Gene Transduction and Cell Entry Pathway of Fiber-Modified Adenovirus Type 5 Vectors Carrying Novel Endocytic Peptide Ligands Selected on Human Tracheal Glandular Cells

PubMed Central

Gaden, Florence; Franqueville, Laure; Magnusson, Maria K.; Hong, Saw See; Merten, Marc D.; Lindholm, Leif; Boulanger, Pierre

2004-01-01

Monolayers of cystic fibrosis transmembrane conductance regulator (CFTR)-deficient human tracheal glandular cells (CF-KM4) were subjected to phage biopanning, and cell-internalized phages were isolated and sequenced, in order to identify CF-KM4-specific peptide ligands that would confer upon adenovirus type 5 (Ad5) vector a novel cell target specificity and/or higher efficiency of gene delivery into airway cells of patients with cystic fibrosis (CF). Three different ligands, corresponding to prototypes of the most represented families of phagotopes recovered from intracellular phages, were designed and individually inserted into Ad5-green fluorescent protein (GFP) (AdGFP) vectors at the extremities of short fiber shafts (seven repeats [R7]) terminated by scissile knobs. Only one vector, carrying the decapeptide GHPRQMSHVY (abbreviated as QM10), showed an enhanced gene transduction of CF-KM4 cells compared to control nonliganded vector with fibers of the same length (AdGFP-R7-knob). The enhancement in gene transfer efficiency was not specific to CF-KM4 cells but was observed in other mammalian cell lines tested. The QM10-liganded vector was referred to as AdGFP-QM10-knob in its knobbed version and as AdGFP-QM10 in its proteolytically deknobbed version. AdGFP-QM10 was found to transduce cells with a higher efficiency than its knob-bearing version, AdGFP-QM10-knob. Consistent with this, competition experiments indicated that the presence of knob domains was not an absolute requirement for cell attachment of the QM10-liganded vector and that the knobless AdGFP-QM10 used alternative cell-binding domains on its capsid, including penton base capsomer, via a site(s) different from its RGD motifs. The QM10-mediated effect on gene transduction seemed to take place at the step of endocytosis in both quantitative and qualitative manners. Virions of AdGFP-QM10 were endocytosed in higher numbers than virions of the control vector and were directed to a compartment different from the early endosomes targeted by members of species C Ad. AdGFP-QM10 was found to accumulate in late endosomal and low-pH compartments, suggesting that QM10 acted as an endocytic ligand of the lysosomal pathway. These results validated the concept of detargeting and retargeting Ad vectors via our deknobbing system and redirecting Ad vectors to an alternative endocytic pathway via a peptide ligand inserted in the fiber shaft domain. PMID:15194799

A continuum mechanics-based musculo-mechanical model for esophageal transport

NASA Astrophysics Data System (ADS)

Kou, Wenjun; Griffith, Boyce E.; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

2017-11-01

In this work, we extend our previous esophageal transport model using an immersed boundary (IB) method with discrete fiber-based structural model, to one using a continuum mechanics-based model that is approximated based on finite elements (IB-FE). To deal with the leakage of flow when the Lagrangian mesh becomes coarser than the fluid mesh, we employ adaptive interaction quadrature points to deal with Lagrangian-Eulerian interaction equations based on a previous work (Griffith and Luo [1]). In particular, we introduce a new anisotropic adaptive interaction quadrature rule. The new rule permits us to vary the interaction quadrature points not only at each time-step and element but also at different orientations per element. This helps to avoid the leakage issue without sacrificing the computational efficiency and accuracy in dealing with the interaction equations. For the material model, we extend our previous fiber-based model to a continuum-based model. We present formulations for general fiber-reinforced material models in the IB-FE framework. The new material model can handle non-linear elasticity and fiber-matrix interactions, and thus permits us to consider more realistic material behavior of biological tissues. To validate our method, we first study a case in which a three-dimensional short tube is dilated. Results on the pressure-displacement relationship and the stress distribution matches very well with those obtained from the implicit FE method. We remark that in our IB-FE case, the three-dimensional tube undergoes a very large deformation and the Lagrangian mesh-size becomes about 6 times of Eulerian mesh-size in the circumferential orientation. To validate the performance of the method in handling fiber-matrix material models, we perform a second study on dilating a long fiber-reinforced tube. Errors are small when we compare numerical solutions with analytical solutions. The technique is then applied to the problem of esophageal transport. We use two fiber-reinforced models for the esophageal tissue: a bi-linear model and an exponential model. We present three cases on esophageal transport that differ in the material model and the muscle fiber architecture. The overall transport features are consistent with those observed from the previous model. We remark that the continuum-based model can handle more realistic and complicated material behavior. This is demonstrated in our third case where a spatially varying fiber architecture is included based on experimental study. We find that this unique muscle fiber architecture could generate a so-called pressure transition zone, which is a luminal pressure pattern that is of clinical interest. This suggests an important role of muscle fiber architecture in esophageal transport.

Phylogenetic evidence for intratypic recombinant events in a novel human adenovirus C that causes severe acute respiratory infection in children.

PubMed

Wang, Yanqun; Li, Yamin; Lu, Roujian; Zhao, Yanjie; Xie, Zhengde; Shen, Jun; Tan, Wenjie

2016-03-10

Human adenoviruses (HAdVs) are prevalent in hospitalized children with severe acute respiratory infection (SARI). Here, we report a unique recombinant HAdV strain (CBJ113) isolated from a HAdV-positive child with SARI. The whole-genome sequence was determined using Sanger sequencing and high-throughput sequencing. A phylogenetic analysis of the complete genome indicated that the CBJ113 strain shares a common origin with HAdV-C2, HAdV-C6, HAdV-C1, HAdV-C5, and HAdV-C57 and formed a novel subclade on the same branch as other HAdV-C subtypes. BootScan and single nucleotide polymorphism analyses showed that the CBJ113 genome has an intra-subtype recombinant structure and comprises gene regions mainly originating from two circulating viral strains: HAdV-1 and HAdV-2. The parental penton base, pVI, and DBP genes of the recombinant strain clustered with the HAdV-1 prototype strain, and the E1B, hexon, fiber, and 100 K genes of the recombinant clustered within the HAdV-2 subtype, meanwhile the E4orf1 and DNA polymerase genes of the recombinant shared the greatest similarity with those of HAdV-5 and HAdV-6, respectively. All of these findings provide insight into our understanding of the dynamics of the complexity of the HAdV-C epidemic. More extensive studies should address the pathogenicity and clinical characteristics of the novel recombinant.

Phylogenetic evidence for intratypic recombinant events in a novel human adenovirus C that causes severe acute respiratory infection in children

PubMed Central

Wang, Yanqun; Li, Yamin; Lu, Roujian; Zhao, Yanjie; Xie, Zhengde; Shen, Jun; Tan, Wenjie

2016-01-01

Human adenoviruses (HAdVs) are prevalent in hospitalized children with severe acute respiratory infection (SARI). Here, we report a unique recombinant HAdV strain (CBJ113) isolated from a HAdV-positive child with SARI. The whole-genome sequence was determined using Sanger sequencing and high-throughput sequencing. A phylogenetic analysis of the complete genome indicated that the CBJ113 strain shares a common origin with HAdV-C2, HAdV-C6, HAdV-C1, HAdV-C5, and HAdV-C57 and formed a novel subclade on the same branch as other HAdV-C subtypes. BootScan and single nucleotide polymorphism analyses showed that the CBJ113 genome has an intra-subtype recombinant structure and comprises gene regions mainly originating from two circulating viral strains: HAdV-1 and HAdV-2. The parental penton base, pVI, and DBP genes of the recombinant strain clustered with the HAdV-1 prototype strain, and the E1B, hexon, fiber, and 100 K genes of the recombinant clustered within the HAdV-2 subtype, meanwhile the E4orf1 and DNA polymerase genes of the recombinant shared the greatest similarity with those of HAdV-5 and HAdV-6, respectively. All of these findings provide insight into our understanding of the dynamics of the complexity of the HAdV-C epidemic. More extensive studies should address the pathogenicity and clinical characteristics of the novel recombinant. PMID:26960434

Hollow Core Optical Fiber Gas Lasers: Toward Novel and Practical Systems in Fused Silica

DTIC Science & Technology

2017-05-18

Hollow core Optically pumped Fiber Gas LASer’s (HOFGLAS’s) based on population inversion combine advantages of fiber lasers such as long interaction...polarization dependent fiber properties. Preliminary experiments were performed toward simultaneous lasing in the visible and near infrared; lasing in...words) Hollow core Optically pumped Fiber Gas LASer’s (HOFGLAS’s) based on population inversion combine advantages of fiber lasers such as long

Probe And Enhancement Of SBS Based Phonons In Infrared Fibers Using Waveguide Coupled External Radiation

NASA Astrophysics Data System (ADS)

Yu, Chung; Chong, Yat C.; Fong, Chee K.

1989-06-01

Interaction of GHz and MHz radiation with CO2 laser propagation in a silver halide fiber using sBs based phonon coupling is furthet investigated. The external signal serves to both probe and enhance laser generated sBs phonons in the fiber. Efficient coupling of microwave radiation into the fiber is accomplished by placing the fiber in a hollow metallic waveguide, designed and constructed to transmit the dominant mode in the 0.9-2.0 GHz band. MHz radiation is conveniently coupled into the fiber using the guided microwave radiation as carrier. Phonon emissions from the fiber under CO2 laser pumping are first established on a spectrum analyzer; low frequency generators ale then tuned to match these frequencies and their maximum interaction recorded. Such interactions are systematically studied by monitoring the amplitude and waveform of the reflected and transmitted laser pulse at various power levels and frequencies of the externally coupled radiation. A plot of reflected laser power versus incident laser power reveals a distinct sBs generated phonon threshold. Variouslaunch directions of the GHz and MHz radiation with respect to the direction of laser propagation are realized to verify theory governing sBs interactions. The MHz radiation and its associated phonons in the fiber are convenient tools for probing sBs related phenomenon in infrared fibers.

Studies in Aromatic and Amine Nitration.

DTIC Science & Technology

1980-05-20

of Commerce, May 1978. 4. J. Hoggett , R. Moodie, F. Penton, and K. Schofield, Nitration and Aromatic Reactivity (Cambridge University Press, 1971). 5...Moodie, K. Schofield, and G. Tobin, J. Chem. Soc., Chem. Comm., 180 (1978); (b) J. Hoggett , R. Moodie, and K. Schofield, Chem. Comm. 605 (1969). 10. (a) S...W. Benson, Thermochemical Kinetics (John Wiley and Sons, Inc., New York, 1968); (b) G. Charlot, D. Bezier, and J. Courtot, Selected Constants--Oxydo

Reactivity of Metal Nitrates.

DTIC Science & Technology

1982-07-20

02NOCuOH Any mechanism suggested for the nitration of aromatic systems by titanium(IV) nitrate must take into account the observed similarity, in...occurs. -26- References 1. For recent reviews see (a) R. B. Moodie and K. Schofield, Accounts Chem. Res., 1976, 9, 287; (b) G. A. Olah and S. J. Kuhn...Ithaca, N.Y., 1969, Chapter VI; L. M. Stock, Prog. Phys. Org. Chem., 1976, 12, 21; J. G. Hoggett , R. B. Moodie, J. R. Penton, and K. Schofield

The prospects for composites based on boron fibers

NASA Technical Reports Server (NTRS)

Naslain, R.

1978-01-01

The fabrication of boron filaments and the production of composite materials consisting of boron filaments and organic or metallic matrices are discussed. Problem involving the use of tungsten substrates in the filament fabrication process, the protection of boron fibers with diffusion barrier cladings, and the application of alloy additives in the matrix to lessen the effects of diffusion are considered. Data on the kinetics of the boron fiber/matrix interaction at high temperatures, and the influence of the fiber/matrix interaction on the mechanical properties of the composite are presented.

Self-Assembly of Molecular Threads into Reversible Gels

NASA Astrophysics Data System (ADS)

Sayar, Mehmet; Stupp, Samuel I.

2001-03-01

Reversible gels formed by low concentrations of molecular gelators that self-assemble into fibers with molecular width and extremely long length have been studied via Monte Carlo simulations. The gelators of interest have two kinds of interactions, one governs self-assembly into fibers and the other provides inter-fiber connectivity to drive the formation of a network. The off-lattice Monte Carlo simulation presented here is based on a point particle representation of gelators. In this model each particle can form only two strong bonds, that enable linear fiber formation, but a variable number of weak bonds which provide inter-fiber connectivity. The gel formation has been studied as a function of concentration of monomers, the strength of interactions, number of bonding sites per particle for weak interactions, and the stiffness of the fibers. The simulation results are compared with two experimental systems synthesized in our group in order to understand gelation mechanisms.

Wavelength-tunable, passively mode-locked fiber laser based on graphene and chirped fiber Bragg grating.

PubMed

He, Xiaoying; Liu, Zhi-bo; Wang, D N

2012-06-15

We demonstrate a wavelength-tunable, passively mode-locked erbium-doped fiber laser based on graphene and chirped fiber Bragg grating. The saturable absorber used to enable passive mode-locking in the fiber laser is a section of microfiber covered by graphene film, which allows light-graphene interaction via the evanescent field of the microfiber. The wavelength of the laser can be continuously tuned by adjusting the chirped fiber Bragg grating, while maintaining mode-locking stability. Such a system has high potential in tuning the mode-locked laser pulses across a wide wavelength range.

Mode conversion in a tapered fiber via a whispering gallery mode resonator and its application as add/drop filter.

PubMed

Huang, Ligang; Wang, Jie; Peng, Weihua; Zhang, Wending; Bo, Fang; Yu, Xuanyi; Gao, Feng; Chang, Pengfa; Song, Xiaobo; Zhang, Guoquan; Xu, Jingjun

2016-02-01

Based on the conversion between the fundamental mode (LP01) and the higher-order mode (LP11) in a tapered fiber via a whispering gallery mode resonator, an add/drop filter was proposed and demonstrated experimentally, in which the resonator only interacted with one tapered fiber, rather than two tapered fibers as in conventional configurations. The filter gains advantages of easy alignment and low scattering loss over the other filters based on tapered fiber and resonator, and will be useful in application.

300-MHz-repetition-rate, all-fiber, femtosecond laser mode-locked by planar lightwave circuit-based saturable absorber.

PubMed

Kim, Chur; Kim, Dohyun; Cheong, YeonJoon; Kwon, Dohyeon; Choi, Sun Young; Jeong, Hwanseong; Cha, Sang Jun; Lee, Jeong-Woo; Yeom, Dong-Il; Rotermund, Fabian; Kim, Jungwon

2015-10-05

We show the implementation of fiber-pigtailed, evanescent-field-interacting, single-walled carbon nanotube (CNT)-based saturable absorbers (SAs) using standard planar lightwave circuit (PLC) fabrication processes. The implemented PLC-CNT-SA device is employed to realize self-starting, high-repetition-rate, all-fiber ring oscillators at telecommunication wavelength. We demonstrate all-fiber Er ring lasers operating at 303-MHz (soliton regime) and 274-MHz (stretched-pulse regime) repetition-rates. The 303-MHz (274-MHz) laser centered at 1555 nm (1550 nm) provides 7.5 nm (19 nm) spectral bandwidth. After extra-cavity amplilfication, the amplified pulse train of the 303-MHz (274-MHz) laser delivers 209 fs (178 fs) pulses. To our knowledge, this corresponds to the highest repetition-rates achieved for femtosecond lasers employing evanescent-field-interacting SAs. The demonstrated SA fabrication method, which is based on well-established PLC processes, also shows a potential way for mass-producible and lower-cost waveguide-type SA devices suitable for all-fiber and waveguide lasers.

Interaction between carbon fibers and polymer sizing: Influence of fiber surface chemistry and sizing reactivity

NASA Astrophysics Data System (ADS)

Moosburger-Will, Judith; Bauer, Matthias; Laukmanis, Eva; Horny, Robert; Wetjen, Denise; Manske, Tamara; Schmidt-Stein, Felix; Töpker, Jochen; Horn, Siegfried

2018-05-01

Different aspects of the interaction of carbon fibers and epoxy-based polymer sizings are investigated, e.g. the wetting behavior, the strength of adhesion between fiber and sizing, and the thermal stability of the sizing layer. The influence of carbon fiber surface chemistry and sizing reactivity is investigated using fibers of different degree of anodic oxidation and sizings with different number of reactive epoxy groups per molecule. Wetting of the carbon fibers by the sizing dispersion is found to be specified by both, the degree of fiber activation and the sizing reactivity. In contrast, adhesion strength between fibers and sizing is dominated by the surface chemistry of the carbon fibers. Here, the number of surface oxygen groups seems to be the limiting factor. We also find that the sizing and the additional functionalities induced by anodic oxidation are removed by thermal treatment at 600 °C, leaving the carbon fiber in its original state after carbonization.

Structural Fluctuations of the Chromatin Fiber within Topologically Associating Domains.

PubMed

Tiana, Guido; Amitai, Assaf; Pollex, Tim; Piolot, Tristan; Holcman, David; Heard, Edith; Giorgetti, Luca

2016-03-29

Experiments based on chromosome conformation capture have shown that mammalian genomes are partitioned into topologically associating domains (TADs), within which the chromatin fiber preferentially interacts. TADs may provide three-dimensional scaffolds allowing genes to contact their appropriate distal regulatory DNA sequences (e.g., enhancers) and thus to be properly regulated. Understanding the cell-to-cell and temporal variability of the chromatin fiber within TADs, and what determines them, is thus of great importance to better understand transcriptional regulation. We recently described an equilibrium polymer model that can accurately predict cell-to-cell variation of chromosome conformation within single TADs, from chromosome conformation capture-based data. Here we further analyze the conformational and energetic properties of our model. We show that the chromatin fiber within TADs can easily fluctuate between several conformational states, which are hierarchically organized and are not separated by important free energy barriers, and that this is facilitated by the fact that the chromatin fiber within TADs is close to the onset of the coil-globule transition. We further show that in this dynamic state the properties of the chromatin fiber, and its contact probabilities in particular, are determined in a nontrivial manner not only by site-specific interactions between strongly interacting loci along the fiber, but also by nonlocal correlations between pairs of contacts. Finally, we use live-cell experiments to measure the dynamics of the chromatin fiber in mouse embryonic stem cells, in combination with dynamical simulations, and predict that conformational changes within one TAD are likely to occur on timescales that are much shorter than the duration of one cell cycle. This suggests that genes and their regulatory elements may come together and disassociate several times during a cell cycle. These results have important implications for transcriptional regulation as they support the concept of highly dynamic interactions driven by a complex interplay between site-specific interactions and the intrinsic biophysical properties of the chromatin fiber. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Contrasting Effects of Human, Canine, and Hybrid Adenovirus Vectors on the Phenotypical and Functional Maturation of Human Dendritic Cells: Implications for Clinical Efficacy▿

PubMed Central

Perreau, Matthieu; Mennechet, Franck; Serratrice, Nicolas; Glasgow, Joel N.; Curiel, David T.; Wodrich, Harald; Kremer, Eric J.

2007-01-01

Antipathogen immune responses create a balance between immunity, tolerance, and immune evasion. However, during gene therapy most viral vectors are delivered in substantial doses and are incapable of expressing gene products that reduce the host's ability to detect transduced cells. Gene transfer efficacy is also modified by the in vivo transduction of dendritic cells (DC), which notably increases the immunogenicity of virions and vector-encoded genes. In this study, we evaluated parameters that are relevant to the use of canine adenovirus serotype 2 (CAV-2) vectors in the clinical setting by assaying their effect on human monocyte-derived DC (hMoDC). We compared CAV-2 to human adenovirus (HAd) vectors containing the wild-type virion, functional deletions in the penton base RGD motif, and the CAV-2 fiber knob. In contrast to the HAd type 5 (HAd5)-based vectors, CAV-2 poorly transduced hMoDC, provoked minimal upregulation of major histocompatibility complex class I/II and costimulatory molecules (CD40, CD80, and CD86), and induced negligible morphological changes indicative of DC maturation. Functional maturation assay results (e.g., reduced antigen uptake; tumor necrosis factor alpha, interleukin-1β [IL-1β], gamma interferon [IFN-γ], IL-10, IL-12, and IFN-α/β secretion; and stimulation of heterologous T-cell proliferation) were also significantly lower for CAV-2. Our data suggested that this was due, in part, to the use of an alternative receptor and a block in vesicular escape. Additionally, HAd5 vector-induced hMoDC maturation was independent of the aforementioned cytokines. Paradoxically, an HAd5/CAV-2 hybrid vector induced the greatest phenotypical and functional maturation of hMoDC. Our data suggest that CAV-2 and the HAd5/CAV-2 vector may be the antithesis of Adenoviridae immunogenicity and that each may have specific clinical advantages. PMID:17229706

Vector rectangular-shape laser based on reduced graphene oxide interacting with a long fiber taper.

PubMed

Gao, Lei; Zhu, Tao; Huang, Wei; Zeng, Jing

2014-10-01

A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber taper deposited with reduced graphene oxide is proposed, where nonlinearity is enhanced due to a large evanescent-field-interacting length and strong field confinement of an 8 mm fiber taper with a waist diameter of 4 μm. Graphene flakes are deposited uniformly on the taper waist with light pressure effect, so this structure guarantees both excellent saturable absorption and high nonlinearity. The RSL with a repetition rate of 7.9 MHz shows fast polarization switching in two orthogonal polarization directions, and temporal and spectral characteristics are investigated.

Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

NASA Astrophysics Data System (ADS)

Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

2017-04-01

We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

Making Optical-Fiber Chemical Detectors More Sensitive

NASA Technical Reports Server (NTRS)

Rogowski, Robert S.; Egalon, Claudio O.

1993-01-01

Calculations based on exact theory of optical fiber shown how to increase optical efficiency and sensitivity of active-cladding step-index-profile optical-fiber fluorosensor using evanescent wave coupling. Optical-fiber fluorosensor contains molecules fluorescing when illuminated by suitable light in presence of analyte. Fluorescence coupled into and launched along core by evanescent-wave interaction. Efficiency increases with difference in refractive indices.

A composites-based hyperelastic constitutive model for soft tissue with application to the human annulus fibrosus

NASA Astrophysics Data System (ADS)

Guo, Z. Y.; Peng, X. Q.; Moran, B.

2006-09-01

This paper presents a composites-based hyperelastic constitutive model for soft tissue. Well organized soft tissue is treated as a composite in which the matrix material is embedded with a single family of aligned fibers. The fiber is modeled as a generalized neo-Hookean material in which the stiffness depends on fiber stretch. The deformation gradient is decomposed multiplicatively into two parts: a uniaxial deformation along the fiber direction and a subsequent shear deformation. This permits the fiber-matrix interaction caused by inhomogeneous deformation to be estimated by using effective properties from conventional composites theory based on small strain linear elasticity and suitably generalized to the present large deformation case. A transversely isotropic hyperelastic model is proposed to describe the mechanical behavior of fiber-reinforced soft tissue. This model is then applied to the human annulus fibrosus. Because of the layered anatomical structure of the annulus fibrosus, an orthotropic hyperelastic model of the annulus fibrosus is developed. Simulations show that the model reproduces the stress-strain response of the human annulus fibrosus accurately. We also show that the expression for the fiber-matrix shear interaction energy used in a previous phenomenological model is compatible with that derived in the present paper.

ECM remodeling and its plasticity

NASA Astrophysics Data System (ADS)

Feng, Jingchen; Jones, Christopher A. R.; Cibula, Matthew; Mao, Xiaoming; Sander, Leonard M.; Levine, Herbert; Sun, Bo

The mechanical interactions between cells and Extracellular Matrix (ECM) are of great importance in many cellular processes. These interactions are reciprocal, i.e. contracting cells pull and reorganize the surrounding matrix, while the remodeled matrix feeds back to regulate cell activities. Recent experiments show in collagen gels with densely distributed cells, aligned fiber bundles are formed in the direction between neighboring cells. Fibers flow into the center region between contracting cell pairs in this process, which causes the concentration of fibers in the fiber bundles to become significantly enhanced. Using an extended lattice-based model, we show that viscoelasticity plays an essential role in ECM remodeling and contributes to the enhanced concentration in fiber bundles. We further characterize ECM plasticity within our model and verify our results with rheometer experiments.

Effects of fiber/matrix interactions on the interfacial deformation micromechanics of cellulose-fiber/polymer composites

NASA Astrophysics Data System (ADS)

Tze, William Tai-Yin

The overall objective of this dissertation was to gain an understanding of the relationship between interfacial chemistry and the micromechanics of the cellulose-fiber/polymer composites. Regenerated cellulose (lyocell) fibers were treated with amine-, phenylamine-, phenyl-, and octadecyl-silanes, and also styrene-maleic anhydride copolymer. Inverse gas chromatography was conducted to evaluate the modified surfaces and to examine the adsorption behavior of ethylbenzene, a model compound for polystyrene, onto the fibers. Micro-composites were formed by depositing micro-droplets of polystyrene onto single fibers. The fiber was subjected to a tensile strain, and Raman spectroscopy was employed to determine the point-to-point variation of the strain- and stress-sensitive 895 cm-1 band of cellulose along the embedded region. Inverse gas chromatography studies reveal that the Ia-b values, calculated by matching the Lewis acid parameter ( KA) and basic parameter (KB) between polystyrene and different fibers, were closely correlated to the acid-base adsorption enthalpies of ethylbenzene onto the corresponding fibers. Hence, Ia-b was subsequently used as a convenient indicator for fiber/matrix acid-base interaction. The Raman micro-spectroscopic studies demonstrate that the interfacial tensile strain and stress are highest at the edge of the droplet, and these values decline from the edge region to the middle region of the embedment. The maximum of these local strains corresponds to a strain-control fracture of the matrix polymer. The minimum of the local tensile stress corresponds to the extent of fiber-to-matrix load transfer. The slope of the tensile stress profile allows for an estimation of the maximum interfacial shear stress, which is indicative of fiber/polymer (practical) adhesion. As such, a novel micro-Raman tensile technique was established for evaluating the ductile-fiber/brittle-polymer system in this study. The micro-Raman tensile technique provided maximum interfacial shear stress values of 8.0 to 13.8 MPa, ranking functional groups according to their practical adhesion to polystyrene: alkyl < untreated < phenyl = phenylamine = styrene copolymer < amine. Overall, interfacial bonding can be increased by increasing the acid-base interactions (Ia-b) or reducing the chemical incompatibility (Deltadelta) between the fibers and matrix. Therefore, interfacial chemistry can be employed to enhance and predict cellulose-fiber/polymer adhesion to better engineer composite properties and ultimately better utilize bio-resources.

Fiber temperature sensor with nanostructured cladding by TiO2 nanoparticles self-assembled onto a side polished optical fiber

NASA Astrophysics Data System (ADS)

Yang, Bing; Chen, Zhe; Wang, Yiting; Zhang, Jun; Liao, Guozhen; Tian, Zhengwen; Yu, Jianhui; Tang, Jieyuan; Luo, Yunhan; Lu, Huihui

2015-07-01

A temperature fiber sensor with nanostructured cladding composed ted by titanium dioxide (TiO2) nanoparticles was demonstrated. The nanoparticles self-assembled onto a side polished optical fiber (SPF). The enhancement of interaction between the propagating light and the TiO2 nanoparticles (TN) can be obtained via strong evanescent field of the SPF. The strong light-TN interaction gives rise to temperature sensing with a optical power variation of ~4dB in SPF experimentally for an environment temperature ranging from -7.8°C to 77.6°C. The novel temperature sensor shows a sensitivity of ~0.044 dB/°C. The TN-based fiber-optic temperature sensor is facile to manufactured, compatible with fiber-optic interconnections and high potential in photonics applications.

Polarization domain wall pulses in a microfiber-based topological insulator fiber laser

PubMed Central

Liu, Jingmin; Li, Xingliang; Zhang, Shumin; Zhang, Han; Yan, Peiguang; Han, Mengmeng; Pang, Zhaoguang; Yang, Zhenjun

2016-01-01

Topological insulators (TIs), are novel two-dimension materials, which can act as effective saturable absorbers (SAs) in a fiber laser. Moreover, based on the evanescent wave interaction, deposition of the TI on microfiber would create an effective SA, which has combined advantages from the strong nonlinear optical response in TI material together with the sufficiently-long-range interaction length in fiber taper. By using this type of TI SA, various scalar solitons have been obtained in fiber lasers. However, a single mode fiber always exhibits birefringence, and hence can support two orthogonal degenerate modes. Here we investigate experimentally the vector characters of a TI SA fiber laser. Using the saturated absorption and the high nonlinearity of the TI SA, a rich variety of dynamic states, including polarization-locked dark pulses and their harmonic mode locked counterparts, polarization-locked noise-like pulses and their harmonic mode locked counterparts, incoherently coupled polarization domain wall pulses, including bright square pulses, bright-dark pulse pairs, dark pulses and bright square pulse-dark pulse pairs are all observed with different pump powers and polarization states. PMID:27381942

Polarization domain wall pulses in a microfiber-based topological insulator fiber laser

NASA Astrophysics Data System (ADS)

Liu, Jingmin; Li, Xingliang; Zhang, Shumin; Zhang, Han; Yan, Peiguang; Han, Mengmeng; Pang, Zhaoguang; Yang, Zhenjun

2016-07-01

Topological insulators (TIs), are novel two-dimension materials, which can act as effective saturable absorbers (SAs) in a fiber laser. Moreover, based on the evanescent wave interaction, deposition of the TI on microfiber would create an effective SA, which has combined advantages from the strong nonlinear optical response in TI material together with the sufficiently-long-range interaction length in fiber taper. By using this type of TI SA, various scalar solitons have been obtained in fiber lasers. However, a single mode fiber always exhibits birefringence, and hence can support two orthogonal degenerate modes. Here we investigate experimentally the vector characters of a TI SA fiber laser. Using the saturated absorption and the high nonlinearity of the TI SA, a rich variety of dynamic states, including polarization-locked dark pulses and their harmonic mode locked counterparts, polarization-locked noise-like pulses and their harmonic mode locked counterparts, incoherently coupled polarization domain wall pulses, including bright square pulses, bright-dark pulse pairs, dark pulses and bright square pulse-dark pulse pairs are all observed with different pump powers and polarization states.

Rheological properties of molten flax- and Tencel{sup ®}-polypropylene composites: Influence of fiber morphology and concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdennadher, Ahmed; Vincent, Michel; Budtova, Tatiana, E-mail: Tatiana.Budtova@mines-paristech.fr

The rheological properties of short fiber reinforced polypropylene were investigated. Flax and Tencel{sup ®} are two cellulose based fibers used in this study. Flax fibers are extracted from the bast of plants. They are composed of thin elementary fibers and rigid thick bundles made of elementary fibers “glued” together. Tencel{sup ®} is a man-made cellulosic fiber spun from cellulose solution, with a uniform diameter, thin, and flexible. First, fiber dimensions before and after compounding were analyzed. Both types of fibers were broken during compounding. Flax shows larger length and diameter than Tencel{sup ®}, but aspect ratio of flax is smaller.more » The reason is that after compounding flax remained in bundles. Dynamic viscosity, elastic and viscous moduli were studied as a function of fiber type, concentration (from 0 to 30 wt. %), and composite temperature (from 180 to 200 °C). All Tencel{sup ®}-based composites showed higher apparent yield stress, viscosity, and moduli compared to flax-based composites at the same fiber concentrations. The results are analyzed in terms of the influence of fiber type, aspect ratio, and flexibility. The importance of considering fiber morphology is demonstrated as far as it controls fiber flexibility and fiber-fiber interactions.« less

Interface-Controlled Conductive Fibers for Wearable Strain Sensors and Stretchable Conducting Wires.

PubMed

Cao, Zherui; Wang, Ranran; He, Tengyu; Xu, Fangfang; Sun, Jing

2018-04-25

As an important subfield of flexible electronics, conductive fibers have been an active area of research. The interfacial interaction between nanostructured conductive materials with elastic substrates plays a vital role in the electromechanical performance of conductive fibers. However, the underlying mechanism has seldom been investigated. Here, we propose a fabricating strategy for a silver nanowire (Ag NW)/polyurethane composite fiber with a sheath-core architecture. The interfacial bonding layer is regulated, and its influence on the performance of conductive fibers is investigated, based on which an interfacial interaction model is proposed. The model underlines the significance of the embedding depth of the Ag NW network. Both supersensitive (gauge factor up to 9557) and ultrastable (negligible conductance degradation below the strain of 150%) conductive fibers are obtained via interface regulating, exhibiting great potential in the applications of wearable sensors and stretchable conducting connections.

Comparison of analytical protein separation characteristics for three amine-based capillary-channeled polymer (C-CP) stationary phases.

PubMed

Jiang, Liuwei; Marcus, R Kenneth

2016-02-01

Capillary-channeled polymer (C-CP) fiber stationary phases are finding utility in the realms of protein analytics as well as downstream processing. We have recently described the modification of poly(ethylene terephthalate) (PET) C-CP fibers to affect amine-rich phases for the weak anion-exchange (WAX) separation of proteins. Polyethylenimine (PEI) is covalently coupled to the PET surface, with subsequent cross-linking imparted by treatment with 1,4-butanediol diglycidyl ether (BUDGE). These modifications yield vastly improved dynamic binding capacities over the unmodified fibers. We have also previously employed native (unmodified) nylon 6 C-CP fibers as weak anion/cation-exchange (mixed-mode) and hydrophobic interaction chromatography (HIC) phases for protein separations. Polyamide, nylon 6, consists of amide groups along the polymer backbone, with primary amines and carboxylic acid end groups. The analytical separation characteristics of these three amine-based C-CP fiber phases are compared here. Each of the C-CP fiber columns in this study was shown to be able to separate a bovine serum albumin/hemoglobin/lysozyme mixture at high mobile phase linear velocity (∼70 mm s(-1)) but with different elution characteristics. These differences reflect the types of protein-surface interactions that are occurring, based on the active group composition of the fiber surfaces. This study provides important fundamental understanding for the development of surface-modified C-CP fiber columns for protein separation.

Refractive-index-sensing fiber comb using intracavity multi-mode interference fiber sensor

NASA Astrophysics Data System (ADS)

Oe, Ryo; Minamikawa, Takeo; Taue, Shuji; Fukano, Hideki; Nakajima, Yoshiaki; Minoshima, Kaoru; Yasui, Takeshi

2018-02-01

Refractive index measurement is important for evaluation of liquid materials, optical components, and bio sensing. One promising approach for such measurement is use of optical fiber sensors such as surface plasmonic resonance or multi-mode interference (MMI), which measure the change of optical spectrum resulting from the refractive index change. However, the precision of refractive index measurement is limited by the performance of optical spectrum analyzer. If such the refractive index measurement can be performed in radio frequency (RF) region in place of optical region, the measurement precision will be further improved by the frequency-standard-based RF measurement. To this end, we focus on the disturbance-to-RF conversion in a fiber optical frequency comb (OFC) cavity. Since frequency spacing frep of OFC depends on an optical cavity length nL, frep sensitively reflects the external disturbance interacted with nL. Although we previously demonstrated the precise strain measurement based on the frep measurement, the measurable physical quantity is limited to strain or temperature, which directly interacts with the fiber cavity itself. If a functional fiber sensor can be installed into the fiber OFC cavity, the measurable physical quantity will be largely expanded. In this paper, we introduce a MMI fiber sensor into a ring-type fiber OFC cavity for refractive index measurement. We confirmed the refractive-index-dependent frep shift.

Report to Congress on the Defense Industrial Base: Critical Industries Planning

DTIC Science & Technology

1990-10-01

interactions between fibers and matrices, and production, each exhibiting its own unique the adhesive or fastening systems used to join characteristics. The... interaction among companies specializing in the Douglas and Custom Machine Inc.. although various areas in order to optimize the total Japanese suppliers...Minarad Scientific Inc. Barrianeer Research Lim. Contraves Goerz Corp. Geophysical Environmental Research Corp IRIS Fiber Optics ITT Corp. Magnavox

Ultrastrong Graphene-Based Fibers with Increased Elongation.

PubMed

Li, Mochen; Zhang, Xiaohong; Wang, Xiang; Ru, Yue; Qiao, Jinliang

2016-10-12

A new method to prepare graphene-based fibers with ultrahigh tensile strength, conductivity, and increased elongation is reported. It includes wet-spinning the mixture of GO aqueous dispersion with phenolic resin solution in a newly developed coagulation bath, followed by annealing. The introduced phenolic carbon increased densification of graphene fibers through reducing defects and increased interfacial interaction among graphene sheets by forming new C-C bonds, thus resulting in the increasing of stiffness, toughness, and conductivity simultaneously.

Degradation of cellulose under alkaline conditions: new insights from a 12 years degradation study.

PubMed

Glaus, Martin A; Van Loon, Luc R

2008-04-15

Cellulose degradation under alkaline conditions is of relevance to the mobility of many cations of the transition metal, lanthanide, and actinide series in the geosphere because strong complexants such as isosaccharinic acids, 3-deoxy-2-C-hydroxymethyl-D-erythro-pentonic acid (alpha-ISA) and 3-deoxy-2-C-hydroxymethyl-D-threo-pentonic acid (beta-ISA) may be formed. In the context of the long-term safety of cementitious repositories for low- and intermediate-level radioactive waste, where large amounts of cellulose may be present, the question of the time scales needed for the complete degradation of cellulose is important. The present paper reports the results of a 12 year study of the degradation of four different cellulosic materials (pure cellulose, tissue, cotton, paper) in an artificial cement pore water under anaerobic conditions at approximately 25 degrees C. The observed reaction characteristics can be divided into a fast reaction phase (2-3 years), dominated by the stepwise conversion of terminal glucose monomeric units to alpha-ISA and beta-ISA, and a very slow reaction phase during which the same products were found. The slow rate of the alkaline degradation of cellulose during this second reaction phase shows that previous kinetic models of cellulose degradation did not adequately describe the long-term behavior under alkaline conditions and need to be reassessed. It is postulated that a previously unknown mechanism by which crystalline or inaccessible reducing end groups of the polysaccharide chain become temporarily susceptible to alkaline attack is responsible for the slow rate of cellulose degradation.

Sliding durability of two carbide-oxide candidate high temperature fiber seal materials in air to 900 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Steinetz, Bruce M.

1992-01-01

A test program to determine the friction and wear properties of two complex carbide oxide ceramic fibers for high temperature sliding seal applications is described. The fibers are based on Si, C, O, and Ti or Si, C, N, and O ceramic systems. Pin on disk tests using ceramic fiber covered pins and Inconel 718 disks, were conducted in air from 25 to 900 C to evaluate potential seal materials. This testing procedure was used in a previous study of oxide ceramic fibers which were found to exhibit wear behavior based predominantly on their mechanical properties. Like the oxide fibers tested previously, these carbide oxide ceramic fibers, show an increase in friction and wear with increased test temperature. At room temperature, the wear behavior seems to be based upon mechanical properties, namely tensile strength. At 500 and especially 900 C, the fibers wear by both mechanical fracture and by oxidative type wear. Based upon post test microscopic and x ray analyses, interaction between the fiber constituents and elements transferred from the counterface, namely Ni and Cr, may have occurred enhancing the tribochemical wear process. These results are interpreted.

Does Topology Drive Fiber Polymerization?

PubMed Central

2015-01-01

We have developed new procedures to examine the early steps in fibrin polymerization. First, we isolated fibrinogen monomers from plasma fibrinogen by gel filtration. Polymerization of fibrinogen monomers differed from that of plasma fibrinogen. The formation of protofibrils was slower and the transformation of protofibrils to fibers faster for the fibrinogen monomers. Second, we used formaldehyde to terminate the polymerization reactions. The formaldehyde-fixed products obtained at each time point were examined by dynamic light scattering and transmission electron microscopy (TEM). The data showed the formaldehyde-fixed products were stable and representative of the reaction intermediates. TEM images showed monomers, short oligomers, protofibrils, and thin fibers. The amount and length of these species varied with time. Short oligomers were less than 5% of the molecules at all times. Third, we developed models that recapitulate the TEM images. Fibrin monomer models were assembled into protofibrils, and protofibrils were assembled into two-strand fibers using Chimera software. Monomers were based on fibrinogen crystal structures, and the end-to-end interactions between monomers were based on D-dimer crystal structures. Protofibrils assembled from S-shaped monomers through asymmetric D:D interactions were ordered helical structures. Fibers were modeled by duplicating a protofibril and rotating the duplicate 120° around its long axis. No specific interactions were presumed. The two protofibrils simply twisted around one another to form a fiber. This model suggests that the conformation of the protofibril per se promotes the assembly into fibers. These findings introduce a novel mechanism for fibrin assembly that may be relevant to other biopolymers. PMID:25419972

Mechanical properties of green composites based on thermoplastic starch

NASA Astrophysics Data System (ADS)

Fornes, F.; Sánchez-Nácher, L.; Fenollar, O.; Boronat, T.; Garcia-Sanoguera, D.

2010-06-01

The present work is focused on study of "green composites" elaborated from thermoplastic starch (TPS) as polymer matrix and a fiber from natural origin (rush) as reinforced fiber. The effect of the fiber content has been studied by means of the mechanical properties. The composite resulting presents a lack of interaction between matrix and fiber that represents a performance decrease. However the biodegradability behavior of the resulting composite raise this composite as useful an industrial level.

Polarization dependence of laser interaction with carbon fibers and CFRP.

PubMed

Freitag, Christian; Weber, Rudolf; Graf, Thomas

2014-01-27

A key factor for laser materials processing is the absorptivity of the material at the laser wavelength, which determines the fraction of the laser energy that is coupled into the material. Based on the Fresnel equations, a theoretical model is used to determine the absorptivity for carbon fiber fabrics and carbon fiber reinforced plastics (CFRP). The surface of each carbon fiber is considered as multiple layers of concentric cylinders of graphite. With this the optical properties of carbon fibers and their composites can be estimated from the well-known optical properties of graphite.

Hollow-core photonic-crystal-fiber-based optical frequency references

NASA Astrophysics Data System (ADS)

Holá, Miroslava; Hrabina, Jan; Mikel, Břetislav; Lazar, Josef; Číp, Ondřej

2016-12-01

This research deals with preparation of an optical frequency references based on hollow-core photonic crystal fibers (HC-PCF). This fiber-based type of absorption cells represents a effiecient way how to replace classic bulky and fragile glass made tubes references with low-weight and low-volume optical fibers. This approach allows not only to increase possible interaction length between incident light and absorption media but it also carries a possibility of manufacturing of easy-operable reference which is set up just by plugging-in of optical connectors into the optical setup. We present the results of preparation, manufacturing and filling of a set of fiber-based cells intended for lasers frequency stabilization. The work deals with setting and optimalization of HC-PCF splicing processes, minimalization of optical losses between HC-PCF and SMF fiber transitions and finishing of HC-PCF spliced ends with special care for optimal closing of hollow-core structure needed for avoiding of absorption media leakage.

Interactive educational technologies as a method of communicative competency development of optical and fiber optic communication systems specialists

NASA Astrophysics Data System (ADS)

Matveeva, Tatiana U.; Osadchiy, Igor S.; Husnutdinova, Marina N.

2017-04-01

The article examines the process of formation of communicative competencies of optic and fiber optic communication systems specialists; the role of communicative competencies is examined in the structure of professionally important skills, together with the contents of professional activity. The stages of empirical research into formation of communicative competencies have been presented, and the values of statistical reliability of data have been provided. The model of formation of communicative competency using interactive technology has been developed based on the research done, and main stages of model implementation and motives of formation of communicative competency have been highlighted. A scheme of "Communicative competence as a base of future success" training session has been suggested as one of the basic interactive technologies. Main components of education that are used during the stages of the training cycle have been examined. The statistical data on the effectiveness of use of interactive educational technologies has been presented; it allowed development of communicative competency of specialists in the field of optical and fiber optic communication system.

Optical sensor for fluoride determination in tea sample based on evanescent-wave interaction and fiber-optic integration.

PubMed

Xiong, Yan; Wu, Jiayi; Wang, Qing; Xu, Jing; Fang, Shenwen; Chen, Jie; Duan, Ming

2017-11-01

In this work, a miniaturized optical sensor was developed for fluoride determination in tea samples to evaluate their specific risks of fluorosis for public health based on evanescent-wave interaction. The sensor design was integrated on the optical fiber by utilizing the evanescent wave produced on the fiber surface to react with sensing reagents. According to the absorption change at 575nm, fluoride could be determined by colorimetric method and evaluated by Beer's law. With improved performances of small detection volume (1.2μL), fast analysis (0.41min), wide linear range (0.01-1.4mgL -1 ), low detection limit (3.5μgL -1 , 3σ) and excellent repeatability (2.34%), the sensor has been applied to fluoride determination in six different tea samples. Conventional spectrophotometry and ion chromatography were employed to validate the sensor's accuracy and potential application. Furthermore, this sensor fabrication provided a miniaturized colorimetric detection platform for other hazardous species monitoring based on evanescent wave interaction. Copyright © 2017 Elsevier B.V. All rights reserved.

Simulation of Guided Wave Interaction with In-Plane Fiber Waviness

NASA Technical Reports Server (NTRS)

Leckey, Cara A. C.; Juarez, Peter D.

2016-01-01

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

Simulation of guided wave interaction with in-plane fiber waviness

NASA Astrophysics Data System (ADS)

Leckey, Cara A. C.; Juarez, Peter D.

2017-02-01

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

Effects of fiber/matrix interactions on the properties of graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Mcmahon, P. E.; Ying, L.

1982-01-01

A state-of-the-art literature review of the interactions between fibers and resin within graphite epoxy composite materials was performed. Emphasis centered on: adhesion theory; wetting characteristics of carbon fiber; load transfer mechanisms; methods to evaluate and measure interfacial bond strengths; environmental influence at the interface; and the effect of the interface/interphase on composite performance, with particular attention to impact toughness. In conjunction with the literature review, efforts were made to design experiments to study the wetting behavior of carbon fibers with various finish variants and their effect on adhesion joint strength. The properties of composites with various fiber finishes were measured and compared to the base-line properties of a control. It was shown that by tailoring the interphase properties, a 30% increase in impact toughness was achieved without loss of mechanical properties at both room and elevated temperatures.

Graphene mode-lockers for fiber lasers functioned with evanescent field interaction

NASA Astrophysics Data System (ADS)

Song, Yong-Won; Jang, Sung-Yeon; Han, Won-Suk; Bae, Mi-Kyung

2010-02-01

Employing graphene as an intracavity passive power modulating element, we demonstrate the efficient laser pulsation in high pulse-energy regime with evanescent field interaction between the propagating light and graphene layer. Graphene is prepared by the solution based reduction of graphene oxide, and dispersed homogeneously into the water for spray onto an all-fiber substrate, side-polished fiber. With the intracavity power up to 21.41 dBm, we ensure the robust high-energy operation without any thermal damage of graphene. Resultant output pulses have center wavelength, spectral width, and repetition rate of 1561.6 nm, 1.96 nm, and 6.99 MHz, respectively.

Methods And Apparatus For Acoustic Fiber Fractionation

DOEpatents

Brodeur, Pierre

1999-11-09

Methods and apparatus for acoustic fiber fractionation using a plane ultrasonic wave field interacting with water suspended fibers circulating in a channel flow using acoustic radiation forces to separate fibers into two or more fractions based on fiber radius, with applications of the separation concept in the pulp and paper industry. The continuous process relies on the use of a wall-mounted, rectangular cross-section piezoelectric ceramic transducer to selectively deflect flowing fibers as they penetrate the ultrasonic field. The described embodiment uses a transducer frequency of approximately 150 kHz. Depending upon the amount of dissolved gas in water, separation is obtained using a standing or a traveling wave field.

Numerical simulation of fiber interaction in short-fiber injection-molded composite using different cavity geometries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thi, Thanh Binh Nguyen, E-mail: nttbinh@kit.ac.jp; Yokoyama, Atsushi, E-mail: yokoyama@kit.ac.jp; Hamanaka, Senji

The theoretical fiber-interaction model for calculating the fiber orientation in the injection molded short fiber/thermoplastic composite parts was proposed. The proposed model included the fiber dynamics simulation in order to obtain an equation of the global interaction coefficient and accurate estimate of the fiber interacts at all orientation states. The steps to derive the equation for this coefficient in short fiber suspension as a function of the fiber aspect ratio, volume fraction and general shear rate are delineated. Simultaneously, the high-resolution 3D X-ray computed tomography system XVA-160α was used to observe fiber distribution of short-glass-fiber-reinforced polyamide specimens using different cavitymore » geometries. The fiber orientation tensor components are then calculated. Experimental orientation measurements of short-glass-fiber-reinforced polyamide is used to check the ability of present theory for predicting orientation. The experiments and predictions show a quantitative agreement and confirm the basic understanding of fiber orientation in injection-molded composites.« less

Numerical simulation of fiber interaction in short-fiber injection-molded composite using different cavity geometries

NASA Astrophysics Data System (ADS)

Thi, Thanh Binh Nguyen; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

2016-03-01

The theoretical fiber-interaction model for calculating the fiber orientation in the injection molded short fiber/thermoplastic composite parts was proposed. The proposed model included the fiber dynamics simulation in order to obtain an equation of the global interaction coefficient and accurate estimate of the fiber interacts at all orientation states. The steps to derive the equation for this coefficient in short fiber suspension as a function of the fiber aspect ratio, volume fraction and general shear rate are delineated. Simultaneously, the high-resolution 3D X-ray computed tomography system XVA-160α was used to observe fiber distribution of short-glass-fiber-reinforced polyamide specimens using different cavity geometries. The fiber orientation tensor components are then calculated. Experimental orientation measurements of short-glass-fiber-reinforced polyamide is used to check the ability of present theory for predicting orientation. The experiments and predictions show a quantitative agreement and confirm the basic understanding of fiber orientation in injection-molded composites.

Molecular interference of fibrin’s divalent polymerization mechanism enables modulation of multiscale material properties

PubMed Central

Brown, Ashley C.; Baker, Stephen; Douglas, Alison; Keating, Mark; Alvarez-Elizondo, Martha; Botvinick, Elliot; Guthold, Martin; Barker, Thomas H.

2015-01-01

Protein based polymers provide an exciting and complex landscape for tunable natural biomaterials through modulation of molecular level interactions. Here we demonstrate the ability to modify protein polymer structural and mechanical properties at multiple length scales by molecular ‘interference’ of fibrin’s native polymerization mechanism. We have previously reported that engagement of fibrin’s polymerization ‘hole b’, also known as ‘b-pockets’, through PEGylated complimentary ‘knob B’ mimics can increase fibrin network porosity but also, somewhat paradoxically, increase network stiffness. Here, we explore the possible mechanistic underpinning of this phenomenon through characterization of the effects of knob B-fibrin interaction at multiple length scales from molecular to bulk polymer. Despite its weak monovalent binding affinity for fibrin, addition of both knob B and PEGylated knob B at concentrations near the binding coefficient, Kd, increased fibrin network porosity, consistent with the reported role of knob B-hole b interactions in promoting lateral growth of fibrin fibers. Addition of PEGylated knob B decreases the extensibility of single fibrin fibers at concentrations near its Kd but increases extensibility of fibers at concentrations above its Kd. The data suggest this bimodal behavior is due to the individual contributions knob B, which decreases fiber extensibility, and PEG, which increase fiber extensibility. Taken together with laser trap-based microrheological and bulk rheological analyses of fibrin polymers, our data strongly suggests that hole b engagement increases in single fiber stiffness that translates to higher storage moduli of fibrin polymers despite their increased porosity. These data point to possible strategies for tuning fibrin polymer mechanical properties through modulation of single fiber mechanics. PMID:25725552

An Inventory of Pedagogical Considerations for Interactive Television.

ERIC Educational Resources Information Center

MacKinnon, Allan; And Others

1995-01-01

Reports on a research and development project based at Simon Fraser University (Canada) involving the use of interactive television in teacher education. Describes several interactive television conferences that have taken place in British Columbia using a fiber optics telephone network. Discusses pedagogical styles and interaction considerations.…

Using carboxylated cellulose nanofibers to enhance mechanical and barrier properties of collagen fiber film by electrostatic interaction.

PubMed

Wang, Wenhang; Zhang, Xiuling; Li, Cong; Du, Guanhua; Zhang, Hongjie; Ni, Yonghao

2018-06-01

Collagen-based films including casings with a promising application in meat industry are still needed to improve its inferior performance. In the present study, the reinforcement of carboxylated cellulose nanofibers (CNF) for collagen film, based on inter-/intra- molecular electrostatic interaction between cationic acid-swollen collagen fiber and anionic carboxylated CNF, was investigated. Adding CNF decreased the zeta-potential but increased particle size of collagen fiber suspension, with little effect on pH. Furthermore, CNF addition led to a higher tensile strength but a lower elongation, and the water vapor and oxygen barrier properties were improved remarkably. Because the CNF content was 50 g kg -1 or lower, the films had a homogeneous interwoven network, and CNF homogeneously embedded into collagen fiber matrix according to the scanning electron microscopy and atomic force microscopy analysis. Additionally, CNF addition increased film thickness and opacity, as well as swelling rate. The incorporation of CNF endows collagen fiber films good mechanical and barrier properties over a proper concentration range (≤ 50 g kg -1 collagen fiber), which is closely associated with electrostatic reaction of collagen fiber and CNF and, subsequently, the form of the homogenous, compatible spatial network, indicating a potential applications of CNF in collagenous protein films, such as edible casings. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

A Fibre-Optic Communications Network for Teaching Clinical Medicine.

ERIC Educational Resources Information Center

Williams, Robin

1985-01-01

Describes an interactive television system based on fiber-optic communications technology which is used to facilitate participation by University of London medical students in lecture/tutorials by teachers in different hospital locations. Highlights include advantages of fiber-optics, cable manufacture and installation, opto-electronic interface,…

Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi

Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey’s equation a diffusive type of term by introducing amore » phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29{sup th} International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.« less

Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

NASA Astrophysics Data System (ADS)

Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

2015-05-01

Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey's equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

Membrane materials for storing biological samples intended for comparative nanotoxicological testing

NASA Astrophysics Data System (ADS)

Metelkin, A.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

2015-11-01

The study is aimed at identifying the samples of most promising membrane materials for storing dry specimens of biological fluids (Dried Blood Spots, DBS technology). Existing sampling systems using cellulose fiber filter paper have a number of drawbacks such as uneven distribution of the sample spot, dependence of the spot spreading area on the individual biosample properties, incomplete washing-off of the sample due to partially inconvertible sorption of blood components on cellulose fibers, etc. Samples of membrane materials based on cellulose, polymers and glass fiber with applied biosamples were studied using methods of scanning electron microscopy, FT-IR spectroscopy and surface-wetting measurement. It was discovered that cellulose-based membrane materials sorb components of biological fluids inside their structure, while membranes based on glass fiber display almost no interaction with the samples and biological fluid components dry to films in the membrane pores between the structural fibers. This characteristic, together with the fact that membrane materials based on glass fiber possess sufficient strength, high wetting properties and good storage capacity, attests them as promising material for dry samples of biological fluids storage systems.

Photoacoustic shock wave emission and cavitation from structured optical fiber tips

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadzadeh, M.; Gonzalez-Avila, S. R.; Ohl, C. D., E-mail: cdohl@ntu.edu.sg

Photoacoustic waves generated at the tip of an optical fiber consist of a compressive shock wave followed by tensile diffraction waves. These tensile waves overlap along the fiber axis and form a cloud of cavitation bubbles. We demonstrate that shaping the fiber tip through micromachining alters the number and direction of the emitted waves and cavitation clouds. Shock wave emission and cavitation patterns from five distinctively shaped fiber tips have been studied experimentally and compared to a linear wave propagation model. In particular, multiple shock wave emission and generation of strong tension away from the fiber axis have been realizedmore » using modified fiber tips. These altered waveforms may be applied for novel microsurgery protocols, such as fiber-based histotripsy, by utilizing bubble-shock wave interaction.« less

Antibody-based bacterial toxin detection

NASA Astrophysics Data System (ADS)

Menking, Darrell E.; Heitz, Jonathon M.; Anis, Nabil A.; Thompson, Roy G.

1994-03-01

Fiber optic evanescent fluorosensors are under investigation in our laboratory for the study of drug-receptor interactions for detection of threat agents and antibody-antigen interactions for detection of biological toxins. In a one step assay, antibodies against Cholera toxin or Staphylococcus Enterotoxin B were noncovalently immobilized on quartz fibers and probed with fluorescein-isothiocyanate (FITC)-labeled toxins. In the two-step assay, Cholera toxin or Botulinum toxoid A was immobilized onto the fiber, followed by incubation in an antiserum or partially purified antitoxin IgG. These were then probed with FITC-anti-IgG antibodies. Unlabeled toxins competed with labeled toxins or antitoxin IgG in a dose-dependent manner and the detection of the toxins was in the nanomolar range.

Nonadiabatic tapered optical fiber sensor for measuring interaction nicotine with DNA

NASA Astrophysics Data System (ADS)

Zibaii, M. I.; Latifi, H.; Pourbeyram, H.; Gholami, M.; Taghipour, Z.; Saeedian, Z.; Hosseini, S. M.

2011-05-01

A nonadiabatic tapered optical fiber sensor was utilized for studying of bimolecular interactions including DNA-DNA and DNA-Drug interaction. This work presents a simple evanescent wave sensing system based on an interferometric approach, suitable to meet the requirements of lable-free sensor systems for detecting biomolecular interactions. We have demonstrated the measuring refractive index and the real time detection of interactions between biomolecules. Furthermore basic experiments were carried out, for detecting the hybridization of 25-mer DNA with an immobilized counterpart on the surface. The overall shift after the successful DNA hybridization was 9.5 nm. In this work, a new approach for studying DNA-drug interactions was successfully tested. Nicotine as a carcinogenic compound in cigarette smoke plays an important role in interaction with DNA. Different concentrations of nicotine were applied to observe the Longmuir interaction with DNA.

Combined raman and IR fiber-based sensor for gas detection

DOEpatents

Carter, Jerry C; Chan, James W; Trebes, James E; Angel, Stanley M; Mizaikoff, Boris

2014-06-24

A double-pass fiber-optic based spectroscopic gas sensor delivers Raman excitation light and infrared light to a hollow structure, such as a hollow fiber waveguide, that contains a gas sample of interest. A retro-reflector is placed at the end of this hollow structure to send the light back through the waveguide where the light is detected at the same end as the light source. This double pass retro reflector design increases the interaction path length of the light and the gas sample, and also reduces the form factor of the hollow structure.

All-fiber mode-locked laser via short single-wall carbon nanotubes interacting with evanescent wave in photonic crystal fiber.

PubMed

Li, Yujia; Gao, Lei; Huang, Wei; Gao, Cong; Liu, Min; Zhu, Tao

2016-10-03

We report an all-fiber passively mode-locked laser based on a saturable absorber fabricated by filling short single-wall carbon nanotubes into cladding holes of grapefruit-type photonic crystal fiber. The single-wall carbon nanotube is insensitive to polarization of light for its one-dimensional structure, which suppresses the polarization dependence loss. Carbon nanotubes interact with photonic crystal fiber with ultra-weak evanescent field, which enhances the damage threshold of the saturable absorber and improves the operating stability. In our experiment, conventional soliton with a pulse duration of 1.003 ps and center wavelength of 1566.36 nm under a pump power of 240 mW is generated in a compact erbium-doped fiber laser cavity with net anomalous dispersion of -0.4102 ps². The signal to noise ratio of the fundamental frequency component is ~80 dB. The maximum average output power of the mode-locked laser reaches 9.56 mW under a pump power of 360 mW. The output power can be further improved by a higher pump power.

Long period fiber grating based sensor for the detection of triacylglycerides.

PubMed

Baliyan, Anjli; Sital, Shivani; Tiwari, Umesh; Gupta, Rani; Sharma, Enakshi K

2016-05-15

In this paper, stable, label free enzyme based sensor using long period fiber grating (LPG) is described for the detection of triacylglycerides. A stable covalent binding technique for lipase enzyme immobilization on an optical fiber is reported. An active and stable attachment of the functional group of the enzyme on the fiber surface is achieved using this method. Enzyme immobilization is confirmed by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The stability is confirmed by lipase p-nitrophenyl palmitate (PNP) assay. In contrast to widely used amperometric based biosensor, where a number of enzymes are required, only one enzyme, namely, lipase is required in our sensor. The sensor shows optimum response within one minute at a temperature of 37°C and pH of 7.4. The sensor is based on the shift in resonance wavelength of the LPG transmission spectrum due to the interaction of triacylglycerides with the enzyme. The biosensor is highly specific towards triacylglycerides and is unaffected by the presence of many other interfering substances in serum. Interaction between the bio-molecules and the long period grating surface is also modeled theoretically using a four layer model for the LPG fiber with the bio-recognition layer and the results obtained are consistent with experimentally obtained results. The sensor shows a high sensitivity of 0.5 nm/mM and a low detection limit of 17.71 mg/dl for the physiological range of triacylglycerides in human blood. Copyright © 2015 Elsevier B.V. All rights reserved.

Nanoscale Morphology to Macroscopic Performance in Ultra High Molecular Weight Polyethylene Fibers

NASA Astrophysics Data System (ADS)

McDaniel, Preston B.

Ultra high molecular weight polyethylene (UHMWPE) fibers are increasingly used in high -performance applications where strength, stiffness, and the ability to dissipate energy are of critical importance. Despite their use in a variety of applications, the influence of morphological features at the meso/nanoscale on the macroscopic performance of the fibers has not been well understood. There is particular interest in gaining a better understanding of the nanoscale structure-property relationships in UHMWPE fibers used in ballistics applications. In order to accurately model and predict failure in the fiber, a more complete understanding of the complex load pathways that dictate the ways in which load is transferred through the fiber, across interfaces and length scales is required. The goal of the work discussed herein is to identify key meso/nanostructural features evolved in high performance fibers and determine how these features influence the performance of the fiber through a variety of different loading mechanisms. The important structural features in high-performance UHMWPE fibers are first identified through examination of the meso/nanostructure of a series of fibers with different processing conditions. This is achieved primarily through the use of wide-angle x-ray diffraction (WAXD) and atomic force microscopy (AFM). Analysis of AFM images and WAXD data allows identification and quantifications of important structural features at these length scales. Key meso/nanostructural features are then examined with respect to their influence on the transverse compression behavior of single fibers. Through post-mortem AFM analysis of samples at incremental compressive strains, the evolution of damage is examined and compared with macroscopic fiber mechanical response. It was found that collapse of mesoscale voids, followed by nanoscale fibrillation and reorganization of a fibrillar network has a significant influence on the mechanical response of the fiber. Through this work, the importance of nanoscale fibril adhesive interactions is highlighted. However, very little information exists in the literature as to the nature and magnitude of these interactions. Examination of nanoscale fibrillar adhesive interactions is experimentally difficult, and necessitated the development of an AFM based nanoscale splitting technique to quantify the interactions between fibrils. Through analysis of split geometry and careful partitioning of energies, the adhesive energy between fibrils in UHMWPE fibers are determined. The calculated average adhesive energies are significantly larger than the estimated energy due to van der Waals interactions, suggesting that there are physical connections (e.g., tie chains, tie fibrils, and lamellar crystalline bridges) that influence the interactions between fibrils. The interactions identified through this work are believed to be responsible for the creation of load pathways across fibril interfaces where load may be translated through the fiber in tension, compression, and shear. Finally, the nature of the mesoscale fibrillar network is explored through the development of a variable angle, single fiber peel test. This peel test enables the quantification of Mode I and Mode II peel energies. The modes of deformation observed in the peel test are representative of the mechanisms experienced during tensile and transverse compression loading. The quantification of peel energies in both Mode I and Mode II failure highlight the importance of the fibrillar network as a key mechanism for the translation of load through the fiber. In both modes of failure, the fibril network acts as a framework for the orientation and subsequent failure of nanoscale fibrils.

Interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Da-Shuai; Wu, Ge; Gao, Bo; Tian, Xiao-Jian

2013-01-01

We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the inter-cavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.

A novel psittacine adenovirus identified during an outbreak of avian chlamydiosis and human psittacosis: zoonosis associated with virus-bacterium coinfection in birds.

PubMed

To, Kelvin K W; Tse, Herman; Chan, Wan-Mui; Choi, Garnet K Y; Zhang, Anna J X; Sridhar, Siddharth; Wong, Sally C Y; Chan, Jasper F W; Chan, Andy S F; Woo, Patrick C Y; Lau, Susanna K P; Lo, Janice Y C; Chan, Kwok-Hung; Cheng, Vincent C C; Yuen, Kwok-Yung

2014-12-01

Chlamydophila psittaci is found worldwide, but is particularly common among psittacine birds in tropical and subtropical regions. While investigating a human psittacosis outbreak that was associated with avian chlamydiosis in Hong Kong, we identified a novel adenovirus in epidemiologically linked Mealy Parrots, which was not present in healthy birds unrelated to the outbreak or in other animals. The novel adenovirus (tentatively named Psittacine adenovirus HKU1) was most closely related to Duck adenovirus A in the Atadenovirus genus. Sequencing showed that the Psittacine adenovirus HKU1 genome consists of 31,735 nucleotides. Comparative genome analysis showed that the Psittacine adenovirus HKU1 genome contains 23 open reading frames (ORFs) with sequence similarity to known adenoviral genes, and six additional ORFs at the 3' end of the genome. Similar to Duck adenovirus A, the novel adenovirus lacks LH1, LH2 and LH3, which distinguishes it from other viruses in the Atadenovirus genus. Notably, fiber-2 protein, which is present in Aviadenovirus but not Atadenovirus, is also present in Psittacine adenovirus HKU1. Psittacine adenovirus HKU1 had pairwise amino acid sequence identities of 50.3-54.0% for the DNA polymerase, 64.6-70.7% for the penton protein, and 66.1-74.0% for the hexon protein with other Atadenovirus. The C. psittaci bacterial load was positively correlated with adenovirus viral load in the lung. Immunostaining for fiber protein expression was positive in lung and liver tissue cells of affected parrots, confirming active viral replication. No other viruses were found. This is the first documentation of an adenovirus-C. psittaci co-infection in an avian species that was associated with a human outbreak of psittacosis. Viral-bacterial co-infection often increases disease severity in both humans and animals. The role of viral-bacterial co-infection in animal-to-human transmission of infectious agents has not received sufficient attention and should be emphasized in the investigation of disease outbreaks in human and animals.

A Novel Psittacine Adenovirus Identified During an Outbreak of Avian Chlamydiosis and Human Psittacosis: Zoonosis Associated with Virus-Bacterium Coinfection in Birds

PubMed Central

Chan, Wan-Mui; Choi, Garnet K. Y.; Zhang, Anna J. X.; Sridhar, Siddharth; Wong, Sally C. Y.; Chan, Jasper F. W.; Chan, Andy S. F.; Woo, Patrick C. Y.; Lau, Susanna K. P.; Lo, Janice Y. C.; Chan, Kwok-Hung; Cheng, Vincent C. C.; Yuen, Kwok-Yung

2014-01-01

Chlamydophila psittaci is found worldwide, but is particularly common among psittacine birds in tropical and subtropical regions. While investigating a human psittacosis outbreak that was associated with avian chlamydiosis in Hong Kong, we identified a novel adenovirus in epidemiologically linked Mealy Parrots, which was not present in healthy birds unrelated to the outbreak or in other animals. The novel adenovirus (tentatively named Psittacine adenovirus HKU1) was most closely related to Duck adenovirus A in the Atadenovirus genus. Sequencing showed that the Psittacine adenovirus HKU1 genome consists of 31,735 nucleotides. Comparative genome analysis showed that the Psittacine adenovirus HKU1 genome contains 23 open reading frames (ORFs) with sequence similarity to known adenoviral genes, and six additional ORFs at the 3′ end of the genome. Similar to Duck adenovirus A, the novel adenovirus lacks LH1, LH2 and LH3, which distinguishes it from other viruses in the Atadenovirus genus. Notably, fiber-2 protein, which is present in Aviadenovirus but not Atadenovirus, is also present in Psittacine adenovirus HKU1. Psittacine adenovirus HKU1 had pairwise amino acid sequence identities of 50.3–54.0% for the DNA polymerase, 64.6–70.7% for the penton protein, and 66.1–74.0% for the hexon protein with other Atadenovirus. The C. psittaci bacterial load was positively correlated with adenovirus viral load in the lung. Immunostaining for fiber protein expression was positive in lung and liver tissue cells of affected parrots, confirming active viral replication. No other viruses were found. This is the first documentation of an adenovirus-C. psittaci co-infection in an avian species that was associated with a human outbreak of psittacosis. Viral-bacterial co-infection often increases disease severity in both humans and animals. The role of viral-bacterial co-infection in animal-to-human transmission of infectious agents has not received sufficient attention and should be emphasized in the investigation of disease outbreaks in human and animals. PMID:25474263

Fast and Exact Fiber Surfaces for Tetrahedral Meshes.

PubMed

Klacansky, Pavol; Tierny, Julien; Carr, Hamish; Zhao Geng

2017-07-01

Isosurfaces are fundamental geometrical objects for the analysis and visualization of volumetric scalar fields. Recent work has generalized them to bivariate volumetric fields with fiber surfaces, the pre-image of polygons in range space. However, the existing algorithm for their computation is approximate, and is limited to closed polygons. Moreover, its runtime performance does not allow instantaneous updates of the fiber surfaces upon user edits of the polygons. Overall, these limitations prevent a reliable and interactive exploration of the space of fiber surfaces. This paper introduces the first algorithm for the exact computation of fiber surfaces in tetrahedral meshes. It assumes no restriction on the topology of the input polygon, handles degenerate cases and better captures sharp features induced by polygon bends. The algorithm also allows visualization of individual fibers on the output surface, better illustrating their relationship with data features in range space. To enable truly interactive exploration sessions, we further improve the runtime performance of this algorithm. In particular, we show that it is trivially parallelizable and that it scales nearly linearly with the number of cores. Further, we study acceleration data-structures both in geometrical domain and range space and we show how to generalize interval trees used in isosurface extraction to fiber surface extraction. Experiments demonstrate the superiority of our algorithm over previous work, both in terms of accuracy and running time, with up to two orders of magnitude speedups. This improvement enables interactive edits of range polygons with instantaneous updates of the fiber surface for exploration purpose. A VTK-based reference implementation is provided as additional material to reproduce our results.

Method for oil pipeline leak detection based on distributed fiber optic technology

NASA Astrophysics Data System (ADS)

Chen, Huabo; Tu, Yaqing; Luo, Ting

1998-08-01

Pipeline leak detection is a difficult problem to solve up to now. Some traditional leak detection methods have such problems as high rate of false alarm or missing detection, low location estimate capability. For the problems given above, a method for oil pipeline leak detection based on distributed optical fiber sensor with special coating is presented. The fiber's coating interacts with hydrocarbon molecules in oil, which alters the refractive indexed of the coating. Therefore the light-guiding properties of the fiber are modified. Thus pipeline leak location can be determined by OTDR. Oil pipeline lead detection system is designed based on the principle. The system has some features like real time, multi-point detection at the same time and high location accuracy. In the end, some factors that probably influence detection are analyzed and primary improving actions are given.

Low temperature and UV curable sol-gel coatings for long lasting optical fiber biosensors

NASA Astrophysics Data System (ADS)

Otaduy, D.; Villar, A.; Gomez-Herrero, E.; Goitandia, A. M.; Gorritxategi, E.; Quintana, I.

