Sample records for fibre layer rnfl

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

    PubMed

    Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

    2014-06-01

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

  2. Correlation between retinal nerve fibre layer thickness and optic nerve head size: an optical coherence tomography study

    Microsoft Academic Search

    G Savini; M Zanini; V Carelli; A A Sadun; F N Ross-Cisneros; P Barboni

    2005-01-01

    Aim: To investigate the correlation between retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) size in normal white subjects by means of optical coherence tomography (OCT).Methods: 54 eyes of 54 healthy subjects aged between 15 and 54 underwent peripapillary RNFL thickness measurement by a series of three circular scans with a 3.4 mm diameter (Stratus OCT, RNFL

  3. Laser scanning tomography of localised nerve fibre layer defects

    Microsoft Academic Search

    Reinhard O W Burk; Anja Tuulonen; P Juhani Airaksinen

    1998-01-01

    AIMSRetinal nerve fibre layer photography is a well established method to qualitatively document early structural changes which might be induced by primary open angle glaucoma. The aim was to analyse localised retinal nerve fibre layer (RNFL) defects in a new quantitative way with respect to surface topography, defect width, and surface reflectivity by means of the technique of confocal scanning

  4. Relation between size of optic disc and thickness of retinal nerve fibre layer in normal subjects

    Microsoft Academic Search

    Shigeo Funaki; Motohiro Shirakashi; Haruki Abe

    1998-01-01

    AIMSTo evaluate the relation between the optic disc size and the thickness of the peripapillary retinal nerve fibre layer (RNFL) in normal Japanese subjects by means of scanning laser polarimetry.METHODSScanning laser polarimetry was performed in 60 normal subjects. One eye of each subject was randomly selected for study. Using a scanning laser polarimeter, the integral of RNFL thickness was measured

  5. Scanning laser polarimetry of the retinal nerve fibre layer in primary open angle and capsular glaucoma

    Microsoft Academic Search

    Gábor Holló; Ildikó Süveges; Attila Nagymihály; Péter Vargha

    1997-01-01

    AIMSTo evaluate the clinical value of scanning laser polarimetry with the nerve fibre analyser type II in primary open angle glaucoma (POAG) and capsular glaucoma.METHODSScanning laser polarimetry was performed on one eye of 30 patients suffering from POAG, 25 patients suffering from capsular glaucoma, and on 35 healthy control subjects. The retinal nerve fibre layer (RNFL) thickness values were compared

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

    PubMed Central

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

    2013-01-01

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

  7. 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

    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

    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

  8. Peripapillary retinal nerve fibre layer thickness in highly myopic Caucasians as measured by Stratus optical coherence tomography

    Microsoft Academic Search

    S A Vernon; A P Rotchford; A Negi; S Ryatt; C Tattersal

    2008-01-01

    Aims:To assess peripapillary retinal nerve fibre layer (RNFL) thickness distribution in a group of non-glaucomatous Caucasian subjects with a high degree of myopia and to evaluate the relationship between RNFL thickness, both global and sectoral, and other variables including axial length and optic disc size.Method:31 eyes of 31 healthy Caucasian subjects with spherical equivalent ??6 dioptres (D) were recruited from

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

    Microsoft Academic Search

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

    2011-01-01

    Aims\\/PurposeTo determine and correlate the long-term changes in retinal nerve fibre layer (RNFL) thickness, optic nerve head (ONH) morphology, and visual fields after a single episode of acute primary angle closure (APAC).MethodsThis was a cross-sectional comparative study of patients at National University Hospital (Singapore) from 2000 to 2006 after an episode of unilateral APAC. The peripapillary and macular RNFL were

  10. Ethnic differences in optic nerve head and retinal nerve fibre layer thickness parameters in children

    Microsoft Academic Search

    Chameen Samarawickrama; Jie Jin Wang; Son C Huynh; Amy Pai; George Burlutsky; Kathryn A Rose; Paul Mitchell

    2009-01-01

    AimTo examine ethnic differences in optic nerve head and retinal nerve fibre layer (RNFL) parameters between European Caucasian and East Asian children aged 6–12 years.MethodsOf 4118 children examined in the Sydney Childhood Eye Study (incorporating the Sydney Myopia Study) from 34 randomly selected primary and 21 secondary schools during 2003–5, 3382 (82.1%) had optical coherence tomography (OCT; Zeiss Stratus) data

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

    PubMed Central

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

    2015-01-01

    Objectives. This study compared the macular and retinal nerve fibre layer (RNFL) thicknesses and optic nerves of eyes with reduced vision due to anisometropia with the contralateral healthy eyes in adults using optical coherence tomography (OCT). Methods. This cross-sectional study was conducted in Atatürk State Hospital, Sinop, Turkey. Macular and RNFL thicknesses, optic nerve disc area, cup area, and horizontal and vertical cup-to-disc ratios obtained using a NIDEK RS-3000 SLO spectral domain OCT device were compared between the amblyopic and fellow eyes in 30 adults with anisometropic amblyopia 18–55 years old who were seen in our clinic with unilateral poor vision. Results. The mean macular thickness was 266.90 ± 23.22?µm in the amblyopic eyes and 263.90 ± 22.84?µm in the fellow eyes, and the mean RNFL thickness was 111.90 ± 12.9 and 109.70 ± 9.42?µm, respectively. The two thicknesses did not differ significantly between the amblyopic and fellow eyes. There were also no significant differences between the eyes in disc area, cup area, and horizontal-vertical cup/disc ratios. Conclusion. There does not seem to be a difference in macular thickness, peripapillary RNFL, or optic disc structures between the amblyopic and fellow eyes in adults. PMID:26064676

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

    PubMed

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

    2015-01-01

    Objectives. This study compared the macular and retinal nerve fibre layer (RNFL) thicknesses and optic nerves of eyes with reduced vision due to anisometropia with the contralateral healthy eyes in adults using optical coherence tomography (OCT). Methods. This cross-sectional study was conducted in Atatürk State Hospital, Sinop, Turkey. Macular and RNFL thicknesses, optic nerve disc area, cup area, and horizontal and vertical cup-to-disc ratios obtained using a NIDEK RS-3000 SLO spectral domain OCT device were compared between the amblyopic and fellow eyes in 30 adults with anisometropic amblyopia 18-55 years old who were seen in our clinic with unilateral poor vision. Results. The mean macular thickness was 266.90 ± 23.22?µm in the amblyopic eyes and 263.90 ± 22.84?µm in the fellow eyes, and the mean RNFL thickness was 111.90 ± 12.9 and 109.70 ± 9.42?µm, respectively. The two thicknesses did not differ significantly between the amblyopic and fellow eyes. There were also no significant differences between the eyes in disc area, cup area, and horizontal-vertical cup/disc ratios. Conclusion. There does not seem to be a difference in macular thickness, peripapillary RNFL, or optic disc structures between the amblyopic and fellow eyes in adults. PMID:26064676

  13. Correlation between nerve fibre layer thickness measured with spectral domain OCT and visual field in patients with different stages of glaucoma

    Microsoft Academic Search

    Barbara Cvenkel; Alenka Šket Kontestabile

    2011-01-01

    Background  To measure retinal nerve fibre layer (RNFL) thickness with spectral-domain OCT (SD-OCT) in patients with glaucoma, and to\\u000a evaluate the correlation between visual field parameters and RNFL thickness.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Two hundred twelve subjects—55 normal, 37 with preperimetric glaucoma (PPG) and 119 with different stages of primary open\\u000a angle glaucoma (POAG) were enrolled in this study. Standard automated perimetry was performed in

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

    PubMed

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

    2015-01-01

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

  15. Correlation of Retinal Nerve Fibre Layer Thickness and Spontaneous Retinal Venous Pulsations in Glaucoma and Normal Controls

    PubMed Central

    Golzan, S. Mojtaba; Morgan, William H.; Georgevsky, Dana; Graham, Stuart L.

    2015-01-01

    Purpose To study the relationship between amplitude of spontaneous retinal venous pulsatility (SRVP) and retinal nerve fibre layer (RNFL) thickness in glaucomatous eyes, and to determine if this parameter may be a potential marker for glaucoma severity. Method 85 subjects including 50 glaucoma (21 males, 67±10 yrs) and 35 normals (16 males, 62±11 yrs) were studied. SRVP amplitude was measured using the Dynamic Vessel Analyser (DVA, Imedos, Germany) at four regions of the retina simultaneously within one disc diameter from the optic disc—temporal-superior (TS), nasal-superior (NS), temporal-inferior (TI) and nasal-inferior (NI)). This was followed by RNFL thickness measurement using spectral domain optical coherence tomography (Spectralis OCT). The correlation between SRVP amplitude and corresponding sectoral RNFL thickness was assessed by means of non-linear regression (i.e. logarithmic). Linear regression was also applied and slopes were compared using analysis of covariance (ANCOVA). Results Greater SRVP amplitude was associated with thicker RNFL. Global SRVP amplitude was significantly lower in glaucoma eyes compared with normals (p<0.0001). The correlation coefficient of the linear regression between RNFL and SRVP at TS, NS, TI and NI quadrants in the glaucoma group were r = 0.5, 0.5, 0.48, 0.62. Mean SRVP amplitude and RNFL thickness for TS, NS, TI and NI quadrants were 4.3±1.5, 3.5±1.3, 4.7±1.6, 3.1±1 ?m and 96±30, 75±22, 89±35 and 88±30 ?m, respectively. The ANCOVA test showed that the slope of linear regression between the four quadrants was not significant (p>0.05). Since the slopes are not significantly different, it is possible to calculate one slope for all the data. The pooled slope equals 10.8 (i.e. RNFL = 10.8SRVP+41). Conclusion While SRVP was present and measurable in all individuals, the amplitude of SRVP is reduced in glaucoma with increasing RNFL loss. Our findings suggest the degree of SRVP may be an additional marker for glaucoma severity. Further studies are needed to determine the mechanism of reduction in SRVP, and whether changes can predict increased risk of progression. PMID:26042791

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

    PubMed

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

    2014-12-01

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

  17. Evaluation of the retinal nerve fibre layer and ganglion cell complex thickness in pituitary macroadenomas without optic chiasmal compression.

    PubMed

    Cennamo, G; Auriemma, R S; Cardone, D; Grasso, L F S; Velotti, N; Simeoli, C; Di Somma, C; Pivonello, R; Colao, A; de Crecchio, G

    2015-06-01

    PurposeThe aim of this prospective study was to measure the thickness of the circumpapillary retinal nerve fibre layer (cpRNFL) and the ganglion cell complex (GCC) using spectral domain optical coherence tomography (SD-OCT) in a cohort of consecutive de novo patients with pituitary macroadenomas without chiasmal compression.Patients and methodsTwenty-two consecutive patients with pituitary macroadenoma without chiasmal compression (16 men, 6 women, aged 45.2±14.6 years, 43 eyes) entered the study between September 2011 and June 2013. Among them, 31.8% harboured a growth hormone-secreting pituitary adenoma, 27.3% a prolactin-secreting pituitary adenoma, 27.3% a corticotrophin-secreting pituitary adenoma, and 13.6% a non-secreting pituitary tumour. Eighteen subjects (nine females, nine males, mean age 36.47±6.37 years; 33 eyes) without pituitary adenoma, with normal ophthalmic examination, served as controls. In both patients and controls, cpRNFL and GCC thicknesses were measured by SD-OCT.ResultsPatients were significantly older (P=0.02) than controls. Best corrected visual acuity, intraocular pressure, colour fundus photography, and automatic perimetry test were within the normal range in patients and controls. Conversely, cpRNFL (P=0.009) and GCC (P<0.0001) were significantly thinner in patients than in controls. The average GCC (r=0.306, P=0.046) significantly correlated with the presence of arterial hypertension. OCT parameters did not differ significantly between patients with a tumour volume above the median and those with a tumour volume below the median.ConclusionPituitary macroadenomas, even in the absence of chiasmal compression, may induce GCC and retinal nerve fibre layer thinning. SD-OCT may have a role in the early diagnosis and management of patients with pituitary tumours. PMID:25853400

  18. Influence of the Disc–Fovea Angle on Limits of RNFL Variability and Glaucoma Discrimination

    PubMed Central

    Amini, Navid; Nowroozizadeh, Sara; Cirineo, Nila; Henry, Sharon; Chang, Ted; Chou, Tom; Coleman, Anne L.; Caprioli, Joseph; Nouri-Mahdavi, Kouros

    2014-01-01

    Purpose. To determine factors affecting the disc–fovea angle (DFA), and to test the hypotheses that adjusting for DFA improves limits of retinal nerve fiber layer (RNFL) variability in normal subjects or enhances performance of RNFL measures for glaucoma detection. Methods. Disc–fovea angle was measured on scanning laser ophthalmoscope fundus images from 170 eyes (110 normal and glaucoma subjects). The DFA measurements were repeated in 24 eyes. The relationship between DFA and various anatomic variables was explored. Main outcome measures were changes in 95% RNFL prediction limits or glaucoma discrimination after adjusting for DFA. We also explored the angle between temporal raphe and horizontal meridian in 19 eyes with nasal field defects limited to one hemifield. Results. Average mean deviation and DFA were ?0.1 (±1.2) dB and ?6.6° (±3.4°) and ?4.1 (±3.3) dB and ?7.9° (±3.9°) in the control and glaucoma groups, respectively (P < 0.001 and = 0.029). The average difference between DFA repeat measurements was 2.0° (±1.8°). Predictors for DFA were female sex (P = 0.004), smaller disc area (P = 0.006), and glaucoma diagnosis (P = 0.019). The absolute change in sectoral RNFL thickness was 6.1 (±3.9) and 4.6 (±3.1) ?m in control and glaucoma subjects, respectively. Retinal nerve fiber layer prediction limits improved in 5, 9, and 10 o'clock sectors (P < 0.02). Discrimination ability for the best-performing RNFL sector did not improve (P = 0.936). The average angle between temporal raphe and horizontal meridian was 0.8° (±0.8°). Conclusions. Disc–fovea angle measurements demonstrated fair intersession repeatability. While adjusting for DFA improved RNFL prediction limits in some sectors, it did not enhance glaucoma detection. PMID:25301880

  19. Influence of optic-disc size on parameters of retinal nerve fibre analysis as measured using GDx VCC and ECC in healthy subjects

    Microsoft Academic Search

    Hemma Resch; Gabor Deak; Clemens Vass

    2010-01-01

    BackgroundTo date, there is no knowledge on the impact of optic-disc size on the retinal nerve fibre layer (RNFL) as measured with GDx VCC or GDx ECC. Since the size of the optic disc is not taken into account for the analyses carried out by the GDx, it might affect sensitivity in large optic discs and specificity in small ones.MethodsTopographic

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

    Microsoft Academic Search

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

    2000-01-01

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

  1. On the distribution of pore heights in layered random fibre networks

    E-print Network

    Dodson, C.T.J.

    On the distribution of pore heights in layered random fibre networks C.T.J. Dodson Department research meeting1 , discussion of measurements of internal pore heights from cross sections of paper by K of Corte and Kallmes [1, 2]; it provides the analytic distribution for internal and surface pore heights

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

    PubMed Central

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

    2014-01-01

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

  3. Selenium adsorption and speciation with Mg-FeCO? layered double hydroxides loaded cellulose fibre.

    PubMed

    Chen, Ming-Li; An, Myog-Il

    2012-06-15

    A novel adsorbent was developed by coating Mg-FeCO(3) layered double hydroxides (LDHs) on cellulose fibre. The LDHs take up significant amount of selenite and selenate in a wide pH range with similar sorption capacities (pH 3.8-8.0 for selenite and pH 5.8-7.0 for selenate). A mini-column packed with Mg-FeCO(3) LDHs layer coated cellulose fibre particles was incorporated into a sequential injection system for uptake of selenite at pH 6.0. The retained selenite was afterwards collected with 70 ? L of 0.8%(m/v) NaOH as eluent, followed by hydride generation and atomic fluorescence spectrometric detection. Total inorganic selenium was adsorbed at pH 6.0 by the LDHs-cellulose fibre mini-column after selenate was pre-reduced to selenite by 2.0 mol L(-1) HCl at 80°C, and selenium speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 13.3 was derived with a detection limit of 11 ng L(-1) within a linear range of 0.04-4.0 ?g L(-1). A relative standard deviation (RSD) of 3.3% (0.5 ?g L(-1), n=11) was achieved. The procedure was validated by analyzing selenium in a certified reference material GBW 10010 (rice), and speciation of inorganic selenium in natural water samples. PMID:22748552

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

    PubMed

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

    2014-04-01

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

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

    SciTech Connect

    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

    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.

  6. Ganglion cell layer analysis unmasks axonal loss in anterior optic neuritis.

    PubMed

    Rebolleda, Gema; de Dompablo, Elisabet; Muñoz-Negrete, Francisco J

    2015-06-01

    Optical coherence tomography is a valuable tool for evaluating patients with neuro-ophthalmic disorders. In the acute phase of anterior optic neuritis (ON), peripapillary retinal nerve fiber layer (pRNFL) measurements can underestimate the amount of damage as axonal swelling could mask the true degree of RNFL loss. Contrary to pRNFL evaluation, we hypothesize that macular ganglion cell layer analysis could detect true neuronal loss before swelling resolution in anterior ON. We describe 4 patients with anterior ON in whom ganglion cell layer and inner plexiform layer (GCIPL) thinning was detected earlier than pRNFL loss. GCIPL analysis may provide more accurate information than pRNFL thickness and serve as an early structural indicator of irreversible neuronal loss. PMID:25534475

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

    E-print Network

    Paris-Sud XI, Université de

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

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

    Microsoft Academic Search

    Alain Schmutz; Titus Jenny; Nikolaus Amrhein; Ulrich Ryser

    1993-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

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

    PubMed Central

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

    2014-01-01

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

  11. Retinal nerve fiber layer thickness in myopic, emmetropic, and hyperopic children.

    PubMed

    Lee, Jacky W Y; Yau, Gordon S K; Woo, Tiffany T Y; Yick, Doris W F; Tam, Victor T Y; Lai, Jimmy S M

    2015-03-01

    The purpose of this study was to investigate the peripapillary retinal nerve fiber layer (RNFL) thickness in myopic, emmetropic, and hyperopic children using optical coherence tomography. Two-hundred one right eyes of subjects aged 4 to 18 years were divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<-1.0?D), emmetropes (?-1.0 to ?+1.0?D), and hyperopes (>+1.0?D). The RNFL was correlated with age, spherical equivalent, and axial length. The RNFL was compared between the 3 groups before and after age adjustment. The RNFL was thickest in the hyperopic group (107.2?±?10.13??m, n?=?73), followed by the emmetropic group (102.5?±?9.2??m, n?=?61), and then the myopic group (95.7?±?10.3, n?=?67) (all P?RNFL than the other 2 groups (all P?RNFL thickness difference between the emmetropic and hyperopic groups (P?>?0.05). A thinner RNFL was associated with an older age (r?=?-0.4, P?RNFL in hyperopic and emmetropic children was attributed to their younger age as compared with their myopic counterparts. When adjusted for age, only myopia was associated with a thinner RNFL, with emmetropic and hyperopic children having equal RNFL thicknesses. Advancing age, a more myopic spherical equivalent, and a longer axial length were associated with a thinner RNFL in children. PMID:25816043

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  15. Retinal nerve fiber layer thickness in human eyes

    Microsoft Academic Search

    Albert Dichtl; Jost B. Jonas; Gottfried O. H. Naumann

    1999-01-01

    · Background: A study was carried out to measure the thickness of the retinal nerve fiber layer (RNFL) at the optic disc border.\\u000a · Methods: RNFL thickness at the optic disc border was histomorphometrically measured on histological sections of 22 human\\u000a eyes with normal optic nerves and 21 human eyes with absolute secondary angle-closure glaucoma. For three eyes with normal

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

    PubMed

    Kalmendal, R; Wall, H

    2012-01-01

    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 condition, and was accompanied by improved FCR compared with controls. Feeding the high oil and fibre diet tended to improve FCR compared with the control diet. 3. The dry matter of faeces was reduced in both treatments compared with controls. Foot pad cleanliness and the proportion of dirty eggs were negatively affected by the high oil and fibre diet. Foot health was superior in LB compared to LSL. 4. LB used the outdoor hen-runs more than LSL, but LSL consumed more litter indoors. Fewer LB hens fed on the control feed were recorded in the outdoor hen-runs. Supplemental roughage tended to decrease litter consumption. 5. In conclusion, supplemental roughage reduced vent injuries and was correlated with foraging activities. Feeding 260 g/kg sunflower cake negatively affected hygiene in aviary hens. Sunflower cake is nevertheless a promising alternative feedstuff to fulfil the protein requirement in organic layers. PMID:22646779

  17. Evaluation of the effect of intravitreal ranibizumab injections in patients with neovascular age related macular degeneration on retinal nerve fiber layer thickness using optical coherence tomography

    PubMed Central

    El-Ashry, Mohamed F; Lascaratos, Gerassimos; Dhillon, Baljean

    2015-01-01

    Purpose To evaluate the effect of repeated intravitreal ranibizumab injections for neovascular age related macular degeneration (nAMD) on the retinal nerve fiber layer (RNFL) thickness using optical coherence tomography. Design A prospective observational cohort study of patients with nAMD. Methods Thirty eyes of 30 patients with nAMD were selected. All patients received three ranibizumab injections and underwent scans using the fast RNFL thickness protocol (Stratus optical coherence tomography) before starting the first injection and 1 month after the third injection. The RNFL thickness measurements prior to the injections and after the third injection were used for the analysis. We also evaluated the effect of the lens status as well as the type of choroidal neovascular membrane on RNFL thickness measurements pre- and post-injection. Pre- and post-injection average and individual quadrant RNFL thickness were measured and statistically analyzed. Results The mean (± standard deviation) pre-injection RNFL thickness was 90.8±18. The mean (± standard deviation) post-injection RNFL thickness was 91.03±15. The pre- and post-injection values of the mean RNFL thickness were not statistically significant. Likewise, the pre- and post-injection values for RNFL thickness in the different quadrants were not statistically significant. There was no statistical significance for the lens status or the type of choroidal neovascular membrane on the RNFL thickness. Conclusion Repeated ranibizumab injections in nAMD appear to have no harmful effect on the RNFL thickness in the short term, in spite of the proven neurotrophic effect of vascular endothelial growth factor. Nevertheless, the safety profile of ranibizumab injections in nAMD needs to be further evaluated in a large multicenter trial with special emphasis on the long-term effects on the retina and optic nerve.

  18. Retinal Nerve Fiber Layer Thickness. The Beijing Eye Study 2011

    PubMed Central

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

    2013-01-01

    Purpose To measure retinal nerve fiber layer (RNFL) thickness in a population-based setting. Methods In the population-based Beijing Eye Study 2011 with 3468 individuals, RNFL thickness was measured in a subgroup of 1654 (47.7%) study participants by spectral domain optical coherence tomography (iVue SD-OCT). Results Mean RNFL thickness was significantly (P<0.001) higher in the inferior sector (131.4±20.6 µm) than the superior sector (126.1±19.1 µm), where it was higher than in the temporal sector (79.8±12.2 µm;P<0.001), where it was higher than in the nasal sector (75.1±12.6 µm;P<0.001). In multivariate analysis, mean global RNFL thickness (103.2±12.6 µm) increased significantly with younger age (standardized correlation coefficient beta:?0.30;P<0.001), larger neuroretinal rim area (beta:0.26;P<0.001), shorter axial length (beta:?0.21;P<0.001), thicker subfoveal choroidal thickness (beta:0.15;P<0.001), larger optic disc area (beta:0.10;P<0.001), less refractive lens power (beta:0.10;P<0.001), flatter anterior cornea (beta:0.07;P?=?0.01) and female gender (beta:0.05;P?=?0.03). In this population with an age of 50+ years, the age-related decline in RNFL thickness was 0.5 µm per year of life or 0.36% of an original RNFL thickness of 137 µm at baseline of the study at 50 years of age. Mean global RNFL thickness decreased by 2.4 µm for each mm enlargement of axial length. Conclusions The RNFL profile shows a double hump configuration with the thickest part in the inferior sector, followed by the superior sector, temporal sector and nasal sector. Factors influencing global RNFL thickness were younger age, larger neuroretinal rim, shorter axial length, thicker subfoveal choroid, larger optic disc, less refractive lens power, flatter anterior cornea and female gender. Beyond an age of 50+ years, RNFL decreased by about 0.3% per year of life at an age of 50+ years and by 2.4 µm per mm of axial elongation. These findings may be of interest for the knowledge of the normal anatomy of the eye and may be of help to diagnose diseases affecting the RNFL. PMID:23826129

  19. Visualization of localized retinal nerve fiber layer defects with the GDx with individualized and with fixed compensation of anterior segment birefringence

    Microsoft Academic Search

    Nicolaas J Reus; Thomas P Colen; Hans G Lemij

    2003-01-01

    PurposeTo compare the visualization of localized retinal nerve fiber layer (RNFL) defects in GDx images with fixed and with individualized compensation of anterior segment birefringence (FC and IC, respectively) with their visualization in red-free fundus photographs.

  20. 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

  1. Topographic Differences in the Age-Related Changes in the Retinal Nerve Fiber Layer of Normal Eyes Measured by Stratus™ Optical Coherence Tomography

    PubMed Central

    Feuer, William J.; Budenz, Donald L.; Anderson, Douglas R.; Cantor, Louis; Greenfield, David S.; Savell, Jonathan; Schuman, Joel S.; Varma, Rohit

    2010-01-01

    Purpose To determine whether there are regional differences in the age-related changes in peripapillary retinal nerve fiber layer thickness as measured by time-domain optical coherence tomography (OCT). Methods Fast peripapillary RNFL scans obtained with the Stratus™ time-domain OCT with nominal diameter of 3.46 mm centered on the optic disc were performed on 425 normal subjects over a wide age range. One eye was randomly selected for scanning or analysis. Average RNFL-, clock hour-, and quadrant-specific rates of RNFL thickness change were calculated and compared. Results The 425 study participants ranged in age from 18 to 85 years with mean (±SD) of 46 (±15) years. The mean (±SD) average measured RNFL thickness was 104.7 (±10.8) micrometers (?m). The decline in the average RNFL thickness was 2.4 ?m per decade of age. Changes in RNFL thickness per decade of age ranged from -5.4 (p<0.001) at clock hour 12 to -0.9 (p=0.28) at clock hour 6. Similarly, the rate of thickness change per decade of age in the superior quadrant was -4.3 (p<0.001) versus -1.5 (p=0.006) in the inferior quadrant. The slopes of thinning superiorly and inferiorly were highly significantly different (p=0.001). Conclusions The age-related decline in normal RNFL measurements does not occur at equal rates around the disc and occurs mainly superiorly. PMID:20577113

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

    PubMed Central

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

    2015-01-01

    Purpose: Aim of the present study was to evaluate whether there is a correlation between retinal blood vessel density (RVD) and the peripapillary retinal nerve fiber layer (RNFL) thickness profile. Methods: RNFL thickness of 106 healthy subjects was measured using scanning laser polarimetry, GDx variable corneal compensation (VCC), and GDx enhanced corneal compensation (ECC). A proprietary software was developed in MATLAB to measure the peripapillary retinal vessels using scanning laser ophthalmoscopy fundus images, centered on the optic disc measured by Cirrus spectral domain optical coherence tomography. The individual retinal vessel positions and thickness values were integrated in a 64-sector RVD profile and intrasubject and intersubject correlations were calculated. Results: The mean R value±SD for intrasubject correlation between RVD and RNFL thickness measured with GDx VCC and GDx ECC was 0.714±0.157 and 0.629±0.140, with 105 of 106 subjects presenting significant correlations. In the intersubject linear regression analysis for GDx VCC, 33 of 64 (52%) sectors presented a significant Pearson correlation coefficient between RNFL thickness and RVD values, with a mean R value of 0.187±0.135 (P<0.05). Conclusions: Peripapillary RNFL thickness profiles correlate with the RVD over 50% of the sectors and might explain up to 26% of the interindividual variance of the peripapillary RNFL thickness values as measured with GDx VCC. To our opinion, taking into account RVD might reduce interindividual variation in peripapillary RNFL thickness profiles measured with scanning laser polarimetry. PMID:25719231

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

    PubMed Central

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

    2014-01-01

    Background To evaluate peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous Nepalese eyes using spectral domain optical coherence tomography (SD-OCT) and study its relationship with visual field sensitivity. Methods A total of 120 eyes comprising primary open angle glaucoma (POAG), glaucoma suspects (GS), normal tension glaucoma (NTG) and healthy subjects (n = 30 cases in each group) underwent a complete ophthalmic examination, including optic nerve head (ONH) evaluation and standard automated perimetry (SAP). RNFL thickness measurements around the optic disk were taken with circular spectral domain optical coherence tomography (SD-OCT) scans. Analysis of variance (ANOVA) was used for comparison of RNFL parameters among various study groups. The relationship of RNFL parameters with visual field (VF) global indices was evaluated with regression analysis. Results The mean pRNFL thickness was significantly less in the POAG (64.30 ± 14.45 ?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

  4. Retinal nerve fiber layer thickness is associated with episodic memory deficit in mild cognitive impairment patients.

    PubMed

    Shen, Yuan; Liu, Liang; Cheng, Yan; Feng, Wei; Shi, Zhongyong; Zhu, Yikang; Wu, Wenyuan; Li, Chunbo

    2014-03-01

    Changes in retinal nerve fiber layer (RNFL) thickness have been reported in patients with mild cognitive impairment (MCI), the pre-dementia stage of Alzheimer's disease (AD). However, whether RNFL thickness is associated with specific cognitive impairment of MCI patients remains unknown. Therefore, we set out to investigate the potential association between RNFL thickness and episodic memory in MCI patients. Seventy five older adults (mean age 74 ± 3 years, 55% men) were included in the study. Fifty-two participants had normal cognition (NC), and 23 participants were diagnosed with MCI. RNFL thickness was obtained by optical coherence tomography measurement. Cognitive function was evaluated by the Repeatable Battery for the Assessment of Neuropsychological Status on the same day of the optical examination. We found that nasal quadrant RNFL thickness was positively associated with episodic memory scores in the participants with normal cognition: word list learning (r=0.392, p=0.004) and story recall (r=0.307, p=0.027). In the participants with MCI, however, the inferior quadrant RNFL thickness was inversely associated with the episodic memory score: word list learning (r=-0.652, p=0.001), story memory (r=-0.429, p=0.041), and story recall (r=-0.502, p=0.015,). The findings from this pilot study suggest that the inferior quadrant RNFL thickness was associated with specific episodic memory in MCI patients and could serve as a biomarker of MCI and AD. These findings would promote more studies to determine the potential application of RNFL as an AD biomarker. PMID:24484274

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

    PubMed Central

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

    2015-01-01

    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

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

    PubMed

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

    2014-09-01

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

  7. Myelinated Nerve Fibre, Myelin

    Microsoft Academic Search

    Margit Pavelka; Jürgen Roth

    \\u000a Nerve fibres designed for particularly rapid and efficient conduction of action potentials are equipped with a myelin sheath,\\u000a a lipid-enriched layer, produced by specialised glial cells, the oligodendrocytes in the central nervous system, and the Schwann\\u000a cells in the peripheral nervous system. The myelin sheath isolates the axon from the surrounding compartments. It reduces\\u000a the current flow across the axonal

  8. Optical fibre Optical fibre OPTICAL FIBRE NANOWIRE SENSORS AND APPLICATIONS

    E-print Network

    Quartly, Graham

    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] and their extraordinary optical and mechanical properties, which include, amongst others: - biocompatibility: OFNs show

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed Central

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

    2014-01-01

    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

  11. Retinal Nerve Fiber Layer Atrophy Is Associated with Visual Field Loss over Time in Glaucoma Suspect and Glaucomatous Eyes

    PubMed Central

    Sehi, Mitra; Zhang, Xinbo; Greenfield, David S.; Chung, YunSuk; Wollstein, Gadi; Francis, Brian A.; Schuman, Joel S.; Varma, Rohit; Huang, David

    2012-01-01

    Purpose To prospectively compare detection of progressive retinal nerve fiber layer thickness (RNFL) atrophy identified using time-domain optical coherence tomography (OCT) with visual field progression using standard automated perimetry (SAP) in glaucoma suspect and preperimetric glaucoma and perimetric glaucoma patients. Design Prospective longitudinal clinical trial Methods Eligible eyes with ?2 years of follow-up underwent time-domain OCT and SAP every 6 months. The occurrence of visual field progression was defined as the first follow-up visit reaching a significant (p<0.05) negative visual field index (VFI) slope over time. RNFL progression/improvement was defined as a significant negative/positive slope over time. Specificity was defined as the number of eyes with neither progression nor improvement, divided by the number of eyes without progression. Cox proportional hazard ratios (HR) were calculated using univariate and multivariate models with RNFL loss as a time-dependent covariate. Results 310 glaucoma suspect and preperimetric glaucoma, and 177 perimetric glaucoma eyes were included. Eighty-nine eyes showed visual field progression and 101 eyes showed RNFL progression. The average time to detect visual field progression in those 89 eyes was 35±13 months; and to detect RNFL progression in those 101 eyes was 36±13 months. In multivariate Cox models, average and superior RNFL losses were associated with subsequent VFI loss in the entire cohort (every 10?m loss, HR=1.38,p=0.03; HR=1.20, p=0.01 respectively). Among the entire cohort of 487 eyes, 42 had significant VFI improvement and 55 had significant RNFL improvement (specificity 91.4% and 88.7%, respectively). Conclusion Structural progression is associated with functional progression in glaucoma suspect and glaucomatous eyes. Average and superior RNFL thickness may predict subsequent SAP loss. PMID:23036570

  12. Lightweight carbon fibre rods and truss structures

    Microsoft Academic Search

    R Schütze

    1997-01-01

    Lightweight carbon fibre rods and truss structures are of growing importance for modern transportation technologies. The struts of such frameworks are commonly designed as fibre-wound CFRP tubes. Here CFRP sandwich rods are an advantageous alternative. They have a lightweight foam core covered by a relative thin layer of composite material. In many real applications, however, the superior mechanical properties of

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

    Microsoft Academic Search

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

    2010-01-01

    In recent years, sugar palm fibre has been found to have great potential to be used as fibre reinforcement in polymer matrix composites. This research investigates the mechanical properties of woven glass\\/sugar palm fibres reinforced unsaturated polyester hybrid composite. The composite specimens made of different layer of fibres such as strand mat, natural and hand woven of sugar palm fibres.

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

    PubMed Central

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

    2015-01-01

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

  15. The Correlation of Retinal Nerve Fiber Layer Thickness With Blood Pressure in a Chinese Hypertensive Population.

    PubMed

    Gangwani, Rita A; Lee, Jacky W Y; Mo, H Y; Sum, Rita; Kwong, Alfred S K; Wang, Jenny H L; Tsui, Wendy W S; Chan, Jonathan C H; Lai, Jimmy S M

    2015-06-01

    To investigate the association between retinal nerve fiber layer (RNFL) thickness and blood pressure (BP) in subjects with systemic hypertension.Subjects with systemic hypertension on anti-hypertensive medications were screened by fundus photography and referred for glaucoma work-up if there was enlarged vertical cup-to-disc (VCDR) ratio ?0.6, VCDR asymmetry ?0.2, or optic disc hemorrhage. Workup included a complete ophthalmological examination, Humphrey visual field test, and RNFL thickness measurement by optical coherence tomography. The intraocular pressure (IOP) and RNFL thicknesses (global and quadrant) were averaged from both eyes and the means were correlated with: the systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) using Pearson correlation.Among 4000 screened hypertensive subjects, 133 were referred for glaucoma workup and 110 completed the workup. Of the 4000 screened subjects, 1.3% had glaucoma (0.9% had normal tension glaucoma [NTG], 0.2% had primary open angle glaucoma, and 0.2% had primary angle closure glaucoma), whereas 0.3% were NTG suspects. The SBP was negatively correlated with the mean superior RNFL thickness (P?=?0.01). The DBP was negatively correlated with the mean global (P?=?0.03), superior (P?=?0.02), and nasal (P?=?0.003) RNFL thickness. The MAP was negatively correlated with the mean global (P?=?0.01), superior (P?=?0.002), and nasal (P?=?0.004) RNFL thickness while positively correlated with the mean IOP (P?=?0.02).In medically treated hypertensive subjects, glaucoma was present in 1.3%, with NTG being most prevalent. MAP control may help with IOP lowering and RNFL preservation, although future prospective studies will be needed. PMID:26061324

  16. Multimaterial Piezoelectric Fibres

    E-print Network

    Egusa, S.

