Rapid Quantification of 3D Collagen Fiber Alignment and Fiber Intersection Correlations with High Sensitivity

PubMed Central

Sun, Meng; Bloom, Alexander B.; Zaman, Muhammad H.

2015-01-01

Metastatic cancers aggressively reorganize collagen in their microenvironment. For example, radially orientated collagen fibers have been observed surrounding tumor cell clusters in vivo. The degree of fiber alignment, as a consequence of this remodeling, has often been difficult to quantify. In this paper, we present an easy to implement algorithm for accurate detection of collagen fiber orientation in a rapid pixel-wise manner. This algorithm quantifies the alignment of both computer generated and actual collagen fiber networks of varying degrees of alignment within 5°°. We also present an alternative easy method to calculate the alignment index directly from the standard deviation of fiber orientation. Using this quantitative method for determining collagen alignment, we demonstrate that the number of collagen fiber intersections has a negative correlation with the degree of fiber alignment. This decrease in intersections of aligned fibers could explain why cells move more rapidly along aligned fibers than unaligned fibers, as previously reported. Overall, our paper provides an easier, more quantitative and quicker way to quantify fiber orientation and alignment, and presents a platform in studying effects of matrix and cellular properties on fiber alignment in complex 3D environments. PMID:26158674

Mechanically Oriented 3D Collagen Hydrogel for Directing Neurite Growth.

PubMed

Antman-Passig, Merav; Levy, Shahar; Gartenberg, Chaim; Schori, Hadas; Shefi, Orit

2017-05-01

Recent studies in the field of neuro-tissue engineering have demonstrated the promising effects of aligned contact guidance cue to scaffolds of enhancement and direction of neuronal growth. In vivo, neurons grow and develop neurites in a complex three-dimensional (3D) extracellular matrix (ECM) surrounding. Studies have utilized hydrogel scaffolds derived from ECM molecules to better simulate natural growth. While many efforts have been made to control neuronal growth on 2D surfaces, the development of 3D scaffolds with an elaborate oriented topography to direct neuronal growth still remains a challenge. In this study, we designed a method for growing neurons in an aligned and oriented 3D collagen hydrogel. We aligned collagen fibers by inducing controlled uniaxial strain on gels. To examine the collagen hydrogel as a suitable scaffold for neuronal growth, we evaluated the physical properties of the hydrogel and measured collagen fiber properties. By combining the neuronal culture in 3D collagen hydrogels with strain-induced alignment, we were able to direct neuronal growth in the direction of the aligned collagen matrix. Quantitative evaluation of neurite extension and directionality within aligned gels was performed. The analysis showed neurite growth aligned with collagen matrix orientation, while maintaining the advantageous 3D growth.

Strain-Induced Alignment in Collagen Gels

PubMed Central

Vader, David; Kabla, Alexandre; Weitz, David; Mahadevan, Lakshminarayana

2009-01-01

Collagen is the most abundant extracellular-network-forming protein in animal biology and is important in both natural and artificial tissues, where it serves as a material of great mechanical versatility. This versatility arises from its almost unique ability to remodel under applied loads into anisotropic and inhomogeneous structures. To explore the origins of this property, we develop a set of analysis tools and a novel experimental setup that probes the mechanical response of fibrous networks in a geometry that mimics a typical deformation profile imposed by cells in vivo. We observe strong fiber alignment and densification as a function of applied strain for both uncrosslinked and crosslinked collagenous networks. This alignment is found to be irreversibly imprinted in uncrosslinked collagen networks, suggesting a simple mechanism for tissue organization at the microscale. However, crosslinked networks display similar fiber alignment and the same geometrical properties as uncrosslinked gels, but with full reversibility. Plasticity is therefore not required to align fibers. On the contrary, our data show that this effect is part of the fundamental non-linear properties of fibrous biological networks. PMID:19529768

Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

PubMed

Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

2015-06-29

Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.

Shear induced alignment of short nanofibers in 3D printed polymer composites.

PubMed

Yunus, Doruk Erdem; Shi, Wentao; Sohrabi, Salman; Liu, Yaling

2016-12-09

3D printing of composite materials offers an opportunity to combine the desired properties of composite materials with the flexibility of additive manufacturing in geometric shape and complexity. In this paper, the shear-induced alignment of aluminum oxide nanowires during stereolithography printing was utilized to fabricate a nanowire reinforced polymer composite. To align the fibers, a lateral oscillation mechanism was implemented and combined with wall pattern printing technique to generate shear flow in both vertical and horizontal directions. A series of specimens were fabricated for testing the composite material's tensile strength. The results showed that mechanical properties of the composite were improved by reinforcement of nanofibers through shear induced alignment. The improvement of tensile strength was approximately ∼28% by aligning the nanowires at 5 wt% (∼1.5% volume fraction) loading of aluminum oxide nanowires.

E-Spun Composite Fibers of Collagen and Dragline Silk Protein: Fiber Mechanics, Biocompatibility, and Application in Stem Cell Differentiation

PubMed Central

2015-01-01

Biocomposite matrices with high mechanical strength, high stability, and the ability to direct matrix-specific stem cell differentiation are essential for the reconstruction of lesioned tissues in tissue engineering and cell therapeutics. Toward this end, we used the electrospinning technique to fabricate well-aligned composite fibers from collagen and spider dragline silk protein, obtained from the milk of transgenic goats, mimicking the native extracellular matrix (ECM) on a similar scale. Collagen and the dragline silk proteins were found to mix homogeneously at all ratios in the electrospun (E-spun) fibers. As a result, the ultimate tensile strength and elasticity of the fibers increased monotonically with silk percentage, whereas the stretchability was slightly reduced. Strikingly, we found that the incorporation of silk proteins to collagen dramatically increased the matrix stability against excessive fiber swelling and shape deformation in cell culture medium. When human decidua parietalis placental stem cells (hdpPSCs) were seeded on the collagen–silk matrices, the matrices were found to support cell proliferation at a similar rate as that of the pure collagen matrix, but they provided cell adhesion with reduced strengths and induced cell polarization at varied levels. Matrices containing 15 and 30 wt % silk in collagen (CS15, CS30) were found to induce a level of neural differentiation comparable to that of pure collagen. In particular, CS15 matrix induced the highest extent of cell polarization and promoted the development of extended 1D neural filaments strictly in-line with the aligned fibers. Taking the increased mechanical strength and fiber stability into consideration, CS15 and CS30 E-spun fibers offer better alternatives to pure collagen fibers as scaffolds that can be potentially utilized in neural tissue repair and the development of future nanobiodevices. PMID:25405355

Monitoring techniques for the manufacture of tapered optical fibers.

PubMed

Mullaney, Kevin; Correia, Ricardo; Staines, Stephen E; James, Stephen W; Tatam, Ralph P

2015-10-01

The use of a range of optical techniques to monitor the process of fabricating optical fiber tapers is investigated. Thermal imaging was used to optimize the alignment of the optical system; the transmission spectrum of the fiber was monitored to confirm that the tapers had the required optical properties and the strain induced in the fiber during tapering was monitored using in-line optical fiber Bragg gratings. Tapers were fabricated with diameters down to 5 μm and with waist lengths of 20 mm using single-mode SMF-28 fiber.

Fiber optic light collection system for scanning-tunneling-microscope-induced light emission.

PubMed

Watkins, Neil J; Long, James P; Kafafi, Zakya H; Mäkinen, Antti J

2007-05-01

We report a compact light collection scheme suitable for retrofitting a scanning tunneling microscope (STM) for STM-induced light emission experiments. The approach uses a pair of optical fibers with large core diameters and high numerical apertures to maximize light collection efficiency and to moderate the mechanical precision required for alignment. Bench tests indicate that efficiency reduction is almost entirely due to reflective losses at the fiber ends, while losses due to fiber misalignment have virtually been eliminated. Photon-map imaging with nanometer features is demonstrated on a stepped Au(111) surface with signal rates exceeding 10(4) counts/s.

Aligned Layers of Silver Nano-Fibers.

PubMed

Golovin, Andrii B; Stromer, Jeremy; Kreminska, Liubov

2012-02-01

We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polarization of transmitted light. The aligned layers of silver nano-fibers might be used in optics, microwave applications, and organic electronics.

The direction of stretch-induced cell and stress fiber orientation depends on collagen matrix stress.

PubMed

Tondon, Abhishek; Kaunas, Roland

2014-01-01

Cell structure depends on both matrix strain and stiffness, but their interactive effects are poorly understood. We investigated the interactive roles of matrix properties and stretching patterns on cell structure by uniaxially stretching U2OS cells expressing GFP-actin on silicone rubber sheets supporting either a surface-adsorbed coating or thick hydrogel of type-I collagen. Cells and their actin stress fibers oriented perpendicular to the direction of cyclic stretch on collagen-coated sheets, but oriented parallel to the stretch direction on collagen gels. There was significant alignment parallel to the direction of a steady increase in stretch for cells on collagen gels, while cells on collagen-coated sheets did not align in any direction. The extent of alignment was dependent on both strain rate and duration. Stretch-induced alignment on collagen gels was blocked by the myosin light-chain kinase inhibitor ML7, but not by the Rho-kinase inhibitor Y27632. We propose that active orientation of the actin cytoskeleton perpendicular and parallel to direction of stretch on stiff and soft substrates, respectively, are responses that tend to maintain intracellular tension at an optimal level. Further, our results indicate that cells can align along directions of matrix stress without collagen fibril alignment, indicating that matrix stress can directly regulate cell morphology.

Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques.

PubMed

Munro, Troy; Putzeys, Tristan; Copeland, Cameron G; Xing, Changhu; Lewis, Randolph V; Ban, Heng; Glorieux, Christ; Wubbenhorst, Michael

2017-04-01

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production.

Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques

PubMed Central

Munro, Troy; Putzeys, Tristan; Copeland, Cameron G.; Xing, Changhu; Lewis, Randolph V; Ban, Heng; Glorieux, Christ; Wubbenhorst, Michael

2018-01-01

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production. PMID:29430211

Biodegradable composites with aligned hydroxyapatite nanoneedles.

PubMed

Sun, Shih-Po; Wei, Mei; Olson, James R; Shaw, Montgomery T

2012-10-01

We prepared an anisotropic bone graft composite to mimic the hierarchical structure of the natural bone in which aligned hydroxyapatite (HA) nanocrystals deposit along collagen fibers. To approach the modulus and strength of the bone, we incorporated synthesized HA nanoneedles and melt drawn poly(L-lactic acid) fibers in our composite as reinforcing components. Their preferred orientation was induced via a modified pultrusion process. The HA orientation distribution was examined using wide angle X-ray diffraction. Micromechanical Halpin-Tsai model predictions considering the amount, shape, and orientation distribution of HA were compared, favorably, with the experimental observations. Copyright © 2012 Wiley Periodicals, Inc.

Oriented nanofibers embedded in a polymer matrix

NASA Technical Reports Server (NTRS)

Barrera, Enrique V. (Inventor); Lozano, Karen (Inventor); Rodriguez-Macias, Fernando J. (Inventor); Chibante, Luis Paulo Felipe (Inventor); Stewart, David Harris (Inventor)

2011-01-01

A method of forming a composite of embedded nanofibers in a polymer matrix is disclosed. The method includes incorporating nanofibers in a plastic matrix forming agglomerates, and uniformly distributing the nanofibers by exposing the agglomerates to hydrodynamic stresses. The hydrodynamic said stresses force the agglomerates to break apart. In combination or additionally elongational flow is used to achieve small diameters and alignment. A nanofiber reinforced polymer composite system is disclosed. The system includes a plurality of nanofibers that are embedded in polymer matrices in micron size fibers. A method for producing nanotube continuous fibers is disclosed. Nanofibers are fibrils with diameters of 100 nm, multiwall nanotubes, single wall nanotubes and their various functionalized and derivatized forms. The method includes mixing a nanofiber in a polymer; and inducing an orientation of the nanofibers that enables the nanofibers to be used to enhance mechanical, thermal and electrical properties. Orientation is induced by high shear mixing and elongational flow, singly or in combination. The polymer may be removed from said nanofibers, leaving micron size fibers of aligned nanofibers.

Nonlinear temperature dependence of glue-induced birefringence in polarization maintaining FBG sensors

NASA Astrophysics Data System (ADS)

Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

2016-05-01

Glue-induced stresses decrease the accuracy of surface-mounted fiber Bragg gratings (FBG). Significant temperature dependent glue-induced birefringence was verified when a thermally cured epoxy-based bonding technique had been used. Determining the peak separation of two azimuthally aligned FBGs in PM fibers combined with a polarization resolved measurement set-up in a temperature range between -30°C and 150°C revealed high glue-induced stresses at low temperatures. Peak separations of about 60 pm and a nonlinear temperature dependence of the glue-induced birefringence due to stress relaxation processes and a visco-elastic behavior of the used adhesive have been shown.

Impact of elastin incorporation into electrochemically aligned collagen fibers on mechanical properties and smooth muscle cell phenotype.

PubMed

Nguyen, Thuy-Uyen; Bashur, Chris A; Kishore, Vipuil

2016-03-17

Application of tissue-engineered vascular grafts (TEVGs) for the replacement of small-diameter arteries is limited due to thrombosis and intimal hyperplasia. Previous studies have attempted to address the limitations of TEVGs by developing scaffolds that mimic the composition (collagen and elastin) of native arteries to better match the mechanical properties of the graft with the native tissue. However, most existing scaffolds do not recapitulate the aligned topography of the collagen fibers found in native vessels. In the current study, based on the principles of isoelectric focusing, two different types of elastin (soluble and insoluble) were incorporated into highly oriented electrochemically aligned collagen (ELAC) fibers and the effect of elastin incorporation on the mechanical properties of the ELAC fibers and smooth muscle cell (SMC) phenotype was investigated. The results indicate that elastin incorporation significantly decreased the modulus of ELAC fibers to converge upon that of native vessels. Further, a significant increase in yield strain and decrease in Young's modulus was observed on all fibers post SMC culture compared with before the culture. Real-time polymerase chain reaction results showed a significant increase in the expression of α-smooth muscle actin and calponin on ELAC fibers with insoluble elastin, suggesting that incorporation of insoluble elastin induces a contractile phenotype in SMCs after two weeks of culture on ELAC fibers. Immunofluorescence results showed that calponin expression increased with time on all fibers. In conclusion, insoluble elastin incorporated ELAC fibers have the potential to be used for the development of functional TEVGs for the repair and replacement of small-diameter arteries.

Structure-induced variation of thermal conductivity in epoxy resin fibers.

PubMed

Zeng, Xiaoliang; Xiong, Yucheng; Fu, Qiang; Sun, Rong; Xu, Jianbin; Xu, Dongyan; Wong, Ching-Ping

2017-08-03

The ability to control thermal conductivity is important in a wide variety of applications, especially in heat removal, heat insulation, and thermoelectric energy conversion. Herein, we reveal that the thermal conductivity of epoxy resin fibers increases on decreasing the fiber diameter and surpasses the bulk value (0.25 W m -1 K -1 at 300 K) for the fiber with a diameter of 211 nm. The variation of thermal conductivity in epoxy resin fibers can likely be attributed to their microstructure change-enhanced interface phonon scattering between amorphous and crystalline regions and the enhanced alignment of the molecular chain orientation.

On-command on/off switching of progenitor cell and cancer cell polarized motility and aligned morphology via a cytocompatible shape memory polymer scaffold.

PubMed

Wang, Jing; Quach, Andy; Brasch, Megan E; Turner, Christopher E; Henderson, James H

2017-09-01

In vitro biomaterial models have enabled advances in understanding the role of extracellular matrix (ECM) architecture in the control of cell motility and polarity. Most models are, however, static and cannot mimic dynamic aspects of in vivo ECM remodeling and function. To address this limitation, we present an electrospun shape memory polymer scaffold that can change fiber alignment on command under cytocompatible conditions. Cellular response was studied using the human fibrosarcoma cell line HT-1080 and the murine mesenchymal stem cell line C3H/10T1/2. The results demonstrate successful on-command on/off switching of cell polarized motility and alignment. Decrease in fiber alignment causes a change from polarized motility along the direction of fiber alignment to non-polarized motility and from aligned to unaligned morphology, while increase in fiber alignment causes a change from non-polarized to polarized motility along the direction of fiber alignment and from unaligned to aligned morphology. In addition, the findings are consistent with the hypothesis that increased fiber alignment causes increased cell velocity, while decreased fiber alignment causes decreased cell velocity. On-command on/off switching of cell polarized motility and alignment is anticipated to enable new study of directed cell motility in tumor metastasis, in cell homing, and in tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

Neurite Outgrowth On Electrospun PLLA Fibers Is Enhanced By Exogenous Electrical Stimulation

PubMed Central

Koppes, A. N.; Zaccor, N. W.; Rivet, C. J.; Williams, L. A.; Piselli, J. M.; Gilbert, R. J.; Thompson, D. M.

2014-01-01

Objective Both electrical stimuli (endogenous and exogenous) and topographical cues are instructive to axonal extension. This report, for the first time, investigated the relative dominance of directional topographical guidance cues and directional electrical cues to enhance and/or direct primary neurite extension. We hypothesized the combination of electrical stimulation with electrospun fiber topography would induce longer neurite extension from DRG neurons than the presence of electrical stimulation or aligned topography alone. Approach To test the hypothesis, neurite outgrowth was examined on laminin-coated poly-L-lactide (PLLA) films or electrospun fibers (2 μm in diameter) in the presence or absence of electrical stimulation. Immunostained neurons were semi-automatically traced using Neurolucida software and morphology was evaluated. Results Neurite extension increased 74% on the aligned fibers compared to film controls. Stimulation alone increased outgrowth by 32% on films or fibers relative to unstimulated film controls. The co-presentation of topographical (fibers) with biophysical (electrical stimulation) cues resulted in a synergistic 126% increase in outgrowth relative to unstimulated film controls. Field polarity had no influence on the directionality of neurite, indicating topographical cues are responsible to guide neurite extension. Significance Both cues (electrical stimulation and fiber geometry) are modular in nature and can be synergistically applied in conjunction with other common methods in regenerative medicine such as controlled release of growth factors to further influence axonal growth in vivo. The combined application of electrical and aligned fiber topographical guidance cues described herein, if translated in vivo, could provide a more supportive environment for directed and robust axonal regeneration following peripheral nerve injury. PMID:24891494

Neurite outgrowth on electrospun PLLA fibers is enhanced by exogenous electrical stimulation.

PubMed

Koppes, A N; Zaccor, N W; Rivet, C J; Williams, L A; Piselli, J M; Gilbert, R J; Thompson, D M

2014-08-01

Both electrical stimuli (endogenous and exogenous) and topographical cues are instructive to axonal extension. This report, for the first time, investigated the relative dominance of directional topographical guidance cues and directional electrical cues to enhance and/or direct primary neurite extension. We hypothesized the combination of electrical stimulation with electrospun fiber topography would induce longer neurite extension from dorsal root ganglia neurons than the presence of electrical stimulation or aligned topography alone. To test the hypothesis, neurite outgrowth was examined on laminin-coated poly-L-lactide films or electrospun fibers (2 µm in diameter) in the presence or absence of electrical stimulation. Immunostained neurons were semi-automatically traced using Neurolucida software and morphology was evaluated. Neurite extension increased 74% on the aligned fibers compared to film controls. Stimulation alone increased outgrowth by 32% on films or fibers relative to unstimulated film controls. The co-presentation of topographical (fibers) with biophysical (electrical stimulation) cues resulted in a synergistic 126% increase in outgrowth relative to unstimulated film controls. Field polarity had no influence on the directionality of neurites, indicating topographical cues are responsible for guiding neurite extension. Both cues (electrical stimulation and fiber geometry) are modular in nature and can be synergistically applied in conjunction with other common methods in regenerative medicine such as controlled release of growth factors to further influence axonal growth in vivo. The combined application of electrical and aligned fiber topographical guidance cues described herein, if translated in vivo, could provide a more supportive environment for directed and robust axonal regeneration following peripheral nerve injury.

A simplified implementation of edge detection in MATLAB is faster and more sensitive than fast fourier transform for actin fiber alignment quantification.

PubMed

Kemeny, Steven Frank; Clyne, Alisa Morss

2011-04-01

Fiber alignment plays a critical role in the structure and function of cells and tissues. While fiber alignment quantification is important to experimental analysis and several different methods for quantifying fiber alignment exist, many studies focus on qualitative rather than quantitative analysis perhaps due to the complexity of current fiber alignment methods. Speed and sensitivity were compared in edge detection and fast Fourier transform (FFT) for measuring actin fiber alignment in cells exposed to shear stress. While edge detection using matrix multiplication was consistently more sensitive than FFT, image processing time was significantly longer. However, when MATLAB functions were used to implement edge detection, MATLAB's efficient element-by-element calculations and fast filtering techniques reduced computation cost 100 times compared to the matrix multiplication edge detection method. The new computation time was comparable to the FFT method, and MATLAB edge detection produced well-distributed fiber angle distributions that statistically distinguished aligned and unaligned fibers in half as many sample images. When the FFT sensitivity was improved by dividing images into smaller subsections, processing time grew larger than the time required for MATLAB edge detection. Implementation of edge detection in MATLAB is simpler, faster, and more sensitive than FFT for fiber alignment quantification.

Direct-write 3D printing of composite materials with magnetically aligned discontinuous reinforcement

NASA Astrophysics Data System (ADS)

Martin, Joshua J.; Caunter, Andrew; Dendulk, Amy; Goodrich, Scott; Pembroke, Ryan; Shores, Dan; Erb, Randall M.

2017-05-01

Three-dimensional (3D) printing of fiber reinforced composites represents an enabling technology that may bring toughness and specific strength to complex parts. Recently, direct-write 3D printing has been offered as a promising route to manufacturing fiber reinforced composites that show high specific strength. These approaches primarily rely on the use of shear-alignment during the extrusion process to align fibers along the printing direction. Shear alignment prevents fibers from being oriented along principle stress directions of the final designed part. This paper describes a new direct-write style 3D printing system that incorporates magnetic fields to actively control the orientation of reinforcing fibers during the printing of fiber reinforced composites. Such a manufacturing system is fraught with complications from the high shear dominated alignment experienced by the fibers during extrusion to the slow magnetic alignment dynamics of fibers in viscous media. Here we characterize these issues and suggest effective operating windows in which magnetic alignment is a viable approach to orienting reinforcing particles during direct-write 3D printing.

Few-mode fiber based distributed curvature sensor through quasi-single-mode Brillouin frequency shift.

PubMed

Wu, Hao; Wang, Ruoxu; Liu, Deming; Fu, Songnian; Zhao, Can; Wei, Huifeng; Tong, Weijun; Shum, Perry Ping; Tang, Ming

2016-04-01

We proposed and demonstrated a few-mode fiber (FMF) based optical-fiber sensor for distributed curvature measurement through quasi-single-mode Brillouin frequency shift (BFS). By central-alignment splicing FMF and single-mode fiber (SMF) with a fusion taper, a SMF-components-compatible distributed curvature sensor based on FMF is realized using the conventional Brillouin optical time-domain analysis system. The distributed BFS change induced by bending in FMF has been theoretically and experimentally investigated. The precise BFS response to the curvature along the fiber link has been calibrated. A proof-of-concept experiment is implemented to validate its effectiveness in distributed curvature measurement.

Photothermal camera port accessory for microscopic thermal diffusivity imaging

NASA Astrophysics Data System (ADS)

Escola, Facundo Zaldívar; Kunik, Darío; Mingolo, Nelly; Martínez, Oscar Eduardo

2016-06-01

The design of a scanning photothermal accessory is presented, which can be attached to the camera port of commercial microscopes to measure thermal diffusivity maps with micrometer resolution. The device is based on the thermal expansion recovery technique, which measures the defocusing of a probe beam due to the curvature induced by the local heat delivered by a focused pump beam. The beam delivery and collecting optics are built using optical fiber technology, resulting in a robust optical system that provides collinear pump and probe beams without any alignment adjustment necessary. The quasiconfocal configuration for the signal collection using the same optical fiber sets very restrictive conditions on the positioning and alignment of the optical components of the scanning unit, and a detailed discussion of the design equations is presented. The alignment procedure is carefully described, resulting in a system so robust and stable that no further alignment is necessary for the day-to-day use, becoming a tool that can be used for routine quality control, operated by a trained technician.

Mechanisms of lamellar collagen formation in connective tissues.

PubMed

Ghazanfari, Samaneh; Khademhosseini, Ali; Smit, Theodoor H

2016-08-01

The objective of tissue engineering is to regenerate functional tissues. Engineering functional tissues requires an understanding of the mechanisms that guide the formation and evolution of structure in the extracellular matrix (ECM). In particular, the three-dimensional (3D) collagen fiber arrangement is important as it is the key structural determinant that provides mechanical integrity and biological function. In this review, we survey the current knowledge on collagen organization mechanisms that can be applied to create well-structured functional lamellar tissues and in particular intervertebral disc and cornea. Thus far, the mechanisms behind the formation of cross-aligned collagen fibers in the lamellar structures is not fully understood. We start with cell-induced collagen alignment and strain-stabilization behavior mechanisms which can explain a single anisotropically aligned collagen fiber layer. These mechanisms may explain why there is anisotropy in a single layer in the first place. However, they cannot explain why a consecutive collagen layer is laid down with an alternating alignment. Therefore, we explored another mechanism, called liquid crystal phasing. While dense concentrations of collagen show such behavior, there is little evidence that the conditions for liquid crystal phasing are actually met in vivo. Instead, lysyl aldehyde-derived collagen cross-links have been found essential for correct lamellar matrix deposition. Furthermore, we suggest that supra-cellular (tissue-level) shear stress may be instrumental in the alignment of collagen fibers. Understanding the potential mechanisms behind the lamellar collagen structure in connective tissues will lead to further improvement of the regeneration strategies of functional complex lamellar tissues. Copyright © 2016 Elsevier Ltd. All rights reserved.

A fiber optic sensor for ophthalmic refractive diagnostics

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Dhadwal, Harbans S.; Campbell, Melanie C. W.; Dellavecchia, Michael A.

1992-01-01

This paper demonstrates the application of a lensless fiber optic spectrometer (sensor) to study the onset of cataracts. This new miniaturized and rugged fiber optic probe is based upon dynamic light scattering (DLS) principles. It has no moving parts, no apertures, and requires no optical alignment. It is flexible and easy to use. Results are presented for cold-induced cataract in excised bovine eye lenses, and aging effects in excised human eye lenses. The device can be easily incorporated into a slit-lamp apparatus (ophthalmoscope) for complete eye diagnostics.

Production of aligned microfibers and nanofibers and derived functional monoliths

DOEpatents

Hu, Michael Z [Knoxville, TN; DePaoli, David W [Knoxville, TN; Kuritz, Tanya [Kingston, TN; Omatete, Ogbemi [New Port Richey, FL

2007-08-14

The present invention comprises a method for producing microfibers and nanofibers and further fabricating derived solid monolithic materials having aligned uniform micro- or nanofibrils. A method for producing fibers ranging in diameter from micrometer-sized to nanometer-sized comprises the steps of producing an electric field and preparing a solid precipitative reaction media wherein the media comprises at least one chemical reactive precursor and a solvent having low electrical conductivity and wherein a solid precipitation reaction process for nucleation and growth of a solid phase occurs within the media. Then, subjecting the media to the electric field to induce in-situ growth of microfibers or nanofibers during the reaction process within the media causing precipitative growth of solid phase particles wherein the reaction conditions and reaction kinetics control the size, morphology and composition of the fibers. The fibers can then be wet pressed while under electric field into a solid monolith slab, dried and consolidated.

Changes in collection efficiency in nylon net filter media through magnetic alignment of elongated aerosol particles.

PubMed

Lam, Christopher O; Finlay, W H

2009-10-01

Fiber aerosols tend to align parallel to surrounding fluid streamlines in shear flows, making their filtration more difficult. However, previous research indicates that composite particles made from cromoglycic acid fibers coated with small nanoscaled magnetite particles can align with an applied magnetic field. The present research explored the effect of magnetically aligning these fibers to increase their filtration. Nylon net filters were challenged with the aerosol fibers, and efficiency tests were performed with and without a magnetic field applied perpendicular to the flow direction. We investigated the effects of varying face velocities, the amount of magnetite material on the aerosol particles, and magnetic field strengths. Findings from the experiments, matched by supporting single-fiber theories, showed significant efficiency increases at the low face velocity of 1.5 cm s(-1) at all magnetite compositions, with efficiencies more than doubling due to magnetic field alignment in certain cases. At a higher face velocity of 5.12 cm s(-1), filtration efficiencies were less affected by the magnetic field alignment being, at most, 43% higher for magnetite weight compositions up to 30%, while at a face velocity of 10.23 cm s(-1) alignment effects were insignificant. In most cases, efficiencies became independent of magnetic field strength above 50 mT, suggesting full alignment of the fibers. The present data suggest that fiber alignment in a magnetic field may warrant applications in the filtration and detection of fibers, such as asbestos.

Image-based quantification of fiber alignment within electrospun tissue engineering scaffolds is related to mechanical anisotropy.

PubMed

Fee, Timothy; Downs, Crawford; Eberhardt, Alan; Zhou, Yong; Berry, Joel

2016-07-01

It is well documented that electrospun tissue engineering scaffolds can be fabricated with variable degrees of fiber alignment to produce scaffolds with anisotropic mechanical properties. Several attempts have been made to quantify the degree of fiber alignment within an electrospun scaffold using image-based methods. However, these methods are limited by the inability to produce a quantitative measure of alignment that can be used to make comparisons across publications. Therefore, we have developed a new approach to quantifying the alignment present within a scaffold from scanning electron microscopic (SEM) images. The alignment is determined by using the Sobel approximation of the image gradient to determine the distribution of gradient angles with an image. This data was fit to a Von Mises distribution to find the dispersion parameter κ, which was used as a quantitative measure of fiber alignment. We fabricated four groups of electrospun polycaprolactone (PCL) + Gelatin scaffolds with alignments ranging from κ = 1.9 (aligned) to κ = 0.25 (random) and tested our alignment quantification method on these scaffolds. It was found that our alignment quantification method could distinguish between scaffolds of different alignments more accurately than two other published methods. Additionally, the alignment parameter κ was found to be a good predictor the mechanical anisotropy of our electrospun scaffolds. The ability to quantify fiber alignment within and make direct comparisons of scaffold fiber alignment across publications can reduce ambiguity between published results where cells are cultured on "highly aligned" fibrous scaffolds. This could have important implications for characterizing mechanics and cellular behavior on aligned tissue engineering scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1680-1686, 2016. © 2016 Wiley Periodicals, Inc.

Variable percolation threshold of composites with fiber fillers under compression

NASA Astrophysics Data System (ADS)

Lin, Chuan; Wang, Hongtao; Yang, Wei

2010-07-01

The piezoresistant effect in conducting fiber-filled composites has been studied by a continuum percolation model. Simulation was performed by a Monte Carlo method that took into account both the deformation-induced fiber bending and rotation. The percolation threshold was found to rise with the compression strain, which explains the observed positive piezoresistive coefficients in such composites. The simulations unveiled the effect of the microstructure evolution during deformation. The fibers are found to align perpendicularly to the compression direction. As the fiber is bended, the effective length in making a conductive network is shortened. Both effects contribute to a larger percolation threshold and imply a positive piezoresistive coefficient according the universal power law.

Optical fiber stripper positioning apparatus

DOEpatents

Fyfe, Richard W.; Sanchez, Jr., Amadeo

1990-01-01

An optical fiber positioning apparatus for an optical fiber stripping device is disclosed which is capable of providing precise axial alignment between an optical fiber to be stripped of its outer jacket and the cutting blades of a stripping device. The apparatus includes a first bore having a width approximately equal to the diameter of an unstripped optical fiber and a counter bore axially aligned with the first bore and dimensioned to precisely receive a portion of the stripping device in axial alignment with notched cutting blades within the stripping device to thereby axially align the notched cutting blades of the stripping device with the axis of the optical fiber to permit the notched cutting blades to sever the jacket on the optical fiber without damaging the cladding on the optical fiber. In a preferred embodiment, the apparatus further includes a fiber stop which permits determination of the length of jacket to be removed from the optical fiber.

Electrospinning of single wall carbon nanotube reinforced aligned fibrils and yarns

NASA Astrophysics Data System (ADS)

Lam, Hoa Le

Commercial carbon fibers produced from a polyacrylonitrile (PAN) precursor have reached their performance limit. The approach in this study involves the use of single carbon nanotubes (SWNT) with an ultra-high elastic modulus of approximately ˜1 TPa and tensile strength of ˜37 GPa at a breaking strain of ˜6% to reinforce PAN. In order to translate these extraordinary properties to a higher order structure, the need for a media to carry and assemble the SWNT into continuous fibers or yarns is necessary. Effective translation of properties can only be achieved through uniform distribution of SWNT and their alignment in the fiber axis. This has been one of the major challenges since SWNTs tend to agglomerate due to high van der Waals attraction between tubes. It is the goal of this study to develop dispersion technique(s) for the SWNT and process them into aligned fibers utilizing the electrospinning process. The electrospun nanofibers were then characterized by various techniques such as ESEM, Raman microspectroscopy, HRTEM, and tensile testing. Composite nanofibers containing various contents of SWNT up to 10 wt. % with diameter ranging from 40--300 nm were successfully electrospun through varying the polymer concentration and spinning parameters. The inclusion of SWNTs and their alignment in the fiber axis were confirmed by Raman microspectroscopy, polarized Raman and HRETEM. The failure mechanism of the nanofibers was investigated by HRTEM through fiber surface fracture. A two stage rupture mechanism was observed where crazing initiates at a surface defect followed by SWNTs pulling out of the PAN matrix. Such mechanisms consume energy therefore strengthening and toughening the fibers. Mechanical drawing of the fiber prior to heat treatment induced molecular orientation resulting in oriented graphite layers in the carbonized fibers. This study has established a processing base and characterization techniques to support the design and development of SWNT reinforced PAN-derived carbon nanofibers. The encouraging results from this study suggest a promising pathway to produce the next generation of high performance CNT reinforced carbon nanofibers. This would help in translating of the remarkable properties of SWNT to macroscopic applications, thus filling the dimensional and properties gap between nanoscopic and macroscopic structures.

Platelet-derived Growth-factor-releasing Aligned Collagen-nanoparticle Fibers Promote the Proliferation and Tenogenic Differentiation of Adipose-derived Stem Cells

DTIC Science & Technology

2013-11-27

lar to the slow axis appear yellow [19]. To observe the morphology of aligned collagen fibril, fibers were dehydrated via graded series of ethanols (70...Invitrogen) displayed prolifer- ating cell numbers. 2.5. Effect of aligned collagen–NP fibers on cell morphology and proliferation (7 days’ culture) A...loaded with PDGF than in the well with fibers that contained only empty NPs (control). 3.5. ADSCs cell proliferation and morphology on aligned collagen–NP

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.

Albumin fiber scaffolds for engineering functional cardiac tissues.

PubMed

Fleischer, Sharon; Shapira, Assaf; Regev, Omri; Nseir, Nora; Zussman, Eyal; Dvir, Tal

2014-06-01

In recent years attempts to engineer contracting cardiac patches were focused on recapitulation of the myocardium extracellular microenvironment. We report here on our work, where for the first time, a three-dimensional cardiac patch was fabricated from albumin fibers. We hypothesized that since albumin fibers' mechanical properties resemble those of cardiac tissue extracellular matrix (ECM) and their biochemical character enables their use as protein carriers, they can support the assembly of cardiac tissues capable of generating strong contraction forces. Here, we have fabricated aligned and randomly oriented electrospun albumin fibers and investigated their structure, mechanical properties, and chemical nature. Our measurements showed that the scaffolds have improved elasticity as compared to synthetic electrospun PCL fibers, and that they are capable of adsorbing serum proteins, such as laminin leading to strong cell-matrix interactions. Moreover, due to the functional groups on their backbone, the fibers can be chemically modified with essential biomolecules. When seeded with rat neonatal cardiac cells the engineered scaffolds induced the assembly of aligned cardiac tissues with high aspect ratio cardiomyocytes and massive actinin striation. Compared to synthetic fibrous scaffolds, cardiac cells cultured within aligned or randomly oriented scaffolds formed functional tissues, exhibiting significantly improved function already on Day 3, including higher beating rate (P = 0.0002 and P < 0.0001, respectively), and higher contraction amplitude (P = 0.009 and P = 0.003, respectively). Collectively, our results suggest that albumin electrospun scaffolds can play a key role in contributing to the ex vivo formation of a contracting cardiac muscle tissue. © 2014 Wiley Periodicals, Inc.

Formation of Highly Aligned Collagen Nanofibers by Continuous Cyclic Stretch of a Collagen Hydrogel Sheet.

PubMed

Nam, Eunryel; Lee, Won Chul; Takeuchi, Shoji

2016-07-01

A collagen sheet with highly aligned collagen fibers is fabricated by continuous cyclic stretch. The rearrangement of the collagen fibers depends on the different process parameters of the cyclic stretch, including magnitude, frequency, and period of stretch. The collagen fibers are aligned perpendicularly to the direction of the stretch. Corneal stromal cells and smooth muscle cells cultivated on the highly aligned collagen sheet show alignment along the collagen fibers without the stretch during culture. Thus, the sheet can be a suitable scaffold for use in regenerative medicine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A continuous process to align electrospun nanofibers into parallel and crossed arrays

NASA Astrophysics Data System (ADS)

Laudenslager, Michael J.; Sigmund, Wolfgang M.

2013-04-01

Electrical, optical, and mechanical properties of nanofibers are strongly affected by their orientation. Electrospinning is a nanofiber processing technique that typically produces nonwoven meshes of randomly oriented fibers. While several alignment techniques exist, they are only able to produce either a very thin layer of aligned fibers or larger quantities of fibers with less control over their alignment and orientation. The technique presented herein fills the gap between these two methods allowing one to produce thick meshes of highly oriented nanofibers. In addition, this technique is not limited to collection of fibers along a single axis. Modifications to the basic setup allow collection of crossed fibers without stopping and repositioning the apparatus. The technique works for a range of fiber sizes. In this study, fiber diameters ranged from 100 nm to 1 micron. This allows a few fibers at a time to rapidly deposit in alternating directions creating an almost woven structure. These aligned nanofibers have the potential to improve the performance of energy storage and thermoelectric devices and hold great promise for directed cell growth applications.

Polarization variations in installed fibers and their influence on quantum key distribution systems.

PubMed

Ding, Yu-Yang; Chen, Hua; Wang, Shuang; He, De-Yong; Yin, Zhen-Qiang; Chen, Wei; Zhou, Zheng; Guo, Guang-Can; Han, Zheng-Fu

2017-10-30

Polarization variations in the installed fibers are complex and volatile, and would severely affect the performances of polarization-sensitive quantum key distribution (QKD) systems. Based on the recorded data about polarization variations of different installed fibers, we establish an analytical methodology to quantitatively evaluate the influence of polarization variations on polarization-sensitive QKD systems. Using the increased quantum bit error rate induced by polarization variations as a key criteria, we propose two parameters - polarization drift time and required tracking speed - to characterize polarization variations. For field buried and aerial fibers with different length, we quantitatively evaluate the influence of polarization variations, and also provide requirements and suggestions for polarization basis alignment modules of QKD systems deployed in different kind of fibers.

Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

PubMed

Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

2016-02-10

Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

Platform technologies for hybrid optoelectronic integration and packaging

NASA Astrophysics Data System (ADS)

Datta, Madhumita

In order to bring fiber-optics closer to individual home and business services, the optical network components have to be inexpensive and reliable. Integration and packaging of optoelectronic devices holds the key to high-volume low-cost component manufacturing. The goal of this dissertation is to propose, study, and demonstrate various ways to integrate optoelectronic devices on a packaging platform to implement cost-effective, functional optical modules. Two types of hybrid integration techniques have been proposed: flip-chip solder bump bonding for high-density two-dimensional array packaging of surface-emitting devices, and solder preform bonding for fiber-coupled edge-emitting semiconductor devices. For flip-chip solder bump bonding, we developed a simple, inexpensive remetallization process called "electroless plating", which converts the aluminum bond pads of foundry-made complementary metal oxide semiconductor (CMOS) chips into solder-bondable and wire-bondable gold surfaces. We have applied for a patent on this remetallization technique. For fiber-pigtailed edge-emitting laser modules, we have studied the coupling characteristics of different types of lensed single-mode fibers including semispherically lensed fiber, cylindrically lensed fiber and conically lensed fiber. We have experimentally demonstrated 66% coupling efficiency with semispherically lensed fiber and 50% efficiency with conically lensed fibers. We have proposed and designed a packaging platform on which lensed fibers can be actively aligned to a laser and solder-attached reliably to the platform so that the alignment is retained. We have designed thin-film nichrome heaters on fused quartz platforms as local heat source to facilitate on-board solder alignment and attachment of fiber. The thermal performance of the heaters was simulated using finite element analysis tool ANSYS prior to fabrication. Using the heater's reworkability advantage, we have estimated the shift of the fiber due to solder shrinkage and introduced a pre-correction in the alignment process to restore optimum coupling efficiency close to 50% with conically lensed fibers. We have applied for a patent on this unique active alignment method through the University of Maryland's Technology Commercialization Office. Although we have mostly concentrated on active alignment platforms, we have proposed the idea of combining the passive alignment advantages of silicon optical benches to the on-board heater-assisted active alignment technique. This passive-active alignment process has the potential of cost-effective array packaging of edge-emitting devices.

