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1

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

PubMed

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

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-06-01

2

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

PubMed Central

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

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-01-01

3

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

4

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

PubMed Central

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

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

2015-01-01

5

Comparison between confocal scanning laser tomography, scanning laser polarimetry and optical coherence tomography on the ability to detect localised retinal nerve fibre layer defects in glaucoma patients  

Microsoft Academic Search

Background\\/aim:To compare the ability of confocal scanning laser tomography (CSLT), scanning laser polarimetry (SLP) and optical coherence tomography (OCT) in recognising localised retinal nerve fibre layer (RNFL) defects.Methods:51 eyes from 43 patients with glaucoma were identified by two observers as having RNFL defects visible on optic disc photographs. 51 eyes of 32 normal subjects were used as controls. Three masked

B K Windisch; P J Harasymowycz; J L See; B C Chauhan; A C Belliveau; D M Hutchison; M T Nicolela

2009-01-01

6

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

7

Optic nerve atrophy and retinal nerve fibre layer thinning following optic neuritis: Evidence that axonal loss is a substrate of MRI-detected atrophy  

Microsoft Academic Search

Magnetic resonance imaging (MRI) measures of brain atrophy are often considered to be a marker of axonal loss in multiple sclerosis (MS) but evidence is limited. Optic neuritis is a common manifestation of MS and results in optic nerve atrophy. Retinal nerve fibre layer (RNFL) imaging is a non-invasive way of detecting axonal loss following optic neuritis. We hypothesise that

S. Anand Trip; Patricio G. Schlottmann; Stephen J. Jones; Wai-Yung Li; David F. Garway-Heath; Alan J. Thompson; Gordon T. Plant; David H. Miller

2006-01-01

8

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

9

Retinal nerve fibre layer evaluation in ocular hypertensive eyes using optical coherence tomography and scanning laser polarimetry in the diagnosis of early glaucomatous defects  

Microsoft Academic Search

AimsTo evaluate and compare the accuracy of scanning laser polarimetry with variable corneal compensation (GDx-VCC) and optical coherence tomography (OCT) for detecting glaucomatous damage observed in retinal nerve fibre layer (RNFL) monochromatic photographs from ocular hypertensive (OHT) individuals with normal visual fields.MethodsA total of 181 eyes from 181 patients with intraocular pressure >22 mm Hg were enrolled in a cross-sectional,

Luis E Pablo; Antonio Ferreras; Patricio G Schlottmann

2010-01-01

10

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

11

Compensation for Retinal Vessel Density Reduces the Variation of Circumpapillary RNFL in Healthy Subjects.  

PubMed

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

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

2015-01-01

12

Compensation for Retinal Vessel Density Reduces the Variation of Circumpapillary RNFL in Healthy Subjects  

PubMed Central

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

2015-01-01

13

Retinal Nerve Fibre Layer Thickness and Contrast Sensitivity in HIV-Infected Individuals in South Africa: A Case-Control Study  

PubMed Central

Background Antiretroviral treatment (ART) has altered the spectrum of HIV-related eye disease, resulting in a lower prevalence of retinal opportunistic infections (OIs). However, abnormalities in visual function have been reported in HIV-infected individuals despite effective viral suppression and the absence of retinal OIs. These changes may be mediated by an HIV-associated ‘neuroretinal disorder’, characterized by changes in the retinal nerve fibre layer (RNFL). HIV infection may also be associated with accelerated biological aging. The aim of this study was to investigate the relationships between contrast sensitivity, RNFL thickness, HIV infection and frailty in South African adults. Methods Case-control study of 225 HIV-infected individuals without retinal OIs and 203 gender/age-matched HIV-seronegative individuals. Peri-papillary RNFL thickness was determined with spectral domain optical coherence tomography in four quadrants. CS was measured using a Pelli-Robson chart. Frailty was assessed using standard criteria. Multivariable linear and logistic regression were used to assess associations between HIV status and RNFL/CS and frailty. Results The median age of both groups was similar (41.2 vs. 41.9 years, p?=?0.37). 88% of HIV-infected individuals were receiving ART and their median CD4 count was 468 cells/?l. Adjusted CS score was lower in HIV-infected participants compared to HIV-seronegative individuals (1.76 vs. 1.82, p?=?0.002). Independent predictors of poor CS in the HIV-infected group were positive frailty status and current HIV viral load >2 log copies/ml. Lower CS score was also associated with thin temporal RNFL in HIV-infected individuals (p?=?0.04). Superior quadrant RNFL thickness was greatest in ART-naïve participants relative to the HIV-uninfected group (p-trend?=?0.04). Longer ART duration was associated with thinning of inferior and nasal RNFL quadrants (p-trend?=?0.03 and 0.04, respectively). Conclusions Contrast sensitivity is reduced in HIV-infected individuals and functionally associated with frailty and unsuppressed viraemia. This may reflect structural changes in the RNFL that are evident despite the absence of OIs. PMID:24069225

Pathai, Sophia; Lawn, Stephen D.; Weiss, Helen A.; Cook, Colin; Bekker, Linda-Gail; Gilbert, Clare E.

2013-01-01

14

Retinal nerve fibre layer, ganglion cell layer and choroid thinning in migraine with aura  

PubMed Central

Background The aim of this study was to investigate the thickness of the retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL), and choroid thickness (CT) in patients who have migraines, with and without aura, using spectral optical coherence tomography (OCT). Methods Forty-five patients who had migraines without aura (Group 1), 45 patients who had migraines with aura (Group 2), and 30 healthy participants (control group) were included in the study. Spectral OCT was used to measure the RNFL, GCL and CT values for all patients. Results The mean age of Group 1, Group 2, and the control group was 34.6?±?4.3, 32.8?±?4.9, and 31.8?±?4.6 years, respectively. The mean attack frequency was 3.6/month in Group 1 and 3.7/month in Group 2. The mean age among the groups (p?=?0.27) and number of attacks in migraine patients (p?=?0.73) were not significantly different. There was significant thinning in the RNFL and GCL in Group 2 (p?RNFL and GCL measurements between Group 1 and the control group (p?>?0.05). All groups were significantly different from one another with respect to CT, with the most thinning observed in Group 2 (p?RNFL thickness, GCC thickness and CT (p?RNFL and GCL were significantly thinner in the migraine patients with aura as compared with both the migraine patients without aura and the control subjects. In migraine, both with aura and without aura, patients’ choroid thinning should be considered when evaluating ophthalmological findings. PMID:24885597

2014-01-01

15

Optic nerve atrophy and retinal nerve fibre layer thinning following optic neuritis: evidence that axonal loss is a substrate of MRI-detected atrophy.  

PubMed

Magnetic resonance imaging (MRI) measures of brain atrophy are often considered to be a marker of axonal loss in multiple sclerosis (MS) but evidence is limited. Optic neuritis is a common manifestation of MS and results in optic nerve atrophy. Retinal nerve fibre layer (RNFL) imaging is a non-invasive way of detecting axonal loss following optic neuritis. We hypothesise that if the optic nerve atrophy that develops following optic neuritis is contributed to by axonal loss, it will correlate with thinning of the RNFL. Twenty-five patients were studied at least 1 year after a single unilateral attack of optic neuritis without recurrence, with a selection bias towards incomplete recovery. They had MR quantification of optic nerve cross-sectional area and optic nerve lesion length, as well as optical coherence tomography (OCT) measurement of mean RNFL thickness and macular volume, quantitative visual testing, and visual evoked potentials (VEPs). Fifteen controls were also studied. Significant optic nerve atrophy (mean decrease 30% versus controls), RNFL thinning (mean decrease 33% versus controls), and macular volume loss occurred in patients' affected eyes when compared with patients' unaffected eyes and healthy controls. The optic nerve atrophy was correlated with the RNFL thinning, macular volume loss, visual acuity, visual field mean deviation, and whole field VEP amplitude but not latency. These findings suggest that axonal loss contributes to optic nerve atrophy following a single attack of optic neuritis. By inference, axonal loss due to other post-inflammatory brain lesions is likely to contribute to the global MRI measure of brain atrophy in multiple sclerosis. PMID:16446103

Trip, S Anand; Schlottmann, Patricio G; Jones, Stephen J; Li, Wai-Yung; Garway-Heath, David F; Thompson, Alan J; Plant, Gordon T; Miller, David H

2006-05-15

16

Four-wave mixing in two-layer microstructure fibres  

SciTech Connect

The dispersion and waveguide characteristics of two-layer microstructure fibres with different layer filling factors are studied theoretically and experimentally. It is shown that by changing the filling factor of the second layer, it is possible to achieve lower effective cross sections for a mode and to control dispersion characteristics in a broader range. Frequency conversion during four-wave mixing with a frequency shift of 5460 cm{sup -1} (1098-687 nm) and efficiency of 0.1% at 200 mW of cw pump power was obtained for the first time in two-layer fibres fabricated for experiments. (nonlinear optical phenomena)

Yatsenko, Yu P; Levchenko, A E; Pryamikov, A D; Kosolapov, A F; Semenov, S L; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2005-08-31

17

Quantitative RNFL attenuation coefficient measurements by RPE-normalized OCT data  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

18

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. PMID:25684853

Gunes, Alime; Demirci, Seden; Umul, Ayse

2014-01-01

19

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

20

Microstructure of nylon 66 transcrystalline layers in carbon and aramid fibre reinforced composites  

Microsoft Academic Search

The effect of the transcrystalline layer on the performance of fibre reinforced composite materials has been attributed to its better elastic\\/mechanical properties, which in turn result from a higher degree of crystalline order in the transcrystalline phase. For the aramid and carbon fibre reinforced nylon 66 composites, atomic force microscopy reveals radial regularity in the transcrystalline layer relative to the

E. Wachtel; G MAROM

1996-01-01

21

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

Microsoft Academic Search

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

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

2011-01-01

22

Non-invasive fibre optic Fourier transform-infrared reflectance spectroscopy on painted layers  

Microsoft Academic Search

Fibre optic Fourier transform-infrared (FT-IR) reflectance spectroscopy has recently made it possible to perform completely non-invasive investigations on works of art and, in particular, on painted layers. The use of chalcogenide fibre optics can overcome most of the limitations due to the size of the objects under investigation, and permits the acquisition of spectra in a wide mid-IR range that

M Bacci; M Fabbri; M Picollo; S Porcinai

2001-01-01

23

Influence of the DiscFovea Angle on Limits of RNFL Variability and Glaucoma Discrimination  

E-print Network

Glaucoma Influence of the Disc­Fovea Angle on Limits of RNFL Variability and Glaucoma. Coleman,1 Joseph Caprioli,1 and Kouros Nouri-Mahdavi1 1 Glaucoma Division, Stein Eye Institute, David on limits of RNFL vari- ability and glaucoma discrimination. Invest Ophthalmol Vis Sci. 2014

Levine, Alex J.

24

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

SciTech Connect

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

Belanov, A S; Tsvetkov, S V [Moscow State University of Instrument Engineering and Informatics, Moscow (Russian Federation)

2010-02-28

25

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

26

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

PubMed

Recent years have seen an increase in the use of retinal nerve fiber layer (RNFL) evaluation as an easy-to-use, reproducible, proxy-measure of brain structural abnormalities. Here, we evaluated RNFL thickness in a group of subjects with high functioning autism (HFA) or with Asperger Syndrome (AS) to its potential as a tool to study autism pathophysiology. All subjects underwent high-resolution spectral domain optical coherence tomography to evaluate RNFL thickness. HFA subjects presented with reduced global RNFL thickness compared both to AS subjects and controls. AS subjects showed a reduced nasal quadrant RNFL thickness compared to controls. Verbal-IQ/performance-IQ discrepancy correlated with RNFL thickness. Our data suggest that RNFL evaluation could help in the development of biological markers of autism pathophysiology. PMID:24014196

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

2014-04-01

27

Dispersion and energy parameters of the HE{sub 1m} modes of two-layer optical fibres  

SciTech Connect

Dispersion and energy parameters of the HE{sub 1m} modes of multimode two-layer step-index optical fibres are studied. The results of studies on chromatic dispersion for wavelengths {lambda} < 1.3 {mu}m and {lambda} > 1.3 {mu}m, phase and group delays, waveguide and material dispersions of the modes, as well as results of calculations of fibre core diameters, normalised powers and corresponding effective areas of HE{sub 1m} modes are presented under conditions of the zero chromatic dispersion at {lambda}{sub 0} = 1.55 and 1.06 {mu}m. (optical waveguides)

Belanov, A S; Kharitonova, K Yu; Tsvetkov, S V [Moscow State University of Instrument Making and Computer Science (Russian Federation); Dianov, Evgenii M; Sysolyatin, A A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2009-02-28

28

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

29

Direct Lattice Resolution of Layer Planes in Polyacrylonitrile Based Carbon Fibres  

Microsoft Academic Search

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

D. J. Johnson

1970-01-01

30

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

ERIC Educational Resources Information Center

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

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

2014-01-01

31

Caffeic acid and glycerol are constituents of the suberin layers in green cotton fibres  

Microsoft Academic Search

The fibres of the green-lint mutant (Lg) of cotton (Gossypium hirsutum L.) are suberized and contain a large proportion of wax. The unidentified components of the wax were separated into a colourless\\u000a fluorescent fraction and a yellow pigmented fraction. Using ultraviolet spectroscopy and nuclear-magneticresonance (1H-NMR) spectroscopy, esterified trans-caffeic acid was identified as the only phenolic component in the colourless fraction.

Alain Schmutz; Titus Jenny; Nikolaus Amrhein; Ulrich Ryser

1993-01-01

32

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

33

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

PubMed

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

Skacel, Pavel; Bursa, Jiri

2015-01-01

34

Energy transfer in optical fibres  

SciTech Connect

The possibility of energy transfer over long distances in the form of laser radiation propagating in dielectric optical fibres is discussed. Because nonlinear-optical phenomena in glasses prevent the transfer of high radiation powers in standard two-layer fibres, the outlook for this transfer is associated with the development of the technology of microstructure fibres with a hollow core and with further progress in the development of high-power fibre lasers. (optical fibres)

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

2007-04-30

35

Interocular Retinal Nerve Fiber Layer Thickness Difference in Normal Adults  

PubMed Central

Purpose To determine the interocular retinal nerve fiber layer (RNFL) thickness difference of normal subjects. Methods Both eyes of 230 normal adults received peripapillary RNFL thickness measurements using OCT. The effect of ocular cyclotorsion on the RNFL thickness profile was mathematically corrected. The fractional and absolute interocular RNFL thickness differences at 256 points of peripapillary area were calculated. We divided the subjects into 3 groups according to the locations of superior and inferior peak thickness, respectively, and compared the interocular RNFL thickness differences between the subgroups. Results The fractional interocular RNFL thickness difference exhibited smaller regional variations than the absolute interocular difference. The means of fractional interocular differences were 0.100 ± 0.077 in the temporal half area and 0.146 ± 0.105 in the nasal half area, and the tolerance limits for the 95th and 99th distributions were about 0.246 and 0.344 in the temporal half area and 0.293 and 0.408 in the nasal half area, respectively. The fractional interocular differences of subgroups classified by the locations of superior and inferior peak RNFL thickness showed difference at smaller areas than the absolute interocular differences (19 and 8 points versus 49 and 23 points, respectively). Conclusion Glaucoma can be strongly suspected, if interocular fractional RNFL thickness difference is over 25% at 5 consecutive points or over 35% at 3 consecutive points in the temporal half area. The fractional interocular comparison is a better diagnostic approach because the fractional interocular RNFL thickness difference is less influenced by the locations of peak RNFL thickness. PMID:25679786

Hong, Seung Woo; Lee, Seung Bum; Jee, Dong-hyun; Ahn, Myung Douk

2015-01-01

36

Multimaterial piezoelectric fibres.  

PubMed

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 mum 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. PMID:20622864

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

37

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

38

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

39

On the possibility of compensating material dispersion in three-layer optical fibres in the wavelength range below 1.3 {mu}m  

SciTech Connect

Idealised three-layer model optical fibres consisting of an optically dense core with the refractive index n{sub 1} surrounded by a 'holey' intermediate cladding having a much lower optical density and the refractive index n{sub 2} and by a rather thick outer cladding with the refractive index n{sub 3} are investigated. The idealised model assumes that the intermediate cladding is homogeneous. It is also assumed that n{sub 1} > n{sub 3} > n{sub 2}. It is shown that in such fibres with large differences n{sub 1} - n{sub 2} and n{sub 3} - n{sub 2}, a single-mode regime can be realised in fact, when the nearest higher modes H{sub 01}, E{sub 01}, HE{sub 21} have additional radiative losses of several hundred dB km{sup -1}, whereas the main operating mode HE{sub 11} has no such losses in the single-mode regime. It is important that the zero dispersion can be obtained in these fibres in the spectral region below 1.3 {mu}m. (optical fibres and fibre lasers)

Belanov, A S; Krivenkov, V I; Kharitonova, K Yu [Moscow State Academy of Instrument Engineering and Informatics, Moscow (Russian Federation); Belov, A V; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Raevskii, A S [Nizhnii Novgorod State Technical University, Nizhnii Novgorod (Russian Federation)

2002-05-31

40

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

41

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

42

Utility of Heidelberg retinal tomography as a screening tool for analyzing retinal nerve fiber layer defects  

PubMed Central

Context Although Heidelberg retinal tomography (HRT)-generated topographic images have been studied extensively for the detection of retinal nerve fiber layer (RNFL) defects, little is known about the role of HRT-generated surface reflectivity images in the detection of RNFL defects in either patients with glaucoma or glaucoma suspects. Aims To evaluate the effectiveness of HRT version II (HRT II) optic nerve reflectivity images in uncovering RNFL defects in an outpatient population evaluated for glaucoma. Study design/materials and methods In 102 consecutive eyes from 60 patients evaluated for glaucoma in an academic-based practice, HRT II optic nerve images were prospectively imaged and compared with clinical optic nerve exam techniques to see if HRT II was able to detect RNFL defects overlooked in clinical practice. Results Nine eyes (8.8%) were found to have RNFL defects recognized by screening with HRT II. Of these nine eyes, eight (88.9%) were recognized to demonstrate RNFL defects by conventional examination techniques. One additional eye had an RNFL defect seen on physical exam that was not detected by HRT. Conclusion In academic practice, HRT II may be helpful in complementing conventional exam techniques in the recognition and documentation of acquired RNFL loss. PMID:25506202

Belyea, David A; Alhabshan, Rashed N; Mahesh, Sankaranarayana P; Gertner, Gregory S; Ibisevic, Mirsad M; Habib, Abdullah S; Dan, Jacob A

2014-01-01

43

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

PubMed

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

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

2014-09-01

44

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

PubMed Central

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

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

2014-01-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

46

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

NASA Astrophysics Data System (ADS)

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

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

2006-05-01

47

Investigation of the deposition of porous layers by the MCVD method for the preparation of rare-earth doped cores of optical fibres  

NASA Astrophysics Data System (ADS)

Investigation was carried out on core layer deposition by modified chemical vapour deposition (MCVD) process to fabricate rare earth (RE) doped preforms and fibres. The solution doping technique was adopted for incorporation of the RE and codopant such as Al 2O 3 into the core. The deposited cores composed of GeO 2/P 2O 5/SiO 2 glasses with GeO 2 level in the range of 3-15 mol% and P 2O 5 up to 5 mol%. The soot layer was deposited inside the substrate tube both by forward and backward deposition methods. This basic difference in the process between the two modes of deposition produced significant variation in the RE incorporation, numerical aperture as well as core-clad dimensions, all of which contribute to the end fibre performance. The backward deposition method provided greater flexibility and control over the RE incorporation.

Pal, M.; Sen, R.; Paul, M. C.; Bhadra, S. K.; Chatterjee, S.; Ghosal, D.; Dasgupta, K.

2005-10-01

48

Retinal Nerve Fiber Layer Assessment: Area versus Thickness Measurements from Elliptical Scans Centered on the Optic Nerve  

PubMed Central

Purpose. An evaluation of the retinal nerve fiber layer (RNFL) provides important information on the health of the optic nerve. Standard measurements of the RNFL consider only thickness, but an accurate assessment should also consider axial length, size of the optic nerve head (ONH), blood vessel contribution, and distance of the scan from the ONH margin. In addition, although most primate ONHs are elliptical, the circular scan centered on the ONH is the mainstay in both clinical and research analyses. The purpose of this study was to evaluate thickness and area measures of RNFL cross sections when axial length and ONH shape are included. Methods. Circular, raster, and radial scans of left eye optic nerves were acquired from 40 normal rhesus monkeys (Macaca mulatta) using spectral domain optical coherence tomography. The disc margin was identified by manually selecting the RPE/Bruch's membrane opening and ONH border tissue. With a pixel-to-micrometer conversion computed from a three-surface schematic eye, RNFL scans were interpolated at 300 to 600 ?m (50-?m increments) from the edge of the ONH. The thickness and area of the RNFL at each distance were obtained by custom programs. Blood vessels in the RNFL were selected and removed from the overall RNFL measures. Results. The average RNFL thickness decreased systematically from 149 ± 12.0 ?m for scans 300 ?m from the disc margin to 113 ± 7.2 ?m at an eccentricity of 600 ?m (P < 0.05). In contrast, the cross-sectional areas of the RNFL did not vary with scan location from the disc margin (0.85 ± 0.07 mm2 at 300 ?m compared with 0.86 ± 0.06 mm2 at 600 ?m). Blood vessels accounted for 9.3% of total RNFL thickness or area, but varied with retinal location. On average, 17.6% of the superior and 14.2% of the inferior RNFL was vascular, whereas blood vessels accounted for only 2.3% of areas of the temporal and nasal RNFL regions. Conclusions. In nonhuman primates, with appropriate transverse scaling and ONH shape analysis, the cross-sectional area of the RNFL is independent of scan distance, up to 600 ?m from the rim margin, indicating that the axonal composition changes little over this range. The results suggest that, with incorporation of transverse scaling, the RNFL cross-sectional area, rather than RNFL thickness, provides an accurate assessment of the retinal ganglion cell axonal content within the eye. PMID:21220552

Luo, Xunda; Wheat, Joe L.; Harwerth, Ronald S.

2011-01-01

49

Effects of a high oil and fibre diet and supplementary roughage on performance, injurious pecking and foraging activities in two layer hybrids  

Microsoft Academic Search

1. The study investigated the feeding of a high oil and fibre diet containing 260?g\\/kg organically produced cold pressed sunflower cake or supplemental roughage to aviary-housed Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) layers between 20 and 74 weeks of age with outdoor access during summer.2. Feeding roughage was associated with reduced vent injuries, a tendency to improve plumage

R. Kalmendal; H. Wall

2012-01-01

50

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

51

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

PubMed Central

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

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

2010-01-01

52

Bismuth-ring-doped fibres  

SciTech Connect

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

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

2009-11-30

53

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

54

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

PubMed

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

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

2015-04-01

55

The fibre fuse effect in microstructured fibres  

SciTech Connect

The fibre fuse effect was observed for the first time in microstructured fibres exposed to laser radiation. The threshold power for this effect in such fibres is an order of magnitude higher than that for conventional silica fibres. (optical fibres)

Dianov, Evgenii M; Frolov, A A; Bufetov, Igor' A; Semenov, S L [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Chamorovsky, Yury K; Ivanov, G A; Vorob'ev, Igor' L [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow (Russian Federation)

2004-01-31

56

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

57

Fibre Channel over Ethernet: A beginners perspective  

Microsoft Academic Search

Fibre Channel over Ethernet is proposed mapping of Fibre Channel frames in existing Ethernet, a successful convergence of LAN and SAN. FCoE is not a replacement for conventional Fibre Channel but is an extension of Fibre Channel over a different link layer transport. The basic terminologies for FCoE are FCoE software Initiator and Target. Initiator of FCoE is the client

Pranoti Kale; Ashwin Tumma; Harshada Kshirsagar; Pooja Ramrakhyani; Tejashri Vinode

2011-01-01

58

Evaluation of changes in retinal nerve fiber layer thickness and visual functions in cases of optic neuritis and multiple sclerosis  

PubMed Central

Context: Retinal nerve fiber layer (RNFL) thinning has been demonstrated in cases of optic neuritis (ON) and multiple sclerosis (MS) in Caucasian eyes, but no definite RNFL loss pattern or association with visual functions is known in Indian eyes. Aim: To evaluate RNFL thickness in cases of ON and MS, and to correlate it with visual function changes in Indian patients. Settings and Design: Cross-sectional case-control study at a tertiary level institution. Materials and Methods: Cases consisted of patients of (i) typical ON without a recent episode (n = 30:39 ON eyes and 21 fellow eyes), (ii) MS without ON (n = 15;30 eyes) while the controls were age-matched (n = 15; 30 eyes). RNFL thickness was measured using the Stratus 3°CT. The visual functions tested included the best-corrected visual acuity (BCVA), contrast sensitivity, stereopsis, visual evoked responses, and visual fields. Statistical analysis used: Intergroup analysis was done using ANOVA and Pearson's correlation coefficient used for associations. Results: RNFL thickness was reduced significantly in the ON and MS patients compared to the controls (P-0.001). Maximum loss is in the temporal quadrant. Lower visual function scores are associated with reduced average overall RNFL thickness. In ON group, RNFL thinning is associated with severe visual field defects while contrast sensitivity has strongest correlation with RNFL in the MS group. Conclusions: RNFL thickness is reduced in ON and MS cases in a pattern similar to Caucasians and is associated with the magnitude of impairment of other visual parameters. Contrast sensitivity and stereoacuity are useful tests to identify subclinical optic nerve involvement in multiple sclerosis. PMID:24212307

Saxena, Rohit; Bandyopadhyay, Gopal; Singh, Digvijay; Singh, Sumit; Sharma, Pradeep; Menon, Vimla

2013-01-01

59

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

60

Fibre Models  

NASA Astrophysics Data System (ADS)

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

Herrmann, H. J.; Kun, F.