2010-04-01

The use of optical fibers as sensing element is increasing in clinical, pharmaceutical and industrial applications. Excellent light delivery, long interaction length, low cost and ability not only to excite the target molecules but also to capture the emitted light from the targets are the hallmarks of optical fiber as biosensors. In biosensors based on fiber optics the interaction with the analyte can occur within an element of the optical fiber. One of the techniques for this kind of biosensors is to remove the fiber optic cladding and substitute it for biological coatings that will interact with the parameter to sensorize. The deposition of these layers can be made by sol-gel technology. The sol-gel technology is being increasingly used mainly due to the high versatility to tailor their optical features. Incorporation of suitable chemical and biochemical sensing agents have allowed determining pH, gases, and biochemical species, among others. Nonetheless, the relatively high processing temperatures and short lifetime values mean severe drawbacks for a successful exploitation of sol-gel based coated optical fibres. With regard to the latter, herein we present the design, preparation and characterization of novel sol-gel coated optical fibres. Low temperature and UV curable coating formulations were optimized to achieve a good adhesion and optical performance. The UV photopolymerizable formulation was comprised by glycidoxypropyltrimethoxysilane (GLYMO), Tetraethylorthosilicate (TEOS) and an initiator. While the thermoset coating was prepared by using 3-aminopropyltrimethoxysilane, GLYMO, and TEOS as main reagents. Both curable sol-gel coated fibres were analysed by FTIR, SEM and optical characterization. Furthermore, in the present work a new technique for silica cladding removal has been developed by ultra-short pulses laser processing, getting good dimensional accuracy and surface integrity.

Drug interactions with the dietary fiber Plantago ovata husk.

PubMed

Fernandez, Nelida; Lopez, Cristina; Díez, Raquel; Garcia, Juan J; Diez, Maria Jose; Sahagun, Ana; Sierra, Matilde

2012-11-01

Plantago ovata husk is a viscous water-soluble fiber obtained by milling the seed of Plantago ovata. The increased use of this compound for the treatment of diseases makes it necessary to know of its potential drug interactions. The present paper reviews the literature concerning interactions between drugs and the dietary fiber Plantago ovata husk. All publications which might describe interactions between the dietetic fiber Plantago ovata husk and other drugs were identified by searches using databases such as MEDLINE or EMBASE. Drug interactions have been the subject of numerous studies, but few of them have been carried out with dietary fiber and the results obtained have often been variable. The incidence and importance of interactions between fiber and drugs has increased due to a worldwide rise in the use of dietary fiber. Plantago ovata husk has the potential for producing both benefits and risks with both desirable and undesirable effects when coadministered with drugs. More clinical studies are justifiably needed to improve treatments and to better evaluate patient safety.

Laser-Bioplasma Interaction: Excitation and Suppression of the Brain Waves by the Multi-photon Pulsed-operated Fiber Lasers in the Ultraviolet Range of Frequencies

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander; IAPS-team Team

2017-10-01

The novel study of the laser excitation-suppression of the brain waves is proposed. It is based on the pulsed-operated multi-photon fiber-laser interaction with the brain parvalbumin (PV) neurons. The repetition frequency matches the low frequency brain waves (5-100 Hz); enabling the resonance-scanning of the wide range of the PV neurons (the generators of the brain wave activity). The tunable fiber laser frequencies are in the ultraviolet frequency range, thus enabling the monitoring of the PV neuron-DNA, within the 10s of milliseconds. In medicine, the method can be used as an ``instantaneous-on-off anesthetic.'' Supported by Nikola Tesla Labs, Stefan University.

Capturing and concentrating adenovirus using magnetic anionic nanobeads

PubMed Central

Sakudo, Akikazu; Baba, Koichi; Ikuta, Kazuyoshi

2016-01-01

We recently demonstrated how various enveloped viruses can be efficiently concentrated using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). However, the exact mechanism of interaction between the virus particles and anionic beads remains unclear. To further investigate whether these magnetic anionic beads specifically bind to the viral envelope, we examined their potential interaction with a nonenveloped virus (adenovirus). The beads were incubated with either adenovirus-infected cell culture medium or nasal aspirates from adenovirus-infected individuals and then separated from the supernatant by applying a magnetic field. After thoroughly washing the beads, adsorption of adenovirus was confirmed by a variety of techniques, including immunochromatography, polymerase chain reaction, Western blotting, and cell culture infection assays. These detection methods positively identified the hexon and penton capsid proteins of adenovirus along with the viral genome on the magnetic beads. Furthermore, various types of adenovirus including Types 5, 6, 11, 19, and 41 were captured using the magnetic bead procedure. Our bead capture method was also found to increase the sensitivity of viral detection. Adenovirus below the detectable limit for immunochromatography was efficiently concentrated using the magnetic bead procedure, allowing the virus to be successfully detected using this methodology. Moreover, these findings clearly demonstrate that a viral envelope is not required for binding to the anionic magnetic beads. Taken together, our results show that this capture procedure increases the sensitivity of detection of adenovirus and would, therefore, be a valuable tool for analyzing both clinical and experimental samples. PMID:27274228

Simulating Fiber Ordering and Aggregation In Shear Flow Using Dissipative Particle Dynamics

NASA Astrophysics Data System (ADS)

Stimatze, Justin T.

We have developed a mesoscale simulation of fiber aggregation in shear flow using LAMMPS and its implementation of dissipative particle dynamics. Understanding fiber aggregation in shear flow and flow-induced microstructural fiber networks is critical to our interest in high-performance composite materials. Dissipative particle dynamics enables the consideration of hydrodynamic interactions between fibers through the coarse-grained simulation of the matrix fluid. Correctly simulating hydrodynamic interactions and accounting for fluid forces on the microstructure is required to correctly model the shear-induced aggregation process. We are able to determine stresses, viscosity, and fiber forces while simulating the evolution of a model fiber system undergoing shear flow. Fiber-fiber contact interactions are approximated by combinations of common pairwise forces, allowing the exploration of interaction-influenced fiber behaviors such as aggregation and bundling. We are then able to quantify aggregate structure and effective volume fraction for a range of relevant system and fiber-fiber interaction parameters. Our simulations have demonstrated several aggregate types dependent on system parameters such as shear rate, short-range attractive forces, and a resistance to relative rotation while in contact. A resistance to relative rotation at fiber-fiber contact points has been found to strongly contribute to an increased angle between neighboring aggregated fibers and therefore an increase in average aggregate volume fraction. This increase in aggregate volume fraction is strongly correlated with a significant enhancement of system viscosity, leading us to hypothesize that controlling the resistance to relative rotation during manufacturing processes is important when optimizing for desired composite material characteristics.

Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

NASA Astrophysics Data System (ADS)

Nguyen Thi, T. B.; Yokoyama, A.; Ota, K.; Kodama, K.; Yamashita, K.; Isogai, Y.; Furuichi, K.; Nonomura, C.

2014-05-01

One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, which is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.

A novel fiber-free technique for brain activity imaging in multiple freely behaving mice

NASA Astrophysics Data System (ADS)

Inagaki, Shigenori; Agetsuma, Masakazu; Nagai, Takeharu

2018-02-01

Brain functions and related psychiatric disorders have been investigated by recording electrophysiological field potential. When recording it, a conventional method requires fiber-based apparatus connected to the brain, which however hampers the simultaneous measurement in multiple animals (e.g. by a tangle of fibers). Here, we propose a fiber-free recording technique in conjunction with a ratiometric bioluminescent voltage indicator. Our method allows investigation of electrophysiological filed potential dynamics in multiple freely behaving animals simultaneously over a long time period. Therefore, this fiber-free technique opens up the way to investigate a new mechanism of brain function that governs social behaviors and animal-to-animal interaction.

A mathematical model for the determination of forming tissue moduli in needled-nonwoven scaffolds.

PubMed

Soares, João S; Zhang, Will; Sacks, Michael S

2017-03-15

Formation of engineering tissues (ET) remains an important scientific area of investigation for both clinical translational and mechanobiological studies. Needled-nonwoven (NNW) scaffolds represent one of the most ubiquitous biomaterials based on their well-documented capacity to sustain tissue formation and the unique property of substantial construct stiffness amplification, the latter allowing for very sensitive determination of forming tissue modulus. Yet, their use in more fundamental studies is hampered by the lack of: (1) substantial understanding of the mechanics of the NNW scaffold itself under finite deformations and means to model the complex mechanical interactions between scaffold fibers, cells, and de novo tissue; and (2) rational models with reliable predictive capabilities describing their evolving mechanical properties and their response to mechanical stimulation. Our objective is to quantify the mechanical properties of the forming ET phase in constructs that utilize NNW scaffolds. We present herein a novel mathematical model to quantify their stiffness based on explicit considerations of the modulation of NNW scaffold fiber-fiber interactions and effective fiber stiffness by surrounding de novo ECM. Specifically, fibers in NNW scaffolds are effectively stiffer than if acting alone due to extensive fiber-fiber cross-over points that impart changes in fiber geometry, particularly crimp wavelength and amplitude. Fiber-fiber interactions in NNW scaffolds also play significant role in the bulk anisotropy of the material, mainly due to fiber buckling and large translational out-of-plane displacements occurring to fibers undergoing contraction. To calibrate the model parameters, we mechanically tested impregnated NNW scaffolds with polyacrylamide (PAM) gels with a wide range of moduli with values chosen to mimic the effects of surrounding tissues on the scaffold fiber network. Results indicated a high degree of model fidelity over a wide range of planar strains. Lastly, we illustrated the impact of our modeling approach quantifying the stiffness of engineered ECM after in vitro incubation and early stages of in vivo implantation obtained in a concurrent study of engineered tissue pulmonary valves in an ovine model. Regenerative medicine has the potential to fully restore diseased tissues or entire organs with engineered tissues. Needled-nonwoven scaffolds can be employed to serve as the support for their growth. However, there is a lack of understanding of the mechanics of these materials and their interactions with the forming tissues. We developed a mathematical model for these scaffold-tissue composites to quantify the mechanical properties of the forming tissues. Firstly, these measurements are pivotal to achieve functional requirements for tissue engineering implants; however, the theoretical development yielded critical insight into particular mechanisms and behaviors of these scaffolds that were not possible to conjecture without the insight given by modeling, let alone describe or foresee a priori. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanadi, A.R.; Caulfield, D.F.; Jacobson, R.E.

Kenaf (Hibiscus Cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In our experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50 % by volume (39 % by volume) of kenaf-PP composites compares favorablymore » with a 40 % by weight of glass fiber-PP injection molded composites, These results suggest that kenaf fibers are a viable alternative to inorganic/mineral based reinforcing fibers as long as the right processing conditions are used and for applications where the higher water absorption is not critical.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanadi, A.R.; Caulfield, D.F.; Jacobson, R.E.

Kenaf (Hibiscus cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In these experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the nonpolar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50% by weight (39% by volume) of kenaf-PP composite compare favorably with amore » 40% by weight of glass fiber-PP injection-molded composite. These results suggest that kenaf fibers are a viable alternative to inorganic/mineral-based reinforcing fibers as long as the right processing conditions are used and they are used in applications where the higher water absorption is not critical.« less

SWCNTs-based nanocomposites as sensitive coatings for advanced fiber optic chemical nanosensors

NASA Astrophysics Data System (ADS)

Consales, M.; Crescitelli, A.; Penza, M.; Aversa, P.; Giordano, M.; Cutolo, A.; Cusano, A.

2008-04-01

In this work, the feasibility of exploiting novel Cadmium Arachidate (CdA)/single-walled carbon nanotubes (SWCNTs) based composites as sensitive coatings for the development of robust and high performances optoelectronic chemosensors able to work in liquid environments has been investigated and proved. Here, nano-composite sensing layers have been transferred upon the distal end of standard optical fibers by the Langmuir-Blodgett (LB) technique. Reflectance measurements have been carried out to monitor ppm concentration of chemicals in water through the changes in the optical and geometrical features of the sensing overlay induced by the interaction with the analyte molecules. Preliminary experimental results evidence that such nanoscale coatings integrated with the optical fiber technology offers great potentialities for the room temperature detection of chemical traces in water and lead to significant improvements of the traditional fiber optic sensors based on SWCNTs layers.

Simultaneous transmission of accurate time, stable frequency, data, and sensor system over one fiber with ITU 100 GHz grid

NASA Astrophysics Data System (ADS)

Horvath, Tomas; Munster, Petr; Vojtech, Josef; Velc, Radek; Oujezsky, Vaclav

2018-01-01

Optical fiber is the most used medium for current telecommunication networks. Besides data transmissions, special advanced applications like accurate time or stable frequency transmissions are more common, especially in research and education networks. On the other hand, new applications like distributed sensing are in ISP's interest because e.g. such sensing allows new service: protection of fiber infrastructure. Transmission of all applications in a single fiber can be very cost efficient but it is necessary to evaluate possible interaction before real application and deploying the service, especially if standard 100 GHz grid is considered. We performed laboratory measurement of simultaneous transmission of 100 G data based on DP-QPSK modulation format, accurate time, stable frequency and sensing system based on phase sensitive OTDR through two types of optical fibers, G.655 and G.653. These fibers are less common than G.652 fiber but thanks to their slightly higher nonlinear character, there are suitable for simulation of the worst case which can arise in a real network.

Striated Acto-Myosin Fibers Can Reorganize and Register in Response to Elastic Interactions with the Matrix

PubMed Central

Friedrich, Benjamin M.; Buxboim, Amnon; Discher, Dennis E.; Safran, Samuel A.

2011-01-01

The remarkable striation of muscle has fascinated many for centuries. In developing muscle cells, as well as in many adherent, nonmuscle cell types, striated, stress fiberlike structures with sarcomere-periodicity tend to register: Based on several studies, neighboring, parallel fibers at the basal membrane of cultured cells establish registry of their respective periodic sarcomeric architecture, but, to our knowledge, the mechanism has not yet been identified. Here, we propose for cells plated on an elastic substrate or adhered to a neighboring cell, that acto-myosin contractility in striated fibers close to the basal membrane induces substrate strain that gives rise to an elastic interaction between neighboring striated fibers, which in turn favors interfiber registry. Our physical theory predicts a dependence of interfiber registry on externally controllable elastic properties of the substrate. In developing muscle cells, registry of striated fibers (premyofibrils and nascent myofibrils) has been suggested as one major pathway of myofibrillogenesis, where it precedes the fusion of neighboring fibers. This suggests a mechanical basis for the optimal myofibrillogenesis on muscle-mimetic elastic substrates that was recently observed by several groups in cultures of mouse-, human-, and chick-derived muscle cells. PMID:21641316

Evaluation of Aerogel Clad Optical Fibers Final Report CRADA No. TSB-1448-97

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maitland, Duncan; Droege, M. W.

Fiber-optic based sensors will be needed for in situ monitoring of degradation products in various components of nuclear weapons. These sensors typically consist of a transducer located at the measurement site whose optical properties are modulated by interaction with the targeted degradation product. The interrogating light source and the detector for determining sensor response are located remotely. These two subsystems are connected by fiber optic cables. LLNL has developed a new technology, aerogel clad optical fibers, that have the advantage of accepting incident rays over a much wider angular range than normal glass clad fibers. These fibers are also capablemore » of transmitting light more efficiently. These advantages can lead to a factor of 2-4 improvement in sensitivity and detection limit.« less

Core-Shell Composite Fibers for High-Performance Flexible Supercapacitor Electrodes.

PubMed

Lu, Xiaoyan; Shen, Chen; Zhang, Zeyang; Barrios, Elizabeth; Zhai, Lei

2018-01-31

Core-shell nanofibers containing poly(acrylic acid) (PAA) and manganese oxide nanoparticles as the core and polypyrrole (PPy) as the shell were fabricated through electrospinning the solution of PAA and manganese ions (PAA/Mn 2+ ). The obtained nanofibers were stabilized by Fe 3+ through the interaction between Fe 3+ ions and carboxylate groups. Subsequent oxidation of Mn 2+ by KMnO 4 produced uniform manganese dioxide (MnO 2 ) nanoparticles in the fibers. A PPy shell was created on the fibers by immersing the fibers in a pyrrole solution where the Fe 3+ ions in the fiber polymerized the pyrrole on the fiber surfaces. In the MnO 2 @PAA/PPy core-shell composite fibers, MnO 2 nanoparticles function as high-capacity materials, while the PPy shell prevents the loss of MnO 2 during the charge/discharge process. Such a unique structure makes the composite fibers efficient electrode materials for supercapacitors. The gravimetric specific capacity of the MnO 2 @PAA/PPy core-shell composite fibers was 564 F/g based on cyclic voltammetry curves at 10 mV/s and 580 F/g based on galvanostatic charge/discharge studies at 5 A/g. The MnO 2 @PAA/PPy core-shell composite fibers also present stable cycling performance with 100% capacitance retention after 5000 cycles.

Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen Thi, T. B., E-mail: thanhbinh.skku@gmail.com, E-mail: yokoyama@kit.ac.jp; Yokoyama, A., E-mail: thanhbinh.skku@gmail.com, E-mail: yokoyama@kit.ac.jp; Ota, K., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp

2014-05-15

One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, whichmore » is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.« less

In vitro study of improved wound-healing effect of bioactive borate-based glass nano-/micro-fibers.

PubMed

Yang, Qingbo; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

2015-10-01

Because of the promising wound-healing capability, bioactive glasses have been considered as one of the next generation hard- and soft-tissue regeneration materials. The lack of understanding of the substantial mechanisms, however, indicates the need for further study on cell-glass interactions to better interpret the rehabilitation capability. In the present work, three bioactive glass nano-/micro-fibers, silicate-based 45S5, borate-based 13-93B3 and 1605 (additionally doped with copper oxide and zinc oxide), were firstly compared for their in vitro soaking/conversion rate. The results of elemental monitoring and electron microscopic characterization demonstrated that quicker ion releasing and glass conversion occurred in borate-based fibers than that of silicate-based one. This result was also reflected by the formation speed of hydroxyapatite (HA). This process was further correlated with original boron content and surrounding rheological condition. We showed that an optimal fiber pre-soaking time (or an ideal dynamic flow rate) should exist to stimulate the best cell proliferation and migration ability. Moreover, 13-93B3 and 1605 fibers showed different glass conversion and biocompatibility properties as well, indicating that trace amount variation in composition can also influence fiber's bioactivity. In sum, our in vitro rheological module closely simulated in vivo niche environment and proved a potentially improved wound-healing effect by borate-based glass fibers, and the results shall cast light on future improvement in bioactive glass fabrication. Copyright © 2015 Elsevier B.V. All rights reserved.

Low-loss saturable absorbers based on tapered fibers embedded in carbon nanotube/polymer composites

NASA Astrophysics Data System (ADS)

Martinez, Amos; Al Araimi, Mohammed; Dmitriev, Artemiy; Lutsyk, Petro; Li, Shen; Mou, Chengbo; Rozhin, Alexey; Sumetsky, Misha; Turitsyn, Sergei

2017-12-01

The emergence of low-dimensional materials has opened new opportunities in the fabrication of compact nonlinear photonic devices. Single-walled carbon nanotubes were among the first of those materials to attract the attention of the photonics community owing to their high third order susceptibility, broadband operation, and ultrafast response. Saturable absorption, in particular, has become a widespread application for nanotubes in the mode-locking of a fiber laser where they are used as nonlinear passive amplitude modulators to initiate pulsed operation. Numerous approaches have been proposed for the integration of nanotubes in fiber systems; these can be divided into those that rely on direct interaction (where the nanotubes are sandwiched between fiber connectors) and those that rely on lateral interaction with the evanescence field of the propagating wave. Tapered fibers, in particular, offer excellent flexibility to adjust the nonlinearity of nanotube-based devices but suffer from high losses (typically exceeding 50%) and poor saturable to non-saturable absorption ratios (typically above 1:5). In this paper, we propose a method to fabricate carbon nanotube saturable absorbers with controllable saturation power, low-losses (as low as 15%), and large saturable to non-saturable loss ratios approaching 1:1. This is achieved by optimizing the procedure of embedding tapered fibers in low-refractive index polymers. In addition, this study sheds light in the operation of these devices, highlighting a trade-off between losses and saturation power and providing guidelines for the design of saturable absorbers according to their application.

Femtomolar Detection by Nanocoated Fiber Label-Free Biosensors.

PubMed

Chiavaioli, Francesco; Zubiate, Pablo; Del Villar, Ignacio; Zamarreño, Carlos R; Giannetti, Ambra; Tombelli, Sara; Trono, Cosimo; Arregui, Francisco J; Matias, Ignacio R; Baldini, Francesco

2018-05-25

The advent of optical fiber-based biosensors combined with that of nanotechnologies has provided an opportunity for developing in situ, portable, lightweight, versatile, and high-performance optical sensing platforms. We report on the generation of lossy mode resonances by the deposition of nanometer-thick metal oxide films on optical fibers, which makes it possible to measure precisely and accurately the changes in optical properties of the fiber-surrounding medium with very high sensitivity compared to other technology platforms, such as long period gratings or surface plasmon resonances, the gold standard in label-free and real-time biomolecular interaction analysis. This property, combined with the application of specialty structures such as D-shaped fibers, permits enhancing the light-matter interaction. SEM and TEM imaging together with X-EDS tool have been utilized to characterize the two films used, i.e., indium tin oxide and tin dioxide. Moreover, the experimental transmission spectra obtained after the deposition of the nanocoatings have been numerically corroborated by means of wave propagation methods. With the use of a conventional wavelength interrogation system and ad hoc developed microfluidics, the shift of the lossy mode resonance can be reliably recorded in response to very low analyte concentrations. Repeated experiments confirm a big leap in performance thanks to the capability to detect femtomolar concentrations in human serum, improving the detection limit by 3 orders of magnitude when compared with other fiber-based configurations. The biosensor has been regenerated several times by injecting sodium dodecyl sulfate, which proves the capability of sensor to be reused.

On the design of composite protein-quantum dot biomaterials via self-assembly.

PubMed

Majithia, Ravish; Patterson, Jan; Bondos, Sarah E; Meissner, Kenith E

2011-10-10

Incorporation of nanoparticles during the hierarchical self-assembly of protein-based materials can impart function to the resulting composite materials. Herein we demonstrate that the structure and nanoparticle distribution of composite fibers are sensitive to the method of nanoparticle addition and the physicochemical properties of both the nanoparticle and the protein. Our model system consists of a recombinant enhanced green fluorescent protein-Ultrabithorax (EGFP-Ubx) fusion protein and luminescent CdSe-ZnS core-shell quantum dots (QDs), allowing us to optically assess the distribution of both the protein and nanoparticle components within the composite material. Although QDs favorably interact with EGFP-Ubx monomers, the relatively rough surface morphology of composite fibers suggests EGFP-Ubx-QD conjugates impact self-assembly. Indeed, QDs templated onto EGFP-Ubx film post-self-assembly can be subsequently drawn into smooth composite fibers. Additionally, the QD surface charge impacts QD distribution within the composite material, indicating that surface charge plays an important role in self-assembly. QDs with either positively or negatively charged coatings significantly enhance fiber extensibility. Conversely, QDs coated with hydrophobic moieties and suspended in toluene produce composite fibers with a heterogeneous distribution of QDs and severely altered fiber morphology, indicating that toluene severely disrupts Ubx self-assembly. Understanding factors that impact the protein-nanoparticle interaction enables manipulation of the structure and mechanical properties of composite materials. Since proteins interact with nanoparticle surface coatings, these results should be applicable to other types of nanoparticles with similar chemical groups on the surface.

Associations between dietary fiber and colorectal polyp risk differ by polyp type and smoking status.

PubMed

Fu, Zhenming; Shrubsole, Martha J; Smalley, Walter E; Ness, Reid M; Zheng, Wei

2014-05-01

The association of dietary fiber intake with colorectal cancer risk is established. However, the association may differ between cigarette smokers and nonsmokers. We evaluated this hypothesis in a large colonoscopy-based case-control study. Dietary fiber intakes were estimated by self-administered food frequency questionnaire. Unconditional logistic regression analysis was used to estimate ORs and 95% CIs with adjustment for potential confounders. Analysis also was stratified by cigarette smoking and sex. High dietary fiber intake was associated with reduced risk of colorectal polyps (P-trend = 0.003). This association was found to be stronger among cigarette smokers (P-trend = 0.006) than nonsmokers (P-trend = 0.21), although the test for multiplicative interaction was not statistically significant (P = 0.11). This pattern of association was more evident for high-risk adenomatous polyps (ADs), defined as advanced or multiple ADs (P-interaction smoking and dietary fiber intake = 0.09). Among cigarette smokers who smoked ≥23 y, a 38% reduced risk of high-risk ADs was found to be associated with high intake of dietary fiber compared with those in the lowest quartile fiber intake group (P-trend = 0.004). No inverse association with dietary fiber intake was observed for low-risk ADs, defined as single nonadvanced ADs. Cigarette smoking may modify the association of dietary fiber intake with the risk of colorectal polyps, especially high-risk ADs, a well-established precursor of colorectal cancer.

Adenovirus Type 5 Viral Particles Pseudotyped with Mutagenized Fiber Proteins Show Diminished Infectivity of Coxsackie B-Adenovirus Receptor-Bearing Cells

PubMed Central

Jakubczak, John L.; Rollence, Michele L.; Stewart, David A.; Jafari, Jonathon D.; Von Seggern, Dan J.; Nemerow, Glen R.; Stevenson, Susan C.; Hallenbeck, Paul L.

2001-01-01

A major limitation of adenovirus type 5 (Ad5)-based gene therapy, the inability to target therapeutic genes to selected cell types, is attributable to the natural tropism of the virus for the widely expressed coxsackievirus-adenovirus receptor (CAR) protein. Modifications of the Ad5 fiber knob domain have been shown to alter the tropism of the virus. We have developed a novel system to rapidly evaluate the function of modified fiber proteins in their most relevant context, the adenoviral capsid. This transient transfection/infection system combines transfection of cells with plasmids that express high levels of the modified fiber protein and infection with Ad5.βgal.ΔF, an E1-, E3-, and fiber-deleted adenoviral vector encoding β-galactosidase. We have used this system to test the adenoviral transduction efficiency mediated by a panel of fiber protein mutants that were proposed to influence CAR interaction. A series of amino acid modifications were incorporated via mutagenesis into the fiber expression plasmid, and the resulting fiber proteins were subsequently incorporated onto adenoviral particles. Mutations located in the fiber knob AB and CD loops demonstrated the greatest reduction in fiber-mediated gene transfer in HeLa cells. We also observed effects on transduction efficiency with mutations in the FG loop, indicating that the binding site may extend to the adjacent monomer in the fiber trimer and in the HI loop. These studies support the concept that modification of the fiber knob domain to diminish or ablate CAR interaction should result in a detargeted adenoviral vector that can be combined simultaneously with novel ligands for the development of a systemically administered, targeted adenoviral vector. PMID:11222722

Modeling of Distributed Sensing of Elastic Waves by Fiber-Optic Interferometry

PubMed Central

Agbodjan Prince, Just; Kohl, Franz; Sauter, Thilo

2016-01-01

This paper deals with the transduction of strain accompanying elastic waves in solids by firmly attached optical fibers. Stretching sections of optical fibers changes the time required by guided light to pass such sections. Exploiting interferometric techniques, highly sensitive fiber-optic strain transducers are feasible based on this fiber-intrinsic effect. The impact on the actual strain conversion of the fiber segment’s shape and size, as well as its inclination to the elastic wavefront is studied. FEM analyses show that severe distortions of the interferometric response occur when the attached fiber length spans a noticeable fraction of the elastic wavelength. Analytical models of strain transduction are presented for typical transducer shapes. They are used to compute input-output relationships for the transduction of narrow-band strain pulses as a function of the mechanical wavelength. The described approach applies to many transducers depending on the distributed interaction with the investigated object. PMID:27608021

Modeling of Distributed Sensing of Elastic Waves by Fiber-Optic Interferometry.

PubMed

Agbodjan Prince, Just; Kohl, Franz; Sauter, Thilo

2016-09-06

This paper deals with the transduction of strain accompanying elastic waves in solids by firmly attached optical fibers. Stretching sections of optical fibers changes the time required by guided light to pass such sections. Exploiting interferometric techniques, highly sensitive fiber-optic strain transducers are feasible based on this fiber-intrinsic effect. The impact on the actual strain conversion of the fiber segment's shape and size, as well as its inclination to the elastic wavefront is studied. FEM analyses show that severe distortions of the interferometric response occur when the attached fiber length spans a noticeable fraction of the elastic wavelength. Analytical models of strain transduction are presented for typical transducer shapes. They are used to compute input-output relationships for the transduction of narrow-band strain pulses as a function of the mechanical wavelength. The described approach applies to many transducers depending on the distributed interaction with the investigated object.

Carbon nanotube-based mode-locked wavelength-switchable fiber laser via net gain cross section alteration

NASA Astrophysics Data System (ADS)

Latif, A. A.; Mohamad, H.; Abu Bakar, M. H.; Muhammad, F. D.; Mahdi, M. A.

2016-02-01

We have proposed and demonstrated a carbon nanotube-based mode-locked erbium-doped fiber laser with switchable wavelength in the C-band wavelength region by varying the net gain cross section of erbium. The carbon nanotube is coated on a tapered fiber to form the saturable absorber for the purpose of mode-locking by exploiting the concept of evanescent field interaction on the tapered fiber with the carbon nanotube in a ring cavity configuration. The propagation loss is adjusted by inducing macrobend losses of the optical fiber in the cavity through a fiber spooling technique. Since the spooling radius can be gradually adjusted to achieve continuous tuning of attenuation, this passive tuning approach can be an alternative to optical tunable attenuator, with freedom of external device integration into the laser cavity. Based on this alteration, the net gain cross section of the laser system can be tailored to three different lasing wavelength ranges; 1533, 1560 nm and both (1533 and 1560 nm) with the minimum pulse duration of 734 fs. The proposed design is simple and stable with high beam quality and good reliability for multiple applications.

Sidelobe suppression in all-fiber acousto-optic tunable filter using torsional acoustic wave.

PubMed

Lee, Kwang Jo; Hwang, In-Kag; Park, Hyun Chul; Kim, Byoung Yoon

2010-06-07

We propose two techniques to suppress intrinsic sidelobe spectra in all-fiber acousto-optic tunable filter using torsional acoustic wave. The techniques are based on either double-pass filter configuration or axial tailoring of mode coupling strength along an acousto-optic interaction region in a highly birefringent optical fiber. The sidelobe peak in the filter spectrum is experimentally suppressed from -8.3 dB to -16.4 dB by employing double-pass configuration. Axial modulation of acousto-optic coupling strength is proposed using axial variation of the fiber diameter, and the simulation results show that the maximum side peak of -9.3 dB can be reduced to -22.2dB. We also discuss the possibility of further spectral shaping of the filter based on the axial tailoring of acousto-optic coupling strength.

Evanescent Wave Absorption Based Fiber Sensor for Measuring Glucose Solution Concentration

NASA Astrophysics Data System (ADS)

Marzuki, Ahmad; Candra Pratiwi, Arni; Suryanti, Venty

2018-03-01

An optical fiber sensor based on evanescent wave absorption designed for measuring glucose solution consentration was proposed. The sensor was made to detect absorbance of various wavelength in the glucose solution. The sensing element was fabricated by side polishing of multimode polymer optical fiber to form a D-shape. The sensing element was immersed in different concentration of glucoce solution. As light propagated through the optical fiber, the evanescent wave interacted with the glucose solution. Light was absorbed by the glucose solution. The larger concentration the glucose solution has, the more the evanescent wave was absorbed in particular wavelenght. Here in this paper, light absorbtion as function of glucose concentration was measured as function of wavelength (the color of LED). We have shown that the proposed sensor can demonstrated an increase of light absorption as function of glucose concentration.

In-fiber Fabry-Perot refractometer assisted by a long-period grating.

PubMed

Mosquera, L; Sáez-Rodriguez, D; Cruz, J L; Andrés, M V

2010-02-15

We present an optical fiber refractometer based on a Fabry-Perot interferometer defined by two fiber Bragg gratings and an intracavity long-period grating that makes the light confined in the resonator interact with the surrounding medium. The external refractive index is monitored by the resonant frequencies of the Fabry-Perot interferometer, which can be measured either in transmission or in reflection. In this first experiment, wavelength shifts measured with a resolution of 0.1 pm have allowed one to establish a refractive index detection limit of 2.1x10(-5).

Genome-wide identification and characterization of TCP transcription factor genes in upland cotton (Gossypium hirsutum).

PubMed

Li, Wen; Li, Deng-Di; Han, Li-Hong; Tao, Miao; Hu, Qian-Qian; Wu, Wen-Ying; Zhang, Jing-Bo; Li, Xue-Bao; Huang, Geng-Qing

2017-08-31

TCP proteins are plant-specific transcription factors (TFs), and perform a variety of physiological functions in plant growth and development. In this study, 74 non-redundant TCP genes were identified in upland cotton (Gossypium hirsutum L.) genome. Cotton TCP family can be classified into two classes (class I and class II) that can be further divided into 11 types (groups) based on their motif composition. Quantitative RT-PCR analysis indicated that GhTCPs display different expression patterns in cotton tissues. The majority of these genes are preferentially or specifically expressed in cotton leaves, while some GhTCP genes are highly expressed in initiating fibers and/or elongating fibers of cotton. Yeast two-hybrid results indicated that GhTCPs can interact with each other to form homodimers or heterodimers. In addition, GhTCP14a and GhTCP22 can interact with some transcription factors which are involved in fiber development. These results lay solid foundation for further study on the functions of TCP genes during cotton fiber development.

Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax

NASA Astrophysics Data System (ADS)

Wróbel-Kwiatkowska, Magdalena; Żuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

2009-07-01

The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds.

Guidance of neurite outgrowth on aligned electrospun polypyrrole/poly(styrene-beta-isobutylene-beta-styrene) fiber platforms.

PubMed

Liu, Xiao; Chen, Jun; Gilmore, Kerry J; Higgins, Michael J; Liu, Yong; Wallace, Gordon G

2010-09-15

The purpose of this work was to investigate the potential biomedical application of novel aligned electrospun polypyrrole (PPy)/poly(styrene-beta-isobutylene-beta-styrene) (SIBS) fibers. After successfully aligning the electroactive PPy/SIBS fibers based on our modified electrospinning method, we demonstrated that neurite outgrowth from PC12 cells could be highly orientated parallel to the aligned PPy/SIBS fibers. Physical interactions between the nerve cells and PPy/SIBS fibers through filopodia "sensing" were observed using atomic force microscopy. These observations indicate a role of contact guidance as a mechanism for the observed alignment. This work highlights the capacity for electroactive PPy/SIBS fibers to support and guide nerve cell differentiation through topographic cues, which is a highly desirable characteristic in medical implants for neurological applications. (c) 2010 Wiley Periodicals, Inc.

Electron tomography and nano-diffraction enabling the investigation of individual magnetic nanoparticles inside fibers of MR visible implants

NASA Astrophysics Data System (ADS)

Slabu, I.; Wirch, N.; Caumanns, T.; Theissmann, R.; Krüger, M.; Schmitz-Rode, T.; Weirich, T. E.

2017-08-01

Superparamagnetic iron oxide nanoparticles (SPIONPs) incorporated into the base material of implants are used as contrast agents in magnetic resonance imaging for the delineation of the implants from the surrounding tissue. However, the delineation quality is strongly related to the structural characteristics of the incorporated SPIONPs and their interparticle interaction as well as their interaction with the polymer matrix of the implant. Consequently, a profound knowledge of the formation of aggregates inside the polymer matrix, which are responsible for strong interparticle interactions, and of their structural characteristics, is required for controlling the magnetic resonance image quality of the implants. In this work, transmission electron microscopy methods such as electron tomography and nano-electron diffraction were used to depict SPIONP aggregates inside the melt-spin polyvinylidene fluoride fibers used for the assembly of implants and to determine the crystal structure of individual nanocrystals inside these aggregates, respectively. Using these techniques it was possible for the first time to characterize the aggregates inside the fibers of implants and to validate the magnetization measurements that have been previously used to assess the interaction phenomena inside the fibers of implants. With electron tomography, inhomogeneously sized distributed aggregates were delineated and 3D models of these aggregates were constructed. Furthermore, the distribution of the aggregates inside the fibers was verified by means of magnetic force microscopy. With nano-diffraction measurements, the SPIONP crystal structure inside the fibers of the implant could not be clearly assigned to that of magnetite (Fe3O4) or maghemite (γ-Fe2O3). Therefore, additional electron energy loss spectroscopy measurements were performed, which revealed the presence of both phases of Fe3O4 and γ-Fe2O3, probably caused by oxidation processes during the manufacture of the fibers by melt-spinning.

Spatial Soliton Interactions for Photonic Switching. Part I

DTIC Science & Technology

2000-03-07

technique , a fully vectorial, first-order nonlinear wave equation that consistently includes terms two -orders beyond the slowly-varying amplitude , slowly...by using two tunable mode-locked Er-doped fiber lasers ," in Conference on Optical Fiber Communications, OSA Technical Digest Series, vol. 4, 1994...instead, based on optical logic gates. In addition, optical logic could be used for contention resolution, real-time encryption /decryption, and other

Surface decoration of polyimide fiber with carbon nanotubes and its application for mechanical enhancement of phosphoric acid-based geopolymers

NASA Astrophysics Data System (ADS)

Yang, Tao; Han, Enlin; Wang, Xiaodong; Wu, Dezhen

2017-09-01

A new methodology to decorate the surface of polyimide (PI) fiber with carbon nanotubes (CNTs) has been developed in this study. This surface decoration was carried out through a surface alkali treatment, a carboxylation modification, surface functionalization with acyl chloride groups and then with amino groups, and a surface graft of CNTs onto PI fiber. Fourier-transform infrared and X-ray photoelectron spectroscopic characterizations confirmed that CNTs were chemically grafted onto the surface of PI fiber, and scanning electron microscopic observation demonstrated the fiber surface was uniformly and densely covered with CNTs. The surface energy and wettability of PI fiber were improved in the presence of CNTs on the fiber surface, which made a contribution to enhance the interfacial adhesion of PI fiber with other inorganic matrices when used as a reinforcing fiber. The application of CNTs-decorated PI fiber for the reinforcement of phosphoric acid-based geopolymers was investigated, and the results indicated that the geopolymeric composites gained a noticeable reinforcement. Compared to unreinforced geopolymer, the geopolymeric composites achieved a remarkable increase in compressive strength by 120% and in flexural strength by 283%. Fractography investigation demonstrated that the interaction adhesion between the fibers and matrix was enhanced due to the surface decoration of PI fiber with CNTs, which contributed to an improvement in fracture-energy dissipation by fiber pullout and fiber debonding from the matrix. As a result, a significant reinforcement effect on geopolymeric composites was achieved through a fiber-bridging mechanism. This study provided an effective methodology to improve the interracial bonding force for PI fiber and also proves a highly efficient application of CNTs-decorated PI fiber for the mechanical enhancement of geopolymeric composites.

Detection of unamplified genomic DNA by a PNA-based microstructured optical fiber (MOF) Bragg-grating optofluidic system.

PubMed

Bertucci, Alessandro; Manicardi, Alex; Candiani, Alessandro; Giannetti, Sara; Cucinotta, Annamaria; Spoto, Giuseppe; Konstantaki, Maria; Pissadakis, Stavros; Selleri, Stefano; Corradini, Roberto

2015-01-15

Microstructured optical fibers containing microchannels and Bragg grating inscribed were internally functionalized with a peptide nucleic acid (PNA) probe specific for a gene tract of the genetically modified Roundup Ready soy. These fibers were used as an optofluidic device for the detection of DNA by measuring the shift in the wavelength of the reflected IR light. Enhancement of optical read-out was obtained using streptavidin coated gold-nanoparticles interacting with the genomic DNA captured in the fiber channels (0%, 0.1%, 1% and 10% RR-Soy), enabling to achieve statistically significant, label-free, and amplification-free detection of target DNA in low concentrations, low percentages, and very low sample volumes. Computer simulations of the fiber optics based on the finite element method (FEM) were consistent with the formation of a layer of organic material with an average thickness of 39 nm for the highest percentage (10% RR soy) analysed. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical resonance analysis of reflected long period fiber gratings with metal film overlay

NASA Astrophysics Data System (ADS)

Zhang, Guiju; Cao, Bing; Wang, Chinua; Zhao, Minfu

2008-11-01

We present the experimental results of a novel single-ended reflecting surface plasma resonance (SPR) based long period fiber grating (LPFG) sensor. A long period fiber grating sensing device is properly designed and fabricated with a pulsed CO2 laser writing system. Different nm-thick thin metal films are deposited on the fiber cladding and the fiber end facet for the excitation of surface plasma waves (SPWs) and the reflection of the transmission spectrum of the LPFG with doubled interaction between metal-dielectric interfaces of the fiber to enhance the SPW of the all-fiber SPR-LPFG sensing system. Different thin metal films with different thicknesses are investigated. The effect of the excited SPW transmission along the fiber cladding-metal interface with silver and aluminum films is observed. It is found that different thicknesses of the metal overlay show different resonant behaviors in terms of resonance peak situation, bandwidth and energy loss. Within a certain range, thinner metal film shows narrower bandwidth and deeper peak loss.

The Secretory Response of Rat Peritoneal Mast Cells on Exposure to Mineral Fibers.

PubMed

Borelli, Violetta; Trevisan, Elisa; Francesca, Vita; Zabucchi, Giuliano

2018-01-10

Exposure to mineral fibers is of substantial relevance to human health. A key event in exposure is the interaction with inflammatory cells and the subsequent generation of pro-inflammatory factors. Mast cells (MCs) have been shown to interact with titanium oxide (TiO₂) and asbestos fibers. In this study, we compared the response of rat peritoneal MCs challenged with the asbestos crocidolite and nanowires of TiO₂ to that induced by wollastonite employed as a control fiber. Rat peritoneal MCs (RPMCs), isolated from peritoneal lavage, were incubated in the presence of mineral fibers. The quantities of secreted enzymes were evaluated together with the activity of fiber-associated enzymes. The ultrastructural morphology of fiber-interacting RPMCs was analyzed with electron microscopy. Asbestos and TiO₂ stimulate MC secretion. Secreted enzymes bind to fibers and exhibit higher activity. TiO₂ and wollastonite bind and improve enzyme activity, but to a lesser degree than crocidolite. (1) Mineral fibers are able to stimulate the mast cell secretory process by both active (during membrane interaction) and/or passive (during membrane penetration) interaction; (2) fibers can be found to be associated with secreted enzymes-this process appears to create long-lasting pro-inflammatory environments and may represent the active contribution of MCs in maintaining the inflammatory process; (3) MCs and their enzymes should be considered as a therapeutic target in the pathogenesis of asbestos-induced lung inflammation; and (4) MCs can contribute to the inflammatory effect associated with selected engineered nanomaterials, such as TiO₂ nanoparticles.

Contraction of electroweak model and neutrino

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gromov, N. A., E-mail: gromov@dm.komisc.ru

The electroweak model, which lepton sector correspond to the contracted gauge group SU(2; j) Multiplication-Sign U(1), j {yields} 0, whereas boson and quark sectors are standard one, is suggested. The field space of the model is fibered under contraction in such a way that neutrino fields are in the fiber and all other fields are in the base. Properties of the fibered field space are understood in context of semi-Riemannian geometry. This model describes in a natural manner why neutrinos so rarely interact with matter, as well as why neutrino cross section increase with the energy. Dimensionfull parameter of themore » model is interpreted as neutrino energy. Dimensionless contraction parameter j at low energy is connected with the Fermi constant of weak interactions and is approximated as j{sup 2} Almost-Equal-To 10{sup -5}.« less

New insights into chromatin folding and dynamics from multi-scale modeling

NASA Astrophysics Data System (ADS)

Olson, Wilma

The dynamic organization of chromatin plays an essential role in the regulation of gene expression and in other fundamental cellular processes. The underlying physical basis of these activities lies in the sequential positioning, chemical composition, and intermolecular interactions of the nucleosomes-the familiar assemblies of roughly 150 DNA base pairs and eight histone proteins-found on chromatin fibers. We have developed a mesoscale model of short nucleosomal arrays and a computational framework that make it possible to incorporate detailed structural features of DNA and histones in simulations of short chromatin constructs with 3-25 evenly spaced nucleosomes. The correspondence between the predicted and observed effects of nucleosome composition, spacing, and numbers on long-range communication between regulatory proteins bound to the ends of designed nucleosome arrays lends credence to the model and to the molecular insights gleaned from the simulated structures. We have extracted effective nucleosome-nucleosome potentials from the mesoscale simulations and introduced the potentials in a larger scale computational treatment of regularly repeating chromatin fibers. Our results reveal a remarkable influence of nucleosome spacing on chromatin flexibility. Small changes in the length of the DNA fragments linking successive nucleosomes introduce marked changes in the local interactions of the nucleosomes and in the spatial configurations of the fiber as a whole. The changes in nucleosome positioning influence the statistical properties of longer chromatin constructs with 100-10,000 nucleosomes. We are investigating the extent to which the `local' interactions of regularly spaced nucleosomes contribute to the corresponding interactions in chains with mixed spacings as a step toward the treatment of fibers with nucleosomes positioned at the sites mapped at base-pair resolution on genomic sequences. Support of the work by USPHS R01 GM 34809 is gratefully acknowledged.

Fiber optic gas detection system for health monitoring of oil-filled transformer

NASA Astrophysics Data System (ADS)

Ho, H. L.; Ju, J.; Jin, W.

2009-10-01

This paper reports the development of a fiber-optic gas detection system capable of detecting three types of dissolved fault gases in oil-filled power transformers or equipment. The system is based on absorption spectroscopy and the target gases include acetylene (C2H2), methane (CH4) and ethylene (C2H4). Low-cost multi-pass sensor heads using fiber coupled micro-optic cells are employed for which the interaction length is up to 4m. Also, reference gas cells made of photonic bandgap (PBG) fiber are implemented. The minimum detectable gas concentrations for methane, acetylene and ethylene are 5ppm, 2ppm and 50ppm respectively.

Lightweight Fiber Optic Gas Sensor for Monitoring Regenerative Food Production

NASA Technical Reports Server (NTRS)

Schmidlin, Edward; Goswami, Kisholoy

1995-01-01

In this final report, Physical Optics Corporation (POC) describes its development of sensors for oxygen, carbon dioxide, and relative humidity. POC has constructed a phase fluorometer that can detect oxygen over the full concentration range from 0 percent to 100 percent. Phase-based measurements offer distinct advantages, such as immunity to source fluctuation, photobleaching, and leaching. All optics, optoelectronics, power supply, and the printed circuit board are included in a single box; the only external connections to the fluorometer are the optical fiber sensor and a power cord. The indicator-based carbon dioxide sensor is also suitable for short-term and discrete measurements over the concentration range from 0 percent to 100 percent. The optical fiber-based humidity sensor contains a porous core for direct interaction of the light beam with water vapor within fiber pores; the detection range for the humidity sensor is 10 percent to 100 percent, and response time is under five minutes. POC is currently pursuing the commercialization of these oxygen and carbon dioxide sensors for environmental applications.

Influence of functionalized silicones on hair fiber-fiber interactions and on the relationship with the macroscopic behavior of hair assembly.

PubMed

Dussaud, Anne; Fieschi-Corso, Lara

2009-01-01

It is well established that silicones alter hair surface properties and that silicones have a significant impact on the macroscopic behavior of hair assembly, such as visual appearance, combing performance and manageability of the hair. In order to fine-tune the chemistry of functionlized silicones for specific consumer benefits and hair types, we investigated the influence of silicones on hair fiber-fiber interactions and their correlation to hair volume. The incline plane fiber loop method, implemented with a high-precision motorized rotary stage, was used to quantify the fiber-fiber interactions. Low load static friction was studied as a function of polymer molecular weight, dose and chemical architecture. This information was related to the macroscopic behavior of hair assembly, using virgin curly hair in high humidity.

Fiber optic relative humidity sensor based on the tilted fiber Bragg grating coated with graphene oxide

NASA Astrophysics Data System (ADS)

Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying; Zhong, Chuan; Dong, Xinyong; Tong, Limin

2016-07-01

A fiber optic relative humidity (RH) sensor based on the tilted fiber Bragg grating (TFBG) coated with graphene oxide (GO) film was presented. Amplitudes of the cladding mode resonances of the TFGB varies with the water sorption and desorption processes of the GO film, because of the strong interactions between the excited backward propagating cladding modes and the GO film. By detecting the transmission intensity changes of the cladding mode resonant dips at the wavelength of 1557 nm, the maximum sensitivity of 0.129 dB/%RH with a linear correlation coefficient of 99% under the RH range of 10-80% was obtained. The Bragg mode of TFBG can be used as power or wavelength references, since it is inherently insensitive to RH changes. In addition, the proposed humidity sensor shows a good performance in repeatability and stability.

Holographic imaging based on time-domain data of natural-fiber-containing materials

DOEpatents

Bunch, Kyle J.; McMakin, Douglas L.

2012-09-04

Methods and apparatuses for imaging material properties in natural-fiber-containing materials can utilize time-domain data. In particular, images can be constructed that provide quantified measures of localized moisture content. For example, one or more antennas and at least one transceiver can be configured to collect time-domain data from radiation interacting with the natural-fiber-containing materials. The antennas and the transceivers are configured to transmit and receive electromagnetic radiation at one or more frequencies, which are between 50 MHz and 1 THz, according to a time-domain impulse function. A computing device is configured to transform the time-domain data to frequency-domain data, to apply a synthetic imaging algorithm for constructing a three-dimensional image of the natural-fiber-containing materials, and to provide a quantified measure of localized moisture content based on a pre-determined correlation of moisture content to frequency-domain data.

Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties.

PubMed

Stephansen, Karen; García-Díaz, María; Jessen, Flemming; Chronakis, Ioannis S; Nielsen, Hanne M

2016-03-07

Intermolecular interaction phenomena occurring between endogenous compounds, such as proteins and bile salts, and electrospun compounds are so far unreported, despite the exposure of fibers to such biorelevant compounds when applied for biomedical purposes, e.g., tissue engineering, wound healing, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining with the hydrophobic dye 8-anilino-1-naphthalenesulfonic acid indicated that the FSP-Ins fibers were hydrophobic, and showed that the fiber surface properties were affected differently by the surfactants. Bovine serum albumin also affected insulin release in vitro, indicating that also proteins may affect the fiber performance in an in vivo setting.

Graphene-Based Long-Period Fiber Grating Surface Plasmon Resonance Sensor for High-Sensitivity Gas Sensing

PubMed Central

Wei, Wei; Nong, Jinpeng; Zhang, Guiwen; Tang, Linlong; Jiang, Xiao; Chen, Na; Luo, Suqin; Lan, Guilian; Zhu, Yong

2016-01-01

A graphene-based long-period fiber grating (LPFG) surface plasmon resonance (SPR) sensor is proposed. A monolayer of graphene is coated onto the Ag film surface of the LPFG SPR sensor, which increases the intensity of the evanescent field on the surface of the fiber and thereby enhances the interaction between the SPR wave and molecules. Such features significantly improve the sensitivity of the sensor. The experimental results demonstrate that the sensitivity of the graphene-based LPFG SPR sensor can reach 0.344 nm%−1 for methane, which is improved 2.96 and 1.31 times with respect to the traditional LPFG sensor and Ag-coated LPFG SPR sensor, respectively. Meanwhile, the graphene-based LPFG SPR sensor exhibits excellent response characteristics and repeatability. Such a SPR sensing scheme offers a promising platform to achieve high sensitivity for gas-sensing applications. PMID:28025483

Neutralized adenovirus-immune complexes can mediate effective gene transfer via an Fc receptor-dependent infection pathway.

PubMed

Leopold, Philip L; Wendland, Rebecca L; Vincent, Theresa; Crystal, Ronald G

2006-10-01

Neutralization of adenovirus (Ad) by anti-Ad neutralizing antibodies in serum involves formation of Ad-immune complexes that prevent the virus from interacting with target cells. We hypothesized that Ad-immune complexes likely contain viable Ad vectors which, although no longer capable of gaining access to receptors on target cells, may be able to express transgenes in cells bearing Fc receptors for immunoglobulins, i.e., that antibody-based "neutralization" of Ad vectors may be circumvented by the Fc receptor pathway. To test this hypothesis, we expressed the Fcgamma receptor IIA (FcgammaR) in A549 lung epithelial cells or human dermal fibroblasts and evaluated gene transfer in the presence of human neutralizing anti-Ad serum. FcgammaR-expressing cells bound and internalized copious amounts of Ad, with a distinct population of internalized Ad trafficking to the nucleus. The dose-response curves for inhibition of gene transfer revealed that FcgammaR-expressing cells required a more-than-10-fold higher concentration of anti-Ad serum to achieve 50% inhibition of Ad-encoded beta-galactosidase expression compared with non-FcgammaR-expressing cells. The discrepancy between neutralization of Ad during infection of FcgammaR-expressing cells and neutralization of Ad during infection of non-FcgammaR-expressing cells occurred with either heat-inactivated or non-heat-inactivated sera, was blocked by addition of purified Fc domain protein, and did not require the cytoplasmic domain of FcgammaR, suggesting that immune complex internalization proceeded via endocytosis rather than phagocytosis. FcgammaR-mediated infection by Ad-immune complexes did not require expression of the coxsackie virus-Ad receptor (CAR) since similar data were obtained when CAR-deficient human dermal fibroblasts were engineered to express FcgammaR. However, interaction of the Ad penton base with cell surface integrins contributed to the difference in neutralization between FcgammaR-expressing and non-FcgammaR-expressing cells. The data indicate that complexes formed from Ad and anti-Ad neutralizing antibodies, while compromised with respect to infection of non-FcgammaR-expressing target cells, maintain the potential to transfer genes to FcgammaR-expressing cells, with consequent expression of the transgene. The formation of Ad-immune complexes that can target viable virus to antigen-presenting cells may account for the success of Ad-based vaccines administered in the presence of low levels of neutralizing anti-Ad antibody.

Detecting ionizing radiation with optical fibers down to biomedical doses

NASA Astrophysics Data System (ADS)

Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; De Natale, P.; Gagliardi, G.

2013-10-01

We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10-4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.

Certain bright soliton interactions of the Sasa-Satsuma equation in a monomode optical fiber

NASA Astrophysics Data System (ADS)

Liu, Lei; Tian, Bo; Chai, Han-Peng; Yuan, Yu-Qiang

2017-03-01

Under investigation in this paper is the Sasa-Satsuma equation, which describes the propagation of ultrashort pulses in a monomode fiber with the third-order dispersion, self-steepening, and stimulated Raman scattering effects. Based on the known bilinear forms, through the modified expanded formulas and symbolic computation, we construct the bright two-soliton solutions. Through classifying the interactions under different parameter conditions, we reveal six cases of interactions between the two solitons via an asymptotic analysis. With the help of the analytic and graphic analysis, we find that such interactions are different from those of the nonlinear Schrödinger equation and Hirota equation. When those solitons interact with each other, the singular-I soliton is shape-preserving, while the singular-II and nonsingular solitons may be shape preserving or shape changing. Such elastic and inelastic interaction phenomena in a scalar equation might enrich the knowledge of soliton behavior, which could be expected to be experimentally observed.

Certain bright soliton interactions of the Sasa-Satsuma equation in a monomode optical fiber.

PubMed

Liu, Lei; Tian, Bo; Chai, Han-Peng; Yuan, Yu-Qiang

2017-03-01

Under investigation in this paper is the Sasa-Satsuma equation, which describes the propagation of ultrashort pulses in a monomode fiber with the third-order dispersion, self-steepening, and stimulated Raman scattering effects. Based on the known bilinear forms, through the modified expanded formulas and symbolic computation, we construct the bright two-soliton solutions. Through classifying the interactions under different parameter conditions, we reveal six cases of interactions between the two solitons via an asymptotic analysis. With the help of the analytic and graphic analysis, we find that such interactions are different from those of the nonlinear Schrödinger equation and Hirota equation. When those solitons interact with each other, the singular-I soliton is shape-preserving, while the singular-II and nonsingular solitons may be shape preserving or shape changing. Such elastic and inelastic interaction phenomena in a scalar equation might enrich the knowledge of soliton behavior, which could be expected to be experimentally observed.

Ytterbium-doped fiber laser passively mode locked by few-layer Molybdenum Disulfide (MoS2) saturable absorber functioned with evanescent field interaction

PubMed Central

Du, Juan; Wang, Qingkai; Jiang, Guobao; Xu, Changwen; Zhao, Chujun; Xiang, Yuanjiang; Chen, Yu; Wen, Shuangchun; Zhang, Han

2014-01-01

By coupling few-layer Molybdenum Disulfide (MoS2) with fiber-taper evanescent light field, a new type of MoS2 based nonlinear optical modulating element had been successfully fabricated as a two-dimensional layered saturable absorber with strong light-matter interaction. This MoS2-taper-fiber device is not only capable of passively mode-locking an all-normal-dispersion ytterbium-doped fiber laser and enduring high power laser excitation (up to 1 W), but also functions as a polarization sensitive optical modulating component (that is, different polarized light can induce different nonlinear optical response). Thanks to the combined advantages from the strong nonlinear optical response in MoS2 together with the sufficiently-long-range interaction between light and MoS2, this device allows for the generation of high power stable dissipative solitons at 1042.6 nm with pulse duration of 656 ps and a repetition rate of 6.74 MHz at a pump power of 210 mW. Our work may also constitute the first example of MoS2-enabled wave-guiding photonic device, and potentially give some new insights into two-dimensional layered materials related photonics. PMID:25213108

Cavitation effect of holmium laser pulse applied to ablation of hard tissue underwater.

PubMed

Lü, Tao; Xiao, Qing; Xia, Danqing; Ruan, Kai; Li, Zhengjia

2010-01-01

To overcome the inconsecutive drawback of shadow and schlieren photography, the complete dynamics of cavitation bubble oscillation or ablation products induced by a single holmium laser pulse [2.12 microm, 300 micros (FWHM)] transmitted in different core diameter (200, 400, and 600 microm) fibers is recorded by means of high-speed photography. Consecutive images from high-speed cameras can stand for the true and complete process of laser-water or laser-tissue interaction. Both laser pulse energy and fiber diameter determine cavitation bubble size, which further determines acoustic transient amplitudes. Based on the pictures taken by high-speed camera and scanned by an optical coherent microscopy (OCM) system, it is easily seen that the liquid layer at the distal end of the fiber plays an important role during the process of laser-tissue interaction, which can increase ablation efficiency, decrease heat side effects, and reduce cost.

Interaction of DNA with Simple and Mixed Ligand Copper(II) Complexes of 1,10-Phenanthrolines as Studied by DNA-Fiber EPR Spectroscopy

PubMed Central

Chikira, Makoto; Ng, Chew Hee; Palaniandavar, Mallayan

2015-01-01

The interaction of simple and ternary Cu(II) complexes of 1,10-phenanthrolines with DNA has been studied extensively because of their various interesting and important functions such as DNA cleavage activity, cytotoxicity towards cancer cells, and DNA based asymmetric catalysis. Such functions are closely related to the DNA binding modes of the complexes such as intercalation, groove binding, and electrostatic surface binding. A variety of spectroscopic methods have been used to study the DNA binding mode of the Cu(II) complexes. Of all these methods, DNA-fiber electron paramagnetic resonance (EPR) spectroscopy affords unique information on the DNA binding structures of the complexes. In this review we summarize the results of our DNA-fiber EPR studies on the DNA binding structure of the complexes and discuss them together with the data accumulated by using other measurements. PMID:26402668

Effects of corn silage hybrids and dietary nonforage fiber sources on feed intake, digestibility, ruminal fermentation, and productive performance of lactating Holstein dairy cows.

PubMed

Holt, M S; Williams, C M; Dschaak, C M; Eun, J-S; Young, A J

2010-11-01

This experiment was conducted to determine the effects of corn silage hybrids and nonforage fiber sources (NFFS) in high forage diets formulated with high dietary proportions of alfalfa hay (AH) and corn silage (CS) on ruminal fermentation and productive performance by early lactating dairy cows. Eight multiparous Holstein cows (4 ruminally fistulated) averaging 36±6.2 d in milk were used in a duplicated 4 × 4 Latin square design experiment with a 2 × 2 factorial arrangement of treatments. Cows were fed 1 of 4 dietary treatments during each of the four 21-d replicates. Treatments were (1) conventional CS (CCS)-based diet without NFFS, (2) CCS-based diet with NFFS, (3) brown midrib CS (BMRCS)-based diet without NFFS, and (4) BMRCS-based diet with NFFS. Diets were isonitrogenous and isocaloric. Sources of NFFS consisted of ground soyhulls and pelleted beet pulp to replace a portion of AH and CS in the diets. In vitro 30-h neutral detergent fiber (NDF) degradability was greater for BMRCS than for CCS (42.3 vs. 31.2%). Neither CS hybrids nor NFFS affected intake of dry matter (DM) and nutrients. Digestibility of N, NDF, and acid detergent fiber tended to be greater for cows consuming CCS-based diets. Milk yield was not influenced by CS hybrids and NFFS. However, a tendency for an interaction between CS hybrids and NFFS occurred, with increased milk yield due to feeding NFFS with the BMRCS-based diet. Yields of milk fat and 3.5% fat-corrected milk decreased when feeding the BMRCS-based diet, and a tendency existed for an interaction between CS hybrids and NFFS because milk fat concentration further decreased by feeding NFFS with BMRCS-based diet. Although feed efficiency (milk/DM intake) was not affected by CS hybrids and NFFS, an interaction was found between CS hybrids and NFFS because feed efficiency increased when NFFS was fed only with BMRCS-based diet. Total volatile fatty acid production and individual molar proportions were not affected by diets. Dietary treatments did not influence ruminal pH profiles, except that duration (h/d) of pH <5.8 decreased when NFFS was fed in a CCS-based diet but not in a BMRCS-based diet, causing a tendency for an interaction between CS hybrids and NFFS. Overall measurements in our study reveal that high forage NDF concentration (20% DM on average) may eliminate potentially positive effects of BMRCS. In the high forage diets, NFFS exerted limited effects on productive performance when they replaced AH and CS. Although the high quality AH provided adequate NDF (38.3% DM) for optimal rumen fermentative function, the low NDF concentration of the AH and the overall forage particle size reduced physically effective fiber and milk fat concentration. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Biosensing with optical fiber gratings

NASA Astrophysics Data System (ADS)

Chiavaioli, Francesco; Baldini, Francesco; Tombelli, Sara; Trono, Cosimo; Giannetti, Ambra

2017-06-01

Optical fiber gratings (OFGs), especially long-period gratings (LPGs) and etched or tilted fiber Bragg gratings (FBGs), are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI) change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength) as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors), and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

Multiscale characterization of chemical–mechanical interactions between polymer fibers and cementitious matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernández-Cruz, Daniel; Hargis, Craig W.; Bae, Sungchul

2014-04-01

Together with a series of mechanical tests, the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (lCT). Experimental results showed that these techniques have great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber the polypropylene core and the ethylene acrylic acid copolymer sheath. Similarly, chemical interactions between the hybrid fiber and the cement hydration products were observed, indicating the chemical bonding between the sheath and the hardened cement paste matrix. Microtomography allowedmore » visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars.« less

Cotton and Protein Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goheen, Steven C.; Edwards, J. V.; Rayburn, Alfred R.

The adsorbent properties of important wound fluid proteins and cotton cellulose are reviewed. This review focuses on the adsorption of albumin to cotton-based wound dressings and some chemically modified derivatives targeted for chronic wounds. Adsorption of elastase in the presence of albumin was examined as a model to understand the interactive properties of these wound fluid components with cotton fibers. In the chronic non-healing wound, elastase appears to be over-expressed, and it digests tissue and growth factors, interfering with the normal healing process. Albumin is the most prevalent protein in wound fluid, and in highly to moderately exudative wounds, itmore » may bind significantly to the fibers of wound dressings. Thus, the relative binding properties of both elastase and albumin to wound dressing fibers are of interest in the design of more effective wound dressings. The present work examines the binding of albumin to two different derivatives of cotton, and quantifies the elastase binding to the same derivatives following exposure of albumin to the fiber surface. An HPLC adsorption technique was employed coupled with a colorimetric enzyme assay to quantify the relative binding properties of albumin and elastase to cotton. The results of wound protein binding are discussed in relation to the porosity and surface chemistry interactions of cotton and wound proteins. Studies are directed to understanding the implications of protein adsorption phenomena in terms of fiber-protein models that have implications for rationally designing dressings for chronic wounds.« less

Detection of adulteration in diesel and petrol by kerosene using SPR based fiber optic technique

NASA Astrophysics Data System (ADS)

Verma, Rajneesh K.; Suwalka, Payal; Yadav, Jatin

2018-07-01

In this paper we focused on the experimental investigations for fabricating a surface plasmon resonance (SPR) based fiber optic sensor for the detection of the extent of adulteration in petrochemicals: petrol and diesel by kerosene. Primarily it is observed that the refractive index of the petrol and diesel changes if we mix kerosene in it. The variation in refractive index is linear in nature. Utilizing the phenomenon of surface plasmon resonance in Krestchmann configuration on optical fiber, the percentage of adulteration in petrol and diesel is detected. The detection level of adulteration is quantified systematically for both the petrol and diesel. The study carried out here explores the possibility of utilizing SPR technique for the detection of the level of adulteration in petrochemicals. The suitability of the optical fiber for remote sensing and its immunity towards electromagnetic interaction makes this probe very useful for such endeavor. High sensitivity, easy construction and its portability, makes this study important in the development of SPR based optical fiber sensors for petrochemical industries. Apart from this various aspects of environment polluting hazardous/toxic gases as an emission product of automobile fuels has also been discussed.

Body-monitoring and health supervision by means of optical fiber-based sensing systems in medical textiles.

PubMed

Quandt, Brit M; Scherer, Lukas J; Boesel, Luciano F; Wolf, Martin; Bona, Gian-Luca; Rossi, René M

2015-02-18

Long-term monitoring with optical fibers has moved into the focus of attention due to the applicability for medical measurements. Within this Review, setups of flexible, unobtrusive body-monitoring systems based on optical fibers and the respective measured vital parameters are in focus. Optical principles are discussed as well as the interaction of light with tissue. Optical fiber-based sensors that are already used in first trials are primarily selected for the section on possible applications. These medical textiles include the supervision of respiration, cardiac output, blood pressure, blood flow and its saturation with hemoglobin as well as oxygen, pressure, shear stress, mobility, gait, temperature, and electrolyte balance. The implementation of these sensor concepts prompts the development of wearable smart textiles. Thus, current sensing techniques and possibilities within photonic textiles are reviewed leading to multiparameter designs. Evaluation of these designs should show the great potential of optical fibers for the introduction into textiles especially due to the benefit of immunity to electromagnetic radiation. Still, further improvement of the signal-to-noise ratio is often necessary to develop a commercial monitoring system. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fiber optic evanescent field sensor for detection of explosives and CO2 dissolved in water

NASA Astrophysics Data System (ADS)

Orghici, R.; Willer, U.; Gierszewska, M.; Waldvogel, S. R.; Schade, W.

2008-02-01

A fiber optic approach for the determination of the carbon dioxide concentration in the gas or fluid phase during sequestration, as well as for the sensing of the explosive TNT is described. The sensor consists of a quartz glass multimode fiber with core diameter of 200 μm and is based on the evanescent field principle. Cladding and jacket of the fiber are removed in the sensing portion, therefore interaction between light within the fiber and the surrounding medium is possible. A single-mode distributed feedback (DFB) laser diode with an emission wavelength around λ= 1.57 μm and a frequency doubled passively Q-switched Cr4+:Nd3+:YAG microchip laser (λ= 1064 nm)are used as light sources. The experimental setup and the sensitivity of the evanescent field sensor are characterized.

Conservation laws, bilinear forms and solitons for a fifth-order nonlinear Schrödinger equation for the attosecond pulses in an optical fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chai, Jun; Tian, Bo, E-mail: tian_bupt@163.com; Zhen, Hui-Ling

Under investigation in this paper is a fifth-order nonlinear Schrödinger equation, which describes the propagation of attosecond pulses in an optical fiber. Based on the Lax pair, infinitely-many conservation laws are derived. With the aid of auxiliary functions, bilinear forms, one-, two- and three-soliton solutions in analytic forms are generated via the Hirota method and symbolic computation. Soliton velocity varies linearly with the coefficients of the high-order terms. Head-on interaction between the bidirectional two solitons and overtaking interaction between the unidirectional two solitons as well as the bound state are depicted. For the interactions among the three solitons, two head-onmore » and one overtaking interactions, three overtaking interactions, an interaction between a bound state and a single soliton and the bound state are displayed. Graphical analysis shows that the interactions between the two solitons are elastic, and interactions among the three solitons are pairwise elastic. Stability analysis yields the modulation instability condition for the soliton solutions.« less

Potential artifacts associated with historical preparation of joint compound samples and reported airborne asbestos concentrations.

PubMed

Brorby, G P; Sheehan, P J; Berman, D W; Bogen, K T; Holm, S E

2011-05-01

Airborne samples collected in the 1970s for drywall workers using asbestos-containing joint compounds were likely prepared and analyzed according to National Institute of Occupational Safety and Health Method P&CAM 239, the historical precursor to current Method 7400. Experimentation with a re-created, chrysotile-containing, carbonate-based joint compound suggested that analysis following sample preparation by the historical vs. current method produces different fiber counts, likely because of an interaction between the different clearing and mounting chemicals used and the carbonate-based joint compound matrix. Differences were also observed during analysis using Method 7402, depending on whether acetic acid/dimethylformamide or acetone was used during preparation to collapse the filter. Specifically, air samples of sanded chrysotile-containing joint compound prepared by the historical method yielded fiber counts significantly greater (average of 1.7-fold, 95% confidence interval: 1.5- to 2.0-fold) than those obtained by the current method. In addition, air samples prepared by Method 7402 using acetic acid/dimethylformamide yielded fiber counts that were greater (2.8-fold, 95% confidence interval: 2.5- to 3.2-fold) than those prepared by this method using acetone. These results indicated (1) there is an interaction between Method P&CAM 239 preparation chemicals and the carbonate-based joint compound matrix that reveals fibers that were previously bound in the matrix, and (2) the same appeared to be true for Method 7402 preparation chemicals acetic acid/dimethylformamide. This difference in fiber counts is the opposite of what has been reported historically for samples of relatively pure chrysotile dusts prepared using the same chemicals. This preparation artifact should be considered when interpreting historical air samples for drywall workers prepared by Method P&CAM 239. Copyright © 2011 JOEH, LLC

Biodegradable-Polymer-Blend-Based Surgical Sealant with Body-Temperature-Mediated Adhesion.

PubMed

Behrens, Adam M; Lee, Nora G; Casey, Brendan J; Srinivasan, Priya; Sikorski, Michael J; Daristotle, John L; Sandler, Anthony D; Kofinas, Peter

2015-12-22

The development of practical and efficient surgical sealants has the propensity to improve operational outcomes. A biodegradable polymer blend is fabricated as a nonwoven fiber mat in situ. After direct deposition onto the tissue of interest, the material transitions from a fiber mat to a film. This transition promotes polymer-substrate interfacial interactions leading to improved adhesion and surgical sealant performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robust, low-noise, polarization-maintaining mode-locked Er-fiber laser with a planar lightwave circuit (PLC) device as a multi-functional element.