    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 ...

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

    PubMed Central

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

    2013-01-01

    AIM To assess the effect of myopia on the thickness of retinal nerve fiber layer (RNFL) measured by 3D optical coherence tomography (3D-OCT) in a group of nonglaucomatous Chinese subjects. METHODS Two hundred and fifty-eight eyes of 258 healthy Chinese myopic individuals were recruited and four groups were classified according to their spherical equivalent (SE): low myopia (n=42, -0.5DRNFL thickness profile including superior, nasal, inferior and temporal quadrant and each of the 12 clock-hour thicknesses were measured by 3D-OCT. The RNFL thicknesses among four sample groups were performed by one-way analysis of variance (one-way ANOVA) and least significant difference test (LSD test). Correlations between RNFL thickness and axial length/spherical equivalent were performed by linear regression analysis. RESULTS The overall RNFL parameters shown significant differences between groups excluding 7, 9, 10, 11 o'clock hour thickness. The RNFL thickness of superior, nasal, inferior, average and 1, 2, 3, 4, 5, 6, 12 o'clock sectors were decreased with the increasing axial length and higher degree of myopia. In contrast, as axial length and the degree of myopia increased, the temporal and 8, 9 o'clock sectors thicknesses were increased. A considerable proportion of myopic eyes were classified as outside the normal limits. Six o'clock was the most notable of the total, which 43.4% were outside the normal limits. CONCLUSION On the measurement of RNFL, the characteristics of RNFL with the change of the degree of myopia were observed. As the degree of myopia increases, the RNFL thickness measured by 3D-OCT including the average and superior, nasal, inferior sectors decreases. And due to the change of RNFL thickness, it should be considered when using OCT to access for the damage of glaucoma especially people with myopia. PMID:24195037

  18. Peripapillary Retinal Nerve Fiber Layer Thickness Measurement by Three-Dimensional Optical Coherence Tomography in a Normal Population

    PubMed Central

    Pakravan, Mohammad; Aramesh, Shila; Yazdani, Shahin; Yaseri, Mehdi; Sedigh-Rahimabadi, Massih

    2009-01-01

    Purpose To determine peripapillary retinal nerve fiber layer (RNFL) thickness values by three-dimensional optical coherence tomography (3D-OCT) in a normal Iranian population and to evaluate the concordance of these measurements with those obtained by the second generation of optical coherence tomography (OCT II). Methods In a cross-sectional observational study, 96 normal Iranian subjects 20-53 years old were enrolled. Peripapillary RNFL thickness in one randomly selected eye of each subject was measured by 3D-OCT and also by OCT II. Standard achromatic perimetry, corneal pachymetry and A-scan ultrasonographic biometry were also performed. Other study variables included age, gender, laterality (right versus left eye), refractive error, corneal diameter and disc area. Results Mean peripapillary RNFL thickness measured by 3D-OCT (75.50±8.38) ?m was significantly less than that measured by OCT II (144.10±33.32 ?m) (P<0.001). Using 3DOCT, no significant difference in peripapillary RNFL thickness was observed by gender (P=0.90) or laterality (P=0.17); RNFL thickness had no correlation with age (P=0.95), axial length (P=0.32), spherical equivalent refractive error (P=0.21), central corneal thickness (P=0.66) and disc area (P=0.31). However, a positive correlation was found between peripapillary RNFL thickness and corneal diameter (P=0.03). Conclusion 3D-OCT seems to yield lower RNFL thickness values as compared to OCT II. It seems advisable to obtain separate baseline measurements when using different generations of OCT machines. PMID:23330060

  19. Fibre-reinforced materials.

    PubMed

    Brown, D

    2000-11-01

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

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

    Microsoft Academic Search

    Yasufumi Fukuma; Yoshio Okazaki; Takashi Shioiri; Yukio Iida; Hisao Kikuta; Motohiro Shirakashi; Kiyoshi Yaoeda; Haruki Abe; Kazuhiko Ohnuma

    2011-01-01

    To measure the retardation distribution of the optic retinal nerve fiber layer (RNFL) from a single image, we have developed a new polarization analysis system that is able to detect the Stokes vector using a fundus camera. The polarization analysis system is constructed with a CCD area image sensor, a linear polarizing plate, a microphase plate array, and a circularly

  1. Asymmetry in Intraocular Pressure and Retinal Nerve Fiber Layer Thickness in Normal-Tension Glaucoma

    Microsoft Academic Search

    Konstantin Gugleta; Selim Orgül; Josef Flammer

    1999-01-01

    The etiology of glaucoma is most probably multifactorial. This study intended to investigate the asymmetry in intraocular pressure (IOP) and that in retinal nerve fiber layer (RNFL) thickness in normal-tension glaucoma patients. Two diurnal tension curves, obtained within 3 months and counting at least five IOP readings each, including an early morning IOP measurement upon awaking, were obtained in 15

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

    PubMed

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

    2015-04-01

    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

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

    PubMed Central

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

    2010-01-01

    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

  4. Ganglion Cell Layer–Inner Plexiform Layer Thickness and Vision Loss in Young Children With Optic Pathway Gliomas

    PubMed Central

    Gu, Sherry; Glaug, Natalie; Cnaan, Avital; Packer, Roger J.; Avery, Robert A.

    2014-01-01

    Purpose. To determine if measures of macular ganglion cell layer–inner plexiform layer (GCL-IPL) thickness can discriminate between children with and without vision loss (visual acuity or field) from their optic pathway glioma (OPG) using spectral-domain optical coherence tomography (SD-OCT). Methods. Children with OPGs (sporadic or secondary to neurofibromatosis type 1) enrolled in a prospective study of SD-OCT were included if they were cooperative for vision testing and macular SD-OCT images were acquired. Manual segmentation of the macular GCL-IPL and macular retinal nerve fiber layer (RNFL) was performed using elliptical annuli with diameters of 1.5, 3.0, and 4.5 mm. Logistic regression assessed the ability of GCL-IPL and RNFL thickness measures (micrometers) to differentiate between the normal and abnormal vision groups. Results. Forty-seven study eyes (normal vision = 31, abnormal vision = 16) from 26 children with OPGs were included. Median age was 5.3 years (range, 2.5–12.8). Thickness of all GCL-IPL and RNFL quadrants differed between the normal and abnormal vision groups (P < 0.01). All GCL-IPL measures demonstrated excellent discrimination between groups (area under the curve [AUC] > 0.90 for all diameters). Using the lower fifth percentile threshold, the number of abnormal GCL-IPL inner macula (3.0 mm) quadrants achieved the highest AUC (0.989) and was greater than the macula RNFL AUCs (P < 0.05). Conclusions. Decreased GCL-IPL thickness (layer–inner plexiform layer thickness could be used as a surrogate marker of vision in children with OPGs. PMID:24519429

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

    Microsoft Academic Search

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

    1994-01-01

    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

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

    PubMed Central

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

    2014-01-01

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

  7. Fibre optics: Forty years later

    SciTech Connect

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

    2010-01-31

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

  8. Interpretation of the potential fields generated in the cerebellar cortex by a mossy fibre volley

    Microsoft Academic Search

    J. C. Eccles; K. Sasaki; P. Strata

    1967-01-01

    1.Potential fields and unitary spikes in the cat cerebellar cortex were generated specifically by mossy fibre volleys and recorded by means of microelectrodes. The mossy fibres were excited by trans-folial (T. F.) stimulation which was compared with juxtafastigial (J.F.) stimulation. Both were conditioned by local stimuli of parallel fibres.2.In the granular layer, an incoming mossy fibre volley evoked a small

  9. Characterisation of Grass Fibres

    Microsoft Academic Search

    M. Sfiligoj Smole; T. Kreze; S. Strnad; K. Stana Kleinschek; S. Hribernik

    2005-01-01

    The elementary grass fibres were isolated from different grass and legumes sorts, i.e. Ryegrass (Lolium hybridum Gumpenstein), Wheat straw, Trefoil (Trifolium pratense) and Lucerne (Medicago sativa). The fibre-samples were obtained in a bio-refinery, after the liquid phase containing proteins and lactic acid was eliminated from the ensiled and green grasses, respectively. For the isolation of elementary grass fibres different processes

  10. Integrated fibres for self-monitored optical transport

    NASA Astrophysics Data System (ADS)

    Bayindir, Mehmet; Shapira, Ofer; Saygin-Hinczewski, Dursen; Viens, Jeff; Abouraddy, Ayman F.; Joannopoulos, John D.; Fink, Yoel

    2005-11-01

    The ability to integrate distinct functional elements into a single device structure enables the realization of systems with higher-level functionality. Here we report on the design and fabrication of a fibre device structure that contains integrated optical, electrical and thermal elements for self-monitored optical transport. The fibre transmission element uses a hollow-core multilayer cylindrical photonic bandgap structure designed to guide high-power radiation at 10.6 ?m along the fibre axis. Multiple thermal-detection elements are placed in the vicinity of the hollow core for the purpose of temperature monitoring along the entire fibre length. Metal wires bridged by a semiconductor layer extend along the length of the fibre and deliver an electrical response to the fibre ends on change in the fibre temperature. The multimaterial fibre is drawn at high speeds from a single preform to produce extended lengths of optically and thermally functional fibres. The exponential dependence on temperature of the electrical conductivity of the semiconducting material allows for the discrimination, in real time, between normal transmission conditions and those that are indicative of localized defect formation, thus enabling a self-monitoring high-power optical transmission line for failure prediction and prevention.

  11. Optical fibre biosensors for oxygen and glucose monitoring

    NASA Astrophysics Data System (ADS)

    Young, J. S.; Scully, Patricia J.; Kvasnik, F.; Rose, K.; Kuncova, Gabriela; Podrazky, O.; Matejec, Vlastimil; Mrazek, Jan

    2005-05-01

    An optical fibre biosensor that uses an oxygen sensitive coating; Ruthenium complex [Dichlorotris(1,10-phenantroline)-ruthenium(II) hydrate], incorporated into an adhesive inorganic-organic hybrid polymer coating (ORMOCER) is described. The Ruthenium/ ORMOCER layer is used with optical fibres to form an extrinsic or intrinsic sensor. It can be applied to a microscope slide or lens to be interrogated by optical fibres, or form a cladding layer for an evanescent field optical fibre sensor. The Ruthenium complex is caused to fluoresce by a high brightness blue LED at 470 nm and the excitation light at 600nm is detected by a photomultiplier tube used as a photon counter, to measure fluorescence lifetime. The fluorescence is quenched by oxygen depletion within the layer, which can be linked to glucose by incorporation of suitable enzymes. The detection threshold is 0.7mg(O2)/litre, and the sensitivity is 70 ns/mg per litre.

  12. Effects of vitamin D on retinal nerve fiber layer in vitamin D deficient patients with optic neuritis: Preliminary findings of a randomized, placebo-controlled trial

    PubMed Central

    Salari, Mehri; Janghorbani, Mohsen; Etemadifar, Masoud; Dehghani, Alireza; Razmjoo, Hassan; Naderian, Gholamali

    2015-01-01

    Background: There is accumulating evidence for a possible protective role of vitamin D in the development and disease course of multiple sclerosis. Whether vitamin D is also effective in treating patients with optic neuritis (ON) is not known. The aim of this study was to evaluate the effect of oral vitamin D on the thickness of retinal nerve fiber layer (RNFL) in vitamin D deficient patients with ON by optical coherence tomography. Materials and Methods: A Phase II placebo-controlled randomized clinical trial conducted between July 2011 and November 2012 included 52 patients with confirmed unilateral ON aged 15-38 years and low serum 25-hydroxyvitamin D levels. The main outcome measures were changes in thickness of RNFL and macula 6 months after treatment. Patients were randomly allocated to receive 6 months of treatment with adding either 50,000 IU/week vitamin D or placebo. Results: In the 27 patients treated with vitamin D, the mean (standard deviation [SD]) thickness of RNFL decreased from 111.3 (18.9) ?m at baseline to 91.4 (13.3) at the end of study period (P < 0.001). Correspondingly, in the 25 patients treated with placebo, the mean (SD) thickness of RNFL decreased from 113.7 (21.5) ?m at baseline to 96.1 (12.3) at the end of study period (P < 0.01). In both groups, the mean thickness of the macula did not changed (P > 0.05). Average thickness of RNFL at the end of trial did not differ between groups. Conclusion: Adding vitamin D to routine disease therapy had no significant effect on the thickness of RNFL or macula in patients with ON. This trial is registered on www.clinicaltrials.gov (ID NCT01465893).

  13. Production of alumina fibre through jute fibre substrate

    Microsoft Academic Search

    M. Patel; B. K. Padhi

    1990-01-01

    Alumina fibre has been produced using jute fibre as substrate material at temperatures lower than 1600‡ C in a reducing atmosphere. Processed jute fibre was chemically pretreated by saturation with Al2Cl6 · 12H2O, coked and then pyrolysed to obtain alumina fibre. Chemical pretreatment conditions have been determined by following weight loss measurements of the jute fibre at 0.1 to 0.6

  14. Macular and peripapillary retinal nerve fiber layer thickness in children with hyperopic anisometropic amblyopia

    PubMed Central

    Wu, Shuang-Qing; Zhu, Li-Wei; Xu, Qi-Bin; Xu, Jun-Li; Zhang, Yu

    2013-01-01

    AIM To compare the retinal nerve fiber layer (RNFL) thickness and macular thickness in the amblyopic eye with that in the sound eye of children with hyperopic anisometropic amblyopia using optical coherence tomography (OCT). METHODS A prospective, nonrandom, intraindividual comparative cohort study includes 72 children with hyperopic anisometropic amblyopia in a single center. Macular thickness, macular foveola thickness, and peripapillary RNFL thickness were compared between the amblyopia eyes and the contralateral sound eyes. RESULTS There were 38 male and 34 female patients, with a mean age as 9.7±1.9 years (range, 5–16 years). Hyperopic was +3.62±1.16D (range +2.00D to +6.50D) in the amblyopic eyes, which was significantly higher in the control eyes with +0.76±0.90D (range 0D to +2.00D) (P < 0.01). The mean peripapillary RNFL thickness was 113.9±7.2µm and 109.2±6.9µm in the amblyopic eye and the normal eye, respectively, reaching statistical significance (P = 0.02). The mean macular foveola thickness was significantly thicker in the amblyopic eyes than the contralateral sound eyes (181.4±14.2µm vs 175.2±13.3µm, P < 0.01), but the 1mm, 3mm or 6mm macular thickness central macular thickness was not significantly different. Degree of anisometropia in the contralateral eyes was not significantly correlated with differences of peripapillary RNFL, macular foveola thickness or central macular thickness. CONCLUSION Eyes with hyperopic anisometropic amblyopia are found thicker macular foveola and peripapillary RNFL than the contralateral eyes in children. PMID:23550031

  15. Age-Associated Changes in the Retinal Nerve Fiber Layer and Optic Nerve Head

    PubMed Central

    Patel, Nimesh B.; Lim, Mimi; Gajjar, Avni; Evans, Kelsey B.; Harwerth, Ronald S.

    2014-01-01

    Purpose. Optical coherence tomography (OCT) measures of the retinal nerve fiber layer (RNFL) thickness and neuroretinal rim (NRR) parameters are often used as a surrogate for retinal ganglion cell content. The purpose of this study was to investigate the relationship between these morphological measures and the aging effects on these structures. Methods. One hundred thirteen healthy individuals, aged 19 to 76 years, with no prior history of retinal of optic nerve head pathology were recruited. A circumpapillary and radial OCT scan centered on the optic nerve head (ONH) was used for data analysis. Transverse scaling was calculated for each subject using measures from optical biometry. Custom algorithms were used for morphological analysis of the ONH NRR and RNFL that included quantification of major retinal vascular contribution. Results. There was a significant age-related loss of RNFL thickness (?0.23 ?m/y, R2 = 0.24, P < 0.01), major retinal vascular contribution (?0.03 ?m/y, R2 = 0.07, P = 0.01, neural rim volume (NRV, ?0.004 mm3/y, R2 = 0.15, P < 0.01), and minimum rim width (MRW, ?1.77 ?m/y, R2 = 0.23, P < 0.01) before, and after, incorporating the Bruch's membrane opening size (sMRW, ?1.86 ?m/y, R2 = 0.22, P < 0.01). When normalized, the rates of change for ONH NRR parameters (NRV, 0.69%/y and sMRW, 0.50%/y) exceeded that of RNFL thickness (0.19%/y, P < 0.01). Conclusions. Although both RNFL and ONH NRR parameters contain axons of retinal ganglion cells, there are differences in age-related changes in these measures that should be considered in clinical application. PMID:25052998

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

    PubMed Central

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

    2013-01-01

    AIM To investigate peripapillary retinal nerve fiber layer (RNFL), macula and ganglion cell layer thicknesses (GCC) in amblyopic eyes with spectral domain optical coherence tomography (SD-OCT). METHODS Thirty six patients with a history of unilateral amblyopia and thirty two children who had emmetropia without amblyopia were included in this study. In this institutional study, 36 eyes of 36 patients with amblyopia (AE), 36 fellow eyes without amblyopia (FE), and 32 eyes of 32 normal subjects (NE) were included. RNFL, GCC and macular thickness measurements were performed with RS-3000 OCT Retina Scan (Nidek Inc CA. USA). RESULTS The mean global thicknesses of the RNFL were 113.22±21.47, 111.57±18.25, 109.96±11.31µm in the AE, FE, and NE, respectively. There was no statistically significant difference for mean global RNFL thickness among the eyes (P=0.13). The mean thicknesses of the macula were 258.25±18.31, 258.75±19.54, 248.62±10.57µm in the AE, FE and NE, respectively. There was no statistically significant difference for thickness of macula among the eyes (P=0.06). The GCC was investigated into two parts: superior and inferior. The mean thicknesses of superior GCC were 102.57±13.32, 103.32±10.64, 100.52±5.88µm in the AE, FE, and NE, respectively. The mean thicknesses of inferior GCC were 103.82±12.60, 107.82±12.33, 105.86±10.79µm in the AE, FE and NE, respectively. There was no statistically significant difference for thickness of superior and inferior GCC between the eyes (P=0.63, P=0.46). CONCLUSION The macular thicknesses of AE and FE were greater than the NE, although it was not statistically significant. Amblyopia does not seem to have a profound effect on the RNFL, macula and GCC. PMID:23550060

  17. Optical Coherence Tomography of the Swollen Optic Nerve Head: Deformation of the Peripapillary Retinal Pigment Epithelium Layer in Papilledema

    PubMed Central

    Sibony, Patrick; Mandel, Gary; Durbin, Mary; Kardon, Randy H.

    2011-01-01

    Purpose. To examine the biomechanical deformation of load bearing structures of the optic nerve head (ONH) resulting from raised intracranial pressure, using high definition optical coherence tomography (HD-OCT). The authors postulate that elevated intracranial pressure induces forces in the retrolaminar subarachnoid space that can deform ONH structures, particularly the peripapillary Bruch's membrane (BM) and RPE layers. Methods. The authors compared HD-OCT optic nerve and peripapillary retinal nerve fiber layer (RNFL) findings in eyes with papilledema caused by raised intracranial pressure to findings in eyes with optic disc swelling caused by optic neuritis and nonarteritic anterior ischemic optic neuropathy (NAION), conditions without intracranial hypertension. The authors measured average thickness of the RNFL and the angle of the RPE/BM at the temporal and nasal borders of the neural canal opening. The angle was measured as positive with inward (toward the vitreous) angulation and as negative with outward angulation. Results. Of 30 eyes with papilledema, 20 eyes (67%) had positive RPE/BM rim angles. One of eight optic neuritis (12%) eyes and 1 of 12 NAION (8%) eyes had positive angulation. In five eyes with papilledema, RNFL thickening increased, three of which developed positive RPE/BM angles. On follow-up, 22 papilledema eyes had a reduction of RNFL swelling, and 17 of these eyes had less positive RPE/BM angulation. Conclusions. In papilledema, the RPE/BM is commonly deflected inward, in contrast to eyes with NAION or optic neuritis. The RPE/BM angulation is presumed to be caused by elevated pressure in the subarachnoid space, does not correlate with the amount of RNFL swelling, and resolves as papilledema subsides. PMID:21705690

  18. Respiratory monitoring using fibre long period grating sensors

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

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

    Microsoft Academic Search

    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

    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

  20. Low Loss Photonic Crystal Fibre

    Microsoft Academic Search

    L. Farr; J. C. Knight; B. J. Mangan; P. J. Roberts

    2002-01-01

    We describe a photonic crystal fibre with an optical loss of 0.58 dB\\/km. We find a strong correlation between the measured loss minimum and the overall structural scale in otherwise identical fibres

  1. The long-term effect of intravitreal ranibizumab on retinal nerve fiber layer thickness in exudative age-related macular degeneration.

    PubMed

    Parlak, Melih; Oner, F Hakan; Saatci, A Osman

    2015-08-01

    The aim of this study was to evaluate the long-term effect of intravitreal ranibizumab on the retinal nerve fiber layer (RNFL) in exudative age-related macular degeneration (AMD). Patients with treatment naive neovascular AMD in one eye were enrolled into the study. Following 3 monthly intravitreal ranibizumab injections, the patients were evaluated according to disease activity and re-injections were performed according to "treat and extend" protocol. During the follow-up, peripapillary nerve fiber layer thickness measurements were compared with normal fellow eyes. Forty-four eyes of 11 women and 11 men with the mean age of 66.3 ± 8.8 years (50-80) were enrolled into the study. All patients had completed at least 12 months of follow-up time. Patients received an average of 4.7 (3-11 injections) intravitreal injections. At baseline, no significant difference was observed between two groups for RNFL thickness, which was assessed as quadrants (p = 0.250-0.944) and globally (p = 0.814). In each group, there was a significant RNFL thinning (p = 0.009 and 0.022) after the third month, whereas no significant difference was observed between treated and untreated eyes. Patients were also classified according to the number of injections, and RNFL thickness showed no difference between eyes treated with less or more than five intravitreal injections (p = 0.757-0.973). Although there was no statistically significant difference in RNFL thickness between study and control eyes during 12 months of follow-up, a significant thinning was recorded in both groups compared with baseline values. Cross-sectional images with higher resolutions and precise segmentation opportunities are needed to investigate the hypothesis "VEGF neutralization and inhibition of cell maintenance" in detail. PMID:25059401

  2. Population-Based Evaluation of Retinal Nerve Fiber Layer, Retinal Ganglion Cell Layer, and Inner Plexiform Layer as a Diagnostic Tool For Glaucoma

    PubMed Central

    Springelkamp, Henriët; Lee, Kyungmoo; Wolfs, Roger C. W.; Buitendijk, Gabriëlle H. S.; Ramdas, Wishal D.; Hofman, Albert; Vingerling, Johannes R.; Klaver, Caroline C. W.; Abràmoff, Michael D.; Jansonius, Nomdo M.

    2014-01-01

    Purpose. We determined the glaucoma screening performance of regional optical coherence tomography (OCT) layer thickness measurements in the peripapillary and macular region, in a population-based setting. Methods. Subjects (n = 1224) in the Rotterdam Study underwent visual field testing (Humphrey Field Analyzer) and OCT of the macula and optic nerve head (Topcon 3-D OCT-1000). We determined the mean thicknesses of the retinal nerve fiber layer (RNFL), retinal ganglion cell layer (RGCL), and inner plexiform layer for regions-of-interest; thus, defining a series of OCT parameters, using the Iowa Reference Algorithms. Reference standard was the presence of glaucomatous visual field loss (GVFL); controls were subjects without GVFL, an intraocular pressure (IOP) of 21 mm Hg or less, and no positive family history for glaucoma. We calculated the area under the receiver operating characteristics curve (AUCs) and the sensitivity at 97.5% specificity for each parameter. Results. After excluding 23 subjects with an IOP > 21 mm Hg and 73 subjects with a positive family history for glaucoma, there were 1087 controls and 41 glaucoma cases. Mean RGCL thickness in the inferior half of the macular region showed the highest AUC (0.85; 95% confidence interval [CI] 0.77–0.92) and sensitivity (53.7%; 95% CI, 38.7–68.0%). The mean thickness of the peripapillary RNFL had an AUC of 0.77 (95% CI, 0.69–0.85) and a sensitivity of 24.4% (95% CI, 13.7–39.5%). Conclusions. Macular RGCL loss is at least as common as peripapillary RNFL abnormalities in population-based glaucoma cases. Screening for glaucoma using OCT-derived regional thickness identifies approximately half of those cases of glaucoma as diagnosed by perimetry. PMID:25414193

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    PubMed Central

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

    2011-01-01

    A Swept Source Polarization-Sensitive Optical Coherence Tomography (SS-PS-OCT) instrument has been designed, constructed, and verified to provide high sensitivity depth-resolved birefringence and phase retardation measurements of the retinal nerve fiber layer. The swept-source laser had a center wavelength of 1059 nm, a full-width-half-max spectral bandwidth of 58 nm and an A-line scan rate of 34 KHz. Power incident on the cornea was 440 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

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

    PubMed Central

    Yalcin, Elvan; Balci, Ozlem

    2014-01-01

    Purpose To evaluate whether there was a difference in peripapillary retinal nerve fiber layer (RNFL) and foveal thickness between amblyopic and normal individuals with optical coherence tomography. Materials and methods Sixty patients, 30 patients with hypermetropic anisometropic amblyopia and 30 normal emmetropic subjects, were enrolled in this study. The eyes of the participants were divided into three groups: 30 eyes of 30 patients with amblyopia (A), 30 fellow eyes of the amblyopic patients (B), and 30 eyes of 30 normal subjects (C). Emmetropic normal subjects included cases with normal visual acuity and unremarkable ocular examinations. After routine ophthalmic examination, peripapillary retinal nerve fiber layer and foveal thickness measurements were measured by time-domain optical coherence tomography and compared among the three groups. Results The difference in RNFL thickness between amblyopic eyes, fellow eyes of the amblyopic patients, and normal eyes of the emmetropic subjects was not clinically significant. However, the mean foveal thickness was significantly thicker in amblyopic eyes versus the fellow eyes and normal subjects’ eyes. Conclusion Our results suggest that amblyopia seems to have an effect on the foveal thickness, but not on the RNFL thickness. PMID:24748770

  7. Hybrid Filtration Membranes incorporating Nanoporous Silica within a Nanoscale Alumina Fibre Scaffold

    E-print Network

    Su, Veronica Mei Tiing; Clyne, Trevor William

    2015-06-11

    Membranes were produced from fine (?10?nm) alumina fibres, by dispersing them in liquid and using controlled sedimentation to produce two types of membrane – one a duplex structure (layers of well-dispersed fibres and micro-bundles) and the other...

  8. The association between macular thickness and peripapillary retinal nerve fiber layer thickness in Chinese children.

    PubMed

    Lee, Jacky W Y; Yau, Gordon S K; Woo, Tiffany T Y; Lai, Jimmy S M

    2015-02-01

    To investigate the association between macular thickness and peripapillary retinal nerve fiber layer (RNFL) thickness in Chinese children. This cross-sectional study recruited consecutive cases of healthy pediatric subjects aged 4 to 18 from Caritas Medical Centre in Hong Kong Special Administrative Region, China, from 2013 to 2014. Subjects with only eye, ocular tumors, congenital glaucoma, congenital cataract, congenital nystagmus, microphthalmos, optic nerve or retinal disease, active ocular infections, corneal scars, and severe visual impairment of any cause were excluded. Peripapillary RNFL thickness and macular thickness at 1-mm-diameter fovea center (C1), 3-mm-diameter temporal quadrant (T3), and 3-mm-diameter nasal quadrant (N3) were measured with optical coherence tomography. Best-corrected visual acuity, axial length, and cycloplegic refraction were also recorded. Spearman correlation was used to analyze the association between T3, C1, and N3 with each of the following: average and quadrant RNFL thickness, axial length, and spherical equivalent. In 179 subjects, the mean age was 7.9?±?3.6 years. There were 90 male and 89 female subjects, all of Chinese ethnicity. The mean spherical equivalent was -0.1?±?3.1 D and mean axial length was 22.9?±?1.4?mm. There were significant and positive correlations of the average (T3: r?=?0.20, P?=?0.04; N3: r?=?0.2, P?=?0.005), superior (T3: r?=?0.20, P?=?0.03; N3: r?=?0.2, P?=?0.03), and inferior (T3: r?=?0.20, P?=?0.02; N3: r?=?0.2, P?=?0.01) peripapillary RNFL thicknesses with the T3 and N3 macular thicknesses but not C1. The nasal peripapillary RNFL thickness was also positively correlated with T3 (r?=?0.20, P?=?0.01). There were no significant associations between the macular thickness (T3, C1, N3) with neither the spherical equivalent (P?>?0.2) nor the axial length (P?>?0.3). The macular thickness was positive correlated with the peripapillary RNFL thickness in a population of healthy Chinese children. PMID:25715254

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

    Microsoft Academic Search

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

    2002-01-01

    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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed Central

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

    2014-01-01

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

  13. Estimation of fibre and interfacial shear strength by using a single-fibre composite

    Microsoft Academic Search

    Masatoshi Shioya; Akira Takaku

    1995-01-01

    The fibre\\/matrix interfacial shear strength is often estimated from the fragmentation process of a fibre in a single-fibre composite loaded in tension. The interfacial shear strength is calculated from a knowledge of the critical length and the tensile strength of the fibre. Unfortunately, if the tensile strength of fibres distributes widely and increases with decreasing fibre length, then problems arise

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

    NASA Astrophysics Data System (ADS)

    Trindade, M. A.; Benjeddou, A.

    2011-07-01

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

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

    PubMed

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

    1997-08-01

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

  16. Distributed ultrafast fibre laser

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  18. Comparison of responses of spontaneously active cells in the cerebellar purkinje layer to parallel fibre stimulation in slice preparations and urethane-anaesthetised rats: Effects of benzodiazepine receptor ligands

    Microsoft Academic Search

    C. R. Gardner; S. Hussain; A. Pringle; J. Bagust; R. J. Walker

    1998-01-01

    1.1. GABA-mediated inhibitory responses were induced in spontaneously active Purkinje cells by parallel fibre stimulation in cerebellar slices or in urethane-anaesthetised rats. Effects of agonist and inverse agonist benzodiazepine (BDZ) receptor ligands were compared in the preparations.2.2. Purkinje cells fired simple spikes at higher rates in slice preparations while complex spikes were seldom (in vivo) or never observed (slice). Cells

  19. Comparative Study of Retinal Nerve Fiber Layer Measurement by StratusOCT and GDx VCC, II: Structure\\/Function Regression Analysis in Glaucoma

    Microsoft Academic Search

    Christopher Kai-shun Leung; Kelvin Kam-Long Chong; Wai-man Chan; Cedric Ka-Fai Yiu; Man-yee Tso; Jackson Woo; Moon-Kwong Tsang; Kwok-kay Tse; Wing-ho Yung

    2005-01-01

    PURPOSE. To evaluate the structure\\/function relationship be- tween visual field sensitivity and retinal nerve fiber layer (RNFL) thickness measured by StratusOCT (Carl Zeiss Meditec, Inc., Dublin, CA) and GDx VCC (Laser Diagnostic Technolo- gies, Inc., San Diego, CA). METHODS. Eighty-nine subjects (27 who had healthy eyes, 21 who were glaucoma suspect, 41 who had glaucoma) were enrolled in this cross-sectional

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

    Microsoft Academic Search

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

    2002-01-01

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

  1. Local real-time detection of pH using fibre tapers

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  2. Nanophotonics inside structured optical fibres

    NASA Astrophysics Data System (ADS)

    Canning, J.

    2011-05-01

    Tailoring and structuring optical fibres to nanoscale dimensions is rapidly becoming a focus area of research and is important for the eventual success of future in-fibre optical systems and novel technologies. Here, I review one aspect of our work in establishing and pursuing this field: localizing light for sensing.

  3. End effects in optical fibres

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The performance of highly multiplexed spectrographs is limited by focal ratio degradation (FRD) in the optical fibres. It has already been shown that this is caused mainly by processes concentrated around the mounting points at the ends of the fibres. We use the thickness of rings produced in the far-field when a fibre is illuminated by a collimated beam, to estimate the size of the region where the FRD is generated. This requires the development of a new model, using features of existing ray-tracing and wave-based models, which fits existing data very well. The results suggest that the amount of FRD is primarily determined by the length of fibre bonded into the supporting ferrule. We point out the implications for the production of future fibre systems.

  4. Study on pulse compression in tapered holey fibres

    NASA Astrophysics Data System (ADS)

    Ma, Wen-Wen; Li, Shu-Guang; Yin, Guo-Bing; Fu, Bo; Zhang, Lei

    2010-10-01

    This paper proposes three kinds of tapered holey fibres with a multi-layer of holes whose pitch of air holes at the end of untapered and tapered are 5.8 ?m and 1.8 ?m. The central wavelength which locates in the anomalous dispersion region is 1.55 ?m. An adaptive split-step Fourier method is numerically used to study the pulse propagation in tapered holey fibres. For the considered convex tapered holey fibre, at a wavelength of 1.55 ?m, a compression factor of 136.7 can be achieved by initial width of 800 fs propagation through a length of 0.8 m. It demonstrates that in anomalous dispersion region, pulse can be compressed with the increase of nonlinearity coefficient and the decrease of dispersion coefficient.