2007-12-01

61

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

62

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

E-print Network

SFT 1SFT 1 SFT 2SFT 2 Weilin Yu, DPG Frühjahrstagung,Gießen #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

63

Optical fibre Optical fibre OPTICAL FIBRE NANOWIRE SENSORS AND APPLICATIONS  

E-print Network

OFN Optical fibre Optical fibre Transition regions Core OPTICAL FIBRE NANOWIRE SENSORS SO17 1BJ, U.K. e-mail : gb2@orc.soton.ac.uk Optical fibre nanowires (OFN) have recently attracted/flexibility: OFN are manufactured stretching optical fibres, thus they mantain their original size

Quartly, Graham

64

The attenuation of retinal nerve fiber layer thickness and cognitive deterioration  

PubMed Central

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

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

2013-01-01

65

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

66

Comparison of retinal nerve fiber layer and macular thickness measurements with Stratus OCT and OPKO/OTI OCT devices in healthy subjects  

PubMed Central

AIM To compare retinal nerve fiber layer (RNFL) and macular thickness measurements obtained with the Stratus optical coherence tomography (OCT) and OPKO/OTI OCT devices. METHODS Included in the study were 59 eyes of 30 participants. All measurements for each eye were done on the same day with both devices. Student's paired t-tests were used to compare the central macular thickness and RNFL measurements of the Stratus OCT and OPKO/OTI OCT. Pearson correlation was used to assess the relationship between the devices. Coefficient of variation (COV) was calculated to assess intersession repeatability. RESULTS Using both the Stratus OCT and OPKO/OTI OCT, respectively, the measured mean average RNFL thicknesses were 98.9±11.1 µm and 115.1±9.6 µm (P=0.001), and the measured mean central retinal thicknesses (CRT) were 196.2±18.8 µm and 204.5±21.1 µm (P<0.001). Measured by the two devices, the RNFL thickness values were correlated in all quadrants, as were the retinal thickness values except the inferior outer sector. COV for average RNFL and CRT thickness were 2.9% and 4.6% for Stratus OCT, and 2.1% and 4.2% for OPKO/OTI OCT, respectively. CONCLUSION We found good reproducibility of RNFL and retina thickness measurements for both Stratus OCT and OPKO/OTI OCT devices. However, even though the two OCT systems provided statistically correlated results, the values for both RNFL and macular thickness were statistically different. RNFL and macular thickness measurements with the OPKO/OTI OCT were higher than that of the Stratus OCT; therefore, the two OCT systems cannot be used interchangeably for the measurements of RNFL and macular thickness. PMID:25709916

Ozkok, Ahmet; Akkan, Julide Canan Umurhan; Tamcelik, Nevbahar; Erdogan, Mehmet; Comlekoglu, Didar Ucar; Yildirim, Rengin

2015-01-01

67

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

PubMed

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

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

2014-09-01

68

Peripapillary Retinal Nerve Fiber Layer Assessment of Spectral Domain Optical Coherence Tomography and Scanning Laser Polarimetry to Diagnose Preperimetric Glaucoma  

PubMed Central

Purpose To compare the abilities of peripapillary retinal nerve fiber layer (RNFL) parameters of spectral domain optical coherence tomograph (SDOCT) and scanning laser polarimeter (GDx enhanced corneal compensation; ECC) in detecting preperimetric glaucoma. Methods In a cross-sectional study, 35 preperimetric glaucoma eyes (32 subjects) and 94 control eyes (74 subjects) underwent digital optic disc photography and RNFL imaging with SDOCT and GDx ECC. Ability of RNFL parameters of SDOCT and GDx ECC to discriminate preperimetric glaucoma eyes from control eyes was compared using area under receiver operating characteristic curves (AUC), sensitivities at fixed specificities and likelihood ratios (LR). Results AUC of the global average RNFL thickness of SDOCT (0.786) was significantly greater (p<0.001) than that of GDx ECC (0.627). Sensitivities at 95% specificity of the corresponding parameters were 20% and 8.6% respectively. AUCs of the inferior, superior and temporal quadrant RNFL thickness parameters of SDOCT were also significantly (p<0.05) greater than the respective RNFL parameters of GDx ECC. LRs of outside normal limits category of SDOCT parameters ranged between 3.3 and 4.0 while the same of GDx ECC parameters ranged between 1.2 and 2.1. LRs of within normal limits category of SDOCT parameters ranged between 0.4 and 0.7 while the same of GDx ECC parameters ranged between 0.7 and 1.0. Conclusions Abilities of the RNFL parameters of SDOCT and GDx ECC to diagnose preperimetric glaucoma were only moderate. Diagnostic abilities of the RNFL parameters of SDOCT were significantly better than that of GDx ECC in preperimetric glaucoma. PMID:25279801

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

2014-01-01

69

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

70

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

71

Single-mode optical fibre surface plasma wave chemical sensor  

Microsoft Academic Search

We describe a new design of optical fibre surface plasma wave chemical sensor. The basic sensor consists of a tapered single-mode optical fibre with a thin layer of silver evaporated onto the tapered section. The gradually changing diameter of the fibre along the taper and the variation in silver depth around the taper result in a distributed coupling between the

A. J. C. Tubb; F. P. Payne; R. B. Millington; C. R. Lowe

1997-01-01

72

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

PubMed Central

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

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

2015-01-01

73

Microstructured polymer optical fibre  

Microsoft Academic Search

The first microstructured polymer optical fibre is described. Both experimental and theoretical evidence is presented to establish that the fibre is effectively single moded at optical wavelengths. Polymer-based microstructured optical fibres offer key advantages over both conventional polymer optical fibres and glass microstructured fibres. The low-cost manufacturability and the chemical flexibility of the polymers provide great potential for applications in

Martijn van Eijkelenborg; Maryanne Large; Alexander Argyros; Joseph Zagari; Steven Manos; Nader A. Issa; Ian M. Bassett; Simon C. Fleming; Ross C. McPhedran; C. Martijn de Sterke; Nicolae A. P. Nicorovici

2001-01-01

74

Relationship among Photopic Negative Response, Retinal Nerve Fiber Layer Thickness, and Visual Field between Normal and POAG Eyes  

PubMed Central

Purpose. To determine the relationship among photopic negative response (PhNR) of the electroretinogram (ERG), retinal nerve fiber layer (RNFL) thickness, and the visual field in normal and glaucomatous patients. Methods. Thirty-eight normal volunteers and one hundred twenty-four patients with Primary open-angle glaucoma (POAG) were enrolled in the study. The PhNRs were elicited by white stimuli on a white background and red stimuli on a blue background. The visual field parameters were measured using the standard automated perimetry (SAP). The spectral domain optical coherence tomography (SD-OCT) was used to measure the retinal nerve fiber layer (RNFL) thickness around the optic disc. Results. The PhNR amplitude (W/W, B/R), MD, and mean RNFL thickness in POAG eyes were significantly lower than normal eyes (P = 0.001). The R value in Normal + Glaucomatous group was higher than that of the only glaucomatous group. The R values of PhNR amplitude (B/R) with MD and RNFL were higher than those of PhNR amplitude (W/W). Significant linear association was found in the relationship between RNFL thickness and PhNR amplitude (B/R) (R2 = 0.5, P = 0.001). However, significant curve associations were found in the relationship between MD and PhNR amplitude (B/R) and RNFL thickness (R2 = 0.525, 0.442, P = 0.001). Conclusions. The ganglion cell activity can be more efficiently evaluated with the PhNR elicited with a red than with a broadband stimulus. The linear relationship between the PhNR amplitude and RNFL thickness indicates that inner retinal function declines proportionately with neural loss in glaucomatous eyes. The PhNR and RNFLT are more objective tools to detect glaucomatous damage than visual field. PMID:24558598

Shen, Xiaoli; Huang, Lina; Fan, Ning; He, Jing

2013-01-01

75

Relationship among Photopic Negative Response, Retinal Nerve Fiber Layer Thickness, and Visual Field between Normal and POAG Eyes.  

PubMed

Purpose. To determine the relationship among photopic negative response (PhNR) of the electroretinogram (ERG), retinal nerve fiber layer (RNFL) thickness, and the visual field in normal and glaucomatous patients. Methods. Thirty-eight normal volunteers and one hundred twenty-four patients with Primary open-angle glaucoma (POAG) were enrolled in the study. The PhNRs were elicited by white stimuli on a white background and red stimuli on a blue background. The visual field parameters were measured using the standard automated perimetry (SAP). The spectral domain optical coherence tomography (SD-OCT) was used to measure the retinal nerve fiber layer (RNFL) thickness around the optic disc. Results. The PhNR amplitude (W/W, B/R), MD, and mean RNFL thickness in POAG eyes were significantly lower than normal eyes (P = 0.001). The R value in Normal + Glaucomatous group was higher than that of the only glaucomatous group. The R values of PhNR amplitude (B/R) with MD and RNFL were higher than those of PhNR amplitude (W/W). Significant linear association was found in the relationship between RNFL thickness and PhNR amplitude (B/R) (R (2) = 0.5, P = 0.001). However, significant curve associations were found in the relationship between MD and PhNR amplitude (B/R) and RNFL thickness (R (2) = 0.525, 0.442, P = 0.001). Conclusions. The ganglion cell activity can be more efficiently evaluated with the PhNR elicited with a red than with a broadband stimulus. The linear relationship between the PhNR amplitude and RNFL thickness indicates that inner retinal function declines proportionately with neural loss in glaucomatous eyes. The PhNR and RNFLT are more objective tools to detect glaucomatous damage than visual field. PMID:24558598

Shen, Xiaoli; Huang, Lina; Fan, Ning; He, Jing

2013-01-01

76

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.

77

Assessing the Relationship between Central Corneal Thickness and Retinal Nerve Fiber Layer Thickness in Healthy Subjects  

PubMed Central

Purpose To determine the relationship between central corneal thickness (CCT) and retinal nerve fiber layer (RNFL) thickness obtained by scanning laser polarimetry (GDx-VCC; Carl Zeiss Meditec, Dublin, CA) confocal scanning laser ophthalmoscopy (HRT II; Heidelberg Engineering, Heidelberg, Germany) and optical coherence tomography (Stratus OCT; Carl Zeiss Meditec, Dublin, CA). Design Multi-center clinical trial, retrospective cross-sectional study. Methods One hundred and nine healthy subjects from the Advanced Imaging in Glaucoma Study were enrolled in this study. All subjects had a standard clinical examination, including visual field and good quality scans from all three imaging devices. Central corneal thickness was measured using an ultrasonic pachymeter. A linear mixed effects model was used to assess the relationship between RNFL thickness and CCT, accounting for clustering of eyes within subjects, testing site, ethnicity, family history of glaucoma, axial length intraocular pressure and visual field global indices. Results For OCT and GDx, there was a slight non-statistically significant positive relationship between CCT and RNFL thickness. For HRT, there was a slight non-statistically significant negative relationship between CCT and RNFL thickness. Relationships for each device were found to differ between sites. Conclusions CCT was not statistically significantly related to RNFL thickness in healthy eyes. PMID:18657796

Mumcuoglu, Tarkan; Townsend, Kelly A; Wollstein, Gadi; Ishikawa, Hiroshi; Bilonick, Richard A; Sung, Kyung Rim; Kagemann, Larry; Schuman, Joel S

2008-01-01

78

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

79

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

PubMed Central

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

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

2014-01-01

80

Fibre-reinforced materials.  

PubMed

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

Brown, D

2000-11-01

81

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

Microsoft Academic Search

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

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

2011-01-01

82

Constitutive modelling of arteries considering fibre recruitment and three-dimensional fibre distribution.  

PubMed

Structurally motivated material models may provide increased insights into the underlying mechanics and physics of arteries under physiological loading conditions. We propose a multiscale model for arterial tissue capturing three different scales (i) a single collagen fibre; (ii) bundle of collagen fibres; and (iii) collagen network within the tissue. The waviness of collagen fibres is introduced by a probability density function for the recruitment stretch at which the fibre starts to bear load. The three-dimensional distribution of the collagen fibres is described by an orientation distribution function using the bivariate von Mises distribution, and fitted to experimental data. The strain energy for the tissue is decomposed additively into a part related to the matrix material and a part for the collagen fibres. Volume fractions account for the matrix/fibre constituents. The proposed model only uses two parameters namely a shear modulus of the matrix material and a (stiffness) parameter related to a single collagen fibre. A fit of the multiscale model to representative experimental data obtained from the individual layers of a human thoracic aorta shows that the proposed model is able to adequately capture the nonlinear and anisotropic behaviour of the aortic layers. PMID:25788541

Weisbecker, Hannah; Unterberger, Michael J; Holzapfel, Gerhard A

2015-04-01

83

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

PubMed Central

Purpose To understand better the influence of retinal blood vessels (BVs) on the interindividual variation in the retinal nerve fiber layer (RNFL) thickness measured with optical coherence tomography (OCT). Subjects and Methods RNFL thickness profiles were measured by OCT in 16 control individuals and 16 patients. The patients had advanced glaucoma defined by abnormal disc appearance, abnormal visual fields, and a mean visual field deviation worse than ? 10 dB. Results In general, the OCT RNFL thickness profiles showed 4 local maxima, with the peak amplitudes in the superior and inferior regions occurring in the temporal (peripapillary) disc region. There was considerable variability among individuals in the location of these maxima. However, the 4 maxima typically fell on, or near, a major BV with the temporal and inferior peaks nearly always associated with the main temporal branches of the superior and inferior veins and arteries. In the patients’ hemifields with severe loss (mean visual field deviation worse than ? 20 dB), the signals associated with the major BVs were in the order of 100 to 150 µm. Conclusions The variation in the local peaks of the RNFL profiles of controls correlates well with the location of the main temporal branches of the superior and inferior veins and arteries. This correspondence is, in part, due to a direct BV contribution to the shape of the OCT RNFL and, in part, due to the fact that BVs develop along the densest regions of axons. Although the overall BV contribution was estimated to be relatively modest, roughly 13% of the total peripapillary RNFL thickness in controls, their contribution represents a substantial portion locally and increases in importance with disease progression. PMID:18854727

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

2010-01-01

84

FIBRE OPTICS: Sulphur-doped silica fibres  

Microsoft Academic Search

An optical fibre with low optical losses is manufactured from a sulphur-doped quartz glass. Optical absorption spectra are measured for various parts of the fibre core. Most of the bands of these spectra are assigned to oxygen-deficient centres and colour centres containing sulphur atoms. The photosensitivity of glasses exposed to laser radiation at wavelengths of 193 and 244 nm is

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

2003-01-01

85

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

86

Photonic crystal fibres  

Microsoft Academic Search

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

Jonathan C. Knight

2003-01-01

87

High-Resolution Imaging of the Retinal Nerve Fiber Layer in Normal Eyes Using Adaptive Optics Scanning Laser Ophthalmoscopy  

PubMed Central

Purpose To conduct high-resolution imaging of the retinal nerve fiber layer (RNFL) in normal eyes using adaptive optics scanning laser ophthalmoscopy (AO-SLO). Methods AO-SLO images were obtained in 20 normal eyes at multiple locations in the posterior polar area and a circular path with a 3–4-mm diameter around the optic disc. For each eye, images focused on the RNFL were recorded and a montage of AO-SLO images was created. Results AO-SLO images for all eyes showed many hyperreflective bundles in the RNFL. Hyperreflective bundles above or below the fovea were seen in an arch from the temporal periphery on either side of a horizontal dividing line to the optic disc. The dark lines among the hyperreflective bundles were narrower around the optic disc compared with those in the temporal raphe. The hyperreflective bundles corresponded with the direction of the striations on SLO red-free images. The resolution and contrast of the bundles were much higher in AO-SLO images than in red-free fundus photography or SLO red-free images. The mean hyperreflective bundle width around the optic disc had a double-humped shape; the bundles at the temporal and nasal sides of the optic disc were narrower than those above and below the optic disc (P<0.001). RNFL thickness obtained by optical coherence tomography correlated with the hyperreflective bundle widths on AO-SLO (P<0.001) Conclusions AO-SLO revealed hyperreflective bundles and dark lines in the RNFL, believed to be retinal nerve fiber bundles and Müller cell septa. The widths of the nerve fiber bundles appear to be proportional to the RNFL thickness at equivalent distances from the optic disc. PMID:22427978

Takayama, Kohei; Ooto, Sotaro; Hangai, Masanori; Arakawa, Naoko; Oshima, Susumu; Shibata, Naohisa; Hanebuchi, Masaaki; Inoue, Takashi; Yoshimura, Nagahisa

2012-01-01

88

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

89

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

90

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

91

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

PubMed Central

Purpose To determine the agreement between Spectralis and Cirrus spectral domain optical coherence tomography (SD-OCT) measurements of peripapillary retinal nerve fiber layer (RNFL) thickness. Methods Suspected or confirmed cases of glaucoma who met the inclusion criteria underwent peripapillary RNFL thickness measurement using both the Spectralis and Cirrus on the same day within a few minutes. Results Measurements were performed on 103 eyes of 103 patients with mean age of 50.4±17.7 years. Mean RNFL thickness was 89.22±15.87 versus 84.54±13.68 µm using Spectralis and Cirrus, respectively. The difference between measurements and the average of paired measurements with the two devices showed a significant linear relationship. Bland-Altman plots demonstrated that Spectralis thickness values were systematically larger than that of Cirrus. Conclusion Spectralis OCT generates higher peripapillary RNFL thickness readings as compared to Cirrus OCT; this should be kept in mind when values obtained with different instruments are compared during follow-up. PMID:24982729

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

2014-01-01

92

Adjusted color probability codes for peripapillary retinal nerve fiber layer thickness in healthy Koreans  

PubMed Central

Background Though a newly developed spectral domain optical coherence tomography (OCT) is at the center of interests for many ophthalmologic researchers and clinicians, its own characteristics are not fully evaluated yet. The main purpose of this study was to establish the adjusted color probability codes for peripapillary retinal nerve fiber layer (RNFL) thickness in healthy Koreans and to compare them with original color codes provided by spectral domain OCT. Methods Two hundred ninety-five healthy Korean eyes were enrolled and their peripapillary RNFL thickness was measured by Cirrus OCT. For each decade of age, the normal thickness reference was determined on the basis of z-scores and the adjusted color probability codes were established. Then the agreements between adjusted and original color codes were calculated using weighted Kappa (Kw) coefficient. Results On the basis of Kw coefficient, the overall agreement between the adjusted and original probability color codes was not excellent (Kw range of 0.500 to 0.806). If the adjusted probability codes were assumed as a standard of comparison, the original color codes showed the false-negative in 11% of eyes and the false-positive in 0.3% of eyes for average RNFL thickness. Conclusions Adjusted color probability codes judged by the Korean normative data showed a discrepancy with original codes. It implies that normal reference and adjusted probability codes for each ethnicity might be needed to determine whether a certain RNFL thickness is within normal range or not. PMID:24678925

2014-01-01

93

A chirped photonic-crystal fibre  

NASA Astrophysics Data System (ADS)

Photonic crystals have widely increased the facility to guide and confine light at wavelengths close to the optical wavelength. Because they can include extremely sharp bends, photonic-crystal waveguides are a key element in future integrated optical devices. Moreover, they enable the manipulation of the spontaneous emission properties of luminescent devices, the localization of light in microcavities, and they may serve to generate negative refraction. A special class of these devices are the hollow-core photonic-crystal fibres, which confine the light by means of a periodic cladding, consisting of several layers of identical cells. This design resonantly decreases the transmission losses of such fibres to values of a few dB km-1 in a narrow wavelength range. However, the rather narrowband transmission bands and the detrimental third-order dispersion characteristics of this single-cell design generally render application of such hollow-core fibres difficult in the femtosecond range. Therefore, no fibre-based concept can currently provide guiding of sub-100 fs pulses over extended distances. By introducing a radial chirp into the photonic crystal, we here demonstrate a novel concept for photonic-crystal fibres that breaks with the paradigm of lattice homogeneity and enables a new degree of freedom in photonic-crystal-fibre design, eliminating much of the pulse duration restriction of earlier approaches.

Skibina, Julia S.; Iliew, Rumen; Bethge, Jens; Bock, Martin; Fischer, Dorit; Beloglasov, Valentin I.; Wedell, Reiner; Steinmeyer, Günter

2008-11-01

94

HIPPI and Fibre Channel  

SciTech Connect

The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background.

Tolmie, D.E.

1992-01-01

95

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

PubMed Central

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

Budenz, Donald L.

2008-01-01

96

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

97

Cross-sectional study of the retinal nerve fiber layer thickness at 7 years after an acute episode of unilateral primary acute angle closure.  

PubMed

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

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

2015-01-01

98

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

99

Reproducibility of peripapillary retinal nerve fiber layer thickness measurements with cirrus HD-OCT in glaucomatous eyes  

PubMed Central

AIM To assess the reproducibility of Cirrus high-definition optical coherence tomography (HD-OCT; Carl Zeiss Meditec, Dublin, CA, USA) for analysis of peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes METHODS Forty-five eyes (one eye from each glaucomatous patient) were imaged with Cirrus HD-OCT. Each eye was imaged three times by two separate operators. Intraclass correlation coefficient (ICC), coefficient of variation (CV), and test-retest variability were evaluated for both intraobserver and interobsever measurements RESULTS In intraobserver measurements, the average RNFL thickness ICC was 0.983. CV and test-retest variability were 2.3% and 4.4 µm respectively. In quadrants ICC ranged from 0.886 to 0.956, the lowest associated with nasal quadrant and CV ranged from 3.6% to 7.7%. In interobsever measurements, the average RNFL thickness ICC was 0.979. CV and test-retest variability were 2.4% and 4.5 µm respectively. In quadrants ICC ranged from 0.886 to 0.957, the lowest associated with nasal quadrant and CV ranged from 3.8% to 8.6%. CONCLUSION The reproducibility of Cirrus OCT for RNFL thickness is sufficiently good to be useful clinically as a measure of glaucoma progression. PMID:25709919

Soltani-Moghadam, Reza; Alizadeh, Yousef; Kazemnezhad Leili, Ehsan; Absari Haghighi, Mohamadreza

2015-01-01

100

Strength distribution of elementary flax fibres  

Microsoft Academic Search

Flax fibres, along with a number of other natural fibres, are being considered as an environmentally friendly alternative of synthetic fibres in fibre-reinforced polymer composites. A common feature of natural fibres is a much higher variability of mechanical properties. This necessitates study of the flax fibre strength distribution and efficient experimental methods for its determination. Elementary flax fibres of different

J. Andersons; E. Sp?rni?š; R. Joffe; L. Wallström

2005-01-01

101

Flax fibre–polyester composites  

Microsoft Academic Search

Composites of an aliphatic polyester (Bionolle) with natural flax fibres are prepared by batch mixing. The effect of processing conditions on fibre length distribution and the dependence of the composite mechanical properties on fibre content are investigated. The tensile modulus changes with fibre content according to the modified rule-of-mixture equation, with a fibre orientation efficiency factor ?0=0.194. The strength of

Massimo Baiardo; Elisa Zini; Mariastella Scandola

2004-01-01

102

Thermal stabilization of polyacrylonitrile fibres  

Microsoft Academic Search

A polyacrylonitrile (PAN) fibre, Dralon T (DT), and a copolymer manufactured as a carbon fibre precursor, Special Acrylic Fibre (SAF), were studied as received and after heat-treatment in air at various temperatures up to 300°C. Wide angle X-ray scattering (WAXS) was undertaken on single fibres, fibre bundles and films, utilizing both conventional and synchrotron sources. With a conventional source, the

Stephen Dalton; Frank Heatley; Peter M. Budd

1999-01-01

103

Birefringence Phenomena in Kidney-shaped Multilayer Fibres  

Microsoft Academic Search

A theoretical treatment of the shape of Fizeau fringes crossing a multilayer fibre of kidney-shaped cross-section is presented. A mathematical expression is derived and used to estimate the refractive indices and the birefringence of Dralon-K polyacrylonitrile fibre. Variation of refractive index with temperature is reported. The resulting data were utilized to calculate the polarizability per unit volume for each layer.Applications

I. M. Fouda; M. M. El Niklawy; K. A. El Farhaty; T. El Dessouki

1987-01-01

104

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

PubMed Central

Purpose To study the influence of the transient elevation of intraocular pressure during suction in laser-assisted in situ keratomileusis (LASIK) on the retinal nerve fiber layer (RNFL) thickness both in microkeratome assisted and femotsecond (FS) LASIK. Patients and methods An interventional case series that included 40 eyes suffering from myopia who were candidates for LASIK. All underwent Wave Front Guided LASIK by the same surgeon using the VisX CustomVue platform. A corneal flap was created in 20 eyes using a mechanical microkeratome Moria M2 (MMK), while the IFS IntraLase™ was used in the remaining 20 eyes. Mean suction time was recorded from “Suction ON” to “Suction OFF” time. Optic cube and RNFL thickness analysis using Spectral Domain Optical Coherence Tomography (SD-OCT) Cirrus-HD was completed before, and 1 month after LASIK. Results The study included 40 eyes of 20 patients. All were females with mean age 33.5 ± 6.4 years. Mean preoperative spherical equivalent was ?3.62 ± 2.31D. Average preoperative RNFL thickness was 94.6 ± 12.1?m in MMK group while the postoperative average thickness was 95.1 ± 11.9 um with no statistically significant difference (P-value: 0.37). Average preoperative RNFL thickness was 108.28 ± 8.4 ?m in FS group compared to 108.38 ± 11.2 ?m in the postoperative average with no statistically significant difference (P-value: 0.94). Mean “Suction ON” to “Suction OFF” time was 22 seconds in the MMK group compared to 41 seconds in the FS group. Conclusion The rise of intraocular pressure during application of suction ring in LASIK surgery does not affect the RNFL thickness as measured by SD-OCT, whether the flap is created by MMK or FS. PMID:24109171

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

2013-01-01

105

Fibre Bragg gratings and fibre interferometers for medical applications  

Microsoft Academic Search

In this presentation three rather different types of fibre optic probe for medical applications are presented: temperature profile monitoring based upon a multiplexed array of fibre Bragg gratings (FBG); FBG ultrasonic probe; miniature pressure sensor based on a Fizeau cavity.