PubMed

Kim, Chur; Kwon, Dohyeon; Kim, Dohyun; Choi, Sun Young; Cha, Sang Jun; Choi, Ki Sun; Yeom, Dong-Il; Rotermund, Fabian; Kim, Jungwon

2017-04-15

We demonstrate a new planar lightwave circuit (PLC)-based device, integrated with a 980/1550 wavelength division multiplexer, an evanescent-field-interaction-based saturable absorber, and an output tap coupler, which can be employed as a multi-functional element in mode-locked fiber lasers. Using this multi-functional PLC device, we demonstrate a simple, robust, low-noise, and polarization-maintaining mode-locked Er-fiber laser. The measured full-width at half-maximum bandwidth is 6 nm centered at 1555 nm, corresponding to 217 fs transform-limited pulse duration. The measured RIN and timing jitter are 0.22% [10 Hz-10 MHz] and 6.6 fs [10 kHz-1 MHz], respectively. Our results show that the non-gain section of mode-locked fiber lasers can be easily implemented as a single PLC chip that can be manufactured by a wafer-scale fabrication process. The use of PLC processes in mode-locked lasers has the potential for higher manufacturability of low-cost and robust fiber and waveguide lasers.

FIBER AND INTEGRATED OPTICS: Magnetooptic interaction in fiber waveguides

NASA Astrophysics Data System (ADS)

Antonov, S. N.; Bulyuk, A. N.; Gulyaev, Yurii V.

1989-11-01

Theoretical and experimental studies were made of the effects of a distributed magnetooptic interaction in fiber waveguides. Analytic solutions were obtained for relating light modulation at the exit of a waveguide to the parameters of its winding in the form of a coil and to an external magnetic field under conditions ensuring the exact spatial phase matching. It was confirmed experimentally that the interaction length of the order of several tens of meters was quite acceptable and could ensure a sensitivity of at least 10 - 4 Oe in the case of a quartz fiber waveguide.

Microstructural Dynamics and Rheology of Suspensions of Rigid Fibers

NASA Astrophysics Data System (ADS)

Butler, Jason E.; Snook, Braden

2018-01-01

The dynamics and rheology of suspensions of rigid, non-Brownian fibers in Newtonian fluids are reviewed. Experiments, theories, and computer simulations are considered, with an emphasis on suspensions at semidilute and concentrated conditions. In these suspensions, interactions between the particles strongly influence the microstructure and rheological properties of the suspension. The interactions can arise from hydrodynamic disturbances, giving multibody interactions at long ranges and pairwise lubrication forces over short distances. For concentrated suspensions, additional interactions due to excluded volume (contacts) and adhesive forces are addressed. The relative importance of the various interactions as a function of fiber concentration is assessed.

High-density, microsphere-based fiber optic DNA microarrays.

PubMed

Epstein, Jason R; Leung, Amy P K; Lee, Kyong Hoon; Walt, David R

2003-05-01

A high-density fiber optic DNA microarray has been developed consisting of oligonucleotide-functionalized, 3.1-microm-diameter microspheres randomly distributed on the etched face of an imaging fiber bundle. The fiber bundles are comprised of 6000-50000 fused optical fibers and each fiber terminates with an etched well. The microwell array is capable of housing complementary-sized microspheres, each containing thousands of copies of a unique oligonucleotide probe sequence. The array fabrication process results in random microsphere placement. Determining the position of microspheres in the random array requires an optical encoding scheme. This array platform provides many advantages over other array formats. The microsphere-stock suspension concentration added to the etched fiber can be controlled to provide inherent sensor redundancy. Examining identical microspheres has a beneficial effect on the signal-to-noise ratio. As other sequences of interest are discovered, new microsphere sensing elements can be added to existing microsphere pools and new arrays can be fabricated incorporating the new sequences without altering the existing detection capabilities. These microarrays contain the smallest feature sizes (3 microm) of any DNA array, allowing interrogation of extremely small sample volumes. Reducing the feature size results in higher local target molecule concentrations, creating rapid and highly sensitive assays. The microsphere array platform is also flexible in its applications; research has included DNA-protein interaction profiles, microbial strain differentiation, and non-labeled target interrogation with molecular beacons. Fiber optic microsphere-based DNA microarrays have a simple fabrication protocol enabling their expansion into other applications, such as single cell-based assays.

Dark-dark solitons for a coupled variable-coefficient higher-order nonlinear Schrödinger system in an inhomogeneous optical fiber

NASA Astrophysics Data System (ADS)

Li, Ming-Zhen; Tian, Bo; Qu, Qi-Xing; Chai, Han-Peng; Liu, Lei; Du, Zhong

2017-12-01

In this paper, under investigation is a coupled variable-coefficient higher-order nonlinear Schrödinger system, which describes the simultaneous propagation of optical pulses in an inhomogeneous optical fiber. Based on the Lax pair and binary Darboux transformation, we present the nondegenerate N-dark-dark soliton solutions. With the graphical simulation, soliton propagation and interaction are discussed with the group velocity dispersion and fourth-order dispersion effects, which affect the velocity but have no effect on the amplitude. Linear, parabolic and periodic one dark-dark solitons are displayed. Interactions between the two solitons are presented as well, which are all elastic.

Interface Bond Improvement of Sisal Fibre Reinforced Polylactide Composites with Added Epoxy Oligomer

PubMed Central

Hao, Mingyang; Qiu, Feng; Wang, Xiwen

2018-01-01

To improve the interfacial bonding of sisal fiber-reinforced polylactide biocomposites, polylactide (PLA) and sisal fibers (SF) were melt-blended to fabricate bio-based composites via in situ reactive interfacial compatibilization with addition of a commercial grade epoxy-functionalized oligomer Joncryl ADR@-4368 (ADR). The FTIR (Fourier Transform infrared spectroscopy) analysis and SEM (scanning electron microscope) characterization demonstrated that the PLA molecular chain was bonded to the fiber surface and the epoxy-functionalized oligomer played a hinge-like role between the sisal fibers and the PLA matrix, which resulted in improved interfacial adhesion between the fibers and the PLA matrix. The interfacial reaction and microstructures of composites were further investigated by thermal and rheological analyses, which indicated that the mobility of the PLA molecular chain in composites was restricted because of the introduction of the ADR oligomer, which in turn reflected the improved interfacial interaction between SF and the PLA matrix. These results were further justified with the calculation of activation energies of glass transition relaxation (∆Ea) by dynamic mechanical analysis. The mechanical properties of PLA/SF composites were simultaneously reinforced and toughened with the addition of ADR oligomer. The interfacial interaction and structure–properties relationship of the composites are the key points of this study. PMID:29518949

Interface Bond Improvement of Sisal Fibre Reinforced Polylactide Composites with Added Epoxy Oligomer.

PubMed

Hao, Mingyang; Wu, Hongwu; Qiu, Feng; Wang, Xiwen

2018-03-07

To improve the interfacial bonding of sisal fiber-reinforced polylactide biocomposites, polylactide (PLA) and sisal fibers (SF) were melt-blended to fabricate bio-based composites via in situ reactive interfacial compatibilization with addition of a commercial grade epoxy-functionalized oligomer Joncryl ADR @ -4368 (ADR). The FTIR (Fourier Transform infrared spectroscopy) analysis and SEM (scanning electron microscope) characterization demonstrated that the PLA molecular chain was bonded to the fiber surface and the epoxy-functionalized oligomer played a hinge-like role between the sisal fibers and the PLA matrix, which resulted in improved interfacial adhesion between the fibers and the PLA matrix. The interfacial reaction and microstructures of composites were further investigated by thermal and rheological analyses, which indicated that the mobility of the PLA molecular chain in composites was restricted because of the introduction of the ADR oligomer, which in turn reflected the improved interfacial interaction between SF and the PLA matrix. These results were further justified with the calculation of activation energies of glass transition relaxation (∆ E a ) by dynamic mechanical analysis. The mechanical properties of PLA/SF composites were simultaneously reinforced and toughened with the addition of ADR oligomer. The interfacial interaction and structure-properties relationship of the composites are the key points of this study.

Sensing surface morphology of biofibers by decorating spider silk and cellulosic filaments with nematic microdroplets.

PubMed

Aguirre, Luis E; de Oliveira, Alexandre; Seč, David; Čopar, Simon; Almeida, Pedro L; Ravnik, Miha; Godinho, Maria Helena; Žumer, Slobodan

2016-02-02

Probing the surface morphology of microthin fibers such as naturally occurring biofibers is essential for understanding their structural properties, biological function, and mechanical performance. The state-of-the-art methods for studying the surfaces of biofibers are atomic force microscopy imaging and scanning electron microscopy, which well characterize surface geometry of the fibers but provide little information on the local interaction potential of the fibers with the surrounding material. In contrast, complex nematic fluids respond very well to external fields and change their optical properties upon such stimuli. Here we demonstrate that liquid crystal droplets deposited on microthin biofibers--including spider silk and cellulosic fibers--reveal characteristics of the fibers' surface, performing as simple but sensitive surface sensors. By combining experiments and numerical modeling, different types of fibers are identified through the fiber-to-nematic droplet interactions, including perpendicular and axial or helicoidal planar molecular alignment. Spider silks align nematic molecules parallel to fibers or perpendicular to them, whereas cellulose aligns the molecules unidirectionally or helicoidally along the fibers, indicating notably different surface interactions. The nematic droplets as sensors thus directly reveal chirality of cellulosic fibers. Different fiber entanglements can be identified by depositing droplets exactly at the fiber crossings. More generally, the presented method can be used as a simple but powerful approach for probing the surface properties of small-size bioobjects, opening a route to their precise characterization.

Radiation dosimetry with fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; Gagliardi, G.; De Natale, P.

2014-05-01

The measurement and monitoring of radiation dose delivered in patient tissues is a critical aspect in radiation therapy. Various dosimeters have proven effective in measuring radiations at low doses. However, there is a growing demand for new dosimeters based on small, non-invasive and high resolution devices. Here we report on a miniature dosimeter based on an optical fiber cavity. We demonstrate an ultimate detection limit of 160 mGy with an effective interaction region of 6 x 10-4 mm3. Due to its reliability, compactness and biomedical dose level sensitivity, our system shows itself suitable for applications in radiation therapy dosimetry.

Two classes of capillary optical fibers: refractive and photonic

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.

2008-11-01

This paper is a digest tutorial on some properties of capillary optical fibers (COF). Two basic types of capillary optical fibers are clearly distinguished. The classification is based on propagation mechanism of optical wave. The refractive, singlemode COF guides a dark hollow beam of light (DHB) with zero intensity on fiber axis. The photonic, singlemode COF carries nearly a perfect axial Gaussian beam with maximum intensity on fiber axis. A subject of the paper are these two basic kinds of capillary optical fibers of pure refractive and pure photonic mechanism of guided wave transmission. In a real capillary the wave may be transmitted by a mixed mechanism, refractive and photonic, with strong interaction of photonic and refractive guided wave modes. Refractive capillary optical fibers are used widely for photonic instrumentation applications, while photonic capillary optical fibers are considered for trunk optical communications. Replacement of classical, single mode, dispersion shifted, 1550nm optimized optical fibers for communications with photonic capillaries would potentially cause a next serious revolution in optical communications. The predictions say that such a revolution may happen within this decade. This dream is however not fulfilled yet. The paper compares guided modes in both kinds of optical fiber capillaries: refractive and photonic. The differences are emphasized indicating prospective application areas of these fibers.

A numerical method for simulations of rigid fiber suspensions

NASA Astrophysics Data System (ADS)

Tornberg, Anna-Karin; Gustavsson, Katarina

2006-06-01

In this paper, we present a numerical method designed to simulate the challenging problem of the dynamics of slender fibers immersed in an incompressible fluid. Specifically, we consider microscopic, rigid fibers, that sediment due to gravity. Such fibers make up the micro-structure of many suspensions for which the macroscopic dynamics are not well understood. Our numerical algorithm is based on a non-local slender body approximation that yields a system of coupled integral equations, relating the forces exerted on the fibers to their velocities, which takes into account the hydrodynamic interactions of the fluid and the fibers. The system is closed by imposing the constraints of rigid body motions. The fact that the fibers are straight have been further exploited in the design of the numerical method, expanding the force on Legendre polynomials to take advantage of the specific mathematical structure of a finite-part integral operator, as well as introducing analytical quadrature in a manner possible only for straight fibers. We have carefully treated issues of accuracy, and present convergence results for all numerical parameters before we finally discuss the results from simulations including a larger number of fibers.

Holographic imaging of natural-fiber-containing materials

DOEpatents

Bunch, Kyle J [Richland, WA; Tucker, Brian J [Pasco, WA; Severtsen, Ronald H [Richland, WA; Hall, Thomas E [Kennewick, WA; McMakin, Douglas L [Richland, WA; Lechelt, Wayne M [West Richland, WA; Griffin, Jeffrey W [Kennewick, WA; Sheen, David M [Richland, WA

2010-12-21

The present invention includes methods and apparatuses for imaging material properties in natural-fiber-containing materials. In particular, the images can provide quantified measures of localized moisture content. Embodiments of the invention utilize an array of antennas and at least one transceiver to collect amplitude and phase data from radiation interacting with the natural-fiber-containing materials. The antennas and the transceivers are configured to transmit and receive electromagnetic radiation at one or more frequencies, which are between 50 MHz and 1 THz. A conveyance system passes the natural-fiber-containing materials through a field of view of the array of antennas. A computing device is configured to apply a synthetic imaging algorithm to construct a three-dimensional image of the natural-fiber-containing materials that provides a quantified measure of localized moisture content. The image and the quantified measure are both based on the amplitude data, the phase data, or both.

All fiber magnetic field sensor with Ferrofluid-filled tapered microstructured optical fiber interferometer.

PubMed

Deng, Ming; Huang, Can; Liu, Danhui; Jin, Wei; Zhu, Tao

2015-08-10

An ultra-compact optical fiber magnetic field sensor based on a microstructured optical fiber (MOF) modal interference and ferrofluid (FF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing a tapered germanium-doped index guided MOF with six big holes injected with FF to two conventional single-mode fibers. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. Due to an efficient interaction between the magnetic nanoparticles in FF and the excited cladding mode, the magnetic field sensitivity reaches up to117.9pm/mT with a linear range from 0mT to 30mT. Moreover, the fabrication process of the proposed sensor is simple, easy and cost-effective. Therefore, it will be a promising candidate for military, aviation industry, and biomedical applications, especially, for the applications where the space is limited.

Theoretical analysis of the all-fiberized, dispersion-managed regenerator for simultaneous processing of WDM channels

NASA Astrophysics Data System (ADS)

Kouloumentas, Christos

2011-09-01

The concept of the all-fiberized multi-wavelength regenerator is analyzed, and the design methodology for operation at 40 Gb/s is presented. The specific methodology has been applied in the past for the experimental proof-of-principle of the technique, but it has never been reported in detail. The regenerator is based on a strong dispersion map that is implemented using alternating dispersion compensating fibers (DCF) and single-mode fibers (SMF), and minimizes the nonlinear interaction between the wavelength-division multiplexing (WDM) channels. The optimized regenerator design with + 0.86 ps/nm/km average dispersion of the nonlinear fiber section is further investigated. The specific design is capable of simultaneously processing five WDM channels with 800 GHz channel spacing and providing Q-factor improvement higher than 1 dB for each channel. The cascadeability of the regenerator is also indicated using a 6-node metropolitan network simulation model.

An inhibitory interaction of human cortical responses to stimuli preferentially exciting Aδ or C fibers

PubMed Central

Tran, Tuan D.; Matre, Dagfinn; Casey, Kenneth L.

2008-01-01

Finely myelinated (type Aδ) and unmyelinated (type C) fibers are the major afferent inputs to spinothalamic tract neurons mediating sensory and reflex responses to noxious and thermal stimuli. These two fiber types differ in their sensory and biophysical properties, raising questions about the interaction of their supraspinal responses. Therefore, we investigated the interaction of cortical responses to stimuli that preferentially excite these fibers in human subjects using evoked potential recordings in a paired conditioning stimulation (CS) and test stimulation (TS) paradigm. There were two experiments, one with Aδ as CS and C as TS (Aδ-C) and another with these stimuli reversed (C-Aδ). We used intra-epidermal electrical pulses applied to the dorsal left hand at 2 and 1 × pinprick threshold (pp) for the preferential stimulation of Aδ fibers and 37 – 50°C contact heat pulses applied to the left or right thenar and left hypothenar eminences for the preferential stimulation of C fibers. We found that the cortical response to preferential Aδ or C fiber stimulation was attenuated whenever either cortical response preceded the other. Standardized values of peak and integrated amplitudes were < 1 in all paring conditions and in all subjects in both experiments. The suppressive effect varied in magnitude with the intensity of the conditioning stimulus in both Aδ-C and C-Aδ experiments. Furthermore, intra-segmental interaction was differentially effective for Aδ conditioning, (peak amplitude, p < 0.008; ANOVA). Our experiments provide the first neurophysiological evidence for a somatotopically distributed, mutually suppressive interaction between cortical responses to preferentially activated Aδ and C afferents in humans. This suppressive interaction of cortical responses suggests contrasting and possibly mutually exclusive sensori-motor functions mediated through the Aδ and C fiber afferent channels. PMID:18308475

Advanced end-to-end fiber optic sensing systems for demanding environments

NASA Astrophysics Data System (ADS)

Black, Richard J.; Moslehi, Behzad

2010-09-01

Optical fibers are small-in-diameter, light-in-weight, electromagnetic-interference immune, electrically passive, chemically inert, flexible, embeddable into different materials, and distributed-sensing enabling, and can be temperature and radiation tolerant. With appropriate processing and/or packaging, they can be very robust and well suited to demanding environments. In this paper, we review a range of complete end-to-end fiber optic sensor systems that IFOS has developed comprising not only (1) packaged sensors and mechanisms for integration with demanding environments, but (2) ruggedized sensor interrogators, and (3) intelligent decision aid algorithms software systems. We examine the following examples: " Fiber Bragg Grating (FBG) optical sensors systems supporting arrays of environmentally conditioned multiplexed FBG point sensors on single or multiple optical fibers: In conjunction with advanced signal processing, decision aid algorithms and reasoners, FBG sensor based structural health monitoring (SHM) systems are expected to play an increasing role in extending the life and reducing costs of new generations of aerospace systems. Further, FBG based structural state sensing systems have the potential to considerably enhance the performance of dynamic structures interacting with their environment (including jet aircraft, unmanned aerial vehicles (UAVs), and medical or extravehicular space robots). " Raman based distributed temperature sensing systems: The complete length of optical fiber acts as a very long distributed sensor which may be placed down an oil well or wrapped around a cryogenic tank.

Distributed photothermal spectroscopy in microstructured optical fibers: towards high-resolution mapping of gas presence over long distances.

PubMed

Garcia-Ruiz, Andres; Pastor-Graells, Juan; Martins, Hugo F; Tow, Kenny Hey; Thévenaz, Luc; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

2017-02-06

Chemical sensing using optical fibers is often challenging, as it is generally difficult to achieve strong interaction between the guided light and the analyte at the wavelength of interest for performing the detection. Despite this difficulty, many schemes exist (and can be found in the literature) for point chemical fiber sensors. However, the challenge increases even further when it comes to performing fully distributed chemical sensing. In this case, the optical signal which interacts with the analyte is typically also the signal that has to travel to and from the interrogator: for a good sensitivity, the light should interact strongly with the analyte, leading inevitably to an increased loss and a reduced range. Few works in the literature actually provide demonstrations of truly distributed chemical sensing and, although there have been several attempts to realize these sensors (e.g. based on special fiber coatings), the vast majority of these attempts has failed to reach widespread use due to several reasons, among them: lack of sensitivity or selectivity, lack of range or resolution, cross sensitivity to temperature or strain, or need to work at specific wavelengths where fiber instrumentation becomes extremely expensive or unavailable. In this work we provide a preliminary demonstration of the possibility of achieving distributed detection of gas presence with spectroscopic selectivity, high spatial resolution, potential for long range measurements and feasibility of having most of the interrogator system working at conventional telecom wavelengths. For a full exploitation of this concept, new fibers (or more likely, fiber bundles) should be developed capable of guiding specific wavelengths in the IR (corresponding to gas absorption wavelengths) with good overlap with the analyte while also having a solid core with good transmission behavior at 1.55 μm, and good thermal coupling between the two guiding structures.

Local alignment vectors reveal cancer cell-induced ECM fiber remodeling dynamics

PubMed Central

Lee, Byoungkoo; Konen, Jessica; Wilkinson, Scott; Marcus, Adam I.; Jiang, Yi

2017-01-01

Invasive cancer cells interact with the surrounding extracellular matrix (ECM), remodeling ECM fiber network structure by condensing, degrading, and aligning these fibers. We developed a novel local alignment vector analysis method to quantitatively measure collagen fiber alignment as a vector field using Circular Statistics. This method was applied to human non-small cell lung carcinoma (NSCLC) cell lines, embedded as spheroids in a collagen gel. Collagen remodeling was monitored using second harmonic generation imaging under normal conditions and when the LKB1-MARK1 pathway was disrupted through RNAi-based approaches. The results showed that inhibiting LKB1 or MARK1 in NSCLC increases the collagen fiber alignment and captures outward alignment vectors from the tumor spheroid, corresponding to high invasiveness of LKB1 mutant cancer cells. With time-lapse imaging of ECM micro-fiber morphology, the local alignment vector can measure the dynamic signature of invasive cancer cell activity and cell-migration-induced ECM and collagen remodeling and realigning dynamics. PMID:28045069

Mode-locked Er-doped fiber laser based on liquid phase exfoliated Sb2Te3 topological insulator

NASA Astrophysics Data System (ADS)

Boguslawski, J.; Sotor, J.; Sobon, G.; Tarka, J.; Jagiello, J.; Macherzynski, W.; Lipinska, L.; Abramski, K. M.

2014-10-01

In this paper, femtosecond pulse generation in an Er-doped fiber laser is reported. The laser is passively mode-locked by an antimony telluride (Sb2Te3) topological insulator (TI) saturable absorber (SA) placed on a side-polished fiber. The Sb2Te3/chitosan suspension used to prepare the SA was obtained via liquid phase exfoliation from bulk Sb2Te3.Ultra-short 449 fs soliton pulses were generated due to the interaction between the evanescent field propagated in the fiber cladding and the Sb2Te3 layers. The optical spectrum is centered at 1556 nm with 6 nm of full-width at half maximum bandwidth. The presented method benefits from a much better repeatability compared to mechanical exfoliation.

Laboratory Directed Research and Development Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

Laboratory Directed Research and Development Program. Annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

FIND: difFerential chromatin INteractions Detection using a spatial Poisson process

PubMed Central

Chen, Yang; Zhang, Michael Q.

2018-01-01

Polymer-based simulations and experimental studies indicate the existence of a spatial dependency between the adjacent DNA fibers involved in the formation of chromatin loops. However, the existing strategies for detecting differential chromatin interactions assume that the interacting segments are spatially independent from the other segments nearby. To resolve this issue, we developed a new computational method, FIND, which considers the local spatial dependency between interacting loci. FIND uses a spatial Poisson process to detect differential chromatin interactions that show a significant difference in their interaction frequency and the interaction frequency of their neighbors. Simulation and biological data analysis show that FIND outperforms the widely used count-based methods and has a better signal-to-noise ratio. PMID:29440282

Multi-colored fibers by self-assembly of DNA, histone proteins, and cationic conjugated polymers.

PubMed

Wang, Fengyan; Liu, Zhang; Wang, Bing; Feng, Liheng; Liu, Libing; Lv, Fengting; Wang, Yilin; Wang, Shu

2014-01-07

The development of biomolecular fiber materials with imaging ability has become more and more useful for biological applications. In this work, cationic conjugated polymers (CCPs) were used to construct inherent fluorescent microfibers with natural biological macromolecules (DNA and histone proteins) through the interfacial polyelectrolyte complexation (IPC) procedure. Isothermal titration microcalorimetry results show that the driving forces for fiber formation are electrostatic and hydrophobic interactions, as well as the release of counterions and bound water molecules. Color-encoded IPC fibers were also obtained based on the co-assembly of DNA, histone proteins, and blue-, green-, or red- (RGB-) emissive CCPs by tuning the fluorescence resonance energy-transfer among the CCPs at a single excitation wavelength. The fibers could encapsulate GFP-coded Escherichia coli BL21, and the expression of GFP proteins was successfully regulated by the external environment of the fibers. These multi-colored fibers show a great potential in biomedical applications, such as biosensor, delivery, and release of biological molecules and tissue engineering. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mathematical model of the two-point bending test for strength measurement of optical fibers

NASA Astrophysics Data System (ADS)

Srubshchik, Leonid S.

1999-12-01

The mathematical and numerical analysis of two nonlinear problems of solid mechanics related to the breaking strength of coated optical glass fibers are presented. Both of these problems are concerned with the two-point bending technique which measures the strength of optical fibers by straining them in a bending mode between two parallel plates. The plates are squeezed together until the fiber fractures. The process gives a measurement of fiber strength. The present theory of this test is based on the elastica theory of an unshearable and inextensible rod. However, within the limits of the elastics theory the tensile and shear stresses cannot be determined. In this paper we study the behavior of optical glass fiber on the base of a geometrically exact nonlinear Cosserat theory in which a rod can suffer flexure, extension, and shear. We adopt the specific nonlinear stress-strain relations in silica and titania-doped silica glass fibers and show that it does not yield essential changes in the results as compared with the results for the linear stress-strain relations. We obtain the governing equations of the motion of the fiber in the two-point bending test taking into account the friction between the test fiber and the rigid plates. We develop the computational methods to solve the initial and equilibrium free-boundary nonlinear planar problems. We derive formulas for tensile and shear stresses which allow us to calculate tension in the fiber. The numerical results show that frictional forces play an important role. The interaction of optical fiber and rigid plates is treated by means of the classical contact theory.

Unravel the key genes potentially related to high strength of cotton fiber by comparative phenotypic and genomic analyses

USDA-ARS?s Scientific Manuscript database

The demand of high strength of cotton fibers has been increased dramatically with the advent of modern high speed spinning technology for producing yarn. Bundle fiber strength is affected by fiber-to-fiber interactions in addition to the individual fiber strength. The bundle fiber strength is not al...

Fiber optic-based regenerable biosensor

DOEpatents

Sepaniak, Michael J.; Vo-Dinh, Tuan

1993-01-01

A fiber optic-based regenerable biosensor. The biosensor is particularly suitable for use in microscale work in situ. In one embodiment, the biosensor comprises a reaction chamber disposed adjacent the distal end of a waveguide and adapted to receive therein a quantity of a sample containing an analyte. Leading into the chamber is a plurality of capillary conduits suitable for introducing into the chamber antibodies or other reagents suitable for selective interaction with a predetermined analyte. Following such interaction, the contents of the chamber may be subjected to an incident energy signal for developing fluorescence within the chamber that is detectable via the optical fiber and which is representative of the presence, i.e. concentration, of the selected analyte. Regeneration of the biosensor is accomplished by replacement of the reagents and/or the analyte, or a combination of these, at least in part via one or more of the capillary conduits. The capillary conduits extend from their respective terminal ends that are in fluid communication with the chamber, away from the chamber to respective location(s) remote from the chamber thereby permitting in situ location of the chamber and remote manipulation and/or analysis of the activity with the chamber.

Characterization of water in hydrated Bombyx mori silk fibroin fiber and films by 2H NMR relaxation and 13C solid state NMR.

PubMed

Asakura, Tetsuo; Isobe, Kotaro; Kametani, Shunsuke; Ukpebor, Obehi T; Silverstein, Moshe C; Boutis, Gregory S

2017-03-01

The mechanical properties of Bombyx mori silk fibroin (SF), such as elasticity and tensile strength, change remarkably upon hydration. However, the microscopic interaction with water is not currently well understood on a molecular level. In this work, the dynamics of water molecules interacting with SF was studied by 2 H solution NMR relaxation and exchange measurements. Additionally, the conformations of hydrated [3- 13 C]Ala-, [3- 13 C]Ser-, and [3- 13 C]Tyr-SF fibers and films were investigated by 13 C DD/MAS NMR. Using an inverse Laplace transform algorithm, we were able to identify four distinct components in the relaxation times for water in SF fiber. Namely, A: bulk water outside the fiber, B: water molecules trapped weakly on the surface of the fiber, C: bound water molecules located in the inner surface of the fiber, and D: bound water molecules located in the inner part of the fiber were distinguishable. In addition, four components were also observed for water in the SF film immersed in methanol for 30s, while only two components for the film immersed in methanol for 24h. The effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and non-crystalline domains of 13 C selectively labeled SF, respectively, could be determined independently. Our measurements provide new insight relating the characteristics of water and the hydration structure of silk, which are relevant in light of current interest in the design of novel silk-based biomaterials. The mechanical properties of Bombyx mori silk fibroin (SF) change remarkably upon hydration. However, the microscopic interaction between SF and water is not currently well understood on a molecular level. We were able to identify four distinct components in the relaxation times for water in SF fiber by 2 H solution NMR relaxation and exchange measurements. In addition, the effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and non-crystalline domains of 13 C selectively labeled SF, respectively, could be determined independently. Thus, our measurements provide new insight relating the characteristics of water and the hydration structure of silk, which are relevant in light of current interest in the design of novel silk-based biomaterials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanism of Membranous Tunnelling Nanotube Formation in Viral Genome Delivery

PubMed Central

Peralta, Bibiana; Gil-Carton, David; Castaño-Díez, Daniel; Bertin, Aurelie; Boulogne, Claire; Oksanen, Hanna M.; Bamford, Dennis H.; Abrescia, Nicola G. A.

2013-01-01

In internal membrane-containing viruses, a lipid vesicle enclosed by the icosahedral capsid protects the genome. It has been postulated that this internal membrane is the genome delivery device of the virus. Viruses built with this architectural principle infect hosts in all three domains of cellular life. Here, using a combination of electron microscopy techniques, we investigate bacteriophage PRD1, the best understood model for such viruses, to unveil the mechanism behind the genome translocation across the cell envelope. To deliver its double-stranded DNA, the icosahedral protein-rich virus membrane transforms into a tubular structure protruding from one of the 12 vertices of the capsid. We suggest that this viral nanotube exits from the same vertex used for DNA packaging, which is biochemically distinct from the other 11. The tube crosses the capsid through an aperture corresponding to the loss of the peripentonal P3 major capsid protein trimers, penton protein P31 and membrane protein P16. The remodeling of the internal viral membrane is nucleated by changes in osmolarity and loss of capsid-membrane interactions as consequence of the de-capping of the vertices. This engages the polymerization of the tail tube, which is structured by membrane-associated proteins. We have observed that the proteo-lipidic tube in vivo can pierce the gram-negative bacterial cell envelope allowing the viral genome to be shuttled to the host cell. The internal diameter of the tube allows one double-stranded DNA chain to be translocated. We conclude that the assembly principles of the viral tunneling nanotube take advantage of proteo-lipid interactions that confer to the tail tube elastic, mechanical and functional properties employed also in other protein-membrane systems. PMID:24086111

Endoluminal non-contact soft tissue ablation using fiber-based Er:YAG laser delivery

NASA Astrophysics Data System (ADS)

Kundrat, Dennis; Fuchs, Alexander; Schoob, Andreas; Kahrs, Lüder A.; Ortmaier, Tobias

2016-03-01

The introduction of Er:YAG lasers for soft and hard tissue ablation has proven promising results over the last decades due to strong absorption at 2.94 μm wavelength by water molecules. An extension to endoluminal applications demands laser delivery without mirror arms due to dimensional constraints. Therefore, fiber-based solutions are advanced to provide exible access while keeping space requirements to a minimum. Conventional fiber-based treatments aim at laser-tissue interactions in contact mode. However, this procedure is associated with disadvantages such as advancing decrease in power delivery due to particle coverage of the fiber tip, tissue carbonization, and obstructed observation of the ablation progress. The objective of this work is to overcome aforementioned limitations with a customized fiber-based module for non-contact robot-assisted endoluminal surgery and its associated experimental evaluation. Up to the authors knowledge, this approach has not been presented in the context of laser surgery at 2.94 μm wavelength. The preliminary system design is composed of a 3D Er:YAG laser processing unit enabling automatic laser to fiber coupling, a GeO2 solid core fiber, and a customized module combining collimation and focusing unit (focal length of 20 mm, outer diameter of 8 mm). The performance is evaluated with studies on tissue substitutes (agar-agar) as well as porcine samples that are analysed by optical coherence tomography measurements. Cuts (depths up to 3mm) with minimal carbonization have been achieved under adequate moistening and sample movement (1.5mms-1). Furthermore, an early cadaver study is presented. Future work aims at module miniaturization and integration into an endoluminal robot for scanning and focus adaptation.

Does dietary calcium interact with dietary fiber against colorectal cancer? A case-control study in Central Europe.

PubMed

Galas, Aleksander; Augustyniak, Malgorzata; Sochacka-Tatara, Elzbieta

2013-10-04

An unfavorable trend of increasing rates of colorectal cancer has been observed across modern societies. In general, dietary factors are understood to be responsible for up to 70% of the disease's incidence, though there are still many inconsistencies regarding the impact of specific dietary items. Among the dietary minerals, calcium intake may play a crucial role in the prevention. The purpose of this study was to assess the effect of intake of higher levels of dietary calcium on the risk of developing of colorectal cancer, and to evaluate dose dependent effect and to investigate possible effect modification. A hospital based case-control study of 1556 patients (703 histologically confirmed colon and rectal incident cases and 853 hospital-based controls) was performed between 2000-2012 in Krakow, Poland. The 148-item semi-quantitative Food Frequency Questionnaire to assess dietary habits and level of nutrients intake was used. Data regarding possible covariates was also collected. After adjustment for age, gender, education, consumption of fruits, raw and cooked vegetables, fish, and alcohol, as well as for intake of fiber, vitamin C, dietary iron, lifetime recreational physical activity, BMI, smoking status, and taking mineral supplements, an increase in the consumption of calcium was associated with the decrease of colon cancer risk (OR = 0.93, 95% CI: 0.89-0.98 for every 100 mg Ca/day increase). Subjects consumed >1000 mg/day showed 46% decrease of colon cancer risk (OR = 0.54, 95% CI: 0.35-0.83). The effect of dietary calcium was modified by dietary fiber (p for interaction =0.015). Finally, consistent decrease of colon cancer risk was observed across increasing levels of dietary calcium and fiber intake. These relationships were not proved for rectal cancer. The study confirmed the effect of high doses of dietary calcium against the risk of colon cancer development. This relationship was observed across different levels of dietary fiber, and the beneficial effect of dietary calcium depended on the level of dietary fiber suggesting modification effect of calcium and fiber. Further efforts are needed to confirm this association, and also across higher levels of dietary fiber intake.

Dynamics of small flexible fibers in turbulent channel flow

NASA Astrophysics Data System (ADS)

Marchioli, Cristian; Dotto, Diego; Soldati, Alfredo

2017-11-01

In this paper we investigate the dynamics of small flexible fibers in turbulent channel flow. Our aim is to examine the effect of local shear and turbulence anisotropy on the translation and rotation of fibers with different elongation and inertia. To these aims, we use a Eulerian-Lagrangian approach based on direct numerical simulation of turbulence in the dilute regime, and we model fibers, which are longer than the Kolmogorov scale, as chains of sub-Kolmogorov rods connected through ball-and-socket joints that enable bending and twisting. Velocity, orientation and concentration statistics, extracted from simulations at Reτ = 300 , are presented to give insights into the complex fibers-turbulence interactions that arise when non-sphericity and deformability add to inertial bias. Compared to fibers that translate and rotate as rigid bodies relative to the surrounding fluid, flexible fibers exhibit a stronger tendency to accumulate in the near-wall region, where they are trapped by the same mechanisms that govern preferential concentration of spherical particles. In such region, the mean shear is strong enough to reduce bending and stretch the fibers. Preferential segregation into low-speed streaks and preferential orientation in the mean flow direction are also observed.

Real-time association rate constant measurement using combination tapered fiber-optic biosensor (CTFOB) dip-probes

NASA Astrophysics Data System (ADS)

Simmonds, Boris; Wang, Chun-Wei; Kapoor, Rakesh

2010-02-01

This document reports a novel method of measuring association rate constant (ka) for antibody-antigen interaction using evanescent wave-based combination tapered fiber-optic biosensor (CTFOB) dip-probes. The method was demonstrated by measuring association rate constant for bovine serum albumin (BSA) and anti-BSA antibody interaction. "Direct method" was used for detection; goat anti-BSA "capture" antibodies were immobilized on the probe surfaces while the antigen (BSA) was directly labeled with Alexa 488 dye. The probes were subsequently submerged in 3nM Labeled BSA in egg albumin (1 mg/ml). The fluorescence signal recorded was proportional to BSA anti-BSA conjugates and continuous signal was acquired suing a fiber optic spectrometer (Ocean Optics, Inc.). A 476 nm diode laser was use as an excitation source. Association constant was estimated from a plot of signal as a function of time. Measured association rate constant ka for the binding of BSA with anti-BSA at room temperature is (8.33 +/- 0.01) x 104 M-1s-1.

Study of Natural Fiber Breakage during Composite Processing

NASA Astrophysics Data System (ADS)

Quijano-Solis, Carlos Jafet

Biofiber-thermoplastic composites have gained considerable importance in the last century. To provide mechanical reinforcement to the polymer, fibers must be larger than a critical aspect ratio (length-to-width ratio). However, biofibers undergo breakage in length or width during processing, affecting their final aspect ratio in the composites. In this study, influence on biofiber breakage by factors related to processing conditions, fiber morphology and the flow type was investigated through: a) experiments using an internal mixer, a twin-screw extruder (TSE) or a capillary rheometer; and b) a Monte Carlo computer simulation. Composites of thermomechanical fibers of aspen or wheat straw mixed with polypropylene were studied. Internal mixer experiments analyzed wheat straw and two batches of aspen fibers, named AL and AS. AL fibers had longer average length. Processing variables included the temperature, rotors speed and fiber concentration. TSE experiments studied AL and AS fiber composites under various screws speeds, temperatures and feeding rates of the polymer and fibers. Capillary rheometers experiments determined AL fiber breakage in shear and elongational flows for composites processed at different concentrations, temperatures, and strain rates. Finally, the internal mixer experimental results where compared to Monte Carlo simulation predictions. The simulation focused on fiber length breakage due to fiber-polymer interactions. Internal mixer results showed that final fiber average length depended almost solely on processing conditions while final fiber average width depended on both processing conditions and initial fiber morphology. In the TSE, processing conditions as well as initial fiber length influenced final average length. TSE results showed that the fiber concentration regime seems to influence the effect of processing variables on fiber breakage. Capillary rheometer experiments demonstrated that biofiber breakage happens in both elongational and shear flows. In some cases, percentage of biofiber breakage in elongational flow is higher. In general, simulation predictions of final average lengths were in good agreement with experiments, indicating the importance of fiber-polymer interactions on fiber breakage. The largest discrepancies were obtained at higher fiber concentration composites; these differences might be resolved, in future simulations, by including the effect of fiber-fiber interactions.

Silver-cotton nanocomposites: Nano-design of microfibrillar structure causes morphological changes and increased tenacity

PubMed Central

Nam, Sunghyun; Condon, Brian D.; Delhom, Christopher D.; Fontenot, Krystal R.

2016-01-01

The interactions of nanoparticles with polymer hosts have important implications for directing the macroscopic properties of composite fibers, yet little is known about such interactions with hierarchically ordered natural polymers due to the difficulty of achieving uniform dispersion of nanoparticles within semi-crystalline natural fiber. In this study we have homogeneously dispersed silver nanoparticles throughout an entire volume of cotton fiber. The resulting electrostatic interaction and distinct supramolecular structure of the cotton fiber provided a favorable environment for the controlled formation of nanoparticles (12 ± 3 nm in diameter). With a high surface-to-volume ratio, the extensive interfacial contacts of the nanoparticles efficiently “glued” the structural elements of microfibrils together, producing a unique inorganic-organic hybrid substructure that reinforced the multilayered architecture of the cotton fiber. PMID:27849038

Simple Model of Sickle Hemoglobin

NASA Astrophysics Data System (ADS)

Shiryayev, Andrey; Li, Xiaofei; Gunton, James

2006-03-01

A microscopic model is proposed for the interactions between sickle hemoglobin molecules based on information from the protein data bank. A Monte Carlo simulation of a simplified two patch model is carried out, with the goal of understanding fiber formation. A gradual transition from monomers to one dimensional chains is observed as one varies the density of molecules at fixed temperature, somewhat similar to the transition from monomers to polymer fibers in sickle hemoglobin molecules in solution. An observed competition between chain formation and crystallization for the model is also discussed. The results of the simulation of the equation of state are shown to be in excellent agreement with a theory for a model of globular proteins, for the case of two interacting sites.

Sensing surface morphology of biofibers by decorating spider silk and cellulosic filaments with nematic microdroplets

PubMed Central

Aguirre, Luis E.; de Oliveira, Alexandre; Seč, David; Čopar, Simon; Almeida, Pedro L.; Ravnik, Miha; Godinho, Maria Helena; Žumer, Slobodan

2016-01-01

Probing the surface morphology of microthin fibers such as naturally occurring biofibers is essential for understanding their structural properties, biological function, and mechanical performance. The state-of-the-art methods for studying the surfaces of biofibers are atomic force microscopy imaging and scanning electron microscopy, which well characterize surface geometry of the fibers but provide little information on the local interaction potential of the fibers with the surrounding material. In contrast, complex nematic fluids respond very well to external fields and change their optical properties upon such stimuli. Here we demonstrate that liquid crystal droplets deposited on microthin biofibers—including spider silk and cellulosic fibers—reveal characteristics of the fibers’ surface, performing as simple but sensitive surface sensors. By combining experiments and numerical modeling, different types of fibers are identified through the fiber-to-nematic droplet interactions, including perpendicular and axial or helicoidal planar molecular alignment. Spider silks align nematic molecules parallel to fibers or perpendicular to them, whereas cellulose aligns the molecules unidirectionally or helicoidally along the fibers, indicating notably different surface interactions. The nematic droplets as sensors thus directly reveal chirality of cellulosic fibers. Different fiber entanglements can be identified by depositing droplets exactly at the fiber crossings. More generally, the presented method can be used as a simple but powerful approach for probing the surface properties of small-size bioobjects, opening a route to their precise characterization. PMID:26768844

A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

NASA Astrophysics Data System (ADS)

Nazockdast, Ehssan; Rahimian, Abtin; Zorin, Denis; Shelley, Michael

2017-01-01

We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid-structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler-Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber-fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of semi-flexible fibers.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard

NASA Astrophysics Data System (ADS)

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than gfree with g = 2.002644 =gfree · (1 + 162ppm) with a relative uncertainty of 15ppm . This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time.

Impairment assessment of orthogonal frequency division multiplexing over dispersion-managed links in backbone and backhaul networks

NASA Astrophysics Data System (ADS)

Tamilarasan, Ilavarasan; Saminathan, Brindha; Murugappan, Meenakshi

2016-04-01

The past decade has seen the phenomenal usage of orthogonal frequency division multiplexing (OFDM) in the wired as well as wireless communication domains, and it is also proposed in the literature as a future proof technique for the implementation of flexible resource allocation in cognitive optical networks. Fiber impairment assessment and adaptive compensation becomes critical in such implementations. A comprehensive analytical model for impairments in OFDM-based fiber links is developed. The proposed model includes the combined impact of laser phase fluctuations, fiber dispersion, self phase modulation, cross phase modulation, four-wave mixing, the nonlinear phase noise due to the interaction of amplified spontaneous emission with fiber nonlinearities, and the photodetector noises. The bit error rate expression for the proposed model is derived based on error vector magnitude estimation. The performance analysis of the proposed model is presented and compared for dispersion compensated and uncompensated backbone/backhaul links. The results suggest that OFDM would perform better for uncompensated links than the compensated links due to the negligible FWM effects and there is a need for flexible compensation. The proposed model can be employed in cognitive optical networks for accurate assessment of fiber-related impairments.

Physicochemical properties of surimi gels fortified with dietary fiber.

PubMed

Debusca, Alicia; Tahergorabi, Reza; Beamer, Sarah K; Matak, Kristen E; Jaczynski, Jacek

2014-04-01

Although dietary fiber provides health benefits, most Western populations have insufficient intake. Surimi seafood is not currently fortified with dietary fiber, nor have the effects of fiber fortification on physicochemical properties of surimi been thoroughly studied. In the present study, Alaska pollock surimi was fortified with 0-8 g/100 g of long-chain powdered cellulose as a source of dietary fiber. The protein/water concentrations in surimi were kept constant by adding an inert filler, silicon dioxide in inverse concentrations to the fiber fortification. Fiber-fortified surimi gels were set at 90 °C. The objectives were to determine (1) textural and colour properties; (2) heat-induced gelation (dynamic rheology); and (3) protein endothermic transitions (differential scanning calorimetry) of surimi formulated with constant protein/water, but variable fiber content. Fiber fortification up to 6 g/100 g improved (P<0.05) texture and colour although some decline occurred with 8 g/100g of fiber. Dynamic rheology correlated with texture and showed large increase in gel elasticity, indicating enhanced thermal gelation of surimi. Differential scanning calorimetry showed that fiber fortification did not interfere with thermal transitions of surimi myosin and actin. Long-chain fiber probably traps water physically, which is stabilized by chemical bonding with protein within surimi gel matrix. Based on the present study, it is suggested that the fiber-protein interaction is mediated by water and is physicochemical in nature. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantitative analysis of the role of fiber length on phagocytosis and inflammatory response by alveolar macrophages

PubMed Central

Padmore, Trudy; Stark, Carahline; Turkevich, Leonid A.; Champion, Julie A.

2017-01-01

Background In the lung, macrophages attempt to engulf inhaled high aspect ratio pathogenic materials, secreting inflammatory molecules in the process. The inability of macrophages to remove these materials leads to chronic inflammation and disease. How the biophysical and biochemical mechanisms of these effects are influenced by fiber length remains undetermined. This study evaluates the role of fiber length on phagocytosis and molecular inflammatory responses to non-cytotoxic fibers, enabling development of quantitative length-based models. Methods Murine alveolar macrophages were exposed to long and short populations of JM-100 glass fibers, produced by successive sedimentation and repeated crushing, respectively. Interactions between fibers and macrophages were observed using time-lapse video microscopy, and quantified by flow cytometry. Inflammatory biomolecules (TNF-α, IL-1 α, COX-2, PGE2) were measured. Results Uptake of short fibers occurred more readily than for long, but long fibers were more potent stimulators of inflammatory molecules. Stimulation resulted in dose-dependent secretion of inflammatory biomolecules but no cytotoxicity or strong ROS production. Linear cytokine dose-response curves evaluated with length-dependent potency models, using measured fiber length distributions, resulted in identification of critical fiber lengths that cause frustrated phagocytosis and increased inflammatory biomolecule production. Conclusion Short fibers played a minor role in the inflammatory response compared to long fibers. The critical lengths at which frustrated phagocytosis occurs can be quantified by fitting dose-response curves to fiber distribution data. PMID:27784615

Application of diffusion barriers to high modulus fibers

NASA Technical Reports Server (NTRS)

Veltri, R. D.; Douglas, F. C.; Paradis, E. L.; Galasso, F. S.

1977-01-01

Barrier layers were coated onto high-modulus fibers, and nickel and titanium layers were overcoated as simulated matrix materials. The objective was to coat the high-strength fibers with unreactive selected materials without degrading the fibers. The fibers were tungsten, niobium, and single-crystal sapphire, while the materials used as barrier coating layers were Al2O3, Y2O3, TiC, ZrC, WC with 14% Co, and HfO2. An ion-plating technique was used to coat the fibers. The fibers were subjected to high-temperature heat treatments to evaluate the effectiveness of the barrier layer in preventing fiber-metal interactions. Results indicate that Al2O3, Y2O3, and HfO2 can be used as barrier layers to minimize the nickel-tungsten interaction. Further investigation, including thermal cycling tests at 1090 C, revealed that HfO2 is probably the best of the three.

Predicting Silk Fiber Mechanical Properties through Multiscale Simulation and Protein Design.

PubMed

Rim, Nae-Gyune; Roberts, Erin G; Ebrahimi, Davoud; Dinjaski, Nina; Jacobsen, Matthew M; Martín-Moldes, Zaira; Buehler, Markus J; Kaplan, David L; Wong, Joyce Y

2017-08-14

Silk is a promising material for biomedical applications, and much research is focused on how application-specific, mechanical properties of silk can be designed synthetically through proper amino acid sequences and processing parameters. This protocol describes an iterative process between research disciplines that combines simulation, genetic synthesis, and fiber analysis to better design silk fibers with specific mechanical properties. Computational methods are used to assess the protein polymer structure as it forms an interconnected fiber network through shearing and how this process affects fiber mechanical properties. Model outcomes are validated experimentally with the genetic design of protein polymers that match the simulation structures, fiber fabrication from these polymers, and mechanical testing of these fibers. Through iterative feedback between computation, genetic synthesis, and fiber mechanical testing, this protocol will enable a priori prediction capability of recombinant material mechanical properties via insights from the resulting molecular architecture of the fiber network based entirely on the initial protein monomer composition. This style of protocol may be applied to other fields where a research team seeks to design a biomaterial with biomedical application-specific properties. This protocol highlights when and how the three research groups (simulation, synthesis, and engineering) should be interacting to arrive at the most effective method for predictive design of their material.

FIND: difFerential chromatin INteractions Detection using a spatial Poisson process.

PubMed

Djekidel, Mohamed Nadhir; Chen, Yang; Zhang, Michael Q

2018-02-12

Polymer-based simulations and experimental studies indicate the existence of a spatial dependency between the adjacent DNA fibers involved in the formation of chromatin loops. However, the existing strategies for detecting differential chromatin interactions assume that the interacting segments are spatially independent from the other segments nearby. To resolve this issue, we developed a new computational method, FIND, which considers the local spatial dependency between interacting loci. FIND uses a spatial Poisson process to detect differential chromatin interactions that show a significant difference in their interaction frequency and the interaction frequency of their neighbors. Simulation and biological data analysis show that FIND outperforms the widely used count-based methods and has a better signal-to-noise ratio. © 2018 Djekidel et al.; Published by Cold Spring Harbor Laboratory Press.

Detection of localized inclusions of gold nanoparticles in Intralipid-1% by point-radiance spectroscopy

NASA Astrophysics Data System (ADS)

Grabtchak, Serge; Palmer, Tyler J.; Whelan, William M.

2011-07-01

Interstitial fiber-optic-based approaches used in both diagnostic and therapeutic applications rely on localized light-tissue interactions. We present an optical technique to identify spectrally and spatially specific exogenous chromophores in highly scattering turbid media. Point radiance spectroscopy is based on directional light collection at a single point with a side-firing fiber that can be rotated up to 360 deg. A side firing fiber accepts light within a well-defined, solid angle, thus potentially providing an improved spatial resolution. Measurements were performed using an 800-μm diameter isotropic spherical diffuser coupled to a halogen light source and a 600 μm, ~43 deg cleaved fiber (i.e., radiance detector). The background liquid-based scattering phantom was fabricated using 1% Intralipid. Light was collected with 1 deg increments through 360 deg-segment. Gold nanoparticles , placed into a 3.5-mm diameter capillary tube were used as localized scatterers and absorbers introduced into the liquid phantom both on- and off-axis between source and detector. The localized optical inhomogeneity was detectable as an angular-resolved variation in the radiance polar plots. This technique is being investigated as a potential noninvasive optical modality for prostate cancer monitoring.

Detection of localized inclusions of gold nanoparticles in Intralipid-1% by point-radiance spectroscopy.

PubMed

Grabtchak, Serge; Palmer, Tyler J; Whelan, William M

2011-07-01

Interstitial fiber-optic-based approaches used in both diagnostic and therapeutic applications rely on localized light-tissue interactions. We present an optical technique to identify spectrally and spatially specific exogenous chromophores in highly scattering turbid media. Point radiance spectroscopy is based on directional light collection at a single point with a side-firing fiber that can be rotated up to 360 deg. A side firing fiber accepts light within a well-defined, solid angle, thus potentially providing an improved spatial resolution. Measurements were performed using an 800-μm diameter isotropic spherical diffuser coupled to a halogen light source and a 600 μm, ∼43 deg cleaved fiber (i.e., radiance detector). The background liquid-based scattering phantom was fabricated using 1% Intralipid. Light was collected with 1 deg increments through 360 deg-segment. Gold nanoparticles , placed into a 3.5-mm diameter capillary tube were used as localized scatterers and absorbers introduced into the liquid phantom both on- and off-axis between source and detector. The localized optical inhomogeneity was detectable as an angular-resolved variation in the radiance polar plots. This technique is being investigated as a potential noninvasive optical modality for prostate cancer monitoring.

Geometric phase due to orbit-orbit interaction: rotating LP11 modes in a two-mode fiber

NASA Astrophysics Data System (ADS)

Pradeep Chakravarthy, T.; Naik, Dinesh N.; Viswanathan, Nirmal K.

2017-10-01

Accumulation of geometric phase due to non-coplanar propagation of higher-order modes in an optical fiber is experimentally demonstrated. Vertically-polarized LP11 fiber mode, excited in a horizontally-held, torsion-free, step-index, two-mode optical fiber, rotates due to asymmetry in the propagating k-vectors, arising due to off-centered beam location at the fiber input. Perceiving the process as due to rotation of the fiber about the off-axis launch position, the orbital Berry phase accumulation upon scanning the launch position in a closed-loop around the fiber axis manifests as rotational Doppler effect, a consequence of orbit-orbit interaction. The anticipated phase accumulation as a function of the input launch position, observed through interferometry is connected to the mode rotation angle, quantified using the autocorrelation method.

Modulating bacterial and gut mucosal interactions with engineered biofilm matrix proteins.

PubMed

Duraj-Thatte, Anna M; Praveschotinunt, Pichet; Nash, Trevor R; Ward, Frederick R; Joshi, Neel S

2018-02-22

Extracellular appendages play a significant role in mediating communication between bacteria and their host. Curli fibers are a class of bacterial fimbria that is highly amenable to engineering. We demonstrate the use of engineered curli fibers to rationally program interactions between bacteria and components of the mucosal epithelium. Commensal E. coli strains were engineered to produce recombinant curli fibers fused to the trefoil family of human cytokines. Biofilms formed from these strains bound more mucins than those producing wild-type curli fibers, and modulated mucin rheology as well. When treated with bacteria producing the curli-trefoil fusions mammalian cells behaved identically in terms of their migration behavior as when they were treated with the corresponding soluble trefoil factors. Overall, this demonstrates the potential utility of curli fibers as a scaffold for the display of bioactive domains and an untapped approach to rationally modulating host-microbe interactions using bacterial matrix proteins.

Capturing Structural Heterogeneity in Chromatin Fibers.

PubMed

Ekundayo, Babatunde; Richmond, Timothy J; Schalch, Thomas

2017-10-13

Chromatin fiber organization is implicated in processes such as transcription, DNA repair and chromosome segregation, but how nucleosomes interact to form higher-order structure remains poorly understood. We solved two crystal structures of tetranucleosomes with approximately 11-bp DNA linker length at 5.8 and 6.7 Å resolution. Minimal intramolecular nucleosome-nucleosome interactions result in a fiber model resembling a flat ribbon that is compatible with a two-start helical architecture, and that exposes histone and DNA surfaces to the environment. The differences in the two structures combined with electron microscopy reveal heterogeneous structural states, and we used site-specific chemical crosslinking to assess the diversity of nucleosome-nucleosome interactions through identification of structure-sensitive crosslink sites that provide a means to characterize fibers in solution. The chromatin fiber architectures observed here provide a basis for understanding heterogeneous chromatin higher-order structures as they occur in a genomic context. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Need for US Coast Guard Underwater Mission Development

DTIC Science & Technology

2013-04-23

vehicles and proliferation of fiber optic cables, raising the level of human interactions in the underwater environment. Besides the benefits from the...unmanned underwater vehicles, proliferation of fiber optic cables, and observation posts on the ocean floor will raise the level of human interactions...world’s demand for wood grows.39 As technology progresses, undersea infrastructure will continue to expand. Already, underwater fiber optic communication

Thermomechanical Characterization of SiC Fiber Tows and Implications for CMC

NASA Technical Reports Server (NTRS)

Yun, H. M.; DiCarlo, J. A.

1999-01-01

In order to better understand SiC fiber behavior within CMC microstructures, mechanical tests were performed on multifilament tows consisting of different types of as produced and pretreated fibers. Tensile strengths of tows and single fibers were measured at room temperature for nonstoichiometric Hi-Nicalon and ZMI fibers and for stoichiometric Hi-Nicalon-S, Tyranno SA. and Sylramic fibers. Based on simple bundle theory, measured strengths for as-produced and sized tows were in general agreement with the single fiber results. However, after sizing removal under inert conditions, tow strengths for the coarser grained stoichiometric fibers were typically lower than those predicted from individual fiber data. This effect is attributed to enhanced fiber-fiber mechanical interaction caused by sizing removal from the rough surfaces of these fibers. In support of this, tow strengths remained high for those fiber types with fine grains or excess surface carbon; and, when re-coated with a BN interphase coating, tow strengths for the coarser grained fibers returned to their as-produced values. When the tows were pretreated in air at intermediate temperatures, tow strengths decreased in a manner that could be correlated with the oxidation characteristics of each fiber type as measured by thermogravimetric analysis. The creep and rupture properties of Hi-Nicalon and Sylramic tows were also measured in air and argon from 1200 to 1400 C. Although displaying transient and environmental effects similar to single fibers, the tows crept faster at short times and slower at long times. This resulted in the tow rupture strengths at long time being much greater than the rupture strengths of single fibers. The CMC implications of the tow results are discussed, as well as the benefits and limitations of tow testing.

A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nazockdast, Ehssan, E-mail: ehssan@cims.nyu.edu; Center for Computational Biology, Simons Foundation, New York, NY 10010; Rahimian, Abtin, E-mail: arahimian@acm.org

We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs),more » and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid–structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler–Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber–fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of semi-flexible fibers.« less

Dynamics of Cancer Cell near Collagen Fiber Chain

NASA Astrophysics Data System (ADS)

Kim, Jihan; Sun, Bo

Cell migration is an integrated process that is important in life. Migration is essential for embryonic development as well as homeostatic processes such as wound healing and immune responses. When cell migrates through connective extracellular matrix (ECM), it applies cellular traction force to ECM and senses the rigidity of their local environment. We used human breast cancer cell (MDA-MB-231) which is highly invasive and applies strong traction force to ECM. As cancer cell applies traction force to type I collage-based ECM, it deforms collagen fibers near the surface. Patterns of deforming collagen fibers are significantly different with pairs of cancer cells compared to a single cancer cell. While a pair of cancer cells within 60 um creates aligned collagen fiber chains between them permanently, a single cancer cell does not form any fiber chains. In this experiment we measured a cellular response and an interaction between a pair of cells through the chain. Finally, we analyzed correlation of directions between cancer cell migration and the collagen chain alignment.

New methods of multimode fiber interferometer signal processing

NASA Astrophysics Data System (ADS)

Vitrik, Oleg B.; Kulchin, Yuri N.; Maxaev, Oleg G.; Kirichenko, Oleg V.; Kamenev, Oleg T.; Petrov, Yuri S.

1995-06-01

New methods of multimode fiber interferometers signal processing are suggested. For scheme of single fiber multimode interferometers with two excited modes, the method based on using of special fiber unit is developed. This unit provides the modes interaction and further sum optical field filtering. As a result the amplitude of output signal is modulated by external influence on interferometer. The stabilization of interferometer sensitivity is achieved by using additional special modulation of output signal. For scheme of single fiber multimode interferometers with excitation of wide mode spectrum, the signal of intermode interference is registered by photodiode matrix and then special electronic unit performs correlation processing. For elimination of temperature destabilization, the registered signal is adopted to multimode interferometers optical signal temperature changes. The achieved parameters for double mode scheme: temporary stability--0.6% per hour, sensitivity to interferometer length deviations--3,2 nm; for multimode scheme: temperature stability--(0.5%)/(K), temporary nonstability--0.2% per hour, sensitivity to interferometer length deviations--20 nm, dynamic range--35 dB.

Particle Trapping Mechanisms Are Different in Spatially Ordered and Disordered Interacting Gels.

PubMed

Hansing, Johann; Netz, Roland R

2018-06-05

Using stochastic simulations, we study the influence of spatial disorder on the diffusion of a single particle through a gel that consists of rigid, straight fibers. The interaction between the particle and the gel fibers consists of an invariant short-range repulsion, the steric part, and an interaction part that can be attractive or repulsive and of varying range. The effect that spatial disorder of the gel structure has on the particle diffusivity depends crucially on the presence of nonsteric interactions. For attractive interactions, disorder slows down diffusion, because in disordered gels, the particle becomes strongly trapped in regions of locally increased fiber density. For repulsive interactions, the diffusivity is minimal for intermediate disorder strength, because highly disordered lattices exhibit abundant passageways of locally low fiber density. The comparison with experimental data on protein and fluorophore diffusion through various hydrogels is favorable. Our findings shed light on particle-diffusion mechanisms in biogels and thus on biological barrier properties, which can be helpful for the optimal design of synthetic diffusors as well as synthetic mucus constructs. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

From single muscle fiber to whole muscle mechanics: a finite element model of a muscle bundle with fast and slow fibers.

PubMed

Marcucci, Lorenzo; Reggiani, Carlo; Natali, Arturo N; Pavan, Piero G

2017-12-01

Muscles exhibit highly complex, multi-scale architecture with thousands of muscle fibers, each with different properties, interacting with each other and surrounding connective structures. Consequently, the results of single-fiber experiments are scarcely linked to the macroscopic or whole muscle behavior. This is especially true for human muscles where it would be important to understand of how skeletal muscles disorders affect patients' life. In this work, we developed a mathematical model to study how fast and slow muscle fibers, well characterized in single-fiber experiments, work and generate together force and displacement in muscle bundles. We characterized the parameters of a Hill-type model, using experimental data on fast and slow single human muscle fibers, and comparing experimental data with numerical simulations obtained from finite element (FE) models of single fibers. Then, we developed a FE model of a bundle of 19 fibers, based on an immunohistochemically stained cross section of human diaphragm and including the corresponding properties of each slow or fast fiber. Simulations of isotonic contractions of the bundle model allowed the generation of its apparent force-velocity relationship. Although close to the average of the force-velocity curves of fast and slow fibers, the bundle curve deviates substantially toward the fast fibers at low loads. We believe that the present model and the characterization of the force-velocity curve of a fiber bundle represents the starting point to link the single-fiber properties to those of whole muscle with FE application in phenomenological models of human muscles.

The Interaction between Dietary Fiber and Fat and Risk of Colorectal Cancer in the Women's Health Initiative.

PubMed

Navarro, Sandi L; Neuhouser, Marian L; Cheng, Ting-Yuan David; Tinker, Lesley F; Shikany, James M; Snetselaar, Linda; Martinez, Jessica A; Kato, Ikuko; Beresford, Shirley A A; Chapkin, Robert S; Lampe, Johanna W

2016-11-30

Combined intakes of specific dietary fiber and fat subtypes protect against colon cancer in animal models. We evaluated associations between self-reported individual and combinations of fiber (insoluble, soluble, and pectins, specifically) and fat (omega-6, omega-3, and docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), specifically) and colorectal cancer (CRC) risk in the Women's Health Initiative prospective cohort ( n = 134,017). During a mean 11.7 years (1993-2010), 1952 incident CRC cases were identified. Cox regression models computed multivariate adjusted hazard ratios to estimate the association between dietary factors and CRC risk. Assessing fiber and fat individually, there was a modest trend for lower CRC risk with increasing intakes of total and insoluble fiber ( p-trend 0.09 and 0.08). An interaction ( p = 0.01) was observed between soluble fiber and DHA + EPA, with protective effects of DHA + EPA with lower intakes of soluble fiber and an attenuation at higher intakes, however this association was no longer significant after correction for multiple testing. These results suggest a modest protective effect of higher fiber intake on CRC risk, but not in combination with dietary fat subtypes. Given the robust results in preclinical models and mixed results in observational studies, controlled dietary interventions with standardized intakes are needed to better understand the interaction of specific fat and fiber subtypes on colon biology and ultimately CRC susceptibility in humans.

Effects of sodium salt types on the intermolecular interaction of sodium alginate/antarctic krill protein composite fibers.

PubMed

Zhang, Rui; Guo, Jing; Liu, Yuanfa; Chen, Shuang; Zhang, Sen; Yu, Yue

2018-06-01

Sodium alginate (SA) and antarctic krill protein (AKP) were blended to fabricate the SA/AKP composite fibers by the conventional wet spinning method using 5% CaCl 2 as coagulation solution. The sodium salt was added to the SA/AKP solution to adjust the ionization degree and intermolecular interaction of composite system. The main purpose of this study is to investigate the influences of sodium salt types (NaCl, CH 3 COONa, Na 2 SO 4 ) on the intermolecular interaction of SA/AKP composite fibers. The intermolecular interaction, morphology, crystallinity, thermal stability and mechanical properties of SA/AKP composite fibers were analyzed by fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), x-ray diffraction (XRD), thermogravimetric analysis (TGA). The results show that the types of sodium salt have obvious influences on the content of both β-sheet, intermolecular hydrogen bond, breaking strength and surface morphology in SA/AKP composite fibers, but have a negligible effect on the crystallinity and thermal stability. Copyright © 2018 Elsevier Ltd. All rights reserved.

UNC-Utah NA-MIC framework for DTI fiber tract analysis.

PubMed

Verde, Audrey R; Budin, Francois; Berger, Jean-Baptiste; Gupta, Aditya; Farzinfar, Mahshid; Kaiser, Adrien; Ahn, Mihye; Johnson, Hans; Matsui, Joy; Hazlett, Heather C; Sharma, Anuja; Goodlett, Casey; Shi, Yundi; Gouttard, Sylvain; Vachet, Clement; Piven, Joseph; Zhu, Hongtu; Gerig, Guido; Styner, Martin

2014-01-01

Diffusion tensor imaging has become an important modality in the field of neuroimaging to capture changes in micro-organization and to assess white matter integrity or development. While there exists a number of tractography toolsets, these usually lack tools for preprocessing or to analyze diffusion properties along the fiber tracts. Currently, the field is in critical need of a coherent end-to-end toolset for performing an along-fiber tract analysis, accessible to non-technical neuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents a coherent, open source, end-to-end toolset for atlas fiber tract based DTI analysis encompassing DICOM data conversion, quality control, atlas building, fiber tractography, fiber parameterization, and statistical analysis of diffusion properties. Most steps utilize graphical user interfaces (GUI) to simplify interaction and provide an extensive DTI analysis framework for non-technical researchers/investigators. We illustrate the use of our framework on a small sample, cross sectional neuroimaging study of eight healthy 1-year-old children from the Infant Brain Imaging Study (IBIS) Network. In this limited test study, we illustrate the power of our method by quantifying the diffusion properties at 1 year of age on the genu and splenium fiber tracts.

UNC-Utah NA-MIC framework for DTI fiber tract analysis

PubMed Central

Verde, Audrey R.; Budin, Francois; Berger, Jean-Baptiste; Gupta, Aditya; Farzinfar, Mahshid; Kaiser, Adrien; Ahn, Mihye; Johnson, Hans; Matsui, Joy; Hazlett, Heather C.; Sharma, Anuja; Goodlett, Casey; Shi, Yundi; Gouttard, Sylvain; Vachet, Clement; Piven, Joseph; Zhu, Hongtu; Gerig, Guido; Styner, Martin

2014-01-01

Diffusion tensor imaging has become an important modality in the field of neuroimaging to capture changes in micro-organization and to assess white matter integrity or development. While there exists a number of tractography toolsets, these usually lack tools for preprocessing or to analyze diffusion properties along the fiber tracts. Currently, the field is in critical need of a coherent end-to-end toolset for performing an along-fiber tract analysis, accessible to non-technical neuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents a coherent, open source, end-to-end toolset for atlas fiber tract based DTI analysis encompassing DICOM data conversion, quality control, atlas building, fiber tractography, fiber parameterization, and statistical analysis of diffusion properties. Most steps utilize graphical user interfaces (GUI) to simplify interaction and provide an extensive DTI analysis framework for non-technical researchers/investigators. We illustrate the use of our framework on a small sample, cross sectional neuroimaging study of eight healthy 1-year-old children from the Infant Brain Imaging Study (IBIS) Network. In this limited test study, we illustrate the power of our method by quantifying the diffusion properties at 1 year of age on the genu and splenium fiber tracts. PMID:24409141

Ultrahigh resolution radiation imaging system using an optical fiber structure scintillator plate.

PubMed

Yamamoto, Seiichi; Kamada, Kei; Yoshikawa, Akira

2018-02-16

High resolution imaging of radiation is required for such radioisotope distribution measurements as alpha particle detection in nuclear facilities or high energy physics experiments. For this purpose, we developed an ultrahigh resolution radiation imaging system using an optical fiber structure scintillator plate. We used a ~1-μm diameter fiber structured GdAlO 3 :Ce (GAP) /α-Al 2 O 3 scintillator plate to reduce the light spread. The fiber structured scintillator plate was optically coupled to a tapered optical fiber plate to magnify the image and combined with a lens-based high sensitivity CCD camera. We observed the images of alpha particles with a spatial resolution of ~25 μm. For the beta particles, the images had various shapes, and the trajectories of the electrons were clearly observed in the images. For the gamma photons, the images also had various shapes, and the trajectories of the secondary electrons were observed in some of the images. These results show that combining an optical fiber structure scintillator plate with a tapered optical fiber plate and a high sensitivity CCD camera achieved ultrahigh resolution and is a promising method to observe the images of the interactions of radiation in a scintillator.

Fracture surface analysis in composite and titanium bonding

NASA Technical Reports Server (NTRS)

Devilbiss, T. A.; Wightman, J. P.

1985-01-01

To understand the mechanical properties of fiber-reinforced composite materials, it is necessary to understand the mechanical properties of the matrix materials and of the reinforcing fibers. Another factor that can affect the mechanical properties of a composite material is the interaction between the fiber and the matrix. In general, composites with strong fiber matrix bonding will give higher modulus, lower toughness composites. Composites with weak bonding will have a lower modulus and more ductility. The situation becomes a bit more complex when all possibilities are examined. To be considered are the following: the properties of the surface layer on the fiber, the interactive forces between polymer and matrix, the surface roughness and porosity of the fiber, and the morphology of the matrix polymer at the fiber surface. In practice, the surface of the fibers is treated to enhance the mechanical properties of a composite. These treatments include anodization, acid etching, high temperature oxidation, and plasma oxidation, to name a few. The goal is to be able to predict the surface properties of carbon fibers treated in various ways, and then to relate surface properties to fiber matrix bonding.

Using graphene nano-particle embedded in photonic crystal fiber for evanescent wave mode-locking of fiber laser.