  5. Fatigue behaviour of metallic fibre-reinforced materials: a study of steel fibre-reinforced silver

    Microsoft Academic Search

    G. Rosenkranz; V. Gerold; K. Kromp; D. Stöckel; L. Tillmann

    1982-01-01

    Fatigue damage and crack propagation modes in composites with unidirectionally aligned fibres may be affected by several variables such as fibre and matrix strength, fibre—matrix interfacial bonding and possible fluctuations in the strength of the reinforcing fibres. The influence of the different parameters on the behaviour of metallic fibre-reinforced materials was investigated up to 108 cycles in a model compound

  6. Why animals have different muscle fibre types

    Microsoft Academic Search

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

    1988-01-01

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

  7. Tapered optical fibres for sensing

    NASA Astrophysics Data System (ADS)

    Martan, Tomas; Kanka, Jiri; Kasik, Ivan; Matejec, Vlastimil

    2008-11-01

    Recently, optical fibre tapers have intensively been investigated for many applications e.g. in telecommunications, medicine and (bio-) chemical sensing. The paper deals with enhancement of evanescent-field sensitivity of the solid-core microstructured fibre with steering-wheel air-cladding. Enhancement of a performance of the microstructured fibre is based on reduction of fibre core diameter down to narrow filament by tapering thereby defined part of light power is guided by an evanescent wave traveling in axial cladding air holes. The original fibre structure with outer diameter of 125 µm was reduced 2×, 2.5×, 3.33×, and 4× for increasing relatively small intensity overlap of guided core mode at wavelength of 1.55 ?m with axial air holes. The inner structures of tapered microstructured fibre with steering-wheel aircladding were numerically analyzed and mode intensity distributions were calculated using the FDTD technique. Analyzed fiber tapers were prepared by constructed fibre puller employing 'flame brush technique'.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

    Purpose: To determine the correlations and strength of association between different imaging systems in analyzing the retinal nerve fiber layer (RNFL) of glaucoma patients: optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO). Materials and Methodology: 114 eyes of patients with moderate open angle glaucoma underwent spectral domain OCT (Topcon SD-OCT 2000 and Zeiss Cirrus HD-OCT), SLP (GDx VCC and GDx Pro) and CSLO (Heidelberg Retina Tomograph, HRT 3). Correlation coefficients were calculated between the structural parameters yielded by these examinations. The quantitative relationship between the measured RNFL thickness globally and for the four regions (superior, inferior, nasal, temporal) were evaluated with different regression models for all used imaging systems. Results: The strongest correlation of RNFL measurements was found between devices using the same technology like GDx VCC and GDx Pro as well as Topcon OCT and Cirrus OCT. In glaucoma patients, the strongest associations (R²) were found between RNFL measurements of the two optical coherence tomography devices Topcon OCT and Cirrus OCT (R² = 0.513) and between GDx VCC and GDx Pro (R² = 0.451). The results of the OCTs and GDX Pro also had a strong quantitative relationship (Topcon OCT R² = 0.339 and Cirrus OCT R² = 0.347). GDx VCC and the OCTs showed a mild to moderate association (Topcon OCT R² = 0.207 and Cirrus OCT R² = 0.258). The confocal scanning laser ophthalmoscopy (HRT 3) had the lowest association to all other devices (Topcon OCT R² = 0.254, Cirrus OCT R² = 0.158, GDx Pro R² = 0.086 and GDx VCC R² = 0.1). Conclusion: The measurements of the RNFL in glaucoma patients reveal a high correlation of OCT and GDx devices because OCTs can measure all major retinal layers and SLP can detect nerve fibers allowing a comparison between the results of this devices. However, CSLO by means of HRT topography can only measure height values of the retinal surface but it cannot distinguish between different retinal layers. This may explain the rather poor correlations and associations between CSLO measurements and those of all other imaging devices which makes it difficult to compare HRT 3 nerve fiber data. These correlations are important in clinical routine especially when different techniques are used in the follow-up of glaucoma patients. PMID:25926903

  10. Use of fibre wastes from production of acetate fibres

    SciTech Connect

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

    1995-07-01

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

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

    Microsoft Academic Search

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

    2005-01-01

    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

  12. Microcystic Inner Nuclear Layer Changes and Retinal Nerve Fiber Layer Defects in Eyes with Glaucoma

    PubMed Central

    Hasegawa, Tomoko; Akagi, Tadamichi; Yoshikawa, Munemitsu; Suda, Kenji; Yamada, Hiroshi; Kimura, Yugo; Nakanishi, Hideo; Miyake, Masahiro; Unoki, Noriyuki; Ikeda, Hanako Ohashi; Yoshimura, Nagahisa

    2015-01-01

    Objective To examine microcystic inner nuclear layer (INL) changes in glaucomatous eyes and to determine associated factors. Design Retrospective, cross-sectional, observational study. Methods Two hundred seventeen eyes of 133 patients with primary open angle glaucoma (POAG), 41 eyes of 32 patients with preperimetric glaucoma and 181 normal eyes of 117 subjects were ultimately included. Microcystic INL lesions were examined with infrared fundus images and with 19 vertical spectral domain optical coherence tomography (SD-OCT) images in the macular area. Results Microcystic INL changes were observed in 6.0% of eyes with POAG, but none of the normal eyes or eyes with preperimetric glaucoma showed microcystic INL changes. The proportion of eyes with advanced glaucoma was significantly larger (P = 0.013) in eyes with microcystic lesions than without. The visual field mean deviation (MD) slope was also significantly worse (P = 0.027) in eyes with microcystic lesions. No significant differences were observed in age, sex, refraction, axial length, intraocular pressure, or MD value between eyes with and without microcystic INL lesions. In several cases, microcystic INL lesions occurred along with glaucomatous visual field progression. The retinal nerve fiber layer (RNFL) thickness (P = 0.013) and ganglion cell layer (GCL) + inner plexiform layer thickness (P = 0.023) were significantly lower in areas with microcystic lesions than without. The INL was also significantly thicker (P = 0.002) in areas with microcystic lesions. Conclusions Microcystic INL lesions in glaucomatous eyes are closely associated with RNFL and GCL thinning and correlated with worse MD slope. These INL lesions may indicate focal and progressive damage in glaucoma. PMID:26066021

  13. Monte Carlo study of the time resolution of scintillating fibre detectors

    NASA Astrophysics Data System (ADS)

    Ziembicki, M.; Marzec, J.; Dziewiecki, M.

    2007-08-01

    This paper presents the results of a Monte Carlo study of the time resolution of a scintillating fibre detector and analyses its dependence on the various aspects of detector construction. The estimations of the theoretical time resolutions for detectors with different numbers of fibre layers and different types of acrylic-based fibre coatings are presented. The method is suggested to decrease the rate counting effects encountered in high rate applications. It has been observed that for dual cladding fibres with a fluorinated polymer used for the outer cladding, the most significant factor contributing to the time resolution is the number of fibre layers, with the fibre coating being the marginal one. Another observation shows that the introduction of a gap between the fibre and the photomultiplier glass window allows the reduction of the number of photoelectrons by 25% with only a slight decrease in the time resolution, which may be helpful in decreasing the pulse pile-up effects and the photomultiplier gain, commonly observed under high rate conditions.

  14. Behaviour of disc oedema during and after amiodarone optic neuropathy: case report.

    PubMed

    Martínez-LóPez-Portillo, Med Alejandro; Martínez-Gamero, Bertha O; Mohamed-Noriega, Jibran; Cavazos-Adame, Med Humberto; Mohamed-Hamsho, Med Jesús

    2014-04-01

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

  15. Structure-Function Relationship between Frequency-Doubling Technology Perimetry and Optical Coherence Tomography in Glaucoma.

    PubMed

    Fuertes-Lazaro, Isabel; Sanchez-Cano, Ana; Ferreras, Antonio; Ferrandez, Blanca; Calvo, Pilar; Abadia, Beatriz; Otin, Sofia; Pablo, Luis E

    2014-11-26

    Purpose: To assess the relationship between the retinal nerve fibre layer (RNFL) thickness and the frequency-doubling technology perimetry (FDT) outcome. Methods: Sixty-two healthy individuals and 72 glaucoma patients were prospectively selected. All participants underwent a reliable FDT and optical coherence tomography (OCT). Pearson correlations were calculated between the unlogged threshold values of FDT and RNFL thicknesses measured by OCT. Results: Mild to moderate correlations were found between a few points from FDT and RNFL thicknesses in the vertical axis. The nasal superior area of FDT and the RNFL thickness at the 7-o'clock position had the strongest correlation (0.434, p < 0.001). Conclusions: The poor agreement between FDT and OCT parameters suggests that both instruments assess different characteristics of glaucomatous optic neuropathy. The map obtained validates previously reported clinical findings and contributes to a better understanding of the structure-function relationship in glaucoma. © 2014 S. Karger AG, Basel. PMID:25427775

  16. Assessment of rates of structural change in glaucoma using imaging technologies

    PubMed Central

    Mansouri, K; Leite, M T; Medeiros, F A; Leung, C K; Weinreb, R N

    2011-01-01

    Purpose To review the ability of current imaging technologies to provide estimates of rates of structural change in glaucoma patients. Patients and methods Review of literature. Results Imaging technologies, such as confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and optical coherence tomography (OCT), provide quantifiable and reproducible measurements of the optic disc and parapapillary retinal nerve fibre layer (RNFL). Rates of change as quantified by the rim area (RA) (for CSLO) and RNFL thickness (for SLP and OCT) are related to glaucoma progression as detected by conventional methods (eg, visual fields and optic disc photography). Evidence shows that rates of RNFL and RA loss are significantly faster in progressing compared with non-progressing glaucoma patients. Conclusion Measurements of rates of optic disc and RNFL change are becoming increasingly precise and individualized. Currently available imaging technologies have the ability to detect and quantify progression in glaucoma, and their measurements may be suitable end points in glaucoma clinical trials. PMID:21212798

  17. Theoretical Model Analysis of the Governing Relationship of the Inlaid Fibre Plank – Concrete Bond Structure

    Microsoft Academic Search

    Zuquan Yang; Zailin Guo

    \\u000a The reinforcement technology of the surface layer embedded carbon fibre plank is a kind of new application form used in the\\u000a carbon fibre plank reinforced concrete structure components. In this page, the theoretical model of the governing relationship\\u000a of the inlaid fiber plank –concrete bond structure has been illustrated according to the test research with the epoxy resin\\u000a and epoxy

  18. Finite element analysis of an inelastic interface in ultrasonic welded metal\\/fibre-reinforced polymer joints

    Microsoft Academic Search

    N. Konchakova; F. Balle; F. J. Barth; R. Mueller; D. Eifler; P. Steinmann

    2010-01-01

    The ultrasonic welding technology is an innovative method to produce hybrid joints for multi-material components. In this contribution, the behaviour of an interface layer of metal\\/fibre-reinforced polymer single overlap tensile specimens is considered. The investigations are carried out using the ultrasonic metal welding technique (UMW) for joining carbon fibre reinforced thermoplastic composites (CFRP) with aluminium alloys. An interfacial traction-separation-law based

  19. Effects of local fibre waviness on damage mechanisms and fatigue behaviour of biaxially loaded tube specimens

    Microsoft Academic Search

    F. Schmidt; M. Rheinfurth; P. Horst; G. Busse

    Damage development in and final failure process of glass fibre winding specimens during biaxial fatigue loading are investigated. The phenomena in nominally defect-free tubes and specimens exhibiting local fibre waviness in one layer are compared. A subset of wound tubes is analysed using non-destructive testing methods, i.e. air-coupled guided waves, thermography, optical fracture analysis by a high-speed camera, and discrete

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

    Microsoft Academic Search

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

    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

  1. Multifunctional, supramolecular, continuous artificial nacre fibres

    PubMed Central

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-01-01

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

  2. Wetting of flexible fibre arrays.

    PubMed

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

    2012-02-23

    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

  3. Decreased retinal nerve fiber layer thickness in patients with obstructive sleep apnea\\/hypopnea syndrome

    Microsoft Academic Search

    Pei-Wen Lin; Michael Friedman; Hsin-Ching Lin; Hsueh-Wen Chang; Tanya M. Pulver; Chien-Hung Chin

    2011-01-01

    Background  To compare parameters for retinal nerve fiber layer (RNFL) thickness, optic nerve head (ONH) measurements, and macular thickness\\u000a in patients with different severities of obstructive sleep apnea\\/hypopnea syndrome (OSAHS) versus normal controls.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Patients presenting with snoring and daytime sleepiness who underwent overnight polysomnography to determine OSAHS severity\\u000a were recruited, and subsequently referred for ophthalmologic evaluation. Optical coherence tomography was used

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

    Microsoft Academic Search

    Tim Huber; Udo Biedermann; Jörg Müssig

    2010-01-01

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

  5. Assessment of Macular Peripapillary Nerve Fiber Layer and Choroidal Thickness Changes in Pregnant Women with Gestational Diabetes Mellitus, Healthy Pregnant Women, and Healthy Non-Pregnant Women

    PubMed Central

    Acmaz, Gokhan; Atas, Mustafa; Gulhan, Ahmet; Acmaz, Banu; Atas, Fatma; Aksoy, Huseyin; Zararsiz, Gokmen; Gokce, Gokcen

    2015-01-01

    Background Gestational diabetes mellitus (GDM) is a risk factor for the development of type II diabetes and it causes maternal and child morbidity. Screening for diabetic retinopathy (DR) is important because patients who develop DR have no symptoms until macular edema and/or proliferative diabetic retinopathy (PDR) are already present. The aim of this study was to determine the early retinal findings of GDM. Material/Methods This study was conducted in a tertiary research center. We conducted a prospective cross-sectional study with 3 groups: Group 1 consisted of 36 pregnant women with GDM, Group 2 consisted of 24 healthy pregnant women, and Group 3 consisted of 38 healthy non-pregnant women of reproductive age. Spectralis optical coherence tomography (OCT) was used for the assessment. Macular, choroid, and retinal nerve fiber layer (RNFL) thicknesses were evaluated in patients with GDM and comparisons were made among pregnant women with GDM, healthy pregnant women, and healthy non-pregnant women for these parameters. Results The nasal part of the RNFL was significantly thinner in the GDM group than in the healthy pregnant group. None of the patients had retinopathy or macular edema at the time of examination. Conclusions Decreased nasal part of RNFL thickness may be the first retinal change in patients with GDM. Our study suggests that OCT should be performed for the patients with GDM for detection of early retinal changes associated with GDM. PMID:26084958

  6. Assessment of Macular Peripapillary Nerve Fiber Layer and Choroidal Thickness Changes in Pregnant Women with Gestational Diabetes Mellitus, Healthy Pregnant Women, and Healthy Non-Pregnant Women.

    PubMed

    Acmaz, Gokhan; Atas, Mustafa; Gulhan, Ahmet; Acmaz, Banu; Atas, Fatma; Aksoy, Huseyin; Zararsiz, Gokmen; Gokce, Gokcen

    2015-01-01

    BACKGROUND Gestational diabetes mellitus (GDM) is a risk factor for the development of type II diabetes and it causes maternal and child morbidity. Screening for diabetic retinopathy (DR) is important because patients who develop DR have no symptoms until macular edema and/or proliferative diabetic retinopathy (PDR) are already present. The aim of this study was to determine the early retinal findings of GDM. MATERIAL AND METHODS This study was conducted in a tertiary research center. We conducted a prospective cross-sectional study with 3 groups: Group 1 consisted of 36 pregnant women with GDM, Group 2 consisted of 24 healthy pregnant women, and Group 3 consisted of 38 healthy non-pregnant women of reproductive age. Spectralis optical coherence tomography (OCT) was used for the assessment. Macular, choroid, and retinal nerve fiber layer (RNFL) thicknesses were evaluated in patients with GDM and comparisons were made among pregnant women with GDM, healthy pregnant women, and healthy non-pregnant women for these parameters. RESULTS The nasal part of the RNFL was significantly thinner in the GDM group than in the healthy pregnant group. None of the patients had retinopathy or macular edema at the time of examination. CONCLUSIONS Decreased nasal part of RNFL thickness may be the first retinal change in patients with GDM. Our study suggests that OCT should be performed for the patients with GDM for detection of early retinal changes associated with GDM. PMID:26084958

  7. Short communication FibreBags vs. FibreCaps for acid

    E-print Network

    Paris-Sud XI, Université de

    and neutral detergent fibre (ADF and NDF) was developed to reduce the need for filtration and to allowBag is suitably similar in performance to the FibreCap system. NDF, neutral detergent fibre / ADF, acid detergent]. Based on this concept of batch process- ing, the FibreCap system of forage analysis was developed [4

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  9. Structure–Property Relationships in Natural Cellulosic Fibres: Part IV: Biodegradability of Textile Fibres

    Microsoft Academic Search

    I. A. Ansari; G. C. East; D. J. Johnson

    2003-01-01

    This is the fourth and final part in a series of research papers featuring structure-property relationships in natural cellulosic fibres; this part gives a comparative study made of the biodegradability of various fibres when buried in soil. The weight loss of the fibres after burial for different lengths of time was determined, and the fibres were examined under a scanning

  10. Moderate-power cw fibre lasers

    SciTech Connect

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

    2004-10-31

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

  11. Development of bioabsorbable glass fibres.

    PubMed

    Lin, S T; Krebs, S L; Kadiyala, S; Leong, K W; LaCourse, W C; Kumar, B

    1994-10-01

    Calcium-iron phosphate glasses with an iron oxide content ranging from 5 wt.% to 22 wt.% were prepared to investigate the effect of iron oxide on the properties of the glass. It was found that the dissolution rate, the fibre strength and the glass transition temperature were strongly affected by iron oxide. The glass dissolution rate exhibited a 50-fold reduction while the fibre strength doubled when the iron oxide content was increased from 5 wt.% to 22 wt.%. The phosphate glass containing 22 wt.% of iron oxide had a dissolution rate of about 5 micrograms/(cm2 day). The fibres drawn from this glass also exhibited the highest tensile strength over 1000 MPa. A cortical bone plug method was used to assess the biocompatibility of the glasses with the hard and soft tissues. The tissues surrounding the samples showed no inflammation at 9 wk. PMID:7888576

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  13. Preliminary study: fibre content in pet rabbit diets, crude fibre versus total dietary fibre.

    PubMed

    Molina, J; Martorell, J; Hervera, M; Pérez-Accino, J; Fragua, V; Villaverde, C

    2015-04-01

    Fibre is an important nutrient for rabbit health, and, on commercial pet rabbit packaging, it is labelled as crude fibre (CF). In several species, it is considered that CF is not an accurate representation of the fibre content in feedstuffs. The objective of this study was to compare the CF stated on the label (CFL) with laboratory analysis of CF (CFA) and the analysed content of total dietary fibre (TDF) in different commercial pet rabbit feeds. We selected 15 commercial diets and analysed CF and TDF. A mixed model was used to evaluate differences between CFL, CFA and TDF, and linear regression was performed to study the correlation between CFL and CFA with TDF. CFA and CFL were not significantly different (p = 0.836) in the feeds studied, and both were lower than TDF (p < 0.001). The correlations between TDF and both CFA and CFL were significant (p < 0.001 and p = 0.02, respectively), but the correlation was better with CFA (R = 0.86) than with CFL (R = 0.53). As expected, TDF content was higher than CF content, an average of two times. These results suggest that the CF content in rabbit diets reported on the label is not an appropriate indicator of their total fibre content, although further work with a larger sample size is required to confirm these results. PMID:25865419

  14. More about fibre friction and its measurements

    Microsoft Academic Search

    Mehmet Emin Yuksekkay

    2009-01-01

    Unfortunately, the classical empirical friction laws do not hold true for fibrous and viscoelastic materials comprising most of the textile fibres. In the second half of the twentieth century, fibre surfaces have been studied by many distinguished scientists who were able to complete numerous researches for the frictional characteristics of different types of fibres. Most of the researchers have aimed

  15. Respiratory muscle fibres: specialisation and plasticity

    PubMed Central

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

    2004-01-01

    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

  16. FIBRED CATEGORIES `a la Jean Benabou

    E-print Network

    Haller-Dintelmann, Robert

    FIBRED CATEGORIES `a la Jean B´enabou Thomas Streicher April 1999 ­ February 2012 The notion of fibred category was introduced by A. Grothendieck for purely geometric reasons. The "logical" aspect] of Des Cat´egories Fibr´ees, a course by Jean B´enabou given at the University of Louvain-la-Neuve back

  17. ADVANCES IN ACTIVE FIBRES FOR HIGH-POWER AND HIGH-BRIGHTNESS FIBRE SOURCES

    Microsoft Academic Search

    J. K. Sahu; S. Yoo; A. J. Boyland; A. Webb; M. Kalita; Y. Jeong; J. Nilsson; D. N. Payne

    This paper reviews the progress in rare-earth dope d fibre technology towards power scaling of high-brightness fibre sources. SUMMARY After the successful implementation of erbium doped fibre amplifiers (EDFAs) in telecommunications, the area of high-power, cladding-pumped fibre lasers an d amplifiers have seen a major field of operation of rare-earth doped fibres. High power sources have numerous industrial, military, and

  18. Climbing fibre induced depression of both mossy fibre responsiveness and glutamate sensitivity of cerebellar Purkinje cells

    PubMed Central

    Ito, Masao; Sakurai, Masaki; Tongroach, Pavich

    1982-01-01

    1. In high decerebrate rabbits, cells were sampled extracellularly from the rostral flocculus. Purkinje cells were identified by their characteristic responses to stimulation of the contralateral inferior olive. Identification of basket cells was based on the absence of olivary responses and also on their location in the molecular layer adjacent to identified Purkinje cells. Mass field potentials in the flocculus were also studied. 2. Single pulse stimulation of a vestibular nerve, either ipsilateral or contralateral, at a rate of 2/sec excited Purkinje cells with a latency of 3-6 msec. This early excitation represents activation through vestibular mossy fibres, granule cells and their axons (parallel fibres). Similar early excitation also occurred in putative basket cells. 3. Conjunctive stimulation of a vestibular nerve at 20/sec and the inferior olive at 4/sec, for 25 sec per trial, effectively depressed the early excitation of Purkinje cells by that nerve, without an associated change in spontaneous discharge. The depression recovered in about ten minutes. This recovery was followed by the onset of a slow depression lasting for an hour. 4. Conjunctive vestibular—olivary stimulation produced no such depression in the following responses: early excitation in Purkinje cells induced from the vestibular nerve not involved in the conjunctive stimulation; early excitation in putative basket cells from either vestibular nerve; inhibition or rebound facilitation in Purkinje cells following the early excitation; vestibular-evoked field potentials in the granular layer and white matter of the flocculus. These observations lead to the conclusion that the depression occurs specifically at parallel fibre—Purkinje cell synapses involved in conjunctive stimulation. 5. Ionophoretic application of glutamate to Purkinje cells in conjunction with 4/sec olivary stimulation depressed the glutamate sensitivity of Purkinje cells; aspartate sensitivity was depressed to a much lesser degree. The depression diminished in about 10 min, but this recovery was succeeded by a slow depression lasting for an hour. The depression was seen only when glutamate sensitivity was relatively high, suggesting that the micro-electrode was impinging onto Purkinje cell dendrites. These observations suggest that subsynaptic chemosensitivity of Purkinje cells to the putative neurotransmitter of parallel fibres is involved in the depression observed after conjunctive stimulation of a vestibular nerve and the inferior olive. 6. The present results are consistent with the Marr-Albus assumption concerning plasticity of cerebellar neuronal networks. PMID:7097592

  19. A colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell

    NASA Astrophysics Data System (ADS)

    Zhang, Zhitao; Guo, Kunping; Li, Yiming; Li, Xueyi; Guan, Guozhen; Li, Houpu; Luo, Yongfeng; Zhao, Fangyuan; Zhang, Qi; Wei, Bin; Pei, Qibing; Peng, Huisheng

    2015-04-01

    The emergence of wearable electronics and optoelectronics requires the development of devices that are not only highly flexible but can also be woven into textiles to offer a truly integrated solution. Here, we report a colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell (PLEC). The fibre-shaped PLEC is fabricated using all-solution-based processes that can be scaled up for practical applications. The design has a coaxial structure comprising a modified metal wire cathode and a conducting aligned carbon nanotube sheet anode, with an electroluminescent polymer layer sandwiched between them. The fibre shape offers unique and promising advantages. For example, the luminance is independent of viewing angle, the fibre-shaped PLEC can provide a variety of different and tunable colours, it is lightweight, flexible and wearable, and it can potentially be woven into light-emitting clothes for the creation of smart fabrics.

  20. Multi Stage Fibre Optic Probes

    NASA Astrophysics Data System (ADS)

    Held, M.; Nikowitsch, P.

    1985-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  2. Elastic fibres in health and disease.

    PubMed

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

    2013-01-01

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

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

    PubMed Central

    Ishizuka, Hisao

    2012-01-01

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

  4. Durability under fatigue loading of optical fibres applied to fibre reinforced plastic composites

    NASA Astrophysics Data System (ADS)

    Herszberg, Israel; Bannister, Michael K.; Li, Henry C. H.; Qi, Ben; Marsden, Jane

    2007-07-01

    This paper summarises ongoing research conducted at the Cooperative Research Centre for Advanced Composite Structures (CRC-ACS) on the durability to fatigue loading of optical fibre sensors, which were surface mounted or embedded in fibre reinforced plastic composites. The objective of the research is to quantify the parameters affecting the fatigue performance of such optical fibres. Signal degradation of surface mounted and embedded Bragg grating sensors has been studied for a number of configurations. For some configurations, preliminary results indicate significant signal degradation on tension loaded optical fibres after 50,000 cycles strained to 4000 ?\\Vegr and this degradation has been linked with fibre cracking. No such cracking was observed in compression loaded optical fibres. The durability of the bonding at various interfaces of the optical fibre / composite system has been investigated for various polyimide coated fibres. After one million cycles to 3000 ?\\Vegr, 150 ?m diameter optical fibres exhibited significant disbonding in the coating / cladding interface of the optical fibre. Special 52 ?m diameter optical fibres also exhibited significant disbonding but to a lesser degree than that in the larger fibres. Stripped fibres exhibited no disbonding at the optical fibre to composite interface.

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

    SciTech Connect

    Kulchin, Yu N; Voznesenskii, S S; Galkina, A N; Mal'tseva, T L; Nagornyi, I G [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

    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)

  6. Formation of surface membranes in developing mammalian hair fibres.

    PubMed

    Jones, L N; Horr, T J; Kaplin, I J

    1994-01-01

    Mammalian hair fibres result from complex mechanisms involving synthesis, assembly and stabilisation of keratin proteins in the follicle. The developing hair shaft consists of outer cuticle cells surrounding cortical and medullary (optional) cell types. Presumptive fibre cuticle (FC) is contained by the inner root sheath (IRS) consisting of IRS cuticle, Huxley and Henle cells which are in turn enclosed in an outer root sheath (ORS) of epidermal-like cells. In the current structural studies we have used energy filtered transmission electron microscopy (Zeiss 902A) on Merino sheep skin biopsies to examine the fine sequence of morphological changes involved in forming the fibre surface membrane and the associated underlying structural bands comprising the a-layer and exocuticle. Prior to the development of the exocuticle, FC cells demonstrate a typical plasma-membrane apposed to IRS cuticle plasma-membranes separated by an intercellular space. The formation of exocuticular lamellae is followed by degradation of the residual FC surface membrane and the appearance of intercellular laminae demonstrating a stained central band. As maturation continues cleavage between IRS cuticle and FC occurs along this central band liberating hair into the pilary canal. The mature surface consists of keratinized cells containing a well developed exocuticle and a-layer coated with paired lamina (presumably two lipid containing bilayers) of material approximately 10-12 nm thick derived from the intercellular laminae. The current observations show FC surface formation is similar to processes occurring in epidermal stratum corneum and that the cuticle surface membrane of mammalian fibres is not derived from a modified plasma-membrane as previously documented. PMID:7881896

  7. PRECAUTIONS FOR THE STRUCTURALANALYSIS OF THE GELATINOUS LAYER IN TENSION WOOD

    E-print Network

    Paris-Sud XI, Université de

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

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

    PubMed Central

    2010-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

  11. Optical coherence tomography predicts visual outcome for pituitary tumors.

    PubMed

    Danesh-Meyer, Helen V; Wong, Aaron; Papchenko, Taras; Matheos, Kaliopy; Stylli, Stanley; Nichols, Andrew; Frampton, Chris; Daniell, Mark; Savino, Peter J; Kaye, Andrew H

    2015-07-01

    We evaluate if the relationship between optical coherence tomography (OCT) of the retinal nerve fibre layer (RNFL) and visual outcome continued over long-term visual recovery in 107 patients undergoing pituitary decompression. Recently, it has been recognized that OCT of the RNFL has prognostic value in predicting visual outcomes after surgery for chiasmal compression caused by pituitary tumours. Patients were followed up at three time points: pre-operative (visit 1), 6-10weeks post-operative (visit 2) and 9-15months follow-up (visit 3). We found that patients with thin pre-operative RNFL had more severe visual field defects (mean deviation [MD] -9.22 versus -3.96 decibels [dB]; p=0.001), but pre-operative visual acuity (VA) was good in both normal and thin RNFL groups (Snellen VA 6/5 and 6/4; p=0.039). For those with thin RNFL the greatest improvement was between visit 2 and 3 (MD -7.1dB versus -3.4dB, respectively; p<0.001) compared with pre-operative -9.8dB. Normal RNFL patients showed greatest improvement between visits 1 and 2 (pre-operative -4.8dB, visit 2 -2.0dB, visit 3 -0.9dB; p=0.001). For long-term follow-up, 81.0% of eyes with normal RNFL, compared to 37.1% with thin RNFL (p<0.001), achieved an MD of -2.00dB (final visit). At final follow-up, 97.5% of normal RNFL eyes achieved VA of 6/12 or better compared with 88.2% with thin RNFL (p=0.034). Our results indicate that long-term visual recovery after surgical decompression of pituitary lesions is predicted by pre-operative OCT RNFL. Patients with normal RNFL thickness show an increased propensity for visual recovery. This effect continues after long-term follow-up, however, most visual recovery occurs within the first 6-10weeks. PMID:25891894

  12. The effect of fibre diameter on filtration and flux distribution — relevance to submerged hollow fibre modules

    Microsoft Academic Search

    S Chang; A. G Fane

    2001-01-01

    This paper examines the effect of fibre diameter on filtration and flux distribution with inter-fibre two-phase flow for conditions relevant to submerged bioreactors (SMBR). Hollow fibres of different diameters fixed in a specially designed holder providing shell-side feed were tested for a model biomass feed with pumping and submerged systems. The experimental results showed that the effect of the fibre

  13. Fatigue behaviour of metallic fibre-reinforced materials: a study of steel fibre-reinforced silver

    Microsoft Academic Search

    G. Rosenkranz; V. Gerold; D. Stöckel; L. Tillmann

    1982-01-01

    Low-cycle fatigue tests were performed on silver matrix-steel-fibre-reinforced composites (FRC) with unidirectionally aligned fibres of constant volume-fraction,Vf=0.35. The influence of various material parameters, namely the fibre and matrix strengths, the interfacial bond strength and the mean fibre diameter, was examined. Low-cycle fatigue hardening and softening of FRCs deviate from the behaviour expected from the properties of the components. The differences

  14. Cone calorimeter study of high performance fibres—application to polybenzazole and p-aramid fibres

    Microsoft Academic Search

    Serge Bourbigot; Xavier Flambard; Franck Poutch; Sophie Duquesne

    2001-01-01

    This work investigates the fire behaviour of high performance fibres. Poly-p-phenylenediamine-terephtalamide fibres (PPT) and poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibres as knitted fabrics are evaluated using the cone calorimeter as fire model. The investigation of the fire performance of the PPT and PBO fibres shows the excellent behaviour of PBO in comparison with PPT. The contribution to fire growth of PBO is very

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

    PubMed Central

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

    2008-01-01

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

  16. Mechano-sorptive creep in wood fibres

    Microsoft Academic Search

    Anne-Mari Olsson; Lennart Salmén; Michaela Eder; Ingo Burgert

    2007-01-01

    In order to investigate the way in which fibre properties affect the mechano-sorptive creep phenomenon in paper, single wood\\u000a fibres were exposed to tensile stresses at a constant humidity of 80% relative humidity (RH) and in a cyclic humidity environment\\u000a varying between 80 and 30% RH. Contrary to earlier claims, it was demonstrated that single wood fibres exposed to a

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

    Microsoft Academic Search

    Nguyen Nhut Xuan Dung; Luu Huu Manh; Peter Udén

    2002-01-01

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

  18. Interfacial studies of natural fibre\\/polypropylene composites using single fibre fragmentation test (SFFT)

    Microsoft Academic Search

    A. Awal; G. Cescutti; S. B. Ghosh; J. Müssig

    2011-01-01

    For the potential use and new applications of natural fibre reinforced plastics, it is crucial that the mechanical behaviour of these composites is fully understood. Single fibre fragmentation tests (SFFT) were carried out to compare the fragmentation phenomenon in two natural fibres\\/polypropylene (PP) composites. Polypropylene was used with maleic anhydride (MAPP) as a coupling agent for this study. The SFFT

  19. Surface treated polypropylene (PP) fibres for reinforced concrete

    SciTech Connect

    López-Buendía, Angel M., E-mail: buendia@uv.es [AIDICO Technological Institute of Construction, Benjamin Franklin 17, 46380 Paterna, Valencia (Spain); Romero-Sánchez, María Dolores [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain)] [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain); Climent, Verónica [Lafarge Cementos, Polígono Sepes, Isaac Newton s/n, 46500 Sagunto, Valencia (Spain)] [Lafarge Cementos, Polígono Sepes, Isaac Newton s/n, 46500 Sagunto, Valencia (Spain); Guillem, Celia [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain)] [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain)

    2013-12-15

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

  20. Space-division multiplexing in optical fibres

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  2. A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Weber, M.; van Haag, J.; Schöngart, M.

    2015-05-01

    To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material's properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

  3. Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50?mol% P2O5.

    PubMed

    Sharmin, Nusrat; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

    2014-11-01

    Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P2O5 content less than 50?mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 contents fixed at 40, 45 and 50?mol%, where Na2O was replaced by 5 and 10?mol% B2O3 and MgO and CaO were fixed to 24 and 16?mol%, respectively. The effect of B2O3 addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10?mol% B2O3 enabled successful drawing of continuous fibres from glasses with phosphate (P2O5) contents fixed at 40, 45 and 50?mol%. The mechanical properties of the fibres were found to significantly increase with increasing B2O3 content. The highest tensile strength (1200?±?130?MPa) was recorded for 45P2O5-16CaO-5Na2O-24MgO-10B2O3 glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37? for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B2O3-containing glass fibres were found to degrade at a much slower rate as compared to the non-B2O3-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation. PMID:24939962

  4. Combining Ability Analysis of Fibre Characteristics in Gossypium hirsutum L

    Microsoft Academic Search

    MUHAMMAD TEHSEEN AZHAR; ASIF ALI KHAN; NASIR MAHMOOD

    In order to study the genetic basis of fibre characters of Gossypium hirsutum L. lint four varieties namely, MNH-554, Delcerro, Coker-304 and Albacala (71)1190 were crossed in all possible combinations. The genetic analysis of the F1 data showed that effects of general combining ability were significant for fibre length, fibre fineness, fibre strength, fibre whiteness and fibre yellowness as affected

  5. Myofibrillar fatigue versus failure of activation during repetitive stimulation of frog muscle fibres.

    PubMed Central

    Edman, K A; Lou, F

    1992-01-01

    1. Single fibres isolated from the anterior tibialis muscle of Rana temporaria (temperature, 2-5 degrees C; sarcomere length, 2.10 microns) were fatigued using two separate protocols that led to different degrees of depression of tetanic force. Under control conditions the fibre was stimulated to produce a 1 s fused isometric tetanus at 300 s intervals. A moderate degree of fatigue (tetanic force reduced to 70-80% of the control value) was produced by decreasing the intervals between tetani to 15 s ('fatiguing protocol 1'). A more pronounced depression of tetanic force (to 40-50% of the control value) was produced by evoking a single twitch at 1-2 s intervals ('fatiguing protocol 2'). 2. Fatiguing protocol 1 reduced the contracture response to submaximal and supramaximal concentrations of caffeine (3-15 mM) in proportion to the decrease in tetanic force. These results support the view that fatiguing stimulation according to protocol 1 leads to a true 'myofibrillar fatigue' with no failure of activation of the muscle fibre. 3. Fatiguing protocol 2 reduced the amplitudes of isometric twitch and tetanus to below 10 and 50% of the control values, respectively. By contrast, the maximal contracture response to caffeine (15 mM) was depressed by merely 2-3% of its prefatigue value. 4. Force and instantaneous fibre stiffness were recorded simultaneously during twitch and tetanus as fatigue was induced by protocol 2. During the initial part of fatigue (tetanic force reduced by 25% of control) stiffness was reduced by merely 9% in accordance with previous measurements during fatigue induced by protocol 1. However, with further depression of twitch and tetanus by protocol 2 there was a marked reduction of fibre stiffness. These results, together with the findings reported under point 3, strongly suggest that at an advanced state of fatigue induced by protocol 2 the decrease in active force is largely due to failure of activation of the contractile system. 5. Muscle fibres were quickly frozen for electron microscopical examination after shortening below slack length (to approximately 1.6 microns sarcomere spacing) during tetanic stimulation. In non-fatigued fibres, and in fibres fatigued according to protocol 1, the myofibrils exhibited a straight appearance throughout the preparation suggesting that the entire volume of the fibre was properly activated. In fibres fatigued by protocol 2, on the other hand, only the most peripheral layers of myofibrils remained straight after shortening, whereas the centre of the fibre showed marked waviness indicating failure of the inward spread of activation in this case. Images Fig. 8 PMID:1297847

  6. 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

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

    2014-02-21

    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

  7. Welding of glass fibres onto large-scale substrates with high mechanical stability and optical quality

    NASA Astrophysics Data System (ADS)

    Schaefer, Lorenz; Schmidt, Michael

    In optical data transmission, adherence is the common method for joining optical components like fibres and lenses. Adhesive joints however have some disadvantages. The transmittable optical power is limited and the boundary layer causes undesired reflections. An alternative method for joining fibers with lenses is welding using CO2 laser radiation. The irradiation pattern is designed in such a way, that the fibre is welded to the substrate around its whole circumference. Therefore a ring shaped beam is formed by a novel focusing device based on the Schwarzschild objective. The results of the welding experiments show significantly improved characterisitcs of the joint.

