Entire Fiber Research Articles

P.479 - Morphological spectrum of RYR1 recessive myopathies: Clinical and genetic correlation.

RYR recessive myopathy is a rare disease manifesting with a wide spectrum of clinical and morphological phenotypes. Here we present the histological and ultrastructural analysis of muscle biopsy from 50 patients with genetically confirmed RYR1 recessive myopathy. Up to 30% presented classical core myopathy, 12% core and rods, 8% type1 uniformity, 2% congenital fiber type disproportion and almost 50% showed a characteristic variable combination of sarcomeric disorganization, protein accumulation, type1 predominance and nuclear internalization. In the latter group, in addition, some patients presented rods, or/and areas of disorganization with targetoid appearance. Ultrastructural study has been performed in 35 patients. Regardless of histological findings, by electron microscopy all but two patients presented various degree of disorganization ranging from z-line duplication or smearing to larger areas of myofibrillar disorganization including more than 50 sarcomeres and occupying almost the entire fiber diameter. Frequently, different kinds of these areas were detected in the same biopsy. Pure disorganization was observed in one third of patients, whereas 25% showed also small areas of sarcomeric disorganization containing short elements resembling minirods rising from z-line fragments, 20% contained also subsarcolemmal rods outside sarcomeric disorganization areas and in 10% rods where detected only in atrophic fibers. In conclusion RyR1 recessive myopathy seems to manifest as continuum spectrum of histological and ultrastructural alterations in which myofibrillar disorganization ranges from very mild to severe. Moreover, levels of RyR1 expression in muscle biopsies have been assessed by Western Blot in several patients and its pertinence with genetics background, clinical severity and morphological findings has been investigated.

Microstructure and tensile properties of various varieties of rice husk.

Rice husk is a complex hierarchical assembly of hollow fibers consisting of cellulose, hemicellulose and lignin. In addition, it can also contain pectin and significant amounts of silica. Rice husk can be used in diverse applications and generally in the form of rice husk powder. This study aimed to investigate the structural features and mechanical properties of various varieties of whole rice husks. Rice husk consists of three sections: epidermis, sub-hypodermis and hypodermis. The thickness of these layers, the diameters of the hollow fibers and the wall thickness vary with the variety of rice husk. The elastic modulus is typically between 0.3 and 2.6 GPa, and the ultimate tensile strength varies from 19 to 135 MPa depending on the variety of rice husk. Rice husk has a unique hierarchical structure in which the fibers exhibit a staggered perpendicular arrangement and the entire fiber sections are covered by an external shell. The tensile properties vary with the variety of rice husk. The wide range in these tensile properties may be attributed to the size and orientation of the fibers. © 2017 Society of Chemical Industry.

Astrocytes follow ganglion cell axons to establish an angiogenic template during retinal development.

Immature astrocytes and blood vessels enter the developing mammalian retina at the optic nerve head and migrate peripherally to colonize the entire retinal nerve fiber layer (RNFL). Retinal vascularization is arrested in retinopathy of prematurity (ROP), a major cause of bilateral blindness in children. Despite their importance in normal development and ROP, the factors that control vascularization of the retina remain poorly understood. Because astrocytes form a reticular network that appears to provide a substrate for migrating endothelial cells, they have long been proposed to guide angiogenesis. However, whether astrocytes do in fact impose a spatial pattern on developing vessels remains unclear, and how astrocytes themselves are guided is unknown. Here we explore the cellular mechanisms that ensure complete retinal coverage by astrocytes and blood vessels in mouse. We find that migrating astrocytes associate closely with the axons of retinal ganglion cells (RGCs), their neighbors in the RNFL. Analysis of Robo1; Robo2 mutants, in which RGC axon guidance is disrupted, and Math5 (Atoh7) mutants, which lack RGCs, reveals that RGCs provide directional information to migrating astrocytes that sets them on a centrifugal trajectory. Without this guidance, astrocytes exhibit polarization defects, fail to colonize the peripheral retina, and display abnormal fine-scale spatial patterning. Furthermore, using cell type-specific chemical-genetic tools to selectively ablate astrocytes, we show that the astrocyte template is required for angiogenesis and vessel patterning. Our results are consistent with a model whereby RGC axons guide formation of an astrocytic network that subsequently directs vessel development.