PubMed

Lin, Yung-Hsiang; Yang, Chun-Yu; Liou, Jia-Hong; Yu, Chin-Ping; Lin, Gong-Ru

2013-07-15

A photonic crystal fiber (PCF) with high-quality graphene nano-particles uniformly dispersed in the hole cladding are demonstrated to passively mode-lock the erbium-doped fiber laser (EDFL) by evanescent-wave interaction. The few-layer graphene nano-particles are obtained by a stabilized electrochemical exfoliation at a threshold bias. These slowly and softly exfoliated graphene nano-particle exhibits an intense 2D band and an almost disappeared D band in the Raman scattering spectrum. The saturable phenomena of the extinction coefficient β in the cladding provides a loss modulation for the intracavity photon intensity by the evanescent-wave interaction. The evanescent-wave mode-locking scheme effectively enlarges the interaction length of saturable absorption with graphene nano-particle to provide an increasing transmittance ΔT of 5% and modulation depth of 13%. By comparing the core-wave and evanescent-wave mode-locking under the same linear transmittance, the transmittance of the graphene nano-particles on the end-face of SMF only enlarges from 0.54 to 0.578 with ΔT = 3.8% and the modulation depth of 10.8%. The evanescent wave interaction is found to be better than the traditional approach which confines the graphene nano-particles at the interface of two SMF patchcords. When enlarging the intra-cavity gain by simultaneously increasing the pumping current of 980-nm and 1480-nm pumping laser diodes (LDs) to 900 mA, the passively mode-locked EDFL shortens its pulsewidth to 650 fs and broadens its spectral linewidth to 3.92 nm. An extremely low carrier amplitude jitter (CAJ) of 1.2-1.6% is observed to confirm the stable EDFL pulse-train with the cladding graphene nano-particle based evanescent-wave mode-locking.

Method and apparatus for detecting neutrons

DOEpatents

Perkins, R.W.; Reeder, P.L.; Wogman, N.A.; Warner, R.A.; Brite, D.W.; Richey, W.C.; Goldman, D.S.

1997-10-21

The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO{sub 2} with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. 5 figs.

Method and apparatus for detecting neutrons

DOEpatents

Perkins, Richard W.; Reeder, Paul L.; Wogman, Ned A.; Warner, Ray A.; Brite, Daniel W.; Richey, Wayne C.; Goldman, Don S.

1997-01-01

The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO.sub.2 with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation.

Fiber intake modulates the association of alcohol intake with breast cancer.

PubMed

Romieu, Isabelle; Ferrari, Pietro; Chajès, Veronique; de Batlle, Jordi; Biessy, Carine; Scoccianti, Chiara; Dossus, Laure; Christine Boutron, Marie; Bastide, Nadia; Overvad, Kim; Olsen, Anja; Tjønneland, Anne; Kaaks, Rudolf; Boeing, Heiner; Trichopoulou, Antonia; Lagiou, Pagona; Trichopoulos, Dimitrios; Palli, Domenico; Sieri, Sabina; Tumino, Rosario; Vineis, Paolo; Panico, Salvatore; Bueno-de-Mesquita, H B As; Gils, Carla H; Peeters, Petra H; Lund, Eiliv; Skeie, Guri; Weiderpass, Elisabete; Ramón Quirós, J; Chirlaque, María-Dolores; Ardanaz, Eva; Sánchez, María-José; Duell, Eric J; Amiano Etxezarreta, Pilar; Borgquist, Signe; Hallmans, Göran; Johansson, Ingegerd; Maria Nilsson, Lena; Khaw, Kay-Tee; Wareham, Nick; Key, Timothy J; Travis, Ruth C; Murphy, Neil; Wark, Petra A; Riboli, Elio

2017-01-15

Alcohol intake has been related to an increased risk of breast cancer (BC) while dietary fiber intake has been inversely associated to BC risk. A beneficial effect of fibers on ethanol carcinogenesis through their impact on estrogen levels is still controversial. We investigated the role of dietary fiber as a modifying factor of the association of alcohol and BC using data from the European Prospective Investigation into Cancer and Nutrition (EPIC). This study included 334,850 women aged 35-70 years at baseline enrolled in the ten countries of the EPIC study and followed up for 11.0 years on average. Information on fiber and alcohol intake at baseline and average lifetime alcohol intake were calculated from country-specific dietary and lifestyle questionnaires. Hazard ratios (HR) of developing invasive BC according to different levels of alcohol and fiber intake were computed. During 3,670,439 person-years, 11,576 incident BC cases were diagnosed. For subjects with low intake of fiber (<18.5 g/day), the risk of BC per 10 g/day of alcohol intake was 1.06 (1.03-1.08) while among subjects with high intake of fiber (>24.2 g/day) the risk of BC was 1.02 (0.99-1.05) (test for interaction p = 0.011). This modulating effect was stronger for fiber from vegetables. Our results suggest that fiber intake may modulate the positive association of alcohol intake and BC. Alcohol is well known to increase the risk for BC, while a fiber-rich diet has the opposite effect. Here the authors find a significant interaction between both lifestyle factors indicating that high fiber intake can ease the adverse effects associated with alcohol consumption. Consequently, women with high alcohol intake and low fiber intake (<18.5 g/day) had the highest risk for BC. Specific benefits were associated with fibers from vegetable, warranting further investigations into specific fiber sources and their mechanistic interactions with alcohol-induced BC risk. © 2016 UICC.

Detection of deoxynivalenol using biolayer interferometry

USDA-ARS?s Scientific Manuscript database

Biolayer interferometry allows for the real time monitoring of the interactions between molecules without the need for reagents with enzymatic, fluorescent, or radioactive labels. The technology is based upon the changes in interference pattern of light reflected from the surface of an optical fiber...

Flexible fiber in interaction with a dense granular flow close to the jamming transition

NASA Astrophysics Data System (ADS)

Algarra, Nicolas; Leang, Marguerite; Lazarus, Arnaud; Vandembroucq, Damien; Kolb, Evelyne

2017-06-01

We propose a new fluid/structure interaction in the unusual case of a dense granular medium flowing against an elastic fiber acting as a flexible intruder. We study experimentally the reconfiguration and the forces exerted on the flexible fiber produced by the flow at a constant and low velocity of a two-dimensional disordered packing of grains close but below the jamming transition.

Non-Neoplastic and Neoplastic Pleural Endpoints Following Fiber Exposure

PubMed Central

Broaddus, V. Courtney; Everitt, Jeffrey I.; Black, Brad; Kane, Agnes B.

2011-01-01

Exposure to asbestos fibers is associated with non-neoplastic pleural diseases including plaques, fibrosis, and benign effusions, as well as with diffuse malignant pleural mesothelioma. Translocation and retention of fibers are fundamental processes in understanding the interactions between the dose and dimensions of fibers retained at this anatomic site and the subsequent pathological reactions. The initial interaction of fibers with target cells in the pleura has been studied in cellular models in vitro and in experimental studies in vivo. The proposed biological mechanisms responsible for non-neoplastic and neoplastic pleural diseases and the physical and chemical properties of asbestos fibers relevant to these mechanisms are critically reviewed. Understanding mechanisms of asbestos fiber toxicity may help us anticipate the problems from future exposures both to asbestos and to novel fibrous materials such as nanotubes. Gaps in our understanding have been outlined as guides for future research. PMID:21534088

Grating-flanked plasmonic coaxial apertures for efficient fiber optical tweezers.

PubMed

Saleh, Amr A E; Sheikhoelislami, Sassan; Gastelum, Steven; Dionne, Jennifer A

2016-09-05

Subwavelength plasmonic apertures have been foundational for direct optical manipulation of nanoscale specimens including sub-100 nm polymeric beads, metallic nanoparticles and proteins. While most plasmonic traps result in two-dimensional localization, three-dimensional manipulation has been demonstrated by integrating a plasmonic aperture on an optical fiber tip. However, such 3D traps are usually inefficient since the optical mode of the fiber and the subwavelength aperture only weakly couple. In this paper we design more efficient optical-fiber-based plasmonic tweezers combining a coaxial plasmonic aperture with a plasmonic grating coupler at the fiber tip facet. Using full-field finite difference time domain analysis, we optimize the grating design for both gold and silver fiber-based coaxial tweezers such that the optical transmission through the apertures is maximized. With the optimized grating, we show that the maximum transmission efficiency increases from 2.5% to 19.6% and from 1.48% to 16.7% for the gold and silver structures respectively. To evaluate their performance as optical tweezers, we calculate the optical forces and the corresponding trapping potential on dielectric particles interacting with the apertures. We demonstrate that the enahncement in the transmission translates into an equivalent increase in the optical forces. Consequently, the optical power required to achieve stable optical trapping is significantly reduced allowing for efficient localization and 3D manipulation of sub-30 nm dielectric particles.

AFOSR Indo-UK -US Joint Physics Initiative for Study of Angular Optical Mode Fiber Amplification

DTIC Science & Technology

2017-02-20

AFRL -AFOSR-UK-TR-2017-0011 AFOSR Indo-UK -US Joint Physics Initiative for study of angular optical mode fiber amplification Johan Nilsson UNIVERSITY...ES) EOARD Unit 4515 APO AE 09421-4515 10. SPONSOR/MONITOR’S ACRONYM(S) AFRL /AFOSR IOE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) AFRL -AFOSR-UK-TR-2017-0011...this travel, he had the opportunity to visit the Kirtland Air Force Base and interact with Dr Leanne Henry as well as Dr Iyad Dajani to discuss

Multimerization of Adenovirus Serotype 3 Fiber Knob Domains Is Required for Efficient Binding of Virus to Desmoglein 2 and Subsequent Opening of Epithelial Junctions▿

PubMed Central

Wang, Hongjie; Li, ZongYi; Yumul, Roma; Lara, Stephanie; Hemminki, Akseli; Fender, Pascal; Lieber, André

2011-01-01

Recently, we identified desmoglein 2 (DSG2) as the main receptor for a group of species B adenoviruses (Ads), including Ad3, a serotype that is widely distributed in the human population (H. Wang et al., Nat. Med. 17:96–104, 2011). In this study, we have attempted to delineate structural details of the Ad3 interaction with DSG2. For CAR- and CD46-interacting Ad serotypes, attachment to cells can be completely blocked by an excess of recombinant fiber knob protein, while soluble Ad3 fiber knob only inefficiently blocks Ad3 infection. We found that the DSG2-interacting domain(s) within Ad3 is formed by several fiber knob domains that have to be in the spatial constellation that is present in viral particles. Based on this finding, we generated a small recombinant, self-dimerizing protein containing the Ad3 fiber knob (Ad3-K/S/Kn). Ad3-K/S/Kn bound to DSG2 with high affinity and blocked Ad3 infection. We demonstrated by confocal immunofluorescence and transmission electron microscopy analyses that Ad3-K/S/Kn, through its binding to DSG2, triggered the transient opening of intercellular junctions in epithelial cells. The pretreatment of epithelial cells with Ad3-K/S/Kn resulted in increased access to receptors that are localized in or masked by epithelial junctions, e.g., CAR or Her2/neu. Ad3-K/S/Kn treatment released CAR from tight junctions and thus increased the transduction of epithelial cells by a serotype Ad5-based vector. Furthermore, the pretreatment of Her2/neu-positive breast cancer cells with Ad3-K/S/Kn increased the killing of cancer cells by the Her2/neu-targeting monoclonal antibody trastuzumab (Herceptin). This study widens our understanding of how Ads achieve high avidity to their receptors and the infection of epithelial tissue. The small recombinant protein Ad3-K/S/Kn has practical implications for the therapy of epithelial cancer and gene/drug delivery to normal epithelial tissues. PMID:21525338

Fuel level sensor based on polymer optical fiber Bragg gratings for aircraft applications

NASA Astrophysics Data System (ADS)

Marques, C. A. F.; Pospori, A.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

2016-04-01

Safety in civil aviation is increasingly important due to the increase in flight routes and their more challenging nature. Like other important systems in aircraft, fuel level monitoring is always a technical challenge. The most frequently used level sensors in aircraft fuel systems are based on capacitive, ultrasonic and electric techniques, however they suffer from intrinsic safety concerns in explosive environments combined with issues relating to reliability and maintainability. In the last few years, optical fiber liquid level sensors (OFLLSs) have been reported to be safe and reliable and present many advantages for aircraft fuel measurement. Different OFLLSs have been developed, such as the pressure type, float type, optical radar type, TIR type and side-leaking type. Amongst these, many types of OFLLSs based on fiber gratings have been demonstrated. However, these sensors have not been commercialized because they exhibit some drawbacks: low sensitivity, limited range, long-term instability, or limited resolution. In addition, any sensors that involve direct interaction of the optical field with the fuel (either by launching light into the fuel tank or via the evanescent field of a fiber-guided mode) must be able to cope with the potential build up of contamination - often bacterial - on the optical surface. In this paper, a fuel level sensor based on microstructured polymer optical fiber Bragg gratings (mPOFBGs), including poly (methyl methacrylate) (PMMA) and TOPAS fibers, embedded in diaphragms is investigated in detail. The mPOFBGs are embedded in two different types of diaphragms and their performance is investigated with aviation fuel for the first time, in contrast to our previous works, where water was used. Our new system exhibits a high performance when compared with other previously published in the literature, making it a potentially useful tool for aircraft fuel monitoring.

LiNbO3 Cylinder Fiber

NASA Technical Reports Server (NTRS)

2004-01-01

We have successfully fabricate optical fiber with a thin layer of LiNbO3 at the boundary of the glass core and dear glass cladding. The construction of this fiber is based on our successful Semiconductor Cylinder Fibers (SCF). A schematic representation of a LiNbO3 Cylinder Fiber is shown. These fibers can be used as light modulators, sonar detectors and in other applications. The core diameter of the fiber is sufficiently small compared to the light wavelength and the indices of refraction of the core and cladding glasses are sufficiently close in value so that there is sufficient light at the core cladding boundary to interact with the LiNbO3 layer. This fiber functions best when just a single light mode propagates through the fiber. The idea for a LiNbO3 Cylinder Fiber came from Dr. Tracee Jamison of NASA. The optical properties of LiNbO3 can be changed with strain or the application of an electric field. Thus these fibers can be used as acoustic sensors as for example in a sonar. They can also be used as electric field operated light modulators. However, for this application the fibers would be made with a cross section in the form of a 'D'. The core with its surrounding LiNbO, layer would be close to the flat portion of the 'D' shaped fiber. Two metal contacts would be deposited on the flat portion of the fiber on either side of the core. A voltage applied across these contacts will result in an electric field in the core region that can be used for modulating the optical properties of the LiNbO, layer. To our knowledge this is the first ever LiNbO, Cylinder Fiber made.

LiNbO3 Cylinder Fiber

NASA Technical Reports Server (NTRS)

Kornreich, Philip

2004-01-01

We have successfully fabricate optical fiber with a thin layer of LiNbO3 at the boundary of the glass core and clear glass cladding. The construction of this fiber is based on our successful Semiconductor Cylinder Fibers (SCF). A schematic representation of a LiN bo, Cylinder Fiber. These fibers can be used as light modulators, sonar detectors and in other applications. The core diameter of the fiber is sufficiently small compared to the light wavelength and the indices of refraction of the core and cladding glasses are sufficiently close in value so that there is sufficient light at the core cladding boundary to interact with the LiNbO3 layer. This fiber functions best when just a single light mode propagates through the fiber. The idea for a LiNbO3 Cylinder Fiber came from Dr. Tracee Jamison of NASA. The optical properties of LiNbO3 can be changed with strain or the application of an electric field. Thus these fibers can be used as acoustic sensors as for example in a sonar. They can also be used as electric field operated light modulators. However, for this application the fibers would be made with a cross section in the form of a "D". The core with its surrounding LiNbO, layer would be close to the flat portion of the "D" shaped fiber. Two metal contacts would be deposited on the flat portion of the fiber on either side of the core. A voltage applied across these contacts will result in an electric field in the core region that can be used for modulating the optical properties of the LiNbO3 layer. To our knowledge this is the first ever LiNbO3 Cylinder Fiber made.

Modified Hyperbranched Polymers for Fluorescence Sensing Applications

DTIC Science & Technology

2012-06-01

sensors. The HBPs transported the fluorescent groups to the fiber mat surface where they interacted with mercury (Hg(II)) or cytochrome c as the analyte...coworkers (27, 28) have employed fluorescence quenching using a binol-based dendrimer sensor, which exhibited differential sensitivity to enantiomeric...based sensors using HBP-based fluorophores was demonstrated in this report. Low concentrations of fluorophore were transported to the surface of

On the inter-stitch interaction in biaxial non-crimp fabrics

NASA Astrophysics Data System (ADS)

Colin, David; Bel, Sylvain; Hans, Thorsten; Hartmann, Mathias

2018-05-01

Simulation models of fiber reinforcements at the scale of fibers possibly reproduce important deformation mechanisms and can offer predictive capabilities on the macroscopic mechanical behavior. Although potential deformation mechanisms are already listed in the literature, these phenomena should be experimentally investigated to evaluate their relevance in simulation at the scale of fibers. This study focuses on the inter-stitch interaction of Non-Crimp Fabric (NCF) and aims at quantifying the relative motion of the stitching yarns. To this end, controlled shear deformation was introduced on +/-45° biaxial tricot stitched NCF. The stitching yarns have been colored on the backside of the sample while the front face remained uncolored. Therefore, an inter-stitch relative motion can be observed if an uncolored portion of the stitching yarn appears on the back face of the sample. The samples were observed during the experiments with a digital microscope in order to measure the uncolored portion of the yarns on the back face. Thus, the stitching yarn movement can be quantified for various shear angles. A significant relative motion was observed compared to the original stitching length. Based on this study, the authors argue that the inter-stitch sliding is a relevant deformation mechanism for biaxial tricot stitched NCF at the scale of fibers.

Observation of orbital angular momentum transfer between acoustic and optical vortices in optical fiber.

PubMed

Dashti, Pedram Z; Alhassen, Fares; Lee, Henry P

2006-02-03

Acousto-optic interaction in optical fiber is examined from the perspective of copropagating optical and acoustic vortex modes. Calculation of the acousto-optic coupling coefficient between different optical modes leads to independent conservation of spin and orbital angular momentum of the interacting photons and phonons. We show that the orbital angular momentum of the acoustic vortex can be transferred to a circularly polarized fundamental optical mode to form a stable optical vortex in the fiber carrying orbital angular momentum. The technique provides a useful way of generating stable optical vortices in the fiber medium.

The Scintillating Optical Fiber Calorimeter Instrument Performance (SOFCAL)

NASA Technical Reports Server (NTRS)

Christl, M. J.; Benson, C. M.; Berry, F. A.; Fountain, W. F.; Gregory, J. C.; Johnson, J. S.; Munroe, R. B.; Parnell, T. A.; Takahashi, Y.; Watts, J. W.

1999-01-01

SOFCAL is a balloon-borne instrument designed to measure the P-He cosmic ray spectra from about 200 GeV/amu - 20 TeV/amu. SOFCAL uses a thin lead and scintillating-fiber ionization calorimeter to measure the cascades produced by cosmic rays interacting in the hybrid detector system. Above the fiber calorimeter is an emulsion chamber that provides the interaction target, primary particle identification and in-flight energy calibration for the scintillating fiber data. The energy measurement technique and its calibration are described, and the present results from the analysis of a 1 day balloon flight will be presented.

Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks

PubMed Central

Tuan, Juan; Chen, Ying-Xuan

2016-01-01

Background Diets and lifestyles have been strongly associated with colorectal cancer (CRC). In the past several decades, emerging evidence has suggested that the gut microbiota may have a role in the development of CRC. Its interaction with diets and lifestyles could affect the carcinogenesis of CRC. Summary This review presents the most recent epidemiologic and experimental evidence of three factors that may convincingly have a role in CRC, including fiber, red or processed meat, and alcohol, focusing on potential mechanisms and their interactions with the gut microbiota. Key Message High consumption of fiber, low consumption of red or processed red meat as well as minimizing alcohol intake have been associated with a lower risk of CRC. Many microbial metabolites formed from those three substances may mediate the microbial diversity and the composition and abundance of the gut microbiota, which eventually affects the balance between health and disease, including CRC. Practical Implications Based on our synthetic review, clinicians may probably offer some recommendations and explanations to their patients who may want to modulate their diet and lifestyle to prevent CRC. As an easily modifiable environmental factor, it may be possible that applying dietary or lifestyle intervention could effectively protect against the development of CRC in the future. PMID:27722153

Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks.

PubMed

Tuan, Juan; Chen, Ying-Xuan

2016-09-01

Diets and lifestyles have been strongly associated with colorectal cancer (CRC). In the past several decades, emerging evidence has suggested that the gut microbiota may have a role in the development of CRC. Its interaction with diets and lifestyles could affect the carcinogenesis of CRC. This review presents the most recent epidemiologic and experimental evidence of three factors that may convincingly have a role in CRC, including fiber, red or processed meat, and alcohol, focusing on potential mechanisms and their interactions with the gut microbiota. High consumption of fiber, low consumption of red or processed red meat as well as minimizing alcohol intake have been associated with a lower risk of CRC. Many microbial metabolites formed from those three substances may mediate the microbial diversity and the composition and abundance of the gut microbiota, which eventually affects the balance between health and disease, including CRC. Based on our synthetic review, clinicians may probably offer some recommendations and explanations to their patients who may want to modulate their diet and lifestyle to prevent CRC. As an easily modifiable environmental factor, it may be possible that applying dietary or lifestyle intervention could effectively protect against the development of CRC in the future.

Aligned fibers direct collective cell migration to engineer closing and nonclosing wound gaps

PubMed Central

Sharma, Puja; Ng, Colin; Jana, Aniket; Padhi, Abinash; Szymanski, Paige; Lee, Jerry S. H.; Behkam, Bahareh; Nain, Amrinder S.

2017-01-01

Cell emergence onto damaged or organized fibrous extracellular matrix (ECM) is a crucial precursor to collective cell migration in wound closure and cancer metastasis, respectively. However, there is a fundamental gap in our quantitative understanding of the role of local ECM size and arrangement in cell emergence–based migration and local gap closure. Here, using ECM-mimicking nanofibers bridging cell monolayers, we describe a method to recapitulate and quantitatively describe these in vivo behaviors over multispatial (single cell to cell sheets) and temporal (minutes to weeks) scales. On fiber arrays with large interfiber spacing, cells emerge (invade) either singularly by breaking cell–cell junctions analogous to release of a stretched rubber band (recoil), or in groups of few cells (chains), whereas on closely spaced fibers, multiple chains emerge collectively. Advancing cells on fibers form cell streams, which support suspended cell sheets (SCS) of various sizes and curvatures. SCS converge to form local gaps that close based on both the gap size and shape. We document that cell stream spacing of 375 µm and larger hinders SCS advancement, thus providing abilities to engineer closing and nonclosing gaps. Altogether we highlight the importance of studying cell-fiber interactions and matrix structural remodeling in fundamental and translational cell biology. PMID:28747440

Effect of dietary fiber on the level of free angiotensin II receptor blocker in vitro.

PubMed

Iwazaki, Ayano; Takahashi, Kazuhiro; Tamezane, Yui; Tanaka, Kenta; Nakagawa, Minami; Imai, Kimie; Nakanishi, Kunio

2014-01-01

The interaction between angiotensin II type 1 (AT1) receptor blockers (ARBs), such as losartan potassium (LO), candesartan (CA), and telmisartan (TE), and dietary fiber was studied as to the level of free ARB in vitro. When ARB was incubated with soluble (sodium alginate, pectin, and glucomannan) or insoluble (cellulose and chitosan) dietary fiber, the levels of free LO, TE, and CA decreased. This resulted only from mixing the dietary fiber with the ARBs and differed among the types of dietary fiber, and the pH and electrolytes in the mixture. The levels of free LO and TE tended to decrease with a higher concentration of sodium chloride in pH 1.2 fluid. These results suggest that it is important to pay attention to the possible interactions between ARBs and dietary fiber.

The Interaction between Dietary Fiber and Fat and Risk of Colorectal Cancer in the Women’s Health Initiative

PubMed Central

Navarro, Sandi L.; Neuhouser, Marian L.; Cheng, Ting-Yuan David; Tinker, Lesley F.; Shikany, James M.; Snetselaar, Linda; Martinez, Jessica A.; Kato, Ikuko; Beresford, Shirley A. A.; Chapkin, Robert S.; Lampe, Johanna W.

2016-01-01

Combined intakes of specific dietary fiber and fat subtypes protect against colon cancer in animal models. We evaluated associations between self-reported individual and combinations of fiber (insoluble, soluble, and pectins, specifically) and fat (omega-6, omega-3, and docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), specifically) and colorectal cancer (CRC) risk in the Women’s Health Initiative prospective cohort (n = 134,017). During a mean 11.7 years (1993–2010), 1952 incident CRC cases were identified. Cox regression models computed multivariate adjusted hazard ratios to estimate the association between dietary factors and CRC risk. Assessing fiber and fat individually, there was a modest trend for lower CRC risk with increasing intakes of total and insoluble fiber (p-trend 0.09 and 0.08). An interaction (p = 0.01) was observed between soluble fiber and DHA + EPA, with protective effects of DHA + EPA with lower intakes of soluble fiber and an attenuation at higher intakes, however this association was no longer significant after correction for multiple testing. These results suggest a modest protective effect of higher fiber intake on CRC risk, but not in combination with dietary fat subtypes. Given the robust results in preclinical models and mixed results in observational studies, controlled dietary interventions with standardized intakes are needed to better understand the interaction of specific fat and fiber subtypes on colon biology and ultimately CRC susceptibility in humans. PMID:27916893

Multifunctional Polymer Nanofibers: UV Emission, Optical Gain, Anisotropic Wetting, and High Hydrophobicity for Next Flexible Excitation Sources

PubMed Central

2015-01-01

The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures that are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials are desired to feature a number of opto-mechanical properties, including brightness, optical gain for being used in laser devices, flexibility to conform with different lab-on-chip architectures, and tailorable wettability to control and minimize their interaction with ambient humidity and fluids. In this work, we introduce multifunctional, UV-emitting electrospun fibers with both optical gain and greatly enhanced anisotropic hydrophobicity compared to films. Fibers are described by the onset of a composite wetting state, and their arrangement in uniaxial arrays further favors liquid directional control. The low gain threshold, optical losses, plastic nature, flexibility, and stability of these UV-emitting fibers make them interesting for building light-emitting devices and microlasers. Furthermore, the anisotropic hydrophobicity found is strongly synergic with optical properties, reducing interfacial interactions with liquids and enabling smart functional surfaces for droplet microfluidic and wearable applications. PMID:26401889

Ultrafast Fabry-Perot fiber-optic pressure sensors for multimedia blast event measurements.

PubMed

Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Yang; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2013-02-20

A shock wave (SW) is characterized as a large pressure fluctuation that typically lasts only a few milliseconds. On the battlefield, SWs pose a serious threat to soldiers who are exposed to explosions, which may lead to blast-induced traumatic brain injuries. SWs can also be used beneficially and have been applied to a variety of medical treatments due to their unique interaction with tissues and cells. Consequently, it is important to have sensors that can quantify SW dynamics in order to better understand the physical interaction between body tissue and the incident acoustic wave. In this paper, the ultrafast fiber-optic sensor based on the Fabry-Perot interferometric principle was designed and four such sensors were fabricated to quantify a blast event within different media, simultaneously. The compact design of the fiber-optic sensor allows for a high degree of spatial resolution when capturing the wavefront of the traveling SW. Several blast event experiments were conducted within different media (e.g., air, rubber membrane, and water) to evaluate the sensor's performance. This research revealed valuable knowledge for further study of SW behavior and SW-related applications.

Polarization chaos and random bit generation in nonlinear fiber optics induced by a time-delayed counter-propagating feedback loop.

PubMed

Morosi, J; Berti, N; Akrout, A; Picozzi, A; Guasoni, M; Fatome, J

2018-01-22

In this manuscript, we experimentally and numerically investigate the chaotic dynamics of the state-of-polarization in a nonlinear optical fiber due to the cross-interaction between an incident signal and its intense backward replica generated at the fiber-end through an amplified reflective delayed loop. Thanks to the cross-polarization interaction between the two-delayed counter-propagating waves, the output polarization exhibits fast temporal chaotic dynamics, which enable a powerful scrambling process with moving speeds up to 600-krad/s. The performance of this all-optical scrambler was then evaluated on a 10-Gbit/s On/Off Keying telecom signal achieving an error-free transmission. We also describe how these temporal and chaotic polarization fluctuations can be exploited as an all-optical random number generator. To this aim, a billion-bit sequence was experimentally generated and successfully confronted to the dieharder benchmarking statistic tools. Our experimental analysis are supported by numerical simulations based on the resolution of counter-propagating coupled nonlinear propagation equations that confirm the observed behaviors.

Handsheet formation and mechanical testing via fiber-level simulations

Treesearch

Leonard H. Switzer; Daniel J. Klingenberg; C. Tim Scott

2004-01-01

A fiber model and simulation method are employed to investigate the mechanical response of planar fiber networks subjected to elongational deformation. The simulated responses agree qualitatively with numerous experimental observations. suggesting that such simulation methods may be useful for probing the relationships between fiber properties and interactions and the...

NRL Review, 2002

DTIC Science & Technology

2002-05-01

technology for polarization-maintaining fiber amplification and an ultrashort pulsed fiber laser to Calmar Optcom. Calmar Optcom will be manufacturing...June 1995. This facility is made up of 56 laser beams and is single pulsed (4 nanosecond pulse ). This facil- ity provides intense radiation for studying...plasma interactions, in- tense laser -electron beam interactions, and intense laser -matter interactions. The division is building a repetitively pulsed (5

Optimization of ultrasonic-assisted preparation of dietary fiber from corn pericarp using response surface methodology.

PubMed

Wang, Anna; Wu, Ligen; Li, Xiulin

2013-09-01

Corn pericarp, which is an industrial waste of corn starch production, is an important source of dietary fiber in cereals, with claimed health benefits. However, they used to be discarded or utilized as animal feed. The application of pre-ultrasound treatment is critical for achieving rapid preparation of desired components from plant materials and for preserving structural and molecular properties of these compounds. Ultrasonic-assisted preparation was used to produce dietary fiber from corn pericarp using response surface methodology. The optimal particle size of corn pericarp (mesh size 40), the ratio of liquid to solid (25 mL g⁻¹), ultrasonic power (180 W) and ultrasonic time (80 min) were determined based on response surface methodology analysis. The interaction effects of particle size of corn pericarp and ultrasonic time had a highlysignificant effect on the yield of dietary fiber, and a significant effect was shown by ultrasonic power and ultrasonic time. The maximum yield of dietary fiber was 86.84%, which agreed closely with the predicted value. Using ultrasonic-assisted preparation, it may be possible to enhance the yield of dietary fiber from corn pericarp. © 2013 Society of Chemical Industry.

Al-Coated Conductive Fiber Filters for High-Efficiency Electrostatic Filtration: Effects of Electrical and Fiber Structural Properties.

PubMed

Choi, Dong Yun; An, Eun Jeong; Jung, Soo-Ho; Song, Dong Keun; Oh, Yong Suk; Lee, Hyung Woo; Lee, Hye Moon

2018-04-10

Through the direct decomposition of an Al precursor ink AlH 3 {O(C 4 H 9 ) 2 }, we fabricated an Al-coated conductive fiber filter for the efficient electrostatic removal of airborne particles (>99%) with a low pressure drop (~several Pascals). The effects of the electrical and structural properties of the filters were investigated in terms of collection efficiency, pressure drop, and particle deposition behavior. The collection efficiency did not show a significant correlation with the extent of electrical conductivity, as the filter is electrostatically charged by the metallic Al layers forming electrical networks throughout the fibers. Most of the charged particles were collected via surface filtration by Coulombic interactions; consequently, the filter thickness had little effect on the collection efficiency. Based on simulations of various fiber structures, we found that surface filtration can transition to depth filtration depending on the extent of interfiber distance. Therefore, the effects of structural characteristics on collection efficiency varied depending on the degree of the fiber packing density. This study will offer valuable information pertaining to the development of a conductive metal/polymer composite air filter for an energy-efficient and high-performance electrostatic filtration system.

PLLA-PHB fiber membranes obtained by solvent-free electrospinning for short-time drug delivery.

PubMed

Cao, K; Liu, Y; Olkhov, A A; Siracusa, V; Iordanskii, A L

2018-02-01

Fibers of poly(L-lactic acid) (PLLA)/polyhydroxybutyrate (PHB) with different concentrations of the drug dipyridamole (DPD) were prepared using solvent-free melt electrospinning to obtain a polymeric drug delivery system. The electrospun fibers were morphologically, structurally, thermally, and dynamically characterized. Crazes that resemble lotus root crevices were interestingly observed in the 7:3 PLLA/PHB fibers with 1% DPD. The crystallinity of PLLA slightly decreased as PHB was incorporated, and the addition of DPD significantly reduced the melting temperature of the composite. The interactions between PLLA and PHB mainly occurred at a proportion of 7:3, and drug encapsulation in the fibers was verified. The kinetic profiles of drug release demonstrated the predominant multiple patterns involving a diffusional stage in the short-term mode of release and kinetic process related to the hydrolysis of the biopolymers. Furthermore, the dynamic behavior of the polymer molecules was evaluated based on the segmental mobility using probe electron spin resonance spectroscopy. The segmental mobility in the amorphous fraction of PLLA decreased with increasing PLLA content. The 9:1 PLLA/PHB system was more resistant to polymer hydrolysis than to the 7:3 system and the rate of diffusion transport was approximately two times higher for the 7:3 PLLA/PHB fibers than for the 9:1 PLLA/PHB fibers.

Stochastic DT-MRI connectivity mapping on the GPU.

PubMed

McGraw, Tim; Nadar, Mariappan

2007-01-01

We present a method for stochastic fiber tract mapping from diffusion tensor MRI (DT-MRI) implemented on graphics hardware. From the simulated fibers we compute a connectivity map that gives an indication of the probability that two points in the dataset are connected by a neuronal fiber path. A Bayesian formulation of the fiber model is given and it is shown that the inversion method can be used to construct plausible connectivity. An implementation of this fiber model on the graphics processing unit (GPU) is presented. Since the fiber paths can be stochastically generated independently of one another, the algorithm is highly parallelizable. This allows us to exploit the data-parallel nature of the GPU fragment processors. We also present a framework for the connectivity computation on the GPU. Our implementation allows the user to interactively select regions of interest and observe the evolving connectivity results during computation. Results are presented from the stochastic generation of over 250,000 fiber steps per iteration at interactive frame rates on consumer-grade graphics hardware.

3D Finite Element Model for Writing Long-Period Fiber Gratings by CO2 Laser Radiation

PubMed Central

Coelho, João M. P.; Nespereira, Marta; Abreu, Manuel; Rebordão, José

2013-01-01

In the last years, mid-infrared radiation emitted by CO2 lasers has become increasing popular as a tool in the development of long-period fiber gratings. However, although the development and characterization of the resulting sensing devices have progressed quickly, further research is still necessary to consolidate functional models, especially regarding the interaction between laser radiation and the fiber's material. In this paper, a 3D finite element model is presented to simulate the interaction between laser radiation and an optical fiber and to determine the resulting refractive index change. Dependence with temperature of the main parameters of the optical fiber materials (with special focus on the absorption of incident laser radiation) is considered, as well as convection and radiation losses. Thermal and residual stress analyses are made for a standard single mode fiber, and experimental results are presented. PMID:23941908

FIBER AND INTEGRATED OPTICS: Radio-frequency electrooptic modulation in optical fibers

NASA Astrophysics Data System (ADS)

Bulyuk, A. N.

1992-10-01

The electrooptic interaction in single-mode optical fibers with both linear and circular birefringe is analyzed. In most cases, a large interaction length imposes a limit on the modulation frequency. A circular birefringence in an optical fiber may lead to an effective coupling of polarization normal modes if a phase-matching condition is satisfied. Through an appropriate choice of polarization states of the light at the entrance and exit of the device, one can achieve a polarization modulation or a frequency shift of the light. There are possible applications in rf polarization modulators, devices for shifting the frequency of light, and detectors of electromagnetic fields.

Theory of nematic order with aggregate dehydration for reversibly assembling proteins in concentrated solutions: Application to sickle-cell hemoglobin polymers

NASA Astrophysics Data System (ADS)

Hentschke, Reinhard; Herzfeld, Judith

1991-06-01

The reversible association of globular protein molecules in concentrated solution leads to highly polydisperse fibers, e.g., actin filaments, microtubules, and sickle-cell hemoglobin fibers. At high concentrations, excluded-volume interactions between the fibers lead to spontaneous alignment analogous to that in simple lyotropic liquid crystals. However, the phase behavior of reversibly associating proteins is complicated by the threefold coupling between the growth, alignment, and hydration of the fibers. In protein systems aggregates contain substantial solvent, which may cause them to swell or shrink, depending on osmotic stress. Extending previous work, we present a model for the equilibrium phase behavior of the above-noted protein systems in terms of simple intra- and interaggregate interactions, combined with equilibration of fiber-incorporated solvent with the bulk solvent. Specifically, we compare our model results to recent osmotic pressure data for sickle-cell hemoglobin and find excellent agreement. This comparison shows that particle interactions sufficient to cause alignment are also sufficient to squeeze significant amounts of solvent out of protein fibers. In addition, the model is in accord with findings from independent sedimentation and birefringence studies on sickle-cell hemoglobin.

Mechanical property enhancement of high conductive reduced graphene oxide fiber by a small loading of polydopamine

NASA Astrophysics Data System (ADS)

Zeng, Jie; Liu, Yuhang; Han, Di; Yu, Bowen; Deng, Sha; Chen, Feng; Fu, Qiang

2018-04-01

Improving the interaction of individual reduced graphene oxide sheet is an effective way to enhance the mechanical property of reduced graphene oxide fiber. In this study, to enhance the interaction forces of graphene sheets, large-sized graphene oxide sheets were used to assemble graphene fiber, and dopamine was mixed with the graphene oxide spinning drop. During the wet-spinning procedure, polydopamine was formed by polymerizing. It is found that such obtained composite fiber shows enhanced tensile strength (increased from 314 MPa to 527 MPa) and increased toughness (increased from 3.5 MJ m‑3 to 12.9 MJ m‑3) compared with pure reduced graphene oxide fiber. Fourier-transform infrared spectra, Raman spectra and x-ray photoelectron spectroscopy were performed to characterize the interaction between reduced graphene oxide sheets and polydopamine, and a possible enhancement mechanism of C-N bonds formation was proposed. It is suggested that this newly formed C‑N bonds can not only enhance the tensile strength, but also increase the elongation simultaneously. Additionally, the graphene fiber remains great electrical conductivity (33 100 s m‑1) since the conductive network can be maintained.

Spatiotemporal mode-locking in multimode fiber lasers

NASA Astrophysics Data System (ADS)

Wright, Logan G.; Christodoulides, Demetrios N.; Wise, Frank W.

2017-10-01

A laser is based on the electromagnetic modes of its resonator, which provides the feedback required for oscillation. Enormous progress has been made toward controlling the interactions of longitudinal modes in lasers with a single transverse mode. For example, the field of ultrafast science has been built on lasers that lock many longitudinal modes together to form ultrashort light pulses. However, coherent superposition of longitudinal and transverse modes in a laser has received little attention. We show that modal and chromatic dispersions in fiber lasers can be counteracted by strong spatial and spectral filtering. This allows locking of multiple transverse and longitudinal modes to create ultrashort pulses with a variety of spatiotemporal profiles. Multimode fiber lasers thus open new directions in studies of nonlinear wave propagation and capabilities for applications.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard.

PubMed

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than g free with g=2.002644=g free ·(1+162ppm) with a relative uncertainty of 15ppm. This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Aqueous contaminant detection via UiO-66 thin film optical fiber sensor platform with fast Fourier transform based spectrum analysis

NASA Astrophysics Data System (ADS)

Nazari, Marziyeh; Rubio-Martinez, Marta; Babarao, Ravichandar; Ayad Younis, Adel; Collins, Stephen F.; Hill, Matthew R.; Duke, Mikel C.

2018-01-01

Routine water quality monitoring is required in drinking and waste water management. A particular interest is to measure concentrations of a range of diverse contaminants on-site or remotely in real time. Here we present metal organic framework (MOF) integrated optical fiber sensor that allows for rapid optical measurement based on fast Fourier transform (FFT) spectrum analysis. The end-face of these glass optical fibers was modified with UiO-66(Zr) MOF thin film by in situ hydrothermal synthesis for the detection of the model contaminants, Rhodamine-B and 4-Aminopyridine, in water. The sensing mechanism is based on the change in the optical path length of the thin film induced by the adsorption of chemical molecules by UiO-66. Using FFT analysis, various modes of interaction (physical and chemical) became apparent, showing both irreversible changes upon contact with the contaminant, as well as reversible changes according to actual concentration. This was indicated by the second harmonic elevation to a certain level translating to high sensitivity detection.

Intermodal Parametric Frequency Conversion in Optical Fibers

NASA Astrophysics Data System (ADS)

Demas, Jeffrey D.

Lasers are an essential technology enabling countless fields of optics, however, their operation wavelengths are limited to isolated regions across the optical spectrum due to the need for suitable gain media. Parametric frequency conversion (PFC) is an attractive means to convert existing lasers to new colors using nonlinear optical interactions rather than the material properties of the host medium, allowing for the development of high power laser sources across the entire optical spectrum. PFC in bulk chi(2) crystals has led to the development of the optical parametric oscillator, which is currently the standard source for high power light at non-traditional wavelengths in the laboratory setting. Ideally, however, one could implement PFC in an optical fiber, thus leveraging the crucial benefits of a guided-wave geometry: alignment-free, compact, and robust operation. Four-wave mixing (FWM) is a nonlinear effect in optical fibers that can be used to convert frequencies, the major challenge being conservation of momentum, or phase matching, between the interacting light waves. Phase matching can be satisfied through the interaction of different spatial modes in a multi-mode fiber, however, previous demonstrations have been limited by mode stability and narrow-band FWM gain. Alternatively, phase matching within the fundamental mode can be realized in high-confinement waveguides (such as photonic crystal fibers), but achieving the anomalous waveguide dispersion necessary for phase matching at pump wavelengths near ˜1 mum (where the highest power fiber lasers emit) comes at the cost of reducing the effective area of the mode, thus limiting power-handling. Here, we specifically consider the class of Bessel-like LP0,m modes in step-index fibers. It has been shown that these modes can be selectively excited and guided stably for long lengths of fiber, and mode stability increases with mode order 'm'. The effective area of modes in these fibers can be very large (>6000 mum2 demonstrated) and is decoupled from dispersion, allowing for phase matching within a single mode in a power-scalable platform. Furthermore, step-index fibers can guide many different LP0,m modes, allowing access to a highly multi-moded basis set with which to study FWM interactions between different modes. In this thesis we develop techniques to excite, propagate, and characterize LP0,m modes in order to demonstrate FWM in two regimes: monomode interactions comprising waves all belonging to the same mode, and intermodal interactions between different modes. In the monomode regime we demonstrate parametric sources which operate at near-infrared wavelengths under-served by conventional fiber lasers, including 880, 974, 1173, and 1347 nm. The output pulses for these systems are ˜300 ps in duration and reach peak powers of ˜10 kW, representing, to the best our knowledge, the highest peak power fiber laser sources demonstrated at these wavelengths to date. In the intermodal regime, we demonstrate a cascade of FWM processes between different modes that lead to a series of discrete peaks in the visible portion of the spectrum, increasing monotonically in mode order from LP0,7 at 678 nm to LP0,16 at 443 nm. This cascade underscores the huge number of potential FWM interactions between different LP0,m modes available in a highly multi-mode fiber, which scale as N4 for N guided modes. Finally, we demonstrate a novel intermodal FWM process pumped between the LP0,4 and LP0,5 modes of a step-index fiber, which provides broadband FWM gain (63 nm at 1550 nm) while maintaining wavelength separations of nearly an octave (762 nm) - a result that cannot be replicated in the single-mode regime. We seed this process to generate a ˜10 kW, ˜300-ps pulsed fiber laser wavelength-tunable from 786-795 nm; representing a fiber analogue of the ubiquitous Ti:Sapphire laser.

Processing-microstructure models for short- and long-fiber thermoplastic composites

NASA Astrophysics Data System (ADS)

Phelps, Jay H.

The research for this thesis has explored the important microstructural variables for injection-molded thermoplastic composites with discontinuous fiber reinforcement. Two variables, the distributions of fiber orientation and fiber length after processing, have proven to be not only important for correct material property prediction but also difficult to predict using currently available modeling and simulation techniques. In this work, we develop new models for the prediction of these two microstructural variables. Previously, the Folgar-Tucker model has been widely used to predict fiber orientation in injection molded SFT composites. This model accounts for the effects of both hydrodynamics and fiber-fiber interactions in order to give a prediction for a tensorial measure of fiber orientation. However, when applied to at least some classes of LFTs, this model does not match all components of experimental fiber orientation tensor data. In order to address this shortcoming of the model, we hypothesize that Folgar and Tucker's phenomenological treatment of the effects of fiber-fiber interactions with an isotropic rotary diffusion contribution to the rate of change of orientation is insufficient for materials with longer fibers. Instead, this work develops a fiber orientation model that incorporates anisotropic rotary diffusion (ARD). From kinetic theory we derive a general family of evolution equations for the second-order orientation tensor, correcting errors in earlier treatments, and identify a specific equation that is useful for predicting orientation in LFTs. The amount of diffusivity in this model used to approximate the effect of fiber-fiber interactions in each direction is assumed to depend on a second-order space tensor, which is taken to be a function of the orientation state and the rate of deformation. Also, concentrated fiber suspensions align more slowly with respect to strain than the Folgar-Tucker model predicts. Here, we borrow the technique of Wang et al. (2008) to incorporate this behavior in an objective fashion in this new model. Model parameters are selected by matching the experimental steady-state orientation in simple shear flow, and by requiring stable steady states and physically realizable solutions. Utilizing two separate techniques, we identify model parameters for three different materials. We then show that once a set of parameters that meets all previously established criteria has been identified, the differences in model behavior are negligible within that set of parameters. The final model with the proper parameter set is suitable for use in mold filling and other flow simulations, and does give improved predictions of fiber orientation for injection molded LFTs. Although significant fiber length degradation in LFTs has been observed both in literature and in this work, there are no quantitative fiber breakage models to predict either fiber length distributions or average fiber length measures. This work reviews the suspected causes of fiber breakage during the processing of discontinuously-reinforced thermoplastics, specifically LFTs, and introduces a phenomenological fiber breakage model based on the buckling force in a hydrodynamically loaded fiber. This breakage model is incorporated into a conservation equation for total fiber length, and a phenomenological model for the evolution of the fiber length distribution is developed. From this model, we also develop separate, approximate models for the evolution of both the number-average and weight-average fiber length measures. By applying these models to both a simple numerical example and a more complex mold-filling simulation, a qualitative agreement between experiment and prediction is observed. Although these results are promising, the breakage models have only been applied to the mold cavity in injection molding simulation. Both a literature review and our experimental data strongly suggest that the majority of fiber length degradation occurs in the earlier stages of injection molding, in the screw nozzle, runners, and gate. A better understanding of the melting and flow conditions upstream of the mold cavity, the simulation of which is beyond the scope of this work, is needed before these breakage models can be properly applied to the entire injection molding process. (Abstract shortened by UMI.)

Interaction and dispersion of waveguide modes in an optical fiber with microirregularities of the core surface

NASA Astrophysics Data System (ADS)

Zadorin, A. S.; Kruglov, R. S.; Surkova, G. A.

2012-08-01

A self-consistent linear model is proposed for the transformation of the average intensity of the mode spectrum I( z) of the waveguide field in a multimode optical fiber with a stepped refractive index profile and the core having a rough surface. The model is based on the concept of the intermodal dispersion matrix of an elementary segment of the fiber, ∆, whose elements characterize the mutual transfer of energy between the waveguide modes, as well as their conversion to radiation modes on the specified interval. On this basis, the features of the transformation of the mode spectrum I( z) in a multimode optical fiber with a stepped refractive index profile are considered that is due to the effects of multiple dispersion of the signal by the stochastic irregularities of the duct. The effect of self-filtering of I( z) is described that results in the formation of a stable (normalized) distribution I*. The features of the normalization of the radiative damping of a group of modes I i ( z) in an optical fiber are considered.

Strategies to improve fiber utilization in swine

PubMed Central

2013-01-01

Application of feed processing methods and use of exogenous feed additives in an effort to improve nutrient digestibility of plant-based feed ingredients for swine has been studied for decades. The following review will discuss several of these topics, including: fiber characterization, impact of dietary fiber on gastrointestinal physiology, energy, and nutrient digestibility, mechanical processing of feed on fiber and energy digestibility, and the use of exogenous enzymes in diets fed to growing pigs. Taken together, the diversity and concentration of chemical characteristics that exists among plant-based feed ingredients, as well as interactions among constituents within feed ingredients and diets, suggests that improvements in nutrient digestibility and pig performance from mechanical processing or adding exogenous enzymes to diets fed to swine depends on a better understanding of these characteristics, but also relating enzyme activity to targeted substrates. It may be that an enzyme must not only match a target substrate(s), but there may also need to be a ′cocktail′ of enzymes to effectively breakdown the complex matrixes of fibrous carbohydrates, such that the negative impact of these compounds on nutrient digestibility or voluntary feed intake are alleviated. With the inverse relationship between fiber content and energy digestibility being well described for several feed ingredients, it is only logical that development of processing techniques or enzymes that degrade fiber, and thereby improve energy digestibility or voluntary feed intake, will be both metabolically and economically beneficial to pork production. PMID:23497595

Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

PubMed

Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

2017-07-01

Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Silk Self-Assembly Mechanisms and Control-From Thermodynamics to Kinetics

PubMed Central

Lu, Qiang; Zhu, Hesun; Zhang, Cencen; Zhang, Feng; Zhang, Bing; Kaplan, David L.

2012-01-01

Silkworms and spiders generate fibres that exhibit high strength and extensibility. The underlying mechanisms involved in processing silk proteins into fiber form remain incompletely understood, resulting in the failure to fully recapitulate the remarkable properties of native fibers in vitro from regenerated silk solutions. In the present study, the extensibility and high strength of regenerated silks were achieved by mimicking the natural spinning process. Conformational transitions inside micelles, followed by aggregation of micelles and their stabilization as they relate to the metastable structure of silk are described. Subsequently, the mechanisms to control the formation of nanofibrous structures were elucidated. The results clarify that the self-assembly of silk in aqueous solution is a thermodynamically driven process where kinetics also play a key role. Four key factors, molecular mobility, charge, hydrophilic interactions and concentration underlie the process. Adjusting these factors can balance nanostructure and conformational composition, and be used to achieve silk-based materials with properties comparable to native fibers. These mechanisms suggest new directions to design silk-based multifunctional materials. PMID:22320432

Development of FRP composite structural biomaterials: ultimate strength of the fiber/matrix interfacial bond in in vivo simulated environments.

PubMed

Latour, R A; Black, J

1992-05-01

Fiber reinforced polymer (FRP) composites are being developed as alternatives to metals for structural orthopedic implant applications. FRP composite fracture behavior and environmental interactions are distinctly different from those which occur in metals. These differences must be accounted for in the design and evaluation of implant performance. Fiber/matrix interfacial bond strength in a FRP composite is known to strongly influence fracture behavior. The interfacial bond strength of four candidate fiber/matrix combinations (carbon fiber/polycarbonate, carbon fiber/polysulfone, polyaramid fiber/polycarbonate, polyaramid fiber/polysulfone) were investigated at 37 degrees C in dry and in vivo simulated (saline, exudate) environments. Ultimate bond strength was measured by a single fiber-microdroplet pull-out test. Dry bond strengths were significantly decreased following exposure to either saline or exudate with bond strength loss being approximately equal in both the saline and exudate. Bond strength loss is attributed to the diffusion of water and/or salt ions into the sample and their interaction with interfacial bonding. Because bond degradation is dependent upon diffusion, diffusional equilibrium must be obtained in composite test samples before the full effect of the test environment upon composite mechanical behavior can be determined.

Improvement of Interaction in a Composite Structure by Using a Sol-Gel Functional Coating on Carbon Fibers.

PubMed

Szczurek, Anna; Barcikowski, Michał; Leluk, Karol; Babiarczuk, Bartosz; Kaleta, Jerzy; Krzak, Justyna

2017-08-25

The modification of carbon fibers for improving adhesion between fibers and an epoxy resin in composite materials has become the focus of attention. In this work the carbon fiber coating process has been devised in a way preventing the stiffening and clumping of fibers. To improve interactions between coated fibers and a resin in composites, four types of silica coatings with different organic functional groups (3-aminopropyl-coating 1, 3-mercaptopropyl-coating 2, 2-(3,4-epoxycyclohexyl) ethyl-coating 3, methyl-coating 4) were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to distinguish the changes of a carbon fibers surface after coating deposition. The thickness of the obtained coatings, including the diversity of thickness, was determined by transmission electron microscopy (TEM). The increase in surface free energy (SFE) of modified fibers, including the distinction between the polar and dispersive parts, was examined by wettability measurements using a tensometric test. The developed coating preparation process allowed to cover fibers separately with nanoscale silica layers, which changed their morphology. The introduction of organic functional groups resulted in surface free energy changes, especially an increase in specific polar surface energy components.

Improvement of Interaction in a Composite Structure by Using a Sol-Gel Functional Coating on Carbon Fibers

PubMed Central

Barcikowski, Michał; Leluk, Karol; Babiarczuk, Bartosz; Kaleta, Jerzy

2017-01-01

The modification of carbon fibers for improving adhesion between fibers and an epoxy resin in composite materials has become the focus of attention. In this work the carbon fiber coating process has been devised in a way preventing the stiffening and clumping of fibers. To improve interactions between coated fibers and a resin in composites, four types of silica coatings with different organic functional groups (3-aminopropyl–coating 1, 3-mercaptopropyl–coating 2, 2-(3,4-epoxycyclohexyl) ethyl–coating 3, methyl–coating 4) were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to distinguish the changes of a carbon fibers surface after coating deposition. The thickness of the obtained coatings, including the diversity of thickness, was determined by transmission electron microscopy (TEM). The increase in surface free energy (SFE) of modified fibers, including the distinction between the polar and dispersive parts, was examined by wettability measurements using a tensometric test. The developed coating preparation process allowed to cover fibers separately with nanoscale silica layers, which changed their morphology. The introduction of organic functional groups resulted in surface free energy changes, especially an increase in specific polar surface energy components. PMID:28841187

Effects of push/pull perfusion and ultrasonication on the extraction efficiencies of phthalate esters in sports drink samples using on-line hollow-fiber liquid-phase microextraction.

PubMed

Chao, Yu-Ying; Lee, Chien-Hung; Chien, Tzu-Yang; Shih, Yu-Hsuan; Lu, Yin-An; Kuo, Ting-Hsuan; Huang, Yeou-Lih

2013-08-28

In previous studies, we developed a process, on-line ultrasound-assisted push/pull perfusion hollow-fiber liquid-phase microextraction (UA-PPP-HF-LPME), combining the techniques of push/pull perfusion (PPP) and ultrasonication with hollow-fiber liquid-phase microextraction (HF-LPME), to achieve rapid extraction of acidic phenols from water samples. In this present study, we further evaluated three more-advanced and novel effects of PPP and ultrasonication on the extraction efficiencies of neutral high-molecular-weight phthalate esters (HPAEs) in sports drinks. First, we found that inner-fiber fluid leakage occurs only in push-only perfusion-based and pull-only perfusion-based HF-LPME, but not in the PPP mode. Second, we identified a significant negative interaction between ultrasonication and temperature. Third, we found that the extraction time of the newly proposed system could be shortened by more than 93%. From an investigation of the factors affecting UA-PPP-HF-LPME, we established optimal extraction conditions and achieved acceptable on-line enrichment factors of 92-146 for HPAEs with a sampling time of just 2 min.

Agent-based paradigm for integration of interactive cable television operations and business support systems

NASA Astrophysics Data System (ADS)

Wattawa, Scott

1995-11-01

Offering interactive services and data in a hybrid fiber/coax cable system requires the coordination of a host of operations and business support systems. New service offerings and network growth and evolution create never-ending changes in the network infrastructure. Agent-based enterprise models provide a flexible mechanism for systems integration of service and support systems. Agent models also provide a mechanism to decouple interactive services from network architecture. By using the Java programming language, agents may be made safe, portable, and intelligent. This paper investigates the application of the Object Management Group's Common Object Request Brokering Architecture to the integration of a multiple services metropolitan area network.

Bright and dark solitons in the normal dispersion regime of inhomogeneous optical fibers: Soliton interaction and soliton control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Wenjun; Tian Bo, E-mail: tian.bupt@yahoo.com.c; State Key Laboratory of Software Development Environment, Beijing University of Aeronautics and Astronautics, Beijing 100191

2010-08-15

Symbolically investigated in this paper is a nonlinear Schroedinger equation with the varying dispersion and nonlinearity for the propagation of optical pulses in the normal dispersion regime of inhomogeneous optical fibers. With the aid of the Hirota method, analytic one- and two-soliton solutions are obtained. Relevant properties of physical and optical interest are illustrated. Different from the previous results, both the bright and dark solitons are hereby derived in the normal dispersion regime of the inhomogeneous optical fibers. Moreover, different dispersion profiles of the dispersion-decreasing fibers can be used to realize the soliton control. Finally, soliton interaction is discussed withmore » the soliton control confirmed to have no influence on the interaction. The results might be of certain value for the study of the signal generator and soliton control.« less

[Ecological regionalization of national cotton fiber quality in China using GGE biplot analysis method].

PubMed

Xu, Nai Yin; Jin, Shi Qiao; Li, Jian

2017-01-01

The distinctive regional characteristics of cotton fiber quality in the major cotton-producing areas in China enhance the textile use efficiency of raw cotton yarn by improving fiber quality through ecological regionalization. The "environment vs. trait" GGE biplot analysis method was adopted to explore the interaction between conventional cotton sub-regions and cotton fiber quality traits based on the datasets collected from the national cotton regional trials from 2011 to 2015. The results showed that the major cotton-producing area in China were divided into four fiber quality ecological regions, namely, the "high fiber quality ecological region", the "low micronaire ecological region", the "high fiber strength and micronaire ecological region", and the "moderate fiber quality ecological region". The high fiber quality ecological region was characterized by harmonious development of cotton fiber length, strength, micronaire value and the highest spinning consistency index, and located in the conventional cotton regions in the upper and lower reaches of Yangtze River Valley. The low micronaire value ecological region composed of the northern and south Xinjiang cotton regions was characterized by low micronaire value, relatively lower fiber strength, and relatively high spinning consistency index performance. The high fiber strength and micronaire value ecological region covered the middle reaches of Yangtze River Valley, Nanxiang Basin and Huaibei Plain, and was prominently characterized by high strength and micronaire value, and moderate performance of other traits. The moderate fiber quality ecological region included North China Plain and Loess Plateau cotton growing regions in the Yellow River Valley, and was characterized by moderate or lower performances of all fiber quality traits. This study effectively applied "environment vs. trait" GGE biplot to regionalize cotton fiber quality, which provided a helpful reference for the regiona-lized cotton growing regions in terms of optimal raw fiber production for textile industry, and gave a good example for the implementation of similar ecological regionalization of other crops as well.

Fiber optical tweezers for microscale and nanoscale particle manipulation and force sensing

NASA Astrophysics Data System (ADS)

Liu, Yuxiang

2011-12-01

Optical tweezers have been an important tool in biology and physics for studying single molecules and colloidal systems. Most of current optical tweezers are built with microscope objectives, which are: i) expensive, ii) bulky and hard to integrate, iii) sensitive to environmental fluctuations, iv) limited in terms of working distances from the substrate, and v) rigid with the requirements on the substrate (transparent substrate made with glass and with a fixed thickness). These limitations of objective-based optical tweezers prevent them from being miniaturized. Fiber optical tweezers can provide a solution for cost reduction and miniaturization, and these optical tweezers can be potentially used in microfluidic systems. However, the existing fiber optical tweezers have the following limitations: i) low trapping efficiency due to weakly focused beams, ii) lack of the ability to control the positions of multiple particles simultaneously, and iii) limited functionalities. The overall objective of this dissertation work is to further the fundamental understanding of fiber optical tweezers through experimental study and modeling, and to develop novel fiber optical tweezers systems to enhance the capability and functionalities of fiber optical tweezers as microscale and nanoscale manipulators/sensors. The contributions of this dissertation work are summarized as follows. i) An enhanced understanding of the inclined dual-fiber optical tweezers (DFOTs) system has been achieved. Stable three dimensional (3D) optical trapping of a single micron-sized particle has been experimentally demonstrated. This is the first time that the trapping efficiency has been calibrated and the stiffness of the trap has been obtained in the experiments, which has been carried out by using two methods: the drag force method and power spectrum analysis. Such calibration enables the system to be used as a picoNewton-level force sensor in addition to a particle manipulator. The influence of system parameters on the trapping performance has been carefully investigated through both experimental and numerical studies. ii) Multiple traps have been created and carefully studied with the inclined DFOTs for the first time. Three traps, one 3D trap and two 2D traps, have been experimentally created at different vertical levels with adjustable separations and positions. iii) Multiple functionalities have been achieved and studied for the first time with the inclined DFOTs. Particle separation, grouping, stacking, rod alignment, rod rotation, and optical binding have been experimentally demonstrated. The multiple functionalities allow the inclined DFOTs to find applications in the study of interaction forces in colloidal systems as well as parallel particle manipulation in drug delivery systems. iv) Far-field superfocusing effect has been investigated and successfully demonstrated with a fiber-based surface plasmonic (SP) lens for the first time. A planar SP lens with a set of concentric nanoscale rings on a fiber endface has been developed. For the first time, a focus size that is comparable to the smallest achievable focus size of high NA objective lenses has been achieved with the fiber-based SP lens. The fiber-based SP lens can bridge the nanoscale particles/systems and the macroscale power sources/detectors, which has been a long standing challenge for nanophotonics. In addition to optical trapping, the fiber-based SP lens will impact many applications including high-resolution lithography, high-resolution fluorescence detection, and sub-wavelength imaging. v) Trapping ability enhanced with the fiber-based SP lens has been successfully demonstrated. With the help of the fiber-based SP lens, the trapping efficiency of fiber optical tweezers has been significantly enhanced, which is comparable with that of objective-based optical tweezers. A submicron-sized bacterium has been successfully trapped in three dimensions for the first time with optical tweezers based on single fibers.

Monte Carlo simulation of a very high resolution thermal neutron detector composed of glass scintillator microfibers.

PubMed

Song, Yushou; Conner, Joseph; Zhang, Xiaodong; Hayward, Jason P

2016-02-01

In order to develop a high spatial resolution (micron level) thermal neutron detector, a detector assembly composed of cerium doped lithium glass microfibers, each with a diameter of 1 μm, is proposed, where the neutron absorption location is reconstructed from the observed charged particle products that result from neutron absorption. To suppress the cross talk of the scintillation light, each scintillating fiber is surrounded by air-filled glass capillaries with the same diameter as the fiber. This pattern is repeated to form a bulk microfiber detector. On one end, the surface of the detector is painted with a thin optical reflector to increase the light collection efficiency at the other end. Then the scintillation light emitted by any neutron interaction is transmitted to one end, magnified, and recorded by an intensified CCD camera. A simulation based on the Geant4 toolkit was developed to model this detector. All the relevant physics processes including neutron interaction, scintillation, and optical boundary behaviors are simulated. This simulation was first validated through measurements of neutron response from lithium glass cylinders. With good expected light collection, an algorithm based upon the features inherent to alpha and triton particle tracks is proposed to reconstruct the neutron reaction position in the glass fiber array. Given a 1 μm fiber diameter and 0.1mm detector thickness, the neutron spatial resolution is expected to reach σ∼1 μm with a Gaussian fit in each lateral dimension. The detection efficiency was estimated to be 3.7% for a glass fiber assembly with thickness of 0.1mm. When the detector thickness increases from 0.1mm to 1mm, the position resolution is not expected to vary much, while the detection efficiency is expected to increase by about a factor of ten. Copyright © 2015 Elsevier Ltd. All rights reserved.

Interactions Between Diet and the Intestinal Microbiota Alter Intestinal Permeability and Colitis Severity in Mice.

PubMed

Llewellyn, Sean R; Britton, Graham J; Contijoch, Eduardo J; Vennaro, Olivia H; Mortha, Arthur; Colombel, Jean-Frederic; Grinspan, Ari; Clemente, Jose C; Merad, Miriam; Faith, Jeremiah J

2018-03-01

It is not clear how the complex interactions between diet and the intestinal microbiota affect development of mucosal inflammation or inflammatory bowel disease. We investigated interactions between dietary ingredients, nutrients, and the microbiota in specific pathogen-free (SPF) and germ-free (GF) mice given more than 40 unique diets; we quantified individual and synergistic effects of dietary macronutrients and the microbiota on intestinal health and development of colitis. C56BL/6J SPF and GF mice were placed on custom diets containing different concentrations and sources of protein, fat, digestible carbohydrates, and indigestible carbohydrates (fiber). After 1 week, SPF and GF mice were given dextran sulfate sodium (DSS) to induce colitis. Disease severity was determined based on the percent weight change from baseline, and modeled as a function of the concentration of each macronutrient in the diet. In unchallenged mice, we measured intestinal permeability by feeding mice labeled dextran and measuring levels in blood. Feces were collected and microbiota were analyzed by 16S rDNA sequencing. We collected colons from mice and performed transcriptome analyses. Fecal microbiota varied with diet; the concentration of protein and fiber had the strongest effect on colitis development. Among 9 fiber sources tested, psyllium, pectin, and cellulose fiber reduced the severity of colitis in SPF mice, whereas methylcellulose increased severity. Increasing dietary protein increased the density of the fecal microbiota and the severity of colitis in SPF mice, but not in GF mice or mice given antibiotics. Psyllium fiber reduced the severity of colitis through microbiota-dependent and microbiota-independent mechanisms. Combinatorial perturbations to dietary casein protein and psyllium fiber in parallel accounted for most variation in gut microbial density and intestinal permeability in unchallenged mice, as well as the severity of DSS-induced colitis; changes in 1 ingredient could be offset by changes in another. In an analysis of the effects of different dietary components and the gut microbiota on mice with and without DSS-induced colitis, we found complex mixtures of nutrients affect intestinal permeability, gut microbial density, and development of intestinal inflammation. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

Characterizing natural colloidal/particulate-protein interactions using fluorescence-based techniques and principal component analysis.

PubMed

Peiris, Ramila H; Ignagni, Nicholas; Budman, Hector; Moresoli, Christine; Legge, Raymond L

2012-09-15

Characterization of the interactions between natural colloidal/particulate- and protein-like matter is important for understanding their contribution to different physiochemical phenomena like membrane fouling, adsorption of bacteria onto surfaces and various applications of nanoparticles in nanomedicine and nanotoxicology. Precise interpretation of the extent of such interactions is however hindered due to the limitations of most characterization methods to allow rapid, sensitive and accurate measurements. Here we report on a fluorescence-based excitation-emission matrix (EEM) approach in combination with principal component analysis (PCA) to extract information related to the interaction between natural colloidal/particulate- and protein-like matter. Surface plasmon resonance (SPR) analysis and fiber-optic probe based surface fluorescence measurements were used to confirm that the proposed approach can be used to characterize colloidal/particulate-protein interactions at the physical level. This method has potential to be a fundamental measurement of these interactions with the advantage that it can be performed rapidly and with high sensitivity. Copyright © 2012 Elsevier B.V. All rights reserved.

Multiferroic Core-Shell Nanofibers, Assembly in a Magnetic Field, and Studies on Magneto-Electric Interactions

PubMed Central

Zhang, Jitao; Zhang, Ru; Popov, Maksym

2017-01-01

Ferromagnetic–ferroelectric nanocomposites are of interest for realizing strong strain-mediated coupling between electric and magnetic subsystems due to a high surface area-to-volume ratio. This report is on the synthesis of nickel ferrite (NFO)–barium titanate (BTO) core–shell nanofibers, magnetic field assisted assembly into superstructures, and studies on magneto-electric (ME) interactions. Electrospinning techniques were used to prepare coaxial fibers of 0.5–1.5 micron in diameter. The core–shell structure of annealed fibers was confirmed by electron microscopy and scanning probe microscopy. The fibers were assembled into discs and films in a uniform magnetic field or in a field gradient. Studies on ME coupling in the assembled films and discs were done by magnetic field (H)-induced polarization, magneto–dielectric effects at low frequencies and at 16–24 GHz, and low-frequency ME voltage coefficients (MEVC). We measured ~2–7% change in remnant polarization and in the permittivity for H = 7 kOe, and a MEVC of 0.4 mV/cm Oe at 30 Hz. A model has been developed for low-frequency ME effects in an assembly of fibers and takes into account dipole–dipole interactions between the fibers and fiber discontinuity. Theoretical estimates for the low-frequency MEVC have been compared with the data. These results indicate strong ME coupling in superstructures of the core–shell fibers. PMID:29295512

Fiber inhalability and head deposition in rats and humans.

EPA Science Inventory

Due to their dimensions and long durability, inhaled asbestos fibers clear slowly from lung airways. Retained fibers may injure the epithelium, interact with macrophages, or translocate to the interstitium to result in various respiratory diseases. Therefore, calculations of fibe...

Tailoring light-sound interactions in a single mode fiber for the high-power transmission or sensing applications

NASA Astrophysics Data System (ADS)

Gulistan, Aamir; Rahman, M. M.; Ghosh, Souvik; Rahman, B. M. A.

2018-03-01

A full-vectorial numerically efficient Finite Element Method (FEM) based computer code is developed to study complex light-sound interactions in a single mode fiber (SMF). The SBS gain or SBS threshold in a fiber is highly related to the overlap between the optical and acoustic modes. For a typical SMF the acoustic-optic overlap strongly depends on the optical and acoustic mode profiles and it is observed that the acoustic mode is more confined in the core than the optical mode and reported overlap is around 94 % between these fundamental optical and acoustic modes. However, it is shown here that selective co-doping of Aluminum and Germanium in core reduces the acoustic index while keeping the optical index of the same value and thus results in increased acoustic- optic overlap of 99.7%. On the other hand, a design of acoustic anti-guide fiber for high-power transmission systems is also proposed, where the overlap between acoustic and optical modes is reduced. Here, we show that by keeping the optical properties same as a standard SMF and introducing a Boron doped 2nd layer in the cladding, a very low value of 2.7% overlap is achieved. Boron doping in cladding 2nd layer results in a high acoustic index and acoustic modes shifts in the cladding from the core, allowing much high power delivery through this SMF.

Processing of oil palm empty fruit bunch as filler material of polymer recycles

NASA Astrophysics Data System (ADS)

Saepulloh, D. R.; Nikmatin, S.; Hardhienata, H.

2017-05-01

Oil palm empty fruit bunches (OPEFB) is waste from crude palm oil (CPO) processing plants. This research aims to process OPEFB to be a reinforcement polymer recycle with the mechanical milling method and identify each establishment molecular with the orbital hybridization theory. OPEFB fibers were synthesized using a mechanical milling until the size shortfiber and microfiber. Then do the biocomposite granular synthesis with single screw extruder. TAPPI chemical test shows levels of α-cellulose fibers amounted 41.68%. Based on density, the most optimum composition contained in the filler amounted 15% with the size is the microfiber. The test results of morphology with SEM showed deployment of filler OPEFB fiber is fairly equitable distributed. Regarding the molecular interaction between matrix with OPEFB fiber, described by the theory of orbital hybridization. But the explanation establishment of the bond for more complex molecules likes this from the side of the molecular orbital theory is necessary complete information of the hybrid levels.