QEPAS nitric oxide sensor based on a mid-infrared fiber-coupled quantum cascade laser

NASA Astrophysics Data System (ADS)

Ren, Wei; Shi, Chao; Wang, Zhen; Yao, Chenyu

2017-04-01

We report a quartz-enhanced photoacoustic sensor (QEPAS) for nitric oxide (NO) detection using a mid-infrared fibercoupled quantum cascade laser (QCL) near 5.2 μm. The QCL radiation was coupled into an InF3 fiber (100 μm core diameter) for light delivery to the quartz tuning fork, a tiny piezoelectric element converting the acoustic wave induced mechanical vibration to the gas-absorption associated electrical signal. This mid-infrared fiber can achieve nearly single-mode light delivery for the target wavelength. The off-beam configuration was adopted for the fiber-coupled detection considering its simpler installation, optical alignment and comparative sensitivity to the traditional on-beam setup.

Investigation of a tissue engineered tendon model by PS-OCT

NASA Astrophysics Data System (ADS)

Yang, Ying; Ahearne, Mark; Wimpenny, Ian; Guijarro-Leach, Juan; Torbet, Jim

2010-02-01

A few native tissues, such as tendon, skin and eye, possess highly organized collagenous matrices. In particular, the collagen fibers in tendon are organized into a hierarchical and unidirectional format, which gives rise to the high tissuespecific mechanical properties. This organization has been clearly revealed by a conventional polarized light microscope. The newly developed polarization-sensitive optical coherence tomography (PS-OCT) technique allows non-invasive visualization of birefringence images arising from orientated structures in a three dimensional format. Our previous studies of native tendon and tissue engineered tendon by PS-OCT demonstrate that tissue engineered tendon has a far less perfect collagen fiber organization than native tendon even under dynamic culture conditions. The purpose of this study is to use PS-OCT to assess the relationship between the degree of birefringence, collagen concentration and fiber density in model tendon tissues. The model tissue is constructed from an aligned collagen hydrogel and aligned polyester nanofibers. The effects of the diameter and density of the nanofibers and the collagen concentration in the model have been investigated. The alignment of collagen fibrils is induced by application of a high magnetic field during fibrillogenesis while aligned polyester nanofibers are manufactured using the electrospinning technique. It is found that the collagen concentration, the density and size of nanofiber bundles are the key parameters to produce birefringence in OCT images. The perfectly aligned collagen hydrogel with concentration as high as 4 mg/ml does not exhibit a birefringence image until the hydrogel has been compressed and concentrated. Aligned nanofiber bundles have demonstrated marginal birefringence in the absence of the collagen matrix. These studies enhance our understanding of how to control and optimize the parameters in tendon tissue engineering.

Analysis and experimental demonstration of conformal adaptive phase-locked fiber array for laser communications and beam projection applications

NASA Astrophysics Data System (ADS)

Liu, Ling

The primary goal of this research is the analysis, development, and experimental demonstration of an adaptive phase-locked fiber array system for free-space optical communications and laser beam projection applications. To our knowledge, the developed adaptive phase-locked system composed of three fiber collimators (subapertures) with tip-tilt wavefront phase control at each subaperture represents the first reported fiber array system that implements both phase-locking control and adaptive wavefront tip-tilt control capabilities. This research has also resulted in the following innovations: (a) The first experimental demonstration of a phase-locked fiber array with tip-tilt wave-front aberration compensation at each fiber collimator; (b) Development and demonstration of the fastest currently reported stochastic parallel gradient descent (SPGD) system capable of operation at 180,000 iterations per second; (c) The first experimental demonstration of a laser communication link based on a phase-locked fiber array; (d) The first successful experimental demonstration of turbulence and jitter-induced phase distortion compensation in a phase-locked fiber array optical system; (e) The first demonstration of laser beam projection onto an extended target with a randomly rough surface using a conformal adaptive fiber array system. Fiber array optical systems, the subject of this study, can overcome some of the draw-backs of conventional monolithic large-aperture transmitter/receiver optical systems that are usually heavy, bulky, and expensive. The primary experimental challenges in the development of the adaptive phased-locked fiber-array included precise (<5 microrad) alignment of the fiber collimators and development of fast (100kHz-class) phase-locking and wavefront tip-tilt control systems. The precise alignment of the fiber collimator array is achieved through a specially developed initial coarse alignment tool based on high precision piezoelectric picomotors and a dynamic fine alignment mechanism implemented with specially designed and manufactured piezoelectric fiber positioners. Phase-locking of the fiber collimators is performed by controlling the phases of the output beams (beamlets) using integrated polarization-maintaining (PM) fiber-coupled LiNbO3 phase shifters. The developed phase-locking controllers are based on either the SPGD algorithm or the multi-dithering technique. Subaperture wavefront phase tip-tilt control is realized using piezoelectric fiber positioners that are controlled using a computer-based SPGD controller. Both coherent (phase-locked) and incoherent beam combining in the fiber array system are analyzed theoretically and experimentally. Two special fiber-based beam-combining testbeds have been built to demonstrate the technical feasibility of phase-locking compensation prior to free-space operation. In addition, the reciprocity of counter-propagating beams in a phase-locked fiber array system has been investigated. Coherent beam combining in a phase-locking system with wavefront phase tip-tilt compensation at each subaperture is successfully demonstrated when laboratory-simulated turbulence and wavefront jitters are present in the propagation path of the beamlets. In addition, coherent beam combining with a non-cooperative extended target in the control loop is successfully demonstrated.

Anisotropic contraction of hydrogel reinforced by aligned fibers

NASA Astrophysics Data System (ADS)

Olvera de La Cruz, Monica; Liu, Shuangping

Hydrogel reinforced by aligned fibers can have strong anisotropic contraction or swelling behavior triggered by external stimuli, which has been largely employed in realizing soft actuators for artificial muscles as well as many biological systems. In this work, we investigate how this anisotropic behavior is controlled by the dimension of the embedded fibers and their reinforcement to the surrounding hydrogel. We describe the anisotropic contraction of hydrogels with rigid fibers using the Flory-Rehner thermodynamic model under periodic boundary conditions. It is found that a hydrogel reinforced by aligned fibers exhibits larger anisotropy when it is pre-stretched before contraction. Using finite element method, we further observe that the anisotropic contraction is dampened by reducing the fiber-fiber distance due to the finite size of the fibers.

Optimization of electrospun TSF nanofiber alignment and diameter to promote growth and migration of mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Qu, Jing; Zhou, Dandan; Xu, Xiaojing; Zhang, Feng; He, Lihong; Ye, Rong; Zhu, Ziyu; Zuo, Baoqi; Zhang, Huanxiang

2012-11-01

Silk fibroin scaffolds are a naturally derived biocompatible matrix with the potential for reconstructive surgical applications. In this study, tussah silk fibroin (TSF) nanofiber with different diameters (400 nm, 800 nm and 1200 nm) and alignment (random and aligned) were prepared by electrospinning, then the growth and migration of mesenchymal stem cells (MSCs) on these materials were further evaluated. CD90 immunofluorescence staining showed that fiber alignment exhibited a strong influence on the morphology of MSCs, indicating that the alignment of the scaffolds could determine the distribution of cells. Moreover, smaller diameter and aligned TSF scaffolds are more favorable to the growth of MSCs as compared with 800 nm and 1200 nm random TSF scaffolds. In addition, the increased migration speed and efficiency of MSCs induced by three-D TSF were verified, highlighting the guiding roles of TSF to the migrated MSCs. More importantly, 400 nm aligned TSF scaffolds dramatically improved cell migratory speed and further induced the most efficient migration of MSCs as compared with larger diameter TSF scaffolds. In conclusion, the data demonstrate that smaller diameter and aligned electrospun TSF represent valuable scaffolds for supporting and promoting MSCs growth and migration, thus raising the possibility of manipulating TSF scaffolds to enhance homing and therapeutic potential of MSCs in cellular therapy.

High-Throughput Image Analysis of Fibrillar Materials: A Case Study on Polymer Nanofiber Packing, Alignment, and Defects in Organic Field Effect Transistors.

PubMed

Persson, Nils E; Rafshoon, Joshua; Naghshpour, Kaylie; Fast, Tony; Chu, Ping-Hsun; McBride, Michael; Risteen, Bailey; Grover, Martha; Reichmanis, Elsa

2017-10-18

High-throughput discovery of process-structure-property relationships in materials through an informatics-enabled empirical approach is an increasingly utilized technique in materials research due to the rapidly expanding availability of data. Here, process-structure-property relationships are extracted for the nucleation, growth, and deposition of semiconducting poly(3-hexylthiophene) (P3HT) nanofibers used in organic field effect transistors, via high-throughput image analysis. This study is performed using an automated image analysis pipeline combining existing open-source software and new algorithms, enabling the rapid evaluation of structural metrics for images of fibrillar materials, including local orientational order, fiber length density, and fiber length distributions. We observe that microfluidic processing leads to fibers that pack with unusually high density, while sonication yields fibers that pack sparsely with low alignment. This is attributed to differences in their crystallization mechanisms. P3HT nanofiber packing during thin film deposition exhibits behavior suggesting that fibers are confined to packing in two-dimensional layers. We find that fiber alignment, a feature correlated with charge carrier mobility, is driven by increasing fiber length, and that shorter fibers tend to segregate to the buried dielectric interface during deposition, creating potentially performance-limiting defects in alignment. Another barrier to perfect alignment is the curvature of P3HT fibers; we propose a mechanistic simulation of fiber growth that reconciles both this curvature and the log-normal distribution of fiber lengths inherent to the fiber populations under consideration.

Molecular Orientation in Dry and Hydrated Cellulose Fibers: A Coherent Anti-Stokes Raman Scattering Microscopy Study

PubMed Central

Zimmerley, Maxwell; Younger, Rebecca; Valenton, Tiffany; Oertel, David C.; Ward, Jimmie L.; Potma, Eric O.

2012-01-01

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with spontaneous Raman scattering microspectroscopy and second harmonic generation (SHG) microscopy to interrogate the molecular alignment in dry and hydrated cellulose fibers. Two types of cellulose were investigated: natural cellulose I in cotton fibers and regenerated cellulose II in rayon fibers. On the basis of the orientation of the methylene symmetric stretching vibration, the molecular alignment of cellulose microfibrils is found to be conserved on the micrometer scale. Whereas the molecular orientation in cotton shows modest variability along the fiber, the alignment of the cellulose units in rayon is highly consistent throughout the fiber. The ordered alignment is retained upon fiber hydration. Upon hydration of the cellulose fibers, an anisotropic electronic contribution is observed, which indicates an ordered incorporation of water molecules into the fiber structure. The third-order and second-order electronic polarizability of cellulose I are directed along the axis of the polyglucan chain. No second-order optical response is observed in cellulose II, supporting the antiparallel arrangement of the polyglucan chains in regenerated cellulose. PMID:20684644

Aligning precisely polarization maintaining photonic crystal fiber and conventional single-mode fiber by online spectrum monitoring

NASA Astrophysics Data System (ADS)

Jiang, Ying; Zeng, Jie; Liang, Dakai; Ni, Xiaoyu; Luo, Wenyong

2013-06-01

The fibers aligning is very important in fusion splicing process. The core of polarization maintaining photonic crystal fiber(PM-PCF) can not be seen in the splicer due to microhole structure of its cross-section. So it is difficult to align precisely PM-PCF and conventional single-mode fiber(SMF).We demonstrate a novel method for aligning precisely PM-PCF and conventional SMF by online spectrum monitoring. Firstly, the light source of halogen lamp is connected to one end face of conventional SMF.Then align roughly one end face of PM-PCF and the other end face of conventional SMF by observing visible light in the other end face of PM-PCF. If there exists visible light, they are believed to align roughly. The other end face of PM-PCF and one end face of the other conventional SMF are aligned precisely in the other splicer by online spectrum monitoring. Now the light source of halogen lamp is changed into a broadband light source with 52nm wavelength range.The other end face of the other conventional SMF is connected to an optical spectrum analyzer.They are translationally and rotationally adjusted in the splicer by monitoring spectrum. When the transmission spectrum power is maximum, the aligning is precise.

Tolerancing the alignment of large-core optical fibers, fiber bundles and light guides using a Fourier approach.

PubMed

Sawyer, Travis W; Petersburg, Ryan; Bohndiek, Sarah E

2017-04-20

Optical fiber technology is found in a wide variety of applications to flexibly relay light between two points, enabling information transfer across long distances and allowing access to hard-to-reach areas. Large-core optical fibers and light guides find frequent use in illumination and spectroscopic applications, for example, endoscopy and high-resolution astronomical spectroscopy. Proper alignment is critical for maximizing throughput in optical fiber coupling systems; however, there currently are no formal approaches to tolerancing the alignment of a light-guide coupling system. Here, we propose a Fourier alignment sensitivity (FAS) algorithm to determine the optimal tolerances on the alignment of a light guide by computing the alignment sensitivity. The algorithm shows excellent agreement with both simulated and experimentally measured values and improves on the computation time of equivalent ray-tracing simulations by two orders of magnitude. We then apply FAS to tolerance and fabricate a coupling system, which is shown to meet specifications, thus validating FAS as a tolerancing technique. These results indicate that FAS is a flexible and rapid means to quantify the alignment sensitivity of a light guide, widely informing the design and tolerancing of coupling systems.

Tolerancing the alignment of large-core optical fibers, fiber bundles and light guides using a Fourier approach

PubMed Central

Sawyer, Travis W.; Petersburg, Ryan; Bohndiek, Sarah E.

2017-01-01

Optical fiber technology is found in a wide variety of applications to flexibly relay light between two points, enabling information transfer across long distances and allowing access to hard-to-reach areas. Large-core optical fibers and light guides find frequent use in illumination and spectroscopic applications; for example, endoscopy and high-resolution astronomical spectroscopy. Proper alignment is critical for maximizing throughput in optical fiber coupling systems, however, there currently are no formal approaches to tolerancing the alignment of a light guide coupling system. Here, we propose a Fourier Alignment Sensitivity (FAS) algorithm to determine the optimal tolerances on the alignment of a light guide by computing the alignment sensitivity. The algorithm shows excellent agreement with both simulated and experimentally measured values and improves on the computation time of equivalent ray tracing simulations by two orders of magnitude. We then apply FAS to tolerance and fabricate a coupling system, which is shown to meet specifications, thus validating FAS as a tolerancing technique. These results indicate that FAS is a flexible and rapid means to quantify the alignment sensitivity of a light guide, widely informing the design and tolerancing of coupling systems. PMID:28430250

Synthesis and Fabrication of Nanocomposite Fibers of Collagen-Cellulose Nanocrystals by Coelectrocompaction.

PubMed

Cudjoe, Elvis; Younesi, Mousa; Cudjoe, Edward; Akkus, Ozan; Rowan, Stuart J

2017-04-10

An electrochemical process has been used to compact cellulose nanocrystals (CNC) and access aligned micron-sized CNC fibers. Placing a current across aqueous solutions of carboxylic acid functionalized CNCs (t-CNC-COOH) or carboxylic acid/primary amine functionalized CNCs (t-CNC-COOH-NH 2 ) creates a pH gradient between the electrodes, which results in the migration and concentration of the CNC fibers at their isoelectric point. By matching the carboxylic acid/amine ratio of CNCs and collagen (ca. 30:70 carboxylic acid:amine ratio), it is possible to coelectrocompact both nanofibers and access aligned nanocomposite fibers. t-CNC-COOH-NH 2 /collagen fibers showed a maximum increase in mechanical properties at 5 wt % of t-CNC-COOH-NH 2 . Compared to collagen/CNC films which have no alignment in the plane of the films, the tensile properties of the aligned fibers show a significant enhancement in the wet mechanical properties (40 MPa vs 230 MPa) for the 5 wt % of t-CNC-COOH-NH 2 /collagen films and fiber, respectively.

Fitting-free algorithm for efficient quantification of collagen fiber alignment in SHG imaging applications.

PubMed

Hall, Gunnsteinn; Liang, Wenxuan; Li, Xingde

2017-10-01

Collagen fiber alignment derived from second harmonic generation (SHG) microscopy images can be important for disease diagnostics. Image processing algorithms are needed to robustly quantify the alignment in images with high sensitivity and reliability. Fourier transform (FT) magnitude, 2D power spectrum, and image autocorrelation have previously been used to extract fiber information from images by assuming a certain mathematical model (e.g. Gaussian distribution of the fiber-related parameters) and fitting. The fitting process is slow and fails to converge when the data is not Gaussian. Herein we present an efficient constant-time deterministic algorithm which characterizes the symmetricity of the FT magnitude image in terms of a single parameter, named the fiber alignment anisotropy R ranging from 0 (randomized fibers) to 1 (perfect alignment). This represents an important improvement of the technology and may bring us one step closer to utilizing the technology for various applications in real time. In addition, we present a digital image phantom-based framework for characterizing and validating the algorithm, as well as assessing the robustness of the algorithm against different perturbations.

Mechanical function near defects in an aligned nanofiber composite is preserved by inclusion of disorganized layers: Insight into meniscus structure and function.

PubMed

Bansal, Sonia; Mandalapu, Sai; Aeppli, Céline; Qu, Feini; Szczesny, Spencer E; Mauck, Robert L; Zgonis, Miltiadis H

2017-07-01

The meniscus is comprised of circumferentially aligned fibers that resist the tensile forces within the meniscus (i.e., hoop stress) that develop during loading of the knee. Although these circumferential fibers are severed by radial meniscal tears, tibial contact stresses do not increase until the tear reaches ∼90% of the meniscus width, suggesting that the severed circumferential fibers still bear load and maintain the mechanical functionality of the meniscus. Recent data demonstrates that the interfibrillar matrix can transfer strain energy to disconnected fibrils in tendon fascicles. In the meniscus, interdigitating radial tie fibers, which function to stabilize and bind the circumferential fibers together, are hypothesized to function in a similar manner by transmitting load to severed circumferential fibers near a radial tear. To test this hypothesis, we developed an engineered fibrous analog of the knee meniscus using poly(ε-caprolactone) to create aligned scaffolds with variable amounts of non-aligned elements embedded within the scaffold. We show that the tensile properties of these scaffolds are a function of the ratio of aligned to non-aligned elements, and change in a predictable fashion following a simple mixture model. When measuring the loss of mechanical function in scaffolds with a radial tear, compared to intact scaffolds, the decrease in apparent linear modulus was reduced in scaffolds containing non-aligned layers compared to purely aligned scaffolds. Increased strains in areas adjacent to the defect were also noted in composite scaffolds. These findings indicate that non-aligned (disorganized) elements interspersed within an aligned network can improve overall mechanical function by promoting strain transfer to nearby disconnected fibers. This finding supports the notion that radial tie fibers may similarly promote tear tolerance in the knee meniscus, and will direct changes in clinical practice and provide guidance for tissue engineering strategies. The meniscus is a complex fibrous tissue, whose architecture includes radial tie fibers that run perpendicular to and interdigitate with the predominant circumferential fibers. We hypothesized that these radial elements function to preserve mechanical function in the context of interruption of circumferential bundles, as would be the case in a meniscal tear. To test this hypothesis, we developed a biomaterial analog containing disorganized layers enmeshed regularly throughout an otherwise aligned network. Using this material formulation, we showed that strain transmission is improved in the vicinity of defects when disorganized fiber layers were present. This supports the idea that radial elements within the meniscus improve function near a tear, and will guide future clinical interventions and the development of engineered replacements. Copyright © 2017 Acta Materialia Inc. All rights reserved.

Fiber alignment apparatus and method

DOEpatents

Kravitz, Stanley H.; Warren, Mial Evans; Snipes, Jr., Morris Burton; Armendariz, Marcelino Guadalupe; Word, V., James Cole

1997-01-01

A fiber alignment apparatus includes a micro-machined nickel spring that captures and locks arrays of single mode fibers into position. The design consists of a movable nickel leaf shaped spring and a fixed pocket where fibers are held. The fiber is slid between the spring and a fixed block, which tensions the spring. When the fiber reaches the pocket, it automatically falls into the pocket and is held by the pressure of the leaf spring.

Fiber alignment apparatus and method

DOEpatents

Kravitz, S.H.; Warren, M.E.; Snipes, M.B. Jr.; Armendariz, M.G.; Word, J.C. V

1997-08-19

A fiber alignment apparatus includes a micro-machined nickel spring that captures and locks arrays of single mode fibers into position. The design consists of a movable nickel leaf shaped spring and a fixed pocket where fibers are held. The fiber is slid between the spring and a fixed block, which tensions the spring. When the fiber reaches the pocket, it automatically falls into the pocket and is held by the pressure of the leaf spring. 8 figs.

Passively aligned multichannel fiber-pigtailing of planar integrated optical waveguides

NASA Astrophysics Data System (ADS)

Kremmel, Johannes; Lamprecht, Tobias; Crameri, Nino; Michler, Markus

2017-02-01

A silicon device to simplify the coupling of multiple single-mode fibers to embedded single-mode waveguides has been developed. The silicon device features alignment structures that enable a passive alignment of fibers to integrated waveguides. For passive alignment, precisely machined V-grooves on a silicon device are used and the planar lightwave circuit board features high-precision structures acting as a mechanical stop. The approach has been tested for up to eight fiber-to-waveguide connections. The alignment approach, the design, and the fabrication of the silicon device as well as the assembly process are presented. The characterization of the fiber-to-waveguide link reveals total coupling losses of (0.45±0.20 dB) per coupling interface, which is significantly lower than the values reported in earlier works. Subsequent climate tests reveal that the coupling losses remain stable during thermal cycling but increases significantly during an 85°C/85 Rh-test. All applied fabrication and bonding steps have been performed using standard MOEMS fabrication and packaging processes.

Diagnostic apparatus and method for use in the alignment of one or more laser means onto a fiber optics interface

DOEpatents

Johnson, Steve A.; Shannon, Robert R.

1987-01-01

Diagnostic apparatus for use in determining the proper alignment of a plurality of laser beams onto a fiber optics interface is disclosed. The apparatus includes a lens assembly which serves two functions, first to focus a plurality of laser beams onto the fiber optics interface, and secondly to reflect and image the interface using scattered light to a monitor means. The monitor means permits indirect observation of the alignment or focusing of the laser beams onto the fiber optics interface.

Diagnostic apparatus and method for use in the alignment of one or more laser means onto a fiber optics interface

DOEpatents

Johnson, S.A.; Shannon, R.R.

1985-01-18

Diagnostic apparatus for use in determining the proper alignment of a plurality of laser beams onto a fiber optics interface is disclosed. The apparatus includes a lens assembly which serves two functions, first to focus a plurality of laser beams onto the fiber optics interface, and secondly to reflect and image the interface using scattered light to a monitor means. The monitor means permits indirect observation of the alignment or focusing of the laser beams onto the fiber optics interface.

Package for integrated optic circuit and method

DOEpatents

Kravitz, Stanley H.; Hadley, G. Ronald; Warren, Mial E.; Carson, Richard F.; Armendariz, Marcelino G.

1998-01-01

A structure and method for packaging an integrated optic circuit. The package comprises a first wall having a plurality of microlenses formed therein to establish channels of optical communication with an integrated optic circuit within the package. A first registration pattern is provided on an inside surface of one of the walls of the package for alignment and attachment of the integrated optic circuit. The package in one embodiment may further comprise a fiber holder for aligning and attaching a plurality of optical fibers to the package and extending the channels of optical communication to the fibers outside the package. In another embodiment, a fiber holder may be used to hold the fibers and align the fibers to the package. The fiber holder may be detachably connected to the package.

Package for integrated optic circuit and method

DOEpatents

Kravitz, S.H.; Hadley, G.R.; Warren, M.E.; Carson, R.F.; Armendariz, M.G.

1998-08-04

A structure and method are disclosed for packaging an integrated optic circuit. The package comprises a first wall having a plurality of microlenses formed therein to establish channels of optical communication with an integrated optic circuit within the package. A first registration pattern is provided on an inside surface of one of the walls of the package for alignment and attachment of the integrated optic circuit. The package in one embodiment may further comprise a fiber holder for aligning and attaching a plurality of optical fibers to the package and extending the channels of optical communication to the fibers outside the package. In another embodiment, a fiber holder may be used to hold the fibers and align the fibers to the package. The fiber holder may be detachably connected to the package. 6 figs.

Numerical prediction of flow induced fibers orientation in injection molded polymer composites

NASA Astrophysics Data System (ADS)

Oumer, A. N.; Hamidi, N. M.; Mat Sahat, I.

2015-12-01

Since the filling stage of injection molding process has important effect on the determination of the orientation state of the fibers, accurate analysis of the flow field for the mold filling stage becomes a necessity. The aim of the paper is to characterize the flow induced orientation state of short fibers in injection molding cavities. A dog-bone shaped model is considered for the simulation and experiment. The numerical model for determination of the fibers orientation during mold-filling stage of injection molding process was solved using Computational Fluid Dynamics (CFD) software called MoldFlow. Both the simulation and experimental results showed that two different regions (or three layers of orientation structures) across the thickness of the specimen could be found: a shell region which is near to the mold cavity wall, and a core region at the middle of the cross section. The simulation results support the experimental observations that for thin plates the probability of fiber alignment to the flow direction near the mold cavity walls is high but low at the core region. It is apparent that the results of this study could assist in decisions regarding short fiber reinforced polymer composites.

Fabrication and design of bioactive agent coated, highly-aligned electrospun matrices for nerve tissue engineering: Preparation, characterization and application

NASA Astrophysics Data System (ADS)

Lee, Sang Jin; Heo, Min; Lee, Donghyun; Heo, Dong Nyoung; Lim, Ho-Nam; Kwon, Il Keun

2017-12-01

In this study, we designed highly-aligned thermoplastic polycarbonate urethane (PCU) fibrous scaffolds coated with bioactive compounds, such as Poly-L-Lysine (PLL) and Poly-L-Ornithine (PLO), to enhance cellular adhesion and directivity. These products were characterized by scanning electron microscope (SEM) analysis which demonstrated that highly aligned fiber strands were formed without beads when coated onto a mandrel rotating at 1800 rpm. During in vitro cell test, PLO-coated, aligned PCU scaffolds were found to have significantly higher proliferation rates than PLL coated and bare PCU scaffolds. Interestingly, dental pulp stem cells (DPSCs) were observed to stretch along the longitudinal axis parallel to the cell direction on highly aligned scaffolds. These results clearly confirm that our strategy may suggest a useful paradigm by inducing neural tissue repair as a means to remodeling and healing of tissue for restorative procedures in neural tissue engineering.

Additive manufacturing of short and mixed fibre-reinforced polymer

DOEpatents

Lewicki, James; Duoss, Eric B.; Rodriguez, Jennifer Nicole; Worsley, Marcus A.; King, Michael J.

2018-01-09

Additive manufacturing of a fiber-reinforced polymer (FRP) product using an additive manufacturing print head; a reservoir in the additive manufacturing print head; short carbon fibers in the reservoir, wherein the short carbon fibers are randomly aligned in the reservoir; an acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin in the reservoir, wherein the short carbon fibers are dispersed in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin; a tapered nozzle in the additive manufacturing print head operatively connected to the reservoir, the tapered nozzle produces an extruded material that forms the fiber-reinforced polymer product; baffles in the tapered nozzle that receive the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin with the short carbon fibers dispersed in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin; and a system for driving the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin with the short carbon fibers dispersed in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin from the reservoir through the tapered nozzle wherein the randomly aligned short carbon fibers in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin are aligned by the baffles and wherein the extruded material has the short carbon fibers aligned in the acrylate, methacrylate, epoxy, cyanate ester or isocyanate resin that forms the fiber-reinforced polymer product.

Fiber optics welder having movable aligning mirror

DOEpatents

Higgins, Robert W.; Robichaud, Roger E.

1981-01-01

A system for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45.degree. angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

Osteogenesis of human adipose-derived stem cells on hydroxyapatite-mineralized poly(lactic acid) nanofiber sheets.

PubMed

Kung, Fu-Chen; Lin, Chi-Chang; Lai, Wen-Fu T

2014-12-01

Electrospun fiber sheets with various orientations (random, partially aligned, and aligned) and smooth and roughened casted membranes were prepared. Hydroxyapatite (HA) crystals were in situ formed on these material surfaces via immersion in 10× simulated body fluid solution. The size and morphology of the resulting fibers were examined using scanning electron microscopy. The average diameter of the fibers ranged from 225±25 to 1050±150 nm depending on the electrospinning parameters. Biological experiment results show that human adipose-derived stem cells exhibit different adhesion and osteogenic differentiation on the three types of fiber. The cell proliferation and osteogenic differentiation were best on the aligned fibers. Similar results were found for phosphorylated focal adhesion kinase expression. Electrospun poly(lactic acid) aligned fibers mineralized with HA crystals provide a good environment for cell growth and osteogenic differentiation and thus have great potential in the tissue engineering field. Copyright © 2014 Elsevier B.V. All rights reserved.

Rod-Shaped Neural Units for Aligned 3D Neural Network Connection.

PubMed

Kato-Negishi, Midori; Onoe, Hiroaki; Ito, Akane; Takeuchi, Shoji

2017-08-01

This paper proposes neural tissue units with aligned nerve fibers (called rod-shaped neural units) that connect neural networks with aligned neurons. To make the proposed units, 3D fiber-shaped neural tissues covered with a calcium alginate hydrogel layer are prepared with a microfluidic system and are cut in an accurate and reproducible manner. These units have aligned nerve fibers inside the hydrogel layer and connectable points on both ends. By connecting the units with a poly(dimethylsiloxane) guide, 3D neural tissues can be constructed and maintained for more than two weeks of culture. In addition, neural networks can be formed between the different neural units via synaptic connections. Experimental results indicate that the proposed rod-shaped neural units are effective tools for the construction of spatially complex connections with aligned nerve fibers in vitro. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of uniaxially aligned TiO2 ultrafine fibers by electrospinning.

PubMed

Nien, Yu-Hsun; Tsai, Yan-Sheng; Wang, Jia-Yi; Syu, Shu-Ping

2012-11-01

TiO2 nanofibers are often produced by electrospinning using a collector consisting of two parallel electrodes. In this work, a high speed rotating drum was used as a collector to produce uniaxially aligned TiO2 ultrafine fibers. The apparatus to manufacture uniaxially aligned TiO2 ultrafine fiber consisted of a high-speed roller, a high-voltage power supply, a controllable syringe pump and a syringe. Titanium (IV) isopropoxide and polyvinylpyrrolidone were used as precursor and auxiliary, respectively. Titanium (IV) isopropoxide and polyvinylpyrrolidone were well mixed with other essential reagents to form the polymer solution. The polymer solution was poured into the syringe and pumped at various flow rates. The electrospun ultrafine fibers collected on the roller were heat treated up to 600 degrees C and the uniaxially aligned TiO2 ultrafine fibers were formed and characterized using scanning electron microscope and X-ray diffraction.

Femtosecond laser inscription of optical circuits in the cladding of optical fibers

NASA Astrophysics Data System (ADS)

Grenier, Jason R.

The aim of this dissertation was to address the question of whether the cladding of single-mode fibers (SMFs) could be modified to enable optical fibers to serve as a more integrated, highly functional platform for optical circuit devices that can efficiently interconnect with the pre-existing fiber core waveguide. The approach adopted in this dissertation was to employ femtosecond laser direct writing (FLDW), an inherently 3D fabrication technique that harnesses non-linear laser-material interactions to modify the fused silica fiber cladding. A fiber mounting and alignment technique was developed along with oil-immersion focusing to address the strong aberrations caused by the cylindrical fiber shape. The development of real-time device monitoring during the FLDW was instrumental to overcome the acute coupling sensitivity to laser alignment errors of +/-1 ?m positional uncertainty, and thereby opened a new practical direction for the precise fabrication of optical devices inside optical fibers. These powerful and flexible laser fabrication and characterization techniques were successfully employed to optimize optical waveguiding devices positioned within the core and cladding of optical fibers. X-, S-Bend, and directional couplers were developed to enable efficient coupling between the laser-formed cladding devices and the pre-existing core waveguide, enabling up to 62% power transfer over bandwidths up to 300 nm at telecommunication wavelengths. Precise alignment of femtosecond laser modification tracks were positioned inside or near the core waveguide of SMFs was further shown to enable a flexible reshaping of the optical properties to create multimode guiding sections arbitrarily along the fiber length. This core waveguide modification facilitated the precise formation of multimode interferometers along the core waveguide to precisely tailor the modal profiles, and control the spectral and polarization response. In-fiber multimode interference (MMI) splitters and couplers were fabricated with coupling ratios from 2% to 50% over a broad 350 nm bandwidth across the telecommunication band. Laser-induced birefringence was harnessed to generate polarization dependent MMI devices for strong polarization filtering (24 dB isolation), or polarization selective taps with up to 50% tapping efficiency over a 25 nm bandwidth. This dissertation is therefore the first demonstration of femtosecond laser direct writing as a flexible and monolithic means of embedding and integrating highly functional optical circuit devices within the cladding of optical fibers that can interconnect efficiently with the pre-existing fiber core waveguide. These developments represent a significant technological advancement for creating new 3D photonic integrated microsystems within the cladding of optical fibers and underpins a new technological platform of fiber cladding photonics.

Aligning Arrays of Lenses and Single-Mode Optical Fibers

NASA Technical Reports Server (NTRS)

Liu, Duncan

2004-01-01

A procedure now under development is intended to enable the precise alignment of sheet arrays of microscopic lenses with the end faces of a coherent bundle of as many as 1,000 single-mode optical fibers packed closely in a regular array (see Figure 1). In the original application that prompted this development, the precise assembly of lenses and optical fibers serves as a single-mode spatial filter for a visible-light nulling interferometer. The precision of alignment must be sufficient to limit any remaining wavefront error to a root-mean-square value of less than 1/10 of a wavelength of light. This wavefront-error limit translates to requirements to (1) ensure uniformity of both the lens and fiber arrays, (2) ensure that the lateral distance from the central axis of each lens and the corresponding optical fiber is no more than a fraction of a micron, (3) angularly align the lens-sheet planes and the fiber-bundle end faces to within a few arc seconds, and (4) axially align the lenses and the fiber-bundle end faces to within tens of microns of the focal distance. Figure 2 depicts the apparatus used in the alignment procedure. The beam of light from a Zygo (or equivalent) interferometer is first compressed by a ratio of 20:1 so that upon its return to the interferometer, the beam will be magnified enough to enable measurement of wavefront quality. The apparatus includes relay lenses that enable imaging of the arrays of microscopic lenses in a charge-coupled-device (CCD) camera that is part of the interferometer. One of the arrays of microscopic lenses is mounted on a 6-axis stage, in proximity to the front face of the bundle of optical fibers. The bundle is mounted on a separate stage. A mirror is attached to the back face of the bundle of optical fibers for retroreflection of light. When a microscopic lens and a fiber are aligned with each other, the affected portion of the light is reflected back by the mirror, recollimated by the microscopic lens, transmitted through the relay lenses and the beam compressor/expander, then split so that half goes to a detector and half to the interferometer. The output of the detector is used as a feedback control signal for the six-axis stage to effect alignment.

Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

NASA Astrophysics Data System (ADS)

Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

2012-01-01

We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.

Hollow fiber clinostat for simulating microgravity in cell culture

NASA Technical Reports Server (NTRS)

Rhodes, Percy H. (Inventor); Miller, Teresa Y. (Inventor); Snyder, Robert S. (Inventor)

1992-01-01

A clinostat for simulating microgravity on cell systems carried in a fiber fixedly mounted in a rotatable culture vessel is disclosed. The clinostat is rotated horizontally along its longitudinal axis to simulate microgravity or vertically as a control response. Cells are injected into the fiber and the ends of the fiber are sealed and secured to spaced end pieces of a fiber holder assembly which consists of the end pieces, a hollow fiber, a culture vessel, and a tension spring with three alignment pins. The tension spring is positioned around the culture vessel with its ends abutting the end pieces for alignment of the spring. After the fiber is secured, the spring is decompressed to maintain tension on the fiber while it is being rotated. This assures that the fiber remains aligned along the axis of rotation. The fiber assembly is placed in the culture vessel and culture medium is added. The culture vessel is then inserted into the rotatable portion of the clinostat and subjected to rotate at selected rpms. The internal diameter of the hollow fiber determines the distance the cells are from the axis of rotation.

Multiscale mechanisms of nutritionally induced property variation in spider silks.

PubMed

Blamires, Sean J; Nobbs, Madeleine; Martens, Penny J; Tso, I-Min; Chuang, Wei-Tsung; Chang, Chung-Kai; Sheu, Hwo-Shuenn

2018-01-01

Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales. Our analyses found that the properties of each spider's silk varied differently in response to variations in their protein intake. We found changes in the crystalline and non-crystalline nanostructures to play specific roles in inducing the property variations we found. Across treatment MaSp expression patterns differed in each of the five species. We found that in most species MaSp expression and amino acid composition variations did not conform with our predictions based on a traditional MaSp expression model. In general, changes to the silk's alanine and proline compositions influenced the alignment of the proteins within the silk's amorphous region, which influenced silk extensibility and toughness. Variations in structural alignment in the crystalline and non-crystalline regions influenced ultimate strength independent of genetic expression. Our study provides the deepest insights thus far into the mechanisms of how MA silk properties vary from gene expression to nanostructure formations to fiber mechanics. Such knowledge is imperative for promoting the production of synthetic silk fibers.

Increased dermal collagen bundle alignment in systemic sclerosis is associated with a cell migration signature and role of Arhgdib in directed fibroblast migration on aligned ECMs

PubMed Central

Lafyatis, Robert; Burkly, Linda C.

2017-01-01

Systemic sclerosis (SSc) is a devastating disease affecting the skin and internal organs. Dermal fibrosis manifests early and Modified Rodnan Skin Scores (MRSS) correlate with disease progression. Transcriptomics of SSc skin biopsies suggest the role of the in vivo microenvironment in maintaining the pathological myofibroblasts. Therefore, defining the structural changes in dermal collagen in SSc patients could inform our understanding of fibrosis pathogenesis. Here, we report a method for quantitative whole-slide image analysis of dermal collagen from SSc patients, and our findings of more aligned dermal collagen bundles in diffuse cutaneous SSc (dcSSc) patients. Using the bleomycin-induced mouse model of SSc, we identified a distinct high dermal collagen bundle alignment gene signature, characterized by a concerted upregulation in cell migration, adhesion, and guidance pathways, and downregulation of spindle, replication, and cytokinesis pathways. Furthermore, increased bundle alignment induced a cell migration gene signature in fibroblasts in vitro, and these cells demonstrated increased directed migration on aligned ECM fibers that is dependent on expression of Arhgdib (Rho GDP-dissociation inhibitor 2). Our results indicate that increased cell migration is a cellular response to the increased collagen bundle alignment featured in fibrotic skin. Moreover, many of the cell migration genes identified in our study are shared with human SSc skin and may be new targets for therapeutic intervention. PMID:28662216

Environmental Aspects of Use of Recycled Carbon Fiber Composites in Automotive Applications.

PubMed

Meng, Fanran; McKechnie, Jon; Turner, Thomas; Wong, Kok H; Pickering, Stephen J

2017-11-07

The high cost and energy intensity of virgin carbon fiber manufacture provides an opportunity to recover substantial value from carbon fiber reinforced plastic wastes. In this study, we assess the life cycle environmental implications of recovering carbon fiber and producing composite materials as substitutes for conventional and proposed lightweight materials in automotive applications (e.g., steel, aluminum, virgin carbon fiber). Key parameters for the recycled carbon fiber materials, including fiber volume fraction and fiber alignment, are investigated to identify beneficial uses of recycled carbon fiber in the automotive sector. Recycled carbon fiber components can achieve the lowest life cycle environmental impacts of all materials considered, although the actual impact is highly dependent on the design criteria (λ value) of the specific component. Low production impacts associated with recycled carbon fiber components are observed relative to lightweight competitor materials (e.g., aluminum, virgin carbon fiber reinforced plastic). In addition, recycled carbon fiber components have low in-use energy use due to mass reductions and associated reduction in mass-induced fuel consumption. The results demonstrate environmental feasibility of the CFRP recycling materials, supporting the emerging commercialization of CF recycling technologies and identifying significant potential market opportunities in the automotive sector.

Computational modeling for prediction of the shear stress of three-dimensional isotropic and aligned fiber networks.

