Reynaud, S.; Rushbrooke, J. G.; Thevenin, J.-C.; Tsang, W. Y.; Weidberg, A. R.; Wells, P. S.; Wotton, S. A.; White, T. O.; Zaccone, H.

1988-12-01

77

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

78

Retinal nerve fiber layer defects and automated perimetry evaluation in ocular hypertensives  

Microsoft Academic Search

Preliminary results of a larger investigation on correlation between Retinal Nerve Fiber Layer Defects (RNFL) and Automated Perimetry (AP) are presented. A group of ocular hypertensive patients was recruited and a cross-section, randomized study was carried out. The group was composed of 54 eyes from 28 patients; 15 men and 13 women, mean age 42.76 year, mean visual acuity 0.95

Emilio Abecia; Francisco M. Honrubia

1992-01-01

79

Glaucoma Progression Detection by Retinal Nerve Fiber Layer Measurement Using Scanning Laser Polarimetry: Event and Trend Analysis  

PubMed Central

Purpose To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. Methods Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). Results Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (±standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 ± 0.148 µm/yr vs. -0.218 ± 0.151 µm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. Conclusions RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression. PMID:22670073

Moon, Byung Gil; Cho, Jung Woo; Kang, Sung Yong; Yun, Sung-Cheol; Na, Jung Hwa; Lee, Youngrok; Kook, Michael S.

2012-01-01

80

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

PubMed Central

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

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

2014-01-01

81

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 PMID:7309897

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

1981-01-01

82

Dynamically reconfigurable fibre optical spanner.  

PubMed

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

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

2014-03-21

83

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

84

Ris-PhD-11(EN) Properties of hemp fibre polymer  

E-print Network

. The mild defibration was performed by degradation of the pectin and lignin rich middle lamellae around explosion of hemp fibres prior defibrated with pectin degrading enzymes. The S2 layer in the fibre wall.3.2 Hemicellulose 28 5.3.3 Lignin 29 5.3.4 Pectin 29 6 From hemp plant to composites 30 6.1 From plant stem to fibre

85

Layers  

NASA Astrophysics Data System (ADS)

The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states ?4( z), ?5( x), and ?5( y) to the conduction-band state ?1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states ?4( z), ?5( x), and ?5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

Hong, K. J.; Jeong, T. S.; Youn, C. J.

2014-09-01

86

Histochemical and functional fibre typing of the rabbit masseter muscle.  

PubMed Central

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

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

1990-01-01

87

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

PubMed Central

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

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

2011-01-01

88

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. PMID:24748770

Yalcin, Elvan; Balci, Ozlem

2014-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

90

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

91

Effect of surface chemistry and topography of sulphite fibres on the transcrystallinity of polypropylene  

Microsoft Academic Search

In the present study the effect of chemically and mechanically treated cellulose materials on the degree of polypropylene transcrystallisation was investigated. The cellulose materials which were sulphite fibres, microcrystalline cellulose (MCC) and knife milled sulphite fibre, were either chemically treated by esterification or mechanically treated by beating. The esterified cellulose materials did not induce a transcrystalline layer, however, all unesterified

Marianne Lenes; Ųyvind W. Gregersen

2006-01-01

92

Comptes Rendus des JNC 17 -Poitiers 2011 Nouvelle mthode de fabrication des composites fibres naturelles  

E-print Network

Comptes Rendus des JNC 17 - Poitiers 2011 1 Nouvelle mƩthode de fabrication des composites Ơ fibres method of manufacture of natural fibers composites: Contribution of a paper layer to minimize mƩcaniques des matƩriaux composites unidirectionnels Ơ fibres naturelles de chanvre et de lin. L

Paris-Sud XI, UniversitƩ de

93

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

PubMed

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

Ata?, Mustafa; Yuvac?, Isa; Demircan, Süleyman; Güler, Emel; Altunel, Orhan; Pangal, Emine; Gökta?, Altan; Sütbeyaz, Serap; Zarars?z, Gökmen

2014-01-01

94

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

PubMed Central

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

Ata?, Mustafa; Yuvac?, ?sa; Demircan, Süleyman; Güler, Emel; Altunel, Orhan; Pangal, Emine; Gökta?, Altan; Sütbeyaz, Serap; Zarars?z, Gökmen

2014-01-01

95

Fibre materials for advanced technical textiles  

Microsoft Academic Search

In this article, most kinds of fibre materials used for advanced technical textiles are systematically introduced. The definition of advanced technical textiles and the scope of fibre materials used for advanced technical textiles are given in the introductory chapter, PET, nylon and PP fibres are explained as three major conventional fibres for advanced technical textiles. High mechanical performance fibres such

T. Matsuo

2008-01-01

96

OPTICAL FIBRES: Optical properties of fibres with aluminophosphosilicate glass cores  

NASA Astrophysics Data System (ADS)

The optical properties of fibres with aluminophosphosilicate (APS) glass cores have been studied at Al2O3 and P2O5 concentrations varied independently from 0 to 20%, and the ranges of dopant concentrations that ensure an optical loss level acceptable for the fabrication of active fibres have been established. The origin of the increased losses observed previously in APS fibres containing excess phosphorus pentoxide has been identified, and the contamination source responsible for such losses in our fibres has been eliminated.

Bubnov, M. M.; Gur'yanov, Aleksei N.; Zotov, K. V.; Iskhakova, L. D.; Lavrishchev, S. V.; Lipatov, D. S.; Likhachev, M. E.; Rybaltovsky, A. A.; Khopin, V. F.; Yashkov, M. V.; Dianov, Evgenii M.

2009-09-01

97

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

PubMed Central

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

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

2014-01-01

98

Retinal Nerve Fiber Layer Thickness Changes in Parkinson Disease: A Meta-Analysis  

PubMed Central

Background Parkinson disease (PD) is a neurodegenerative process that leads to a selective loss of dopaminergic neurons, mainly in the basal ganglia of the brain. Numerous studies have analyzed the ability of optical coherence tomography (OCT) to detect retinal nerve fiber layer (RNFL) thickness abnormalities and changes in PD, but the results have not always been consistent. Therefore, we carried out a meta-analysis to evaluate the RNFL thickness measured with OCT in PD. Methods and Findings Case-control studies were selected through an electronic search of the Cochrane Controlled Trials Register, PUBMED and EMBASE. For the continuous outcomes, we calculated the weighted mean difference (WMD) and 95% confidence interval (CI). The statistical analysis was performed by RevMan 5.0 software. Thirteen case-control studies were included in the present meta-analysis, containing a total of 644 eyes in PD patients and 604 eyes in healthy controls. The results of our study showed that there was a significant reduction in average RNFL thickness in patients with PD compared to healthy controls (WMD?=??5.76, 95% CI: ?8.99 to ?2.53, P?=?0.0005). Additionally, differences of RNFL thickness in superior quadrant (WMD?=??4.44, 95% CI: ?6.93 to ?1.94, P?=?0.0005), inferior quadrant (WMD?=??7.56, 95% CI: ?11.33 to ?3.78, P<0.0001), nasal quadrant (WMD?=??3.12, 95% CI: ?5.63 to ?0.61, P?=?0.01) and temporal quadrant (WMD?=??4.63, 95% CI: ?7.20 to ?2.06, P?=?0.0004) were all significant between the two groups. Conclusion In view of these results and the noninvasive nature of OCT technology, we surmise that OCT could be a useful tool for evaluating the progression of the Parkinson disease. Trial Registration ClinicalTrials.gov NCT01928212 PMID:24465663

Yu, Ji-guo; Feng, Yi-fan; Xiang, Yi; Huang, Jin-hai; Savini, Giacomo; Parisi, Vincenzo; Yang, Wan-ju; Fu, Xun-an

2014-01-01

99

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

100

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. PMID:22778147

Nakagawa, Kaori; Yoshinaga, Arata; Takabe, Keiji

2012-01-01

101

Local real-time detection of pH using fibre tapers  

NASA Astrophysics Data System (ADS)

A size of tapered silica fibre probes makes them suitable for exploration of small objects, as e.g. cells. Fibre-optic probes of enhanced mechanical durability can be advantageously used particularly for investigation of plant cells with hard walls. The paper deals with preparation of suitable optical probes based on coated fibre tapers and their using for local detection of extracellular pH in samples simulating native conditions of plant cells. Fibre tapers from single-mode and polymer-clad-silica fibres were prepared by tapering apparatus of own construction. The drawn tapers were immediately coated with a thin layer of Indium-Tin-Oxide in order to protect them from embrittlement. A CO2 laser was used for cutting the tapered fibres in narrow taper waist. Opto-chemical transducer 2',7'- Bis(2-carbonylethyl)-5(6)-carboxyfluorescein was immobilized onto the end-face of cut fibre tapers by a thin TEOS layer. The pH was determined by fluorescence spectroscopy using excitation wavelength 473 nm. The fibre taper probes of waist diameter from 80 ?m to 2 ?m and of suitable optical and mechanical properties were prepared. Suitability of opto-chemical transducer 2',7'-Bis(2-carbonylethyl)-5(6)-carboxyfluorescein for detection of samples simulating native conditions of pH ranging from 5.0 to 7.0 was confirmed. This approach has allowed us to determine extra-cellular pH of in-vitro samples.

Kasik, Ivan; Martan, Tomas; Podrazky, Ondrej; Mrazek, Jan; Pospisilova, Marie; Matejec, Vlastimil

2009-05-01

102

Influence of wood-fibre hygroexpansion on the dimensional instability of fibre mats and composites  

Microsoft Academic Search

Wood fibres are gaining increased use as reinforcement in plastics. One of the disadvantages of cellulose-based fibres is their propensity to absorb water and swell. This inevitably leads to undesired dimensional instability of the composite and its fibre-mat preform. A measure of the hygroexpansion behaviour of the fibres could serve to rank the suitability of different kinds of cellulosic fibres

R. Cristian Neagu; E. Kristofer Gamstedt; Mikael Lindström

2005-01-01

103

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

104

Random distributed feedback fibre lasers  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

105

Ultrasonic assembly of anisotropic short fibre reinforced composites.  

PubMed

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

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

2014-04-01

106

Comparison of Peripapillary Retinal Nerve Fiber Layer Loss and Visual Outcome in Fellow Eyes Following Sequential Bilateral Non-Arteritic Anterior Ischemic Optic Neuropathy.  

PubMed

ABSTRACT Aim: To report on the correlation of structural damage to the axons of the optic nerve and visual outcome following bilateral non-arteritic anterior ischemic optic neuropathy. Methods: A retrospective review of the medical records of 25 patients with bilateral sequential non-arteritic anterior ischemic optic neuropathy was performed. Outcome measures were peripapillary retinal nerve fiber layer thickness measured with the Stratus optical coherence tomography scanner, visual acuity and visual field loss. Results: Median peripapillary retinal nerve fiber layer (RNFL) thickness, mean deviation (MD) of visual field, and visual acuity of initially involved NAION eyes (54.00?µm, -17.77 decibels (dB), 0.4, respectively) were comparable to the same parameters measured following development of second NAION event in the other eye (53.70?µm, p?=?0.740; -16.83 dB, p?=?0.692; 0.4, p?=?0.942, respectively). In patients with bilateral NAION, there was a significant correlation of peripapillary RNFL thickness (r?=?0.583, p?=?0.002) and MD of the visual field (r?=?0.457, p?=?0.042) for the pairs of affected eyes, whereas a poor correlation was found in visual acuity of these eyes (r?=?0.279, p?=?0.176). Peripapillary RNFL thickness following NAION was positively correlated with MD of visual field (r?=?0.312, p?=?0.043) and negatively correlated with logMAR visual acuity (r?=?-0.365, p?=?0.009). Conclusion: In patients who experience bilateral NAION, the magnitude of RNFL loss is similar in each eye. There is a greater similarity in visual field loss than in visual acuity between the two affected eyes with NAION of the same individual. PMID:25153943

Dotan, Gad; Kesler, Anat; Naftaliev, Elvira; Skarf, Barry

2014-08-25

107

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. PMID:24959500

Martķnez-Gamero, Bertha O.; Mohamed-Noriega, Jibran; Cavazos-Adame, Med. Humberto; Mohamed-Hamsho, Med. Jesśs

2014-01-01

108

In vitro recordings of afferent fibres with receptive fields in the serosa, muscle and mucosa of rat colon  

PubMed Central

Colonic afferent fibres were recorded using a novel in vitro preparation. Fibres with endings in the colonic mucosa are described, along with those in muscle and serosa, and their responses to a range of mechanical and chemical luminal stimuli. Mechanical stimuli were applied to the tissue, which included stretch, blunt probing of the mucosa and stroking of the mucosa with von Frey hairs (10-1000 mg). Chemical stimuli were applied into a ring that was placed over the mechanoreceptive field of the fibre; these were distilled water, 154 and 308 mM NaCl, 100 ?M capsaicin, 50 mM HCl, and undiluted and 50 % ferret bile. Recordings were made from 52 fibres, 12 of which showed characteristics of having endings in the mucosa. Mucosal afferents were sensitive to a 10 mg von Frey hair and were generally chemosensitive to ? 1 chemical stimulus. Ten fibres showed characteristics of having receptive fields in the muscular layer. These fibres responded readily to circumferential stretch, as well as to blunt probing. Twenty-seven fibres showed characteristics of having endings in the serosal layer. They adapted rapidly to circumferential stretch and responded to blunt probing of the serosa. Fifteen of 19 serosal fibres tested also responded to luminal chemicals. Three fibres were unresponsive to all mechanical stimuli but were recruited by chemical stimuli. This is the first characterization of colonic afferent fibres using an in vitro method and the first documentation of afferent fibres with their endings in the mucosa of the colon. These fibres are likely to be important in aspects of colonic sensation and reflex control. PMID:10373708

Lynn, Penny A; Blackshaw, L Ashley

1999-01-01

109

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; Protičre, S; Beebe, A Y; Stone, H A

2012-02-23

110

Multifunctional, supramolecular, continuous artificial nacre fibres  

PubMed Central

Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized “brick-and-mortar” (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance. PMID:23097689

Hu, Xiaozhen; Xu, Zhen; Gao, Chao

2012-01-01

111

Multifunctional, supramolecular, continuous artificial nacre fibres  

NASA Astrophysics Data System (ADS)

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

Hu, Xiaozhen; Xu, Zhen; Gao, Chao

2012-10-01

112

Multifunctional, supramolecular, continuous artificial nacre fibres.  

PubMed

Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized "brick-and-mortar" (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance. PMID:23097689

Hu, Xiaozhen; Xu, Zhen; Gao, Chao

2012-01-01

113

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

114

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

115

Photonic-crystal fibre: Mapping the structure  

NASA Astrophysics Data System (ADS)

The demonstration of real-time and non-destructive Doppler-assisted tomography of the internal structure of photonic-crystal fibres could aid the fabrication of high-quality fibres with enhanced performance.

Markos, Christos

2015-01-01

116

Novel pulp fibre reinforced thermoplastic composites  

Microsoft Academic Search

The reinforcement potential of pulp fibres is presently not fully explored in thermoplastic composites. One of the reasons is that currently used processing methods comprise several severe thermomechanical steps inducing premature degradation of the fibres. Three pre-forming techniques were developed to prepare pulp fibre reinforced cellulose diacetate (CDA) pre-forms, namely filtration-forming, solvent impregnation, and commingling with polymer fibres. These techniques

L Lundquist; B Marque; P.-O Hagstrand; Y Leterrier; J.-A. E Månson

2003-01-01

117

Super-tough carbon-nanotube fibres  

NASA Astrophysics Data System (ADS)

The energy needed to rupture a fibre (its toughness) is five times higher for spider silk than for the same mass of steel wire, which has inspired efforts to produce spider silk commercially. Here we spin 100-metre-long carbon-nanotube composite fibres that are tougher than any natural or synthetic organic fibre described so far, and use these to make fibre supercapacitors that are suitable for weaving into textiles.

Dalton, Alan B.; Collins, Steve; Muńoz, Edgar; Razal, Joselito M.; Ebron, Von Howard; Ferraris, John P.; Coleman, Jonathan N.; Kim, Bog G.; Baughman, Ray H.

2003-06-01

118

Dietary fibre and colonic neoplasia.  

PubMed Central

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

Freeman, H J

1979-01-01

119

Modelling film flows down a fibre  

NASA Astrophysics Data System (ADS)

Consider the gravity-driven flow of a thin liquid film down a vertical fibre. A model of two coupled evolution equations for the local film thickness h and the local flow rate q is formulated within the framework of the long-wave and boundary-layer approximations. The model accounts for inertia and streamwise viscous diffusion. Evolution equations obtained by previous authors are recovered in the appropriate limit. Comparisons to experimental results show good agreement in both linear and nonlinear regimes. Viscous diffusion effects are found to have a stabilizing dispersive effect on the linear waves. Time-dependent computations of the spatial evolution of the film reveal a strong influence of streamwise viscous diffusion on the dynamics of the flow and the wave selection process.

Ruyer-Quil, C.; Treveleyan, P.; Giorgiutti-Dauphin?, F.; Duprat, C.; Kalliadasis, S.

120

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

PubMed Central

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

GRITSCH, CRISTINA SANCHIS; MURPHY, RICHARD J.

2005-01-01

121

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 PMID:8226288

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

1993-01-01

122

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

123

High-tech Fibres for Technical Textiles  

Microsoft Academic Search

This review explains how an understanding of relationships between the fine structure of fibres and their physical properties has developed over the past 60 or 70 years, culminating in the production of high-tech fibres with greatly superior properties, utilised in technical textiles, which are now commonplace aspects of modern life. In the early days, when natural fibres of cellulose were

D. J. Johnson

2003-01-01

124

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

125

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

126

Multi Stage Fibre Optic Probes  

NASA Astrophysics Data System (ADS)

Fibre optic probes easily can be placed on high explosive charges. Thus the detonation front can be observed while breaking through the surface of the charge. By inser ting those probes in a high explosive charge, this technique can be extended to a diagnostic tool for observation detonation phenomena inside the charge. Arrival time at the tip of the probes can be measured simultaniously to the break-through of the detonation front at the outer surface of the charge when a streak camera is used Each of the light fibres can transduce one light pulse only If there is need for observation in several planes of the high explosive charge the number of probes has to be increased to an amount which however causes severe disturbance of the detonation wave propagation. The detonation wave can be observed in a multi-planar way by means of a new probetechnique avoiding the disadvantage mentioned above. The light fibre probe now has several airgaps placed appropriately along the probe, each of them giving an output of light at the end of the probe when the detonation wave propagates down the probe. Thus by multiplanar diagnostic of the detonation wave inside a high explosive charge it is possible to measure the detonation front with comparatively small disturbances and little effort. Practicable solutions for the set-up of the light fibre probes are discussed and the advantage of this technique is demonstrated on examples.

Held, M.; Nikowitsch, P.

1985-02-01

127

Wool as a Technical Fibre  

Microsoft Academic Search

To use wool successfully in technical applications requires a high-value application that can exploit its natural properties, a reduction in costs, or modifying the fibre to achieve a particular target performance. Wool is increasingly being used in technical applications in which its unique properties and the opportunities for specific enhancements can be profitably utilised. This paper examines wool's attributes for

N. A. G. Johnson; E. J. Wood; P. E. Ingham; S. J. McNeil; I. D. McFarlane

2003-01-01

128

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

129

Elastic fibres in health and disease.  

PubMed

Elastic fibres are insoluble components of the extracellular matrix of dynamic connective tissues such as skin, arteries, lungs and ligaments. They are laid down during development, and comprise a cross-linked elastin core within a template of fibrillin-based microfibrils. Their function is to endow tissues with the property of elastic recoil, and they also regulate the bioavailability of transforming growth factor ?. Severe heritable elastic fibre diseases are caused by mutations in elastic fibre components; for example, mutations in elastin cause supravalvular aortic stenosis and autosomal dominant cutis laxa, mutations in fibrillin-1 cause Marfan syndrome and Weill-Marchesani syndrome, and mutations in fibulins-4 and -5 cause autosomal recessive cutis laxa. Acquired elastic fibre defects include dermal elastosis, whereas inflammatory damage to fibres contributes to pathologies such as pulmonary emphysema and vascular disease. This review outlines the latest understanding of the composition and assembly of elastic fibres, and describes elastic fibre diseases and current therapeutic approaches. PMID:23962539

Baldwin, Andrew K; Simpson, Andreja; Steer, Ruth; Cain, Stuart A; Kielty, Cay M

2013-01-01

130

‘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. PMID:23112385

Ishizuka, Hisao

2012-01-01

131

Ytterbium fibre laser with a heavily Yb{sup 3+}-doped glass fibre core  

SciTech Connect

The use of optical fibres with a high concentration of active ions in the fibre core allows the reduction of the active fibre length and the increase in the threshold powers of various nonlinear effects in the fibre, thereby increasing the maximum output power of fibre lasers. For this purpose, we manufactured a highly concentrated ytterbium-doped ({approx}1.0x10{sup 21}cm{sup -3}) phosphate glass for the active fibre core and a pure glass of a similar composition for the fibre cladding. A single-mode fibre is fabricated from these glasses and generation is obtained in an ytterbium laser based on this fibre with the slope efficiency of no less than 60% at a wavelength of 975 nm. (letters)

Bufetov, Igor' A; Semenov, S L; Kosolapov, A F; Mel'kumov, Mikhail A; Dudin, V V; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Galagan, B I; Denker, B I; Osiko, Vyacheslav V; Sverchkov, S E [Laser Materials and Technology Research Center, A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2006-03-31

132

Growth of calcium phosphate on phosphorylated chitin fibres.  

PubMed

Calcium phosphate growth on chitin phosphorylated fibres was studied using scanning electron microscopy and energy dispersive X-ray analysis (SEM, EDX), micro-Fourier transform infrared spectroscopy (FTIR), and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The C6 chemical shift positions of 13C MAS NMR in the chitin fibres phosphorylated using urea and H3PO4 are obvious indicating that phosphorylation takes place not in the C1 but in the C6 region. Micro-FTIR and 31P MAS NMR suggested that ammonium hydrogen phosphate formed during the phosphorylation procedure. Chitin fibres phosphorylated using urea and H3PO4 and then soaked in saturated Ca(OH)2 solution at ambient temperature, which lead to the formation of thin coatings formed by partial hydrolysis of the PO4 functionalities, were found to stimulate the growth of a calcium phosphate coating on their surfaces after soaking in 1.5xSBF solution for as little as one day. The thin layer after Ca(OH)2 treatment functioned as a nucleation layer for further calcium phosphate deposition after soaking in 1.5xSBF solution. EDX-measured Ca : P ratios of the coatings of Ca(OH)2-treated phosphorylated chitin in 1.5xSBF solution suggested that calcium-deficient apatite was formed. PMID:15348722

Yokogawa, Y; Paz Reyes, J; Mucalo, M R; Toriyama, M; Kawamoto, Y; Suzuki, T; Nishizawa, K; Nagata, F; Kamayama, T

1997-07-01

133

Tapered optical fibres for local pH detection  

NASA Astrophysics Data System (ADS)

This paper deals with preparation of optical probes based on tapered optical fibres and their using for local detection of pH in samples simulating native conditions of plant cells. Optical probes, so-called V-tapers were prepared for this purpose. Fluorescence pH transducer 2',7'-Bis(2-carbonylethyl)-5(6)-carboxyfluorescein was immobilized onto the end-face of cut V-tapers in a thin xerogel layer. Changes of fluorescence-intensity spectra caused by pH changes were employed for pH measurements. Indium-tin oxide or aluminium coated fibre probes with suitable optical and mechanical properties were successfully tested. It has been confirmed that the selected pH transducer is suitable for pH detection from 5.0 to 7.0. This approach has allowed us to determine extra-cellular pH of in-vitro samples.

Martan, T.; Pospisilova, M.; Aubrecht, J.; Mrazek, J.; Podrazky, O.; Kasik, I.; Matejec, V.

2010-02-01

134

Optical fibres based on natural biological minerals - sea sponge spicules  

SciTech Connect

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

Kulchin, Yu N; Voznesenskii, S S; Galkina, A N; Mal'tseva, T L; Nagornyi, I G [Institute for Automation and Control Processes, Far-Eastern Branch, Russian Academy of Sciences, Vladivostok (Russian Federation); Bukin, O A [V.I. Il'ichev Pacific Oceanological Institute, Far-Eastern Division of the Russian Academy of Sciences, Vladivostok (Russian Federation); Gnedenkov, S V; Kuryavyi, V G; Sinebryukhov, S L; Cherednichenko, A I [Institute of Chemistry, Far East Branch of the Russian Academy of Sciences, Vladivostok (Russian Federation); Drozdov, A L [Institute of Marine Biology, Far Eastern Branch of Russian Academy of Sciences, Vladivostok (Russian Federation)

2008-01-31

135

Isolation of nanocellulose from pineapple leaf fibres by steam explosion  

Microsoft Academic Search

Steam explosion process is employed for the successful extraction of cellulose nanofibrils from pineapple leaf fibres for the first time. Steam coupled acid treatment on the pineapple leaf fibres is found to be effective in the depolymerization and defibrillation of the fibre to produce nanofibrils of these fibres. The chemical constituents of the different stages of pineapple fibres undergoing treatment

Bibin Mathew Cherian; Alcides Lopes Lećo; Sivoney Ferreira de Souza; Sabu Thomas; Laly A. Pothan; M. Kottaisamy

2010-01-01

136

Nanocellulose enhanced interfaces in truly green unidirectional fibre reinforced composites  

Microsoft Academic Search

One of the main problems in fabricating natural fibre reinforced polymers is the poor adhesion between intrinsically polar plant fibres and non-polar polymer matrices. We have developed a truly green technique of modifying natural fibre (hemp and sisal) surfaces to improve the interaction between the fibres and polymers by attaching nano-scale bacterial cellulose to the fibre surfaces. These modified natural

Julasak Juntaro; Marion Pommet; Athanasios Mantalaris; Milo Shaffer; Alexander Bismarck

2007-01-01

137

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

PubMed Central

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

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

2014-01-01

138

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

PubMed Central

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

2010-01-01

139

International Year of Natural Fibres  

NSDL National Science Digital Library

The United Nations Food and Agriculture Organization has designated 2009 as the International Year of Natural Fibres. The goals of this year are three-fold: to raise the profile of natural fibers in a market increasingly dominated by synthetic fibers; convey the value of using natural fibers to consumers; and help sustain the income of the often poor farmers of natural fibers. This very interesting website for the "Year" is available in English, French, Chinese and Spanish. Visitors interested in learning about the history of natural fibers, as well as what different types of natural fibers there are, what they look like, and what they are used for, will find this website fits the bill. On the menu on the far right side of the page, visitors can click on the link "15 Natural Fibres" to peruse a brief history and learn about the different natural fibers that come from plants and animals. Most of the fibers featured include information on what the fiber is, who produces it, how it's produced, and how much is produced, which can be accessed by rolling the mouse over the name or picture of the fiber, and clicking. The link on the menu on the far right side of the page entitled "Fibre Stories" has four stories about new innovations for several different natural fibers. There is a story about cotton in Asia, hemp in China, alpaca in Peru, and sisal in Tanzania. Events around the world celebrating the International Year of Natural Fibres can be found on the far right menu, at the "Events" link.