Mechanical and water soaking properties of medium density fiberboard with wood fiber and soybean protein adhesive.

PubMed

Li, Xin; Li, Yonghui; Zhong, Zhikai; Wang, Donghai; Ratto, Jo A; Sheng, Kuichuan; Sun, Xiuzhi Susan

2009-07-01

Soybean protein is a renewable and abundant material that offers an alternative to formaldehyde-based resins. In this study, soybean protein was modified with sodium dodecyl sulfate (SDS) as an adhesive for wood fiber medium density fiberboard (MDF) preparation. Second-order response surface regression models were used to study the effects and interactions of initial moisture content (IMC) of coated wood fiber, press time (PT) and temperature on mechanical and water soaking properties of MDF. Results showed that IMC of coated fiber was the dominant influencing factor. Mechanical and soaking properties improved as IMC increased and reached their highest point at an IMC of 35%. Press time and temperature also had a significant effect on mechanical and water soaking properties of MDF. Second-order regression results showed that there were strong relationships between mechanical and soaking properties of MDF and processing parameters. Properties of MDF made using soybean protein adhesive are similar to those of commercial board.

Lipid-based nanotubes as functional architectures with embedded fluorescence and recognition capabilities.

PubMed

John, George; Mason, Megan; Ajayan, Pulickel M; Dordick, Jonathan S

2004-11-24

A limited combinatorial strategy was used to synthesize a small library of soft lipid-based materials ranging from structurally unordered fibers to highly uniform nanotubes. The latter nanotubes are comprised of a bilayer structure with interdigitated alkyl chains associated through hydrophobic interactions. These tubes contain accessible 2,6-diaminopyridine linkers that can interact with thymidine and related nucleosides through multipoint hydrogen bonding, thereby quenching the intrinsic fluorescence of the aromatic linker. These results are the first example of a systematic strategy to design functional lipid nanotubes with precise structural and functional features.

Meta-analysis of Polyploid Cotton QTL Shows Unequal Contributions of Subgenomes to a Complex Network of Genes and Gene Clusters Implicated in Lint Fiber Development

PubMed Central

Rong, Junkang; Feltus, F. Alex; Waghmare, Vijay N.; Pierce, Gary J.; Chee, Peng W.; Draye, Xavier; Saranga, Yehoshua; Wright, Robert J.; Wilkins, Thea A.; May, O. Lloyd; Smith, C. Wayne; Gannaway, John R.; Wendel, Jonathan F.; Paterson, Andrew H.

2007-01-01

QTL mapping experiments yield heterogeneous results due to the use of different genotypes, environments, and sampling variation. Compilation of QTL mapping results yields a more complete picture of the genetic control of a trait and reveals patterns in organization of trait variation. A total of 432 QTL mapped in one diploid and 10 tetraploid interspecific cotton populations were aligned using a reference map and depicted in a CMap resource. Early demonstrations that genes from the non-fiber-producing diploid ancestor contribute to tetraploid lint fiber genetics gain further support from multiple populations and environments and advanced-generation studies detecting QTL of small phenotypic effect. Both tetraploid subgenomes contribute QTL at largely non-homeologous locations, suggesting divergent selection acting on many corresponding genes before and/or after polyploid formation. QTL correspondence across studies was only modest, suggesting that additional QTL for the target traits remain to be discovered. Crosses between closely-related genotypes differing by single-gene mutants yield profoundly different QTL landscapes, suggesting that fiber variation involves a complex network of interacting genes. Members of the lint fiber development network appear clustered, with cluster members showing heterogeneous phenotypic effects. Meta-analysis linked to synteny-based and expression-based information provides clues about specific genes and families involved in QTL networks. PMID:17565937

Meta-analysis of polyploid cotton QTL shows unequal contributions of subgenomes to a complex network of genes and gene clusters implicated in lint fiber development.

PubMed

Rong, Junkang; Feltus, F Alex; Waghmare, Vijay N; Pierce, Gary J; Chee, Peng W; Draye, Xavier; Saranga, Yehoshua; Wright, Robert J; Wilkins, Thea A; May, O Lloyd; Smith, C Wayne; Gannaway, John R; Wendel, Jonathan F; Paterson, Andrew H

2007-08-01

QTL mapping experiments yield heterogeneous results due to the use of different genotypes, environments, and sampling variation. Compilation of QTL mapping results yields a more complete picture of the genetic control of a trait and reveals patterns in organization of trait variation. A total of 432 QTL mapped in one diploid and 10 tetraploid interspecific cotton populations were aligned using a reference map and depicted in a CMap resource. Early demonstrations that genes from the non-fiber-producing diploid ancestor contribute to tetraploid lint fiber genetics gain further support from multiple populations and environments and advanced-generation studies detecting QTL of small phenotypic effect. Both tetraploid subgenomes contribute QTL at largely non-homeologous locations, suggesting divergent selection acting on many corresponding genes before and/or after polyploid formation. QTL correspondence across studies was only modest, suggesting that additional QTL for the target traits remain to be discovered. Crosses between closely-related genotypes differing by single-gene mutants yield profoundly different QTL landscapes, suggesting that fiber variation involves a complex network of interacting genes. Members of the lint fiber development network appear clustered, with cluster members showing heterogeneous phenotypic effects. Meta-analysis linked to synteny-based and expression-based information provides clues about specific genes and families involved in QTL networks.

Liquid crystalline phase behavior of protein fibers in water: experiments versus theory.

PubMed

Jung, Jin-Mi; Mezzenga, Raffaele

2010-01-05

We have developed a new method allowing the study of the thermodynamic phase behavior of mesoscopic colloidal systems consisting of amyloid protein fibers in water, obtained by heat denaturation and aggregation of beta-lactoglobulin, a dairy protein. The fibers have a cross section of about 5.2 nm and two groups of polydisperse contour lengths: (i) long fibers of 1-20 microm, showing semiflexible behavior, and (ii) short rods of 100-200 nm long, obtained by cutting the long fibers via high-pressure homogenization. At pH 2 without salt, these fibers are highly charged and stable in water. We have studied the isotropic-nematic phase transition for both systems and compared our results with the theoretical values predicted by Onsager's theory. The experimentally measured isotropic-nematic phase transition was found to occur at 0.4% and at 3% for the long and short fibers, respectively. For both systems, this phase transition occurs at concentrations more than 1 order of magnitude lower than what is expected based on Onsager's theory. Moreover, at low enough pH, no intermediate biphasic region was observed between the isotropic phase and the nematic phase. The phase diagrams of both systems (pH vs concentration) showed similar, yet complex and rich, phase behavior. We discuss the possible physical fundamentals ruling the phase diagram as well as the discrepancy we observe for the isotropic-nematic phase transition between our experimental results and the predicted theoretical results. Our work highlights that systems formed by water-amyloid protein fibers are way too complex to be understood based solely on Onsager's theories. Experimental results are revisited in terms of the Flory's theory (1956) for suspensions of rods, which allows accounting for rod-solvent hydrophobic interactions. This theoretical approach allows explaining, on a semiquantitative basis, most of the discrepancies observed between the experimental results and Onsager's predictions. The sources of protein fibers complex colloidal behavior are analyzed and discussed at length.

Dispersion of cellulose nanofibers in biopolymer based nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Bei

The focus of this work was to understand the fundamental dispersion mechanism of cellulose based nanofibers in bionanocomposites. The cellulose nanofibers were extracted from soybean pod and hemp fibers by chemo-mechanical treatments. These are bundles of cellulose nanofibers with a diameter ranging between 50 to 100 nm and lengths of thousands of nanometers which results in very high aspect ratio. In combination with a suitable matrix polymer, cellulose nanofiber networks show considerable potential as an effective reinforcement for high quality specialty applications of bio-based nanocomposites. Cellulose fibrils have a high density of --OH groups on the surface, which have a tendency to form hydrogen bonds with adjacent fibrils, reducing interaction with the surrounding matrix. The use of nanofibers has been mostly restricted to water soluble polymers. This thesis is focused on synthesizing the nanocomposite using a solid phase matrix polypropylene (PP) or polyethylene (PE) by hot compression and poly (vinyl alcohol) (PVA) in an aqueous phase by film casting. The mechanical properties of nanofiber reinforced PVA film demonstrated a 4-5 fold increase in tensile strength, as compared to the untreated fiber-blend-PVA film. It is necessary to reduce the entanglement of the fibrils and improve their dispersion in the matrix by surface modification of fibers without deteriorating their reinforcing capability. Inverse gas chromatography (IGC) was used to explore how various surface treatments would change the dispersion component of surface energy and acid-base character of cellulose nanofibers and the effect of the incorporation of these modified nanofibers into a biopolymer matrix on the properties of their nano-composites. Poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) based nanocomposites using cellulose nanofibers were prepared by extrusion, injection molding and hot compression. The IGC results indicated that styrene maleic anhydride coated and ethylene-acrylic acid coated fibers improved their potential to interact with both acidic and basic resins. From transmission electron micrograph, it was shown that the nanofibers were partially dispersed in the polymer matrix. The mechanical properties of the nanocomposites were lower than those predicted by theoretical calculations for both nanofiber reinforced biopolymers.

Optical diagnostics of mercury jet for an intense proton target.

PubMed

Park, H; Tsang, T; Kirk, H G; Ladeinde, F; Graves, V B; Spampinato, P T; Carroll, A J; Titus, P H; McDonald, K T

2008-04-01

An optical diagnostic system is designed and constructed for imaging a free mercury jet interacting with a high intensity proton beam in a pulsed high-field solenoid magnet. The optical imaging system employs a backilluminated, laser shadow photography technique. Object illumination and image capture are transmitted through radiation-hard multimode optical fibers and flexible coherent imaging fibers. A retroreflected illumination design allows the entire passive imaging system to fit inside the bore of the solenoid magnet. A sequence of synchronized short laser light pulses are used to freeze the transient events, and the images are recorded by several high speed charge coupled devices. Quantitative and qualitative data analysis using image processing based on probability approach is described. The characteristics of free mercury jet as a high power target for beam-jet interaction at various levels of the magnetic induction field is reported in this paper.

Cadmium arachidate single-walled carbon nanotubes composites as sensitive coatings for high sensitivity fiber optic chemo-sensors

NASA Astrophysics Data System (ADS)

Consales, M.; Crescitelli, A.; Cutolo, A.; Penza, M.; Aversa, P.; Giordano, M.; Cusano, A.

2007-07-01

In this work, the feasibility to exploit optoelectronic chemo-sensors based on cadmium arachidate (CdA)/single-walled carbon nanotubes (SWCNTs) composites for detection of chemical pollutants both in air and water environments has been investigated. The nanocomposite sensing layers have been transferred upon the distal end of standard optical fibers by the Langmuir-Blodgett (LB) technique. Single wavelength reflectance measurements (λ=1310 nm) have been carried out to monitor chemicals concentration through changes in the optical length of the Fabry-Pérot (FP) cavity induced by the interaction of the sensitive layer with the analyte molecules. The preliminary experimental results evidence the good potentiality of these fiber optic nanosensors to detect toluene and xylene at ppm level both in air and water environments at room temperature.

The Effect of Adhesion Interaction on the Mechanical Properties of Thermoplastic Basalt Plastics

NASA Astrophysics Data System (ADS)

Bashtannik, P. I.; Kabak, A. I.; Yakovchuk, Yu. Yu.

2003-01-01

The effect of temperature, adhesion time, and surface treatment of a reinforcing filler on the mechanical properties of thermoplastic basalt plastics based on a high-density polyethylene and a copolymer of 1,3,5-trioxane with 1,3-dioxolan is investigated. An extreme dependence for the adhesive strength in a thermoplastic-basalt fiber system is established and its effect on the mechanical properties of basalt plastics and the influence of the adhesion contact time on the adhesive strength in the system are clarified. The surface modification of basalt fibers in acidic and alkaline media intensifies the adhesion of thermoplastics to them owing to a more developed surface of the reinforcing fibers after etching. It is found that the treatment in the acidic medium is more efficient and considerably improves the mechanical properties of basalt plastics.

The Impact of Carnitine on Dietary Fiber and Gut Bacteria Metabolism and Their Mutual Interaction in Monogastrics

PubMed Central

Ghonimy, Abdallah; Zhang, Dong Ming; Farouk, Mohammed Hamdy; Wang, Qiuju

2018-01-01

Carnitine has vital roles in the endogenous metabolism of short chain fatty acids. It can protect and support gut microbial species, and some dietary fibers can reduce the available iron involved in the bioactivity of carnitine. There is also an antagonistic relationship between high microbial populations and carnitine bioavailability. This review shows the interactions between carnitine and gut microbial composition. It also elucidates the role of carnitine bacterial metabolism, mitochondrial function, fiber fermentability, and short chain fatty acids (SCFAs). PMID:29597260

Aqueous Zinc Compounds as Residual Antimicrobial Agents for Textiles.

PubMed

Holt, Brandon Alexander; Gregory, Shawn Alan; Sulchek, Todd; Yee, Shannon; Losego, Mark D

2018-03-07

Textiles, especially those worn by patients and medical professionals, serve as vectors for proliferating pathogens. Upstream manufacturing techniques and end-user practices, such as transition-metal embedment in textile fibers or alcohol-based disinfectants, can mitigate pathogen growth, but both techniques have their shortcomings. Fiber embedment requires complete replacement of all fabrics in a facility, and the effects of embedded nanoparticles on human health remain unknown. Alcohol-based, end-user disinfectants are short-lived because they quickly volatilize. In this work, common zinc salts are explored as an end-user residual antimicrobial agent. Zinc salts show cost-effective and long-lasting antimicrobial efficacy when solution-deposited on common textiles, such as nylon, polyester, and cotton. Unlike common alcohol-based disinfectants, these zinc salt-treated textiles mitigate microbial growth for more than 30 days and withstand commercial drying. Polyester fabrics treated with ZnO and ZnCl 2 were further explored because of their commercial ubiquity and likelihood for rapid commercialization. ZnCl 2 -treated textiles were found to retain their antimicrobial coating through abrasive testing, whereas ZnO-treated textiles did not. Scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry analyses suggest that ZnCl 2 likely hydrolyzes and reacts with portions of the polyester fiber, chemically attaching to the fiber, whereas colloidal ZnO simply sediments and binds with weaker physical interactions.

Engineering cholesterol-based fibers for antibody immobilization and cell capture

NASA Astrophysics Data System (ADS)

Cohn, Celine

In 2015, the United States is expected to have nearly 600,000 deaths attributed to cancer. Of these 600,000 deaths, 90% will be a direct result of cancer metastasis, the spread of cancer throughout the body. During cancer metastasis, circulating tumor cells (CTCs) are shed from primary tumors and migrate through bodily fluids, establishing secondary cancer sites. As cancer metastasis is incredibly lethal, there is a growing emphasis on developing "liquid biopsies" that can screen peripheral blood, search for and identify CTCs. One popular method for capturing CTCs is the use of a detection platform with antibodies specifically suited to recognize and capture cancer cells. These antibodies are immobilized onto the platform and can then bind and capture cells of interest. However, current means to immobilize antibodies often leave them with drastically reduced function. The antibodies are left poorly suited for cell capture, resulting in low cell capture efficiencies. This body of work investigates the use of lipid-based fibers to immobilize proteins in a way that retains protein function, ultimately leading to increased cell capture efficiencies. The resulting increased efficiencies are thought to arise from the retained three-dimensional structure of the protein as well as having a complete coating of the material surface with antibodies that are capable of interacting with their antigens. It is possible to electrospin cholesterol-based fibers that are similar in design to the natural cell membrane, providing proteins a more natural setting during immobilization. Such fibers have been produced from cholesterol-based cholesteryl succinyl silane (CSS). These fibers have previously illustrated a keen aptitude for retaining protein function and increasing cell capture. Herein the work focuses on three key concepts. First, a model is developed to understand the immobilization mechanism used by electrospun CSS fibers. The antibody immobilization and cell capturing abilities of the CSS fibers were compared to that of hydrophobic polycaprolactone (PCL) fibers and hydrophilic plasma-treated PCL fibers. Electrospun CSS fibers were found to immobilize equivalent amounts of protein as hydrophobically immobilized proteins. However, these proteins captured 6 times more cells, indicative of retained protein function. The second key concept was the design and fabrication of a hybridized lipid fiber. Lipid fibers provide improved protein function but fabrication difficulties have limited their adoption. Thus, we sought to fabricate a lipid-polymer hybrid that is easily fabricated while maintaining protein function. The hybrid fiber consists of a PCL backbone with conjugated CSS. The hybrid lipid fibers showed improved protein function. In addition, higher lipid concentrations were directly correlated to higher cell capture efficiencies. The third key concept was on the development of dually functionalized lipid fibers and understanding the resulting cell capture efficiencies. Many platforms are unable to simultaneously search for heterogeneous populations of CTCs -- the ability to dually functionalize cell-capturing platforms would address this technological weakness. Studies indicated that dually functionalizing the lipid fibers did not compromise the platforms' abilities to capture the cells of interest. Such dually functionalized fibers allow for a single cell-capture platform to successfully detect heterogeneous populations of CTCs. The body of work encompassed herein describes the use of lipid fibers for antibody immobilization and cell capture. Data from various projects indicate that the use of cholesterol-based fibers produced from electrospun CSS are well suited for protein immobilization. The CSS fibers are able to immobilize equivalent amounts of protein as compared to other immobilization techniques. However, the benefit of these fibers is illustrated by the strong cell-capturing efficiencies, indicating that the immobilized proteins are able to retain their function and selectively target cells of interest. The successful immobilization of proteins and their retained function allows for the development of increasingly sensitive cancer diagnostic tools that are able to screen for CTCs early on in the cancer disease cycle.

Mid infrared LHS system packaging using flexible waveguides

NASA Technical Reports Server (NTRS)

Yu, Chung

1987-01-01

As mid IR fiber optic systems are rapidly approaching a reality, so is the feasibility of fiber optic laser heterodyne systems. Laser heterodyne spectroscopy for high resolution monitoring of atmospheric gaseous pollutants is necessarily in the mid IR, the region in which the absorption signature of gaseous species is most prominent. It so happens that the lowest theoretical loss due to Rayleigh-Brillouin scattering also lies in the mid IR. Prospects of highly efficient laser heterodyne systems are thus very good. Such fibers are now beginning to be commercially available, and a test program is being conducted for such fibers with ambient temperature ranging from cryogenic to above room, and stringest mechanical flexibility requirements. Preliminary results are encouraging. A program is being started to explore the possibility of mid IR fiber optic device applications, by taking advantage of this phonon rich region. The potential long interaction length in fibers coupled with predicted extremely low losses point to stimulated Brillouin scattering based devices in the mW range. The generation of backscattered sBs at low laser powers is significant not only as an ultimate power limiting factor for laser transmission in fibers in the mid IR, but also the presence of frequency-shifted multiple order sBs Stokes and antiStokes lines will certainly have severe effect on the laser beats crucial in high resolution heterodyne spectroscopy.

Spectral shaping of an all-fiber torsional acousto-optic tunable filter.

PubMed

Ko, Jeakwon; Lee, Kwang Jo; Kim, Byoung Yoon

2014-12-20

Spectral shaping of an all-fiber torsional acousto-optic (AO) tunable filter is studied. The technique is based on the axial modulation of AO coupling strength along a highly birefringent optical fiber, which is achieved by tailoring the outer diameter of the fiber along its propagation axis. Two kinds of filter spectral shaping schemes-Gaussian apodization and matched filtering with triple resonance peaks-are proposed and numerically investigated under realistic experimental conditions: at the 50-cm-long AO interaction length of the fiber and at half of the original fiber diameter as the minimum thickness of the tailored fiber section. The results show that the highest peak of sidelobe spectra in filter transmission is suppressed from 11.64% to 0.54% via Gaussian modulation of the AO coupling coefficient (κ). Matched filtering with triple resonance peaks operating with a single radio frequency signal is also achieved by cosine modulation of κ, of which the modulation period determines the spectral distance between two satellite peaks located in both wings of the main resonance peak. The splitting of two satellite peaks in the filter spectra reaches 48.2 nm while the modulation period varies from 7.7 to 50 cm. The overall peak power of two satellite resonances is calculated to be 22% of the main resonance power. The results confirm the validity and practicality of our approach, and we predict robust and stable operation of the designed all-fiber torsional AO filters.

Effect of texture dispersion on the effective biaxial modulus of fiber-textured hexagonal, tetragonal, and orthorhombic films

NASA Astrophysics Data System (ADS)

Wu, Huaping; Wu, Linzhi; Du, Shanyi

2008-04-01

The effective biaxial modulus (Meff) of fiber-textured hexagonal, tetragonal, and orthorhombic films is estimated by using the Voigt-Reuss-Hill and Vook-Witt grain-interaction models. The orientation distribution function with Gaussian distributions of the two Euler angles θ and ϕ is adopted to analyze the effect of texture dispersion degree on Meff. Numerical results that are based on ZnO, BaTiO3, and yttrium barium copper oxide (YBCO) materials show that the Vook-Witt average of Meff is identical to the Voigt-Reuss-Hill average of Meff for the (001) plane of ideally fiber-textured hexagonal and tetragonal films. The ϕ distribution has no influence on Meff of the (hkl)-fiber-textured hexagonal film at any θ distribution in terms of the isotropy in the plane perpendicular to the [001] direction. Comparably, tetragonal and orthorhombic films represent considerable actions of ϕ dispersion on Meff, and the effect of ϕ dispersion on Meff of a (001)-fiber-textured YBCO film is smaller than that for a (001)-fiber-textured BaTiO3 film since the shear anisotropic factor in the (001) shear plane of a YBCO film more closely approaches 1. Enhanced θ and ϕ distributions destroy the perfect fiber textures, and as a result, the films exhibit an evolution from ideal (hkl) fiber textures to random textures with varying full widths at half maximums of θ and ϕ.

Processing of a fiber-reinforced transparent glass matrix composite and study of micromechanics of load transfer from matrix to fiber using micro-fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Banerjee, Debangshu

The brittleness of monolithic ceramic materials can be overcome by reinforcing them with high strength, high modulus ceramic fibers. These ceramic matrix composites exhibit improved strength, toughness, and work of fracture. Successful design of a ceramic matrix composite (CMC) depends on two factors: proper choice of fiber, matrix, and interface material, and understanding the mechanics of fracture. The conventional techniques for measuring stress and strain at a local level in CMCs are based on indirect experiments and analytical models. In recent years a couple of optical techniques have been explored for non- contact and direct evaluation of the stress and strain in materials, such as laser Raman spectroscopy and fluorescence spectroscopy. In order to employ spectroscopy to study stress in a composite, a transparent matrix was needed. In this study a SiC fiber reinforced transparent glass matrix composite was developed. A tape casting, binder burnout, and sintering route was adopted to achieve the optimum transparency with proper fiber alignment and interfacial properties. Sapphire fibers were used to act as probe to generate fluorescence signals for measuring stress. A fugitive carbon coating was developed to act as a weak interface for the sapphire fiber, which otherwise, forms a strong bond with the matrix. A fixture was designed to apply stress on the composite specimen, in situ, under the microscope of the spectrometer. Using fluorescence spectroscopy, the micromechanics of load transfer from matrix to fibers were studied. Studies were conducted on both strongly and weakly bonded fibers, as well as on single fiber, and multi fiber situations. Residual stresses arising from thermal expansion mismatch have been mapped along the fiber length with resolution in microns. Residual axial stress was found to follow a shear lag profile along the fiber length. A finite residual axial stress was detected at the fiber ends. Correction of the measured stress for sample probe interaction could not eliminate this finite stress completely. Residual axial stress was also found to vary across the fiber cross section. Analytical models predicting the stress variation along the fiber length and across fiber cross section were developed. (Abstract shortened by UMI.)

Carbon nanotube mode lockers with enhanced nonlinearity via evanescent field interaction in D-shaped fibers

NASA Astrophysics Data System (ADS)

Song, Yong-Won; Yamashita, Shinji; Goh, Chee S.; Set, Sze Y.

2007-01-01

We demonstrate a novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.

Carbon nanotube mode lockers with enhanced nonlinearity via evanescent field interaction in D-shaped fibers.

PubMed

Song, Yong-Won; Yamashita, Shinji; Goh, Chee S; Set, Sze Y

2007-01-15

We demonstrate a novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.

Time-Dependent Stress Rupture Strength Degradation of Hi-Nicalon Fiber-Reinforced Silicon Carbide Composites at Intermediate Temperatures

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2016-01-01

The stress rupture strength of silicon carbide fiber-reinforced silicon carbide composites with a boron nitride fiber coating decreases with time within the intermediate temperature range of 700 to 950 degree Celsius. Various theories have been proposed to explain the cause of the time-dependent stress rupture strength. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of silicon carbide fiber-reinforced silicon carbide composites. This is achieved through the development of a numerically based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time-marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time-dependent behavior.

Recent Progress in Brillouin Scattering Based Fiber Sensors

PubMed Central

Bao, Xiaoyi; Chen, Liang

2011-01-01

Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave), the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, and railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures. PMID:22163842

Recent progress in Brillouin scattering based fiber sensors.

PubMed

Bao, Xiaoyi; Chen, Liang

2011-01-01

Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave), the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, and railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures.

Impacts of Cellulose Fiber Particle Size and Starch Type on Expansion During Extrusion Processing.

PubMed

Kallu, Sravya; Kowalski, Ryan J; Ganjyal, Girish M

2017-07-01

Objective of this study was to understand the impacts of cellulose fiber with different particle size distributions, and starches with different molecular weights, on the expansion of direct expanded products. Fiber with 3 different particle size distributions (<125, 150 to 250, 300 to 425 μm) and 4 types of starches representing different amylose contents (0%, 23%, 50%, and 70%) were investigated. Feed moisture content (18 ± 0.5 % w.b) and extruder temperature (140 °C) were kept constant and only the extruder screw speed was varied (100, 175, and 250 rpm) to achieve different specific mechanical energy inputs. Fiber particle size and starch type significantly influenced the various product parameters. In general, the smaller fiber particle size resulted in extrudate with higher expansion ratio. Starch with an amylose: amylopectin ratio of 23:77 resulted in highest expansion compared to the other starches, when no fiber was added. Interestingly, starch with 50:50, amylose: amylopectin ratio in combination with smaller fiber particles resulted in product with significantly greater expansion than the control starch extrudates. Aggregation of fiber and shrinkage of surface was observed in the Scanning Electron Microscope images at 10% fiber level. The results suggest the presence of active interactions between the cellulose fiber particles and corn starch molecules during the expansion process. A better understanding of these interactions can help in the development of high fiber extruded products with better expansion. © 2017 Institute of Food Technologists®.

Interlaminar Toughening of Fiber Reinforced Polymers

NASA Astrophysics Data System (ADS)

Bian, Dakai

Modification in the resin-rich region between plies, also known as the interlaminar region, was investigated to increase the toughness of laminate composites structures. To achieve suitable modifications, the complexities of the physical and chemical processes during the resin curing procedure must be studied. This includes analyses of the interactions among the co-dependent microstructure, process parameters, and material responses. This dissertation seeks to investigate these interactions via a series of experimental and numerical analyses of the geometric- and temperature-based effects on locally interleaving toughening methods and further interlaminar synergistic toughening without interleaf. Two major weaknesses in composite materials are the brittle resin-rich interlaminar region which forms between the fiber plies after resin infusion, and the ply dropoff region which introduces stress concentration under loads. To address these weaknesses and increase the delamination resistance of the composite specimens, a dual bonding process was explored to alleviate the dropoff effect and toughen the interlaminar region. Hot melt bonding was investigated by applying clamping pressure to ductile thermoplastic interleaf and fiber fabric at an elevated temperature, while diffusion bonding between thermoplastic interleaf and thermoset resin is performed during the resin infusion. This method increased the fracture energy level and thus delamination resistance in the interlaminar region because of deep interleaf penetration into fiber bundles which helped confining crack propagation in the toughened area. The diffusion and precipitation between thermosets and thermoplastics also improved the delamination resistance by forming a semi-interpenetration networks. This phenomenon was investigated in concoctions of low-concentration polystyrene additive modified epoxy system, which facilitates diffusion and precipitation without increasing the viscosity of the system. Additionally, chemical reaction induced phase separation, concentration of polystyrene, and various curing temperatures are used to evaluate their effects on diffusion and precipitation. These effects were directly investigated by performing attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The diffusivity and curing kinetics experiments are performed to quantify the diffusivity coefficient of epoxy, hardener and thermoplastics, as well as the reaction rate constant of curing epoxy at various temperatures. Finally, mechanical testing and fracture surface imaging were used to quantify the improvements and characterize the toughening mechanism. Further improvement on delamination resistance was studied through the synergistic effect of combining different modification methods without the interleaf. Polysulfone molecules are end-capped with epoxide groups. Fiber surface is functionalized with amino groups to generate micro-mechanical interlocks. The interaction between two individual modifications chemically links the modified semi-interpenetration networks to the improved interfacial strength between fiber and epoxy to. The impact of the additive on the crosslinking density was examined through glass transition temperatures, and the chemical modification was characterized by Raman spectroscopy. Mode I and II fracture tests were performed to quantify the improvement of delamination resistance under pure opening and shear loads. The mechanism of synergistic effect was explained based on the fracture surface morphology and the interactions between the modification methods.

Mechanics of Failure of High Temperature Metal Matrix Composites

DTIC Science & Technology

1993-12-22

by two inhomogeneities that sustain an eigenstrain loading, proportional to the difference of fiber/matrx thermal expansion coefficients. Utilizing the...appropriate eigenstrain field. sustained by the fiber cross sections. Our primary interest is to determine how the fiber interaction relates to the local...inhomogeneities (fiber cross sections). with a central distance c. undergo an eigenstrain loading. Utilizing the di. -Sacement potentials approach. an

Effect of interactions between Co(2+) and surface goethite layer on the performance of α-FeOOH coated hollow fiber ceramic ultrafiltration membranes.

PubMed

Zhu, Zhiwen; Zhu, Li; Li, Jianrong; Tang, Jianfeng; Li, Gang; Hsieh, Yi-Kong; Wang, TsingHai; Wang, Chu-Fang

2016-03-15

The consideration of water energy nexus inspires the environmental engineering community to pursue a more sustainable strategy in the wastewater treatment. One potential response would be to enhance the performance of the low-pressure driven filtration system. To reach this objective, it is essential to have a better understanding regarding the surface interaction between the target substance and the surface of membrane. In this study, the hollow fiber ceramic membranes were coated with a goethite layer in order to enhance the Co(2+) rejection. Experimental results indicate that higher Co(2+) rejections are always accompanied with the significant reduction in the permeability. Based on the consideration of electroviscous effect, the surface interactions including the induced changes in viscosity, pore radius and Donnan effect in the goethite layer are likely responsible for the pH dependent behaviors in the rejection and permeability. These results could be valuable references to develop the filtration system with high rejection along with acceptable degree of permeability in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

Fabrication of CA/TPU Helical Nanofibers and its Mechanism Analysis

NASA Astrophysics Data System (ADS)

Wu, Huihui; Zhao, Shihang; Han, Lei

2018-04-01

To explore the mechanism of cellulose acetate (CA)/thermoplastic polyurethane (TPU) on the fabrication of helical nanofibers, a series of experiments were conducted to find the optimum spinning conditions. The experimental results show that the CA (14 wt%, DMAc/acetone, 1/2 volume ratio)/TPU2 (18 wt%, DMAc/acetone, 3/1 volume ratio) system can fabricate helical nanofibers effectively via co-electrospinning. We focus on the interfacial interaction between the polymer components induced by the polymer structure and intrinsic properties, including solution properties, hydrogen bonding, and miscibility behavior of the two solutions. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) are employed to investigate the interfacial interaction between the two phases of the polymer system. The analysis results provide the explanation of the experimental results that the CA/TPU system has the potential for producing helical nanofibers effectively. This study based on the interfacial interaction between polymer components provides an insight into the mechanism of CA/TPU helical fiber formation and introduces a richer choice of materials for the application of helical fibers.

Time and frequency pump-probe multiplexing to enhance the signal response of Brillouin optical time-domain analyzers.

PubMed

Soto, Marcelo A; Ricchiuti, Amelia Lavinia; Zhang, Liang; Barrera, David; Sales, Salvador; Thévenaz, Luc

2014-11-17

A technique to enhance the response and performance of Brillouin distributed fiber sensors is proposed and experimentally validated. The method consists in creating a multi-frequency pump pulse interacting with a matching multi-frequency continuous-wave probe. To avoid nonlinear cross-interaction between spectral lines, the method requires that the distinct pump pulse components and temporal traces reaching the photo-detector are subject to wavelength-selective delaying. This way the total pump and probe powers launched into the fiber can be incrementally boosted beyond the thresholds imposed by nonlinear effects. As a consequence of the multiplied pump-probe Brillouin interactions occurring along the fiber, the sensor response can be enhanced in exact proportion to the number of spectral components. The method is experimentally validated in a 50 km-long distributed optical fiber sensor augmented to 3 pump-probe spectral pairs, demonstrating a signal-to-noise ratio enhancement of 4.8 dB.

Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

NASA Astrophysics Data System (ADS)

Aslani, Farhad; Nejadi, Shami

2012-09-01

Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers, information is hardly available in this area. In this study, bond characteristics of deformed reinforcing steel bars embedded in SFRSCC is investigated secondly.

Cross layer optimization for cloud-based radio over optical fiber networks

NASA Astrophysics Data System (ADS)

Shao, Sujie; Guo, Shaoyong; Qiu, Xuesong; Yang, Hui; Meng, Luoming

2016-07-01

To adapt the 5G communication, the cloud radio access network is a paradigm introduced by operators which aggregates all base stations computational resources into a cloud BBU pool. The interaction between RRH and BBU or resource schedule among BBUs in cloud have become more frequent and complex with the development of system scale and user requirement. It can promote the networking demand among RRHs and BBUs, and force to form elastic optical fiber switching and networking. In such network, multiple stratum resources of radio, optical and BBU processing unit have interweaved with each other. In this paper, we propose a novel multiple stratum optimization (MSO) architecture for cloud-based radio over optical fiber networks (C-RoFN) with software defined networking. Additionally, a global evaluation strategy (GES) is introduced in the proposed architecture. MSO can enhance the responsiveness to end-to-end user demands and globally optimize radio frequency, optical spectrum and BBU processing resources effectively to maximize radio coverage. The feasibility and efficiency of the proposed architecture with GES strategy are experimentally verified on OpenFlow-enabled testbed in terms of resource occupation and path provisioning latency.

β-Glucans and Resistant Starch Alter the Fermentation of Recalcitrant Fibers in Growing Pigs.

PubMed

de Vries, Sonja; Gerrits, Walter J J; Kabel, Mirjam A; Vasanthan, Thava; Zijlstra, Ruurd T

2016-01-01

Interactions among dietary ingredients are often assumed non-existent when evaluating the nutritive value and health effects of dietary fiber. Specific fibers can distinctly affect digestive processes; therefore, digestibility and fermentability of the complete diet may depend on fiber types present. This study aimed to evaluate the effects of readily fermentable fibers (β-glucans and resistant starch) on the degradation of feed ingredients containing more persistent, recalcitrant, fibers. Six semi-synthetic diets with recalcitrant fibers from rapeseed meal (pectic polysaccharides, xyloglucans, and cellulose) or corn distillers dried grain with solubles (DDGS; (glucurono)arabinoxylans and cellulose) with or without inclusion of β-glucans (6%) or retrograded tapioca (40%) substituted for corn starch were formulated. Six ileal-cannulated pigs (BW 28±1.4 kg) were assigned to the diets according to a 6×6 Latin square. β-glucan-extract increased apparent total tract digestibility (ATTD) of non-glucosyl polysaccharides (accounting for ~40% of the fiber-fraction) from rapeseed meal (6%-units, P<0.001), but did not affect non-glucosyl polysaccharides from DDGS. Retrograded tapioca reduced ATTD of non-glucosyl polysaccharides from rapeseed meal and DDGS (>10%-units, P<0.001), indicating that the large amount of resistant starch entering the hindgut was preferentially degraded over recalcitrant fibers from rapeseed meal and DDGS, possibly related to reduced hindgut-retention time following the increased intestinal bulk. Fermentation of fiber sources was not only dependent on fiber characteristics, but also on the presence of other fibers in the diet. Hence, interactions in the gastrointestinal tract among fibrous feed ingredients should be considered when evaluating their nutritive value.

Mesh-type acoustic vector sensor

NASA Astrophysics Data System (ADS)

Zalalutdinov, M. K.; Photiadis, D. M.; Szymczak, W. G.; McMahon, J. W.; Bucaro, J. A.; Houston, B. H.

2017-07-01

Motivated by the predictions of a theoretical model developed to describe the acoustic flow force exerted on closely spaced nano-fibers in a viscous medium, we have demonstrated a novel concept for a particle velocity-based directional acoustic sensor. The central element of the concept exploits the acoustically induced normal displacement of a fine mesh as a measure of the collinear projection of the particle velocity in the sound wave. The key observations are (i) the acoustically induced flow force on an individual fiber within the mesh is nearly independent of the fiber diameter and (ii) the mesh-flow interaction can be well-described theoretically by a nearest neighbor coupling approximation. Scaling arguments based on these two observations indicate that the refinement of the mesh down to the nanoscale leads to significant improvements in performance. The combination of the two dimensional nature of the mesh together with the nanoscale dimensions provides a dramatic gain in the total length of fiber exposed to the flow, leading to a sensitivity enhancement by orders of magnitude. We describe the fabrication of a prototype mesh sensor equipped with optical readout. Preliminary measurements carried out over a considerable bandwidth together with the results of numerical simulations are in good agreement with the theory, thus providing a proof of concept.

Titin Based Viscosity in Ventricular Physiology: An Integrative Investigation of PEVK-Actin Interactions

PubMed Central

Chung, Charles S; Methawasin, Methajit; Nelson, O Lynne; Radke, Michael H; Hidalgo, Carlos G; Gotthardt, Michael; Granzier, Henk L

2011-01-01

Viscosity is proposed to modulate diastolic function, but only limited understanding of the source(s) of viscosity exists. In-vitro experiments have shown that the proline-glutamic acid-valine-lysine (PEVK) rich element of titin interacts with actin, causing a viscous force in the sarcomere. It is unknown whether this mechanism contributes to viscosity in-vivo. We tested the hypothesis that PEVK-actin interaction causes cardiac viscosity and is important in-vivo via an integrative physiological study on a unique PEVK-knockout (KO) model. Both skinned cardiomyocytes and papillary muscle fibers were isolated from wildtype (WT) and PEVK KO mice and passive viscosity was examined using stretch-hold-release and sinusoidal analysis. Viscosity was reduced by ~60% in KO myocytes and ~50% in muscle fibers at room temperature. The PEVK-actin interaction was not modulated by temperature or diastolic calcium, but was increased by lattice compression. Stretch-hold and sinusoidal frequency protocols on intact isolated mouse hearts showed a smaller, 30–40% reduction in viscosity, possibly due to actomyosin interactions, and showed that microtubules did not contribute to viscosity. Transmitral Doppler echocardiography similarly revealed a 40% decrease in LV chamber viscosity in the PEVK KO in-vivo. This integrative study is the first to quantify the influence of a specific molecular (PEVK-actin) viscosity in-vivo and shows that PEVK-actin interactions are an important physiological source of viscosity. PMID:21708170

Use of analyte-modulated modal power distribution in multimode optical fibers for simultaneous single-wavelength evanescent-wave refractometry and spectrometry.

PubMed

Potyrailo, R A; Ruddy, V P; Hieftje, G M

1999-11-01

A new method is described for the simultaneous determination of absorbance and refractive index of a sample medium. The method is based on measurement of the analyte-modulated modal power distribution (MPD) in a multimode waveguide. In turn, the MPD is quantified by the far-field spatial pattern and intensity of light, i.e., the Fraunhofer diffraction pattern (registered on a CCD camera), that emerges from a multimode optical fiber. Operationally, light that is sent down the fiber interacts with the surrounding analyte-containing medium by means of the evanescent wave at the fiber boundary. The light flux in the propagating beam and the internal reflection angles within the fiber are both affected by optical absorption connected with the analyte and by the refractive index of the analyte-containing medium. In turn, these angles are reflected in the angular divergence of the beam as it leaves the fiber. As a result, the Fraunhofer diffraction pattern of that beam yields two parameters that can, together, be used to deduce refractive index and absorbance. This MPD based detection offers important advantages over traditional evanescent-wave detection strategies which rely on recording only the total transmitted optical power or its lost fraction. First, simultaneous determination of sample refractive index and absorbance is possible at a single probe wavelength. Second, the sensitivity of refractometric and absorption measurements can be controlled simply, either by adjusting the distance between the end face of the fiber and the CCD detector or by monitoring selected modal groups at the fiber output. As a demonstration of these capabilities, several weakly absorbing solutions were examined, with refractive indices in the range from 1.3330 to 1.4553 and with absorption coefficients in the range 0-16 cm-1. The new detection strategy is likely to be important in applications in which sample coloration varies and when it is necessary to compensate for variations in the refractive index of a sample.

Stimulated Brillouin scattering continuous wave phase conjugation in step-index fiber optics.

PubMed

Massey, Steven M; Spring, Justin B; Russell, Timothy H

2008-07-21

Continuous wave (CW) stimulated Brillouin scattering (SBS) phase conjugation in step-index optical fibers was studied experimentally and modeled as a function of fiber length. A phase conjugate fidelity over 80% was measured from SBS in a 40 m fiber using a pinhole technique. Fidelity decreases with fiber length, and a fiber with a numerical aperture (NA) of 0.06 was found to generate good phase conjugation fidelity over longer lengths than a fiber with 0.13 NA. Modeling and experiment support previous work showing the maximum interaction length which yields a high fidelity phase conjugate beam is inversely proportional to the fiber NA(2), but find that fidelity remains high over much longer fiber lengths than previous models calculated. Conditions for SBS beam cleanup in step-index fibers are discussed.

Measuring shear modulus of individual fibers

NASA Astrophysics Data System (ADS)

Behlow, Herbert; Saini, Deepika; Oliviera, Luciana; Skove, Malcolm; Rao, Apparao

2014-03-01

Fiber technology has advanced to new heights enabling tailored mechanical properties. For reliable fiber applications their mechanical properties must be well characterized at the individual fiber level. Unlike the tensile modulus, which can be well studied in a single fiber, the present indirect and dynamic methods of measuring the shear properties of fibers suffer from various disadvantages such as the interaction between fibers and the influence of damping. In this talk, we introduce a quasi-static method to directly measure the shear modulus of a single micron-sized fiber. Our simple and inexpensive setup yields a shear modulus of 16 and 2 GPa for a single IM7 carbon fiber and a Kevlar fiber, respectively. Furthermore, our setup is also capable of measuring the creep, hysteresis and the torsion coefficient, and examples of these will be presented.

Development of natural fiber reinforced polylactide-based biocomposites

NASA Astrophysics Data System (ADS)

Arias Herrera, Andrea Marcela

Polylactide or PLA is a biodegradable polymer that can be produced from renewable resources. This aliphatic polyester exhibits good mechanical properties similar to those of polyethylene terephthalate (PET). Since 2003, bio-based high molecular weight PLA is produced on an industrial scale and commercialized under amorphous and semicrystalline grades for various applications. Enhancement of PLA crystallization kinetics is crucial for the competitiveness of this biopolymer as a commodity material able to replace petroleum-based plastics. On the other hand, the combination of natural fibers with polymer matrices made from renewable resources, to produce fully biobased and biodegradable polymer composite materials, has been a strong trend in research activities during the last decade. Nevertheless, the differences related to the chemical structure, clearly observed in the marked hydrophilic/hydrophobic character of the fibers and the thermoplastic matrix, respectively, represent a major drawback for promoting strong fiber/matrix interactions. The aim of the present study was to investigate the intrinsic fiber/matrix interactions of PLAbased natural fiber composites prepared by melt-compounding. Short flax fibers presenting a nominal length of ˜1 mm were selected as reinforcement and biocomposites containing low to moderate fiber loading were processed by melt-mixing. Fiber bundle breakage during processing led to important reductions in length and diameter. The mean aspect ratio was decreased by about 50%. Quiescent crystallization kinetics of PLA and biocomposite systems was examined under isothermal and non-isothermal conditions. The nucleating nature of the flax fibers was demonstrated and PLA crystallization was effectively accelerated as the natural reinforcement content increased. Such improvement was controlled by the temperature at which crystallization took place, the liquid-to-solid transition being thermodynamically promoted by the degree of supercooling. During crystallization, viscoelastic properties are expected to be strongly influenced by crystallite development and impingement. Rheometry was selected as a suitable technique to study the evolution of complex viscosity and storage and loss moduli during the crystallization of compounded PLA and PLA-biocomposites. Optimization of experimental conditions was needed for achieving the compensation of polymer shrinkage, which was a major concern for the reproducibility of measurements, particularly at high supercooling level. Fruitful information about the enhanced crystallization rate due to the presence of flax fibers in a wide range of crystallization temperatures was obtained from this study. Since development of crystallization in industrial processing may differ greatly from quiescent studies, a preliminary investigation of the effect of shear flow on the improvement of PLA crystallization was carried out. Using the same shear rate interval, two different sets of conditions were explored, namely (1) constant total deformation and (2) constant shearing time. In both cases, the crystallization enhancement was evidenced by a decrease in the induction time which became stronger as shear rate augmented. About 75% of reduction was observed at 4 s-1, the maximum shear rate reached in this research. The size reduction of cellulose particles from micro to the nanoscale has also drawn special attention over the last decade. Well-dispersed nanosized fiber networks into polymeric matrices may bring extraordinary strength enhancement and modify the particle/polymer interactions at the molecular level. As a consequence, crystallization may be promoted at considerably low concentrations of reinforcement. It is well-known that dispersion of cellulose nanocrystals (CNC) in non-aqueous systems is a major challenge for further developments. In this work, a novel twostep process involving solvent-mixing and melt-mixing was found to successfully dispersed cellulose nanocrystals at low weight loadings in the PLA matrix. Polyethylene oxide (PEO) of high and low molecular weight was proposed as a polymer carrier for nanocrystals, and the encapsulation of CNC in this polymer was achieved. Reduction of agglomerate size was controlled by the increase of PEO:CNC weight content ratio in the final nanocomposites. A synergistic effect between plasticization and reinforcement of the PLA matrix was clearly evidenced from the crystallization behavior of nanocomposites. The PLA nanocomposite preparation method presented in this dissertation represents a step forward in the potential applications of CNC in green composite materials.

A new technique to transfer metallic nanoscale patterns to small and non-planar surfaces: Application to a fiber optic device for surface enhanced Raman scattering detection

NASA Astrophysics Data System (ADS)

Smythe, Elizabeth Jennings

This thesis focuses on the development of a bidirectional fiber optic probe for the detection of surface enhanced Raman scattering (SERS). One facet of this fiber-based probe featured an array of coupled optical antennas, which we designed to enhance the Raman signal of nearby analytes. When this array interacted with an analyte, it generated SERS signals specific to the chemical composition of the sample; some of these SERS signals coupled back into the fiber. We used the other facet of the probe to input light into the fiber and collect the SERS signals that coupled into the probe. In this dissertation, the development of the probe is broken into three sections: (i) characterization of antenna arrays, (ii) fabrication of the probe, and (iii) device measurements. In the first section we present a comprehensive study of metallic antenna arrays. We carried out this study to determine the effects of antenna geometry, spacing, and composition on the surface plasmon resonance (SPR) of a coupled antenna array; the wavelength range and strength of the SPR are functions of the shape and interactions of the antennas. The SPR of the array ultimately amplified the Raman signal of analytes and produced a measurable SERS signal, thus determination of the optimal array geometries for SERS generation was an important first step in the development of the SERS fiber probe. We then introduce a new technique developed to fabricate the SERS fiber probes. This technique involves transferring antenna arrays (created by standard lithographic methods) from a large silicon substrate to a fiber facet. We developed this fabrication technique to bypass many of the limitations presented by previously developed methods for patterning unconventional substrates (i.e. small and/or non-planar substrates), such as focused ion-beam milling and soft lithography. In the third section of this thesis, we present SERS measurements taken with the fiber probe. We constructed a measurement system to couple light into the probe and filter out background noise; this allowed simultaneous detection of multiple chemicals. Antenna array enhancement factor (EF) calculations are shown; these allowed us to determine that the probe efficiently collected SERS signals.

Inclusion models of tensile fracture in fiber-reinforced brittle-matrix composites. Ph.D. Thesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, W.

1993-12-31

Inclusion models of tensile fracture in fiber-reinforced brittle-matrix composites are proposed in this study. Three stages of matrix cracking including initiation of microcracks, propagation of a bridged crack and multiplication of periodic cracks are modeled using the unique approach - Eshelby`s equivalent inclusion method. Moreover, the interfacial debonding may occur during matrix cracking and is taken into account by the present analysis. After interfacial debonding initiates, the fiber slides against the friction which is assumed to be constant in chapter 2 and chapter 3. However, the fiber-matrix interfaces are assumed to be Coulomb`s friction controlled in chapter 4. Energy releasemore » rate and crack resistance are obtained analytically. From the fracture criterion, the equivalence of energy release rate and crack resistance, the critical applied stress is also obtained. On the critical applied stress the effects of material parameters such as interfacial frictional stress, interfacial surface energy, volume fraction of fibers, misfit strain are evaluated. These evaluations are important for the purpose of material design. Finally, it is attempted in chapter 5 to solve the crack-inhomogeneity interaction problem inhomogeneities. First, the formulation of two inhomogeneities without overlapping is derived in detail. When one of the inhomogeneities is the penny-shape crack and the other one is the ellipsoidal inhomogeneity, the interaction energy between the crack and the applied stress and the energy release rate of the crack are evaluated. Based on the framework of this chapter, one can deal with the real configuration including many inhomogeneities in the similar way. Also, the misfit strains due to thermal mismatch, phase transformation et al. can be included in the present analysis with no difficulty.« less

Amine-functionalized MIL-53(Al)-coated stainless steel fiber for efficient solid-phase microextraction of synthetic musks and organochlorine pesticides in water samples.

PubMed

Xie, Lijun; Liu, Shuqin; Han, Zhubing; Jiang, Ruifen; Zhu, Fang; Xu, Weiqin; Su, Chengyong; Ouyang, Gangfeng

2017-09-01

The fiber coating is the key part of the solid-phase microextraction (SPME) technique, and it determines the sensitivity, selectivity, and repeatability of the analytical method. In this work, amine (NH 2 )-functionalized material of Institute Lavoisier (MIL)-53(Al) nanoparticles were successfully synthesized, characterized, and applied as the SPME fiber coating for efficient sample pretreatment owing to their unique structures and excellent adsorption properties. Under optimized conditions, the NH 2 -MIL-53(Al)-coated fiber showed good precision, low limits of detection (LODs) [0.025-0.83 ng L -1 for synthetic musks (SMs) and 0.051-0.97 ng L -1 for organochlorine pesticides (OCPs)], and good linearity. Experimental results showed that the NH 2 -MIL-53(Al) SPME coating was solvent resistant and thermostable. In addition, the extraction efficiencies of the NH 2 -MIL-53(Al) coating for SMs and OCPs were higher than those of commercially available SPME fiber coatings such as polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, and polyacrylate. The reasons may be that the analytes are adsorbed on NH 2 -MIL-53(Al) primarily through π-π interactions, electron donor-electron acceptor interactions, and hydrogen bonds between the analytes and organic linkers of the material. Direct immersion (DI) SPME-gas chromatography-mass spectrometry methods based on NH 2 -MIL-53(Al) were successfully applied for the analysis of tap and river water samples. The recoveries were 80.3-115% for SMs and 77.4-117% for OCPs. These results indicate that the NH 2 -MIL-53(Al) coating may be a promising alternative to SPME coatings for the enrichment of SMs and OCPs.

Transverse mode instability of fiber oscillators in comparison with fiber amplifiers

NASA Astrophysics Data System (ADS)

Hejaz, Kamran; Shayganmanesh, Mahdi; Azizi, Saeed; Abedinajafi, Ali; Roohforouz, Ali; Rezaei-Nasirabad, Reza; Vatani, Vahid

2018-05-01

Transverse mode instability (TMI) is experimentally investigated in a fiber oscillator and a fiber amplifier. For a reasonable comparison of TMI in these two configurations, the same optical components and design parameters are applied to both. Our experimental results show that the TMI power threshold in a fiber oscillator is lower than in a corresponding fiber amplifier. By using simulation software, a fiber oscillator and an amplifier are designed with similar characteristics, to provide identical conditions for all effective parameters on TMI in both of them. Since the signal propagation in fiber oscillators is different from that of single-pass fiber amplifiers, and also since both forward and backward propagating signals in fiber oscillators can generate thermo-optic index gratings, the observed lower TMI threshold in the fiber oscillator is due to its different interaction of light with index gratings.

Numerical modelling of the reinforced concrete influence on a combined system of tunnel support

NASA Astrophysics Data System (ADS)

Grujić, Bojana; Jokanović, Igor; Grujić, Žarko; Zeljić, Dragana

2017-12-01

The paper presents the experimental, laboratory determined rheological-dynamic analysis of the properties of fiber reinforced concrete, which was then utilized to show nonlinear analysis of combined system of tunnel support structure. According to the performed experiments and calculations, different processes of destructive behavior of tunnel lining were simulated in combination with elastic and elastic-plastic behavior of materials taking into account the tunnel loading, the interaction between the fiber reinforced concrete and soil, as well as the interaction between the fiber reinforced concrete and the inner lining of the tunnel.

Understanding Polymorphism Formation in Electrospun Fibers of Immiscible Poly(vinylidene fluoride) Blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

G Zhong; L Zhang; R Su

2011-12-31

Effects of electric poling, mechanical stretching, and dipolar interaction on the formation of ferroelectric ({beta} and/or {gamma}) phases in poly(vinylidene fluoride) (PVDF) have been studied in electrospun fibers of PVDF/polyacrylonitrile (PAN) and PVDF/polysulfone (PSF) blends with PVDF as the minor component, using wide-angle X-ray diffraction and Fourier transform infrared techniques. Experimental results of as-electrospun neat PVDF fibers (beaded vs. bead-free) showed that mechanical stretching during electrospinning, rather than electric poling, was effective to induce ferroelectric phases. For as-electrospun PVDF blend fibers with the non-polar PSF matrix, mechanical stretching during electrospinning again was capable of inducing some ferroelectric phases in additionmore » to the major paraelectric ({alpha}) phase. However, after removing the mechanical stretching in a confined melt-recrystallization process, only the paraelectric phase was obtained. For as-electrospun PVDF blend fibers with the polar (or ferroelectric) PAN matrix, strong intermolecular interactions between polar PAN and PVDF played an important role in the ferroelectric phase formation in addition to the mechanical stretching effect during electrospinning. Even after the removal of mechanical stretching through the confined melt-recrystallization process, a significant amount of ferroelectric phases persisted. Comparing the ferroelectric phase formation between PVDF/PSF and PVDF/PAN blend fibers, we concluded that the local electric field-dipole interactions were the determining factor for the nucleation and growth of polar PVDF phases.« less

3D fiber deposited polymeric scaffolds for external auditory canal wall.

PubMed

Mota, Carlos; Milazzo, Mario; Panetta, Daniele; Trombi, Luisa; Gramigna, Vera; Salvadori, Piero A; Giannotti, Stefano; Bruschini, Luca; Stefanini, Cesare; Moroni, Lorenzo; Berrettini, Stefano; Danti, Serena

2018-05-07

The external auditory canal (EAC) is an osseocartilaginous structure extending from the auricle to the eardrum, which can be affected by congenital, inflammatory, and neoplastic diseases, thus reconstructive materials are needed. Current biomaterial-based approaches for the surgical reconstruction of EAC posterior wall still suffer from resorption (biological) and extrusion (synthetic). In this study, 3D fiber deposited scaffolds based on poly(ethylene oxide terephthalate)/poly(butylene terephthalate) were designed and fabricated to replace the EAC wall. Fiber diameter and scaffold porosity were optimized, leading to 200 ± 33 µm and 55% ± 5%, respectively. The mechanical properties were evaluated, resulting in a Young's modulus of 25.1 ± 7.0 MPa. Finally, the EAC scaffolds were tested in vitro with osteo-differentiated human mesenchymal stromal cells (hMSCs) with different seeding methods to produce homogeneously colonized replacements of interest for otologic surgery. This study demonstrated the fabrication feasibility of EAC wall scaffolds aimed to match several important requirements for biomaterial application to the ear under the Tissue Engineering paradigm, including shape, porosity, surface area, mechanical properties and favorable in vitro interaction with osteoinduced hMSCs. This study demonstrated the fabrication feasibility of outer ear canal wall scaffolds via additive manufacturing. Aimed to match several important requirements for biomaterial application to ear replacements under the Tissue Engineering paradigm, including shape, porosity and pore size, surface area, mechanical properties and favorable in vitro interaction with osteo-differentiated mesenchymal stromal cells.

Nanoscale Mechanism of Composite Reinforcement by Fibers and Filler, Theoretical Computation and Experimental Validation of the Theory Using Rubber/Short Carbon Fiber Compounds

DTIC Science & Technology

2005-06-24

for an adhesion-active surface. 2.8.2 Dupre’s equation Let adhesive interaction between two bodies take place. Dupre’s equation defines the...connection between work of external forces on system of two bodies with adhesive interaction contact, the potential energies these bodies and the energy...Lagrangian of system of two bodies with adhesion interaction is equal half of work of external forces enclosed to this system” With the help of

Investigation of laser induced parametric interactions in optical waveguides and fibers

NASA Technical Reports Server (NTRS)

Yu, C.

1978-01-01

Experimental and theoretical aspects of the laser pump depletion characteristics in an optical fiber due to stimulated Raman scattering, and stimulated Brillouin scattering were studied. A review is presented of research in fiber transmission accompanied by stimulated scattering. Results of experimental work with tunable dye lasers and argon lasers are presented. The spectral profiles of the laser pump and its transmitted light through the fiber are given.

Fiber optic refractive index and magnetic field sensors based on microhole-induced inline Mach-Zehnder interferometers

NASA Astrophysics Data System (ADS)

Chen, Feifei; Jiang, Yi; Zhang, Liuchao; Jiang, Lan; Wang, Sumei

2018-04-01

A compact microhole-induced fiber optic inline Mach-Zehnder interferometer (MZI) is demonstrated for measurements of refractive index (RI) and magnetic field. Inline MZIs with different etched diameters, different interaction lengths and different sizes of microholes are fabricated and assessed. The optical transmission spectra of the inline MZIs immersed into a series of liquids are characterized and analysed. Experimental results show that liquid RI sensitivity as high as 539.8436 nm RIU-1 in the RI range of 1.3352-1.4113 RIU is achieved and also exhibits good linearity with a correlation coefficient  >93%. An inline MZI is also fabricated to be a magnetic field sensor by using magnetic fluid material. The experimental results show that this magnetic field sensor has a high sensitivity of  -275.6 pm Oe-1. The inline MZI-based fiber optic sensors possess many advantages, such as small size, simple fabrication, high sensitivity and good linearity, which has a wide application potential in chemical, biological and environmental sensing fields.

Connectome imaging for mapping human brain pathways

PubMed Central

Shi, Y; Toga, A W

2017-01-01

With the fast advance of connectome imaging techniques, we have the opportunity of mapping the human brain pathways in vivo at unprecedented resolution. In this article we review the current developments of diffusion magnetic resonance imaging (MRI) for the reconstruction of anatomical pathways in connectome studies. We first introduce the background of diffusion MRI with an emphasis on the technical advances and challenges in state-of-the-art multi-shell acquisition schemes used in the Human Connectome Project. Characterization of the microstructural environment in the human brain is discussed from the tensor model to the general fiber orientation distribution (FOD) models that can resolve crossing fibers in each voxel of the image. Using FOD-based tractography, we describe novel methods for fiber bundle reconstruction and graph-based connectivity analysis. Building upon these novel developments, there have already been successful applications of connectome imaging techniques in reconstructing challenging brain pathways. Examples including retinofugal and brainstem pathways will be reviewed. Finally, we discuss future directions in connectome imaging and its interaction with other aspects of brain imaging research. PMID:28461700

Perspectives of powerful laser technique for medicine

NASA Astrophysics Data System (ADS)

Konov, Vitali I.; Prokhorov, Alexander M.; Shcherbakov, Ivan A.

1991-11-01

The optimum laser-system parameters are being selected for several types of surgical operations using ablation techniques. The choice is based on the specific demands of the operation performed, knowledge of the ablation laws, limitations on laser-beam intensity which come from the necessity to transport high-intensity light through flexible fiber, and the peculiarities of different laser systems. At present it is more expedient to develop laser medical setups oriented to the solution of one task or a limited number of problems. The choice of a concrete installation should be based on the investigation results of interaction of radiation with biological tissues and its transmission through the fiber, the analysis of the level of development of laser and fiber technique, specificity of the operation, and compatibility of laser facilitates and traditional medical equipment. The paper illustrates such an approach by way of several concrete examples and notes the corresponding laser systems, which were developed or are in the developmental stage in the General Physics Institute of the USSR Academy of Sciences and in organizations connected with the Institute.

Etching twin core fiber for the temperature-independent refractive index sensing

NASA Astrophysics Data System (ADS)

Zhang, Chuanbiao; Ning, Tigang; Li, Jing; Zheng, Jingjing; Gao, Xuekai; Lin, Heng; Pei, Li

2018-04-01

We proposed an ultra-compact chemically etched twin core fiber (TCF) based optic refractive index (RI) sensor, in which the etched fiber was fabricated by immersing in an aqueous solution of hydrofluoric acid (HF) to etch the cladding. Due to the multipath evolutions of light during the TCF, the mode induced interference pattern can be used for measurement. Numerical simulations were performed, demonstrating that only the cladding mode strongly interacts with the surrounding media, and the higher cladding modes will be more sensitive to external medium. In the experiment demonstration, the RI response characteristics of the sensor were investigated, which shows a relatively high RI sensitivity and a much low temperature cross-sensitivity with about 1.06 × 10-6 RIU °C-1. Due to low cost and easy fabrication, the sensor can be a suitable candidate in the biochemical field.

Strain monitoring of bismaleimide composites using embedded microcavity sensor

NASA Astrophysics Data System (ADS)

Kaur, Amardeep; Anandan, Sudharshan; Yuan, Lei; Watkins, Steve E.; Chandrashekhara, K.; Xiao, Hai; Phan, Nam

2016-03-01

A type of extrinsic Fabry-Perot interferometer (EFPI) fiber optic sensor, i.e., the microcavity strain sensor, is demonstrated for embedded, high-temperature applications. The sensor is fabricated using a femtosecond (fs) laser. The fs-laser-based fabrication makes the sensor thermally stable to sustain operating temperatures as high as 800°C. The sensor has low sensitivity toward the temperature as compared to its response toward the applied strain. The performance of the EFPI sensor is tested in an embedded application. The host material is carbon fiber/bismaleimide (BMI) composite laminate that offer thermally stable characteristics at high ambient temperatures. The sensor exhibits highly linear response toward the temperature and strain. Analytical work done with embedded optical-fiber sensors using the out-of-autoclave BMI laminate was limited until now. The work presented in this paper offers an insight into the strain and temperature interactions of the embedded sensors with the BMI composites.

Computational modeling of three-dimensional ECM-rigidity sensing to guide directed cell migration.

PubMed

Kim, Min-Cheol; Silberberg, Yaron R; Abeyaratne, Rohan; Kamm, Roger D; Asada, H Harry

2018-01-16

Filopodia have a key role in sensing both chemical and mechanical cues in surrounding extracellular matrix (ECM). However, quantitative understanding is still missing in the filopodial mechanosensing of local ECM stiffness, resulting from dynamic interactions between filopodia and the surrounding 3D ECM fibers. Here we present a method for characterizing the stiffness of ECM that is sensed by filopodia based on the theory of elasticity and discrete ECM fiber. We have applied this method to a filopodial mechanosensing model for predicting directed cell migration toward stiffer ECM. This model provides us with a distribution of force and displacement as well as their time rate of changes near the tip of a filopodium when it is bound to the surrounding ECM fibers. Aggregating these effects in each local region of 3D ECM, we express the local ECM stiffness sensed by the cell and explain polarity in the cellular durotaxis mechanism.

Physics of the Brain. Prevention of the Epileptic Seizures by the Multi-photon Pulsed-operated Fiber Lasers in the Ultraviolet Range of Frequencies.

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander; IAPS Team

The novel study of the epileptogenesis mechanisms is proposed. It is based on the pulsed-operated (amplitude modulation) multi-photon (frequency modulation) fiber-laser interaction with the brain epilepsy-topion (the epilepsy onset area), so as to prevent the excessive electrical discharge (epileptic seizure) in the brain. The repetition frequency, Ω, matches the low frequency (epileptic) phonon waves in the brain. The laser repetition frequency (5-100 pulses per second) enables the resonance-scanning of the wide range of the phonon (possible epileptic-to-be) activity in the brain. The tunable fiber laser frequencies, Δω (multi photon operation), are in the ultraviolet frequency range, thus enabling monitoring of the electrical charge imbalance (within the 10s of milliseconds), and the DNA-corruption in the epilepsy-topion, as the possible cause of the disease. Supported by Nikola Tesla Labs., Stefan University.

Effect of part thickness, glass fiber and crystallinity on light scattering during laser transmission welding of thermoplastics

NASA Astrophysics Data System (ADS)

Xu, Xin Feng; Parkinson, Alexander; Bates, Philip J.; Zak, Gene

2015-12-01

It is important to understand how laser energy scatters within the transparent component in order to predict and optimize the laser transmission welding process. This paper examines the influence of part thickness, glass fiber and crystallinity levels on the distribution of laser light after transmission through amorphous polycarbonate (PC) and semi-crystalline polymers such as polyamide 6 (PA6), polypropylene (PP), and polyethylene (PE). An experimental technique based on laser-scanned lines of progressively increasing power was used to assess the transmitted energy distribution. This distribution was characterized using a two-parameter model that captures scattered and un-scattered components of the laser beam. The results clearly show how the scattering is increased by increasing the numbers of interactions between laser light and phase boundaries either by increasing the particle concentration (i.e., glass fiber level and crystallinity) or increasing part thickness.

Black phosphorus: a two-dimension saturable absorption material for mid-infrared Q-switched and mode-locked fiber lasers

PubMed Central

Li, Jianfeng; Luo, Hongyu; Zhai, Bo; Lu, Rongguo; Guo, Zhinan; Zhang, Han; Liu, Yong

2016-01-01

Black phosphorus (BP) as a novel class of two-dimension (2D) materials has recently attracted enormous attention as a result of its unique physical and chemical features. The remarkably strong light-matter interaction and tunable direct band-gap at a wide range make it an ideal candidate especially in the mid-infrared wavelength region as the saturable absorber (SA). In this paper, the simple and effective liquid phase exfoliation (LPE) method was used to fabricate BP. By introducing the same BP SA into two specifically designed rare earth ions doped fluoride fiber lasers at mid-infrared wavebands, Q-switching with the pulse energy of 4.93 μJ and mode-locking with the pulse duration of 8.6 ps were obtained, respectively. The operation wavelength of ~2970 nm for generated pulse is the reported longest wavelength for BP SA based fiber lasers. PMID:27457338

Microcautery based on zinc metallic nanoparticles photodeposited on the core of an optical fiber

NASA Astrophysics Data System (ADS)

Zaca-Morán, P.; Pastelín, C. F.; Morán, C.; Pérez-Sánchez, G. F.; Chávez, F.

2017-01-01

The experimental arrangement of a microcautery implemented by an optical fiber with zinc nanoparticles (ZnNPs) photodeposited on its core for the cauterization and coagulation in blood vessels hemostasis processes is presented. The interaction between a laser radiation source and the ZnNPS on the fiber core produces a controllable punctual heat source through the radiation intensity, which is capable of reaching a temperature up to 200 °C covering an area of approximately ten micrometers. By using three-to-four-month-old rats of CIIZ-V strain, we made several microcauterization experimental tests to stop blood flow. The findings show that the microcautery obliterates the smooth muscle of the blood vessels concatenating mutually to tissue in an average time of three seconds, at the same time, the blood elements responsible for the coagulation are thermally activated and thus the bleeding is stopped.

Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Holbery, Jim; Smith, Mark T.

2006-11-30

This report describes the status of the current process modeling approaches to predict the behavior and flow of fiber-filled thermoplastics under injection molding conditions. Previously, models have been developed to simulate the injection molding of short-fiber thermoplastics, and an as-formed composite part or component can then be predicted that contains a microstructure resulting from the constituents’ material properties and characteristics as well as the processing parameters. Our objective is to assess these models in order to determine their capabilities and limitations, and the developments needed for long-fiber injection-molded thermoplastics (LFTs). First, the concentration regimes are summarized to facilitate the understandingmore » of different types of fiber-fiber interaction that can occur for a given fiber volume fraction. After the formulation of the fiber suspension flow problem and the simplification leading to the Hele-Shaw approach, the interaction mechanisms are discussed. Next, the establishment of the rheological constitutive equation is presented that reflects the coupled flow/orientation nature. The decoupled flow/orientation approach is also discussed which constitutes a good simplification for many applications involving flows in thin cavities. Finally, before outlining the necessary developments for LFTs, some applications of the current orientation model and the so-called modified Folgar-Tucker model are illustrated through the fiber orientation predictions for selected LFT samples.« less

The Cotton Kinesin-Like Calmodulin-Binding Protein Associates with Cortical Microtubles in Cotton Fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preuss, Mary L.; Delmar, Deborah P.; Liu, Bo

Microtubules in interphase plant cells form a cortical array, which is critical for plant cell morphogenesis. Genetic studies imply that the minus end-directed microtubule motor kinesin-like calmodulin-binding protein (KCBP) plays a role in trichome morphogenesis in Arabidopsis. However, it was not clear whether this motor interacted with interphase microtubules. In cotton (Gossypium hirsutum) fibers, cortical microtubules undergo dramatic reorganization during fiber development. In this study, cDNA clones of the cotton KCBP homolog GhKCBP were isolated from a cotton fiber-specific cDNA library. During cotton fiber development from 10 to 21 DPA, the GhKCBP protein level gradually decreases. By immunofluorescence, GhKCBP wasmore » detected as puncta along cortical microtubules in fiber cells of different developmental stages. Thus the results provide evidence that GhKCBP plays a role in interphase cell growth likely by interacting with cortical microtubules. In contrast to fibers, in dividing cells of cotton, GhKCBP localized to the nucleus, the microtubule preprophase band, mitotic spindle, and the phragmoplast. Therefore KCBP likely exerts multiple roles in cell division and cell growth in flowering plants.« less

OPTOELECTRONICS, FIBER OPTICS, AND OTHER ASPECTS OF QUANTUM ELECTRONICS: Interference-threshold storage of optical data

NASA Astrophysics Data System (ADS)

Efimkov, V. F.; Zubarev, I. G.; Kolobrodov, V. V.; Sobolev, V. B.

1989-08-01

A method for the determination of the spatial characteristics of a laser beam is proposed and implemented. This method is based on the interaction of an interference field of two laser beams, which are spatially similar to the one being investigated, with a light-sensitive material characterized by a sensitivity threshold.