D. A. Jackson

2000-01-01

106

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

107

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

PubMed Central

Purpose: To compare the visual field index (VFI) in primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) eyes, and to study the correlation with disc variables on optical coherence tomography (OCT) in all stages of severity. Materials and Methods: Thirty POAG and PACG underwent Humphrey visual field 24-2 along with detailed examination. They also underwent stratus OCT imaging of the optic nerve and retinal nerve fiber layer (RNFL). The correlation of VFI with RNFL thickness was compared in POAG and PACG. Results: The VFI significantly differed between POAG and PACG, with POAG eyes apparently having a better VFI at all severities of glaucoma. There were statistically significant differences in the superior max (Smax) and inferior max (Imax) in early and moderate POAG and PACG eyes. In early and moderate glaucoma, multivariate regression showed that maximum correlation of the VFI was seen with the mean deviation (b = 1.7, P < 0.001), average and superior RNFL thickness (b = 2.1, P < 0.001 and b = 1.8, P = 0.03, respectively), and age (b = 0.7, P = 0.04); while no correlation was seen with intraocular pressure (IOP), axial length, sex, or other clinical variables. VFI did not correlate well with RNFL thickness or other disc variables on OCT in severe glaucoma. Conclusion: VFI may not serve as a useful indicator of visual function in severe glaucoma. More useful indicators are required to monitor glaucoma patients with severe damage. PMID:24799794

Rao, Aparna

2014-01-01

108

Tensile fatigue properties of fibre Bragg grating optical fibre sensors  

Microsoft Academic Search

This paper presents an experimental study into the tensile strength and fatigue properties of uncoated optical glass fibres containing Bragg grating (FBG) sensors. The protective polymer coating of the optical fibres must be removed by chemical or mechanical stripping methods to produce the Bragg gratings in the fibre core. This paper investigates the effects of chemical or mechanical stripping on

J. Ang; H. C. H. Li; I. Herszberg; M. K. Bannister; A. P. Mouritz

2010-01-01

109

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

Microsoft Academic Search

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

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

1978-01-01

110

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

111

Health monitoring of composite plastic waterworks lock gates using in-fibre Bragg grating sensors  

Microsoft Academic Search

A new concept of fibre-reinforced composite layered material lock gates has been developed to be used on navigable waterways. To contribute to the validation of the prototype, a permanent optical fibre sensor non-destructive evaluation system was installed. Qualification measurements using both electrical strain gauges and in-fibre Bragg gratings (FBGs) demonstrate usability and advantages of FBG sensors as a lifecycle health

Michel Bugaud; Pierre Ferdinand; Stéphane Rougeault; Véronique Dewynter-Marty; Patrick Parneix; Dominique Lucas

2000-01-01

112

Microstructure and performance of novel Ni anode for hollow fibre solid oxide fuel cells  

Microsoft Academic Search

Nickel anodes were deposited on hollow fibre yttria-stabilised zirconia (YSZ) electrolyte substrates for use in solid oxide fuel cells (SOFCs). The hollow fibres are characterised by porous external and internal surfaces supported by a central gas-tight layer (300 ?m total wall thickness and 1.6 mm external diameter). The YSZ hollow fibres were prepared by a phase inversion technique followed by high temperature

Francesco Dal Grande; Alan Thursfield; Krzysztof Kanawka; Nicolas Droushiotis; Uttam Doraswami; Kang Li; Geoff Kelsall; Ian S. Metcalfe

2009-01-01

113

Muscle fibre types in the external eye muscles of the pigeon, Columba livia.  

PubMed Central

Fibre typing with antisera raised against specific myosin types from muscles of known physiological properties were used to characterise the fibre types within the oculorotatory muscles of pigeons. Fibres reacting strongly to antiserum anti-ALD (specific for tonic fibre myosin) were found lying along the global margin of the muscle and also in a layer lying immediately beneath a discrete band of fibres running along the orbital margin. These fibres resembled those of the skeletal muscle ALD in their type properties. Using another antiserum, anti-I, specific for slow twitch and to a lesser extent, slow tonic myosins, it was possible to identify another slow fibre type which formed the orbital layer and also lay scattered randomly through the body of the muscle. No equivalent to this type was found in the skeletal muscles ALD or iliofibularis. The remaining fibres which did not react with either anti-ALD or anti-I formed 58% of the fibre population and reacted with an antiserum specific for fast myosin. However, their response to alkali preincubation suggests that the fast fibres of eye muscles also contain a myosin which is different from those in skeletal muscle. Images Fig. 1 Fig. 2 Fig. 3 PMID:2965693

McVean, A; Stelling, J; Rowlerson, A

1987-01-01

114

Fibre gratings and their applications  

SciTech Connect

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

Vasil'ev, Sergei A; Medvedkov, O I; Korolev, I G; Bozhkov, A S; Kurkov, Andrei S; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2005-12-31

115

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

116

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

Microsoft Academic Search

A fibre Raman amplifier operating at a wavelength of 1.65-mum is fabricated. A two-stage phosphosilicate fibre Raman converter of 1.53-mum radiation for pumping the Raman amplifier is designed and tested. The amplifier pumped by a phosphosilicate fibre Raman converter can operate with a maximum of the gain band ranging from 1.6 to 1.7 mum. A fibre with a core of

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

2002-01-01

117

Multifunctional conducting fibres with electrically controlled release of ciprofloxacin.  

PubMed

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

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

2013-08-10

118

Identification and localization of suberin in the cell walls of green cotton fibres ( Gossypium hirsutum L., var. green lint)  

Microsoft Academic Search

Summary The secondary cell walls of fibres of the green lint variety of cotton are strongly autofluorescent and stain with both Sudan III and osmium tetroxide. In the electron microscope thin sections of aldehydeosmium fixed fibres show concentric, osmiophilic layers in the walls, each separated by cellulosic material. The number of these layers corresponds approximately to the number of days

U. Ryser; H. Meier; P. J. Holloway

1983-01-01

119

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

120

Electrodynamic approach to the estimate of the pumping efficiency of double cladding active optical fibres  

SciTech Connect

A method of increasing the pumping efficiency of active optical fibres doped with Er{sup 3+} ions by decreasing the diameter of the inner cladding is analysed. An active optical fibre is described by using the electrodynamic model of a three-layer dielectric waveguide. The dependence of the average pump power flux through the core on the ratio of the radii of the core and the inner cladding is obtained. It is shown that this dependence can also be interpreted as the dependence of the damping constant averaged over all the waves in the core and the cladding. (optical fibres and fibre lasers)

Britov, I E; Raevskii, A S [Nizhnii Novgorod State Technical University, Nizhnii Novgorod (Russian Federation); Kurkov, Andrei S [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2002-05-31

121

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

SciTech Connect

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

Yatsenko, Yu P [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Mashinsky, V M; Medvedkov, O I; Sazhin, O D; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Khopin, V F; Vechkanov, N N; Gur'yanov, A N [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2003-03-31

122

Experimental and theoretical study of optical losses in straight and bent Bragg fibres  

SciTech Connect

The leakage loss in straight and bent Bragg fibres has been studied experimentally and theoretically using five fibres differing in the core diameter, the number of layers in the Bragg mirror and their refractive indices. Simple analytical formulas have been derived within ray-optics theory which describe leakage and bending losses. The optical loss calculated using these formulas agrees well with our experimental data. Analysis of the theoretical and experimental results enables us to assess the effect of parameters of the waveguiding system on the optical loss in straight and bent fibres. (optical fibres)

Aleshkina, S S; Likhachev, M E; Bubnov, M M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Uspenskii, Yurii A [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-12-09

123

Dissolution behaviour of model basalt fibres studied by surface analysis methods  

NASA Astrophysics Data System (ADS)

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

Förster, T.; Scheffler, C.; Mäder, E.; Heinrich, G.; Jesson, D. A.; Watts, J. F.

2014-12-01

124

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

PubMed

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

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

2014-07-01

125

OPTICAL FIBRES: Optical properties of fibres with aluminophosphosilicate glass cores  

Microsoft Academic Search

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

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

2009-01-01

126

OPTICAL FIBRES: Photosensitivity of optical fibres doped with different impurities  

Microsoft Academic Search

Photosensitivities of hydrogen-loaded silica fibres doped with germanium, phosphorus, antimony, and aluminium are estimated and compared. It is shown that although all the fibres can be pre-exposed, the degree of this effect is noticeably different for different fibres because the induction of the refractive index is determined by a combined contribution from a one-step photochemical reaction and a two-step reaction

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

2004-01-01

127

Synaptic modification of parallel fibre-Purkinje cell transmission in in vitro guinea-pig cerebellar slices.  

PubMed Central

1. Synaptic transmission from parallel fibres to Purkinje cells and its modification by paired stimulation of parallel fibres and climbing fibres were studied in in vitro slices of the cerebellum obtained from guinea-pigs. 2. Intracellular recordings were made from Purkinje cells, mainly from dendrites in the middle third of the molecular layer, but also, in a few cases, from somata. Climbing fibres were activated by stimulation of the white matter, while parallel fibres were stimulated with an electrode placed near the pial surface of the molecular layer. 3. Stimulation of the white matter elicited antidromic spikes, all-or-none climbing fibre responses, disynaptic responses through mossy fibres and parallel fibres, and trisynaptic responses through inhibitory interneurones. Climbing fibre responses were often followed by a small plateau potential, usually less than 2-3 mV in amplitude and less than 100 ms in duration, followed by a slow hyperpolarization which reached its peak in several seconds. Inhibitory inputs to Purkinje cells were blocked with picrotoxin for the experiments described below. 4. Stimulation of the superficial molecular layer with currents less than 50 microA produced graded parallel fibre-mediated excitatory postsynaptic potentials (e.p.s.p.s) ranging from 4 to 8 mV in peak amplitude. 5. Conjunctive stimulation of climbing fibres and parallel fibres at 4 Hz for 25 s induced depression of parallel fibre-mediated e.p.s.p.s in Purkinje cells, both in the peak amplitudes and in the slopes. The depression was about 30% on average and lasted for more than 50 min. 6. No such depression occurred when the intensity of the white matter stimulation was set just subthreshold for the climbing fibre innervating the Purkinje cell under study. Instead, the parallel fibre-mediated e.p.s.p.s were moderately potentiated for a period ranging from 10 to 50 min. Repetitive stimulation of the climbing fibre alone did not affect parallel fibre-mediated e.p.s.p.s. 7. Immediately after the conjunctive stimulation or the repetitive stimulation of climbing fibres alone, a transient hyperpolarization which lasted for several minutes was seen. Its time course was similar to that of the hyperpolarization following a climbing fibre response. Except for this, there were no associated changes in the membrane potential, the input resistance, or the magnitudes of climbing fibre responses in any of the cases mentioned in 5 and 6 above. Images Fig. 1 PMID:2832595

Sakurai, M

1987-01-01

128

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

NASA Astrophysics Data System (ADS)

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

Bhatt, Mittal G.; Rao, Navalgund

2005-04-01

129

Distributed ultrafast fibre laser  

NASA Astrophysics Data System (ADS)

A traditional ultrafast fibre laser has a constant cavity length that is independent of the pulse wavelength. The investigation of distributed ultrafast (DUF) lasers is conceptually and technically challenging and of great interest because the laser cavity length and fundamental cavity frequency are changeable based on the wavelength. Here, we propose and demonstrate a DUF fibre laser based on a linearly chirped fibre Bragg grating, where the total cavity length is linearly changeable as a function of the pulse wavelength. The spectral sidebands in DUF lasers are enhanced greatly, including the continuous-wave (CW) and pulse components. We observe that all sidebands of the pulse experience the same round-trip time although they have different round-trip distances and refractive indices. The pulse-shaping of the DUF laser is dominated by the dissipative processes in addition to the phase modulations, which makes our ultrafast laser simple and stable. This laser provides a simple, stable, low-cost, ultrafast-pulsed source with controllable and changeable cavity frequency.

Liu, Xueming; Cui, Yudong; Han, Dongdong; Yao, Xiankun; Sun, Zhipei

2015-03-01

130

Fibre-optical microendoscopy.  

PubMed

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

Gu, M; Bao, H; Kang, H

2014-04-01

131

Distributed ultrafast fibre laser.  

PubMed

A traditional ultrafast fibre laser has a constant cavity length that is independent of the pulse wavelength. The investigation of distributed ultrafast (DUF) lasers is conceptually and technically challenging and of great interest because the laser cavity length and fundamental cavity frequency are changeable based on the wavelength. Here, we propose and demonstrate a DUF fibre laser based on a linearly chirped fibre Bragg grating, where the total cavity length is linearly changeable as a function of the pulse wavelength. The spectral sidebands in DUF lasers are enhanced greatly, including the continuous-wave (CW) and pulse components. We observe that all sidebands of the pulse experience the same round-trip time although they have different round-trip distances and refractive indices. The pulse-shaping of the DUF laser is dominated by the dissipative processes in addition to the phase modulations, which makes our ultrafast laser simple and stable. This laser provides a simple, stable, low-cost, ultrafast-pulsed source with controllable and changeable cavity frequency. PMID:25765454

Liu, Xueming; Cui, Yudong; Han, Dongdong; Yao, Xiankun; Sun, Zhipei

2015-01-01

132

Distributed ultrafast fibre laser  

PubMed Central

A traditional ultrafast fibre laser has a constant cavity length that is independent of the pulse wavelength. The investigation of distributed ultrafast (DUF) lasers is conceptually and technically challenging and of great interest because the laser cavity length and fundamental cavity frequency are changeable based on the wavelength. Here, we propose and demonstrate a DUF fibre laser based on a linearly chirped fibre Bragg grating, where the total cavity length is linearly changeable as a function of the pulse wavelength. The spectral sidebands in DUF lasers are enhanced greatly, including the continuous-wave (CW) and pulse components. We observe that all sidebands of the pulse experience the same round-trip time although they have different round-trip distances and refractive indices. The pulse-shaping of the DUF laser is dominated by the dissipative processes in addition to the phase modulations, which makes our ultrafast laser simple and stable. This laser provides a simple, stable, low-cost, ultrafast-pulsed source with controllable and changeable cavity frequency. PMID:25765454

Liu, Xueming; Cui, Yudong; Han, Dongdong; Yao, Xiankun; Sun, Zhipei

2015-01-01

133

Properties of nanocomposite PP fibres  

NASA Astrophysics Data System (ADS)

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

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

2005-06-01

134

Vectran High-performance Fibre  

Microsoft Academic Search

Vectran fibre is a high-performance fibre produced from Hoechst Celanese Vectra polymer. The Vectra family of liquid-crystal engineering resins was commercialized in 1985 after more than fifteen years of research and development on naphthalene-based thermotropic copolyesters. Since 1986, Hoechst Celanese and the Kuraray Company Ltd of Japan have jointly evaluated these materials in fibre applications.The attributes of the Vectra liquid-crystal

D. E. Beers; J. E. Ramirez

1990-01-01

135

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

PubMed

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

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

1997-08-01

136

Sulphur-doped silica fibres  

SciTech Connect

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

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

2003-01-31

137

Investigation of industrial tea-leaf-fibre waste material for its sound absorption properties  

Microsoft Academic Search

The sound absorption of an industrial waste, developed during the processing of tea leaves has been investigated. Three different layers of tea-leaf-fibre waste materials with and without backing provided by a single layer of woven textile cloth were tested for their sound absorption properties. The experimental data indicate that a 1cm thick tea-leaf-fibre waste material with backing, provides sound absorption

Sezgin Ersoy; Haluk Küçük

2009-01-01

138

Influence of short-fibre reinforcement on the fracture behaviour of a bulk liquid crystal polymer  

Microsoft Academic Search

The microstructure and some mechanical properties of a liquid crystal polymer (LCP) and its short-fibre composites have been investigated. Injection moulded plates of the latter materials exhibit a layered structure well-known for many short-fibre reinforced polymer systems. A pronounced layered structure is also found in the neat LCP matrix, superimposed by a certain degree of molecular orientation. The special, microstructural

H. Voss; K. Friedrich

1986-01-01

139

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

140

Fibre Bragg Gratings Inscribed in Homemade Microstructured Fibres  

Microsoft Academic Search

Fibre Bragg gratings (FBGs) are inscribed in homemade microstructured fibres by the standard phase mask method. Enhanced couplings between the forward fundamental mode and backward cladding modes are obtained. The mode coupling and spectral characteristics are investigated experimentally. The cladding mode resonances can be affected by filling active materials into the air holes, which will be useful for the implementation

Long Jin; Gui-Yun Kai; Jin-Yan Li; Wei Chen; Jian-Guo Liu; Yan-Ge Liu; Zhi Wang; Jian Zhang; Bo Liu; Shu-Zhong Yuan; Xiao-Yi Dong

2007-01-01

141

A definition for dietary fibre  

Microsoft Academic Search

The objective of this paper is to present a definition for dietary fibre based on recent advances that have taken place not only in human nutrition but also in plant cell-wall science and animal nutrition. We propose a physiologically based framework definition but, recognizing the diversity of dietary fibre, we have proposed further classifications within this framework. We also suggest

M-A Ha; MC Jarvis; JI Mann

2000-01-01

142

Submicroscopic fibres in industrial atmospheres.  

PubMed

Evidence obtained from a large number of samples of airborne dust from a number of different asbestos-using industries suggests that it would be possible to use gravimetric sampling to estimate the respirable fibre concentration of the atmosphere around specific operations. The precision of this method of estimating airborne fibre concentration is shown to be approximately the same as the variation between different counters using existing counting techniques. Tables are included showing the fibre content of industrial dusts in millions of fibres/mg of dust and the factors (with 95% confidence limits) by which light microscope counts should be multiplied to give the true counts of fibres longer than 5 micrometers. PMID:7014440

Rendall, R E; Skikne, M I

1980-01-01

143

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

PubMed Central

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

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

2015-01-01

144

The influence of fibre sizing on the strength and fracture toughness of glass fibre composites  

Microsoft Academic Search

The influence of the fibre\\/matrix interface strength on fibre cross-over bridging in a crack along fibres is investigated. Four different composite systems (commercial glass fibre with two different sizings and two matrix resins) resulting in strong and weak interfaces were manufactured. Their crack growth resistance during crack propagation with fibre bridging in a double cantilever beam specimen loaded with end

S. Feih; J. Wei; P. Kingshott; B. F. Sørensen

2005-01-01

145

Multilayered Glass Fibre-reinforced Composites In Rotational Moulding  

SciTech Connect

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

Chang, W. C.; Harkin-Jones, E. [School of Mechanical and Aerospace Engineering, Queen's University Belfast, Ashby Building, Stranmillis Road, Belfast BT9 5AH, Northern Ireland (United Kingdom); Kearns, M.; McCourt, M. [Polymer Processing Research Centre, Queen's University Belfast, Ashby Building, Stranmillis Road, Belfast BT9 5AH Northern Ireland (United Kingdom)

2011-05-04

146

Thermal and fatigue cycling of fibre composites  

Microsoft Academic Search

Systematic investigations on the thermal and mechanical properties of fibre composites (fibre glass, carbon fibres, Kevlar fibres) have been performed. Special emphasis is put on the influence of the matrix on the properties. In particular, the fatigue behaviour is different for duroplastic (brittle) and thermoplastic (ductile) matrix materials. A survey of these properties is given.

Günther Hartwig; Ralph Hübner

1995-01-01

147

Ring structures in microstructured polymer optical fibres  

Microsoft Academic Search

Recent developments in polymer microstructured optical fibres allow for the realisation of microstructures in fibres that would be problematic to fabricate using glass-based capillary stacking. We present one class of such structures, where the holes lie on circular rings. A fibre of this type is fabricated and shown to be single moded for relatively long lengths of fibre, whereas shorter

Alexander Argyros; Ian Bassett; Martijn van Eijkelenborg; Maryanne C. J. Large; Joseph Zagari; Nicolae A. P. Nicorovici; Ross C. McPhedran; C. Martijn de Sterke

2001-01-01

148

Polypropylene composites with enzyme modified abaca fibre  

Microsoft Academic Search

Abaca fibre reinforced PP composites were prepared using a high speed mixer followed by injection moulding with 30wt.% of fibre load. Prior to composite production, the fibres were modified by fungamix and natural enzyme. The effects of modification of the fibre were assessed on the basis of morphology and thermal resistance and as well as on mechanical, thermal and environmental

Andrzej K. Bledzki; Abdullah A. Mamun; Adam Jaszkiewicz; Karsten Erdmann

2010-01-01

149

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

150

Whispering-gallery waves in optical fibres  

SciTech Connect

The process of excitation of whispering-gallery waves (WGWs) in optical fibres (microcavities) with the help of a bitapered fibre is analysed. It is shown that useful information on the WGW modes can be obtained from the spectrograms recorded by scanning the exciting-radiation frequency. Based on the geometrical-optic approximation, the longitudinal sizes of the WGW modes are estimated and it is shown that the ultimate diameter of the fibre exists for optical fibres (microcavities) where a mode can be still excited with the help of a bitapered fibre. (fibre optics. optical fibres)

Sychugov, V A; Torchigin, V P; Tsvetkov, M Yu [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2002-08-31

151

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

PubMed Central

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

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

2008-01-01

152

Polarisation reflectometry of anisotropic optical fibres  

SciTech Connect

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

Konstantinov, Yurii A; Kryukov, Igor' I; Pervadchuk, Vladimir P; Toroshin, Andrei Yu [Institute of Photonics and Optoelectronic Device Manufacturing, Perm State Technical University, Perm (Russian Federation)

2009-11-30

153

Exciplex laser spatial coherence and its impact on fibre Bragg grating writing in large diameter fibres  

Microsoft Academic Search

The spatial coherence of an ArF exciplex (excimer) laser has been investigated by writing fibre Bragg gratings in photosensitive boron-codoped germanosilicate fibre to analyse the effect of limited spatial coherence on large diameter fibres.

Nathaniel Groothoff; John Canning

2006-01-01

154

Symplectic properties of Milnor fibres  

E-print Network

We present two results relating to the symplectic geometry of the Milnor fibres of isolated affine hypersurface singularities. First, given two Lagrangian spheres in an exact symplectic manifold, we find conditions under ...

Keating, Ailsa Macgregor

2014-01-01

155

Mechanical Properties of Natural-Fibre-Mat- Reinforced Thermoplastics based on Flax Fibres and Polypropylene  

Microsoft Academic Search

Thermoplastic composites based on flax fibres and a polypropylene (PP) matrix were manufactured using (i) a film-stacking method based on random fibre mats and (ii) a paper making process based on chopped fibres. The influence of fibre length and fibre content on stiffness, strength and impact strength of these so-called natural-fibre-mat-reinforced thermoplastics (NMTs) is reported and compared with data for

S. K. Garkhail; R. W. H. Heijenrath; T. Peijs

2000-01-01

156

Strain development in curing epoxy resin and glass fibre\\/epoxy composites monitored by fibre Bragg grating sensors in birefringent optical fibre  

Microsoft Academic Search

Fibre Bragg gratings (FBGs) fabricated in linearly birefringent fibres were embedded in glass fibre\\/epoxy composites and in the corresponding unreinforced resin to monitor the effective transverse strain development during the cure process. The optical fibres containing the FBG sensors were aligned either normal or parallel to the reinforcement fibres in unidirectional glass fibre\\/epoxy prepregs. The chemical cure kinetics of the

E. Chehura; A. A. Skordos; C.-C. Ye; S. W. James; I. K. Partridge; R. P. Tatam

2005-01-01

157

Compressive properties of aramid fibres  

Microsoft Academic Search

A four-point bending beam method has been employed in order to study the compressive properties of a number of well-characterized aromatic polyamide (aramid) fibres using a combination of Raman spectroscopy and optical microscopy. Raman spectroscopy has been used to follow the molecular deformation of the aramid fibres in both tension and compression, from which the stress\\/strain data have been derived.