Microscopy Study of Morphology of Electrospun Fiber-MOF Composites with Secondary Growth

ABSTRACTMicroscopy studies were performed over a series of metal-organic-framework (MOF) imbedded electrospun fibers. Analysis of as-spun fibers revealed five different MOF particle-fiber imbedded morphologies including complete particle encasement, over-filled, surface-bound, welded, and agglomerated. To mitigate issues with fiber breakup during electrospinning (ES) due to MOF particle incorporation, secondary growth method was used. Secondary growth was performed on both Matrimid and polysulfone fibers impregnated with a MOF, ZIF-8, in either water or methanol solvents. Results show that when water was used, crystal formation was limited to formation on the top layer of the fiber mat due to hydrophobicity. When methanol was used in place of water, MOF crystal growth occurred in a patchwise manner, where crystals grow across fibers and span the entire fiber mat. From this work, it was determined that successful secondary growth of MOF imbedded electrospun fibers can be accomplished when particles are either highly exposed along the fiber surface for adequate exposure to solvent, or the solvent used promotes reactant penetration into the polymer to allow access to the seeded MOF crystals.

The biology and genetics of curly hair.

Hair fibres show wide diversity across and within all human populations, suggesting that hair fibre form and colour have been subject to much adaptive pressure over thousands of years. All human hair fibres typically have the same basic structure. However, the three-dimensional shape of the entire fibre varies considerably depending on ethnicity and geography, with examples from very straight hair with no rotational turn about the long axis, to the tightly sprung coils of African races. The creation of the highly complex biomaterials in hair follicle and how these confer mechanical functions on the fibre so formed is a topic that remains relatively unexplained thus far. We review the current understanding on how hair fibres are formed into a nonlinear coiled form and which genetic and biological factors are thought to be responsible for hair shape. We report on a new GWAS comparing low and high curl individuals in South Africa, revealing strong links to polymorphic variation in trichohyalin, a copper transporter protein CUTC and the inner root sheath component keratin 74. This builds onto the growing knowledge base describing the control of curly hair formation.

Opto-mechanical inter-core cross-talk in multi-core fibers

Optical fibers containing multiple cores are widely regarded as the leading solution to the optical communications capacity crunch. The most prevalent paradigm for the design and employment of multi-core fibers relies on the suppression of direct coupling of optical power among cores. The cores, however, remain mechanically coupled. Inter-core, opto-mechanical cross-talk, among cores that are otherwise optically isolated from one another, is shown in this work for the first time, to the best of our knowledge. Light in one core stimulates guided acoustic modes of the entire fiber cladding. These modes, in turn, induce refractive index perturbations that extend across to other cores. Unlike corresponding processes in standard fiber, light waves in off-axis cores stimulate general torsional–radial guided acoustic modes of the cylindrical cross section. Hundreds of such modes give rise to inter-core cross-phase modulation, with broad spectra that are quasi-continuous up to 1 GHz frequency. Inter-core cross-talk in a commercial, seven-core fiber is studied in both analysis and experiment. Opto-mechanical cross-talk is quantified in terms of an equivalent nonlinear coefficient, per acoustic mode or per frequency. The nonlinear coefficient may reach 1.9[W×km]−1, a value that is comparable with that of the intra-core Kerr effect in the same fiber.

Amorphous Molybdenum Sulfide Deposited Graphene Liquid Crystalline Fiber for Hydrogen Evolution Reaction Catalysis

Amorphous Molybdenum Sulfide Deposited Graphene Liquid Crystalline Fiber for Hydrogen Evolution Reaction Catalysis

Size‐dependent mechanical properties of glassy polymer nanofibers via molecular dynamics simulations

ABSTRACTThe microstructure of polymer matrix under cylindrical confinement is key to understanding the size‐dependent thermomechanical behavior of electrospun nanofibers. Coarse‐grained molecular dynamics simulation was applied here to probe polymer systems under cylindrical confinement, prepared with or without pre‐stretching. Simulation results showed that below a certain radius, a noticeable increase of the elastic modulus is observed with the decrease of the radius of cylindrical confinement. This size‐dependent mechanical behavior correlated to the degree of polymer chain orientation. Modulation of density and bond orientation in the radial direction was observed: the density and bond orientation began to oscillate, increasing the oscillation amplitudes with decreases in the radius. Such behavior suggests that the cylindrical confinement enhances the bond alignment of the entire fiber and not in the near‐surface layers only. The unstretched fibers had uniform density distribution along the fiber axis, while the stretched fibers demonstrated a fluctuation in density distribution. The crossover radius of size‐dependent behavior was two orders of magnitude smaller than observed in real experiments, demonstrating that the confinement affects some internal fiber scale, which exceeds the scale of individual macromolecules, and this internal scale may be related to supramolecular structures of the polymer matrix rather than the individual macromolecules. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 506–514

Mechanical tension and spontaneous muscle twitching precede the formation of cross-striated muscle in vivo.