140

Motor unit fibre density in the extensor digitorum communis muscle. Single fibre electromyographic study in normal subjects at different ages  

Microsoft Academic Search

A single fibre EMG study is presented from extensor digitorum communis muscle in sujbects aged 10 to 89 years. The average number of single muscle fibre action potentials generated by muscle fibres in the same motor unit within the uptake area of the electrode is used as a measure of the motor unit fibre density. The fibre density increases slowly

E Stålberg; B Thiele

1975-01-01

141

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

142

Study of water sorption properties for esparto grass ultimate fibre (ALFA fibre)  

Microsoft Academic Search

Natural fibres present multiple characteristics and are used in many fields such as textiles, technical or medical applications. In this context, we tried to use ligno-cellulosic fibres extracted from esparto (Stipa tenacissima L) as a support fiber in hygienic products. Due to their cellulosic nature, esparto fibres can provide a certain water sorption potential. In fact, fluff pulp was always

S. Sayeb; I. Marzoug; M. Ben Hassen; F. Sakli; S. Rodesli

2010-01-01

143

Effect of fibre curl on the properties of wood pulp fibre-cement and silica sheets  

Microsoft Academic Search

Curl has been induced in unbleached softwood kraft pulp fibres by treatment in the laboratory at 20% consistency in a planetary mixer. Steam treatment of the fibres to set the curl more strongly was found to be detrimental to fibre properties as deduced from handsheet properties. A means of producing two-ply specimens in the laboratory was devised and a tensile

A. J. Michell; G. Freischmidt

1990-01-01

144

Capillary supply and cross-sectional area of slow and fast twitch muscle fibres in man  

Microsoft Academic Search

The muscles triceps brachii, quadriceps femoris (part vastus lateralis) and soleus were analysed in 6 men and 6 women for fibre composition (% slow twitch, ST-fibres and % fast twitch, FT-fibres), fibre cross sectional areas, and capillarization. Also the fraction of fibres enclosed by their own fibre type was analysed together with the capillary supply of these fibres. Fibre composition

G. Sjųgaard

1982-01-01

145

PRECAUTIONS FOR THE STRUCTURALANALYSIS OF THE GELATINOUS LAYER IN TENSION WOOD  

E-print Network

PRECAUTIONS FOR THE STRUCTURALANALYSIS OF THE GELATINOUS LAYER IN TENSION WOOD by Bruno Clair1, 2, CC 048, 34095 Montpellier CDX 5, France #12;SUMMARY The gelatinous layer (G-layer) of tension wood-layer. Key-words: artefact, fibre wall, gelatinous layer (G-layer), tension wood INTRODUCTION The study

Paris-Sud XI, UniversitƩ de

146

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

147

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

PubMed

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

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

2010-01-01

148

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

149

Occurrence and propagation of delamination during the machining of carbon fibre reinforced plastics (CFRPs) – An experimental study  

Microsoft Academic Search

The machining of carbon fibre reinforced plastics (CFRPs) is often accompanied by delamination of the top layers of the machined edges. Such damage necessitates time-consuming and costly post-machining and in some cases leads to rejection of components. The work described in this paper systematically investigates the occurrence of delamination of the top layers during the machining of CFRP tape, with

Wolfgang Hintze; Dirk Hartmann; Christoph Schütte

2011-01-01

150

Reduction in retinal nerve fiber layer thickness in migraine patients.  

PubMed

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

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

2013-06-01

151

Behaviour of Sand Reinforced with Fibres  

NASA Astrophysics Data System (ADS)

This study focuses on the effects of randomly oriented discrete crimped polypropylene fibres on the mechanical response of very fine sand. Compaction and direct shear tests were performed on sand specimens of different densities unreinforced and reinforced with fibres in different proportions. The presence of reinforcement provides an extra resistance to the compaction, causing a less dense packing as the quantity of fibres is increased. The results of the direct shear tests indicate that inclusion of fibres increases the peak shear strength and the strain required to reach the peak. The post-peak strength at large strains was also higher when fibres were included. The presence of fibres leads to more dilative behaviour. In this study, for the range of the effective normal stresses employed, a linear failure envelope has been recorded for all densities and fibre concentrations. The increase of the peak shear strength was almost linear for all densities at low effective normal stress and approached a limiting value for higher normal stresses. For the loosest specimens reinforced with the highest percentage of fibres that could be employed in the laboratory using a moist tamping fabrication method, the relative increase of the peak shear strength was more than 50%.

Ibraim, Erdin; Fourmont, Stephane

152

Progress of coherent optical fibre communication systems  

Microsoft Academic Search

The recent progress of coherent optical fibre communication systems is reviewed. System constituent technologies, such as coherent optical modulation-demodulation, optical direct amplification for repeaters and single polarization fibre transmission are outlined. Several important optical device technologies, such as frequency stabilization of semiconductor lasers, AM and FM quantum noise and their reduction, and integrated opto-electronic devices, are also described. Finally, on

Tatsuya Kimura; Yoshihisa Yamamoto

1983-01-01

153

EDITORIAL: Optical Fibre Sensors 17 (OFS-17)  

Microsoft Academic Search

This special issue of Measurement Science and Technology provides an overview of current developments in the field of optical fibre sensors. The papers presented here are more detailed versions of those presented at the 17th Optical Fibre Sensors conference (OFS-17) held at the Oud St-Jan Art and Congress Centre in Bruges, Belgium, from 23 27 May 2005. The first OFS

Ralph P. Tatam; Julian D. C. Jones

2006-01-01

154

The fatigue behaviour of Kevlar-29 fibres  

Microsoft Academic Search

Single Kevlar-29 fibres have been subjected to a variety of tensile cyclic and steady loading conditions. The dispersion of tensile strengths of the samples tested was found to be inherent to the fibre due to the distribution of defects in it and not due to variations of diameter between samples. Cyclic loading was found to produce both longer and shorter

M. H. Lafitte; A. R. Bunsell

1982-01-01

155

CONCENTRATION OF NUCLEI IN CHICKEN MUSCLE FIBRE  

E-print Network

.e. muscle proteins. The aim of the present investigation was to compare the changes of nuclear concentrationCONCENTRATION OF NUCLEI IN CHICKEN MUSCLE FIBRE IN RELATION TO THE INTENSITY OF GROWTH Helena KNƍ concentration on a constant length segment of muscle fibre released by maceration has been investigated

Paris-Sud XI, UniversitƩ de

156

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

157

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

158

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

159

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 Cancśn, 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, Gonzįlez-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

160

Fibre-Matrix Interaction in Soft Tissue  

SciTech Connect

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 [Departments of Civil and Mechanical Engineering, University of Glasgow Glasgow G12 8LT (United Kingdom)

2010-05-21

161

Highly efficient Raman distributed feedback fibre lasers.  

PubMed

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

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

2012-02-27

162

Compression fracture of unidirectional carbon fibre-reinforced plastics  

Microsoft Academic Search

The effect of volume fraction and tensile strength of fibres, temperature and stress concentrators on the compression strength and fracture mode of unidirectional CFRP was studied. The cause of kinking is different for composites reinforced by low-(<3 GPa) and high-strength fibres. If fibre strength is high, the kink is initiated by composite splitting followed by fibre bend fracture in the

S. L. Bazhenov; V. V. Kozey

1991-01-01

163

Health benefits of cereal fibre: a review of clinical trials  

PubMed Central

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

Smith, Caren E.; Tucker, Katherine L.

2011-01-01

164

Controlling dust when cutting fibre-cement board  

E-print Network

Controlling dust when cutting fibre-cement board Page 1 of 2 Cutting fibre-cement board (e are not typically used when cutting and shaping fibre-cement board. To protect yourself you should: Use one of the methods described above for cutting fibre-Ā· cement board Inspect the dust control equipment before you

Knowles, David William

165

Extraction of nanocellulose fibrils from lignocellulosic fibres: A novel approach  

Microsoft Academic Search

The objective of this work was to develop a simple process to obtain an aqueous stable colloid suspension of cellulose nano fibrils from various lignocellulosic fibres. For the preliminary analysis we have studied three different fibres: banana (pseudo stem), jute (stem) and pineapple leaf fibre (PALF). To study the feasibility of extracting cellulose from these raw fibres we have adopted

E. Abraham; B. Deepa; L. A. Pothan; M. Jacob; S. Thomas; U. Cvelbar; R. Anandjiwala

2011-01-01

166

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

167

Modelling dichotomously marked muscle fibre configurations.  

PubMed

Human skeletal muscle consists of contractile elements (fibres) that may be differentiated according to their physiological and biochemical properties. The different types of fibre are distributed throughout each muscle, with the pattern (when viewed as a cross-section) of cell distribution being an important determinant of the functional properties of each muscle. It is well known that the proportions and distributions of muscle fibre types change with advancing age or disease, but few studies have quantitatively investigated these changes. A better knowledge of the nature of changes in muscle fibre distributions is an essential requirement for future development of therapies and interventions directed at maintaining or restoring good muscle function. In this work, we examine several statistical methods designed to gauge the departure of a dichotomously labelled muscle fibre distribution from that of a random fibre-type dispersal. These methods are also applicable to a wide range of biological investigations in which the spatial distribution of cells or specimens underpins an important biological principle. This work includes the proposal of a novel technique, based on weighted kernel-smoothed density ratios, which can account for the variable areas of the individual fibres. We illustrated the methodology by using a number of real-data examples, and we employed a comprehensive set of simulations to assess the empirical power and false-positive rates of these tests. PMID:23564677

Davies, Tilman M; Cornwall, Jon; Sheard, Philip W

2013-10-30

168

Retinal nerve fiber layer reflectance for early glaucoma diagnosis  

PubMed Central

Purpose Compare performance of normalized reflectance index (NRI) and retinal nerve fiber layer thickness (RNFLT) parameters determined from OCT images for glaucoma and glaucoma suspect diagnosis. Methods Seventy-five eyes from seventy-one human subjects were studied: 33 controls, 24 glaucomatous, and 18 glaucoma-suspects. RNFLT and NRI maps were measured using two custom-built OCT systems and the commercial instrument RTVue. Using area under the receiver operating characteristic (ROC) curve, RNFLT and NRI measured in seven RNFL locations were analyzed to distinguish between control, glaucomatous, and glaucoma-suspect eyes. Results The mean NRI of the control group was significantly larger than the means of glaucomatous and glaucoma-suspect groups in most RNFL locations for all three OCT systems (p<0.05 for all comparisons). NRI performs significantly better than RNFLT at distinguishing between glaucoma-suspect and control eyes using RTVue OCT (p=0.008). The performances of NRI and RNFLT for classifying glaucoma-suspect vs. control eyes were statistically indistinguishable for PS-OCT-EIA (p=0.101) and PS-OCT-DEC (p=0.227). The performances of NRI and RNFLT for classifying glaucomatous vs. control eyes were statistically indistinguishable (PS-OCT-EIA: p=0.379; PS-OCT-DEC: p=0.338; RTVue OCT: p=0.877). Conclusions NRI is a promising measure for distinguishing between glaucoma-suspect and control eyes and may indicate disease in the pre-perimetric stage. Results of this pilot clinical study warrant a larger study to confirm the diagnostic power of NRI for diagnosing pre-perimetric glaucoma. PMID:23835671

Liu, Shuang; Wang, Bingqing; Yin, Biwei; Milner, Thomas E.; Markey, Mia K.; McKinnon, Stuart J.; Rylander, H. Grady

2013-01-01

169

Gibberellin mediates the development of gelatinous fibres in the tension wood of inclined Acacia mangium seedlings  

PubMed Central

Background and Aims Gibberellin stimulates negative gravitropism and the formation of tension wood in tilted Acacia mangium seedlings, while inhibitors of gibberellin synthesis strongly inhibit the return to vertical growth and suppress the formation of tension wood. To characterize the role of gibberellin in tension wood formation and gravitropism, this study investigated the role of gibberellin in the development of gelatinous fibres and in the changes in anatomical characteristics of woody elements in Acacia mangium seedlings exposed to a gravitational stimulus. Methods Gibberellin, paclobutrazol and uniconazole-P were applied to the soil in which seedlings were growing, using distilled water as the control. Three days after the start of treatment, seedlings were inclined at 45 ° to the vertical and samples were harvested 2 months later. The effects of the treatments on wood fibres, vessel elements and ray parenchyma cells were analysed in tension wood in the upper part of inclined stems and in the opposite wood on the lower side of inclined stems. Key Results Application of paclobutrazol or uniconazole-P inhibited the increase in the thickness of gelatinous layers and prevented the elongation of gelatinous fibres in the tension wood of inclined stems. By contrast, gibberellin stimulated the elongation of these fibres. Application of gibberellin and inhibitors of gibberellin biosynthesis had only minor effects on the anatomical characteristics of vessel and ray parenchyma cells. Conclusions The results suggest that gibberellin is important for the development of gelatinous fibres in the tension wood of A. mangium seedlings and therefore in gravitropism. PMID:24043495

Nugroho, Widyanto Dwi; Nakaba, Satoshi; Yamagishi, Yusuke; Begum, Shahanara; Marsoem, Sri Nugroho; Ko, Jae-Heung; Jin, Hyun-O; Funada, Ryo

2013-01-01

170

High pressure CVD inside microstructured optical fibres  

Microsoft Academic Search

We report the fabrication of semiconductor structures within holey fibres via a pressure driven microfluidic chemical vapour deposition process, demonstrating templated growth of crystalline Group IV semiconductor structures and devices in extreme aspect ratio geometries.

Pier J. A. Sazio; Adrian Amezcua-Correa; Chris E. Finlayson; John R. Hayes; Thomas J. Scheidemantel; Feng Zhang; Elena R. Margine; Neil F. Baril; Bryan R. Jackson; John V. Badding; Dong-Jin Won; Venkatraman Gopalan; Vincent H. Crespi

2006-01-01

171

GMOS\\/bHROS Fibre Connection  

Microsoft Academic Search

Over the last year (2002-2003) ING was subcontracted by University College London (UCL) to produce a module of 18 science fibres for the bHROS instrument, one of the instruments on the Gemini South telescope. bHROS is a high-resolution (R=150,000) prism cross dispersed echelle spectrograph, situated in the pier of Gemini-South. It is fed by optical fibres mounted on the GMOS

M. F. Blanken; G. Talbot; M. Aderin

2003-01-01

172

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

173

Uncertainty in diffusion tensor based fibre tracking  

Microsoft Academic Search

\\u000a Background. diffusion tensor imaging and related fibre tracking techniques have the potential to identify major white matter tracts\\u000a afflicted by an individual pathology or tracts at risk for a given surgical approach. However, the reliability of these techniques\\u000a is known to be limited by image distortions, image noise, low spatial resolution, and the problem of identifying crossing\\u000a fibres. This paper

H. K. Hahn; J. Klein; C. Nimsky; J. Rexilius; H.-O. Peitgen

174

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

175

A review of flame retardant polypropylene fibres  

Microsoft Academic Search

Flame retardants for polypropylene (PP) and their potential suitability for use in fibre applications are reviewed. Five principal types of generic flame retardant systems for inclusion in polypropylene fibres have been identified as phosphorus-containing, halogen-containing, silicon-containing, metal hydrate and oxide and the more recently developed nanocomposite flame retardant formulations.The most effective to date comprise halogen–antimony and phosphorus–bromine combinations, which while

Sheng Zhang; A. Richard Horrocks

2003-01-01

176

Optical Fibre Sensors 17 (OFS-17)  

Microsoft Academic Search

This special issue of Measurement Science and Technology provides an overview of current developments in the field of optical fibre sensors. The papers presented here are more detailed versions of those presented at the 17th Optical Fibre Sensors conference (OFS-17) held at the Oud St-Jan Art and Congress Centre in Bruges, Belgium, from 23–27 May 2005.The first OFS conference was

Ralph P Tatam; Julian D C Jones

2006-01-01

177

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

178

Simulating Fibre Suspensions: Lagrangian versus Statistical Approach  

NASA Astrophysics Data System (ADS)

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

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

179

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

180

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

PubMed

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

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

2014-01-01

181

Fibre positioning algorithms for the WEAVE spectrograph  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

182

Economics Of Optical Fibre Transmission Systems  

NASA Astrophysics Data System (ADS)

Optical fibre as a telecommunication transmission medium has become one of the most significant developments so far of the digital era. A major contributory factor to the availability of optical fibre transmission systems has been the outstanding progress in the technology of manufacturing high quality glass fibre having relatively low attenuation and broad bandwidths. This and other achievements has enabled manufacturers in the United Kingdom to develop a range of optical fibre cables and transmission equipment for operation over short and long distances at the CCITT recommended digital hierarchical rates of 2, 8, 34 and 140Mbit/s which have been adopted by British Telecom (BT) for modernisation to an all digital transmission network. These optical fibre systems are now becoming increasingly price and performance competitive with conventional technology in many parts of telecommunications networks. In the British Telecom (BT) network the 140Mbit/s optical fibre systems are now economically competitive with equivalent systems on coaxial cable and microwave radio. The economics of 8 and 34Mbit/s systems are not yet sufficiently attractive, compared with 2Mbit/s digital line systems on pair type copper cables, for large scale use in rural and local distribution networks and are presently only justified on cost in and around large cities. As system costs decrease large applications are predicted particularly in support of future high speed data, cable television and visual information services.

Murray, W. J.

1983-08-01

183

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.

2014-04-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

185

Does Optic Nerve Head Surface Topography Change Prior to Loss of Retinal Nerve Fiber Layer Thickness: A Test of the Site of Injury Hypothesis in Experimental Glaucoma  

PubMed Central

Purpose To test the hypothesis that optic nerve head (ONH) deformation manifesting as changes in its mean surface height precedes thinning of the peripapillary retinal nerve fiber layer (RNFL) in experimental glaucoma (EG). Methods 68 rhesus macaque monkeys each had three or more baseline imaging sessions under manometric intraocular pressure (IOP) control to obtain average RNFL thickness (RNFLT) and the ONH surface topography parameter mean position of the disc (MPD). Laser photocoagulation was then applied to the trabecular meshwork of one eye to induce chronic, mild-to-moderate IOP elevation and bi-weekly imaging continued. Event analysis was applied to determine for each parameter when an ‘endpoint’ occurred (signficant change from baseline) for eight different endpoint criteria. Specificity was assessed in the group of 68 fellow control eyes. Classical signal detection theory and survival analysis were used to compare MPD with RNFLT. Results Regardless of the endpoint criterion, endpoints were always more frequent for MPD than for RNFLT. The discriminability index (d’) was 2.7 ± 0.2 for MPD and 1.9 ± 0.2 for RNFLT (p<0.0001). Endpoints were reached by MPD an average of 1-2 months earlier than by RNFLT (p<0.01). At the onset of the first specific, detectable MPD change in EG eyes, there was still no significant change in RNFLT on average (p=0.29) and only 25% of individual eyes exhibited signficant reduction. In contrast, at onset of signficant RNFLT change, MPD had already changed an average of 101 µm from baseline (p<0.0001) and 71% of the individual eyes had exhibited significant change. The magnitude of MPD change was more than could be explained on the basis of axon loss alone. Conclusions This study demonstrates that the average surface height of the ONH changes prior to any detectable loss of average peripapillary RNFL thickness in non-human primate eyes with experimental glaucoma. PMID:24204989

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

2013-01-01

186

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

187

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

PubMed

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

Smith, Caren E; Tucker, Katherine L

2011-06-01

188

Magnesium coated bioresorbable phosphate glass fibres: investigation of the interface between fibre and polyester matrices.  

PubMed

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 Mg(2+) in the human body was deposited via magnetron sputtering onto bioresorbable phosphate glass fibres to obtain roughened fibre surfaces. Fibre surface morphology after coating was observed using scanning electron microscope (SEM). The roughness profile and crystalline texture of the coatings were determined via atomic force microscope (AFM) and X-ray diffraction (XRD) analysis, respectively. The roughness of the coatings was seen to increase from 40 ± 1?nm to 80 ± 1?nm. The mechanical properties (tensile strength and modulus) of fibre with coatings decreased with increased magnesium coating thickness. PMID:24066297

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

2013-01-01

189

OPTICAL FIBRES: Envelope and phase evolution of femtosecond pulses in hollow photonic-crystal fibres  

Microsoft Academic Search

Changes in the envelope and the evolution of the spectral phase and chirp of femtosecond pulses propagating through hollow fibres with a photonic-crystal cladding are experimentally studied. Envelope and phase distortions of ultrashort pulses transmitted through such fibres are shown to be controlled by the detuning of the carrier frequency of laser pulses from the central frequency of the passband

Stanislav O. Konorov; Andrei B. Fedotov; V. I. Beloglazov; N. B. Skibina; Andrei V. Shcherbakov; Aleksei M. Zheltikov

2004-01-01

190

Evolution of organic matter and drainages in wood fibre and coconut fibre substrates  

Microsoft Academic Search

New organic substrates have been introduced in hydroponic culture in order to substitute peat, because is a non-renewable resource, and in less rockwool or perlite due to their problematical recycling. The objective of this work is to evaluate the evolution of two renewable organic substrates, wood fibre (WF) and coconut fibre (CF) throughout one cultivation cycle. Two trials were set

I. Domeńo; N. Irigoyen; J. Muro

2009-01-01

191

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

192

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. PMID:24066297

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

2013-01-01

193

The influence of muscle respiration and glycolysis on surface and intracellular pH in fibres of the rat soleus.  

PubMed Central

Extracellular pH (pHo) and intracellular pH (pHi) of superficial fibres of the rat soleus muscle were measured in vitro using pH-sensitive glass micro-electrodes. The origin of the pH gradient existing between the bulk phase of extracellular solution and the surface of muscle fibres was investigated. The pHo decreased almost linearly over a distance of 285 microns from bulk solution to fibre surface. The magnitude of the bulk-surface pH gradient is greater in the mid region of the muscle than close to the tendon. Decreasing the superfusate velocity increased the magnitude of the pH gradient. Reducing the buffer capacity of the superfusing solution had the same effect. Inhibiting the aerobic metabolism or stimulating it acidified the fibre surface. Inhibiting glycolysis alone, or both aerobic metabolism and glycolysis, alkalinized the fibre surface. Inhibiting the membrane ionic exchange process involved in pHi regulation had no effect on surface pH. Changing the rate of aerobic or anaerobic metabolism quickly modified pHi in most cases. In conclusion the bulk-surface pH gradient seems to result mainly from diffusion of CO2 and lactic acid across an unstirred layer of fluid covering the surface of muscle fibres. PMID:6707968

de Hemptinne, A; Huguenin, F

1984-01-01

194

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

195

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

PubMed Central

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

Hotte, Naomi SC; Deyholos, Michael K

2008-01-01

196

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. PMID:18593690

Roach, Melissa J.; Deyholos, Michael K.

2008-01-01

197

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.

Cheri Tremarco

2011-10-07

198

FIBRE CHANNEL By Robert C Burton, burton@cis.ohio-state.edu  

E-print Network

FIBRE CHANNEL By Robert C Burton, burton@cis.ohio-state.edu Abstract Fibre Channel is the general for networking, storage and data transfer. In general Fibre Channel provides speed, reliability, distance or topology. This is a survey paper on Fibre Channel. Table of Contents Fibre Channel Overviewq Fibre Channel

Jain, Raj

199

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

200

Progress and development in fibre laser technology  

NASA Astrophysics Data System (ADS)

High performance fibre lasers are now well established as an extremely robust and reliable technology enabling a growing and diverse number of demanding industrial and medical and applications. Compared to rival technologies, such as carbon-dioxide (CO II), Lamp/Diode-Pumped Solid-State (L/DPSS) and disk lasers, fibre lasers offer a number of unique characteristics that have resulted in their wide adoption in an increasing number of industrial sectors. In addition to replacing conventional lasers in existing applications, fibre lasers have been very successful in enabling new applications, both factors which explain their increasing market share. In this paper we describe the basic features of fibre lasers, and discuss their generic advantages compared with other laser technologies and consider how these may translate to defence applications. We explain our proprietary cladding-pumping technology (GTWave TM) and the laser architectures we use to implement our commercial products. We present parametric performance data that show the vast range of pulse waveforms that can be produced and discuss some new industrial applications that they have recently enabled. Finally, we reference some of the leading research results for multi-kW continuous-wave (CW) fibre lasers and summarise SPIE's published work in this field.

Horley, Ray; Norman, Stephen; Zervas, Mikhail N.

2007-10-01

201

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

PubMed Central

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

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

2014-01-01

202

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

Microsoft Academic Search

In this work, two of surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR)-based optical fibre sensors have been successfully developed and cross-compared. With one SPR sensor being coated with a thin layer of gold film and the other gold-nanorods (GNRs), forming a LSPR sensor, both sensors are subjected to various refractive index changes. As a result their sensitivities

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

2011-01-01

203

On the topology of chromatin fibres.  

PubMed

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. PMID:24098838

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

2012-10-01

204

Nonlinear optics of fibre event horizons.  