Polymers in the gut compress the colonic mucus hydrogel

PubMed Central

Datta, Sujit S.; Preska Steinberg, Asher

2016-01-01

Colonic mucus is a key biological hydrogel that protects the gut from infection and physical damage and mediates host–microbe interactions and drug delivery. However, little is known about how its structure is influenced by materials it comes into contact with regularly. For example, the gut abounds in polymers such as dietary fibers or administered therapeutics, yet whether such polymers interact with the mucus hydrogel, and if so, how, remains unclear. Although several biological processes have been identified as potential regulators of mucus structure, the polymeric composition of the gut environment has been ignored. Here, we demonstrate that gut polymers do in fact regulate mucus hydrogel structure, and that polymer–mucus interactions can be described using a thermodynamic model based on Flory–Huggins solution theory. We found that both dietary and therapeutic polymers dramatically compressed murine colonic mucus ex vivo and in vivo. This behavior depended strongly on both polymer concentration and molecular weight, in agreement with the predictions of our thermodynamic model. Moreover, exposure to polymer-rich luminal fluid from germ-free mice strongly compressed the mucus hydrogel, whereas exposure to luminal fluid from specific-pathogen-free mice—whose microbiota degrade gut polymers—did not; this suggests that gut microbes modulate mucus structure by degrading polymers. These findings highlight the role of mucus as a responsive biomaterial, and reveal a mechanism of mucus restructuring that must be integrated into the design and interpretation of studies involving therapeutic polymers, dietary fibers, and fiber-degrading gut microbes. PMID:27303035

Polymers in the gut compress the colonic mucus hydrogel.

PubMed

Datta, Sujit S; Preska Steinberg, Asher; Ismagilov, Rustem F

2016-06-28

Colonic mucus is a key biological hydrogel that protects the gut from infection and physical damage and mediates host-microbe interactions and drug delivery. However, little is known about how its structure is influenced by materials it comes into contact with regularly. For example, the gut abounds in polymers such as dietary fibers or administered therapeutics, yet whether such polymers interact with the mucus hydrogel, and if so, how, remains unclear. Although several biological processes have been identified as potential regulators of mucus structure, the polymeric composition of the gut environment has been ignored. Here, we demonstrate that gut polymers do in fact regulate mucus hydrogel structure, and that polymer-mucus interactions can be described using a thermodynamic model based on Flory-Huggins solution theory. We found that both dietary and therapeutic polymers dramatically compressed murine colonic mucus ex vivo and in vivo. This behavior depended strongly on both polymer concentration and molecular weight, in agreement with the predictions of our thermodynamic model. Moreover, exposure to polymer-rich luminal fluid from germ-free mice strongly compressed the mucus hydrogel, whereas exposure to luminal fluid from specific-pathogen-free mice-whose microbiota degrade gut polymers-did not; this suggests that gut microbes modulate mucus structure by degrading polymers. These findings highlight the role of mucus as a responsive biomaterial, and reveal a mechanism of mucus restructuring that must be integrated into the design and interpretation of studies involving therapeutic polymers, dietary fibers, and fiber-degrading gut microbes.

[Development and perspective of bio-based chemical fiber industry].

PubMed

Li, Zengjun

2016-06-25

Bio-based fiber is environment friendly, reproducible, easily biodegradable. Therefore, rapid development of bio-based fiber industry is an obvious in progress to replace petrochemical resources, develop sustainable economy, build resource saving and environment friendly society. This article describes the current development of bio-based fiber industry, analyzes existing problems, indicates the trends and objectives of bio-based fiber materials technology innovation and recommends developing bio-based fibers industry of our country.

3D Finite Element Models of Shoulder Muscles for Computing Lines of Actions and Moment Arms

PubMed Central

Webb, Joshua D.; Blemker, Silvia S.; Delp, Scott L.

2014-01-01

Accurate representation of musculoskeletal geometry is needed to characterize the function of shoulder muscles. Previous models of shoulder muscles have represented muscle geometry as a collection of line segments, making it difficult to account the large attachment areas, muscle-muscle interactions, and complex muscle fiber trajectories typical of shoulder muscles. To better represent shoulder muscle geometry we developed three-dimensional finite element models of the deltoid and rotator cuff muscles and used the models to examine muscle function. Muscle fiber paths within the muscles were approximated, and moment arms were calculated for two motions: thoracohumeral abduction and internal/external rotation. We found that muscle fiber moment arms varied substantially across each muscle. For example, supraspinatus is considered a weak external rotator, but the three-dimensional model of supraspinatus showed that the anterior fibers provide substantial internal rotation while the posterior fibers act as external rotators. Including the effects of large attachment regions and three-dimensional mechanical interactions of muscle fibers constrains muscle motion, generates more realistic muscle paths, and allows deeper analysis of shoulder muscle function. PMID:22994141

High-power graphene mode-locked Tm/Ho co-doped fiber laser with evanescent field interaction.

PubMed

Li, Xiaohui; Yu, Xuechao; Sun, Zhipei; Yan, Zhiyu; Sun, Biao; Cheng, Yuanbing; Yu, Xia; Zhang, Ying; Wang, Qi Jie

2015-11-16

Mid-infrared ultrafast fiber lasers are valuable for various applications, including chemical and biomedical sensing, material processing and military applications. Here, we report all-fiber high-power graphene mode-locked Tm/Ho co-doped fiber laser at long wavelength with evanescent field interaction. Ultrafast pulses up to 7.8 MHz are generated at a center wavelength of 1879.4 nm, with a pulse width of 4.7 ps. A graphene absorber integrated with a side-polished fiber can increase the damage threshold significantly. Harmonics mode-locking can be obtained till to the 21(th) harmonics at a pump power of above 500 mW. By using one stage amplifier in the anomalous dispersion regime, the laser can be amplified up to 450 mW and the narrowest pulse duration of 1.4 ps can be obtained simultaneously. Our work paves the way to graphene Tm/Ho co-doped mode-locked all-fiber master oscillator power amplifiers as potentially efficient and economic laser sources for high-power laser applications, such as special material processing and nonlinear optical studies.

Bidirectional fiber-wireless and fiber-VLLC transmission system based on an OEO-based BLS and a RSOA.

PubMed

Lu, Hai-Han; Li, Chung-Yi; Lu, Ting-Chien; Wu, Chang-Jen; Chu, Chien-An; Shiva, Ajay; Mochii, Takao

2016-02-01

A bidirectional fiber-wireless and fiber-visible-laser-light-communication (VLLC) transmission system based on an optoelectronic oscillator (OEO)-based broadband light source (BLS) and a reflective semiconductor optical amplifier (RSOA) is proposed and experimentally demonstrated. Through an in-depth observation of such bidirectional fiber-wireless and fiber-VLLC transmission systems, good bit error rate performances are obtained over a 40 km single-mode fiber and a 10 m RF/optical wireless transport. Such a bidirectional fiber-wireless and fiber-VLLC transmission system is an attractive option for providing broadband integrated services.

All-fiber mode-locked laser oscillator with pulse energy of 34 nJ using a single-walled carbon nanotube saturable absorber.

PubMed

Jeong, Hwanseong; Choi, Sun Young; Rotermund, Fabian; Cha, Yong-Ho; Jeong, Do-Young; Yeom, Dong-Il

2014-09-22

We demonstrate a dissipative soliton fiber laser with high pulse energy (>30 nJ) based on a single-walled carbon nanotube saturable absorber (SWCNT-SA). In-line SA that evanescently interacts with the high quality SWCNT/polymer composite film was fabricated under optimized conditions, increasing the damage threshold of the saturation fluence of the SA to 97 mJ/cm(2). An Er-doped mode-locked all-fiber laser operating at net normal intra-cavity dispersion was built including the fabricated in-line SA. The laser stably delivers linearly chirped pulses with a pulse duration of 12.7 ps, and exhibits a spectral bandwidth of 12.1 nm at the central wavelength of 1563 nm. Average power of the laser output is measured as 335 mW at an applied pump power of 1.27 W. The corresponding pulse energy is estimated to be 34 nJ at the fundamental repetition rate of 9.80 MHz; this is the highest value, to our knowledge, reported in all-fiber Er-doped mode-locked laser using an SWCNT-SA.

Inelastic response of metal matrix composites under biaxial loading

NASA Technical Reports Server (NTRS)

Lissenden, C. J.; Mirzadeh, F.; Pindera, M.-J.; Herakovich, C. T.

1991-01-01

Theoretical predictions and experimental results were obtained for inelastic response of unidirectional and angle ply composite tubes subjected to axial and torsional loading. The composite material consist of silicon carbide fibers in a titanium alloy matrix. This material is known to be susceptible to fiber matrix interfacial damage. A method to distinguish between matrix yielding and fiber matrix interfacial damage is suggested. Biaxial tests were conducted on the two different layup configurations using an MTS Axial/Torsional load frame with a PC based data acquisition system. The experimentally determined elastic moduli of the SiC/Ti system are compared with those predicted by a micromechanics model. The test results indicate that fiber matrix interfacial damage occurs at relatively low load levels and is a local phenomenon. The micromechanics model used is the method of cells originally proposed by Aboudi. Finite element models using the ABACUS finite element program were used to study end effects and fixture specimen interactions. The results to date have shown good correlation between theory and experiment for response prior to damage initiation.

Measurement of gas viscosity using photonic crystal fiber

NASA Astrophysics Data System (ADS)

Gao, R.-K.; Sheehe, S. L.; Kurtz, J.; O'Byrne, S.

2016-11-01

A new measurement technique for gas viscosity coefficient is designed and demonstrated using the technique of tunable diode laser absorption spectroscopy (TDLAS). Gas flow is driven by a pressure gradient between two gas cells, through a photonic crystal fiber (PCF) surrounded by a furnace for temperature adjustment. PCF with 20-micron diameter affords physical space for gas-light interaction and provides a basis for gas viscosity measurement by determining the time for flow to exit a capillary tube under the influence of a pressure gradient. Infrared radiation from a diode laser is coupled into the fiber to be guided through the gas, and the light attenuation due to absorption from the molecular absorbing species is measured by a photo detector placed at the exit of the fiber. A numerical model from Sharipov and Graur describing local number density distribution in a unsteady state is applied for the determination of gas viscosity, based on the number density of gas measured by the absorption of the laser light, using the Beer-Lambert law. The measurement system is confirmed by measuring the viscosity of CO2 as a reference gas.

A Structural Finite Element Model for Lamellar Unit of Aortic Media Indicates Heterogeneous Stress Field After Collagen Recruitment

PubMed Central

Thunes, James R.; Pal, Siladitya; Fortunato, Ronald N.; Phillippi, Julie A.; Gleason, Thomas G.; Vorp, David A.; Maiti, Spandan

2016-01-01

Incorporation of collagen structural information into the study of biomechanical behavior of ascending thoracic aortic (ATA) wall tissue should provide better insight into the pathophysiology of ATA. Structurally motivated constitutive models that include fiber dispersion and recruitment can successfully capture overall mechanical response of the arterial wall tissue. However, these models cannot examine local microarchitectural features of the collagen network, such as the effect of fiber disruptions and interaction between fibrous and non-fibrous components, which may influence emergent biomechanical properties of the tissue. Motivated by this need, we developed a finite element based three-dimensional structural model of the lamellar units of the ATA media that directly incorporates the collagen fiber microarchitecture. The fiber architecture was computer generated utilizing network features, namely fiber orientation distribution, intersection density and areal concentration, obtained from image analysis of multiphoton microscopy images taken from human aneurysmal ascending thoracic aortic media specimens with bicuspid aortic valve (BAV) phenotype. Our model reproduces the typical J-shaped constitutive response of the aortic wall tissue. We found that the stress state in the non-fibrous matrix was homogeneous until the collagen fibers were recruited, but became highly heterogeneous after that event. The degree of heterogeneity was dependent upon local network architecture with high stresses observed near disrupted fibers. The magnitude of non-fibrous matrix stress at higher stretch levels was negatively correlated with local fiber density. The localized stress concentrations, elucidated by this model, may be a factor in the degenerative changes in aneurysmal ATA tissue. PMID:27113538

Mechanisms of Plastic Deformation in Collagen Networks Induced by Cellular Forces.

PubMed

Ban, Ehsan; Franklin, J Matthew; Nam, Sungmin; Smith, Lucas R; Wang, Hailong; Wells, Rebecca G; Chaudhuri, Ovijit; Liphardt, Jan T; Shenoy, Vivek B

2018-01-23

Contractile cells can reorganize fibrous extracellular matrices and form dense tracts of fibers between neighboring cells. These tracts guide the development of tubular tissue structures and provide paths for the invasion of cancer cells. Here, we studied the mechanisms of the mechanical plasticity of collagen tracts formed by contractile premalignant acinar cells and fibroblasts. Using fluorescence microscopy and second harmonic generation, we quantified the collagen densification, fiber alignment, and strains that remain within the tracts after cellular forces are abolished. We explained these observations using a theoretical fiber network model that accounts for the stretch-dependent formation of weak cross-links between nearby fibers. We tested the predictions of our model using shear rheology experiments. Both our model and rheological experiments demonstrated that increasing collagen concentration leads to substantial increases in plasticity. We also considered the effect of permanent elongation of fibers on network plasticity and derived a phase diagram that classifies the dominant mechanisms of plasticity based on the rate and magnitude of deformation and the mechanical properties of individual fibers. Plasticity is caused by the formation of new cross-links if moderate strains are applied at small rates or due to permanent fiber elongation if large strains are applied over short periods. Finally, we developed a coarse-grained model for plastic deformation of collagen networks that can be employed to simulate multicellular interactions in processes such as morphogenesis, cancer invasion, and fibrosis. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Fermentation of Ammonia Fiber Expansion Treated and Untreated Barley Straw in a Rumen Simulation Technique Using Rumen Inoculum from Cattle with Slow versus Fast Rate of Fiber Disappearance.

PubMed

Griffith, Candace L; Ribeiro, Gabriel O; Oba, Masahito; McAllister, Tim A; Beauchemin, Karen A

2016-01-01

The purpose of this study was to determine the effect of rumen inoculum from heifers with fast vs. slow rate of in situ fiber digestion on the fermentation of complex versus easily digested fiber sources in the forms of untreated and Ammonia Fiber Expansion (AFEX) treated barley straw, respectively, using an artificial rumen simulation technique (Rusitec). In situ fiber digestion was measured in a previous study by incubating untreated barley straw in the rumen of 16 heifers fed a diet consisting of 700 g/kg barley straw and 300 g/kg concentrate. The two heifers with fastest rate of digestion (Fast ≥ 4.18% h -1 ) and the two heifers with the slowest rate of digestion (Slow ≤ 3.17% h -1 ) were chosen as inoculum donors for this study. Two Rusitec apparatuses each equipped with eight fermenters were used in a completely randomized block design with two blocks (apparatus) and four treatments in a 2 × 2 factorial arrangement of treatments (Fast or Slow rumen inoculum and untreated or AFEX treated straw). Fast rumen inoculum and AFEX straw both increased ( P < 0.05) disappearance of dry matter (DMD), organic matter, true DMD, neutral detergent fiber, acid detergent fiber, and nitrogen (N) with an interactive effect between the two ( P < 0.05). Fast rumen inoculum increased ( P > 0.05) methane production per gram of digested material for both untreated and AFEX straw, and reduced (interaction, P < 0.05) acetate: propionate ratio for untreated straw. Greater relative populations of Ruminococcus albus ( P < 0.05) and increased microbial N production ( P = 0.045) were observed in Fast rumen inoculum. AFEX straw in Fast inoculum had greater total bacterial populations than Slow, but for untreated straw this result was reversed (interaction, P = 0.013). These findings indicate that differences in microbial populations in rumen fluid contribute to differences in the capacity of rumen inoculum to digest fiber.

Polarization dependence of Brillouin linewidth and peak frequency due to fiber inhomogeneity in single mode fiber and its impact on distributed fiber Brillouin sensing.

PubMed

Xie, Shangran; Pang, Meng; Bao, Xiaoyi; Chen, Liang

2012-03-12

The dependence of Brillouin linewidth and peak frequency on lightwave state of polarization (SOP) due to fiber inhomogeneity in single mode fiber (SMF) is investigated by using Brillouin optical time domain analysis (BOTDA) system. Theoretical analysis shows fiber inhomogeneity leads to fiber birefringence and sound velocity variation, both of which can cause the broadening and asymmetry of the Brillouin gain spectrum (BGS) and thus contribute to the variation of Brillouin linewidth and peak frequency with lightwave SOP. Due to fiber inhomogeneity both in lateral profile and longitudinal direction, the measured BGS is the superposition of several spectrum components with different peak frequencies within the interaction length. When pump or probe SOP changes, both the peak Brillouin gain and the overlapping area of the optical and acoustic mode profile that determine the peak efficiency of each spectrum component vary within the interaction length, which further changes the linewidth and peak frequency of the superimposed BGS. The SOP dependence of Brillouin linewidth and peak frequency was experimentally demonstrated and quantified by measuring the spectrum asymmetric factor and fitting obtained effective peak frequency respectively via BOTDA system on standard step-index SMF-28 fiber. Experimental results show that on this fiber the Brillouin spectrum asymmetric factor and effective peak frequency vary in the range of 2% and 0.06MHz respectively over distance with orthogonal probe input SOPs. Experimental results also show that in distributed fiber Brillouin sensing, polarization scrambler (PS) can be used to reduce the SOP dependence of Brillouin linewidth and peak frequency caused by fiber inhomogeneity in lateral profile, however it maintains the effects caused by fiber inhomogeneity in longitudinal direction. In the case of non-ideal polarization scrambling using practical PS, the fluctuation of effective Brillouin peak frequency caused by fiber inhomogeneity provides another limit of sensing frequency resolution of distributed fiber Brillouin sensor.

β-Glucans and Resistant Starch Alter the Fermentation of Recalcitrant Fibers in Growing Pigs

PubMed Central

Gerrits, Walter J. J.; Kabel, Mirjam A.; Vasanthan, Thava; Zijlstra, Ruurd T.

2016-01-01

Interactions among dietary ingredients are often assumed non-existent when evaluating the nutritive value and health effects of dietary fiber. Specific fibers can distinctly affect digestive processes; therefore, digestibility and fermentability of the complete diet may depend on fiber types present. This study aimed to evaluate the effects of readily fermentable fibers (β-glucans and resistant starch) on the degradation of feed ingredients containing more persistent, recalcitrant, fibers. Six semi-synthetic diets with recalcitrant fibers from rapeseed meal (pectic polysaccharides, xyloglucans, and cellulose) or corn distillers dried grain with solubles (DDGS; (glucurono)arabinoxylans and cellulose) with or without inclusion of β-glucans (6%) or retrograded tapioca (40%) substituted for corn starch were formulated. Six ileal-cannulated pigs (BW 28±1.4 kg) were assigned to the diets according to a 6×6 Latin square. β-glucan-extract increased apparent total tract digestibility (ATTD) of non-glucosyl polysaccharides (accounting for ~40% of the fiber-fraction) from rapeseed meal (6%-units, P<0.001), but did not affect non-glucosyl polysaccharides from DDGS. Retrograded tapioca reduced ATTD of non-glucosyl polysaccharides from rapeseed meal and DDGS (>10%-units, P<0.001), indicating that the large amount of resistant starch entering the hindgut was preferentially degraded over recalcitrant fibers from rapeseed meal and DDGS, possibly related to reduced hindgut-retention time following the increased intestinal bulk. Fermentation of fiber sources was not only dependent on fiber characteristics, but also on the presence of other fibers in the diet. Hence, interactions in the gastrointestinal tract among fibrous feed ingredients should be considered when evaluating their nutritive value. PMID:27911928

Transport of Spherical Particles Through Fibrous Media and a Row of Parallel Cylinders: Applications to Glomerular Filtration.

PubMed

Punyaratabandhu, Numpong; Kongoup, Pimkhwan; Dechadilok, Panadda; Katavetin, Pisut; Triampo, Wannapong

2017-12-01

Viewed in renal physiology as a refined filtration device, the glomerulus filters large volumes of blood plasma while keeping proteins within blood circulation. Effects of macromolecule size and macromolecule hydrodynamic interaction with the nanostructure of the cellular layers of the glomerular capillary wall on the glomerular size selectivity are investigated through a mathematical simulation based on an ultrastructural model. The epithelial slit, a planar arrangement of fibers connecting the epithelial podocytes, is represented as a row of parallel cylinders with nonuniform spacing between adjacent fibers. The mean and standard deviation of gap half-width between its fibers are based on values recently reported from electron microscopy. The glomerular basement membrane (GBM) is represented as a fibrous medium containing fibers of two different sizes: the size of type IV collagens and that of glycosaminoglycans (GAGs). The endothelial cell layer is modeled as a layer full of fenestrae that are much larger than solute size and filled with GAGs. The calculated total sieving coefficient agrees well with the sieving coefficients of ficolls obtained from in vivo urinalysis in humans, whereas the computed glomerular hydraulic permeability also falls within the range estimated from human glomerular filtration rate (GFR). Our result indicates that the endothelial cell layer and GBM significantly contribute to solute and fluid restriction of the glomerular barrier, whereas, based on the structure of the epithelial slit obtained from electron microscopy, the contribution of the epithelial slit could be smaller than previously believed.

Blind I/Q imbalance and nonlinear ISI mitigation in Nyquist-SCM direct detection system with cascaded widely linear and Volterra equalizer

NASA Astrophysics Data System (ADS)

Liu, Na; Ju, Cheng

2018-02-01

Nyquist-SCM signal after fiber transmission, direct detection (DD), and analog down-conversion suffers from linear ISI, nonlinear ISI, and I/Q imbalance, simultaneously. Theoretical analysis based on widely linear (WL) and Volterra series is given to explain the relationship and interaction of these three interferences. A blind equalization algorithm, cascaded WL and Volterra equalizer, is designed to mitigate these three interferences. Furthermore, the feasibility of the proposed cascaded algorithm is experimentally demonstrated based on a 40-Gbps data rate 16-quadrature amplitude modulation (QAM) virtual single sideband (VSSB) Nyquist-SCM DD system over 100-km standard single mode fiber (SSMF) transmission. In addition, the performances of conventional strictly linear equalizer, WL equalizer, Volterra equalizer, and cascaded WL and Volterra equalizer are experimentally evaluated, respectively.

Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

NASA Technical Reports Server (NTRS)

Sodano, Henry A.; Brett, Robert

2011-01-01

The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

The effect of thiolated additives on the properties of wheat gluten based plastics, aqueous solutions and electrospun fibers

NASA Astrophysics Data System (ADS)

Dong, Jing

Wheat gluten (WG) is a promising substitute for petroleum-based plastics due to its unique ability to form a cohesive blend with viscoelastic properties once plasticized. Previous work blending WG with thiolated poly(vinyl alcohol) (TPVA) showed that both the strength and elongation of compression molded native WG bars can be improved via thiol/disulfide interchange reactions between WG and TPVA. In this study, the morphology of WG/TPVA blends was investigated by atomic force (AFM) and transmission electron microscopy (TEM), as well as by modulated dynamic scanning calorimetry (MDSC). Consistent with our earlier results, AFM and TEM imaging clearly indicated that TPVA is much more compatible with WG compared with poly(vinyl alcohol) (PVA) although there are still two phases in the blend: one WG rich phase and another TPVA rich phase. TPVA was also blended with WG in an aqueous solvent (1/1 (v/v) water/1-propanol mixture) to improve its solubility and spinnability. Control experiments were conducted with PVA and dithiothreitol (DTT) for comparison purposes. The concentration and the thiolation level of TPVA were also varied to explore the parameter space. The interactions of thiol groups from TPVA and soluble WG were found to be important during electrospinning. The fiber diameter became more uniform and the fiber quality increased very noticeably when TPVA was included. Furthermore, the time-dependent rheology behaviors of TPVA/WG and DTT/WG electrospinning solutions were investigated by using steady shear sweeps, oscillatory frequency sweeps, SE-HPLC and free -SH content determination. A two-step mechanism of interaction was proposed for DTT/WG and TPVA/WG solutions based on current results and other earlier studies. In comparison with WG and PVA/WG solutions, the reduction and reformation of disulfide linkages in both TPVA/WG and DTT/WG solutions were believed to play a key role in determining the rheological properties and molecular weight distribution of WG fractions in the solution. Finally, the effect of thiol groups on the electrospinning behavior of pure TPVA aqueous solution was studied. It has found that the fiber quality was improved obviously within the first few days of solution preparation, while no fiber can be obtained when the viscosity became too high.

Effect of Surface Coverage of Gold Nanoparticles on the Refractive Index Sensitivity in Fiber-Optic Nanoplasmonic Sensing.

PubMed

Wu, Wei-Te; Chen, Chien-Hsing; Chiang, Chang-Yue; Chau, Lai-Kwan

2018-05-31

A simple theoretical model was developed to analyze the extinction spectrum of gold nanoparticles (AuNPs) on the fiber core and glass surfaces in order to aid the determination of the surface coverage and surface distribution of the AuNPs on the fiber core surface for sensitivity optimization of the fiber optic particle plasmon resonance (FOPPR) sensor. The extinction spectrum of AuNPs comprises of the interband absorption of AuNPs, non-interacting plasmon resonance (PR) band due to isolated AuNPs, and coupled PR band of interacting AuNPs. When the surface coverage is smaller than 12.2%, the plasmon coupling effect can almost be ignored. This method is also applied to understand the refractive index sensitivity of the FOPPR sensor with respect to the non-interacting PR band and the coupled PR band. In terms of wavelength sensitivity at a surface coverage of 18.6%, the refractive index sensitivity of the coupled PR band (205.5 nm/RIU) is greater than that of the non-interacting PR band (349.1 nm/RIU). In terms of extinction sensitivity, refractive index sensitivity of the coupled PR band (-3.86/RIU) is similar to that of the non-interacting PR band (-3.93/RIU). Both maximum wavelength and extinction sensitivities were found at a surface coverage of 15.2%.

Gain-assisted broadband ring cavity enhanced spectroscopy

NASA Astrophysics Data System (ADS)

Selim, Mahmoud A.; Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

2017-02-01

Incoherent broadband cavity enhanced spectroscopy can significantly increase the effective path length of light-matter interaction to detect weak absorption lines over broad spectral range, for instance to detect gases in confined environments. Broadband cavity enhancement can be based on the decay time or the intensity drop technique. Decay time measurement is based on using tunable laser source that is expensive and suffers from long scan time. Intensity dependent measurement is usually reported based on broadband source using Fabry-Perot cavity, enabling short measurement time but suffers from the alignment tolerance of the cavity and the cavity insertion loss. In this work we overcome these challenges by using an alignment-free ring cavity made of an optical fiber loop and a directional coupler, while having a gain medium pumped below the lasing threshold to improve the finesse and reduce the insertion loss. Acetylene (C2H2) gas absorption is measured around 1535 nm wavelength using a semiconductor optical amplifier (SOA) gain medium. The system is analyzed for different ring resonator forward coupling coefficient and loses, including the 3-cm long gas cell insertion loss and fiber connector losses used in the experimental verification. The experimental results are obtained for a coupler ratio of 90/10 and a fiber length of 4 m. The broadband source is the amplified spontaneous emission of another SOA and the output is measured using a 70pm-resolution optical spectrum analyzer. The absorption depth and the effective interaction length are improved about an order of magnitude compared to the direct absorption of the gas cell. The presented technique provides an engineering method to improve the finesse and, consequently the effective length, while relaxing the technological constraints on the high reflectivity mirrors and free-space cavity alignment.

The energy dissipative mechanisms of the particle-fiber interface in a textile composite

NASA Astrophysics Data System (ADS)

McAllister, Quinn Patrick

Impact resistant fabrics comprised of woven high performance fibers (e.g., Kevlar) have exhibited improved energy dissipative capability with the inclusion of nano- to micrometer sized particles. Upon impact, the particles embed and gouge adjacent fiber surfaces. While the particle-fiber interactions appear to be a primary mechanism for the increase in energy dissipation, the fundamentals of the nano- to micrometer sized gouging response of high performance fibers and the dissipation of energy due to particle gouging have not been studied previously. In this research, nanoindentation and nanoscratching techniques, which exploit probe sizes in the range of nano- to micrometers, were used to study the particle-fiber contact and develop nanoscale structure-property relationships of single Kevlar fibers. Atomic force microscopy based methods were used to create high resolution stiffness maps of fiber cross-sections, the results of which indicated that the stiffness of Kevlar 49 fibers is independent of radial position, while Kevlar KM2 fibers exhibit a reduced stiffness "shell" region (up to ˜300-350 nm thick). Instrumented indentation was used to evaluate the local response of Kevlar fibers with respect to orientation and contact size. For radial indentation, modifications to the traditional indentation analysis were developed to account for fiber curvature and finite size effects. A critical contact size was established above which the fiber response was independent of indenter size. This "homogeneous" response was used to estimate the local material properties of the Kevlar fibers through the application of an analytical model for indentation of a transversely isotropic material. The local properties of both fibers differed from their previously measured bulk properties, which was likely due, at least in part, to the deformation mechanisms of the fiber microstructure during indentation. Nanoindentation and nanoscratch tests were then conducted to study the deformation mechanisms of the fiber microstructure associated with a nano- to micrometer sized gouge of the fiber surface. Relationships between the observed mechanisms and the measured friction and energy were developed, resulting in new insights into the relevant energy dissipation processes of the particle-fiber interface. The level of apparent friction increased with increasing levels of strain imparted on the fiber surface, reaching values of up to ˜300% of the previously reported Kevlar yarn-yarn friction. Increased levels of friction during impact of a fabric have been shown to increase the energy required for the relative yarn translations, increasing the number of fibers strained and failed in tension. The energy of a single gouge made using probes exhibiting contact geometries similar to a particle-fiber contact was on the order of just 1% of the energy required to fail a fiber in tension (calculated based on a particle gouge and fiber tensile strain over one particle diameter). In the case of multiple particles distributed within a fabric, an impact event will involve energy dissipation from particle gouging, transverse fiber compression, and fiber tensile failure, where the ratio of the total energies associated with each of these processes was estimated to be on the order of 0.2:1:1 (assuming a limit at a transverse compressive strain of 0.3). Therefore, both the energy and the friction associated with particle gouging can increase the energy dissipative capabilities of a fabric, where the maximum contribution of the particle-fiber interface is likely related to the fabric's energy dissipative mechanisms that depend on friction.

Molecular Pathways: Gene-environment interactions regulating dietary fiber induction of proliferation and apoptosis via butyrate for cancer prevention

PubMed Central

Bultman, Scott J.

2013-01-01

Gene-environment interactions are so numerous and biologically complicated that it can be challenging to understand their role in cancer. However, dietary fiber and colorectal cancer prevention may represent a tractable model system. Fiber is fermented by colonic bacteria into short-chain fatty acids such as butyrate. One molecular pathway that has emerged involves butyrate having differential effects depending on its concentration and the metabolic state of the cell. Low-moderate concentrations, which are present near the base of colonic crypts, are readily metabolized in the mitochondria to stimulate cell proliferation via energetics. Higher concentrations, which are present near the lumen, exceed the metabolic capacity of the colonocyte. Unmetabolized butyrate enters the nucleus and functions as a histone deacetylase (HDAC) inhibitor that epigenetically regulates gene expression to inhibit cell proliferation and induce apoptosis as the colonocytes exfoliate into the lumen. Butyrate may therefore play a role in normal homeostasis by promoting turnover of the colonic epithelium. Because cancerous colonocytes undergo the Warburg effect, their preferred energy source is glucose instead of butyrate. Consequently, even moderate concentrations of butyrate accumulate in cancerous colonocytes and function as HDAC inhibitors to inhibit cell proliferation and induce apoptosis. These findings implicate a bacterial metabolite with metaboloepigenetic properties in tumor suppression. PMID:24270685

Opportunities and challenges for optical wireless: the competitive advantage of free space telecommunications links in today's crowded marketplace

NASA Astrophysics Data System (ADS)

Carbonneau, Theresa H.; Wisely, David R.

1998-01-01

Never before has the opportunity for terrestrial optical wireless communications links been so great. The high data rates attainable, up to OC-24, make it a very attractive and cost effective alternative to traditional fiber optic and microwave links. With today's demand for interactive multimedia-based applications, such as video conferencing and telemedicine, optical wireless products are the only ones that can provide the needed bandwidth in situations when it is too costly or impossible to install fiber optic cable. Recent developments in laser and optics technologies, in addition to auto beam tracking, permit transmission units to achieve excellent performance rates in all weather conditions.

On crystal versus fiber formation in dipeptide hydrogelator systems.

PubMed

Houton, Kelly A; Morris, Kyle L; Chen, Lin; Schmidtmann, Marc; Jones, James T A; Serpell, Louise C; Lloyd, Gareth O; Adams, Dave J

2012-06-26

Naphthalene dipeptides have been shown to be useful low-molecular-weight gelators. Here we have used a library to explore the relationship between the dipeptide sequence and the hydrogelation efficiency. A number of the naphthalene dipeptides are crystallizable from water, enabling us to investigate the comparison between the gel/fiber phase and the crystal phase. We succeeded in crystallizing one example directly from the gel phase. Using X-ray crystallography, molecular modeling, and X-ray fiber diffraction, we show that the molecular packing of this crystal structure differs from the structure of the gel/fiber phase. Although the crystal structures may provide important insights into stabilizing interactions, our analysis indicates a rearrangement of structural packing within the fibers. These observations are consistent with the fibrillar interactions and interatomic separations promoting 1D assembly whereas in the crystals the peptides are aligned along multiple axes, allowing 3D growth. This observation has an impact on the use of crystal structures to determine supramolecular synthons for gelators.

Genetic interaction of Neuroglian and Semaphorin1a during guidance and synapse formation.

PubMed

Godenschwege, Tanja A; Murphey, Rodney K

2009-01-01

We have previously demonstrated a function for Neuroglian and Semaphorin1a in Drosophila giant fiber circuit formation. Both molecules are required for guiding the giant fibers out of the brain and have distinct functions during giant synapse formation. In this study we characterized the effects of various combinations of Neuroglian and Semaphorin1a gain and loss of function backgrounds on giant fiber circuitry formation. We found that Neuroglian and Semaphorin1a genetically interact with each other during axon guidance as well as during synapse formation. Our experiments revealed that during pathfinding of the giant fibers out of the brain, Neuroglian function seems to be dependent on Semaphorin1a. In contrast, during giant fiber synapse formation we observed that Semaphorin1a signaling as a receptor can be altered by Neuroglian in the same cell. In summary, our findings suggest that Neuroglian and Semaphorin1a can regulate each other's function in cis and that the resultant signaling output is possibly different during guidance and synapse formation.

Use of electromyography to detect muscle exhaustion in finishing barrows fed ractopamine HCl.

PubMed

Noel, J A; Broxterman, R M; McCoy, G M; Craig, J C; Phelps, K J; Burnett, D D; Vaughn, M A; Barstow, T J; O'Quinn, T G; Woodworth, J C; DeRouchey, J M; Rozell, T G; Gonzalez, J M

2016-06-01

The objectives of this study were to determine the effects of dietary ractopamine HCl (RAC) on muscle fiber characteristics and electromyography (EMG) measures of finishing barrow exhaustion when barrows were subjected to increased levels of activity. Barrows ( = 34; 92 ± 2 kg initial BW) were assigned to 1 of 2 treatments: a conventional swine finishing diet containing 0 mg/kg ractopamine HCl (CON) or a diet formulated to meet the requirements of finishing barrows fed 10 mg/kg RAC (RAC+). After 32 d on feed, barrows were individually moved around a track at 0.79 m/s until subjectively exhausted. Wireless EMG sensors were affixed to the deltoideus (DT), triceps brachii lateral head (TLH), tensor fasciae latae (TFL), and semitendinosus (ST) muscles to measure median power frequency (MdPF) and root mean square (RMS) as indicators of action potential conduction velocity and muscle fiber recruitment, respectively. After harvest, samples of each muscle were collected for fiber type, succinate dehydrogenase (SDH), and capillary density analysis. Speed was not different ( = 0.82) between treatments, but RAC+ barrows reached subjective exhaustion earlier and covered less distance than CON barrows ( < 0.01). There were no treatment × muscle interactions or treatment effects for end-point MdPF values ( > 0.29). There was a treatment × muscle interaction ( = 0.04) for end-point RMS values. The RAC diet did not change end-point RMS values in the DT or TLH ( > 0.37); however, the diet tended to decrease and increase end-point RMS in the ST and TFL, respectively ( < 0.07). There were no treatment × muscle interactions for fiber type, SDH, or capillary density measures ( > 0.10). Muscles of RAC+ barrows tended to have less type I fibers and more capillaries per fiber ( < 0.07). Type I and IIA fibers of RAC+ barrows were larger ( < 0.07). Compared with all other muscles, the ST had more ( < 0.01) type IIB fibers and larger type I, IIA, and IIX fibers ( < 0.01). Type I, IIA, and IIX fibers of the ST also contained less SDH compared with the other muscles ( < 0.01). Barrows fed a RAC diet had increased time to subjective exhaustion due to loss of active muscle fibers in the ST, possibly due to fibers being larger and less oxidative in metabolism. Size increases in type I and IIA fibers with no change in oxidative capacity could also contribute to early exhaustion of RAC+ barrows. Overall, EMG technology can measure real-time muscle fiber loss to help explain subjective exhaustion in barrows.

Tapered fibers embedded in silica aerogel.

PubMed

Xiao, Limin; Grogan, Michael D W; Leon-Saval, Sergio G; Williams, Rhys; England, Richard; Wadsworth, Willam J; Birks, Tim A

2009-09-15

We have embedded thin tapered fibers (with diameters down to 1 microm) in silica aerogel with low loss. The aerogel is rigid but behaves refractively like air, protecting the taper without disturbing light propagation along it. This enables a new class of fiber devices exploiting volume evanescent interactions with the aerogel itself or with dopants or gases in the pores.

Reactive compatibilization in polymer alloys, recyclates and composites

NASA Astrophysics Data System (ADS)

Czvikovszky, T.; Hargitai, H.; Rácz, I.; Csukat, G.

1999-05-01

The efficiency of all composite materials depends on the fiber-matrix interface and its ability to transfer stress from the matrix to the fiber. Radiation treatment is a possible way to bind together the main components of the composite. In our earlier work we applied acrylic oligomer-treated fibers irradiated with low energy electron beam to reinforce recycled polypropylene. In the present work the interaction between the matrix and fibers - PAN and glass fibers - was investigated by ESCA (Electron Spectroscopy for Chemical Analysis). On the other hand, the conventional way of compatibilization - the effect of using maleic anhydride grafted PP as a coupling agent - was examined in flax fiber-PP composites.

Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2016-09-06

A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Fiber-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

DOEpatents

Janke, Christopher J; Dai, Sheng; Oyola, Yatsandra

2014-05-13

A fiber-based adsorbent and a related method of manufacture are provided. The fiber-based adsorbent includes polymer fibers with grafted side chains and an increased surface area per unit weight over known fibers to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. The polymer fibers include a circular morphology in some embodiments, having a mean diameter of less than 15 microns, optionally less than about 1 micron. In other embodiments, the polymer fibers include a non-circular morphology, optionally defining multiple gear-shaped, winged-shaped or lobe-shaped projections along the length of the polymer fibers. A method for forming the fiber-based adsorbents includes irradiating high surface area polymer fibers, grafting with polymerizable reactive monomers, reacting the grafted fibers with hydroxylamine, and conditioning with an alkaline solution. High surface area fiber-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

Interactions between Chloramphenicol, Carrier Polymers, and Bacteria-Implications for Designing Electrospun Drug Delivery Systems Countering Wound Infection.

PubMed

Preem, Liis; Mahmoudzadeh, Mohammad; Putrinš, Marta; Meos, Andres; Laidmäe, Ivo; Romann, Tavo; Aruväli, Jaan; Härmas, Riinu; Koivuniemi, Artturi; Bunker, Alex; Tenson, Tanel; Kogermann, Karin

2017-12-04

Antibacterial drug-loaded electrospun nano- and microfibrous dressings are of major interest as novel topical drug delivery systems in wound care. In this study, chloramphenicol (CAM)-loaded polycaprolactone (PCL) and PCL/poly(ethylene oxide) (PEO) fiber mats were electrospun and characterized in terms of morphology, drug distribution, physicochemical properties, drug release, swelling, cytotoxicity, and antibacterial activity. Computational modeling together with physicochemical analysis helped to elucidate possible interactions between the drug and carrier polymers. Strong interactions between PCL and CAM together with hydrophobicity of the system resulted in much slower drug release compared to the hydrophilic ternary system of PCL/PEO/CAM. Cytotoxicity studies confirmed safety of the fiber mats to murine NIH 3T3 cells. Disc diffusion assay demonstrated that both fast and slow release fiber mats reached effective concentrations and had similar antibacterial activity. A biofilm formation assay revealed that both blank matrices are good substrates for the bacterial attachment and formation of biofilm. Importantly, prolonged release of CAM from drug-loaded fibers helps to avoid biofilm formation onto the dressing and hence avoids the treatment failure.

Control over Structure and Function of Peptide Amphiphile Supramolecular Assemblies through Molecular Design and Energy Landscapes

NASA Astrophysics Data System (ADS)

Tantakitti, Faifan

Supramolecular chemistry is a powerful tool to create a material of a defined structure with tunable properties. This strategy has led to catalytically active, bioactive, and environment-responsive materials, among others, that are valuable in applications ranging from sensor technology to energy and medicine. Supramolecular polymers formed by peptide amphiphiles (PAs) have been especially relevant in tissue regeneration due to their ability to form biocompatible structures and mimic many important signaling molecules in biology. These supramolecular polymers can form nanofibers that create networks which mimic natural extracellular matrices. PA materials have been shown to induce growth of blood vessels, bone, cartilage, and nervous tissue, among others. The work described in this thesis not only studied the relationship between molecular structure and functions of PA assemblies, but also uncovered a powerful link between the energy landscape of their supramolecular self-assembly and the ability of PA materials to interact with cells. In chapter 2, it is argued that fabricating fibrous nanostructures with defined mechanical properties and decoration with bioactive molecules is not sufficient to create a material that can effectively communicate with cells. By systemically placing the fibronectin-derived RGDS epitope at increasing distances from the surface of PA nanofibers through a linker of one to five glycine residues, integrin-mediated RGDS signaling was enhanced. The results suggested that the spatial presentation of an epitope on PA nanofibers strongly influences the bioactivity of the PA substrates. In further improving functionality of a PA-based scaffold to effectively direct cell growth and differentiation, chapter 3 explored the use of a cell microcarrier to compartmentalize and simultaneously tune insoluble and soluble signals in a single matrix. PA nanofibers were incorporated at the surface of the microcarrier in order to promote cell adhesion, while a controlled local release of the soluble growth factor bone morphogenetic protein 4 (BMP-4) was realized from the particle's core composed of cross-linked alginate. The alginate-core and PA-shell microparticles were found to allow independent tuning of the bioactivity of a PA and a release of the growth factor for specific signaling to cells. Using microcarriers which encapsulated BMP-4 and coated with RGDS PA nanofibers, it was shown that a control over spatial distribution, proliferation, and osteogenic differentiation of premyoblastic cells on the surface of microcarriers can be effectively achieved. Finally, in drastic contrast to the traditional approach to material development based on altering molecular structure, chapter 4 presents the energy landscapes in which supramolecular assemblies of unique architecture exist in different thermodynamic wells. Experimental results and calculations revealed that the energy landscapes are rooted in competing interactions between PA monomers, namely beta-sheet hydrogen bonds and repulsion among charged groups. Switching off or on the repulsive electrostatic interactions by changing the ionic strength promoted or suppressed the dominant ?-sheet hydrogen bonding interactions respectively. However, the dominant forces can prevail if the assemblies are above a certain size and thereby can exist in a kinetically trapped state. Preparative pathways involving dilution, annealing, and addition of salt were investigated in which the structures belonging to different energy states could be accessed and demonstrated that these energy landscapes involving competitive interactions was applicable not only to PA systems but also to a non-peptide supramolecular system based on pi-orbital overlaps as the dominant attraction among molecules and electrostatic repulsion. In chapter 5, structure and biological function relationships of long or short PA nanofibers are reported, and such fibers were prepared from identical monomers based on knowledge of their energy landscapes described in chapter 4. Biological experiments were performed to compare the cytotoxicity of solutions containing short or long PA assemblies, as well as the ability of PA substrates to support cell adhesion and growth. In one assay, short fibers killed cells faster than long fibers and a study of interactions between lipid membrane and PA fibers suggested that cell death occurred through disruption of cell membrane by intact fibers, as opposed to single PA monomers. In another assay, long fibers induced better cell-spreading than short ones when immobilized on a surface. Mechanical measurements on the PA substrates indicated a higher ability of long fibers to sustain a higher pulling force exerted by cells. In summary, this thesis highlights that function in PA supramolecular materials is not only connected to chemical structure but also to the positions of specific materials within their respective energy landscapes.

Human adenovirus serotypes 3 and 5 bind to two different cellular receptors via the fiber head domain.

PubMed Central

Stevenson, S C; Rollence, M; White, B; Weaver, L; McClelland, A

1995-01-01

The adenovirus fiber protein is responsible for attachment of the virion to cell surface receptors. The identity of the cellular receptor which mediates binding is unknown, although there is evidence suggesting that two distinct adenovirus receptors interact with the group C (adenovirus type 5 [Ad5]) and the group B (Ad3) adenoviruses. In order to define the determinants of adenovirus receptor specificity, we have carried out a series of competition binding experiments using recombinant native fiber polypeptides from Ad5 and Ad3 and chimeric fiber proteins in which the head domains of Ad5 and Ad3 were exchanged. Specific binding of fiber to HeLa cell receptors was assessed with radiolabeled protein synthesized in vitro, and by competition analysis with baculovirus-expressed fiber protein. Fiber produced in vitro was found as both monomer and trimer, but only the assembled trimers had receptor binding activity. Competition data support the conclusion that Ad5 and Ad3 interact with different cellular receptors. The Ad5 receptor distribution on several cell lines was assessed with a fiber binding flow cytometric assay. HeLa cells were found to express high levels of receptor, while CHO and human diploid fibroblasts did not. A chimeric fiber containing the Ad5 fiber head domain blocked the binding of Ad5 fiber but not Ad3 fiber. Similarly, a chimeric fiber containing the Ad3 fiber head blocked the binding of labeled Ad3 fiber but not Ad5 fiber. In addition, the isolated Ad3 fiber head domain competed effectively with labeled Ad3 fiber for binding to HeLa cell receptors. These results demonstrate that the determinants of receptor binding are located in the head domain of the fiber and that the isolated head domain is capable of trimerization and binding to cellular receptors. Our results also show that it is possible to change the receptor specificity of the fiber protein by manipulation of sequences contained in the head domain. Modification or replacement of the fiber head domain with novel ligands may permit adenovirus vectors with new receptor specificities which could be useful for targeted gene delivery in vivo to be engineered. PMID:7707507

Microstructural characterization of PAN based carbon fiber reinforced nylon 6 polymer composites

NASA Astrophysics Data System (ADS)

Munirathnamma, L. M.; Ningaraju, S.; Kumar, K. V. Aneesh; Ravikumar, H. B.

2018-04-01

Microstructural characterization of nylon 6/polyacrolonitrile based carbon fibers (PAN-CFs) of 10 to 40 wt% has been performed by positron lifetime technique (PLT). The positron lifetime parameters viz., o-Ps lifetime (τ3), o-Ps intensity (I3) and fractional free volume (Fv) of nylon 6/PAN-CF composites are correlated with the mechanical properties viz., Tensile strength and Young's modulus. The Fv show negative deviation with the reinforcement of 10 to 40 wt% of PAN-CF from the linear additivity relation. The negative deviation in nylon 6/PAN-CF composite suggests the induced molecular packing due to the chemical interaction between the polymeric chains of nylon 6 and PAN-CF. This is evident from Fourier Transform Infrared Spectrometry (FTIR) studies. The FTIR results suggests that observed negative deviation in PALS results of nylon 6/PAN-CF reinforced polymer composites is due to the induced chemical interaction at N-H-O sites. The improved tensile strength (TS) and Young's modulus (YM) in nylon 6/PAN-CF reinforced polymer composites is due to AS4C (surface treated and epoxy coated) PAN-CF has shown highest adhesion level due to better stress transfer between nylon 6 and PAN-CF.

Dietary fiber, kidney function, inflammation, and mortality risk.

PubMed

Xu, Hong; Huang, Xiaoyan; Risérus, Ulf; Krishnamurthy, Vidya M; Cederholm, Tommy; Arnlöv, Johan; Lindholm, Bengt; Sjögren, Per; Carrero, Juan Jesús

2014-12-05

In the United States population, high dietary fiber intake has been associated with a lower risk of inflammation and mortality in individuals with kidney dysfunction. This study aimed to expand such findings to a Northern European population. Dietary fiber intake was calculated from 7-day dietary records in 1110 participants aged 70-71 years from the Uppsala Longitudinal Study of Adult Men (examinations performed during 1991-1995). Dietary fiber was adjusted for total energy intake by the residual method. Renal function was estimated from the concentration of serum cystatin C, and deaths were registered prospectively during a median follow-up of 10.0 years. Dietary fiber independently and directly associated with eGFR (adjusted difference, 2.6 ml/min per 1.73 m(2) per 10 g/d higher; 95% confidence interval [95% CI], 0.3 to 4.9). The odds of C-reactive protein >3 mg/L were lower (linear trend, P=0.002) with higher fiber quartiles. During follow-up, 300 participants died (incidence rate of 2.87 per 100 person-years at risk). Multiplicative interactions were observed between dietary fiber intake and kidney dysfunction in the prediction of mortality. Higher dietary fiber was associated with lower mortality in unadjusted analysis. These associations were stronger in participants with kidney dysfunction (eGFR<60 ml/min per 1.73 m(2)) (hazard ratio [HR], 0.58; 95% CI, 0.35 to 0.98) than in those without (HR, 1.30; 95% CI, 0.76 to 2.22; P value for interaction, P=0.04), and were mainly explained by a lower incidence of cancer-related deaths (0.25; 95% CI, 0.10 to 0.65) in individuals with kidney dysfunction versus individuals with an eGFR≥60 ml/min per 1.73 m(2) (1.61; 95% CI, 0.69 to 3.74; P value for interaction, P=0.01). High dietary fiber was associated with better kidney function and lower inflammation in community-dwelling elderly men from Sweden. High dietary fiber was also associated with lower (cancer) mortality risk, especially in individuals with kidney dysfunction. Copyright © 2014 by the American Society of Nephrology.

Dietary Fiber, Kidney Function, Inflammation, and Mortality Risk

PubMed Central

Xu, Hong; Huang, Xiaoyan; Risérus, Ulf; Krishnamurthy, Vidya M.; Cederholm, Tommy; Ärnlöv, Johan; Lindholm, Bengt; Sjögren, Per

2014-01-01

Background and objectives In the United States population, high dietary fiber intake has been associated with a lower risk of inflammation and mortality in individuals with kidney dysfunction. This study aimed to expand such findings to a Northern European population. Design, setting, participants, & measurements Dietary fiber intake was calculated from 7-day dietary records in 1110 participants aged 70–71 years from the Uppsala Longitudinal Study of Adult Men (examinations performed during 1991–1995). Dietary fiber was adjusted for total energy intake by the residual method. Renal function was estimated from the concentration of serum cystatin C, and deaths were registered prospectively during a median follow-up of 10.0 years. Results Dietary fiber independently and directly associated with eGFR (adjusted difference, 2.6 ml/min per 1.73 m2 per 10 g/d higher; 95% confidence interval [95% CI], 0.3 to 4.9). The odds of C-reactive protein >3 mg/L were lower (linear trend, P=0.002) with higher fiber quartiles. During follow-up, 300 participants died (incidence rate of 2.87 per 100 person-years at risk). Multiplicative interactions were observed between dietary fiber intake and kidney dysfunction in the prediction of mortality. Higher dietary fiber was associated with lower mortality in unadjusted analysis. These associations were stronger in participants with kidney dysfunction (eGFR<60 ml/min per 1.73 m2) (hazard ratio [HR], 0.58; 95% CI, 0.35 to 0.98) than in those without (HR, 1.30; 95% CI, 0.76 to 2.22; P value for interaction, P=0.04), and were mainly explained by a lower incidence of cancer-related deaths (0.25; 95% CI, 0.10 to 0.65) in individuals with kidney dysfunction versus individuals with an eGFR≥60 ml/min per 1.73 m2 (1.61; 95% CI, 0.69 to 3.74; P value for interaction, P=0.01). Conclusions High dietary fiber was associated with better kidney function and lower inflammation in community-dwelling elderly men from Sweden. High dietary fiber was also associated with lower (cancer) mortality risk, especially in individuals with kidney dysfunction. PMID:25280496

Observations and analysis activities of the International Ultraviolet Explorer satellite telescope

NASA Technical Reports Server (NTRS)

Shull, J. Michael

1996-01-01

The funds from this grant were used to support observations and analysis with the International Ultraviolet Explorer (IUE) satellite telescope. The main area of scientific research concerned the variability analyses of ultraviolet spectra of Active Galactic Nuclei, primarily quasars, Seyfert galaxies, and BL Lacertae objects. The Colorado group included, at various times, the P.I. (J.M. Shull), Research Associate Dr. Rick Edelson, and graduate students Jon Saken, Elise Sachs, and Steve Penton. A portion of the work was also performed by CU undergraduate student Cheong-ming Fu. A major product of the effort was a database of all IUE spectra of active galactic nuclei. This database is being analyzed to obtain spectral indices, line fluxes, and continuum fluxes for over 500 AGN. As a by-product of this project, we implemented a new, improved technique of spectral extraction of IUE spectra, which has been used in several AGN-WATCH campaigns (on the Seyfert galaxy NGC 4151 and on the BL Lac object PKS 2155-304).

Modification of the Interfacial Interaction between Carbon Fiber and Epoxy with Carbon Hybrid Materials

PubMed Central

Yu, Kejing; Wang, Menglei; Wu, Junqing; Qian, Kun; Sun, Jie; Lu, Xuefeng

2016-01-01

The mechanical properties of the hybrid materials and epoxy and carbon fiber (CF) composites were improved significantly as compared to the CF composites made from unmodified epoxy. The reasons could be attributed to the strong interfacial interaction between the CF and the epoxy composites for the existence of carbon nanomaterials. The microstructure and dispersion of carbon nanomaterials were characterized by transmission electron microscopy (TEM) and optical microscopy (OM). The results showed that the dispersion of the hybrid materials in the polymer was superior to other carbon nanomaterials. The high viscosity and shear stress characterized by a rheometer and the high interfacial friction and damping behavior characterized by dynamic mechanical analysis (DMA) indicated that the strong interfacial interaction was greatly improved between fibers and epoxy composites. Remarkably, the tensile tests presented that the CF composites with hybrid materials and epoxy composites have a better reinforcing and toughening effect on CF, which further verified the strong interfacial interaction between epoxy and CF for special structural hybrid materials. PMID:28335217

Silk/nano-material hybrid: properties and functions

NASA Astrophysics Data System (ADS)

Steven, Eden; Lebedev, Victor; Laukhina, Elena; Laukhin, Vladimir; Alamo, Rufina G.; Rovira, Concepcio; Veciana, Jaume; Brooks, James S.

2014-03-01

Silk continues to emerge as a material of interest in electronics. In this work, the interaction between silk and conducting nano-materials are investigated. Simple fabrication methods, physical, electronic, thermal, and actuation properties are reported for spider silk / carbon nanotube (CNT-SS) and Bombyx mori / (BEDT-TTF)-based organic molecular conductor hybrids (ET-S). The CNT-SS fibers are produced via water and shear assisted method, resulting in fibers that are tough, custom-shapeable, flexible, and electrically conducting. For ET-S bilayer films, a layer transfer technique is developed to deposit linked crystallites of (BEDT-TTF)2I3 molecular conductor onto silk films, generating highly piezoresistive semi-transparent films. In both cases, the hybridization allows us to gain additional functions by harnessing the water-dependent properties of silk materials, for example, as humidity sensor and electrical current- or water-driven actuators. SEM, TEM, FT-IR, and resistance measurements under varying temperature, strain, and relative humidity reveal the synergistic interactions between the bio- and nano-materials. E.S. is supported by NSF-DMR 1005293.

A mock heart engineered with helical aramid fibers for in vitro cardiovascular device testing.

PubMed

Jansen-Park, So-Hyun; Hsu, Po-Lin; Müller, Indra; Steinseifer, Ulrich; Abel, Dirk; Autschbach, Rüdiger; Rossaint, Rolf; Schmitz-Rode, Thomas

2017-04-01

Mock heart circulation loops (MHCLs) serve as in-vitro platforms to investigate the physiological interaction between circulatory systems and cardiovascular devices. A mock heart (MH) engineered with silicone walls and helical aramid fibers, to mimic the complex contraction of a natural heart, has been developed to advance the MHCL previously developed in our group. A mock aorta with an anatomical shape enables the evaluation of a cannulation method for ventricular assist devices (VADs) and investigation of the usage of clinical measurement systems like pressure-volume catheters. Ventricle and aorta molds were produced based on MRI data and cast with silicone. Aramid fibers were layered in the silicone ventricle to reproduce ventricle torsion. A rotating hollow shaft was connected to the apex enabling the rotation of the MH and the connection of a VAD. Silicone wall thickness, aramid fiber angle and fiber pitch were varied to generate different MH models. All MH models were placed in a tank filled with variable amounts of water and air simulating the compliance. In this work, physiological ventricular torsion angles (15°-26°) and physiological pressure-volume loops were achieved. This MHCL can serve as a comprehensive testing platform for cardiovascular devices, such as artificial heart valves and cannulation of VADs.

Effect of Simultaneous Water Deficit Stress and Meloidogyne incognita Infection on Cotton Yield and Fiber Quality

PubMed Central

Davis, R. F.; Earl, H. J.; Timper, P.

2014-01-01

Both water deficit stress and Meloidogyne incognita infection can reduce cotton growth and yield, and drought can affect fiber quality, but the effect of nematodes on fiber quality is not well documented. To determine whether nematode parasitism affects fiber quality and whether the combined effects of nematode and drought stress on yield and quality are additive (independent effects), synergistic, or antagonistic, we conducted a study for 7 yr in a field infested with M. incognita. A split-plot design was used with the main plot factor as one of three irrigation treatments (low [nonirrigated], moderate irrigation, and high irrigation [water-replete]) and the subplot factor as 0 or 56 l/ha 1,3-dichloropropene. We prevented water deficit stress in plots designated as water-replete by supplementing rainfall with irrigation. Plots receiving moderate irrigation received half the water applied to the water-replete treatment. The severity of root galling was greater in nonfumigated plots and in plots receiving the least irrigation, but the amount of irrigation did not influence the effect of fumigation on root galling (no irrigation × fumigation interaction). The weights of lint and seed harvested were reduced in nonfumigated plots and also decreased as the level of irrigation decreased, but fumigation did not influence the effect of irrigation. Nematodes affected fiber quality by increasing micronaire readings but typically had little or no effect on percent lint, fiber length (measured by HVI), uniformity, strength, elongation, length (based on weight or number measured by AFIS), upper quartile length, or short fiber content (based on weight or number). Micronaire also was increased by water deficit stress, but the effects from nematodes and water stress were independent. We conclude that the detrimental effects caused to cotton yield and quality by nematode parasitism and water deficit stress are independent and therefore additive. PMID:24987162

Effect of lightning strike on bromine intercalated graphite fiber/epoxy composites

NASA Technical Reports Server (NTRS)

Gaier, James R.; Slabe, Melissa E.; Brink, Norman O.

1991-01-01

Laminar composites were fabricated from pristine and bromine intercalated pitch based graphite fibers. It was found that laminar composites could be fabricated using either pristine or intercalated graphite fibers using standard fabrication techniques. The intercalated graphite fiber composites had electrical properties which were markedly improved over both the corresponding pitch based and polyacrylonitrile (PAN) based composites. Despite composites resistivities more than an order of magnitude lower for pitch based fiber composites, the lightning strike resistance was poorer than that of the Pan based fiber composites. This leads to the conclusion that the mechanical properties of the pitch fibers are more important than electrical or thermal properties in determining the lightning strike resistance. Based on indicated lightning strike tolerance for high elongation to failure materials, the use of vapor grown, rather than pitch based graphite fibers appears promising.

Role of Fiber Length on Phagocytosis & Inflammatory Response

NASA Astrophysics Data System (ADS)

Turkevich, Leonid; Stark, Carahline; Champion, Julie

2014-03-01

Asbestos fibers have long been associated with lung cancer death. The inability of immune cells (e.g. macrophages) to effectively remove asbestos leads to chronic inflammation and disease. This study examines the role of fiber length on toxicity at the cellular level using model glass fibers. A major challenge is obtaining single diameter fibers but differing in length. Samples of 1 micron diameter fibers with different length distributions were prepared: short fibers (less than 15 microns) by aggressive crushing, and long fibers (longer than 15 microns) by successive sedimentation. Time-lapse video microscopy monitored the interaction of MH-S murine alveolar macrophages with the fibers: short fibers were easily internalized by the macrophages, but long fibers resisted internalization over many hours. Production of TNF- α (tumor necrosis factor alpha), a general inflammatory secreted cytokine, and Cox-2 (cyclo-oxygenase-2), an enzyme that produces radicals, each exhibited a dose-dependence that was greater for long than for short fibers. These results corroborate the importance of fiber length in both physical and biochemical cell response and support epidemiological observations of higher toxicity for longer fibers.

Computational modeling of high performance steel fiber reinforced concrete using a micromorphic approach

NASA Astrophysics Data System (ADS)

Huespe, A. E.; Oliver, J.; Mora, D. F.

2013-12-01

A finite element methodology for simulating the failure of high performance fiber reinforced concrete composites (HPFRC), with arbitrarily oriented short fibers, is presented. The composite material model is based on a micromorphic approach. Using the framework provided by this theory, the body configuration space is described through two kinematical descriptors. At the structural level, the displacement field represents the standard kinematical descriptor. Additionally, a morphological kinematical descriptor, the micromorphic field, is introduced. It describes the fiber-matrix relative displacement, or slipping mechanism of the bond, observed at the mesoscale level. In the first part of this paper, we summarize the model formulation of the micromorphic approach presented in a previous work by the authors. In the second part, and as the main contribution of the paper, we address specific issues related to the numerical aspects involved in the computational implementation of the model. The developed numerical procedure is based on a mixed finite element technique. The number of dofs per node changes according with the number of fiber bundles simulated in the composite. Then, a specific solution scheme is proposed to solve the variable number of unknowns in the discrete model. The HPFRC composite model takes into account the important effects produced by concrete fracture. A procedure for simulating quasi-brittle fracture is introduced into the model and is described in the paper. The present numerical methodology is assessed by simulating a selected set of experimental tests which proves its viability and accuracy to capture a number of mechanical phenomenon interacting at the macro- and mesoscale and leading to failure of HPFRC composites.

Analysis of differential gene expression by bead-based fiber-optic array in growth-hormone-secreting pituitary adenomas.

PubMed

Jiang, Zhiquan; Gui, Songbo; Zhang, Yazhuo

2010-09-01

Growth-hormone-secreting pituitary adenomas (GHomas) account for approximately 20% of all pituitary neoplasms. However, the pathogenesis of GHomas remains to be elucidated. To explore the possible pathogenesis of GHomas, we used bead-based fiber-optic arrays to examine the gene expression in five GHomas and compared them to three healthy pituitaries. Four differentially expressed genes were chosen randomly for validation by quantitative real-time reverse transcription-polymerase chain reaction. We then performed pathway analysis on the identified differentially expressed genes using the Kyoto Encyclopedia of Genes and Genomes. Array analysis showed significant increases in the expression of 353 genes and 206 expressed sequence tags (ESTs) and decreases in 565 genes and 29 ESTs. Bioinformatic analysis showed that the genes HIGD1B, HOXB2, ANGPT2, HPGD and BTG2 may play an important role in the tumorigenesis and progression of GHomas. Pathway analysis showed that the wingless-type signaling pathway and extracellular-matrix receptor interactions may play a key role in the tumorigenesis and progression of GHomas. Our data suggested that there are numerous aberrantly expressed genes and pathways involved in the pathogenesis of GHomas. Bead-based fiber-optic arrays combined with pathway analysis of differentially expressed genes appear to be a valid method for investigating the pathogenesis of tumors.

Analysis of differential gene expression by bead-based fiber-optic array in growth-hormone-secreting pituitary adenomas

PubMed Central

JIANG, ZHIQUAN; GUI, SONGBO; ZHANG, YAZHUO

2010-01-01

Growth-hormone-secreting pituitary adenomas (GHomas) account for approximately 20% of all pituitary neoplasms. However, the pathogenesis of GHomas remains to be elucidated. To explore the possible pathogenesis of GHomas, we used bead-based fiber-optic arrays to examine the gene expression in five GHomas and compared them to three healthy pituitaries. Four differentially expressed genes were chosen randomly for validation by quantitative real-time reverse transcription-polymerase chain reaction. We then performed pathway analysis on the identified differentially expressed genes using the Kyoto Encyclopedia of Genes and Genomes. Array analysis showed significant increases in the expression of 353 genes and 206 expressed sequence tags (ESTs) and decreases in 565 genes and 29 ESTs. Bioinformatic analysis showed that the genes HIGD1B, HOXB2, ANGPT2, HPGD and BTG2 may play an important role in the tumorigenesis and progression of GHomas. Pathway analysis showed that the wingless-type signaling pathway and extracellular-matrix receptor interactions may play a key role in the tumorigenesis and progression of GHomas. Our data suggested that there are numerous aberrantly expressed genes and pathways involved in the pathogenesis of GHomas. Bead-based fiber-optic arrays combined with pathway analysis of differentially expressed genes appear to be a valid method for investigating the pathogenesis of tumors. PMID:22993617

A 2D modeling approach for fluid propagation during FE-forming simulation of continuously reinforced composites in wet compression moulding

NASA Astrophysics Data System (ADS)

Poppe, Christian; Dörr, Dominik; Henning, Frank; Kärger, Luise

2018-05-01

Wet compression moulding (WCM) provides large-scale production potential for continuously fiber reinforced components as a promising alternative to resin transfer moulding (RTM). Lower cycle times are possible due to parallelization of the process steps draping, infiltration and curing during moulding (viscous draping). Experimental and theoretical investigations indicate a strong mutual dependency between the physical mechanisms, which occur during draping and mould filling (fluid-structure-interaction). Thus, key process parameters, like fiber orientation, fiber volume fraction, cavity pressure and the amount and viscosity of the resin are physically coupled. To enable time and cost efficient product and process development throughout all design stages, accurate process simulation tools are desirable. Separated draping and mould filling simulation models, as appropriate for the sequential RTM-process, cannot be applied for the WCM process due to the above outlined physical couplings. Within this study, a two-dimensional Darcy-Propagation-Element (DPE-2D) based on a finite element formulation with additional control volumes (FE/CV) is presented, verified and applied to forming simulation of a generic geometry, as a first step towards a fluid-structure-interaction model taking into account simultaneous resin infiltration and draping. The model is implemented in the commercial FE-Solver Abaqus by means of several user subroutines considering simultaneous draping and 2D-infiltration mechanisms. Darcy's equation is solved with respect to a local fiber orientation. Furthermore, the material model can access the local fluid domain properties to update the mechanical forming material parameter, which enables further investigations on the coupled physical mechanisms.

Electrospun PVA/HAp nanocomposite nanofibers: biomimetics of mineralized hard tissues at a lower level of complexity.

PubMed

Kim, Gyeong-Man; Asran, Ashraf Sh; Michler, Georg H; Simon, Paul; Kim, Jeong-Sook

2008-12-01

Based on the biomimetic approaches the present work describes a straightforward technique to mimic not only the architecture (the morphology) but also the chemistry (the composition) of the lowest level of the hierarchical organization of bone. This technique uses an electrospinning (ES) process with polyvinyl alcohol (PVA) and hydroxyapatite (HAp) nanoparticles. To determine morphology, crystalline structures and thermal properties of the resulting electrospun fibers with the pure PVA and PVA/HAp nanocomposite (NC) before electrospinning various techniques were employed, including transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, FT-IR spectroscopy was carried out to analyze the complex structural changes upon undergoing electrospinning as well as interactions between HAp and PVA. The morphological and crystallographic investigations revealed that the rod-like HAp nanoparticles exhibit a nanoporous morphology and are embedded within the electrospun fibers. A large number of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers, which closely resemble the naturally mineralized hard tissues of bones. Due to abundant OH groups present in PVA and HAp nanorods, they strongly interact via hydrogen bonding within the electrospun PVA/HAp NC fibers, which results in improved thermal properties. The unique physiochemical features of the electrospun PVA/HAp NC nanofibers prepared by the ES process will open up a wide variety of future applications related to hard tissue replacement and regeneration (bone and dentin), not limited to coating implants.

High-power graphene mode-locked Tm/Ho co-doped fiber laser with evanescent field interaction

PubMed Central

Li, Xiaohui; Yu, Xuechao; Sun, Zhipei; Yan, Zhiyu; Sun, Biao; Cheng, Yuanbing; Yu, Xia; Zhang, Ying; Wang, Qi Jie

2015-01-01

Mid-infrared ultrafast fiber lasers are valuable for various applications, including chemical and biomedical sensing, material processing and military applications. Here, we report all-fiber high-power graphene mode-locked Tm/Ho co-doped fiber laser at long wavelength with evanescent field interaction. Ultrafast pulses up to 7.8 MHz are generated at a center wavelength of 1879.4 nm, with a pulse width of 4.7 ps. A graphene absorber integrated with a side-polished fiber can increase the damage threshold significantly. Harmonics mode-locking can be obtained till to the 21th harmonics at a pump power of above 500 mW. By using one stage amplifier in the anomalous dispersion regime, the laser can be amplified up to 450 mW and the narrowest pulse duration of 1.4 ps can be obtained simultaneously. Our work paves the way to graphene Tm/Ho co-doped mode-locked all-fiber master oscillator power amplifiers as potentially efficient and economic laser sources for high-power laser applications, such as special material processing and nonlinear optical studies. PMID:26567536

Accurate mode characterization of two-mode optical fibers by in-fiber acousto-optics.

PubMed

Alcusa-Sáez, E; Díez, A; Andrés, M V

2016-03-07

Acousto-optic interaction in optical fibers is exploited for the accurate and broadband characterization of two-mode optical fibers. Coupling between LP 01 and LP 1m modes is produced in a broadband wavelength range. Difference in effective indices, group indices, and chromatic dispersions between the guided modes, are obtained from experimental measurements. Additionally, we show that the technique is suitable to investigate the fine modes structure of LP modes, and some other intriguing features related with modes' cut-off.

Mechanical properties of reinforced denture base resin: the effect of position and the number of woven glass fibers.

PubMed

Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

2002-09-01

This study examined the effects of the position and the number of woven glass fibers on the flexural strength, flexural modulus, and toughness of reinforced denture base resin. The woven glass fiber consisted of 1-4 laminated sheets. Chemical curing was used to polymerize three types of 4-mm-thick test specimens: fibers in compresrion, fibers in the center, and fibers in tension. Unreinforced specimens were produced as controls. A three-point flexural test was performed and the woven glass fiber content was calculated after the woven glass fiber was fired. The best results were obtained when the woven glass fiber was incorporated outside the base resin under tension, thereby increasing the flexural strength and flexural modulus. Furthermore, the denture base resin reinforced with woven glass fiber was made tougher by increasing the number of woven glass fibers incorporated into the portion under tension.