  8. The fatigue behaviour of Kevlar-29 fibres

    Microsoft Academic Search

    M. H. Lafitte; A. R. Bunsell

    1982-01-01

    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

  9. CONCENTRATION OF NUCLEI IN CHICKEN MUSCLE FIBRE

    E-print Network

    Paris-Sud XI, Université de

    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

  10. Development of the fibres of MOONS

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  11. Fibring of Logics as a Categorial Construction

    E-print Network

    Lisboa, Universidade Técnica de

    )cartesian liftings are concerned. When establishing the category of interpretation systems we face some foundational fibring as a coproduct. Fibring with shared symbols is then easily obtained by cocartesian lifting from­ egorial constructions, using coproducts and cocartesian liftings. Note that we allow the sharing of any

  12. Radial distribution function analysis of coir fibre

    Microsoft Academic Search

    D. N. Mahato; B. K. Mathur; S. Bhattacherjee

    1993-01-01

    Radial distribution analysis of X-ray intensities diffracted by natural coir fibre subjected to various thermal and mercerization treatments has been carried out. Interatomic distances, mean square displacements and interatomic coupling constants have been obtained from the radial distribution curves. As coir fibre finds its various applications in its natural form, its study has been carried out without disturbing the configuration

  13. Optical Fibre Sensors 18 (OFS-18)

    Microsoft Academic Search

    Julian D C Jones; Ralph P Tatam

    2007-01-01

    The International Conference on Optical Fibre Sensors (OFS-18) was held in October 2006 in Cancn, Mexico, under the general chairmanship of Dr Alexis Mendez (MCH Engineering LLC, USA) and Dr Fernando Mendoza (Centro de Investigaciones en Optica, Mexico). 'OFS', as it has become known, is firmly established as the leading international conference for the optical fibre sensor community. Since its

  14. EDITORIAL: Optical Fibre Sensors 18 (OFS-18)

    Microsoft Academic Search

    Julian D. C. Jones; Ralph P. Tatam

    2007-01-01

    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

  15. Amphibole fibres in Chinese chrysotile asbestos.

    PubMed

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

    2001-03-01

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

  16. Continuous conduction in demyelinated mammalian nerve fibres

    Microsoft Academic Search

    H. Bostock; T. A. Sears

    1976-01-01

    MYELINATED nerve fibres conduct in a saltatory fashion, with sites of inward membrane current restricted to the nodes of Ranvier1. Loss of myelin causes long delays in the inter nodal conduction time, extreme refractoriness and conduction block2. In the large rat ventral root fibres studied the slowed conduction always remained saltatory, with discrete sites of inward current, but the limited

  17. Magnetic study of elongated polypropylene fibres

    Microsoft Academic Search

    M. Rákos; R. Šimo; Z. Varga

    1966-01-01

    A study is made of the magnetic properties of polypropylene fibres (PP) subjected to permanent unidirectional deformation at room and higher temperatures of the medium (120°C). It follows from the results that the values of the magnetic susceptibility, measured perpendicular to the axis of the fibres, change as a function of the relative elongation while they express the changes in

  18. Minimum ignition energy of nylon fibres

    Microsoft Academic Search

    L. Marmo; D. Cavallero

    2008-01-01

    The aim of this paper is to provide new experimental data on the minimum ignition energy (MIE) of clouds of fibres dispersed in the air. Nylon fibres from an Italian flock manufacturer (diameter between 10 and 27.4?m, length between 600 and 1800?m) were collected and tested in a modified Hartmann tube in order to measure the MIE. The instrument is

  19. Gas permeation of fibre reinforced plastics

    Microsoft Academic Search

    Jens Humpenöder

    1998-01-01

    Propulsion with liquid hydrogen or methane is under development. Storage and transportation of these fuels is part of these activities. Lightweight vessels out of fibre composites are promising candidates. Their disadvantage might be gas permeation, especially when exposed to mechanical and thermal cycling. For several applications of superconducting magnets (pulsed magnets, SQUID detectors), non-metallic and non-magnetic cryostats are required. Fibre

  20. Bicomponent Meltblown Nonwovens and Fibre Splitting

    Microsoft Academic Search

    Dong Zhang; Yanbo Liu; Jihua Xiao

    2004-01-01

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

  1. Laser based coating and modification of carbon fibres: application of industrial lasers to manufacturing of composite materials

    NASA Astrophysics Data System (ADS)

    Hopfe, V.; Jäckel, R.; Schönfeld, K.

    1996-10-01

    For high temperature applications of fibre reinforced ceramic composites, the adhesion, and chemical reactions at the fibre-matrix interface, has to be engineered by coating the fibres. Based on a technological 5 kW cw-CO 2 laser, an atmospheric pressure laser assisted CVD process has been established performing a continuous high rate coating of carbon fibre rovings. Layers of pyrolytic carbon have been deposited from CH 4 with a rate of 0.6 ?m/s, which enhances the tensile strength and Weibull modulus of fibres. The design of the LCVD reactor and the optimization of its operational conditions are supported by computational fluid dynamics techniques. The gas flow dynamics, concentration of species and heat tranfer in the reaction chamber have been calculated. Within the symmetrical chamber a flow regime is established with a free standing laminar gas flow around the fibre tape which shields the reaction zone against purge gases. The diffusion limited deposition rate of this configuration is estimated. The influence of laser irradiation on mechanical properties and structure of the carbon fibres have been checked by tensile (bundle) testing, SEM/EDX, XRD and Raman spectroscopy. The detected changes indicate a complex dependence on irradiation time, laser power and gaseous ambient.

  2. Fibre Optic Data Links For Military Applications

    NASA Astrophysics Data System (ADS)

    Coden, Michael H.; Blott, Paul A.

    1984-08-01

    Fibre optics provide many advantages in conventional strategic, tactical, ground base and airbourne military situations. These include security, small size and light weight of both cable and electronics, lower power consumption of electronics and immunity to EMI, EMP and RFI just as in the commercial uses of fibre optics. In many military applications the advantages of fibre optics may be critical to mission performance. A major stumbling block has been the development of fibre optic components and systems that meet the environmental, reliability and maintainability requirements of military equipment. Bearing these requirements in mind, this paper identifies some of the techniques used and recent advances made by Codenoll Technology in producing fibre optic data links suitable for military use. Some general tactical and strategic military applications involving these data links will then be discussed.

  3. Dietary fibre and coronary heart disease.

    PubMed

    Mia, M A R; Siddiqui, M N I; Haque, M S; Islam, M N; Rukunzzaman, M; Deb, K

    2002-07-01

    Intake of dietary fibres lowers plasma lipids. Fibres particularly soluble ones lower serum total cholesterol (TC) and serum low-density lipoprotein cholesterol (LDL-C) without significant alteration in serum high-density lipoprotein cholesterol (HDL-C) and triacylglyccrol (TG). Consequently, the incidence of atherosclerotic heart diseases is lower in those who take high dietary fibre. Persons taking diet rich in saturated fat and poor in dietary fibre is more prone to develop coronary artery diseases. Dietary fibres also lower TC: HDL-C and LDL-C: HDL-C ratios. Higher TC: HDL-C and LDL-C: HDL-C ratios are in favour of development and progression of atherosclerotic vascular diseases, a pioneer cause of myocardial infarction (MI). PMID:12395688

  4. Supercontinuum generation in thulium-doped fibres

    SciTech Connect

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

    2012-09-30

    Supercontinuum generation in thulium-doped fibres under pumping at 1.59 {mu}m is investigated. Amplification of supercontinuum in the range of 1.8--2.0 {mu}m is found for a fibre doped to a level of 2 Multiplication-Sign 10{sup 19} cm{sup -3}. For a fibre with an activator concentration of 2 Multiplication-Sign 10{sup 20} cm{sup -3} amplification is also observed in the (2.1 - 2.45)-{mu}m band, which suggests the occurrence of the {sup 3}H{sub 4} {yields} {sup 3}H{sub 5} optical transition in the fibre. The occupation of the {sup 3}H{sub 4} level can be explained by cooperative effects. (optical fibres, lasers and amplifiers. properties and applications)

  5. Erbium-doped aluminophosphosilicate optical fibres

    SciTech Connect

    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

    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)

  6. EDITORIAL: Optical Fibre Sensors 18 (OFS-18)

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    The International Conference on Optical Fibre Sensors (OFS-18) was held in October 2006 in 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

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

    PubMed

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

    2015-01-01

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

  8. Influence of Slip on the Plateau-Rayleigh Instability on a Fibre

    E-print Network

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

    2015-05-24

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

  9. Influence of slip on the Plateau–Rayleigh instability on a fibre

    PubMed Central

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

    2015-01-01

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

  10. Effects of Extrusion on Fibre Length in Sisal Fibre-Reinforced Polypropylene Composites

    NASA Astrophysics Data System (ADS)

    Pathi, Sridhar; Jayaraman, Krishnan

    Natural fibre reinforced thermoplastic composites find a wide array of applications in the automobile, building and construction industries. These composites are mostly produced by injection moulding or extrusion through properly designed dies. During these production processes, the shear forces exerted by the screw or ram leads to the degradation of the natural fibres. A screwless extruder that minimises fibre degradation and employs a reliable and low technology process has already been developed. However, the fibre degradation caused by the screwless extruder has not been compared with that of the conventional extruders. So, this study is focused on the influence of extrusion processes on the degradation of natural fibres in thermoplastic composites. Sisal fibres of 10 mm length were extruded with polypropylene, to furnish extrudates with a fibre mass fraction of 25%, using conventional single screw and screwless extruders. Polypropylene in the extrudates was dissolved in Xylene in a Sohxlet process; the fibres that were extracted were analysed for length variations. While fibre degradation in the form of fibre length variation is similar in both cases, this can be minimised in screwless extrusion by extending the gap between the front face of the cone and the orifice plate.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre's properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment.

  12. Diagnostic Ability of Macular Ganglion Cell Inner Plexiform Layer Measurements in Glaucoma Using Swept Source and Spectral Domain Optical Coherence Tomography

    PubMed Central

    Yang, Zhiyong; Tatham, Andrew J.; Weinreb, Robert N.; Medeiros, Felipe A.; Liu, Ting; Zangwill, Linda M.

    2015-01-01

    Purpose To evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements. Methods The study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes. Results Mean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements. Conclusion Assessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection. PMID:25978420

  13. High-temperature behaviour of HPC with polypropylene fibres

    Microsoft Academic Search

    Pierre Kalifa; Grégoire Chéné; Christophe Gallé

    2001-01-01

    The addition of polypropylene (PP) fibres to high-performance concrete (HPC) is one way to avoid spalling of concrete under fire conditions. The present work contributes both to the understanding of the way in which fibres act and to optimising the fibre dosage. Pore pressure measurements performed on heated specimens showed that the presence of fibres led to a large decrease

  14. Restoring Strength to Recycled Fibres by Blending with Kenaf Pulp

    Microsoft Academic Search

    S. Mahmudin

    2009-01-01

    Recycled fibres are important sources for paperboard industry in Malaysia. There are various approaches to enhance the strength of recycled fibres which include mechanical treatment, chemical addition, and physical fractionation as well as blending with virgin fibres. In this study, the old corrugated containers (OCC) pulp was subjected to blending with virgin fibres of kenaf pulp. The OCC pulp was

  15. The characteristics of a quartz-fibre electroscope

    Microsoft Academic Search

    F. Harlen

    1954-01-01

    The deflecting element of the electroscope is a conducting fibre mounted parallel to a support rod and kept taut by a quartz-fibre loop. A theory is developed which describes the mechanical restoring forces acting on a deflected fibre and shows how manufacturing tolerances may be accommodated so that all electroscopes conform to a given non-linear calibration curve. Experimental fibre deflexion

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

    Microsoft Academic Search

    Jinshui Wang; Cristina M Rosell; Carmen Benedito de Barber

    2002-01-01

    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.

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

    E-print Network

    Bristol, University of

    1996-01-01

    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

  18. Fibre-reinforced composites in restorative dentistry.

    PubMed

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

    2003-01-01

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

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

    SciTech Connect

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

    2014-01-01

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

  20. Radio-over-fibre distribution using an optical D-fibre antenna

    NASA Astrophysics Data System (ADS)

    Bhatti, A.; Al-Raweshidy, H. S.; Murtaza, G.

    2001-04-01

    Finite element analysis has been used to characterise an all-fibre antenna using circular core D-fibre. The optical D-fibre carrying a transversely poled piezoelectric polyvinylidene fluoride polymer coating was modelled by using three-dimensional stress analysis. The response of the D-fibre antenna was determined over a wide frequency range from 1 to 800 MHz. The modelling predicts that the electric-field-induced strains will cause a phase shift of 2.43×10 -5 rad/( V/ m) per metre at 5 MHz. At frequencies higher than 8 MHz, the optical response is dominated by radial resonances of the D-fibre/coating composite. Using the simulation results, an electric-field-induced phase shift of 7.35×10 -5 rad/( V/ m) per metre has been obtained. An increase in phase modulation sensitivity by a factor of three compared to conventional circular fibre has been achieved by utilising the unique properties of the D-fibre structure. The D-fibre antenna has potential applications in areas such as EMC testing and radio-over-fibre networks where it provides a convenient means of optically generating radio signals.

  1. Optical antenna using D-fibre for radio-over-fibre applications

    NASA Astrophysics Data System (ADS)

    Bhatti, A.; Al-Raweshidy, H. S.; Murtaza, G.

    2002-04-01

    Finite element analysis has been used to characterize an all-fibre antenna using circular core D-fibre. The optical D-fibre carrying a transversely poled piezoelectric polyvinylidene fluoride (PVDF) polymer coating was modeled by using three-dimensional stress analysis. The response of the D-fibre antenna was determined over a wide frequency range from 1 to 700 MHz. The modeling predicts that the electric field induced strains will cause a phase shift of 2.43×10 -5 rad/(V/m) per metre at 5 MHz. At frequencies higher than 8 MHz the optical response is dominated by radial resonances of the D-fibre/coating composite. Using the simulation results, an electric field induced phase shift of 7.35×10 -5 rad/(V/m) per metre has been obtained. An increase in phase modulation sensitivity by a factor of three compared to conventional circular fibre has been achieved by utilizing the unique properties of the D-fibre structure. The D-fibre antenna has potential applications in areas such as EMC testing and radio-over-fibre networks where it provides a convenient means of optically generating radio signals.

  2. An all-fibre robust and tunable Raman fibre laser with reconfigurable asymmetric cavities

    NASA Astrophysics Data System (ADS)

    Im, Young-Eun; Hann, Swook; Kim, Hangeul; Kim, Dong-Hwan; Park, Chang-Soo

    2009-03-01

    A robust Raman fibre laser (RFL) for tunable and multiple outputs has been proposed using an all-fibre asymmetric cavity which is composed of a wideband chirped fibre Bragg grating (CFBG) and narrowband tunable fibre Bragg gratings (TFBGs). The wideband CFBG has high reflectivity across the spectral range from 1404 to 1465 nm as an input reflector. Output couplers (OCs) consist of three TFBGs with center wavelengths of 1410, 1425 and 1440 nm, respectively, which can each be tuned over 10 nm. The output power and wavelength can be flexibly controlled by tuning of TFBGs in the 14xx nm band.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  4. 3D Non-Woven Polyvinylidene Fluoride Scaffolds: Fibre Cross Section and Texturizing Patterns Have Impact on Growth of Mesenchymal Stromal Cells

    PubMed Central

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

    2014-01-01

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

  5. Enhancing the radiation dose detection sensitivity of optical fibres.

    PubMed

    Bradley, D A; Mahdiraji, G Amouzad; Ghomeishi, M; Dermosesian, E; Adikan, F R M; Rashid, H A A; Maah, M J

    2015-06-01

    A method for improving the thermoluminescence (TL) yield of silica-based optical fibres is demonstrated. Using silica obtained from a single manufacturer, three forms of pure (undoped) fibre (capillary-, flat-, and photonic crystal fibre (PCF)) and two forms of Ge-doped fibre (capillary- and flat-fibre) were fabricated. The pure fibre samples were exposed to 6 and 21MeV electrons, the doped fibres to 6MV photons. The consistent observation of large TL yield enhancement is strongly suggestive of surface-strain defects generation. For 6MeV irradiations of flat-fibre and PCF, respective TL yields per unit mass of about 12.0 and 17.5 times that of the undoped capillary-fibre have been observed. Similarly, by making a Ge-doped capillary-fibre into flat-fibre, the TL response is found to increase by some 6.0 times. Thus, in addition to TL from the presence of a dopant, the increase in fused surface areas of flat-fibres and PCF is seen to be a further important source of TL. The glow-curves of the undoped fibres have been analysed by computational deconvolution. Trap centre energies have been estimated and compared for the various fibre samples. Two trap centre types observed in capillary-fibre are also observed in flat-fibre and PCF. An additional trap centre in flat-fibre and one further trap centre in PCF are observed when compared to capillary fibre. These elevated-energy trap centres are linked with strain-generated defects in the collapsed regions of the flat fibre and PCF. PMID:25533626

  6. Shrinkage of steel fibre reinforced cement composites

    Microsoft Academic Search

    P. S. Mangat; M. Motamedi Azari

    1988-01-01

    The paper presents results of an experimental investigation on the influence of steel fibres on the free shrinkage of cement-based\\u000a matrices. Shrinkage tests were carried out on cement paste, mortar and two types of concrete mixes for a period of up to 520\\u000a days. Melt extract, crimped and hooked steel fibres were used for reinforcement at volume fractions ranging between

  7. A high-temperature fibre testing facility

    Microsoft Academic Search

    E. Lara-Curzio; S. S. Sternstein

    1991-01-01

    A multiple-unit fibre tester with a controlled environment and fully computerized data acquisition and control has been designed and constructed to study the thermomechanical behaviour of fibres at high temperatures. High temperatures are achieved by a self-resistance heating technique, strains are estimated from displacement measurements using LVDTs, while temperature is measured using a two-colour infrared pyrometer. In the determination of

  8. Thermal Characteristics of Para-Aramid Fibres

    Microsoft Academic Search

    K. E. Perepelkin; I. V. Andreeva; E. A. Pakshver; I. Yu. Morgoeva

    2003-01-01

    Comparative studies of the thermal characteristics of para-aramid fibres (Armos, Rusar, Terlon, Twaron, and Kevlar) were conducted using thermomechanical analysis (TMA), dynamic thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). According to the TMA data, the para-aramid fibres studied are characterized by dimensional stability up to temperatures of 400-450°C; shrinkage or spontaneous elongation does not exceed 0.5-1%. TGA and DSC

  9. Dietary fibre in foods: a review

    Microsoft Academic Search

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

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

  10. Simulation of single muscle fibre action potentials

    Microsoft Academic Search

    S. D. Nandedkar

    1983-01-01

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

  11. Fibre-optic sensors in health care

    NASA Astrophysics Data System (ADS)

    Grazia Mignani, Anna; Baldini, Francesco

    1997-05-01

    Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are able to offer in different application fields such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology and dentistry.

  12. Fibre-optic sensors in health care.

    PubMed

    Mignani, A G; Baldini, F

    1997-05-01

    Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are able to offer in different application fields such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology and dentistry. PMID:9172270

  13. Oxidation protection for carbon fibre composites

    Microsoft Academic Search

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

    1996-01-01

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

  14. Microstructure characterization of erosion resistant coatings on carbon-bonded carbon fibre composites.

    PubMed

    Moskalewicz, T; Smeacetto, F; Salvo, M; Boccaccini, A R; Czyrska-Filemonowicz, A

    2010-03-01

    The microstructure of as received and surface treated carbon-bonded carbon fibre composites has been examined by light microscopy, scanning and transmission electron microscopy. The microstructure of the as received material consists of a bonded together layered carbon fiber network, identified as graphitic carbon (hexagonal close packed). To improve the erosion resistance of the carbon-bonded carbon fibre composites composite, the SiC and silicate glass-ceramic coatings from the system SiO(2)-Al(2)O(3)-Y(2)O(3) were produced on carbon-bonded carbon fibre composites composites by a low-cost slurry technique. Transmission electron microscopy investigations of cross-section thin foils allowed for detailed analysis of the coatings microstructure. It was found that the SiC coating was consisting mainly of a nanocrystalline SiC (fcc). The multilayered glass-ceramic coating showed a complex microstructure consisting of an external SiO(2)-Al(2)O(3)-Y(2)O(3) layer and an intermediate nanocrystalline SiC layer. The SiO(2)-Al(2)O(3)-Y(2)O(3) layer was composed of SiO(2) (fcc), Y(2)Si(2)O(7) (op) and Al(4.644)Si(1.357)O(9.68) (op). PMID:20500382

  15. Economics Of Optical Fibre Transmission Systems

    NASA Astrophysics Data System (ADS)

    Murray, W. J.

    1983-08-01

    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.

  16. Reinforcing of Cement Composites by Estabragh Fibres

    NASA Astrophysics Data System (ADS)

    Merati, A. A.

    2014-04-01

    The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Resonantly pumped holmium fibre lasers present a range of opportunities for the development of novel fibre laser and amplifier devices due to the availability of mature, efficient high power thulium fibre pump lasers. In this paper we describe the operation of a large mode area holmium-doped fibre amplifier. The master-oscillator is an all-fibre linearly polarised, core pumped single mode laser operating at 27 W at 2.11 ?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.

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

    PubMed

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

    2014-11-01

    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

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

    Microsoft Academic Search

    Mangilal Agarwal; Yuri Lvov; Kody Varahramyan

    2006-01-01

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

  20. Bending strength and static fatigue of glass fibre in different atmospheres by fibre loop test

    Microsoft Academic Search

    Pentti K. Järvelä

    1984-01-01

    This study deals with the dependence of glass-fibre bending strength and static fatigue on different factors, mainly the ambient atmosphere. The fracture diameter of a loop (as measured by the loop test), which is proportional to the bending strength, was found to be dependent on the diameter of the fibre, as well as on the water concentration of the ambient

  1. Structural study of adenovirus type 2 fibre using anti-fibre and anti-peptide sera.

    PubMed

    Caillet-Boudin, M L; Novelli, A; Gesquière, J C; Lemay, P

    1988-01-01

    Peptides corresponding to the N- and C-extremities of the adenovirus 2 fibre polypeptide were synthesized, coupled to tetanus toxoid and injected into rabbits. Two sera were obtained: the anti-NTT serum and the anti-CTT serum. These sera and an anti-native-fibre serum were used to study fragments generated by hydrochloric acid cleavage of the fibre. The 44-Kd fragment corresponding to the 2/3 N-terminal part of the molecule retained its antigenic reactivity. This is consistent with a shaft structure for this part of the fibre. The anti-peptide sera were used to orientate the fibre, i.e., to determine the site of anchorage of this protein in the penton base. First, immunorevelation of blots of enzymatic digests of native or dissociated penton suggested that the N-extremity of the fibre was involved in the assembly of this protein in the penton base. Second, attempts were made to determine the accessibility of the fibre ends in the penton structure by ELISA assays and by immunorevelation of penton in Western blots. The results agreed with the proposed orientation derived from study of the enzymatic digests. Since the 2 anti-peptide sera and the peptides were unable to affect viral adsorption, it was not possible to determine how the fibre is orientated with respect to the cell receptor. However, the anti-peptide sera were found to inhibit viral production slightly. PMID:3155400

  2. Spun microstructured optical fibres for Faraday effect current sensors

    SciTech Connect

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

    2009-11-30

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

  3. Fatigue Damage Characterization by NDT in Polypropylene/Glass Fibre Composites

    NASA Astrophysics Data System (ADS)

    Reis, Paulo N. B.; Ferreira, José A. M.; Richardson, Mel O. W.

    2011-10-01

    This paper presents the results of a study on glass-fibre-reinforced polypropylene composite in which the fatigue damage was investigated in terms of residual stiffness and temperature rise. Thermographic and acoustic emission techniques were used to aid the interpretation the fatigue damage mechanisms. Different laminates were tested. For one series, all the layers have one of the two fibre directions oriented with the axis of the plate. For the other two series layer distribution was obtained with the following laminate orientation in respect to the axis of the sheet: +45°/0°/-45°/0°/+45°/0°/-45° and +30°/-30°/+30°/0°/+30°/-30°/+30°. It was possible to conclude that the residual stiffness and temperature rise can be used to predict final failure of a structure and/or component. With thermographic technique it is possible to obtain temperature maps and the precise site where the failure will occur.

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

    SciTech Connect

    Zagorul'ko, K A; Kryukov, P G; Dianov, Evgenii M [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

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

  5. Development of a fibre optic sensor for the detection of harmful algae bloom and in particular domoic acid

    Microsoft Academic Search

    E. O'Connell; W. B. Lyons; C. Sheridan; E. Lewis

    2007-01-01

    Research into an early warning harmful algae bloom (HAB) sensing system for use in underwater monitoring applications is presented. The sensor proposed by the authors utilises principal component analysis (PCA) to establish the complex linkages between ocean colour, absorption and scattering, algae pigmentation and cell size, along with depth of bloom layers. The authors are proposing an optical fibre sensor

  6. Voronoi cells, fractal dimensions and fibre composites.

    PubMed

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

    2001-02-01

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

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

    PubMed Central

    Hotte, Naomi SC; Deyholos, Michael K

    2008-01-01

    Background Bast fibres from the phloem tissues of flax are scientifically interesting and economically useful due in part to a dynamic system of secondary cell wall deposition. To better understand the molecular mechanisms underlying the process of cell wall development in flax, we extracted proteins from individually dissected phloem fibres (i.e. individual cells) at an early stage of secondary cell wall development, and compared these extracts to protein extracts from surrounding, non-fibre cells of the cortex, using fluorescent (DiGE) labels and 2D-gel electrophoresis, with identities assigned to some proteins by mass spectrometry. Results The abundance of many proteins in fibres was notably different from the surrounding non-fibre cells of the cortex, with approximately 13% of the 1,850 detectable spots being significantly (> 1.5 fold, p ? 0.05) enriched in fibres. Following mass spectrometry, we assigned identity to 114 spots, of which 51 were significantly enriched in fibres. We observed that a K+ channel subunit, annexins, porins, secretory pathway components, ?-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

  8. Efficient finite element modelling of reinforced concrete beams retrofitted with fibre reinforced polymers

    Microsoft Academic Search

    M. Barbato

    2009-01-01

    This paper presents a new simple and efficient two-dimensional frame finite element (FE) able to accurately estimate the load-carrying capacity of reinforced concrete (RC) beams flexurally strengthened with externally bonded fibre reinforced polymer (FRP) strips and plates. The proposed FE, denoted as FRP–FB-beam, considers distributed plasticity with layer-discretization of the cross-sections in the context of a force-based (FB) formulation. The

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

    Microsoft Academic Search

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

    2011-01-01

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

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

    PubMed

    Baker; Grant; Jenkins

    1999-11-01

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

  11. Baseband Frequency Response Of Multimode Fibres

    NASA Astrophysics Data System (ADS)

    Chapman, J. E. G.

    1986-04-01

    The correlation of the baseband frequency response of single lengths of multimode fibre with that of an assembled set of such fibres has remained one of their most unsatisfactory features. Many approaches to this problem have yielded only partial success in a predictive sense, despite their effectiveness in accounting, after the event, for observed experimental results. The common feature among most predictive procedures is an assumption of 'good behaviour' of the fibres involved. Others have attempted to take into account 'rogue behaviour' (fibres having modes separable into distinctly fast and slow groups) by manipulation of the transfer function, in either time or frequency domains, in an effort to derive a frequency parameter leading to a consistently applicable predictive theory. The motivation, apart from scientific thirst for knowledge and understanding, has been economic. An algorithm enabling a required system performance to be achieved with certainty, without an excessive margin, and using the most readily available, lowest-cost fibre would clearly be a desirable outcome. Has such an outcome been attained? If so, to what extent, and under what conditions? Does the complexity of the available algorithms in any way detract from their practical utility and economic benefit? Are there better, simpler ways of achieving the end result? The author is of the opinion that the problems, scientifically fascinating though they are, are likely to remain largely unsolved, because in the end, they will not be worth solving.

  12. A 1.65-{mu}m fibre Raman amplifier

    SciTech Connect

    Kurkov, Andrei S; Paramonov, Vladimir M; Egorova, O N; Medvedkov, O I; Dianov, Evgenii M; Zalevskii, I D; Goncharov, S E [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-08-31

    A fibre Raman amplifier operating at a wavelength of 1.65-{mu}m is fabricated. A two-stage phosphosilicate fibre Raman converter of 1.53-{mu}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 {mu}m. A fibre with a core of a high (25%) molecular content of GeO{sub 2} serves as an active medium for the Raman amplifier. The gain obtained for different powers of the input signal is 22 - 25 dB. Our calculations show that the use of a standard telecommunication fibre (with a lower content of GeO{sub 2}) allows one to increase the gain in this scheme by reducing fibre splicing losses. (fibre optics. optical fibres)

  13. Crystalline silicon core fibres from aluminium core preforms.

    PubMed

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

    2015-01-01

    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

  14. Development of fibre-metal laminates for improved impact performance

    NASA Astrophysics Data System (ADS)

    Morinière, F. D.; Alderliesten, R. C.; Benedictus, R.

    2012-05-01

    An analytical and experimental investigation into the low-velocity behaviour of GLARE Fibre-Metal Laminates (FMLs) has been performed. A quasi-static approach was developed to estimate the perforation energy absorbed between the constituents of GLARE. The analysis considered contact area increase during perforation and strain rate effect on material properties. Particular attention was paid to the effect of ply-angle orientation and aluminium position. Predicted maximum impact force, maximum displacement, and perforation energy related to impact velocity were within 10% of test results. Stacking composite plies oriented along the diagonal of the plate with more than 2 aluminium layers leads to a more impact resistant FML. The generic nature of the developed methodology can support the optimization of high-performance FML concepts.

  15. Superoxide anion release by alveolar macrophages exposed to respirable industrial fibres: modifying effect of fibre opsonisation.

    PubMed

    Donaldson, K; Hill, I M; Beswick, P H

    1995-09-01

    Phagocyte-derived free radicals are considered to play a role in fibre-related pathology and the components of the lung lining fluid could modify the surface of fibres. Therefore we examined the ability of long amosite asbestos and a range of man-made fibres to stimulate release of superoxide anion from rat alveolar macrophages when they were in their native form (unopsonised) and opsonised by incubation in rat Immunoglobulin G. We also assessed the specific amount of opsonin adsorbed to each fibre type. In the uncoated form all of the fibres produced modest amounts of superoxide release from macrophages. When they were opsonised however there was an effect on stimulation of release of superoxide that was fibre-specific. Both MMVF21 and RCF 1 were dramatically enhanced in their ability to stimulate release and this was related to a high affinity of their surface for IgG. Code 100/475 and SiC were not substantially affected by opsonisation and this was reflected in their low affinity for IgG. Long amosite had low affinity for IgG but showed dramatic enhancement of capacity to stimulate superoxide release. These fibre-specific differences in the effect of a coating of material that is found in the lung lining points out the problems of interpretation of in vitro data and more work on this important area is warranted. PMID:8855115

  16. Measurement of dispersion in optical fibres with a microstructure cladding

    SciTech Connect

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

    2005-09-30

    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)

  17. Fibre function and perception during cutaneous nerve block.

    PubMed Central

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

    1975-01-01

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

  18. Production and use of polypropylene fibres and yarn

    Microsoft Academic Search

    E. M. Aizenshtein; V. N. Efremov

    2006-01-01

    World production of PP fibres in 2004 was approximately 6.3 million tons, including 2.1 million tons of film fibres. The total\\u000a consumption of PP fibres, including spunbond\\/meltblown, on the European continent increased by 2.5% in 2004, reaching 2.4\\u000a million tons. In the near future, expansion of use of PP fibres for production of nonwovens is projected. The world market\\u000a capacity

  19. Theoretical aspects of fibre laser cutting

    NASA Astrophysics Data System (ADS)

    Mahrle, A.; Beyer, E.

    2009-09-01

    Fibre lasers offer distinct advantages over established laser systems with respect to power efficiency, beam guidance and beam quality. Consequently, the potential of these new laser beam sources will be increasingly exploited for laser cutting applications that are conventionally carried out with CO2 lasers. However, theoretical estimates of the effective absorptivity at the cut front suggest that the shorter wavelength of the fibre laser in combination with its high focusability seems to be primarily advantageous for thin sheet metal cutting whereas the CO2 laser is probably still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behaviour of metals that shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the angle of incidence between the laser beam and the material to be cut. In evaluation of the revealed dependences, solution strategies for an improvement of the efficiency of fibre laser cutting of thicker metal sheets are suggested.

  20. Optical fibre cantilever sensor for biological application

    NASA Astrophysics Data System (ADS)

    Li, J.; Zhou, Y. X.; Patterson, G.; Shu, W. M.; Maier, R. R. J.; Fowler, R.; Hand, D. P.; MacPherson, W. N.

    2014-05-01

    Micro-cantilever sensors have shown great promise in a wide range of application are as including chemical and biological sensing. However, many of these devices are based upon a sensor `chip' that requires careful alignment between the cantilever and the read-out system, which can be challenging. Furthermore, optical interrogation typically involves a bulky free-space system. Optical fibre addressed cantilevers have been reported previously in the literature and in this paper we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibres using laser machining. Low-cost optical sources and a fibre coupled spectrometer are employed to monitor the cantilever deflection and therefore observe biological binding between a species of interest and an activated cantilever. Proof-of-concept experiments show that the sensor is capable of detecting pathogen concentration with down to a level of 105cfu/ml.