M. C. Andrews; D. Lu; R. J. Young

1997-01-01

158

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

SciTech Connect

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

Baum, Ol'ga I; Mishakov, Gennadii V; Sokolov, Viktor I [Institute of Laser and Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation); Varlamova, Nina V; Zapadinskii, Boris I [N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow (Russian Federation)

2004-09-30

159

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

Microsoft Academic Search

The proton spin-spin relaxation time, T2, measured from solid-state NMR, indicates a greater rigidity for cellulose than for the adhesive matrix between the microfibrils of flax ultimate fibres. Cytochemical and biochemical analyses allow the identification of: (1) EDTA-soluble RG I-polymers in the primary walls and cell junctions of fibres; (2) long 1?4-?-d-galactan chains between primary and secondary wall layers; and

Raynald Girault; Francois Bert; Christophe Rihouey; Alain Jauneau; Claudine Morvan; Michael Jarvis

1997-01-01

160

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

Microsoft Academic Search

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

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

161

Wetting of flexible fibre arrays.  

PubMed

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

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

2012-02-23

162

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

163

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

164

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

165

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

PubMed Central

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

Chen, Teresa C.

2009-01-01

166

Carbon-fibre-reinforced plastic (CFRP) strengthening of aluminium extrusions  

Microsoft Academic Search

The flexural behaviour of compound beams in which unidirectional carbon-fibre-reinforced plastic (CFRP) is externally bonded to extruded aluminium box-sections, is discussed. Simple transformed-section analysis and elastic buckling theory have been adapted to predict improvements in stiffness and strength with single-layer reinforcement. Close correlation between theory and experiment is observed and maximum gains in stiffness and ultimate strengths of 75% and

J. G. Broughton; A. Beevers; A. R. Hutchinson

1997-01-01

167

Postponed sowing does not alter the fibre\\/wood ratio or fibre extractability of fibre hemp (Cannabis sativa)  

Microsoft Academic Search

Because hemp is a short-day plant, postponing the sowing date might be a suitable strategy to obtain shorter and smaller plants around flowering, when primary fibres are 'ripe' enough to be harvested. Smaller plants can be processed on existing flax scutching and hackling lines and might have fibre characteristics that are desirable for producing high-quality 'long fibres' for yarn spinning.

W. Westerhuis; P. C. Struik; Dam van J. E. G; T. J. Stomph

2009-01-01

168

Reproducibility of RTVue Retinal Nerve Fiber Layer Thickness and Optic Disc Measurements and Agreement with Stratus Optical Coherence Tomography Measurements  

PubMed Central

PURPOSE To evaluate RTVue spectral-domain optical coherence tomography (OCT) (Optovue Inc, Fremont, California, USA) reproducibility and to assess agreement with Stratus time-domain OCT (Carl Zeiss Meditec, Dublin, California, USA) measurements. DESIGN Observational clinical study. METHODS Scans were obtained from both eyes of all participants 3 times using the RTVue nerve head map 4-mm diameter protocol and once using Stratus OCT within the same session. RTVue reproducibility and agreement with Stratus OCT were evaluated for retinal nerve fiber layer (RNFL) and optic disc measurements. RESULTS Thirty healthy participants (60 eyes) and 38 glaucoma patients (76 eyes) were included in the study. RTVue reproducibility was good in both healthy participants and patients. For average RNFL thickness, the intraclass correlation coefficients in healthy eyes and patient eyes were 0.97 whereas for rim area they were 0.97 and 0.96, respectively. The correlation between RTVue and Stratus measurements generally was good, especially for average RNFL thickness (healthy eyes and patient eyes, r2 = 0.82 and 0.86, respectively) and rim volume (healthy eyes and patient eyes, r2 = 0.78 and 0.76, respectively). Bland-Altman plots showed good agreement between the instruments, with better agreement for average RNFL thickness (95% limits of agreement in healthy eyes and patient eyes, ?8.6 to 12 µm and ?5.6 to ?14.8 µm, respectively) than optic disc parameters. Cup-to-disc ratio 95% limits of agreement in healthy eyes and patient eyes were ?0.3 to 0.4 and ?0.2 to 0.3, respectively. Optic disc measurements with RTVue were smaller than those with Stratus OCT (eg, disc area was on average 0.4 mm2 smaller and rim area was 0.3 mm2 smaller with RTVue). CONCLUSIONS Reproducibility of RTVue RNFL and optic disc measurements was excellent in both groups. The level of agreement between RTVue and Stratus measurements suggests that RTVue has the potential to detect glaucomatous structural changes. PMID:19268891

González-García, Alberto O.; Vizzeri, Gianmarco; Bowd, Christopher; Medeiros, Felipe A.; Zangwill, Linda M.; Weinreb, Robert N.

2009-01-01

169

Fibre-epoxy composites at low temperatures  

NASA Astrophysics Data System (ADS)

The thermal and mechanical properties of carbon, glass and Kevlar fibre reinforced epoxy composites are discussed, with particular reference to the behaviour of these materials at cryogenic temperatures. The effects of production techniques and various fibre arrangements are determined.

Hartwig, G.; Knaak, S.

170

Moderate-power cw fibre lasers  

SciTech Connect

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

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

2004-10-31

171

In-fibre Bragg grating sensors  

Microsoft Academic Search

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

Yun-Jiang Rao

1997-01-01

172

Optical properties of microstructure tellurite glass fibres  

SciTech Connect

The dispersion characteristics and waveguide optical losses are calculated by the multipole method for microstructure optical fibres with a continuous core, which can be made of a tellurite glass holding much promise for fibre optics. The effect of geometrical parameters on the optical properties is studied and conditions for the single-mode propagation of radiation in such fibres are determined. (optical fibres and waveguides)

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

2006-04-30

173

Composites reinforced with cellulose based fibres  

Microsoft Academic Search

This review article concerning natural and man-made cellulose fibre reinforced plastics, introduces possible applications of this material group. The physical properties of natural fibres are mainly determined by the chemical and physical composition, such as the structure of fibres, cellulose content, angle of fibrils, cross-section, and by the degree of polymerization. Only a few characteristic values, but especially the specific

A. K Bledzki; J Gassan

1999-01-01

174

Glass Fibre Reinforced Cement and Gypsum Products  

Microsoft Academic Search

Glass fibre reinforced cements and gypsum plaster provide examples of composite materials where both the components are brittle and the matrix phase fails at a much lower strain than the fibre. Porosities of the order of 30% or more are usually present in these matrices. The interfacial bond that develops between the fibre and the matrix is very discontinuous and

A. J. Majumdar

1970-01-01

175

Respiratory muscle fibres: specialisation and plasticity  

PubMed Central

Skeletal muscles are composed of fibres of different types, each type being identified by the isoform of myosin heavy chain which is expressed as slow 1, fast 2A, fast 2X, and fast 2B. Slow fibres are resistant to fatigue due to their highly oxidative metabolism whereas 2X and 2B fibres are easily fatiguable and fast 2A fibres exhibit intermediate fatigue resistance. Slow fibres and fast fibres are present in equal proportions in the adult human diaphragm while intercostal muscles contain a higher proportion of fast fibres. A small fibre size, abundance of capillaries, and a high aerobic oxidative enzyme activity are typical features of diaphragm fibres and give them the resistance to fatigue required by their continuous activity. Because of their fibre composition, intercostal muscles are less resistant to fatigue. The structural and functional characteristics of respiratory muscle fibres are not fixed, however, and can be modified in response to several physiological and pathological conditions such as training (adaptation to changes in respiratory load), adaptation to hypoxia, age related changes, and changes associated with respiratory diseases. The properties of respiratory muscle fibres can also be modified by pharmacological agents such as ß2 agonists and corticosteroids used for the treatment of respiratory diseases. PMID:15333861

Polla, B; D'Antona, G; Bottinelli, R; Reggiani, C

2004-01-01

176

Raman fibre lasers based on heavily GeO{sub 2}-doped fibres  

SciTech Connect

Amplification of radiation due to stimulated Raman scattering in an optical fibre with a heavily GeO{sub 2}-doped core and a fused silica cladding is studied. The applications of such fibres in Raman lasers are demonstrated. A Raman fibre laser emitting 10 W at a fibre length of only 3 m and Raman lasers emitting at 1.73, 1.85, 2.06, and 2.2 {mu}m are fabricated for the first time. (fibre lasers)

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

2005-05-31

177

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

Microsoft Academic Search

This study examined the effect of type of wood fibre source on the physical and mechanical properties of wood fibre-polypropylene\\u000a composites. Wood flour, fibres of heat-treated wood and pellets were used as sources of wood fibres in the manufacturing process.\\u000a All studied wood fibre-polypropylene composites were made from 75% wood, 22% recycled polypropylene (PP) and 3% maleated polypropylene\\u000a (MAPP). Wood

Svetlana Butylina; Ossi Martikka; Timo Kärki

2011-01-01

178

Liquid crystal assisted optical fibres.  

PubMed

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

Wahle, M; Kitzerow, H-S

2014-01-13

179

Palladium coated ball lens for optical fibre refractometry based hydrogen sensing  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

180

`Giant' Fibres in Dragonfly Nymphs  

Microsoft Academic Search

A PRELIMINARY study of transverse and horizontal sections through the ventral nerve cord of late instar nymphs of Anax imperator (Anisoptera) has revealed several notable features. Accurate counts of the number of fibres within the commissures have shown that these range continuously from 0 to 16 µ, as set out in the accompanying histogram (Fig. 1). The total number of

G. M. Hughes

1953-01-01

181

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

182

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

183

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

184

Fragmentation of aramid fibres in single-fibre model composites  

Microsoft Academic Search

Raman spectroscopy has been used to monitor the state of axial stress along fragmented, high-modulus Kevlar 149 aramid fibres in an epoxy resin matrix by monitoring the peak position of the strain-sensitive 1610 cm-1 aramid Raman band along individual fragments. It is shown that the interfacial shear stress along each fragment, derived from the strain distribution profiles, is not constant

M. C. Andrews; R. J. Young

1995-01-01

185

Nanoporous carbon fibres by pyrolysis of nomex polyaramid fibres  

Microsoft Academic Search

Summary The development of porosity upon pyrolysis of Nomex®[poly (m-phenylene isophthalamide)] fibres has been investigated up to a temperature of 1173 K through physical adsorption of N2 (77 K) and CO2 (273 K). The carbonisation temperatures were chosen on the basis of thermal analysis studies (TG and DTA). The results of porous texture characterisation were compared with characteristic features in

J. M. D. Tascón

2005-01-01

186

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

187

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

188

Squeeze flow of concentrated long fibre suspensions: experiments and model  

Microsoft Academic Search

Experimental squeeze flow results show that the behaviour of concentrated short fibre suspensions and concentrated long fibre suspensions impregnated with polymer melts are qualitatively different. Short fibre suspensions have a low yield stress, have an overall squeeze pressure independent of the fibre length, but gap dependent. In contrast, long fibre suspensions have a higher yield stress and their squeeze pressure

Colin Servais; André Luciani; Jan-Anders E. Månson

2002-01-01

189

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

190

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 Leão; Sivoney Ferreira de Souza; Sabu Thomas; Laly A. Pothan; M. Kottaisamy

2010-01-01

191

Relationship between structure and mechanical properties for aramid fibres  

Microsoft Academic Search

The relationship between structure and mechanical properties for a series of twelve wellcharacterized aramid fibres has been determined. The fibres were produced under a variety of processing conditions and the fibre structure has been characterized using transmission electron microscopy. In particular, both the overall degree of molecular orientation in the fibres and the difference in structure between the fibre skin

R. J. Young; D. Lu; R. J. Day; W. F. Knoff; H. A. Davis

1992-01-01

192

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

193

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

PubMed Central

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

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

1999-01-01

194

Impurity effects in carbon fibres  

Microsoft Academic Search

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

M. L. Lieberman; G. T. Noles

1972-01-01

195

Quantum Networking with Optical Fibres  

E-print Network

I propose a scheme which allows for reliable transfer of quantum information between two atoms via an optical fibre in the presence of decoherence. The scheme is based on performing an adiabatic passage through two cavities which remain in their respective vacuum states during the whole operation. The scheme may be useful for networking several ion-trap quantum computers, thereby increasing the number of quantum bits involved in a computation.

T. Pellizzari

1997-07-01

196

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.

197

Bend effects on fibre Bragg gratings in standard and low bend loss optical fibres  

Microsoft Academic Search

Summary The effects of relatively small bend diameters on fibre Bragg gratings written in standard and low bend loss fibre have been investigated. Results including Bragg wavelength shifts with bending are reported.

Alexander C. Thompson; William G. A. Brown; Paul R. Stoddart; Scott A. Wade

2010-01-01

198

Fibre bragg gratings optical sensing technology  

Microsoft Academic Search

Fibre optic technology is a well established field in the world of smart structures. While optical communications systems date back as far as the late 1700s when the French engineer Claude Chappe invented the ‘optical telegraph’, advances in optical fibres did not really take off until Corning Glass Works (now Corning, Inc.) developed single-mode fibres with attenuation below 20 dB\\/km

Toni Poloso

2001-01-01

199

Single-mode optical fibre thermocoupler based on regenerated fibre Bragg gratings evaluated at ~1500 °C  

Microsoft Academic Search

The viability of an all-optical fibre optical thermocoupler for remote sensing of ultra-high temperatures, independent of electronics, is explored. Simple packaging of regenerated fibre Bragg gratings (FBGs) within silica capillaries were shown to protect the fibre structure sufficiently to allow the temperature measurement of a furnace element to >1500 °C a temperature at which the regenerated FBG, which was written

Mattias L. Åslund; John Canning; Hongyan Fu; Hwayaw Tam

2010-01-01

200

Tensile and compressive properties of flax fibres for natural fibre reinforced composites  

Microsoft Academic Search

Mechanical properties of standard decorticated and hand isolated flax bast fibres were determined in tension as well as in compression. The tensile strength of technical fibre bundles was found to depend strongly on the clamping length. The tensile strength of elementary flax fibres was found to range between 1500 MPa and 1800 MPa, depending on the isolation procedure. The compressive

H. L. Bos; M. J. A. Van Den Oever; O. C. J. J. Peters

2002-01-01

201

OPTICAL FIBRES: Enhanced diffusion of molecular hydrogen in germanosilicate fibres loaded with hydrogen at high pressures  

Microsoft Academic Search

Absorption spectra and spontaneous Raman spectra of optical fibres with a germanosilicate core loaded with molecular hydrogen at a pressure of 150-170 MPa are studied; the variation of these spectra during the outdiffusion of hydrogen from the fibres is also investigated. The purely rotational transitions of molecular hydrogen in Raman spectra of optical fibres are recorded for the first time.

Sergei A. Vasil'ev; A. O. Rybaltovskii; V. V. Koltashev; V. O. Sokolov; Semen N. Klyamkin; O. I. Medvedkov; A. A. Rybaltovsky; A. R. Malosiev; V. G. Plotnichenko; Evgenii M. Dianov

2005-01-01

202

Oil Palm Fibre Reinforced Phenol Formaldehyde Composites: Influence of Fibre Surface Modifications on the Mechanical Performance  

Microsoft Academic Search

Oil palm fibres have been used as reinforcement in phenol formaldehyde resin. In order to improve the interfacial properties, the fibres were subjected to different chemical modifications such as mercerisation, acrylonitrile grafting, acrylation, latex coating, permanganate treatment, acetylation, and peroxide treatment. The effect of fibre coating on the interface properties has also been investigated. Morphological and structural changes of the

M. S. Sreekala; M. G. Kumaran; Seena Joseph; Maya Jacob; Sabu Thomas

2000-01-01

203

Space-division multiplexing in optical fibres  

NASA Astrophysics Data System (ADS)

Optical communication technology has been advancing rapidly for several decades, supporting our increasingly information-driven society and economy. Much of this progress has been in finding innovative ways to increase the data-carrying capacity of a single optical fibre. To achieve this, researchers have explored and attempted to optimize multiplexing in time, wavelength, polarization and phase. Commercial systems now utilize all four dimensions to send more information through a single fibre than ever before. The spatial dimension has, however, remained untapped in single fibres, despite it being possible to manufacture fibres supporting hundreds of spatial modes or containing multiple cores, which could be exploited as parallel channels for independent signals.

Richardson, D. J.; Fini, J. M.; Nelson, L. E.

2013-05-01

204

Modelling skeletal muscle fibre orientation arrangement.  

PubMed

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

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

2011-12-01

205

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

PubMed

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

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

2014-02-21

206

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

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

2010-01-01

207

Exposure to asbestos fibres during gasket removal.  

PubMed

In the chemical industry, asbestos gaskets have been used extensively to prevent leakage between solid surfaces. The purpose of this study was to assess the potential personal exposure to asbestos fibres during gasket removal and thus to determine what is reasonably required in terms of protective regime and work method. Two groups were studied: group A, who only removed gaskets if they could be removed easily and without breaking; and group B, who removed gaskets which were left by the first group. For both groups, the gasket was first made wet before removal. The samples were analysed using phase-contrast microscopy and transmission electron microscopy. The average exposure to fibres for group A, averaged over the work period, was 0.04-0.242 fibres ml-1 as determined by phase-contrast microscopy. On further analysis with transmission electron microscopy it was found that only four of the 11 samples contained asbestos in very low concentrations and that most of the fibres, which were identified using phase-contrast microscopy, probably originated from the glass fibre lagging around the pipes. For group B the average fibre concentration, averaged over the work period, as determined by phase-contrast microscopy, ranged between below the detection limit and 0.02 fibres ml-1. The subsequent transmission electron microscopy analysis shows that the exposure to asbestos fibres ranged between below the limit of detection to 0.004 fibres ml-1. This study shows that the exposure to asbestos fibres during gasket removal activities was well within the 8-h average exposure limit of 0.3 fibres ml-1. PMID:8888636

Spence, S K; Rocchi, P S

1996-10-01

208

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

209

[Evaluation of stereometric parameters of optic disc and nerve fiber layer using HRT III. Report 1: reproducibility and intraobserver variability coefficients].  

PubMed

29 patients with initial primary open angle glaucoma were examined using Heidelberg retinal tomograph III (HRT III). In one visit 2 observers took 2 measurements. Intra- and interobserver errors (reproducibility and intraobserver variability coefficient) were calculated for 13 stereometric parameters of optic disc and retinal nerve fiber layer (RNFL). Rim area, cup depth (mean, maximum) and linear cup/disc ratios showed to be minimally variable. Cup area and volume, disc/cup area ratio were found to have greater variability. When performed by different observers (each entering his own contour) reproducibility was 1,4 fold lower compared with intraobserver reproducibility. PMID:21721272

Shpak, A A; Malakhanova, M K; Shormaz, I N

2011-01-01

210

New single-mode fibres with the flat spectral dependence of the chromatic dispersion varying over the fibre length  

SciTech Connect

Single-mode fibres of a new type are manufactured. The fibres are made of high-purity silica and have a flat spectral dependence of chromatic dispersion in the region of 1550 nm varying over the fibre length. The new method and technology are proposed for manufacturing single-mode fibres with dispersion characteristics varying in a specified way along the fibre length. (fibre optics)

Akhmetshin, U G; Bogatyrev, V A; Senatorov, A K; Sysolyatin, A A; Shalygin, M G [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2003-03-31

211

Effect of heating on the optical properties of Yb{sup 3+}-doped fibres and fibre lasers  

SciTech Connect

The effect of heating on the optical properties of Yb{sup 3+}-doped fibres is studied. It is shown that the lasing efficiency of fibre lasers depends on the fibre temperature, the type and extent of the effect being substantially dependent on the laser wavelength. It is proposed to use fibre heating to increase the efficiency of lasers emitting in the 1.15 - 1.2-{mu}m region. (optical fibres and fibre lasers)

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

2004-06-30

212

AFM observation of surface topography of fibre Bragg gratings fabricated in germanium–boron codoped fibres and hydrogen-loaded fibres  

Microsoft Academic Search

This paper reports the measurement of the surface topology of optical fibres containing a fibre Bragg grating (FBG) using an atomic force microscope (AFM). The AFM observation was made on FBGs fabricated via the phase mask technique in germanium–boron codoped optical fibres, in hydrogen-loaded germanium–boron codoped fibres and in standard telecommunications optical fibres. The surface images reveal that a spatial

C. Y. Wei; C. C. Ye; S. W. James; P. E. Irving; R. P. Tatam

2002-01-01

213

CONCENTRATION OF NUCLEI IN CHICKEN MUSCLE FIBRE  

E-print Network

CONCENTRATION OF NUCLEI IN CHICKEN MUSCLE FIBRE IN RELATION TO THE INTENSITY OF GROWTH Helena KNÍ concentration on a constant length segment of muscle fibre released by maceration has been investigated of the muscle tissue are in approximate agreement with these observations. In the course of the investigated

Paris-Sud XI, Université de

214

Development of the fibres of MOONS  

NASA Astrophysics Data System (ADS)

MOONS will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.8 - 1.8 ?m, with a multiplex capability of approximately 1000 fibres. Each triple arm spectrograph will produce spectra for half of the targets simultaneously. The system will have both a medium resolution (R~4000-6000) mode and a high resolution (R~20000) mode. The fibres are used to pick off each sub field of 1.05 arcseconds and are used to transport the light from the instrument focal plane to the two spectrographs. Each fibre has a microlens to focus the beam into the fibre at a relative fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD). This paper presents the overall design of the fibre system and describes the specific developments required to optimise its performance. The design of the fibre input optics, the choice of the fibre connector, and the layout of the slit end are described. The results of preliminary tests to measure the effect of twisting on the FRD performance of prototype fibres are also discussed.

Guinouard, Isabelle; Lee, David; Schnetler, Hermine; Taylor, William; Amans, Jean-Philippe; Montgomery, David; Oliva, Ernesto

2014-07-01

215

Packaging of optical Fibre Bragg Gratings  

Microsoft Academic Search

Fibre Bragg Gratings (FBGs) are all-fibre optical filters with applications in sensing and telecommunication systems. The packaging of FBGs offers many challenges to the manufacturer as stringent tolerances for wavelength stability of the filter over widely varying environmental operating conditions are required for state of the art Dense Wavelength Division Multiplexing (DWDM) telecommunication systems. This paper presents various processes and

D. C. Psaila; H. G. Inglis

2001-01-01

216

Glass fibre paper separator for electrochemical cells  

Microsoft Academic Search

A separator suitable for electrochemical cells of the lead-acid recombinant type comprises a sheet of entangled glass fibres. It has been found that significant improvements in performance can be obtained when 5 to 35% by weight of the fibres have a diameter of less than 1 ..mu..m. It has also been found surprisingly advantageous if the overall solubility of the

F. J. T

1984-01-01

217

Microstructured Polymer Optical Fibres: Progress and Promise  

Microsoft Academic Search

ABSTRACT Microstructured optical fibres ( MOFs) have aroused great interest in recent years because of their unusual optical properties. These include their ability to be effectively single -moded over a very large range of wavelengths, tailorisable dispersion, high or low non-linearity(depending on the hole design) and large core single -mode fibres. We have recently fabricated the first Microstructured Polymer Optical

Maryanne C. J. Large; Martijn A. Van Eijkelenborg; Alexander Argyros; Joseph Zagari; Steven Manos; Nader A. Issa; Ian Bassett; Simon Fleming; Ross C. Mcphedran; C. Martijn De; Nicolae A. p. Nicorovici

2006-01-01

218

Fabrication of microstructured polymer optical fibres  

Microsoft Academic Search

A methodology is presented suitable for the fabrication of a wide range of microstructured polymer optical fibres (mPOFs), a recent development where light guidance is achieved through the incorporation of a pattern of air channels that run the entire length of the fibre. We show that the key to good mPOF fabrication is a secondary draw oven that has tight

Geoff Barton; Martijn A. van Eijkelenborg; Geoffrey Henry; Maryanne C. J. Large; Joseph Zagari

2004-01-01

219

INNOVATION IN MAN-MADE FIBRES: CORPORATE  

E-print Network

on woodpulp) Rayon (viscose), acetate, lyocell (Tencel) Synthetic fibres (based on oil) Polyester, Acrylic 1900-1945 Growth of rayon before and after first world war; invention of nylon by DuPont in 1935 1945/75 Investment in textiles and clothing 1969 Builds carbon fibre plant 1988 Buys PRC (aircraft sealants

Sussex, University of

220

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

221

A model of multicomponent cardiac fibre.  