Characterization of the stress and refractive-index distributions in optical fibers and fiber-based devices

NASA Astrophysics Data System (ADS)

Hutsel, Michael R.

2011-07-01

Optical fiber technology continues to advance rapidly as a result of the increasing demands on communication systems and the expanding use of fiber-based sensing. New optical fiber types and fiber-based communications components are required to permit higher data rates, an increased number of channels, and more flexible installation requirements. Fiber-based sensors are continually being developed for a broad range of sensing applications, including environmental, medical, structural, industrial, and military. As optical fibers and fiber-based devices continue to advance, the need to understand their fundamental physical properties increases. The residual-stress distribution (RSD) and the refractive-index distribution (RID) play fundamental roles in the operation and performance of optical fibers. Custom RIDs are used to tailor the transmission properties of fibers used for long-distance transmission and to enable fiber-based devices such as long-period fiber gratings (LPFGs). The introduction and modification of RSDs enable specialty fibers, such as polarization-maintaining fiber, and contribute to the operation of fiber-based devices. Furthermore, the RSD and the RID are inherently linked through the photoelastic effect. Therefore, both the RSD and the RID need to be characterized because these fundamental properties are coupled and affect the fabrication, operation, and performance of fibers and fiber-based devices. To characterize effectively the physical properties of optical fibers, the RSD and the RID must be measured without perturbing or destroying the optical fiber. Furthermore, the techniques used must not be limited in detecting small variations and asymmetries in all directions through the fiber. Finally, the RSD and the RID must be characterized concurrently without moving the fiber to enable the analysis of the relationship between the RSD and the RID. Although many techniques exist for characterizing the residual stress and the refractive index in optical fibers, there is no existing methodology that meets all of these requirements. Therefore, the primary objective of the research presented in this thesis was to provide a methodology that is capable of characterizing concurrently the three-dimensional RSD and RID in optical fibers and fiber-based devices. This research represents a detailed study of the requirements for characterizing optical fibers and how these requirements are met through appropriate data analysis and experimental apparatus design and implementation. To validate the developed methodology, the secondary objective of this research was to characterize both unperturbed and modified optical fibers. The RSD and the RID were measured in a standard telecommunications-grade optical fiber, Corning SMF-28. The effects of cleaving this fiber were also analyzed and the longitudinal variations that result from cleaving were explored for the first time. The fabrication of carbon-dioxide-laser-induced (CO2 -laser-induced) LPFGs was also examined. These devices provide many of the functionalities required for fiber-based communications components as well as fiber-based sensors, and they offer relaxed fabrication requirements when compared to LPFGs fabricated by other methods. The developed methodology was used to perform the first measurements of the changes that occur in the RSD and the RID during LPFG fabrication. The analysis of these measurements ties together many of the existing theories of CO2-laser-induced LPFG fabrication to present a more coherent understanding of the processes that occur. In addition, new evidence provides detailed information on the functional form of the RSD and the RID in LPFGs. This information is crucial for the modeling of LPFG behavior, for the design of LPFGs for specific applications, for the tailoring of fabrication parameters to meet design requirements, and for understanding the limitations of LPFG fabrication in commercial optical fibers. Future areas of research concerning the improvement of the developed methodology, the need to characterize other fibers and fiber-based devices, and the characterization of CO2-laser-induced LPFGs are identified and discussed.

Rac1 GTPase -deficient mouse lens exhibits defects in shape, suture formation, fiber cell migration and survival

PubMed Central

Maddala, Rupalatha; Chauhan, Bharesh K.; Walker, Christopher; Zheng, Yi; Robinson, Michael L.; Lang, Richard A.; Rao, Ponugoti V.

2011-01-01

Morphogenesis and shape of the ocular lens depend on epithelial cell elongation and differentiation into fiber cells, followed by the symmetric and compact organization of fiber cells within an enclosed extracellular matrix-enriched elastic capsule. The cellular mechanisms orchestrating these different events however, remain obscure. We investigated the role of the Rac1 GTPase in these processes by targeted deletion of expression using the conditional gene knockout (cKO) approach. Rac1 cKO mice were derived from two different Cre (Le-Cre and MLR-10) transgenic mice in which lens-specific Cre expression starts at embryonic day 8.75 and 10.5, respectively, in both the lens epithelium and fiber cells. The Le-Cre/Rac1 cKO mice exhibited an early-onset (E12.5) and severe lens phenotype compared to the MLR-10/Rac1 cKO (E15.5) mice. While the Le-Cre/Rac1 cKO lenses displayed delayed primary fiber cell elongation, lenses from both Rac1 cKO strains were characterized by abnormal shape, impaired secondary fiber cell migration, sutural defects and thinning of the posterior capsule which often led to rupture. Lens fiber cell N-cadherin/β-catenin/Rap1/Nectin-based cell-cell junction formation and WAVE-2/Abi-2/Nap1-regulated actin polymerization were impaired in the Rac1 deficient mice. Additionally, the Rac1 cKO lenses were characterized by a shortened epithelial sheet, reduced levels of extracellular matrix (ECM) proteins and increased apoptosis. Taken together, these data uncover the essential role of Rac1 GTPase activity in establishment and maintenance of lens shape, suture formation and capsule integrity, and in fiber cell migration, adhesion and survival, via regulation of actin cytoskeletal dynamics, cell adhesive interactions and ECM turnover. PMID:21945075

Physical and mechanical properties of PMMA bone cement reinforced with nano-sized titania fibers.

PubMed

Khaled, S M Z; Charpentier, Paul A; Rizkalla, Amin S

2011-02-01

X-ray contrast medium (BaSO(4) or ZrO(2)) used in commercially available PMMA bone cements imparts a detrimental effect on mechanical properties, particularly on flexural strength and fracture toughness. These lower properties facilitate the chance of implant loosening resulting from cement mantle failure. The present study was performed to examine the mechanical properties of a commercially available cement (CMW1) by introducing novel nanostructured titania fibers (n-TiO(2) fibers) into the cement matrix, with the fibers acting as a reinforcing phase. The hydrophilic nature of the n-TiO(2) fibers was modified by using a bifunctional monomer, methacrylic acid. The n-TiO(2) fiber content of the cement was varied from 0 to 2 wt%. Along with the mechanical properties (fracture toughness (K (IC)), flexural strength (FS), and flexural modulus (FM)) of the reinforced cements the following properties were investigated: complex viscosity-versus-time, maximum polymerization temperature (T (max)), dough time (t (dough)), setting time (t (set)), radiopacity, and in vitro biocompatibility. On the basis of the determined mechanical properties, the optimized composition was found at 1 wt% n-TiO(2) fibers, which provided a significant increase in K (IC) (63%), FS (20%), and FM (22%), while retaining the handling properties and in vitro biocompatibility compared to that exhibited by the control cement (CMW1). Moreover, compared to the control cement, there was no significant change in the radiopacity of any of the reinforced cements at p = 0.05. This study demonstrated a novel pathway to augment the mechanical properties of PMMA-based cement by providing an enhanced interfacial interaction and strong adhesion between the functionalized n-TiO( 2) fibers and PMMA matrix, which enhanced the effective load transfer within the cement.

Stress and strain provide positional and directional cues in development.

PubMed

Bozorg, Behruz; Krupinski, Pawel; Jönsson, Henrik

2014-01-01

The morphogenesis of organs necessarily involves mechanical interactions and changes in mechanical properties of a tissue. A long standing question is how such changes are directed on a cellular scale while being coordinated at a tissular scale. Growing evidence suggests that mechanical cues are participating in the control of growth and morphogenesis during development. We introduce a mechanical model that represents the deposition of cellulose fibers in primary plant walls. In the model both the degree of material anisotropy and the anisotropy direction are regulated by stress anisotropy. We show that the finite element shell model and the simpler triangular biquadratic springs approach provide equally adequate descriptions of cell mechanics in tissue pressure simulations of the epidermis. In a growing organ, where circumferentially organized fibers act as a main controller of longitudinal growth, we show that the fiber direction can be correlated with both the maximal stress direction and the direction orthogonal to the maximal strain direction. However, when dynamic updates of the fiber direction are introduced, the mechanical stress provides a robust directional cue for the circumferential organization of the fibers, whereas the orthogonal to maximal strain model leads to an unstable situation where the fibers reorient longitudinally. Our investigation of the more complex shape and growth patterns in the shoot apical meristem where new organs are initiated shows that a stress based feedback on fiber directions is capable of reproducing the main features of in vivo cellulose fiber directions, deformations and material properties in different regions of the shoot. In particular, we show that this purely mechanical model can create radially distinct regions such that cells expand slowly and isotropically in the central zone while cells at the periphery expand more quickly and in the radial direction, which is a well established growth pattern in the meristem.

Buckling Modes of Structural Elements of Off-Axis Fiber-Reinforced Plastics

NASA Astrophysics Data System (ADS)

Paimushin, V. N.; Polyakova, N. V.; Kholmogorov, S. A.; Shishov, M. A.

2018-05-01

The structures of two types of unidirectional fiber-reinforced composites — with an ELUR-P carbon fiber tape, an XT-118 cold-cure binder with an HSE 180 REM prepreg, and a hot-cure binder — were investigated. The diameters of fibers and fiber bundles (threads) of both the types of composites were measured, and their mutual arrangement was examined both in the semifinished products (in the uncured state) and in the finished composites. The defects characteristic of both the types of binder and manufacturing technique were detected in the cured composites. Based on an analysis of the results obtained, linearized problems on the internal multiscale buckling modes of an individual fiber (with and without account of its interaction with the surrounding matrix) or of a fiber bundle are formulated. In the initial atate, these structural elements of the fibrous composites are in a subcritical (unperturbed) state under the action of shear stresses and tension (compression) in the transverse direction. Such an initial stress state is formed in them in tension and compression tests on flat specimens made of off-axis-reinforced composites with straight fibers. To formulate the problems, the equations derived earlier from a consistent variant of geometrically nonlinear equations of elasticity theory by reducing them to the one-dimensional equations of the theory of straight rods on the basis of a refined Timoshenko shear model with account of tensile-compressive strains in the transverse direction are used. It is shown that, in loading test specimens, a continuous rearrangement of composite structure can occur due to the realization and continuous change of internal buckling modes as the wave-formation parameter varies continuously, which apparently explain the decrease revealed in the tangential shear modulus of the fibrous composites with increasing shear strains.

Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

NASA Astrophysics Data System (ADS)

Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

2018-06-01

A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

NASA Astrophysics Data System (ADS)

Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

2018-03-01

A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

Penny-shaped crack in a fiber-reinforced matrix. [elastostatics

NASA Technical Reports Server (NTRS)

Narayanan, T. V.; Erdogan, F.

1974-01-01

Using a slender inclusion model developed earlier, the elastostatic interaction problem between a penny-shaped crack and elastic fibers in an elastic matrix is formulated. For a single set and for multiple sets of fibers oriented perpendicularly to the plane of the crack and distributed symmetrically on concentric circles, the problem was reduced to a system of singular integral equations. Techniques for the regularization and for the numerical solution of the system are outlined. For various fiber geometries numerical examples are given, and distribution of the stress intensity factor along the crack border was obtained. Sample results showing the distribution of the fiber stress and a measure of the fiber-matrix interface shear are also included.

Penny-shaped crack in a fiber-reinforced matrix

NASA Technical Reports Server (NTRS)

Narayanan, T. V.; Erdogan, F.

1975-01-01

Using the slender inclusion model developed earlier the elastostatic interaction problem between a penny-shaped crack and elastic fibers in an elastic matrix is formulated. For a single set and for multiple sets of fibers oriented perpendicularly to the plane of the crack and distributed symmetrically on concentric circles the problem is reduced to a system of singular integral equations. Techniques for the regularization and for the numerical solution of the system are outlined. For various fiber geometries numerical examples are given and distribution of the stress intensity factor along the crack border is obtained. Sample results showing the distribution of the fiber stress and a measure of the fiber-matrix interface shear are also included.

Electric papers of graphene-coated Co₃O₄ fibers for high-performance lithium-ion batteries.

PubMed

Yang, Xiaoling; Fan, Kaicai; Zhu, Yihua; Shen, Jianhua; Jiang, Xin; Zhao, Peng; Luan, Shaorong; Li, Chunzhong

2013-02-01

A facile strategy to synthesize the novel composite paper of graphene nanosheets (GNS) coated Co(3)O(4) fibers is reported as an advanced anode material for high-performance lithium-ion batteries (LIBs). The GNS were able to deposit onto Co(3)O(4) fibers and form the coating via electrostatic interactions. The unique hybrid paper is evaluated as an anode electrode for LIBs, and it exhibits a very large reversible capacity (∼840 mA h g(-1) after 40 cycles), excellent cyclic stability and good rate capacity. The substantially excellent electrochemical performance of the graphene/Co(3)O(4) composite paper is the result from its unique features. Notably, the flexible structure of graphenic scaffold and the strong interaction between graphene and Co(3)O(4) fibers are beneficial for providing excellent electronic conductivity, short transportation length for lithium ions, and elastomeric space to accommodate volume varies upon Li(+) insertion/extraction.

Magnetic Snell's law and spin-wave fiber with Dzyaloshinskii-Moriya interaction

NASA Astrophysics Data System (ADS)

Yu, Weichao; Lan, Jin; Wu, Ruqian; Xiao, Jiang

2016-10-01

Spin waves are collective excitations propagating in the magnetic medium with ordered magnetizations. Magnonics, utilizing the spin wave (magnon) as an information carrier, is a promising candidate for low-dissipation computation and communication technologies. We discover that, due to the Dzyaloshinskii-Moriya interaction, the scattering behavior of the spin wave at a magnetic domain wall follows a generalized Snell's law, where two magnetic domains work as two different mediums. Similar to optical total reflection that occurs at water-air interfaces, spin waves may experience total reflection at the magnetic domain walls when their incident angle is larger than a critical value. We design a spin-wave fiber using a magnetic domain structure with two domain walls, and demonstrate that such a spin-wave fiber can transmit spin waves over long distances by total internal reflections, in analogy to an optical fiber.

Computational Modeling of Single-Cell Migration: The Leading Role of Extracellular Matrix Fibers

PubMed Central

Schlüter, Daniela K.; Ramis-Conde, Ignacio; Chaplain, Mark A.J.

2012-01-01

Cell migration is vitally important in a wide variety of biological contexts ranging from embryonic development and wound healing to malignant diseases such as cancer. It is a very complex process that is controlled by intracellular signaling pathways as well as the cell’s microenvironment. Due to its importance and complexity, it has been studied for many years in the biomedical sciences, and in the last 30 years it also received an increasing amount of interest from theoretical scientists and mathematical modelers. Here we propose a force-based, individual-based modeling framework that links single-cell migration with matrix fibers and cell-matrix interactions through contact guidance and matrix remodelling. With this approach, we can highlight the effect of the cell’s environment on its migration. We investigate the influence of matrix stiffness, matrix architecture, and cell speed on migration using quantitative measures that allow us to compare the results to experiments. PMID:22995486

Refractive index sensor based on lateral-offset of coreless silica interferometer

NASA Astrophysics Data System (ADS)

Baharin, Nur Faizzah; Azmi, Asrul Izam; Abdullah, Ahmad Sharmi; Mohd Noor, Muhammad Yusof

2018-02-01

A compact, cost-effective and high sensitivity fiber interferometer refractive index (RI) sensor based on symmetrical offset coreless silica fiber (CSF) configuration is proposed, optimized and demonstrated. The sensor is formed by splicing a section of CSF between two CSF sections in an offset manner. Thus, two distinct optical paths are created with large index difference, the first path through the connecting CSF sections and the second path is outside the CSF through the surrounding media. RI sensing is established from direct interaction of light with surrounding media, hence high sensitivity can be achieved with a relatively compact sensor length. In the experimental work, a 1.5 mm sensor demonstrates RI sensitivity of 750 nm/RIU for RI range between 1.33 and 1.345. With the main attributes of high sensitivity and compact size, the proposed sensor can be further developed for related applications including blood diagnosis, water quality control and food industries.

Stimulated Brillouin Scattering Phase Conjugation in Fiber Optic Waveguides

DTIC Science & Technology

2008-07-01

61] The discrepancy is reduced since the effective length of the interaction may be limited by the coherence length of the signal laser as in Eq...these cases, the coherence length of the pulsed laser typically limits the effective length of the Brillouin scattering interaction. Long... coherence length lasers with long fiber SBS media have been used to reduce threshold energy, but as indicated at the end of Chapter 2, this has produced

Detection device for hazardous materials

DOEpatents

Partin, Judy K.; Grey, Alan E.

1994-01-01

A detection device that is activated by the interaction of a hazardous chcal with a coating interactive with said chemical on an optical fiber thereby reducing the amount of light passing through the fiber to a light detector. A combination of optical filters separates the light into a signal beam and a reference beam which after detection, appropriate amplification, and comparison with preset internal signals, activates an alarm means if a predetermined level of contaminant is observed.

Detection device for hazardous materials

DOEpatents

Partin, Judy K.; Grey, Alan E.

1994-04-05

A detection device that is activated by the interaction of a hazardous chcal with a coating interactive with said chemical on an optical fiber thereby reducing the amount of light passing through the fiber to a light detector. A combination of optical filters separates the light into a signal beam and a reference beam which after detection, appropriate amplification, and comparison with preset internal signals, activates an alarm means if a predetermined level of contaminant is observed.

High Areal Capacity Si/LiCoO 2 Batteries from Electrospun Composite Fiber Mats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Self, Ethan C.; Naguib, Michael; Ruther, Rose E.

Here, freestanding nanofiber mat Li-ion battery anodes containing Si nanoparticles, carbon black, and poly(acrylic acid) (Si/C/PAA) are prepared using electrospinning. The mats are compacted to a high fiber volume fraction (~0.85), and interfiber contacts are welded by exposing the mat to methanol vapor. A compacted+welded fiber mat anode containing 40 wt % Si exhibits high capacities of 1,484 mA h g -1 (3,500 mA h gmore » $$-1\\atop{Si}$$) at 0.1 C and 489 mAh g -1 at 1 C and good cycling stability (e.g., 73% capacity retention over 50 cycles). Post-mortem analysis of the fiber mats shows that the overall electrode structure is preserved during cycling. Whereas many nanostructured Si anodes are hindered by their low active material loadings and densities, thick, densely packed Si/C/PAA fiber mat anodes reported here have high areal and volumetric capacities (e.g., 4.5 mA h cm -2 and 750 mA h cm -3, respectively). A full cell containing an electrospun Si/C/PAA anode and electrospun LiCoO 2-based cathode has a high specific energy density of 270 Wh kg -1. The excellent performance of the electrospun Si/C/PAA fiber mat anodes is attributed to the: (i) PAA binder which interacts with the SiO x surface of Si nanoparticles and (ii) high material loading, high fiber volume fraction, and welded interfiber contacts of the electrospun mats« less

Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer

NASA Astrophysics Data System (ADS)

Lim, Ho-Joon; Chang, Kuang-An; Su, Chin B.; Chen, Chi-Yueh

2008-12-01

A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the underestimated measurement value. Velocity information is accurately obtained from the reflected signals before the fiber tip touches the bubble surface so that several factors affecting the traditional dual-tip probes such as blinding, crawling, and drifting effects due to the interaction between the probe and bubbles can be prevented. The coherent signals reflected from both the front and rear ends of a bubble can provide velocity information. Deceleration of rising bubbles and particles due to the presence of the fiber probe is observed when they are very close to the fiber tip. With the residence time obtained, the bubble chord length can be determined by analyzing the coherent signal for velocity determination before the deceleration starts. The bubble diameters are directly obtained from analyzing the signals of the bubbles that contain velocity information. The chord lengths of these bubbles measured by FOR represent the bubble diameters when the bubble shape is spherical or represent the minor axes when the bubble shape is ellipsoidal. The velocity and size of bubbles obtained from the FOR measurements are compared with those obtained simultaneously using a high speed camera.

High Areal Capacity Si/LiCoO 2 Batteries from Electrospun Composite Fiber Mats

DOE PAGES

Self, Ethan C.; Naguib, Michael; Ruther, Rose E.; ...

2017-03-24

Here, freestanding nanofiber mat Li-ion battery anodes containing Si nanoparticles, carbon black, and poly(acrylic acid) (Si/C/PAA) are prepared using electrospinning. The mats are compacted to a high fiber volume fraction (~0.85), and interfiber contacts are welded by exposing the mat to methanol vapor. A compacted+welded fiber mat anode containing 40 wt % Si exhibits high capacities of 1,484 mA h g -1 (3,500 mA h gmore » $$-1\\atop{Si}$$) at 0.1 C and 489 mAh g -1 at 1 C and good cycling stability (e.g., 73% capacity retention over 50 cycles). Post-mortem analysis of the fiber mats shows that the overall electrode structure is preserved during cycling. Whereas many nanostructured Si anodes are hindered by their low active material loadings and densities, thick, densely packed Si/C/PAA fiber mat anodes reported here have high areal and volumetric capacities (e.g., 4.5 mA h cm -2 and 750 mA h cm -3, respectively). A full cell containing an electrospun Si/C/PAA anode and electrospun LiCoO 2-based cathode has a high specific energy density of 270 Wh kg -1. The excellent performance of the electrospun Si/C/PAA fiber mat anodes is attributed to the: (i) PAA binder which interacts with the SiO x surface of Si nanoparticles and (ii) high material loading, high fiber volume fraction, and welded interfiber contacts of the electrospun mats« less

Photonic sensors review recent progress of fiber sensing technologies in Tianjin University

NASA Astrophysics Data System (ADS)

Liu, Tiegen; Liu, Kun; Jiang, Junfeng; Li, Enbang; Zhang, Hongxia; Jia, Dagong; Zhang, Yimo

2011-03-01

The up to date progress of fiber sensing technologies in Tianjin University are proposed in this paper. Fiber-optic temperature sensor based on the interference of selective higher-order modes in circular optical fiber is developed. Parallel demodulation for extrinsic Fabry-Perot interferometer (EFPI) and fiber Bragg grating (FBG) sensors is realized based on white light interference. Gas concentration detection is realized based on intra-cavity fiber laser spectroscopy. Polarization maintaining fiber (PMF) is used for distributed position or displacement sensing. Based on the before work and results, we gained National Basic Research Program of China on optical fiber sensing technology and will develop further investigation in this area.

Improving the reliability of road materials based on micronized sulfur composites

NASA Astrophysics Data System (ADS)

Abdrakhmanova, K. K.

2015-01-01

The work contains the results of a nano-structural modification of sulfur that prevents polymorphic transformations from influencing the properties of sulfur composites where sulfur is present in a thermodynamic stable condition that precludes destruction when operated. It has been established that the properties of sulfur-based composite materials can be significantly improved by modifying sulfur and structuring sulfur binder by nano-dispersed fiber particles and ultra-dispersed state filler. The paper shows the possibility of modifying Tengiz sulfur by its fragmenting which ensures that the structured sulfur is structurally changed and stabilized through reinforcement by ultra-dispersed fiber particles allowing the phase contact area to be multiplied. Interaction between nano-dispersed fibers of chrysotile asbestos and sulfur ensures the implementation of the mechanical properties of chrysotile asbestos tubes in reinforced composite and its integrity provided that the surface of chrysotile asbestos tubes are highly moistened with molten sulfur and there is high adhesion between the tubes and the matrix that, in addition to sulfur, contains limestone microparticles. Ability to apply materials in severe operation conditions and possibility of exposure in both aggressive medium and mechanical loads makes produced sulfur composites required by the road construction industry.

A Review on Grafting of Biofibers for Biocomposites

PubMed Central

Wei, Liqing; McDonald, Armando G.

2016-01-01

A recent increase in the use of biofibers as low-cost and renewable reinforcement for the polymer biocomposites has been seen globally. Biofibers are classified into: lignocellulosic fibers (i.e., cellulose, wood and natural fibers), nanocellulose (i.e., cellulose nanocrystals and cellulose nanofibrils), and bacterial cellulose, while polymer matrix materials can be petroleum based or bio-based. Green biocomposites can be produced using both biobased fibers and polymers. Incompatibility between the hydrophilic biofibers and hydrophobic polymer matrix can cause performance failure of resulting biocomposites. Diverse efforts have focused on the modification of biofibers in order to improve the performances of biocomposites. “Grafting” copolymerization strategy can render the advantages of biofiber and impart polymer properties onto it and the performance of biocomposites can be tuned through changing grafting parameters. This review presents a short overview of various “grafting” methods which can be directly or potentially employed to enhance the interaction between biofibers and a polymer matrix for biocomposites. Major grafting techniques, including ring opening polymerization, grafting via coupling agent and free radical induced grafting, have been discussed. Improved properties such as mechanical, thermal, and water resistance have provided grafted biocomposites with new opportunities for applications in specific industries. PMID:28773429

A musculo-mechanical model of esophageal transport based on an immersed boundary-finite element approach

NASA Astrophysics Data System (ADS)

Kou, Wenjun; Griffith, Boyce E.; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

2015-11-01

This work extends a fiber-based immersed boundary (IB) model of esophageal transport by incorporating a continuum model of the deformable esophageal wall. The continuum-based esophagus model adopts finite element approach that is capable of describing more complex and realistic material properties and geometries. The leakage from mismatch between Lagrangian and Eulerian meshes resulting from large deformations of the esophageal wall is avoided by careful choice of interaction points. The esophagus model, which is described as a multi-layered, fiber-reinforced nonlinear elastic material, is coupled to bolus and muscle-activation models using the IB approach to form the esophageal transport model. Cases of esophageal transport with different esophagus models are studied. Results on the transport characteristics, including pressure field and esophageal wall kinematics and stress, are analyzed and compared. Support from NIH grant R01 DK56033 and R01 DK079902 is gratefully acknowledged. BEG is supported by NSF award ACI 1460334.

All-optical fiber anemometer based on laser heated fiber Bragg gratings.

PubMed

Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

2011-05-23

A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

Characterization of low thermal conductivity PAN-based carbon fibers

NASA Technical Reports Server (NTRS)

Katzman, Howard A.; Adams, P. M.; Le, T. D.; Hemminger, Carl S.

1992-01-01

The microstructure and surface chemistry of eight low thermal conductivity (LTC) PAN-based carbon fibers were determined and compared with PAN-based fibers heat treated to higher temperatures. Based on wide-angle x ray diffraction, the LTC PAN fibers all appear to have a similar turbostratic structure with large 002 d-spacings, small crystallite sizes, and moderate preferred orientation. Limited small-angle x ray scattering (SAXS) results indicate that, with the exception of LTC fibers made by BASF, the LTC fibers do not have well developed pores. Transmission electron microscopy shows that the texture of the two LTC PAN-based fibers studied (Amoco T350/23X and /25X) consists of multiple sets of parallel, wavy, bent layers that interweave with each other forming a complex three dimensional network oriented randomly around the fiber axis. X ray photoelectron spectroscopy (XPS) analysis finds correlations between heat treated temperatures and the surface composition chemistry of the carbon fiber samples.

Objective-lens-free Fiber-based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System.

PubMed

Ti, Chaoyang; Ho-Thanh, Minh-Tri; Wen, Qi; Liu, Yuxiang

2017-10-13

Position detection with high accuracy is crucial for force calibration of optical trapping systems. Most existing position detection methods require high-numerical-aperture objective lenses, which are bulky, expensive, and difficult to miniaturize. Here, we report an affordable objective-lens-free, fiber-based position detection scheme with 2 nm spatial resolution and 150 MHz bandwidth. This fiber based detection mechanism enables simultaneous trapping and force measurements in a compact fiber optical tweezers system. In addition, we achieved more reliable signal acquisition with less distortion compared with objective based position detection methods, thanks to the light guiding in optical fibers and small distance between the fiber tips and trapped particle. As a demonstration of the fiber based detection, we used the fiber optical tweezers to apply a force on a cell membrane and simultaneously measure the cellular response.

Impact of fiber ring laser configuration on detection capabilities in FBG based sensor systems

NASA Astrophysics Data System (ADS)

Osuch, Tomasz; Kossek, Tomasz; Markowski, Konrad

2014-11-01

In this paper fiber ring lasers (FRL) as interrogation units for distributed fiber Bragg grating (FBG) based sensor networks are studied. In particular, two configurations of the fiber laser with erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA) as gain medium were analyzed. In the case of EDFA-based fiber interrogation systems, CW as well as active-mode locking operation were taken into account. The influence of spectral overlapping of FBGs spectra on detection capabilities of examined FRLs are presented. Experimental results show that the SOA-based fiber laser interrogation unit can operate as a multi-parametric sensing system. In turn, using an actively mode-locked fiber ring laser with an EDFA, an electronically switchable FBG based sensing system can be realized.

Sagnac-interferometer-based fresnel flow probe.

PubMed

Tselikov, A; Blake, J

1998-10-01

We used a near-diffraction-limited flow or light-wave-interaction pipe to produce a Sagnac-interferometer-based Fresnel drag fluid flowmeter capable of detecting extremely small flow rates. An optimized design of the pipe along with the use of a state-of-the-art Sagnac interferometer results in a minimum-detectable water flow rate of 2.4 nl/s [1 drop/(5 h)]. The flowmeter's capability of measuring the water consumption by a small plant in real time has been demonstrated. We then designed an automated alignment system that finds and maintains the optimum fiber-coupling regime, which makes the applications of the Fresnel-drag-based flowmeters practical, especially if the length of the interaction pipe is long. Finally, we have applied the automatic alignment technique to an air flowmeter.

Postquench prethermalization in a disordered quantum fluid of light

NASA Astrophysics Data System (ADS)

Larré, Pierre-Élie; Delande, Dominique; Cherroret, Nicolas

2018-04-01

We study the coherence of a disordered and interacting quantum light field after propagation along a nonlinear optical fiber. Disorder is generated by a cross-phase modulation with a randomized auxiliary classical light field, while interactions are induced by self-phase modulation. When penetrating the fiber from free space, the incoming quantum light undergoes a disorder and interaction quench. By calculating the coherence function of the transmitted quantum light, we show that the decoherence induced by the quench spreads in a light-cone fashion in the nonequilibrium many-body quantum system, leaving the latter prethermalize with peculiar features originating from disorder.

Optimization of a Paper-Based ELISA for a Human Performance Biomarker

DTIC Science & Technology

2013-11-11

the response of the assay through minimizing the interaction of the antigen with the cellulose fibers 28 . However, the chemiluminescent assay used...28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 18 to proteases, microbial contamination, or

Three-dimensional FEM model of FBGs in PANDA fibers with experimentally determined model parameters

NASA Astrophysics Data System (ADS)

Lindner, Markus; Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

2017-04-01

A 3D-FEM model has been developed to improve the understanding of multi-parameter sensing with Bragg gratings in attached or embedded polarization maintaining fibers. The material properties of the fiber, especially Young's modulus and Poisson's ratio of the fiber's stress applying parts, are crucial for accurate simulations, but are usually not provided by the manufacturers. A methodology is presented to determine the unknown parameters by using experimental characterizations of the fiber and iterative FEM simulations. The resulting 3D-Model is capable of describing the change in birefringence of the free fiber when exposed to longitudinal strain. In future studies the 3D-FEM model will be employed to study the interaction of PANDA fibers with the surrounding materials in which they are embedded.

Cardiometabolic risk factors are associated with high urinary enterolactone concentration, independent of urinary enterodiol concentration and dietary fiber intake in adults.

PubMed

Frankenfeld, Cara L

2014-09-01

The study objective was to evaluate independent and interactive associations of dietary fiber intake and high urinary enterolignans with cardiometabolic risk factors. The analysis included 2260 adults (≥20 y of age) from the 2003-2010 NHANES. Logistic regression models were used to evaluate obesity and clinically defined cardiometabolic risk factors in relation to dietary fiber intake and urinary enterolignan concentrations. Three sets of models were created: 1) independent associations, 2) mutually adjusted associations, and 3) interactions. Models were adjusted for age, gender, race/ethnicity, education, smoking status, and energy intake. High concentrations were considered to be above the 90th percentile of urinary enterolignan concentrations. Increasing dietary fiber intake was associated with high blood pressure (P = 0.02) and low serum HDL cholesterol (P-trend = 0.03). High urinary enterodiol concentration was not associated with obesity or cardiometabolic risk factors. High urinary enterolactone concentration was inversely associated with obesity (OR: 0.44; 95% CI: 0.29, 0.66), abdominal obesity (OR: 0.58; 95% CI: 0.39, 0.87), high serum C-reactive protein (CRP; OR: 0.52; 95% CI: 0.37, 0.74), high serum triglycerides (OR: 0.39; 95% CI: 0.23, 0.61), low serum HDL cholesterol (OR: 0.37; 95% CI: 0.23, 0.61), and metabolic syndrome (OR: 0.47; 95% CI: 0.30, 0.74). In mutually adjusted models, enterolactone associations observed in independent models remained similar, but associations for dietary fiber intake were attenuated, with the exception of blood pressure. In interaction models, there were 2 significant interactions: between high urinary enterodiol concentration and dietary fiber intake for high serum CRP (P = 0.04) and high plasma glucose (P = 0.04). Overall, being in the highest 10% of urinary enterolactone concentration was associated with cardiometabolic risk factors, independent of dietary fiber intake and enterodiol concentration. Future studies are warranted to evaluate physiologic actions of enterolactone or aspects of the gut microbial profile responsible for lignan metabolism to enterolactone. © 2014 American Society for Nutrition.

Fermentation of Ammonia Fiber Expansion Treated and Untreated Barley Straw in a Rumen Simulation Technique Using Rumen Inoculum from Cattle with Slow versus Fast Rate of Fiber Disappearance

PubMed Central

Griffith, Candace L.; Ribeiro, Gabriel O.; Oba, Masahito; McAllister, Tim A.; Beauchemin, Karen A.

2016-01-01

The purpose of this study was to determine the effect of rumen inoculum from heifers with fast vs. slow rate of in situ fiber digestion on the fermentation of complex versus easily digested fiber sources in the forms of untreated and Ammonia Fiber Expansion (AFEX) treated barley straw, respectively, using an artificial rumen simulation technique (Rusitec). In situ fiber digestion was measured in a previous study by incubating untreated barley straw in the rumen of 16 heifers fed a diet consisting of 700 g/kg barley straw and 300 g/kg concentrate. The two heifers with fastest rate of digestion (Fast ≥ 4.18% h-1) and the two heifers with the slowest rate of digestion (Slow ≤ 3.17% h-1) were chosen as inoculum donors for this study. Two Rusitec apparatuses each equipped with eight fermenters were used in a completely randomized block design with two blocks (apparatus) and four treatments in a 2 × 2 factorial arrangement of treatments (Fast or Slow rumen inoculum and untreated or AFEX treated straw). Fast rumen inoculum and AFEX straw both increased (P < 0.05) disappearance of dry matter (DMD), organic matter, true DMD, neutral detergent fiber, acid detergent fiber, and nitrogen (N) with an interactive effect between the two (P < 0.05). Fast rumen inoculum increased (P > 0.05) methane production per gram of digested material for both untreated and AFEX straw, and reduced (interaction, P < 0.05) acetate: propionate ratio for untreated straw. Greater relative populations of Ruminococcus albus (P < 0.05) and increased microbial N production (P = 0.045) were observed in Fast rumen inoculum. AFEX straw in Fast inoculum had greater total bacterial populations than Slow, but for untreated straw this result was reversed (interaction, P = 0.013). These findings indicate that differences in microbial populations in rumen fluid contribute to differences in the capacity of rumen inoculum to digest fiber. PMID:27899919

Homogenization Models for Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Muc, A.; Jamróz, M.

2004-03-01

Two homogenization models for evaluating Young's modulus of nanocomposites reinforced with single-walled and multi-walled carbon nanotubes are presented. The first model is based on a physical description taking into account the interatomic interaction and nanotube geometry. The elementary cell, here a nanotube with a surrounding resin layer, is treated as a homogeneous body — a material continuum. The second model, similar to a phenomenological engineering one, is obtained by combining the law of mixture with the Cox mechanical model. This model describes the stress distribution along stretched short fibers surrounded by a resin matrix. The similarities between composite materials reinforced with short fibers and nanotubes are elucidated. The results obtained are compared with those for classical microcomposites to demonstrate the advantages and disadvantages of both the composite materials.

Freestanding, Fiber-Based, Wearable Temperature Sensor with Tunable Thermal Index for Healthcare Monitoring.

PubMed

Trung, Tran Quang; Le, Hoang Sinh; Dang, Thi My Linh; Ju, Sanghyun; Park, Sang Yoon; Lee, Nae-Eung

2018-06-01

Fiber-based sensors integrated on textiles or clothing systems are required for the next generation of wearable electronic platforms. Fiber-based physical sensors are developed, but the development of fiber-based temperature sensors is still limited. Herein, a new approach to develop wearable temperature sensors that use freestanding single reduction graphene oxide (rGO) fiber is proposed. A freestanding and wearable temperature-responsive rGO fiber with tunable thermal index is obtained using simple wet spinning and a controlled graphene oxide reduction time. The freestanding fiber-based temperature sensor shows high responsivity, fast response time (7 s), and good recovery time (20 s) to temperature. It also maintains its response under an applied mechanical deformation. The fiber device fabricated by means of a simple process is easily integrated into fabric such as socks or undershirts and can be worn by a person to monitor the temperature of the environment and skin temperature without interference during movement and various activities. These results demonstrate that the freestanding fiber-based temperature sensor has great potential for fiber-based wearable electronic platforms. It is also promising for applications in healthcare and biomedical monitoring. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic Interaction of Neuroglian and Semaphorin1a during Guidance and Synapse Formation

PubMed Central

Godenschwege, Tanja A.; Murphey, Rodney K.

2009-01-01

We have previously demonstrated a function for Neuroglian and Semaphorin1a in Drosophila giant fiber circuit formation. Both molecules are required for guiding the giant fibers out of the brain and have distinct functions during giant synapse formation. In this study we characterized the effects of various combinations of Neuroglian and Semaphorin1a gain and loss of function backgrounds on giant fiber circuitry formation. We found that Neuroglian and Semaphorin1a genetically interact with each other during axon guidance as well as during synapse formation. Our experiments revealed that during pathfinding of the giant fibers out of the brain, Neuroglian function seems to be dependent on Semaphorin1a. In contrast, during giant fiber synapse formation we observed that Semaphorin1a signaling as a receptor can be altered by Neuroglian in the same cell. In summary, our findings suggest that Neuroglian and Semaphorin1a can regulate each other’s function in cis and that the resultant signaling output is possibly different during guidance and synapse formation. PMID:19052954

Defluoridation potential of jute fibers grafted with fatty acyl chain

NASA Astrophysics Data System (ADS)

Manna, Suvendu; Saha, Prosenjit; Roy, Debasis; Sen, Ramkrishna; Adhikari, Basudam

2015-11-01

Waterborne fluoride is usually removed from water by coagulation, adsorption, ion exchange, electro dialysis or reverse osmosis. These processes are often effective over narrow pH ranges, release ions considered hazardous to human health or produce large volumes of toxic sludge that are difficult to handle and dispose. Although plant matters have been shown to remove waterborne fluoride, they suffer from poor removal efficiency. Following from the insight that interaction between microbial carbohydrate biopolymers and anionic surfaces is often facilitated by lipids, an attempt has been made to enhance fluoride adsorption efficiency of jute by grafting the lignocellulosic fiber with fatty acyl chains found in vegetable oils. Fluoride removal efficiency of grafted jute was found to be comparable or higher than those of alternative defluoridation processes. Infrared and X-ray photoelectron spectroscopic evidence indicated that hydrogen bonding, protonation and C-F bonding were responsible for fluoride accumulation on grafted jute. Adsorption based on grafted jute fibers appears to be an economical, sustainable and eco-friendly alternative technique for removing waterborne fluoride.

Ultrasonic NDE Simulation for Composite Manufacturing Defects

NASA Technical Reports Server (NTRS)

Leckey, Cara A. C.; Juarez, Peter D.

2016-01-01

The increased use of composites in aerospace components is expected to continue into the future. The large scale use of composites in aerospace necessitates the development of composite-appropriate nondestructive evaluation (NDE) methods to quantitatively characterize defects in as-manufactured parts and damage incurred during or post manufacturing. Ultrasonic techniques are one of the most common approaches for defect/damage detection in composite materials. One key technical challenge area included in NASA's Advanced Composite's Project is to develop optimized rapid inspection methods for composite materials. Common manufacturing defects in carbon fiber reinforced polymer (CFRP) composites include fiber waviness (in-plane and out-of-plane), porosity, and disbonds; among others. This paper is an overview of ongoing work to develop ultrasonic wavefield based methods for characterizing manufacturing waviness defects. The paper describes the development and implementation of a custom ultrasound simulation tool that is used to model ultrasonic wave interaction with in-plane fiber waviness (also known as marcelling). Wavefield data processing methods are applied to the simulation data to explore possible routes for quantitative defect characterization.

Physical measurement with in-line fiber Mach-Zehnder interferometer using differential phase white light interferometry

NASA Astrophysics Data System (ADS)

Aref, Seyed Hashem

2017-11-01

In this letter, the sensitivity to strain, curvature, and temperature of a sensor based on in-line fiber Mach-Zahnder interferometer (IFMZI) is studied and experimentally demonstrated. The sensing structure is simply a section of single mode fiber sandwiched between two abrupt tapers to achieve a compact IFMZI. The phase of interferometer changes with the measurand interaction, which is the basis for considering this structure for sensing. The physical parameter sensitivity of IFMZI sensor has been evaluated using differential white light interferometry (DWLI) technique as a phase read-out system. The differential configuration of the IFMZI sensor is used to achieve a high phase resolving power of ±0.062° for read-out interferometer by means of omission of phase noise of environment perturbations. The sensitivity of the sensor to the strain, curvature, and temperature has been measured 0.0199 degree/με, 757.00 degree/m-1, and 3.25 degree/°C, respectively.

Precision-feeding dairy heifers a high rumen-undegradable protein diet with different proportions of dietary fiber and forage-to-concentrate ratios.

PubMed

Koch, L E; Gomez, N A; Bowyer, A; Lascano, G J

2017-12-01

The addition of dietary fiber can alter nutrient and N utilization in precision-fed dairy heifers and may further benefit from higher inclusion levels of RUP. The objective of this experiment was to determine the effects of feeding a high-RUP diet when dietary fiber content was manipulated within differing forage-to-concentrate ratios (F:C) on nutrient utilization of precision-fed dairy heifers. Six rumen-cannulated Holstein heifers (555.4 ± 31.4 kg BW; 17.4 ± 0.1 mo) were randomly assigned to 2 levels of forage, high forage (HF; 60% forage) or low forage (LF; 45% forage), and to a fiber proportion sequence (low fiber: 100% oat hay and silage [OA], 0% wheat straw [WS]; medium fiber: 83.4% OA, 16.6% WS; and high fiber: 66.7% OA, 33.3% WS) administered according to a split-plot 3 × 3 Latin square design (21-d periods). Similar levels of N intake (1.70 g N/kg BW) and RUP (55% of CP) were provided. Data were analyzed as a split-plot, 3 × 3 Latin square design using a mixed model with fixed effects of period and treatment. A repeated measures model was used with data that had multiple measurements over time. No differences were observed for DM, OM, NDF, or ADF apparent digestibility coefficients (dC) between HF- and LF-fed heifers. Heifers receiving LF diets had greater starch dC compared to HF heifers. Increasing the fiber level through WS addition resulted in a linear reduction of OM dC. There was a linear interaction for DM dC with a concurrent linear interaction in NDF dC. Nitrogen intake, dC, and retention did not differ; however, urine and total N excretion increased linearly with added fiber. Predicted microbial CP flow (MP) linearly decreased with WS inclusion mainly in LF heifers, as indicated by a significant interaction between F:C and WS. Rumen pH linearly increased with WS addition, although no F:C effect was detected. Ruminal ammonia concentration had an opposite linear effect with respect to MP as WS increased. Diets with the higher proportion of fiber benefited the most from a high RUP supply, complementing the substantial reduction in predicted MP caused by the incremental dietary fiber concentration. These results suggest that RUP supplementation is a practical method for reestablishing optimal ruminal N balance in the event of increased dietary fiber through forage inclusion in precision-fed dairy heifer diets.

Stitch modeling of non crimp fabric in forming simulations

NASA Astrophysics Data System (ADS)

Steer, Q.; Colmars, J.; Boisse, P.

2018-05-01

The use of Non Crimp Fabric composite has increased during the last years due to cheaper cost of manufacturing and high mechanicals properties suitable for applications such as aeronautic, automotive and wind turbines. The main difference between Non Crimp Fabric (NCF) and textile reinforcement is the mean of manufacturing: where in textile fibers are woven, in NCF layers of unidirectional oriented fibers are assembled with a stitch. As a consequence, the stitch especially its geometry (stitch pattern) will have a major influence on the deformation of this type of reinforcement during forming process. Experimental campaigns on NCF samples compared to textile with the same fibers orientation have showed that the stitch affects the shear behavior of the reinforcement which is the main mode of deformation in the forming process. A description of the stitch has been implemented in a shell element for macro scale forming simulation as a first approach based on simple hypothesis. Further works are focus on the specific behavior of the stitch along the fabric and interaction with the fibers layers during shear deformation of the reinforcement and a method to implement the stitch in a more refined model of the fabric.

Hybrid photonic-crystal fiber

NASA Astrophysics Data System (ADS)

Markos, Christos; Travers, John C.; Abdolvand, Amir; Eggleton, Benjamin J.; Bang, Ole

2017-10-01

This article offers an extensive survey of results obtained using hybrid photonic-crystal fibers (PCFs) which constitute one of the most active research fields in contemporary fiber optics. The ability to integrate novel and functional materials in solid- and hollow-core PCFs through various postprocessing methods has enabled new directions toward understanding fundamental linear and nonlinear phenomena as well as novel application aspects, within the fields of optoelectronics, material and laser science, remote sensing, and spectroscopy. Here the recent progress in the field of hybrid PCFs is reviewed from scientific and technological perspectives, focusing on how different fluids, solids, and gases can significantly extend the functionality of PCFs. The first part of this review discusses the efforts to develop tunable linear and nonlinear fiber-optic devices using PCFs infiltrated with various liquids, glasses, semiconductors, and metals. The second part concentrates on recent and state-of-the-art advances in the field of gas-filled hollow-core PCFs. Extreme ultrafast gas-based nonlinear optics toward light generation in the extreme wavelength regions of vacuum ultraviolet, pulse propagation, and compression dynamics in both atomic and molecular gases, and novel soliton-plasma interactions are reviewed. A discussion of future prospects and directions is also included.

Multi-kW single fiber laser based on an extra large mode area fiber design

NASA Astrophysics Data System (ADS)

Langner, Andreas; Such, Mario; Schötz, Gerhard; Just, Florian; Leich, Martin; Schwuchow, Anka; Grimm, Stephan; Zimer, Hagen; Kozak, Marcin; Wedel, Björn; Rehmann, Georg; Bachert, Charley; Krause, Volker

2012-02-01

The quality of Yb-doped fused bulk silica produced by sintering of Yb-doped fused silica granulates has improved greatly in the past five years [1 - 4]. In particular, the refractive index and doping level homogeneity of such materials are excellent and we achieved excellent background fiber attenuation of the active core material down to about 20 dB/km at 1200 nm. The improvement of the Yb-doped fused bulk silica has enabled the development of multi-kW fiber laser systems based on a single extra large multimode laser fiber (XLMA fiber). When a single active fiber is used in combination with the XLMA multimode fiber of 1200 μm diameter simple and robust high power fiber laser setups without complex fiber coupling and fiber combiner systems become possible. In this papper, we will discuss in detail the development of the core material based on Yb-doped bulk silica and the characterization of Yb-doped fibers with different core compositions. We will also report on the excellent performance of a 4 kW fiber laser based on a single XLMA-fiber and show the first experimental welding results of steel sheets achieved with such a laser.

A TEMPLATE-BASED FABRICATION TECHNIQUE FOR SPATIALLY-DESIGNED POLYMER MICRO/NANOFIBER COMPOSITES

PubMed Central

Naik, Nisarga; Caves, Jeff; Kumar, Vivek; Chaikof, Elliot; Allen, Mark G.

2013-01-01

This paper reports a template-based technique for the fabrication of polymer micro/nanofiber composites, exercising control over the fiber dimensions and alignment. Unlike conventional spinning-based methods of fiber production, the presented approach is based on micro-transfer molding. It is a parallel processing technique capable of producing fibers with control over both in-plane and out-of-plane geometries, in addition to packing density and layout of the fibers. Collagen has been used as a test polymer to demonstrate the concept. Hollow and solid collagen fibers with various spatial layouts have been fabricated. Produced fibers have widths ranging from 2 µm to 50 µm, and fiber thicknesses ranging from 300 nm to 3 µm. Also, three-dimensionality of the process has been demonstrated by producing in-plane serpentine fibers with designed arc lengths, out-of-plane wavy fibers, fibers with focalized particle encapsulation, and porous fibers with desired periodicity and pore sizes. PMID:24533428

A comparison of the bromination dynamics of various carbon and graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, James R.

1987-01-01

The electrical resistance of four grades of pitch-based graphite fibers and three experimental organic vapor-derived fibers was determined in situ during bromination and subsequent exposure to ambient laboratory air. The results show that the least graphitic pitch-based fiber does not brominate significantly, and that bromination and debrominaton reactions proceed much slower for vapor-derived fibers than for pitch-based ones. It is suggested that this decreased reacton rate is primarily due to the differences in graphene plane orientation between the fiber types. The results also imply that the vapor-derived and pitch-based fibers produce true intercalation compounds.

On-Chip Photonic Circuits for Atom-Light Interaction in Quantum Information and Integrated Optical Spectrometer for Astrophotonics

NASA Astrophysics Data System (ADS)

Meng, Yang

Photonic circuits are becoming very promising in many different applications, such as optical amplification, optical switching and wavelength division multiplexing optical networks, lab-on-chip in bioengineering, atom-light interaction in quantum information processing, wavelength selecting and filtering in astronomy, etc. Thanks to major developments in the nanofabrication technology, smaller but more powerful photonic circuits can be made to realize more complex applications. Here we propose two on-chip photonic circuits: one is for atom-light interaction in quantum information, and the other is for an optical spectrometer in astronomy. Part I. The atom-light interaction can be used for a number of quantum based application, such as quantum information processing and atomic sensing. These significant applications make atom-light interaction a strong candidate for next-generation quantum computers and ultraprecise magnetic or navigation sensors. People have proposed various types of atom-photon interaction, and enhancing the interaction by using a small mode area has also been demonstrated in several platforms such as a hollow-core fiber, a hollow-core waveguide, a tapered fiber, and a nanowaveguide. In our work, we propose a nanowaveguide platform for collective atom-light interaction through the evanescent optical field coupling. We have demonstrated a centimeter-long silicon nitride nanowaveguide that has a sub-micrometer mode area and high fiber-to-waveguide coupling efficiencies for near-infrared wavelengths, working as evanescent field atom trapping/probing of an ensemble of 87Rb atoms. Inverse tapers are made at both ends of the waveguide that adiabatically transfer the weakly guided fiber-coupled mode to a strongly guided mode with an evanescent field for a better fiber-waveguide coupling efficiency. The coupling efficiency improves from around 2% to around 80% for both wavelengths. Trapping atoms by nanowaveguide modes is challenging because the small mode area generates high heat flux at the waveguide in an ultra-high vacuum. This platform has good thermal conductance and could transfer high enough optical powers to trap atoms in an ultra-high vacuum compared to a standalone photonic crystal waveguide with no substrate or an evanescent field coupled with a nanofiber. We have experimentally measured the optical absorption of thermal 87Rb atoms through the guided waveguide mode. We have also demonstrated an atom-chip mirror MOT with the same dimension of the platform that can be transferred to the proximity of the surface by magnetic field controls. Part II. In astronomical applications, wavelength analysis is very important especially for the wavelength selecting and filtering. Here we focus on the wavelength range from 1microm to 1.7microm. There are many valuable applications that make this near infrared wavelength range so important. For example, the Lyman-alpha line of hydrogen is one of the very important emission lines of hydrogen for understanding the origin and creation of the universe. Since the universe has expanded for more than 10 billion years after the big bang, the Lyman-alpha line of hydrogen has redshifted from 121.5nm to the 1microm-to-1.7microm wavelength range according to Hubble's Law. In addition, analysis of this wavelength range can also help us understand many other cosmic phenomena such as quasars, Gamma-ray bursts, etc. Therefore, a good spectrometer is needed to achieve this. Here we present an echelle grating which is based on an on-chip spectrometer that covers the near infrared wavelength range from 1.45um to 1.7um. To begin with, we use optical waveguides as the input and output channels. We have successfully achieved a reliable fabrication process to make the on-chip echelle-grating spectrometer. We have also achieved high fiber-waveguide coupling efficiency (94% per facet at 1550nm) and low propagation loss (-0.975dB/cm at 1550nm) for the input and output waveguides. In addition, we have characterized the bending loss of the waveguide. Finally, we have successfully measured the output spectrum of the echelle grating we designed and found it to be in good agreement with our simulation.

Bilinearization of the generalized coupled nonlinear Schrödinger equation with variable coefficients and gain and dark-bright pair soliton solutions.

PubMed

Chakraborty, Sushmita; Nandy, Sudipta; Barthakur, Abhijit

2015-02-01

We investigate coupled nonlinear Schrödinger equations (NLSEs) with variable coefficients and gain. The coupled NLSE is a model equation for optical soliton propagation and their interaction in a multimode fiber medium or in a fiber array. By using Hirota's bilinear method, we obtain the bright-bright, dark-bright combinations of a one-soliton solution (1SS) and two-soliton solutions (2SS) for an n-coupled NLSE with variable coefficients and gain. Crucial properties of two-soliton (dark-bright pair) interactions, such as elastic and inelastic interactions and the dynamics of soliton bound states, are studied using asymptotic analysis and graphical analysis. We show that a bright 2-soliton, in addition to elastic interactions, also exhibits multiple inelastic interactions. A dark 2-soliton, on the other hand, exhibits only elastic interactions. We also observe a breatherlike structure of a bright 2-soliton, a feature that become prominent with gain and disappears as the amplitude acquires a minimum value, and after that the solitons remain parallel. The dark 2-soliton, however, remains parallel irrespective of the gain. The results found by us might be useful for applications in soliton control, a fiber amplifier, all optical switching, and optical computing.

Robust transmission of non-Gaussian entanglement over optical fibers

NASA Astrophysics Data System (ADS)

Biswas, Asoka; Lidar, Daniel A.

2006-12-01

We show how the entanglement in a wide range of continuous variable non-Gaussian states can be preserved against decoherence for long-range quantum communication through an optical fiber. We apply protection via decoherence-free subspaces and quantum dynamical decoupling to this end. The latter is implemented by inserting phase shifters at regular intervals Δ inside the fiber, where Δ is roughly the ratio of the speed of light in the fiber to the bath high-frequency cutoff. Detailed estimates of relevant parameters are provided using the boson-boson model of system-bath interaction for silica fibers and Δ is found to be on the order of a millimeter.

Rate and timing cues associated with the cochlear amplifier: level discrimination based on monaural cross-frequency coincidence detection.

PubMed

Heinz, M G; Colburn, H S; Carney, L H

2001-10-01

The perceptual significance of the cochlear amplifier was evaluated by predicting level-discrimination performance based on stochastic auditory-nerve (AN) activity. Performance was calculated for three models of processing: the optimal all-information processor (based on discharge times), the optimal rate-place processor (based on discharge counts), and a monaural coincidence-based processor that uses a non-optimal combination of rate and temporal information. An analytical AN model included compressive magnitude and level-dependent-phase responses associated with the cochlear amplifier, and high-, medium-, and low-spontaneous-rate (SR) fibers with characteristic frequencies (CFs) spanning the AN population. The relative contributions of nonlinear magnitude and nonlinear phase responses to level encoding were compared by using four versions of the model, which included and excluded the nonlinear gain and phase responses in all possible combinations. Nonlinear basilar-membrane (BM) phase responses are robustly encoded in near-CF AN fibers at low frequencies. Strongly compressive BM responses at high frequencies near CF interact with the high thresholds of low-SR AN fibers to produce large dynamic ranges. Coincidence performance based on a narrow range of AN CFs was robust across a wide dynamic range at both low and high frequencies, and matched human performance levels. Coincidence performance based on all CFs demonstrated the "near-miss" to Weber's law at low frequencies and the high-frequency "mid-level bump." Monaural coincidence detection is a physiologically realistic mechanism that is extremely general in that it can utilize AN information (average-rate, synchrony, and nonlinear-phase cues) from all SR groups.

Whole Tibetan Hull-Less Barley Exhibit Stronger Effect on Promoting Growth of Genus Bifidobacterium than Refined Barley In Vitro.

PubMed

Gong, Lingxiao; Cao, Wenyan; Gao, Jie; Wang, Jing; Zhang, Huijuan; Sun, Baoguo; Yin, Meng

2018-04-01

The gut microbiota has recently become a new route for research at the intersection of diet and human health. The aim of this study was to investigate whether whole Tibetan hull-less barley (WHB) and refined Tibetan hull-less barley (RHB) caused differentiation of the fecal microbiota in vitro. The microbiota-accessible ingredients in the 2 barley samples were studied using an in vitro enzymatic digestion procedure. After in vitro digestion, insoluble dietary fiber, phenolic compounds, proteins, and β-glucans were 93.2%, 103.4%. 18.8%, and 10.2% higher provided by WHB flour as compared with RHB flour based on the same mass amount. However, due to the significantly higher content of insoluble dietary fiber, WHB digesta had lower percentage contents of fast fermentable substrates including dietary fiber and starch as compared with RHB digesta. The results of Next-generation sequencing of the bacterial 16SrRNA gene showed that both WHB and RHB fermentation had significantly promoted the growth of Bifidobacterium and inhibited the growth of pathogenic bacteria such as Dorea, Escherichia, Oscillopira, and Ruminococcus. Moreover, in response to WHB fermentation, the relative abundance of Bifidobacterium increased by 78.5% and 92.8% as compared with RHB and fructo-oligosaccharides (FOs). Both WHB and RHB are good sources of fermentable dietary fiber with the ability to yield high concentration of short chain fatty acids (SCFAs) as compared to FOs. However, the higher fraction of soluble fiber in RHB digesta increase higher amounts of SCFA compared with WHB digesta. Our findings shed light on the complex interactions of whole cereals with gut microbiota and the possible impact on host health. Until now, only few reports have regarded the impact of in vitro digestion in components of whole grain with complex food matrix. Moreover, our findings shed light on the complex interactions of whole cereals with gut microbiota and the possible impact on host health. © 2018 Institute of Food Technologists®.

Behavior of concrete specimens reinforced with composite materials : laboratory study

DOT National Transportation Integrated Search

2000-02-01

The main objective of this study was to investigate the interaction between FRP composite and concrete by addressing the most important : variables in terms of FRP (fiber reinforced polymer) properties. Type of fibers, thickness of the laminates, fib...

Fluorescence lifetime endoscopy using TCSPC for the measurement of FRET in live cells

PubMed Central

Fruhwirth, Gilbert O.; Ameer-Beg, Simon; Cook, Richard; Watson, Timothy; Ng, Tony; Festy, Frederic

2010-01-01

Development of remote imaging for diagnostic purposes has progressed dramatically since endoscopy began in the 1960’s. The recent advent of a clinically licensed intensity-based fluorescence micro-endoscopic instrument has offered the prospect of real-time cellular resolution imaging. However, interrogating protein-protein interactions deep inside living tissue requires precise fluorescence lifetime measurements to derive the Förster resonance energy transfer between two tagged fluorescent markers. We developed a new instrument combining remote fiber endoscopic cellular-resolution imaging with TCSPC-FLIM technology to interrogate and discriminate mixed fluorochrome labeled beads and expressible GFP/TagRFP tags within live cells. Endoscopic-FLIM (e-FLIM) data was validated by comparison with data acquired via conventional FLIM and e-FLIM was found to be accurate for both bright bead and dim live cell samples. The fiber based micro-endoscope allowed remote imaging of 4 µm and 10 µm beads within a thick Matrigel matrix with confident fluorophore discrimination using lifetime information. More importantly, this new technique enabled us to reliably measure protein-protein interactions in live cells embedded in a 3D matrix, as demonstrated by the dimerization of the fluorescent protein-tagged membrane receptor CXCR4. This cell-based application successfully demonstrated the suitability and great potential of this new technique for in vivo pre-clinical biomedical and possibly human clinical applications. PMID:20588974

Polarization insensitive all-fiber mode-lockers functioned by carbon nanotubes deposited onto tapered fibers

NASA Astrophysics Data System (ADS)

Song, Yong-Won; Morimune, Keiyo; Set, Sze Y.; Yamashita, Shinji

2007-01-01

The authors demonstrate a nonblocked all-fiber mode locker operated by the interaction of carbon nanotubes with the evanescent field of propagating light in a tapered fiber. Symmetric cross section of the device with the randomly oriented nanotubes guarantees the polarization insensitive operation of the pulse formation. In order to minimize the scattering, the carbon nanotubes are deposited within a designed area around the tapered waist. The demonstrated passively pulsed laser has the repetition rate of 7.3MHz and the pulse width of 829fs.

A Measurement and Modeling Study of Hair Partition of Neutral, Cationic, and Anionic Chemicals.

PubMed

Li, Lingyi; Yang, Senpei; Chen, Tao; Han, Lujia; Lian, Guoping

2018-04-01

Various neutral, cationic, and anionic chemicals contained in hair care products can be absorbed into hair fiber to modulate physicochemical properties such as color, strength, style, and volume. For environmental safety, there is also an interest in understanding hair absorption to wide chemical pollutants. There have been very limited studies on the absorption properties of chemicals into hair. Here, an experimental and modeling study has been carried out for the hair-water partition of a range of neutral, cationic, and anionic chemicals at different pH. The data showed that hair-water partition not only depends on the hydrophobicity of the chemical but also the pH. The partition of cationic chemicals to hair increased with pH, and this is due to their electrostatic interaction with hair increased from repulsion to attraction. For anionic chemicals, their hair-water partition coefficients decreased with increasing pH due to their electrostatic interaction with hair decreased from attraction to repulsion. Increase in pH did not change the partition of neutral chemicals significantly. Based on the new physicochemical insight of the pH effect on hair-water partition, a new quantitative structure property relationship model has been proposed, taking into account of both the hydrophobic interaction and electrostatic interaction of chemical with hair fiber. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Multi-Physics MRI-Based Two-Layer Fluid-Structure Interaction Anisotropic Models of Human Right and Left Ventricles with Different Patch Materials: Cardiac Function Assessment and Mechanical Stress Analysis

PubMed Central

Tang, Dalin; Yang, Chun; Geva, Tal; Gaudette, Glenn; del Nido, Pedro J.

2011-01-01

Multi-physics right and left ventricle (RV/LV) fluid-structure interaction (FSI) models were introduced to perform mechanical stress analysis and evaluate the effect of patch materials on RV function. The FSI models included three different patch materials (Dacron scaffold, treated pericardium, and contracting myocardium), two-layer construction, fiber orientation, and active anisotropic material properties. The models were constructed based on cardiac magnetic resonance (CMR) images acquired from a patient with severe RV dilatation and solved by ADINA. Our results indicate that the patch model with contracting myocardium leads to decreased stress level in the patch area, improved RV function and patch area contractility. PMID:21765559

The role of local interaction mechanics in fiber optic smart structures

NASA Astrophysics Data System (ADS)

Sirkis, J. S.; Dasgupta, A.

1993-04-01

The concept of using 'smart' composite materials/structures with built-in self-diagnostic capabilities for health monitoring involves embedding discrete and/or distributed sensory networks in the host composite material, along with a central and/or distributed artificial intelligence capability for signal processing, data collection, interpretation and diagnostic evaluations. This article concentrates on the sensory functions in 'smart' structure applications and concentrates in particular on optical fiber sensors. Specifically, we present an overview of recent research dealing with the basic mechanics of local interactions between the embedded optical fiber sensors and the surrounding host composite. The term 'local' is defined by length scales on the order of several optical fiber diameters. We examine some generic issues, such as the 'calibration' and 'obtrusivity' of the sensor, and the inherent damage caused by the sensor inclusions to the surrounding host and vice-versa under internal and/or external applied loads. Analytical, numerical and experimental results are presented regarding the influence of local strain concentrations caused by the sensory inclusions on sensor and host performance. The important issues examined are the local mechanistic effects of optical fiber coatings on the behavior of the sensor and the host, and mechanical survivability of optical fibers experiencing quasi-static and time-varying thermomechanical loading.

Record power, ultra-broadband supercontinuum source based on highly GeO₂ doped silica fiber.

PubMed

Jain, D; Sidharthan, R; Moselund, P M; Yoo, S; Ho, D; Bang, O

2016-11-14

We demonstrate highly germania doped fibers for mid-infrared supercontinuum generation. Experiments ensure a highest output power of 1.44 W for a broadest spectrum from 700 nm to 3200 nm and 6.4 W for 800 nm to 2700 nm from these fibers, while being pumped by a broadband Erbium-Ytterbium doped fiber based master oscillator power amplifier. The effect of repetition frequency of pump source and length of germania-doped fiber has also been investigated. Further, germania doped fiber has been pumped by conventional supercontinuum source based on silica photonic crystal fiber supercontinuum source. At low power, a considerable broadening of 200-300 nm was observed. Further broadening of spectrum was limited due to limited power of pump source. Our investigations reveal the unexploited potential of germania doped fiber for mid-infrared supercontinuum generation. These measurements ensure the potential of germania based photonic crystal fiber or a step-index fiber supercontinuum source for high power ultra-broad band emission being by pumped a 1060 nm or a 1550 nm laser source. To the best of our knowledge, this is the record power, ultra-broadband, and all-fiberized supercontinuum light source based on silica and germania fiber ever demonstrated to the date.

A Numerical Solution Routine for Investigating Oxidation-Induced Strength Degradation Mechanisms in SiC/SiC Composites

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2015-01-01

The stress rupture strength of silicon carbide fiber-reinforced silicon carbide (SiCSiC) composites with a boron nitride (BN) fiber coating decreases with time within the intermediate temperature range of 700-950 C. Various theories have been proposed to explain the cause of the time dependent stress rupture strength. Some previous authors have suggested that the observed composite strength behavior is due to the inherent time dependent strength of the fibers, which is caused by the slow growth of flaws within the fibers. Flaw growth is supposedly enabled by oxidation of free carbon at the grain boundaries. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of SiCSiC composites. This is achieved through the development of a numerically-based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time dependent behavior.

Internal-Specific Morphological Analysis of Sciatic Nerve Fibers in a Radiofrequency-Induced Animal Neuropathic Pain Model

PubMed Central

Choi, Samjin; Choi, Hyuk Jai; Cheong, Youjin; Lim, Young-Jin; Park, Hun-Kuk

2013-01-01

This study investigated the reversible effects of pulsed radiofrequency (PRF) treatment at 42°C on the ultrastructural and biological changes in nerve and collagen fibers in the progression of neuropathic pain after rat sciatic nerve injury. Assessments of morphological changes in the extracellular matrices by atomic force microscopy and hematoxylin-eosin, Masson’s trichrome and picrosirius-red staining as well as the expressions of two fibril-forming collagens, types-I and -III, and two inflammatory cytokines, TNF-α and IL-6, were evaluated on day 30 after RF exposure. There were four groups for different RF thermal treatments: no treatment, no current, PRF, and continuous RF (CRF). An RF procedure similar to that used in human clinical trials was used in this study. The CRF treatment at 82°C led to neural and collagen damage by the permanent blockage of sensory nociceptors. The PRF treatment led to excellent performance and high expandability compared to CRF, with effects including slight damage and swelling of myelinated axons, a slightly decreased amount of collagen fibers, swelling of collagen fibril diameters, decreased immunoreactivity of collagen types-I and -III, presence of newly synthesized collagen, and recovery of inflammatory protein immunoreactivity. These evidence-based findings suggest that PRF-based pain relief is responsible for the temporary blockage of nerve signals as well as the preferential destruction of pain-related principal sensory fibers like the Aδ and C fibers. This suggestion can be supported by the interaction between the PRF-induced electromagnetic field and cell membranes; therefore, PRF treatment provides pain relief while allowing retention of some tactile sensation. PMID:24066083

Effect of source of trace minerals in either forage- or by-product-based diets fed to dairy cows: 2. Apparent absorption and retention of minerals.

PubMed

Faulkner, M J; St-Pierre, N R; Weiss, W P

2017-07-01

Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of source of supplemental Cu, Zn, and Mn (sulfates or hydroxy) on apparent absorption of minerals when fed in either a forage- or by-product-based diet. The by-product diets were formulated to have greater concentrations of NDF and lesser concentrations of starch, and specific ingredients were chosen because they were good sources of soluble fiber and β-glucans, which bind trace minerals in nonruminants. We hypothesized that hydroxy trace minerals would interact less with digesta and have greater apparent absorption compared with sulfate minerals, and the difference in apparent absorption would be greater for the by-product diet compared with the forage-based diet. During the 56-d experiment, cows remained on the same fiber treatment but source of supplemental trace mineral was different for each 28-d period; thus, all cows were exposed to both mineral treatments. During each period cows were fed no supplemental Cu, Zn, or Mn for 16 d, followed by 12 d of feeding supplemental minerals from either sulfate or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total Cu, Zn, and Mn dietary concentrations, respectively, were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 for the by-product diets. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Cows consuming the by-product diets had greater Zn (1,863 vs. 1,453 mg/d) and Mn (1,790 vs. 1,588 mg/d) intake compared with cows fed forage diets, but apparent Zn absorption was similar between treatments. Manganese apparent absorption was greater for the by-product diets compared with the forage diets (16 vs. 11%). A fiber by mineral interaction was observed for Cu apparent absorption, as cows fed hydroxy minerals with forage diets had greater apparent absorption compared with cows fed sulfate minerals; however, the opposite was observed with the by-product diets. Source of supplemental trace minerals and type of fiber in diets affected availability of Cu and Mn and should be considered in ration formulation. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A simple immunofluorescence technique for simultaneous visualization of mast cells and nerve fibers reveals selectivity and hair cycle--dependent changes in mast cell--nerve fiber contacts in murine skin.

PubMed

Botchkarev, V A; Eichmüller, S; Peters, E M; Pietsch, P; Johansson, O; Maurer, M; Paus, R

1997-04-01

Close contacts between mast cells (MC) and nerve fibers have previously been demonstrated in normal and inflamed skin by light and electron microscopy. A key step for any study in MC-nerve interactions in situ is to simultaneously visualize both communication partners, preferably with the option of double labelling the nerve fibers. For this purpose, we developed the following triple-staining technique. After paraformaldehyde-picric acid perfusion fixation, cryostat sections of back skin from C57BL/6 mice were incubated with a primary rat monoclonal antibody to substance P (SP), followed by incubation with a secondary goat-anti-rat TRITC-conjugated IgG. A rabbit antiserum to CGRP was then applied, followed by a secondary goat-anti-rabbit FITC-conjugated IgG. MCs were visualized by incubation with AMCA-labelled avidin, or (for a more convenient quantification of close MC-nerve fiber contacts) with a mixture of TRITC- and FITC-labelled avidins. Using this simple, novel covisualization method, we were able to show that MC-nerve associations in mouse skin are, contrary to previous suggestions, highly selective for nerve fiber types, and that these interactions are regulated in a hair cycle-dependent manner: in telogen and early anagen skin, MCs preferentially contacted CGRP-immunoreactive (IR) or SP/CGRP-IR double-labelled nerve fibers. Compared with telogen values, there was a significant increase in the number of close contacts between MCs and tyrosine hydroxylase-IR fibers during late anagen, and between MCs and peptide histidine-methionine-IR and choline acetyl transferase-IR fibers during catagen.