PubMed

Park, Seungman

2017-09-01

Interstitial flow (IF) is a creeping flow through the interstitial space of the extracellular matrix (ECM). IF plays a key role in diverse biological functions, such as tissue homeostasis, cell function and behavior. Currently, most studies that have characterized IF have focused on the permeability of ECM or shear stress distribution on the cells, but less is known about the prediction of shear stress on the individual fibers or fiber networks despite its significance in the alignment of matrix fibers and cells observed in fibrotic or wound tissues. In this study, I developed a computational model to predict shear stress for different structured fibrous networks. To generate isotropic models, a random growth algorithm and a second-order orientation tensor were employed. Then, a three-dimensional (3D) solid model was created using computer-aided design (CAD) software for the aligned models (i.e., parallel, perpendicular and cubic models). Subsequently, a tetrahedral unstructured mesh was generated and flow solutions were calculated by solving equations for mass and momentum conservation for all models. Through the flow solutions, I estimated permeability using Darcy's law. Average shear stress (ASS) on the fibers was calculated by averaging the wall shear stress of the fibers. By using nonlinear surface fitting of permeability, viscosity, velocity, porosity and ASS, I devised new computational models. Overall, the developed models showed that higher porosity induced higher permeability, as previous empirical and theoretical models have shown. For comparison of the permeability, the present computational models were matched well with previous models, which justify our computational approach. ASS tended to increase linearly with respect to inlet velocity and dynamic viscosity, whereas permeability was almost the same. Finally, the developed model nicely predicted the ASS values that had been directly estimated from computational fluid dynamics (CFD). The present computational models will provide new tools for predicting accurate functional properties and designing fibrous porous materials, thereby significantly advancing tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-time high-resolution measurement of collagen alignment in dynamically loaded soft tissue.

PubMed

York, Timothy; Kahan, Lindsey; Lake, Spencer P; Gruev, Viktor

2014-06-01

A technique for creating maps of the direction and strength of fiber alignment in collagenous soft tissues is presented. The method uses a division of focal plane polarimeter to measure circularly polarized light transmitted through the tissue. The architecture of the sensor allows measurement of the retardance and fiber alignment at the full frame rate of the sensor without any moving optics. The technique compares favorably to the standard method of using a rotating polarizer. How the new technique enables real-time capture of the full angular spread of fiber alignment and retardance under various cyclic loading conditions is illustrated.

Multianode Photomultiplier Tube Alignment for the MINERvA Experiment at Fermilab

NASA Astrophysics Data System (ADS)

Bruno, Jorge

2006-10-01

The MINERvA experiment (Main INjector ExpeRiment vA) at FNAL will study the neutrino-nucleon and neutrino-nucleus interaction. The light collection from the detector will be done via optic fibers using Hamamatsu H8804 64-channel photomultiplier tubes (PMT). Each PMT channel needs to be precisely aligned with the corresponding optic fiber. The MINERvA PMT optical boxes contain precision machined optic ``cookies'' which capture the 8x8 array of optic fibers. Each PMT-cookie pair needs to be aligned as precisely as possible. This contribution will describe the alignment setup and procedure implemented at James Madison University.

3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

NASA Astrophysics Data System (ADS)

Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; Worsley, Marcus A.; Wu, Amanda S.; Kanarska, Yuliya; Horn, John D.; Duoss, Eric B.; Ortega, Jason M.; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A.; King, Michael J.

2017-03-01

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties.

PubMed

Lewicki, James P; Rodriguez, Jennifer N; Zhu, Cheng; Worsley, Marcus A; Wu, Amanda S; Kanarska, Yuliya; Horn, John D; Duoss, Eric B; Ortega, Jason M; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A; King, Michael J

2017-03-06

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

PubMed Central

Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; Worsley, Marcus A.; Wu, Amanda S.; Kanarska, Yuliya; Horn, John D.; Duoss, Eric B.; Ortega, Jason M.; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A.; King, Michael J.

2017-01-01

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response. PMID:28262669

A New Three-Dimensional High-Accuracy Automatic Alignment System For Single-Mode Fibers

NASA Astrophysics Data System (ADS)

Yun-jiang, Rao; Shang-lian, Huang; Ping, Li; Yu-mei, Wen; Jun, Tang

1990-02-01

In order to achieve the low-loss splices of single-mode fibers, a new three-dimension high-accuracy automatic alignment system for single -mode fibers has been developed, which includes a new-type three-dimension high-resolution microdisplacement servo stage driven by piezoelectric elements, a new high-accuracy measurement system for the misalignment error of the fiber core-axis, and a special single chip microcomputer processing system. The experimental results show that alignment accuracy of ±0.1 pin with a movable stroke of -±20μm has been obtained. This new system has more advantages than that reported.

Design and fabrication of advanced fiber alignment structures for field-installable fiber connectors

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Vervaeke, Michael; Sánchez Martínez, Alberto; Beri, Stefano; Debaes, Christof; Watté, Jan; Thienpont, Hugo

2012-06-01

Fiber-To-The-Home (FTTH) networks have been adopted as a potential replacement of traditional electrical connections for the 'last mile' transmission of information at bandwidths over 1Gb/s. However, the success and adoption of optical access networks critically depend on the quality and reliability of connections between optical fibers. In particular a further reduction of insertion loss of field-installable connectors must be achieved without a significant increase in component cost. This requires precise alignment of fibers that can differ in terms of ellipticity, eccentricity or diameter and seems hardly achievable using today's widespread ferrule-based alignment systems. Novel low-cost structures for bare fiber alignment with outstanding positioning accuracies are strongly desired as they would allow reducing loss beyond the level achievable with ferrule-bore systems. However, the realization of such alignment system is challenging as it should provide sufficient force to position the fiber with sub-micron accuracy required in positioning the fiber. In this contribution we propose, design and prototype a bare-fiber alignment system which makes use of deflectable/compressible micro-cantilevers. Such cantilevers behave as springs and provide self-centering functionality to the structure. Simulations of the mechanical properties of the cantilevers are carried out in order to get an analytical approximation and a mathematical model of the spring constant and stress in the structure. Elastic constants of the order of 104 to 105N/m are found out to be compatible with a proof stress of 70 MPa. Finally a first self-centering structure is prototyped in PMMA using our Deep Proton Writing technology. The spring constants of the fabricated cantilevers are in the range of 4 to 6 × 104N/m and the stress is in the range 10 to 20 MPa. These self-centering structures have the potential to become the basic building blocks for a new generation of field-installable connectors.

Patterned Cell Alignment in Response to Macroscale Curvature

NASA Astrophysics Data System (ADS)

Bade, Nathan; Kamien, Randall; Assoian, Richard; Stebe, Kathleen

The formation of spatial behavior patterns in tissues is a long-standing problem in biology. Decades of research have focused on understanding how biochemical signaling and morphogen gradients establish cell patterns during development and tissue morphogenesis. Here, we show that geometry and physical cues can drive organization and pattern formation. We find that mouse embryonic fibroblasts and human vascular smooth muscle cells sense curvature differently when in monolayers than when isolated on surfaces with various amounts of Gaussian curvature. While the long, apical stress fibers within these cells align in the direction of minimum curvature on cylindrical substrates, a subpopulation of stress fibers beneath the nucleus aligns in the circumferential direction and is bent maximally. We find dramatic reorganization of the actin cytoskeleton upon activation of RhoA, which is associated with increased contractility of the fibers. Thus, stress fiber alignment is likely a result of a complex balance between energy penalties associated with stress fiber bending, contractility, and the dynamics of F-actin assembly.

Co-effects of matrix low elasticity and aligned topography on stem cell neurogenic differentiation and rapid neurite outgrowth

NASA Astrophysics Data System (ADS)

Yao, Shenglian; Liu, Xi; Yu, Shukui; Wang, Xiumei; Zhang, Shuming; Wu, Qiong; Sun, Xiaodan; Mao, Haiquan

2016-05-01

The development of novel biomaterials that deliver precise regulatory signals to direct stem cell fate for nerve regeneration is the focus of current intensive research efforts. In this study, a hierarchically aligned fibrillar fibrin hydrogel (AFG) that was fabricated through electrospinning and the concurrent molecular self-assembly process mimics both the soft and oriented features of nerve tissue, thus providing hybrid biophysical cues to instruct cell behavior in vitro and in vivo. The electrospun hydrogels were examined by scanning electron microscopy (SEM), polarized light microscopy, small angle X-ray scattering assay and atomic force microscopy (AFM), showing a hierarchically linear-ordered structure from the nanoscale to the macroscale with a soft elastic character (elasticity ~1 kPa). We found that this low elasticity and aligned topography of AFG exhibit co-effects on promoting the neurogenic differentiation of human umbilical cord mesenchymal stem cells (hUMSCs) in comparison to random fibrin hydrogel (RFG) and tissue culture plate (TCP) control after two week cell culture in growth medium lacking supplementation with soluble neurogenic induction factors. In addition, AFG also induces dorsal root ganglion (DRG) neurons to rapidly project numerous long neurite outgrowths longitudinally along the AFG fibers for a total neurite extension distance of 1.96 mm in three days in the absence of neurotrophic factor supplementation. Moreover, the AFG implanted in a rat T9 dorsal hemisection spinal cord injury model was found to promote endogenous neural cell fast migration and axonal invasion along AFG fibers, resulting in aligned tissue cables in vivo. Our results suggest that matrix stiffness and aligned topography may instruct stem cell neurogenic differentiation and rapid neurite outgrowth, providing great promise for biomaterial design for applications in nerve regeneration.The development of novel biomaterials that deliver precise regulatory signals to direct stem cell fate for nerve regeneration is the focus of current intensive research efforts. In this study, a hierarchically aligned fibrillar fibrin hydrogel (AFG) that was fabricated through electrospinning and the concurrent molecular self-assembly process mimics both the soft and oriented features of nerve tissue, thus providing hybrid biophysical cues to instruct cell behavior in vitro and in vivo. The electrospun hydrogels were examined by scanning electron microscopy (SEM), polarized light microscopy, small angle X-ray scattering assay and atomic force microscopy (AFM), showing a hierarchically linear-ordered structure from the nanoscale to the macroscale with a soft elastic character (elasticity ~1 kPa). We found that this low elasticity and aligned topography of AFG exhibit co-effects on promoting the neurogenic differentiation of human umbilical cord mesenchymal stem cells (hUMSCs) in comparison to random fibrin hydrogel (RFG) and tissue culture plate (TCP) control after two week cell culture in growth medium lacking supplementation with soluble neurogenic induction factors. In addition, AFG also induces dorsal root ganglion (DRG) neurons to rapidly project numerous long neurite outgrowths longitudinally along the AFG fibers for a total neurite extension distance of 1.96 mm in three days in the absence of neurotrophic factor supplementation. Moreover, the AFG implanted in a rat T9 dorsal hemisection spinal cord injury model was found to promote endogenous neural cell fast migration and axonal invasion along AFG fibers, resulting in aligned tissue cables in vivo. Our results suggest that matrix stiffness and aligned topography may instruct stem cell neurogenic differentiation and rapid neurite outgrowth, providing great promise for biomaterial design for applications in nerve regeneration. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01169a

Polymer fiber-based models of connective tissue repair and healing.

PubMed

Lee, Nancy M; Erisken, Cevat; Iskratsch, Thomas; Sheetz, Michael; Levine, William N; Lu, Helen H

2017-01-01

Physiologically relevant models of wound healing are essential for understanding the biology of connective tissue repair and healing. They can also be used to identify key cellular processes and matrix characteristics critical for the design of soft tissue grafts. Modeling the various stages of repair post tendon injury, polymer meshes of varying fiber diameter (nano-1 (390 nm) < nano-2 (740 nm) < micro (1420 nm)) were produced. Alignment was also introduced in the nano-2 group to model matrix undergoing biological healing rather than scar formation. The response of human tendon fibroblasts on these model substrates were evaluated over time as a function of fiber diameter and alignment. It was observed that the repair models of unaligned nanoscale fibers enhanced cell growth and collagen synthesis, while these outcomes were significantly reduced in the mature repair model consisting of unaligned micron-sized fibers. Organization of paxillin and actin on unaligned meshes was enhanced on micro- compared to nano-sized fibers, while the expression and activity of RhoA and Rac1 were greater on nanofibers. In contrast, aligned nanofibers promoted early cell organization, while reducing excessive cell growth and collagen production in the long term. These results show that the early-stage repair model of unaligned nanoscale fibers elicits a response characteristic of the proliferative phase of wound repair, while the more mature model consisting of unaligned micron-sized fibers is more representative of the remodeling phase by supporting cell organization while suppressing growth and biosynthesis. Interestingly, introduction of fiber alignment in the nanofiber model alters fibroblast response from repair to healing, implicating matrix alignment as a critical design factor for circumventing scar formation and promoting biological healing of soft tissue injuries. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aligning Optical Fibers by Means of Actuated MEMS Wedges

NASA Technical Reports Server (NTRS)

Morgan, Brian; Ghodssi, Reza

2007-01-01

Microelectromechanical systems (MEMS) of a proposed type would be designed and fabricated to effect lateral and vertical alignment of optical fibers with respect to optical, electro-optical, optoelectronic, and/or photonic devices on integrated circuit chips and similar monolithic device structures. A MEMS device of this type would consist of a pair of oppositely sloped alignment wedges attached to linear actuators that would translate the wedges in the plane of a substrate, causing an optical fiber in contact with the sloping wedge surfaces to undergo various displacements parallel and perpendicular to the plane. In making it possible to accurately align optical fibers individually during the packaging stages of fabrication of the affected devices, this MEMS device would also make it possible to relax tolerances in other stages of fabrication, thereby potentially reducing costs and increasing yields. In a typical system according to the proposal (see Figure 1), one or more pair(s) of alignment wedges would be positioned to create a V groove in which an optical fiber would rest. The fiber would be clamped at a suitable distance from the wedges to create a cantilever with a slight bend to push the free end of the fiber gently to the bottom of the V groove. The wedges would be translated in the substrate plane by amounts Dx1 and Dx2, respectively, which would be chosen to move the fiber parallel to the plane by a desired amount Dx and perpendicular to the plane by a desired amount Dy. The actuators used to translate the wedges could be variants of electrostatic or thermal actuators that are common in MEMS.

The influence of fiber orientation on the equilibrium properties of neutral and charged biphasic tissues.

PubMed

Nagel, Thomas; Kelly, Daniel J

2010-11-01

Constitutive models facilitate investigation into load bearing mechanisms of biological tissues and may aid attempts to engineer tissue replacements. In soft tissue models, a commonly made assumption is that collagen fibers can only bear tensile loads. Previous computational studies have demonstrated that radially aligned fibers stiffen a material in unconfined compression most by limiting lateral expansion while vertically aligned fibers buckle under the compressive loads. In this short communication, we show that in conjunction with swelling, these intuitive statements can be violated at small strains. Under such conditions, a tissue with fibers aligned parallel to the direction of load initially provides the greatest resistance to compression. The results are further put into the context of a Benninghoff architecture for articular cartilage. The predictions of this computational study demonstrate the effects of varying fiber orientations and an initial tare strain on the apparent material parameters obtained from unconfined compression tests of charged tissues.

A tissue engineering approach to anterior cruciate ligament regeneration using novel shaped capillary channel polymer fibers

NASA Astrophysics Data System (ADS)

Sinclair, Kristofer D.

2009-12-01

Ruptures of the anterior cruciate ligament (ACL) are the most frequent of injuries to the knee due to its role in preventing anterior translation of the tibia. It is estimated that as many as 200,000 Americans per year will suffer from a ruptured ACL, resulting in management costs on the order of 5 billion dollars. Without treatment these patients are unable to return to normal activity, as a consequence of the joint instability found within the ACL deficient knee. Over the last thirty years, a variety of non-degradable, synthetic fibers have been evaluated for their use in ACL reconstruction; however, a widely accepted prosthesis has been unattainable due to differences in mechanical properties of the synthetic graft relative to the native tissue. Tissue engineering is an interdisciplinary field charged with the task of developing therapeutic solutions for tissue and organ failure by enhancing the natural wound healing process through the use of cellular transplants, biomaterials, and the delivery of bioactive molecules. The capillary channel polymer (CC-P) fibers used in this research were fabricated by melt extrusion from polyethylene terephthalate and polybutylene terephthalate. These fibers possess aligned micrometer scale surface channels that may serve as physical templates for tissue growth and regeneration. This inherent surface topography offers a unique and industrially viable approach for cellular contact guidance on three dimensional constructs. In this fundamental research the ability of these fiber channels to support the adhesion, alignment, and organization of fibroblasts was demonstrated and found to be superior to round fiber controls. The results demonstrated greater uniformity of seeding and accelerated formation of multi-layered three-dimensional biomass for the CC-P fibers relative to those with a circular cross-section. Furthermore, the CC-P geometry induced nuclear elongation consistent with that observed in native ACL tissue. Through the application of uniaxial cyclic strain the mechanical properties of the cell seeded CC-P fiber scaffold systems were shown to improve via the induction of increased cellular proliferation and extracellular matrix synthesis. Finally, unlike many studies examining the effects of cyclic strain on cellular behavior, the CC-P fiber geometry displayed the ability to maintain cellular alignment in the presence of an applied uniaxial cyclic strain.

Effects of fiber motion on the acoustic behavior of an anisotropic, flexible fibrous material

NASA Technical Reports Server (NTRS)

Dahl, Milo D.; Rice, Edward J.; Groesbeck, Donald E.

1987-01-01

The acoustic behavior of a flexible fibrous material was studied experimentally. The material consisted of cylindrically shaped fibers arranged in a batting with the fibers primarily aligned parallel to the face of the batting. This type of material was considered anisotropic, with the acoustic propagation constant depending on whether the dirction of sound propagation was parallel or normal to the fiber arrangement. Normal incidence sound absorption measurements were taken for both fiber orientations over the frequency range 140 to 1500 Hz and with bulk densities ranging from 4.6 to 67 kg/cu m. When the sound propagated in a direction normal to the fiber alignment, the measured sound absorption showed the occurrence of a strong resonance, which increased absorption above that attributed to viscous and thermal effects. When the sound propagated in a direction parallel to the fiber alignment, indications of strong resonances in the data were not present. The resonance in the data for fibers normal to the direction of sound propagation is attributed to fiber motion. An analytical model was developed for the acoustic behavior of the material displaying the same fiber motion characteristics shown in the measurements.

Effects of fiber motion on the acoustic behavior of an anisotropic, flexible fibrous material

NASA Technical Reports Server (NTRS)

Dahl, Milo D.; Rice, Edward J.; Groesbeck, Donald E.

1990-01-01

The acoustic behavior of a flexible fibrous material was studied experimentally. The material consisted of cylindrically shaped fibers arranged in a batting with the fibers primarily aligned parallel to the face of the batting. This type of material was considered anisotropic, with the acoustic propagation constant depending on whether the direction of sound propagation was parallel or normal to the fiber arrangement. Normal incidence sound absorption measurements were taken for both fiber orientations over the frequency range 140 to 1500 Hz and with bulk densities ranging from 4.6 to 67 kg/cu m. When the sound propagated in a direction normal to the fiber alignment, the measured sound absorption showed the occurrence of a strong resonance, which increased absorption above that attributed to viscous and thermal effects. When the sound propagated in a direction parallel to the fiber alignment, indications of strong resonances in the data were not present. The resonance in the data for fibers normal to the direction of sound propagation is attributed to fiber motion. An analytical model was developed for the acoustic behavior of the material displaying the same fiber motion characteristics shown in the measurements.

Increasing the strength and bioactivity of collagen scaffolds using customizable arrays of 3D-printed polymer fibers.

PubMed

Mozdzen, Laura C; Rodgers, Ryan; Banks, Jessica M; Bailey, Ryan C; Harley, Brendan A C

2016-03-01

Tendon is a highly aligned connective tissue which transmits force from muscle to bone. Each year, people in the US sustain more than 32 million tendon injuries. To mitigate poor functional outcomes due to scar formation, current surgical techniques rely heavily on autografts. Biomaterial platforms and tissue engineering methods offer an alternative approach to address these injuries. Scaffolds incorporating aligned structural features can promote expansion of adult tenocytes and mesenchymal stem cells capable of tenogenic differentiation. However, appropriate balance between scaffold bioactivity and mechanical strength of these constructs remains challenging. The high porosity required to facilitate cell infiltration, nutrient and oxygen biotransport within three-dimensional constructs typically results in insufficient biomechanical strength. Here we describe the use of three-dimensional printing techniques to create customizable arrays of acrylonitrile butadiene styrene (ABS) fibers that can be incorporated into a collagen scaffold under development for tendon repair. Notably, mechanical performance of scaffold-fiber composites (elastic modulus, peak stress, strain at peak stress, and toughness) can be selectively manipulated by varying fiber-reinforcement geometry without affecting the native bioactivity of the collagen scaffold. Further, we report an approach to functionalize ABS fibers with activity-inducing growth factors via sequential oxygen plasma and carbodiimide crosslinking treatments. Together, we report an adaptable approach to control both mechanical strength and presence of biomolecular cues in a manner orthogonal to the architecture of the collagen scaffold itself. Tendon injuries account for more than 32 million injuries each year in the US alone. Current techniques use allografts to mitigate poor functional outcomes, but are not ideal platforms to induce functional regeneration following injury. Tissue engineering approaches using biomaterial substrates have significant potential for addressing these defects. However, the high porosity required to facilitate cell infiltration and nutrient transport often dictates that the resultant biomaterials has insufficient biomechanical strength. Here we describe the use of three-dimensional printing techniques to generate customizable fiber arrays from ABS polymer that can be incorporated into a collagen scaffold under development for tendon repair applications. Notably, the mechanical performance of the fiber-scaffold composite can be defined by the fiber array independent of the bioactivity of the collagen scaffold design. Further, the fiber array provides a substrate for growth factor delivery to aid healing. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanism of orientation of stimulating currents in magnetic brain stimulation (abstract)

NASA Astrophysics Data System (ADS)

Ueno, S.; Matsuda, T.

1991-04-01

We made a functional map of the human motor cortex related to the hand and foot areas by stimulating the human brain with a focused magnetic pulse. We observed that each functional area in the cortex has an optimum direction for which stimulating currents can produce neural excitation. The present report focuses on the mechanism which is responsible for producing this anisotropic response to brain stimulation. We first obtained a functional map of the brain related to the left ADM (abductor digiti minimi muscles). When the stimulating currents were aligned in the direction from the left to the right hemisphere, clear EMG (electromyographic) responses were obtained only from the left ADM to magnetic stimulation of both hemisphere. When the stimulating currents were aligned in the direction from the right to the left hemisphere, clear EMG signals were obtained only from the right ADM to magnetic stimulation of both hemisphere. The functional maps of the brain were sensitive to changes in the direction of the stimulating currents. To explain the phenomena obtained in the experiments, we developed a model of neural excitation elicited by magnetic stimulation. When eddy currents which are induced by pulsed magnetic fields flow in the direction from soma to the distal part of neural fiber, depolarized area in the distal part are excited, and the membrane excitation propagates along the nerve fiber. In contrast, when the induced currents flow in the direction from the distal part to soma, hyperpolarized parts block or inhibit neural excitation even if the depolarized parts near the soma can be excited. The model explains our observation that the orientation of the induced current vectors reflect both the functional and anatomical organization of the neural fibers in the brain.

Multiscale mechanisms of nutritionally induced property variation in spider silks

PubMed Central

Nobbs, Madeleine; Martens, Penny J.; Tso, I-Min; Chuang, Wei-Tsung; Chang, Chung-Kai; Sheu, Hwo-Shuenn

2018-01-01

Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales. Our analyses found that the properties of each spider’s silk varied differently in response to variations in their protein intake. We found changes in the crystalline and non-crystalline nanostructures to play specific roles in inducing the property variations we found. Across treatment MaSp expression patterns differed in each of the five species. We found that in most species MaSp expression and amino acid composition variations did not conform with our predictions based on a traditional MaSp expression model. In general, changes to the silk’s alanine and proline compositions influenced the alignment of the proteins within the silk’s amorphous region, which influenced silk extensibility and toughness. Variations in structural alignment in the crystalline and non-crystalline regions influenced ultimate strength independent of genetic expression. Our study provides the deepest insights thus far into the mechanisms of how MA silk properties vary from gene expression to nanostructure formations to fiber mechanics. Such knowledge is imperative for promoting the production of synthetic silk fibers. PMID:29390013

Enzyme activity assays within microstructured optical fibers enabled by automated alignment.

PubMed

Warren-Smith, Stephen C; Nie, Guiying; Schartner, Erik P; Salamonsen, Lois A; Monro, Tanya M

2012-12-01

A fluorescence-based enzyme activity assay has been demonstrated within a small-core microstructured optical fiber (MOF) for the first time. To achieve this, a reflection-based automated alignment system has been developed, which uses feedback and piezoelectric actuators to maintain optical alignment. The auto-alignment system provides optical stability for the time required to perform an activity assay. The chosen assay is based on the enzyme proprotein convertase 5/6 (PC6) and has important applications in women's health.

Modulation of anisotropy in electrospun tissue-engineering scaffolds: Analysis of fiber alignment by the fast Fourier transform

PubMed Central

Ayres, Chantal; Bowlin, Gary L.; Henderson, Scott C.; Taylor, Leander; Shultz, Jackie; Alexander, John; Telemeco, Todd A.; Simpson, David G.

2010-01-01

We describe the use of the fast Fourier transform (FFT) in the measurement of anisotropy in electrospun scaffolds of gelatin as a function of the starting conditions. In electrospinning, fiber alignment and overall scaffold anisotropy can be manipulated by controlling the motion of the collecting mandrel with respect to the source electrospinning solution. By using FFT to assign relative alignment values to an electrospun matrix it is possible to systematically evaluate how different processing variables impact the structure and material properties of a scaffold. Gelatin was suspended at varying concentrations (80, 100, 130, 150 mg/ml) and electrospun from 2,2,2 trifluoroethanol onto rotating mandrels (200–7000 RPM). At each starting concentration, fiber diameter remained constant over a wide range of mandrel RPM. Scaffold anisotropy developed as a function of fiber diameter and mandrel RPM. The induction of varying degrees of anisotropy imparted distinctive material properties to the electrospun scaffolds. The FFT is a rapid method for evaluating fiber alignment in tissue-engineering materials. PMID:16859744

Bimodal and multimodal plant biomass particle mixtures

DOEpatents

Dooley, James H.

2013-07-09

An industrial feedstock of plant biomass particles having fibers aligned in a grain, wherein the particles are individually characterized by a length dimension (L) aligned substantially parallel to the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L, wherein the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces, and wherein the particles in the feedstock are collectively characterized by having a bimodal or multimodal size distribution.

Preparation of active 3D film patches via aligned fiber electrohydrodynamic (EHD) printing

NASA Astrophysics Data System (ADS)

Wang, Jun-Chuan; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

2017-03-01

The design, preparation and application of three-dimensional (3D) printed structures have gained appreciable interest in recent times, particularly for drug dosage development. In this study, the electrohydrodynamic (EHD) printing technique was developed to fabricate aligned-fiber antibiotic (tetracycline hydrochloride, TE-HCL) patches using polycaprolactone (PCL), polyvinyl pyrrolidone (PVP) and their composite system (PVP-PCL). Drug loaded 3D patches possessed perfectly aligned fibers giving rise to fibrous strut orientation, variable inter-strut pore size and controlled film width (via layering). The effect of operating parameters on fiber deposition and alignment were explored, and the impact of the film structure, composition and drug loading was evaluated. FTIR demonstrated successful TE-HCL encapsulation in aligned fibers. Patches prepared using PVP and TE-HCL displayed enhanced hydrophobicity. Tensile tests exhibited changes to mechanical properties arising from additive effects. Release of antibiotic from PCL-PVP dosage forms was shown over 5 days and was slower compared to pure PCL or PVP. The printed patch void size also influenced antibiotic release behavior. The EHDA printing technique provides an exciting opportunity to tailor dosage forms in a single-step with minimal excipients and operations. These developments are crucial to meet demands where dosage forms cannot be manufactured rapidly or when a personalized approach is required.

Preparation of active 3D film patches via aligned fiber electrohydrodynamic (EHD) printing

PubMed Central

Wang, Jun-Chuan; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

2017-01-01

The design, preparation and application of three-dimensional (3D) printed structures have gained appreciable interest in recent times, particularly for drug dosage development. In this study, the electrohydrodynamic (EHD) printing technique was developed to fabricate aligned-fiber antibiotic (tetracycline hydrochloride, TE-HCL) patches using polycaprolactone (PCL), polyvinyl pyrrolidone (PVP) and their composite system (PVP-PCL). Drug loaded 3D patches possessed perfectly aligned fibers giving rise to fibrous strut orientation, variable inter-strut pore size and controlled film width (via layering). The effect of operating parameters on fiber deposition and alignment were explored, and the impact of the film structure, composition and drug loading was evaluated. FTIR demonstrated successful TE-HCL encapsulation in aligned fibers. Patches prepared using PVP and TE-HCL displayed enhanced hydrophobicity. Tensile tests exhibited changes to mechanical properties arising from additive effects. Release of antibiotic from PCL-PVP dosage forms was shown over 5 days and was slower compared to pure PCL or PVP. The printed patch void size also influenced antibiotic release behavior. The EHDA printing technique provides an exciting opportunity to tailor dosage forms in a single-step with minimal excipients and operations. These developments are crucial to meet demands where dosage forms cannot be manufactured rapidly or when a personalized approach is required. PMID:28272513

Mechanical model of suture joints with fibrous connective layer

NASA Astrophysics Data System (ADS)

Miroshnichenko, Kateryna; Liu, Lei; Tsukrov, Igor; Li, Yaning

2018-02-01

A composite model for suture joints with a connective layer of aligned fibers embedded in soft matrix is proposed. Based on the principle of complementary virtual work, composite cylinder assemblage (CCA) approach and generalized self-consistent micro-mechanical models, a hierarchical homogenization methodology is developed to systematically quantify the synergistic effects of suture morphology and fiber orientation on the overall mechanical properties of sutures. Suture joints with regular triangular wave-form serve as an example material system to apply this methodology. Both theoretical and finite element mechanical models are developed and compared to evaluate the overall normal stiffness of sutures as a function of wavy morphology of sutures, fiber orientation, fiber volume fraction, and the mechanical properties of fibers and matrix in the interfacial layer. It is found that generally due to the anisotropy-induced coupling effects between tensile and shear deformation, the effective normal stiffness of sutures is highly dependent on the fiber orientation in the connective layer. Also, the effective shear modulus of the connective layer and the stiffness ratio between the fiber and matrix significantly influence the effects of fiber orientation. In addition, optimal fiber orientations are found to maximize the stiffness of suture joints.

Hydrostatic pressure in combination with topographical cues affects the fate of bone marrow-derived human mesenchymal stem cells for bone tissue regeneration.

PubMed

Reinwald, Yvonne; El Haj, Alicia J

2018-03-01

Topographical and mechanical cues are vital for cell fate, tissue development in vivo, and to mimic the native cell growth environment in vitro. To date, the combinatory effect of mechanical and topographical cues as not been thoroughly investigated. This study investigates the effect of PCL nanofiber alignment and hydrostatic pressure on stem cell differentiation for bone tissue regeneration. Bone marrow-derived human mesenchymal stem cells were seeded onto standard tissue culture plastic and electrospun random and aligned nanofibers. These substrates were either cultured statically or subjected to intermittent hydrostatic pressure at 270 kPa, 1 Hz for 60 min daily over 21 days in osteogenic medium. Data revealed higher cell metabolic activities for all mechanically stimulated cell culture formats compared with non-stimulated controls; and random fibers compared with aligned fibers. Fiber orientation influenced cell morphology and patterns of calcium deposition. Significant up-regulation of Collagen-I, ALP, and Runx-2 were observed for random and aligned fibers following mechanical stimulation; highest levels of osteogenic markers were expressed when hydrostatic pressure was applied to random fibers. These results indicate that fiber alignment and hydrostatic pressure direct stem cell fate and are important stimulus for tissue regeneration. © 2017 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: A: 629-640, 2018. © 2017 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc.

Hydrostatic pressure in combination with topographical cues affects the fate of bone marrow‐derived human mesenchymal stem cells for bone tissue regeneration

PubMed Central

El Haj, Alicia J.

2017-01-01

Abstract Topographical and mechanical cues are vital for cell fate, tissue development in vivo, and to mimic the native cell growth environment in vitro. To date, the combinatory effect of mechanical and topographical cues as not been thoroughly investigated. This study investigates the effect of PCL nanofiber alignment and hydrostatic pressure on stem cell differentiation for bone tissue regeneration. Bone marrow‐derived human mesenchymal stem cells were seeded onto standard tissue culture plastic and electrospun random and aligned nanofibers. These substrates were either cultured statically or subjected to intermittent hydrostatic pressure at 270 kPa, 1 Hz for 60 min daily over 21 days in osteogenic medium. Data revealed higher cell metabolic activities for all mechanically stimulated cell culture formats compared with non‐stimulated controls; and random fibers compared with aligned fibers. Fiber orientation influenced cell morphology and patterns of calcium deposition. Significant up‐regulation of Collagen‐I, ALP, and Runx‐2 were observed for random and aligned fibers following mechanical stimulation; highest levels of osteogenic markers were expressed when hydrostatic pressure was applied to random fibers. These results indicate that fiber alignment and hydrostatic pressure direct stem cell fate and are important stimulus for tissue regeneration. © 2017 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: A: 629–640, 2018. PMID:28984025

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.

From Wood to Textiles: Top-Down Assembly of Aligned Cellulose Nanofibers.

PubMed

Jia, Chao; Chen, Chaoji; Kuang, Yudi; Fu, Kun; Wang, Yilin; Yao, Yonggang; Kronthal, Spencer; Hitz, Emily; Song, Jianwei; Xu, Fujun; Liu, Boyang; Hu, Liangbing

2018-06-07

Advanced textiles made of macroscopic fibers are usually prepared from synthetic fibers, which have changed lives over the past century. The shortage of petrochemical resources, however, greatly limits the development of the textile industry. Here, a facile top-down approach for fabricating macroscopic wood fibers for textile applications (wood-textile fibers) comprising aligned cellulose nanofibers directly from natural wood via delignification and subsequent twisting is demonstrated. Inherently aligned cellulose nanofibers are well retained, while the microchannels in the delignified wood are squeezed and totally removed by twisting, resulting in a dense structure with approximately two times higher mechanical strength (106.5 vs 54.9 MPa) and ≈20 times higher toughness (7.70 vs 0.36 MJ m -3 ) than natural wood. Dramatically different from natural wood, which is brittle in nature, the resultant wood-textile fibers are highly flexible and bendable, likely due to the twisted structures. The wood-textile fibers also exhibit excellent knitting properties and dyeability, which are critical for textile applications. Furthermore, functional wood-textile fibers can be achieved by preinfiltrating functional materials in the delignified wood film before twisting. This top-down approach of fabricating aligned macrofibers is simple, scalable, and cost-effective, representing a promising direction for the development of smart textiles and wearable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Observations of axisymmetric tracer particle orientation during flow through a dilute fixed bed of fibers

NASA Astrophysics Data System (ADS)

Frattini, Paul L.; Shaqfeh, Eric S. G.; Levy, Jeffrey L.; Koch, Donald L.

1991-11-01

Direct microstructural evidence for net tracer particle orientation induced solely by hydrodynamic interactions in a dilute, disordered, fibrous media is reported. A dilute fixed bed of randomly placed fibers was constructed and glycerol/water suspensions of either synthetic akaganeite (βFeOOH, average aspect ratio 6.3) or hematite (αFe2O3, average aspect ratio 1.6) tracer particles were made to flow axially through the bed at prescribed flow rates. Conservative linear dichroism, a noninvasive light scattering technique, was employed to provide a direct measure of the orientational order parameter for the tracer particle population at the end of the bed. The effect of Brownian motion on the hydrodynamically induced order in the suspensions was studied over three orders of magnitude in scaled rotary Peclet number, 5

Self-centering fiber alignment structures for high-precision field installable single-mode fiber connectors

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Ebraert, Evert; Gao, Fei; Vervaeke, Michael; Berghmans, Francis; Beri, Stefano; Watté, Jan; Thienpont, Hugo

2014-05-01

There is a steady increase in the demand for internet bandwidth, primarily driven by cloud services and high-definition video streaming. Europe's Digital Agenda states the ambitious objective that by 2020 all Europeans should have access to internet at speeds of 30Mb/s or above, with 50% or more of households subscribing to connections of 100Mb/s. Today however, internet access in Europe is mainly based on the first generation of broadband, meaning internet accessed over legacy telephone copper and TV cable networks. In recent years, Fiber-To-The-Home (FTTH) networks have been adopted as a replacement of traditional electrical connections for the `last mile' transmission of information at bandwidths over 1Gb/s. However, FTTH penetration is still very low (< 5%) in most major Western economies. The main reason for this is the high deployment cost of FTTH networks. Indeed, the success and adoption of optical access networks critically depend on the quality and reliability of connections between optical fibers. In particular a further reduction of insertion loss of field- installable connectors must be achieved without a significant increase in component cost. This requires precise alignment of fibers that can differ in terms of ellipticity, eccentricity or diameter and seems hardly achievable using today's widespread ferrule-based alignment systems. In this paper, we present a field-installable connector based on deflectable/compressible spring structures, providing a self-centering functionality for the fiber. This way, it can accommodate for possible fiber cladding diameter variations (the tolerance on the cladding diameter of G.652 fiber is typically +/-0.7μm). The mechanical properties of the cantilever are derived through an analytical approximation and a mathematical model of the spring constant, and finite element-based simulations are carried out to find the maximum first principal stress as well as the stress distribution distribution in the fiber alignment structure. Elastic constants of the order of 104N=m are found to be compatible with a proof stress of 70 M Pa. We show the successful prototyping of 3-spring fiber alignment structures using deep proton writing and investigate their compatibility with replication techniques such as hot embossing and injection moulding. Fiber insertion in our self-centering alignment structures is achieved by means of a dedicated interferometric setup allowing assessment of the fiber facet quality, of the fiber's position in relation to the connector's front and of the spring deformation during fiber insertion. These self-centering structures have the potential to become the basic building blocks for a new generation of field-installable connectors, ultimately breaking the current paradigm of ferrule-based connectivity requiring extensive pre-engineering and highly specialized manpower for field deployment.

Laser-fiber coupling by means of a silicon micro-optical bench and a self-aligned soldering process

NASA Astrophysics Data System (ADS)

Schmidt, Jan P.; Cordes, A.; Mueller, Joerg; Burkhardt, Hans

1995-02-01

The alignment of laser diodes to monomode fibers has to meet extremely close tolerances for a low coupling loss. Typically < 0.5 micrometers in lateral and vertical direction and less than two degrees in angle deviation are allowed for a coupling loss below 2 dB. Presently such close tolerances can only be met by gluing or soldering both components on separate base plates and combining them via piezoactivated alignment monitoring the output of the circuit and then gluing them using UV-hardening epoxies. Such a procedure is not very economical and not useful for mass applications. This paper presents the principle and realization of a silicon micro-optical bench for laser-fiber-coupling, which avoids the above mentioned disadvantages. The micro-optical bench is realized using well controlled plasma etching processes to transfer the guiding patterns for the laser and the fiber into the silicon substrate, keeping geometry tolerances below +/- 0.5 micrometers in lateral and vertical direction. Mounting the laser diode by means of a self-aligned soldering process, an additional contribution to the precise alignment of the laser is further improved.

Fabrication of drug-loaded electrospun aligned fibrous threads for suture applications.

PubMed

He, Chuang-Long; Huang, Zheng-Ming; Han, Xiao-Jian

2009-04-01

In this work, drug-loaded fibers and threads were successfully fabricated by combining electrospinning with aligned fibers collection. Two different electrospinning processes, that is, blend and coaxial electrospinning, to incorporate a model drug tetracycline hydrochloride (TCH) into poly(L-lactic acid) (PLLA) fibers have been used and compared with each other. The resulting composite ultrafine fibers and threads were characterized through scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and tensile testing. It has been shown that average diameters of the fibers made from the same polymer concentration depended on the processing method. The blend TCH/PLLA fibers showed the smallest fiber diameter, whereas neat PLLA fibers and core-shell TCH-PLLA fibers showed a larger proximal average diameter. Higher rotating speed of a wheel collector is helpful for obtaining better-aligned fibers. Both the polymer and the drug in the electrospun fibers have poor crystalline property. In vitro release study indicated that threads made from the core-shell fibers could suppress the initial burst release and provide a sustained drug release useful for the release of growth factor or other therapeutic drugs. On the other hand, the threads from the blend fibers produced a large initial burst release that may be used to prevent bacteria infection. A combination of these results suggests that electrospinning technique provides a novel way to fabricate medical agents-loaded fibrous threads for tissue suturing and tissue regeneration applications. Copyright 2008 Wiley Periodicals, Inc.

Engineered plant biomass feedstock particles

DOEpatents

Dooley, James H [Federal Way, WA; Lanning, David N [Federal Way, WA; Broderick, Thomas F [Lake Forest Park, WA

2012-04-17

A new class of plant biomass feedstock particles characterized by consistent piece size and shape uniformity, high skeletal surface area, and good flow properties. The particles of plant biomass material having fibers aligned in a grain are characterized by a length dimension (L) aligned substantially parallel to the grain and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. In particular, the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces. The L.times.W surfaces of particles with L/H dimension ratios of 4:1 or less are further elaborated by surface checking between longitudinally arrayed fibers. The length dimension L is preferably aligned within 30.degree. parallel to the grain, and more preferably within 10.degree. parallel to the grain. The plant biomass material is preferably selected from among wood, agricultural crop residues, plantation grasses, hemp, bagasse, and bamboo.

Effect of Electromechanical Stimulation on the Maturation of Myotubes on Aligned Electrospun Fibers

PubMed Central

Liao, I-Chien; Liu, Jason B.; Bursac, Nenad; Leong, Kam W.