PubMed

The nonlinear interaction of light in an optical fibre can mimic the physics at an event horizon. This analogue arises when a weak probe wave is unable to pass through an intense soliton, despite propagating at a different velocity. To date, these dynamics have been described in the time domain in terms of a soliton-induced refractive index barrier that modifies the velocity of the probe. Here we complete the physical description of fibre-optic event horizons by presenting a full frequency-domain description in terms of cascaded four-wave mixing between discrete single-frequency fields, and experimentally demonstrate signature frequency shifts using continuous wave lasers. Our description is confirmed by the remarkable agreement with experiments performed in the continuum limit, reached using ultrafast lasers. We anticipate that clarifying the description of fibre event horizons will significantly impact on the description of horizon dynamics and soliton interactions in photonics and other systems. PMID:25230247

Webb, Karen E; Erkintalo, Miro; Xu, Yiqing; Broderick, Neil G R; Dudley, John M; Genty, Goėry; Murdoch, Stuart G

2014-01-01

205

MICROSTRUCTURED AIR-SILICA FIBRES: RECENT DEVELOPMENTS IN MODELLING,  

E-print Network

to microstrutured air-silica optical fibres (MOFs) are presented and discussed. Then, the specific propagation properties of MOFs are studied in detail. Characteristics measured on fibres manufactured in our laboratory they are based on Bragg reflection, Bragg fibres also exhibit a strong band- pass filtering behaviour around

Boyer, Edmond

206

Optical fibre amplifiers: physical model and design issues  

Microsoft Academic Search

The development of optical fibre amplifiers has caused an impressive evolution in optical telecommunications systems since the end of the 1980s. The widespread application of active fibre amplifiers requires accurate tools to design and simulate these devices in very different operating conditions. The present work describes some physical aspects of active fibre amplifiers and a numerical model for the analysis

M. Artiglia; P. DI VITA; M. Potenza

1994-01-01

207

Evaluation of a data communication model for switched fibre channel  

Microsoft Academic Search

The ANSI standard fibre channel is emerging as the networking protocol of choice for high bandwidth applications. Fibre channel is an enabling technology because of the tremendous advantages in speed and latency it provides over existing networking technologies. Applications that weren't feasible before are now possible, and more applications that demand similar performance will follow. Fibre channel is the high

Steven Emerson

1995-01-01

208

Evaluation of a data communication model for switched fibre channel  

Microsoft Academic Search

ANSI standard Fibre Channel is emerging as the networking protocol of choice for high bandwidth applications. Fibre Channel is an enabling technology because of the tremendous advantages in speed and latency it provides over existing networking technologies. Applications which weren't feasible before are now possible and more will follow which demand this performance. Fibre Channel is the high performance alternative

S. Emerson

1995-01-01

209

Hybrid yarn for thermoplastic fibre composites Publications Department  

E-print Network

that the hybrid yarn is a thorough and homogenous mixture (on the fibre level) of the two types of fibres. WhenHybrid yarn for thermoplastic fibre composites Publications Department publications Hybrid yarn Texturing of the Hybrid Yarn Materials and Mechanical Properties Press Consolidation of Hybrid Yarn Fabrics

210

Deposition of Electronic and Plasmonic Materials inside Microstructured Optical Fibres  

Microsoft Academic Search

Optical fibres are the transport medium of today's digital information. However, current telecommunications fibre systems require external solid state circuits to generate, amplify, receive, and manipulate the light. The fusion of the two technologies, namely fibre photonics and semiconductor electronics is expected to have a major impact on next generation of optoelectronic devices, exploiting both the guiding capabilities of optical

Adrian Amezcua-Correa; V. Gopalan

211

Fibre-top cantilevers: design, fabrication and applications  

Microsoft Academic Search

Fibre-top cantilevers are a new generation of miniaturized devices obtained by carving tiny mechanical beams directly on the cleaved edge of an optical fibre. The light coupled from the other side of the fibre allows measurements of the position of the cantilever with sub-nanometre accuracy. The monolithic structure of the device, the absence of electronic contacts on the sensing head,

D. Iannuzzi; K. Heeck; M. Slaman; S. de Man; J. H. Rector; H. Schreuders; J. W. Berenschot; V. J. Gadgil; R. G. P. Sanders; M. C. Elwenspoek; S. Deladi

2007-01-01

212

Compressive and torsional behaviour of Kevlar 49 fibre  

Microsoft Academic Search

The mechanical anisotropy of an aromatic polyamide fibre, Kevlar 49, was studied in tension, compression and torsion. A new technique involved applying small and defined compressive strains to filaments by bonding them to one side of a beam which is subsequently bent to compress the fibres. Using scanning electron and optical microscopy, fibres were shown to form regularly-spaced helical kink

S. J. Deteresa; S. R. Allen; R. J. Farris; R. S. Porter

1984-01-01

213

Rheology of pulp fibre suspensions: A critical review  

Microsoft Academic Search

This paper reviews past studies on the measurement of rheological properties of pulp fibre suspensions. Such suspensions are complex fluids important in the manufacture of many pulp-fibre based products, such as communication papers, hygiene products, packaging, as well as other fibre-based materials. Pulp suspensions play a role in other biomass conversion processes as well. This review focuses on key properties

B. Derakhshandeh; R. J. Kerekes; S. G. Hatzikiriakos; C. P. J. Bennington

2011-01-01

214

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

PubMed

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

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

2013-01-01

215

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. PMID:23755181

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

2013-01-01

216

Determination of fibre-resin interface strength in fibre-reinforced plastics using the acoustic emission technique  

Microsoft Academic Search

The acoustic emission (AE) technique has been employed in a new way, to deduce information regarding the level of adhesion and the strength of the bond between fibres and the matrix materials used in composite manufacture using a transverse sample based on fibre bundles. When unidirectional composites of E-glass fibres\\/polyester and Kevlar-49 fibres\\/polyester respectively were subjected to transverse tension, the

E. U. Okoroafor; R. Hill

1995-01-01

217

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

218

Dietary fibre and fibre-rich by-products of food processing: Characterisation, technological functionality and commercial applications: A review  

Microsoft Academic Search

Incidental products derived from the manufacturing or processing of plant based foods: cereals, fruits, vegetables, as well as algae, are sources of abundant dietary fibre. These fibre-rich by-products can fortify foods, increase their dietary fibre content and result in healthy products, low in calories, cholesterol and fat. They may also serve as functional ingredients to improve physical and structural properties

Mohamed Elleuch; Dorothea Bedigian; Olivier Roiseux; Souhail Besbes; Christophe Blecker; Hamadi Attia

2011-01-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

220

Comparative study of WLS fibres for the ATLAS Tile Calorimeter  

NASA Astrophysics Data System (ADS)

The Wave Length Shifting (WLS) fibres are one of the most important components of the ATLAS barrel hadronic tile calorimeter (Tilecal). The fibres collect the hght produced in the injection molded scintillating tiles and transport it to the photomultipliers. Parameters like attenuation length and light yield are important, as well as flexibility and radiation hardness. Comparative results of WLS fibres produced by Bicron, Kuraray and Pol.Hi.Tech are presented. The performance of the fibres BCF91A from Bicron and S048 from Pol.Hi.Tech was significatively improved, but the most performant are still the double clad Y11 fibres from Kuraray.

Gomes, A.; David, M.; Henriques, A.; Maio, A.

1998-02-01

221

Comparative study of WLS fibres for the ATLAS tile calorimeter  

NASA Astrophysics Data System (ADS)

The Wave Length Shifting (WLS) fibres are one of the most important components of the ATLAS barrel hadronic tile calorimeter (Tilecal). The fibres collect the light produced in the injection molded scintillating tiles and transport it to the photomultipliers. Parameters like attenuation length and light yield are important, as well as flexibility and radiation hardness. Comparative results of WLS fibres produced by Bicron, Kuraray and Pol.Hi.Tech are presented. The performance of the fibres BCF91A from Bicron and S048 from Pol.Hi.Tech was significatively improved, but the most performant are still the double clad Y11 fibres from Kuraray.

Gomes, A.; David, M.; Henriques, A.; Maio, A.

1997-02-01

222

Bismuth-doped Mg — Al silicate glasses and fibres  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

223

Micromechanical measurements on biological materials: muscle fibres  

Microsoft Academic Search

Movement often distinguishes living from inanimate matter. Much of current understanding of the molecular mechanism underlying biological movement has developed through the study of the characteristics of isolated muscle fibres. Techniques for handling single muscle cells, and salient results from such investigations are described.

Michael A. Ferenczi

2000-01-01

224

Remote process monitoring using optical fibre sensors  

Microsoft Academic Search

Conventional means of curing thermosetting resins used in advanced fibre reinforced composites involves heating the sample in an oven or autoclave where heat is transferred to the sample through conduction and convection. This conventional method for manufacturing composites involves long processing time. On the other hand, microwave-based processing offers the advantage of a significantly faster processing time where the heating

B. Degamber; G. F. Fernando

2002-01-01

225

NOTE: Radioluminescence of some optical fibres  

Microsoft Academic Search

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

R. Nowotny

2007-01-01

226

WEAVE MOS fibre bundle test plan  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

227

Original article Fibre type differentiation during postnatal  

E-print Network

muscles V HorƔk Institute of Animal Physiology and Genetics, the Czech Academy of Sciences, 27721 UMchov differentiation of 12 skeletal muscles with a different fibre type composi- tion was studied in miniature pigs from 80 d of gestation to 1 year of age. Two fetal myofibre types were distinguished at 100 d

Boyer, Edmond

228

The structure of boron in boron fibres  

NASA Technical Reports Server (NTRS)

The structure of noncrystalline, chemically vapour-deposited boron fibres was investigated by computer modelling the experimentally obtained X-ray diffraction patterns. The diffraction patterns from the models were computed using the Debye scattering equation. The modelling was done utilizing the minimum nearest-neighbour distance, the density of the model, and the broadening and relative intensity of the various peaks as boundary conditions. The results suggest that the fibres consist of a continuous network of randomly oriented regions of local atomic order, about 2 nm in diameter, containing boron atoms arranged in icosahedra. Approximately half of these regions have a tetragonal structure and the remaining half a distorted rhombohedral structure. The model also indicates the presence of many partial icosahedra and loose atoms not associated with any icosahedra. The partial icosahedra and loose atoms indicated in the present model are in agreement with the relaxing sub-units which have been suggested to explain the anelastic behavior of fibre boron and the loosely bound boron atoms which have been postulated to explain the strengthening mechanism in boron fibres during thermal treatment.

Bhardwaj, J.; Krawitz, A. D.

1983-01-01

229

High-intensity fibre laser design for micro-machining applications  

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

230

Development of an electrically tuneable Bragg grating filter in polymer optical fibre operating at 1.55 µm  

NASA Astrophysics Data System (ADS)

We present a thorough study on the development of a polymer optical fibre-based tuneable filter utilizing an intra-core Bragg grating that is electrically tuneable, operating at 1.55 µm. The Bragg grating is made tuneable using a thin-film resistive heater deposited on the surface of the fibre. The polymer fibre was coated via the photochemical deposition of a Pd/Cu metallic layer with the procedure induced by VUV radiation at room temperature. The resulting device, when wavelength tuned via Joule heating, underwent a wavelength shift of 2 nm for a moderate input power of 160 mW, a wavelength to input power coefficient of -13.4 pm mW-1 and time constant of 1.7 s-1. A basic theoretical study verified that for this fibre type one can treat the device as a one-dimensional system. The model was extended to include the effect of input electrical power changes on the refractive index of the fibre and subsequently to changes in the Bragg wavelength of the grating, showing excellent agreement with the experimental measurements.

Kalli, K.; Dobb, H. L.; Webb, D. J.; Carroll, K.; Themistos, C.; Komodromos, M.; Peng, G.-D.; Fang, Q.; Boyd, I. W.

2007-10-01

231

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

PubMed Central

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

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

2013-01-01

232

Astronomical optical frequency comb generation in nonlinear fibres and ring resonators: optimization studies  

NASA Astrophysics Data System (ADS)

We here discuss recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam. Two different platforms (and approaches) are numerically and experimentally investigated targeting medium and low resolution spectrographs at astronomical facilities in which innoFSPEC is currently involved. In the first approach, a frequency comb is generated by propagating two lasers through three nonlinear stages - the first two stages serve for the generation of low-noise ultra-short pulses, while the final stage is a low-dispersion highly-nonlinear fibre where the pulses undergo strong spectral broadening. In our approach, the wavelength of one of the lasers can be tuned allowing the comb line spacing being continuously varied during the calibration procedure - this tuning capability is expected to improve the calibration accuracy since the CCD detector response can be fully scanned. The input power, the dispersion, the nonlinear coefficient, and fibre lengths in the nonlinear stages are defined and optimized by solving the Generalized Nonlinear Schrodinger Equation. Experimentally, we generate the 250GHz line-spacing frequency comb using two narrow linewidth lasers that are adiabatically compressed in a standard fibre first and then in a double-clad Er/Yb doped fibre. The spectral broadening finally takes place in a highly nonlinear fibre resulting in an astro-comb with 250 calibration lines (covering a bandwidth of 500 nm) with good spectral equalization. In the second approach, we aim to generate optical frequency combs in dispersion-optimized silicon nitride ring resonators. A technique for lowering and flattening the chromatic dispersion in silicon nitride waveguides with silica cladding is proposed and demonstrated. By minimizing the waveguide dispersion in the resonator two goals are targeted: enhancing the phase matching for non-linear interactions and producing equally spaced resonances. For this purpose, instead of one cladding layer our design incorporates two layers with appropriate thicknesses. We demonstrate a nearly zero dispersion (with +/- 4 ps/nm-km variation) over the spectral region from 1.4 to 2.3 microns. The techniques reported here should open new avenues for the generation of compact astronomical frequency comb sources on a chip or in nonlinear fibres.

Chavez Boggio, J. M.; Fremberg, T.; Bodenmüller, D.; Wysmolek, M.; Sanyic, H.; Fernando, H.; Neumann, J.; Kracht, D.; Haynes, R.; Roth, M. M.

2012-09-01

233

Modified glass fibre reinforced polymer composites  

NASA Astrophysics Data System (ADS)

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

Cao, Yumei

234

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

235

Comparison of cytotoxicity of man-made vitreous fibres.  

PubMed

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

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

1997-01-01

236

Physicochemical properties of commercial fibres from different sources: A comparative approach  

Microsoft Academic Search

The lower intake of fibre and fibre-containing foods has refocused the food industry on the benefits of incorporating different fibres in the foodstuff. Nowadays, a whole range of fibres are available in the market, but sometimes a good choice becomes complicated due to their varied physico-chemical properties. In order to give some light when selecting fibres, a comparative study regarding

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

2009-01-01

237

Study of the tensile properties of stinging nettle fibres ( Urtica dioica)  

Microsoft Academic Search

Developing new natural fibre composites is the focus of many studies today. Indeed, they are made out of renewable resources and, therefore, have a lower environmental impact in comparison to mineral fibre composites. The mechanical performances of stinging nettle fibres are measured and compared to flax and other lignocellulosic fibres. The stress\\/strain curve of stinging nettle fibres (Urtica dioica) shows

Edwin Bodros; Christophe Baley

2008-01-01

238

Effect of surface modification by bromination and metalation on Kevlar fibre-epoxy adhesion  

Microsoft Academic Search

This research uses metalation, bromination, and grafting to modify the surface of Kevlar fibre. The resulting fibre was characterized with tensile measurement, infrared spectroscopy, intrinsic viscosity, and scanning electron microscopy (SEM). From the SEM micrographs, the surface morphology of the bromine etched Kevlar fibre has a rougher surface than the untreated fibre. Furthermore, the tensile strength of Kevlar fibre decreases

Jeng-Shyong Lin

2002-01-01

239

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

SciTech Connect

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

Grukh, Dmitrii A; Levchenko, A E; Kurkov, Andrei S; Paramonov, Vladimir M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2005-05-31

240

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

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

241

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

PubMed Central

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

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

1988-01-01

242

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

PubMed

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

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

2009-03-30

243

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. PMID:23881131

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

2013-01-01

244

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

245

Chloride fluxes in crab muscle fibres  

PubMed Central

1. Isotopic techniques were used to study the efflux of Cl- from single cannulated muscle fibres of the crab Maia squinado. 2. The efflux of 36Cl- was found to be exponential with steady rate constants ranging from 0·01 to 0·07 min-1. The steady efflux was ca. 1000-2000 pM cm-2 sec-1. The efflux was slightly depressed by K+-free saline and was unaffected by 40 mM-K+ saline and NO3- saline. The influx and efflux of Cl- were presumed independent. 3. The membrane conductance calculated from 36Cl- flux data was consistent with that determined by the method of electrotonic spread for other marine crustacean muscle fibres. Cl- accounted for most of the membrane conductance. PMID:5770889

Richards, C. D.

1969-01-01

246

FOCES - a fibre optics Cassegrain Echelle spectrograph  

Microsoft Academic Search

We have designed and built the echelle spectrograph FOCES fed by 100 mu m optical fibres to be mounted at the Cassegrain focus of either the 2.2 m or the 3.5 m telescope at the Calar Alto Observatory. The spectrograph itself follows a white-pupil design collimated with two off-axis parabolic mirrors. The 15 cm beam leaving the 31.6 lines\\/mm R2

M. J. Pfeiffer; C. Frank; D. Baumueller; K. Fuhrmann; T. Gehren

1998-01-01

247

On the Hausdorff dimension of fibres  

Microsoft Academic Search

It is well known that there are planar sets of Hausdorff dimension greater than 1 which are graphs of functions, i.e., all\\u000a their vertical fibres consist of 1 point. We show this phenomenon does not occur for sets constructed in a certain “regular”\\u000a fashion. Specifically, we consider sets obtained by partitioning a square into 4 subsquares, discarding 1 of them

ITAI BENJAMINI; YUVAL PERESI

1991-01-01

248

Relation Between Macular Retinal Ganglion Cell/Inner Plexiform Layer Thickness and Multifocal Electroretinogram Measures in Experimental Glaucoma  

PubMed Central

Purpose. We investigated relations between macular retinal ganglion cell plus inner plexiform layer (RGC+IPL) thickness and macular retinal function revealed by multifocal electroretinonography (mfERG) in a nonhuman primate model of experimental glaucoma. Methods. Retinal ganglion cell (RGC) structure and function were followed with spectral-domain optical coherence tomography (SD-OCT) and ERGs in five macaques with unilateral experimental glaucoma. Linear regression was used to study correlations in control (Con) and experimental (Exp) eyes between peripapillary retinal nerve fiber layer (RNFL) thickness, macular RGC+IPL thickness, multifocal photopic negative response (mfPhNR) and high-frequency multifocal oscillatory potentials (mfOP) in slow-sequence mfERG, and low-frequency component (mfLFC) in global-flash mfERG. We used ANOVA and paired t-tests to compare glaucoma-related mfERG changes between superior and inferior hemifields, foveal hexagon, inner three rings, and four quadrants of macula. Results. Average macular RGC+IPL and temporal RNFL thickness were strongly correlated (r2 = 0.90, P < 0.001). In hexagon-by-hexagon analysis, all three mfERG measures were correlated (P < 0.001) with RGC+IPL thickness for Con (r2, 0.33–0.51) and Exp eyes (r2, 0.17–0.35). The RGC structural and functional metrics decreased as eccentricity increased. The reduction in amplitude of mfERG measures in Exp eyes relative to Con eyes was proportionally greater, in general, than the relative thinning of RGC+IPL at the same location for eyes in which structural loss was not evident, or mild to moderate. Although not statistically significant, percent amplitude reduction of mfERG measures was greatest in the inferior temporal quadrant. Conclusions. Macular RGC+IPL thickness and mfERG measures of RGC function can be complementary tools in assessing glaucomatous neuropathy. PMID:24970256

Luo, Xunda; Patel, Nimesh B.; Rajagopalan, Lakshmi P.; Harwerth, Ronald S.; Frishman, Laura J.

2014-01-01

249

Bundled capillary electrophoresis using microstructured fibres.  

PubMed

Joule heating, arising from the electric current passing through the capillary, causes many undesired effects in CE that ultimately result in band broadening. The use of narrow-bore capillaries helps to solve this problem as smaller cross-sectional area results in decreased Joule heating and the rate of heat dissipation is increased by the larger surface-to-volume ratio. Issues arising from such small capillaries, such as poor detection sensitivity, low loading capacity and high flow-induced backpressure (complicating capillary loading) can be avoided by using a bundle of small capillaries operating simultaneously that share buffer reservoirs. Microstructured fibres, originally designed as waveguides in the telecommunication industry, are essentially a bundle of parallel ?5??m id channels that extend the length of a fibre having otherwise similar dimensions to conventional CE capillaries. This work presents the use of microstructured fibres for CZE, taking advantage of their relatively high surface-to-volume ratio and the small individual size of each channel to effect highly efficient separations, particularly for dye-labelled peptides. PMID:21254119

Rogers, Benjamin; Gibson, Graham T T; Oleschuk, Richard D

2011-01-01

250

Towards woven logic from organic electronic fibres  

NASA Astrophysics Data System (ADS)

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

Hamedi, Mahiar; Forchheimer, Robert; Inganäs, Olle

2007-05-01

251

Erbium-doped nanoparticles in silica-based optical fibres  

E-print Network

Developing of new rare-earth (RE)-doped optical fibres for power amplifiers and lasers requires continuous improvements in the fibre spectroscopic properties (like shape and width of the gain curve, optical quantum efficiency, resistance to spectral hole burning and photodarkening...). Silica glass as a host material for fibres has proved to be very attractive. However, some potential applications of RE-doped fibres suffer from limitations in terms of spectroscopic properties resulting from clustering or inappropriate local environment when doped into silica. To this aim, we present a new route to modify some spectroscopic properties of RE ions in silica-based fibres based on the incorporation of erbium ions in amorphous dielectric nanoparticles, grown in-situ in fibre preforms. By adding alkaline earth elements, in low concentration into silica, one can obtain a glass with an immiscibility gap. Then, phase separation occurs under an appropriate heat treatment. We investigated the role of three alkaline-earth...

Blanc, Wilfried; Dussardier, Bernard; 10.1504/IJNT.2012.045350

2012-01-01

252

Effects of chemical treatments on hemp fibre structure  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

253

Bismuth-doped Mg - Al silicate glasses and fibres  

SciTech Connect

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

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

2012-09-30

254

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

255

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

256

Compressive and torsional behaviour of Kevlar 49 fibre  

Microsoft Academic Search

The mechanical anisotropy of an aromatic polyamide fibre, Kevlar 49, was studied in tension, compression and torsion. A new\\u000a technique involved applying small and defined compressive strains to filaments by bonding them to one side of a beam which\\u000a is subsequently bent to compress the fibres. Using scanning electron and optical microscopy, fibres were shown to form regularly-spaced\\u000a helical kink

S. J. Deteresa; S. R. Allen; R. J. Farris; R. S. Porter

1984-01-01

257

Surface Enhanced Raman Scattering using Metal Modified Microstructured Optical Fibre Substrates  

Microsoft Academic Search

We report the fabrication of metallic metamaterials using microstructured optical fibres as templates. The resulting fibres serve as excellent substrates for surface enhanced Raman spectroscopy and represent an exciting platform for in-fibre plasmonic devices.

Adrian Amezcua-Correa; Anna C. Peacock; Chris E. Finlayson; Jeremy J. Baumberg; Jixin Yang; Steven M. Howdle; Pier. J. A. Sazio

2006-01-01

258

Passively Q-switched Ytterbium and Chromium all-fibre laser  

E-print Network

A chromium-doped saturable absorber fibre stabilizes an otherwise spontaneously chaotic ytterbium- doped fibre laser. This original passively Q-switched all-fibre laser produces sustained and stable trains of smooth pulses at high repetition rate.

Dussardier, Bernard; Peterka, Pavel

2012-01-01

259

Variability of muscle fibre composition and fibre size in the horse gluteus medius: an enzyme-histochemical and morphometric study.  

PubMed Central

To determine the variability in fibre types and fibre sizes in the equine gluteus medius muscle, biopsy specimens were removed from 5 sites, at 4 different depths, within the right and left muscles of 3 Andalusian stallions. The percentage, lesser fibre diameter and cross-sectional area of the various fibre types were measured systematically in myosin ATPase and NADH-tetrazolium reductase-stained, serial cryostat sections of these multiple samples. Significant differences in muscle fibre type composition were recorded, with a lower percentage of type I fibres (high myosin ATPase activity at pH 4.5) being observed towards superficial regions of the muscle and a greater percentage towards the deep areas. Type II B fibres (moderate myosin ATPase activity at pH 4.5), including both II B nonoxidative (low NADH-TR activity) and II B oxidative (moderate NADH-TR activity), displayed the opposite tendency, and the percentage of type II A fibres (low myosin ATPase activity at pH 4.5) did not change with depth. Types I and II A fibres in the deep regions were larger than superficially, whereas the II B fibres in the deep regions were smaller than in the superficial parts of the muscle. The results also imply that type I fibres tend to be larger than type II fibres in the deep regions. The size of type I fibres is more homogeneous in the deep parts than in the superficial regions of the muscle, while II B fibres vary more in size in the peripheral portions than in deep regions. A single biopsy taken from the gluteus medius muscle of the horse is therefore a poor representative of the whole muscle and care should be exercised in sampling and interpreting data obtained from limited biopsy of this muscle. The pattern of variation in fibre types and fibre sizes between the different depths of the muscle probably reflect different functional demands on the gluteus medius muscle. Images Fig. 1 PMID:1284127

López-Rivero, J L; Serrano, A L; Diz, A M; Galisteo, A M

1992-01-01

260

FIBRE OPTICS: Waveguiding properties and the spectrum of modes of hollow-core photonic-crystal fibres  

NASA Astrophysics Data System (ADS)

Glass fibres with a hollow core and a two-dimensionally periodic cladding are studied experimentally and theoretically. The spectrum of modes guided in the hollow core of these fibres displays isolated maxima, indicating that waveguiding is supported due to the high reflectivity of the fibre cladding within photonic band gaps. The main properties of the spectrum of modes guided in a hollow core of a photonic-crystal fibre and radiation intensity distribution in these modes are qualitatively explained in terms of the model of a periodic coaxial waveguide.

Fedotov, Andrei B.; Konorov, Stanislav O.; Kolevatova, O. A.; Beloglazov, V. I.; Skibina, N. B.; Mel'nikov, L. A.; Shcherbakov, Andrei V.; Zheltikov, Aleksei M.

2003-03-01

261

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

262

Design of single-mode large-mode area bandgap fibre with microstructured-core  

NASA Astrophysics Data System (ADS)

Tailoring the modal characteristics of all-solid photonic bandgap fibre by the inclusion of low-index rods in the fibre core is investigated. By lowering the core index of the fibre, the high-order modes in the fibre can be shifted to the border of the bandgap, as a result, single-mode operation in large-mode area bandgap fibre can be realized without bending the fibre. In addition, large-mode area and single-mode operation in the all-solid microstructured-core bandgap fibre can be achieved by bending the fibre at a wide bending radius range.

Chen, Ming-Yang; Gong, Tian-Yi; Gao, Yong-Feng; Zhou, Jun

2014-11-01

263

Ultrasound detection of damage in complex carbon fibre/metal structures  

NASA Astrophysics Data System (ADS)

We describe work carried out to monitor the structural health of a complex structure comprising both carbon fibre and metal components using ultrasound techniques. The work is designed to be used in a high performance car, but could find applications in other areas such as the aerospace industry. There are two different types of potential problem that need to be examined; the first is damage (e.g. holes, delaminations) to carbon fibre structure, and the second is damage to joints either between two carbon fibre components or between a carbon fibre component and a metallic one. The techniques used are based around the use of PZT transducers for both the generation and detection of ultrasonic Lamb waves. To date we have been carrying out experiments on mock-up samples, but are due to conduct tests on an actual vehicle. Lamb waves propagate in modes whose order is determined by the frequency thickness product. Their properties, such as phase and amplitude can be modified by the presence of damage, such as holes and delaminations. If we record the response of a healthy structure, we can then compare it with signals obtained on subsequent occasions to determine if any significant change has taken place. It is essential, however, to be able to differentiate between the effects of damage and those of environmental changes such as temperature. For this reason we have monitored the response of a sample at different temperatures both before and after drilling a hole in it to simulate damage. Depending on the positions of the transducers with respect to the damaged area, it is possible to detect either attenuation of the entire signal or changes in a specific portion of the signal produced by reflections. Results from these experiments will be presented at the conference. Signal processing techniques for separating damage from the effects of temperature will also be discussed. We also look at the deterioration of joints, which can either be epoxy bonded (carbon fibre to carbon fibre) or bolted together (carbon fibre to aluminium). In the case of the bonded structures we are looking at the effects of failure of the bond layer, whilst in the case of the bolted samples we are looking at loosening of the bolts. The debonding was simulated by joining together a flat plate of carbon fibre composite with an L-shaped carbon fibre piece using a couplant such as grease. Similar experiments were carried out using an aluminium anglebar bolted to the plate, with the bolts both tightened and loose. Signals of both the transmitted wave in the plate and the power coupled to the L piece were measured before and after debonding. This gives a more reliable measure of the change in power transfer between the two components as the joint/bond degrades. It was found that in order to get maximum coupling to the second component the frequency of the acoustic wave had to be altered. This is because in the bonding region the combined thickness of the components alters the modal propagation characteristics of the structure compared with those of the single component region.

Thursby, G. J.; MacLean, A.; Hogg, H.; Culshaw, B.