A numerical study of a long flexible fiber in shear flow: dynamics and rheology

NASA Astrophysics Data System (ADS)

Zuk, Pawel; Perazzo, Antonio; Nunes, Janine; Stone, Howard

2017-11-01

Long slender particles can span the whole spectrum of stiffness: from very flexible particles such as globular proteins to extremely rigid particles, e.g. carbon nanotubes or β-amyloid fibers. The behavior of rigid particles is well understood, however there are only few recent experimental reports about long fibers of moderate flexibility. We present a numerical study of a single long flexible fiber in a shear flow. The fiber is simulated as a bead-spring model including hydrodynamic interactions in the Rotne-Prager-Yamakawa approximation. We analyze fiber shape, motion and stress induced in the fluid under the shear flow. We find that all of these properties appear to be related to the characteristic length scale of the kinks formed in the fibers. We present a scaling law for the kink size as a function of shear rate and the fiber parameters and justify it using elastic theory. The study suggests that local properties of a single fiber may condition the behavior of concentrated suspensions.

Nucleation and growth of a bacterial functional amyloid at single fiber resolution

PubMed Central

Feuillie, Cécile; Jonckheere, Wim; Valotteau, Claire; Dufrêne, Yves F.; Remaut, Han

2017-01-01

Curli are functional amyloids produced by proteobacteria like Escherichia coli, as part of the extracellular matrix that holds cells together into biofilms. The molecular events during curli nucleation and fiber extension remain largely unknown. Combining observations from curli amyloidogenesis in bulk solutions with real-time in situ nanoscopic imaging at the single fiber level, we show that curli display polar growth, and detect two kinetic regimes of fiber elongation. Single fibers exhibit stop-and-go dynamics characterized by bursts of steady-state growth alternated with periods of stagnation. At high subunit concentrations fibers show constant, unperturbed burst growth. Curli follow a one-step nucleation process, where monomers contemporaneously fold and oligomerize into minimal fiber units that have growth characteristics identical to the mature fibrils. Kinetic data and interaction studies of curli fibrillation in the presence of the natural inhibitor CsgC show the inhibitor binds curli fibers and predominantly acts at the level of fiber elongation. PMID:28628096

A Solid-State Fibriform Supercapacitor Boosted by Host-Guest Hybridization between the Carbon Nanotube Scaffold and MXene Nanosheets.

PubMed

Yu, Chenyang; Gong, Yujiao; Chen, Ruyi; Zhang, Mingyi; Zhou, Jinyuan; An, Jianing; Lv, Fan; Guo, Shaojun; Sun, Gengzhi

2018-06-25

Fiber-shaped supercapacitors with improved specific capacitance and high rate capability are a promising candidate as power supply for smart textiles. However, the synergistic interaction between conductive filaments and active nanomaterials remains a crucial challenge, especially when hydrothermal or electrochemical deposition is used to produce a core (fiber)-shell (active materials) fibrous structure. On the other hand, although 2D pseudocapacitive materials, e.g., Ti 3 C 2 T x (MXene), have demonstrated high volumetric capacitance, high electrical conductivity, and hydrophilic characteristics, MXene-based electrodes normally suffer from poor rate capability owing to the sheet restacking especially when the loading level is high and solid-state gel is used as electrolyte. Herein, by hosting MXene nanosheets (Ti 3 C 2 T x ) in the corridor of a scrolled carbon nanotube (CNT) scaffold, a MXene/CNT fiber with helical structure is successfully fabricated. These features offer open spaces for rapid ion diffusion and guarantee fast electron transport. The solid-state supercapacitor based on such hybrid fibers with gel electrolyte coating exhibits a volumetric capacitance of 22.7 F cm -3 at 0.1 A cm -3 with capacitance retention of 84% at current density of 1.0 A cm -3 (19.1 F cm -3 ), improved volumetric energy density of 2.55 mWh cm -3 at the power density of 45.9 mW cm -3 , and excellent mechanical robustness. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectral wings of the fiber supercontinuum and the dark-bright soliton interaction.

PubMed

Milián, C; Marest, T; Kudlinski, A; Skryabin, D V

2017-05-01

We present experimental and numerical data on the supercontinuum generation in an optical fiber pumped in the normal dispersion range where the seeded dark and the spontaneously generated bright solitons contribute to the spectral broadening. We report the dispersive radiation arising from the interaction of the bright and dark solitons. This radiation consists of the two weak dispersing pulses that continuously shift their frequencies and shape the short and long wavelength wings of the supercontinuum spectrum.

The effect of age and carbohydrate and protein sources on digestibility, fecal microbiota, fermentation products, fecal IgA, and immunological blood parameters in dogs.

PubMed

Maria, A P J; Ayane, L; Putarov, T C; Loureiro, B A; Neto, B P; Casagrande, M F; Gomes, M O S; Glória, M B A; Carciofi, A C

2017-06-01

The present study compared the effects of diets formulated with fibers of different fermentability and protein sources of animal or vegetable origins on old and adult dogs. The experiment was organized in a 3 (diets) × 2 (ages) factorial arrangement, totaling 6 treatments. Thirty-six Beagle dogs were used (18 old dogs [10.2 ± 1.0 yr] and 18 young adult dogs [2.6 ± 0.9 yr]), with 6 dogs per treatment. Three diets with similar compositions were used: a nonfermentable insoluble fiber source (sugarcane fiber) and chicken byproduct meal (nonfermentable fiber [NFF] diet), a fermentable fiber source (beet pulp) and chicken byproduct meal (fermentable fiber [FF] diet), and soybean meal as a protein and fiber source (soybean meal [SM] diet). Data were evaluated using the MIXED procedure and considering the effects and interactions of block, animal, diets, and age. Means were compared using Tukey's test ( < 0.05). Age × diet interactions were evaluated when < 0.1. Old dogs had a reduced coefficient of total tract apparent digestibility of DM, which was explained by the age and diet interaction of CP and fat digestibility that was lower for old than for adult dogs fed the FF diet ( < 0.05). The SM diet obtained higher DM, OM, CP, and fiber digestibility compared with the NFF diet ( < 0.05). The feces of dogs fed the NFF diet had increased DM content ( < 0.05). The short-chain fatty acids (SCFA) did not change by age group and were higher for dogs fed the FF and SM diets compared with dogs fed the NFF diet ( < 0.05). An age and diet interaction was observed for lactate and was increased in the feces of old dogs compared with adult dogs fed the FF diet ( < 0.05). Fecal putrescine, cadaverine, and spermine were increased for old dogs compared with adult dogs ( < 0.05), and the spermidine fecal concentration was increased for dogs fed the SM diet regardless of age ( < 0.05). Old dogs had reduced peripheral T and B lymphocytes ( < 0.05). An age and diet interaction was observed for fecal IgA ( < 0.001). Adult dogs fed the SM diet had increased IgA in feces compared with animals fed the NFF and FF diets ( < 0.05). However, for old dogs, both the FF and SM diets induced increased IgA compared with the NFF diet ( < 0.05). In conclusion, beet pulp may reduce digestibility and induce increased lactate in the feces of old dogs. The protein and oligosaccharides of soybean meal are digestible by dogs, induce the production of SCFA and spermidine, and increase fecal IgA. Old dogs had increased putrecine, cadaverine, and spermine fecal concentrations.

An experimentally based analytical model for the shear capacity of FRP-strengthened reinforced concrete beams

NASA Astrophysics Data System (ADS)

Pellegrino, C.; Modena, C.

2008-05-01

This paper deals with the shear strengthening of Reinforced Concrete (RC) flexural members with externally bonded Fiber-Reinforced Polymers (FRPs). The interaction between an external FRP and an internal transverse steel reinforcement is not considered in actual code recommendations, but it strongly influences the efficiency of the shear strengthening rehabilitation technique and, as a consequence, the computation of interacting contributions to the nominal shear strength of beams. This circumstance is also discussed on the basis of the results of an experimental investigation of rectangular RC beams strengthened in shear with "U-jacketed" carbon FRP sheets. Based on experimental results of the present and other investigations, a new analytical model for describing the shear capacity of RC beams strengthened according to the most common schemes (side-bonded and "U-jacketed"), taking into account the interaction between steel and FRP shear strength contributions, is proposed.

Cascaded interactions between Raman induced solitons and dispersive waves in photonic crystal fibers at the advanced stage of supercontinuum generation.

PubMed

Driben, Rodislav; Mitschke, Fedor; Zhavoronkov, Nickolai

2010-12-06

The complex mechanism of multiple interactions between solitary and dispersive waves at the advanced stage of supercontinuum generation in photonic crystal fiber is studied in experiment and numerical simulations. Injection of high power negatively chirped pulses near zero dispersion frequency results in an effective soliton fission process with multiple interactions between red shifted Raman solitons and dispersive waves. These interactions may result in relative acceleration of solitons with further collisions between them of quasi-elastic or quasi-plastic kinds. In the spectral domain these processes result in enhancement of certain wavelength regions within the spectrum or development of a new significant band at the long wavelength side of the spectrum.

Interfacial and capillary phenomena in solidification processing of metal-matrix composites

NASA Technical Reports Server (NTRS)

Asthana, R.; Tewari, S. N.

1993-01-01

Chemical and hydrodynamic aspects of wetting and interfacial phenomena during the solidification processing of metal-matrix composites are reviewed. Significant experimental results on fiber-matrix interactions and wetting under equilibrium and non-equilibrium conditions in composites of engineering interest have been compiled, based on a survey of the recent literature. Finally, certain aspects of wetting relevant to stir-casting and infiltration processing of composites are discussed.

NDE Research At Nondestructive Measurement Science At NASA Langley

DTIC Science & Technology

1989-06-01

our staff include: ultrasonics, nonlinear acoustics , thermal acoustics and diffusion, magnetics , fiber optics, and x-ray tomography . We have a...based on the simple assumption that acoustic waves interact with the sample and reveal "important" properties . In practice, such assumptions have...between the acoustic wave and the media. The most useful models can generally be inverted to determine the physical properties or geometry of the

Production and application of chemical fibers with special properties for manufacturing composite materials and goods of different usage

NASA Technical Reports Server (NTRS)

Levit, R.

1993-01-01

The development of modern technologies demands the creation of new nonmetallic, fibrous materials with specific properties. The fibers and materials developed by NII 'Chimvolokno', St. Petersburg, can be divided into two groups. The first group includes heat-resistant fibers, fire-resistant fibers, thermotropic fibers, fibers for medical application, and textile structures. The second group contains refractory fibers, chemoresistant and antifriction fibers, fibers on the basis of polyvinyl alcohol, microfiltering films, and paperlike and nonwoven materials. In cooperation with NPO 'Chimvolokno' MYTITSHI, we developed and started producing heat-resistant high-strength fibers on the base of polyhetarearilin and aromatic polyimides (SVM and terlon); heat-resistant fibers on the base of polyemede (aramid); fire-retardant fibers (togilen); chemoresistant and antifriction fibers on the basis of homo and copolymers of polytetrafluoroethylene (polyfen and ftorin); and water soluble, acetylated, and high-modulus fibers from polyvinyl alcohol (vylen). Separate reports will deal with textile structures and thermotropic fibers, as well as with medical fibers. One of the groups of refractory fibers carbon fibers (CF) and the corresponding paperlike nonwoven materials are discussed in detail. Also, composite materials (CM) and their base, which is the subject of the author's research since 1968, is discussed.

Real-Time Analysis of Specific Protein-DNA Interactions with Surface Plasmon Resonance

PubMed Central

Ritzefeld, Markus; Sewald, Norbert

2012-01-01

Several proteins, like transcription factors, bind to certain DNA sequences, thereby regulating biochemical pathways that determine the fate of the corresponding cell. Due to these key positions, it is indispensable to analyze protein-DNA interactions and to identify their mode of action. Surface plasmon resonance is a label-free method that facilitates the elucidation of real-time kinetics of biomolecular interactions. In this article, we focus on this biosensor-based method and provide a detailed guide how SPR can be utilized to study binding of proteins to oligonucleotides. After a description of the physical phenomenon and the instrumental realization including fiber-optic-based SPR and SPR imaging, we will continue with a survey of immobilization methods. Subsequently, we will focus on the optimization of the experiment, expose pitfalls, and introduce how data should be analyzed and published. Finally, we summarize several interesting publications of the last decades dealing with protein-DNA and RNA interaction analysis by SPR. PMID:22500214

Profilin is required for viral morphogenesis, syncytium formation, and cell-specific stress fiber induction by respiratory syncytial virus

PubMed Central

Bitko, Vira; Oldenburg, Anja; Garmon, Nicolle E; Barik, Sailen

2003-01-01

Background Actin is required for the gene expression and morphogenesis of respiratory syncytial virus (RSV), a clinically important Pneumovirus of the Paramyxoviridae family. In HEp-2 cells, RSV infection also induces actin stress fibers, which may be important in the immunopathology of the RSV disease. Profilin, a major regulator of actin polymerization, stimulates viral transcription in vitro. Thus, we tested the role of profilin in RSV growth and RSV-actin interactions in cultured cells (ex vivo). Results We tested three cell lines: HEp-2 (human), A549 (human), and L2 (rat). In all three, RSV grew well and produced fused cells (syncytium), and two RSV proteins, namely, the phosphoprotein P and the nucleocapsid protein N, associated with profilin. In contrast, induction of actin stress fibers by RSV occurred in HEp-2 and L2 cells, but not in A549. Knockdown of profilin by RNA interference had a small effect on viral macromolecule synthesis but strongly inhibited maturation of progeny virions, cell fusion, and induction of stress fibers. Conclusions Profilin plays a cardinal role in RSV-mediated cell fusion and viral maturation. In contrast, interaction of profilin with the viral transcriptional proteins P and N may only nominally activate viral RNA-dependent RNA polymerase. Stress fiber formation is a cell-specific response to infection, requiring profilin and perhaps other signaling molecules that are absent in certain cell lines. Stress fibers per se play no role in RSV replication in cell culture. Clearly, the cellular architecture controls multiple steps of host-RSV interaction, some of which are regulated by profilin. PMID:12740026

Microscopic mechanism of amino silicone oil modification and modification effect with different amino group contents based on molecular dynamics simulation

NASA Astrophysics Data System (ADS)

He, Liping; Li, Wenjun; Chen, Dachuan; Yuan, Jianmin; Lu, Gang; Zhou, Dianwu

2018-05-01

The microscopic mechanism of amino silicone oil (ASO) modification of natural fiber was investigated for the first time using molecular dynamics (MD) simulation at the atomic and molecular levels. The MD simulation results indicated that the ASO molecular interacted with the cellulose molecular within the natural fiber, mainly by intermolecular forces of Nsbnd Hsbnd O and Osbnd Hsbnd N hydrogen bonds and the molecular chain of ASO absorbed onto the natural fiber in a selective orientation, i.e., the hydrophobic alkyl groups (sbnd CnH2n+1) project outward and the polar amino groups (sbnd NH2) point to the surface of natural fiber. Consequently, the ASO modification changed the surface characteristic of natural fiber from hydrophilic to hydrophobic. Furthermore, the modification effects of the ASO modification layer with different amino group contents (m:n ratio) were also evaluated in this study by calculating the binding energy between the ASO modifier and natural fiber, and the cohesive energy density and free volume of the ASO modification layer. The results showed that the binding energy reached a maximum when the m:n ratio of ASO was of 8:4, suggesting that a good bonding strength was achieved at this m:n ratio. It was also found that the cohesive energy density enhanced with the increase in the amino group content, and the higher the cohesive energy density, the easier the formation of the ASO modification layer. However, the fraction free volume decreased with the increase in the amino group content. This is good for improving the water-proof property of natural fiber. The present work can provide an effective method for predicting the modification effects and designing the optimized m:n ratio of ASO modification.

Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks.

PubMed

Walugembe, M; Hsieh, J C F; Koszewski, N J; Lamont, S J; Persia, M E; Rothschild, M F

2015-10-01

This experiment was conducted to evaluate the effects of feeding dietary fiber on cecal short-chain fatty acid (SCFA) concentration and cecal microbiota of broiler and laying-hen chicks. The lower fiber diet was based on corn-soybean meal (SBM) and the higher fiber diet was formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran to contain 60.0 g/kg of both DDGS and wheat bran from 1 to 12 d and 80.0 g/kg of both DDGS and wheat bran from 13 to 21 d. Diets were formulated to meet or exceed NRC nutrient requirements. Broiler and laying-hen chicks were randomly assigned to the high and low fiber diets with 11 replicates of 8 chicks for each of the 4 treatments. One cecum from 3 chicks was collected from each replicate: one cecum underwent SCFA concentration analysis, one underwent bacterial DNA isolation for terminal restriction fragment length polymorphism (TRFLP), and the third cecum was used for metagenomics analyses. There were interactions between bird line and dietary fiber for acetic acid (P = 0.04) and total SCFA (P = 0.04) concentration. There was higher concentration of acetic acid (P = 0.02) and propionic acid (P < 0.01) in broiler chicks compared to laying-hen chicks. TRFLP analysis showed that cecal microbiota varied due to diet (P = 0.02) and chicken line (P = 0.03). Metagenomics analyses identified differences in the relative abundance of Helicobacter pullorum and Megamonas hypermegale and the genera Enterobacteriaceae, Campylobacter, Faecalibacterium, and Bacteroides in different treatment groups. These results provide insights into the effect of dietary fiber on SCFA concentration and modulation of cecal microbiota in broiler and laying-hen chicks. © 2015 Poultry Science Association Inc.

High-density fiber optic biosensor arrays

NASA Astrophysics Data System (ADS)

Epstein, Jason R.; Walt, David R.

2002-02-01

Novel approaches are required to coordinate the immense amounts of information derived from diverse genomes. This concept has influenced the expanded role of high-throughput DNA detection and analysis in the biological sciences. A high-density fiber optic DNA biosensor was developed consisting of oligonucleotide-functionalized, 3.1 mm diameter microspheres deposited into the etched wells on the distal face of a 500 micrometers imaging fiber bundle. Imaging fiber bundles containing thousands of optical fibers, each associated with a unique oligonucleotide probe sequence, were the foundation for an optically connected, individually addressable DNA detection platform. Different oligonucleotide-functionalized microspheres were combined in a stock solution, and randomly dispersed into the etched wells. Microsphere positions were registered from optical dyes incorporated onto the microspheres. The distribution process provided an inherent redundancy that increases the signal-to-noise ratio as the square root of the number of sensors examined. The representative amount of each probe-type in the array was dependent on their initial stock solution concentration, and as other sequences of interest arise, new microsphere elements can be added to arrays without altering the existing detection capabilities. The oligonucleotide probe sequences hybridize to fluorescently-labeled, complementary DNA target solutions. Fiber optic DNA microarray research has included DNA-protein interaction profiles, microbial strain differentiation, non-labeled target interrogation with molecular beacons, and single cell-based assays. This biosensor array is proficient in DNA detection linked to specific disease states, single nucleotide polymorphism (SNP's) discrimination, and gene expression analysis. This array platform permits multiple detection formats, provides smaller feature sizes, and enables sensor design flexibility. High-density fiber optic microarray biosensors provide a fast, reversible format with the detection limit of a few hundred molecules.

A double-taper optical fiber-based radiation wave other than evanescent wave in all-fiber immunofluorescence biosensor for quantitative detection of Escherichia coli O157:H7.

PubMed

Zhang, Zhonghuan; Hua, Fei; Liu, Ting; Zhao, Yong; Li, Jun; Yang, Ruifu; Yang, Changxi; Zhou, Lei

2014-01-01

Cylindrical or taper-and-cylinder combination optical fiber probe based on evanescent wave has been widely used for immunofluorescence biosensor to detect various analytes. In this study, in contrast to the contradiction between penetration depth and analyte diameter of optical fiber probe-based evanescent wave, we demonstrate that double-taper optical fiber used in a radiation wave-based all-fiber immunofluorescence biosensor (RWAIB) can detect micron-scale analytes using Escherichia coli O157:H7 as representative target. Finite-difference time-domain method was used to compare the properties of evanescent wave and radiation wave (RW). Ray-tracing model was formulated to optimize the taper geometry of the probe. Based on a commercial multi-mode fiber, a double-taper probe was fabricated and connected with biosensor through a "ferrule connector" optical fiber connector. The RWAIB configuration was accomplished using commercial multi-mode fibers and fiber-based devices according to the "all-fiber" method. The standard sample tests revealed that the sensitivity of the proposed technique for E. coli O157:H7 detection was 10(3) cfu · mL(-1). Quantitation could be achieved within the concentration range of 10(3) cfu · mL(-1) to 107 cfu · mL(-1). No non-specific recognition to ten kinds of food-borne pathogens was observed. The results demonstrated that based on the double-taper optical fiber RWAIB can be used for the quantitative detection of micron-scale targets, and RW sensing is an alternative for traditional evanescent wave sensing during the fabrication of fiber-optic biosensors.

Nanofiber quantum photonics

NASA Astrophysics Data System (ADS)

Nayak, Kali P.; Sadgrove, Mark; Yalla, Ramachandrarao; Le Kien, Fam; Hakuta, Kohzo

2018-07-01

Recent advances in the coherent control of single quanta of light, photons, is a topic of prime interest, and is discussed under the banner of quantum photonics. In the last decade, the subwavelength diameter waist of a tapered optical fiber, referred to as an optical nanofiber, has opened promising new avenues in the field of quantum optics, paving the way toward a versatile platform for quantum photonics applications. The key feature of the technique is that the optical field can be tightly confined in the transverse direction while propagating over long distances as a guided mode and enabling strong interaction with the surrounding medium in the evanescent region. This feature has led to surprising possibilities to manipulate single atoms and fiber-guided photons, e.g. the efficient channeling of emission from single atoms and solid-state quantum emitters into the fiber-guided modes, high optical depth with a few atoms around the nanofiber, trapping atoms around a nanofiber, and atomic memories for fiber-guided photons. Furthermore, implementing a moderate longitudinal confinement in nanofiber cavities has enabled the strong coupling regime of cavity quantum electrodynamics to be reached, and the long-range dipole–dipole interaction between quantum emitters mediated by the nanofiber offers a platform for quantum nonlinear optics with an ensemble of atoms. In addition, the presence of a longitudinal component of the guided field has led to unique capabilities for chiral light–matter interactions on nanofibers. In this article, we review the key developments of the nanofiber technology toward a vision for quantum photonics on an all-fiber interface.

Nonlinear waveguide optics and photonic crystal fibers.

PubMed

Knight, J C; Skryabin, D V

2007-11-12

Focus Serial: Frontiers of Nonlinear Optics

Self-starting picosecond optical pulse source using stimulated Brillouin scattering in an optical fiber.

PubMed

Tang, W W; Shu, C

2005-02-21

We demonstrate a regeneratively mode-locked optical pulse source at about 10 GHz using an optoelectronic oscillator constructed with an electro-absorption modulator integrated distributed feedback laser diode. The 10 GHz RF component is derived from the interaction between the pump wave and the backscattered, frequency-downshifted Stokes wave resulted from stimulated Brillouin scattering in an optical fiber. The component serves as a modulation source for the 1556 nm laser diode without the need for any electrical or optical RF filter to perform the frequency extraction. Dispersion-compensated fiber, dispersion-shifted fiber, and standard single-mode fiber have been used respectively to generate optical pulses at variable repetition rates.

Fiber Optics: Deregulate and Deploy.

ERIC Educational Resources Information Center

Suwinski, Jan H.

1993-01-01

Describes fiber optic technology, explains its use in education and commercial settings, and recommends regulations and legislation that will speed its use to create broadband information networks. Topics discussed include distance learning; interactive video; costs; and the roles of policy makers, lawmakers, public advocacy groups, and consumers.…

Super-resolution microscopy reveals LINC complex recruitment at nuclear indentation sites.

PubMed

Versaevel, Marie; Braquenier, Jean-Baptiste; Riaz, Maryam; Grevesse, Thomas; Lantoine, Joséphine; Gabriele, Sylvain

2014-12-08

Increasing evidences show that the actin cytoskeleton is a key parameter of the nuclear remodeling process in response to the modifications of cellular morphology. However, detailed information on the interaction between the actin cytoskeleton and the nuclear lamina was still lacking. We addressed this question by constraining endothelial cells on rectangular fibronectin-coated micropatterns and then using Structured Illumination Microscopy (SIM) to observe the interactions between actin stress fibers, nuclear lamina and LINC complexes at a super-resolution scale. Our results show that tension in apical actin stress fibers leads to deep nuclear indentations that significantly deform the nuclear lamina. Interestingly, indented nuclear zones are characterized by a local enrichment of LINC complexes, which anchor apical actin fibers to the nuclear lamina. Moreover, our findings indicate that nuclear indentations induce the formation of segregated domains of condensed chromatin. However, nuclear indentations and condensed chromatin domains are not irreversible processes and both can relax in absence of tension in apical actin stress fibers.

Hedgehog signaling and laminin play unique and synergistic roles in muscle development.

PubMed

Peterson, Matthew T; Henry, Clarissa A

2010-03-01

Hedgehog (Hh) signaling and laminin-111, a basement membrane protein, are required for early muscle development. Hh signaling specifies different populations of muscle fibers and laminin-111 is critical for early muscle morphogenesis. However, additional requirements for Hh signaling and laminin during later phases of muscle development are not known. Furthermore, interactions between Hh signaling and laminin in this context are unknown. We used laminin gamma1 mutant zebrafish and cyclopamine to block Hh signal transduction separately and in combination to investigate their functions and interactions. We found that both Hh signaling and laminin are required for normal myosin chain expression. In addition, Hh signaling and laminin act synergistically during fast-twitch fiber elongation: fast muscle cells do not elongate in embryos deficient for both Hh signaling and laminin. Finally, we present evidence that suggests that Hh signaling is indirectly required via slow fiber specification for recovery of fast fiber elongation in laminin gamma1 mutant embryos. Copyright (c) 2010 Wiley-Liss, Inc.

Laser absorption of carbon fiber reinforced polymer with randomly distributed carbon fibers

NASA Astrophysics Data System (ADS)

Hu, Jun; Xu, Hebing; Li, Chao

2018-03-01

Laser processing of carbon fiber reinforced polymer (CFRP) is a non-traditional machining method which has many prospective applications. The laser absorption characteristics of CFRP are analyzed in this paper. A ray tracing model describing the interaction of the laser spot with CFRP is established. The material model contains randomly distributed carbon fibers which are generated using an improved carbon fiber placement method. It was found that CFRP has good laser absorption due to multiple reflections of the light rays in the material’s microstructure. The randomly distributed carbon fibers make the absorptivity of the light rays change randomly in the laser spot. Meanwhile, the average absorptivity fluctuation is obvious during movement of the laser. The experimental measurements agree well with the values predicted by the ray tracing model.

Biaxial (Tension-Torsion) Testing of an Oxide/Oxide Ceramic Matrix Composite

DTIC Science & Technology

2013-03-01

estimation algorithms and constants . . . . . . . . . . . . . 61 4.27 Biaxial (tension-torsion) load spreadsheet with independent axial load and torsion...through the composite and provides the main load - bearing capability. The interaction of the two (or more) phases takes place in the interface. The...transfer loads between fibers[15]. The fiber-to-fiber load transfer mechanism provided by the matrix plays a major role in the load - bearing properties of the

Ultrasonication-enhanced gelation properties of a versatile amphiphilic formamidine-based gelator exhibiting both organogelation and hydrogelation abilities.

PubMed

Bachl, Jürgen; Sampedro, Diego; Mayr, Judith; Díaz Díaz, David

2017-08-30

We describe the preparation of a novel amphiphilic gelator built from a formamidine core, which is able to form a variety of physical organogels and hydrogels at concentrations ranging from 15 to 150 mg mL -1 . Interestingly, ultrasound treatment of isotropic solutions (i.e., gel-precursor) resulted in a remarkable enhancement of the gelation kinetics as well as the gelation scope and characteristic gel properties (e.g., critical gelation concentration, gel-to-sol transition temperature, viscoelastic moduli) in comparison to the heating-cooling protocol typically used to obtain supramolecular gels. Thermoreversibility, thixotropy, injectability and multistimuli responsiveness are some of the most relevant functionalities of these gels. Electron microscopy imaging revealed the formation of entangled networks made of fibers of nanometer diameters and micrometer lengths, with different morphological features depending on the solvent. Insights into the driving forces for molecular aggregations were obtained from FTIR, NMR, PXRD and computational studies. The results suggest a major stabilization of the fibers through additive N-HO hydrogen bonds, in combination with hydrophobic interactions, over π-π stacking interactions.

Erbium/ytterbium co-doped double clad fiber amplifier, its applications and effects in fiber optic communication systems

NASA Astrophysics Data System (ADS)

Dua, Puneit

Increased demand for larger bandwidth and longer inter-amplifiers distances translates to higher power budgets for fiber optic communication systems in order to overcome large splitting losses and achieve acceptable signal-to-noise ratios. Due to their unique design ytterbium sensitized erbium doped, double clad fiber amplifiers; offer significant increase in the output powers that can be obtained. In this thesis we investigate, a one-stage, high power erbium and ytterbium co-doped double clad fiber amplifier (DCFA) with output power of 1.4W, designed and built in our lab. Experimental demonstration and numerical simulation techniques have been used to systematically study the applications of such an amplifier and the effects of incorporating it in various fiber optic communication systems. Amplitude modulated subcarrier multiplexed (AM-SCM) CATV distribution experiment has been performed to verify the feasibility of using this amplifier in an analog/digital communication system. The applications of the amplifier as a Fabry-Perot and ring fiber laser with an all-fiber cavity, a broadband supercontinuum source and for generation of high power, short pulses at 5GHz have been experimentally demonstrated. A variety of observable nonlinear effects occur due to the high intensity of the optical powers confined in micron-sized cores of the fibers, this thesis explores in detail some of these effects caused by using the high power Er/Yb double clad fiber amplifier. A fiber optic based analog/digital CATV system experiences composite second order (CSO) distortion due to the interaction between the gain tilt---the variation of gain with wavelength, of the doped fiber amplifier and the wavelength chirp of the directly modulated semiconductor laser. Gain tilt of the Er/Yb co-doped fiber amplifier has been experimentally measured and its contribution to the CSO of the system calculated. Theoretical analysis of a wavelength division multiplexed system with closely spaced channels has been carried out to show that crosstalk can occur due to the four-wave mixing products generated inside the high power Er/Yb DCFA. A model for parametric amplification due to four-wave mixing has been developed and used to analyze its application for short pulse generation and high speed optical time division multiplexing.

Fiber inhalability and head deposition in rats and humans. ...

EPA Pesticide Factsheets

Due to their dimensions and long durability, inhaled asbestos fibers clear slowly from lung airways. Retained fibers may injure the epithelium, interact with macrophages, or translocate to the interstitium to result in various respiratory diseases. Therefore, calculations of fiber inhalability, deposition, and retention in respiratory tract regions of both rats and humans are crucial, both to assess the health risk of fiber exposures and to facilitate inferences from rat inhalation studies. Rat inhalation experiments are underway at the EPA and NIEHS. A model of fiber inhalability and initial deposition in the human and rat nasal cavity was developed. Existing models for particles were extended to fibers by replacing particle diameter with an equivalent fiber diameter. Since fiber inhalability into the respiratory tract and deposition in the extra thoracic airways depended mainly on its inertia, equivalent impaction diameters were derived and substituted in expressions for spherical particle diameter to determine fiber inhalability and nasal losses. Fiber impaction diameter depended strongly on its orientation in the air. Highest inhalability was obtained when fibers were aligned perpendicular to the flow streamlines in the inhaled air. However, detailed calculations of fiber transport in slow moving air such as that in the atmosphere and in lung airways showed that fibers stayed primarily aligned (parallel) to the flow. Therefore, for inhalability calculations,

Modeling the formation of cell-matrix adhesions on a single 3D matrix fiber.

PubMed

Escribano, J; Sánchez, M T; García-Aznar, J M

2015-11-07

Cell-matrix adhesions are crucial in different biological processes like tissue morphogenesis, cell motility, and extracellular matrix remodeling. These interactions that link cell cytoskeleton and matrix fibers are built through protein clutches, generally known as adhesion complexes. The adhesion formation process has been deeply studied in two-dimensional (2D) cases; however, the knowledge is limited for three-dimensional (3D) cases. In this work, we simulate different local extracellular matrix properties in order to unravel the fundamental mechanisms that regulate the formation of cell-matrix adhesions in 3D. We aim to study the mechanical interaction of these biological structures through a three dimensional discrete approach, reproducing the transmission pattern force between the cytoskeleton and a single extracellular matrix fiber. This numerical model provides a discrete analysis of the proteins involved including spatial distribution, interaction between them, and study of the different phenomena, such as protein clutches unbinding or protein unfolding. Copyright © 2015 Elsevier Ltd. All rights reserved.

Seeing More by Showing Less: Orientation-Dependent Transparency Rendering for Fiber Tractography Visualization.

PubMed

Tax, Chantal M W; Chamberland, Maxime; van Stralen, Marijn; Viergever, Max A; Whittingstall, Kevin; Fortin, David; Descoteaux, Maxime; Leemans, Alexander

2015-01-01

Fiber tractography plays an important role in exploring the architectural organization of fiber trajectories, both in fundamental neuroscience and in clinical applications. With the advent of diffusion MRI (dMRI) approaches that can also model "crossing fibers", the complexity of the fiber network as reconstructed with tractography has increased tremendously. Many pathways interdigitate and overlap, which hampers an unequivocal 3D visualization of the network and impedes an efficient study of its organization. We propose a novel fiber tractography visualization approach that interactively and selectively adapts the transparency rendering of fiber trajectories as a function of their orientation to enhance the visibility of the spatial context. More specifically, pathways that are oriented (locally or globally) along a user-specified opacity axis can be made more transparent or opaque. This substantially improves the 3D visualization of the fiber network and the exploration of tissue configurations that would otherwise be largely covered by other pathways. We present examples of fiber bundle extraction and neurosurgical planning cases where the added benefit of our new visualization scheme is demonstrated over conventional fiber visualization approaches.

Highly efficient and completely flexible fiber-shaped dye-sensitized solar cell based on TiO2 nanotube array

NASA Astrophysics Data System (ADS)

Lv, Zhibin; Yu, Jiefeng; Wu, Hongwei; Shang, Jian; Wang, Dan; Hou, Shaocong; Fu, Yongping; Wu, Kai; Zou, Dechun

2012-02-01

A type of highly efficient completely flexible fiber-shaped solar cell based on TiO2 nanotube array is successfully prepared. Under air mass 1.5G (100 mW cm-2) illumination conditions, the photoelectric conversion efficiency of the solar cell approaches 7%, the highest among all fiber-shaped cells based on TiO2 nanotube arrays and the first completely flexible fiber-shaped DSSC. The fiber-shaped solar cell demonstrates good flexibility, which makes it suitable for modularization using weaving technologies.A type of highly efficient completely flexible fiber-shaped solar cell based on TiO2 nanotube array is successfully prepared. Under air mass 1.5G (100 mW cm-2) illumination conditions, the photoelectric conversion efficiency of the solar cell approaches 7%, the highest among all fiber-shaped cells based on TiO2 nanotube arrays and the first completely flexible fiber-shaped DSSC. The fiber-shaped solar cell demonstrates good flexibility, which makes it suitable for modularization using weaving technologies. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11532h

An atom interferometer inside a hollow-core photonic crystal fiber

PubMed Central

Xin, Mingjie; Leong, Wui Seng; Chen, Zilong; Lan, Shau-Yu

2018-01-01

Coherent interactions between electromagnetic and matter waves lie at the heart of quantum science and technology. However, the diffraction nature of light has limited the scalability of many atom-light–based quantum systems. We use the optical fields in a hollow-core photonic crystal fiber to spatially split, reflect, and recombine a coherent superposition state of free-falling 85Rb atoms to realize an inertia-sensitive atom interferometer. The interferometer operates over a diffraction-free distance, and the contrasts and phase shifts at different distances agree within one standard error. The integration of phase coherent photonic and quantum systems here shows great promise to advance the capability of atom interferometers in the field of precision measurement and quantum sensing with miniature design of apparatus and high efficiency of laser power consumption. PMID:29372180

Stretchable Fiber Supercapacitors with High Volumetric Performance Based on Buckled MnO2 /Oxidized Carbon Nanotube Fiber Electrodes.

PubMed

Li, Mingyang; Zu, Mei; Yu, Jinshan; Cheng, Haifeng; Li, Qingwen

2017-03-01

A stretchable fiber supercapacitor (SC) based on buckled MnO 2 /oxidized carbon nanotube (CNT) fiber electrode is fabricated by a simple prestraining-then-buckling method. The prepared stretchable fiber SC has a specific volumetric capacitance up to 409.4 F cm -3 , which is 33 times that of the pristine CNT fiber based SC, and shows the outstanding stability and repeatability in performance as a stretchable SC. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel liquid-filled microstructured polymer optical fiber as bio-sensing platform for Raman spectroscopy

NASA Astrophysics Data System (ADS)

Azkune, Mikel; Arrospide, Eneko; Berganza, Amaia; Bikandi, Iñaki; Aldabaldetreku, Gotzon; Durana, Gaizka; Zubia, Joseba

2018-02-01

One approach to overcome the poor efficiency of the Raman scattering as a sensing platform is to use microstructured optical fibers. In this type of fibers with a longitudinal holey structure, light interacts with the target sample, which is confined in the core, giving rise to a light intensity increase of the obtained Raman spectra due to the large interaction distances and the guidance of the scattered light. In this work, we present an ad-hoc fabricated liquid-core microstructured polymer optical fiber (LC-mPOF) as a bio-sensing platform for Raman Spectroscopy. Arising from an initial simulation stage, we create the desired preform using the drilling technique and afterwards the LC-mPOF is drawn in our fiber drawing tower. The guiding mechanism of the light through the solution has a major importance, being a key factor to obtain appreciable enhancements in Raman scattering. In this case, in order to optimize the Raman scattering signal of dissolved glucose (target molecule), we have filled the core with an aqueous solution of the target molecule, enabling in this way the modified total internal reflection mechanism. Experimental Raman measurements are performed and results are discussed.

Interface stresses in fiber-reinforced materials with regular fiber arrangements

NASA Astrophysics Data System (ADS)

Mueller, W. H.; Schmauder, S.

The theory of linear elasticity is used here to analyze the stresses inside and at the surface of fiber-reinforced composites. Plane strain, plane stress, and generalized plane strain are analyzed using the shell model and the BHE model and are numerically studied using finite element analysis. Interface stresses are shown to depend weakly on Poisson's ratio. For equal values of the ratio, generalized plane strain and plane strain results are identical. For small volume fractions up to 40 vol pct of fibers, the shell and the BHE models predict the interface stresses very well over a wide range of elastic mismatches and for different fiber arrangements. At higher volume fractions the stresses are influenced by interactions with neighboring fibers. Introducing an external pressure into the shell model allows the prediction of interface stresses in real composite with isolated or regularly arranged fibers.

The Role of Viscosity and Fermentability of Dietary Fibers on Satiety- and Adiposity-Related Hormones in Rats

PubMed Central

Schroeder, Natalia; Marquart, Len F.; Gallaher, Daniel D.

2013-01-01

Dietary fiber may contribute to satiety. This study examined the effect of two dietary fiber characteristics, small intestinal contents viscosity and large intestinal fermentability, on satiety-and adiposity-related hormones in rats. Diets contained fiber sources that were non-viscous, somewhat viscous, or highly viscous, and either highly fermentable or non-fermentable, in a 2 × 3 factorial design. In the fed state (2 h postprandial), rats fed non-fermentable fibers had significantly greater plasma GLP-1 concentration than fermentable fibers. In the fasted state, among non-fermentable fibers, viscosity had no effect on GLP-1 concentration. However, among fermentable fibers, greater viscosity reduced GLP-1 concentration. Plasma peptide tyrosine tyrosine (PYY) concentrations in the fasted state were not influenced by the fermentability of the fiber overall, however animals consuming a fructooligosaccharide greater PYY concentration. In both the fed and fasted states, rats fed non-fermentable fibers had a significantly lower plasma ghrelin concentration than rats fed fermentable fibers. In the fasted state, rats fed non-fermentable fibers had a significantly lower plasma leptin concentration than rats fed fermentable fibers. Thus, fermentability and viscosity of dietary fiber interacted in complex ways to influence satiety- and adiposity-related plasma hormone concentrations. However, the results suggest that highly viscous, non-fermentable fibers may limit weight gain and reduce adiposity and non-fermentable fibers, regardless of viscosity, may promote meal termination. PMID:23749206

The role of viscosity and fermentability of dietary fibers on satiety- and adiposity-related hormones in rats.

PubMed

Schroeder, Natalia; Marquart, Len F; Gallaher, Daniel D

2013-06-07

Dietary fiber may contribute to satiety. This study examined the effect of two dietary fiber characteristics, small intestinal contents viscosity and large intestinal fermentability, on satiety-and adiposity-related hormones in rats. Diets contained fiber sources that were non-viscous, somewhat viscous, or highly viscous, and either highly fermentable or non-fermentable, in a 2 × 3 factorial design. In the fed state (2 h postprandial), rats fed non-fermentable fibers had significantly greater plasma GLP-1 concentration than fermentable fibers. In the fasted state, among non-fermentable fibers, viscosity had no effect on GLP-1 concentration. However, among fermentable fibers, greater viscosity reduced GLP-1 concentration. Plasma peptide tyrosine tyrosine (PYY) concentrations in the fasted state were not influenced by the fermentability of the fiber overall, however animals consuming a fructooligosaccharide greater PYY concentration. In both the fed and fasted states, rats fed non-fermentable fibers had a significantly lower plasma ghrelin concentration than rats fed fermentable fibers. In the fasted state, rats fed non-fermentable fibers had a significantly lower plasma leptin concentration than rats fed fermentable fibers. Thus, fermentability and viscosity of dietary fiber interacted in complex ways to influence satiety- and adiposity-related plasma hormone concentrations. However, the results suggest that highly viscous, non-fermentable fibers may limit weight gain and reduce adiposity and non-fermentable fibers, regardless of viscosity, may promote meal termination.

Influence of the addition of soy product and wheat fiber on rheological, textural, and other quality characteristics of pizza.

PubMed

Glicerina, Virginia; Balestra, Federica; Capozzi, Francesco; Dalla Rosa, Marco; Romani, Santina

2017-11-17

The effect of partial replacement of wheat flour with soy paste and wheat fiber on rheological, textural, physicochemical, and organoleptic characteristics of an enriched pizza base (E) was investigated in comparison with those of a control pizza base (C). New ingredients (e.g., enriched cooked ham, whey cheese, and tomato sauce realized using food industry by-products) were also used in E pizza topping to further increase its nutritional properties. Enriched dough was developed first at a laboratory level. Large and small deformation, moisture, leavening activity, and metabolic heat were tested. On the final product, produced at the industrial level, textural, color, sensory, and nutritional analyses were performed. Preliminary rheological analysis was essential to evaluate the suitability of the new pizza to be processed at industrial level. Both pizza dough samples showed a solid elastic-like behavior; however, the addition of soy and fiber increased moisture content of E pizza, due to the water binding ability of soy protein and to the effect of fibers that also decreased E dough elasticity. No differences in extensibility between the two samples were observed, whereas significantly lower values of resistance to extension and dough force were shown in sample E. These differences were likely due to the presence of soy that interfere with gluten formation and to the dietary fibers that interact with water. Ingredients used in E pizza improved its nutritional quality increasing dietary fibers and protein, and decreasing saturated fatty acids and cholesterol content, which contributed to decrease energy value, in terms of kilocalorie reduction. In this work, the effects of using new ingredients (e.g., soy paste, wheat fiber) on the rheological, textural, physicochemical, nutritional, and organoleptic characteristics of an enriched pizza type were investigated both at laboratory and industrial levels. The new pizza provides a product that combines solid technological performances, in terms of rheological properties and dough elasticity, with improved and balanced nutritional quality, thanks also to the ingredients used in the topping. Results demonstrate the possibility of obtaining new pizza products characterized by nutritional and sensorial properties tailored for different group of consumers. © 2017 Wiley Periodicals, Inc.

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

PubMed Central

Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K.

2013-01-01

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency. PMID:23963358

Microwave photonics systems based on whispering-gallery-mode resonators.

PubMed

Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K

2013-08-05

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

Effect of laser frequency noise on fiber-optic frequency reference distribution

NASA Technical Reports Server (NTRS)

Logan, R. T., Jr.; Lutes, G. F.; Maleki, L.

1989-01-01

The effect of the linewidth of a single longitude-mode laser on the frequency stability of a frequency reference transmitted over a single-mode optical fiber is analyzed. The interaction of the random laser frequency deviations with the dispersion of the optical fiber is considered to determine theoretically the effect on the Allan deviation (square root of the Allan variance) of the transmitted frequency reference. It is shown that the magnitude of this effect may determine the limit of the ultimate stability possible for frequency reference transmission on optical fiber, but is not a serious limitation to present system performance.

Microbend fiber-optic chemical sensor

DOEpatents

Weiss, Jonathan D.

2002-01-01

A microbend fiber-optic chemical sensor for detecting chemicals in a sample, and a method for its use, is disclosed. The sensor comprises at least one optical fiber having a microbend section (a section of small undulations in its axis), for transmitting and receiving light. In transmission, light guided through the microbend section scatters out of the fiber core and interacts, either directly or indirectly, with the chemical in the sample, inducing fluorescence radiation. Fluorescence radiation is scattered back into the microbend section and returned to an optical detector for determining characteristics of the fluorescence radiation quantifying the presence of a specific chemical.

All-optical control of group velocity dispersion in tellurite photonic crystal fibers.

PubMed

Liu, Lai; Tian, Qijun; Liao, Meisong; Zhao, Dan; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

2012-12-15

We demonstrate all-optical control of group velocity dispersion (GVD) via optical Kerr effect in highly nonlinear tellurite photonic crystal fibers. The redshift of the zero-dispersion wavelength is over 307 nm, measured by soliton self-frequency shift cancellation, when the pump peak power of a 1.56 μm femtosecond fiber laser is increased to 11.6 kW. The all-optical control of GVD not only offers a new platform for constructing all-optical-control photonic devices but also promises a new class of experiments in nonlinear fiber optics and light-matter interactions.

A comparison of the bromination dynamics of pitch-based and vapor-grown graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, J. R.

1986-01-01

The electrical resistance of pitch based P-100 fibers and experimental organic vapor grown fibers was recorded in-situ during bromination and subsequent exposure to ambient laboratory air. The results indicate that the bromination and debromination reactions proceed much slower for vapor grown fibers than for pitch based. While this may be due in part to the larger diameter of the vapor grown fibers, the majority of the effect can probably be attributed to the differences in graphene plane orientation between the fiber types. Although the reactions are slower in the vapor grown than in the pitch based fibers, the extent of reaction as measured by the change in electrical resistance is essentially the same, with comparable (or larger) decreases in resistivity. The bromination reaction proceeds with one or more plateaus in the resistance versus time curves, which suggests staging and strengthens the argument that these fibers produce true intercalation compounds.

Deformation behavior of carbon-fiber reinforced shape-memory-polymer composites used for deployable structures (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lan, Xin; Liu, Liwu; Li, Fengfeng; Pan, Chengtong; Liu, Yanju; Leng, Jinsong

2017-04-01

Shape memory polymers (SMPs) are a new type of smart material, they perform large reversible deformation with a certain external stimulus (e.g., heat and electricity). The properties (e.g., stiffness, strength and other mechanically static or quasi-static load-bearing capacity) are primarily considered for conventional resin-based composite materials which are mainly used for structural materials. By contrast, the mechanical actuating performance with finite deformation is considered for the shape memory polymers and their composites which can be used for both structural materials and functional materials. For shape memory polymers and their composites, the performance of active deformation is expected to further promote the development in smart active deformation structures, such as deployable space structures and morphing wing aircraft. The shape memory polymer composites (SMPCs) are also one type of High Strain Composite (HSC). The space deployable structures based on carbon fiber reinforced shape memory polymer composites (SMPCs) show great prospects. Considering the problems that SMPCs are difficult to meet the practical applications in space deployable structures in the recent ten years, this paper aims to research the mechanics of deformation, actuation and failure of SMPCs. In the overall view of the shape memory polymer material's nonlinearity (nonlinearity and stress softening in the process of pre-deformation and recovery, relaxation in storage process, irreversible deformation), by the multiple verifications among theory, finite element and experiments, one obtains the deformation and actuation mechanism for the process of "pre-deformation, energy storage and actuation" and its non-fracture constraint domain. Then, the parameters of SMPCs will be optimized. Theoretical analysis is realized by the strain energy function, additionally considering the interaction strain energy between the fiber and the matrix. For the common resin-based or soft-material-based composites under pure bending deformation, we expect to uniformly explain the whole process of buckling occurrence, evolution and finally failure, especially for the early evolution characteristics of fiber microbuckling inside the microstructures. The research results are meaningful for the practical applications for SMPC deployable structures in space. Considering the deformation mechanisms of SMPCs, the local post-microbuckling is required for the unidirectional fiber reinforced composite materials, at the conditions of its large geometrical deflection. The cross section of SMPC is divided into three areas: non-buckling stretching area, non-buckling compressive area, and buckling compressive area. Three variables are considered: critical buckling position, and neutral plane, the fiber buckling half-wavelength. Considering the condition of the small strain and large displacement, the strain energy expression of the SMP/fiber system was derived, which contains two types, e.g., strain energy of SMP and fiber. According to the minimum energy principle, the expression for all key parameters were derived, including the critical buckling curvature, neutral plane position, the buckling half-wavelength, fiber buckling amplitude, and strain.

Adaptive fiber optics collimator based on flexible hinges.

PubMed

Zhi, Dong; Ma, Yanxing; Ma, Pengfei; Si, Lei; Wang, Xiaolin; Zhou, Pu

2014-08-20

In this manuscript, we present a new design for an adaptive fiber optics collimator (AFOC) based on flexible hinges by using piezoelectric stacks actuators for X-Y displacement. Different from traditional AFOC, the new structure is based on flexible hinges to drive the fiber end cap instead of naked fiber. We fabricated a real AFOC based on flexible hinges, and the end cap's deviation and resonance frequency of the device were measured. Experimental results show that this new AFOC can provide fast control of tip-tilt deviation of the laser beam emitting from the end cap. As a result, the fiber end cap can support much higher power than naked fiber, which makes the new structure ideal for tip-tilt controlling in a high-power fiber laser system.

Bam35 tectivirus intraviral interaction map unveils new function and localization of phage ORFan proteins.

PubMed

Berjón-Otero, Mónica; Lechuga, Ana; Mehla, Jitender; Uetz, Peter; Salas, Margarita; Redrejo-Rodríguez, Modesto

2017-07-26

Tectiviridae comprises a group of tail-less, icosahedral, membrane-containing bacteriophages that can be divided into two groups by their hosts, either Gram-negative or Gram-positive bacteria. While the first group is composed of PRD1 and nearly identical well characterized lytic viruses, the second one includes more variable temperate phages, like GIL16 or Bam35, whose hosts are Bacillus cereus and related Gram-positive bacteria.In the genome of Bam35, nearly half of the 32 annotated open reading frames (ORFs) have no homologs in databases (ORFans), being putative proteins of unknown function, which hinders the understanding of their biology. With the aim of increasing the knowledge of the viral proteome, we carried out a comprehensive yeast two-hybrid analysis among all the putative proteins encoded by the Bam35 genome. The resulting protein interactome comprises 76 unique interactions among 24 proteins, of which 12 have an unknown function. These results suggested that the P17 protein is the minor capsid protein of Bam35 and P24 is the penton protein, being the latter also supported by iterative threading protein modeling. Moreover, the inner membrane transglycosylase protein P26 could have an additional structural role. We also detected interactions involving non-structural proteins, such as the DNA binding protein P1 and the genome terminal protein (P4), which was confirmed by co-immunoprecipitation of recombinant proteins. Altogether, our results provide a functional view of the Bam35 viral proteome, with a focus on the composition and organization of the viral particle. IMPORTANCE Tail-less viruses of the family Tectiviridae can infect commensal and pathogenic Gram-positive and Gram-negative bacteria. Moreover, they have been proposed to be at the evolutionary origin of several groups of large eukaryotic DNA viruses and self-replicating plasmids. However, due to their ancient origin and complex diversity, many tectiviral proteins are ORFans of unknown function.Comprehensive protein-protein interaction (PPI) analysis among viral proteins can eventually disclose biological mechanisms and thus provide new insights into protein function unattainable by studying proteins one by one. Here we comprehensively describe intraviral PPIs among tectivirus Bam35 proteins using multi-vector yeast two-hybrid screening that was further supported by co-immunoprecipitation assays and protein structural models. This approach allowed us to propose new functions for known proteins and hypothesize on the biological role localization within the viral particle of some viral ORFan proteins that will be helpful for understanding the biology of Gram-positive tectivirus. Copyright © 2017 American Society for Microbiology.

Bam35 Tectivirus Intraviral Interaction Map Unveils New Function and Localization of Phage ORFan Proteins

PubMed Central

Berjón-Otero, Mónica; Lechuga, Ana; Mehla, Jitender; Uetz, Peter

2017-01-01

ABSTRACT The family Tectiviridae comprises a group of tailless, icosahedral, membrane-containing bacteriophages that can be divided into two groups by their hosts, either Gram-negative or Gram-positive bacteria. While the first group is composed of PRD1 and nearly identical well-characterized lytic viruses, the second one includes more variable temperate phages, like GIL16 or Bam35, whose hosts are Bacillus cereus and related Gram-positive bacteria. In the genome of Bam35, nearly half of the 32 annotated open reading frames (ORFs) have no homologs in databases (ORFans), being putative proteins of unknown function, which hinders the understanding of their biology. With the aim of increasing knowledge about the viral proteome, we carried out a comprehensive yeast two-hybrid analysis of all the putative proteins encoded by the Bam35 genome. The resulting protein interactome comprised 76 unique interactions among 24 proteins, of which 12 have an unknown function. These results suggest that the P17 protein is the minor capsid protein of Bam35 and P24 is the penton protein, with the latter finding also being supported by iterative threading protein modeling. Moreover, the inner membrane transglycosylase protein P26 could have an additional structural role. We also detected interactions involving nonstructural proteins, such as the DNA-binding protein P1 and the genome terminal protein (P4), which was confirmed by coimmunoprecipitation of recombinant proteins. Altogether, our results provide a functional view of the Bam35 viral proteome, with a focus on the composition and organization of the viral particle. IMPORTANCE Tailless viruses of the family Tectiviridae can infect commensal and pathogenic Gram-positive and Gram-negative bacteria. Moreover, they have been proposed to be at the evolutionary origin of several groups of large eukaryotic DNA viruses and self-replicating plasmids. However, due to their ancient origin and complex diversity, many tectiviral proteins are ORFans of unknown function. Comprehensive protein-protein interaction (PPI) analysis of viral proteins can eventually disclose biological mechanisms and thus provide new insights into protein function unattainable by studying proteins one by one. Here we comprehensively describe intraviral PPIs among tectivirus Bam35 proteins determined using multivector yeast two-hybrid screening, and these PPIs were further supported by the results of coimmunoprecipitation assays and protein structural models. This approach allowed us to propose new functions for known proteins and hypothesize about the biological role of the localization of some viral ORFan proteins within the viral particle that will be helpful for understanding the biology of tectiviruses infecting Gram-positive bacteria. PMID:28747494

Development of Al2O3 fiber-reinforced Al2O3-based ceramics.

PubMed

Tanimoto, Yasuhiro; Nemoto, Kimiya

2004-09-01

The purpose of this study was to use a tape casting technique to develop an Al2O3 fiber-reinforced Al2O3-based ceramic material (Al2O3-fiber/Al2O3 composite) into a new type of dental ceramic. The Al2O3-based ceramic used a matrix consisting of 60 wt% Al2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of Al2O3-fiber/Al2O3 composite (in which uniaxially aligned Al2O3 fibers were infiltrated with the Al2O3-based matrix) were fabricated continuously using tape casting technique with a doctor blade system. Multilayer preforms of Al2O3-fiber/Al2O3 composite sheets were then sintered at a maximum temperature of 1000 degrees C under an atmospheric pressure in a furnace. The results showed that the shrinkage and bending properties of Al2O3-fiber/Al2O3 composite exceeded those of unreinforced Al2O3--hence demonstrating the positive effects of fiber reinforcement. In conclusion, the tape casting technique has been utilized to successfully develop a new type of dental ceramic material.

Stretchable All-Gel-State Fiber-Shaped Supercapacitors Enabled by Macromolecularly Interconnected 3D Graphene/Nanostructured Conductive Polymer Hydrogels.

PubMed

Li, Panpan; Jin, Zhaoyu; Peng, Lele; Zhao, Fei; Xiao, Dan; Jin, Yong; Yu, Guihua

2018-05-01

Nanostructured conductive polymer hydrogels (CPHs) have been extensively applied in energy storage owing to their advantageous features, such as excellent electrochemical activity and relatively high electrical conductivity, yet the fabrication of self-standing and flexible electrode-based CPHs is still hampered by their limited mechanical properties. Herein, macromolecularly interconnected 3D graphene/nanostructured CPH is synthesized via self-assembly of CPHs and graphene oxide macrostructures. The 3D hybrid hydrogel shows uniform interconnectivity and enhanced mechanical properties due to the strong macromolecular interaction between the CPHs and graphene, thus greatly reducing aggregation in the fiber-shaping process. A proof-of-concept all-gel-state fibrous supercapacitor based on the 3D polyaniline/graphene hydrogel is fabricated to demonstrate the outstanding flexibility and mouldability, as well as superior electrochemical properties enabled by this 3D hybrid hydrogel design. The proposed device can achieve a large strain (up to ≈40%), and deliver a remarkable volumetric energy density of 8.80 mWh cm -3 (at power density of 30.77 mW cm -3 ), outperforming many fiber-shaped supercapacitors reported previously. The all-hydrogel design opens up opportunities in the fabrication of next-generation wearable and portable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Search for technological advantages and commercial success in sensor applications: lessons of industrial trials for fiber multianalyzer technology

NASA Astrophysics Data System (ADS)

McMillan, Norman D.; Baker, M.; O'Neill, M.; Smith, Stuart; Augousti, Andreas T.; Mason, Julian; Ryan, Bernard; Ryan, R. A.

1999-01-01

The multianalyzer is a powerful amplitude modulated fiber optic sensor which is perhaps quite typical of so many sensor innovations in that it is a technology looking for an application. Consequently, a series of collaborations with fruit juice, brewing, distilling, biotechnology and polymer industries were made with the objective of identifying potential applications of the multianalyzer. An assessment of these interactions is made for each of the industrial fields explored, by giving for each, just one positive result from the work. The results are then critically assessed. While these studies have illustrated the universal nature of the technology, in every case, lessons have been drawn of a general nature. This experience in particular underlined the difficulty in acceptance of a fiber based technology in industrial process monitoring, against the backdrop of the conservative practice of industry with long established instrumentation. The hard won experience of this product development has shown the vital important of technologists understanding the difference between the marketing concepts of features, benefits and advantages. Three categories of conclusions are drawn, the technical, the commercial, and finally, conclusions drawn from generalizations of the project by the Kingston partners based on their own independent experience in sensor development involving industrial and medical collaborations.

Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

NASA Technical Reports Server (NTRS)

Tan, Seng; Zhou, Jian-guo

2013-01-01

Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

Interaction of Aβ(1-42) amyloids with lipids promotes "off-pathway" oligomerization and membrane damage.

PubMed

Henry, Sarah; Vignaud, Hélène; Bobo, Claude; Decossas, Marion; Lambert, Oliver; Harte, Etienne; Alves, Isabel D; Cullin, Christophe; Lecomte, Sophie

2015-03-09

The toxicity of amyloids, as Aβ(1-42) involved in Alzheimer disease, is a subject under intense scrutiny. Many studies link their toxicity to the existence of various intermediate structures prior to fiber formation and/or their specific interaction with membranes. In this study we focused on the interaction between membrane models and Aβ(1-42) peptides and variants (L34T, mG37C) produced in E. coli and purified in monomeric form. We evaluated the interaction of a toxic stable oligomeric form (oG37C) with membranes as comparison. Using various biophysical techniques as fluorescence and plasmon waveguide resonance, we clearly established that the oG37C interacts strongly with membranes leading to its disruption. All the studied peptides destabilized liposomes and accumulated slowly on the membrane (rate constant 0.02 min(-1)). Only the oG37C exhibited a particular pattern of interaction, comprising two steps: the initial binding followed by membrane reorganization. Cryo-TEM was used to visualize the peptide effect on liposome morphologies. Both oG37C and mG37C lead to PG membrane fragmentation. The PG membrane promotes peptide oligomerization, implicated in membrane disruption. WT (Aβ(1-42)) also perturbs liposome organization with membrane deformation rather than disruption. For all the peptides studied, their interaction with the membranes changes their fibrillization process, with less fibers and more small aggregates being formed. These studies allowed to establish, a correlation between toxicity, fiber formation, and membrane disruption.

Preparation and electrochemical characterization of ionic-conducting lithium lanthanum titanate oxide/polyacrylonitrile submicron composite fiber-based lithium-ion battery separators

NASA Astrophysics Data System (ADS)

Liang, Yinzheng; Ji, Liwen; Guo, Bingkun; Lin, Zhan; Yao, Yingfang; Li, Ying; Alcoutlabi, Mataz; Qiu, Yiping; Zhang, Xiangwu

Lithium lanthanum titanate oxide (LLTO)/polyacrylonitrile (PAN) submicron composite fiber-based membranes were prepared by electrospinning dispersions of LLTO ceramic particles in PAN solutions. These ionic-conducting LLTO/PAN composite fiber-based membranes can be directly used as lithium-ion battery separators due to their unique porous structure. Ionic conductivities were evaluated after soaking the electrospun LLTO/PAN composite fiber-based membranes in a liquid electrolyte, 1 M lithium hexafluorophosphate (LiPF 6) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1:1 vol). It was found that, among membranes with various LLTO contents, 15 wt.% LLTO/PAN composite fiber-based membranes provided the highest ionic conductivity, 1.95 × 10 -3 S cm -1. Compared with pure PAN fiber membranes, LLTO/PAN composite fiber-based membranes had greater liquid electrolyte uptake, higher electrochemical stability window, and lower interfacial resistance with lithium. In addition, lithium//1 M LiPF 6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes as the separator exhibited high discharge specific capacity of 162 mAh g -1 and good cycling performance at 0.2 C rate at room temperature.

A Novel Low-Power-Consumption All-Fiber-Optic Anemometer with Simple System Design.

PubMed

Zhang, Yang; Wang, Fang; Duan, Zhihui; Liu, Zexu; Liu, Zigeng; Wu, Zhenlin; Gu, Yiying; Sun, Changsen; Peng, Wei

2017-09-14

A compact and low-power consuming fiber-optic anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is presented. TFBG as a near infrared in-fiber sensing element is able to excite a number of cladding modes and radiation modes in the fiber and effectively couple light in the core to interact with the fiber surrounding mediums. It is an ideal in-fiber device used in a fiber hot-wire anemometer (HWA) as both coupling and sensing elements to simplify the sensing head structure. The fabricated TFBG was immobilized with an SWCNT film on the fiber surface. SWCNTs, a kind of innovative nanomaterial, were utilized as light-heat conversion medium instead of traditional metallic materials, due to its excellent infrared light absorption ability and competitive thermal conductivity. When the SWCNT film strongly absorbs the light in the fiber, the sensor head can be heated and form a "hot wire". As the sensor is put into wind field, the wind will take away the heat on the sensor resulting in a temperature variation that is then accurately measured by the TFBG. Benefited from the high coupling and absorption efficiency, the heating and sensing light source was shared with only one broadband light source (BBS) without any extra pumping laser complicating the system. This not only significantly reduces power consumption, but also simplifies the whole sensing system with lower cost. In experiments, the key parameters of the sensor, such as the film thickness and the inherent angle of the TFBG, were fully investigated. It was demonstrated that, under a very low BBS input power of 9.87 mW, a 0.100 nm wavelength response can still be detected as the wind speed changed from 0 to 2 m/s. In addition, the sensitivity was found to be -0.0346 nm/(m/s) under the wind speed of 1 m/s. The proposed simple and low-power-consumption wind speed sensing system exhibits promising potential for future long-term remote monitoring and on-chip sensing in practical applications.

In vivo effects of metal ions on conformation and mechanical performance of silkworm silks.

PubMed

Wang, Xin; Li, Yi; Liu, Qingsong; Chen, Quanmei; Xia, Qingyou; Zhao, Ping

2017-03-01

The mechanism of silk fiber formation is of particular interest. Although in vitro evidence has shown that metal ions affect conformational transitions of silks, the in vivo effects of metal ions on silk conformations and mechanical performance are still unclear. This study explored the effects of metal ions on silk conformations and mechanical properties of silk fibers by adding K + and Cu 2+ into the silk fibroin solutions or injecting them into the silkworms. Aimed by CD analysis, FTIR analysis, and mechanical testing, the conformational and mechanical changes of the silks were estimated. By using BION Web Server, the interactions of K + and N-terminal of silk fibroin were also simulated. We presented that K + and Cu 2+ induced the conformational transitions of silk fibroin by forming β-sheet structures. Moreover, the mechanical parameters of silk fibers, such as strength, toughness and Young's modulus, were also improved after K + or Cu 2+ injection. Using BION Web Server, we found that potassium ions may have strong electrostatic interactions with the negatively charged residues. We suggest that K + and Cu 2+ play crucial roles in the conformation and mechanical performances of silks and they are involved in the silk fiber formation in vivo. Our results are helpful for clarifying the mechanism of silk fiber formation, and provide insights for modifying the mechanical properties of silk fibers. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication and characterization of polycaprolactone-graphene powder electrospun nanofibers

NASA Astrophysics Data System (ADS)

Ginestra, Paola; Ghazinejad, Maziar; Madou, Marc; Ceretti, Elisabetta

2016-09-01

Porous fibrous membranes having multiple scales geometries and tailored properties have become attractive microfabrication materials in recent years. Due to the feasibility of incorporating graphene in electrospun nanofibres and the growing interest on these nanomaterials, the present paper focuses on the electrospinning of Poly (ɛ-Caprolactone) (PCL) solutions in the presence of different amounts of Graphene platelets. Electrospinning is a process whereby ultrafine fibers are formed in a high-voltage electrostatic field. The morphological appearance, fiber diameter, and structure of PCL nanofibers produced by the electrospinning process were studied in the presence of different concentration of graphene. Moreover, the effect of a successful incorporation of graphene nanosheets into PCL polymer nanofibers was analyzed. Scanning electron microscope micrographs of the electrospun fibers showed that the average fiber diameter increases in the presence of graphene. Furthermore, the intrinsic properties developed due to the interactions of graphene and PCL improved the mechanical properties of the nanofibers. The results reveal the effect of various graphene concentrations on PCL and the strong interfacial interactions between the graphene platelets phase and the polymer matrix. The functional complexity of the electrospun fibers provides significant advantages over other techniques and shows the promise of these fibers for many applications including air/water filters, sensors, organic solar cells, smart textiles, biocompatible scaffolds for tissue engineering and load-bearing applications. Optimizing deposition efficiency, however, is a necessary milestone for the widespread use of this technique.

Fiber Optic-Based Refractive Index Sensing at INESC Porto

PubMed Central

Jorge, Pedro A. S.; Silva, Susana O.; Gouveia, Carlos; Tafulo, Paula; Coelho, Luis; Caldas, Paulo; Viegas, Diana; Rego, Gaspar; Baptista, José M.; Santos, José L.; Frazão, Orlando

2012-01-01

A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers. PMID:22969405

Hydrodynamic and elastic interactions of sedimenting flexible fibers

NASA Astrophysics Data System (ADS)

Ekiel-Jezewska, Maria L.; Bukowicki, Marek

2017-11-01

Dynamics of flexible micro and nano filaments in fluids is intensively investigated in many laboratories, with a perspective of numerous applications in biology, medicine or modern technology. In the literature, different theoretical models of elastic interactions between flexible fiber segments are applied. The task of this work is to examine the impact of a chosen elastic model on the dynamics of fibers settling in a viscous fluid under low Reynolds number. To this goal, we construct two trumbbells, each made of three beads connected by springs and with a bending resistance, and we describe hydrodynamic interactions of the beads in terms of the Rotne-Prager mobility tensors. Using the harmonic bending potential, and coupling it to the spring potential by the Young's modulus, we find simple benchmark solutions: stable stationary configurations of a single elastic trumbbell and a fast horizontal attraction of two elastic trumbbells towards a periodic long-lasting orbit. We show that for sufficiently large bending angles, other models of bending interactions can lead to qualitatively and quantitatively different spurious effects. We also demonstrate examples of essential differences between the dynamics of elastic dumbbells and trumbbells. This work was supported in part by Narodowe Centrum Nauki under Grant No. 2014/15/B/ST8/04359.

Experimental phase-space-based optical amplification of scar modes.

PubMed

Michel, C; Tascu, S; Doya, V; Aschiéri, P; Blanc, W; Legrand, O; Mortessagne, F

2012-04-01

Wave billiards which are chaotic in the geometrical limit are known to support nongeneric spatially localized modes called scar modes. The interaction of the scar modes with gain has been recently investigated in optics in microcavity lasers and vertical-cavity surface-emitting lasers. Exploiting the localization properties of scar modes in their wave-analogous phase-space representation, we report experimental results of scar mode selection by gain in a doped D-shaped optical fiber.

Optical microfiber-based photonic crystal cavity

NASA Astrophysics Data System (ADS)

Yu, Yang; Sun, Yi-zhi; Andrews, Steve; Li, Zhi-yuan; Ding, Wei

2016-01-01

Using a focused ion beam milling technique, we fabricate broad stop band (∼10% wide) photonic crystal (PhC) cavities in adiabatically-tapered silica fibers. Abrupt structural design of PhC mirrors efficiently reduces radiation loss, increasing the cavity finesse to ∼7.5. Further experiments and simulations verify that the remaining loss is mainly due to Ga ion implantation. Such a microfiber PhC cavity probably has potentials in many light-matter interaction applications.

Development of Fiber-Based Laser Systems for LISA

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2010-01-01

We present efforts on fiber-based laser systems for the LISA mission at the NASA Goddard Space Flight Center. A fiber-based system has the advantage of higher robustness against external disturbances and easier implementation of redundancies. For a master oscillator, we are developing a ring fiber laser and evaluating two commercial products, a DBR linear fiber laser and a planar-waveguide external cavity diode laser. They all have comparable performance to a traditional NPRO at LISA band. We are also performing reliability tests of a 2-W Yb fiber amplifier and radiation tests of fiber laser/amplifier components. We describe our progress to date and discuss the path to a working LISA laser system design.