PubMed

In order to simulate the contraction of a cardiac myofibre, a multicomponent fibre model has been developed. This model is composed of a series of segments which are activated in succession. Each segment is represented by the Hill's three component model of the sarcomere. The contractile element behaviour is described by the Huxley's theory and the time dependence agrees with the activation factor proposed by Julian for skeletal muscle, and modified by Wong for cardiac muscle. The two elastic elements have non-linear exponential characteristics. The isometric contraction of the multicomponent fibre has been simulated by means of a computer program. The results show the tension generated by the fibre, the propagation of the contraction along the fibre and the different contribution of each segment depending on its position inside the fibre. PMID:3597453

Montevecchi, F M; Pietrabissa, R

1987-01-01

222

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

223

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

224

EDITORIAL: Optical Fibre Sensors 18 (OFS-18)  

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

225

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

226

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

227

Frequency dependence of the phase shift in optical-fibre thermal modulators  

NASA Astrophysics Data System (ADS)

The optical phase shift as a function of frequency was determined in the range from DC to >10 kHz for some single-mode optical-fibre phase modulators, formed by depositing a metal layer on the cladding surface by vacuum evaporation. A thermal analysis is presented in which the fibre surface and core temperatures are determined as a function of the frequency of the heating due to an electric current passing through the coating. The phase modulation arises from a combination of the temperature change at the core (predominant at low frequencies) and strains produced by the thermal expansion of the metal coating (predominant at the high frequencies). Applications include phase and birefringence control in optical-fibre interferometers.

Brown, J. B.; Jones, J. D. C.; Rogers, S. J.; Chan, R. K. Y.; Wong, H. H.

1995-10-01

228

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

229

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

230

Alkali treatment of coir fibres for coir-polyester composites  

Microsoft Academic Search

Coir fibres were subjected to alkali treatment with a view to improving the wettability of coir fibres by a commercially available resin such as polyester. Tensile strength of the fibres increases by 15% when the fibres are soaked in 5% aqueous solution of NaOH at 28±1° C for 72 to 76 h after which it shows a gradual decrease. This

S. V. Prasad; C. Pavithran; P. K. Rohatgi

1983-01-01

231

On the mechanisms of abrasive wear of polyamide fibres  

Microsoft Academic Search

The abrasion resistance of fibres is a basic property in the textile industry since the fibres can be damaged during the manufacturing process. To understand the fundamental mechanisms of abrasion of 40?m diameter polyamide fibres, a tribometer using a fibre-cylinder contact configuration immersed in water has been developed. This instrumented device controls tribological parameters such as the sliding speed, the

J. Cayer-Barrioz; D. Mazuyer; P. Kapsa; A. Chateauminois; F. Bouquerel

2003-01-01

232

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

233

SEMICONDUCTOR FIBRE DEVICES FOR NONLINEAR PHOTONICS , N. Healy1  

E-print Network

new functionality to optical fibres. In particular, fibres that offer improved nonlinear performance the abilities of electronic systems. Although conventional silica optical fibres have already been demonstrated on the characterization of these semiconductor core fibres with the aim to developing all-optical nonlinear photonic

Quartly, Graham

234

Liquid nitrogen strengths of coated optical glass fibres  

Microsoft Academic Search

The strengths of plastic-coated glass fibres have been measured at liquid nitrogen temperatures using a bending technique. The method yields data on the strengths of coated optical fibres in the absence of stress corrosion. Pristine strengths corresponding to a breaking strain of 21% have been measured for silica fibre and 12% for sodium borosilicate compound glass fibre, corrected to 50

P. W. France; M. J. Paradine; M. H. Reeve; G. R. Newns

1980-01-01

235

Improving the Radial Dopant Distribution in Silica Optical Fibres  

E-print Network

Improving 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 Fibres; I. INTRODUCTION Rare-earth (RE) doped optical fibres constitute a key component in the production

Paris-Sud XI, Université de

236

Gain-controlled wave chaos in a chaotic optical fibre  

E-print Network

Gain-controlled wave chaos in a chaotic optical fibre C. Michel, S. Tascu, V. Doya, O. Legrand, F of a multimode chaotic optical fibre. More precisely, we introduce Ytterbium in the optical fibre as a gain of a chaotic optical fibre as a device to visualise quantum chaos, we describe the amplification process

Paris-Sud XI, Université de

237

Self-Healing Capability of Fibre Reinforced Cementitious Composites  

Microsoft Academic Search

In order to investigate the self-healing capability of fibre reinforced cementitious composites (FRCC), mechanical properties and surface morphology of crack in FRCC were studied. Three types of FRCC specimens containing (1) polyethylene (PE) fibre, (2) steel cord (SC) fibre, and (3) hybrid fibres composite (both of PE and SC) were prepared. These specimens, in which cracks were introduced by tension

Daisuke Homma; Hirozo Mihashi; Tomoya Nishiwaki

2009-01-01

238

A novel cryogenic fibre maker for continuous extrusion  

Microsoft Academic Search

The results of a cryogenics fibre maker which extrudes fibres continuously are presented. The fibre maker is based on a simple concept of differential temperature. Two reservoirs are connected in cascade and are kept at different temperatures. The first reservoir is connected to an external gas line supply (the gas that will made the fibre) and is used to liquefy

R. Aliaga-Rossel; J. Bayley

1997-01-01

239

Deterministic and Probabilistic Tractography Based on Complex Fibre Orientation Distributions  

Microsoft Academic Search

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

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

2009-01-01

240

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

241

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

PubMed

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

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

2014-01-16

242

Optical fibre biosensors using enzymatic transducers to monitor glucose  

NASA Astrophysics Data System (ADS)

The construction and performance of a novel enzyme based optical sensor for in situ continuous monitoring of glucose in biotechnological production processes is presented. Sensitive optical coatings are formed from inorganic-organic hybrid polymers (ORMOCER®sORMOCER®: Trademark of Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. in Germany.) combined with a flurophore (ruthenium complex) and an enzyme, and applied to lenses, declad polymer optical fibre (POF) and polymer clad silica fibre (PCS). The enzyme, glucose oxidase, catalyzes oxidization of glucose to gluconic acid by depleting oxygen. Oxygen consumption is determined by measuring the fluorescence lifetime of metal organic ruthenium complexes which are quenched by oxygen. The coatings developed were designed to adhere to glass and polymer surfaces, to be compatible with enzymes and ruthenium complexes, and were demonstrated both as double- and single-layer structures. The sensor response to gaseous oxygen, dissolved oxygen and dissolved glucose was measured via fluorescence lifetime changes. A best detection limit of 0.5% (vol) has been determined for gaseous O2 with selected ORMOCER® sensing layers. Glucose concentrations were measured to a detection limit of 0.1 mmol L-1 over a range up to 30 mmol L-1. The sensor was usable for 30 days in a bioreactor. The opto-electronic instrumentation and performance in laboratory bioreactors and in an industrial reactor are evaluated.

Scully, P. J.; Betancor, L.; Bolyo, J.; Dzyadevych, S.; Guisan, J. M.; Fernández-Lafuente, R.; Jaffrezic-Renault, N.; Kuncová, G.; Matejec, V.; O'Kennedy, B.; Podrazky, O.; Rose, K.; Sasek, L.; Young, J. S.

2007-10-01

243

SMALLER DIAMETER OPTICAL FIBRE SENSOR FOR AUTOMATED EMBEDDING IN COMPOSITE LAMINATES  

E-print Network

diameter fibre Bragg grating (FBG) sensors in composite materials. When an optical fibre is embedded. Draw Tower fibre Bragg gratings (DTG®s) are inscribed in this fibre which show identical strain optic in this paper KEYWORDS : fibre Bragg gratings, automated fibre placement, embedded sensors, fibre reinforced

Boyer, Edmond

244

Effect of the addition of different fibres on wheat dough performance and bread quality  

Microsoft Academic Search

A good correlation has become evident between fibre consumption and the reduction of coronary heart-related diseases and diabetes incidence. However, fibre intake is commonly lower than recommended. In consequence, the development of foods with high fibre content should be desirable. The potential use of various commercial fibres (carob fibre, inulin and pea fibre), as fibre-enriching agents in breadmaking, is reported.

Jinshui Wang; Cristina M Rosell; Carmen Benedito de Barber

2002-01-01

245

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

246

An infrared fibre evanescent wave spectroscopic (FEWS) sensor using purified GeTeSe chalcogenide fibres  

NASA Astrophysics Data System (ADS)

In this study, we report the fabrication and engineering of an infrared fibre evanescent wave spectroscopic (FEWS) sensor using GeTeSe chalcogenide fibres, which manifests high temperature durability (glass transformation temperature at 260°C) and extended infrared transmission from 1.5 to 18 ?m. We also report the methodologies adopted for the fabrication of fibres, including the purification of starting chemicals for high spectral purity, glass melting, quenching and annealing, fabrication of fibre performs. The designed FEWS sensor consists of a 40 cm unstructured GeTeSe fibre coupled with a Fourier transform infrared (FTIR) spectrometer and a Mercury-Cadmium-Tellurium (MCT) infrared detector, and the active sensing length of the fibre is 3 cm. In this paper, we demonstrate the sensing results with various analytes and investigate the sensitivity of this sensor.

Jiang, Xin; Jha, Animesh

2009-10-01

247

Efficient Fibre Amplifiers Based on a Highly Er3+/Yb3+ Codoped Phosphate Glass-Fibre  

NASA Astrophysics Data System (ADS)

Highly Er3+/Yb3+-codoped single-mode phosphate glass fibre is fabricated by the rod-in-tube technique. The performances of high-concentration Er3+/Yb3+-codoped phosphate glass fibre amplifiers are investigated and discussed. An efficient optical fibre amplifier with a gain of 12.6 dB based on a 3.0 cm long Er3+/Yb3+-codoped phosphate glass fibre is demonstrated under a dual-pump configuration with two 976 nm fibre-pigtail laser diodes, which make it attractive for compact Er3+ -doped fibre amplifiers. The obtained noise figures of signal wavelength from 1525 to 1565 nm are less than 6.0 dB. Gain saturation behaviour at 1535 nm is also investigated, and the obtained saturation output power is larger than 10 dBm.

Xu, Shan-Hui; Yang, Zhong-Min; Feng, Zhou-Ming; Zhang, Qin-Yuan; Jiang, Zhong-Hong; Xu, Wen-Cheng

2009-04-01

248

Fibre laser torsion sensor system using an excessively tilted fibre grating and low-cost time domain demodulation  

E-print Network

, a normal structure fibre Bragg grating (FBG) and a ETFG with fringe structure tiled at 79° (79°-ETFG) were . Optical fibre grating based torsion sensors are intrinsically small and easy to implement. A corrugatedFibre laser torsion sensor system using an excessively tilted fibre grating and low-cost time

Neirotti, Juan Pablo

249

Integration and assessment of fibre Bragg grating sensors in an all-fibre reinforced polymer composite road bridge  

Microsoft Academic Search

This paper reports on the integration and assessment of 40 ruggedly protected fibre Bragg grating sensors (FBGs) in an all-glass fibre reinforced polymer composite road bridge. This bridge is reported to be Europe's first all-fibre reinforced composite bridge. A unique feature of this bridge was that it was constructed from pultruded glass fibre composite sections, which were bonded on site.

Y. M. Gebremichael; W. Li; W. J. O. Boyle; B. T. Meggitt; K. T. V. Grattan; B. McKinley; G. F. Fernando; G. Kister; D. Winter; L. Canning; S. Luke

2005-01-01

250

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

E-print Network

and a diamond fibre-reinforced titanium alloy composite. 2. Experimental procedure Fibres have been made with titanium and embedded in Ti-6AI~4V alloy at 900 ~ by hot vac- uum pressing under superplastic conditions with tungsten wire or SiC fibre cores are attractive for reinforcing metals and ceramics. The fibres have

Bristol, University of

1996-01-01

251

Ocean Applications Of Fibre Optic Sensors  

NASA Astrophysics Data System (ADS)

The unique features of fibre optic sensors have sparked wide spread interest in applications that provide new sensor capabilities or offer cost or performance benefits over existing sensors. Fibre optic sensors are small, lightweight, electrically passive and immune to electromagnetic interference, making them attractive for industrial, marine, military and medical applications. The oceans provide a unique arena where many of the attributes of optical sensing can be and are being applied today. However, the oceans also present many challenges in bringing fibre optic sensing to an especially hostile environment.

Paton, Barry E.

1986-11-01

252

A device to characterize optical fibres  

E-print Network

ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave Length Shifting (WLS) fibres (corresponding to a total length of 1,120 Km) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres.

F. Bosi; S. Burdin; V. Cavasinni; D. Costanzo; T. Del Prete; V. Flaminio; E. Mazzoni; C. Roda; G. Usai; A. Vasiljev

2001-09-03

253

Fibre-reinforced composites in restorative dentistry.  

PubMed

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

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

2003-01-01

254

Recent progress in microstructured polymer optical fibre fabrication and characterisation  

Microsoft Academic Search

Recent progress in microstructured polymer optical fibre fabrication and characterisation will be presented. A wide range of different optical functionalities can now be obtained by modifications of the microstructure, as is demonstrated by the fibres presented here. Microstructured fibres that are single-mode, highly birefringent or show twin-core coupling are described, in addition to graded-index microstructured fibres and hollow core fibres,

Martijn A. van Eijkelenborg; Alexander Argyros; Geoff Barton; Ian M. Bassett; Matthew Fellew; Geoffrey Henry; Nader A. Issa; Maryanne C. J. Large; Steven Manos; Whayne Padden; Leon Poladian; Joseph Zagari

2003-01-01

255

OPTICAL FIBRES: Peculiarities of the photosensitivity of low-loss phosphosilica fibres  

Microsoft Academic Search

The peculiarities of the refractive-index change in low-loss heavily P2O5-doped silica fibres fabricated by the MCVD method caused by irradiation with UV light are studied. The pre-exposure effect is found in these fibres. The mechanisms of the refractive-index change in phosphosilica and germanosilica fibres are considered and compared in the presence of this effect.

Yu V. Larionov; A. A. Rybaltovsky; S. L. Semenov; M. M. Bubnov; Evgenii M. Dianov

2002-01-01

256

Low Cost Carbon Fibre for Automotive Applications Part 1: Low Cost Carbon Fibre Development  

SciTech Connect

In pursuit of the goal to produce ultra-lightweight fuel efficient vehicles, there has been great excitement during the last few years about the potential for using carbon fibre reinforced composites in high volume applications. Currently, the greatest hurdle that inhibits wider implementation of carbon fibre composites in transportation is the high cost of carbon fibre when compared to other candidate materials. However, significant research is being conducted to develop lower cost, high volume technologies for producing carbon fibre. This chapter will highlight ongoing research in this area.

Warren, Charles David [ORNL; Das, Sujit [ORNL; Wheatley, Dr. Alan [University of Sunderland

2014-01-01

257

Fibre Bragg grating sensor for respiratory monitoring  

Microsoft Academic Search

A temperature sensor based on fibre Bragg gratings has been used to monitor human respiration. We discuss the thermodynamic properties of the sensor and present the general performance characteristics of the system.

Y. Liang; A. P. Mazzolini; P. R. Stoddart

2006-01-01

258

Bott periodicity for fibred cusp operators  

E-print Network

In the framework of fibred cusp operators on a manifold X associated to a boundary fibration ... , the homotopy groups of the space ... of invertible smoothing perturbations of the identity are computed in terms of the ...

Rochon, Frédéric, 1978-

2005-01-01

259

Fibre to the home – infrastructure deployment issues  

Microsoft Academic Search

To date the use of optical fibre in the access network has typically only proved cost effective for supplying the high-bandwidthdemands of large corporate companies. For new and established network operators, however, the increasing demand forbandwidth to deliver bearer, interactive and bundled services to business and residential customers is requiring them to seriouslyconsider the high volume roll-out of optical-fibre-based systems.

A. J. Mayhew; S. J. Page; A. M. Walker; S. I. Fisher

2002-01-01

260

Synaptic plasticity at hippocampal mossy fibre synapses  

Microsoft Academic Search

The dentate gyrus provides the main input to the hippocampus. Information reaches the CA3 region through mossy fibre synapses made by dentate granule cell axons. Synaptic plasticity at the mossy fibre–pyramidal cell synapse is unusual for several reasons, including low basal release probability, pronounced frequency facilitation and a lack of N-methyl-D-aspartate receptor involvement in long-term potentiation. In the past few

Roger A. Nicoll; Dietmar Schmitz

2005-01-01

261

Nonlinear switching in fibre Bragg gratings.  

PubMed

We report on our recent experiments on nonlinear switching in fibre Bragg gratings. Using an all-fibre source we show an increase in transmission of a FBG from 4% to 40% at high powers. This switching is associated with the formation of gap solitons inside the grating. We also demonstrate an all-optical AND gate using polarization coupled gap solitons and the optical pushbroom. PMID:19384393

Broderick, N; Taverner, D; Richardson, D

1998-11-23

262

Fibre Bragg grating for flood embankment monitoring  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

263

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

264

Thermally induced structural changes in Nomex fibres  

Microsoft Academic Search

Thermally aged Nomex fibres manifest several residual effects viz. reduction in X-ray crystallinity, weight loss and deterioration\\u000a in tensile characteristics. Surface damages in the form of longitudinal openings, holes, material deposits etc have also been\\u000a observed. Based on the data from thermally exposed fibres, the time needed for states of zero tensile strength and modulus\\u000a have been predicted.

Anjana Jain; Kalyani Vijayan

2002-01-01

265

Investigation of low-velocity impact damage in fibre-metal-laminates  

NASA Astrophysics Data System (ADS)

Fibre-metal-laminates (FMLs) represent a significant evolution in airframe material technology. This new family of materials combines low density, high strength and excellent damage tolerance through the use of metal layers strengthened with fibre-reinforced polymer layers. When subjected to low-velocity impact these laminates like traditional composites, develop internal delamination damage, matrix cracks and limited fibre fractures. Also, as in traditional composites, this damage is hidden within the laminate. A method for predicting the amount of internal damage would reduce the experimental testing requirements for the certification of new laminates. This thesis describes the development of a modelling methodology that makes use of a new material subroutine based on continuum damage mechanics in the explicit finite-element code LS-DYNA. This subroutine was verified using the experimental data from low-velocity impact tests of various types of GLARE (GLAss REinforced) aluminum laminates, a common type of commercially available fibre-metal-laminate. Static characterization tests were also conducted on GLARE coupons to provide basic property data for the development of the model. These included static tensile tests and double cantilever beam delamination tests. The modelling methodology was used to improve simulations of low-velocity impact on GLARE laminates. The simulations demonstrated that intralaminar damage has a greater effect on the impact response of the panels than interlaminar damage. Parts of this thesis were components of a multi-year collaborative FML Durability Project between Carleton University, Bombardier Aerospace and the National Research Council Canada.

Laliberte, Jeremy F.

2002-04-01

266

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

267

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

PubMed Central

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

268

Evaluation of Retinal Nerve Fiber Layer Thickness in Acromegalic Patients Using Spectral-Domain Optical Coherence Tomography.  

PubMed

ABSTRACT Purpose: To evaluate retinal nerve fiber layer (RNFL) thickness in acromegalic patients. Methods: A study group of 29 patients with acromegaly and a control group of 38 age-matched healthy individuals were enrolled in a cross-sectional study. The study group was further divided by tumor size into two subgroups, a macroadenoma group and a microadenoma group. Serum growth hormone (GH) and insulin-like growth factor-1 (IGF-I) levels were detected at the time of ophthalmological examination in the study group. In both the study and control group, the RNFL thickness in the four quadrants was measured by optical coherence tomography. The relationship between GH and IGF-I levels and RNLF thickness was also evaluated. Results: The difference in mean RNLF thickness in all quadrants between the study and control groups was not statistically significant. In acromegalic patients with macroadenoma, the mean RNLF thickness of the inferior quadrant decreased significantly compared to both patients with microadenoma and healthy individuals (p?=?0,032 and p?=?0,046). GH and IGF-1 levels were not significantly correlated with the RNLF thickness in the study group. Conclusions: Excessive GH and IGF-1 levels do not affect the optic nerve or RNLF thickness, whereas the RNLF becomes thinner in the inferior quadrant in acromegalic patients with macroadenoma as a result of the chiasmal compression. PMID:25380485

Duru, Necati; Ersoy, Reyhan; Altinkaynak, Hasan; Duru, Zeynep; Ca?il, Nurullah; Cakir, Bekir

2014-11-01

269

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

270

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

271

The Design and Performance of a Scintillating-Fibre Tracker for the Cosmic-ray Muon Tomography of Legacy Nuclear Waste Containers  

E-print Network

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 2mm-pitch plastic scintillating fibres. Identification of the two struck fibres per module allows the reconstruction of 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 fibre...

Clarkson, Anthony; Hoek, Matthias; Ireland, David G; Johnstone, Russell; Kaiser, Ralf; Keri, Tibor; Lumsden, Scott; Mahon, David F; McKinnon, Bryan; Murray, Morgan; Nutbeam-Tuffs, Sian; Shearer, Craig; Staines, Cassie; Yang, Guangliang; Zimmerman, Colin

2013-01-01

272

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

273

Mechanical properties of short flax fibre bundle\\/polypropylene composites: Influence of matrix\\/fibre modification, fibre content, water uptake and recycling  

Microsoft Academic Search

The aim of this work was to compare the effect of modification way of short flax fibre bundle\\/polypropylene (PP) composites on mechanical properties. Modification was carried out on fibre surface and also modifying PP matrix using several amounts of maleic anhydride-polypropylene copolymer (MAPP) as compatibilizer. The optimum doses of two different MAPP compatibilizers have been obtained. The effect of fibre

A. Arbelaiz; B. Fernández; J. A. Ramos; A. Retegi; R. Llano-Ponte; I. Mondragon

2005-01-01

274

Corneal confocal microscopy: A novel means to detect nerve fibre damage in idiopathic small fibre neuropathy  

PubMed Central

Patients with idiopathic small fibre neuropathy (ISFN) have been shown to have significant intraepidermal nerve fibre loss and an increased prevalence of impaired glucose tolerance (IGT). It has been suggested that the dysglycemia of IGT and additional metabolic risk factors may contribute to small nerve fibre damage in these patients. 25 patients with ISFN and 12 aged-matched control subjects underwent a detailed evaluation of neuropathic symptoms, neurological deficits (Neuropathy deficit score (NDS); Nerve Conduction Studies (NCS); Quantitative Sensory Testing (QST) and Corneal Confocal Microscopy (CCM) to quantify small nerve fibre pathology. 8 (32%) of patients had IGT. Whilst all patients with ISFN had significant neuropathic symptoms, NDS, NCS and QST except for warm thresholds were normal. Corneal sensitivity was reduced and CCM demonstrated a significant reduction in corneal nerve fibre density (NFD) (P<0.0001), nerve branch density (NBD) (P<0.0001), nerve fibre length (NFL) (P<0.0001) and an increase in nerve fibre tortuosity (NFT) (P<0.0001). However these parameters did not differ between ISFN patients with and without IGT, nor did they correlate with BMI, lipids and blood pressure. Corneal confocal microscopy provides a sensitive non-invasive means to detect small nerve fibre damage in patients with ISFN and metabolic abnormalities do not relate to nerve damage. PMID:19748505

Tavakoli, Mitra; Marshall, Andrew; Pitceathly, Robert; Gow, David; Roberts, Mark E; Malik, Rayaz A

2009-01-01

275

Characterisation of long term behaviour of polyester fibres and fibre assemblies for offshore mooring lines  

E-print Network

Characterisation of long term behaviour of polyester fibres and fibre assemblies for offshore have to be replaced. Polyester lines are being progressively introduced as a lighter alternative offset of the platform are some of the requirements. Polyester presents a fair compromise between

Burgoyne, Chris

276

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

277

Temperature and strain discrimination using a single fibre Bragg grating written in a tapered optical fibre  

Microsoft Academic Search

A sensing head configuration and the necessary interrogation parameters to simultaneously measure strain and temperature using a single FBG are presented and demonstrated. By writing the FBG in a linearly etched fibre, we were able to use the information encoded in the peak wavelength and in the spectral width of the fibre Bragg grating. The spectral width of the grating

H. F. Lima; P. F. Antunes; R. N. Nogueira; J. L. Lemos Pinto

2009-01-01

278

Dichroism measurements in forensic fibre examination. Part 2 — Dyed polyamide, wool and silk fibres  

Microsoft Academic Search

A number of dyed polyamide, wool and silk samples were examined with plane polarized light on their dichroic behavior by optical light microscopy (OLM) and microspectrophotometry with plane polarized light (MSP-PPL). It was found that most of these acid dyed peptidic fibres possess dichroism, but these are weaker than the effects previously described for polyester fibres. The small effects may

K. De Wael; T. Vanden Driessche

279

Influence of development and rearing temperature on the distribution, ultrastructure and myosin sub-unit composition of myotomal muscle-fibre types in the plaice Pleuronectes platessa  

Microsoft Academic Search

Eggs of the plaice Pleuronectes platessa L. were incubated at temperatures of 5, 8, 10, 12 and 15°C in March 1990, 1991 and 1992. The myotomes of yolk-sac larvae contain a single superficial layer of small-diameter muscle fibres which stain intensely for succinic dehydrogenase activity, surrounding 390 to 500 weakly staining inner-muscle fibres of larger diameter. Larvae reared at 15°C

S. Brooks; I. A. Johnston

1993-01-01

280

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

SciTech Connect

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

Bufetov, Igor' A; Bubnov, M M; Mel'kumov, Mikhail A; Dudin, V V; Shubin, Aleksei V; Semenov, S L; Kravtsov, K S; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, A N; Yashkov, M V [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2005-04-30

281

Spun microstructured optical fibres for Faraday effect current sensors  

SciTech Connect

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

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

2009-11-30

282

Radiation-resistant erbium-doped silica fibre  

SciTech Connect

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

Zotov, K V; Likhachev, M E; Tomashuk, A L; Bubnov, M M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Yashkov, M V; Gur'yanov, A N [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2007-10-31

283

Photosensitivity of optical fibres doped with different impurities  

SciTech Connect

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

Larionov, Yu V; Rybaltovsky, A A; Semenov, S L [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Vartapetov, Sergei K; Kurzanov, M A; Obidin, Aleksei Z [Physics Instrumentation Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)

2004-02-28

284

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

SciTech Connect

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

Zagorul'ko, K A; Kryukov, P G; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Dragomir, A; Nikogosyan, D N [Department of Physics, National University of Ireland, University College Cork, Cork (Ireland)

2003-08-31

285

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

286

Modelling non-symmetric collagen fibre dispersion in arterial walls.  