  1. Nonlinear optics of fibre event horizons.

    PubMed

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

    2014-01-01

    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

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

    PubMed

    Blank, Britta; Schlecht, Eva; Susenbeth, Andreas

    2012-04-01

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

  3. Compressive and torsional behaviour of Kevlar 49 fibre

    Microsoft Academic Search

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

    1984-01-01

    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

  4. Development and characterisation of polyaniline - carbon nanotube conducting composite fibres

    Microsoft Academic Search

    Vahid Mottaghitalab

    2006-01-01

    The present study describes methods for development and characterization of conducting electroactive polymer (CEP) fibre consisting of polyaniline (PAni) and single walled carbon nanotubes (SWNTs) which have potential applications as electronic devices to form building blocks of electronic textiles. The conducting composite fibres of PAni- SWNT were developed respectively using two steps (acid doping after fibre spinning) and one step

  5. Observation of the optoacoustic effect in an optical fibre

    Microsoft Academic Search

    J. A. Burt; K. J. Ebeling; D. Efthimiades

    1980-01-01

    The rediationless absorption of light propagating in optical fibres induces both stress waves and thermal waves in the fibre medium. Detection of such waves is termed the optoacoustic effect. Successful detection in optical fibres is easily obscured by scattered light impinging on the detector. We have obtained a signal of 2 mV on a piezoceramic transducer attached to a commercial

  6. Degradation of Technora aramid fibres in alkaline and neutral environments

    Microsoft Academic Search

    Guillaume Derombise; Laëtitia Vouyovitch Van Schoors; Peter Davies

    2009-01-01

    Technora fibres are high performance aramid fibres which have been used in ropes and protective clothing for many years. They are also now being proposed as geotextiles for soil reinforcement. However, there is a lack of experience on the long-term behaviour of Technora fibres in an alkaline environment (lime-treated ground…). Consequently, aging studies have been performed under different conditions (deionised

  7. Amplifier Similariton Fibre Laser with Nonlinear Spectral Compression

    E-print Network

    Paris-Sud XI, Université de

    Amplifier Similariton Fibre Laser with Nonlinear Spectral Compression Sonia Boscolo (1 demonstrate a new concept of fibre laser architecture supporting self-similar pulse evolution in the amplifier was demonstrated in a laser with an anomalous-dispersion segment 3 , in a Raman fibre laser and in an all

  8. Relations between cadmium and magnesium and aronia fractional dietary fibre

    Microsoft Academic Search

    Bozena Borycka; Jadwiga Stachowiak

    2008-01-01

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

  9. Optic fibre as a transducer of tendomuscular forces

    Microsoft Academic Search

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

    1996-01-01

    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

  10. Clothing as a source of fibres within museums

    Microsoft Academic Search

    Young Hun Yoon; Peter Brimblecombe

    2000-01-01

    This paper examines the role of visitors’ clothing as a source of fibres and dust in museums. Some idealised experiments determined the mass of fibres and dust emitted from clothing and the range of particle sizes found. In chamber studies it was possible to examine the effect of different humidity and airflow on fibre release. Image analysis was used to

  11. BOLTED CONNECTIONS FOR FIBRE-REINFORCED COMPOSITE STRUCTURAL MEMBERS

    E-print Network

    BOLTED CONNECTIONS FOR FIBRE-REINFORCED COMPOSITE STRUCTURAL MEMBERS Charles N. Rosner and Sami H Kingston, Ontario, K7K 5LO ABSTRACT Bolted connections in orthotropic materials, such as fibre the behaviour of bolted connections in fibre-reinforced composite members. The behaviour of connections

  12. Computation of Normal Logic Programs by Fibring Neural Networks

    E-print Network

    Seda, Anthony Karel

    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

  13. Greaseproof paper from Banana ( Musa paradisica L.) pulp fibre

    Microsoft Academic Search

    T Goswami; Dipul Kalita; P G Rao

    Utilization of banana pulp fibre for producing greaseproof paper has been investigated. The morphological characteristics of plant and fibre, chemical constituents of the sheath, characteristics of pulp and physical strength properties of hand sheet of 45+5 gsm made from banana pulp alone or in combination with bamboo pulp fibre are presented. Results of the laboratory investigation show that Musa paradisica

  14. Transition zone studies of vegetable fibre-cement paste composites

    Microsoft Academic Search

    Holmer Savastano; Vahan Agopyan

    1999-01-01

    The transition zone of short filament fibres randomly dispersed in a paste of ordinary Portland cement was analysed. Composites with vegetable fibres (malva, sisal and coir) were compared with those with chrysotile asbestos and polypropylene fibres. The composites were prepared for testing at the ages of 7, 28, 90 and 180 days. The water-cement ratio was 0.38; at the age

  15. Fatigue crack propagation in polypropylene reinforced with short glass fibres

    Microsoft Academic Search

    Alessandro Pegoretti

    1999-01-01

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

  16. Performance of oil palm EFB fibre reinforced concrete roof slates

    Microsoft Academic Search

    J. Kaliwon; S. Sh Ahmad; A. Abdul Aziz

    2010-01-01

    Natural fibres such as wood and vegetable fibre offer many advantages such as renewability, recyclability low specific gravity and high specific strength. In Malaysia most of the studies only focused on producing EFB as MDF and pulp and paper products. This paper reviews the development of natural fibres for building material and discusses the performance of oil palm empty fruit

  17. Fibre-based imaging: new challenges

    NASA Astrophysics Data System (ADS)

    Plöschner, Martin; Straka, Branislav; Dholakia, Kishan; ?ižmár, TomáÅ.¡

    2015-03-01

    A novel minimally invasive micro-endoscopes utilizing disordered light within a standard multimode optical fibre have been introduced recently. The two most important limitations of this exciting technology are (i) the lack of bending flexibility (transformation matrix is only valid as long as the fibre remains stationary) and (ii) high demands on computational power, making the performance of such systems slow. Here we discuss possible routes to address the later one: We introduce a GPU toolbox to make this powerful technique faster and more accessible to bio-medical researchers.

  18. Friction measurements on carbon fibre tows

    NASA Astrophysics Data System (ADS)

    Cornelissen, B.; Warnet, L.; Akkerman, R.

    2010-06-01

    Friction plays an important role in the production of fibre reinforced composite products. The fibrous tows deform during the forming phase. Friction is regarded as a dominant phenomenon in tow deformation mechanisms. The coefficient of friction is a material-interface characteristic which gives a relation between applied deformation loads and frictional forces. A capstan experiment has been performed with carbon fibre tows on a steel cylinder. This work aims to clarify friction related mechanisms and identify dominant parameters. The applicability of the capstan experiment is investigated with respect to the frictional behaviour of fibrous tows.

  19. Microstructured fibres ultraviolet sources for sensing applications

    NASA Astrophysics Data System (ADS)

    Holdynski, Zbigniew; Napierala, Marek; Szymanski, Michal; Murawski, Michal; Mergo, Pawel; Marc, Pawel; Jaroszewicz, Leszek R.; Nasilowski, Tomasz

    2014-05-01

    We show a new possibility for extension of supercontinuum spectrum generated in photonic crystal fibre towards the UV light. To do so, we use four wave mixing and cross phase modulation nonlinear effects as well as interaction of fundamental mode with higher order modes. It is shown that a few modes operation and proper dispersion profiles of these modes give a possibility of nonlinear effects optimization and thus improvement of UV generation. The advantage of presented solution is the employment of cascaded nonlinear interactions inside one microstructured fibre.

  20. Multicore microstructured optical fibre for sensing applications

    NASA Astrophysics Data System (ADS)

    Sójka, L.; Pajewski, L.; ?liwa, M.; Mergo, P.; Benson, T. M.; Sujecki, S.; Bere?-Pawlik, E.

    2015-06-01

    In this contribution we present the sensing capabilities of a novel N-path Mach-Zehnder interferometer (MZI) that relies on a multicore microstructured optical fibre (MC-MOF) connected between two sections of standard single mode fibre. The modal properties of the MC-MOF structure are analysed experimentally by measuring near field profiles. The dependence of the N-path MC-MOF MZI sensitivity on temperature, tensile strain and bending is investigated. The results suggest that such an interferometer is a good candidate for a tensile strain or bending sensor.

  1. Continuous Atmospheric Plasma Oxidation of Carbon Fibres: Influence on the Fibre Surface and Bulk Properties and Adhesion to Polyamide 12

    Microsoft Academic Search

    Seckin ErdenKingsley; Kingsley K. C. Ho; Steven Lamoriniere; Adam F. Lee; Hasan Yildiz; Alexander Bismarck

    2010-01-01

    Continuous atmospheric plasma oxidation (APO) was used to introduce oxygen functionalities to the surface of carbon fibres\\u000a in an attempt to enhance interfacial adhesion between carbon fibres and polyamide-12 (PA-12). APO only affects the surface\\u000a properties of the fibres while their bulk properties remained unchanged. Contact angle and ?-potential measurements demonstrated\\u000a that APO-treated fibres became significantly more hydrophilic due to

  2. Frequency doubling technique perimetry and spectral domain optical coherence tomography in patients with early glaucoma

    Microsoft Academic Search

    F K Horn; C Y Mardin; D Bendschneider; A G Jünemann; W Adler; R P Tornow

    2011-01-01

    PurposeTo assess the combined diagnostic power of frequency-doubling technique (FDT)-perimetry and retinal nerve fibre layer (RNFL) thickness measurements with spectral domain optical coherence tomography (SDOCT).MethodsThe study included 330 experienced participants in five age-related groups: 77 ‘preperimetric’ open-angle glaucoma (OAG) patients, 52 ‘early’ OAG, 50 ‘moderate’ OAG, 54 ocular hypertensivepatients, and 97 healthy subjects. For glaucoma assessment in all subjects conventional

  3. Influence of fibre length and concentration on the properties of glass fibre-reinforced polypropylene: 4. Impact properties

    Microsoft Academic Search

    J. L. Thomason; M. A. Vlug

    1997-01-01

    The results are presented from the final part of a study on the influence of fibre length and concentration on the properties of glass-reinforced polypropylene. Composite impact strength increased directly with increasing fibre concentration. Charpy impact, tensile impact and high speed impact properties increased with fibre length up to 6 mm. A surprising result was that the Charpy impact strength

  4. Intraepidermal neuron-specific enolase (NSE)-immunoreactive nerve fibres: evidence for sprouting in uremic patients on maintenance hemodialysis.

    PubMed

    Johansson, O; Hilliges, M; Ståhle-Bäckdahl, M

    1989-05-01

    The use of indirect immunohistochemistry in 12 patients on maintenance hemodialysis has shown weak or moderately strong neuron-specific enolase (NSE)-immunoreactive nerve terminals and fibres sprouting throughout the layers of the epidermis. No such terminals or fibres were found in any of 15 controls. There was no difference between uremic patients with pruritus and those without. Furthermore, NSE-positive nerve fibres with a normal appearance were seen in the dermis, at the epidermal-dermal junctional zone and sometimes entering the stratum basale in both patients and controls. The immunoreactive nerves were thin, smooth and, at their terminal fields, varicose. The immunoreactivity seemed to be associated chiefly with sensory nerves. Thus, our results suggest that uremic patients undergoing maintenance hemodialysis develop an abnormal pattern of cutaneous innervation. PMID:2657508

  5. Fibre-Optic Impact Damage Detection Of Composite Materials

    NASA Astrophysics Data System (ADS)

    Measures, R. M.; Glossop, N. D. W.; Lymer, J.; Dubois, S.; Tsaw, W.; West, J.; Tennyson, R. C.

    1988-09-01

    The development of a fibre-optic based damage assessment system for composite material structures requires a base of knowledge that to date is not available in the literature. We report on several advances that will contribute towards the development of "structurally imbedded fibre optic damage evaluation" (SIFODE) technology. These include: devising a special surface treatment that allows control of the damage sensitivity of the optical fibres, determining their optimum orientation with respect to the material fibres in the adjacent plies and their depth in regard to an impact surface. The influence of the imbedded optical fibres on the strength and impact resistance of the composite material has also been investigated.

  6. FRD and scrambling properties of recent non-circular fibres

    NASA Astrophysics Data System (ADS)

    Avila, Gerardo

    2012-09-01

    Optical fibres with octagonal, square and rectangular core shapes have been proposed as alternative to the circular fibres to link the telescopes to spectrographs in order to increase the accuracy of radial velocity measurements. Theoretically they offer better scrambling properties than their circular counterparts. First commercial octagonal fibres provided good near field scrambling gains. Unfortunately the far field scrambling did not show important figures. This article shows test results on new fibres from CeramOptec. The measurements show substantial improvements of the far field scrambling gains. In addition, evaluation of their focal ratio degradation (FRD) shows much better performances than previous fibres.

  7. Design, manufacture and testing of self-sensing carbon fibre glass fibre reinforced polymer rods

    Microsoft Academic Search

    F. Nanni; G. Ruscito; G. Forte; G. Gusmano

    2007-01-01

    At present much attention is being devoted to the study of self-monitoring materials, which simultaneously offer good structural and sensing properties. In the present study self-sensing carbon-glass hybrid structural composites, behaving as 'guard' sensors (i.e. they give a warning when fixed loads are reached) were designed, manufactured and tested. In particular, samples containing different carbon fibre\\/glass fibre ratios were prepared

  8. High-power erbium-doped fibre amplifier pumped by a phosphosilicate fibre Raman converter

    SciTech Connect

    Kurkov, Andrei S; Paramonov, Vladimir M; Egorova, O N; Medvedkov, O I; Dianov, Evgenii M [A.M. Prokhorov General Physics Institute, 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); Zalevskii, I D [M.F. Stel'makh Polyus Research and Development Institute, Moscow (Russian Federation); Goncharov, S E ['Millon' Company, St. Petersburg (Russian Federation)

    2001-09-30

    A high power erbium-doped fibre amplifier pumped by single-mode radiation at 1478 nm is fabricated and tested. A Raman converter based on a fibre with a phosphosilicate core was used as the pumping source. The maximum output power achieved in spectral ranges C (1.53 - 1.56 {mu}m) and L (1.56 - 1.60 {mu}m) is 28 dBm. (active media. lasers)

  9. The mechanical properties of fibre-metal laminates based on glass fibre reinforced polypropylene

    Microsoft Academic Search

    W. J. Cantwell

    2000-01-01

    This paper investigates the quasi-static and impact properties of a novel fibre\\/metal laminate system based on a tough glass-fibre-reinforced polypropylene (GFPP). Initial testing has shown that excellent adhesion can be achieved by surface treating the aluminium and incorporating an interlayer based on a maleic-anhydride modified polypropylene copolymer at the interface between the composite and aluminium plies. Single cantilever beam tests

  10. Remotely addressed optical fibre curvature sensor using multicore photonic crystal fibre

    Microsoft Academic Search

    W. N. MacPherson; M. J. Gander; R. McBride; J. D. C. Jones; P. M. Blanchard; J. G. Burnett; A. H. Greenaway; B. Mangan; T. A. Birks; J. C. Knight; P.St.J. Russell

    2001-01-01

    We demonstrate an all-fibre curvature sensor that uses two-core photonic crystal fibre (PCF) as the sensing element. The PCF acts as a two-beam interferometer in which phase difference is a function of curvature in the plane containing the cores. A broadband source illuminates both cores, and the spectrum at a single point in the far-field interferogram is recorded. Applying a

  11. Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes

    PubMed Central

    Ara, Mirian; Ferreras, Antonio; Pajarin, Ana B.; Calvo, Pilar; Figus, Michele; Frezzotti, Paolo

    2015-01-01

    Objective. To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. Methods. One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. Results. ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. Conclusions. The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression. PMID:26185762

  12. Optical Fibre Bragg Gratings for Acoustic Sensors

    Microsoft Academic Search

    Graham Wild; Steven Hinckley

    2010-01-01

    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

  13. Planning a urban Radio over Fibre network

    Microsoft Academic Search

    Carlos Santiago; Bodhisattwa Gangopadhyay; Joao Pedro

    2011-01-01

    In order to reduce the costs associated with network planning, this paper presents a tool tailored for Radio over Fibre networks that: determines the location of antennas to cover a Manhattan like scenario considering candidate sites at different heights, for example on top of building or on street lamp posts; defines the number and location of optical splitters; determines the

  14. Activated carbon fibre materials for VOC removal

    Microsoft Academic Search

    P Navarri; D Marchal; A Ginestet

    2001-01-01

    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

  15. The zeta potential of mineral fibres.

    PubMed

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

    2014-07-15

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

  16. Distributed fibre optic sensors for pipeline protection

    Microsoft Academic Search

    Femi Tanimola; David Hill

    2009-01-01

    Pipeline leakage and intrusion detection continue to be a difficult issue because existing leak detection methods and the traditional methods of guarding pipelines have proven inadequate in the prevention of leaks and deterring third party intrusion into pipelines and plant facilities.The application of fibre optic leak detection and third party intruder detection methods have been successfully demonstrated to provide non-intrusive

  17. FIBRE MEDULLATION, MICRON, MARKETING AND MANAGEMENT

    Microsoft Academic Search

    S. HATCHER

    SUMMARY There are vast differences between the 'exotic' sheep breeds currently run in Australia with respect to their fleece structure, fibre type composition and characteristics such as fleece shedding, pigmentation and medullation. This leads to different end uses for the fleeces from these breeds and different potential to impact upon the Australian wool clip. A greater understanding of the biology

  18. Metal-insulator-semiconductor optoelectronic fibres

    Microsoft Academic Search

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

    2004-01-01

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

  19. Modified glass fibre reinforced polymer composites

    Microsoft Academic Search

    Yumei Cao

    2004-01-01

    A high ratio of strength to density and relatively low-cost are some of the significant features of glass fibre reinforced polymer composites (GFRPCs) that made them one of the most rapidly developed materials in recent years. They are widely used as the material of construction in the areas of aerospace, marine and everyday life, such as airplane, helicopter, boat, canoe,

  20. Jute and glass fibre hybrid laminates

    Microsoft Academic Search

    R. A. Clark; M. P. Ansell

    1986-01-01

    Hybrid laminates have been fabricated from randomly oriented jute fibre mats and woven glass fabrics with a common polyster resin matrix. Hand lay up techniques were used to simulate practical production methods in the field. A variety of laminate constructions were mechanically tested and some laminates were in addition assessed for environmental stability. Modified rule of mixtures expressions successfully predicted

  1. Properties of composites of carbon nanotube fibres

    Microsoft Academic Search

    R. J. Mora; J. J. Vilatela; A. H. Windle

    2009-01-01

    Composites have set the standard for high strength materials for several decades. With the discovery of nanotubes, new possibilities for reinforced composites have arisen, with potential mechanical properties superior to those of currently available materials. This paper reports the properties of epoxy matrix reinforced with fibres of carbon nanotubes (CNTs) which, in many ways, are similar to standard composites reinforced

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  3. Ectopic release of glutamate contributes to spillover at parallel fibre synapses in the cerebellum

    PubMed Central

    Balakrishnan, Saju; Dobson, Katharine L; Jackson, Claire; Bellamy, Tomas C

    2014-01-01

    In the rat cerebellar molecular layer, spillover of glutamate between parallel fibre synapses can lead to activation of perisynaptic receptors that mediate short-and long-term plasticity. This effect is greatest when clusters of fibres are stimulated at high frequencies, suggesting that glutamate clearance mechanisms must be overwhelmed before spillover can occur. However, parallel fibres can also release transmitter directly into the extracellular space, from ‘ectopic’ release sites. Ectopic transmission activates AMPA receptors on the Bergmann glial cell processes that envelop parallel fibre synapses, but the possible contribution of this extrasynaptic release to intersynaptic communication has not been explored. We exploited long-term depression of ectopic transmission, and selective pharmacology, to investigate the impact of these release sites on the time course of Purkinje neuron excitatory postsynaptic currents (EPSCs). Depletion of ectopic release pools by activity-dependent long-term depression decreased EPSC decay time, revealing a ‘late’ current that is present when fibres are stimulated at low frequencies. This effect was enhanced when glutamate transporters were inhibited, and reduced when extracellular diffusion was impeded. Blockade of N-type Ca2+ channels inhibited ectopic transmission to Bergmann glia and decreased EPSC decay time. Similarly, perfusion of the Ca2+ chelator EGTA-AM into the slice progressively eliminated ectopic transmission to glia and decreased EPSC decay time with closely similar time courses. Collectively, this evidence suggests that ectopically released glutamate contributes to spillover transmission, and that ectopic release therefore degrades the spatial precision of synapses that fire infrequently, and may make them more prone to exhibit plasticity. PMID:24421351

  4. Sapphire-derived all-glass optical fibres

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  5. Peripapillary Nerve Fiber Layer Thickness Profile Determined with High Speed, Ultrahigh Resolution

    E-print Network

    Srinivasan, Vivek J.

    -house software program. The disc margin was de- fined subjectively in each image and RNFL thickness profiles, and have shown that the convergence of ganglion cell axons from the retinal periphery toward the optic disc motion artifacts. It is then possible to detect and segment the RNFL in each raster OCT image and use

  6. Super-hydrophobic surfaces of layer-by-layer structured film-coated electrospun nanofibrous membranes

    Microsoft Academic Search

    Tasuku Ogawa; Bin Ding; Yuji Sone; Seimei Shiratori

    2007-01-01

    We have recently fabricated super-hydrophobic membrane surfaces based on the inspiration of self-cleaning silver ragwort leaves. This biomimetic super-hydrophobic surface was composed of fluoroalkylsilane (FAS)-modified layer-by-layer (LBL) structured film-coated electrospun nanofibrous membranes. The rough fibre surface caused by the electrostatic LBL coating of TiO2 nanoparticles and poly(acrylic acid) (PAA) was used to imitate the rough surface of nanosized grooves along

  7. A peptide hormone gene, GhPSK promotes fibre elongation and contributes to longer and finer cotton fibre.

    PubMed

    Han, Jie; Tan, Jiafu; Tu, Lili; Zhang, Xianlong

    2014-09-01

    Cotton fibres, the single-celled trichomes derived from the ovule epidermis, provide the most important natural material for the global textile industry. A number of studies have demonstrated that regulating endogenous hormone levels through transgenic approaches can improve cotton fibre qualities. Phytosulfokine-? (PSK-?) is a novel peptide hormone in plants that is involved in regulating cell proliferation and elongation. However, its potential applications in crop genetic improvement have not been evaluated. In this study, we describe how exogenous PSK-? application promotes cotton fibre cell elongation in vitro. Chlorate, an effective inhibitor of peptide sulfation, suppressed fibre elongation in ovule culture. Exogenously applied PSK-? partly restored the chlorate-induced suppression. A putative PSK gene (GhPSK) was cloned from Gossypium hirsutum. Expression pattern analysis revealed that GhPSK is preferentially expressed in rapidly elongating fibre cells (5-20 days postanthesis). Overexpression of GhPSK in cotton increased the endogenous PSK-? level and promoted cotton fibre cell elongation, resulting in longer and finer fibres. Further results from electrophysiological and physiological analyses suggest that GhPSK affects fibre development through regulation of K(+) efflux. Digital gene expression (DGE) profile analysis of GhPSK overexpression lines indicates that PSK signalling may regulate the respiratory electron-transport chain and reactive oxygen species to affect cotton fibre development. These results imply that peptide hormones are involved in cotton fibre growth and suggest a new strategy for the biotechnological improvement of cotton fibre quality. PMID:24666593

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

    E-print Network

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

    2015-01-01

    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).

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

    PubMed

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

    2011-08-01

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

  10. Modified glass fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Cao, Yumei

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  12. Fibre laser component technology for 2-micron laser systems

    NASA Astrophysics Data System (ADS)

    Stevens, G.; Robertson, A.

    2014-05-01

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

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

    Microsoft Academic Search

    Jeng-Shyong Lin

    2002-01-01

    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

  14. Quantitation of cotton fibre-quality variations arising from boll and plant growth environments

    Microsoft Academic Search

    Judith M. Bradow; Philip J. Bauer; Oscar Hinojosa; Gretchen Sassenrath-Cole

    1997-01-01

    Crop growth simulation models used to manage cultural inputs and to improve yields of cotton, Gossypium hirsutum L., do not address fibre quality, a major determinant of cotton fibre price and end-use. Fibre maturation simulations require rapid, reproducible methods for fibre quality quantitation at the boll or locule level. Combination of fibre quality mapping by fruiting site with quality quantitation

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

    Microsoft Academic Search

    Edwin Bodros; Christophe Baley

    2008-01-01

    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

  16. Fibre Optic Sensors for Selected Wastewater Characteristics

    PubMed Central

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

    2013-01-01

    Demand for online and real-time measurements techniques to meet environmental regulation and treatment compliance are increasing. However the conventional techniques, which involve scheduled sampling and chemical analysis can be expensive and time consuming. Therefore cheaper and faster alternatives to monitor wastewater characteristics are required as alternatives to conventional methods. This paper reviews existing conventional techniques and optical and fibre optic sensors to determine selected wastewater characteristics which are colour, Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). The review confirms that with appropriate configuration, calibration and fibre features the parameters can be determined with accuracy comparable to conventional method. With more research in this area, the potential for using FOS for online and real-time measurement of more wastewater parameters for various types of industrial effluent are promising. PMID:23881131

  17. Supercontinuum Generation in a Photonic Crystal Fibre

    Microsoft Academic Search

    Pei-Guang Yan; Shuang-Chen Ruan; Hao-Jia Lin; Chen-Lin Du; Yong-Qin Yu; Ke-Cheng Lu; Jian-Quan Yao

    2004-01-01

    Nearly 1000-nm broad continuum from 390 nm to 1370 nm is generated in a 2-m long photonic crystal fibre. The maximum total power of supercontinuum is measured to be 60 mW with the pumping power of 800 mW output from a 200-fs Ti:sapphire laser. The evolution of the pumping light into supercontinuum is experimentally studied in detail. It is found

  18. Effective Properties of Viscoelastic Fibre Composites

    NASA Astrophysics Data System (ADS)

    Andrianov, Igor V.; Danishevs'kyy, Vladyslav V.; Kirichek, Oleksandr U.

    2010-09-01

    The present paper provides details on the application of asymptotic homogenization techniques for calculation of effective properties of fibre composite material. Correspondence principle allows transforming governing boundary value problems to the quasistatic ones. For solving of the cell problem modified boundary shape perturbation procedure is used. For inversion of the Laplace transform effective and accurate Gaver algorithm is used. Proposed approach gives the computer time consuming solution.

  19. Genetics of dietary fibre in bread wheat

    Microsoft Academic Search

    G. Charmet; U. Masood-Quraishi; C. Ravel; I. Romeuf; F. Balfourier; M. R. Perretant; J. L. Joseph; M. Rakszegi; F. Guillon; P. E. Sado; Z. Bedo; L. Saulnier

    2009-01-01

    Arabinoxylans (AX) are major components of cell walls in wheat endosperm. The water-extractable part, WEAX, is considered\\u000a as dietary fibres with health promoting effects. AX exhibit large natural variations in their amount but few studies have\\u000a been carried out on the genetics of WEAX content and structure in bread wheat. We first carried out a “forward” quantitative\\u000a genetic approach, using

  20. A novel fibre Bragg grating hydrophone system

    NASA Astrophysics Data System (ADS)

    Wang, Yanhua; Ren, Wenhua; Tan, Zhongwei; Liu, Yan; Jian, Shuisheng; Gong, Taorong

    2007-11-01

    A novel fibre Bragg grating (FBG) hydrophone system is introduced in the paper. The influence of the sound pressure on the FBG is transformed to light intensity measurement with tuned laser. Elastic material and matched FBGs are employed to enhance the sensitivity of the hydrophone system. The hydrophone system can operate in a wide acoustic frequency range from 100Hz to 3kHz and good linear relationship is observed between the output light intensity and the sound pressure.

  1. Electrically conductive glass fibre reinforced epoxy resin

    Microsoft Academic Search

    M. Kupke; Hans-Peter Wentzel; Karl Schulte

    1998-01-01

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

  2. Broadband optical isolator in fibre optics

    NASA Astrophysics Data System (ADS)

    Berent, Micha?; Rangelov, Andon A.; Vitanov, Nikolay V.

    2013-08-01

    We propose a broadband optical diode, which is composed of one achromatic reciprocal quarter-wave plate and one non-reciprocal quarter-wave plate, both placed between two crossed polarizers. The presented design of the achromatic wave plates relies on an adiabatic evolution of the Stokes vector; thus, the scheme is robust and efficient. A possible simple implementation using fibre optics is suggested.

  3. Effects of chemical treatments on hemp fibre structure

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  4. Flat Ge-doped optical fibres for food irradiation dosimetry

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-04-01

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  5. Chronological ageing of human hair keratin fibres.

    PubMed

    Thibaut, S; de Becker, E; Bernard, B A; Huart, M; Fiat, F; Baghdadli, N; Luengo, G S; Leroy, F; Angevin, P; Kermoal, A M; Muller, S; Peron, M; Provot, G; Kravtchenko, S; Saint-Léger, D; Desbois, G; Gauchet, L; Nowbuth, K; Galliano, A; Kempf, J Y; Silberzan, I

    2010-12-01

    Examination of very long hair (length > 2.4 m) using a large range of evaluation methods including physical, chemical, biochemical and microscopic techniques has enabled to attain a detailed understanding of natural ageing of human hair keratin fibres. Scrutinizing hair that has undergone little or no oxidative aggression--because of the absence of action of chemical agents such as bleaching or dyeing--from the root to the tip shows the deterioration process, which gradually takes place from the outside to the inside of the hair shaft: first, a progressive abrasion of the cuticle, whilst the cortex structure remains unaltered, is evidenced along a length of roughly 1 m onwards together with constant shine, hydrophobicity and friction characteristics. Further along the fibre, a significant damage to cuticle scales occurs, which correlates well with ceramides and 18-Methyl Eicosanoic Acid (18-MEA) decline, and progressive decrease in keratin-associated protein content. Most physical descriptors of mechanical and optical properties decay significantly. This detailed description of natural ageing of human hair fibres by a fine analysis of hair components and physical parameters in relationship with cosmetic characteristics provides a time-dependent 'damage scale' of human hair, which may help in designing new targeted hair care formulations. PMID:20384898

  6. Optical fibre Bragg grating cladding mode sensors

    NASA Astrophysics Data System (ADS)

    Baiad, M. D.; Gagné, M.; de Montigny, E.; Madore, W.-J.; Godbout, N.; Boudoux, C.; Kashyap, R.

    2013-05-01

    In this paper we propose and demonstrate two forms of a device for sensing cladding modes efficiently. The cladding modes, generated by an untilted and tilted fibre Bragg grating (TFBG) written in SMF28 fibre are captured by splicing it to an in-line double-clad fibre coupler (DCFC). A comaprison is made of the capture efficiency of the cladding modes in two configurations; one in which the TFBG is taper spliced to the DCF, or in the other in which an FBG in an SMF28 is etched down to match the outer core of the DCF. In both cases the cladding modes are captured efficiently, but with significantly improved results for the former configuration. We demonstrate surrounding refractive index sensing using a new signal analysis scheme based on the extinction of each cladding mode resolved over a bandwidth of over ~60nm. This robust device has the advantage of faithfully transmitting the cladding modes over a long distance and is therefore suitable for remote sensing over long distances. The sensitivity of the device is discussed. This device may be used in a variety of applications such as for bend, strain, temperature and surrounding refractive index sensing.

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

    SciTech Connect

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

    1994-12-31

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

  8. Optical fibre musical instruments: making sense of the senseless

    Microsoft Academic Search

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

    2009-01-01

    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

  9. Histological assessment of sintered metal-fibre-web materials.

    PubMed

    Jansen, J A; van't Hof, M A

    1994-07-01

    Recently it has been shown that flexible metal fibre mesh structures can be used for the subcutaneous stabilisation of percutaneous devices. However, for the safe application of fibre mesh structures, it is necessary that these materials possess certain biological properties. The purpose of this paper is to discuss surgical, statistical and histological methods for the testing and evaluation of metal fibre web materials for soft tissue application. The use and potential of the described techniques are demonstrated with two examples. PMID:7983585

  10. Strength and permeability of steel fibre reinforced grouts

    Microsoft Academic Search

    M. L. Berndt

    2010-01-01

    The feasibility of using steel fibres to improve the tensile strength and durability of cement–sand grout was investigated. Initial tests focused on achieving pumpable grout mixes and 13mm round steel fibres with a diameter of 0.16mm were found to be compatible with a conventional grout paddle mixer and piston pump. Subsequently, grouts with 0.5% and 1% fibre volume fraction were

  11. Thermal Characteristics of High-Strength and Thermostable Aromatic Fibres

    Microsoft Academic Search

    K. E. Perepelkin; E. A. Pakshver; I. V. Andreeva; O. B. Malan'ina; R. A. Makarova; Z. G. Oprits

    2005-01-01

    The thermal characteristics of ten kinds of para-aramid, meta-aramid, polyoxadiazole, and polyimide fibres were investigated\\u000a by dynamic thermogravimetric analysis, differential scanning calorimetry, and thermomechanical analysis. It was shown that\\u000a thermooxidative degradation of these fibres begins at 400–450 C and is intensified at higher temperatures. These fibres are\\u000a characterized by dimensional stability up to the temperature of onset of thermooxidative processes

  12. Thermal characteristics of high-strength and thermostable aromatic fibres

    Microsoft Academic Search

    K. E. Perepelkin; E. N. Dresvyanina; E. A. Pakshver

    2008-01-01

    The thermal characteristics of para-aramid, polyoxadiazole, and polyimide fibres were comparatively investigated by dynamic\\u000a thermogravimetric analysis, differential scanning calorimetry, and thermomechanical analysis. It was shown that thermooxidative\\u000a degradation of these types of fibres began at 400–450 °C and intensified at higher temperatures. The fibres investigated are\\u000a characterized by size stability up to the initial temperature of thermooxidative processes (400–450 °C).

  13. Fatigue behaviour of synthetic fibres, yarns, and ropes

    Microsoft Academic Search

    M. C. Kenney; J. F. Mandell; F. J. McGarry

    1985-01-01

    S-N fatigue and creep-rupture data have been obtained for nylon 6,6 single fibres, interlaced yarns, and small ropes under a variety of loading conditions. The results show a similar degradation rate at each level of structure, with no apparent influence of inter-fibre effects. Cyclic lifetimes of single fibres of nylon 6,6 as well as polyester and aramid can be predicted

  14. Fibre optic sensors with nano-structured coatings

    Microsoft Academic Search

    Stephen W. James; Ralph P. Tatam

    2006-01-01

    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.

  15. Optical Fibre Connection Performance Investigation for BigBOSS"

    NASA Astrophysics Data System (ADS)

    Poppett, Claire; Edelstein, J.; Sirk, M.; Vanderburg, A. M.

    2012-01-01

    Fibre optics connectors with satisfactory performance in terms of throughput and conservation of étendue would be beneficial to many astronomical fibre optic systems. We measure the focal ratio degradation performance of various methods of fibre connections which are commercially available in order to establish a method which will meet the BigBOSS design requirements. These results are then compared to theoretical predictions in order to quantitatively evaluate their performance.

  16. Thermal dependence of passive electrical properties of lizard muscle fibres.

    PubMed

    Adams, B A

    1987-11-01

    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

  17. High-speed Temperature Control for Polymeric Fibres

    Microsoft Academic Search

    C. P. Buckley; M. E. Sikorski

    1991-01-01

    A description is given of a method devised for high-speed open-loop control of temperature in polymeric fibres, suitable for either running threadlines in processing machinery or static fibre specimens in testing equipment. It is based on Impingement on the fibre by a variable-temperature transverse air jet, formed by the mixing of varying proportions of hot and cold air. Mixing is

  18. The properties of PIPD-fibre\\/epoxy composites

    Microsoft Academic Search

    B. Brew; P. J. Hine; I. M. Ward

    1999-01-01

    In this paper we describe measurements of the properties of composites based on a new organic fibre, poly {2,6 dimidazo [4,5-6: 4?5?-e] pyridinylene – 1,4 (2,5-dihidroxy) phenylene} (PIPD). The properties of unidirectional PIPD-fibre\\/epoxy composites were measured using a range of standard ASTM tests, and the measured values were compared with other fibre-reinforced materials. This comparison showed that the most outstanding

  19. Phase transition temperature of water restrained in polysulfone hollow fibres

    Microsoft Academic Search

    T. Hatakeyama; S. Yamamoto; H. Hatakeyama

    1993-01-01

    The melting and crystallization behaviour of water restrained in polysulfone (PSF) hollow fibre has been investigated by DSC.\\u000a The PSF hollow fibre was prepared by wet spinning. The morphology of the fibre was observed by scanning electron microscopy.\\u000a The amount of water was varied by successive evaporation and it was observed that melting and crystallization shifted to temperatures\\u000a lower than

  20. The renaissance and bright future of fibre lasers

    Microsoft Academic Search

    A. Tünnermann; T. Schreiber; F. Röser; A. Liem; S. Höfer; H. Zellmer; S. Nolte; J. Limpert

    2005-01-01

    The first rare-earth-doped fibre lasers were operated in the early 1960s and produced a few milliwatts at a wavelength around 1 µm. For the next several decades, fibre lasers were little more than a low-power laboratory curiosity. Recently, however, fibre lasers have entered the realm of kilowatt powers with diffraction-limited beam quality. In this paper we review the reasons for

  1. Ultimate low loss of hollow-core photonic crystal fibres

    Microsoft Academic Search

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

    2005-01-01

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

  2. REVIEW ARTICLE: Fibre optic sensors with nano-structured coatings

    NASA Astrophysics Data System (ADS)

    James, Stephen W.; Tatam, Ralph P.

    2006-07-01

    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.