Muscle forces are produced by repeated stereotypical actomyosin units called sarcomeres. Sarcomeres are chained into linear myofibrils spanning the entire muscle fiber. In mammalian body muscles, myofibrils are aligned laterally, resulting in their typical cross-striated morphology. Despite this detailed textbook knowledge about the adult muscle structure, it is still unclear how cross-striated myofibrils are built in vivo. Here, we investigate the morphogenesis of Drosophila abdominal muscles and establish them as an in vivo model for cross-striated muscle development. By performing live imaging, we find that long immature myofibrils lacking a periodic actomyosin pattern are built simultaneously in the entire muscle fiber and then align laterally to give mature cross-striated myofibrils. Interestingly, laser micro-lesion experiments demonstrate that mechanical tension precedes the formation of the immature myofibrils. Moreover, these immature myofibrils do generate spontaneous Ca2+-dependent contractions in vivo, which, when chemically blocked, result in cross-striation defects. Taken together, these results suggest a myofibrillogenesis model in which mechanical tension and spontaneous muscle twitching synchronize the simultaneous self-organization of different sarcomeric protein complexes to build highly regular cross-striated myofibrils spanning the length of large muscle fibers.

Accurate determination of fiber strength distributions

AbstractTensile strengths of small‐diameter ceramic fibers are commonly obtained from measured fracture loads on individual fibers and the average cross‐sectional area of the entire fiber population. The goal of the present article is to provide a critical assessment of the consequences of using the average fiber area in the inferred strength distribution. The issues are addressed through established theorems in convolution and uncertainty propagation as well as Monte Carlo simulations. Systematic errors introduced by using the average area are well‐represented by simple analytical formulae. The formulae are couched in terms of the coefficient of variation in fiber area and the dispersion in fiber strengths, characterized by the Weibull modulus. In turn, the formulae are used to determine the true values of Weibull modulus and reference strength from their nominal values. Random uncertainties associated with a finite number of tests decay slowly with number, in accordance with an inverse root scaling. When systematic errors are conflated with random uncertainties, accurate determination of the true Weibull modulus becomes increasingly challenging, even for seemingly large numbers of strength measurements. The results are used to assess the fidelity of previously‐reported experimental results based on nominal strength data.

Simulated characteristics of a heterojunction phototransistor with Ge1-xSnx alloy as base

Groups III-V compound semiconductors and their alloys are the main photodetecting elements for the entire fiber optic telecommunication band. However, the recent successful growth of Ge1-xSnx alloy on Ge virtual substrates on Si platform makes the group IV alloys a potential competitor. Ge1-xSnx alloy shows direct band gap and has an absorption coefficient almost 10 times higher than that of Ge. The photonic devices are complementary metal–oxide–semiconductor compatible. We have considered an n-Ge/p+-Ge1-xSnx/n-Ge1-xSnx heterojunction phototransistor (HPT) and studied the variations of terminal currents by considering the Gummel Poon model of HPT, and values of optical and current gains, photocurrent, and responsivity have been obtained. The performance of the device as a photodetector at fiber optic communication wavelengths seems quite encouraging to justify the use of GeSn-based HPTs as a replacement of III-IV semiconductor-based photodetectors.

Double-pulse pair Brillouin optical correlation-domain analysis.

Brillouin optical correlation-domain analysis (B-OCDA) allows for distributed measurements of strain and temperature with sub-cm resolution. Time-multiplexing techniques have previously extended B-OCDA to the monitoring of many km of fiber and two million resolution points. Thus far, however, the number of scans of correlation peaks positions, necessary to cover the fiber under test, was restricted to the order of 100 or more. In this work we report a B-OCDA protocol that is able to address an entire fiber using only 11 pairs of position scans per choice of frequency. The measurements protocol relies on a merger between B-OCDA principles and double-pulse-pair analysis, previously incorporated in time-domain Brillouin sensors. Phase coding of the pump and signal waves with a repeating, short and high-rate code stimulates Brillouin interactions in a large number of narrow correlation peaks, with substantial temporal overlap. Unambiguous measurements are achieved by repeating each experiment twice, using a pair of pump pulses of different durations, and subtracting the two output traces. The principle is demonstrated in the analysis of a 43 m-long fiber with 2.7 cm resolution. Several local hot-spots are properly identified in the measurements. The experimental uncertainty in the measurement of the local Brillouin frequency shift is estimated as ± 1.9 MHz. The proposed method requires broader detection bandwidth and a larger number of averages than those of previous time-gated B-OCDA setups. Hence the overall number of measurements is similar to that of previous setups.

Optoelectronic Fibers via Selective Amplification of In-Fiber Capillary Instabilities.