2006-03-01

264

The magnetic properties of aligned M hexa-ferrite fibres  

NASA Astrophysics Data System (ADS)

Aligned and random fibres of strontium hexaferrite (SrM, SrFe 12O 19) and barium hexaferrite (BaM, BaFe 12O 19) were manufactured by blow spinning from an aqueous inorganic sol-gel precursor, which was then fired to give the hexagonal ferrite fibre. Their magnetic properties were studied by VSM, investigating the evolution of these properties with firing and measurement temperature, and in particular the effects of fibre alignment. It has been predicted that aligned ferrite fibres will demonstrate an enhanced magnetisation along the axis of alignment with respect to perpendicular to the axis, and this has been demonstrated here for the first time. The optimum firing temperature was 1000 °C, at which point they still had submicron grains. In BaM random fibres Ms=63.8 emu g -1 and Hc=428.1 kA m -1, and in SrM random fibres Ms=63.3 emu g -1 and Hc=452.8 kA m -1, high values for polycrystalline materials. Fibres aligned parallel to the applied field had saturation magnetisation ( Ms) values equal to those of the random fibres, whilst fibres aligned perpendicular to the field had Ms values 62% and 75% lower, for BaM and SrM, respectively. There was no change in coercivity ( Hc) between random or aligned fibres of any orientation, and fibres aligned 45° and parallel to H appeared identical. Therefore, properties along the axis of alignment were superior when compared to measurements perpendicular to the axis of alignment, giving a directionality to the magnetisation in an otherwise randomly oriented ferrite material.

Pullar, R. C.; Bhattacharya, A. K.

2006-05-01

265

Thermal conductivity of CVD diamond fibres and diamond fibre-reinforced epoxy composites  

E-print Network

deposition (CVD) with tungsten wire of varying diameters as the cores. A steady-state technique was used. The room temperature thermal conductivity of the fibres ranged between 750 and 1088 W mĆ?1 KĆ?1 lengthwise heat transfer with low heat transfer to the surroundings, as well as high electrical insulation

Bristol, University of

266

Fifth Russian Workshop on Fibre Lasers  

NASA Astrophysics Data System (ADS)

The Fifth Russian Workshop on Fibre Lasers was held in Akademgorodok, Novosibirsk, Russia on 27 — 30 March 2012. The idea to organise the workshop emerged in summer 2006 during an English-speaking conference held in Russia, where most participants were Russians. After a session where a Russian-speaking scientist reported his achievements to other Russian-speaking scientists in broken English, a group of attendees came up with the idea to launch a scientific workshop in Russian. That group included S. Turitsyn (Aston University, UK), S. Kobtsev (Novosibirsk State University, Novosibirsk), S. Babin [Institute of Automation and Electrometry, Siberian Branch (SB), Russian Academy of Sciences (RAS), Novosibirsk], and me.

Kurkov, Andrei S.

2012-09-01

267

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

268

Analysis and measurement of modal noise in an optical fibre  

Microsoft Academic Search

Modal noise in analogue and digital optical fibre systems has been demonstrated to be a significant effect. In this letter, we give some theoretical and experimental results concerning the behavior of the signal-to-noise ratio in presence of modal noise considering the power from the exit face of a short sample of a graded-index multimode optical fibre.

B. Daino; G. de Marchis; S. Piazzolla

1979-01-01

269

Speckle and Modal Noise in Optical Fibres Theory and Experiment  

Microsoft Academic Search

Modal noise has been observed in optical fibres excited by partially coherent sources. In this paper the theory of this noise is presented. Following the basic guidelines of the speckle theory, the statistical properties of the fluctuations of the power transmitted through a circular aperture of arbitrary size are evaluated. It is found that, for fibres having an ? -exponent

B. Daino; G. de Marchis; S. Piazzolla

1980-01-01

270

Bamboo and wood fibre cement composites for sustainable infrastructure regeneration  

Microsoft Academic Search

This paper describes the development of eco-friendly bamboo and wood fibre cement composites from agriculture wastes for applications in the housing and building industries, and for sustainable infrastructure regeneration. Bamboo flakes and fibres from oil palm tree fronds were produced and tested for their sugar content and effect on the setting and strength development of the portland cement matrix. To

Rahim Sudin; Narayan Swamy

2006-01-01

271

Muscle fibre loss and reinnervation after long-term denervation  

Microsoft Academic Search

Summary Cutaneus pectoris muscles of frog (Rana temporaria) were investigated 19.5–40 months after denervation. On whole mounts a heavy reduction in size and number of muscle fibres is noticed; in two muscles studied with semithin and ultrathin sections the number of remaining muscle fibres is 149 and around 120, while one of the contralateral muscles contains 250 and control muscles

A. P. Anzil; A. Wernig

1989-01-01

272

Distributed feedback photonic crystal fibre (DFB-PCF) laser.  

PubMed

A distributed feedback laser is fabricated in Er3+-doped photonic crystal fibre. Preferential single-mode lasing is obtained with no special consideration of polarisation issues. The results demonstrate practical implementation of a multi-photon writing process for complex structures in these optical fibres. No hydrogen loading and no germanium are involved. PMID:19495188

Groothoff, Nathaniel; Canning, John; Ryan, Tom; Lyytikainen, Katja; Inglis, Hugh

2005-04-18

273

Upgrading existing optical fibre plants to higher bit-rates  

Microsoft Academic Search

To upgrade existing conventional fibre lines to very high data rates, effective methods of coping with the chromatic dispersion problem are therefore needed. Several techniques for the compensation of chromatic dispersion have been suggested so far. They include the use of externally modulated chirp-free transmitters, pre-chirping techniques of the transmitter laser, dispersion supported transmission, midpoint spectral inversion, dispersion compensating fibres,

M. Artiglia; E. Ciaramella; F. Cisternino; P. Di Vita; R. Girardi; A. Pagano; B. Sordo

1996-01-01

274

Laboratory and telescope experiences with long optical fibre links  

Microsoft Academic Search

The installation at the (Coudé Echelle Spectrograph) of the new Short Camera coupled with an efficient CCD detector and the improvements on the spectral transmission of the commercially available fibres prompted a new experiment. The link was established between the Cassegrain focus of the 3.6 m and the CES. A change of fibres to take into account variable seeing conditions

G. Avila; S. D'Odorico

1988-01-01

275

Alternative designs for high power single mode active optical fibres  

Microsoft Academic Search

In this paper, we propose, through different theoretical examples of composite fibre designs, some alternative ways to push up the limits of active optical fibres. Highly ytterbium-doped large cores are required for high power delivery and low non linear limitations. Such cores usually support several guided modes. We demonstrate in this paper that by surrounding the core with a tailored

P. Roy; M. Devautour; S. Fevrier; L. Lavoute; K. Schuster; J. Kobelke; S. Grimm

2009-01-01

276

Measuring unsteady axial velocity of fibres and threads  

Microsoft Academic Search

To measure – in fact even sense – axial motions of fibres and threads is difficult. Especially synthetic fibres may lack any distinguishable features on their surface, so that they seem to be motionless and optical sensing fails. The motion may be transferred by friction to a mechanical component (e.g., a pulley) the speed of which is measured, but this

V. Tesa?

2009-01-01

277

An Analysis of Algorithms for In Vivo Fibre Tractography  

Microsoft Academic Search

Diffusion tensor imaging (DTI) is a relatively new imaging technique which is used to measure the water diffusion in the brain. Since water diffusion is influenced by the micro-structure of tissue DTI can be used to identify nerve fibre tracts in the brain. Over recent years many fibre tracking techniques have been proposed, but little work has been done to

Jing Li; Burkhard C. Wunsche

278

Digestion Modelling in the Small Intestine : Impact of Dietary Fibre  

E-print Network

Digestion Modelling in the Small Intestine : Impact of Dietary Fibre M. Taghipoor , G. Barles , C. Georgelin , J.R. Licois & Ph. Lescoat Abstract In this work, we continue the modelling of the digestion the role of dietary fibre on digestion, we model their two principal physiochemical characteristics which

Paris-Sud XI, UniversitƩ de

279

Singlet oxygen luminescence detection with a fibre-coupled superconducting  

E-print Network

Singlet oxygen luminescence detection with a fibre-coupled superconducting nanowire single Triplet State Singlet State 1O2 Ground State Oxygen 3O2 Singlet oxygen Free space singlet oxygen luminescence detection Fibre-based singlet oxygen luminescence detection References Superconducting Detector

Greenaway, Alan

280

The mechanical and thermal properties of frog slow muscle fibres  

PubMed Central

1. A study has been made of the mechanical behaviour and the heat production of frog slow muscle fibres in iliofibularis nerve—muscle preparations at 20° C. 2. The slow fibre isometric tension and its rate of development increase with stimulation frequency, the increases beyond 30 Hz being relatively small. Relaxation rate also increases with stimulation frequency. The tension—length curve and maximum isometric tension (250 mN.mm-2) are similar to those of twitch fibres. The maximum shortening velocity is estimated to be 0·11 tonus bundle lengths per second. 3. For contractions up to 60 sec at 30-50 Hz the slow fibre heat rate is steady at 6 mJ.g-1.sec-1. Slow fibres produce aerobic recovery heat with a time course similar to that of twitch fibres. 4. The accuracy of the results is discussed, and a comparison is made with the properties of twitch fibres. It is concluded that the tension-producing reactions are thirty times slower in the slow fibres. PMID:5551404

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

1971-01-01

281

Damping analysis of unidirectional glass and Kevlar fibre composites  

Microsoft Academic Search

The paper presents an extensive analysis of the damping of unidirectional fibre composites as function of frequency and fibre orientation. Damping of glass and Kevlar composites is analysed experimentally using a cantilever beam test specimen and an impulse technique. Damping parameters are derived by fitting the experimental Fourier responses with the analytical motion responses. The experimental results are compared with

Jean-Marie Berthelot; Youssef Sefrani

2004-01-01

282

Fibre operating lengths of human lower limb muscles during walking  

PubMed Central

Muscles actuate movement by generating forces. The forces generated by muscles are highly dependent on their fibre lengths, yet it is difficult to measure the lengths over which muscle fibres operate during movement. We combined experimental measurements of joint angles and muscle activation patterns during walking with a musculoskeletal model that captures the relationships between muscle fibre lengths, joint angles and muscle activations for muscles of the lower limb. We used this musculoskeletal model to produce a simulation of muscle–tendon dynamics during walking and calculated fibre operating lengths (i.e. the length of muscle fibres relative to their optimal fibre length) for 17 lower limb muscles. Our results indicate that when musculotendon compliance is low, the muscle fibre operating length is determined predominantly by the joint angles and muscle moment arms. If musculotendon compliance is high, muscle fibre operating length is more dependent on activation level and force–length–velocity effects. We found that muscles operate on multiple limbs of the force–length curve (i.e. ascending, plateau and descending limbs) during the gait cycle, but are active within a smaller portion of their total operating range. PMID:21502124

Arnold, Edith M.; Delp, Scott L.

2011-01-01

283

A fibre optic chemical sensor for the detection of cocaine  

Microsoft Academic Search

A fibre-optic chemical sensor for the detection of cocaine has been developed, based on a molecularly imprinted polymer (MIP) containing a fluorescein moiety as the signalling group. The fluorescent MIP was formed and covalently attached to the distal end of an optical fibre. The sensor exhibited an increase in fluorescence intensity in response to cocaine in the concentration range of

T. Hien Nguyen; Tong Sun; Kenneth T. V. Grattan; S. A. Hardwick

2010-01-01

284

The polypeptide components of the parasporal fibres of Pasteuria penetrans  

Microsoft Academic Search

A variety of treatments were tested for their ability to solubilize the parasporal fibres from Pasteuria penetrans, a parasite of some plant–parasitic nematodes. Selective solubilization of the parasporal fibres resulted from some of the extraction procedures tested. Subsequent acrylamide gel electrophoresis and Western blotting of the resolved polypeptides, using polyclonal sera against the spores, disclosed up to 15 distinct bands,

Alka Vaid; Alistair H. Bishop; Keith G. Davies

2002-01-01

285

Numerical simulation of incoherent optical wave propagation in nonlinear fibres  

E-print Network

laser, a master oscillator coupled with fibre amplifier, usually a cladding-pumped high-power amplifier RƩsumƩ The present work concerns the study of pulsed laser systems containing a fibre amplifier depending on the characteristics of the optical source emitted by the master laser. However, it has not been

Boyer, Edmond

286

Improving the Radial Dopant Distribution in Silica Optical Fibres  

E-print Network

of fabrication parameters (i.e., surface adsorption, solution concentration, soot density, etc), is still a majorImproving the Radial Dopant Distribution in Silica Optical Fibres Fotios Sidiroglou1 , Wilfried and solution doping techniques is presented. Keywords-component; Fibre Frabrication; MCVD; Erbium Doped Optical

Paris-Sud XI, UniversitƩ de

287

Viscoelasticity of Kevlar 49 fibres Ioannis P. GIANNOPOULOS1  

E-print Network

1 Viscoelasticity of Kevlar 49 fibres Ioannis P. GIANNOPOULOS1 , Chris J. BURGOYNE2 Key words: Viscoelasticity, creep, creep compliance, Kevlar 49 ABSTRACT: Aramid fibres are being considered for use in many Breaking Load) for a long period of time. The results indicate that Kevlar 49 yarns show a non

Burgoyne, Chris

288

A Scintillating Fibre Tracker for the LHCb Upgrade  

NASA Astrophysics Data System (ADS)

A scintillating fibre tracker with multichannel silicon photomultiplier readout is an option for the LHCb upgrade. The radiation hardness of the scintillating fibres and silicon photomultipliers has been studied. Production methods and machines to build 5m long modules with an accuracy of 50 ?m have been designed and built. All developments are well on track for the technical design report in March 2014.

Ekelhof, Robert

2014-06-01

289

Concrete Cylinders Confined with Basalt Fibre Reinforced Polymer Eythor Thorhallsson  

E-print Network

1 Concrete Cylinders Confined with Basalt Fibre Reinforced Polymer Eythor Thorhallsson M that was done on concrete cylinders confined with basalt fibre reinforced polymer (BFRP) and examination of its of more ductile behaviour. Key words: Concrete, confinement, basalt, BFRP and strengthening. 1

Karlsson, Brynjar

290

Structure investigation of lyocell fibres by in situ USANS measurements  

NASA Astrophysics Data System (ADS)

Lyocell fibres nowadays are widely used in textile production and have an enormous potential for various technical applications. The structure of these fibres, however, is a pending research issue. Particularly, the process of fibrillation is still to be understood and a major issue for the optimisation of the production process. Now, first experiments with neutrons using USANS technique have revealed indications about the fibre structure in the micrometer range. We observed clear ultra-small-angle scattering patterns from even small numbers of fibres after spinning and even from inside the spinning bath during the spinning process. The outer diameter of the fibres is well reproduced in the scattering patterns which also indicate the presence of smaller internal structure. First experimental results obtained at the S18 instrument at the ILL are presented.

Jericha, E.; Villa, M.; Baron, M.; Loidl, R.; Biganska, O.; Navard, P.; Patlazhan, S.; Aldred, P.; Rüf, H.; Schuster, K. C.

2004-07-01

291

Glaucoma Diagnostic Accuracy of Machine Learning Classifiers Using Retinal Nerve Fiber Layer and Optic Nerve Data from SD-OCT  

PubMed Central

Purpose. To investigate the diagnostic accuracy of machine learning classifiers (MLCs) using retinal nerve fiber layer (RNFL) and optic nerve (ON) parameters obtained with spectral domain optical coherence tomography (SD-OCT). Methods. Fifty-seven patients with early to moderate primary open angle glaucoma and 46 healthy patients were recruited. All 103 patients underwent a complete ophthalmological examination, achromatic standard automated perimetry, and imaging with SD-OCT. Receiver operating characteristic (ROC) curves were built for RNFL and ON parameters. Ten MLCs were tested. Areas under ROC curves (aROCs) obtained for each SD-OCT parameter and MLC were compared. Results. The mean age was 56.5 ± 8.9 years for healthy individuals and 59.9 ± 9.0 years for glaucoma patients (P = 0.054). Mean deviation values were ?1.4?dB for healthy individuals and ?4.0?dB for glaucoma patients (P < 0.001). SD-OCT parameters with the greatest aROCs were cup/disc area ratio (0.846) and average cup/disc (0.843). aROCs obtained with classifiers varied from 0.687 (CTREE) to 0.877 (RAN). The aROC obtained with RAN (0.877) was not significantly different from the aROC obtained with the best single SD-OCT parameter (0.846) (P = 0.542). Conclusion. MLCs showed good accuracy but did not improve the sensitivity and specificity of SD-OCT for the diagnosis of glaucoma. PMID:24369495

Barella, Kleyton Arlindo; Costa, Vital Paulino; Gonēalves Vidotti, Vanessa; Silva, Fabrķcio Reis; Dias, Marcelo; Gomi, Edson Satoshi

2013-01-01

292

Determining the fibrillar orientation of bast fibres with polarized light microscopy: the modified Herzog test (red plate test) explained  

PubMed Central

The identification of bast fibre samples, in particular, bast fibres used in textiles, is an important issue in archaeology, criminology and other scientific fields. One of the characteristic features of bast fibres is their fibrillar orientation, referred to as Z- or S twist (or alternatively right- and left-handed fibres). An empirical test for determining the fibrillar orientation using polarized light microscopy has been known in the community for many years. It is referred to as the modified Herzog test or red plate test. The test has the reputation for never producing false results, but also for occasionally not working. However, so far, no proper justification has been provided in the literature that the ‘no false results’ assumption is really correct and it has also not been clear up till now, why the method sometimes does not work. In this paper, we present an analytical model for the modified Herzog test, which explains why the test never gives a false result. We also provide an explanation for why the Herzog test sometimes does not work: According to our model, the Herzog test will not work if none of the three distinct layers in the secondary cell wall is significantly thicker than the others. PMID:24020614

HAUGAN, E; HOLST, B

2013-01-01

293

High altitude tissue adaptation in Andean coots: capillarity, fibre area, fibre type and enzymatic activities of skeletal muscle  

Microsoft Academic Search

Capillarity, fibre types, fibre area and enzyme activities of different skeletal muscles (pectoralis, extensor digitorum longus), tibialis anterior, plantaris and the myocardium were compared in Andean coot (Fulica americana peruviana) native to high altitude (Junķn, Perś, 4200 m) and the same species nesting at sea level. Numbers of capillaries per square millimeter were higher in all high-altitude muscles when compared

F. León-Velarde; J. Sanchez; A. X. Bigard; A. Brunet; C. Lesty; C. Monge-C

1993-01-01

294

JOURNAL OF MATERIALS SCIENCE 31 (1996) 2801 2805 Laser ablation of diamond fibres and a diamond fibre  

E-print Network

modulus values for natural or synthetic diamond grit are greater than those of any other material [1JOURNAL OF MATERIALS SCIENCE 31 (1996) 2801 2805 Laser ablation of diamond fibres and a diamond Research Agency Farnborough, GU14 6TD, UK Continuous chemical vapour-deposited diamond-coated fibres

Bristol, University of

295

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

296

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

297

Synthesis and characterization of copper, polyimide and TIPS-pentacene layers for the development of a solution processed fibrous transistor  

Microsoft Academic Search

A study was performed for the development of a flexible organic field effect transistor starting from a polyester fibre as substrate material. Focus of subsequent layer deposition was on low temperature soluble processes to allow upscaling. Gate layer consists out of a pyrrole polymerization and copper coating step. Polyimide dielectric layer was deposited using dipcoating. Gold electrodes were vacuum evaporated

B. Van Genabet; A. Schwarz; E. Bruneel; L. Rambausek; I. Van Driessche; L. Van Langenhove

2011-01-01

298

Spiders spinning electrically charged nano-fibres.  

PubMed

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

Kronenberger, Katrin; Vollrath, Fritz

2015-01-01

299

High altitude tissue adaptation in Andean coots: capillarity, fibre area, fibre type and enzymatic activities of skeletal muscle.  

PubMed

Capillarity, fibre types, fibre area and enzyme activities of different skeletal muscles (pectoralis, extensor digitorum longus), tibialis anterior, plantaris and the myocardium) were compared in Andean coot (Fulica americana peruviana) native to high altitude (Junķn, Perś, 4200 m) and the same species nesting at sea level. Numbers of capillaries per square millimeter were higher in all high-altitude muscles when compared with sea-level muscles (P < 0.0001). Moreover, values for capillaries per fibre and capillaries in contact with each fibre were higher in digitorum and tibialis high-altitude muscles. Muscle fibres were classified as Type I, Type IIA or Type IIB on the basis of their myofibrillar ATPase pH lability. Pectoralis muscle of high-altitude and sea-level coots presented only fibres of Type IIA. In contrast, all the leg muscles studied showed a mosaic pattern of the three fibre types. Fibre areas were determined using a Leitz Texture Analysis System. Significant differences in fibre area were observed (P < 0.01) between high-altitude and sea-level muscles. Mean muscle fibre diameters were also lower in the high-altitude group than in the sea-level group. The enzyme activities studied were hexokinase, lactate dehydrogenase, citrate synthase and 3-hydroxyacyl-CoA-dehydrogenase. The oxidative capacity, as reflected by citrate synthetase and hydroxyacyl-CoA-dehydrogenase activities, was greater for myocardial and pectoralis than for leg muscles. However, analysis of maximal enzyme activities showed that there were no significant differences between the glycolytic and oxidative enzyme activities of high-altitude and sea-level coots.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8459054

León-Velarde, F; Sanchez, J; Bigard, A X; Brunet, A; Lesty, C; Monge, C

1993-01-01

300

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

301

Development of a Brillouin scattering based distributed fibre optic strain sensor  

Microsoft Academic Search

The parameters of the Brillouin spectrum of an optical fibre depend upon the strain and temperature conditions of the fibre. As a result, fibre optic distributed sensors based on Brillouin scattering can measure strain and temperature in arbitrary regions of a sensing fibre. In the past, such sensors have often been demonstrated under laboratory conditions, demonstrating the principle of operation.

Anthony Wayne Brown

2001-01-01

302

Synthetic and steel fibres in concrete with regard to equal toughness  

Microsoft Academic Search

Purpose – Establishing toughness performance in concrete using steel fibres is well understood, and design guides are available to assist with this process. What is less readily understood is the use of Type 2 synthetic fibres to provide toughness. This problem is exacerbated by the wide range of synthetic fibres available, with each different fibre providing different structural properties. This

A. E. Richardson; K. Coventry; S. Landless

2010-01-01

303

Man-made fibre spinning in liquors of dissimilar precipitation power  

Microsoft Academic Search

Published material relating to the mechanism of spinning fibres by the wer method deals, with few exceptions, with fibres whiah undergo preliminary orientation. Deformation produces significant changes in the original structure of the fibre so that the results are not always reliable. In this article, which is largely an attempt to develop S. P. Papkov's approach to man-made fibre spinning

O. I. Nachinkin

1976-01-01

304

Bioactive evaluation of 45S5 bioactive glass fibres and preliminary study of human osteoblast attachment  

Microsoft Academic Search

Bioactive glass fibres can be used as tissue engineering scaffolds. In this investigation, the bioactive response of 45S5 glass fibres was assessed in simulated body fluid (SBF). Preliminary attachment of osteoblasts to the fibre surface was assessed, as were the fibre tensile strength and fracture toughness. Fourier transform infrared spectroscopy (FTIR) analysis revealed that hydroxyapatite (HA) was formed on the

Daniel C. Clupper; Julie E. Gough; Papy M. Embanga; Ioan Notingher; Larry L. Hench; Matthew M. Hall

2004-01-01

305

Microstructural cumulative material degradation and fatigue-failure micromechanisms in wood-pulp fibres  

Microsoft Academic Search

This paper establishes the fundamental micro-mechanisms associated with the conversion of single wood pulp fibres into fibres suitable for the production of paper. It deals with an examination of the morphological and structural changes taking place in pulp fibres being subjected to cyclic mechanical actions that are representative of those experienced by fibres in mechanical refiners. Implementing the experimental procedure

Wadood Y. Hamad; James W. Provan

1995-01-01

306

Texture dependence of the Rayleigh instability in discotic mesophase fibres  

NASA Astrophysics Data System (ADS)

Classical theories of liquid crystalline (LC) materials are used to develop a new model that describes the effect of texture on the Rayleigh instability of discotic mesophase cylindrical fibres; these LC fibres arise in the fabrication of carbon fibres by melt spinning of mesophase precursors. The thermodynamic model identifies the new contributions to elastic storage due to the liquid crystal orientational order present in discotic mesophase fibres. The two classical radial and onion textures found in discotic fibres are associated with pure splay 0965-0393/7/2/001/img1 and bend 0965-0393/7/2/001/img2 elastic modes, respectively. It is found that the radial texture always promotes the Rayleigh fibre instability because droplet formation decreases the bend energy. On the other hand the onion texture contains two competing elastic modes: the splay mode is stabilizing and the bend mode is destabilizing. The net effect on the fragmentation of the onion texture fibre into an array of droplets thus depends on the elastic anisotropy 0965-0393/7/2/001/img3 of the mesophase. Surprisingly, when the weighted elastic ratio is equal to one, the Rayleigh instability criteria hold.

Rey, Alejandro D.

1999-03-01

307

Can supplementary dietary fibre suppress breast cancer growth?  

PubMed Central

Case-control studies in diverse populations around the world have reported a lower risk of breast cancer in association with higher intake of dietary fibre and complex carbohydrates. Although this has not been confirmed in prospective studies in the USA, the observations have prompted the hypothesis that prolonged use of dietary fibre supplements might reduce breast cancer risk in high-incidence populations. Several possible mechanisms of action have been suggested, all involving a reduction of bioactive oestrogen levels in the blood. The various mechanisms are not necessarily mutually exclusive. First, a high-fibre diet might reduce circulating oestrogen levels by reducing the enterohepatic recirculation of oestrogen. Second, many plants and vegetables contain isoflavones and lignans capable of conversion in the bowel into weak oestrogens that may compete with oestradiol for target binding-sites. Third, a high-fibre diet is less often associated with obesity, which tends to increase availability of the biologically active 16-alpha metabolites of oestrone. Fourth, a high-fibre diet usually has a lower content of fat and a higher content of antioxidant vitamins, which may protect against breast cancer risk. Finally, diets rich in fibre and complex carbohydrates have been shown to improve insulin sensitivity, with an associated reduction in circulating oestrogen levels. Synergism between these effects offers a possible mechanism by which a high fibre intake might suppress breast cancer growth in women. PMID:8605086

Stoll, B. A.

1996-01-01

308

NANO REVIEW Open Access Cellulose fibres, nanofibrils and microfibrils: The  

E-print Network

morphological sequence of MFC components from a plant physiology and fibre technology point of view Gary Chinga-Carrasco During the last decade, major efforts have been made to develop adequate and commercially viable processes for disintegrating cellulose fibres into their structural components. Homogenisation of cellulose fibres has been one of the principal applied procedures. Homogenisation has produced materials which may be inhomogeneous, containing fibres, fibres fragments, fibrillar fines and nanofibrils. The material has been denominated microfibrillated cellulose (MFC). In addition, terms relating to the nano-scale have been given to the MFC material. Several modern and high-tech nano-applications have been envisaged for MFC. However, is MFC a nano-structure? It is concluded that MFC materials may be composed of (1) nanofibrils, (2) fibrillar fines, (3) fibre fragments and (4) fibres. This implies that MFC is not necessarily synonymous with nanofibrils, microfibrils or any other cellulose nano-structure. However, properly produced MFC materials contain nano-structures as a main component, i.e. nanofibrils. Review

unknown authors

309

Interference of dietary fibres with gastrointestinal enzymes in vitro.  