  3. Effect of alkali treated jute fibres on composite properties

    Microsoft Academic Search

    Dipa Ray; B. K. Sarkar; A. K. Rana; N. R. Bose

    2001-01-01

    Jute fibres were subjected to a 5% alkali (NaOH) solution treatment for 0, 2, 4, 6 and 8 h at 30°C. An improvement in the\\u000a crystallinity in the jute fibres increased its modulus by 12%, 68% and 79% after 4, 6 and 8 h of treatment respectively. The\\u000a tenacity of the fibres improved by 46% after 6 and 8 h

  4. Flexible delivery of Er:YAG radiation at 2.94 ?m with novel hollow-core silica glass fibres: demonstration of tissue ablation

    NASA Astrophysics Data System (ADS)

    Urich, Artur; Maier, Robert R. J.; Knight, Jonathan C.; Yu, Fei; Hand, Duncan P.; Shephard, Jonathan D.

    2013-03-01

    In this work we present the delivery of high energy Er:YAG laser pulses operating at 2.94 ?m through a hollow-core negative curvature fibre (HC-NCF) and a hollow-core photonic crystal fibre (HC-PCF) and their use for the ablation of biological tissue. In HC-NCF fibres, which have been developed recently, the laser radiation is confined in a hollow core and by an anti-resonant or reflection principle (also known as ARROW). Both fibres are made of fused silica which has high mechanical and chemical durability, is bio-inert and results in a fibre with the flexibility that lends itself to easy handling and minimally invasive procedures. The HC-NCF structure consists of only one ring of capillaries around a realtively large core, followed by a protecting outer layer, hence the preform is relatively easy to build compared to traditional HC-PCF. The measured attenuation at 2.94 ?m is 0.06 dB/m for the HC-NCF and 1.2 dB/m for the HC-PCF. Both fibres have a single mode output beam profile which can be advantageous for surgical applications as the beam profile is maintained during fibre movement. We demonstrate delivery of high energy pulses through both fibres, well above the thresholds needed for the ablation of biological tissue in non-contact and contact mode. Delivered energy densities reached > 750 J/cm-2 after 10 m of HC-NCF and > 3400 J/cm2 through a 44 cm HC-PCF.

  5. The Visual System Figure 3.1: Left: The visual system seen from underneath the brain showing the nerve fibres from the retina cross

    E-print Network

    Majumder, Aditi

    showing the nerve fibres from the retina cross over to the opposite sides of the brain. A small part that controls the pupil size and hence defines the level of illumination on the #12;3.1. THE EYE 17 retina. The optical image of the eye is formed on the retina ­ a thin layer of cells approximately the thickness

  6. Laser micromachining of optical fibre: an instrumentation enabler

    NASA Astrophysics Data System (ADS)

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

    The use of lasers to process optical fibre at INO goes back in the early '90 when a team developed a CO2 laser-based process to anneal fibre-end surface allowing the lowest back reflection-loss connectors commercially available at that time. Since then, INO has developed several processes for stripping, cleaving, polishing, end-shaping, machining, bending, welding, soldering and packaging optical fibres. More recently, INO has used laser micromachining of optical fibres in order to enable innovative instrumentation in the field of chemical sensors, flow cytometry and gas chromatography.

  7. Nonlinear Optics and Solitons in Photonic Crystal Fibres

    NASA Astrophysics Data System (ADS)

    Skryabin, Dmitry V.; Wadsworth, William J.

    The fibre optics revolution in communication technologies followed the 1950's demonstration of the glass fibres with dielectric cladding [1]. Transmission applications of fibre optics have become a dominant modern day technology not least because nonlinearities present in - or introduced into - glass and enhanced by the tight focusing of the fibre modes allow for numerous light processing techniques, such as amplification, frequency conversion, pulse shaping, and many others. For these reasons, and because of the rich fundamental physics behind it, nonlinear fibre optics has become a blossoming discipline in its own right [1]. The 1990's witnessed another important development in fibre optics. Once again it came from a new approach to the fibre cladding, comprising a periodic pattern of air holes separated by glass membranes forming a photonic crystal structure [2, 3]. This prompted the name Photonic Crystal Fibres (PCFs). The fascinating story behind the invention of PCF and research into various fibre designs can be found, e.g., in [4]. Our aim here is to review the role played by PCFs in nonlinear and quantum optics, which is becoming the mainstream of the PCF related research and applications. Our focus will be on the areas where PCFs have brought to life effects and applications which were previously difficult, impossible to observe or simply not thought about.

  8. The Effect of Low Power Nitrogen Plasma Treatment of Carbon Fibres on the Interfacial Shear Strength of Carbon Fibre\\/Epoxy Composites

    Microsoft Academic Search

    G. J. Farrow; C. Jones

    1994-01-01

    Type II (high strength) carbon fibres have been given a low power nitrogen plasma treatment. It is shown that this plasma treatment has no effect on the fibre diameter, no detrimental effect on fibre strength and can significantly improve fibre\\/resin adhesion. It is proposed that this improvement is due to chemical interaction via amine\\/epoxy bonding at the edge sites together

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

    Microsoft Academic Search

    Guillaume Kister; Brian Ralph; Gerard F. Fernando

    2004-01-01

    The detection of damage in fibre-reinforced composite materials is important in areas where these materials are used for load-bearing applications. This paper reports on the use of conventional reinforcing E-glass fibres that were made to act as light guides. These reinforcing fibre light guides were used to detect damage induced in the composite by impact, indentation and flexure. The E-glass

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

    Microsoft Academic Search

    Serge Bourbigot; Xavier Flambard; Franck Poutch

    2001-01-01

    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

  11. Influence of fibre weight fraction on failure mechanisms of poly(ethylene terephthalate) reinforced by short-glass-fibres

    Microsoft Academic Search

    Kiyoshi Takahashi; Nak-Sam Choi

    1991-01-01

    Failure mechanisms of short-glass-fibre reinforced poly(ethylene terephthalate) were investigated with particular attention\\u000a to the effects of fibre weight fraction (Wf=1 wt%, 30 wt% and 60 wt%). A fracture morphology study was carried out for the surface and for the interior of uniaxial tensile\\u000a specimens. On the surface, tensile cracks occurring mostly at the fibre ends seemed to be more influential

  12. Surface Resistance of Jute Fibre/Polylactic Acid Biocomposite to Wet Heat

    NASA Astrophysics Data System (ADS)

    Zandvliet, Clio; Bandyopadhyay, N. R.; Ray, Dipa

    2015-05-01

    Jute fibre/polylactic acid (PLA) composite is of special interest because both resin and reinforcement come from renewable resources. Thus, it could be a more eco-friendly alternative to glass fibre composite [1] and to conventional wood-based panels made with phenol-formaldehyde resin which present many drawbacks for the workers and the environment [2]. Yet the water affinity of the natural fibres, the susceptibility of PLA towards hydrolysis and the low glass transition of the PLA raise a question about the surface resistance of such composites to wet heat in service condition for a furniture application [3]. In this work, the surface resistance of PLA/jute composite alone and with two different varnishes are investigated in regard to an interior application following the standard test method in accordance to BS EN 18721:2009: "Furniture: assessment of surface resistance to wet heat". It is compared to two common wood based panels, plywood and hardboard. After test, the composite material surface is found to be more affected than plywood and hardboard, but it becomes resistant to wet heat when a layer of biosourced varnish or petrol-based polyurethane varnish are applied on the surface.

  13. Three myosin heavy chain isoforms in type 2 skeletal muscle fibres

    Microsoft Academic Search

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

    1989-01-01

    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

  14. Comparative Characterization of Dietary Fibre-Enriched Frozen\\/Thawed Mashed Potatoes

    Microsoft Academic Search

    María Dolores Alvarez; Cristina Fernández; María Dolores Olivares; Wenceslao Canet

    2012-01-01

    The potential use of commercial fibres (pea fibre, inulin, and their blends), as fibre-enriching agents in frozen\\/thawed mashed potatoes was reported. Pea fibre and inulin supplementations conferred hardness and softness to the product, respectively. Differences were attributed to the relationship of the fibre with the potato starch matrix. The association of pea fibre at low concentration (<15 g\\/kg mashed potatoes)

  15. Properties of mixed particleboards based on white birch ( Betula papyrifera ) inner bark particles and reinforced with wood fibres

    Microsoft Academic Search

    Roger Pedieu; Bernard Riedl; André Pichette

    2009-01-01

    The use of white birch (Betula papyrifera) inner bark particles\\u000a as a raw material for panel manufacture is more profitable than their use for energy production. The\\u000a objective of this study was to manufacture three layers mixed particleboards based on white birch inner\\u000a bark particles in the core and reinforced with wood fibres in the face. Two manufacturing factors were\\u000a taken

  16. Chemical resistance, void content and tensile properties of oil palm\\/jute fibre reinforced polymer hybrid composites

    Microsoft Academic Search

    M. Jawaid; H. P. S. Abdul Khalil; A. Abu Bakar; P. Noorunnisa Khanam

    2011-01-01

    Tri layer hybrid composites of oil palm empty fruit bunches (EFB) and jute fibres was prepared by keeping oil palm EFB as skin material and jute as the core material and vice versa. The chemical resistance, void content and tensile properties of oil palm EFB\\/Jute composites was investigated with reference to the relative weight of oil palm EFB\\/Jute, i.e. 4:1,

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

    SciTech Connect

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

    2001-08-31

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

  18. Numerical aperture analysis of specialty microstructured fibres in a broad wavelength range

    NASA Astrophysics Data System (ADS)

    Ostrowski, L.; Murawski, M.; Szymanski, M.; Holdynski, Z.; Tenderenda, T.; Pura, P.; Mergo, P.; Mar?, P.; Nasilowski, T.; Jaroszewicz, L. R.

    2013-05-01

    Numerical Aperture (NA) is one of the fundamental properties of optical fibres. It determines the ability of efficient light coupling into the fibre and low loss splicing with other fibres. NA is essential when novel fibres are manufactured. Moreover, dispersive behaviour of geometrical guiding mechanisms, existing in microstructured fibres, is completely different comparing with material guiding mechanisms of classical fibres. Therefore we constructed measurement system, for characterization the dispersive properties of NA of specialty microstructured fibres in broad wavelength range. Additionally, presented setup can be applied for measurements refractive index of different materials (including highly absorbing) filling the holes of microstructured fibre in broad wavelength range.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  20. The Influence of Fibre Volume Fraction on the Mode I Interlaminar Fracture Toughness of a Glass-Fibre\\/Vinyl Ester Composite

    Microsoft Academic Search

    P. Compston; P.-Y. B. Jar

    1999-01-01

    This paper investigates the influence of fibre volume fraction on the mode I interlaminar fracture toughness GIc of a glass-fibre\\/vinyl ester composite. Two fibre volume fraction parameters are defined; a global value for the composite specimen and a value for the fibre-dense intralaminar regions. The range of global fibre volume fraction studied was 32–52 %. Results show that GIc values

  1. Processing with kW fibre lasers: advantages and limits

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

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

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

    PubMed Central

    HAUGAN, E; HOLST, B

    2013-01-01

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

  3. Viscoelasticity of Kevlar 49 fibres Ioannis P. GIANNOPOULOS1

    E-print Network

    Burgoyne, Chris

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

  4. Damping analysis of unidirectional glass and Kevlar fibre composites

    Microsoft Academic Search

    Jean-Marie Berthelot; Youssef Sefrani

    2004-01-01

    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

  5. Structure development and properties of PET fibre filled PP composites

    Microsoft Academic Search

    C. Saujanya; S. Radhakrishnan

    2001-01-01

    The structure development and mechanical properties of polypropylene (PP) composite containing polyethylene terephthalate (PET) fibres were studied both in the presence and absence of a compatibilizer such as maleic anhydride (MA). The structural and morphological studies were carried out by WAXD, optical microscopy and SEM techniques. In the absence of MA, the PET fibres in PP showed transcrystalline morphology and

  6. Digestion Modelling in the Small Intestine : Impact of Dietary Fibre

    E-print Network

    Paris-Sud XI, Université de

    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

  7. Dietary fibre and health in children and adolescents.

    PubMed

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

    2015-08-01

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

  8. Optical Fibres In The Industrial And Commercial Environment

    NASA Astrophysics Data System (ADS)

    Baker, P. D. W.

    1984-03-01

    There is considerable growth world-wide in the use of fibre optics in industry and commerce. One of the main reasons given by users so far for installing fibre optic systems is the complete freedom from electrical interference and resulting data integrity. The reliability of fibre optics has now been established by the telecommunication networks, but there is still conservatism amonast some potential industrial users. It is mainly the larger organisations in process control and users of large data processing organisations that are taking up fibre optics enthusiastically. The systems are now competitive with alternative systems and there is a large number of suppliers of components and subsystems world-wide. Integrated circuit signal processing is now being incorporated into transmitter and receiver housings and complete fibre optic local area networks are beginning to challenge brand name copper systems Lack of standards at present however, may present some difficulties for the potential user wishing to fabricate his own system. In the future, the development of integrated optic components will add another dimension to fibre optics in switching and signal processing and fibre optic sensors will challenge traditional transducers- The continued growth of fibre optics in industry and commerce seems well assured.

  9. Numerical simulation of incoherent optical wave propagation in nonlinear fibres

    E-print Network

    Boyer, Edmond

    Résumé The present work concerns the study of pulsed laser systems containing a fibre amplifier laser, a master oscillator coupled with fibre amplifier, usually a cladding-pumped high-power amplifier nonlinear effects (such as Kerr effect, four waves mixing, Raman effect) could behave very differently

  10. Concrete Cylinders Confined with Basalt Fibre Reinforced Polymer Eythor Thorhallsson

    E-print Network

    Karlsson, Brynjar

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

  11. Stimulated Raman scattering in hollow core photonic crystal fibres

    Microsoft Academic Search

    S. Lebrun; P. Delaye; G. Roosen

    2007-01-01

    We present an experimental demonstration of stimulated Raman scattering in a hollow core photonic crystal fibre filled with ethanol. By combining the original transmission properties of these fibres with a highly nonlinear liquid we have realized a very efficient Raman generator. This technique can be applied to other nonlinear mechanisms and opens the way towards the realisation of new fibered

  12. A fire detection system using optical fibres for utility tunnels

    Microsoft Academic Search

    Hiromitsu Ishii; Kiyoshi Kawamura; Takashi Ono; Hirotoshi Megumi; Akimitsu Kikkawa

    1997-01-01

    In this paper we examine a fire detection system for utility tunnels on the basis of the fact that temperature distribution along an optical fibre can be determined through measurement of the Raman back scattering of the Stokes and anti-Stokes lines. This system can measure temperature distribution by scanning, with an accuracy of 5C and 5 m, an optical fibre,

  13. Mutations in TPM2 and congenital fibre type disproportion.

    PubMed

    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

    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

  14. A novel synthetic erionite fibre radiolabelled with (57)Co.

    PubMed

    Patrick, G; Rood, A P; Hoskins, J A; Mongan, L C; Houghton, C E; Jones, T; Dinsdale, D

    2001-07-01

    The aim was to produce a radiolabelled fibre suitable for long-term carcinogenesis studies. To this end, we have successfully synthesised erionite fibres by a method adapted to incorporate (57)Co into the crystal framework. Morphologically the fibres are straight, of median length 2.5 microm, with 11% of fibres > 8 microm long, and median width 0.32 microm. These values are comparable to natural Oregon erionite. Autoradiography confirmed that the (57)Co was associated with the fibres themselves. The stability of the radiolabel in vivo was examined by instilling 1 mg of synthetic erionite into the lungs of F-344 rats. About half of the thoracic content of (57)Co was cleared in the first week, and over the following 5 weeks the remainder was cleared slowly with a half-time of 120 days. After 6 weeks the urinary excretion of (57)Co was only 0.054% of the initial lung content per day. This represented fibre dissolution plus any leaching of (57)Co from the fibres. It can be concluded that the (57)Co is bound into the erionite fibres with sufficient stability in vivo for studying their effects in relation to translocation to the pleura. PMID:11418086

  15. Effect of dietary fibre on dough rheology and bread quality

    Microsoft Academic Search

    Manuel Gómez; Felicidad Ronda; Carlos A. Blanco; Pedro A. Caballero; Arancha Apesteguía

    2003-01-01

    Dietary fibre is a common and important ingredient of a new generation of healthy food products demanded more each day by customers. Dietary fibre increases the nutritional value of bread but usually at the same time alters rheological properties of dough and, finally, the quality and sensorial properties of bread. The present work investigates the effect of some purified dietary

  16. Origin and significance of small muscle fibres in neuromuscular disease

    Microsoft Academic Search

    Lok-Ming Tang; Michael Swash

    1987-01-01

    Small muscle fibres, defined as those of less than 40 µm diameter in the male and 30 µm in the female were encountered in muscle biopsies of patients with spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), polymyositis (PM) and myopathy\\/dystrophy. Excessive reactivity with NADH-TR in small fibres did not discriminate between neurogenic and myopathic disorders. Quantification of perifascicular atrophic

  17. Characterisation of fibre metal laminates under thermomechanical loadings

    Microsoft Academic Search

    M. Hagenbeek

    2005-01-01

    Fibre metal laminates, such as Arall or Glare, can offer improved properties compared to monolithic materials. Glare for example shows improved fatigue, residual strength, burn-through, impact and corrosion properties with respect to aluminium 2024, together with a considerable weight reduction and competitive costs. A large research program has proven the technological readiness of Glare and the fibre metal laminate has

  18. The dynamic elastic constants of man-made fibres

    Microsoft Academic Search

    B. D. Rysyuk; M. P. Nosov; S. G. Osinin

    1978-01-01

    In this article the writers give the elastic constants of a series of unoriented fibres and the results of an investigation of the variation of the dynamic moduli of elasticity E~ and shear G~2 of the fibres, with the degree of molecular orientation. The investigation was carried out with commercial monofilaments. The elastic constants were determined from the speeds C

  19. Keeping Light Behind Bars in Photonic Crystal Fibres

    Microsoft Academic Search

    Philip Russell

    2005-01-01

    Photonic crystal fibres (PCFs) have been the focus of increasing scientific and technological interest since the first working example was reported in 1996. Although superficially similar to a conventional optical fibre, PCF has a unique microstructure, consisting of an array of microscopic holes (i.e., channels) running along its entire length. These holes act as optical barriers or scatterers, which suitably

  20. Material property estimates from ultrasound attenuation in fibre suspensions.

    PubMed

    Aitomäki, Yvonne; Löfqvist, Torbjörn

    2009-05-01

    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

  1. SINGLE-BOLTED CONNECTIONS FOR ORTHOTROPIC FIBRE-REINFORCED

    E-print Network

    SINGLE-BOLTED CONNECTIONS FOR ORTHOTROPIC FIBRE-REINFORCED COMPOSITE STRUCTURAL MEMBERS BY CHARLES a glass-fibre-reinforced composite material. A total of 102 single-bolt double-shear lap connections analytical model introduced to descnbe the behaviour of single-bolted connections in composite materials

  2. Mass and momentum transfer in hollow fibre blood oxygenators

    Microsoft Academic Search

    S. R. Wickramasinghe; J. D. Garcia; Binbing Han

    2002-01-01

    Mass transfer and friction factor correlations for microporous hollow fibre blood oxygenators (BOs) have been determined experimentally. Water and glycerol water solutions were used as a substitute for blood. The diffusion of oxygen into and out of water and glycerol water solutions has been studied. The liquid stream flowed outside and across bundles of woven hollow fibres while the gas

  3. Natural fibres as reinforcement in polylactic acid (PLA) composites

    Microsoft Academic Search

    K. Oksman; M. Skrifvars; J.-F. Selin

    2003-01-01

    The focus in this work has been to study if natural fibres can be used as reinforcement in polymers based on renewable raw materials. The materials have been flax fibres and polylactic acid (PLA). PLA is a thermoplastic polymer made from lactic acid and has mainly been used for biodegradable products, such as plastic bags and planting cups, but in

  4. Aspects of the thermodynamic stability of fibre suspension flows

    Microsoft Academic Search

    J. M. W. Munganga; B. D. Reddy; K. J. Diatezua

    2000-01-01

    We examine the circumstances under which the constitutive equations for fibre suspension flows are consistent with the second law of thermodynamics, and the conditions under which fibre suspension flows are stable, in the energetic sense. The constitutive model investigated is that based on the use of orientation tensors, and these issues are examined in the context of a selection of

  5. Phosphate adsorption on chemically modified sugarcane bagasse fibres

    Microsoft Academic Search

    Wender Santana Carvalho; Douglas Ferreira Martins; Fernando Rosa Gomes; Inácio Ramos Leite; Leandro Gustavo da Silva; Reinaldo Ruggiero; Eduardo Mathias Richter

    2011-01-01

    Integral sugarcane bagasse fibres of about 2 cm length that were pre-treated for removal of greases and sugars were carboxymethylated on their surface, retaining about 20% of impurities (as insoluble material and water). The fibres were doped with Fe2+ ion, by dipping in aqueous iron chloride solutions of different concentrations. This material was used to remove phosphate from water. Thermal analyses

  6. Biodegradable composites based on l-polylactide and jute fibres

    Microsoft Academic Search

    David Plackett; Tom Løgstrup Andersen; Walther Batsberg Pedersen; Lotte Nielsen

    2003-01-01

    Biodegradable polymers can potentially be combined with plant fibres to produce biodegradable composite materials. In our research, a commercial l-polylactide was converted to film and then used in combination with jute fibre mats to generate composites by a film stacking technique. Composite tensile properties were determined and tensile specimen fracture surfaces were examined using environmental scanning electron microscopy. Degradation of

  7. Inertial effects on fibre motion in simple shear flow

    Microsoft Academic Search

    G. Subramanian; Donald L. Koch

    2005-01-01

    The motion of a torque-free slender axisymmetric fibre in simple shear flow is examined theoretically for small but finite Re, where Re is the Reynolds number based on the fibre length, and is a measure of the inertial forces in the fluid. In the limit of zero inertia, an axisymmetric particle in simple shear is known to rotate indefinitely in

  8. Supercontinuum Generation in a Photonic Crystal Fibre

    NASA Astrophysics Data System (ADS)

    Yan, Pei-Guang; Ruan, Shuang-Chen; Lin, Hao-Jia; Du, Chen-Lin; Yu, Yong-Qin; Lu, Ke-Cheng; Yao, Jian-Quan

    2004-06-01

    Nearly 1000-nm broad continuum from 390 nm to 1370 nm is generated in a 2-m long photonic crystal fibre. The maximum total power of supercontinuum is measured to be 60 mW with the pumping power of 800 mW output from a 200-fs Ti:sapphire laser. The evolution of the pumping light into supercontinuum is experimentally studied in detail. It is found that the mechanism for supercontinuum generation has direct relations with Raman effect and soliton effect, and the four-wave mixing plays an important role in the last phase of the supercontinuum generation.

  9. Type number and rigidity of fibred surfaces

    SciTech Connect

    Markov, P E [Rostov State University, Rostov-on-Don (Russian Federation)

    2001-02-28

    Infinitesimal l-th order bendings, 1{<=}l{<=}{infinity}, of higher-dimensional surfaces are considered in higher-dimensional flat spaces (for l={infinity} an infinitesimal bending is assumed to be an analytic bending). In terms of the Allendoerfer type number, criteria are established for the (r,l)-rigidity (in the terminology of Sabitov) of such surfaces. In particular, an (r,l)-infinitesimal analogue is proved of the classical theorem of Allendoerfer on the unbendability of surfaces with type number {>=}3 and the class of (r,l)-rigid fibred surfaces is distinguished.

  10. Single-Mode Quadruple-Core Optical Fibres

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.

    1990-01-01

    Special optical fibres (SOF) are gaining in interest because of their increasing potential applications in optical sensing and (coherent, distributed) optical signal processing technologies. Classical optical fibres, optimized for communications, give much poorer performance of the sensory system than give specialty fibres optimized for sensing and direct optical signal processing. The specialty fibres, or at least some of their families, are technologically sensitized to the desired measurand and simultaneously desensitized to the most of harmful external reactions from the environment. We are manufacturing our specialty fibres using three major technologies - all of them actually hybrid: multi-rod-in-tube (MRiT), multi-crucible-zone-diaphragm (MZD) and mosaic assembling defibering (MAD/MAT). Some of these technologies use, in certain cases, MCVD processes and other high-temperature sub-stages.

  11. Flying particle sensors in hollow-core photonic crystal fibre

    NASA Astrophysics Data System (ADS)

    Bykov, D. S.; Schmidt, O. A.; Euser, T. G.; Russell, P. St. J.

    2015-07-01

    Optical fibre sensors make use of diverse physical effects to measure parameters such as strain, temperature and electric field. Here we introduce a new class of reconfigurable fibre sensor, based on a ‘flying-particle’ optically trapped inside a hollow-core photonic crystal fibre and illustrate its use in electric field and temperature sensing with high spatial resolution. The electric field distribution near the surface of a multi-element electrode is measured with a resolution of ?100??m by monitoring changes in the transmitted light signal due to the transverse displacement of a charged silica microparticle trapped within the hollow core. Doppler-based velocity measurements are used to map the gas viscosity, and thus the temperature, along a hollow-core photonic crystal fibre. The flying-particle approach represents a new paradigm in fibre sensors, potentially allowing multiple physical quantities to be mapped with high positional accuracy over kilometre-scale distances.

  12. Design and construction of the fibre system for FMOS

    NASA Astrophysics Data System (ADS)

    Murray, Graham J.; Dodsworth, George N.; Content, Robert; Tamura, Naoyuki

    2008-07-01

    A consortium of Japanese, Australian and UK groups has developed a fibre-fed near IR (J & H band) multi-object spectrographic facility (FMOS) for the Subaru telescope. In this second-generation instrument, a novel prime focus 400-fibre multi-object positioning system, ECHIDNA, is optically linked via twin cables to dual IR spectrographs. The spectrographs are located some distance away, on a dedicated platform two levels above Nasmyth. The Centre for Advanced Instrumentation at Durham University oversaw the design and construction of the optical fibre system linking ECHIDNA to the spectrographs. A modularised connector within the cable scheme and an integral back illumination unit additionally featured as part of the Durham work-package. At the time of writing (mid 2008) FMOS, including the fibre system, is installed and functional on-telescope, with commissioning currently underway. This paper provides an overview of the design and construction of the optical fibre system.

  13. Enhanced sensitivity fibre Bragg grating (FBG) load sensor

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    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 the period of the embedded section of the FBG. This creates a spectral dropout within the bandwidth of the FBG, with an absolute wavelength that is linearly dependent on the applied load. This technique enhances the sensitivity of the FBG to transverse loading by a factor of 15, to 2.9 × 10-2 ± 0.01 nm N-1, when compared to the direct transverse loading of a bare fibre, and also protects the fibre from mechanical damage at the loading point.

  14. Nox4 Is Dispensable for Exercise Induced Muscle Fibre Switch

    PubMed Central

    Vogel, Juri; Figueiredo de Rezende, Flávia; Rohrbach, Susanne; Zhang, Min; Schröder, Katrin

    2015-01-01

    Introduction By producing H2O2, the NADPH oxidase Nox4 is involved in differentiation of mesenchymal cells. Exercise alters the composition of slow and fast twitch fibres in skeletal. Here we hypothesized that Nox4 contributes to exercise-induced adaptation such as changes in muscle metabolism or muscle fibre specification and studied this in wildtype and Nox4-/- mice. Results Exercise, as induced by voluntary running in a running wheel or forced running on a treadmill induced a switch from fast twitch to intermediate fibres. However the induced muscle fibre switch was similar between Nox4-/- and wildtype mice. The same held true for exercise-induced expression of PGC1? or AMPK activation. Both are increased in response to exercise, but with no difference was observed between wildtype and Nox4-/- mice. Conclusion Thus, exercise-induced muscle fibre switch is Nox4-independent. PMID:26083642

  15. Advanced materials and techniques for fibre-optic sensing

    NASA Astrophysics Data System (ADS)

    Henderson, Philip J.

    2014-06-01

    Fibre-optic monitoring systems came of age in about 1999 upon the emergence of the world's first significant commercialising company - a spin-out from the UK's collaborative MAST project. By using embedded fibre-optic technology, the MAST project successfully measured transient strain within high-performance composite yacht masts. Since then, applications have extended from smart composites into civil engineering, energy, military, aerospace, medicine and other sectors. Fibre-optic sensors come in various forms, and may be subject to embedment, retrofitting, and remote interrogation. The unique challenges presented by each implementation require careful scrutiny before widespread adoption can take place. Accordingly, various aspects of design and reliability are discussed spanning a range of representative technologies that include resonant microsilicon structures, MEMS, Bragg gratings, advanced forms of spectroscopy, and modern trends in nanotechnology. Keywords: Fibre-optic sensors, fibre Bragg gratings, MEMS, MOEMS, nanotechnology, plasmon.

  16. Design of erbium doped double clad ZBLAN Fibre laser

    NASA Astrophysics Data System (ADS)

    Oladeji, A.; Phillips, A.; Lamrini, S.; Scholle, K.; Fuhrberg, P.; Seddon, A. B.; Benson, T. M.; Sujecki, S.

    2015-06-01

    A high powered octagonal double clad ZBLAN (33 ?m/330 ?m, NA=0.13) glass fibre for mid-infrared light generation is studied using a one dimensional rate equation model. The fibre laser design employs the concept of cascade lasing and includes up-conversion phenomena. The results obtained demonstrate that efficient cascade lasing may be achieved in practice without the need for fibre grating fabrication, as a sufficient level of feedback for laser action is provided by Fresnel light reflection at ZBLAN glass fibre air interfaces. Further enhancement of the laser efficiency can be achieved by terminating one of the fibre ends with a mirror. Simulation results show that the laser operation with 20 W of pump power at 0.98 ?m wavelength can be achieved at 2.75 ?m operating wavelength with Er3+ ion concentrations of 60,000 ppm.

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

    PubMed Central

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

    2013-01-01

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

  18. FRD in optical fibres at low temperatures: investigations for Gemini's Wide-field Fibre Multi-Object Spectrograph

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. C.; de Oliveira, L. S.; Dos Santos, J. B.; Arruda, M. V.; Dos Santos, L. G. C.; Rodrigues, F.; de Castro, F. L. F.

    2011-06-01

    While there is no direct evidence for the deterioration in Focal Ratio Degradation (FRD) of optical fibres in severe temperature gradients, the fibre ends inserted into metallic containment devices such as steel ferrules can be a source of stress, and hence increased FRD at low temperatures. In such conditions, instruments using optical fibres may suffer some increase in FRD and consequent loss of system throughput when they are working in environments with significant thermal gradients, a common characteristic of ground-based observatories. In this paper we present results of experiments with optical fibres inserted in different materials as a part of our prototyping study for Gemini's Wide-field Multi-Object Spectrograph (WFMOS) project. Thermal effects and the use of new holding techniques will be discussed in the context of Integral Field Units and multi-fibres systems. In this work, we have used careful methodologies that give absolute measurements of FRD to quantify the advantages of using epoxy-based composites rather than metals as support structures for the fibre ends. This is shown to be especially important in minimizing thermally induced stresses in the fibre terminations. Not only is this important for optimizing fibre spectrograph performance but the benefits of using such materials are demonstrated in the minimization of positional variations and the avoidance of metal-to-glass delamination. Furthermore, by impregnating the composites with small zirconium oxide particles the composite materials supply their own fine polishing grit which aids significantly to the optical quality of the finished product.

  19. Fibrogenesis by mineral fibres: an in-vitro study of the roles of the macrophage and fibre length.

    PubMed Central

    Aalto, M.; Heppleston, A. G.

    1984-01-01

    Evidence on the mechanism by which inhaled mineral fibres lead to pulmonary fibrosis has not been forthcoming. As with silica, a biphasic cell culture system was required to distinguish phagocytosis from collagen formation. Synthesis of total protein and collagen by rat fibroblasts was estimated by incorporation of labelled proline after treatment with the medium from rat peritoneal macrophages that had been cultured in the presence of different types of mineral fibre. The influence of fibre length was also examined. All the main varieties of asbestos reacted with macrophages to produce or release a fibrogenic factor. However, chrysotile and the longer amosite fibres evoked the response only after prolonging the period of incubation with macrophages, presumably by permitting more complete phagocytosis of curled or longer fibres. Short amosite fibres proved to be more active than longer ones and under certain conditions were as potent as quartz. Fibrous glass also possessed stimulatory properties and again a sample having a short length gave a stronger response than a long one. Collagen formation by asbestos thus appears to be mediated by a macrophage factor, so operating in a manner similar to that previously demonstrated for quartz. The conventional view that short fibres are comparatively insignificant in asbestos fibrogenesis cannot, on the present evidence, be sustained. Furthermore, it should not be assumed than man-made mineral fibres of respirable diameter are innocuous or that short ones can be ignored. PMID:6696832

  20. Cellulose microfibril angle in the cell wall of wood fibres.

    PubMed

    Barnett, J R; Bonham, Victoria A

    2004-05-01

    The term microfibril angle (MFA) in wood science refers to the angle between the direction of the helical windings of cellulose microfibrils in the secondary cell wall of fibres and tracheids and the long axis of cell. Technologically, it is usually applied to the orientation of cellulose microfibrils in the S2 layer that makes up the greatest proportion of the wall thickness, since it is this which most affects the physical properties of wood. This review describes the organisation of the cellulose component of the secondary wall of fibres and tracheids and the various methods that have been used for the measurement of MFA. It considers the variation of MFA within the tree and the biological reason for the large differences found between juvenile (or core) wood and mature (or outer) wood. The ability of the tree to vary MFA in response to environmental stress, particularly in reaction wood, is also described. Differences in MFA have a profound effect on the properties of wood, in particular its stiffness. The large MFA in juvenile wood confers low stiffness and gives the sapling the flexibility it needs to survive high winds without breaking. It also means, however, that timber containing a high proportion of juvenile wood is unsuitable for use as high-grade structural timber. This fact has taken on increasing importance in view of the trend in forestry towards short rotation cropping of fast grown species. These trees at harvest may contain 50% or more of timber with low stiffness and therefore, low economic value. Although they are presently grown mainly for pulp, pressure for increased timber production means that ways will be sought to improve the quality of their timber by reducing juvenile wood MFA. The mechanism by which the orientation of microfibril deposition is controlled is still a matter of debate. However, the application of molecular techniques is likely to enable modification of this process. The extent to which these techniques should be used to improve timber quality by reducing MFA in juvenile wood is, however, uncertain, since care must be taken to avoid compromising the safety of the tree. PMID:15191232

  1. A theory for the free shrinkage of steel fibre reinforced cement matrices

    Microsoft Academic Search

    P. S. Mangat; M. Motamedi Azari

    1984-01-01

    The paper presents a theoretical model to predict the free shrinkage of cement matrices reinforced with randomly oriented discrete steel fibres. The model is based on the consideration that the equivalent aligned length of a random fibre is responsible for restraining the shrinkage of a thick matrix cylinder of diameter equal to the fibre spacing, through the fibre-matrix interfacial bond

  2. Assessment of the tensile properties of coir, bamboo and jute fibre

    Microsoft Academic Search

    Nele Defoirdt; Subhankar Biswas; Linde De Vriese; Le Quan Ngoc Tran; Joris Van Acker; Qumrul Ahsan; Larissa Gorbatikh; Aart Van Vuure; Ignaas Verpoest

    2010-01-01

    Natural fibres are studied as alternatives for man-made fibres to reinforce composites while keeping the weight lower. The assessment of the value of some commonly available tropical fibres for the composite industry starts with the determination of the strength, E-modulus and strain to failure through single fibre tensile tests. The mean strength and standard deviation is calculated following the normal

  3. Influence of laser irradiation on the optical and structural properties of poly(ethylene terephthalate) fibres

    Microsoft Academic Search

    V. N. Wijayathunga; C. A. Lawrence; R. S. Blackburn; M. P. U. Bandara; E. L. V. Lewis; H. M. El-Dessouky; V. Cheung

    2007-01-01

    Laser irradiation has been previously investigated for achieving uniform heating of polyethylene terephthalate (PET) fibres in the hot-drawing stage of the production process, so as to obtain better fibre mechanical properties. The optical properties and dye uptake of PET fibres also depend on the polymer chain orientation and crystallinity within the fibre structure. This paper reports an investigation of a

  4. Investigation of the degradation of thermoplastic polyurethane reinforced with short fibres

    Microsoft Academic Search

    Ronaldo A. Corrêa; Regina C. R. Nunes; Vera L. Lourenço

    1996-01-01

    The thermal behaviour of short fibre reinforced composites was studied by DSC and TGA techniques. A thermoplastic polyurethane elastomer was used as the matrix and carbon fibre or aramid fibre as reinforcing fillers in each composite. The influence of short fibres on the thermal resistance of the matrix, glass transition temperature and kinetic parameters of the degradation reaction of the

  5. Optical fibres in biomedical applications: Effect of a biological medium on static fatigue

    Microsoft Academic Search

    William G. A. Brown; Christopher D. Easton; Andrea R. Leong; Catherine M. Wade; Paul R. Stoddart; Scott A. Wade

    2010-01-01

    Summary Optical fibres are finding expanding applications in medicine. This work presents time-to-failure measurements of optical fibres under static stress in a simulated bodily fluid; intended for use in the development of medical fibre optic devices. Keywords-optical fibre, static fatigue, biological media

  6. Thermogravimetric and dynamic mechanical thermal analysis of pineapple fibre reinforced polyethylene composites

    Microsoft Academic Search

    J. George; S. S. Bhagawan; S. Thomas

    1996-01-01

    The thermal behaviour of pineapple leaf fibre (PALF) reinforced polyethylene composites was studied by thermogravimetric and dynamic mechanical thermal analysis. Fibre treatment was carried out using isocyanate, silane and peroxide to improve the interfacial adhesion between fibre and matrix. The effects of fibre loading and surface modification on the thermal properties were evaluated. It was found that at high temperature

  7. Melt rheological behaviour of short pineapple fibre reinforced low density polyethylene composites

    Microsoft Academic Search

    Sabu Thomas; R JANARDHAN; J ANAND; S BHAGAWAN; S THOMAS

    1996-01-01

    The melt theological behaviour of short pineapple fibre reinforced low density polyethylene composite has been studied using a capillary rheometer. The influence of fibre loading, fibre length, and fibre treatment on the theology of composites was investigated. Studies were carried out in the temperature range of 125 to 145°C and shear rate of 016.4 to 5468 s?1. The melt viscosity

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

    Microsoft Academic Search

    Wadood Y. Hamad; James W. Provan

    1995-01-01

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

  9. Mechanical properties of self-compacting concrete reinforced with polypropylene fibres

    E-print Network

    North Texas, University of

    Mechanical properties of self-compacting concrete reinforced with polypropylene fibres O. Gencel*1, the workability and mechanical properties of SCC with fly ash reinforced with monofilament polypropylene fibres no problems with mixing or workability when the fibre distribution is uniform. The polypropylene fibres

  10. Capillarity of flax\\/linseed ( Linum usitatissimum L.) and fibre hemp ( Cannabis sativa L.) straw fractions

    Microsoft Academic Search

    H.-R Kymäläinen; M Hautala; R Kuisma; A Pasila

    2001-01-01

    In a study of the wetting properties of the fractions of unretted and frost-retted fibre straws a method to separate fibre, fine shive, and coarse shive from fibre plants is introduced and tested on bast fibre plants (Linum usitatissimum L. and Cannabis sativa L.) The method consists of optional drying of stalks, cutting of straws, milling the straws with a

  11. Pultruded fibre-reinforced furfuryl alcohol resin composites: 2. Static, dynamic mechanical and thermal properties

    Microsoft Academic Search

    C. C. M Ma; M. S Yn; J. L Han; C. J Chang; H. D Wu

    1995-01-01

    A novel process has been developed to manufacture pultruded fibre-reinforced furfuryl alcohol (FA) resin composites. In this paper, the effects of fibre reinforcement type and content on the static, dynamic mechanical and thermal properties of the FA resin pultruded composites are investigated. The mechanical properties increase with increasing volume content of the glass or carbon fibres, with the glass fibre-reinforced

  12. Impact fatigue behaviour of vinylester resin matrix composites reinforced with alkali treated jute fibres

    Microsoft Academic Search

    D Ray; B. K Sarkar; N. R Bose

    2002-01-01

    An impact fatigue study has been made for the first time on 35% jute\\/vinylester composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the composites made from treated fibre were superior. 4h alkali treated jute fibres gave the optimum combination of

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

    NASA Astrophysics Data System (ADS)

    Lorenz, Pierre; Ehrhardt, Martin; Zimmer, Klaus

    2014-05-01

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

  14. Design, manufacture and testing of self-sensing carbon fibre glass fibre reinforced polymer rods

    NASA Astrophysics Data System (ADS)

    Nanni, F.; Ruscito, G.; Forte, G.; Gusmano, G.