2009-01-01

Tissue engineering may provide an alternative to cell injection as a therapeutic solution for myocardial infarction. A tissue-engineered muscle patch may offer better host integration and higher functional performance. This study examined the differentiation of skeletal myoblasts on aligned electrospun polyurethane (PU) fibers and in the presence of electromechanical stimulation. Skeletal myoblasts cultured on aligned PU fibers showed more pronounced elongation, better alignment, higher level of transient receptor potential cation channel-1 (TRPC-1) expression, upregulation of contractile proteins and higher percentage of striated myotubes compared to those cultured on random PU fibers and film. The resulting tissue constructs generated tetanus forces of 1.1 mN with a 10-ms time to tetanus. Additional mechanical, electrical, or synchronized electromechanical stimuli applied to myoblasts cultured on PU fibers increased the percentage of striated myotubes from 70 to 85% under optimal stimulation conditions, which was accompanied by an upregulation of contractile proteins such as α-actinin and myosin heavy chain. In describing how electromechanical cues can be combined with topographical cue, this study helped move towards the goal of generating a biomimetic microenvironment for engineering of functional skeletal muscle. PMID:19774099

Fiber optics welder

DOEpatents

Higgins, R.W.; Robichaud, R.E.

A system is described for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45/sup 0/ angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

Fabrication and material properties of fibrous PHBV scaffolds depending on the cross-ply angle for tissue engineering.

PubMed

Kim, Yang-Hee; Min, Young-Ki; Lee, Byong-Taek

2012-11-01

Fibrous PHBV cross-ply scaffolds were fabricated using the electrospinning technique. The electrospun fibers were arranged depending on angles of alignment, which were 180°, 90°, 60°, and 45°. The stress and strain values of the fibrous PHBV cross-ply scaffolds increased as the cross-ply angle increased. At 180°, the strength and strain values of the fibers depended on tensile loading directions. At an alignment of 90°, the PHBV scaffolds had a stress value of 3.5 MPa, which was more than two times higher than the random structure. The cell morphology and proliferation of L-929 cells was strongly dependant on the fiber alignment and the best results were observed when the angle alignment was high. The results of this study showed that the cross-ply structure of the PHBV scaffold affected not only the cell adhesion and spreading properties but also dictated the mechanical properties, which were dependent on the angles of alignment.

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

High-efficiency (6 + 1) × 1 pump-signal combiner based on low-deformation and high-precision alignment fabrication

NASA Astrophysics Data System (ADS)

Zou, Shuzhen; Chen, Han; Yu, Haijuan; Sun, Jing; Zhao, Pengfei; Lin, Xuechun

2017-12-01

We demonstrate a new method for fabricating a (6 + 1) × 1 pump-signal combiner based on the reduction of signal fiber diameter by corrosion. This method avoids the mismatch loss of the splice between the signal fiber and the output fiber caused by the signal fiber taper processing. The optimum radius of the corroded signal fiber was calculated according to the analysis of the influence of the cladding thickness on the laser propagating in the fiber core. Besides, we also developed a two-step splicing method to complete the high-precision alignment between the signal fiber core and the output fiber core. A high-efficiency (6 + 1) × 1 pump-signal combiner was produced with an average pump power transmission efficiency of 98.0% and a signal power transmission efficiency of 97.7%, which is well suitable for application to high-power fiber laser system.

Eliminating crystals in non-oxide optical fiber preforms and optical fibers

NASA Technical Reports Server (NTRS)

LaPointe, Michael R. (Inventor); Tucker, Dennis S. (Inventor)

2010-01-01

A method is provided for eliminating crystals in non-oxide optical fiber preforms as well as optical fibers drawn therefrom. The optical-fiber-drawing axis of the preform is aligned with the force of gravity. A magnetic field is applied to the preform as it is heated to at least a melting temperature thereof. The magnetic field is applied in a direction that is parallel to the preform's optical-fiber-drawing axis. The preform is then cooled to a temperature that is less than a glass transition temperature of the preform while the preform is maintained in the magnetic field. When the processed preform is to have an optical fiber drawn therefrom, the preform's optical-fiber-drawing axis is again aligned with the force of gravity and a magnetic field is again applied along the axis as the optical fiber is drawn from the preform.

Optical interconnection for a polymeric PLC device using simple positional alignment.

PubMed

Ryu, Jin Hwa; Kim, Po Jin; Cho, Cheon Soo; Lee, El-Hang; Kim, Chang-Seok; Jeong, Myung Yung

2011-04-25

This study proposes a simple cost-effective method of optical interconnection between a planar lightwave circuit (PLC) device chip and an optical fiber. It was conducted to minimize and overcome the coupling loss caused by lateral offset which is due to the process tolerance and the dimensional limitation existing between PLC device chips and fiber array blocks with groove structures. A PLC device chip and a fiber array block were simultaneously fabricated in a series of polymer replication processes using the original master. The dimensions (i.e., width and thickness) of the under-clad of the PLC device chip were identical to those of the fiber array block. The PLC device chip and optical fiber were aligned by simple positional control for the vertical direction of the PLC device chip under a particular condition. The insertion loss of the proposed 1 x 2 multimode optical splitter device interconnection was 4.0 dB at 850 nm and the coupling loss was below 0.1 dB compared with single-fiber based active alignment.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Holloway, Nancy M. (Inventor); Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor); Leong, Kam W. (Inventor); Kulangara, Karina (Inventor)

2015-01-01

A scaffold assembly and related methods of manufacturing and/or using the scaffold for stem cell culture and tissue engineering applications are disclosed which at least partially mimic a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

NASA Technical Reports Server (NTRS)

Kulangara, Karina (Inventor); Scott Carnell, Lisa A. (Inventor); Holloway, Nancy M. (Inventor); Leong, Kam W. (Inventor); Siochi, Emilie J. (Inventor)

2017-01-01

A method of manufacturing and/or using a scaffold assembly for stem cell culture and tissue engineering applications is disclosed. The scaffold at least partially mimics a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation that uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

Electroactive BaTiO3 nanoparticle-functionalized fibrous scaffolds enhance osteogenic differentiation of mesenchymal stem cells

PubMed Central

Li, Yiping; Dai, Xiaohan; Bai, Yunyang; Liu, Yun; Wang, Yuehong; Liu, Ousheng; Yan, Fei; Tang, Zhangui; Zhang, Xuehui; Deng, Xuliang

2017-01-01

It has been proven that the surface topographic cues of fiber arrangement can induce osteogenic differentiation of mesenchymal stem cells. However, this effect alone is weak and insufficient to meet the needs of regenerative medicine. In this work, electroactivity concept was introduced to enhance the osteoinductivity of fibrous scaffolds. The randomly oriented and aligned electroactive fibrous scaffolds of poly-(l-lactic acid) (PLLA) with incorporation of ferroelectric ceramic BaTiO3 (BTO) nanoparticles (NPs) were fabricated by electrospinning. Physicochemical properties, including fiber morphology, microstructure, composition, thermal stability, surface roughness, and surface wettability, of these fibrous scaffolds were studied. The dielectric properties of the scaffolds were evaluated. The results showed that the randomly oriented BTO/PLLA composite fibrous scaffolds had the highest dielectric permittivity of 1.19, which is of the same order of magnitude as the natural bone. The combined effects of fiber orientation and electrical activity on the osteogenic responses of bone marrow mesenchymal stem cells (BM-MSCs) were specifically investigated. Randomly oriented composite fibrous scaffolds significantly promoted polygonal spreading and encouraged early osteogenic differentiation in BM-MSCs, whereas aligned composite fibrous scaffolds promoted cell elongation and discouraged osteogenic differentiation. These results evidenced that randomly fiber orientation and biomimetic electric activity have combining effects on osteogenic differentiation of BM-MSCs. Our findings indicate that coupling effects of multi-physical properties should be paid more attention to mimic the microenvironment for enhancing osteogenic differentiation of BM-MSCs. PMID:28603415

Electrode alignment of transverse tripoles using a percutaneous triple-lead approach in spinal cord stimulation

NASA Astrophysics Data System (ADS)

Sankarasubramanian, V.; Buitenweg, J. R.; Holsheimer, J.; Veltink, P.

2011-02-01

The aim of this modeling study is to determine the influence of electrode alignment of transverse tripoles on the paresthesia coverage of the pain area in spinal cord stimulation, using a percutaneous triple-lead approach. Transverse tripoles, comprising a central cathode and two lateral anodes, were modeled on the low-thoracic vertebral region (T10-T12) using percutaneous triple-lead configurations, with the center lead on the spinal cord midline. The triple leads were oriented both aligned and staggered. In the staggered configuration, the anodes were offset either caudally (caudally staggered) or rostrally (rostrally staggered) with respect to the midline cathode. The transverse tripolar field steering with the aligned and staggered configurations enabled the estimation of dorsal column fiber thresholds (IDC) and dorsal root fiber thresholds (IDR) at various anodal current ratios. IDC and IDR were considerably higher for the aligned transverse tripoles as compared to the staggered transverse tripoles. The aligned transverse tripoles facilitated deeper penetration into the medial dorsal columns (DCs). The staggered transverse tripoles always enabled broad and bilateral DC activation, at the expense of mediolateral steerability. The largest DC recruited area was obtained with the rostrally staggered transverse tripole. Transverse tripolar geometries, using percutaneous leads, allow for selective targeting of either medial or lateral DC fibers, if and only if the transverse tripole is aligned. Steering of anodal currents between the lateral leads of the staggered transverse tripoles cannot target medially confined populations of DC fibers in the spinal cord. An aligned transverse tripolar configuration is strongly recommended, because of its ability to provide more post-operative flexibility than other configurations.

Optimizing alignment and growth of low-loss YAG single crystal fibers using laser heated pedestal growth technique.

PubMed

Bera, Subhabrata; Nie, Craig D; Soskind, Michael G; Harrington, James A

2017-12-10

The effect of misalignments of different optical components in the laser heated pedestal growth apparatus have been modeled using Zemax optical design software. By isolating the misalignments causing the non-uniformity in the melt zone, the alignment of the components was fine-tuned. Using this optimized alignment, low-loss YAG single crystal fibers of 120 μm diameter were grown, with total attenuation loss as low as 0.5 dB/m at 1064 nm.

Structural hysteresis in dragline spider silks induced by supercontraction: an X-ray fiber micro-diffraction study

DOE PAGES

Sampath, Sujatha; Yarger, Jeffery L.

2014-11-27

Interaction with water causes shrinkage and significant changes in the structure of spider dragline silks, which has been referred to as supercontraction in the literature. Preferred orientation or alignment of protein chains with respect to the fiber axis is extensively changed during this supercontraction process. Synchrotron X-ray micro-fiber diffraction experiments have been performed on Nephila clavipes and Argiope aurantia major and minor ampullate dragline spider fibers in the native dry, contracted (by immersion in water) and restretched (from contracted) states. Changes in the orientation of β-sheet nanocrystallites and the oriented component of the amorphous network have been determined from wide-anglemore » X-ray diffraction patterns. While both the crystalline and amorphous components lose preferred orientation on wetting with water, the nano-crystallites regain their orientation on wet-restretching, whereas the oriented amorphous components only partially regain their orientation. Dragline major ampullate silks in both the species contract more than their minor ampullate silks.« less

Quantitative analysis and temperature-induced variations of moiré pattern in fiber-coupled imaging sensors.

PubMed

Karbasi, Salman; Arianpour, Ashkan; Motamedi, Nojan; Mellette, William M; Ford, Joseph E

2015-06-10

Imaging fiber bundles can map the curved image surface formed by some high-performance lenses onto flat focal plane detectors. The relative alignment between the focal plane array pixels and the quasi-periodic fiber-bundle cores can impose an undesirable space variant moiré pattern, but this effect may be greatly reduced by flat-field calibration, provided that the local responsivity is known. Here we demonstrate a stable metric for spatial analysis of the moiré pattern strength, and use it to quantify the effect of relative sensor and fiber-bundle pitch, and that of the Bayer color filter. We measure the thermal dependence of the moiré pattern, and the achievable improvement by flat-field calibration at different operating temperatures. We show that a flat-field calibration image at a desired operating temperature can be generated using linear interpolation between white images at several fixed temperatures, comparing the final image quality with an experimentally acquired image at the same temperature.

Optimal matrix rigidity for stress fiber polarization in stem cells

PubMed Central

Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.

2010-01-01

The shape and differentiation of human mesenchymal stem cells is especially sensitive to the rigidity of their environment; the physical mechanisms involved are unknown. A theoretical model and experiments demonstrate here that the polarization/alignment of stress-fibers within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix whose polarizability, unlike dead matter, depends on the feedback of cellular forces that develop in response to matrix stresses. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress-fibers parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress-fibers in stem cells. These findings offer a first physical insight for the dependence of stem cell differentiation on tissue elasticity. PMID:20563235

Three-dimensional matrix fiber alignment modulates cell migration and MT1-MMP utility by spatially and temporally directing protrusions

NASA Astrophysics Data System (ADS)

Fraley, Stephanie I.; Wu, Pei-Hsun; He, Lijuan; Feng, Yunfeng; Krisnamurthy, Ranjini; Longmore, Gregory D.; Wirtz, Denis

2015-10-01

Multiple attributes of the three-dimensional (3D) extracellular matrix (ECM) have been independently implicated as regulators of cell motility, including pore size, crosslink density, structural organization, and stiffness. However, these parameters cannot be independently varied within a complex 3D ECM protein network. We present an integrated, quantitative study of these parameters across a broad range of complex matrix configurations using self-assembling 3D collagen and show how each parameter relates to the others and to cell motility. Increasing collagen density resulted in a decrease and then an increase in both pore size and fiber alignment, which both correlated significantly with cell motility but not bulk matrix stiffness within the range tested. However, using the crosslinking enzyme Transglutaminase II to alter microstructure independently of density revealed that motility is most significantly predicted by fiber alignment. Cellular protrusion rate, protrusion orientation, speed of migration, and invasion distance showed coupled biphasic responses to increasing collagen density not predicted by 2D models or by stiffness, but instead by fiber alignment. The requirement of matrix metalloproteinase (MMP) activity was also observed to depend on microstructure, and a threshold of MMP utility was identified. Our results suggest that fiber topography guides protrusions and thereby MMP activity and motility.

Co-effects of matrix low elasticity and aligned topography on stem cell neurogenic differentiation and rapid neurite outgrowth.

PubMed

Yao, Shenglian; Liu, Xi; Yu, Shukui; Wang, Xiumei; Zhang, Shuming; Wu, Qiong; Sun, Xiaodan; Mao, Haiquan

2016-05-21

The development of novel biomaterials that deliver precise regulatory signals to direct stem cell fate for nerve regeneration is the focus of current intensive research efforts. In this study, a hierarchically aligned fibrillar fibrin hydrogel (AFG) that was fabricated through electrospinning and the concurrent molecular self-assembly process mimics both the soft and oriented features of nerve tissue, thus providing hybrid biophysical cues to instruct cell behavior in vitro and in vivo. The electrospun hydrogels were examined by scanning electron microscopy (SEM), polarized light microscopy, small angle X-ray scattering assay and atomic force microscopy (AFM), showing a hierarchically linear-ordered structure from the nanoscale to the macroscale with a soft elastic character (elasticity ∼1 kPa). We found that this low elasticity and aligned topography of AFG exhibit co-effects on promoting the neurogenic differentiation of human umbilical cord mesenchymal stem cells (hUMSCs) in comparison to random fibrin hydrogel (RFG) and tissue culture plate (TCP) control after two week cell culture in growth medium lacking supplementation with soluble neurogenic induction factors. In addition, AFG also induces dorsal root ganglion (DRG) neurons to rapidly project numerous long neurite outgrowths longitudinally along the AFG fibers for a total neurite extension distance of 1.96 mm in three days in the absence of neurotrophic factor supplementation. Moreover, the AFG implanted in a rat T9 dorsal hemisection spinal cord injury model was found to promote endogenous neural cell fast migration and axonal invasion along AFG fibers, resulting in aligned tissue cables in vivo. Our results suggest that matrix stiffness and aligned topography may instruct stem cell neurogenic differentiation and rapid neurite outgrowth, providing great promise for biomaterial design for applications in nerve regeneration.

Quantitative Analysis of Complex Glioma Cell Migration on Electrospun Polycaprolactone Using Time-Lapse Microscopy

PubMed Central

Johnson, Jed; Nowicki, M. Oskar; Lee, Carol H.; Chiocca, E. Antonio; Viapiano, Mariano S.; Lawler, Sean E.

2009-01-01

Malignant gliomas are the most common tumors originating within the central nervous system and account for over 15,000 deaths annually in the United States. The median survival for glioblastoma, the most common and aggressive of these tumors, is only 14 months. Therapeutic strategies targeting glioma cells migrating away from the tumor core are currently hampered by the difficulty of reproducing migration in the neural parenchyma in vitro. We utilized a tissue engineering approach to develop a physiologically relevant model of glioma cell migration. This revealed that glioma cells display dramatic differences in migration when challenged by random versus aligned electrospun poly-ɛ-caprolactone nanofibers. Cells on aligned fibers migrated at an effective velocity of 4.2 ± 0.39 μm/h compared to 0.8 ± 0.08 μm/h on random fibers, closely matching in vivo models and prior observations of glioma spread in white versus gray matter. Cells on random fibers exhibited extension along multiple fiber axes that prevented net motion; aligned fibers promoted a fusiform morphology better suited to infiltration. Time-lapse microscopy revealed that the motion of individual cells was complex and was influenced by cell cycle and local topography. Glioma stem cell–containing neurospheres seeded on random fibers did not show cell detachment and retained their original shape; on aligned fibers, cells detached and migrated in the fiber direction over a distance sixfold greater than the perpendicular direction. This chemically and physically flexible model allows time-lapse analysis of glioma cell migration while recapitulating in vivo cell morphology, potentially allowing identification of physiological mediators and pharmacological inhibitors of invasion. PMID:19199562

Mechanical properties of electrospun bilayer fibrous membranes as potential scaffolds for tissue engineering.

PubMed

Pu, Juan; Komvopoulos, Kyriakos

2014-06-01

Bilayer fibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning, using a parallel-disk mandrel configuration that resulted in the sequential deposition of a layer with fibers aligned across the two parallel disks and a layer with randomly oriented fibers, both layers deposited in a single process step. Membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, bilayer membranes exhibited higher porosity than single-layer membranes consisting of randomly oriented fibers fabricated with a solid-drum collector. However, despite their higher porosity, bilayer membranes demonstrated generally higher elastic modulus, yield strength and toughness than single-layer membranes with random fibers. Bilayer membrane deformation at relatively high strain rates comprised multiple abrupt microfracture events characterized by discontinuous fiber breakage. Bilayer membrane elongation yielded excessive necking of the layer with random fibers and remarkable fiber stretching (on the order of 400%) in the layer with fibers aligned in the stress direction. In addition, fibers in both layers exhibited multiple localized necking, attributed to the nonuniform distribution of crystalline phases in the fibrillar structure. The high membrane porosity, good mechanical properties, and good biocompatibility and biodegradability of PLLA (demonstrated in previous studies) make the present bilayer membranes good scaffold candidates for a wide range of tissue engineering applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fiber optic coupled optical sensor

DOEpatents

Fleming, Kevin J.

2001-01-01

A displacement sensor includes a first optical fiber for radiating light to a target, and a second optical fiber for receiving light from the target. The end of the first fiber is adjacent and not axially aligned with the second fiber end. A lens focuses light from the first fiber onto the target and light from the target onto the second fiber.

Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

USDA-ARS?s Scientific Manuscript database

The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

Density profile and fiber alignment in fiberboard from three southern hardwoods

Treesearch

George E. Woodson

1977-01-01

Density profile and fiber orientation were evaluated for their effects on selected mechanical properties of medium density fiberboard. Bending MOE and modulus of rigidity were predicted from density profiles established by x-ray radiography. Orthotropic ratios ranged from 1.19 to 2.32 for electrically aligned fiberboards from three southern hardwoods. Off-axis tensile...

Magnetically aligned H I fibers and the rolling hough transform

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

Clark, S. E.; Putman, M. E.; Peek, J. E. G.

2014-07-01

We present observations of a new group of structures in the diffuse Galactic interstellar medium (ISM): slender, linear H I features we dub 'fibers' that extend for many degrees at high Galactic latitude. To characterize and measure the extent and strength of these fibers, we present the Rolling Hough Transform, a new machine vision method for parameterizing the coherent linearity of structures in the image plane. With this powerful new tool we show that the fibers are oriented along the interstellar magnetic field as probed by starlight polarization. We find that these low column density (N{sub H} {sub I}≃5×10{sup 18}more » cm{sup –2}) fiber features are most likely a component of the local cavity wall, about 100 pc away. The H I data we use to demonstrate this alignment at high latitude are from the Galactic Arecibo L-Band Feed Array H I (GALFA-H I) Survey and the Parkes Galactic All Sky Survey. We find better alignment in the higher resolution GALFA-H I data, where the fibers are more visually evident. This trend continues in our investigation of magnetically aligned linear features in the Riegel-Crutcher H I cold cloud, detected in the Southern Galactic Plane Survey. We propose an application of the RHT for estimating the field strength in such a cloud, based on the Chandrasekhar-Fermi method. We conclude that data-driven, quantitative studies of ISM morphology can be very powerful predictors of underlying physical quantities.« less

Structure-Property Relations in Carbon Nanotube Fibers by Downscaling Solution Processing.

PubMed

Headrick, Robert J; Tsentalovich, Dmitri E; Berdegué, Julián; Bengio, Elie Amram; Liberman, Lucy; Kleinerman, Olga; Lucas, Matthew S; Talmon, Yeshayahu; Pasquali, Matteo

2018-03-01

At the microscopic scale, carbon nanotubes (CNTs) combine impressive tensile strength and electrical conductivity; however, their macroscopic counterparts have not met expectations. The reasons are variously attributed to inherent CNT sample properties (diameter and helicity polydispersity, high defect density, insufficient length) and manufacturing shortcomings (inadequate ordering and packing), which can lead to poor transmission of stress and current. To efficiently investigate the disparity between microscopic and macroscopic properties, a new method is introduced for processing microgram quantities of CNTs into highly oriented and well-packed fibers. CNTs are dissolved into chlorosulfonic acid and processed into aligned films; each film can be peeled and twisted into multiple discrete fibers. Fibers fabricated by this method and solution-spinning are directly compared to determine the impact of alignment, twist, packing density, and length. Surprisingly, these discrete fibers can be twice as strong as their solution-spun counterparts despite a lower degree of alignment. Strength appears to be more sensitive to internal twist and packing density, while fiber conductivity is essentially equivalent among the two sets of samples. Importantly, this rapid fiber manufacturing method uses three orders of magnitude less material than solution spinning, expanding the experimental parameter space and enabling the exploration of unique CNT sources. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrated optical-fiber capillary electrophoresis microchips with novel spin-on-glass surface modification.

PubMed

Lin, Che-Hsin; Lee, Gwo-Bin; Fu, Lung-Ming; Chen, Shu-Hui

2004-07-30

This paper presents a novel micro-capillary electrophoresis (CE) chip with embedded optical fibers for the on-line detection of DNA samples. The optical fibers are pre-etched and then inserted directly into fiber channels incorporated within low-cost soda-lime glass substrates. The embedded optical fibers are precisely aligned with the microfluidic channels such that the induced fluorescence signals from labeled bio-samples can be detected. This arrangement avoids the requirement for delicate optical alignment procedures and equipment. Surface modification of the CE channels is accomplished by means of a simple and reliable organic-based spin-on-glass (SOG) method. The zeta potential distribution and the corresponding electroosmotic mobility of the fluid are simulated numerically for the modified and non-modified channel surfaces, and then both sets of results are verified experimentally. The present results indicate that the value of the zeta potential for a surface with an SOG coating is 19.3 times smaller than that of an untreated surface. A phiX-174 DNA marker fluid is used to evaluate the injection and separation performance of the developed micro-CE device. Furthermore, the long-term stability of the SOG-coated surface is also investigated. The experimental data reveal that the microchip device is capable of providing highly efficient separations of bio-molecules, and that the SOG layer retains its low zeta potential characteristics for at least 45 days. The present results confirm the effectiveness of the proposed micro-CE chip in performing the on-line detection of DNA samples, and indicate that the SOG process represents a simple and reliable solution for the surface modification of glass-based microchannels.

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.

Multicolor, Fluorescent Supercapacitor Fiber.

PubMed

Liao, Meng; Sun, Hao; Zhang, Jing; Wu, Jingxia; Xie, Songlin; Fu, Xuemei; Sun, Xuemei; Wang, Bingjie; Peng, Huisheng

2017-10-05

Fiber-shaped supercapacitors have attracted broad attentions from both academic and industrial communities due to the demonstrated potentials as next-generation power modules. However, it is important while remains challenging to develop dark-environment identifiable supercapacitor fibers for enhancement on operation convenience and security in nighttime applications. Herein, a novel family of colorful fluorescent supercapacitor fibers has been produced from aligned multi-walled carbon nanotube sheets. Fluorescent dye particles are introduced and stably anchored on the surfaces of aligned multi-walled carbon nanotubes to prepare hybrid fiber electrodes with a broad range of colors from red to purple. The fluorescent component in the dye introduces fluorescent indication capability to the fiber, which is particularly promising for flexible and wearable devices applied in dark environment. In addition, the colorful fluorescent supercapacitor fibers also maintain high electrochemical performance under cyclic bending and charge-discharge processes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical Links and RF Distribution for Antenna Arrays

NASA Technical Reports Server (NTRS)

Huang, Shouhua; Calhoun, Malcolm; Tjoelker, Robert

2006-01-01

An array of three antennas has recently been developed at the NASA Jet Propulsion Laboratory capable of detecting signals at X and Ka band. The array requires a common frequency reference and high precision phase alignment to correlate received signals. Frequency and timing references are presently provided from a remotely located hydrogen maser and clock through a combination of commercially and custom developed optical links. The selected laser, photodetector, and fiber components have been tested under anticipated thermal and simulated antenna rotation conditions. The resulting stability limitations due to thermal perturbations or induced stress on the optical fiber have been characterized. Distribution of the X band local oscillator includes a loop back and precision phase monitor to enable correlation of signals received from each antenna.

Nanotopography guides and directs cell migration in amoeboid and epithelial cells

NASA Astrophysics Data System (ADS)

Lee, Rachel; Das, Satarupa; Hourwitz, Matthew; Sun, Xiaoyu; Parent, Carole; Fourkas, John; Losert, Wolfgang

Cell migration plays a critical role in development, angiogenesis, immune response, wound healing, and cancer metastasis. In many cases, cells also move in the context of a matrix of collagen fibers, and the alignment of these fibers can both affect the migration phenotype and guide cells. Here we show that both fast and slow migrating cells - amoeboid HL-60 and epithelial MCF10A - are affected in similar ways by micro/nanostructures with dimensions similar to those of collagen fibers. Cell alignment enhances the efficiency of migration by increasing directional persistence.

Precision wood particle feedstocks

DOEpatents

Dooley, James H; Lanning, David N

2013-07-30

Wood particles having fibers aligned in a grain, wherein: the wood particles are characterized by a length dimension (L) aligned substantially parallel to the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L; the L.times.H dimensions define two side surfaces characterized by substantially intact longitudinally arrayed fibers; the W.times.H dimensions define two cross-grain end surfaces characterized individually as aligned either normal to the grain or oblique to the grain; the L.times.W dimensions define two substantially parallel top and bottom surfaces; and, a majority of the W.times.H surfaces in the mixture of wood particles have end checking.

Development of an embedded instrument for autofocus and polarization alignment of polarization maintaining fiber

NASA Astrophysics Data System (ADS)

Feng, Di; Fang, Qimeng; Huang, Huaibo; Zhao, Zhengqi; Song, Ningfang

2017-12-01

The development and implementation of a practical instrument based on an embedded technique for autofocus and polarization alignment of polarization maintaining fiber is presented. For focusing efficiency and stability, an image-based focusing algorithm fully considering the image definition evaluation and the focusing search strategy was used to accomplish autofocus. For improving the alignment accuracy, various image-based algorithms of alignment detection were developed with high calculation speed and strong robustness. The instrument can be operated as a standalone device with real-time processing and convenience operations. The hardware construction, software interface, and image-based algorithms of main modules are described. Additionally, several image simulation experiments were also carried out to analyze the accuracy of the above alignment detection algorithms. Both the simulation results and experiment results indicate that the instrument can achieve the accuracy of polarization alignment <±0.1 deg.

Effect of Age and Proteoglycan Deficiency on Collagen Fiber Re-Alignment and Mechanical Properties in Mouse Supraspinatus Tendon

PubMed Central

Connizzo, Brianne K.; Sarver, Joseph J.; Iozzo, Renato V.; Birk, David E.; Soslowsky, Louis J.

2013-01-01

Collagen fiber realignment is one mechanism by which tendon responds to load. Re-alignment is altered when the structure of tendon is altered, such as in the natural process of aging or with alterations of matrix proteins, such as proteoglycan expression. While changes in re-alignment and mechanical properties have been investigated recently during development, they have not been studied in (1) aged tendons, or (2) in the absence of key proteoglycans. Collagen fiber re-alignment and the corresponding mechanical properties are quantified throughout tensile mechanical testing in both the insertion site and the midsubstance of mouse supraspinatus tendons in wild type (WT), decorin-null (Dcn-/-), and biglycan-null (Bgn-/-) mice at three different ages (90 days, 300 days, and 570 days). Percent relaxation was significantly decreased with age in the WT and Dcn-/- tendons, but not in the Bgn-/- tendons. Changes with age were found in the linear modulus at the insertion site where the 300 day group was greater than the 90 day and 570 day group in the Bgn-/- tendons and the 90 day group was smaller than the 300 day and 570 day groups in the Dcn-/- tendons. However, no changes in modulus were found across age in WT tendons were found. The midsubstance fibers of the WT and Bgn-/- tendons were initially less aligned with increasing age. The re-alignment was significantly altered with age in the WT tendons, with older groups responding to load later in the mechanical test. This was also seen in the Dcn-/- midsubstance and the Bgn-/- insertion, but not in the other locations. Although some studies have found changes in the WT mechanical properties with age, this study did not support those findings. However, it did show fiber re-alignment changes at both locations with age, suggesting a breakdown of tendon′s ability to respond to load in later ages. In the proteoglycan-null tendons however, there were changes in the mechanical properties, accompanied only by location-dependent re-alignment changes, suggesting a site-specific role for these molecules in loading. Finally, changes in the mechanical properties did not occur in concert with changes in re-alignment, suggesting that typical mechanical property measurements alone are insufficient to describe how structural alterations affect tendon′s response to load. PMID:23445064

Generation of contractile actomyosin bundles depends on mechanosensitive actin filament assembly and disassembly

PubMed Central

Tojkander, Sari; Gateva, Gergana; Husain, Amjad; Krishnan, Ramaswamy; Lappalainen, Pekka

2015-01-01

Adhesion and morphogenesis of many non-muscle cells are guided by contractile actomyosin bundles called ventral stress fibers. While it is well established that stress fibers are mechanosensitive structures, physical mechanisms by which they assemble, align, and mature have remained elusive. Here we show that arcs, which serve as precursors for ventral stress fibers, undergo lateral fusion during their centripetal flow to form thick actomyosin bundles that apply tension to focal adhesions at their ends. Importantly, this myosin II-derived force inhibits vectorial actin polymerization at focal adhesions through AMPK-mediated phosphorylation of VASP, and thereby halts stress fiber elongation and ensures their proper contractility. Stress fiber maturation additionally requires ADF/cofilin-mediated disassembly of non-contractile stress fibers, whereas contractile fibers are protected from severing. Taken together, these data reveal that myosin-derived tension precisely controls both actin filament assembly and disassembly to ensure generation and proper alignment of contractile stress fibers in migrating cells. DOI: http://dx.doi.org/10.7554/eLife.06126.001 PMID:26652273

Generation of contractile actomyosin bundles depends on mechanosensitive actin filament assembly and disassembly.

PubMed

Tojkander, Sari; Gateva, Gergana; Husain, Amjad; Krishnan, Ramaswamy; Lappalainen, Pekka

2015-12-10

Adhesion and morphogenesis of many non-muscle cells are guided by contractile actomyosin bundles called ventral stress fibers. While it is well established that stress fibers are mechanosensitive structures, physical mechanisms by which they assemble, align, and mature have remained elusive. Here we show that arcs, which serve as precursors for ventral stress fibers, undergo lateral fusion during their centripetal flow to form thick actomyosin bundles that apply tension to focal adhesions at their ends. Importantly, this myosin II-derived force inhibits vectorial actin polymerization at focal adhesions through AMPK-mediated phosphorylation of VASP, and thereby halts stress fiber elongation and ensures their proper contractility. Stress fiber maturation additionally requires ADF/cofilin-mediated disassembly of non-contractile stress fibers, whereas contractile fibers are protected from severing. Taken together, these data reveal that myosin-derived tension precisely controls both actin filament assembly and disassembly to ensure generation and proper alignment of contractile stress fibers in migrating cells.

3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

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

Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignmentmore » within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Moreover, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.« less

3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

DOE PAGES

Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; ...

2017-03-06

Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignmentmore » within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Moreover, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.« less

Comparison of laboratory calibrations of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at the beginning and end of the first flight season

NASA Technical Reports Server (NTRS)

Vane, Gregg; Chrien, Thomas G.; Reimer, John H.; Green, Robert O.; Conel, James E.

1988-01-01

Spectral and radiometric calibrations of AVIRIS are described together with changes in instrument characteristics that occurred during the flight season. These changes include detachment of the optical fibers to two of the four AVIRIS spectrometers, degradation in the optical alignment of the spectrometers due to thermally induced and mechanical warpage, and breakage of a thermal blocking filter in one of the spectrometers. Means of improving the instrument are discussed.

Modeling and Predicting the Stress Relaxation of Composites with Short and Randomly Oriented Fibers

PubMed Central

Obaid, Numaira; Sain, Mohini

2017-01-01

The addition of short fibers has been experimentally observed to slow the stress relaxation of viscoelastic polymers, producing a change in the relaxation time constant. Our recent study attributed this effect of fibers on stress relaxation behavior to the interfacial shear stress transfer at the fiber-matrix interface. This model explained the effect of fiber addition on stress relaxation without the need to postulate structural changes at the interface. In our previous study, we developed an analytical model for the effect of fully aligned short fibers, and the model predictions were successfully compared to finite element simulations. However, in most industrial applications of short-fiber composites, fibers are not aligned, and hence it is necessary to examine the time dependence of viscoelastic polymers containing randomly oriented short fibers. In this study, we propose an analytical model to predict the stress relaxation behavior of short-fiber composites where the fibers are randomly oriented. The model predictions were compared to results obtained from Monte Carlo finite element simulations, and good agreement between the two was observed. The analytical model provides an excellent tool to accurately predict the stress relaxation behavior of randomly oriented short-fiber composites. PMID:29053601

The role of 3D microenvironmental organization in MCF-7 epithelial–mesenchymal transition after 7 culture days

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

Foroni, Laura; Vasuri, Francesco, E-mail: vasurifrancesco@libero.it; Chair of Vascular Surgery, Department of Specialistic Surgery and Anaesthesiological Sciences, S. Orsola-Malpighi Hospital, Bologna University

2013-06-10

We present a multi-technique study on in vitro epithelial–mesenchymal transition (EMT) in human MCF-7 cells cultured on electrospun scaffolds of poly(L-lactic acid) (PLA), with random and aligned fiber orientations. Our aim is to investigate the morphological and genetic characteristics induced by extracellular matrix in tumor cells cultured in different 3D environments, and at different time points. Cell vitality was assessed with AlamarBlue at days 1, 3, 5 and 7. Scanning electron microscopy was performed at culture days 3 and 7. Immunohistochemistry (for E-cadherin, β-catenin, cytokeratins, nucleophosmin, tubulin, Ki-67 and vimentin), immunofluorescence (for F-actin) western blot (for E-cadherin, β-catenin and vimentin)more » and transmission electron microscopy were carried out at day 7. An EMT gene array followed by PCR analysis confirmed the regulation of selected genes. At day 7, scanning electron microscopy on aligned-PLA revealed spindle-shaped cells gathered in buds and ribbon-like structures, with a higher nucleolar/nuclear ratio and a loss in E-cadherin and β-catenin at immunohistochemistry and western blot. An up-regulation of SMAD2, TGF-β2, TFPI2 and SOX10 was found in aligned-PLA compared to random-PLA cultured cells. The topography of the extracellular matrix has a role in tumor EMT, and a more aggressive phenotype characterizes MCF-7 cells cultured on aligned-PLA scaffold. -- Highlights: • After 7 culture days an aligned-PLA scaffold induces a spindle shape to MCF-7 cells. • Despite these changes, the aligned MCF-7 cells keep an epithelial phenotype. • The extracellular environment alone influences the E-cadherin/β-catenin axis. • The extracellular environment can promote the epithelial–mesenchymal transition.« less

EphA2 and Src regulate equatorial cell morphogenesis during lens development

PubMed Central

Cheng, Catherine; Ansari, Moham M.; Cooper, Jonathan A.; Gong, Xiaohua

2013-01-01

High refractive index and transparency of the eye lens require uniformly shaped and precisely aligned lens fiber cells. During lens development, equatorial epithelial cells undergo cell-to-cell alignment to form meridional rows of hexagonal cells. The mechanism that controls this morphogenesis from randomly packed cuboidal epithelial cells to highly organized hexagonal fiber cells remains unknown. In Epha2-/- mouse lenses, equatorial epithelial cells fail to form precisely aligned meridional rows; moreover, the lens fulcrum, where the apical tips of elongating epithelial cells constrict to form an anchor point before fiber cell differentiation and elongation at the equator, is disrupted. Phosphorylated Src-Y424 and cortactin-Y466, actin and EphA2 cluster at the vertices of wild-type hexagonal epithelial cells in organized meridional rows. However, phosphorylated Src and phosphorylated cortactin are not detected in disorganized Epha2-/- cells with altered F-actin distribution. E-cadherin junctions, which are normally located at the basal-lateral ends of equatorial epithelial cells and are diminished in newly differentiating fiber cells, become widely distributed in the apical, lateral and basal sides of epithelial cells and persist in differentiating fiber cells in Epha2-/- lenses. Src-/- equatorial epithelial cells also fail to form precisely aligned meridional rows and lens fulcrum. These results indicate that EphA2/Src signaling is essential for the formation of the lens fulcrum. EphA2 also regulates Src/cortactin/F-actin complexes at the vertices of hexagonal equatorial cells for cell-to-cell alignment. This mechanistic information explains how EphA2 mutations lead to disorganized lens cells that subsequently contribute to altered refractive index and cataracts in humans and mice. PMID:24026120

Polymer based nanocomposites with nanofibers and exfoliated clay

NASA Technical Reports Server (NTRS)

Meador, Michael A.; Reneker, Darrell H.

2005-01-01

Polymer solutions, containing clay sheets, were electrospun into nanofibers and microfibers that contained clay sheets inside. Controllable removal of polymer by plasma etching from the surface of fibers revealed the arrangement of clay. The shape, flexibility, size distribution and arrangement of clay sheets were observed by transmission and scanning electron microscopy. The clay sheets were partially aligned in big fibers with normal direction of clay sheets perpendicular to fiber axis. Crumpling of clay sheets inside fibers was observed when the fiber diameter was comparable to the lateral size of clay sheets. Single sheets of clay were observed both by catching clay sheets dispersed in water with electrospun nanofiber mats and by the deliberate removal of most of the polymer in the fibers. Thin, flexible gas barrier films, that are reasonably strong, were assembled from clay sheets and polymer nanofibers. Structure of composite films was characterized with scanning electron microscopy. Continuous film of clay sheets were physically attached to the surface of fiber mats. Spincoating film of polymer and clay sheets was reinforced by electrospun fiber scaffold. Certain alignment of clay sheets was observed in the vicinity of fibers.

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,

Engineering poly(hydroxy butyrate-co-hydroxy valerate) based vascular scaffolds to mimic native artery.

PubMed

Deepthi, S; Nivedhitha Sundaram, M; Vijayan, Ponni; Nair, Shantikumar V; Jayakumar, R

2018-04-01

Electrospun tri-layered fibrous scaffold incorporating VEGF and Platelet Factor Concentrate (PFC) in multiple layers having different layer architectures was designed to mimic native artery. The scaffold consisted of longitudinally aligned poly(hydroxy butyrate-co-hydroxy valerate) (PHBV) and poly(vinyl alcohol) (PVA) nanofibers (inner layer), radially aligned PHBV-elastin nanofibers (middle layer) to provide the bi-directional alignment and combination of longitudinally aligned PHBV-elastin and random PHBV/PVA multiscale fibers (peripheral layer). Tubular constructs of diameter <6 mm were developed. The developed electrospun fibers were characterised by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy and Tensile tests. Further the burst strength, compliance and stiffness index of tri-layered tubular scaffold was evaluated. SEM images of fibrous layers showed the typical longitudinal and radial alignment of fibers in the tubular construct. SEM images showed that the prepared PHBV nanofibers were in the range of 500-800 nm and PHBV microfibers were of 1-2 μm in diameter in the tri-layered electrospun membrane. PVA nanofibers were of size 200-250 nm. The tensile strength, percentage compliance and stiffness index of tri-layered membrane was in accordance with that of native small blood vessels. The developed tri-layered membrane was blood compatible, with hemolysis degree 0.85 ± 0.21% and did not activate platelets. Controlled release of VEGF and PFC was observed from the scaffold. The biocompatibility of the tri-layered scaffold was evaluated using HUVECs, SMCs and MSCs and SMCs infiltration from the outer layer was also evaluated. Specific protein expression for the HUVECs and SMCs was evaluated by flow cytometry and immunocytochemistry. HUVECs and SMCs exhibited good elongation and alignment along the direction of fibers and was found to maintain its CD31, VE-Cadherin and αSMA expression respectively. The results highlight the importance of bi-directional fiber alignment on the tri-layered electrospun scaffold as a suitable architectural prototype for vascular scaffolds to mimic the native arteries. Copyright © 2017 Elsevier B.V. All rights reserved.