PubMed

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

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

2015-05-01

287

Internodal conduction in undissected demyelinated nerve fibres  

PubMed Central

1. A new method is described for recording external longitudinal currents from single undissected nerve fibres in rat ventral roots. The method permits identification of the sites of fifteen or more successive nodes of Ranvier in a given single fibre and the measurement of internodal conduction times between them. 2. Average internodal conduction time for normal ventral root fibres of internodal length between 0·75 and 1·45 mm is 19·7 ± 4·6 (S.D.) ?sec at 37° C. Internodal conduction time appeared to show a minimum for fibres of internodal length 1·0 mm. 3. Ventral roots were demyelinated by focal application of diphtheria toxin. Although conduction is markedly slowed in demyelinated fibres, sites of inward membrane current remain spatially separated indicating that conduction remains saltatory to the point of conduction block rather than becoming continuous as in unmyelinated fibres. 4. Slowing of conduction appears to be due to changes in the passive electrical properties of the internodal myelin. Evidence is presented suggesting that there is an increase in internodal capacitance and a decrease in internodal transverse resistance at internodes of demyelinated fibres; such changes would have the effect of delaying excitation at the nodes. The changes in passive electrical properties, which appear to be primarily in the vicinity of the nodes, would be consistent with the pathological changes observed in demyelinated fibres. 5. Internodal conduction times in demyelinated fibres have ranged from normal (26 ?sec at 30° C) to more than 600 ?sec. There is a great variation in internodal conduction time at successive internodes of a given single fibre; this presumably reflects the varying severity of demyelination of successive internodes. 6. As in normal fibres, nodes of demyelinated fibres generate less current when excited by the second of two closely spaced impulses. This results in an increased internodal conduction time for the second impulse and, at a critically short interstimulus interval, conduction block of the second impulse. 7. The increased refractory period of transmission of internodes with increased internodal conduction times is a consequence of the decreased ability of such internodes to sustain propagation in the face of small decreases in nodal current. 8. During tetanic stimulation, increases in internodal conduction time are associated with corresponding decreases in nodal current generated by the node proximal to the internode in question. 9. It is suggested that changes in the magnitude of the nodal current during repetitive activity are due to changes in transmembrane concentration gradients of sodium, the increased internodal conduction time and eventual conduction block during tetanic stimulation being caused by intracellular sodium accumulation. 10. Intracellular sodium accumulation is also offered as the explanation for the post-tetanic depression seen in demyelinated fibres. ImagesPlate 1 PMID:4647244

Rasminsky, M.; Sears, T. A.

1972-01-01

288

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

289

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

290

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

Microsoft Academic Search

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

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

1992-01-01

291

Co-axial dual-core resonant leaky fibre for optical amplifiers Ajeet Kumar1  

E-print Network

-mode fibre, large-mode-area-fibre, leakage loss, confinement loss, fibre laser, optical communication, dense-wavelength-division-multiplexing lasers and for high data rate dense wavelength division multiplexed optical fibre communication system to step index fibre [1]. With the recent advances in high power fibre lasers and need to scale core size

Boyer, Edmond

292

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

PubMed Central

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

2012-01-01

293

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

294

Crystalline silicon core fibres from aluminium core preforms.  

PubMed

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

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

2015-01-01

295

oftheothermemberofthepairwassuitablefor long-distance transmission in optical fibre.  

E-print Network

oftheothermemberofthepairwassuitablefor long-distance transmission in optical fibre- rentlyinferiortothosethatcanbeachievedina small spool of optical fibre. And whereas good efficiency, storage time and bandwidth have all certain practical advantages. For example, Saglamyurek and colleagues2 formed the memory in an optical

Millar, Andrew J.

296

Crystalline silicon core fibres from aluminium core preforms  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

297

On non-Hookean behaviour of carbon fibres in bending  

Microsoft Academic Search

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

H. M. Hawthorne

1993-01-01

298

A 1.65-m fibre Raman amplifier  

Microsoft Academic Search

A fibre Raman amplifier operating at a wavelength of 1.65-m is fabricated. A two-stage phosphosilicate fibre Raman converter of 1.53-m radiation for pumping the Raman amplifier is designed and tested. The amplifier pumped by a phosphosilicate fibre Raman converter can operate with a maximum of the gain band ranging from 1.6 to 1.7 m. A fibre with a core of

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

2002-01-01

299

A 1.65-?m fibre Raman amplifier  

Microsoft Academic Search

A fibre Raman amplifier operating at a wavelength of 1.65-?m is fabricated. A two-stage phosphosilicate fibre Raman converter of 1.53-?m radiation for pumping the Raman amplifier is designed and tested. The amplifier pumped by a phosphosilicate fibre Raman converter can operate with a maximum of the gain band ranging from 1.6 to 1.7 ?m. A fibre with a core of

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

2002-01-01

300

REVIEW ARTICLE: In-fibre Bragg grating sensors  

Microsoft Academic Search

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

Yun-Jiang Rao

1997-01-01

301

Measurement of dispersion in optical fibres with a microstructure cladding  

SciTech Connect

Based on the interferometric technique, a setup is built for measuring the spectral dependence of chromatic dispersion in fibres with a microstructure cladding. The setup provides measurements in a broad spectral range from 670 to 1550 nm taking birefringence in the fibre into account. The results of measurements of dispersion in a standard fibre with this setup and a commercial device are in good agreement. (optical fibres)

Levchenko, A E; Kurkov, Andrei S; Semenov, S L [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2005-09-30

302

Formation of shock waves in inhomogeneous active fibres  

SciTech Connect

The formation dynamics of the shock wave of a pulse envelope is considered in fibres with the gain, dispersion, and nonlinearity distributed over the fibre length. It is shown that the wave-front steepness for inhomogeneous optical fibres can be strongly increased even when the local group-velocity dispersion substantially differs from zero if its average value (over the length of the shock-wave formation) is close to zero. (fibre optics)

Zolotovskii, Igor' O; Sementsov, Dmitrii I [Ul'yanovsk State University, Ul'yanovsk (Russian Federation)

2005-05-31

303

Peculiarities of the photosensitivity of low-loss phosphosilica fibres  

SciTech Connect

The peculiarities of the refractive-index change in low-loss heavily P{sub 2}O{sub 5}-doped silica fibres fabricated by the MCVD method caused by irradiation with UV light are studied. The pre-exposure effect is found in these fibres. The mechanisms of the refractive-index change in phosphosilica and germanosilica fibres are considered and compared in the presence of this effect. (optical fibres)

Larionov, Yu V; Rybaltovsky, A A; Semenov, S L; Bubnov, M M; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2002-02-28

304

Peculiarities of the photosensitivity of low-loss phosphosilica fibres  

Microsoft Academic Search

The peculiarities of the refractive-index change in low-loss heavily PO-doped silica fibres fabricated by the MCVD method caused by irradiation with UV light are studied. The pre-exposure effect is found in these fibres. The mechanisms of the refractive-index change in phosphosilica and germanosilica fibres are considered and compared in the presence of this effect. (optical fibres)

Yu V Larionov; A A Rybaltovsky; S L Semenov; M M Bubnov; Evgenii M Dianov

2002-01-01

305

Cellulosic\\/synthetic fibre reinforced polymer hybrid composites: A review  

Microsoft Academic Search

Present review deals with the recent development of cellulosic\\/cellulosic and cellulosic\\/synthetic fibres based reinforced hybrid composites. Hybrid composites made up of two different cellulosic fibres are less common compare to cellulosic\\/synthetic fibre, but these are also potentially useful materials with respect to environmental concerns. Hybrid composites fabrication by cellulosic fibres is economical and provide another dimension to the versatility of

M. Jawaid; H. P. S. Abdul Khalil

2011-01-01

306

Radiotherapy dosimetry based on plastic optical fibre sensors  

NASA Astrophysics Data System (ADS)

The use of a PMMA based plastic optical fibre in radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces under ionising radiation. The emitted signal penetrates the fibre and propagates along the fibre where it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.59% and the response is independent of dose rate.

O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Lewis, E.

2013-05-01

307

Fluorinated carbon fibres and their suitability as reinforcement for fluoropolymers  

Microsoft Academic Search

The interaction between direct fluorinated carbon fibres and various fluoropolymers (ethylene-chlorotrifluoroethylene, poly vinylidene fluoride, fluorinated ethylene propylene copolymer and tetrafluoroethylene-perfluoro alkoxy vinyl ether copolymer) was studied by means of direct wetting measurements between fibres and the polymer melts and single fibre pull-out tests. The results of both techniques allow the adhesion behaviour between the fibres and the matrices to be

Kingsley K. C. Ho; Gerhard Kalinka; Michael Q. Tran; Natalya V. Polyakova; Alexander Bismarck

2007-01-01

308

Chemical fibres — An important factor in economic development  

Microsoft Academic Search

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

E. M. Aizenshtein

1998-01-01

309

Nonlinear optics of fibre event horizons  

E-print Network

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.

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

2014-01-01

310

Nanostructured fibre tip for trapping of nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

311

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, Goëry; Murdoch, Stuart G

2014-01-01

312

Dichroism measurements in forensic fibre examination. Part 2 - dyed polyamide, wool and silk fibres.  

PubMed

A number of dyed polyamide, wool and silk samples were examined with plane polarized light on their dichroic behavior by optical light microscopy (OLM) and microspectrophotometry with plane polarized light (MSP-PPL). It was found that most of these acid dyed peptidic fibres possess dichroism, but these are weaker than the effects previously described for polyester fibres. The small effects may be not observed, especially for wool, but these can be measured using MSP-PPL. In the three peptidic fibre classes, for the first time, a so called "inverse dichroism" is observed which appears in the absorption spectra as a hyperchromic effect. PMID:22137049

De Wael, K; Vanden Driessche, T

2011-12-01

313

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

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

314

Skeletal muscle fibre type transformation following spinal cord injury  

Microsoft Academic Search

Following spinal cord injury (SCI), upper motor neuron paralysed muscles lose the normal type I (slow) and II (fast) fibre mosaic pattern and become predominantly composed of type II (fast glycolytic) fibres. The majority of the research demonstrating this fibre type shift was based on pH sensitive myofibrillar ATPase staining techniques on muscle from longstanding paraplegics and quadriplegics. The purpose

R Burnham; T Martin; R Stein; G Bell; I MacLean; R Steadward

1997-01-01

315

Temporal stability of cladding pumped Yb-doped fibre lasers  

Microsoft Academic Search

Summary form only given. Over the last several years cladding pumped fibre lasers have become a basic tool in research labs, replacing conventional solid-state lasers. A well-designed fibre laser offers excellent thermal properties, reliability, simplicity and compactness. Output power from fibre lasers can reach a 100 W level. Cladding pumped lasers and amplifiers find applications not only in telecommunications as

M. Hodzynski; A. B. Grudinin; J. Nilsson

2001-01-01

316

Enhanced sensitivity fibre Bragg grating (FBG) load sensor  

Microsoft Academic Search

The characterization of a load sensor based on the transverse loading of a subsection of a fibre Bragg grating (FBG) embedded within a cube of epoxy resin is presented. When the epoxy resin cube is loaded transverse to the axis of the fibre, its deformation transduces the load to a strain along the axis of the optical fibre, which changes

Ricardo Correia; Edmon Chehura; Jin Li; Stephen W. James; Ralph P. Tatam

2010-01-01

317

Fibre optic humidity sensor designed for highly alkaline environments  

NASA Astrophysics Data System (ADS)

This paper presents the design of a sensor packaging for a Fibre Bragg Grating (FBG) based fibre optic humidity sensor. The evaluation of the developed fibre optic sensor was performed under experimental conditions and verified its capability to withstand highly alkaline environments. Therefore, the sensor can be applied to monitor the concrete humidity level and thus to indicate the maintenance of concrete structures.

Bremer, K.; Wollweber, M.; Guenther, S.; Werner, G.; Sun, T.; Grattan, K. T. V.; Roth, B.

2014-05-01

318

Optic fibre as a transducer of tendomuscular forces  

Microsoft Academic Search

Direct in vivo tendon force measurements open up new possibilities for understanding of muscletendon loads during natural locomotion. The present report presents a new optic fibre method for such applications. The method is based on light intensity modulation by mechanical modification of the geometric properties of the optic fibre. A special optic fibre with a plastic covering buffer and with

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

1996-01-01

319

Applications for Fibre Optics In Radio Roshene McCool  

E-print Network

Applications for Fibre Optics In Radio Astronomy Roshene McCool , Dr. Ralph Spencer , Dr. Bryan, Jodrell Bank Observatory, Abstract This paper describes how fibre optic communications play an important and shipped from the observation site. Data transfer by fibre optics offers several advantages over existing

Haddadi, Hamed

320

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 propagationMICROSTRUCTURED AIR-SILICA FIBRES: RECENT DEVELOPMENTS IN MODELLING, MANUFACTURING AND EXPERIMENT properties of MOFs are studied in detail. Characteristics measured on fibres manufactured in our laboratory

Boyer, Edmond

321

Numerical Computation of Band Gaps in Photonic Crystal Fibres  

E-print Network

that ordinary optical fibres do not possess, and efforts have been made to numerically model these propertiesNumerical Computation of Band Gaps in Photonic Crystal Fibres submitted by Richard Norton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Richard Norton #12;#12;SUMMARY Photonic crystal fibres are capable of special light guiding properties

Wirosoetisno, Djoko

322

Computation of Normal Logic Programs by Fibring Neural Networks  

E-print Network

Computation of Normal Logic Programs by Fibring Neural Networks Vladimir Komendantsky1 and Anthony of the integration of fibring neural net- works (a generalization of conventional neural networks) into model by fibring neural networks of semantic immediate consequence operators TP and TP , where TP denotes

Seda, Anthony Karel

323

UV laser cleaving of air–polymer structured fibre  

Microsoft Academic Search

Laser ablation of air–polymer structured fibre with 193 nm light from an ArF laser is demonstrated. The technique is suitable for cleaving these fibres. The thermal diffusion time across a 200?m diameter fibre is determined to be ?500ms from experiment.

J. Canning; E. Buckley; N. Groothoff; B. Luther-Davies; J. Zagari

2002-01-01

324

Spatial coherence properties of light from optical fibres  

Microsoft Academic Search

The mutual intensity of the optical field in the Fraunhofer diffraction region produced from the end of an optical fibre under illumination of a coherent beam, is theoretically analysed by using an optical fibre-end source model. In this source model, the optical field at the end of the fibre is expressed as an aggregation of independent plane waves with random

H. Yoshimura; T. Asakura; N. Takai

1992-01-01

325

Nanometre diameter fibres of polymer, produced by electrospinning  

Microsoft Academic Search

Electrospinning uses electrical forces to produce polymer fibres with nanometre-scale diameters. Electrospinning occurs when the electrical forces at the surface of a polymer solution or melt overcome the surface tension and cause an electrically charged jet to be ejected. When the jet dries or solidifies, an electrically charged fibre remains. This charged fibre can be directed or accelerated by electrical

Darrell H. Reneker; Iksoo Chun

1996-01-01

326

Optical properties of fibres with aluminophosphosilicate glass cores  

Microsoft Academic Search

The optical properties of fibres with aluminophosphosilicate (APS) glass cores have been studied at AlO and PO 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

M M Bubnov; K V Zotov; L D Iskhakova; S V Lavrishchev; M E Likhachev; A A Rybaltovsky; Evgenii M Dianov; Aleksei N Guryanov; D S Lipatov; V F Khopin; M V Yashkov

2009-01-01

327

SINGLE-BOLTED CONNECTIONS FOR ORTHOTROPIC FIBRE-REINFORCED  

E-print Network

SINGLE-BOLTED CONNECTIONS FOR ORTHOTROPIC FIBRE-REINFORCED COMPOSITE STRUCTURAL MEMBERS BY CHARLES. ~. '-.-:-. #12;ABSTRACT Although the high strength-to-weight ratio makes fibre-reinforced composite materials a glass-fibre-reinforced composite material. A total of 102 single-bolt double-shear lap connections

328

Design Criteria for Aramid Fibres Ioannis P. Giannopoulos  

E-print Network

Design Criteria for Aramid Fibres Ioannis P. Giannopoulos Dr. Chris J. Burgoyne Dept of Engineering, University of Cambridge Trumpington Street Cambridge, UK ABSTRACT Aramid fibres should have many structural different aramid fibres, Kevlar 49 and Technora. The paper shows how this information can be used to predict

Burgoyne, Chris

329

Delamination, fibre bridging and toughness of ceramic matrix composites  

Microsoft Academic Search

Delamination cracks in long-fibre reinforced ceramic matrix composites are found to be bridged by fibres which span the crack wake at a shallow angle. The in situ observation of bridging fibres reveals that these are subject to considerable tensile forces, giving rise to a substantial crack closure force. The overall crack closure force is determined by the number of bridging

D. A. W. Kaute; H. R. Shercliff; M. F. Ashby

1993-01-01

330

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

331

AIAA 2004-1819 Carbon Fibre Reinforced Plastic  

E-print Network

AIAA 2004-1819 Carbon Fibre Reinforced Plastic Tape Springs J.C.H. Yee , O. Soykasap , and S, Reston, VA 20191­4344 #12;Carbon Fibre Reinforced Plastic Tape Springs J.C.H. Yee , ¨O. Soykasap , and S trend is towards tape springs made of carbon fibre reinforced plastic (CFRP), for their tailorable

Soykasap, Omer

332

Sensor application of fibre ultrasonic waveguide  

NASA Astrophysics Data System (ADS)

This paper concerns the development of a new ultrasonic waveguide and its application as an environmental sensor. Ultrasonic waves have been guided in cylindrical structures to check the health of the structures themselves. Here, our attention is turned to environmental sensing based on such a cylindrical waveguide. To this end, the ultrasonic waveguide using an optical fibre and piezoelectric transducers is developed and demonstrated in a few promising applications: liquid leak detection, resin front and liquid evaporation monitoring sensors. The fibre waveguide affords notable advantages such as long-distance monitoring, minimum-invasive probing and cost-effectivity.

Lee, Jung-Ryul; Tsuda, Hiroshi

2006-04-01

333

Overview: Physical & DataLink LayersOverview: Physical & DataLink Layers How are frames assembled and transmitted ?  

E-print Network

. Optical Fibre · Optic fiber does not use electrical signals to transmit the data, rather it uses lightOverview: Physical & DataLink LayersOverview: Physical & DataLink Layers · How are frames assembled media types used for Data Communications The choice of medium depends on:Communications. The choice

Murphy, John

334

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

335

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

PubMed Central

Objective To assess the prevalence of localized retinal nerve fiber layer defects (LRNFLD) and associated factors in adult Chinese. Methods The population-based Beijing Eye Study 2011 included 3468 individuals (mean age: 64.6±9.8 years (range: 50–93 years)). The study participants underwent a detailed ophthalmological examination including spectral-domain optical coherence tomography (SpectralisR-OCT) assisted measurement of the RNFL. A LRNFLD was defined as a sector in which the RNFL contour line dipped into the red zone for a length of <180°. Results Readable OCT images were available for 3242 (93.5%) subjects. LRNFLDs were detected in 640 eyes (9.9±0.4%) of 479 subjects (14.8±0.6%). In the age groups of 50–59 years, 60–69 years, 70–79 years, and 80+ years, the prevalence of LRNFLD per person increased from 9.9±0.9%, 11.6±1.0% and 20.6±1.4% to 33.0±3.2%, respectively. In multivariate analysis, prevalence of LRNFLDs was significantly associated with older age (P?=?0.001; Odds Ratio (OR): 1.03; 95% Confidence Interval (CI): 1.01,1.05), myopic refractive error (P<0.001;OR:0.79;95%CI:0.74,0.85), larger beta zone of parapapillary atrophy (P<0.001; OR:1.34;95%CI:1.20,1.50), presence of glaucomatous optic neuropathy (P<0.001;OR:7.02;95%CI:3.87,12.7), presence of non-glaucomatous optic nerve damage (P?=?0.001;OR:43.3;95%CI:8.24,227.1), and presence of diabetic retinopathy (P?=?0.003;OR:2.79;95%CI:1.43,5.44). Conclusions OCT-defined LRNFLDs were present in a prevalence of 14.8±0.6% in a population-based study sample of subjects aged 50+ years. Prevalence of LRNFLDs increased with higher age, myopic refractive error, and larger parapapillary beta zone. Major ocular diseases associated with LRNFLs were glaucoma, non-glaucomatous optic nerve damage and diabetic retinopathy. These data may be helpful for a semiautomatic assessment of the RNFL. PMID:23894392

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

2013-01-01

336

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

337

A wide temperature tunable fibre laser using a chirped grating and a type IIA fibre Bragg grating  

Microsoft Academic Search

A fibre laser sensor has been developed to operate over a wide temperature range from room temperature to 440 °C, where the laser cavity has been formed using a combination of a chirped grating and a type IIA fibre Bragg grating (FBG), enclosing a length of erbium doped fibre as the active gain medium. A FBG stabilized 1480 nm laser

Jharna Mandal; Tong Sun; Kenneth T. V. Grattan; Andreas T. Augousti; Scott A. Wade; Stephen F. Collins; Gregory W. Baxter; Bernard Dussardier; Gérard Monnom

2004-01-01

338

OPTICAL FIBRES: Study of the dynamics of transformation of point defects in phosphosilicate fibres by the induced refraction index  

Microsoft Academic Search

A method for studying the dynamics of transformation of defects in optical fibres, exposed to UV radiation, by the dose dependence of the induced refractive index is proposed. The processes of transformation of defects in a low-loss phosphosilicate fibre, loaded with molecular hydrogen, irradiated at the 193-nm wavelength are investigated using this method. It is assumed that such a fibre

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

2003-01-01

339

Identification of Cellulosic Fibres by FTIR Spectroscopy I: Thread and Single Fibre Analysis by Attenuated Total Reflectance  

Microsoft Academic Search

Summary The ability to accurately identify fibres is of importance to conservators, allowing the most appropriate methods of treatment to be employed. Our research has concentrated on the development of an ATR FT-IR spectroscopic technique for the characterisation of cellulosic (plant) fibres. Six species of fibre were examined, taken largely from the bast group (flax, hemp, jute and ramie), along

Paul Garside; Paul Wyeth

340

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

341

Polarisation characteristics of light from multimode optical fibres  

SciTech Connect

The polarisation beats accompanying decay of LP-mode groups in multimode optical fibres with a step refractive index profile are considered. The theoretical dependences of the degree of linear polarisation on the optical fibre length and light exit angle are determined based on the waveguide properties of these groups. The results obtained are compared with the existing theoretical concepts. It is shown that the light emerging from a multimode optical fibre near its axis can retain linear polarisation in fibres up to several meters long. Some experimental results are reported, which confirm the basic theoretical conclusions. (optical fibres)

Kiesewetter, Dmitrii V [St. Petersburg State Technical University, St. Petersburg (Russian Federation)

2010-08-27

342

Optical properties of fibres with aluminophosphosilicate glass cores  

SciTech Connect

The optical properties of fibres with aluminophosphosilicate (APS) glass cores have been studied at Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} 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. (optical fibres)

Bubnov, M M; Zotov, K V; Iskhakova, L D; Lavrishchev, S V; Likhachev, M E; Rybaltovsky, A A; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, Aleksei N; Lipatov, D S; Khopin, V F; Yashkov, M V [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2009-09-30

343

Comparison of transverse load sensitivities of fibre Bragg gratings in different types of optical fibres  

Microsoft Academic Search

The response of optical fibre Bragg gratings (FBG) to transverse load was found to be significantly different for FBGs inscribed in two different types of single mode optical fibres. The transverse load sensitivity, defined as the relative wavelength separation of the birefringence-induced FBG double-peaks per transverse line-force, was found to be Cq = (45.1 +\\/- 1.5)10-9 1\\/N\\/m for a moderately

Florian Jülich; Johannes Roths

2010-01-01

344

Ultrastructure and chemistry of soluble and polymeric lipids in cell walls from seed coats and fibres of Gossypium species.  