    2007-12-01

    At present much attention is being devoted to the study of self-monitoring materials, which simultaneously offer good structural and sensing properties. In the present study self-sensing carbon-glass hybrid structural composites, behaving as 'guard' sensors (i.e. they give a warning when fixed loads are reached) were designed, manufactured and tested. In particular, samples containing different carbon fibre/glass fibre ratios were prepared and tested, by performing both mechanical (monotonic and cycle tensile tests) and electrical measurements. The results showed the efficiency of the proposed system and the possibility to design such materials to suit any specific application need. The advantages of these materials, compared to other more sophisticated monitoring systems, are the ease of fabrication and use, low production costs and versatility, so such materials are suitable for widespread low-cost applications.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  16. Dynamics of similariton pulses in length-inhomogeneous active fibres

    SciTech Connect

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

    2010-05-26

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

  17. All-fibre ytterbium laser tunable within 45 nm

    SciTech Connect

    Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Kurkov, A S [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2007-12-31

    A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

  18. Weibull analysis of strength-length relationships in single Nicalon SiC fibres

    Microsoft Academic Search

    H. F. Wu; A. N. Netrwavali

    1992-01-01

    Nicalon SiC fibre is naturally brittle and offers high-temperature application in fibrous composites. Due to the randomly distributed flaws along the fibre, the statistical variability in single-fibre strength is obvious. In this paper, the effect of heat-cleaning procedures on Nicalon fibres has been investigated, and the statistical strength and variability of single Nicalon fibres have been characterized in tension and

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

    Microsoft Academic Search

    C. Y. Yue; K. Padmanabhan

    1999-01-01

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

  20. Gene effects for fibre properties in upland cotton ( Gossypium hirsutum L.)

    Microsoft Academic Search

    R. S. Pathak

    1975-01-01

    Six populations — P1,P2,F1,F2,B1 and B2 — each of five Upland Cotton (Gossypium hirsutum L.) crosses were used to evaluate gene effects in the inheritance of fibre properties by Gamble's six-parameter model for the analysis of generation means. Partial dominance of long fibres over short fibres and of mature fibres over immature fibres was found in the material studied. Overdominance

  1. High dietary fibre powders from orange and lime peels: associated polyphenols and antioxidant capacity

    Microsoft Academic Search

    José A. Larrauri; Pilar Rupérez; Laura Bravo; Fulgencio Saura-Calixto

    1996-01-01

    High dietary fibre powders from Valencia orange and Persa lime peels were prepared and their dietary fibre composition and antioxidant capacity studied. Fibres from both peels had a high total dietary fibre content (61–69%) with an appreciable amount of soluble fibre (19–22%). The concentration of antioxidant [AA50] required to achieve a 50% inhibition of oxidation of linoleic acid at 40°C

  2. Sensitive protein detection using an optical fibre long period grating sensor anchored with silica core gold shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Marques, L.; Hernandez, F. U.; Korposh, S.; Clark, M.; Morgan, S.; James, S.; Tatam, R. P.

    2014-05-01

    An optical fibre long period grating (LPG), modified with a coating of silica gold (SiO2:Au) core/shell nanoparticles (NPs) deposited using the layer-by-layer (LbL) method, was employed for the development of a bio-sensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(hydrochloride ammonium) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The lowest detected concentration of SV was 19 nM using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film.

  3. Fibre bundle framework for quantum fault tolerance

    NASA Astrophysics Data System (ADS)

    Zhang, Lucy Liuxuan; Gottesman, Daniel

    2014-03-01

    We introduce a differential geometric framework for describing families of quantum error-correcting codes and for understanding quantum fault tolerance. In particular, we use fibre bundles and a natural projectively flat connection thereon to study the transformation of codewords under unitary fault-tolerant evolutions. We'll explain how the fault-tolerant logical operations are given by the monodromy group for the bundles with projectively flat connection, which is always discrete. We will discuss the construction of the said bundles for two examples of fault-tolerant families of operations, the string operators in the toric code and the qudit transversal gates. This framework unifies topological fault tolerance and fault tolerance based on transversal gates, and is expected to apply for all unitary quantum fault-tolerant protocols.

  4. An Historic Overview of the Development of Fibre Metal Laminates

    NASA Astrophysics Data System (ADS)

    Vermeeren, C. A. J. R.

    2003-07-01

    In this paper a brief overview of the history of Fibre Metal Laminates Arall and Glare is given as background information for the other, technical articles in this journal. The story of the development of Fibre Metal Laminates is rather a unique story in the history of aircraft materials: A university laboratory invented, developed and certified an aircraft material. Many parties were involved naturally, yet the very heart of the activity was the Structures and Materials Laboratory of the Faculty of Aerospace Engineering of Delft University of Technology in The Netherlands. At the break of the world's largest passenger transport aircraft, the Airbus A380, in which a substantial part of the fuselage will be made of Glare, the glass fibre-aluminium version of Fibre Metal Laminates, it is a good moment to tell some of its history.

  5. Optomechanical and optoacoustic phenomena in microstructured silica fibres

    NASA Astrophysics Data System (ADS)

    Butsch, A.; Kang, M. S.; Euser, T. G.; Russell, Philip St. J.

    2013-02-01

    Recent results on optomechanical and optoacoustic nonlinearities in optical fibres are reported. In a new type of a microstructured silica fibre, comprising two ultra-thin closely spaced glass waveguides, an extremely high and optically broadband optomechanical nonlinearity is shown to occur. This nonlinearity originates from the optical gradient forces between coupled waveguides, can exceed the Kerr effect by many orders of magnitude and allows the formation of stable self-trapped optical modes that represent a novel kind of optical soliton. Furthermore, optoacoustic interaction via electrostriction in the micron-sized core of a photonic crystal fibre is studied. It is demonstrated, that coherent optically-driven acoustic waves, tightly guided in the core, can facilitate in-fibre dynamic optical isolation and all-optical switching.

  6. Graphene chiral liquid crystals and macroscopic assembled fibres

    PubMed Central

    Xu, Zhen; Gao, Chao

    2011-01-01

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

  7. Fibre Raman amplifier pumped by continuous-spectrum radiation

    SciTech Connect

    Kobtsev, Sergey M; Pustovskikh, Aleksei A [Novosibirsk State University, Novosibirsk (Russian Federation)

    2004-06-30

    The results of numerical calculations of a fibre Raman amplifier pumped by continuous-spectrum radiation are presented. It is shown that the Raman gain flatness better than 0.1 dB can be achieved in the spectral region between 1528 and 1599 nm at the average gain of 7.7 dB, and the gain flatness of 0.042 dB in the case of the zero average small-signal gain in a 25-km SMF-28 fibre pumped by the 1-W and 364-mW backward radiation, respectively. Different variants of the approximation of the found optimal pump spectrum by a combination of four discrete radiation sources with broadened spectral lines are studied. (optical fibres and fibre lasers)

  8. Apparent intravoxel fibre population dispersion (FPD) using spherical harmonics.

    PubMed

    Assemlal, Haz-Edine; Campbell, Jennifer; Pike, Bruce; Siddiqi, Kaleem

    2011-01-01

    The vast majority of High Angular Resolution Diffusion Imaging (HARDI) modeling methods recover networks of neuronal fibres, using a heuristic extraction of their local orientation. In this paper, we present a method for computing the apparent intravoxel Fibre Population Dispersion (FPD), which conveys the manner in which distinct fibre populations are partitioned within the same voxel. We provide a statistical analysis, without any prior assumptions on the number or size of these fibre populations, using an analytical formulation of the diffusion signal autocorrelation function in the spherical harmonics basis. We also propose to extract features of the FPD obtained in the group of rotations, using several metrics based on unit quaternions. We show results on simulated data and on physical phantoms, that demonstrate the effectiveness of the FPD to reveal regions with crossing tracts, in contrast to the standard anisotropy measures. PMID:21995025

  9. Phase delay of polarisation modes in elastically twisted spun fibres

    SciTech Connect

    Morshnev, Sergey K; Chamorovsky, Yury K; Vorob'ev, Igor' L [Kotel'nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino branch, Fryazino, Moscow Region (Russian Federation)

    2011-05-31

    The evolution of the phase delay between linearly polarised orthogonal modes in a spun fibre elastically twisted around its axis has been studied experimentally and theoretically using a model for a helical structure of the built-in linear birefringence axes. The phase delay is a sinusoidal function of elastic twist angle, with an amplitude and period dependent on fibre parameters: spin pitch and built-in linear birefringence beat length. It is shown that, at a known spin pitch, phase delay versus elastic twist angle data can be used to determine the beat length of built-in linear birefringence in the range 0.01 to 100 mm. The theoretical analysis results are supported by experimental data for conventional and microstructured spun fibres. (fibre optics)

  10. Meniscus on a shaped fibre: singularities and hodograph formulation.

    PubMed

    Alimov, Mars M; Kornev, Konstantin G

    2014-08-01

    Using the method of matched asymptotic expansions, the problem of the capillary rise of a meniscus on the complex-shaped fibres was reduced to a nonlinear problem of determination of a minimal surface. This surface has to satisfy a special boundary condition at infinity. The proposed formulation allows one to interpret the meniscus problem as a problem of flow of a fictitious non-Newtonian fluid through a porous medium. As an example, the shape of a meniscus on a fibre of an oval cross section was analysed employing Chaplygin's hodograph transformation. It was discovered that the contact line may form singularities even if the fibre has a smooth profile: this statement was illustrated with an oval fibre profile having infinite curvature at two endpoints. PMID:25104910

  11. Dietary fibre and colon cancer: epidemiologic and experimental evidence.

    PubMed Central

    Reddy, B S

    1980-01-01

    Epidemiologic studies have identified two dietary factors, a relatively high intake of fat and a relatively low intake of fibre, that are associated with colon cancer in humans. However, a recent study has shown a low risk of large bowel cancer in a rural Finnish population with a high dietary intake of fat, but also a high intake of fibre. Observations in humans and studies in animals have indicated that dietary fibre may protect against colon carcinogenesis by binding bile acids in the intestinal tract, by a direct effect on the colonic mucosa and by an indirect effect on the metabolism of carcinogens. The strength of protection varies with the type of fibre. PMID:6254626

  12. Modelling of a novel hollow-core photonic crystal fibre

    Microsoft Academic Search

    T. D. Hedley; D. M. Bird; F. Benabid; J. C. Knight; P.St.J. Russell

    2003-01-01

    A hollow-core photonic crystal fibre that guides light over a broad range of frequencies has been developed. Calculations indicate that guidance is due to a low density of states of the cladding structure near the air line.

  13. Exploiting multimode waveguides for pure fibre-based imaging

    PubMed Central

    ?ižmár, Tomáš; Dholakia, Kishan

    2012-01-01

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

  14. The Formation and Binding of Gold Nanoparticles onto Wool Fibres

    SciTech Connect

    Johnston, James H.; Burridge, Kerstin A.; Kelly, Fern M. [School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140 (New Zealand)

    2009-07-23

    This paper presents the novel use of nanosize gold with different plasmon resonance colours, as stable colourfast colourants on wool fibres for use in high quality fabrics and textiles. The gold nanoparticles are synthesised by the controlled reduction of Au{sup 3+} in the AuCl{sub 4}{sup -} complex to Au{sup 0} onto the surface of the wool where they attach to the S in the cystine amino acids in wool keratin proteins. Scanning electronmicroscopy shows the nanoparticles are present on the cuticles of the fibre surface and are concentrated at the edges of these cuticles. EDS analysis shows a strong correlation of Au with S and X-ray photoelectron spectroscopy suggests Au-S bond formation. Hence the nanogold colourants are chemically bound to the wool fibre surface and do not fade as traditional organic dyes do. A range of coloured fibres have been produced.

  15. Earth's Layers

    NSDL National Science Digital Library

    Mrs. Walls

    2011-01-30

    Complete a poster all about Earth's Layers! Directions: Make a poster about Earth's Layers. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about Earth's Layers. (5 points each) (15 points) Write at least a three sentence summary of your poster ...

  16. Electron microscopy study of mesophase pitch-based graphite fibres

    Microsoft Academic Search

    E. J. Roche; E. I. DuPont de Nemours

    1990-01-01

    A comprehensive electron microscopic investigation of the structure of the graphitic sheet in mesophase pitch-based fibres is presented.In situ brightfield and (00l) darkfield observation of the sheets in sub micrometre fibres reveals a finely striated structure, associated with three-dimensional order. (hkl) darkfield imaging of the sheets in their edge-on and face-on orientations indicates that the striations correspond to the edge

  17. Compression creep behaviour of steel fibre reinforced cement composites

    Microsoft Academic Search

    P. S. Mangat; M. Motamedi Azari

    1986-01-01

    The paper presents the results of an experimental investigation to determine the influence of steel fibre reinforcement on\\u000a the creep of cement matrices under compression. Creep tests were carried out at a number of applied stress-strength ratios\\u000a ranging between 0.3 to 0.9. Melt extract and hooked steel fibres were used at volume fractions ranging between 0 and 3% by\\u000a volume

  18. SOLITONS: Nonreciprocal dynamics of pulses in a nonlinear inhomogeneous fibre

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  19. Interfaces in nickel aluminide\\/alumina fibre composites

    Microsoft Academic Search

    G. L. Povirk; J. A. Horton; C. G. McKamey; T. N. Tiegs; S. R. Nutt

    1988-01-01

    Metal matrix composites based on the intermetallic alloy Ni3Al and fibres of Al2O3 were fabricated by hot-pressing nickel aluminide powders and alumina fibres. Two matrix alloys were used in this investigation: Ni3Al microalloyed with boron and Ni3Al alloyed with 8 at% chromium and smaller amounts of zirconium and boron. The materials were studied using optical and transmission electron microscopy with

  20. Mechanical properties of polypropylene reinforced with recycled-pet fibres

    Microsoft Academic Search

    Palova Santos; Sérgio Henrique Pezzin

    2003-01-01

    We present an experimental study of the incorporation of fibres of recycled poly(ethylene terephthalate) (PET) in polypropylene (PP). Composites of PP\\/PET with 3, 5 and 7% of PET fibres (w\\/w) were prepared by monoscrew extrusion followed by injection moulding and the mechanical behaviour was estimated by the measurement of the tensile strength, the Izod impact strength and the surface hardness

  1. Intracavity absorption spectroscopy with thulium-doped fibre laser

    Microsoft Academic Search

    A. Stark; L. Correia; M. Teichmann; S. Salewski; C. Larsen; V. M Baev; P. E Toschek

    2003-01-01

    For applications to intracavity laser absorption spectroscopy, we study the spectral properties of a multimode Tm3+-doped silica fibre laser pumped by a diode laser. In cw operation, the emission spectrum of the fibre laser is typically 4 nm wide and can be tuned from 1.70 to 1.98 ?m. It shows many absorption lines of H2O and CO2 due to the

  2. Measurement of magnetic field using Rayleigh backscattering in optical fibres

    SciTech Connect

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

    2011-07-01

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

  3. Active optical fibres in modern particle physics experiments

    Microsoft Academic Search

    Carsten Patrick Achenbach

    2004-01-01

    In modern particle physics experiments wavelength-shifting and scintillating\\u000afibres based on plastic polymers are used for tracking and calorimetry. In this\\u000areview the role of photon trapping efficiencies, transmission functions and\\u000asignal response times for common multimode active fibres is discussed.\\u000aNumerical simulations involving three dimensional tracking of skew rays through\\u000acurved fibres demonstrate the characteristics of trapped light. Of

  4. Z-Pinch Experiments with Styrofoam Fibres and Plasmajets

    Microsoft Academic Search

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

    1994-01-01

    Z-pinch plasmas created from fibres are less prone to macroscopic instabilities than predicted by ideal MHD theory. However, solid fibre experiments at the pulseline KALIF (2 MV, 900 kA) gave disappointing results with respect to driver-load coupling and pinch plasma confinement. High power discharges led to current leaks and plasma expansion presumably due to lacking initial conductivity and compressibility. Therefore

  5. Stabilized polyglycolic acid fibre-based tubes for tissue engineering

    Microsoft Academic Search

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

    1996-01-01

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

  6. Fluorescence based optical fibre fire alarm system [for aeroengine application

    Microsoft Academic Search

    T. Sun; K. T. V. Grattan; W. M. Sun

    2002-01-01

    A fluorescence-based optical fibre fire alarm system, which offers the advantages of light weight and relatively low cost, has been discussed to address the specifications required for aeroengine fire detection. A temperature excursion as low as 50-100°C has been detected and current spatial resolution achieved is ?20 cm. Lengths of 1.2 m of Er & Tm doped fibres have been

  7. Selection of optical modes in multichannel fibre lasers

    SciTech Connect

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

    2006-01-31

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

  8. Low-impulse blast behavior of fibre-metal laminates

    Microsoft Academic Search

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

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

  9. Influence of fluorination on the properties of carbon fibres

    Microsoft Academic Search

    A. Bismarck; R. Tahhan; J. Springer; A. Schulz; T. M. Klapötke; H. Zeil; W. Michaeli

    1997-01-01

    Various fluorination methods were applied to modify the surfaces of carbon fibres. Mild fluorination techniques, such as low pressure fluorine at various temperatures and pressures, were compared with strong fluorination agents, such as HF-F2 mixtures or ClF3. The relationship between the degree of fluorination and the physical and chemical properties of two polyacrylonitrile-based carbon fibres (Torayca, FT 300 6000-99; Sign,

  10. Mechanical properties of woven banana fibre reinforced epoxy composites

    Microsoft Academic Search

    S. M. Sapuan; A. Leenie; M. Harimi; Y. K. Beng

    2006-01-01

    In this paper, the experiments of tensile and flexural (three-point bending) tests were carried out using natural fibre with composite materials (Musaceae\\/epoxy). Three samples prepared from woven banana fibre composites of different geometries were used in this research. From the results obtained, it was found that the maximum value of stress in x-direction is 14.14MN\\/m2, meanwhile the maximum value of

  11. Next generation of optical fibre sensors: new concepts and perspectives

    NASA Astrophysics Data System (ADS)

    Thévenaz, Luc

    2014-05-01

    Fibre sensing has reached an interesting turning point today: a clearer assessment about promises that were really held and those that failed to convince can be envisioned. A choice of key fibre sensing techniques will be reviewed and a critical discussion about their real impact will be presented. The promising potentialities of distributed sensing in its different flavours will be addressed, without omitting perspectives on other major techniques, such as Bragg gratings and chemical sensors.

  12. On fibre debonding effects and the mechanism of transverse-ply failure in cross-ply laminates of glass fibre\\/thermoset composites

    Microsoft Academic Search

    J. E. Bailey; A. Parvizi

    1981-01-01

    The mechanism of transverse-ply failure in cross-ply laminates of glass fibre thermoset composites has been investigated. It is shown that fibre debonding initiates failure, the debonds subsequently joining up to form a transverse crack nucleus. In the epoxy system investigated fibre debonding causes an observable whitening effect and small modulus change; this effect is reversible in that rebonding can be

  13. Fire Retardancy of Natural Fibre Reinforced Sheet Moulding Compound

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Rolfe, Peter; Scopesi, Fabio; Serra, Giovanni

    2007-06-01

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

  15. Novel technique for solar power illumination using plastic optical fibres

    NASA Astrophysics Data System (ADS)

    Munisami, J.; Kalymnios, D.

    2008-09-01

    Plastic Optical Fibres (POF) were developed almost 3 decades ago. They are mainly used for short haul data communications (up to 1 km with data rates up to 1 Gbps). Over the years, POF has found applications in many other areas including solar energy transport for illumination. In such an application, light is collected from the sun and is directed into a space which needs to be illuminated. The use of fibres and more specifically POF, in daylighting systems, started only a few years ago. Several approaches have been investigated and we have seen the development of a few commercial products. The market however, has not really taken off for these technologies simply because of their enormous price tags. It is important to note that the use of POF in these designs has been limited to the function of POF as the transmission medium only. We propose a novel solar illumination technique using POF as both the light collecting/concentrating mechanism and the transmission medium. By modifying the structure of the fibre, solar light can be directed into the fibre by using an analogous process to fibre side emission but, in the reverse. We shall report on the solar light capturing efficiency of POF as modified by several types of external imperfections introduced onto the fibre. One major advantage of our proposed approach lies in the fact that we aim to eliminate at least one of the two axes of sun tracking that is currently used in existing solar illumination systems.

  16. Plantain fibre bundles isolated from Colombian agro-industrial residues.

    PubMed

    Gañán, Piedad; Zuluaga, Robin; Restrepo, Adriana; Labidi, Jalel; Mondragon, Iñaki

    2008-02-01

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

  17. Fibre-optic two-photon scanning fluorescence microscopy.

    PubMed

    Bird, D; Gu, M

    2002-10-01

    Two geometries of a novel two-photon fluorescence microscope incorporating single-mode fibre optics for the delivery of ultrashort-pulsed illumination to a remote sample are characterized. First, a 785 nm single-mode optical fibre is implemented in a scanning microscope, which demonstrates that an improvement in axial resolution is achieved due to the non-linear response of the fibre to intense ultrashort-pulsed light. Second, a 785 nm single-mode optical fibre coupler is adapted, in which case spectral broadening and blue shifting of the ultrashort-pulsed laser beam caused by the non-linear response of the fibre to ultrashort-pulsed illumination are experimentally characterized. An investigation into the impact of temporal broadening of the ultrashort-pulsed beam on the systems is also considered. The coupling efficiency of both geometries for various illumination wavelengths is also presented. The introduction of the fibre coupler to the system has significant advantages, including an improved optical sectioning effect and a reduction in the number of bulk optical components resulting in a low-cost, compact instrument. Sets of three-dimensional images of fluorescent polymer microspheres and biological material confirm these features. PMID:12366596

  18. A fabry-perot fibre-optic hydrophone for the characterisation of ultrasound fields

    NASA Astrophysics Data System (ADS)

    Morris, Paul

    This thesis documents the development of a novel fibre optic hydrophone, for the characterisation of medical ultrasound transducers and the measurement of ultrasound induced temperature rises. The transduction mechanism of the hydrophone is based on the detection of acoustically and thermally induced changes in the optical thickness of a Fabry-Perot interferometer deposited at the tip of a single mode optical fibre. The interferometer comprises a layer of Parylene-C sandwiched between two thin gold mirrors. The design of the sensor was optimised using a numerical model of the interferometer transfer function. Through the use of vacuum deposition techniques, a fabrication procedure has been developed which enables batch production of the sensors. A self contained sensor interrogation system has also been developed. The system uses a rapidly tuneable laser developed originally for the telecoms industry to interrogate the sensor and make acoustic and thermal measurements. Control of the system is achieved via a PC using software written in Labview 8.0. The acoustic performance of the sensors was characterised using a substitution calibration. The frequency response, directivity and sensitivity of the sensor were all investigated. It was found that whilst the sensor offers a wide bandwidth (>50 MHz), the frequency response is significantly non uniform. Using a finite difference model (AFiDS), it was found that diffraction at the sensor tip is the main cause of resonances in the response. The thermal measurement performance of the sensor was investigated in the presence of an ultra sound field. By comparing the temperature measurements from the hydrophone with those obtained from a thin-film thermocouple, it was found that the fibre-optic hydrophone is immune to viscoelastic heating artefacts. Finally, a novel tracking algorithm was developed, allowing the hydrophone to be used to make simultaneous measurements of both acoustic pressures and ultrasound induced temperature rises.

  19. A new helical crossed-fibre structure of ?-keratin in flight feathers and its biomechanical implications.

    PubMed

    Lingham-Soliar, Theagarten; Murugan, Nelisha

    2013-01-01

    The feather aerofoil is unequalled in nature. It is comprised of a central rachis, serial paired branches or barbs, from which arise further branches, the barbules. Barbs and barbules arise from the significantly thinner lateral walls (the epicortex) of the rachis and barbs respectively, as opposed to the thicker dorsal and ventral walls (the cortex). We hypothesized a microstructural design of the epicortex that would resist the vertical or shearing stresses. The microstructures of the cortex and epicortex of the rachis and barbs were investigated in several bird species by microbe-assisted selective disassembly and conventional methods via scanning electron microscopy. We report, preeminent of the finds, a novel system of crossed fibres (ranging from ?100-800 nm in diameter), oppositely oriented in alternate layers of the epicortex in the rachis and barbs. It represents the first cross-fibre microstructure, not only for the feather but in keratin per se. The cortex of the barbs is comprised of syncitial barbule cells, definitive structural units shown in the rachidial cortex in a related study. The structural connection between the cortex of the rachis and barbs appears uninterrupted. A new model on feather microstructure incorporating the findings here and in the related study is presented. The helical fibre system found in the integument of a diverse range of invertebrates and vertebrates has been implicated in profound functional strategies, perhaps none more so potentially than in the aerofoil microstructure of the feather here, which is central to one of the marvels of nature, bird flight. PMID:23762440

  20. Muscle fibre type distribution of the thoracolumbar and hindlimb regions of horses: relating fibre type and functional role

    PubMed Central

    2014-01-01

    Background Although the majority of equine muscles have a mixed fibre type distribution indicative of diverse functional roles, the predominance of a fibre type can indicate the primary function of a muscle. The deep epaxial musculature has an important role in core spinal stability in humans, reflected as a predominantly muscle fibre type (MFT) I or postural fibre type. The fibre type of the deep epaxial musculature has not been determined in horses. The objective of the study was to determine the MFT distribution in selected muscles of thoracolumbar and hindlimb region of horses. This included deep epaxial and hypaxial muscles that were hypothesised to have a postural stabilising role. A second objective was to examine differences in MFT distribution between horses bred for endurance (Arabian) and sprinting (Quarter horse). Muscle biopsy samples were obtained from selected thoracolumbar and hind limb muscles of 5 Quarter horses, 4 Arabians, and 2 Thoroughbreds. The myosin heavy chain distribution was determined by gel electrophoresis. Mann–Whitney rank test was used to compare the proportional MFT and differences between breeds. Results Mm. sacrocaudalis dorsalis medialis and diaphragm had the highest proportion of MFT-I. The remaining deep epaxial muscles and the hypaxial muscle m. psoas minor had approximately equal MFT I and II proportions. Mm. psoas major, iliocostalis, longissimus dorsi and the hind limb muscles contained mostly MFT-IIX. The fibre type distribution was similar between Arabians and Quarter horses, although Quarter horses had more MFT-IIX fibres in psoas major (P?=?0.02) while Arabians had more MFT-I fibres in m. longissimus dorsi (P?=?0.03). Conclusions The fibre type distribution of the deep epaxial muscles, mm psoas minor and diaphragm varied from approximately equal MFT-I and II proportions to predominantly MFT-I suggesting a postural stabilising role possibly important in core spinal stability. In contrast the fibre type proportions of mm psoas major, iliocostalis, longissimus dorsi and the hind limb muscles were mainly MFT-II suggesting a locomotory role. Knowledge of fibre type distribution in such a clinically important area can direct diagnosis, prevention and treatment of muscular or neuromotor dysfunction. PMID:24468115

  1. EFFETTO DELL'ORIENTAMENTO DELLE FIBRE SULLA RESISTENZA A FATICA DI UNA POLIAMMIDE 6 RINFORZATA CON FIBRE DI VETRO

    Microsoft Academic Search

    A. Bernasconi; P. Davoli; A. Basile; A. Filippi

    Sommario In questo lavoro vengono presentati i risultati dello studio dell'effetto dell'orientamento delle fibre sulla resistenza a fatica di una poliammide 6. sono state eseguite prove di fatica su provini estratti da lastre ottenute per stampaggio ad iniezione. I provini sino stati ritagliati con diversi orientamenti rispetto all'asse della lastra, in modo da ottenere differenti orientamenti delle fibre di rinforzo

  2. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  3. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

    McCool, Rauri; Murphy, Adrian; Wilson, Ryan; Jiang Zhenyu; Price, Mark [School of Mechanical and Aerospace Engineering, Queen's University Belfast, Northern Ireland (United Kingdom)

    2011-05-04

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

  4. CARMENES in SPIE 2014. Building a fibre link for CARMENES

    NASA Astrophysics Data System (ADS)

    Stürmer, J.; Stahl, O.; Schwab, C.; Seifert, W.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners, A.; Caballero, J. A.

    2014-07-01

    Optical fibres have successfully been used to couple high-resolution spectrographs to telescopes for many years. As they allow the instrument to be placed in a stable and isolated location, they decouple the spectrograph from environmental influences. Fibres also provide a substantial increase in stability of the input illumination of the spectrograph, which makes them a key optical element of the two high-resolution spectrographs of CARMENES. The optical properties of appropriate fibres are investigated, especially their scrambling and focal ratio degradation (FRD) behaviour. In the laboratory the output illumination of various fibres is characterized and different methods to increase the scrambling of the fibre link are tested and compared. In particular, a combination of fibres with different core shapes shows a very good scrambling performance. The near-field (NF) shows an extremely low sensitivity to the exact coupling conditions of the fibre. However, small changes in the far-field (FF) can still be seen. Related optical simulations of the stability performance of the two spectrographs are presented. The simulations focus on the influence of the non-perfect illumination stabilization in the far-field of the fibre on the radial velocity stability of the spectrographs. We use ZEMAX models of the spectrographs to simulate how the barycentres of the spots move depending on the FF illumination pattern and therefore how the radial velocity is affected by a variation of the spectrograph illumination. This method allows to establish a quantitative link between the results of the measurements of the optical properties of fibres on the one hand and the radial velocity precision on the other. The results provide a strong indication that 1ms?1 precision can be reached using a circular-octagonal fibre link even without the use of an optical double scrambler, which has successfully been used in other high-resolution spectrographs. Given the typical throughput of an optical double scrambler of about 75% to 85 %, our solution allows for a substantially higher throughput of the system.

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

    NASA Astrophysics Data System (ADS)

    Agarwal, Mangilal; Lvov, Yuri; Varahramyan, Kody

    2006-11-01

    A layer-by-layer (LbL) self-assembly of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) on lignocellulose wood microfibres was used to make conductive fibres and paper. Polycations such as poly(allylamine hydrochloride) (PAH), and poly(ethyleneimine) (PEI) were used in alternate deposition with anionic conductive polythiophene (PEDOT-PSS) to construct the multilayer nanofilms on wood microfibres. Current-voltage characterization was measured on single fibres using a Keithley probe measurement system after deposition of every PEDOT-PSS monolayer to study the electrical properties of the coating. The conductivity of the microfibres increased linearly with increasing number of bilayers of PEDOT-PSS/polycation. The measured conductivities of the coated microfibres ranged from 1 to 10 S cm-1. It was also observed that the conductivity of the fibres (i.e., coating of PEDOT-PSS) depends upon the type of polycations used to alternate with the polythiophene. In this work we have demonstrated successful scale integration from nano to micro and macroscale (nanocoating-microfibres-macropaper) in developing new paper material. The conductive paper that has been produced (and its fabrication method) can be used for the development of smart paper technology on monitoring of electrical, and optical/electrical signals.

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

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

    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 skin (BUS-model) has been used. For depth profiling of endogenous and topically applied compounds, subsequent stripping of corneocyte layers by adhesive tape application was carried out in combination with in situ fibre-probe ATR-measurements. The non-invasive measurement technique was also applied to patients with various skin abnormalities. Owing to the remote sensing capability, the technique presented is promising, since it opens the field for new medical and cosmetic applications, which are otherwise not possible with conventional sampling compartment based ATR-accessories.