PubMed

Dietary fibres (Plantago ovata seeds, P. ovata husks, wheat bran, alfalfa, pectin, xylan) were incubated in vitro with gastrointestinal enzymes (pepsin, trypsin, chymotrypsin, lipase, alpha-amylase, maltase, lactase) in buffer solutions at concentrations of 1-5% for 10-30 min at 37 degrees C. All fibres induced sometimes pronounced changes in enzyme activity, but the effect of the different fibres on the various enzymes varied individually and was not predictable. Both P. ovata preparations had no (pepsin, trypsin, alpha-amylase) or only stimulating (chymotrypsin, lipase, lactase) actions whereas all other fibres showed inhibiting as well as stimulating influences. Wheat bran induced the most pronounced alterations increasing lipase, maltase and lactase activity and inhibiting alpha-amylase activity. Pectin and xylan were comparable in decreasing lipase and pepsin activity and in increasing chymotrypsin activity but had opposite effects on maltase activity. Alfalfa was able to stimulate lactase and lipase activity but depressed trypsin and alpha-amylase activity. The inactivation of enzymes by dietary fibres can, at least partly, be explained by adsorption to the fibre or by the presence of enzyme inhibitors especially in natural compounds. The reasons for activation processes are unknown. As enzyme activities are decisive for food digestion, the properties of the individual fibres should be carefully considered when used as dietary supplement in physiological or pathological conditions. PMID:2483692

Leng-Peschlow, E

1989-01-01

310

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

311

Immunomodulatory effects of mineral fibres in occupationally exposed workers.  

PubMed

In the context of a large-scale molecular epidemiology study, the possible immunomodulatory effects of mineral fibres, in workers occupationally exposed to asbestos, rockwool and glass fibres, were examined. In each plant, 61, 98 and 80 exposed workers and 21, 43 or 36 control clerical subjects, respectively, were recruited. In the case of the asbestos-exposed subjects, an additional town-control group of 49 people was included. Evidence of pulmonary fibrosis was found in 42% of the asbestos-exposed workers, while evidence of pleural fibrosis was found in 24%. The asbestos-exposed cohort had significantly decreased forced vital capacity of lungs as well as forced expiratory volume per first second. Our findings indicate that exposure to all three types of fibres examined modulates to different degrees the immune response. Suppression of T-cell immunity and to a lesser extent, B-cell immunity was found in the case of workers from a former asbestos cement plant, while stimulation of T-cell response was observed in rockwool workers, and stimulation of T- and B-cell response was seen in glass fibre workers. Depression of the percentage of lymphocyte subpopulation of CD 16+56 (natural killer cells) in peripheral blood was found in glass fibre workers. Statistical analysis showed increased levels of proinflammatory cytokines (IL-6 asbestos; IL-8 all three fibres), expression of adhesion molecule L-selectin on granulocytes and monocytes (asbestos), levels of soluble adhesion molecules (SAMs) in sera (ICAM-1 all three fibres; E-selectin glass fibres), increased levels of immunoglobulin E (asbestos and rockwool) and elevated expression of activation markers on eosinophils (CD66b asbestos, glass fibres; CD69 asbestos). Significant correlations were observed between lymphocyte proliferation and markers of DNA damage and repair. Increased levels of proinflammatory cytokines, SAMs, immunoglobulin E and elevated expression of activation markers on eosinophils was found in people with symptoms of hypersensitivity and an elevated inflammatory status. PMID:15288538

Tulinska, Jana; Jahnova, Eva; Dusinska, Maria; Kuricova, Miroslava; Liskova, Aurelia; Ilavska, Silvia; Horvathova, Mira; Wsolova, Ladislava; Kyrtopoulos, Soterios A; Collins, Andrew; Harrington, Vikki; Fuortes, Laurence

2004-09-01

312

Enhanced sensitivity of an in-fibre Bragg grating pressure sensor achieved through fibre diameter reduction  

Microsoft Academic Search

Contemporary biomedical pressure sensors are based on miniaturized piezo-resistive, strain-gauge or other solid-state sensing technologies. All of these technologies have key limitations, when packaged into miniaturized sensors, including fragility and long term instability. In-fibre Bragg gratings (FBGs) are an attractive alternative to these electronic technologies because FBGs are biocompatible, robust, immune to electromagnetic interference and mechanically compliant. FBGs can also

Christopher R Dennison; Peter M Wild

2008-01-01

313

All-fibre photonic crystal distributed Bragg reflector (PC-DBR) fibre laser.  

PubMed

We describe an Er3+-doped aluminosilicate core photonic crystal fibre laser incorporating distributed Bragg reflectors written by two-photon 193nm irradiation through an optical phase mask as the feedback elements. The laser is diode pumped at 980nm and evidence of dual linewidth laser operation close to threshold is observed. However, at higher pumping levels gain competition preferentially selects one laser line. PMID:19466085

Canning, J; Groothoff, N; Buckley, E; Ryan, T; Lyytikainen, K; Digweed, J

2003-08-25

314

All-fibre photonic crystal distributed Bragg reflector (PC-DBR) fibre laser  

NASA Astrophysics Data System (ADS)

We describe an Er3+-doped aluminosilicate core photonic crystal fibre laser incorporating distributed Bragg reflectors written by two-photon 193nm irradiation through an optical phase mask as the feedback elements. The laser is diode pumped at 980nm and evidence of dual linewidth laser operation close to threshold is observed. However, at higher pumping levels gain competition preferentially selects one laser line.

Canning, J.; Groothoff, N.; Buckley, E.; Ryan, T.; Lyytikainen, K.; Digweed, J.

2003-08-01

315

Estimation of axial stiffness of plant fibres from compaction of non-woven mats  

NASA Astrophysics Data System (ADS)

Plant fibres are known to show a large variability in stiffness, which makes it time-consuming to experimentally characterize this property by conventional tensile testing. In this work, an alternative method is used, where the average fibre stiffness is back-calculated from compaction tests of in-plane randomly oriented fibre mats. The model by Toll is used to relate the load-displacement curve from the test to the Young modulus of the fibre, taking into account the natural variability in fibre cross section. Several tests have been performed on hemp fibre mats and compared with results from single-fibre tensile testing. The average back-calculated Young's modulus of the fibres was 45 GPa, whereas the average value from tensile testing ranged from 30 to 60 GPa. The straightforward compaction test can be useful in ranking of fibre stiffness, provided that the mat is composed of well-separated fibres and not of twisted yarns.

Gamstedt, E. K.; Bommier, E.; Madsen, B.

2014-03-01

316

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

NASA Astrophysics Data System (ADS)

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

Lorenz, Pierre; Ehrhardt, Martin; Zimmer, Klaus

2014-05-01

317

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.

?ižmįr, Tomįš; Dholakia, Kishan

2012-10-01

318

FT Raman microscopy of untreated natural plant fibres  

NASA Astrophysics Data System (ADS)

The application of FT-Raman microscopy to the non-destructive analysis of natural plant fibres is demonstrated with samples of flax, jute, ramie, cotton, kapok, sisal and coconut fibre. Vibrational assignments are proposed and characteristic features of each material are presented. Samples were not pre-treated chemically before analysis and were used directly from their respective storage collection; the adaptation of the Raman microscopic technique to the identification of specimens of natural fibres in archaeological burial sites is explored for its forensic potential.

Edwards, H. G. M.; Farwell, D. W.; Webster, D.

1997-11-01

319

Fibre morphology and soda-sulphite pulping of switchgrass.  

PubMed

This paper describes the fibre morphology of switchgrass (Panicum virgatum L.) and its pulping characteristics using sodium hydroxide and a combination of sodium hydroxide and sodium sulphite as the cooking agents. It was found that the fibre length of switchgrass is similar to that of poplar despite its high population of short fibre elements (< 0.2 mm). The switchgrass used in this study had a lignin content comparable to that of poplar, but a particularly high content of extractable materials. The soda pulp from switchgrass showed excellent mechanical properties and showed a great potential as a reinforcement component in newsprint making. PMID:11211070

Law, K N; Kokta, B V; Mao, C B

2001-03-01

320

Dynamics of similariton pulses in length-inhomogeneous active fibres  

SciTech Connect

The possibility of producing self-similar frequency-modulated (FM) optical wave packets in length-inhomogeneous active fibres is studied for optical pulses with the initial Gaussian, hyperbolic-secant or parabolic shape. The conditions for converting these pulses into stable parabolic-type pulses with a constant frequency-modulation rate are considered. It is shown that the use of FM pulses of parabolic shape in active and length-inhomogeneous fibres can ensure the creation of an all-fibre generator-amplifier-compressor system with peak powers up to 1 MW and higher in the generated pulses. (nonlinear optical phenomena)

Zolotovskii, Igor' O; Sementsov, Dmitrii I; Yavtushenko, M S [Ulyanovsk State University, Ulyanovsk (Russian Federation); Senatorov, A K; Sysolyatin, A A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2010-05-26

321

Evaluation of fracture toughness of ZrO 2 and Si 3N 4 engineering ceramics following CO 2 and fibre laser surface treatment  

NASA Astrophysics Data System (ADS)

The fracture toughness property ( K1C) of Si 3N 4 and ZrO 2 engineering ceramics was investigated by means of CO 2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate measuring machine was used to investigate the diamond indentations and to measure the lengths of the cracks. Thereafter, computational and analytical methods were employed to determine the K1C. An increase in the K1C of both ceramics was found by the CO 2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO 2 laser radiated surface of the Si 3N 4 was over 3% higher in comparison to that of the fibre laser treated surface. This was by softening of the near surface layer of the Si 3N 4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO 2 ceramic to that of the Si 3N 4 as the fibre laser radiation in this case had produced an increase of 34% compared to that of the CO 2 laser radiation. This occurred due to propagation of lower crack resulting from the Vickers indentation test during the fibre laser surface treatment which inherently affected the end K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO 2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.

Shukla, P. P.; Lawrence, J.

2011-02-01

322

Interfacial studies on surface modified Kevlar fibre\\/epoxy matrix composites  

Microsoft Academic Search

Kevlar fibre\\/epoxy composites with superior interfacial strength were developed, by chemical treatment of the fibre surface with organic solvents. Multiple fibre pullout tests revealed that it is possible to raise the interfacial strength to 63MPa from a value of 39MPa normally exhibited by untreated Kevlar fibre\\/epoxy composites. A physicochemical and morphological characterization of the chemically treated fibre surface by microscopic

C. Y. Yue; K. Padmanabhan

1999-01-01

323

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

SciTech Connect

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

Bufetov, Igor' A; Semenov, S L; Vel'miskin, V V; Firstov, Sergei V; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Bufetova, G A [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-09-10

324

K-theory with fibred control.  

E-print Network

Controlled methods proved to be very effective in the study of assembly maps in algebraic K-theory. For the questions concerning surjectivity of these maps in the context of geometries that have no immanent nonpositive curvature, the setting needs to be enlarged to bounded G-theory with fibred control. We set up the natural framework for this theory. As should be expected, the G-theory has better excision properties. The main result illustrates a fact that has no analogue in bounded K-theory. It is one of the major technical tools used in our work on the Borel Conjecture about topological rigidity of aspherical manifolds. The general framework we develop will be useful for other applications to coarse bundles and stacks.

Gunnar Carlsson; Boris Goldfarb

325

Tellurite glasses for optical fibre fabrication  

NASA Astrophysics Data System (ADS)

Technology of tellurite glasses from the TeO2-WO3-PbO-La2O3 has been investigated. The effect of lanthanum oxide content on tendency to the crystallization of glassy matrix has been studied. Differential thermal analysis DTA/DSC, XRD measurement have been considered in term of lanthanum oxide influence. The refractive indices (n) for series of glass compositions with various La2O3 contents compared with glass without La2O3 addition has been measured. From obtain results it has been stated that the refractive index slightly increases with the addition of the lanthanum oxides in all glass of compositions. Double crucible drawing technique was applied to drown tellurite optical fibre with high numerical aperture (0.8).

Reben, Manuela; Wasylak, Jan; Dorosz, Dominik

2008-06-01

326

Biaxial extension of knitted steel fibre fabrics  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

327

Portable, miniaturized, fibre delivered, multimodal CARS exoscope.  

PubMed

We demonstrate for the first time, a portable multimodal coherent anti-Stokes Raman scattering microscope (exoscope) for minimally invasive in-vivo imaging of tissues. This device is based around a micro-electromechanical system scanning mirror and miniaturized optics with light delivery accomplished by a photonic crystal fibre. A single Ti:sapphire femtosecond pulsed laser is used as the light source to produce CARS, two photon excitation fluorescence and second harmonic generation images. The high resolution and distortion-free images obtained from various resolution and bio-samples, particularly in backward direction (epi) successfully demonstrate proof of concept, and pave the path towards future non or minimally-invasive in vivo imaging. PMID:23938563

Smith, Brett; Naji, Majid; Murugkar, Sangeeta; Alarcon, Emilio; Brideau, Craig; Stys, Peter; Anis, Hanan

2013-07-15

328

Calcium movements in single crustacean muscle fibres  

PubMed Central

1. Internal microinjection of the Ca-sensitive photoprotein aequorin or the isotope 45Ca have been used to assess Ca movements in single muscle fibres from the barnacle Balanus nubilus and the crab Maia squinado. 2. Progressive isosomotic replacement of external Na by Li, choline, sucrose or Tris was associated with a rapid increase in the level of light emission from internally injected aequorin. This response was dependent upon the presence of external Ca. The light output was maximal for Na concentrations < 50 mM in the replaced salines, while Na concentrations > 350 mM produced no apparent increase in the resting light emission. 3. If the Ca concentration in the external saline was altered, no effect was observed in Na replaced salines when the Ca concentration was < 1 mM, but maximal effects were observed at concentrations of Ca of ca. 100 mM. 4. The increased light emission from aequorin in Na-replaced salines was substantially inhibited by 1 mM-La3+ applied externally, but not by N-ethyl maleimide (NEM), propanolol or D-600. 5. Following microinjection of 45Ca and 2 hr equilibration, the residual efflux of Ca was shown to be sensitive to the removal of external Ca and Na, the extent of each component being variable. 6. The Na-sensitive Ca efflux was partially inhibited by external La3+ (1 mM), but not by high concentrations of Mg2+, Ca2+, Mn2+ or Co2+. It was stimulated by NEM and ethacrynic acid, which was considered to be due to an indirect effect upon the sarcoplasmic reticulum. 7. It is concluded that Ca movements in these single crustacean muscle fibres involve Na gradients and a Ca: Ca exchange and from the relative insensitivity of Ca movements to various inhibitors, in contrast to the Mg system, it seems that there may be two independent modes for divalent cation transport in this preparation. PMID:4436825

Ashley, C. C.; Ellory, J. C.; Hainaut, K.

1974-01-01

329

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

330

Nondestructive identification of engineering properties of metal fibre composites  

NASA Astrophysics Data System (ADS)

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

Vala, J.; Horįk, M.

2012-09-01

331

Graphene chiral liquid crystals and macroscopic assembled fibres  

NASA Astrophysics Data System (ADS)

Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles.

Xu, Zhen; Gao, Chao

2011-12-01

332

Desquamative interstitial pneumonia associated with chrysotile asbestos fibres.  

PubMed

The drywall construction trade has in the past been associated with exposure to airborne asbestos fibres. This paper reports a drywall construction worker with 32 years of dust exposure who developed dyspnoea and diminished diffusing capacity, and showed diffuse irregular opacities on chest radiography. He did not respond to treatment with corticosteroids. Open lung biopsy examination showed desquamative interstitial pneumonia. Only a single ferruginous body was seen on frozen section, but tissue examination by electron microscopy showed an extraordinary pulmonary burden of mineral dust with especially high concentrations of chrysotile asbestos fibres. This report emphasises the need to consider asbestos fibre as an agent in the aetiology of desquamative interstitial pneumonia. The coexistent slight interstitial fibrosis present in this case is also considered to have resulted from exposure to mineral dust, particularly ultramicroscopic asbestos fibres. PMID:1645584

Freed, J A; Miller, A; Gordon, R E; Fischbein, A; Kleinerman, J; Langer, A M

1991-05-01

333

NANOCOMPOSITE BASED STRUCTURAL HEALTH MONITORING APPROACHES FOR FIBRE REINFORCED POLYMERS  

E-print Network

NANOCOMPOSITE BASED STRUCTURAL HEALTH MONITORING APPROACHES FOR FIBRE REINFORCED POLYMERS propagating implementation of nanocomposite SHM approaches especially in large structures. Therefore strategies are necessary. The present contribution offers an overview over today's research on nanocomposite

Boyer, Edmond

334

Exploring capacity limits of fibre-optic mommunication systems  

Microsoft Academic Search

The problem of evaluating the maximum possible rate of information transmission in fibre-optic communication systems is discussed. A spectral efficiency of ?7 bits\\/s\\/Hz over 1000 km in one polarization is shown to be theoretically achievable.

Rene-Jean Essiambre; Gerard J. Foschini; Peter J. Winzer; Gerhard Kramer

2008-01-01

335

On the spectral information distribution in optical fibres  

Microsoft Academic Search

A revision of the traditional way of looking at the spectral distribution of the information in optical fibres is proposed. General design rules for the design of high capacity transmission systems are reported.

Hadrien Louchet; Klaus Petermann; Alan Robinson; Richard Epworth

2004-01-01

336

Active optical fibres in modern particle physics experiments  

E-print Network

In modern particle physics experiments wavelength-shifting and scintillating fibres based on plastic polymers are used for tracking and calorimetry. In this review the role of photon trapping efficiencies, transmission functions and signal response times for common multimode active fibres is discussed. Numerical simulations involving three dimensional tracking of skew rays through curved fibres demonstrate the characteristics of trapped light. Of practical interest are the parametrisations of transmission functions and the minimum permissible radius of curvature. These are of great importance in today's experiments where high count rates and small numbers of photoelectrons are encountered. Special emphasis has been placed on the timing resolution of fibre detectors and its limitation due to variations in the path length of generated photons.

C. P. Achenbach

2004-04-05

337

Studies of avalanche photodiodes for scintillating fibre tracking readout  

SciTech Connect

Avalanche Photodiodes (APDs) operating in ``Geiger Mode`` have been studied in a fibre tracking readout environment. A fast recharge circuit has been developed for high rate data taking, and results obtained from a model fibre tracker in the test beam at Brookhaven National Laboratory are presented. A high rate calibrated light source has been developed using a commercially available laser diode and has been used to measure the efficiency of the devices. The transmission of the light from a 1mm fibre onto a 0.5mm diameter APD surface has been identified as the main problem in the use of these particular devices for scintillating fibre tracking in the Superconducting Supercollider environment. Solutions to this problem are proposed.

Fenker, H; Thomas, J

1993-01-01

338

Graphene chiral liquid crystals and macroscopic assembled fibres  

PubMed Central

Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles. PMID:22146390

Xu, Zhen; Gao, Chao

2011-01-01

339

Optical fibre-coupled cryogenic radiometer with carbon nanotube absorber  

NASA Astrophysics Data System (ADS)

A cryogenic radiometer was constructed for direct-substitution optical-fibre power measurements. The cavity is intended to operate at the 3 K temperature stage of a dilution refrigerator or 4.2 K stage of a liquid cryostat. The optical fibre is removable for characterization. The cavity features micromachined silicon centring rings to thermally isolate the optical fibre as well as an absorber made from micromachined silicon on which vertically aligned carbon nanotubes were grown. Measurements of electrical substitution, optical absorption and temperature change indicate that the radiometer is capable of measuring a power level of 10 nW with approximate responsivity of 155 nW K-1 and 1/e time constant of 13 min. An inequivalence between optical and electrical power of approximately 10% was found, but the difference was largely attributable to unaccounted losses in the optical fibre.

Livigni, David J.; Tomlin, Nathan A.; Cromer, Christopher L.; Lehman, John H.

2012-04-01

340

Desquamative interstitial pneumonia associated with chrysotile asbestos fibres.  

PubMed Central

The drywall construction trade has in the past been associated with exposure to airborne asbestos fibres. This paper reports a drywall construction worker with 32 years of dust exposure who developed dyspnoea and diminished diffusing capacity, and showed diffuse irregular opacities on chest radiography. He did not respond to treatment with corticosteroids. Open lung biopsy examination showed desquamative interstitial pneumonia. Only a single ferruginous body was seen on frozen section, but tissue examination by electron microscopy showed an extraordinary pulmonary burden of mineral dust with especially high concentrations of chrysotile asbestos fibres. This report emphasises the need to consider asbestos fibre as an agent in the aetiology of desquamative interstitial pneumonia. The coexistent slight interstitial fibrosis present in this case is also considered to have resulted from exposure to mineral dust, particularly ultramicroscopic asbestos fibres. Images PMID:1645584

Freed, J A; Miller, A; Gordon, R E; Fischbein, A; Kleinerman, J; Langer, A M

1991-01-01

341

Exploiting multimode waveguides for pure fibre-based imaging  

PubMed Central

There has been an immense drive in modern microscopy towards miniaturization and fibre-based technology. This has been necessitated by the need to access hostile or difficult environments in situ and in vivo. Strategies to date have included the use of specialist fibres and miniaturized scanning systems accompanied by ingenious microfabricated lenses. Here we present a novel approach for this field by utilizing disordered light within a standard multimode optical fibre for lensless microscopy and optical mode conversion. We demonstrate the modalities of bright- and dark-field imaging and scanning fluorescence microscopy at acquisition rates that allow observation of dynamic processes such as Brownian motion of mesoscopic particles. Furthermore, we show how such control can realize a new form of mode converter and generate various types of advanced light fields such as propagation-invariant beams and optical vortices. These may be useful for future fibre-based implementations of super-resolution or light-sheet microscopy. PMID:22929784

?ižmįr, Tomįš; Dholakia, Kishan

2012-01-01

342

a type of barley from its crude fibre content using a correction of 110Kcal per supplementary point of crude fibre in the seed dry matter  

E-print Network

a type of barley from its crude fibre content using a correction of 110Kcal per supplementary point of crude fibre in the seed dry matter : D.E. (Kcal i'kg 1) - 4.072- I10 crude fibre p. ioo D.1I. r = - o.96 different types (SoNJn: two-row winter barley, ASTlux: six-row winter barley) and of different crude fibre

Paris-Sud XI, UniversitƩ de

343

Selection of optical modes in multichannel fibre lasers  

SciTech Connect

The numerical simulation of radiation propagation in a multichannel fibre amplifier showed that the phases of input beams having the initial spread are equalised during the propagation of these beams due to the spatial filtration of the field by the structure of amplifying channels. The nonlinear part of the refractive index affects the phase matching process to a lesser extent. An increase in the coupling between the channels enhances the self-organisation of the beams. (optical fibres)

Vysotskii, D V; Elkin, N N; Napartovich, A P [State Research Center of Russian Federation 'Troitsk Institute for Innovation and Fusion Research', Troitsk, Moscow Region (Russian Federation)

2006-01-31

344

Stabilized polyglycolic acid fibre-based tubes for tissue engineering  

Microsoft Academic Search

Polyglycolic acid (PGA) fibre meshes are attractive candidates to transplant cells, but they are incapable of resisting significant compressional forces. To stabilize PGA meshes, atomized solutions of poly(l-lactic acid) (PLLA) and a 50\\/50 copolymer of poly(d,l-lactic-co-glycolic acid) (PLGA) dissolved in chloroform were sprayed over meshes formed into hollow tubes. The PLLA and PLGA coated the PGA fibres and physically bonded

D. J. Mooney; C. L. Mazzoni; C. Breuer; K. McNamara; D. Hern; J. P. Vacanti; R. Langer

1996-01-01

345

Automatic control system for spinning and winding of synthetic fibres  

Microsoft Academic Search

An automatic control system for spinning and winding of synthetic fibres that provides for operation of the electric drive\\u000a of the metering pumps in conditions of stabilization of the melt pressure and rotation rate of the winder drive was proposed.\\u000a A laboratory bench that simulates operation of the device for controlling spinning and winding of synthetic fibres based on\\u000a software

A. V. Shilov; P. V. Matveev; T. A. Feoktistova; K. A. Polyakov; A. E. Polyakov

2007-01-01

346

New SPME fibre for analysis of mequinol emitted from DVDs  

Microsoft Academic Search

A piece of fused-silica fibre coated with silica modified with ketamine-groups was used as a solidphase microextraction (SPME)\\u000a fibre and its efficiency in the qualitative and quantitative analysis of volatile organic compounds released from coloured\\u000a overprinting on DVDs was evaluated. The effect of the parameters that can affect the SPME procedure, such as extraction time,\\u000a extraction temperature, desorption temperature, was

Magdalena Palacz; Wies?aw Wasiak

2011-01-01

347

Elastic and inelastic behaviour of resting frog muscle fibres  

Microsoft Academic Search

Dynamic and static elasticity of the resting skeletal muscle of the frog have been studied as a function of the sarcomere length. Isolated intact fibres as well as glycerol extracted fibres show a resting tension starting at 2,05 µm sarcomere length and increasing approximately exponentially to 2·104 N\\/m2 at 3,0 µm sarcomere length. Differences between the two types of preparation

Rolf Helber; Universitfit Ulm; Angewandte Physik; Oberer Eselsberg

1980-01-01

348

Some special features of spinning of polyethylene gel-fibre  

Microsoft Academic Search

Slow heating of the polymer powder in the solvent with intense stirring in an apparatus with self-cleaning surfaces is required for obtaining a homogeneous solution of ultrahigh-molecular-weight polyethylene (UHMPE). In spinning UHMPE gel-fibre by the dry-wet method, it is necessary to use a liquid with a low surface tension coefficient in the cooling bath. When ultrastrong, high-modulus UHMPE fibre is

V. G. Alekseev

1995-01-01

349

Measurement of magnetic field using Rayleigh backscattering in optical fibres  

SciTech Connect

In this paper, we investigate the use of optical reflectometry in optical fibres for the measurement of magnetic field. The dedicated application concerns the measurement of plasma current in the fusion reactor. The measurement is based on the rotation of the polarization state of the Rayleigh backscattered signal when an optical pulse is launched in the fibre. Particular care has been undertaken to evaluate the impact of linear birefringence on the measurement performance. (authors)

Wuilpart, M.; Caucheteur, C. [Univ. of Mons, Faculty of Engineeering, Electromagnetism and Telecommunications Dept., 31, Boulevard Dolez, 7000 Mons (Belgium); Goussarov, A. [SCK.CEN, 200 Boerentang, 2400 Mol (Belgium); Aerssens, M. [Univ. of Mons, Faculty of Engineeering, Electromagnetism and Telecommunications Dept., 31, Boulevard Dolez, 7000 Mons (Belgium); Massaut, V. [SCK.CEN, 200 Boerentang, 2400 Mol (Belgium); Megret, P. [Univ. of Mons, Faculty of Engineeering, Electromagnetism and Telecommunications Dept., 31, Boulevard Dolez, 7000 Mons (Belgium)

2011-07-01

350

Correct Ray-Tracing Analysis for Interference Microscopy of Fibres  

Microsoft Academic Search

A ray-tracing analysis for calculating, by means of interference microscope data, the radial distribution of refractive index, n(r), for fibres of round cross section has been formulated, solved, tested and used to determine n(r) for high-speed direct-spun polyethylene terephthalate (PET) fibres. The formulation was based on work by Kahl & Mylin (1965) originally performed to explore the radial density profiles

Z. Z. Wu; Hawthorne Davis; S. K. Batra

1995-01-01

351

Cable analysis in quiescent and active sheep Purkinje fibres.  