Rigid Amorphous Fraction in PLA Electrospun Fibers

NASA Astrophysics Data System (ADS)

Cebe, Peggy; Ma, Qian; Simona Cozza, Erika; Pyda, Marek; Mao, Bin; Zhu, Yazhe; Monticelli, Orietta

2013-03-01

Electrospun fibers of poly(lactic acid) (PLA) were formed by adopting a high-speed rotating wheel as the counter-electrode. The molecular orientation, crystallization mechanism, and phase structure and transitions of the aligned ES fibers were investigated. Using thermal analysis and wide angle X-ray scattering (WAXS), we evaluated the confinement that exists in as-spun amorphous, and heat-treated semicrystalline, fibers. Differential scanning calorimetry confirmed the existence of a constrained amorphous phase in as-spun aligned fibers, without the presence of crystals or fillers to serve as fixed physical constraints. Using WAXS, for the first time the mesophase fraction, consisting of oriented amorphous PLA chains, was quantitatively characterized in nanofibers. The authors acknowledge support from the National Science Foundation, Polymers Program under grant DMR-0602473. ESC acknowledges a Ph.D. grant supported by Italian Ministry of Education and Scientific Research.

Laser printed glass planar lightwave circuits with integrated fiber alignment structures

NASA Astrophysics Data System (ADS)

Desmet, A.; Radosavljevic, A.; Missinne, J.; Van Thourhout, D.; Van Steenberge, G.

2018-02-01

Femtosecond laser inscription allows straightforward manufacturing of glass planar lightwave circuits such as waveguides, interferometers, directional couplers, resonators and more complex structures. Fiber alignment structures are needed to facilitate communication with the glass planar lightwave circuit. In this study, a technique is described to create optical waveguides and alignment structures in the same laser exposure step. Using an industrial ytterbium-doped 1030 nm fiber laser pulses of 400 fs were focused into glass with a 0.4 NA objective causing permanent alteration of the material. Depending on laser parameters this modification allows direct writing of waveguides or the creation of channels after exposing the irradiated volumes to an etchant such as KOH. Writing of channels and waveguides with different laser powers, frequencies, polarisations, stage translation speeds and scan densities were investigated in fused silica and borosilicate glass. Waveguides with controlled dimensions were created, as well as etched U-grooves with a diameter of 126 μm and a sidewall roughness Ra of 255 nm. Cut back measurements were performed giving a waveguide propagation loss of 1.1 dB/cm in borosilicate glass. A coupling loss of 0.7 dB was measured for a transition between the waveguide and standard single mode fiber at 1550 nm, using index matching liquid. The described technique eliminates active alignment requirements and is useful for many applications such as microfluidic sensing, PLCs, fan-out connectors for multicore fibers and quantum optical networks.

Fabrication and mechanical behavior of dye-doped polymer optical fiber

NASA Astrophysics Data System (ADS)

Jiang, Changhong; Kuzyk, Mark G.; Ding, Jow-Lian; Johns, William E.; Welker, David J.

2002-07-01

The purpose of this article is to study the materials physics behind dye-doped polymethyl metharcylate (PMMA) that is important for the optical fiber drawing process. We report effects of the fabrication process on the mechanical properties of the final fiber. The qualitative degree of polymer chain alignment is found to increase with the drawing force, which in turn decreases with the drawing temperature and increases with the drawing ratio. The chain alignment relaxes when the fibers are annealed at 95 degC with a commensurate decrease in fiber length and increase in diameter. The annealed fiber has higher ductility but lower strength than the unannealed fiber. Both the yield and tensile strengths are dependent on the strain rate. The relationship between tensile strength, sigmab, and fiber diameter, d, is found empirically to be sigmab[is proportional to]d-0.5. The yield strength appears to be less sensitive to the fiber diameter than the tensile strength. For PMMA doped with disperse red 1 azo dye, the yield strength, tensile strength, and Young's modulus peak at a dye concentration of 0.0094 wt %. These results are useful for designing polymer optical fibers with well-defined mechanical properties.

High-throughput and high-yield fabrication of uniaxially-aligned chitosan-based nanofibers by centrifugal electrospinning

PubMed Central

Erickson, Ariane E.; Edmondson, Dennis; Chang, Fei-Chien; Wood, Dave; Gong, Alex; Levengood, Sheeny Lan; Zhang, Miqin

2016-01-01

The inability to produce large quantities of nanofibers has been a primary obstacle in advancement and commercialization of electrospinning technologies, especially when aligned nanofibers are desired. Here, we present a high-throughput centrifugal electrospinning (HTP-CES) system capable of producing a large number of highly-aligned nanofiber samples with high-yield and tunable diameters. The versatility of the design was revealed when bead-less nanofibers were produced from copolymer chitosan/polycaprolactone (C-PCL) solutions despite variations in polymer blend composition or spinneret needle gauge. Compared to conventional electrospinning techniques, fibers spun with the HTP-CES not only exhibited superior alignment, but also better diameter uniformity. Nanofiber alignment was quantified using Fast Fourier Transform (FFT) analysis. In addition, a concave correlation between the needle diameter and resultant fiber diameter was identified. This system can be easily scaled up for industrial production of highly-aligned nanofibers with tunable diameters that can potentially meet the requirements for various engineering and biomedical applications. PMID:26428148

Epitaxially grown collagen fibrils reveal diversity in contact guidance behavior among cancer cells.

PubMed

Wang, Juan; Petefish, Joseph W; Hillier, Andrew C; Schneider, Ian C

2015-01-01

Invasion of cancer cells into the surrounding tissue is an important step during cancer progression and is driven by cell migration. Cell migration can be random, but often it is directed by various cues such as aligned fibers composed of extracellular matrix (ECM), a process called contact guidance. During contact guidance, aligned fibers bias migration along the long axis of the fibers. These aligned fibers of ECM are commonly composed of type I collagen, an abundant structural protein around tumors. In this paper, we epitaxially grew several different patterns of organized type I collagen on mica and compared the morphology and contact guidance behavior of two invasive breast cancer cell lines (MDA-MB-231 and MTLn3 cells). Others have shown that these cells randomly migrate in qualitatively different ways. MDA-MB-231 cells exert large traction forces, tightly adhere to the ECM, and migrate with spindle-shaped morphology and thus adopt a mesenchymal mode of migration. MTLn3 cells exert small traction forces, loosely adhere to the ECM, and migrate with a more rounded morphology and thus adopt an amoeboid mode of migration. As the degree of alignment of type I collagen fibrils increases, cells become more elongated and engage in more directed contact guidance. MDA-MB-231 cells perceive the directional signal of highly aligned type I collagen fibrils with high fidelity, elongating to large extents and migrating directionally. Interestingly, behavior in MTLn3 cells differs. While highly aligned type I collagen fibril patterns facilitate spreading and random migration of MTLn3 cells, they do not support elongation or directed migration. Thus, different contact guidance cues bias cell migration differently and the fidelity of contact guidance is cell type dependent, suggesting that ECM alignment is a permissive cue for contact guidance, but requires a cell to have certain properties to interpret that cue.

Nanofiber alignment of a small diameter elastic electrospun scaffold

NASA Astrophysics Data System (ADS)

Patel, Jignesh

Cardiovascular disease is the leading cause of death in western countries with coronary heart disease making up 50% of these deaths. As a treatment option, tissue engineered grafts have great potential. Elastic scaffolds that mimic arterial extracellular matrix (ECM) may hold the key to creating viable vascular grafts. Electrospinning is a widely used scaffold fabrication technique to engineer tubular scaffolds. In this study, we investigated how the collector rotation speed altered the nanofiber alignment which may improve mechanical characteristics making the scaffold more suitable for arterial grafts. The scaffold was fabricated from a blend of PCL/Elastin. 2D Fast Fourier Transform (FFT) image processing tool and MatLab were used to quantitatively analyze nanofiber orientation at different collector speeds (13500 to 15500 rpm). Both Image J and MatLab showed graphical peaks indicating predominant fiber orientation angles. A collector speed of 15000 rpm was found to produce the best nanofiber alignment with narrow peaks at 90 and 270 degrees, and a relative amplitude of 200. This indicates a narrow distribution of circumferentially aligned nanofibers. Collector speeds below and above 15000 rpm caused a decrease in fiber alignment with a broader orientation distribution. Uniformity of fiber diameter was also measured. Of 600 measures from the 15000 rpm scaffolds, the fiber diameter range from 500 nm to 899 nm was most prevalent. This diameter range was slightly larger than native ECM which ranges from 50 nm to 500 nm. The second most prevalent diameter range had an average of 404 nm which is within the diameter range of collagen. This study concluded that with proper electrospinning technique and collector speed, it is possible to fabricate highly aligned small diameter elastic scaffolds. Image J 2D FFT results confirmed MatLab findings for the analyses of circumferentially aligned nanofibers. In addition, MatLab analyses simplified the FFT orientation data providing an accurate, user friendly orientation measurement tool.

Alignment reference device

DOEpatents

Patton, Gail Y.; Torgerson, Darrel D.

1987-01-01

An alignment reference device provides a collimated laser beam that minimizes angular deviations therein. A laser beam source outputs the beam into a single mode optical fiber. The output end of the optical fiber acts as a source of radiant energy and is positioned at the focal point of a lens system where the focal point is positioned within the lens. The output beam reflects off a mirror back to the lens that produces a collimated beam.

Transfer of vertically aligned carbon nanofibers to polydimethylsiloxane (PDMS) while maintaining their alignment and impalefection functionality.

PubMed

Pearce, Ryan C; Railsback, Justin G; Anderson, Bryan D; Sarac, Mehmet F; McKnight, Timothy E; Tracy, Joseph B; Melechko, Anatoli V

2013-02-01

Vertically aligned carbon nanofibers (VACNFs) are synthesized on Al 3003 alloy substrates by direct current plasma-enhanced chemical vapor deposition. Chemically synthesized Ni nanoparticles were used as the catalyst for growth. The Si-containing coating (SiN(x)) typically created when VACNFs are grown on silicon was produced by adding Si microparticles prior to growth. The fiber arrays were transferred to PDMS by spin coating a layer on the grown substrates, curing the PDMS, and etching away the Al in KOH. The fiber arrays contain many fibers over 15 μm (long enough to protrude from the PDMS film and penetrate cell membranes) and SiN(x) coatings as observed by SEM, EDX, and fluorescence microscopy. The free-standing array in PDMS was loaded with pVENUS-C1 plasmid and human brain microcapillary endothelial (HBMEC) cells and was successfully impalefected.

Flexible polymeric rib waveguide with self-align couplers system

PubMed Central

Huang, Cheng-Sheng; Wang, Wei-Chih

2011-01-01

The authors report a polymeric based rib waveguide with U shape self-align fiber couplers system using a simple micromolding process with SU8 as a molding material and polydimethysiloxane as a waveguide material. The material is used for its good optical transparency, low surface tension, biocompatibility, and durability. Furthermore, the material is highly formable. This unique fabrication molding technique provides a means of keeping the material and manufacturing costs to a minimum. The self-align fiber couplers system also proves a fast and simple means of light coupling. The flexible nature of the waveguide material makes this process ideal for a potential wearable optical sensor. PMID:22171151

Precision wood particle feedstocks with retained moisture contents of greater than 30% dry basis

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

Dooley, James H; Lanning, David N

Wood particles having fibers aligned in a grain, wherein: the wood particles are characterized by a length dimension (L) aligned substantially parallel to the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L; the L.times.H dimensions define two side surfaces characterized by substantially intact longitudinally arrayed fibers; the W.times.H dimensions define two cross-grain end surfaces characterized individually as aligned either normal to the grain or oblique to the grain; the L.times.W dimensions define two substantially parallel top and bottom surfaces; and, a majority of the W.times.H surfacesmore » in the mixture of wood particles have end checking.« less

Secondary electron emission yield from high aspect ratio carbon velvet surfaces

DOE PAGES

Jin, Chenggang; Ottaviano, Angelica; Raitses, Yevgeny

2017-11-01

The plasma electrons bombarding a plasma-facing wall surface can induce secondary electron emission (SEE) from the wall. A strong SEE can enhance the power losses by reducing the wall sheath potential and thereby increasing the electron flux from the plasma to the wall. The use of the materials with surface roughness and the engineered materials with surface architecture is known to reduce the effective SEE by trapping the secondary electrons. In this work, we demonstrate a 65% reduction of SEE yield using a velvet material consisting of high aspect ratio carbon fibers. The measurements of SEE yield for different velvetmore » samples using the electron beam in vacuum demonstrate the dependence of the SEE yield on the fiber length and the packing density, which is strongly affected by the alignment of long velvet fibers with respect to the electron beam impinging on the velvet sample. Furthermore, the results of SEE measurements support the previous observations of the reduced SEE measured in Hall thrusters.« less

An optical biosensor using MEMS-based V-grooves

NASA Astrophysics Data System (ADS)

Tian, Ye; Ma, Xiaodong; Zou, Xiaotian; Wu, Nan; Wang, Xingwei

2011-05-01

An optical fiber biosensor featuring miniaturization, electromagnetic interference (EMI)-immunity, and flexibility is presented. The sensor was fabricated by aligning two gold-deposited optical single-mode fiber facets inside V-grooves on a silicon chip to form a Fabry-Perot (FP) cavity. The mirrors on the fiber facets were made of deposited gold (Au) films, which provided a high finesse to produce a highly sensitivity. Microelectromechanical systems (MEMS) fabrication techniques were used to precisely control the profile and angle of the V-grooves on the silicon. The biotin-terminated thiol molecule was firstly immobilized on the gold surface. Subsequently, the molecules of Neutravidin were specifically bound to the biotin-terminated self-assembled monolayers (SAMs). The induced changes of cavity length and refractive index (RI) upon the gold surface lead to an optical path difference (OPD) of the FP cavity, which was detected by demodulating the transmission spectrum phase shift. By taking advantage of MEMS techniques, multiple biosensors can be integrated into one small silicon chip for detecting various biomolecule targets simultaneously.

Secondary electron emission yield from high aspect ratio carbon velvet surfaces

NASA Astrophysics Data System (ADS)

Jin, Chenggang; Ottaviano, Angelica; Raitses, Yevgeny

2017-11-01

The plasma electrons bombarding a plasma-facing wall surface can induce secondary electron emission (SEE) from the wall. A strong SEE can enhance the power losses by reducing the wall sheath potential and thereby increasing the electron flux from the plasma to the wall. The use of the materials with surface roughness and the engineered materials with surface architecture is known to reduce the effective SEE by trapping the secondary electrons. In this work, we demonstrate a 65% reduction of SEE yield using a velvet material consisting of high aspect ratio carbon fibers. The measurements of SEE yield for different velvet samples using the electron beam in vacuum demonstrate the dependence of the SEE yield on the fiber length and the packing density, which is strongly affected by the alignment of long velvet fibers with respect to the electron beam impinging on the velvet sample. The results of SEE measurements support the previous observations of the reduced SEE measured in Hall thrusters.

A Thermally Insulating Textile Inspired by Polar Bear Hair.

PubMed

Cui, Ying; Gong, Huaxin; Wang, Yujie; Li, Dewen; Bai, Hao

2018-04-01

Animals living in the extremely cold environment, such as polar bears, have shown amazing capability to keep warm, benefiting from their hollow hairs. Mimicking such a strategy in synthetic fibers would stimulate smart textiles for efficient personal thermal management, which plays an important role in preventing heat loss and improving efficiency in house warming energy consumption. Here, a "freeze-spinning" technique is used to realize continuous and large-scale fabrication of fibers with aligned porous structure, mimicking polar bear hairs, which is difficult to achieve by other methods. A textile woven with such biomimetic fibers shows an excellent thermal insulation property as well as good breathability and wearability. In addition to passively insulating heat loss, the textile can also function as a wearable heater, when doped with electroheating materials such as carbon nanotubes, to induce fast thermal response and uniform electroheating while maintaining its soft and porous nature for comfortable wearing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cardiac differentiation of cardiosphere-derived cells in scaffolds mimicking morphology of the cardiac extracellular matrix.

PubMed

Xu, Yanyi; Patnaik, Sourav; Guo, Xiaolei; Li, Zhenqing; Lo, Wilson; Butler, Ryan; Claude, Andrew; Liu, Zhenguo; Zhang, Ge; Liao, Jun; Anderson, Peter M; Guan, Jianjun

2014-08-01

Stem cell therapy has the potential to regenerate heart tissue after myocardial infarction (MI). The regeneration is dependent upon cardiac differentiation of the delivered stem cells. We hypothesized that timing of the stem cell delivery determines the extent of cardiac differentiation as cell differentiation is dependent on matrix properties such as biomechanics, structure and morphology, and these properties in cardiac extracellular matrix (ECM) continuously vary with time after MI. In order to elucidate the relationship between ECM properties and cardiac differentiation, we created an in vitro model based on ECM-mimicking fibers and a type of cardiac progenitor cell, cardiosphere-derived cells (CDCs). A simultaneous fiber electrospinning and cell electrospraying technique was utilized to fabricate constructs. By blending a highly soft hydrogel with a relatively stiff polyurethane and modulating fabrication parameters, tissue constructs with similar cell adhesion property but different global modulus, single fiber modulus, fiber density and fiber alignment were achieved. The CDCs remained alive within the constructs during a 1week culture period. CDC cardiac differentiation was dependent on the scaffold modulus, fiber volume fraction and fiber alignment. Two constructs with relatively low scaffold modulus, ∼50-60kPa, most significantly directed the CDC differentiation into mature cardiomyocytes as evidenced by gene expressions of cardiac troponin T (cTnT), calcium channel (CACNA1c) and cardiac myosin heavy chain (MYH6), and protein expressions of cardiac troponin I (cTnI) and connexin 43 (CX43). Of these two low-modulus constructs, the extent of differentiation was greater for lower fiber alignment and higher fiber volume fraction. These results suggest that cardiac ECM properties may have an effect on cardiac differentiation of delivered stem cells. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Advancing flexible volatile compound sensors using liquid crystals encapsulated in polymer fibers

NASA Astrophysics Data System (ADS)

Reyes, Catherine G.; Lagerwall, Jan P. F.

2018-02-01

Until recently, organic vapor sensors using liquid crystals (LCs) have employed rigid glass substrates for confining the LC, and bulky equipment for vapor detection. Previously, we demonstrated that coaxially electrospinning nematic LC within the core of polymer fibers provides an alternative and improved form factor for confinement. This enables ppm level sensitivity to harmful industrial organics, such as toluene, while giving the flexibility of textile-like sheets (imparted by polymer encapsulation). Moreover, toluene vapor responses of the LC-core fiber mats were visible macroscopically with the naked eye depending on the morphology of the fibers produced, and whether they were oriented in specific geometries (aligned, or random). We identified two types of responses: one corresponds to the LC transition from nematic to isotropic, and the other we suggest is due to an anchoring change at the LC-polymer interface that influences the alignment. While we need to study the presence that defects can have in more detail, we noted that fiber mat thickness is crucial in attempting to understand how and why we are able to visualize two responses in aligned LC-fiber mats. Ultimately, we noted that the response of the polymer sheath itself (softening) to organic vapor exposure affects the liquid crystal confinement in the core. From the microscopic point of view, this will influence the threshold concentration that fibers in a mat will overall respond to. In this paper we will discuss three findings the morphologies enabling LC-core fiber mat response to vapor seen both micro- and macroscopically, how thickness of the fiber mat can play a role in the visualization of the responses, and the effect that the polymer structure has in the mat's sensitivity threshold.

Synergetic effect of topological cue and periodic mechanical tension-stress on osteogenic differentiation of rat bone mesenchymal stem cells.

PubMed

Liu, Yao; Yang, Guang; Ji, Huanzhong; Xiang, Tao; Luo, En; Zhou, Shaobing

2017-06-01

Mesenchymal stem cells (MSCs) are able to self-renew and differentiate into tissues of mesenchymal origin, making them to be significant for cell-based therapies, such as metabolic bone diseases and bone repair. Regulating the differentiation of MSCs is significant for bone regeneration. Electrospun fibers mimicking natural extracellular matrix (ECM), is an effective artificial ECM to regulate the behaviors and fates of MSCs. The aligned electrospun fibers can modulate polar cell pattern of bone mesenchymal stem cells, which leads to more obvious osteogenic differentiation. Apart from the topographic effect of electrospun fibers, mechanical cues can also intervene the cell behaviors. In this study, the osteogenic differentiation of rat bone mesenchymal stem cells was evaluated, which were cultured on aligned/random electrospun fiber mats materials under mechanical tension intervention. Scanning electron microscope and immune-fluorescent staining were used to directly observe the polarity changing of cellular morphology and cytoskeleton. The results proved that aligned electrospun fibers could be more conducive to promote osteogenic differentiation of rat bone mesenchymal stem cells and this promotion of osteogenic differentiation was enhanced by tension intervention. These results were correlated to the quantitative real-time PCR assay. In general, culturing rat bone mesenchymal stem cells on electrospun fibers under the intervention of mechanical tension is an effective way to mimic a more real cellular microenvironment. Copyright © 2017 Elsevier B.V. All rights reserved.

Coiled fiber scaffolds embedded with gold nanoparticles improve the performance of engineered cardiac tissues

NASA Astrophysics Data System (ADS)

Fleischer, Sharon; Shevach, Michal; Feiner, Ron; Dvir, Tal

2014-07-01

Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold.Coiled perimysial fibers within the heart muscle provide it with the ability to contract and relax efficiently. Here, we report on a new nanocomposite scaffold for cardiac tissue engineering, integrating coiled electrospun fibers with gold nanoparticles. Cultivation of cardiac cells within the hybrid scaffolds promoted cell organization into elongated and aligned tissues generating a strong contraction force, high contraction rate and low excitation threshold. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00300d

Nanofiber Orientation and Surface Functionalization Modulate Human Mesenchymal Stem Cell Behavior In Vitro

PubMed Central

Kolambkar, Yash M.; Bajin, Mehmet; Wojtowicz, Abigail; Hutmacher, Dietmar W.; García, Andrés J.

2014-01-01

Electrospun nanofiber meshes have emerged as a new generation of scaffold membranes possessing a number of features suitable for tissue regeneration. One of these features is the flexibility to modify their structure and composition to orchestrate specific cellular responses. In this study, we investigated the effects of nanofiber orientation and surface functionalization on human mesenchymal stem cell (hMSC) migration and osteogenic differentiation. We used an in vitro model to examine hMSC migration into a cell-free zone on nanofiber meshes and mitomycin C treatment to assess the contribution of proliferation to the observed migration. Poly (ɛ-caprolactone) meshes with oriented topography were created by electrospinning aligned nanofibers on a rotating mandrel, while randomly oriented controls were collected on a stationary collector. Both aligned and random meshes were coated with a triple-helical, type I collagen-mimetic peptide, containing the glycine-phenylalanine-hydroxyproline-glycine-glutamate-arginine (GFOGER) motif. Our results indicate that nanofiber GFOGER peptide functionalization and orientation modulate cellular behavior, individually, and in combination. GFOGER significantly enhanced the migration, proliferation, and osteogenic differentiation of hMSCs on nanofiber meshes. Aligned nanofiber meshes displayed increased cell migration along the direction of fiber orientation compared to random meshes; however, fiber alignment did not influence osteogenic differentiation. Compared to each other, GFOGER coating resulted in a higher proliferation-driven cell migration, whereas fiber orientation appeared to generate a larger direct migratory effect. This study demonstrates that peptide surface modification and topographical cues associated with fiber alignment can be used to direct cellular behavior on nanofiber mesh scaffolds, which may be exploited for tissue regeneration. PMID:24020454

Align and random electrospun mat of PEDOT:PSS and PEDOT:PSS/RGO

NASA Astrophysics Data System (ADS)

Sarabi, Ghazale Asghari; Latifi, Masoud; Bagherzadeh, Roohollah

2018-01-01

In this research work we fabricated two ultrafine conductive nanofibrous layers to investigate the materilas composition and their properties for the preparation of supercapacitor materials application. In first layer, a polymer and a conductive polymer were used and second layer was a composition of polymer, conductive polymer and carbon-base material. In both cases align and randomized mat of conductive nanofibers were fabricated using electrospinning set up. Conductive poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT:PSS) nanofibers were electrospun by dissolving fiber-forming polymer and polyvinyl alcohol (PVA) in an aqueous dispersion of PEDOT:PSS. The effect of addition of reduced graphene oxide (RGO) was considered for nanocomposite layer. The ultrafine conductive polymer fibers and conductive nanocomposite fibrous materials were also fabricated using an electrospinning process. A fixed collector and a rotating drum were used for random and align nanofibers production, respectively. The resulted fibers were characterized and analyzed by SEM, FTIR and two-point probe conductivity test. The average diameter of nanofibers measured by ImageJ software indicated that the average fiber diameter for first layer was 100 nm and for nanocomposite layer was about 85 nm. The presence of PEDOT:PSS and RGO in the nanofibers was confirmed by FT-IR spectroscopy. The conductivity of align and random layers was characterized. The conductivity of PEDOT:PSS nanofibers showed higher enhancement by addition of RGO in aqueous dispersion. The obtained results showed that alignment of fibrous materials can be considered as an engineering tool for tuning the conductivity of fibrous materials for many different applications such as supercapacitors, conductive and transparent materials.

Nanofibers grafted on titanium alloy: the effects of fiber alignment and density on osteoblast mineralization.

PubMed

Lin, Hsin-Yi; Peng, Zhao-Xiang

2017-08-17

The surface of medical implant alloy Ti-6Al-4V was chemically modified to allow it to covalently bond with collagen/PVA nanofibers. These nanofibers were successfully attached to the Ti-6Al-4V surface in three different morphologies: randomly oriented high-density fiber, COL(H); randomly oriented low-density fiber, COL(L); and aligned high-density fiber, COL(A). The effects of the morphology of these covalently-bound collagen nanofibers on the growth and differentiation of osteoblasts were studied for 21 days. The low-density nanofibers covered approximately 80% of the Ti64 surface, while the high-density nanofibers covered nearly 100%. These covalently attached fibrous coatings remained attached to the metal surface after 3 weeks of cell culture. In the first week the aligned fibers of COL(A) allowed the osteoblasts to stretch and elongate in the direction of the fibers. This directional elongation was not seen in the cells on the randomly-oriented samples. Cells proliferated and differentiated on all three surfaces over time. By the end of the test, the amount of type I collagen secreted by the cells on COL(H) was the highest, while the degree of mineralization was highest on COL(A) among the three samples (p < 0.05). Different nanofiber morphologies changed the cell morphology and the secretion of cellular products. The mechanisms remained to be investigated. The surface of medical implant alloy Ti-6Al-4V was chemically modified to allow it to covalently bond with collagen/PVA nanofibers. The SEM micrographs in the top row show the random and aligned morphology of the collagen-PVA nanofibers. The nanofibers on COL(A) were aligned in the general direction indicated by the arrow. The second row are images from EDX titanium element mapping. The location of the titanium elements are shown as bright dots. The low-density nanofibers, COL(L), covered approximately 80% of the Ti64 surface, while the high-density nanofibers, COL(H) and COL(A), covered nearly 100%. All three surfaces demonstrated good biocompatibility for the cultured osteoblasts. The fiber alignment seemed to have an effect on early cellular morphology (day 7), collagen secretion and calcium deposition, while the density of the fibers seemed to have no significant effect on cell behavior. SEM micrographs of osteoblasts after 7 and 14 days of cell culture are shown in the third and fourth rows. The surface of COL(L) has more cell-free spots indicated by (*) on day 7 as other two surfaces were covered by cells. The nanofibers could no longer be observed and were covered with mineralized granules (circles) after 14 days of cell culture. The cells appear stretched out on the mineralized granules.

Cell-cell interactions mediate cytoskeleton organization and collective endothelial cell chemotaxis.

PubMed

Shamloo, Amir

2014-09-01

This study investigates the role of cell-cell and cell-ligand interactions in cytoskeleton organization of endothelial cells (ECs) and their directional migration within a microfluidic device. The migration of ECs in response to a biochemical factor was studied. Mathematical analysis of the cell migration pathways and cellular cytoskeleton revealed that directional migration, migration persistence length, migration speed, and cytoskeletal stress fiber alignment can be mediated by the level of cell contacts as well as the presence or absence of a biochemical polarizing factor. It was shown that in the presence of a biochemical polarizing factor, higher cell density and more frequent cell contacts has a reinforcing effect on collective cell chemotaxis. In contrast, in the absence of a polarizing factor, high cell density can decrease or suppress the ability of the cells to migrate. Also, the correlation of actin stress fiber organization and alignment with directional migration of ECs was investigated. It was shown that in the presence of a biochemical polarizing factor, stress fibers within the cytoskeleton of ECs can be significantly aligned parallel to the gradient direction when the cells have higher level of contacts. The results also show that the organization and alignment of actin stress fibers is mediated by cell adhesion junctions during collective cell migration and introduce cell-cell interactions as a key factor during collective cell chemotaxis. © 2014 Wiley Periodicals, Inc.

Regionally variant collagen alignment correlates with viscoelastic properties of the disc of the human temporomandibular joint.

PubMed

Gutman, Shawn; Kim, Daniel; Tarafder, Solaiman; Velez, Sergio; Jeong, Julia; Lee, Chang H

2018-02-01

To determine the regionally variant quality of collagen alignment in human TMJ discs and its statistical correlation with viscoelastic properties. For quantitative analysis of the quality of collagen alignment, horizontal sections of human TMJ discs with Pricrosirius Red staining were imaged under circularly polarized microscopy. Mean angle and angular deviation of collagen fibers in each region were analyzed using a well-established automated image-processing for angular gradient. Instantaneous and relaxation moduli of each disc region were measured under stress-relaxation test both in tensile and compression. Then Spearman correlation analysis was performed between the angular deviation and the moduli. To understand the effect of glycosaminoglycans on the correlation, TMJ disc samples were treated by chondroitinase ABC (C-ABC). Our imaging processing analysis showed the region-variant direction of collagen alignment, consistently with previous findings. Interestingly, the quality of collagen alignment, not only the directions, was significantly different in between the regions. The angular deviation of fiber alignment in the anterior and intermediate regions were significantly smaller than the posterior region. Medial and lateral regions showed significantly bigger angular deviation than all the other regions. The regionally variant angular deviation values showed statistically significant correlation with the tensile instantaneous modulus and the relaxation modulus, partially dependent on C-ABC treatment. Our findings suggest the region-variant degree of collagen fiber alignment is likely attributed to the heterogeneous viscoelastic properties of TMJ disc that may have significant implications in development of regenerative therapy for TMJ disc. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mode Selection for a Single-Frequency Fiber Laser

NASA Technical Reports Server (NTRS)

Liu, Jian

2010-01-01

A superstructured fiber-grating-based mode selection filter for a single-frequency fiber laser eliminates all free-space components, and makes the laser truly all-fiber. A ring cavity provides for stable operations in both frequency and power. There is no alignment or realignment required. After the fibers and components are spliced together and packaged, there is no need for specially trained technicians for operation or maintenance. It can be integrated with other modules, such as telescope systems, without extra optical alignment due to the flexibility of the optical fiber. The filter features a narrow line width of 1 kHz and side mode suppression ratio of 65 dB. It provides a high-quality laser for lidar in terms of coherence length and signal-to-noise ratio, which is 20 dB higher than solid-state or microchip lasers. This concept is useful in material processing, medical equipment, biomedical instrumentation, and optical communications. The pulse-shaping fiber laser can be directly used in space, airborne, and satellite applications including lidar, remote sensing, illuminators, and phase-array antenna systems.

Carbon nanotube fiber spun from wetted ribbon

DOEpatents

Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

2014-04-29

A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

MEMS Integrated Submount Alignment for Optoelectronics

NASA Astrophysics Data System (ADS)

Shakespeare, W. Jeffrey; Pearson, Raymond A.; Grenestedt, Joachim L.; Hutapea, Parsaoran; Gupta, Vikas

2005-02-01

One of the most expensive and time-consuming production processes for single-mode fiber-optic components is the alignment of the photonic chip or waveguide to the fiber. The alignment equipment is capital intensive and usually requires trained technicians to achieve desired results. Current technology requires active alignment since tolerances are only ~0.2 μ m or less for a typical laser diode. This is accomplished using piezoelectric actuated stages and active optical feedback. Joining technologies such as soldering, epoxy bonding, or laser welding may contribute significant postbond shift, and final coupling efficiencies are often less than 80%. This paper presents a method of adaptive optical alignment to freeze in place directly on an optical submount using a microelectromechanical system (MEMS) shape memory alloy (SMA) actuation technology. Postbond shift is eliminated since the phase change is the alignment actuation. This technology is not limited to optical alignment but can be applied to a variety of MEMS actuations, including nano-actuation and nano-alignment for biomedical applications. Experimental proof-of-concept results are discussed, and a simple analytical model is proposed to predict the stress strain behavior of the optical submount. Optical coupling efficiencies and alignment times are compared with traditional processes. The feasibility of this technique in high-volume production is discussed.

Cyclic mechanical stretch contributes to network development of osteocyte-like cells with morphological change and autophagy promotion but without preferential cell alignment in rat.

PubMed

Inaba, Nao; Kuroshima, Shinichiro; Uto, Yusuke; Sasaki, Muneteru; Sawase, Takashi

2017-09-01

Osteocytes play important roles in controlling bone quality as well as preferential alignment of biological apatite c -axis/collagen fibers. However, the relationship between osteocytes and mechanical stress remains unclear due to the difficulty of three-dimensional (3D) culture of osteocytes in vitro . The aim of this study was to investigate the effect of cyclic mechanical stretch on 3D-cultured osteocyte-like cells. Osteocyte-like cells were established using rat calvarial osteoblasts cultured in a 3D culture system. Cyclic mechanical stretch (8% amplitude at a rate of 2 cycles min -1 ) was applied for 24, 48 and 96 consecutive hours. Morphology, cell number and preferential cell alignment were evaluated. Apoptosis- and autophagy-related gene expression levels were measured using quantitative PCR. 3D-cultured osteoblasts became osteocyte-like cells that expressed osteocyte-specific genes such as Dmp1 , Cx43 , Sost , Fgf23 and RANKL , with morphological changes similar to osteocytes. Cell number was significantly decreased in a time-dependent manner under non-loaded conditions, whereas cyclic mechanical stretch significantly prevented decreased cell numbers with increased expression of anti-apoptosis-related genes. Moreover, cyclic mechanical stretch significantly decreased cell size and ellipticity with increased expression of autophagy-related genes, LC3b and atg7 . Interestingly, preferential cell alignment did not occur, irrespective of mechanical stretch. These findings suggest that an anti-apoptotic effect contributes to network development of osteocyte-like cells under loaded condition. Spherical change of osteocyte-like cells induced by mechanical stretch may be associated with autophagy upregulation. Preferential alignment of osteocytes induced by mechanical load in vivo may be partially predetermined before osteoblasts differentiate into osteocytes and embed into bone matrix.

Electrospun meshes possessing region-wise differences in fiber orientation, diameter, chemistry and mechanical properties for engineering bone-ligament-bone tissues.

PubMed

Samavedi, Satyavrata; Vaidya, Prasad; Gaddam, Prudhvidhar; Whittington, Abby R; Goldstein, Aaron S

2014-12-01

Although bone-patellar tendon-bone (B-PT-B) autografts are the gold standard for repair of anterior cruciate ligament ruptures, they suffer from drawbacks such as donor site morbidity and limited supply. Engineered tissues modeled after B-PT-B autografts are promising alternatives because they have the potential to regenerate connective tissue and facilitate osseointegration. Towards the long-term goal of regenerating ligaments and their bony insertions, the objective of this study was to construct 2D meshes and 3D cylindrical composite scaffolds - possessing simultaneous region-wise differences in fiber orientation, diameter, chemistry and mechanical properties - by electrospinning two different polymers from off-set spinnerets. Using a dual drum collector, 2D meshes consisting of an aligned polycaprolactone (PCL) fiber region, randomly oriented poly(lactide-co-glycolide) (PLGA) fiber region and a transition region (comprised of both PCL and PLGA fibers) were prepared, and region-wise differences were confirmed by microscopy and tensile testing. Bone marrow stromal cells (BMSCs) cultured on these meshes exhibited random orientations and low aspect ratios on the random PLGA regions, and high aspect ratios and alignment on the aligned PCL regions. Next, meshes containing an aligned PCL region flanked by two transition regions and two randomly oriented PLGA regions were prepared and processed into 3D cylindrical composite scaffolds using an interpenetrating photo-crosslinkable polyethylene glycol diacrylate hydrogel to recapitulate the shape of B-PT-B autografts. Tensile testing indicated that cylindrical composites were mechanically robust, and eventually failed due to stress concentration in the aligned PCL region. In summary, this study demonstrates a process to fabricate electrospun meshes possessing region-wise differences in properties that can elicit region-dependent cell responses, and be readily processed into scaffolds with the shape of B-PT-B autografts. © 2014 Wiley Periodicals, Inc.

bFGF-containing electrospun gelatin scaffolds with controlled nano-architectural features for directed angiogenesis

PubMed Central

Montero, Ramon B.; Vial, Ximena; Nguyen, Dat Tat; Farhand, Sepehr; Reardon, Mark; Pham, Si M.; Tsechpenakis, Gavriil; Andreopoulos, Fotios M.

2011-01-01

Current therapeutic angiogenesis strategies are focused on the development of biologically responsive scaffolds that can deliver multiple angiogenic cytokines and/or cells in ischemic regions. Herein, we report on a novel electrospinning approach to fabricate cytokine-containing nanofibrous scaffolds with tunable architecture to promote angiogenesis. Fiber diameter and uniformity were controlled by varying the concentration of the polymeric (i.e. gelatin) solution, the feed rate, needle to collector distance, and electric field potential between the collector plate and injection needle. Scaffold fiber orientation (random vs. aligned) was achieved by alternating the polarity of two parallel electrodes placed on the collector plate thus dictating fiber deposition patterns. Basic fibroblast growth factor (bFGF) was physically immobilized within the gelatin scaffolds at variable concentrations and human umbilical vein endothelial cells (HUVEC) were seeded on the top of the scaffolds. Cell proliferation and migration was assessed as a function of growth factor loading and scaffold architecture. HUVECs successfully adhered onto gelatin B scaffolds and cell proliferation was directly proportional to the loading concentrations of the growth factor (0–100 bFGF ng/mL). Fiber orientation had a pronounced effect on cell morphology and orientation. Cells were spread along the fibers of the electrospun scaffolds with the aligned orientation and developed a spindle-like morphology parallel to the scaffold's fibers. In contrast, cells seeded onto the scaffolds with random fiber orientation, did not demonstrate any directionality and appeared to have a rounder shape. Capillary formation (i.e. sprouts length and number of sprouts per bead), assessed in a 3-D in vitro angiogenesis assay, was a function of bFGF loading concentration (0 ng, 50 ng and 100 ng per scaffold) for both types of electrospun scaffolds (i.e. with aligned or random fiber orientation). PMID:22200610

Nucleation, Growth, and Alignment of Poly(3-hexylthiophene) Nanofibers for High-Performance OFETs.