Thermally drawn metal-insulator-semiconductor fibers provide a scalable path to functional fibers. Here, a ladder-like metal-semiconductor-metal photodetecting device is formed inside a single silica fiber in a controllable and scalable manner, achieving a high density of optoelectronic components over the entire fiber length and operating at a bandwidth of 470 kHz, orders of magnitude larger than any other drawn fiber device.

Functional optical imaging from bat inferior colliculus using a micro-endoscope

We developed a confocal micro-endoscopic system that enables simultaneous recording of electrical neuronal responses—local field potentials (LFPs) and multi-unit activities, (MUA) — and fluorescence changes reflecting calcium activation derived from Oregon green dye. We recorded these responses from different depths of the inferior colliculus (IC) in two species of bats (Carollia perspicillata and Eptesicus fuscus) to tone bursts, noise bursts, and FM sweeps. Electrical responses were fast and registered the occurrence of sounds with submillisecond and millisecond precision. LFPs contained strong onset responses and weaker, extended oscillations that persisted for much of the sound’s duration. In contrast, calcium responses were slow, building up gradually over the course of 50-100 ms, and declined slowly following sound offset. Full horizontal-vertical video image scanning of the entire fiber optic bundle’s face was limited to 18.9 frames/s by the scanning mirror, but isolation and recording of successive individual horizontal scans, done by freezing the vertical scan, yielded 7,550 lines/s, or 132 microseconds for 1 line. Line-scanning revealed that the calcium responses indeed were slow, in the 50-100 ms range. They also were spatially diffuse, suggesting a distributed dendritic origin. [Work supported by JSPS, MEXT Japan, Shandong University, ONR, Capita Foundation.]

Fiber-based multiple-access frequency synchronization via 1f–2f dissemination**Project supported by the National Key Scientific Instrument and Equipment Development Project of China (Grant No. 2013YQ09094303).

Considering the reference frequency dissemination requirements of the Square Kilometre Array telescope (SKA) project, on the basis of the 1f–2f precision frequency synchronization scheme, we propose and demonstrate a fiber-based multiple-access frequency synchronization scheme. The dissemination reference frequency can be recovered at arbitrary nodes along the entire fiber link. It can be applied to antennas close proximity to the SKA central station, and will lead to a better SKA frequency synchronization network. As a performance test, we recover the disseminated 100-MHz reference frequency at an arbitrary node chosen as being 5 km away from the transmitting site. Relative frequency stabilities of 2.0×10−14/s and 1.6×10−16/104s are obtained. We also experimentally verify the feasibility of a frequency dissemination link with three access points.

Influence of finite extinction ratio on performance of phase-sensitive optical time-domain reflectometry.

The leakage light of optical pulses due to finite extinction ratio (ER) of an electro-optic modulator (EOM) leads to Rayleigh backscattered noises over the entire fiber length, and limits spatial resolution and sensing range in phase-sensitive optical time-domain reflectometry (Φ-OTDR). Two configurations are proposed to improve the ER of optical pulses for better spatial resolution over long sensing length. With ER of 55 dB using a nonlinear optical loop mirror, we achieved 2 m spatial resolution over 8.4 km sensing length; while with ER of 60 dB obtained by two cascaded EOMs, we can achieve a 1 m spatial resolution over the same range. Experimental results and analysis show that leakage of the optical pulses acts as a noise floor, which limits the highest spatial resolution over the same sensing range.

Application of diffusion tensor imaging in tracking visual pathway fiber bundles in postoperative intensity-modulated radiotherapy for cerebral gliomas

Objective To analyze the feasibility of incorporation of tracking visual pathway fiber bundles by diffusion tensor imaging (DTI) in computed tomography (CT) simulation to develop a protective radiotherapy regimen for cerebral gliomas. Methods A total of 31 patients with cerebral gliomas who were admitted to our hospital from 2013 to 2015 and planed to receive postoperative radiotherapy were enrolled as subjects. All patients underwent CT simulation, conventional or contrast-enhanced magnetic resonance imaging, and DTI. The obtained DTI images of visual pathway fiber bundles were fused with 3DT1 anatomical scans and then imported into the treatment planning system. A protective treatment plan (setting the entire visual pathway fiber bundles as organs at risk (OARs)) and a conventional treatment plan were made for intensity-modulated radiotherapy (IMRT). Comparison of treatment outcomes was made by paired t test. Results There were no significant differences in the conformity index and heterogeneity index of the planning target volume between the two treatment plans (P=0.875, 0.597), both of which had sufficient radiation doses to the target volume and conventional OARs protected. For the patients undergoing the protective treatment plan, the Dmax and Dmean values were reduced to 9.01% and 9.05%, respectively, in the ipsilateral optic tract and to 17.96% and 15.52%, respectively, in the contralateral optic tract; the Dmax and Dmean values were reduced to 5.37% and 5.48%(P=0.000), respectively, in the ipsilateral optic radiation tract and to 12.89% and 11.21%(P=0.000), respectively, in the contralateral optic radiation tract. Conclusions The protective treatment plan based on CT simulation combined with the display of visual pathway fiber bundles by DTI can reduce the radiation dose to the entire visual pathway fiber bundles, which keeps the risk of visual dysfunction after radiotherapy as low as possible. Key words: Diffusion tensor imaging; Visual pathway fiber bundle; Cerebral gliomas; Intensity modulated radiotherapy; Organs at risk