PubMed

Cable properties of sheep cardiac Purkinje fibres were studied under resting and paced conditions. Standard micro-electrode techniques were used to apply intracellular current pulses and record the resultant voltage changes at various distances from the current input. In a parallel set of experiments, fibre dimensions were measured after freezing and serial sectioning. Fibres selected on the basis of a cylindrical appearance had approximately uniform cross-sectional diameters which varied +/- 12% along their length. Electrotonic potentials recorded at rest and in diastole (under conditions that minimized diastolic depolarization) adhered quite closely to the behaviour expected for a unidimensional cable provided voltages were recorded greater than or equal to one fibre diameter from the current source. The unidimensional space constant, input resistance, and membrane time constant were significantly larger during quiescence than in diastole. These differences were accounted for by a 90% increase in membrane resistance at rest. There was no significant change in internal longitudinal resistance nor membrane capacitance associated with activity. The voltage distribution close to the current input (i.e. within one fibre diameter) strongly deviated from the theoretical three-dimensional voltage decay expected for a homogeneous cylinder. This finding suggests that the transverse resistance to current flow is much greater than the longitudinal resistance. The anisotropic behaviour within the cardiac Purkinje fibre may explain several previous observations: (i) the lack of a relationship between conduction velocity and fibre diameter; and (ii) the much shorter liminal length for excitation in Purkinje fibres than for point-stimulated squid axons. PMID:6747906

Pressler, M L

1984-07-01

352

Low-impulse blast behavior of fibre-metal laminates  

Microsoft Academic Search

This paper presents three dimensional (3D) finite element (FE) models of the low-impulse localised blast loading response of fibre-metal laminates (FMLs) based on an 2024-O aluminium alloy and a woven glass-fibre\\/polypropylene composite (GFPP). A vectorized user material subroutine (VUMAT) is developed to define the mechanical constitutive behaviour and Hashin’s 3D failure criteria incorporating strain-rate effects in the GFPP. In order

T. P. Vo; Z. W. Guan; W. J. Cantwell; G. K. Schleyer

353

Permissible crack widths in steel fibre reinforced marine concrete  

Microsoft Academic Search

The paper presents some results from a continuing study of the marine durability of steel fibre reinforced concrete. The overall\\u000a aim of the investigation is to develop the material for marine applications. The results reported here pertain to pre-cracked\\u000a specimens of steel fibre reinforced concrete which were exposed to wet-dry cycles of marine spray in the laboratory simulating\\u000a tidal zone

P. S. Mangat; K. Gurusamy

1987-01-01

354

Method for calculating SBS threshold in optical fibres  

SciTech Connect

It is shown that the widely used method for calculating the SBS threshold in optical fibres yields erroneous results in a number of practically important cases. In particular, not all acoustic-antiwaveguide optical fibres demonstrate an increase in the SBS threshold. For the SBS threshold to increase, it is necessary to provide fast disruption of the acoustic wavefront due to refraction. (nonlinear optical phenomena)

Nanii, Oleg E; Pavlova, E G [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)

2009-08-31

355

SOLITONS: Nonreciprocal dynamics of pulses in a nonlinear inhomogeneous fibre  

NASA Astrophysics Data System (ADS)

The conditions, under which the nonreciprocity of the frequency modulation rate and pulse duration as well as the spectral nonreciprocity in fibres with different types of inhomogeneity of nonlinearity and group-velocity dispersion appear, are studied for the Gaussian and hyperbolic secant frequency-modulated pulses. Strong compression nonreciprocity is found in fibres with an alternating group-velocity dispersion periodically changing over its length.

Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.

2007-08-01

356

Thixotropy, yielding and ultrasonic Doppler velocimetry in pulp fibre suspensions  

Microsoft Academic Search

This paper reports thixotropy in concentrated pulp fibre suspensions and studies their transient flow behaviour using conventional\\u000a rheometry coupled with a velocimetry technique. Specifically, an ultrasonic Doppler velocimeter is used in conjunction with\\u000a a rate-controlled rheometer to deduce the local velocity profiles of pulp fibre suspensions. Pulp suspensions are found to\\u000a exhibit a plateau in their flow curves where a

Babak Derakhshandeh; Dimitris Vlassopoulos; Savvas G. Hatzikiriakos

357

Growth of calcium phosphate on phosphorylated chitin fibres  

Microsoft Academic Search

Calcium phosphate growth on chitin phosphorylated fibres was studied using scanning electron microscopy and energy dispersive X-ray analysis (SEM, EDX), micro-Fourier transform infrared spectroscopy (FTIR), and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The C6 chemical shift positions of 13C MAS NMR in the chitin fibres phosphorylated using urea and H3PO4 are obvious indicating that phosphorylation

Y. YOKOGAWA; J PAZ REYES; M. R MUCALO; M TORIYAMA; Y KAWAMOTO; T SUZUKI; K NISHIZAWA; F NAGATA; T KAMAYAMA

1997-01-01

358

Nonlinear fibre-optic devices pumped by semiconductor disk lasers  

SciTech Connect

Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

Chamorovskiy, A Yu; Okhotnikov, Oleg G [Optoelectronics Research Center, Tampere University of Technology, Tampere (Finland)

2012-11-30

359

Plantain fibre bundles isolated from Colombian agro-industrial residues.  

PubMed

Comestible fruit production from Musaceas plants is an important economical activity in developing countries like Colombia. However, it generates a large amount of agro-industrial residues. Some of them are a potential resource of natural fibres, which can be used as reinforcement for composite materials. In this work, a series of commercial plantain (Musa AAB, cv "Dominico Harton") fibre bundles extracted from pseudostem, leaf sheath and rachis agricultural wastes were analyzed. Mechanical decortication and biological retting processes were used during fiber extraction. No significant differences in composition of vascular bundles were observed for both extraction processes. Gross morphological characteristics and mechanical behavior have been evaluated. Conducting tissues with spiral-like arrangement are observed attached to fibre bundles. This fact suggests a big amount of these tissues in commercial plantain plants. Both used extraction methods are not enough to remove them. Pseudostem fibre bundles have higher specific strength and modulus and lower strain at break than leaf sheath and rachis fibre bundles, having values comparable to other lignocellulosic fibres bundles. PMID:17350832

Gańįn, Piedad; Zuluaga, Robin; Restrepo, Adriana; Labidi, Jalel; Mondragon, Ińaki

2008-02-01

360

Determinant factor for clearance of ceramic fibres from rat lungs.  

PubMed Central

Deposition, clearance, retention, and durability of inhaled particles from lungs are known to be important factors for induction of pulmonary fibrosis or lung cancer. To study the deposition and clearance of alumina silicate ceramic fibres from the lung, male Wistar rats were exposed to ceramic fibre particles with a mass median aerodynamic diameter (MMAD) of 4.2 micron, for six hours a day, five days a week for two weeks. The average exposure concentration was 20.7 (standard deviation (SD) 4.5) mg/m3. The rats were killed at one day, three months, and six months after the end of exposure, and the fibre numbers and dimensions were measured with a scanning electron microscope. No significant differences in number and geometric mean length of residual ceramic fibres in the lungs were found between the groups. The geometric mean diameter, however, decreased according to the duration of the clearance period. These findings suggest that solubility of fibre contributes most in the clearance of the inhaled ceramic fibres from the lungs. PMID:1554614

Yamato, H; Tanaka, I; Higashi, T; Kido, M

1992-01-01

361

Fire Retardancy of Natural Fibre Reinforced Sheet Moulding Compound  

NASA Astrophysics Data System (ADS)

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

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

2007-07-01

362

Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites  

NASA Astrophysics Data System (ADS)

The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available thermoplastic based composite laminate is investigated followed by post processed part characterization. Key findings include an optimized composite processing window, and the influence of raw material blank forming temperature and mould tool temperature on part crystallinity and flexural strength. This process study forms one element of a major project structure which has been designed to address the gap between design, analysis and manufacturing, using at its core, a digital framework for the creation and management of performance parameters related to the lifecycle performance of thermoplastic composite structures.

McCool, Raurķ; Murphy, Adrian; Wilson, Ryan; Jiang, Zhenyu; Price, Mark

2011-05-01

363

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. PMID:23762440

Lingham-Soliar, Theagarten; Murugan, Nelisha

2013-01-01

364

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

SciTech Connect

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

Kobtsev, Sergey M; Kukarin, S V; Fedotov, Yu S [Novosibirsk State University, Novosibirsk (Russian Federation)

2009-05-31

365

Formation of 8-hydroxydeoxyguanosine by asbestos and man made mineral fibres.  

PubMed

Samples of rockwool and glass fibre were compared with chrysotile fibres for their capacity to hydroxylate 2-deoxyguanosine to 8-hydroxydeoxyguanosine, a reaction that is mediated by formation of hydroxyl radicals. All three fibres produced 8-hydroxydeoxyguanosine in the absence of H2O2. The chrysotile fibres were most potent and produced about ten times more of the modified nucleoside than rockwool and glass fibre. This investigation shows that not only asbestos but also man made mineral fibres are able to modify nucleosides. PMID:2837271

Leanderson, P; Söderkvist, P; Tagesson, C; Axelson, O

1988-05-01

366

Envelope and phase evolution of femtosecond pulses in hollow photonic-crystal fibres  

SciTech Connect

Changes in the envelope and the evolution of the spectral phase and chirp of femtosecond pulses propagating through hollow fibres with a photonic-crystal cladding are experimentally studied. Envelope and phase distortions of ultrashort pulses transmitted through such fibres are shown to be controlled by the detuning of the carrier frequency of laser pulses from the central frequency of the passband in the transmission of the fibre. Near the passband edges, which map the edges of photonic band gaps of the fibre cladding, ultrashort pulses transmitted through the fibre display considerable envelope distortions, as well as frequency- and time-dependent phase shifts. (optical fibres)

Konorov, Stanislav O [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Fedotov, Andrei B; Zheltikov, Aleksei M [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Beloglazov, V I; Skibina, N B; Shcherbakov, Andrei V [Institute of Technology and Processing of Glass Structures, Russian Academy of Sciences, Saratov (Russian Federation)

2004-01-31

367

PRAXIS: low thermal emission high efficiency OH suppressed fibre spectrograph  

NASA Astrophysics Data System (ADS)

PRAXIS is a second generation instrument that follows on from GNOSIS, which was the first instrument using fibre Bragg gratings for OH suppression to be deployed on a telescope. The Bragg gratings reflect the NIR OH lines while being transparent to the light between the lines. This gives in principle a much higher signal-noise ratio at low resolution spectroscopy but also at higher resolutions by removing the scattered wings of the OH lines. The specifications call for high throughput and very low thermal and detector noise so that PRAXIS will remain sky noise limited even with the low sky background levels remaining after OH suppression. The optical and mechanical designs are presented. The optical train starts with fore-optics that image the telescope focal plane on an IFU which has 19 hexagonal microlenses each feeding a multi-mode fibre. Seven of these fibres are attached to a fibre Bragg grating OH suppression system while the others are reference/acquisition fibres. The light from each of the seven OH suppression fibres is then split by a photonic lantern into many single mode fibres where the Bragg gratings are imprinted. Another lantern recombines the light from the single mode fibres into a multi-mode fibre. A trade-off was made in the design of the IFU between field of view and transmission to maximize the signal-noise ratio for observations of faint, compact objects under typical seeing. GNOSIS used the pre-existing IRIS2 spectrograph while PRAXIS will use a new spectrograph specifically designed for the fibre Bragg grating OH suppression and optimised for 1.47 ?m to 1.7 ?m (it can also be used in the 1.09 ?m to 1.26 ?m band by changing the grating and refocussing). This results in a significantly higher transmission due to high efficiency coatings, a VPH grating at low incident angle and optimized for our small bandwidth, and low absorption glasses. The detector noise will also be lower thanks to the use of a current generation HAWAII-2RG detector. Throughout the PRAXIS design, from the fore-optics to the detector enclosure, special care was taken at every step along the optical path to reduce thermal emission or stop it leaking into the system. The spectrograph design itself was particularly challenging in this aspect because practical constraints required that the detector and the spectrograph enclosures be physically separate with air at ambient temperature between them. At present, the instrument uses the GNOSIS fibre Bragg grating OH suppression unit. We intend to soon use a new OH suppression unit based on multicore fibre Bragg gratings which will allow an increased field of view per fibre. Theoretical calculations show that the gain in interline sky background signal-noise ratio over GNOSIS may very well be as high as 9 with the GNOSIS OH suppression unit and 17 with the multicore fibre OH suppression unit.

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

2014-07-01

368

Wave kinetics of random fibre lasers.  

PubMed

Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example-random fibre laser-we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics. PMID:25645177

Churkin, D V; Kolokolov, I V; Podivilov, E V; Vatnik, I D; Nikulin, M A; Vergeles, S S; Terekhov, I S; Lebedev, V V; Falkovich, G; Babin, S A; Turitsyn, S K

2015-01-01

369

Muscle fibre type composition and body composition in hammer throwers.  

PubMed

Aim of the present study was to describe the muscle fibre type composition and body composition of well-trained hammer throwers. Six experienced hammer throwers underwent the following measurements: one repetition maximum in squat, snatch, and clean, standing broad jump, backward overhead shot throw and the hammer throw. Dual x-ray absorptiometry was used for body composition analysis. Fibre type composition and cross sectional area was determined in muscle biopsy samples of the right vastus lateralis. Eight physical education students served as a control group. One repetition maximum in squat, snatch and clean for the hammer throwers was 245 ± 21, 132 ± 13 and 165 ± 12kg, respectively. Lean body mass was higher in hammer throwers (85.9 ± 3. 9kg vs. 62.7 ± 5.1kg (p < 0.01). The percentage area of type II muscle fibres was 66.1 ± 4% in hammer throwers and 51 ± 8% in the control group (p < 0.05). Hammer throwers had significantly larger type IIA fibres (7703 ± 1171 vs. 5676 ± 1270?m(2), p < 0.01). Hammer throwing performance correlated significantly with lean body mass (r = 0.81, p < 0.05). These data indicate that hammer throwers have larger lean body mass and larger muscular areas occupied by type II fibres, compared with relatively untrained subjects. Moreover, it seems that the enlarged muscle mass of the hammer throwers contributes significantly to the hammer throwing performance. Key pointsWell-trained hammer throwers had increased lean body mass, higher type IIA muscle fibres cross sectional areas, as well as higher bone mineral density, compared to controls.Increased lean body mass was closely related with hammer throwing performance.The relative high percentage of type IIX muscle fibres in vastus lateralis in hammer throwers warrants further investigation. PMID:24149393

Terzis, Gerasimos; Spengos, Konstantinos; Kavouras, Stavros; Manta, Panagiota; Georgiadis, Giorgos

2010-01-01

370

Muscle Fibre Type Composition and Body Composition in Hammer Throwers  

PubMed Central

Aim of the present study was to describe the muscle fibre type composition and body composition of well-trained hammer throwers. Six experienced hammer throwers underwent the following measurements: one repetition maximum in squat, snatch, and clean, standing broad jump, backward overhead shot throw and the hammer throw. Dual x-ray absorptiometry was used for body composition analysis. Fibre type composition and cross sectional area was determined in muscle biopsy samples of the right vastus lateralis. Eight physical education students served as a control group. One repetition maximum in squat, snatch and clean for the hammer throwers was 245 ± 21, 132 ± 13 and 165 ± 12kg, respectively. Lean body mass was higher in hammer throwers (85.9 ± 3. 9kg vs. 62.7 ± 5.1kg (p < 0.01). The percentage area of type II muscle fibres was 66.1 ± 4% in hammer throwers and 51 ± 8% in the control group (p < 0.05). Hammer throwers had significantly larger type IIA fibres (7703 ± 1171 vs. 5676 ± 1270?m2, p < 0.01). Hammer throwing performance correlated significantly with lean body mass (r = 0.81, p < 0.05). These data indicate that hammer throwers have larger lean body mass and larger muscular areas occupied by type II fibres, compared with relatively untrained subjects. Moreover, it seems that the enlarged muscle mass of the hammer throwers contributes significantly to the hammer throwing performance. Key points Well-trained hammer throwers had increased lean body mass, higher type IIA muscle fibres cross sectional areas, as well as higher bone mineral density, compared to controls. Increased lean body mass was closely related with hammer throwing performance. The relative high percentage of type IIX muscle fibres in vastus lateralis in hammer throwers warrants further investigation. PMID:24149393

Terzis, Gerasimos; Spengos, Konstantinos; Kavouras, Stavros; Manta, Panagiota; Georgiadis, Giorgos

2010-01-01

371

The surface area of sheep cardiac Purkinje fibres  

PubMed Central

1. Measurements combining the techniques of point counting and line integration were performed on light and electron micrographs of Purkinje fibres from the sheep's heart. The measurements were aimed at determining membrane areas of importance for the cellular electrophysiology of this tissue. 2. The mean volume fractions of the cells occupied by various constituents were: myofibrils, 0·234; mitochondria, 0·103; and nuclei, 0·009. The mean volume fraction of the fibres occupied by the interspaces between the tightly packed cells was 0·0023. 3. The mean fractions of intercellular surface area occupied by junctional specializations were: nexus, 0·17; desmosome, 0·023; and fascia adherens, 0·014. 4. The mean surface to volume ratio of the Purkinje cells and fibres was 0·46 ?-1 which is 11·5 times the value of the surface to volume ratio of a long right circular cylinder 100 ? in diameter. 5. There are two reasons for the increment in the surface to volume ratio of the fibre (when compared to that of a long right circular cylinder 100 ? in diameter): the multicellular composition of the fibres and the extensive folding of the surface of the cells. 6. After correction for the intercellular nexal area the surface to volume ratio of a long cylindrical fibre 100 ? in diameter was 0·39 ?-1, or about 10 times the value for a long right circular cylinder 100 ? in diameter. The surface to volume ratio of the tissue interspaces in the same fibre was 170 ?-1. 7. It was concluded that the total sarcolemmal area in this tissue is great enough so that the specific membrane capacitance could be about 1 ?F/cm2 and the specific membrane resistance 20,000 ? cm2. ImagesABPlate 2AB PMID:5016037

Mobley, Bert A.; Page, Ernest

1972-01-01

372

Fibre-optic laser-assisted infrared tumour diagnostics (FLAIR)  

NASA Astrophysics Data System (ADS)

Laser based fibre-optic surgery procedures are commonly used in minimal invasive surgery. Despite the development of precise and efficient laser systems there are also innovative attempts in the field of bio-medical diagnostics. As a direct result of the tissue's optical properties most applications are focused on the visible wavelength range of the spectrum. The extension of the spectrum up to the mid-infrared (IR) region will offer a broad range of possibilities for novel strategies with a view to non-invasive diagnostics in medicine. We describe a method to detect differences between diseased and normal tissues, which involve Fourier transform IR microspectroscopy and fibre-optics methods. Regions of interest on 10 µm thin tissue sections were mapped using an IR microscope in transmission mode. After IR-mapping, the samples were analysed using standard pathological techniques. Quadratic discriminant and correlation analyses were applied to the IR maps obtained allowing differentiation between cancerous and normal tissue. The use of optical fibres, transparent in the mid-IR, allowed measurements to be made in the attenuated total reflectance (ATR)-mode at a remote location. The IR sensor is in contact with the sample that shows characteristic absorption lines. The total transmission of the fibre and the sample will decrease at these lines. This method can be used to determine the absorption of a sample in a non-destructive manner. In this paper we report on our efforts to develop an IR fibre-optic sensor for tissue identification as well as to differentiate between malignant and healthy tissue in vivo. We also describe the technical design of the laboratory set-up and the results of developments made. Silver halide fibres and a special sensor tip were used for the ATR measurements on tissue specimens. The results indicate that fibre-optic IR spectrometry will be a useful tool for bio-diagnostics.

Bindig, U.; Müller, G.

2005-08-01

373

Abrasive wear performance and microstructure of laser clad WC\\/Ni layers  

Microsoft Academic Search

WC\\/Ni clad layers were produced on H13 tool steel substrates with a pulsed Nd:YAG laser and optical fibres using the injected powder technique. The effects of parameters, such as laser beam profile, WC powder shape and substrate pre-heat temperature on the clad layer microstructure and wear properties were investigated. The microhardness of the clad layers was measured using a Vickers

S. W Huang; M Samandi; M Brandt

2004-01-01

374

The Biomechanical Function of Periodontal Ligament Fibres in Orthodontic Tooth Movement  

PubMed Central

Orthodontic tooth movement occurs as a result of resorption and formation of the alveolar bone due to an applied load, but the stimulus responsible for triggering orthodontic tooth movement remains the subject of debate. It has been suggested that the periodontal ligament (PDL) plays a key role. However, the mechanical function of the PDL in orthodontic tooth movement is not well understood as most mechanical models of the PDL to date have ignored the fibrous structure of the PDL. In this study we use finite element (FE) analysis to investigate the strains in the alveolar bone due to occlusal and orthodontic loads when PDL is modelled as a fibrous structure as compared to modelling PDL as a layer of solid material. The results show that the tension-only nature of the fibres essentially suspends the tooth in the tooth socket and their inclusion in FE models makes a significant difference to both the magnitude and distribution of strains produced in the surrounding bone. The results indicate that the PDL fibres have a very important role in load transfer between the teeth and alveolar bone and should be considered in FE studies investigating the biomechanics of orthodontic tooth movement. PMID:25036099

McCormack, Steven W.; Witzel, Ulrich; Watson, Peter J.; Fagan, Michael J.; Gröning, Flora

2014-01-01

375

Rapid analysis of phthalates in beverage and alcoholic samples by multi-walled carbon nanotubes/silica reinforced hollow fibre-solid phase microextraction.  

PubMed

A novel procedure based on multi-walled carbon nanotubes (MWCNTs)/silica reinforced hollow fibre solid-phase microextraction combined with gas chromatography-mass spectrometry has been developed to analyse trace phthalate acid esters in beverage and alcoholic samples. Because of their excellent adsorption capability towards hydrophobic compounds, functionalized MWCNTs, acting as solid-phase sorbent, were co-deposited with silica particles in the pores of polypropylene hollow fibre through a layer-by-layer self-assembly technique. The parameters influencing the extraction efficiency, such as pH values and ionic strength of sample solution, extraction time, temperature and desorption solvent were optimised. Recoveries for phthalates at spiking levels in different matrices were satisfactory (between 68% and 115%). Moreover, the results were further confirmed by comparing them with those obtained using a solvent extraction method according to the national standard of China. PMID:23993540

Li, Jia; Su, Qiong; Li, Ke-Yao; Sun, Chu-Feng; Zhang, Wen-Bo

2013-12-15

376

Microdysgenesis with abnormal cortical myelinated fibres in temporal lobe epilepsy: a histopathological study with calbindin D-28-K immunohistochemistry.  

PubMed

Microdysgenesis is a microscopic cortical malformation reported to occur with varying incidence in surgical lobectomies from patients with temporal lobe epilepsy (TLE). It may act as a substrate for the seizures. Four patients are reported with TLE, hippocampal sclerosis and cortical microdysgenesis which was also characterized by the presence of abnormal myelinated fibres running tangentially in the superficial cortical laminae and closely associated with abnormal clusters of neurones. Similar abnormal cortical fibres have been described in other malformations of cortical development including polymicrogyria and focal cortical dysplasia and it is therefore likely that these fibres represent part of the microdysgenetic malformation not hitherto reported. The possibility is discussed that they may also be of functional significance in terms of influencing local seizure propagation and the secondary cortical neuronal loss observed, predominantly affecting layer II. Studies of calbindin interneuronal populations showed preservation of these cells in the microdysgenetic cortex, when compared with non-malformed temporal lobes, despite an overall reduction in cortical neuronal density. In addition, prominent numbers of neurogliaform calbindin-positive nerve cells were observed in the microdysgenesis cases and the nature of these cells is speculated upon. PMID:10886683

Thom, M; Holton, J L; D'Arrigo, C; Griffin, B; Beckett, A; Sisodiya, S; Alexiou, D; Sander, J W

2000-06-01

377

Functional capacities of tactile afferent fibres in neonatal kittens  

PubMed Central

1. Responses were recorded from individual tactile afferent fibres isolated by microdissection from the median nerve of pentobarbitone-anaesthetized neonatal kittens (1-5 days post-natal age). Experiments were also conducted on adult cats to permit precise comparisons between neonatal and adult fibres. 2. Neonatal fibres with receptive fields on the glabrous skin of the foot pads were classified into two broad groups, a slowly adapting class (40%) which responded throughout a 1 sec period of steady indentation and a rapidly adapting or dynamically sensitive class comprising 60% of units. Fibres in these two groups had overlapping conduction velocities in the range 4·3 to 7·5 m/sec and were believed to be the developing Group II afferents of the adult. 3. Neonatal slowly adapting fibres qualitatively resembled their adult counter-parts. They displayed graded stimulus-response relations which, over the steepest segment of the curves, had mean slopes of 15·7 impulses/100 ?m of indentation. Plateau levels of response were often reached at amplitudes of skin indentation of < 0·5-0·7 mm. 4. Dynamically sensitive fibres with receptive fields on the glabrous skin were studied using sinusoidal cutaneous vibration which in the adult enables them to be divided into two distinct classes. However, in the neonate, they formed a continuum whether criteria of sensitivity or responsiveness were used. 5. In response to vibration neonatal fibres differed from adult ones according to the following quantitative indices: (i) sensitivity as measured by both absolute thresholds and thresholds for a 1: 1 pattern of response, both of which were higher in the neonate than in the adult at all frequencies > 50 Hz and differed by an order of magnitude at frequencies ? 200 Hz; (ii) responsiveness based on the mean impulse rate evoked at a fixed amplitude of cutaneous vibration; (iii) band width of vibratory sensitivity which in the neonate was confined to approximately 5-300 Hz whereas in the two classes of adult units it covered the range 5-800 Hz; (iv) capacity for coding information about vibration frequency. Impulse activity of neonatal fibres was less tightly phase-locked to the vibratory stimulus and showed a poorer reflection of the periodic nature of the vibratory stimulus than impulse patterns of adult units. 6. The results reveal that tactile receptors and afferent fibres in the neonate are functionally immature. Their restricted coding capacities suggest that peripheral tactile sensory mechanisms impose limits on the ability of the new-born animal to derive information about its tactile environment. PMID:7205668

Ferrington, D. G.; Rowe, Mark J.

1980-01-01

378

Low Temperature Thermal Conductivity of Woven Fabric Glass Fibre Composites  

SciTech Connect

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

Kanagaraj, S.; Pattanayak, S. [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur, West Bengal, 721 302 (India)

2004-06-28

379

Heat production by single fibres of frog muscle.  