PubMed

Persson, Nils E; Chu, Ping-Hsun; McBride, Michael; Grover, Martha; Reichmanis, Elsa

2017-04-18

Conjugated semiconducting polymers have been the subject of intense study for over two decades with promising advances toward a printable electronics manufacturing ecosystem. These materials will deliver functional electronic devices that are lightweight, flexible, large-area, and cost-effective, with applications ranging from biomedical sensors to solar cells. Synthesis of novel molecules has led to significant improvements in charge carrier mobility, a defining electrical performance metric for many applications. However, the solution processing and thin film deposition of conjugated polymers must also be properly controlled to obtain reproducible device performance. This has led to an abundance of research on the process-structure-property relationships governing the microstructural evolution of the model semicrystalline poly(3-hexylthiophene) (P3HT) as applied to organic field effect transistor (OFET) fabrication. What followed was the production of an expansive body of work on the crystallization, self-assembly, and charge transport behavior of this semiflexible polymer whose strong π-π stacking interactions allow for highly creative methods of structural control, including the modulation of solvent and solution properties, flow-induced crystallization and alignment techniques, structural templating, and solid-state thermal and mechanical processing. This Account relates recent progress in the microstructural control of P3HT thin films through the nucleation, growth, and alignment of P3HT nanofibers. Solution-based nanofiber formation allows one to develop structural order prior to thin film deposition, mitigating the need for intricate deposition processes and enabling the use of batch and continuous chemical processing steps. Fiber growth is framed as a traditional crystallization problem, with the balance between nucleation and growth rates determining the fiber size and ultimately the distribution of grain boundaries in the solid state. Control of nucleation can be accomplished through a sonication-based seeding procedure, while growth can be modulated through supersaturation control via the tuning of solvent quality, the use of UV irradiation or through aging. These principles carry over to the flow-induced growth of P3HT nanofibers in a continuous microfluidic processing system, leading to thin films with significantly enhanced mobility. Further gains can be made by promoting long-range polymer chain alignment, achieved by depositing nanofibers through shear-based coating methods that promote high fiber packing density and alignment. All of these developments in processing were carried out on a standard OFET platform, enabling us to generalize quantitative structure-property relationships from structural data sources such as UV-vis, AFM, and GIWAXS. It is shown that a linear correlation exists between mobility and the in-plane orientational order of nanofibers, as extracted from AFM images using advanced computer vision software developed by our group. Herein, we discuss data-driven approaches to the determination of process-structure-property relationships, as well as the transferability of structural control strategies for P3HT to other conjugated polymer systems and applications.

Cholesterol depletion by methyl-beta-cyclodextrin enhances myoblast fusion and induces the formation of myotubes with disorganized nuclei.

PubMed

Mermelstein, Cláudia S; Portilho, Débora M; Medeiros, Rommel B; Matos, Aline R; Einicker-Lamas, Marcelo; Tortelote, Giovane G; Vieyra, Adalberto; Costa, Manoel L

2005-02-01

The formation of a skeletal muscle fiber begins with the withdrawal of committed mononucleated precursors from the cell cycle. These myoblasts elongate while aligning with each other, guided by recognition between their membranes. This step is followed by cell fusion and the formation of long striated multinucleated myotubes. We used methyl-beta-cyclodextrin (MCD) in primary cultured chick skeletal muscle cells to deplete membrane cholesterol and investigate its role during myogenesis. MCD promoted a significant increase in the expression of troponin T, enhanced myoblast fusion, and induced the formation of large multinucleated myotubes with nuclei being clustered centrally and not aligned at the cell periphery. MCD myotubes were striated, as indicated by sarcomeric alpha-actinin staining, and microtubule and desmin filament distribution was not altered. Pre-fusion MCD-treated myoblasts formed large aggregates, with cadherin and beta-catenin being accumulated in cell adhesion contacts. We also found that the membrane microdomain marker GM1 was not present as clusters in the membrane of MCD-treated myoblasts. Our data demonstrate that cholesterol is involved in the early steps of skeletal muscle differentiation.

[Fiber-reinforced composite in fixed prosthodontics].

PubMed

Pilo, R; Abu Rass, Z; Shmidt, A

2010-07-01

Fiber reinforced composite (FRC) is composed of resin matrix and fibers filler. Common types of fibers: polyethylene, carbon and glass. Fibers can be continuous and aligned, discontinuous and aligned, discontinuous and randomly oriented. The architecture of the fibers is unidirectional, woven or braided. The two main types are: dry fibers or impregnated. Inclusion of fibers to resin composite increased its average flexural strength in 100-200 MPa. FRC can be utilized by the dentist in direct approach (splinting, temporary winged bridge) or indirect approach (laboratory made fixed partial denture). Laboratory fixed partial denture (FPD) is made from FRC substructure and Hybrid/Microfill particulate composite veneer. Main indications: interim temporary FPD or FPD in cases of questionable abutment teeth, in aesthetic cases where All Ceram FPD is not feasible. Retention is attained by adhesive cementation to minimally prepared teeth or to conventionally prepared teeth; other options are inlay-onlay bridges or hybrid bridges. Contraindications are: poor hygiene, inability to control humidity, parafunction habits, and more than two pontics. Survival rate of FRC FPD over 5 years is 75%, lower compared to porcelain fused to metal FPD which is 95%. Main reasons for failure are: fracture of framework and delamination of the veneer. Part of the failures is repairable.

Single mode fiber and twin-core fiber connection technique for in-fiber integrated interferometer

NASA Astrophysics Data System (ADS)

Yuan, Tingting; Zhang, Xiaotong; Guan, Chunying; Yang, Xinghua; Yuan, Libo

2015-09-01

A novel twin-core fiber connector has been made by two side-polished fibers. By using side polishing technique, we present a connector based on the twin-core fiber (TCF) and two D-shaped single-core fibers. After simple alignment and splicing, all fiber miniaturizing connector can be obtained. Two cores can operate independently and are non-interfering. The coupling loss of this connector is low and the fabrication technologies are mature. The connector device could be used for sensors or particle trapping.

Fiber link design for the NASA-NSF extreme precision Doppler spectrograph concept "WISDOM"

NASA Astrophysics Data System (ADS)

Fżrész, Gábor; Pawluczyk, Rafal; Fournier, Paul; Simcoe, Robert; Woods, Deborah F.

2016-08-01

We describe the design of the fiber-optic coupling and light transfer system of the WISDOM (WIYN Spectrograph for DOppler Monitoring) instrument. As a next-generation Precision Radial Velocity (PRV) spectrometer, WISDOM incorporates lessons learned from HARPS about thermal, pressure, and gravity control, but also takes new measures to stabilize the spectrograph illumination, a subject that has been overlooked until recently. While fiber optic links provide more even illumination than a conventional slit, careful engineering of the interface is required to realize their full potential. Conventional round fiber core geometries have been used successfully in conjunction with optical double scramblers, but such systems still retain a memory of the input illumination that is visible in systems seeking sub-m/s PRV precision. Noncircular fibers, along with advanced optical scramblers, and careful optimization of the spectrograph optical system itself are therefore necessary to study Earth-sized planets. For WISDOM, we have developed such a state-of-the-art fiber link concept. Its design is driven primarily by PRV requirements, but it also manages to preserve high overall throughput. Light from the telescope is coupled into a set of six, 32 μm diameter octagonal core fibers, as high resolution is achieved via pupil slicing. The low-OH, step index, fused silica, FBPI-type fibers are custom designed for their numerical aperture that matches the convergence of the feeding beam and thus minimizes focal ratio degradation at the output. Given the demanding environment at the telescope the fiber end tips are mounted in a custom fused silica holder, providing a perfect thermal match. We used a novel process, chemically assisted photo etching, to manufacture this glass fiber holder. A single ball-lens scrambler is inserted into the 25m long fibers. Employing an anti-reflection (AR) coated, high index, cubic-zirconia ball lens the alignment of the scrambler components are straightforward, as the fiber end tips (also AR coated) by design touch the ball lens and thus eliminate spacing tolerances. A clever and simple opto-mechanical design and assembly process assures micron-level self-alignment, yielding a 87% throughput and a scrambling gain of >20,000. To mitigate modal noise the individual fibers then subsequently combined into a pair of rectangular fibers, providing a much larger modal area thanks to the 34x106 micron diameter. To minimize slit height, and thus better utilize detector area, the octagonal cores are brought very close together in this transition. The two outer fibers are side polished at one side, into a D-shaped cladding, while the central fiber has a dual side polish. These tapered, side-flattening operations are executed with precise alignment to the octagonal core. Thus the cores of the 3 fibers are brought together and aligned within few microns of each other before spliced onto the rectangular fiber. Overall throughput kept high and FRD at bay by careful management of fiber mounting, vacuum feed-through, application of efficient AR coatings, and implementation of thermal breaks that allow for independent expansion of the fibers and the protective tubing.

The aortic valve microstructure: effects of transvalvular pressure.

PubMed

Sacks, M S; Smith, D B; Hiester, E D

1998-07-01

We undertook this study to establish a more quantitative understanding of the microstructural response of the aortic valve cusp to pressure loading. Fresh porcine aortic valves were fixed at transvalvular pressures ranging from 0 mmHg to 90 mmHg, and small-angle light scattering (SALS) was used to quantify the gross fiber structure of the valve cusps. At all pressures the fiber-preferred directions coursed along the circumferential direction. Increasing transvalvular pressure induced the greatest changes in fiber alignment between 0 and 1 mmHg, with no detectable change past 4 mmHg. When the fibrosa and ventricularis layers of the cusps were re-scanned separately, the fibrosa layer revealed a higher degree of orientation while the ventricularis was more randomly oriented. The degree of fiber orientation for both layers became more similar once the transvalvular pressure exceeded 4 mmHg, and the layers were almost indistinguishable by 60 mmHg. It is possible that, in addition to retracting the aortic cusp during systole, the ventricularis mechanically may contribute to the diastolic cuspal stiffness at high transvalvular pressures, which may help to prevent over distention of the cusp. Our results suggest a complex, highly heterogeneous structural response to transvalvular pressure on a fiber level that will have to be duplicated in future bioprosthetic heart valve designs.

Engineered plant biomass particles coated with biological agents

DOEpatents

Dooley, James H.; Lanning, David N.

2014-06-24

Plant biomass particles coated with a biological agent such as a bacterium or seed, characterized by a length dimension (L) aligned substantially parallel to a grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. In particular, the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces.

Collagen Fiber Orientation in Primate Long Bones.

PubMed

Warshaw, Johanna; Bromage, Timothy G; Terranova, Carl J; Enlow, Donald H

2017-07-01

Studies of variation in orientation of collagen fibers within bone have lead to the proposition that these are preferentially aligned to accommodate different kinds of load, with tension best resisted by fibers aligned longitudinally relative to the load, and compression best resisted by transversely aligned fibers. However, previous studies have often neglected to consider the effect of developmental processes, including constraints on collagen fiber orientation (CFO), particularly in primary bone. Here we use circularly polarized light microscopy to examine patterns of CFO in cross-sections from the midshaft femur, humerus, tibia, radius, and ulna in a range of living primate taxa with varied body sizes, phylogenetic relationships and positional behaviors. We find that a preponderance of longitudinally oriented collagen is characteristic of both periosteal primary and intracortically remodeled bone. Where variation does occur among groups, it is not simply understood via interpretations of mechanical loads, although prioritized adaptations to tension and/or shear are considered. While there is some suggestion that CFO may correlate with body size, this relationship is neither consistent nor easily explicable through consideration of size-related changes in mechanical adaptation. The results of our study indicate that there is no clear relationship between CFO and phylogenetic status. One of the principle factors accounting for the range of variation that does exist is primary tissue type, where slower depositing bone is more likely to comprise a larger proportion of oblique to transverse collagen fibers. Anat Rec, 300:1189-1207, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Measurements of Inertial Torques on Sedimenting Fibers

NASA Astrophysics Data System (ADS)

Hamati, Rami; Roy, Anubhab; Koch, Don; Voth, Greg

2017-11-01

Stokes flow solutions predict that ellipsoids sedimenting in quiescent fluid keep their initial orientation. However, preferential alignment in low Reynolds number sedimentation is easily observed. For example, sun dogs form from alignment of sedimenting ice crystals. The cause of this preferential alignment is a torque due to non-zero fluid inertia that aligns particles with a long axis in the horizontal direction. These torques are predicted analytically for slender fibers with low Reynolds number based on the fiber diameter (ReD) by Khayat and Cox (JFM 209:435, 1989). Despite increasingly widespread use of these expressions, we did not find experimental measurements of these inertial torques at parameters where the theory was valid, so we performed a set of sedimentation experiments using fore-aft symmetric cylinders and asymmetric cylinders with their center of mass offset from their center of drag. Measured rotation rates as a function of orientation using carefully prepared glass capillaries in silicon oil show good agreement with the theory. We quantify the effect of finite tank size and compare with other experiments in water where the low ReD condition is not met. Supported by Army Research Office Grant W911NF1510205.

Fiber Development and Matrix Production in Tissue Engineered Menisci using Bovine Mesenchymal Stem Cells and Fibrochondrocytes

PubMed Central

McCorry, Mary Clare; Bonassar, Lawrence J.

2017-01-01

Mesenchymal stem cells (MSCs) have been investigated with promising results for meniscus healing and tissue engineering. While MSCs are known to contribute to ECM production, less is known about how MSCs produce and align large organized fibers for application to tissue engineering the meniscus. The goal of this study was to investigate the capability of MSCs to produce and organize extracellular matrix molecules compared to meniscal fibrochondrocytes (FCCs). Bovine FCCs and MSCs were encapsulated in an anatomically accurate collagen meniscus using mono-culture and co-culture of each cell type. Each meniscus was mechanically anchored at the horns to mimic the physiological fixation by the meniscal entheses. Mechanical fixation generates a static mechanical boundary condition previously shown to induce formation of oriented fiber by FCCs. Samples were cultured for 4 weeks and then evaluated for biochemical composition and fiber development. MSCs increased the GAG and collagen production in both co-culture and mono-culture groups compared to FCC mono-culture. Collagen organization was greatest in the FCC mono-culture group. While MSCs had increased matrix production they lacked the fiber organization capabilities of FCCs. This study suggests that GAG production and fiber formation are linked. Co-culture can be used as a means of balancing the synthetic properties of MSCs and the matrix remodeling capabilities of FCCs for tissue engineering applications. PMID:27925474

Electrospun fiber surface nanotopography influences astrocyte-mediated neurite outgrowth.

PubMed

Johnson, Christopher D; D'Amato, Anthony R; Puhl, Devan L; Wich, Douglas M; Vespermann, Amanda; Gilbert, Ryan J

2018-05-15

Aligned, electrospun fiber scaffolds provide topographical guidance for regenerating neurons and glia after central nervous system injury. To date, no study has explored how fiber surface nanotopography affects astrocyte response to fibrous scaffolds. Astrocytes play important roles in the glial scar, the blood brain barrier, and in maintaining homeostasis in the central nervous system. In this study, electrospun poly L-lactic acid fibers were engineered with smooth, pitted, or divoted surface nanotopography. Cortical or spinal cord primary rat astrocytes were cultured on the surfaces for either 1 or 3 days to examine the astrocyte response over time. The results showed that cortical astrocytes were significantly shorter and broader on the pitted and divoted fibers compared to those on smooth fibers. However, spinal cord astrocyte morphology was not significantly altered by the surface features. These findings indicate that astrocytes from unique anatomical locations respond differently to the presence of nanotopography. Western Blot results show that the differences in morphology were not associated with significant changes in GFAP or vinculin in either astrocyte population, suggesting that surface pits and divots do not induce a reactive phenotype in either cortical or spinal cord astrocytes. Finally, astrocytes were co-cultured with dorsal root ganglia to determine how the surfaces affected astrocyte-mediated neurite outgrowth. Astrocytes cultured on the fibers for shorter periods of time (1 day) generally supported longer neurite outgrowth. Pitted and divoted fibers restricted spinal cord astrocyte-mediated neurite outgrowth, while smooth fibers increased 3 day spinal cord astrocyte-mediated neurite outgrowth. In total, fiber surface nanotopography can influence astrocyte elongation and influence the capability of astrocytes to direct neurites. Therefore, fiber surface characteristics should be carefully controlled to optimize astrocyte-mediated axonal regeneration. . © 2018 IOP Publishing Ltd.

Generation of Spatially Aligned Collagen Fiber Networks through Microtransfer Molding

PubMed Central

Naik, Nisarga; Caves, Jeffrey

2013-01-01

The unique biomechanical properties of native tissue are governed by the organization and composition of integrated collagen and elastin networks. We report an approach for fabricating spatially aligned, fiber-reinforced composites (FRC) with adjustable collagen fiber dimensions, layouts, and distribution within an elastin-like protein matrix yielding a biocomposite with controllable mechanical responses. Microtransfer molding is employed for the fabrication of hollow and solid collagen fibers with straight or crimped fiber geometries. Collagen fibers (width: 2 – 50 μm, thickness: 300 nm – 3 μm) exhibit a Young’s modulus of 126 ± 61 MPa and an ultimate tensile strength (UTS) of 7 ± 3.2 MPa. As fiber networks within composite structures, straight fiber layouts display orthotropic responses with Young’s modulus ranging from 0.95 ± 0.35 to 10.4 ± 0.5 MPa and tensile strength from 0.22 ± 0.08 to 0.87 ± 0.5 MPa with increasing fraction of collagen fibers (1–10% v/v). In contrast, composites based on crimped fiber layouts exhibit strain-dependent stiffness with an increase in Young’s modulus from 0.7 ± 0.14 MPa to 3.15 ± 0.49 MPa, at a specific transition strain. Through controlling the microstructure of engineered collagen fiber networks, a facile means has been established to control macroscale mechanical responses of composite protein-based materials. PMID:24039146

Electrospun Nanofiber Scaffolds with Gradations in Fiber Organization

PubMed Central

Khandalavala, Karl; Jiang, Jiang; Shuler, Franklin D.; Xie, Jingwei

2015-01-01

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion. PMID:25938562

Fiber coating method

DOEpatents

Corman, Gregory Scot

2003-04-15

A coating is applied to reinforcing fibers arranged into a tow by coaxially aligning the tow with an adjacent separation layer and winding or wrapping the tow and separation layer onto a support structure in an interleaved manner so that the separation layer separates a wrap of the tow from an adjacent wrap of the tow. A coating can then be uniformly applied to the reinforcing fibers without defects caused by fiber tow to fiber tow contact. The separation layer can be a carbon fiber veil.

Electric Field-Assisted Orientation of Short Phosphate Glass Fibers on Stainless Steel for Biomedical Applications.

PubMed

Chen, Qiang; Jing, Jiajia; Qi, Hongfei; Ahmed, Ifty; Yang, Haiou; Liu, Xianhu; Lu, T L; Boccaccini, Aldo R

2018-04-11

Structural and compositional modifications of metallic implant surfaces are being actively investigated to achieve improved bone-to-implant bonding. In this study, a strategy to modify bulk metallic surfaces by electrophoretic deposition (EPD) of short phosphate glass fibers (sPGF) is presented. Random and aligned orientation of sPGF embedded in a poly(acrylic acid) matrix is achieved by vertical and horizontal EPD, respectively. The influence of EPD parameters on the degree of alignment is investigated to pave the way for the fabrication of highly aligned sPGF structures in large areas. Importantly, the oriented sPGF structure in the coating, owing to the synergistic effects of bioactive composition and fiber orientation, plays an important role in directional cell migration and enhanced proliferation. Moreover, gene expression of MC3T3-E1 cells cultured with different concentrations of sPGF is thoroughly assessed to elucidate the potential stimulating effect of sPGF on osteogenic differentiation. This study represents an innovative exploitation of EPD to develop textured surfaces by orientation of fibers in the macroscale, which shows great potential for directional functionalization of metallic implants.

Topography on a subcellular scale modulates cellular adhesions and actin stress fiber dynamics in tumor associated fibroblasts

NASA Astrophysics Data System (ADS)

Azatov, Mikheil; Sun, Xiaoyu; Suberi, Alexandra; Fourkas, John T.; Upadhyaya, Arpita

2017-12-01

Cells can sense and adapt to mechanical properties of their environment. The local geometry of the extracellular matrix, such as its topography, has been shown to modulate cell morphology, migration, and proliferation. Here we investigate the effect of micro/nanotopography on the morphology and cytoskeletal dynamics of human pancreatic tumor-associated fibroblast cells (TAFs). We use arrays of parallel nanoridges with variable spacings on a subcellular scale to investigate the response of TAFs to the topography of their environment. We find that cell shape and stress fiber organization both align along the direction of the nanoridges. Our analysis reveals a strong bimodal relationship between the degree of alignment and the spacing of the nanoridges. Furthermore, focal adhesions align along ridges and form preferentially on top of the ridges. Tracking actin stress fiber movement reveals enhanced dynamics of stress fibers on topographically patterned surfaces. We find that components of the actin cytoskeleton move preferentially along the ridges with a significantly higher velocity along the ridges than on a flat surface. Our results suggest that a complex interplay between the actin cytoskeleton and focal adhesions coordinates the cellular response to micro/nanotopography.

Towards co-packaging of photonics and microelectronics in existing manufacturing facilities

NASA Astrophysics Data System (ADS)

Janta-Polczynski, Alexander; Cyr, Elaine; Bougie, Jerome; Drouin, Alain; Langlois, Richard; Childers, Darrell; Takenobu, Shotaro; Taira, Yoichi; Lichoulas, Ted W.; Kamlapurkar, Swetha; Engelmann, Sebastian; Fortier, Paul; Boyer, Nicolas; Barwicz, Tymon

2018-02-01

The impact of integrated photonics on optical interconnects is currently muted by challenges in photonic packaging and in the dense integration of photonic modules with microelectronic components on printed circuit boards. Single mode optics requires tight alignment tolerance for optical coupling and maintaining this alignment in a cost-efficient package can be challenging during thermal excursions arising from downstream microelectronic assembly processes. In addition, the form factor of typical fiber connectors is incompatible with the dense module integration expected on printed circuit boards. We have implemented novel approaches to interfacing photonic chips to standard optical fibers. These leverage standard high throughput microelectronic assembly tooling and self-alignment techniques resulting in photonic packaging that is scalable in manufacturing volume and in the number of optical IOs per chip. In addition, using dense optical fiber connectors with space-efficient latching of fiber patch cables results in compact module size and efficient board integration, bringing the optics closer to the logic chip to alleviate bandwidth bottlenecks. This packaging direction is also well suited for embedding optics in multi-chip modules, including both photonic and microelectronic chips. We discuss the challenges and rewards in this type of configuration such as thermal management and signal integrity.

Effect of fiber distribution and realignment on the nonlinear and inhomogeneous mechanical properties of human supraspinatus tendon under longitudinal tensile loading.

PubMed

Lake, Spencer P; Miller, Kristin S; Elliott, Dawn M; Soslowsky, Louis J

2009-12-01

Tendon exhibits nonlinear stress-strain behavior that may be partly due to movement of collagen fibers through the extracellular matrix. While a few techniques have been developed to evaluate the fiber architecture of other soft tissues, the organizational behavior of tendon under load has not been determined. The supraspinatus tendon (SST) of the rotator cuff is of particular interest for investigation due to its complex mechanical environment and corresponding inhomogeneity. In addition, SST injury occurs frequently with limited success in treatment strategies, illustrating the need for a better understanding of SST properties. Therefore, the objective of this study was to quantitatively evaluate the inhomogeneous tensile mechanical properties, fiber organization, and fiber realignment under load of human SST utilizing a novel polarized light technique. Fiber distributions were found to become more aligned under load, particularly during the low stiffness toe-region, suggesting that fiber realignment may be partly responsible for observed nonlinear behavior. Fiber alignment was found to correlate significantly with mechanical parameters, providing evidence for strong structure-function relationships in tendon. Human SST exhibits complex, inhomogeneous mechanical properties and fiber distributions, perhaps due to its complex loading environment. Surprisingly, histological grade of degeneration did not correlate with mechanical properties.

Improved Fiber-Optic-Coupled Pressure And Vibration Sensors

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Cuomo, Frank W.

1994-01-01

Improved fiber-optic coupler enables use of single optical fiber to carry light to and from sensor head. Eliminates problem of alignment of multiple fibers in sensor head and simplifies calibration by making performance both more predictable and more stable. Sensitivities increased, sizes reduced. Provides increased margin for design of compact sensor heads not required to contain amplifier circuits and withstand high operating temperatures.

Enlightening the ultrahigh electrical conductivities of doped double-wall carbon nanotube fibers by Raman spectroscopy and first-principles calculations.

PubMed

Tristant, Damien; Zubair, Ahmed; Puech, Pascal; Neumayer, Frédéric; Moyano, Sébastien; Headrick, Robert J; Tsentalovich, Dmitri E; Young, Colin C; Gerber, Iann C; Pasquali, Matteo; Kono, Junichiro; Leotin, Jean

2016-12-01

Highly aligned, packed, and doped carbon nanotube (CNT) fibers with electrical conductivities approaching that of copper have recently become available. These fibers are promising for high-power electrical applications that require light-weight, high current-carrying capacity cables. However, a microscopic understanding of how doping affects the electrical conductance of such CNT fibers in a quantitative manner has been lacking. Here, we performed Raman spectroscopy measurements combined with first-principles calculations to determine the position of the average Fermi energy and to obtain the temperature of chlorosulfonic-acid-doped double-wall CNT fibers under high current. Due to the unique way in which double-wall CNT Raman spectra depend on doping, it is possible to use Raman data to determine the doping level quantitatively. The correspondence between the Fermi level shift and the carbon charge transfer is derived from a tight-binding model and validated by several calculations. For the doped fiber, we were able to associate an average Fermi energy shift of ∼-0.7 eV with a conductance increase by a factor of ∼5. Furthermore, since current induces heating, local temperature determination is possible. Through the Stokes-to-anti-Stokes intensity ratio of the G-band peaks, we estimated a temperature rise at the fiber surface of ∼135 K at a current density of 2.27 × 10 8 A m -2 identical to that from the G-band shift, suggesting that thermalization between CNTs is well achieved.

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.

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.

Design and fabrication of N x N optical couplers based on organic polymer optical waveguides

NASA Astrophysics Data System (ADS)

Krchnavek, Robert R.; Rode, Daniel L.

1994-08-01

In this report, we examine the design and fabrication of a planar, 10x10 optical coupler utilizing photopolymerizable organic polymers. Background information on the theory of operation of the coupler culminating in a set of design equations is presented. The details of the material processing are described, including the preparation of monomer mixtures that result in single-mode polymer waveguides (lambda = 1300 nm) that have core dimensions approximately equal to those of single-mode fiber. This is necessary to insure high coupling efficiency between the planar device and optical fiber. A unique method of aligning and attaching optical fibers to the coupler is demonstrated. This method relies on patterned alignment ways, a transcision cut, and single-mode D-fiber. A theoretical analysis of the in situ monitoring technique used to fabricate the single-mode D-fiber is presented and compared favorably with the experimental results. Finally, the 10x10 coupler is characterized. We have measured an excess loss of approximately 8 dB.

Alignment-free, all-spliced fiber laser source for CARS microscopy based on four-wave-mixing.

PubMed

Baumgartl, Martin; Gottschall, Thomas; Abreu-Afonso, Javier; Díez, Antonio; Meyer, Tobias; Dietzek, Benjamin; Rothhardt, Manfred; Popp, Jürgen; Limpert, Jens; Tünnermann, Andreas

2012-09-10

An environmentally-stable low-repetition rate fiber oscillator is developed to produce narrow-bandwidth pulses with several tens of picoseconds duration. Based on this oscillator an alignment-free all-fiber laser for multi-photon microscopy is realized using in-fiber frequency conversion based on four-wave-mixing. Both pump and Stokes pulses for coherent anti-Stokes Raman scattering (CARS) microscopy are readily available from one fiber end, intrinsically overlapped in space and time, which drastically simplifies the experimental handling for the user. The complete laser setup is mounted on a home-built laser scanning microscope with small footprint. High-quality multimodal microscope images of biological tissue are presented probing the CH-stretching resonance of lipids at an anti-Stokes Raman-shift of 2845 cm(-1) and second-harmonic generation of collagen. Due to its simplicity, compactness, maintenance-free operation, and ease-of-use the presented low-cost laser is an ideal source for bio-medical applications outside laser laboratories and in particular inside clinics.

Effect of Terminal Modification on the Molecular Assembly and Mechanical Properties of Protein-Based Block Copolymers.

PubMed

Jacobsen, Matthew M; Tokareva, Olena S; Ebrahimi, Davoud; Huang, Wenwen; Ling, Shengjie; Dinjaski, Nina; Li, David; Simon, Marc; Staii, Cristian; Buehler, Markus J; Kaplan, David L; Wong, Joyce Y

2017-09-01

Accurate prediction and validation of the assembly of bioinspired peptide sequences into fibers with defined mechanical characteristics would aid significantly in designing and creating materials with desired properties. This process may also be utilized to provide insight into how the molecular architecture of many natural protein fibers is assembled. In this work, computational modeling and experimentation are used in tandem to determine how peptide terminal modification affects a fiber-forming core domain. Modeling shows that increased terminal molecular weight and hydrophilicity improve peptide chain alignment under shearing conditions and promote consolidation of semicrystalline domains. Mechanical analysis shows acute improvements to strength and elasticity, but significantly reduced extensibility and overall toughness. These results highlight an important entropic function that terminal domains of fiber-forming peptides exhibit as chain alignment promoters, which ultimately has notable consequences on the mechanical behavior of the final fiber products. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fibered fluorescence microscopy (FFM) of intra epidermal nerve fibers--translational marker for peripheral neuropathies in preclinical research: processing and analysis of the data

NASA Astrophysics Data System (ADS)

Cornelissen, Frans; De Backer, Steve; Lemeire, Jan; Torfs, Berf; Nuydens, Rony; Meert, Theo; Schelkens, Peter; Scheunders, Paul

2008-08-01

Peripheral neuropathy can be caused by diabetes or AIDS or be a side-effect of chemotherapy. Fibered Fluorescence Microscopy (FFM) is a recently developed imaging modality using a fiber optic probe connected to a laser scanning unit. It allows for in-vivo scanning of small animal subjects by moving the probe along the tissue surface. In preclinical research, FFM enables non-invasive, longitudinal in vivo assessment of intra epidermal nerve fibre density in various models for peripheral neuropathies. By moving the probe, FFM allows visualization of larger surfaces, since, during the movement, images are continuously captured, allowing to acquire an area larger then the field of view of the probe. For analysis purposes, we need to obtain a single static image from the multiple overlapping frames. We introduce a mosaicing procedure for this kind of video sequence. Construction of mosaic images with sub-pixel alignment is indispensable and must be integrated into a global consistent image aligning. An additional motivation for the mosaicing is the use of overlapping redundant information to improve the signal to noise ratio of the acquisition, because the individual frames tend to have both high noise levels and intensity inhomogeneities. For longitudinal analysis, mosaics captured at different times must be aligned as well. For alignment, global correlation-based matching is compared with interest point matching. Use of algorithms working on multiple CPU's (parallel processor/cluster/grid) is imperative for use in a screening model.

Effect on Bone Architecture of Marginal Grooves in Dental Implants Under Occlusal Loaded Conditions in Beagle Dogs.

PubMed

Kato, Hatsumi; Kuroshima, Shinichiro; Inaba, Nao; Uto, Yusuke; Sawase, Takashi

2018-02-01

The aim of this study was to clarify whether marginal grooves on dental implants affect osseointegration, bone structure, and the alignment of collagen fibers to determine bone quality under loaded conditions. Anodized Ti-6Al-4V alloy dental implants, with and without marginal grooves (test and control implants, respectively), were used (3.7 × 8.0 mm). Fourth premolars and first molars of 6 beagle mandibles were extracted. Two control and test implants were placed in randomly selected healed sites at 12 weeks after tooth extraction. Screw-retained single crowns for first molars were fabricated. Euthanasia was performed at 8 weeks after the application of occlusal forces. Implant marginal bone level, bone to implant contact (BIC), bone structure around dental implants, and the alignment of collagen fibers determining bone quality were analyzed. The marginal bone level in test implants was significantly higher than that in control implants. Occlusal forces significantly increased BIC in test implants ( P = .007), whereas BIC did not change in control implants, irrespective of occlusal forces ( P = .303). Moreover, occlusal forces significantly increased BIC in test implants compared with control implants ( P = .032). Additionally, occlusal forces preferentially aligned collagen fibers in test implants, but not control implants. Hence, marginal grooves on dental implants have positive effects on increased osseointegration and adapted bone quality based on the preferential alignment of collagen fibers around dental implants under loaded conditions.

Microfluidic-enhanced 3D bioprinting of aligned myoblast-laden hydrogels leads to functionally organized myofibers in vitro and in vivo.

PubMed

Costantini, Marco; Testa, Stefano; Mozetic, Pamela; Barbetta, Andrea; Fuoco, Claudia; Fornetti, Ersilia; Tamiro, Francesco; Bernardini, Sergio; Jaroszewicz, Jakub; Święszkowski, Wojciech; Trombetta, Marcella; Castagnoli, Luisa; Seliktar, Dror; Garstecki, Piotr; Cesareni, Gianni; Cannata, Stefano; Rainer, Alberto; Gargioli, Cesare

2017-07-01

We present a new strategy for the fabrication of artificial skeletal muscle tissue with functional morphologies based on an innovative 3D bioprinting approach. The methodology is based on a microfluidic printing head coupled to a co-axial needle extruder for high-resolution 3D bioprinting of hydrogel fibers laden with muscle precursor cells (C2C12). To promote myogenic differentiation, we formulated a tailored bioink with a photocurable semi-synthetic biopolymer (PEG-Fibrinogen) encapsulating cells into 3D constructs composed of aligned hydrogel fibers. After 3-5 days of culture, the encapsulated myoblasts started migrating and fusing, forming multinucleated myotubes within the 3D bioprinted fibers. The obtained myotubes showed high degree of alignment along the direction of hydrogel fiber deposition, further revealing maturation, sarcomerogenesis, and functionality. Following subcutaneous implantation in the back of immunocompromised mice, bioprinted constructs generated organized artificial muscle tissue in vivo. Finally, we demonstrate that our microfluidic printing head allows to design three dimensional multi-cellular assemblies with an exquisite compartmentalization of the encapsulated cells. Our results demonstrate an enhanced myogenic differentiation with the formation of parallel aligned long-range myotubes. The approach that we report here represents a robust and valid candidate for the fabrication of macroscopic artificial muscle to scale up skeletal muscle tissue engineering for human clinical application. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Three-Dimensional Printed Thermal Regulation Textiles.

PubMed

Gao, Tingting; Yang, Zhi; Chen, Chaoji; Li, Yiju; Fu, Kun; Dai, Jiaqi; Hitz, Emily M; Xie, Hua; Liu, Boyang; Song, Jianwei; Yang, Bao; Hu, Liangbing

2017-11-28

Space cooling is a predominant part of energy consumption in people's daily life. Although cooling the whole building is an effective way to provide personal comfort in hot weather, it is energy-consuming and high-cost. Personal cooling technology, being able to provide personal thermal comfort by directing local heat to the thermally regulated environment, has been regarded as one of the most promising technologies for cooling energy and cost savings. Here, we demonstrate a personal thermal regulated textile using thermally conductive and highly aligned boron nitride (BN)/poly(vinyl alcohol) (PVA) composite (denoted as a-BN/PVA) fibers to improve the thermal transport properties of textiles for personal cooling. The a-BN/PVA composite fibers are fabricated through a fast and scalable three-dimensional (3D) printing method. Uniform dispersion and high alignment of BN nanosheets (BNNSs) can be achieved during the processing of fiber fabrication, leading to a combination of high mechanical strength (355 MPa) and favorable heat dispersion. Due to the improved thermal transport property imparted by the thermally conductive and highly aligned BNNSs, better cooling effect (55% improvement over the commercial cotton fiber) can be realized in the a-BN/PVA textile. The wearable a-BN/PVA textiles containing the 3D-printed a-BN/PVA fibers offer a promising selection for meeting the personal cooling requirement, which can significantly reduce the energy consumption and cost for cooling the whole building.

Processing and characterization of α-elastin electrospun membranes

NASA Astrophysics Data System (ADS)

Araujo, J.; Padrão, J.; Silva, J. P.; Dourado, F.; Correia, D. M.; Botelho, G.; Gomez Ribelles, J. L.; Lanceros-Méndez, S.; Sencadas, V.

2014-06-01

Elastin isolated from fresh bovine ligaments was dissolved in a mixture of 1,1,1,3,3,3-Hexafluoro-2-propanol and water were electrospun into fiber membranes under different processing conditions. Fiber mats of randomly and aligned fibers were obtained with fixed and rotating ground collectors and fibrils were composed by thin ribbons whose width depends on electrospinning conditions; fibrils with 721 nm up to 2.12 μm width were achieved. After cross-linking with glutaraldehyde, α-elastin can uptake as much as 1700 % of PBS solution and a slight increase on fiber thickness was observed. The glass transition temperature of electrospun fiber mats was found to occur at ˜80 °C. Moreover, α-Elastin showed to be a perfect elastomeric material, and no mechanical hysteresis was found in cycle mechanical measurements. The elastic modulus obtained for random and aligned fibers mats in a PBS solution was 330±10 kPa and 732±165 kPa, respectively. Finally, the electrospinning and cross-linking process does not inhibit MC-3T3-E1 cell adhesion. Cell culture results showed good cell adhesion and proliferation in the cross-linked elastin fiber mats.

Flow cytometry without alignment of collection optics.

PubMed

Sitton, Greg; Srienc, Friedrich

2009-12-01

This study describes the performance of a new waveguide flow cell constructed from Teflon AF (TFC) and the potential use of fiber optic splitters to replace collection objectives and dichroic mirrors. The TFC has the unique optical property that the refractive index of the polymer is lower than water and therefore, water filled TFC behaves and functions as a liquid core waveguide. Thus, as cells flow through the TFC and are illuminated by a laser orthogonal to the flow direction, scattered and fluorescent light is directed down the axis of the TFC to a fiber optic. The total signal in the fiber optic is then split into multiple fibers by fiber optic splitters to enable measurement of signal intensities at different wavelengths. Optical filters are placed at the terminus of each fiber before measurement of specific wavelengths by a PMT. The constructed system was used to measure DNA content of CHO and yeast cells. Polystyrene beads were used for alignment and to assess the performance of the system. Polystyrene beads were observed to produce light scattering signals with unique bimodal characteristics dependent on the direction of flow relative to the collecting fiber optic.

Connector For Embedded Optical Fiber

NASA Technical Reports Server (NTRS)

Wilkerson, Charles; Hiles, Steven; Houghton, J. Richard; Holland, Brent W.

1994-01-01

Partly embedded fixture is simpler and sturdier than other types of outlets for optical fibers embedded in solid structures. No need to align coupling prism and lenses. Fixture includes base, tube bent at 45 degree angle, and ceramic ferrule.

Microcracks induce osteoblast alignment and maturation on hydroxyapatite scaffolds

NASA Astrophysics Data System (ADS)

Shu, Yutian

Physiological bone tissue is a mineral/collagen composite with a hierarchical structure. The features in bone, such as mineral crystals, fibers, and pores can range from the nanometer to the centimeter in size. Currently available bone tissue scaffolds primarily address the chemical composition, pore size, and pore size distribution. While these design parameters are extensively investigated for mimicking bone function and inducing bone regeneration, little is known about microcracks, which is a prevalent feature found in fractured bone in vivo and associated with fracture healing and repair. Since the purpose of bone tissue engineering scaffold is to enhance bone regeneration, the coincidence of microcracks and bone densification should not be neglected but rather be considered as a potential parameter in bone tissue engineering scaffold design. The purpose of this study is to test the hypothesis that microcracks enhance bone healing. In vitro studies were designed to investigate the osteoblast (bone forming cells) response to microcracks in dense (94%) hydroxyapatite substrates. Microcracks were introduced using a well-established Vickers indentation technique. The results of our study showed that microcracks induced osteoblast alignment, enhanced osteoblast attachment and more rapid maturation. These findings may provide insight into fracture healing mechanism(s) as well as improve the design of bone tissue engineering orthopedic scaffolds for more rapid bone regeneration.

Engineered plant biomass particles coated with bioactive agents

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

Dooley, James H; Lanning, David N

Plant biomass particles coated with a bioactive agent such as a fertilizer or pesticide, characterized by a length dimension (L) aligned substantially parallel to a grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. In particular, the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.Wmore » dimensions define a pair of substantially parallel top and bottom surfaces.« less

Electrochromic fiber-shaped supercapacitors.

PubMed

Chen, Xuli; Lin, Huijuan; Deng, Jue; Zhang, Ye; Sun, Xuemei; Chen, Peining; Fang, Xin; Zhang, Zhitao; Guan, Guozhen; Peng, Huisheng

2014-12-23

An electrochromic fiber-shaped super-capacitor is developed by winding aligned carbon nanotube/polyaniline composite sheets on an elastic fiber. The fiber-shaped supercapacitors demonstrate rapid and reversible chromatic transitions under different working states, which can be directly observed by the naked eye. They are also stretchable and flexible, and are woven into textiles to display designed signals in addition to storing energy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrospun nanofibers: Formation, characterization, and evaluation for nerve tissue engineering applications

NASA Astrophysics Data System (ADS)

Zander, Nicole E.