  7. Muscle fibre specialization in the vertebrates is achieved primarily through variation in the isoforms of the proteins of

    E-print Network

    Kier, William M.

    Muscle fibre specialization in the vertebrates is achieved primarily through variation myofilaments and sarcomeres of different vertebrate muscle fibre types are relatively invariant (Eisenberg, 1983; Offer, 1987). We have studied the specialized cross-striated muscle fibres that cause

  8. PRAXIS: low thermal emission high efficiency OH suppressed fibre spectrograph

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  9. The Biomechanical Function of Periodontal Ligament Fibres in Orthodontic Tooth Movement

    PubMed Central

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

    2014-01-01

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

  10. Mechanical and thermo-physical characterization of the carbon fibre composite NB31

    NASA Astrophysics Data System (ADS)

    Pintsuk, G.; Compan, J.; Linke, J.; Majerus, P.; Peacock, A.; Pitzer, D.; Rödig, M.

    2007-03-01

    The use of carbon-based materials, i.e. graphite and carbon fibre composites (CFCs), as plasma facing materials in experimental nuclear fusion devices is widely spread. For the strike point area of the ITER divertor, a European candidate material was NB31, a three directional (3D) CFC material consisting of ex-pitch, ex-PAN and needled ex-PAN fibres, which will be replaced in the future by the newly developed material NB41. This composite material is used for the fabrication of divertor components for Wendelstein 7-X. In the frame of an extensive characterization on three different material batches of NB31 called 'pilot', 'serial' and 'additional' productions for W7-X and ITER, thermo-physical measurements and tensile tests were performed. The results were correlated to density and microstructure. The latter varied due to difficulties in the manufacturing process, in particular in the needling process. Therefore the specification of a minimum density and unit cell width (combined thickness of an ex-pitch and ex-PAN layer) is necessary to meet the ITER specifications for tensile strength and for thermal conductivity in the ex-pitch direction.

  11. Tritium depth profiles in graphite and carbon fibre composite material exposed to tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Penzhorn, R.-D.; Bekris, N.; Berndt, U.; Coad, J. P.; Ziegler, H.; Nägele, W.

    2001-02-01

    Tritium inventories in the plasma-facing surface and the bulk of tiles were investigated with a highly sensitive, accurate full-combustion technique and a PIN-diode method. Examined were (i) a tokamak fusion test reactor (TFTR) graphite tile (D-D plasmas), (ii) a JET graphite tile (low-tritium D-T plasmas), and (iii) several JET carbon fibre composite (CFC) divertor tiles as well as a graphite limiter tile (all high-tritium D-T plasmas). Whilst the bulk tritium concentration in graphite tiles appears to remain at very low levels (about 0.3% of the total tritium) the tritium bulk concentrations in CFC divertor tiles can be as high as three times that in the surface layer. The latter is attributed to plasma-induced trapping of tritium between the fibre planes of CFC in the hot divertor zone. In addition to carbon/hydrogen co-deposition, this contribution constitutes another important source of tritium inventory in the torus that so far had not been recognised.

  12. Optical fibre nanotips fabricated by a dynamic chemical etching for sensing applications

    NASA Astrophysics Data System (ADS)

    Barucci, A.; Cosi, F.; Giannetti, A.; Pelli, S.; Griffini, D.; Insinna, M.; Salvadori, S.; Tiribilli, B.; Righini, G. C.

    2015-02-01

    Nanoprobe tips are key components in many applications such as scanning probe microscopes, nanoscale imaging, nanofabrication and sensing. This paper describes a dynamic chemical etching method for the fabrication of optical nanoprobes. The tips are produced by mechanically rotating and dipping a silica optical fibre in a chemical etching solution (aqueous hydrofluoric acid) covered with a protection layer. Using different dynamic regimes of the mechanical movements during the chemical etching process, it is possible to vary the cone angle, the shape, and the roughness of the nanoprobes. It is found that the tip profiles are determined by the nonlinear dynamic evolution of the meniscus of the etchant near the fibre. Computational fluid dynamic simulations have been performed, showing that different flow regimes correspond to different shear forces acting on the forming nanotip, in agreement with experimental results. With this method, a high yield of reproducible nanotips can be obtained, thus overcoming the drawbacks of conventional etching techniques. Typical tip features are short taper length (˜200 ?m), large cone angle (up to 40°), and small probe tip dimension (less than 30 nm).

  13. The LHCb Upgrade Scintillating Fibre Tracker

    E-print Network

    Leverington, Blake D

    2014-01-01

    The Scintillating Fibre (SciFi) Tracker is designed to replace the current downstream tracking detectors in the LHCb Upgrade during 2018 (CERN/LHCC 2014-001; LHCb TDR 15). The operation and the results obtained from the data collected 2011 and 2012 demonstrate that the current detector is robust and functioning very well. However, the limit of O ( 1 fb-1) of data per year cannot be overcome without improving the detector. This will be achieved using 25 ns bunch spacing with the average number of proton-proton interactions per bunch crossing n = 7 : 6. Collecting data at this luminosity will only be possible if the detector is improved by increasing the readout of the front-end electronics to 40MHz and implementing a more flexible software-based triggering system that will increase the data rate as well as the efficiency. The increase in interactions per bunch crossing will result in an increased occupancy in the tracking detectors and will exceed the operational occupancy for the Outer Tracker. Here we presen...

  14. Smart Structures with Fibre-Optic Technologies

    SciTech Connect

    Del Grosso, Andrea [Department of Civil, Environmental and Architectural Engineering, University of Genoa, Via Montallegro 1, 16145 Genova (Italy); Zangani, Donato; Messervey, Thomas [D'Appolonia S.p.A., Via San Nazaro 19, Genova (Italy)

    2008-07-08

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  15. Smart Structures with Fibre-Optic Technologies

    NASA Astrophysics Data System (ADS)

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-01

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  16. Design and performance evaluation of polyvinyl alcohol/polyimide coated optical fibre grating-based humidity sensors

    NASA Astrophysics Data System (ADS)

    Alwis, L.; Sun, T.; Grattan, K. T. V.

    2013-02-01

    Optical fibre grating based sensors make a significant contribution to relative humidity measurement for various applications and a number of different designs and sensor configurations have been produced and discussed in the literature. Recent developments have included using sensitive polymers and indeed other materials that experience a variation of their physical and optical properties as a result of the absorption of moisture and which thus creates a modification of the characteristic spectral features of the gratings used. The strain and the effective refractive index of the gratings are affected by the change induced by the polymer and these effects were calibrated against the relative humidity variations that initially induce variations in the polymer layer. In this work, an evaluation is made of the performance characteristics of two different moisture sensitive polymers, i.e., polyimide and polyvinyl alcohol, as the basis of such sensors, while at the same time using different types of fibre gratings i.e., fibre Bragg gratings and long period gratings. Their performance is discussed in light of the operation of similar types of polymer-coated and other grating based sensors reported in the literature.

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

    SciTech Connect

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

    2013-01-15

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

  18. Understanding and Improving the Elastic Compressive Modulus of Fibre Reinforced Soy-Based Polyurethane Foams

    NASA Astrophysics Data System (ADS)

    Hussain, Sadakat

    Soy-based polyurethane foams (PUFs) were reinforced with fibres of different aspect ratios to improve the compressive modulus. Each of the three fibre types reinforced PUF differently. Shorter micro-crystalline cellulose fibres were found embedded inside the cell struts of PUF and reinforced them. The reinforcement was attributed to be stress transfer from the matrix to the fibre by comparing the experimental results to those predicted by micro-mechanical models for short fibre reinforced composites. The reinforced cell struts increased the overall compressive modulus of the foam. Longer glass fibres (470 microns, length) provided the best reinforcement. These fibres were found to be larger than the cell diameters. The micro-mechanical models could not predict the reinforcement provided by the longer glass fibres. The models predicted negligible reinforcement because the very low modulus PUF should not transfer load to the higher modulus fibres. However, using a finite element model, it was determined that the fibres were providing reinforcement through direct fibre interaction with each other. Intermediate length glass fibres (260 microns, length) were found to poorly reinforce the PUF and should be avoided. These fibres were too short to interact with each other and were on average too large to embed and reinforce cell struts. In order to produce natural fibre reinforced PUFs in the future, a novel device was invented. The purpose of the device is to deliver natural fibres at a constant mass flow rate. The device was found to consistently meter individual loose natural fibre tufts at a mass flow rate of 2 grams per second. However, the device is not robust and requires further development to deliver a fine stream of natural fibre that can mix and interact with the curing polymeric components of PUF. A design plan was proposed to address the remaining issues with the device.

  19. Resorbable continuous-fibre reinforced polymers for osteosynthesis.

    PubMed

    Dauner, M; Planck, H; Caramaro, L; Missirlis, Y; Panagiotopoulos, E

    1998-03-01

    Four institutes from three countries in the European Union have collaborated under the BRITE-EURAM framework programme for the development of processing technologies for resorbable osteosynthesis devices. The devices should be continuous-fibre reinforced, and the technology should offer the possibility of orienting the fibres in the main trajectories. Poly-L-lactide and poly-L-DL-lactides have been synthesized for reinforcement fibres and matrix material, respectively. Melt-spun P-L-LA fibres of a strength of 800 MPa have been embedded in an amorphous P-L-DL-LA 70 : 30 matrix by compression moulding. Ethyleneoxide sterilized samples have been tested in vitro and in vivo. A satisfying bending modulus has been reached (6 GPa). Yet with 50% strength retention after ten weeks, fast degradation occurred that could be related to residual monomers. By this fast degradation 70% resorption after one year could be observed in the non-functional animal studies in rabbits. There was only a mild inflammatory reaction, which confirmed the good biocompatibility of the materials even during the resorption period. Further effort has to concentrate on the reduction of initial monomer content. The great advantage of the processing method to orient fibres in the device will be utilized in prototype samples, e.g. an osteosynthesis plate with fixation holes. PMID:15348907

  20. A novel fibre-optic system for methane detection

    NASA Astrophysics Data System (ADS)

    Wu, Xijun; Wang, Yutian; Chen, Leilei; Huang, Xinyan

    2007-11-01

    A novel fibre-optic methane detection system was proposed, which involved sampled fibre grating and improved differential absorption detection technique. By this method, near-infrared equal-spaced multi absorption line of methane was detected simultaneously, and that gas weak absorption detection theory was developed. Using the comb shaped filter characteristic of sampled fibre grating, R2, R3 and R4 line of molecule absorption spectrum in 2? 3 overtone band around 1.66?m was measured at one time. Two sampled fibre gratings of same type were used to fulfill the task of difference absorption detection. One sampled grating worked as measure grating with its reflection spectrum corresponding to the absorption line. The other grating worked as reference grating with its reflection spectrum deviate from that of measure grating to some extent. Chirped fibre grating with its central wavelength around R3 was adopted as optical band-pass filter. The light power of the three absorption line and the three reference wavelength was detected alternately by PIN PD at the same time. So that difference absorption detection was achieved. The effect of light source instability was avoided by ratio treatment. The validity of the system was verified by experiments.

  1. Interdiffusion in short-fibre reinforced hydroxyapatite ceramics.

    PubMed

    Knepper, M; Milthorpe, B K; Moricca, S

    1998-10-01

    Sintering in air and hot isostatic pressing are production methods regarded as being capable of producing fibre-reinforced hydroxyapatite ceramics for biomedical applications. These composites may have the advantage of improved mechanical properties and be suitable for applications in areas where there are significant levels of load on the material. The use of pure hydroxyapatite is restricted to those free of dynamical load. Obtaining improved mechanical strength is a question of the bond between the matrix phase and the fibre-reinforcement phase. However, a chemical bond between both phases, indicated by large diffusion zones, might lead to the dehydration of the hydroxyapatite leading to undesired tricalcium phosphate in the matrix resulting in a weakening of the mechanical and biological stability of the composites. Composites with three fibre types, alumina, 316L-stainless steel and titanium were prepared and sintered in air or hot isostatically pressed. A reaction zone was noted around the titanium and stainless steel fibres, but not around the alumina fibres. The reaction zone was larger for stainless steel than titanium. Hot isostatic pressing also reduced the reaction zone markedly compared to sintering in air. PMID:15348692

  2. Z-Pinch Experiments with Styrofoam Fibres and Plasmajets

    NASA Astrophysics Data System (ADS)

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

    1994-03-01

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

  3. Coherent reflectometer with a two-fibre scattered-light interferometer

    SciTech Connect

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

    2011-02-28

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

  4. Improvement of the Tm3+ H4 level lifetime in silica optical fibres

    E-print Network

    Paris-Sud XI, Université de

    ; Multiphonon quenching; Alumino-silicates; Silica; Rare- earths; Thulium Introduction Thulium doped fibres have%. This is why the first Thulium Doped Fibre Amplifier (TDFA) was realized in 1995 by Komukai et al. in fluoride

  5. Elastic fibres are broadly distributed in tendon and highly localized around tenocytes

    PubMed Central

    Grant, Tyler M; Thompson, Mark S; Urban, Jill; Yu, Jing

    2013-01-01

    Elastic fibres have the unique ability to withstand large deformations and are found in numerous tissues, but their organization and structure have not been well defined in tendon. The objective of this study was to characterize the organization of elastic fibres in tendon to understand their function. Immunohistochemistry was used to visualize elastic fibres in bovine flexor tendon with fibrillin-1, fibrillin-2 and elastin antibodies. Elastic fibres were broadly distributed throughout tendon, and highly localized longitudinally around groups of cells and transversely between collagen fascicles. The close interaction of elastic fibres and cells suggests that elastic fibres are part of the pericellular matrix and therefore affect the mechanical environment of tenocytes. Fibres present between fascicles are likely part of the endotenon sheath, which enhances sliding between adjacent collagen bundles. These results demonstrate that elastic fibres are highly localized in tendon and may play an important role in cellular function and contribute to the tissue mechanics of the endotenon sheath. PMID:23587025

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  7. Manufacturing Flax Fibre-Reinforced Polypropylene Composites by Hot-Pressing

    NASA Astrophysics Data System (ADS)

    Jolly, Marc; Jayaraman, Krishnan

    The renewable characteristic of natural fibres, such as flax, and the recyclable nature of thermoplastic polymers, such as polypropylene, provide an attractive eco-friendly quality to the resulting composite materials. Common methods for manufacturing natural fibre-reinforced thermoplastic composites, injection moulding and extrusion, tend to degrade the fibres during processing. Development of a simple manufacturing technique for these composites, that minimises fibre degradation, is the main objective of this study. Flax fibres were conditioned, cut into lengths ranging from 1 mm to 30 mm with scissors and a pelletiser, and shaped into randomly oriented mats using a drop feed tower. Polypropylene in sheet form, was added to the fibres to furnish polypropylene/flax/polypropylene sandwiches with a fibre mass fraction of 25%, which were then consolidated by the hot pressing technique. Tensile, flexural and impact properties of these composite sheets were determined as functions of fibre length and processing temperature.

  8. Large-Area Sandwich Veto Detector with WLS Fibre Readout for Hadron Spectroscopy at COMPASS

    E-print Network

    T. Schlüter; W. Dünnweber; K. Dhibar; M. Faessler; R. Geyer; J. -F. Rajotte; Z. Roushan; H. Wöhrmann

    2011-08-22

    A sandwich detector composed of scintillator and steel-covered lead layers was introduced in the fixed-target COMPASS experiment at CERN for vetoing events not completely covered by the two-stage magnetic spectrometer. Wavelength shifting fibres glued into grooves in the scintillator tiles serve for fast read-out. Minimum ionizing particles impinging on the $2 \\textrm{m} \\times 2 \\textrm{m}$ detector outside of a central hole, sparing the spectrometer's entry, are detected with a probability of 98%. The response to charged particles and photons is modeled in detail in Monte Carlo calculations. Figures of merit of the veto trigger in $190 \\textrm{GeV}/c$ $\\pi^- + p$ (or nucleus) experiments are an enrichment of exclusive events in the recorded data by a factor of 3.5 and a false-veto probability of 1%.

  9. Optimization of microwire/glass-fibre reinforced polymer composites for wind turbine application

    NASA Astrophysics Data System (ADS)

    Qin, F. X.; Peng, H. X.; Chen, Z.; Wang, H.; Zhang, J. W.; Hilton, G.

    2013-11-01

    We here report a comprehensive study of glass-fibre reinforced polymers (GFRP) incorporating ferromagnetic microwires for microwave absorption applications. With wire addition, a remarkable dependence of microwave absorption performance appears on the local properties of wires such as wire geometry and the mesostructure such as inter-wire spacing, as well as the embedded depth of the wires layer. The impact testing further demonstrates that the metallic microwires can to some extent improve the impact performance. Based on both the absorption and impact behavior, we propose an optimized design of the microwire/GFRP composites to achieve simultaneous best possible absorption and impact performance for multifunctional applications in aeronautical structures and wind turbines.

  10. In vitro study of fracture strength and marginal adaptation of polyethylene-fibre-reinforced-composite versus glass-fibre-reinforced-composite fixed partial dentures.

    PubMed

    Kolbeck, C; Rosentritt, M; Behr, M; Lang, R; Handel, G

    2002-07-01

    This in vitro study was carried out in order to estimate the clinical usability of adhesively luted three-unit posterior fixed partial dentures (FPD) made of a polyethylene-fibre-reinforced-composite system (PFRC) in comparison with a glass-fibre-reinforced-composite system (GFRC). Therefore the fracture strength and marginal adaptation were examined. A total of 16 FPDs of each material combination were manufactured and adhesively luted to human molars. Before and after an artificial ageing process by thermal cycling and mechanical loading (TCML) the quality of the marginal adaptation was examined by evaluating epoxy replicas in a scanning electron microscope (SEM). After TCML the fracture strength of eight FPDs of each series was tested by mechanical loading them to failure. With the remaining eight FPDs the quality of deeper layers of the luting was examined with a dye penetration technique. The calculated median fracture strength values (25/75% percentiles) were 830 N (643/982) for the PFRC and 884 N (684/1,113) for the GFRC. The SEM analysis showed at least 80% of perfect marginal areas for both material combinations in dentine as well as in enamel before and after TCML. Looking at the cement-tooth interfaces the dye penetration technique showed statistically significant better results for the enamel finishing lines than for those in dentine. With finishing lines in dentine the two material combinations showed statistically significant differences for this interface. Fracture force results as well as marginal quality encourage further clinical investigations on both systems although the GFRC performed slightly better than the PFRC. PMID:12153457

  11. Changes in rodent muscle fibre types during post-natal growth, undernutrition and exercise.

    PubMed Central

    Goldspink, G; Ward, P S

    1979-01-01

    1. Using histochemical staining methods for myosin ATPase oxidative and glycolytic enzymes, three major types of muscle fibre could be identified in the skeletal muscle of hamsters and mice. 2. Muscle fibre counts showed that the proportions of the different fibres were not entirely stable with age. In the hamster biceps brachii which is predominantly composed of ATPase-high fibres there was a decrease in the number of ATPase-low fibres. In the soleus muscle which is predominantly composed of ATPase-low fibres there was a decrease in ATPase-high fibres with age. 3. Although there was a change in the proportions of fibre types there was no change in the total number of fibres within the muscles with age. It is suggested that some reinnervation may take place during growth and that this is why the less dedominant fibre type decreases. 4. The response of the different fibre types to partial starvation was studied. The ATPase-high fibres showed the greatest decrease in size. Of these, the ATPase-high glycolytic type responded more than the ATPase-high oxidative type. The effects of the under-nutrition on the different fibre types were found to be completely reversible. Starvation did not affect the total number of fibres or the numbers of any fibre type. 5. The response of the different types to high intensity exercise (weight lifting) was studied. This type of exercise resulted in hypertrophy of all three major fibre types. However, the extent of the response varied according to the fibre type and the exact nature of the exercise. In most cases the ATPase-high fibres underwent hypertrophy more readily than the ATPase-low fibres. Where distinction was made between the two types of ATPase-high fibres, the ATPase-high glycolytic were found to hypertrophy more than the ATPase-high oxidative fibres. The effects of post exercise recovery (return to relative inactivity) were also studied and the changes in size of the fibres were found to be completely reversible. Images Plate 2 Plate 1 PMID:160929

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

    PubMed

    Shams, H; Daffonchio, L; Scheid, P

    1996-03-01

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

  13. Influence of Oven-Drying Temperature on Physicochemical and Functional Properties of Date Fibre Concentrates

    Microsoft Academic Search

    Chema Borchani; Souhail Besbes; Manel Masmoudi; Mohamed Ali Bouaziz; Christophe Blecker; Hamadi Attia

    Agri-food by-products rich in dietary fibres may be used as feeds and health foods. Owing to its high fibre content, date\\u000a flesh could be useful in human nutrition. It is interesting to study the influence of oven-drying temperatures of date fibre\\u000a concentrates (DFC) on their physicochemical and functional properties for possible use as a potential fibre source in the\\u000a enrichment

  14. Airborne fibre levels associated with the use of MMMF brazing mats during welding operations.

    PubMed

    Waterman, L S; Purnell, C J; Anderson, P W

    1990-02-01

    In 1985 the Health and Safety Executive set a gravimetric Control Limit for airborne Man-Made Mineral Fibre and in 1987 a respirable fibre number Recommended Limit for Superfine MMMF. A limited investigation was carried out of the use of glass and ceramic fibre products used as protection against welding 'batter' and oxyacetylene welding flame. Airborne fibre levels are compared with the Occupational Exposure Limits. PMID:2158262

  15. Fracture toughness and impact behaviour of glass-fibre-reinforced polyamide 6,6 injection mouldings

    Microsoft Academic Search

    M. Akay; D. F. O'Regan; R. S. Bailey

    1995-01-01

    The fracture toughness of injection-moulded long-glass-fibre-reinforced polyamide 6,6 (average fibre aspect ratio in mouldings, l\\/d ? 55) with fibre weight contents of 50 and 60 % was studied and compared with that of short-glass-fibre-reinforced polyamide 6,6 (l\\/d ? 20). Toughness was measured by using Mode I compact-tension specimens cut from the mouldings and also by means of instrumented drop-weight impact

  16. Comparative characterization of dietary fibre enriched frozen\\/thawed mashed potatoes

    Microsoft Academic Search

    Maria Dolores Alvarez; Cristina Fernandez; María Dolores Olivares; Wenceslao Canet

    2011-01-01

    The potential use of commercial fibres (pea fibre (PF), inulin (I) and their blends (PFI)), as fibre-enriching agents in frozen\\/thawed mashed potatoes (F\\/TM potatoes), was reported. PF and I supplementations conferred hardness and softness to the product respectively. Differences were attributed to the relationship of the fibre with the potato starch matrix. The association of PF at low concentration (<

  17. A study of chemoreceptor and baroreceptor A and C-fibres in the cat carotid nerve

    PubMed Central

    Fidone, S. J.; Sato, A.

    1969-01-01

    1. 149 A-fibres and 52 C-fibres from the cat carotid nerve were studied in vivo with single-unit recording techniques. These units subserved chemoreceptor and baroreceptor modalities. In addition, half of the C-fibres were determined to be efferent in origin. The estimated fibre diameter spectrum for chemoreceptor and baroreceptor A-fibres is described. 2. The discharge pattern of chemoreceptor A and C-fibres was characteristically irregular both at rest and during activation. However, about 5% of the chemoreceptor A-fibre population exhibited a very regular discharge pattern, even at low rates of firing. 3. In comparing A and C-fibres, it was found that chemoreceptor and baroreceptor A-fibres had lower thresholds, shorter response latencies, more rapid acceleration of discharge and higher discharge frequencies than their C-fibre counterparts. 4. During strong chemoreceptor or baroreceptor stimulation, interaction of the `spontaneous' whole nerve activity with the evoked A and C-fibre compound action potentials provided a method of estimating the relative proportions of chemoreceptors and baroreceptors in the A and C-fibre populations of the carotid nerve. The A-fibre population was found to be comprised of approximately 2/3 chemoreceptors, 1/3 baroreceptors. The reverse was true for the C-fibre population, i.e. 2/3 baroreceptors, 1/3 chemoreceptors. 5. A stepwise C-fibre response is described which may arise from the several C-fibres within a single Schwann cell. PMID:5361289

  18. Could biopolymers reinforced by randomly scattered flax fibre be used in structural applications?

    Microsoft Academic Search

    Edwin Bodros; Isabelle Pillin; Nicolas Montrelay; Christophe Baley

    2007-01-01

    Thermoplastics reinforced by natural fibres are mainly used for fitting-up products in the automotive industry. The aim of this work is to study the tensile properties of natural fibre-biopolymer composites in order to determine whether or not, biocomposites may replace glass fibre reinforced unsaturated polyester resins. The materials used are flax fibre, polylactic acid (PLA), l-polylactide acid (PLLA), poly(3-hydroxylbutyrate) (PHB),

  19. Possibilities for improving the mechanical properties of jute\\/epoxy composites by alkali treatment of fibres

    Microsoft Academic Search

    Jochen Gassan; Andrzej K. Bledzki

    1999-01-01

    The aim of this paper is the improvement of the mechanical properties of natural-fibre-reinforced thermosets, as a result of optimization of the properties of tossa jute fibres by the use of an NaOH treatment process. By this process shrinkage of the fibres during treatment had significant effects on fibre structure and, as a result, on the mechanical properties of the

  20. Analogue summation of electrical spike trains in semiconductor nerve fibres

    NASA Astrophysics Data System (ADS)

    Samardak, Alexander; Taylor, Stephen; Nogaret, Alain; Hollier, Garry; Austin, Jim; Farrer, Ian; Ritchie, Dave

    2008-04-01

    We fabricate and investigate electrical pulse propagation in modulation-doped semiconductor nerve fibres made of sub-micron pn wires. We report the analogue summation of electrical impulses at the junction of three or more fibres. These wires model the longitudinal conductivities of potassium and sodium ions inside and outside a nerve capillary as well as the transverse capacitance of the nerve membrane and the non-linear conductance of its ion channels. We demonstrate the summation and annihilation of electrical impulses at both 300 and 77 K, which forms the basis for making spike-timing neural networks. A comparison of experimental and theoretical parameters of pulse propagation at these two temperatures is presented. The successful implementation of artificial nerve fibres promises parallel computation devices and spiking neural networks.

  1. Actuation of shape-memory colloidal fibres of Janus ellipsoids.

    PubMed

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

    2015-01-01

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

  2. Stimulated Raman scattering microscopy with a robust fibre laser source

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  3. Ultrasonic monitoring of asymmetric carbon fibre reinforced aluminum laminates

    NASA Astrophysics Data System (ADS)

    Zhao, Junqing; Yang, Fan; Wang, Rongguo

    2013-08-01

    Asymmetric carbon fibre reinforced aluminum alloy laminates was manufactured for the purpose with repeat tensile test, which will be applied in composite pressure vessel. Ultrasonic C scan and A scan approach are used to evaluate the damage of the asymmetric CFRP-Al (carbon fibre reinforced aluminum alloy) laminates. Nondestructive detection is carried out for the CFRP-Al laminates before and after tensile test. Comparison results and pulse echo analysis show that when subjected to repeat tensile test with 70% elastic limit strain load of the CFRP laminates, the interface debonding between CFRP and Al will not occur but the delamination within CFRP laminates becomes the main damage of the asymmetric CFRP-Al laminates. This investigation indicated that combined ultrasonic C scan and A scan is available for damage evaluation of fibre metal laminates.

  4. Biodegradable fibre scaffolds incorporating water-soluble drugs and proteins.

    PubMed

    Ma, J; Meng, J; Simonet, M; Stingelin, N; Peijs, T; Sukhorukov, G B

    2015-07-01

    A new type of biodegradable drug-loaded fibre scaffold has been successfully produced for the benefit of water-soluble drugs and proteins. Model drug loaded calcium carbonate (CaCO3) microparticles incorporated into poly(lactic acid-co-glycolic acid) (PLGA) fibres were manufactured by co-precipitation of CaCO3 and the drug molecules, followed by electrospinning of a suspension of such drug-loaded microparticles in a PLGA solution. Rhodamine 6G and bovine serum albumin were used as model drugs for our release study, representing small bioactive molecules and protein, respectively. A bead and string structure of fibres was achieved. The drug release was investigated with different drug loadings and in different pH release mediums. Results showed that a slow and sustained drug release was achieved in 40 days and the CaCO3 microparticles used as the second barrier restrained the initial burst release. PMID:26155976

  5. Biogenic silica fibre promotes carcinogenesis in mouse skin.

    PubMed

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

    1984-10-15

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

  6. Agricultural fibres for pulp and paper manufacture in developed countries

    SciTech Connect

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

    1995-11-01

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

  7. Impact of corticofugal fibre involvement in subcortical stroke

    PubMed Central

    Phan, Thanh G; van der Voort, Sanne; Chen, Jian; Beare, Richard; Ma, Henry; Clissold, Benjamin; Ly, John; Foster, Emma; Thong, Eleanor; Srikanth, Velandai

    2013-01-01

    Objective To correlate motor deficit with involvement of corticofugal fibres in patients with subcortical stroke. The descending motor corticofugal fibres originate from the primary motor cortex (M1), dorsal and ventral premotor area (PMdv) and supplementary motor area (SMA). Design Retrospective study. Setting Single tertiary teaching hospital. Participants 57 patients (57% men) with subcortical infarcts on MRI (2009–2011) were included. The mean age was 64.3±14.4?years. Interventions None. Primary and secondary outcome measures National Institute of Health Stroke Scale subscores for arm and leg motor deficit at 90?days. Results An area under the receiver operating characteristics curve (AUC) for the volume of overlap with infarct (and M1/PMdv/SMA fibres) and motor outcome was calculated. The AUC for the association with arm motor deficit from M1 fibres involvement was 0.80 (95% CI 0.66 to 0.94), PMdv was 0.76 (95% CI 0.61 to 0.91) and SMA was 0.73 (95% CI 0.58 to 0.88). The AUC for leg motor deficit from M1 fibres involvement was 0.69 (95% CI 0.52 to 0.85), PMdv was 0.67 (95% CI 0.50 to 0.85), SMA was 0.66 (95% CI 0.48 to 0.84). Conclusions Following subcortical stroke, the correlations between involvement of the corticofugal fibres for upper and lower limbs motor deficit were variable. A poor motor outcome was not universal following subcortical stroke. PMID:24068765

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

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

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

  9. LASERS BRILLOUIN `A FIBRE MICROSTRUCTUR EE EN VERRE DE CHALCOG ENURE `A TR `ES FAIBLES SEUILS

    E-print Network

    Boyer, Edmond

    LASERS BRILLOUIN `A FIBRE MICROSTRUCTUR ´EE EN VERRE DE CHALCOG ´ENURE `A TR `ES FAIBLES SEUILS Sciences chimiques de Rennes, Equipe Verres et C´eramiques heytow@enssat.fr R´ESUM ´E L'utilisation de fibres microstructur´ees en verre de chalcog´enure ouvre la voie `a la r´ealisation des lasers `a fibre

  10. Phase-sensitive polarimetric sensing in the evanescent field of single-mode fibres

    Microsoft Academic Search

    H. Lehmann; M. E. Lippitsch; W. Ecke; W. Haubenreisser; R. Willsch; D. Raabe

    1995-01-01

    A new approach for using optical fibres as sensing elements by exploiting the evanescent field of the guided wave is proposed. The optical principle is based on the differential phase modulation between the two orthogonal polarization modes of a single-mode fibre via evanescent field interaction with sensitive thin films deposited on the side-polished fibre. A new theoretical method to calculate

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

    Microsoft Academic Search

    Jean-Baptiste Donnet; Tong Kuan Wang

    1997-01-01

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

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

    Microsoft Academic Search

    A. R. Bunsell

    1975-01-01

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

  13. Preparation of Conducting Fibres from Cellulose and Silk by Polypyrrole Coating

    Microsoft Academic Search

    S. Hossein Hosseini; Ali Pairovi

    cellulose fibre (e.g., cotton) and a protein fibre (e.g., silk), after under going pre- treatment and activating stages, were coated by conductive polymers such as pyr- role by two methods: Vapour and liquid phases. The value of penetration of con- ductive polymer into fibres by scanning electron microscope (SEM) was determined. Then assessments were made on physical properties and optimization

  14. Guidance properties of few-mode large-mode-area microstructured fibres

    SciTech Connect

    Agruzov, P M; Il'ichev, I V; Kozlov, A S; Shamray, A V [Ioffe Physical Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation); Dukel'skii, K V; Shevandin, V S [Research Institute of Optical Materials Technology, All-Russian Scientific Centre 'S.I. Vavilov State Optical Institute', St Petersburg (Russian Federation)

    2010-05-26

    This paper presents detailed experimental and theoretical studies of the mode composition of light propagating along microstructured fibres having a solid core formed by 7 or 19 missing holes and differing in geometric parameters. The results are used to derive conditions for single fundamental mode operation of the fibres. (fibres)

  15. An assessment of alternative cotton fibre quality attributes and their relationship with yarn strength

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowing the yarn strength performance potential of cotton fibre is advantageous to spinners during mill preparation, and to researchers developing new genotypes and management strategies to produce better fibre. Standard High Volume Instrument (HVI) fibre quality attributes include micronaire, a co...

  16. Change in the Properties of High-Strength Fibres under the Effect of Soil Microorganisms

    Microsoft Academic Search

    E. V. Byzova; K. E. Perepelkin; G. P. Meshcheryakova

    2003-01-01

    The resistance of high-strength para-aramid and polyethylene terephthalate fibres to soil microorganisms was investigated. It was found that the curve of the fibre strength versus the duration of exposure to soil microflora is monotonically diminishing. The elongation at break of the fibres also changes monotonically, with the exception of Kevlar. The change in the strength and elongation at break as

  17. Pulse transition to similaritons in normally dispersive fibre K Hammani1*

    E-print Network

    Paris-Sud XI, Université de

    propagation that can take place in our Raman fibre amplifier. We then describe an experiment conducted fibre medium [22]. The experimental results recorded in the Raman amplifier confiPulse transition to similaritons in normally dispersive fibre amplifiers K Hammani1* , S Boscolo2

  18. Phenotypic and genetic description of fibre traits in South American domestic camelids (llamas and alpacas)

    Microsoft Academic Search

    E. N. Frank; M. V. H. Hick; C. D. Gauna; H. E. Lamas; C. Renieri; M. Antonini

    2006-01-01

    Even though llamas and alpacas are multipurpose animals, fibre production remains the main trait from an international market point of view. The objectives of this review are to describe the phenotypic traits that determine fibre quality, and to identify the genetic mechanisms governing them. The finer and lesser prickling effect the fibre has, the higher its value is. All these

  19. Functional and structural effects of an Ala to Val mutation in the adenovirus serotype 2 fibre.

    PubMed

    Caillet-Boudin, M L; Lemay, P; Boulanger, P

    1991-02-01

    H2ts125 is a fibre-defective, temperature-sensitive mutant of adenovirus serotype 2. H2ts125 fibre is unstable at the non-permissive temperature (ts phenotype), and does not migrate in the same way as the wild-type fibre in an SDS/polyacrylamide gel (elm phenotype). Sequence analysis has shown that H2ts125 carries two mutations on the fibre gene: Leu105 to Phe, and Ala434 to Val. Analysis of the structural modifications occurring in H2ts125 fibre was performed using peptide finger-printing and antipeptide sera as immunological probes. We found that all the detectable structural alterations in the mutant fibre were due to the substitution on codon 434. In addition, the ts phenotype was rescued by a wild-type DNA fragment containing the 3' moiety of the fibre gene and overlapping the 434th codon. Morphological analysis of fibre molecules observed under the electron microscope showed minor but statistically significant differences in the fibre length between mutant and wild-type. The mutant fibre was found to be slightly longer (308.8 +/- 1.9 A) than the wild-type fibre (300.1 +/- 2.1 A). Thus both ts and elm phenotypes were carried by the same Ala434 to Val mutation which probably resulted from a change in the three-dimensional structure of the fibre protein, and not from some proteolytic cleavage. PMID:1994035

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

    Microsoft Academic Search

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

    1998-01-01

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