PubMed

The heat produced during contractions of preparations consisting of one or a few muscle fibres was measured for the first time. Fibres were dissected from the anterior tibialis muscles of the frog, Rana temporaria. Measurements were made with thermopiles of a design based on that described by Howarth et al. (1975). Although the fibre preparations were small, measurable signals could be recorded because the heat capacity of the thermopiles was also small. The output of the thermopile was amplified by a galvanometer circuit. In all the experiments the ends of the preparation were held in a fixed position during stimulation ("isometric'). Observations were made of heat production during twitches and tetanic contractions. The heat produced in a twitch of a single fibre depended on the stimulus strength in an all-or-nothing way. The results show that the amount of heat produced in individual twitches is fairly constant at different temperatures in the range 3-15 degrees C. In contrast, the heat produced in tetanic contractions is considerably greater at higher temperatures. The time course of heat production in a tetanus was influenced by temperature such that the early rapid phase of heat production was less obvious at the higher temperature. The quantities of heat produced by fibre preparations were in reasonable agreement with those produced by whole muscles when the comparison was made on the basis of heat produced per g wet weight of tissue. PMID:6602811

Curtin, N A; Howarth, J V; Woledge, R C

1983-04-01

380

Z-Pinch Experiments with Styrofoam Fibres and Plasmajets  

NASA Astrophysics Data System (ADS)

Z-pinch plasmas created from fibres are less prone to macroscopic instabilities than predicted by ideal MHD theory. However, solid fibre experiments at the pulseline KALIF (2 MV, 900 kA) gave disappointing results with respect to driver-load coupling and pinch plasma confinement. High power discharges led to current leaks and plasma expansion presumably due to lacking initial conductivity and compressibility. Therefore two alternative schemes have been investigated: Solid fibres were replaced by styrofoam fibres with about 1 % solid density and plasmajets of a deuterium-argon mixture. Analyses of the experimental results showed no major differences between styrofoam and solid fibres. However, the plasmajet experiments resulted in significant improvements with respect to the initial discharge behaviour. Unfortunately, severe pinch disruptions about 40 ns after discharge initiation prevented pinch formation and confinement. The high electric field of the pulseline KALIF and the low density of the jet plasma (E/n > 10-15 Vm2) resulted in runaway electrons and plasma erosion rather than in magnetic confinement to the pinch.

Stein, S.; Decker, G.; Kies, W.; Röwekamp, P.; Ziethen, G.; Baumung, K.; Bluhm, H.; Ratajczak, W.; Rusch, D.; Bayley, J. M.

1994-03-01

381

Plastic Fibre Reinforced Soil Blocks as a Sustainable Building Material  

NASA Astrophysics Data System (ADS)

Solid waste management, especially the huge quantity of waste plastics, is one of the major environmental concerns nowadays. Their employability in block making in the form of fibres, as one of the methods of waste management, can be investigated through a fundamental research. This paper highlights the salient observations from a systematic investigation on the effect of embedded fibre from plastic waste on the performance of stabilised mud blocks. Stabilisation of the soil was done by adding cement, lime and their combination. Plastic fibre in chopped form from carry bags and mineral water bottles were added (0.1% & 0.2% by weight of soil) as reinforcement. The blocks were tested for density, and compressive strength, and observed failure patterns were analysed. Blocks with 0.1% of plastic fibres showed an increase in strength of about 3 to 10%. From the observations of failure pattern it can be concluded that benefits of fibre reinforcement includes both improved ductility in comparison with raw blocks and inhibition of crack propogation after its initial formation.

Prasad, C. K. Subramania; Nambiar, E. K. Kunhanandan; Abraham, Benny Mathews

2012-10-01

382

Synchronistic preparation of fibre-like SiC and cubic-ZrO{sub 2}/SiC composite from zircon via carbothermal reduction process  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Zircon carbothermal reduction was carried out in a tailor-made device at high-temperature air atmosphere. ? Fibre-like SiC and cubic-ZrO{sub 2}/SiC composite were obtained synchronically. ? Zirconium and silicon in zircon ore was initial separated. ? [SiO{sub 4}] was mutated to fibre-like SiC, while [ZrO{sub 8}] was transformed to cubic ZrO{sub 2}. ? The SiC were surprisingly enriched in the reducing atmosphere charred coal particles layers by gas–solid reaction. -- Abstract: Fibre-like SiC and cubic-ZrO{sub 2}/SiC composite were prepared respectively from zircon with yttrium oxide addition via carbothermal reduction process at 1600 °C for 4 h in an air atmosphere furnace, where the green samples were immerged in charred coal particles inside a high-temperature enclosed corundum crucible. The reaction products were characterized by XRD, XRF, XPS and SEM. The results indicate that ZrO{sub 2} in the products was mainly existed in the form of cubic phase. The reacted samples mainly contain cubic ZrO{sub 2}, ?-SiC and trace amounts of zircon, with the SiC accounting for 14.8 wt%. Furthermore, a large quantity of fibre-like SiC was surprisingly found to concentrate in the charred coal particles layers around the samples. This study obtains fibre-like SiC and cubic-ZrO{sub 2}/SiC composite synchronically from zircon via carbothermal reduction process, which also bring a value-added high-performance application for natural zircon.

Xu, Youguo; Liu, Yangai [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China)] [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Huang, Zhaohui, E-mail: huang118@cugb.edu.cn [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China)] [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Fang, Minghao [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China)] [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China); Hu, Xiaozhi [School of Mechanical and Chemical Engineering, University of Western Australia, Perth, WA 6009 (Australia)] [School of Mechanical and Chemical Engineering, University of Western Australia, Perth, WA 6009 (Australia); Yin, Li; Huang, Juntong [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China)] [School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083 (China)

2013-01-15

383

Applications of artificial neural network on signal processing of optical fibre pH sensor based on bromophenol blue doped with sol–gel film  

Microsoft Academic Search

In this paper, the applications of artificial neural network (ANN) in signal processing of optical fibre pH sensor is presented. The pH sensor is developed based on the use of bromophenol blue (BPB) indicator immobilized in a sol–gel thin film as a sensing material. A three layer feed-forward network was used and the network training was performed using the back-propagation

Faiz Bukhari Mohd Suah; Musa Ahmad; Mohd Nasir Taib

2003-01-01

384

Fibre-Optic Endoscopy In Clinical Practice  

NASA Astrophysics Data System (ADS)

Man's curiosity has led him to seek methods of investigating the inner workings of the human body, but it is only recently that it has become possible to properly visualise the inner cavities of the human frame. Physiologists such as William Beaumont have occasionally had the opportunity to see the function of the gastrointestinal tract, in this case the gastric fistula of Alexis St Martin who was injured following an accidental firearm explosion. Rigid instruments, down which lights are shone, can be used to visualise the respiratory passages, the gullet, the rectum, and the bladder, and in the past artists were employed to record what was seen. Such instruments are still in use, although light from a powerful source is now conducted down the instrument using a fibreoptic bundle. The first semi-flexible instrument which could be inserted into the stomach and used to visualise its walls was developed by Schindler and Wolf in Germany in 1932. The optics consisted of a series of convex-lenses, transmitting an image back to the eye, but again the view obtained was limited and since its optics were side viewing, the gullet could not be viewed. The advent of fibre-optics revolutionised the situation, and the first fibrescope conducting the image up a fibreoptic bundle was a side-viewing instrument, developed by Hirschowitz, Curtiss, Peters and Pollard by 1958, and used for viewing the stomach. Since those pioneering days, the development of fibrescopes for viewing every potential cavity in the human body has proceeded in leaps and bounds.

Jourdan, Martin H.

1985-08-01

385

Coherent reflectometer with a two-fibre scattered-light interferometer  

SciTech Connect

We have designed and implemented a new fibre-optic phase-sensitive coherent reflectometer configuration, which allows one to avoid signal fading owing to the use of a two-fibre scattered-light interferometer. (fiber optics)

Vdovenko, V S; Gorshkov, B G; Zazirnyi, M V; Kulakov, A T; Kurkov, Andrei S; Paramonov, Vladimir M

2011-02-28

386

Dual Fizeau heterodyne interferometry for high-precision fibre-optic displacement sensor  

Microsoft Academic Search

In this paper, fibre-optic interferometry of single-mode laser diode continuous wave frequency modulation (FMCW) is discussed carefully, and an approach to dual Fizeau heterodyne interferometry for a fibre-optic displacement sensor is put forward theoretically.

Yanzhou Zhou; Xifu Qiang

1998-01-01

387

Transports along paths in fibre bundles. II. Ties with the theory of connections and parallel transports  

E-print Network

A review of the parallel transport (translation) in fibre bundles is presented. The connections between transports along paths and parallel transports in fibre bundles are examined. It is proved that the latter ones are special cases of the former.

Bozhidar Z. Iliev

2005-03-01

388

What holds paper together: Nanometre scale exploration of bonding between paper fibres  

NASA Astrophysics Data System (ADS)

Paper, a man-made material that has been used for hundreds of years, is a network of natural cellulosic fibres. To a large extent, it is the strength of bonding between these individual fibres that controls the strength of paper. Using atomic force microscopy, we explore here the mechanical properties of individual fibre-fibre bonds on the nanometre scale. A single fibre-fibre bond is loaded with a calibrated cantilever statically and dynamically until the bond breaks. Besides the calculation of the total energy input, time dependent processes such as creep and relaxation are studied. Through the nanometre scale investigation of the formerly bonded area, we show that fibrils or fibril bundles play a crucial role in fibre-fibre bonding because they act as bridging elements. With this knowledge, new fabrication routes can be deduced to increase the strength of an ancient product that is in fact an overlooked high-tech material.

Schmied, Franz J.; Teichert, Christian; Kappel, Lisbeth; Hirn, Ulrich; Bauer, Wolfgang; Schennach, Robert

2013-08-01

389

Subchronic inhalation study of stone wool fibres in rats.  

PubMed

Pathology results after subchronic inhalation in rats of three separate fibres representing the new biosoluble high-aluminium low-silica HT type stone wool are given, and the results were compared with the results from a similar study done with the traditional stone wool MMVF21. Male Wistar rats were exposed at one exposure level by nose-only inhalation to well-characterized fibre test atmospheres. The fibres had been size selected to be largely rat respirable. The target dose was an exposure to 150 long fibres/ml (length>20 microm) in each group, and this dose was achieved for all the fibres. The negative control groups were exposed to filtered air. The exposure duration was 6 h/day, 5 days/week for 3 months, with a subsequent non-exposure period lasting 3 months. The rats were killed 1 week after the last exposure and additional post-exposure kills were performed at 1.5 and 3 months to monitor the progression of pulmonary change and fibre numbers in the lung. The assessments included bronchoalveolar lavage fluid (BALF) for evaluation of inflammatory response (e.g. protein content, enzymes, increase in polymorphonuclear leucocytes) and measurement of cell proliferation, assessment of early fibrosis through histological examination and comparison of body weight and lung lobe weights. After exposure of rats to the new biosoluble fibres no biologically significant effects were observed except that a statistically significant increase in lung weight was observed up to 1.5 months post-exposure in all three treatment groups. At 3 months post-exposure, the small increase was no longer significant. The increase in lung weight was still present in the MMVF21 group at the 3 months post-exposure kill. After 3 months exposure, lung retention of long fibres (length>20 microm) varied from 0.4 to 5.2 x 10(6) per lung for the biosoluble fibres. At 3 months post-exposure, the long fibre concentration in the lungs had decreased to 1-7% of this figure. The fibre with the relatively highest biopersistence (RIF41001) showed the highest fibre retention. The retention of the more biopersistent traditional stone wool MMVF21 was 5.7 x 10(6) per rat lung after 3 months exposure and had decreased to 64% of this figure at 3 months post-exposure. There was no clear difference in the bronchoalveolar lavage fluid cell concentration and percentage of cells between MMVF21 and the HT groups. Fibre inhalation caused a significant increase after 3 months in all the biochemical parameters measured in the BALF. Cell proliferation was enhanced at the end of exposure for MMVF21 for all three labelling indices, but only for the bronchiolar epithelium in the RIF41001 group and for alveolar parenchymal cells in the RIF43006-1 group. At the termination of the 3 month exposure period, as well as after 1.5 and 3 month recovery periods, minimal morphological changes were diagnosed in the biosoluble fibre groups. These changes included alveolar macrophage aggregation and/or microgranulomas at the bronchiolar-alveolar junction in the few rats affected. No fibrogenic potential was noted for any of the three fibres. No clear-cut difference between the different biosoluble fibre types was noted. In the MMVF21 group, minimal interstitial fibrosis was observed that gradually decreased after the 1.5 and 3 month non-exposure periods. In this study, the pathological changes found in the lungs of exposed rats were in accordance with the pathology previously reported from full lifespan inhalation studies. This may indicate that for fibres belonging to the man-made vitreous fibres group a well conducted biopersistence study is sufficient to predict possible pathogenic effects for new fibre types. The biological parameters examined in a 90 day study may indicate little additional information to contribute to the prediction of the outcome of carcinogenicity studies. PMID:14990431

Kamstrup, O; Ellehauge, A; Bellmann, B; Chevalier, J; Davis, J M G

2004-03-01

390

Polyaniline and polyaniline–carbon nanotube composite fibres as battery materials in ionic liquid electrolyte  

Microsoft Academic Search

New battery materials are presented that consist of either a solid polyaniline (PANi) fibre or the same fibre containing carbon nanotubes (CNTs). An ionic liquid ethylmethyl imidazolium bis(trifluoromethanesulfonyl) amide (EMI.TFSA) is used as electrolyte. The electrochemical properties of PANi and PANi\\/CNT fibres are investigated by means of cyclic voltammetry, a.c. impedance and galvanostatic charge–discharge techniques. A PANi fibre with a

C. Y. Wang; V. Mottaghitalab; C. O. Too; G. M. Spinks; G. G. Wallace

2007-01-01

391

Effects of levodropropizine on vagal afferent C-fibres in the cat.  

PubMed

1. Levodropropizine (LVDP) is an effective antitussive drug. Its effects on single-unit discharge of vagal afferent C-fibres were tested in anaesthetized cats to assess whether an inhibition of vagal C-fibres is involved in its antitussive properties. Vagal C-fibres, identified by their response to phenylbiguanide (PBG), were recorded via suction electrodes from the distal part of the cut vagus. Based on their response to lung inflation, C-fibres were classified as pulmonary (19 fibres) or non-pulmonary (6 fibres). 2. PBG increased the discharge rate of both C-fibre types and activated a respiratory reflex causing apnoea. This reflex was abolished when the second vagus nerve was cut as well, while PBG-mediated stimulation of the C-fibres was not affected by vagotomy. 3. LVDP was administered intravenously and the C-fibre response to PBG was compared with that before administration of the drug. LVDP reduced both the duration of apnoea and the response of the C-fibre to PBG. 4. Comparison of the C-fibre responses to PBG and to a mixture of PBG and LVDP revealed that the period of apnoea was shortened and the discharge rate of the C-fibre reduced when LVDP was present. 5. The LVDP-induced inhibition of the C-fibre response to PBG was on average 50% in pulmonary and 25% in non-pulmonary fibres. 6. These results suggest that LVDP significantly reduces the response of vagal C-fibres to chemical stimuli. It is, thus, likely that the antitussive effect of LVDP is mediated through its inhibitory action on C-fibres. PMID:8851501

Shams, H; Daffonchio, L; Scheid, P

1996-03-01

392

Effects of levodropropizine on vagal afferent C-fibres in the cat.  

PubMed Central

1. Levodropropizine (LVDP) is an effective antitussive drug. Its effects on single-unit discharge of vagal afferent C-fibres were tested in anaesthetized cats to assess whether an inhibition of vagal C-fibres is involved in its antitussive properties. Vagal C-fibres, identified by their response to phenylbiguanide (PBG), were recorded via suction electrodes from the distal part of the cut vagus. Based on their response to lung inflation, C-fibres were classified as pulmonary (19 fibres) or non-pulmonary (6 fibres). 2. PBG increased the discharge rate of both C-fibre types and activated a respiratory reflex causing apnoea. This reflex was abolished when the second vagus nerve was cut as well, while PBG-mediated stimulation of the C-fibres was not affected by vagotomy. 3. LVDP was administered intravenously and the C-fibre response to PBG was compared with that before administration of the drug. LVDP reduced both the duration of apnoea and the response of the C-fibre to PBG. 4. Comparison of the C-fibre responses to PBG and to a mixture of PBG and LVDP revealed that the period of apnoea was shortened and the discharge rate of the C-fibre reduced when LVDP was present. 5. The LVDP-induced inhibition of the C-fibre response to PBG was on average 50% in pulmonary and 25% in non-pulmonary fibres. 6. These results suggest that LVDP significantly reduces the response of vagal C-fibres to chemical stimuli. It is, thus, likely that the antitussive effect of LVDP is mediated through its inhibitory action on C-fibres. PMID:8851501

Shams, H.; Daffonchio, L.; Scheid, P.

1996-01-01

393

Optical fibre devices based on mode conversion in tilted SPFG and LPFG  

Microsoft Academic Search

Tilted short-period fibre gratings (SPFG) couple the LP01 core mode to contra-directional core and cladding modes and can be used as optical fibre sensors and devices, mainly in reflection. Tilted long-period fibre gratings (LPFG) couple LP01 core mode to co-directional cladding and core modes and can be used as optical fibre sensors and devices in transmission. In this work we

J. L. Arce-Diego; D. Pereda-Cubian; F. Fanjul-Velez

2005-01-01

394

A simple confocal fibre-optic laser method for intraocular lens power measurement  

Microsoft Academic Search

PurposeTo develop novel confocal fibre-optic laser method (CFOLM) for accurate and objective measuring of the dioptric power of both positive and negative intraocular lenses (IOLs).MethodsThe CFOLM principle of operation is based on a simple apertureless single-mode fibre laser confocal design. The key element is a single-mode fibre coupler that serves simultaneously as a point light source (3–5 ?m fibre diameter)

I K Ilev

2007-01-01

395

Unravelling the biodiversity of nanoscale signatures of spider silk fibres.  

PubMed

Living organisms are masters at designing outstanding self-assembled nanostructures through a hierarchical organization of modular proteins. Protein-based biopolymers improved and selected by the driving forces of molecular evolution are among the most impressive archetypes of nanomaterials. One of these biomacromolecules is the myriad of compound fibroins of spider silks, which combine surprisingly high tensile strength with great elasticity. However, no consensus on the nano-organization of spider silk fibres has been reached. Here we explore the biodiversity of spider silk fibres, focusing on nanoscale characterization with high-resolution atomic force microscopy. Our results reveal an evolution of the nanoroughness, nanostiffness, nanoviscoelastic, nanotribological and nanoelectric organization of microfibres, even when they share similar sizes and shapes. These features are related to unique aspects of their molecular structures. The results show that combined nanoscale analyses of spider silks may enable the screening of appropriate motifs for bioengineering synthetic fibres from recombinant proteins. PMID:24345771

Silva, Luciano P; Rech, Elibio L

2013-01-01

396

Small angle light scattering for a glass fibre diameter characterization  

NASA Astrophysics Data System (ADS)

The aim of the paper is to discuss the concept of a method for non-invasive, in situ characterization of a glass fibre diameter. The method involves the use of low-coherence radiation as a measurement tool. The essence of the method is to influence the spectral properties of the incident light in such a way to obtain the scattered field at a small angle easy to explain both, from the physical as well as mathematical point of view. Some numerical examples demonstrate the properties of the scattered field. To obtain the fibre diameter, direct and reverse mathematical analysis will be introduced with the aid of a solution to the Huygens-Fresnel integral. An empirical research will be aimed to demonstrate some achievements in the formation and analysis of the filed scattered on an optical fibre.

?wirniak, Grzegorz; G?omb, Grzegorz

2013-04-01

397

Actuation of shape-memory colloidal fibres of Janus ellipsoids.  

PubMed

Many natural micrometre-scale assemblies can be actuated to control their optical, transport and mechanical properties, yet such functionality is lacking in colloidal structures synthesized thus far. Here, we show with experiments and computer simulations that Janus ellipsoids can self-assemble into self-limiting one-dimensional fibres with shape-memory properties, and that the fibrillar assemblies can be actuated on application of an external alternating-current electric field. Actuation of the fibres occurs through a sliding mechanism that permits the rapid and reversible elongation and contraction of the Janus-ellipsoid chains by ~36% and that on long timescales leads to the generation of long, uniform self-assembled fibres. Colloidal-scale actuation might be useful in microrobotics and in applications of shape-memory materials. PMID:25384169

Shah, Aayush A; Schultz, Benjamin; Zhang, Wenjia; Glotzer, Sharon C; Solomon, Michael J

2015-01-01

398

Stimulated Raman Scattering Microscopy with a Robust Fibre Laser Source  

PubMed Central

Stimulated Raman Scattering microscopy allows label-free chemical imaging and has enabled exciting applications in biology, material science, and medicine. It provides a major advantage in imaging speed over spontaneous Raman scattering and has improved image contrast and spectral fidelity compared to coherent anti-Stokes Raman. Wider adoption of the technique has, however, been hindered by the need for a costly and environmentally sensitive tunable ultra-fast dual-wavelength source. We present the development of an optimized all-fibre laser system based on the optical synchronization of two picosecond power amplifiers. To circumvent the high-frequency laser noise intrinsic to amplified fibre lasers, we have further developed a high-speed noise cancellation system based on voltage-subtraction autobalanced detection. We demonstrate uncompromised imaging performance of our fibre-laser based stimulated Raman scattering microscope with shot-noise limited sensitivity and an imaging speed up to 1 frame/s. PMID:25313312

Freudiger, Christian W.; Yang, Wenlong; Holtom, Gary R.; Peyghambarian, Nasser; Xie, X. Sunney; Kieu, Khanh Q.

2014-01-01

399

Actuation of shape-memory colloidal fibres of Janus ellipsoids  

NASA Astrophysics Data System (ADS)

Many natural micrometre-scale assemblies can be actuated to control their optical, transport and mechanical properties, yet such functionality is lacking in colloidal structures synthesized thus far. Here, we show with experiments and computer simulations that Janus ellipsoids can self-assemble into self-limiting one-dimensional fibres with shape-memory properties, and that the fibrillar assemblies can be actuated on application of an external alternating-current electric field. Actuation of the fibres occurs through a sliding mechanism that permits the rapid and reversible elongation and contraction of the Janus-ellipsoid chains by ~36% and that on long timescales leads to the generation of long, uniform self-assembled fibres. Colloidal-scale actuation might be useful in microrobotics and in applications of shape-memory materials.

Shah, Aayush A.; Schultz, Benjamin; Zhang, Wenjia; Glotzer, Sharon C.; Solomon, Michael J.

2015-01-01

400

Implementation and characterization of a fibre-optic colour sensor  

NASA Astrophysics Data System (ADS)

In this paper the implementation of a fibre-optic sensor for colour detection based on reflective colour sensing is proposed. The sensor consists of three plastic optical fibres emitting red, green and blue components and one optical fibre collecting light reflected from the object. Red, green and blue LEDs are excited at different frequencies. In this way detection of the reflected signal is achieved with only one photodetector and three bandpass filters. Bandpass filters are implemented as digital IIR (infinite impulse response) filters on the microcontroller. Results obtained from the proposed sensor are compared with commercial available colour sensors and the results are satisfactory. Analyses of the sensor performance both in RGB and HSV colour space are done. The proposed solution shows that in specific applications by using the HSV model the sensor can be used both as a colour and distance sensor.

Baji?, Jovan S.; Stupar, Dragan Z.; Daki?, Bojan M.; Manojlovi?, Lazo M.; Slankamenac, Miloš P.; Živanov, Miloš B.

2014-09-01

401

Fibre positioning concept for the WEAVE spectrograph at the WHT  

NASA Astrophysics Data System (ADS)

WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in La Palma, Canary Islands, Spain. It is a multi-object "pick and place" fibre fed spectrograph with more than one thousand fibres behind a new dedicated 2° prime focus corrector, This is similar in concept to the Australian Astronomical Observatory's 2dF instrument1 with two observing plates, one of which is observing the sky while other is being reconfigured by a robotic fibre positioner. It will be capable of acquiring more than 10000 star or galaxy spectra a night. The WEAVE positioner concept uses two robots working in tandem in order to reconfigure a fully populated field within the expected 1 hour dwell-time for the instrument (a good match between the required exposure times and the limit of validity for a given configuration due to the effects of differential refraction).

Lewis, Ian J.; Dalton, Gavin B.; Brock, Matthew; Gilbert, James; Abrams, Don C.; Aguerri, J. Alfonso L.; Bonifacio, Piercarlo; Middleton, Kevin; Trager, Scott C.

2014-07-01

402

Fibre optic coupler as a detector for microfluidic applications.  

PubMed

A new construction of a fibre optic coupler is presented in the paper. Two polymer optical fibres were used to build a coupler in which coupling efficiency of optical power depends on the refractive index of liquid delivered to a microchannel formed by the fibres. The coupler was tested as a detector in saccharose concentration measurements, and was used in absorbance measurements. A red light emitting diode and a spectrometer were used as a light source and a photodetector, respectively. Experiments confirmed that the coupler can be used for the real time monitoring of the changes in the refractive index of a saccharose solution exhibiting repeatable changes in the signal, with no hysteresis. Absorbance tests were performed with a solution of bromothymol blue at different pH. PMID:12866860

Stadnik, Dorota; Dybko, Artur

2003-06-01

403

The “Egg of Columbus” for Making the World's Toughest Fibres  

PubMed Central

In this letter we present the “Egg of Columbus” for making fibres with unprecedented toughness: a slider, in the simplest form just a knot, is introduced as frictional element to dissipate additional energy and thus demonstrating the existence of a previously “hidden” toughness. The proof of concept is experimentally realized making the world's toughest fibre, increasing the toughness modulus of a commercial Endumax macroscopic fibre from 44 J/g up to 1070 J/g (and of a zylon microfiber from 20 J/g up to 1400 J/g). The ideal upperbound toughness is expected for graphene, with a theoretical value of ?105 J/g. This new concept, able of maximizing (one fold increment) the structural robustness, could explain the mysterious abundance of knot formations, in spite of their incremental energy cost and topological difficulty, in biological evolved structures, such as DNA strands and proteins. PMID:24695084

Pugno, Nicola M.

2014-01-01

404

Unravelling the biodiversity of nanoscale signatures of spider silk fibres  

NASA Astrophysics Data System (ADS)

Living organisms are masters at designing outstanding self-assembled nanostructures through a hierarchical organization of modular proteins. Protein-based biopolymers improved and selected by the driving forces of molecular evolution are among the most impressive archetypes of nanomaterials. One of these biomacromolecules is the myriad of compound fibroins of spider silks, which combine surprisingly high tensile strength with great elasticity. However, no consensus on the nano-organization of spider silk fibres has been reached. Here we explore the biodiversity of spider silk fibres, focusing on nanoscale characterization with high-resolution atomic force microscopy. Our results reveal an evolution of the nanoroughness, nanostiffness, nanoviscoelastic, nanotribological and nanoelectric organization of microfibres, even when they share similar sizes and shapes. These features are related to unique aspects of their molecular structures. The results show that combined nanoscale analyses of spider silks may enable the screening of appropriate motifs for bioengineering synthetic fibres from recombinant proteins.

Silva, Luciano P.; Rech, Elibio L.

2013-12-01

405

Biogenic silica fibre promotes carcinogenesis in mouse skin.  