PubMed

Electron-microscopic examination in conjunction with extraction procedures and chemical analysis have confirmed that a suberin-like lipid biopolymer is located within the concentric polylamellate layers found in the secondary cell walls of green cotton fibres (Gossypium hirsutum cv. green lint). A polymer of similar ultrastructure and chemical constitution also occurs mainly in the secondary seed-coat walls of the outer epidermis of both green and white varieties of G. hirsutum. The suberins composed of predominantly C22 compounds are, however, markedly different from those present in the periderms of the same plants; these comprise mainly C16 and C18 compounds. Long-chain 1-alkanols (C26-C36) and alkanoic acids (C16-C36) are the principal components of the wax from white fibres but these lipid classes comprise a much smaller proportion of that from green fibres. unidentified highmolecular-weight compounds were the major constituents of the green-fibre was extract which also contains a number of yellow-green pigments, probably flavonoid in nature. These pigments are thought to be associated with the ultrahistochemical reaction with silver proteinate that was observed only in the green-fibre cell walls. A total of 16 wild and cultivated cotton species were examined with the electron microscope for the presence of suberin. The outer seed-coat epidermis of all the examined species but only the fibres of the wild ones were found to be suberized. Among the analysed mutants of fibre colour in G. hirsutum only the gene Lg (green lint) seemed to be associated with suberin. PMID:24249333

Ryser, U; Holloway, P J

1985-02-01

345

Activated carbon fibre materials for VOC removal  

Microsoft Academic Search

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

P Navarri; D Marchal; A Ginestet

2001-01-01

346

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

347

Radiative Heat Transfer in Fibre Insulations  

Microsoft Academic Search

A first principles method of calculating combined radiative and conductive heat flow in fibrous insulation is presented. Using the measured complex refractive index for the bulk material, the scattering and absorption cross-sections are calculated for an isolated cylinder from expressions analogous to those of Mie theory for spheres. An average over fibre angles gives the cross-sections for the insulation material.

Neil Llewellyn McKay

1984-01-01

348

Original article Fibre type differentiation during postnatal  

E-print Network

in postural muscles (eg, soleus) where it refers to the altered muscle function after birth. In contrast muscles V Horák 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

Boyer, Edmond

349

Strain Measurements Using Fibre Bragg Grating Sensor  

Microsoft Academic Search

Fibre Bragg grating (FBG) sensors are widely accepted as strain and vibration monitoring devices for advanced composite mechanical structures. The advantages of using the FBG sensors include their small physical size, insensitivity to electromagnetic interference, lightweight, multiplex ability and ability to be used at relatively high temperature and environmentally unfavorable conditions. However, most research related to the use of embedded

Bashir Ahmad Tahir; Jalil Ali; Rosly Abdul Rahman

2005-01-01

350

Optical FM Demodulation by Fibre Bragg Grating  

Microsoft Academic Search

In this paper the application of fibre Bragg grating (FBG) as a FM demodulator is presented. Two types of FBG were investigated: with and without athermal package. Main factors limited application of FBG to FM demodulation such as thermal stability, slope of the FBG and dark current of photodetector were discussed. Maximum and minimum FM deviation possible to demodulate for

Jaroslaw Z. Sotor; Arkadiusz J. Antonczak; Krzysztof M. Abramski

2007-01-01

351

Optical Fibre Bragg Gratings for Acoustic Sensors  

Microsoft Academic Search

In this paper, we give a short review of Fibre Bragg Grating (FBG) sensors for the detection of acoustic signals, in particular ultrasound. The primary advantage of FBGs as sensing elements is their spectral encoding of the measurand, which can be either strain or temperature. However, spectral decoding methods cannot be utilized to detect high frequency signals due to their

Graham Wild; Steven Hinckley

2010-01-01

352

Left ventricular fibre architecture in man  

Microsoft Academic Search

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

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

1981-01-01

353

Fibring as biporting subsumes asymmetric combinations  

E-print Network

. We concentrate in this paper on importing (and, so, indirectly, in all the asymmetric mechanismsFibring as biporting subsumes asymmetric combinations J. Rasga A. Sernadas C. Sernadas Dep. Matem between importing (a logic combination mechanism that subsumes several asymmetrical mechanisms

Lisboa, Universidade Técnica de

354

Hybrid Composite Structures: Multifunctionality through Metal Fibres  

Microsoft Academic Search

The introduction of fibre reinforced polymer composites into the wings and fuselages of the newest aircraft are changing the design and manufacturing approach. Composites provide greater freedom to designers who want to improve aircraft performance in an affordable way. In this quest, researchers are looking to the area of multifunctional structures, which represents a new manufacturing and integration methodology. Composite

T. Ahmed

2009-01-01

355

Radiation curing of carbon fibre composites  

NASA Astrophysics Data System (ADS)

Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material.

Spadaro, G.; Alessi, S.; Dispenza, C.; Sabatino, M. A.; Pitarresi, G.; Tumino, D.; Przbytniak, G.

2014-01-01

356

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

NASA Astrophysics Data System (ADS)

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

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

1997-10-01

357

Dietary fibre, lente carbohydrates and the insulin-resistant diseases.  

PubMed

Several epidemiological studies link consumption of fibre-rich foods to a reduced risk of type 2 diabetes and CHD. The 'fibre hypothesis' suggested that this was a direct effect of fibre. However, fibre-rich foods contain different types of fibre as well as other potentially beneficial compounds, and many foods naturally high in fibre have low glycaemic and insulinaemic indices, possibly due to food form. The question therefore emerges as to the effect of isolated fibre per se on insulin sensitivity, lipids and other risk factors associated with the metabolic syndrome. Many beneficial effects are seen with pharmacological doses of isolated viscous soluble fibre, including improved insulin sensitivity, decreased LDL-cholesterol levels and decreased clotting factors. Similar effects are seen with low glycaemic-index foods. In contrast, insoluble non-viscous cereal fibre is not seen to act directly on risk factors when taken in refined foods such as in milled flour. Since cereal fibre, the major type of fibre in western diets, does not directly act on the risk factors for the metabolic syndrome, the question remains as to possible mechanisms. Until now, fibre and the nature and processing of the starch and particle size have been seen as the main determinants of the metabolic response to starchy foods. However, fibre-rich foods also have an increased protein-to-carbohydrate ratio. Hence we suggest that the protective effect of fibre may also be due to increased vegetable protein content, which may act directly to reduce clotting factors and oxidized LDL-cholesterol levels. PMID:10889807

Jenkins, D J; Axelsen, M; Kendall, C W; Augustin, L S; Vuksan, V; Smith, U

2000-03-01

358

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

359

March of the Starbugs: Configuring Fibre-bearing Robots on the UK-Schmidt Optical Plane  

E-print Network

The TAIPAN instrument, currently being developed for the Australian Astronomical Observatory's UK Schmidt telescope at Siding Spring Observatory, makes use of the AAO's Starbug technology to deploy 150 science fibres to target positions on the optical plane. This paper describes the software system for controlling and deploying the fibre-bearing Starbug robots. The TAIPAN software is responsible for allocating each Starbug to its next target position based on its current position and the distribution of targets, finding a collision-free path for each Starbug, and then simultaneously controlling the Starbug hardware in a closed loop, with a metrology camera used to determine the position of each Starbug in the field during reconfiguration. The software is written in C++ and Java and employs a DRAMA middleware layer (Farrell et al. 1995).

Lorente, Nuria P F; Satorre, Christophe; Hong, Sungwook E; Shortridge, Keith; Goodwin, Michael; Kuehn, Kyler

2015-01-01

360

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

361

Macroscopic assembled, ultrastrong and H(2)SO(4)-resistant fibres of polymer-grafted graphene oxide.  

PubMed

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

362

Tapered optical fibre sensor for detection of hydrocarbon spills in seawater  

NASA Astrophysics Data System (ADS)

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

Sánchez Martín, J. A.; Bernabeu, E.; Rodríguez Aramendía, A.; Villalba, A.; Cruzado, E.; Pardo de Santayana, M.

2014-05-01

363

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

NASA Astrophysics Data System (ADS)

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

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

2006-02-01

364

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

365

A novel cryogenic fibre maker for continuous extrusion  

SciTech Connect

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

Aliaga-Rossel, R.; Bayley, J. [Blackett Laboratory, Imperial College, London (United Kingdom)

1997-05-05

366

Fibre laser component technology for 2-micron laser systems  

NASA Astrophysics Data System (ADS)

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

Stevens, G.; Robertson, A.

2014-05-01

367

Carbon fibre compressive strength and its dependence on structure and morphology  

Microsoft Academic Search

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

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

1993-01-01

368

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

369

Investigation of focal ratio degradation in optical fibres for astronomical instrumentation  

E-print Network

Investigation of focal ratio degradation in optical fibres for astronomical instrumentation Lisa) exhibited by, and throughput of, a selection of current-generation optical fibres. These fibres were tested-mode fibres, focal ratio degradation 1. INTRODUCTION 1.1 Goals Fibre optics for astronomy offer a relatively

Bershady, Matthew A.

370

Influence of processing and chemical treatment of flax fibres on their composites  

Microsoft Academic Search

During the consecutive decortication stages of flax fibres (retting, scutching, hackling, …), the fibre properties change tremendously due to mechanical and chemical modifications. This study points out the influence of the flax processing parameters, and consequently of the fibre properties, on the mechanical properties of flax fibre reinforced epoxy composites. The better the retting degree of the fibres, the better

I. Van de Weyenberg; J. Ivens; A. De Coster; B. Kino; E. Baetens; I. Verpoest

2003-01-01

371

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

372

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

373

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

374

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

PubMed Central

Summary Amyloid fibres are proteinaceous aggregates associated with several human diseases, including Alzheimer’s, Huntington’s and Creutzfeldt Jakob’s. Disease-associated amyloid formation is the result of proteins that misfold and aggregate into ? sheet-rich fibre polymers. Cellular toxicity is readily associated with amyloidogenesis, although the molecular mechanism of toxicity remains unknown. Recently, a new class of ‘functional’ amyloid fibres was discovered that demonstrates that amyloids can be utilized as a productive part of cellular biology. These functional amyloids will provide unique insights into how amyloid formation can be controlled and made less cytotoxic. Bacteria produce some of the best-characterized functional amyloids, including a surface amyloid fibre called curli. Assembled by enteric bacteria, curli fibres mediate attachment to surfaces and host tissues. Some bacterial amyloids, like harpins and microcinE492, have exploited amyloid toxicity in a directed and functional manner. Here, we review and discuss the functional amyloids assembled by bacteria. Special emphasis will be paid to the biology of functional amyloid synthesis and the connections between bacterial physiology and pathology. PMID:18373633

Epstein, Elisabeth Ashman; Chapman, Matthew R.

2009-01-01

375

Numerical simulation of photonic-crystal tellurite-tungstate glass fibres used in parametric fibre devices  

SciTech Connect

Using the MIT Photonic-Bands Package to calculate fully vectorial definite-mode eigenmodes of Maxwell's equations with periodic boundary conditions in a plane-wave basis, light propagation is simulated in fibres formed by point defects in two-dimensional periodic lattices of cylindrical holes in a glass or of glass tubes. The holes and gaps between tubes are assumed filled with air. Single-site hexagonal and square lattices are considered, which were most often studied both theoretically and experimentally and are used to fabricate silica photonic-crystal fibres. As a defect, a single vacancy is studied - the absent lattice site (one hole in a glass or one of the tubes are filled with the same glass) and a similar vacancy with nearest neighbours representing holes of a larger diameter. The obtained solutions are analysed by the method of effective mode area. The dependences of the effective refractive index and dispersion of the fundamental mode on the geometrical parameters of a fibre are found. The calculations are performed for tellurite-tungstate 80TeO{sub 2}-20WO{sub 3} glass fibres taking into account the frequency dispersion of the refractive index. (optical fibres)

Sokolov, V O; Plotnichenko, V G; Nazaryants, V O; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2006-01-31

376

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

377

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

378

Retention of Cationic Starch onto Cellulose Fibres  

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

379

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

NASA Astrophysics Data System (ADS)

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

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

1998-04-01

380

Structural characteristics of aramid fibre variants  

Microsoft Academic Search

Recently new types of high-performance aramid fibre based on poly(p-phenylene terephthalamide) have been developed. This paper reports on their very different tensile behaviour and structural character as revealed by electron microscope and X-ray diffraction studies. The relationship between mechanical performance and structure of the variants is explored in detail, and performance-limiting factors are identified with a view to understanding how

M. G. Dobb; R. M. Robson

1990-01-01

381

Fibred Coalgebraic Logic and Quantum Protocols  

E-print Network

Motivated by applications in modelling quantum systems using coalgebraic techniques, we introduce a fibred coalgebraic logic. Our approach extends the conventional predicate lifting semantics with additional modalities relating conditions on different fibres. As this fibred setting will typically involve multiple signature functors, the logic incorporates a calculus of modalities enabling the construction of new modalities using various composition operations. We extend the semantics of coalgebraic logic to this setting, and prove that this extension respects behavioural equivalence. We show how properties of the semantics of modalities are preserved under composition operations, and then apply the calculational aspect of our logic to produce an expressive set of modalities for reasoning about quantum systems, building these modalities up from simpler components. We then demonstrate how these modalities can describe some standard quantum protocols. The novel features of our logic are shown to allow for a uniform description of unitary evolution, and support local reasoning such as "Alice's qubit satisfies condition" as is common when discussing quantum protocols.

Daniel Marsden

2014-12-30

382

Micro-Mechanical Parameters in Short Fibre Composite  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

383

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

384

Amplifying properties of heavily erbium-doped active fibres  

SciTech Connect

The relative concentration of erbium ions undergoing nonradiative relaxation from the metastable to the ground level is measured in aluminosilicate glass fibres doped with erbium ions at concentration between 3x10{sup 18} and 10{sup 20} cm{sup -3}. The dependence of the fraction of such ions on the Er{sup 3+} concentration is determined for fibres containing different amounts of aluminium oxide in a core. It is shown that the fraction of erbium ions not involved in amplification substantially decreases with increasing the Al{sub 2}O{sub 3} concentration. It is found that clustering leads to a considerable decrease in the gain in heavily Er{sup 3+}-doped active fibres. The dependence of the quantum efficiency of a fibre amplifier on the erbium ion concentration is obtained based on the measurements performed. This dependence can be used for optimising the parameters of erbium-doped fibre amplifiers. (fibres. integrated-optic waveguides)

Plotskii, A Yu; Kurkov, Andrei S; Yashkov, M Yu; Bubnov, M M; Likhachev, M E; Sysolyatin, A A; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, A N [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2005-06-30

385

Bizarre repetitive discharges recorded with single fibre EMG.  

PubMed Central

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

Trontelj, J; Stålberg, E

1983-01-01

386

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

SciTech Connect

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

Linkov, V.M.; Sanderson, R.D.; Jacobs, E.P. [Univ. of Stellenbosch (South Africa)

1994-12-31

387

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

PubMed

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

Chen, Lei; Bird, David M

2011-03-28

388

Three-dimensional spectral domain optical coherence tomography in X linked foveal retinoschisis  

PubMed Central

Spectral domain optical coherence tomography (SD-OCT) was performed in two cases of bilateral X linked foveal retinoschisis of different age groups. On fundus examination spoke wheel and honeycomb pattern of cysts were observed along with retinal nerve fibre layer (RNFL) defects. On SD-OCT, schisis was observed in the outer plexiform layer. External limiting membrane disruption was observed in the subfoveal area, along with disruption of outer nuclear layer (ONL) and inner–outer segment junction. Elevation of ONL due to tractional pull of central palisade was a novel observation. Retinoschisis extended beyond the optic disc up to the nasal region. Extracted RNFL tomogram presented an unprecedented visualisation of schisis along 360° of the optic disc. Tractional elevation in the foveal area and schisis involving nasal region, not observed upon clinical examination, was highlighted on SD-OCT. This investigative modality is an important adjunct in the assessment of foveal retinoschisis. PMID:23563673

Saxena, Sandeep; Manisha; Meyer, Carsten H

2013-01-01

389

Fibre drawing from blends of polypropylene and liquid crystal polymers  

SciTech Connect

The paper highlights the hot-drawing of melt-extruded fibres consisting of a polypropylene (PP) matrix and liquid crystal polymer (LCP) as a minor component in a separate phase. During drawing, LCP fibrils, formed within the fibre blend during melt-extrusion, are liable to split into short fragments. After conventional one-stage drawing, fibre reinforcement ceases to be provided by the LCP, and indeed mechanical performance is generally reduced.

Qin, Y.; Brydon, D.L.; Mather, R.R. [Heriot-Watt Univ., Galashiels (United Kingdom)

1995-12-01

390

Thermal dependence of passive electrical properties of lizard muscle fibres.  

PubMed

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

Adams, B A

1987-11-01

391

Optical fibre musical instruments: making sense of the senseless  

Microsoft Academic Search

This paper demonstrates how the light transmitted through a stretched optical fibre may be used to detect its modes of vibration.\\u000a In particular, replacing strings of a musical instrument with optical fibre allows the fabrication of a simple acoustic instrument\\u000a with a single laser source and single detector. The detected signal contains rich harmonics of the vibrating fibre. This device

Isabelle Christiane Fotsing-Djouwe; Mathieu Gagné; Jean-Jacques Laurin; Raman Kashyap

2009-01-01

392

Terahertz pulse transmission in plastic photonic crystal fibres  

Microsoft Academic Search

Guided-wave single-mode propagation of sub-ps terahertz (THz) pulses in a plastic photonic crystal fibre has been experimentally demonstrated. The plastic photonic crystal fibre (PPCF) is fabricated from high-density polyethylene tubes and filaments. The fibre exhibits low loss and relatively low dispersive propagation of THz pulses within the experimental bandwidth of 0.1-3 THz. Such PPCFs have the promise of low loss,

M. Cho; J. Kim; H. Han

2002-01-01

393

Lead silicate microstructured optical fibres for electro-optical applications.  

PubMed

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

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

2013-12-16

394

Description and Performance of the Optical Fibre Diameter Analyser (OFDA)  

Microsoft Academic Search

This paper describes the development of an image-analysis system designed to determine rapidly and precisely the fibre-diameter distribution of a representative specimen of fibre snippets.The instrument hardware and software are described, together with the procedures developed for the measurement of wool samples. Other animal and artificial fibres may also be satisfactorily measured by the instrument. This paper includes details of

B. P. Baxter; M. A. Brims; T. B. Taylor

1992-01-01

395

A simple method to prepare boron suboxide fibres  

Microsoft Academic Search

In this paper, boron suboxide fibres are synthesized by a solid state reaction method using CaO, B and Fe3O4 as starting materials in Ar atmosphere. The boron suboxide fibres include nanobelts and nanowires and they have unique morphologies.\\u000a Through adjusting the contents of starting materials, we can control the diameters of boron suboxide fibres. Using the laser\\u000a Raman spectrum, the

Minghe Cao; Jun Jiang; Hanxing Liu; Jun Yuan

2006-01-01

396

Photosensitivity of optical fibres doped with different impurities  

Microsoft Academic Search

Photosensitivities of hydrogen-loaded silica fibres doped with germanium, phosphorus, antimony, and aluminium are estimated and compared. It is shown that although all the fibres can be pre-exposed, the degree of this effect is noticeably different for different fibres because the induction of the refractive index is determined by a combined contribution from a one-step photochemical reaction and a two-step reaction

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

2004-01-01

397

Fatigue damage mechanisms in unidirectional carbon-fibre-reinforced plastics  

Microsoft Academic Search

The fatigue life behaviour and the underlying micromechanisms have been studied in two different Types of unidirectional carbon-fibre-reinforced plastics loaded in tension-tension along the fibre direction. The carbon fibres (AS4) were the same in the two composite systems. One thermoplastic matrix (polyetheretherketone, PEEK) and one thermosetting matrix (epoxy toughened with a thermoplastic additive) were used. The macroscopic fatigue behaviour was

E. K. Gamstedt; R. Talreja

1999-01-01

398

Characteristics of a silk fibre reinforced biodegradable plastic  

Microsoft Academic Search

Silk fibre is one kind of well recognized animal fibres for bio-medical engineering and surgical operation applications because of its biocompatible and bio-resorbable properties. Recently, the use of silk fibre as reinforcement for some bio-polymers to enhance the stiffnesses of scaffolds and bone fixators has been a hot research topic. However, their mechanical and biodegradable properties have not yet been

Mei-po Ho; Kin-tak Lau; Hao Wang; Debes Bhattacharyya

2011-01-01

399

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

400

Simulations and Experiments on Polarisation Squeezing in Optical Fibre  

E-print Network

We investigate polarisation squeezing of ultrashort pulses in optical fibre, over a wide range of input energies and fibre lengths. Comparisons are made between experimental data and quantum dynamical simulations, to find good quantitative agreement. The numerical calculations, performed using both truncated Wigner and exact $+P$ phase-space methods, include nonlinear and stochastic Raman effects, through coupling to phonons variables. The simulations reveal that excess phase noise, such as from depolarising GAWBS, affects squeezing at low input energies, while Raman effects cause a marked deterioration of squeezing at higher energies and longer fibre lengths. The optimum fibre length for maximum squeezing is also calculated.

Joel F. Corney; Joel Heersink; Ruifang Dong; Vincent Josse; Peter D. Drummond; Gerd Leuchs; Ulrik L. Andersen

2008-07-16

401

Advances in infrared and imaging fibres for astronomical instrumentation  

E-print Network

Optical fibres have already played a huge part in ground based astronomical instrumentation, however, with the revolution in photonics currently taking place new fibre technologies and integrated optical devices are likely to have a profound impact on the way we manipulate light in the future. The Anglo-Australian Observatory, along with partners at the Optical Fibre Technology Centre of the University of Sydney, is investigating some of the developing technologies as part of our Astrophotonics programme. In this paper we discuss the advances that have been made with infrared transmitting fibre, both conventional and microstructured, in particular those based on flouride glasses. Flouride glasses have a particularly wide transparent region from the UV through to around 7um, whereas silica fibres, commonly used in astronomy, only transmit out to about 2um. We discuss the impact of advances in fibre manufacture that have greatly improved the optical, chemical resistance and physical properties of the flouride fibres. We also present some encouraging initial test results for a modern imaging fibre bundle and imaging fibre taper.

Roger Haynes; Pam McNamara; Jackie Marcel; Nemanja Jovanovic

2006-06-13

402

Microstructured fibres: a positive impact on defence technology?  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

403

Coupling light into optical fibres near the diffraction limit  

E-print Network

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

Anthony J. Horton; Joss Bland-Hawthorn

2006-06-13

404

Prospects for millimetre-wave-over-fibre and THz-over-fibre systems  

NASA Astrophysics Data System (ADS)

Optical fibre transmission has enabled greatly increased transmission rates, with 10 Gb/s common in local area networks. End users find wireless access highly convenient, however limited spectrum availability at microwave frequencies results in per-user transmission rates which are limited to much lower values, 500 Mb/s for 5 GHz band IEEE 802.11ac, for example. Extending the high data-rate capacity of optical fibre transmission to wireless devices, requires greatly increased carrier frequencies. This paper will describe how photonic techniques can enable ultra-high capacity wireless data distribution and transmission using signals at millimetre-wave and TeraHertz (THz) frequencies.

Seeds, Alwyn; Shams, Haymen; Fice, Martyn; Balakier, Katarzyna; Ponnampalam, Lalitha; Renaud, Cyril

2015-01-01

405

Guidance in Kagome-like photonic crystal fibres I: analysis of an ideal fibre structure.  