Metal–Insulator–Semiconductor Coaxial Microfibers Based on Self‐Organization of Organic Semiconductor:Polymer Blend for Weavable, Fibriform Organic Field‐Effect Transistors

With the increasing importance of electronic textiles as an ideal platform for wearable electronic devices, requirements for the development of functional electronic fibers with multilayered structures are increasing. In this paper, metal–polymer insulator–organic semiconductor (MIS) coaxial microfibers using the self‐organization of organic semiconductor:insulating polymer blends for weavable, fibriform organic field‐effect transistors (FETs) are demonstrated. A holistic process for MIS coaxial microfiber fabrication, including surface modification of gold microfiber thin‐film coating on the microfiber using a die‐coating system, and the self‐organization of organic semiconductor–insulator polymer blend is presented. Vertical phase‐separation of the organic semiconductor:insulating polymer blend film wrapping the metal microfibers provides a coaxial bilayer structure of gate dielectric (inside) and organic semiconductor (outside) with intimate interfacial contact. It is determined that the fibriform FETs based on MIS coaxial microfiber exhibit good charge carrier mobilities that approach the values of typical devices with planar substrate. It additionally exhibits electrical property uniformity over the entire fiber surface and improved bending durability. Fibriform organic FET embedded in a textile is demonstrated by weaving MIS coaxial microfibers with cotton and conducting threads, which verifies the feasibility of MIS coaxial microfiber for use in electronic textile applications.

Electrocoating of carbon fibres at ambient conditions

Electrocoating at constant current is less sensitive to moisture and oxygen than electrocoating at controlled potential, which makes it more interesting for industrial implementation. The galvanostatic electrocoating of carbon fibres with Poly(methylmethacrylate) (PMMA) was therefore studied and compared to the well researched potentiostatic electrocoating procedure. The influence of different experimental parameters on the coating efficiency was investigated in order to identify the mechanisms that are involved in the cathodic electrocoating at constant current. It could be confirmed that the involved mechanisms differ from potentiostatic electrocoating and it was found that galvanostatic electrocoating is more efficient at ambient conditions compared to potentiostatic electrocoating. Polymer layers that cover the entire carbon fibre surface could be achieved in a continuous process by galvanostatic electrocoating under ambient conditions.

Effects of epimuscular myofascial force transmission on sarcomere length of passive muscles in the rat hindlimb

Results from imaging studies and finite element models suggest epimuscular myofascial effects on sarcomere lengths in series within muscle fibers. However, experimental evidence is lacking. We evaluated epimuscular myofascial effects on (1) muscle belly, fiber, and mean sarcomere length and (2) sarcomere length distribution within passive fibers of the rat tibialis anterior (TA) and soleus (SO) muscles. Hindlimbs (n = 24) were positioned in predefined knee (55°, 90°, 125°, 160°) and ankle (either 90° or 125°) angles, and fixed in a formaldehyde solution. Varying knee joint angle causes changes in muscle–tendon unit length of SO and TA’s synergists, but not of SO and TA. Whole fibers were taken from SO and TA and photographed along their length. Mean sarcomere length was assessed for the entire fiber and for the proximal, intermediate, and distal thirds (fiber segments) separately. Mean sarcomere length of the fiber was not affected by knee angle, neither for SO (mean: 2.44 ± 0.03 μm and 2.19 ± 0.05 μm for ankle angles of 90° and 125°, respectively) nor for TA (mean: 2.33 ± 0.05 μm and 2.51 ± 0.07 μm for ankle angle set to 90° and 125°, respectively). Only for TA, a significant interaction between knee angle and fiber segment was found, indicating changes in the distribution of lengths of in-series sarcomeres. Thus, while epimuscular myofascial force transmission did not cause mean sarcomere length changes within passive SO and TA, it did alter the length distribution of sarcomeres within passive TA.