PubMed

Silica fibres derived from plants are common contaminants of human diet in certain regions of the world where oesophageal cancer reaches extremely high incidences. We show here that one of these types of fibre (derived from Phalaris canariensis L) promotes the occurrence of tumours in the skin of mice initiated with a polycyclic carcinogen. Three experiments are described. In the first, the grain which bears these fibres was added to the diet. This did not result in any abnormality in any part of the gastrointestinal tract, but there was a significant induction of tumours in the skin around the mouth and nose; these were the areas of the body surface which most frequently came into contact with the grain. In the second experiment, the mice were separated from the grain by an intervening wire gauze barrier; a similar number of tumours appeared on initiated mice treated in this way. In this case, contact now occurred most frequently on the dorsal surface, which was rubbed against the gauze barrier, and it was on this surface that the tumours appeared. No tumours appeared if the grain was removed. In the third experiment, pure fibres were isolated from the surface of the grain and boiled in strong nitric acid so as to remove any organic material. When these acid-cleaned fibres were applied to the initiated skin with light pressure, they promoted carcinogenesis in the same way as croton oil. In each experiment the majority of tumours produced were benign neoplasms, together with at least one squamous carcinoma. It seems possible that the size and shape of these fibres are the critical properties determining their promoting activity. Their mean diameter is 15 microns, their modal length close to 200 microns, and they are sharply pointed with a tip diameter of 0.5 micron. PMID:6092284

Bhatt, T; Coombs, M; O'Neill, C

1984-10-15

406

Agricultural fibres for pulp and paper manufacture in developed countries  

SciTech Connect

Agricultural fibres are routinely used for the manufacture of paper products in developing countries. The agriculture (non-wood) pulp industry accounts more than 50% of the national pulp production in China and in India. In contrast, paper manufacturers of the developed countries have relied largely on wood pulp fibres since the 1950`s. During the past 3 decades, the global wood pulp production capacities has expanded substantially. There is a renewed interest to use agriculture-based fibres in place of wood, for the production of pulp and paper in developing countries. The alternative is driven, in part, by the growing shortage of commercial wood supply as caused by the over-cutting of the standing forest and the accelerated re-allocation of forest land for ecological and recreational uses. Although the shortage of wood supply can be alleviated partially by the adoption of higher-yield wood pulping technologies and by the increased use of waste paper. But ultimately, these remedial steps will be inadequate to meet the growing demand for paper products. There are several important factors which affect the use of agricultural fibres for pulp and paper manufacture in developed countries. For some on-purpose fibre crops, continued farm subsidy and repeal of certain sections of the Narcotics Act would be required. Agri-pulp production from agricultural cropping residues appears to be the most practical economic means to supplement the fibre needs of the paper industry. In the social context, agri-pulp implementation in North America would also provide lower taxes that would be accrued from the elimination of substantial annual subsidies to grain farmers from the government.

Wong, A. [Arbokem, Inc., Vancouver (Canada)

1995-11-01

407

High-performace cladding-pumped erbium-doped fibre laser and amplifier  

SciTech Connect

We report cladding-pumped erbium-doped fibre laser and amplifier configurations. Through fibre design optimisation, we have achieved a record-high laser slope efficiency, 40 % with respect to absorbed pump power ({lambda} = 976 nm), and an output power of 7.5 W. The erbium-doped fibre amplifier efficiency reaches 32 %.

Kotov, L V; Likhachev, M E; Bubnov, M M; Medvedkov, O I; Lipatov, D S; Vechkanov, N N; Guryanov, Aleksei N

2012-05-31

408

Bond between reinforcing steel fibres and magnesium phosphate\\/calcium aluminate binders  

Microsoft Academic Search

The work reported provides new information on the bond between two types of steel fibres and two different rapid strengthening matrices, magnesia phosphate and accelerated calcium aluminate. Two new methods have been developed in order to investigate:•the tensile chemical (or adhesive) bond strength between steel fibres and a cement matrix;•the durability of the steel fibre cement matrix bond when exposed

P Frantzis; R Baggott

2000-01-01

409

Nonlinear absorption and self-phase modulation in silicon optical fibres  

Microsoft Academic Search

Silicon optical fibres are generating much interest as a means to directly integrate semiconductor functionality within the fibre architecture to provide a platform for compact all optical signal processing. For example, the high optical nonlinearity of the core material opens up the potential for these fibres to be used for signal regeneration in very short device lengths. In this paper

P. Mehta; N. Healy; J. R. Sparks; T. D. Day; P. J. A. Sazio; J. V. Badding; A. C. Peacock

2011-01-01

410

Novel Fibre Bragg Grating design using Multiobjective Evolutionary Steven Manos1,2  

E-print Network

,2 and Leon Poladian2 1. Optical Fibre Technology Centre Australian Photonics CRC 2. School of Physics optimisation algorithm is applied to a Fibre Bragg Grating (optical filter) design problem. The design of the interconnecting de- vices increases. Fibre Bragg Gratings (FBG) for optical fil- ters and switching

Coello, Carlos A. Coello

411

In-situ cure monitoring using optical fibre sensors - a comparative study  

Microsoft Academic Search

This paper reports a comparative study undertaken for different types of optical fibre sensor developed to monitor the cure of an epoxy resin system. The optical fibre sensors used to monitor the cure process were based on transmission spectroscopy, evanescent wave spectroscopy and refractive index monitoring. The transmission sensor was prepared by aligning two optical fibres within a specially prepared

G. R. Powell; P. A. Crosby; D. N. Waters; C. M. France; R. C. Spooncer; G. F. Fernando

1998-01-01

412

Numerical modelling of imaging fibre bundles and their application in optical coherence tomography  

Microsoft Academic Search

Imaging fibre bundles are widely used in image transmission systems in the visible spectral range1. Their image transmission capabilities and flexibility make them interesting for OCT endoscopy2. However, cross-talk occurring between individual fibres and multimode transmission cause deterioration of the images obtained with OCT systems. In this study, a model of light propagation in a fibre bundle is developed using

Adem Saglam; Helen D. Ford; Ralph P. Tatam

2011-01-01

413

Absorption and luminescence properties of Cr{sup 4+}-doped silica fibres  

SciTech Connect

The absorption and luminescence spectra of silica fibres doped with chromium and various dopants are studied. Fibres doped with aluminium and gallium exhibit a broad (300 nm) luminescence band of Cr{sup 4+} ions at 1100 nm at room temperature. The quantum yield of luminescence is estimated to be 10{sup -4}-10{sup -5}. (optical fibres)

Dvoyrin, V V; Dianov, Evgenii M; Mashinsky, V M; Neustruev, V B [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, A N; Laptev, A Yu; Umnikov, A A; Yashkov, M V [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Vorob'ev, Nikolai S [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2001-11-30

414

Fibre Laser Using a Microchannel Based Loss Tuning Element for Refractive Index Sensing  

E-print Network

Fibre Laser Using a Microchannel Based Loss Tuning Element for Refractive Index Sensing Chengbo Mou, Birmingham, UK, B4 7ET ABSTRACT We have proposed and demonstrated a fibre laser system using a microchannel microchannel was created by femtosecond (fs) laser inscription assisted chemical etching in the cavity fibre

Neirotti, Juan Pablo

415

Gain Scheduling Control Design of an Erbium-Doped Fibre Amplifier by Pump Compensation  

E-print Network

Gain Scheduling Control Design of an Erbium-Doped Fibre Amplifier by Pump Compensation Min Ding) transmission network produces undesirable transients in the existing channels due to erbium-doped fibre the effectiveness of the gain scheduling scheme. I. INTRODUCTION Erbium-doped fibre amplifiers (EDFA's) provide low

Pavel, Lacra

416

Rumen-protected methionine supplementation and fibre production in alpacas (Vicugna pacos).  

PubMed

Sulphur-containing amino acids are a crucial requirement for fibre production and may be supplemented in the diet of fibre-producing animals to stimulate fibre growth. The alpaca fibre industry is a developing industry in Australia with high variability in fibre production. To date, there is no evidence whether supplementing the diet of alpacas with sulphur amino acids improves fibre production. We hypothesised that supplementation with the rumen-protected sulphur amino acid, methionine would increase fibre growth in alpacas. Three groups of eight huacaya alpaca wethers were fed daily a maintenance diet supplemented with 0, 2 or 4?g of rumen-protected methionine for 7?weeks. Fibre samples were taken at the beginning and end of the study with a blood sample taken by jugular venipuncture prior to feeding on the first day of each week. Methionine supplementation had no effect on fibre diameter (p?=?0.92), fibre length (p?=?0.91) or fibre yield (p?=?0.33). The change of season over the study affected plasma glucose (p?fibre diameter (p?

Moore, K E; Maloney, S K; Vaughan, J L; Milton, J T B; Blache, D

2013-12-01

417

Carob pulp preparation rich in insoluble fibre lowers total and LDL cholesterol in hypercholesterolemic patients  

Microsoft Academic Search

Summary. Background: Recently, insoluble fibre from carob pulp has been found to affect blood lipids in animals in a similar manner as soluble dietary fibre. Aim of the study: To investigate whether a carob pulp preparation containing high amounts of insoluble fibre has a beneficial effect on serum cholesterol in humans. Methods: Volunteers (n = 58) with hypercholesterolemia were recruited

H. J. F. Zunft; W. Lüder; A. Harde; B. Haber; H. J. Graubaum; C. Koebnick; J. Grünwald

2003-01-01

418

New equation of turbulent fibre suspensions and its solution and application to the pipe flow  

NASA Astrophysics Data System (ADS)

The mean motion equation of turbulent fibre suspensions and the equation of probability distribution function for mean fibre orientation are derived. The successive iteration for calculating the mean orientation distribution of fibres and the mean and fluctuation-correlated quantities of suspensions is presented. The equations and their solutions are applied to a turbulent pipe flow of fibre suspensions and a corresponding experiment is performed. It is found that the theoretical and experimental results are in good agreement with each other. The obtained results for turbulent pipe flow of fibre suspensions show that the flow rate of fibre suspensions is large under the same pressure drop in comparison with the rate of Newtonian flow in the absence of fibre suspensions. Fibres play an important role in reducing the flow drag. The amount of reduction in drag augments with the increase of the concentration of the fibre mass. The relative turbulent intensity and Reynolds stress in the fibre suspensions are smaller than those in the Newtonian flow under the same condition, which illustrates that the fibres have an influence on suppressing the turbulence. The amount of suppression is directly proportional to the concentration of the fibre mass.

Lin, Jian-Zhong; Li, Jun; Zhu, Li; James, Olson A.

2005-06-01

419

Evaluation of asbestos fibre content in discharge air from a portable canister vacuum cleaner  

E-print Network

greater than 5 microns in length ranged from 6 to 56 fibres per cubic oentimeter, An analysis of variance performed on the fibre count data indicated that fibre concentra- tions are related to filter usage and arrangement, AC KN OWL ED GEMENTS I wish.... . . ~ , ~ , . . . , . . . , . 30 Sampling. . . , Counting. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 33 Data Analysis. . . , . ~ , ~ . . . , , . . . , . . . , . . . , . . . , . . . , . . . , . . . , 35 RESULTS. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ a CONCLUSIONS' . . . . i. e...

Wilson, James Turner

1975-01-01

420

10 Structural Characterisation of Kraft Pulp Fibres and Their Nanofibrillated Materials for Biodegradable Composite Applications  

E-print Network

The utilization of wood pulp fibres in composite materials has gained major interest during the last years. One of the major motivations has been the potential of wood pulp fibres and their nanofibrillated derivatives for increasing the mechanical properties of some materials. However, in order to exploit the full potential of wood pulp fibres and cellulose nanofibrils

Gary Chinga-carrasco; Arttu Miettinen; Cris L. Luengo Hendriks; E. Kristofer Gamstedt

421

Surface microstructure of a Kevlar aramid fibre studied by direct atomic force microscopy  

Microsoft Academic Search

The surface morphology and molecular arrangement of a Kevlar® aramid fibre (coded Fibre A, from E. I. DuPont de Nemours and Co.) were studied by atomic force microscopy (AFM). Pleats parallel to the fibre axis have been observed. At nanometre scale, the polymer chains display several different arrangements from the reported crystalline structures for the bulk polymer especially in the

Jean-Baptiste Donnet; Tong Kuan Wang

1997-01-01

422

The tensile and fatigue behaviour of Kevlar-49 (PRD49) fibre  

Microsoft Academic Search

The tensile, creep and tension-tension fatigue properties of Kevlar-49 fibre (formerly known as PRD-49) have been determined. The fracture morphology of the fibre has been examined and is shown to be complex due to considerable splitting. The fibre quickly stabilizes under a steady load but failure due to creep can occur when it is loaded very near to its simple

A. R. Bunsell

1975-01-01

423

Raman fibre lasers emitting at a wavelength above 2 {mu}m  

SciTech Connect

Single-mode Raman fibre lasers emitting a few hundreds of millwatts at wavelengths of 2.0 and 2.2 {mu}m are built for the first time. Laser emission was amplified in a fibre with a germanium dioxide core and a silica cladding pumped by an Er/Yb-doped fibre laser. (lasers)

Dianov, Evgenii M; Bufetov, Igor' A; Mashinsky, V M; Neustruev, V B; Medvedkov, O I; Shubin, Aleksei V; Mel'kumov, Mikhail A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, A N; Khopin, V F; Yashkov, M V [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2004-08-31

424

Pump radiation distribution in multi-element first cladding laser fibres  

SciTech Connect

Pump radiation transfer is studied experimentally in multi-element first cladding laser fibres. A model of this process is proposed, which is in good agreement with experimental results. An all-fibre single-mode cw ytterbium laser based on a three-element first cladding fibre with an output power of 100W is fabricated. (lasers)

Mel'kumov, Mikhail A; Bufetov, Igor' A; Bubnov, M M; Shubin, Aleksei V; Semenov, S L; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2005-11-30

425

Monthly variation in crude protein, fibre fractions and mineral composition of paragrass (Brachiaria mutica (Forsk)  

E-print Network

Monthly variation in crude protein, fibre fractions and mineral composition of paragrass variation in crude protein, fibre fractions and mineral composition of forages collected in the pastures. The samples were dried, ground and analysed for crude protein (CP), neutral detergent fibre (NDF), acid

Paris-Sud XI, UniversitƩ de

426

Kevlar 49 fibres: correlation between tensile strength and X-ray diffraction peak positions  

Microsoft Academic Search

The exceptional properties and the consequent extensive applications of Kevlar fibres are well known [1]. Some of the applications utilize the high tensile modulus of the fibres and other applications depend on the high tensile strength. It has been observed that exposure to thermal environments can introduce changes in the tensile characteristics of the fibre [2-4]. In particular, the thermally

M. Shubha; H. V. Parimala; Kalyani Vijayan

1991-01-01

427

Identification of ancient textile fibres from Khirbet Qumran caves using synchrotron radiation microbeam diffraction  

Microsoft Academic Search

Archaeological textiles fragments from the caves of Qumran in the Dead Sea region were investigated by means of X-ray microbeam diffraction on single fibres. This non-destructive technique made the identification of the used plant textile fibres possible. Apart from bast fibres (mainly flax), cotton was identified which was most unexpected in the archaeological context.

Martin Müller; Bridget Murphy; Manfred Burghammer; Christian Riekel; Mark Roberts; Miroslav Papiz; David Clarke; Jan Gunneweg; Emmanuel Pantos

2004-01-01

428

SOLITONS AND OPTICAL FIBERS: Self-Q-switched ytterbium-doped cladding-pumped fibre laser  

NASA Astrophysics Data System (ADS)

A self-Q-switched ytterbium-doped double-clad fibre laser is described. A samarium-doped fibre is used as a filter for protecting a pump source. A fibre coupler is employed to obtain a nonlinear feedback. The mechanism of pulse formation in the laser is considered, and the dependence of its output pulse on the coupler parameters is studied.

Grukh, Dmitrii A.; Kurkov, Andrei S.; Razdobreev, I. M.; Fotiadi, A. A.

2002-11-01

429

Plasma behind the front of a damage wave and the mechanism of laser-induced production of a chain of caverns in an optical fibre  

SciTech Connect

The properties of the plasma behind the front of a damage wave generated by laser radiation in an optical fibre are considered. A plasma with a low degree of ionisation but a relatively high electron density is shown to emerge. However, the high absorption coefficient of laser radiation at a temperature of the order of 2000 K cannot be attributed to the presence of bremsstrahlung. The production of a chain of uniformly spaced caverns during the laser damage of the optical fibre is qualitatively explained. It is shown that this effect cannot be explained by the capillary Rayleigh instability because of the high viscosity of the glass. It is found that the fibre core deformation by a high pressure leads to an increase of the fibre volume sufficient to account for the emergence of the caverns after cooling. It is assumed that the periodicity of caverns is caused by the instability of a new type. A high-density double electrical-charge layer is produced at the plasma-liquid interface. Due to the repulsion of similar charges, the surface tends to increase, resulting in the instability development responsible for the production of the chain of caverns. (interaction of laser radiation with matter. laser plasma)

Yakovlenko, Sergei I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2004-08-31

430

Optical turbulence and spectral condensate in long fibre lasers  

PubMed Central

We study numerically optical turbulence using the particular example of a recently created, ultra-long fibre laser. For normal fibre dispersion, we observed an intermediate state with an extremely narrow spectrum (condensate), which experiences instability and a sharp transition to a fluctuating regime with a wider spectrum. We demonstrate that the number of modes has an impact on the condensate's lifetime. The smaller the number of modes, the more resistant is the condensate to perturbations. Experimental results show a good agreement with numerical simulations. PMID:22870062

Turitsyna, E. G.; Falkovich, Gregory; El-Taher, Atalla; Shu, Xuewen; Harper, Paul; Turitsyn, Sergei K.

2012-01-01

431

Recent advances in fibre lasers for nonlinear microscopy  

NASA Astrophysics Data System (ADS)

Nonlinear microscopy techniques developed over the past two decades have provided dramatic new capabilities for biological imaging. The initial demonstrations of nonlinear microscopies coincided with the development of solid-state femtosecond lasers, which continue to be the dominant light source for applications of nonlinear microscopy. Fibre lasers offer attractive features for biological and biomedical imaging, and recent advances are promising for the development of high-performance sources with the potential for realizing integrated instruments that are robust and inexpensive. This Review discusses recent advances, and identifies challenges and opportunities for fibre lasers in nonlinear bioimaging.

Xu, C.; Wise, F. W.

2013-11-01

432

A fibre optic chemical sensor for the detection of cocaine  

NASA Astrophysics Data System (ADS)

A fibre-optic chemical sensor for the detection of cocaine has been developed, based on a molecularly imprinted polymer (MIP) containing a fluorescein moiety as the signalling group. The fluorescent MIP was formed and covalently attached to the distal end of an optical fibre. The sensor exhibited an increase in fluorescence intensity in response to cocaine in the concentration range of 0 - 500 ?M in aqueous acetonitrile mixtures with good reproducibility over 24 h. Selectivity for cocaine over others drugs has also been demonstrated.

Nguyen, T. Hien; Sun, Tong; Grattan, Kenneth T. V.; Hardwick, S. A.

2010-09-01

433

Liquid level sensor based on an excessively tilted fibre grating  

NASA Astrophysics Data System (ADS)

We propose and demonstrate an optical liquid level sensor based on the surrounding medium refractive index (SRI) sensing using an excessively tilted fibre grating (ETFG). When the ETFG submerged in water, two sets of cladding modes are coupled, corresponding to air- and water-surrounded grating structures, respectively. The coupling strengths of the two sets of cladding modes evolve with the submerging length of the grating, providing a mechanism to measure the liquid level. Comparing with long-period fibre grating based liquid level sensor, the ETFG sensor has a much higher SRI responsivity for liquids with refractive index around 1.33 and a lower thermal cross sensitivity.

Mou, Chengbo; Zhou, Kaiming; Yan, Zhijun; Fu, Hongyan; Zhang, Lin

2013-09-01

434

Steady-state heating of active fibres under optical pumping  

SciTech Connect

We have measured the temperature in the core of rare-earth-doped optical fibres under lasing conditions at high optical pump powers using a fibre Mach - Zehnder interferometer and probe light of wavelength far away from the absorption bands of the active ions. From the observed heating kinetics of the active medium, the heat transfer coefficient on the polymer cladding - air interface has been estimated. The temperature of the active medium is shown to depend on the thermal and optical properties of the polymer cladding. (fiber and integrated optics)

Gainov, V V; Shaidullin, R I; Ryabushkin, Oleg A

2011-07-31

435

Further studies of calcium phosphate growth on phosphorylated cotton fibres  

Microsoft Academic Search

Further studies using scanning electron microscopy\\/energy dispersive X-ray analysis (SEM\\/EDX), micro-Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques of calcium phosphate growth on Ca(OH)2-treated urea\\/H3PO3- and urea\\/H3PO4-modified cotton fibres are reported. In the case of the Ca(OH)2-treated urea\\/H3PO3-modified fibres which have been reported in an earlier paper,

M. R. Mucalo; Y. Yokogawa; T. Suzuki; Y. Kawamoto; F. Nagata; K. Nishizawa

1995-01-01

436

The force bearing capacity of frog muscle fibres during stretch: its relation to sarcomere length and fibre width  

PubMed Central

Single fibres isolated from the anterior tibialis muscle of Rana temporaria were tetanized (0.9-1.8 °C) while a marked (?1 mm) segment was held at constant length by feedback control. Force enhancement was produced by applying a controlled stretch ramp to the fibre segment during the tetanus plateau, the steady force reached during stretch being used as a measure of the maximum force that the myosin cross-bridges can hold before they detach. The amplitude of force enhancement during stretch did not vary in proportion to the isometric force as the sarcomere length was changed, maximum force enhancement being attained near 2.4 ?m sarcomere length compared with 2.0 ?m for the isometric force. The influence of fibre width on the force enhancement-sarcomere length relationship was evaluated by normalizing force enhancement to the tetanic (pre-stretch) force in this way allowing for the differences in myofilament overlap at the various lengths. The amplitude of force enhancement (normalized to the tetanic force) increased by approximately 70 % as the relative width of the myofilament lattice was reduced from a nominal value of 1.05 at a sarcomere length of 1.8 ?m to 0.85 at a sarcomere length of 2.8 ?m. Changes in fibre width equivalent to those produced by altering the sarcomere length were produced by varying the tonicity of the extracellular medium. Force enhancement, normalized to the control isometric force at each tonicity, exhibited a width dependence that agreed well with that described in the previous point. Stretch ramps applied to frog skinned muscle fibres during calcium-induced contracture likewise resulted in a greater force enhancement during stretch after reducing the fibre width by osmotic compression. The results suggest that the strength of binding of the myosin cross-bridges, unlike the isometric force, varies with the lateral distance between the myofilaments. PMID:10457067

Edman, K A P

1999-01-01

437

Dietary fibre intake and risk of ischaemic and haemorrhagic stroke in the UK Women's Cohort Study.  

PubMed

Background:Stroke risk is modifiable through many risk factors, one being healthy dietary habits. Fibre intake was associated with a reduced stroke risk in recent meta-analyses; however, data were contributed by relatively few studies, and few examined different stroke types.Methods:A total of 27?373 disease-free women were followed up for 14.4 years. Diet was assessed with a 217-item food frequency questionnaire and stroke cases were identified using English Hospital Episode Statistics and mortality records. Survival analysis was applied to assess the risk of total, ischaemic or haemorrhagic stroke in relation to fibre intake.Results:A total of 135 haemorrhagic and 184 ischaemic stroke cases were identified in addition to 138 cases where the stroke type was unknown or not recorded. Greater intake of total fibre, higher fibre density and greater soluble fibre, insoluble fibre and fibre from cereals were associated with a significantly lower risk for total stroke. For total stroke, the hazard ratio per 6?g/day total fibre intake was 0.89 (95% confidence intervals: 0.81-0.99). Different findings were observed for haemorrhagic and ischaemic stroke in healthy-weight or overweight women. Total fibre, insoluble fibre and cereal fibre were inversely associated with haemorrhagic stroke risk in overweight/obese participants, and in healthy-weight women greater cereal fibre was associated with a lower ischaemic stroke risk. In non-hypertensive women, higher fibre density was associated with lower ischaemic stroke risk.Conclusions:Greater total fibre and fibre from cereals are associated with a lower stroke risk, and associations were more consistent with ischaemic stroke. The different observations by stroke type, body mass index group or hypertensive status indicates potentially different mechanisms.European Journal of Clinical Nutrition advance online publication, 3 December 2014; doi:10.1038/ejcn.2014.260. PMID:25469464

Threapleton, D E; Burley, V J; Greenwood, D C; Cade, J E

2014-12-01

438

Presynaptic inhibition of optogenetically identified VGluT3+ sensory fibres by opioids and baclofen.  

PubMed

Distinct subsets of sensory nerve fibres are involved in mediating mechanical and thermal pain hypersensitivity. They may also differentially respond to analgesics. Heat-sensitive C-fibres, for example, are thought to respond to ?-opioid receptor (MOR) activation while mechanoreceptive fibres are supposedly sensitive to ?-opioid receptor (DOR) or GABAB receptor (GABABR) activation. The suggested differential distribution of inhibitory neurotransmitter receptors on different subsets of sensory fibres is, however, heavily debated. In this study, we quantitatively compared the degree of presynaptic inhibition exerted by opioids and the GABABR agonist baclofen on (1) vesicular glutamate transporter subtype 3-positive (VGluT3) non-nociceptive primary afferent fibres and (2) putative nociceptive C-fibres. To investigate VGluT3 sensory fibres, we evoked excitatory postsynaptic currents with blue light at the level of the dorsal root ganglion (DRG) in spinal cord slices of mice, expressing channelrhodopsin-2. Putative nociceptive C-fibres were explored in VGluT3-knockout mice through electrical stimulation. The MOR agonist DAMGO strongly inhibited both VGluT3 and VGluT3 C-fibres innervating lamina I neurons but generally had less influence on fibres innervating lamina II neurons. The DOR agonist SNC80 did not have any pronounced effect on synaptic transmission in any fibre type tested. Baclofen, in striking contrast, powerfully inhibited all fibre populations investigated. In summary, we report optogenetic stimulation of DRG neurons in spinal slices as a capable approach for the subtype-selective investigation of primary afferent nerve fibres. Overall, pharmacological accessibility of different subtypes of sensory fibres considerably overlaps, indicating that MOR, DOR, and GABABR expressions are not substantially segregated between heat and mechanosensitive fibres. PMID:25599445

Honsek, Silke D; Seal, Rebecca P; Sandkühler, Jürgen

2015-02-01

439

Whispering Gallery Modes in Standard Optical Fibres for Fibre Profiling Measurements and Sensing of Unlabelled Chemical Species  

PubMed Central

Whispering gallery mode resonances in liquid droplets and microspheres have attracted considerable attention due to their potential uses in a range of sensing and technological applications. We describe a whispering gallery mode sensor in which standard optical fibre is used as the whispering gallery mode resonator. The sensor is characterised in terms of the response of the whispering gallery mode spectrum to changes in resonator size, refractive index of the surrounding medium, and temperature, and its measurement capabilities are demonstrated through application to high-precision fibre geometry profiling and the detection of unlabelled biochemical species. The prototype sensor is capable of detecting unlabelled biomolecular species in attomole quantities. PMID:22294898

Boleininger, Anna; Lake, Thomas; Hami, Sophia; Vallance, Claire

2010-01-01

440

Multicomponent strain development in superconducting magnet coils using optical fibre grating sensors fabricated in highly linearly birefringent fibre  

NASA Astrophysics Data System (ADS)

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 development of multiple components of strain in the coils when the magnet quenched was monitored, revealing phenomena that it had not been previously possible to measure using other sensor technologies.

Chehura, Edmon; James, Stephen W.; Twin, Andrew; Domptail, Fred; Tatam, R. P.

2009-10-01