PubMed

Propagation of light in a square-lattice hollow-core photonic crystal fibre is analysed as a model of guidance in a class of photonic crystal fibres that exhibit broad-band guidance without photonic bandgaps. A scalar governing equation is used and analytic solutions based on transfer matrices are developed for the full set of modes. It is found that an exponentially localised fundamental mode exists for a wide range of frequencies. These analytic solutions of an idealised structure will form the basis for analysis of guidance in a realistic structure in a following paper. PMID:21451720

Chen, Lei; Pearce, Greg J; Birks, Timothy A; Bird, David M

2011-03-28

406

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

407

An interrogator for fibre Bragg grating sensors using an ultrasonically induced long-period optical fibre grating  

Microsoft Academic Search

An ultrasonically induced long-period fibre grating (U-LPFG) functions as a tunable notch filter, since the pitch of refractive index modulation is changed by the driving frequency of the ultrasonic vibration propagating along a fibre. In this paper, we present the application of the U-LPFG for a fibre Bragg grating (FBG) sensor interrogator. If the U-LPFG is connected to the FBG

Norimichi Fukuma; Kenji Kubota; Kentaro Nakamura; Sadayuki Ueha

2006-01-01

408

Study of the thermal degradation of high performance fibres—application to polybenzazole and p-aramid fibres  

Microsoft Academic Search

This work investigates the thermal degradation of high performance fibres. Poly-p-phenylenediamine-terephthalamide fibres (PPTA) and poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibres are examined when degrading in a furnace. Both gas and condensed phase are analysed. When degrading PPTA and PBO, CO, CO2 and H2O are detected by FTIR as major compounds composing the gas phase. As minor products, aromatic species, hydrocyanic acid (HCN) and

Serge Bourbigot; Xavier Flambard; Franck Poutch

2001-01-01

409

Determination of fibre-matrix interfacial properties in ceramic-matrix composites by a fibre push-out technique  

Microsoft Academic Search

A simple concentric cylinder model is developed for the fibre push-out test in order to interpret the experimentally observed indenter load-displacement curves in ceramic-matrix composites. The fibre-matrix interface is assumed to be partially bonded and partially frictionally coupled. It is shown that a slope change in the loading curve corresponds to bonding at the fibre-matrix interface. In contrast an insignificant

R. N. Singh; M. Sutcu

1991-01-01

410

Three myosin heavy chain isoforms in type 2 skeletal muscle fibres  

Microsoft Academic Search

Summary Mammalian skeletal muscles consist of three main fibre types, type 1, 2A and 2B fibres, with different myosin heavy chain (MHC) composition. We have now identified another fibre type, called type 2X fibre, characterized by a specific MHC isoform. Type 2X fibres, which are widely distributed in rat skeletal muscles, can be distinguished from 2A and 2B fibres by

Stefano Schiaffino; Luisa Gorza; Saverio Sartore; Leopoldo Saggin; Simonetta Ausoni; Monica Vianello; Kristian Gundersen; Terje LØmo

1989-01-01

411

Neutralizing IL-17 protects the optic nerve from autoimmune pathology and prevents retinal nerve fiber layer atrophy during experimental autoimmune encephalomyelitis.  

PubMed

Optic neuritis is a common inflammatory manifestation of multiple sclerosis (MS). In experimental autoimmune encephalomyelitis (EAE), the optic nerve is affected as well. Here, we investigated whether autoimmune inflammation in the optic nerve is distinct from inflammation in other parts of the central nervous system (CNS). In our study, inflammatory infiltrates in the optic nerve and the brain were characterized by a high fraction of Ly6G(+) granulocytes whereas in the spinal cord, macrophage infiltrates were predominant. At the peak of disease, IL-17 mRNA abundance was highest in the optic nerve as compared with other parts of the CNS. The ratio of IL-17 vs IFN-? producing CD4(+) T cells was higher in the optic nerve and brain than in the spinal cord and more effector CD4(+) T cells were committed to the Th17 transcriptional program in the optic nerve than in the spinal cord. IL-17 producing ?? T cells but rather not Ly6G(+) granulocytes themselves contributed to IL-17 production. Optical coherence tomography (OCT) studies on murine eyes revealed a decline in thickness of the retinal nerve fiber layer (RNFL) and the common layer of ganglion cells and inner plexiform layer (GCL+) after the recovery from motor symptoms indicating that autoimmune inflammation induced a significant atrophy of optic nerve fibers during EAE. Neutralization of IL-17 by treatment with anti-IL-17 antibodies reduced but did not abrogate motor symptoms of EAE. However, RNFL and GCL+ atrophy were completely prevented by blocking IL-17. Thus, the optic nerve compartment is particularly prone to support IL-17 mediated inflammatory responses during CNS autoimmunity and structural integrity of the retina can be preserved by neutralizing IL-17. PMID:25282335

Knier, Benjamin; Rothhammer, Veit; Heink, Sylvia; Puk, Oliver; Graw, Jochen; Hemmer, Bernhard; Korn, Thomas

2015-01-01

412

Epidermal in vivo and in vitro studies by attenuated total reflection mid-infrared spectroscopy using flexible silver halide fibre-probes  

Microsoft Academic Search

Dermatology studies focussing on the stratum corneum were carried out by infrared attenuated total reflection (ATR) spectroscopy using flexible fibre-optic probes made from square cross-section polycrystalline silver halide material. We compared the upper horny layer of human and bovine udder skin (BUS). As a substitute for human in vivo tests, the in vitro model of the isolated perfused bovine udder

H. M. Heise; L. Küpper; W. Pittermann; M. Stücker

2003-01-01

413

Flexible ceramic-reinforced polyurethane composite coatings on synthetic fibres: Process of continuous liquid film coating and its influence on the coating thickness  

Microsoft Academic Search

A concept for the realisation of composite layers on the surface of synthetic fibres by continuous liquid film coating of spread roving or monofilaments with a slurry containing ceramic particles and a polymeric binder is successfully demonstrated. Polyamide 6 monofilaments were coated with alumina particles and a polyurethane elastomer based binder system to achieve higher abrasion resistance. Under frictional load,

Felix A. Reifler; Felipe A. L. Sánchez; Frank J. Clemens; Ksenija Varga; Rudolf Hufenus

2010-01-01

414

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

415

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

416

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

SciTech Connect

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

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

2001-08-31

417

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

PubMed

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

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

2001-08-01

418

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

419

Ultrastructure and chemistry of soluble and polymeric lipids in cell walls from seed coats and fibres of Gossypium species  

Microsoft Academic Search

Electron-microscopic examination in conjunction with extraction procedures and chemical analysis have confirmed that a suberin-like lipid biopolymer is located within the concentric polylamellate layers found in the secondary cell walls of green cotton fibres (Gossypium hirsutum cv. green lint). A polymer of similar ultrastructure and chemical constitution also occurs mainly in the secondary seed-coat walls of the outer epidermis of

U. Ryser; P. J. Holloway

1985-01-01

420

Towards implementation of hollow core fibres for surgical applications  

NASA Astrophysics Data System (ADS)

Presently, there is no truly flexible delivery system for light from Er:Yag medical lasers (? = 2.94 ?m) which allows surgeons to work unrestricted. Instead, either a relatively inflexible articulated arm or multi-mode fibre, limited to large bend radii, must be used. One proposed solution is the use of novel types of hollow core - band gap optical fibre rather than more traditional large area solid core fibres. In these silica based fibres, material absorption and damage limitations are overcome by using a photonic band gap structure. This confines radiation to lower order modes, that are guided in a small diameter air core. The overall fibre diameter is also smaller, which allows a smaller mechanical bend radius. Together with the guidance in air, this improves the laser power damage threshold. However, there are many practical hurdles that must be overcome to achieve a robust system for use in surgery. One of the main problems is that the fibre structure is hollow and ingress of dust, vapour, fluids and other contaminants need to be prevented to ensure safe in-vivo usage. Additionally, any infibre contamination will degrade the laser damage resistance of the fibre leading to potential catastrophic failure. The development of a robust and hermetically sealed end cap for the fibre, without adversely affecting beam quality or damage threshold is an essential prerequisite for the safe and efficient use of such fibres in surgery. In this paper we report on the progress on implementing end caps and describe novel methods of sealing off these hollow fibres in particular for surgical applications. This work will demonstrate that the use of these superior fibres with low loss guidance at 2.94 ?m in surgery is feasible.

Urich, Artur; Delmonte, Tiina; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

2011-03-01

421

Morphological and chemical characterization of microfabricated fibres for biological applications.  

PubMed

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

Gold, J; Kasemo, B

1997-05-01

422

Reduced fibre breakage in a glass-fibre reinforced thermoplastic through foaming  

E-print Network

to dramatically reduce the occurrence of fibre breakage during processing within an injection molding machine-line rheometer was used on the injection molding machine to characterize the melt rheology of the polypropylene. Introduction Injection molding is generally the one of the most economical approaches for producing formed

Thompson, Michael

423

Temperature-Insensitive Fibre-Optic Acceleration Sensor Based on Intensity-Referenced Fibre Bragg Gratings  

Microsoft Academic Search

A temperature-insensitive acceleration sensor using two fibre Bragg gratings (FBGs), based on reflection spectrum intensity modulation and optical power detection, is proposed and demonstrated. A cantilever beam is used to generate acceleration-induced axial strain along two sensing gratings, which are glued on the two opposite surfaces of the beam. Because the two gratings operate within the linear spectral range of

Li-Qun Sun; Bo Dong; Yong-Xin Wang; LALLY Evan; An-Bo Wang

2008-01-01

424

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

Microsoft Academic Search

Acoustic sensors are used in Structural Health Monitoring (SHM) for the detection of impacts and strain. However, secondary damage may result from the initial damage. This secondary damage, such as delamination or cracking, may not be detectable by the SHM system. This is a significant problem for passive sensing systems, such as those based on fibre optics, where signals cannot

Graham Wild; Steven Hinckley

2008-01-01

425

Fibre Optic Sensors for Heat Transfer Studies.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. This thesis describes the design and development of a prototype sensor, based on a miniature optical fibre Fabry-Perot interferometer, for heat transfer studies on model turbomachinery components in transient flow wind tunnels. These sensors overcome a number of difficulties which are often encountered in using conventional electrical thin-film resistance gauges such as in the measurement of rapidly varying heat transfer rates, spatial resolution, electromagnetic interference, calibration and signal processing. The special features of the optical sensor are: (i) short length (<5 mm), and therefore embeddable in thin structures of model components; (ii) direct measurement of heat flux rates; (iii) calorimetric operation with temperature resolution of <25 mK over a measurement bandwidth of 100 kHz: (iv) capability of measuring heat flux <5 kWm^ {-2} with measurement range in excess of 10 MWm^{-2}; (v) temporal response time of <10 mus; (vi) minimal thermal disturbances because models are often made of ceramic materials with thermal properties similar to those of the optical fibre from which sensors are made; (vii) possibility of using in models with dissimilar thermal properties to the optical fibre, for example, metals; (viii) spatial resolution of <5 mu m; (ix) remote operation; (x) an ability to be multiplexed; and (xi) immunity to electromagnetic interference. A detailed discussion of the design considerations for the sensor, system development, evaluation of the sensor performance both in the laboratory and wind tunnel environments is presented in this thesis. The performance of the sensor compared favourably with electrical gauges namely, platinum thin-film resistance thermometers. A 4-sensor multiplexed system has been sucessfully operated, and is reported in the thesis. A brief discussion is also included to indicate that the same sensor design may be considered for applications in other engineering areas.

Sinha, Pranay G.

426

The effects of the fibre environment on the paths taken by regenerating optic nerve fibres in Xenopus.  

PubMed

The paths taken by fibres regenerating to the tectum from various parts of the Xenopus retina were investigated in whole-mount preparations, after localized retinal labelling with HRP. The effects of different environments on the fibres were studied by comparing contralateral with ipsilateral regeneration, in the presence of the other eye or after it had been removed in embryonic life. Under all conditions fibres from the various parts of the retina regenerated to the corresponding appropriate parts of the tectum, but they took a variety of pathways, some grossly abnormal, to get there. Contralaterally regenerating fibres tended to behave less abnormally than ipsilateral fibres; and regeneration in the absence of the other eye tended to be more abnormal than in its presence. In any one category of regeneration the most nearly normal pathways were those of fibres from temporal retina, followed by ventral, nasal and dorsal fibres. Fibres regenerating from all parts of the retina, in the presence of the other eye, tended to become gathered into the medial brachium as they approached the tectum. All regenerating fibres approached their tectal terminations by one or more of three main pathways: round one or both brachia, thus encircling the tectum to get to their terminal zone; directly across the tectum; or by passing on to the tectum before changing course. The changes of direction required to enable fibres wrongly positioned in the tract to reach their correct terminal zones were frequently sudden and considerable, and took place on the tectum or at the tectodiencephalic junction. The results are discussed in relation to the differing substrates over which the fibres regenerate. PMID:4093753

Taylor, J S; Gaze, R M

1985-10-01

427

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

428

Distributed quantum computation via optical fibres  

E-print Network

We investigate the possibility of realising effective quantum gates between two atoms in distant cavities coupled by an optical fibre. We show that highly reliable swap and entangling gates are achievable. We exactly study the stability of these gates in presence of imperfections in coupling strengths and interaction times and prove them to be robust. Moreover, we analyse the effect of spontaneous emission and losses and show that such gates are very promising in view of the high level of coherent control currently achievable in optical cavities.

Alessio Serafini; Stefano Mancini; Sougato Bose

2006-01-09

429

Holmium fibre laser with record quantum efficiency  

SciTech Connect

We report holmium-doped fibre lasers with a Ho{sup 3+} concentration of 1.6 x 10{sup 19} cm{sup -3} and lasing wavelengths of 2.02, 2.05, 2.07 and 2.1 {mu}m at a pump wavelength of 1.15 {mu}m. The slope efficiency of the lasers has been measured. The maximum efficiency, 0.455, has been obtained at a lasing wavelength of 2.05 {mu}m. The laser efficiency is influenced by both the optical loss in the wing of a vibrational absorption band of silica and active-ion clustering. (lasers)

Kurkov, Andrei S; Sholokhov, E M; Tsvetkov, V B; Marakulin, A V; Minashina, L A; Medvedkov, O I; Kosolapov, A F

2011-06-30

430

High-temperature compatibility of carbon fibres with nickel  

Microsoft Academic Search

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

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

1978-01-01

431

Effect of thermal ageing on Nylon 6,6 fibres  

Microsoft Academic Search

The residual effects of thermal ageing at various temperatures on fibres of the aliphatic polyamide Nylon 6,6 have been studied. Both crystal and macro structural characteristics manifest the residual effects. The former category includes changes in intensity, 2? values and half width. The macro changes include introduction of surface damages in the form of holes, material deposits etc. The fibre

A. Jain; K. Vijayan

2002-01-01

432

A novel aqueous route for the synthesis of mullite fibres  

Microsoft Academic Search

There can be significant advantages in the prepara- tion of ceramic materials as fibres rather than as bulk solids. In a fibrous form, brittle materials can develop higher strengths and moduli (1), while fine fibres are reasonably flexible and can be manipulated in large-scale fabrication processes without risk of breakage. Although the electronic properties of certain materials are usually utilized

A. K. Bhattacharya; A. Hartridge; K. K. Mallick; D. M. Taylor

1996-01-01

433

Strengthening of Carbon Fibres by Fast Neutron Irradiation  

Microsoft Academic Search

To assess the effect of fast neutron irradiation on its structure and mechanical properties, a polyacrylonitrile (PAN) based fibre, manufactured by Rolls Royce Limited, was irradiated in the test facilities of the WR1 organic cooled nuclear reactor at temperatures in the range 400°-700° C. Mechanical tests were made at room temperature on the fibres before and after irradiation using a

B. F. Jones; I. D. Peggs

1972-01-01

434

Structural integrity monitoring with fibre Bragg grating sensors  

Microsoft Academic Search

Purpose – This paper describes a recent collaborative project involving the development of a multiplexed fibre Bragg grating (FBG) sensor system for structural integrity monitoring. Design\\/methodology\\/approach – The system is described and field trials on both conventional and novel composite bridges are discussed. A FBG sensor-based structural monitoring system was developed, based on a fluorescent fibre as the optical source.

Robert Bogue

2005-01-01

435

Precise Characterization of Fibre Bragg Gratings for Photonic Communications Systems  

Microsoft Academic Search

A new class of structures based on fibre Bragg gratings enable the next generation of lightwave communication systems. However, these devices require precise recording and determination of the fibre Bragg gratings characteristics for optimised performance. In this paper we present a technique for a precise spatial characterization of gratings based structures. A theoretical model as well as the corresponding experimental

R. Nogueira; I. Abe; H. J. Kalinowski; J. F. da Rocha; J. L. Pinto

436

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

437

Supercontinuum generation in photonic crystal fibres: Modelling and dispersion engineering  

E-print Network

in optical fibres 9 2.1 The generalised nonlinear Schr¨odinger equation . . . . . . . . 10 2.2 PhysicalSupercontinuum generation in photonic crystal fibres: Modelling and dispersion engineering for spectral shaping Michael H. Frosz August 31st 2006 COM·DTU Department of Communications, Optics & Materials

438

Nonlinear limits to the information capacity of optical fibre communications  

Microsoft Academic Search

The exponential growth in the rate at which information can be communicated through an optical fibre is a key element in the `information revolution'. However, as for all exponential growth laws, physical limits must be considered. The nonlinear nature of the propagation of light in optical fibre has made these limits difficult to elucidate. Here we use a key simplification

Partha P. Mitra; Jason B. Stark

2001-01-01

439

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

440

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, Université de

441

Heat transfer within a microstructured polymer optical fibre preform  

Microsoft Academic Search

Preform heating is one of the most important steps in the polymer fibre fabrication process due to the potential distortion that can be introduced when exposing the structure to high temperatures. Such heating is further complicated when internal air-structures are introduced into the preform - such as in Microstructured Polymer Optical Fibre (MPOF) preforms. The aim of this study was

Katja Lyytikäinen; Joseph Zagari; Geoff Barton; John Canning

2006-01-01

442

Heat transfer within a microstructured polymer optical fibre preform  

Microsoft Academic Search

Preform heating is one of the most important steps in the polymer fibre fabrication process due to the potential distortion that can be introduced when exposing the structure to high temperatures. Such heating is further complicated when internal air-structures are introduced into the preform, such as in microstructured polymer optical fibre (MPOF) preforms. The aim of this study was thus

Katja Lyytikäinen; Joseph Zagari; Geoff Barton; John Canning

2004-01-01

443

Photonic band gap guiding in microstructured polymer optical fibres  

Microsoft Academic Search

Abstract:Experimental and theoretical investigation of photonic band gap guidance in an air-core microstructured polymer optical fibre will be presented . Both conventional hexagonal-symmetry band gap fibres and air-core Bragg-guiding ring structures will be discussed. ©2002 Optical Society of America

Martijn A. Van Eijkelenborg; Maryanne C. j. Large; Alexander Argyros; Ian Bassett; Joseph Zagari

444

BOLTED CONNECTIONS FOR FIBRE-REINFORCED COMPOSITE STRUCTURAL MEMBERS  

E-print Network

strength as the result of severed fibres caused by drilling bolt holes. Since the capacity of a structure of the joint. In all the tested connections a 19 mm (3/4 in) high strength bolt was used. The hole diameterBOLTED CONNECTIONS FOR FIBRE-REINFORCED COMPOSITE STRUCTURAL MEMBERS Charles N. Rosner and Sami H

445

Material property estimates from ultrasound attenuation in fibre suspensions.  

PubMed

An investigation of a new method for measuring fibre material properties from ultrasonic attenuation in a dilute suspension of synthetic fibres of uniform geometry is presented. The method is based on inversely solving an ultrasound scattering and absorption model of suspended fibres in water for the material properties of the fibres. Experimental results were obtained from three suspensions of nylon 66 fibres each with different fibre diameters. A forward solution to the model with reference material values is compared to experimental data to verify the model's behaviour. Estimates of the shear and Young's modulus, the compressional wave velocity, Poisson's ratio and loss tangent from nylon 66 fibres are compared to data available from other sources. Experimental data confirms that the model successfully predicts that the resonance features in the frequency response of the attenuation are a function of diameter. Consistent estimated values for the compressional wave velocity and the Poisson's ratio were found to be difficult to obtain but in combination gave values of shear modulus within previously reported values and with low sensitivity to noise. Young's modulus was underestimated by 54% but was consistent and had low sensitivity to noise. The underestimation is believed to be caused by the assumption of isotropic material used in the model. Additional tests on isotropic fibre would confirm this. Further analysis of the model sensitivity and the reasons for the resonance features are required. PMID:19157476

Aitomäki, Yvonne; Löfqvist, Torbjörn

2009-05-01

446

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

447

Reduction of Dispersion Induced Distortions in Radio over Fibre links  

Microsoft Academic Search

The application of microwave \\/ millimeter-wave optical links for future mobile broadband services is limited by the dispersion of the fibre. We present an approach to reduce the chromatic dispersion-induced distortions in optical links carrying combined baseband and microwave signals. This new method is based on the interplay of intensity dependent phase modulation in semiconductor optical amplifiers (SOAs) and fibre

Eszter Udvary; Tibor Berceli; Marek Chacinski; Richard Schatz; Pierre-Yves Fonjallaz

2008-01-01

448

Critical factors on manufacturing processes of natural fibre composites  

Microsoft Academic Search

Elevated environmental awareness of the general public in reducing carbon footprints and the use non-naturally decomposed solid wastes has resulted in an increasing use of natural materials, biodegradable and recyclable polymers and their composites for a wide range of engineering applications. The properties of natural fibre reinforced polymer composites are generally governed by the pre-treated process of fibre and the

Mei-po Ho; Hao Wang; Joong-Hee Lee; Chun-kit Ho; Kin-tak Lau; Jinsong Leng; David Hui

449

Microfoaming of flax and wood fibre reinforced polypropylene composites  

Microsoft Academic Search

Natural and wood fibre reinforced plastics as a relatively new group of environmental friendly materials have been extensively applied in interior, building applications and in the automobile industry. Among others, natural and wood fibre reinforced foamed polymer materials are of high significance because of the possibility of their reducing the density of automotive components which have a cellular structure. However,

Andrzej K. Bledzki; Wenyang Zhang; Omar Faruk

2005-01-01

450

Mutations in TPM2 and congenital fibre type disproportion.  

PubMed

The main diagnostic feature of congenital fibre type disproportion is that type 1 fibres are consistently smaller than type 2 fibres in the absence of other histological abnormalities. Mutations in the TPM3, RYR1 and ACTA1 genes are the most common established genetic causes. There has been one previous report of congenital fibre type disproportion due to a mutation in TPM2, although some atypical histological features were present. We present two cases in which novel de novo missense mutations in TPM2 are associated with marked fibre size disproportion. The finding of typical histological changes of congenital fibre type disproportion in association with a p.Ser61Pro mutation confirms that TPM2 can cause typical congenital fibre type disproportion. Although not seen on light microscopy studies, protein inclusions typical of small 'caps' were found on electron microscopy in a second patient with a p.Ala155Val mutation in TPM2. This case emphasises the importance of electron microscopy in patients with presumed congenital fibre type disproportion, to exclude the presence of caps, nemaline bodies or minicores, which, if present, may be very helpful in guiding genetic analysis. PMID:22832343

Clarke, Nigel F; Waddell, Leigh B; Sie, Lilian T L; van Bon, Bregje W M; McLean, Catriona; Clark, Damian; Kornberg, Andrew; Lammens, Martin; North, Kathryn N

2012-11-01

451

Numerical simulation of incoherent optical wave propagation in nonlinear fibres  

E-print Network

nonlinear effects (such as Kerr effect, four waves mixing, Raman effect) could behave very differentlyNumerical simulation of incoherent optical wave propagation in nonlinear fibres A. Fernandez1,2 , S such as Kerr effect, four waves mixing, Raman effect, for 3 different pulsed fibre laser sources (100 ns

Boyer, Edmond

452

Fibre Based Modeling of Wood Dynamics and Fracture  

E-print Network

Fibre Based Modeling of Wood Dynamics and Fracture by Sean Meiji Sutherland B.Sc., The University for the simulation of the dynamics and fracturing char- acteristics of wood, specifically its anisotropic behaviour bundles of fibres. Additionally, we describe the conditions under which fracture occurs in the material

Bridson, Robert

453

Semiconductor disk laser-pumped subpicosecond holmium fibre laser  

SciTech Connect

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

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

2012-01-31

454

Electron beam irradiation in natural fibres reinforced polymers (NFRP)  

Microsoft Academic Search

This study focuses on the electric charge motion in unsatured polyester and epoxy composites reinforced by natural fibres of Alfa type, treated by different coupling agents. The electric charging phenomenon is studied by scanning electron microscopy mirror effect (SEMME) coupled with the induced current method (ICM). Previously, using the same approach, glass fibre reinforced epoxy (GFRE) was studied to correlate

B. Kechaou; M. Salvia; Z. Fakhfakh; D. Juvé; S. Boufi; A. Kallel; D. Tréheux

2008-01-01

455

The Giant Myelinated Nerve Fibres of the Prawn  

Microsoft Academic Search

Evidence is given that the median and lateral longitudinal giant myelinated fibres in the central nervous system of the prawn Leander serratus are syncitial structures, each formed by the fusion of the processes of many segmental nerve cells. Septa are found at intervals in the axoplasm of the median fibres, but they never completely transect it. They are probably relics

William Holmes

1942-01-01

456

Development of tailor-made silica fibres for TL dosimetry  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

457

Control of interfaces in Al-C fibre composites  

NASA Technical Reports Server (NTRS)

The interface of Al-C fiber composite was modified by coating a silver layer on the surface of carbon fibres prior to making composites, in an attempt to improve the wettability between molten aluminum and carbon fibers during infiltration. An electroless plating technique was adopted and perfected to provide a homogeneous silver coating on the carbon fiber surface. Al-C fiber composites were prepared using a liquid infiltration technique in a vacuum. It was found that silver coating promoted the wetting between aluminum and carbon fibers, particularly with polyacrylonitrile-base carbon fibers. However, due to rapid dissolution of silver in molten aluminum, it was believed that the improved infiltration was not due to the wetting behavior between molten aluminum and silver. The cleaning of the fiber surface and the preservation of the cleaned carbon surface with silver coating was considered to be the prime reason for the improved wettability. Interfacial reactions between aluminum and carbon fibers were observed. Amorphous carbon was found to react more with aluminum than graphitic carbon. This is believed to be because of the inertness of the graphitic basal planes.

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

1993-01-01

458

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 f