The effects of fiber alignment and surface chemistry, including the covalent attachment and physical adsorption of the extracellular matrix (ECM) proteins laminin and collagen, on the neurite outgrowth of neuron-like PC12 cells were examined. Neuron-like PC12 cells responded to fiber orientation, and were successfully contact-guided by aligned electrospun nanofibers. In addition, fibers with attached protein, either physically adsorbed or covalently attached, improved neurite outgrowth lengths. Furthermore, aligning the fibers and attaching the ECM protein laminin, in particular, significantly improved neurite outgrowth over randomly oriented fibers with laminin. Since this research suggested that protein concentration on the fibers was the dominant driving force for improved neurite outgrowth, the effect of protein concentration, incorporated onto the surface of the nanofibers, on neurite outgrowth was examined. Two ways to control protein concentration on the fibers were explored—the variation of the fiber-protein reaction time and the variation of the protein soaking solution concentration. In addition, analytical methods to quantify the concentration of protein, as well as the protein coverage, on the surface of the fibers were developed. Although most of the fiber mats had multilayer protein coverage, and hence physically adsorbed proteins which could potentially mean a loss in bioactivity, the neuron-like PC12 cell neurites responded in a dose-dependent manner with increased neurite lengths on scaffolds with higher protein concentrations. The work was extended further by forming protein gradients on the fiber mats in hopes of locally directing neurite outgrowth and orientation. Fiber mats with both linear gradients (continuous change in protein concentration) and step gradients (six regions of uniform protein coverage, with protein concentration increasing from region to region) were fabricated and analyzed. The step gradients formed in the aligned fiber direction showed the most promise for use in cell culture assays. While surface chemistry and topography are important, porosity of the scaffold is also critical to control cellular infiltration and tissue formation. To enhance the porosity of our electrospun nanofiber scaffolds and improve the infiltration of cells, two methods were explored to control porosity. In the first method, the scaffold polymer polycaprolactone was co-electrospun with a sacrificial polymer polyethylene oxide, which was removed after the bi-component fiber mat was formed. In doing so, the void space was increased. In the second method, the spinning solution concentration of polycaprolactone was varied to control fiber diameter and porosity. The second method proved to be more effective at improving the cellular infiltration of PC12 cells. Two orders of magnitude range of fiber diameters were achieved, and nearly full infiltration of PC12 cells was observed for the mats with the highest porosity. The pore sizes of these mats were on the order of the size of the cell bodies (approximately 6-10 µm). Although the majority of this work focuses on using conventional electrospinning to generate solid-core fibers, core-shell fibers, have many applications in tissue engineering, among other fields. We explored an efficient way to generate these fibers from an emulsion solution using a conventional electrospinning apparatus. We characterized the fibers using an atomic force microscope (AFM) elastic modulus mapping technique, along with AFM phase imaging, angle-resolved x-ray photoelectron spectroscopy and thermal gravimetric analysis, to determine the chemical and molar composition of the core and shell layers. This work presents novel analytical techniques for the characterization of core-shell nanofibers in order to better predict and understand their material properties. (Abstract shortened by UMI.).

Structural Qualification of Composite Airframes

NASA Technical Reports Server (NTRS)

Kedward, Keith T.; McCarty, John E.

1997-01-01

The development of fundamental approaches for predicting failure and elongation characteristics of fibrous composites are summarized in this document. The research described includes a statistical formulation for individual fiber breakage and fragmentation and clustered fiber breakage, termed macrodefects wherein the aligned composite may represent a structural component such as a reinforcing bar element, a rebar. Experimental work conducted in support of the future exploitation of aligned composite rebar elements is also described. This work discusses the experimental challenges associated with rebar tensile test evaluation and describes initial numerical analyses performed in support of the experimental program.

Fabrication of a Highly Aligned Neural Scaffold via a Table Top Stereolithography 3D Printing and Electrospinning^.

PubMed

Lee, Se-Jun; Nowicki, Margaret; Harris, Brent; Zhang, Lijie Grace

2017-06-01

Three-dimensional (3D) bioprinting is a rapidly emerging technique in the field of tissue engineering to fabricate extremely intricate and complex biomimetic scaffolds in the range of micrometers. Such customized 3D printed constructs can be used for the regeneration of complex tissues such as cartilage, vessels, and nerves. However, the 3D printing techniques often offer limited control over the resolution and compromised mechanical properties due to short selection of printable inks. To address these limitations, we combined stereolithography and electrospinning techniques to fabricate a novel 3D biomimetic neural scaffold with a tunable porous structure and embedded aligned fibers. By employing two different types of biofabrication methods, we successfully utilized both synthetic and natural materials with varying chemical composition as bioink to enhance biocompatibilities and mechanical properties of the scaffold. The resulting microfibers composed of polycaprolactone (PCL) polymer and PCL mixed with gelatin were embedded in 3D printed hydrogel scaffold. Our results showed that 3D printed scaffolds with electrospun fibers significantly improve neural stem cell adhesion when compared to those without the fibers. Furthermore, 3D scaffolds embedded with aligned fibers showed an enhancement in cell proliferation relative to bare control scaffolds. More importantly, confocal microscopy images illustrated that the scaffold with PCL/gelatin fibers greatly increased the average neurite length and directed neurite extension of primary cortical neurons along the fiber. The results of this study demonstrate the potential to create unique 3D neural tissue constructs by combining 3D bioprinting and electrospinning techniques.

Mean Green operators of deformable fiber networks embedded in a compliant matrix and property estimates

NASA Astrophysics Data System (ADS)

Franciosi, Patrick; Spagnuolo, Mario; Salman, Oguz Umut

2018-04-01

Composites comprising included phases in a continuous matrix constitute a huge class of meta-materials, whose effective properties, whether they be mechanical, physical or coupled, can be selectively optimized by using appropriate phase arrangements and architectures. An important subclass is represented by "network-reinforced matrices," say those materials in which one or more of the embedded phases are co-continuous with the matrix in one or more directions. In this article, we present a method to study effective properties of simple such structures from which more complex ones can be accessible. Effective properties are shown, in the framework of linear elasticity, estimable by using the global mean Green operator for the entire embedded fiber network which is by definition through sample spanning. This network operator is obtained from one of infinite planar alignments of infinite fibers, which the network can be seen as an interpenetrated set of, with the fiber interactions being fully accounted for in the alignments. The mean operator of such alignments is given in exact closed form for isotropic elastic-like or dielectric-like matrices. We first exemplify how these operators relevantly provide, from classic homogenization frameworks, effective properties in the case of 1D fiber bundles embedded in an isotropic elastic-like medium. It is also shown that using infinite patterns with fully interacting elements over their whole influence range at any element concentration suppresses the dilute approximation limit of these frameworks. We finally present a construction method for a global operator of fiber networks described as interpenetrated such bundles.

Safely splicing glass optical fibers

NASA Technical Reports Server (NTRS)

Korbelak, K.

1980-01-01

Field-repair technique fuses glass fibers in flammable environment. Apparatus consists of v-groove vacuum chucks on manipulators, high-voltage dc power supply and tungsten electrodes, microscope to observe joint alignment and fusion, means of test transmission through joint. Apparatus is enclosed in gas tight bos filled with inert gas during fusion. About 2 feet of fiber end are necessary for splicing.

Innovative design of composite structures: The use of curvilinear fiber format in structural design of composites

NASA Technical Reports Server (NTRS)

Charette, R. F.; Hyer, M. W.

1990-01-01

The influence is investigated of a curvilinear fiber format on load carrying capacity of a layered fiber reinforced plate with a centrally located hole. A curvilinear fiber format is descriptive of layers in a laminate having fibers which are aligned with the principal stress directions in those layers. Laminates of five curvilinear fiber format designs and four straightline fiber format designs are considered. A quasi-isotropic laminate having a straightline fiber format is used to define a baseline design for comparison with the other laminate designs. Four different plate geometries are considered and differentiated by two values of hole diameter/plate width equal to 1/6 and 1/3, and two values of plate length/plate width equal to 2 and 1. With the plates under uniaxial tensile loading on two opposing edges, alignment of fibers in the curvilinear layers with the principal stress directions is determined analytically by an iteration procedure. In-plane tensile load capacity is computed for all of the laminate designs using a finite element analysis method. A maximum strain failure criterion and the Tsai-Wu failure criterion are applied to determine failure loads and failure modes. Resistance to buckling of the laminate designs to uniaxial compressive loading is analyzed using the commercial code Engineering Analysis Language. Results indicate that the curvilinear fiber format laminates have higher in-plane tensile load capacity and comparable buckling resistance relative to the straightline fiber format laminates.

DC Plasma Synthesis of Vertically Aligned Carbon Nanofibers for Biointerfacing

NASA Astrophysics Data System (ADS)

Pearce, Ryan Christopher

Vertically aligned carbon nanofibers (VACNFs) are a class of materials whose nanoscale dimensions and physical properties makes them uniquely suitable as functional elements in many applications for biodetection and biointerfacing on a cellular level. Control of VACNF synthesis by catalytic plasma enhanced chemical vapor deposition (PECVD) presents many challenges in integration into devices and structures designed for biointerfacing, such as transparent or flexible substrates. This dissertation addresses ways to overcome many of these issues in addition to deepening the fundamental understanding of nano-synthesis in catalytic PECVD. First, a survey of the field of VACNF synthesis and biointerfacing is presented, identifying the present challenges and greatest experimental applications. It is followed by experimental observations that elucidate the underlying mechanism to fiber alignment during synthesis, a critical step for deterministic control of fiber growth. Using a grid of electrodes patterned by photolithography on an insulating substrate, it was found that the alignment of the fibers is controlled by the anisotropic etching provided by ions during dc-PECVD synthesis. The VACNFs that have been utilized for many cellular interfacing experiments have unique mechanical and fluorescent properties due to a SiNx coating. The mechanism for SiNx deposition to VACNF sidewalls during synthesis is explored in addition to a detailed study of the optical properties of the coating. To explain the optical properties of this coating it is proposed that the source of photoluminescence for the SiNx coated VACNFs is quantum confinement effects due to the presence of silicon nanoclusters embedded in a Si3N4 matrix. These luminescent fibers have proven useful as registry markers in cell impalefection studies. To realize VACNF arrays used as an inflatable angioplasty balloon with embedded fibers to deliver drugs across the blood-brain barrier, a method for transferring fibers to flexible polydimethylesiloxane (PDMS) is presented. A process has been developed that involves synthesizing fibers on aluminum, followed by spin coating a thin layer of PDMS and then dissolving the underlying aluminum with KOH. Finally, a method of fiber synthesis using just air and acetone as the process gases is presented, enabling the possibility of inatmosphere, large scale VACNF synthesis. It is envisioned that these advancements should assist the viability of large scale VACNF related technologies and will help to bridge the gap between experimental applications and industrial adoption.

Design and prototyping of self-centering optical single-mode fiber alignment structures

NASA Astrophysics Data System (ADS)

Ebraert, Evert; Gao, Fei; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

2016-06-01

The European Commission’s goal of providing each European household with at least a 30 Mb s-1 Internet connection by 2020 would be facilitated by a widespread deployment of fibre-to-the-home, which would in turn be sped up by the development of connector essential components, such as high-precision alignment features. Currently, the performance of state-of-the-art physical contact optical fiber connectors is limited by the tolerance on the cladding of standard telecom-grade single-mode fiber (SMF), which is typically smaller than  ±1 μm. We propose to overcome this limit by developing micro-spring-based self-centering alignment structures (SCAS) for SMF-connectors. We design these alignment structures with robustness and low-cost replication in mind, allowing for large-scale deployment. Both theoretical and finite element analysis (FEA) models are used to determine the optimal dimensions of the beams of which the micro-springs of the SCAS are comprised. Two topologies of the SCAS, consisting of three and four micro-springs respectively, are investigated for two materials: polysulfone (PSU) and polyetherimide (PEI). These materials hold great potential for high-performance fiber connectors while being compatible with low-cost production and with the harsh environmental operation conditions of those connectors. The theory and FEA agree well (<3% difference) for a simple micro-spring. When including a pedestal on the micro-spring (to bring it further away from the fiber) and for shorter spring lengths the agreement worsens. This is due to spring compression effects not being taken into account in our theoretical model. Prototypes are successfully fabricated using deep proton writing and subsequently characterized. The controlled insertion of an SMF in the SCAS is investigated and we determine that a force of 0.11 N is required. The fiber insertion also causes an out-of-plane deformation of the micro-springs in the SCAS of about 7 μm, which is no problem for robustness according to the FEA model. Finally connector-assemblies are made with the alignment system and we show that an insertion loss down to 0.1 dB is achievable. The prototypes are subsequently used as a sacrificial master for mould fabrication through electroplating with the goal of low-cost replication through hot embossing.

Diabetes Alters Mechanical Properties and Collagen Fiber Re-Alignment in Multiple Mouse Tendons

PubMed Central

Connizzo, Brianne K.; Bhatt, Pankti R.; Liechty, Kenneth W.; Soslowsky, Louis J.

2014-01-01

Tendons function to transfer load from muscle to bone through their complex composition and hierarchical structure, consisting mainly of type I collagen. Recent evidence suggests that type II diabetes may cause alterations in collagen structure, such as irregular fibril morphology and density, which could play a role in the mechanical function of tendons. Using the db/db mouse model of type II diabetes, the diabetic skin was found to have impaired biomechanical properties when compared to the non-diabetic group. The purpose of this study was to assess the effect of diabetes on biomechanics, collagen fiber re-alignment, and biochemistry in three functionally different tendons (Achilles, supraspinatus, patellar) using the db/db mouse model. Results showed that cross-sectional area and stiffness, but not modulus, were significantly reduced in all three tendons. However, the tendon response to load (transition strain, collagen fiber re-alignment) occurred earlier in the mechanical test, contrary to expectations. In addition, the patellar tendon had an altered response to diabetes when compared to the other two tendons, with no changes in fiber realignment and decreased collagen content at the midsubstance of the tendon. Overall, type II diabetes alters tendon mechanical properties and the dynamic response to load. PMID:24833253

Stress-Strain Properties of SIFCON in Uniaxial Compression and Tension

DTIC Science & Technology

1988-08-01

direction act as contacting beams whereas fibers aligned parallel to the loading direction act as individual columns . The combination of fiber-to-fiber...applicable to the study of SIFCON. These include such topics as the influence of strain rate on composite behavior, cyclic loading response, fiber-to-matrix...the specimen are shown in Figure 17. The grips consisted of self-clamping steel plates and a universal joint connection to the loading machine which

A Cable-Shaped Lithium Sulfur Battery.

PubMed

Fang, Xin; Weng, Wei; Ren, Jing; Peng, Huisheng

2016-01-20

A carbon nanostructured hybrid fiber is developed by integrating mesoporous carbon and graphene oxide into aligned carbon nanotubes. This hybrid fiber is used as a 1D cathode to fabricate a new cable-shaped lithium-sulfur battery. The fiber cathode exhibits a decent specific capacity and lifespan, which makes the cable-shaped lithium-sulfur battery rank far ahead of other fiber-shaped batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Texture and anisotropy in the bismuth sodium titanate system

NASA Astrophysics Data System (ADS)

Fancher, Christoher M.

Bi0.5Na0.5TiO3 has received interest as a potential replacement for lead containing ferroelectrics. However, the piezoelectric response of pure Bi0.5Na0.5TiO 3 does not compare to the strong piezoelectric response of lead based piezoelectrics. To increase the piezoelectric response, Bi0.5Na 0.5TiO3 has been alloyed with BaTiO3 and K 0.5Na0.5NbO3. Another route to enhance the response is to take advantage of the anisotropic properties by inducing a preferred crystallographic orientation. Both routes were used to investigate the effect a crystallographic texture has on the strain response of Bi0.5Na 0.5TiO3-based ceramics. A crystallographic texture was induced by templated grain growth of pure phase Bi0.5Na0.5TiO3 templates using the tape casting method to orient template particles relative to the tape cast normal. Sintered Bi0.5Na0.5TiO3-based materials developed a strong (00l)pc fiber texture relative to the tape cast normal, with no preferential alignment relative to the tape cast plane. Textured Bi0.5Na0.5TiO3-(5)BaTiO3 showed a piezoelectric response of 245 pC/N, a better than 50% enhancement from the 150 pC/N response of randomly oriented samples. The Bi0.5Na0.5TiO3-(5)BaTiO3-(2)K 0.5Na0.5NbO3 (x,y) system has been shown to undergo electric-field-induced phase transformation from a pseudocubic to polar phase. For (7,2) a strong 8.7 multiples of a random distribution (MRD) crystallographic texture increased the macroscopic strain response by 50%. Applying the electric field perpendicular to the fiber texture axis reduces the macroscopic strain response of textured (7,2) by 17%. The affect field direction has on the electric-field-induced phase transformations of textured (7,2) was investigated using in situ electric field dependent diffraction. In situ diffraction data showed the high strain response of textured (7,2) can be attributed to a reversible pseudocubic to tetragonal transformation. The field-induced tetragonal phase nucleates preferentially with a strong c-axis alignment in the electric field direction, ferroelastic domain texture. In situ diffraction data suggests the origin of the reduction in strain associated with a field applied perpendicular to the fiber texture axis is the result of a shorter induced lattice spacing and lower domain texture.

The effect of enterohemorrhagic E. coli infection on the cell mechanics of host cells.

PubMed

Chen, Yin-Quan; Su, Pin-Tzu; Chen, Yu-Hsuan; Wei, Ming-Tzo; Huang, Chien-Hsiu; Osterday, Kathryn; del Álamo, Juan C; Syu, Wan-Jr; Chiou, Arthur

2014-01-01

Enterohaemorrhagic E. coli (EHEC) is a type of human pathogenic bacteria. The main virulence characteristics of EHEC include the formation of attaching and effacing lesions (A/E lesions) and the production of one or more Shiga-like toxins, which may induce human uremic complications. When EHEC infects host cells, it releases translocated intimin receptor (Tir) and effector proteins inside the host cells, inducing the rearrangement and accumulation of the F-actin cytoskeleton, a phenotype leading to the formation of pedestals in the apical cell surface, and the growth of stress fibers at the base of the cells. To examine the effect of EHEC infection on cell mechanics, we carried out a series of experiments to examine HeLa cells with and without EHEC infection to quantify the changes in (1) focal adhesion area, visualized by anti-vinculin staining; (2) the distribution and orientation of stress fibers; and (3) the intracellular viscoelasticity, via directional video particle tracking microrheology. Our results indicated that in EHEC-infected HeLa cells, the focal adhesion area increased and the actin stress fibers became thicker and more aligned. The cytoskeletal reorganization induced by EHEC infection mediated a dramatic increase in the cytoplasmic elastic shear modulus of the infected cells, and a transition in the viscoelastic behavior of the cells from viscous-like to elastic-like. These changes in mechanobiological characteristics might modulate the attachments between EHEC and the host cell to withstand exfoliation, and between the host cell and the extracellular matrix, and might also alter epithelial integrity.

Uniaxially aligned electrospun cellulose acetate nanofibers for thin layer chromatographic screening of hydroquinone and retinoic acid adulterated in cosmetics.

PubMed

Tidjarat, Siripran; Winotapun, Weerapath; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Rojanarata, Theerasak

2014-11-07

Uniaxially aligned cellulose acetate (CA) nanofibers were successfully fabricated by electrospinning and applied to use as stationary phase for thin layer chromatography. The control of alignment was achieved by using a drum collector rotating at a high speed of 6000 rpm. Spin time of 6h was used to produce the fiber thickness of about 10 μm which was adequate for good separation. Without any chemical modification after the electrospinning process, CA nanofibers could be readily devised for screening hydroquinone (HQ) and retinoic acid (RA) adulterated in cosmetics using the mobile phase consisting of 65:35:2.5 methanol/water/acetic acid. It was found that the separation run on the aligned nanofibers over a distance of 5 cm took less than 15 min which was two to three times faster than that on the non-aligned ones. On the aligned nanofibers, the masses of HQ and RA which could be visualized were 10 and 25 ng, respectively, which were two times lower than those on the non-aligned CA fibers and five times lower than those on conventional silica plates due to the appearance of darker and sharper of spots on the aligned nanofibers. Furthermore, the proposed method efficiently resolved HQ from RA and ingredients commonly found in cosmetic creams. Due to the satisfactory analytical performance, facile and inexpensive production process, uniaxially aligned electrospun CA nanofibers are promising alternative media for planar chromatography. Copyright © 2014 Elsevier B.V. All rights reserved.

Hot-embossing replication of self-centering optical fiber alignment structures prototyped by deep proton writing

NASA Astrophysics Data System (ADS)

Ebraert, Evert; Wissmann, Markus; Guttmann, Markus; Kolew, Alexander; Worgull, Matthias; Barié, Nicole; Schneider, Marc; Hofmann, Andreas; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

2016-07-01

This paper presents the hot-embossing replication of self-centering fiber alignment structures for high-precision, single-mode optical fiber connectors. To this end, a metal mold insert was fabricated by electroforming a polymer prototype patterned by means of deep proton writing (DPW). To achieve through-hole structures, we developed a postembossing process step to remove the residual layer inherently present in hot-embossed structures. The geometrical characteristics of the hot-embossed replicas are compared, before and after removal of the residual layer, with the DPW prototypes. Initial measurements on the optical performance of the replicas are performed. The successful replication of these components paves the way toward low-cost mass replication of DPW-fabricated prototypes in a variety of high-tech plastics.

Super-Strong, Super-Stiff Macrofibers with Aligned, Long Bacterial Cellulose Nanofibers.

PubMed

Wang, Sha; Jiang, Feng; Xu, Xu; Kuang, Yudi; Fu, Kun; Hitz, Emily; Hu, Liangbing

2017-09-01

With their impressive properties such as remarkable unit tensile strength, modulus, and resistance to heat, flame, and chemical agents that normally degrade conventional macrofibers, high-performance macrofibers are now widely used in various fields including aerospace, biomedical, civil engineering, construction, protective apparel, geotextile, and electronic areas. Those macrofibers with a diameter of tens to hundreds of micrometers are typically derived from polymers, gel spun fibers, modified carbon fibers, carbon-nanotube fibers, ceramic fibers, and synthetic vitreous fibers. Cellulose nanofibers are promising building blocks for future high-performance biomaterials and textiles due to their high ultimate strength and stiffness resulting from a highly ordered orientation along the fiber axis. For the first time, an effective fabrication method is successfully applied for high-performance macrofibers involving a wet-drawing and wet-twisting process of ultralong bacterial cellulose nanofibers. The resulting bacterial cellulose macrofibers yield record high tensile strength (826 MPa) and Young's modulus (65.7 GPa) owing to the large length and the alignment of nanofibers along fiber axis. When normalized by weight, the specific tensile strength of the macrofiber is as high as 598 MPa g -1 cm 3 , which is even substantially stronger than the novel lightweight steel (227 MPa g -1 cm 3 ). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gaussian Curvature Directs Stress Fiber Orientation and Cell Migration.

PubMed

Bade, Nathan D; Xu, Tina; Kamien, Randall D; Assoian, Richard K; Stebe, Kathleen J

2018-03-27

We show that substrates with nonzero Gaussian curvature influence the organization of stress fibers and direct the migration of cells. To study the role of Gaussian curvature, we developed a sphere-with-skirt surface in which a positive Gaussian curvature spherical cap is seamlessly surrounded by a negative Gaussian curvature draping skirt, both with principal radii similar to cell-length scales. We find significant reconfiguration of two subpopulations of stress fibers when fibroblasts are exposed to these curvatures. Apical stress fibers in cells on skirts align in the radial direction and avoid bending by forming chords across the concave gap, whereas basal stress fibers bend along the convex direction. Cell migration is also strongly influenced by the Gaussian curvature. Real-time imaging shows that cells migrating on skirts repolarize to establish a leading edge in the azimuthal direction. Thereafter, they migrate in that direction. This behavior is notably different from migration on planar surfaces, in which cells typically migrate in the same direction as the apical stress fiber orientation. Thus, this platform reveals that nonzero Gaussian curvature not only affects the positioning of cells and alignment of stress fiber subpopulations but also directs migration in a manner fundamentally distinct from that of migration on planar surfaces. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Strong Keratin-like Nanofibers Made of Globular Protein

NASA Astrophysics Data System (ADS)

Dror, Yael; Makarov, Vadim; Admon, Arie; Zussman, Eyal

2008-03-01

Protein fibers as elementary structural and functional elements in nature inspire the engineering of protein-based products for versatile bio-medical applications. We have recently used the electrospinning process to fabricate strong sub-micron fibers made solely of serum albumin (SA). This raises the challenges of turning a globular non-viscous protein solution into a polymer--like spinnable solution and producing keratin-like fibers enriched in inter S-S bridges. A stable spinning process was achieved by using SA solution in a rich trifluoroethanol-water mixture with β-mercaptoethanol. The breakage of the intra disulfide bridges, as identified by mass spectrometry, together with the denaturing alcohol, enabled a pronounced expansion of the protein. This in turn, affects the rheological properties of the solution. X-ray diffraction pattern of the fibers revealed equatorial orientation, indicating the alignment of structures along the fiber axis. The mechanical properties reached remarkable average values (Young's modulus of 1.6GPa, and max stress of 36MPa) as compared to other fibrous protein nanofibers. These significant results are attributed to both the alignment and inter disulfide bonds (cross linking) that were formed by spontaneous post-spinning oxidation.

Design of an Fiber-Coupled Laser Heterodyne Interferometer for the FLARE

NASA Astrophysics Data System (ADS)

Frank, Samuel; Yoo, Jongsoo; Ji, Hantao; Jara-Almonte, Jon

2016-10-01

The FLARE (Facility for Laboratory Reconnection Experiments), which is currently under construction at PPPL, requires a complete set of laboratory plasma diagnostics. The Langmuir probes that will be used in the device to gather local density data require a reliable interferometer system to serve as baseline for density measurement calibration. A fully fiber-coupled infrared laser heterodyne interferometer has been designed in order to serve as the primary line-integrated electron density diagnostic. Thanks to advances in the communications industry many fiber optic devices and phase detection methods have advanced significantly becoming increasingly reliable and inexpensive. Fully fiber coupling a plasma interferometer greatly simplifies alignment procedures needed since the only free space laser path needing alignment is through the plasma itself. Fiber-coupling also provides significant resistance to vibrational noise, a common problem in plasma interferometry systems. This device also uses a greatly simplified phase detection scheme in which chips, originally developed for the communications industry, capable of directly detecting the phase shift of a signal with high time resolution. The design and initial performance of the system will be discussed.

A highly flexible piezoelectret-fiber pressure sensor based on highly aligned P(VDF-TrFE) electrospun fibers

NASA Astrophysics Data System (ADS)

Ke, Jun-Yi; Chu, Hsin-Jung; Hsu, Yu-Hsiang; Lee, Chih-Kung

2017-04-01

P(VDF-TrFE) is a ferroelectric material having a strong piezoelectric effect, a good chemical stability, chemical resistance and biocompatibility. Therefore, it is suitable for the development of flexible pressure sensors in biological applications. Using electrospinning method and a drum collector, P(VDF-TrFE) nanofibers are aligned and formed an ultrathin film sheet with a thickness of 15 to 30 μm. A 140 °C annealing process and a corona discharge poling process are conducted to increase the performance of β phase piezoelectricity. Based on this technology, a highly flexible piezoelectret pressure sensor is developed for measuring muscle movement on the surface of human body. The orientation of electrospun P(VDFTrFE) fibers and poling direction are studied to enhance the sensitivity of the piezoelectret-fiber pressure sensor. Preliminary study shows that the sensitivity of piezoelectret-fiber pressure sensor can be 110.37 pC/Pa with a high signal to noise ratio. Sensor design, experimental studies, and biological application are detailed in this paper.

Mechanical alignment of particles for use in fabricating superconducting and permanent magnetic materials

DOEpatents

Nellis, William J.; Maple, M. Brian

1992-01-01

A method for mechanically aligning oriented superconducting or permanently magnetic materials for further processing into constructs. This pretreatment optimizes the final crystallographic orientation and, thus, properties in these constructs. Such materials as superconducting fibers, needles and platelets are utilized.

Truss beam having convex-curved rods, shear web panels, and self-aligning adapters

NASA Technical Reports Server (NTRS)

Fernandez, Ian M. (Inventor)

2013-01-01

A truss beam comprised of a plurality of joined convex-curved rods with self-aligning adapters (SAA) adhesively attached at each end of the truss beam is disclosed. Shear web panels are attached to adjacent pairs of rods, providing buckling resistance for the truss beam. The rods are disposed adjacent to each other, centered around a common longitudinal axis, and oriented so that adjacent rod ends converge to at least one virtual convergence point on the common longitudinal axis, with the rods' curvature designed to increase prevent buckling for the truss beam. Each SAA has longitudinal bores that provide self-aligning of the rods in the SAA, the self-aligning feature enabling creation of strong adhesive bonds between each SAA and the rods. In certain embodiments of the present invention, pultruded unidirectional carbon fiber rods are coupled with carbon fiber shear web panels and metal SAA(s), resulting in a lightweight, low-cost but strong truss beam that is highly resistant to buckling.

Surface Acoustic Waves Grant Superior Spatial Control of Cells Embedded in Hydrogel Fibers.

PubMed

Lata, James P; Guo, Feng; Guo, Jinshan; Huang, Po-Hsun; Yang, Jian; Huang, Tony Jun

2016-10-01

By exploiting surface acoustic waves and a coupling layer technique, cells are patterned within a photosensitive hydrogel fiber to mimic physiological cell arrangement in tissues. The aligned cell-polymer matrix is polymerized with short exposure to UV light and the fiber is extracted. These patterned cell fibers are manipulated into simple and complex architectures, demonstrating feasibility for tissue-engineering applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fatigue failure processes in aligned carbon-epoxy laminates

NASA Astrophysics Data System (ADS)

Piggott, Michael R.; Lam, Patrick W. K.

The failure mechanism involved in the tensile-tensile fatigue of carbon fiber-reinforced polymer matrices may be initiated by the fiber curvature that can be present in the composite. The varying stresses encountered in fatigue begin to damage the composite at the antinodes of the fiber profiles, perhaps in the form of fiber debonds that generate matrix cracks and result in comminution of the polymer; eventually, as the process proceeds, the flexural stresses in the fiber are sufficiently great to cause early fiber failure in wavy regions. The breaks are connected by splits in the polymer.

Fatigue damage development of various CFRP-laminates

NASA Technical Reports Server (NTRS)

Schulte, K.; Baron, CH.

1988-01-01

The chronic strength and fatigue behavior of a woven carbon-fiber reinforced laminate in a balanced eight-shaft satin weave style was compared to nonwoven laminates with an equivalent cross-ply layup. Half the fibers were arranged in the direction of the load and the other half perpendicular to it. Two types of nonwoven laminates consisting of continuous fibers and aligned discontinuous fibers, both produced from carbon fiber prepregs, were studied. The cross-ply laminate with continuous fiber showed the best characteristics with regard to both static strength and fatigue. The similarities and differences in damage mechanisms in the laminates are described.

Bacterial Polymertropism, the Response to Strain-Induced Alignment of Polymers

NASA Astrophysics Data System (ADS)

Lemon, David J.

In nature, bacteria often live in surface-associated communities known as biofilms. Biofilm-forming bacteria deposit a layer of polysaccharide on the surfaces they inhabit; hence, polysaccharide is their immediate environment on any surface. In this study, we examined how the physical characteristics of polysaccharide substrates influence the behavior of the biofilm-forming bacterium Myxococcus xanthus. M. xanthus colonies, and indeed those of the majority of biofilm-forming species tested, respond to the compression-induced deformation of polysaccharide substrates by preferentially spreading across the surface perpendicular to the axis of compression. This response is conserved across multiple distantly related phyla and is found in species with an array of distinct motility apparatuses.The birefringence and small angle X-ray scattering patterns of compressed polysaccharide substrates indicate that the directed surface movements of these bacteria consistently match the orientation of the long axes of aligned and tightly packed polysaccharide fibers in compressed substrates. Therefore, we refer to this behavior as polymertropism to denote that the directed movements are a response to the physical arrangement of the change in packing and alignment of the polymers in the substrate. In addition to altering the colony morphology we find the behavior of groups of cells, called flares, is also affected in several species resulting in increased flare speed, duration, and displacement on compressed gel substrates.We suggest that polymertropism, which requires a downward-facing motility apparatus in M. xanthus, may be responsible for the observed tendency of bacterial cells to follow trails of extruded and presumably aligned polysaccharides, which their neighbors secrete and deposit on the substrate as they move across it. Polymertropism may also play a role in the organization of bacteria in a biofilm, as the iterative process of polysaccharide trail deposition and following is proposed to yield aggregates of cells.

Holograms for laser diode: Single mode optical fiber coupling

NASA Technical Reports Server (NTRS)

Fuhr, P. L.

1982-01-01

The low coupling efficiency of semiconductor laser emissions into a single mode optical fibers place a severe restriction on their use. Associated with these conventional optical coupling techniques are stringent alignment sensitivities. Using holographic elements, the coupling efficiency may be increased and the alignment sensitivity greatly reduced. Both conventional and computer methods used in the generation of the holographic couplers are described and diagrammed. The reconstruction geometries used are shown to be somewhat restrictive but substantially less rigid than their conventional optical counterparts. Single and double hologram techniques are examined concerning their respective ease of fabrication and relative merits.

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.

Quantitative regulation of bone-mimetic, oriented collagen/apatite matrix structure depends on the degree of osteoblast alignment on oriented collagen substrates.

PubMed

Matsugaki, Aira; Isobe, Yoshihiro; Saku, Taro; Nakano, Takayoshi

2015-02-01

Bone tissue has a specific anisotropic morphology derived from collagen fiber alignment and the related apatite crystal orientation as a bone quality index. However, the precise mechanism of cellular regulation of the crystallographic orientation of apatite has not been clarified. In this study, anisotropic construction of cell-produced mineralized matrix in vitro was established by initiating organized cellular alignment and subsequent oriented bone-like matrix (collagen/apatite) production. The oriented collagen substrates with three anisotropic levels were prepared by a hydrodynamic method. Primary osteoblasts were cultured on the fabricated substrates until mineralized matrix formation is confirmed. Osteoblast alignment was successfully regulated by the level of substrate collagen orientation, with preferential alignment along the direction of the collagen fibers. Notably, both fibrous orientation of newly synthesized collagen matrix and c-axis of produced apatite crystals showed preferential orientation along the cell direction. Because the degree of anisotropy of the deposited apatite crystals showed dependency on the directional distribution of osteoblasts cultured on the oriented collagen substrates, the cell orientation determines the crystallographic anisotropy of produced apatite crystals. To the best of our knowledge, this is the first report demonstrating that bone tissue anisotropy, even the alignment of apatite crystals, is controllable by varying the degree of osteoblast alignment via regulating the level of substrate orientation. © 2014 Wiley Periodicals, Inc.

Poly(hydroxybutyrate)/chitosan Aligned Electrospun Scaffold as a Novel Substrate for Nerve Tissue Engineering.

PubMed

Karimi, Afarin; Karbasi, Saeed; Razavi, Shahnaz; Zargar, Elham Naghash

2018-01-01

Reconstruction of nervous system is a great challenge in the therapeutic medical field. Nerve tissue engineering is a novel method to regenerate nervous system in human health care. Tissue engineering has introduced novel approaches to promote and guide peripheral nerve regeneration using submicron and nanoscale fibrous scaffolds. In this study, 9 wt% poly(3-hydroxybutyrate) (PHB) solutions with two different ratios of chitosan (CTS) (15%, and 20%) were mixed in trifluoroacetic acid as a cosolvent. Thereafter, random and aligned PHB/CTS scaffolds were fabricated by electrospinning method in an appropriate condition. Average diameters for aligned PHB, PHB/CTS 85:15 and PHB/CTS 80:20 were obtained as 675 nm, 740.3 nm, and 870.74 nm, which was lesser than random fibers. The solution components entity authenticity was approved by Fourier transform infrared. The addition of CTS decreased both water droplet contact angle from 124.79° to 43.14° in random and 110.87° to 33.49° in aligned PHB/CTS fibrous scaffold. Moreover, alignment of fibers causes tremendous increase in hydrophilicity of fibrous PHB/CTS substrate. Tensile strength increased from 6.41 MPa for random to 8.73 MPa for aligned PHB/CTS 85:15. Our results indicated that aligned PHB/CTS 85:15 nanofibers are the desired scaffold than the random PHB/CTS nanofibers for application in nerve tissue regeneration.

Molecular orientation in aligned electrospun polyimide nanofibers by polarized FT-IR spectroscopy.

PubMed

Yang, Haoqi; Jiang, Shaohua; Fang, Hong; Hu, Xiaowu; Duan, Gaigai; Hou, Haoqing

2018-07-05

Quantitative explanation on the improved mechanical properties of aligned electrospun polyimide (PI) nanofibers as the increased imidization temperatures is highly required. In this work, polarized FT-IR spectroscopy is applied to solve this problem. Based on the polarized FT-IR spectroscopy and the molecular model in the fibers, the length of the repeat unit of PI molecule, the angle between the fiber axis and the symmetric stretching direction of carbonyl group on the imide ring, and the angle between the PI molecular axis and fiber axis are all investigated. The Mark-Howink equation is used to calculate the number-average molar mass of PI molecules. The orientation states of PI molecules in the electrospun nanofibers are studied from the number-average molar mass of PI molecules and the average fiber diameter. Quantitative analysis of the orientation factor of PI molecules in the electrospun nanofibers is performed by polarized FT-IR spectroscopy. Copyright © 2018 Elsevier B.V. All rights reserved.

The James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Nowak, Maria; Eichorn, William; Hill, Michael; Hylan, Jason; Marsh, James; Ohl, Raymond; Sampler, Henry; Wright, Geraldine; Crane, Allen; Herrera, Acey;

Novel electric double-layer capacitor with a coaxial fiber structure.

PubMed

Chen, Xuli; Qiu, Longbin; Ren, Jing; Guan, Guozhen; Lin, Huijuan; Zhang, Zhitao; Chen, Peining; Wang, Yonggang; Peng, Huisheng

2013-11-26

A coaxial electric double-layer capacitor fiber is developed from the aligned carbon nanotube fiber and sheet, which functions as two electrodes with a polymer gel sandwiched between them. The unique coaxial structure enables a rapid transportation of ions between the two electrodes with a high electrochemical performance. These energy storage fibers are also flexible and stretchable, and can be woven into and widely used for electronic textiles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of a biomimetic poly-(lactic acid) ligament scaffold

NASA Astrophysics Data System (ADS)

Uehlin, Andrew F.

The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was used to create nanofibers of PLA, followed by an induced degradation of the nanofibers via 0.25M NaOH hydrolysis. The effects of the unidirectional electrospinning as well as the effects of NaOH hydrolysis on fiber alignment, fiber diameter, surface morphology, crystallinity, in vitro swelling, immobilization of fibrin, and mechanical properties were investigated, resulting in a modified morphology correlating to the microstructure of native ligament tissue with similar mechanical properties. Furthering the development of the PLA nanomatrix composite, a bioinkjet printer was used to immobilize nanoparticulate hydroxyapatite (HANP) on the surface of the scaffold. A series of 300pL droplets of HANP bioink were printed over a gradient pattern mimetic of (and spatially corresponding to) the mineralization gradient found over the microanatomy at the ACL enthesis. Proliferation and differentiation response of human mesenchymal stem cells (hMSCs) in vitro was assessed on a variety of conditions and combinations of the PLA nanofiber scaffold surface modifications (inclusive and exclusive of HANP, fibrin, and various time dependent NaOH treatments). It was found that a combinatory effect of the HANP gradient with fibrin on 20 minute NaOH treated PLA nanofibers enhanced the osteogenic differentiation of hMSCs, with an observable morphological change spatially corresponding to the compositional changes of the printed HANP gradient. Using the bioactive scaffold designed in this study as a template and expanding on the methods utilized, future studies can incorporate specific growth factors and other organic/inorganic biomolecules to further develop the engineered PLA nanomatrix into a functional ligament-replacement graft.

High-power fused assemblies enabled by advances in fiber-processing technologies

NASA Astrophysics Data System (ADS)

Wiley, Robert; Clark, Brett

2011-02-01

The power handling capabilities of fiber lasers are limited by the technologies available to fabricate and assemble the key optical system components. Previous tools for the assembly, tapering, and fusion of fiber laser elements have had drawbacks with regard to temperature range, alignment capability, assembly flexibility and surface contamination. To provide expanded capabilities for fiber laser assembly, a wide-area electrical plasma heat source was used in conjunction with an optimized image analysis method and a flexible alignment system, integrated according to mechatronic principles. High-resolution imaging and vision-based measurement provided feedback to adjust assembly, fusion, and tapering process parameters. The system was used to perform assembly steps including dissimilar-fiber splicing, tapering, bundling, capillary bundling, and fusion of fibers to bulk optic devices up to several mm in diameter. A wide range of fiber types and diameters were tested, including extremely large diameters and photonic crystal fibers. The assemblies were evaluated for conformation to optical and mechanical design criteria, such as taper geometry and splice loss. The completed assemblies met the performance targets and exhibited reduced surface contamination compared to assemblies prepared on previously existing equipment. The imaging system and image analysis algorithms provided in situ fiber geometry measurement data that agreed well with external measurement. The ability to adjust operating parameters dynamically based on imaging was shown to provide substantial performance benefits, particularly in the tapering of fibers and bundles. The integrated design approach was shown to provide sufficient flexibility to perform all required operations with a minimum of reconfiguration.

The fiber optic system for the advanced topographic laser altimeter system instrument (ATLAS)

NASA Astrophysics Data System (ADS)

Ott, Melanie N.; Thomes, W. Joe; Onuma, Eleanya; Switzer, Robert; Chuska, Richard; Blair, Diana; Frese, Erich; Matyseck, Marc

2016-09-01

The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite - 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the "cryosphere" (as well as terrain) to provide data for assessing the earth's global climate changes. Where ICESat's instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm.[1] The ATLAS pulsed transmission system consists of two lasers operating at 532 nm with transmitter optics for beam steering, a diffractive optical element that splits the signal into 6 separate beams, receivers for start pulse detection and a wavelength tracking system. The optical receiver telescope system consists of optics that focus all six beams into optical fibers that feed a filter system that transmits the signal via fiber assemblies to the detectors. Also included on the instrument is a system that calibrates the alignment of the transmitted pulses to the receiver optics for precise signal capture. The larger electro optical subsystems for transmission, calibration, and signal receive, stay aligned and transmitting sufficiently due to the optical fiber system that links them together. The robust design of the fiber optic system, consisting of a variety of multi fiber arrays and simplex assemblies with multiple fiber core sizes and types, will enable the system to maintain consistent critical alignments for the entire life of the mission. Some of the development approaches used to meet the challenging optical system requirements for ATLAS are discussed here.

The fiber optic system for the Advanced Topographic Laser Altimeter System (ATLAS) instrument

PubMed Central

Ott, Melanie N.; Thomes, Joe; Onuma, Eleanya; Switzer, Robert; Chuska, Richard; Blair, Diana; Frese, Erich; Matyseck, Marc

2017-01-01

The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite – 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the “cryosphere” (as well as terrain) to provide data for assessing the earth’s global climate changes. Where ICESat’s instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm.[1] The ATLAS pulsed transmission system consists of two lasers operating at 532 nm with transmitter optics for beam steering, a diffractive optical element that splits the signal into 6 separate beams, receivers for start pulse detection and a wavelength tracking system. The optical receiver telescope system consists of optics that focus all six beams into optical fibers that feed a filter system that transmits the signal via fiber assemblies to the detectors. Also included on the instrument is a system that calibrates the alignment of the transmitted pulses to the receiver optics for precise signal capture. The larger electro optical subsystems for transmission, calibration, and signal receive, stay aligned and transmitting sufficiently due to the optical fiber system that links them together. The robust design of the fiber optic system, consisting of a variety of multi fiber arrays and simplex assemblies with multiple fiber core sizes and types, will enable the system to maintain consistent critical alignments for the entire life of the mission. Some of the development approaches used to meet the challenging optical system requirements for ATLAS are discussed here. PMID:28280284

The fiber optic system for the Advanced Topographic Laser Altimeter System (ATLAS) instrument.

PubMed

Ott, Melanie N; Thomes, Joe; Onuma, Eleanya; Switzer, Robert; Chuska, Richard; Blair, Diana; Frese, Erich; Matyseck, Marc

2016-08-28

The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite - 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the "cryosphere" (as well as terrain) to provide data for assessing the earth's global climate changes. Where ICESat's instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm.[1] The ATLAS pulsed transmission system consists of two lasers operating at 532 nm with transmitter optics for beam steering, a diffractive optical element that splits the signal into 6 separate beams, receivers for start pulse detection and a wavelength tracking system. The optical receiver telescope system consists of optics that focus all six beams into optical fibers that feed a filter system that transmits the signal via fiber assemblies to the detectors. Also included on the instrument is a system that calibrates the alignment of the transmitted pulses to the receiver optics for precise signal capture. The larger electro optical subsystems for transmission, calibration, and signal receive, stay aligned and transmitting sufficiently due to the optical fiber system that links them together. The robust design of the fiber optic system, consisting of a variety of multi fiber arrays and simplex assemblies with multiple fiber core sizes and types, will enable the system to maintain consistent critical alignments for the entire life of the mission. Some of the development approaches used to meet the challenging optical system requirements for ATLAS are discussed here.

The Fiber Optic System for the Advanced Topographic Laser Altimeter System (ATLAS) Instrument

NASA Technical Reports Server (NTRS)

Ott, Melanie N.; Thomes, Joe; Onuma, Eleanya; Switzer, Robert; Chuska, Richard; Blair, Diana; Frese, Erich; Matyseck, Marc

2016-01-01

The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite - 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the "cryosphere" (as well as terrain) to provide data for assessing the earth's global climate changes. Where ICESat's instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm. The ATLAS pulsed transmission system consists of two lasers operating at 532 nm with transmitter optics for beam steering, a diffractive optical element that splits the signal into 6 separate beams, receivers for start pulse detection and a wavelength tracking system. The optical receiver telescope system consists of optics that focus all six beams into optical fibers that feed a filter system that transmits the signal via fiber assemblies to the detectors. Also included on the instrument is a system that calibrates the alignment of the transmitted pulses to the receiver optics for precise signal capture. The larger electro optical subsystems for transmission, calibration, and signal receive, stay aligned and transmitting sufficiently due to the optical fiber system that links them together. The robust design of the fiber optic system, consisting of a variety of multi fiber arrays and simplex assemblies with multiple fiber core sizes and types, will enable the system to maintain consistent critical alignments for the entire life of the mission. Some of the development approaches used to meet the challenging optical system requirements for ATLAS are discussed here.

Fiber Angle and Aspect Ratio Influence the Shear Mechanics of Oriented Electrospun Nanofibrous Scaffolds

PubMed Central

Driscoll, Tristan P.; Nerurkar, Nandan L.; Jacobs, Nathan T.; Elliott, Dawn M.; Mauck, Robert L.

2011-01-01

Fibrocartilages, including the knee meniscus and the annulus fibrosus (AF) of the intervertebral disc, play critical mechanical roles in load transmission across joints and their function is dependent upon well-defined structural hierarchies, organization, and composition. All, however, are compromised in the pathologic transformations associated with tissue degeneration. Tissue engineering strategies that address these key features, for example, aligned nanofibrous scaffolds seeded with mesenchymal stem cells (MSCs), represent a promising approach for the regeneration of these fibrous structures. While such engineered constructs can replicate native tissue structure and uniaxial tensile properties, the multidirectional loading encountered by these tissues in vivo necessitates that they function adequately in other loading modalities as well, including shear. As previous findings have shown that native tissue tensile and shear properties are dependent on fiber angle and sample aspect ratio, respectively, the objective of the present study was to evaluate the effects of a changing fiber angle and sample aspect ratio on the shear properties of aligned electrospun poly(ε-caprolactone) (PCL) scaffolds, and to determine how extracellular matrix deposition by resident MSCs modulates the measured shear response. Results show that fiber orientation and sample aspect ratio significantly influence the response of scaffolds in shear, and that measured shear strains can be predicted by finite element models. Furthermore, acellular PCL scaffolds possessed a relatively high shear modulus, 2–4 fold greater than native tissue, independent of fiber angle and aspect ratio. It was further noted that under testing conditions that engendered significant fiber stretch, the aggregate resistance to shear was higher, indicating a role for fiber stretch in the overall shear response. Finally, with time in culture, the shear modulus of MSC laden constructs increased, suggesting that deposited ECM contributes to the construct shear properties. Collectively, these findings show that aligned electrospun PCL scaffolds are a promising tool for engineering fibrocartilage tissues, and that the shear properties of both acellular and cell-seeded formulations can match or exceed native tissue benchmarks. PMID:22098865

Diamond Shaped Ring Laser Characterization, Package Design and Performance

DTIC Science & Technology

2006-09-01

fabricated by Binoptics, with the end facets formed by chemically assisted ion beam etching . The lasers, designed for operation at 1550 nm, propagated bi...calculated and Corning OptiFocus™ Lensed fiber was chosen to use for the four fiber outputs. Each fiber placement was actively optimized. Output power...aligned using active feedback and placed with submicron precision. The prototype package design was constrained to modification of a prior

A Fiber-Optic Coupled Telescope for Water Vapor DIAL Receivers

NASA Technical Reports Server (NTRS)

DeYoung, Russell J.; Lonn, Frederick

1998-01-01

A fiber-optic coupled telescope of low complexity was constructed and tested. The major loss mechanisms of the optical system have been characterized. Light collected by the receiver mirror is focused onto an optical fiber, and the output of the fiber is filtered by an interference filter and then focused onto an APD detector. This system was used in lidar field measurements with a 532-nm Nd:YAG laser beam. The results were encouraging. A numerical model used for calculation of the expected return signal agreed with the lidar return signal obtained. The assembled system was easy to align and operate and weighed about 8 kg for a 30 cm (12") mirror system. This weight is low enough to allow mounting of the fiber-optic telescope receiver system in a UAV. Furthermore, the good agreement between the numerical lidar model and the performance of the actual receiver system, suggests that this model may be used for estimation of the performance of this and other lidar systems in the future. Such telescopes are relatively easy to construct and align. The fiber optic cable allows easy placement of the optical detector in any position. These telescope systems should find widespread use in aircraft and space home DIAL water vapor receiver systems.

Similar hyaline-like cartilage repair of osteochondral defects in rabbits using isotropic and anisotropic collagen scaffolds.

PubMed

de Mulder, Eric L W; Hannink, Gerjon; van Kuppevelt, Toin H; Daamen, Willeke F; Buma, Pieter

2014-02-01

Lesions in knee joint articular cartilage (AC) have limited repair capacity. Many clinically available treatments induce a fibrous-like cartilage repair instead of hyaline cartilage. To induce hyaline cartilage repair, we hypothesized that type I collagen scaffolds with fibers aligned perpendicular to the AC surface would result in qualitatively better tissue repair due to a guided cellular influx from the subchondral bone. By specific freezing protocols, type I collagen scaffolds with isotropic and anisotropic fiber architectures were produced. Rabbits were operated on bilaterally and two full thickness defects were created in each knee joint. The defects were filled with (1) an isotropic scaffold, (2) an anisotropic scaffold with pores parallel to the cartilage surface, and (3) an anisotropic scaffold with pores perpendicular to the cartilage surface. Empty defects served as controls. After 4 (n=13) and 12 (n=13) weeks, regeneration was scored qualitatively and quantitatively using histological analysis and a modified O'Driscoll score. After 4 weeks, all defects were completely filled with partially differentiated hyaline cartilage tissue. No differences in O'Driscoll scores were measured between empty defects and scaffold types. After 12 weeks, all treatments led to hyaline cartilage repair visualized by increased glycosaminoglycan staining. Total scores were significantly increased for parallel anisotropic and empty defects over time (p<0.05). The results indicate that collagen scaffolds allow the formation of hyaline-like cartilage repair. Fiber architecture had no effect on cartilage repair.

Effects of stress fiber contractility on uniaxial stretch guiding mitosis orientation and stress fiber alignment.

PubMed

Zhao, Lei; Sang, Chen; Yang, Chun; Zhuang, Fengyuan

2011-09-02

It has been documented that mitosis orientation (MO) is guided by stress fibers (SFs), which are perpendicular to exogenous cyclic uniaxial stretch. However, the effect of mechanical forces on MO and the mechanism of stretch-induced SFs reorientation are not well elucidated to date. In the present study, we used murine 3T3 fibroblasts as a model, to investigate the effects of uniaxial stretch on SFO and MO utilizing custom-made stretch device. We found that cyclic uniaxial stretch induced both SFs and mitosis directions orienting perpendicularly to the stretch direction. The F-actin and myosin II blockages, which resulted in disoriented SFs and mitosis directions under uniaxial stretch, suggested a high correlation between SFO and MO. Y27632 (10 μM), ML7 (50 μM, or 75 μM), and blebbistatin (50 μM, or 75 μM) treatments resulted in SFO parallel to the principle stretch direction. Upon stimulating and inhibiting the phosphorylation of myosin light chain (p-MLC), we observed a monotonic proportion of SFO to the level of p-MLC. These results suggested that the level of cell contraction is crucial to the response of SFs, either perpendicular or parallel, to the external stretch. Showing the possible role of cell contractility in tuning SFO under external stretch, our experimental data are valuable to understand the predominant factor controlling SFO response to exogenous uniaxial stretch, and thus helpful for improving mechanical models. Copyright © 2011 Elsevier Ltd. All rights reserved.

Fiber optic spectroscopic digital imaging sensor and method for flame properties monitoring

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

Zelepouga, Serguei A; Rue, David M; Saveliev, Alexei V

2011-03-15

A system for real-time monitoring of flame properties in combustors and gasifiers which includes an imaging fiber optic bundle having a light receiving end and a light output end and a spectroscopic imaging system operably connected with the light output end of the imaging fiber optic bundle. Focusing of the light received by the light receiving end of the imaging fiber optic bundle by a wall disposed between the light receiving end of the fiber optic bundle and a light source, which wall forms a pinhole opening aligned with the light receiving end.

Method and system for aligning fibers during electrospinning

NASA Technical Reports Server (NTRS)

Scott-Carnell, Lisa A. (Inventor); Stephens, Ralph M (Inventor); Holloway, Nancy M. (Inventor); Rhim, Caroline (Inventor); Niklason, Laura (Inventor); Clark, Robert L. (Inventor); Siochi, Emilie J. (Inventor)

2011-01-01

A method and system are provided for aligning fibers in an electrospinning process. A jet of a fiberizable material is directed towards an uncharged collector from a dispensing location that is spaced apart from the collector. While the fiberizable material is directed towards the collector, an elliptical electric field is generated via the electrically charged dispenser and an oppositely-charged control location. The field spans between the dispensing location and the control location that is within line-of-sight of the dispensing location, and impinges upon at least a portion of the collector. Various combinations of numbers and geometries of dispensers, collectors, and electrodes can be used.

Evolution of Texture from a Single Crystal Ti-6Al-4V Substrate During Electron Beam Directed Energy Deposition

NASA Astrophysics Data System (ADS)

Butler, Todd M.; Brice, Craig A.; Tayon, Wesley A.; Semiatin, S. Lee; Pilchak, Adam L.

2017-10-01

Additive manufacturing of Ti-6Al-4V commonly produces 〈001〉 β -fiber textures aligned with the build direction. We have performed wire-feed electron beam directed energy deposition on the {112} β plane of a single prior β-grain. The build initially grew epitaxially from the substrate with the preferred 〈001〉 growth direction significantly angled away from the build direction. However, continued layer deposition drove the formation of a 〈001〉 β -fiber texture aligned with the build direction and the direction of the strongest thermal gradient.

Effects of Schwann cell alignment along the oriented electrospun chitosan nanofibers on nerve regeneration.

PubMed

Wang, Wei; Itoh, Soichiro; Konno, Katsumi; Kikkawa, Takeshi; Ichinose, Shizuko; Sakai, Katsuyoshi; Ohkuma, Tsuneo; Watabe, Kazuhiko

2009-12-15

We have constructed a chitosan nonwoven nanofiber mesh tube consisting of oriented fibers by the electrospinning method. The efficacy of oriented nanofibers on Schwann cell alignment and positive effect of this tube on peripheral nerve regeneration were confirmed. The physical properties of the chitosan nanofiber mesh sheets prepared by electrospinning with or without fiber orientation were characterized. Then, immortalized Schwann cells were cultured on these sheets. Furthermore, the chitosan nanofiber mesh tubes with or without orientation, and bilayered chitosan mesh tube with an inner layer of oriented nanofibers and an outer layer of randomized nanofibers were bridgegrafted into rat sciatic nerve defect. As a result of fiber orientation, the tensile strength along the axis of the sheet increased. Because Schwann cells aligned along the nanofibers, oriented fibrous sheets could exhibit a Schwann cell column. Functional recovery and electrophysiological recovery occurred in time in the oriented group as well as in the bilayered group, and approximately matched those in the isograft. Furthermore, histological analysis revealed that the sprouting of myelinated axons occurred vigorously followed by axonal maturation in the isograft, oriented, and bilayered group in the order. The oriented chitosan nanofiber mesh tube may be a promising substitute for autogenous nerve graft.

4 channel × 10 Gb/s bidirectional optical subassembly using silicon optical bench with precise passive optical alignment.

PubMed

Kang, Eun Kyu; Lee, Yong Woo; Ravindran, Sooraj; Lee, Jun Ki; Choi, Hee Ju; Ju, Gun Wu; Min, Jung Wook; Song, Young Min; Sohn, Ik-Bu; Lee, Yong Tak

2016-05-16

We demonstrate an advanced structure for optical interconnect consisting of 4 channel × 10 Gb/s bidirectional optical subassembly (BOSA) formed using silicon optical bench (SiOB) with tapered fiber guiding holes (TFGHs) for precise and passive optical alignment of vertical-cavity surface-emitting laser (VCSEL)-to-multi mode fiber (MMF) and MMF-to-photodiode (PD). The co-planar waveguide (CPW) transmission line (Tline) was formed on the backside of silicon substrate to reduce the insertion loss of electrical data signal. The 4 channel VCSEL and PD array are attached at the end of CPW Tline using a flip-chip bonder and solder pad. The 12-channel ribbon fiber is simply inserted into the TFGHs of SiOB and is passively aligned to the VCSEL and PD in which no additional coupling optics are required. The fabricated BOSA shows high coupling efficiency and good performance with the clearly open eye patterns and a very low bit error rate of less than 10^-12 order at a data rate of 10 Gb/s with a PRBS pattern of 2³¹-1.

Characterization of Polyester Matrix Reinforced with Banana Fibers Thermal Properties by Photoacoustic Technique

NASA Astrophysics Data System (ADS)

de Assis, Foluke S.; Netto, Pedro A.; Margem, Frederico M.; Monteiro, Artur R. P. Junior Sergio N.

Synthetic fibers are being replaced gradually by natural materials such as lignocellulosic fibers. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as environmental and economic. So there is a growing international interest in the use of those fibers. The banana fiber presents significant properties to be studied, but until now few thermal properties on banana fiber as reinforcement of polyester matrix were performed. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity for polyester composites reinforced with banana fibers. In the polyester matrix will be added up to 30% in volume of continuous and aligned banana fibers. These values show that the incorporation of banana fibers in the polyester matrix changes its thermal properties.

Protein fiber linear dichroism for structure determination and kinetics in a low-volume, low-wavelength couette flow cell.

PubMed

Dafforn, Timothy R; Rajendra, Jacindra; Halsall, David J; Serpell, Louise C; Rodger, Alison

2004-01-01

High-resolution structure determination of soluble globular proteins relies heavily on x-ray crystallography techniques. Such an approach is often ineffective for investigations into the structure of fibrous proteins as these proteins generally do not crystallize. Thus investigations into fibrous protein structure have relied on less direct methods such as x-ray fiber diffraction and circular dichroism. Ultraviolet linear dichroism has the potential to provide additional information on the structure of such biomolecular systems. However, existing systems are not optimized for the requirements of fibrous proteins. We have designed and built a low-volume (200 microL), low-wavelength (down to 180 nm), low-pathlength (100 microm), high-alignment flow-alignment system (couette) to perform ultraviolet linear dichroism studies on the fibers formed by a range of biomolecules. The apparatus has been tested using a number of proteins for which longer wavelength linear dichroism spectra had already been measured. The new couette cell has also been used to obtain data on two medically important protein fibers, the all-beta-sheet amyloid fibers of the Alzheimer's derived protein Abeta and the long-chain assemblies of alpha1-antitrypsin polymers.

A Novel Bioinspired PVDF Micro/Nano Hair Receptor for a Robot Sensing System

PubMed Central

Li, Fei; Liu, Weiting; Stefanini, Cesare; Fu, Xin; Dario, Paolo

2010-01-01

This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride) fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots. PMID:22315581

Self-Powered Active Sensor with Concentric Topography of Piezoelectric Fibers

NASA Astrophysics Data System (ADS)

Fuh, Yiin Kuen; Huang, Zih Ming; Wang, Bo Sheng; Li, Shan Chien

2017-01-01

In this study, we demonstrated a flexible and self-powered sensor based on piezoelectric fibers in the diameter range of nano- and micro-scales. Our work is distinctively different from previous electrospinning research; we fabricated this apparatus precisely via near-field electrospinning which has a spectacular performance to harvest mechanical deformation in arbitrary direction and a novel concentrically circular topography. There are many piezoelectric devices based on electrospinning polymeric fibers. However, the fibers were mostly patterned in parallel lines and they could be actuated in limited direction only. To overcome this predicament, we re-arranged the parallel alignment into concentric circle pattern which made it possible to collect the mechanical energy whenever the deformation is along same axis or not. Despite the change of topography, the output voltage and current could still reach to 5 V and 400 nA, respectively, despite the mechanical deformation was from different direction. This new arbitrarily directional piezoelectric generator with concentrically circular topography (PGCT) allowed the piezoelectric device to harvest more mechanical energy than the one-directional alignment fiber-based devices, and this PGCT could perform even better output which promised more versatile and efficient using as a wearable electronics or sensor.

Self-Powered Active Sensor with Concentric Topography of Piezoelectric Fibers.

PubMed

Fuh, Yiin Kuen; Huang, Zih Ming; Wang, Bo Sheng; Li, Shan Chien

2017-12-01

In this study, we demonstrated a flexible and self-powered sensor based on piezoelectric fibers in the diameter range of nano- and micro-scales. Our work is distinctively different from previous electrospinning research; we fabricated this apparatus precisely via near-field electrospinning which has a spectacular performance to harvest mechanical deformation in arbitrary direction and a novel concentrically circular topography. There are many piezoelectric devices based on electrospinning polymeric fibers. However, the fibers were mostly patterned in parallel lines and they could be actuated in limited direction only. To overcome this predicament, we re-arranged the parallel alignment into concentric circle pattern which made it possible to collect the mechanical energy whenever the deformation is along same axis or not. Despite the change of topography, the output voltage and current could still reach to 5 V and 400 nA, respectively, despite the mechanical deformation was from different direction. This new arbitrarily directional piezoelectric generator with concentrically circular topography (PGCT) allowed the piezoelectric device to harvest more mechanical energy than the one-directional alignment fiber-based devices, and this PGCT could perform even better output which promised more versatile and efficient using as a wearable electronics or sensor.

Visible high power fiber coupled diode lasers

NASA Astrophysics Data System (ADS)

Köhler, Bernd; Drovs, Simon; Stoiber, Michael; Dürsch, Sascha; Kissel, Heiko; Könning, Tobias; Biesenbach, Jens; König, Harald; Lell, Alfred; Stojetz, Bernhard; Löffler, Andreas; Strauß, Uwe

2018-02-01

In this paper we report on further development of fiber coupled high-power diode lasers in the visible spectral range. New visible laser modules presented in this paper include the use of multi single emitter arrays @ 450 nm leading to a 120 W fiber coupled unit with a beam quality of 44 mm x mrad, as well as very compact modules with multi-W output power from 405 nm to 640 nm. However, as these lasers are based on single emitters, power scaling quickly leads to bulky laser units with a lot of optical components to be aligned. We also report on a new approach based on 450 nm diode laser bars, which dramatically reduces size and alignment effort. These activities were performed within the German government-funded project "BlauLas": a maximum output power of 80 W per bar has been demonstrated @ 450 nm. We show results of a 200 μm NA0.22 fiber coupled 35 W source @ 450 nm, which has been reduced in size by a factor of 25 compared to standard single emitter approach. In addition, we will present a 200 μm NA0.22 fiber coupled laser unit with an output power of 135 W.

Fiber optic sensor system for detecting movement or position of a rotating wheel bearing

DOEpatents

Veeser, Lynn R.; Rodriguez, Patrick J.; Forman, Peter R.; Monahan, Russell E.; Adler, Jonathan M.

1997-01-01

An improved fiber optic sensor system and integrated sensor bearing assembly for detecting movement or position of a rotating wheel bearing having a multi-pole tone ring which produces an alternating magnetic field indicative of movement and position of the rotating member. A magneto-optical material, such as a bismuth garnet iron (B.I.G.) crystal, having discrete magnetic domains is positioned in the vicinity of the tone ring so that the domains align themselves to the magnetic field generated by the tone ring. A single fiber optic cable, preferably single mode fiber, carries light generated by a source of light to the B.I.G. crystal. The light passes through the B.I.G. crystal and is refracted at domain boundaries in the crystal. The intensity of the refracted light is indicative of the amount of alignment of the domains and therefore the strength of the magnetic field. The refracted light is carried by the fiber optic cable to an optic receiver where the intensity is measured and an electrical signal is generated and sent to a controller indicating the frequency of the changes in light intensity and therefore the rotational speed of the rotating wheel bearing.

Design and fabrication of sub-wavelength annular apertures on fiber tip for femtosecond laser machining

NASA Astrophysics Data System (ADS)

Tung, Yen-Chun; Chung, Ming-Han; Sung, I.-Hui; Lee, Chih-Kung

2014-03-01

Adopting optical technique to pursue micromachining must make a compromise between the focal spot sizes the depth of focus. The focal spot size determines the minimum features can be fabricated. On the other hand, the depth of focus influences the ease of alignment in positioning the fabrication light beam. A typical approach to bypass the diffraction limit is to adopt the near-field approach, which has spot size in the range of the optical fiber tip. However, the depth of focus of the emitted light beam will be limited to tens of nanometers in most cases, which posts a difficult challenge to control the distance between the optical fiber tip and the sample to be machined optically. More specifically, problems remained in this machining approach, which include issues such as residue induced by laser ablation tends to deposit near the optical fiber tip and leads to loss of coupling efficiency. We proposed a method based on illuminating femtosecond laser through a sub-wavelength annular aperture on metallic film so as to produce Bessel light beam of sub-wavelength while maintaining large depth of focus first. To further advance the ease of use in one such system, producing sub-wavelength annular aperture on a single mode optical fiber head with sub-wavelength focusing ability is detailed. It is shown that this method can be applied in material machining with an emphasis to produce high aspect ratio structure. Simulations and experimental results are presented in this paper.

Effects of mechanical repetitive load on bone quality around implants in rat maxillae

PubMed Central

Uto, Yusuke; Nakano, Takayoshi; Ishimoto, Takuya; Inaba, Nao; Uchida, Yusuke; Sawase, Takashi

2017-01-01

Greater understanding and acceptance of the new concept “bone quality”, which was proposed by the National Institutes of Health and is based on bone cells and collagen fibers, are required. The novel protein Semaphorin3A (Sema3A) is associated with osteoprotection by regulating bone cells. The aims of this study were to investigate the effects of mechanical loads on Sema3A production and bone quality based on bone cells and collagen fibers around implants in rat maxillae. Grade IV-titanium threaded implants were placed at 4 weeks post-extraction in maxillary first molars. Implants received mechanical loads (10 N, 3 Hz for 1800 cycles, 2 days/week) for 5 weeks from 3 weeks post-implant placement to minimize the effects of wound healing processes by implant placement. Bone structures, bone mineral density (BMD), Sema3A production and bone quality based on bone cells and collagen fibers were analyzed using microcomputed tomography, histomorphometry, immunohistomorphometry, polarized light microscopy and birefringence measurement system inside of the first and second thread (designated as thread A and B, respectively), as mechanical stresses are concentrated and differently distributed on the first two threads from the implant neck. Mechanical load significantly increased BMD, but not bone volume around implants. Inside thread B, but not thread A, mechanical load significantly accelerated Sema3A production with increased number of osteoblasts and osteocytes, and enhanced production of both type I and III collagen. Moreover, mechanical load also significantly induced preferential alignment of collagen fibers in the lower flank of thread B. These data demonstrate that mechanical load has different effects on Sema3A production and bone quality based on bone cells and collagen fibers between the inside threads of A and B. Mechanical load-induced Sema3A production may be differentially regulated by the type of bone structure or distinct stress distribution, resulting in control of bone quality around implants in jaw bones. PMID:29244883

Effects of mechanical repetitive load on bone quality around implants in rat maxillae.

PubMed

Uto, Yusuke; Kuroshima, Shinichiro; Nakano, Takayoshi; Ishimoto, Takuya; Inaba, Nao; Uchida, Yusuke; Sawase, Takashi

2017-01-01

Greater understanding and acceptance of the new concept "bone quality", which was proposed by the National Institutes of Health and is based on bone cells and collagen fibers, are required. The novel protein Semaphorin3A (Sema3A) is associated with osteoprotection by regulating bone cells. The aims of this study were to investigate the effects of mechanical loads on Sema3A production and bone quality based on bone cells and collagen fibers around implants in rat maxillae. Grade IV-titanium threaded implants were placed at 4 weeks post-extraction in maxillary first molars. Implants received mechanical loads (10 N, 3 Hz for 1800 cycles, 2 days/week) for 5 weeks from 3 weeks post-implant placement to minimize the effects of wound healing processes by implant placement. Bone structures, bone mineral density (BMD), Sema3A production and bone quality based on bone cells and collagen fibers were analyzed using microcomputed tomography, histomorphometry, immunohistomorphometry, polarized light microscopy and birefringence measurement system inside of the first and second thread (designated as thread A and B, respectively), as mechanical stresses are concentrated and differently distributed on the first two threads from the implant neck. Mechanical load significantly increased BMD, but not bone volume around implants. Inside thread B, but not thread A, mechanical load significantly accelerated Sema3A production with increased number of osteoblasts and osteocytes, and enhanced production of both type I and III collagen. Moreover, mechanical load also significantly induced preferential alignment of collagen fibers in the lower flank of thread B. These data demonstrate that mechanical load has different effects on Sema3A production and bone quality based on bone cells and collagen fibers between the inside threads of A and B. Mechanical load-induced Sema3A production may be differentially regulated by the type of bone structure or distinct stress distribution, resulting in control of bone quality around implants in jaw bones.

Poly(hydroxybutyrate)/chitosan Aligned Electrospun Scaffold as a Novel Substrate for Nerve Tissue Engineering

PubMed Central

Karimi, Afarin; Karbasi, Saeed; Razavi, Shahnaz; Zargar, Elham Naghash

2018-01-01

Background: Reconstruction of nervous system is a great challenge in the therapeutic medical field. Nerve tissue engineering is a novel method to regenerate nervous system in human health care. Tissue engineering has introduced novel approaches to promote and guide peripheral nerve regeneration using submicron and nanoscale fibrous scaffolds. Materials and Methods: In this study, 9 wt% poly(3-hydroxybutyrate) (PHB) solutions with two different ratios of chitosan (CTS) (15%, and 20%) were mixed in trifluoroacetic acid as a cosolvent. Thereafter, random and aligned PHB/CTS scaffolds were fabricated by electrospinning method in an appropriate condition. Results: Average diameters for aligned PHB, PHB/CTS 85:15 and PHB/CTS 80:20 were obtained as 675 nm, 740.3 nm, and 870.74 nm, which was lesser than random fibers. The solution components entity authenticity was approved by Fourier transform infrared. The addition of CTS decreased both water droplet contact angle from 124.79° to 43.14° in random and 110.87° to 33.49° in aligned PHB/CTS fibrous scaffold. Moreover, alignment of fibers causes tremendous increase in hydrophilicity of fibrous PHB/CTS substrate. Tensile strength increased from 6.41 MPa for random to 8.73 MPa for aligned PHB/CTS 85:15. Conclusions: Our results indicated that aligned PHB/CTS 85:15 nanofibers are the desired scaffold than the random PHB/CTS nanofibers for application in nerve tissue regeneration. PMID:29657929

Guiding the orientation of smooth muscle cells on random and aligned polyurethane/collagen nanofibers.

PubMed

Jia, Lin; Prabhakaran, Molamma P; Qin, Xiaohong; Ramakrishna, Seeram

2014-09-01

Fabricating scaffolds that can simulate the architecture and functionality of native extracellular matrix is a huge challenge in vascular tissue engineering. Various kinds of materials are engineered via nano-technological approaches to meet the current challenges in vascular tissue regeneration. During this study, nanofibers from pure polyurethane and hybrid polyurethane/collagen in two different morphologies (random and aligned) and in three different ratios of polyurethane:collagen (75:25; 50:50; 25:75) are fabricated by electrospinning. The fiber diameters of the nanofibrous scaffolds are in the range of 174-453 nm and 145-419 for random and aligned fibers, respectively, where they closely mimic the nanoscale dimensions of native extracellular matrix. The aligned polyurethane/collagen nanofibers expressed anisotropic wettability with mechanical properties which is suitable for regeneration of the artery. After 12 days of human aortic smooth muscle cells culture on different scaffolds, the proliferation of smooth muscle cells on hybrid polyurethane/collagen (3:1) nanofibers was 173% and 212% higher than on pure polyurethane scaffolds for random and aligned scaffolds, respectively. The results of cell morphology and protein staining showed that the aligned polyurethane/collagen (3:1) scaffold promote smooth muscle cells alignment through contact guidance, while the random polyurethane/collagen (3:1) also guided cell orientation most probably due to the inherent biochemical composition. Our studies demonstrate the potential of aligned and random polyurethane/collagen (3:1) as promising substrates for vascular tissue regeneration. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Optimal Parameter Design of Coarse Alignment for Fiber Optic Gyro Inertial Navigation System.

PubMed

Lu, Baofeng; Wang, Qiuying; Yu, Chunmei; Gao, Wei

2015-06-25

Two different coarse alignment algorithms for Fiber Optic Gyro (FOG) Inertial Navigation System (INS) based on inertial reference frame are discussed in this paper. Both of them are based on gravity vector integration, therefore, the performance of these algorithms is determined by integration time. In previous works, integration time is selected by experience. In order to give a criterion for the selection process, and make the selection of the integration time more accurate, optimal parameter design of these algorithms for FOG INS is performed in this paper. The design process is accomplished based on the analysis of the error characteristics of these two coarse alignment algorithms. Moreover, this analysis and optimal parameter design allow us to make an adequate selection of the most accurate algorithm for FOG INS according to the actual operational conditions. The analysis and simulation results show that the parameter provided by this work is the optimal value, and indicate that in different operational conditions, the coarse alignment algorithms adopted for FOG INS are different in order to achieve better performance. Lastly, the experiment results validate the effectiveness of the proposed algorithm.

Understanding Beam Alignment in a Coherent Lidar System

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Roychoudhari, Chandrasekhar

2015-01-01

Optical beam alignment in a coherent lidar (or ladar) receiver system plays a critical role in optimizing its performance. Optical alignment in a coherent lidar system dictates the wavefront curvature (phase front) and Poynting vector) matching of the local oscillator beam with the incoming receiver beam on a detector. However, this alignment is often not easy to achieve and is rarely perfect. Furthermore, optical fibers are being increasingly used in coherent lidar system receivers for transporting radiation to achieve architectural elegance. Single mode fibers also require stringent mode matching for efficient light coupling. The detector response characteristics vary with the misalignment of the two pointing vectors. Misalignment can lead to increase in DC current. Also, a lens in front of the detector may exasperate phase front and Poynting vector mismatch. Non-Interaction of Waves, or the NIW property indicates the light beams do not interfere by themselves in the absence of detecting dipoles. In this paper, we will analyze the extent of misalignment on the detector specifications using pointing vectors of mixing beams in light of the NIW property.

Structural Inheritance of the Actin Cytoskeletal Organization Determines the Body Axis in Regenerating Hydra.

PubMed

Livshits, Anton; Shani-Zerbib, Lital; Maroudas-Sacks, Yonit; Braun, Erez; Keren, Kinneret

2017-02-07

Understanding how mechanics complement bio-signaling in defining patterns during morphogenesis is an outstanding challenge. Here, we utilize the multicellular polyp Hydra to investigate the role of the actomyosin cytoskeleton in morphogenesis. We find that the supra-cellular actin fiber organization is inherited from the parent Hydra and determines the body axis in regenerating tissue segments. This form of structural inheritance is non-trivial because of the tissue folding and dynamic actin reorganization involved. We further show that the emergence of multiple body axes can be traced to discrepancies in actin fiber alignment at early stages of the regeneration process. Mechanical constraints induced by anchoring regenerating Hydra on stiff wires suppressed the emergence of multiple body axes, highlighting the importance of mechanical feedbacks in defining and stabilizing the body axis. Together, these results constitute an important step toward the development of an integrated view of morphogenesis that incorporates mechanics. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Analysis of poration-induced changes in cells from laser-activated plasmonic substrates

PubMed Central

Saklayen, Nabiha; Kalies, Stefan; Madrid, Marinna; Nuzzo, Valeria; Huber, Marinus; Shen, Weilu; Sinanan-Singh, Jasmine; Heinemann, Dag; Heisterkamp, Alexander; Mazur, Eric

2017-01-01

Laser-exposed plasmonic substrates permeabilize the plasma membrane of cells when in close contact to deliver cell-impermeable cargo. While studies have determined the cargo delivery efficiency and viability of laser-exposed plasmonic substrates, morphological changes in a cell have not been quantified. We porated myoblast C2C12 cells on a plasmonic pyramid array using a 532-nm laser with 850-ps pulse length and time-lapse fluorescence imaging to quantify cellular changes. We obtain a poration efficiency of 80%, viability of 90%, and a pore radius of 20 nm. We quantified area changes in the plasma membrane attached to the substrate (10% decrease), nucleus (5 – 10% decrease), and cytoplasm (5 – 10% decrease) over 1 h after laser treatment. Cytoskeleton fibers show a change of 50% in the alignment, or coherency, of fibers, which stabilizes after 10 mins. We investigate structural and morphological changes due to the poration process to enable the safe development of this technique for therapeutic applications. PMID:29082100

Aligned 1-D nanorods of a π-gelator exhibit molecular orientation and excitation energy transport different from entangled fiber networks.

PubMed

Sakakibara, Keita; Chithra, Parayalil; Das, Bidisa; Mori, Taizo; Akada, Misaho; Labuta, Jan; Tsuruoka, Tohru; Maji, Subrata; Furumi, Seiichi; Shrestha, Lok Kumar; Hill, Jonathan P; Acharya, Somobrata; Ariga, Katsuhiko; Ajayaghosh, Ayyappanpillai

2014-06-18

Linear π-gelators self-assemble into entangled fibers in which the molecules are arranged perpendicular to the fiber long axis. However, orientation of gelator molecules in a direction parallel to the long axes of the one-dimensional (1-D) structures remains challenging. Herein we demonstrate that, at the air-water interface, an oligo(p-phenylenevinylene)-derived π-gelator forms aligned nanorods of 340 ± 120 nm length and 34 ± 5 nm width, in which the gelator molecules are reoriented parallel to the long axis of the rods. The orientation change of the molecules results in distinct excited-state properties upon local photoexcitation, as evidenced by near-field scanning optical microscopy. A detailed understanding of the mechanism by which excitation energy migrates through these 1-D molecular assemblies might help in the design of supramolecular structures with improved charge-transport properties.

Optical waveguide circuit board with a surface-mounted optical receiver array

NASA Astrophysics Data System (ADS)

Thomson, J. E.; Levesque, Harold; Savov, Emil; Horwitz, Fred; Booth, Bruce L.; Marchegiano, Joseph E.

1994-03-01

A photonic circuit board is fabricated for potential application to interchip and interboard parallel optical links. The board comprises photolithographically patterned polymer optical waveguides on a conventional glass-epoxy electrical circuit board and a surface-mounted integrated circuit (IC) package that optically and electrically couples to an optoelectronic IC. The waveguide circuits include eight-channel arrays of straights, cross-throughs, curves, self- aligning interconnects to multi-fiber ribbon, and out-of-plane turning mirrors. A coherent, fused bundle of optical fibers couples light between 45-deg waveguide mirrors and a GaAs receiver array in the IC package. The fiber bundle is easily aligned to the mirrors and the receivers and is amenable to surface mounting and hermetic sealing. The waveguide-receiver- array board achieved error-free data rates up to 1.25 Gbits/s per channel, and modal noise was shown to be negligible.

Evanescent-wave photoacoustic spectroscopy with optical micro/nano fibers.

PubMed

Cao, Yingchun; Jin, Wei; Ho, Lut Hoi; Liu, Zhibo

2012-01-15

We demonstrate gas detection based on evanescent-wave photoacoustic (PA) spectroscopy with tapered optical fibers. Evanescent-field instead of open-path absorption is exploited for PA generation, and a quartz tuning fork is used for PA detection. A tapered optical fiber with a diameter down to the wavelength scale demonstrates detection sensitivity similar to an open-path system but with the advantages of easier optical alignment, smaller insertion loss, and multiplexing capability.

Synthesis of high crystallinity ZnO nanowire array on polymer substrate and flexible fiber-based sensor.

PubMed

Liu, Jinmei; Wu, Weiwei; Bai, Suo; Qin, Yong

2011-11-01

Well aligned ZnO nanowire (NW) arrays are grown on Kevlar fiber and Kapton film via the chemical vapor deposition (CVD) method. These NWs have better crystallinity than those synthesized through the low-temperature hydrothermal method. The average length and diameter of ZnO NWs grown on Kevlar fiber can be controlled from 0.5 to 2.76 μm and 30 to 300 nm, respectively. A flexible ultraviolet (UV) sensor based on Kevlar fiber/ZnO NWs hybrid structure is made to detect UV illumination quantificationally.

Novel spot size converter for coupling standard single mode fibers to SOI waveguides

NASA Astrophysics Data System (ADS)

Sisto, Marco Michele; Fisette, Bruno; Paultre, Jacques-Edmond; Paquet, Alex; Desroches, Yan

2016-03-01

We have designed and numerically simulated a novel spot size converter for coupling standard single mode fibers with 10.4μm mode field diameter to 500nm × 220nm SOI waveguides. Simulations based on the eigenmode expansion method show a coupling loss of 0.4dB at 1550nm for the TE mode at perfect alignment. The alignment tolerance on the plane normal to the fiber axis is evaluated at +/-2.2μm for <=1dB excess loss, which is comparable to the alignment tolerance between two butt-coupled standard single mode fibers. The converter is based on a cross-like arrangement of SiOxNy waveguides immersed in a 12μm-thick SiO2 cladding region deposited on top of the SOI chip. The waveguides are designed to collectively support a single degenerate mode for TE and TM polarizations. This guided mode features a large overlap to the LP01 mode of standard telecom fibers. Along the spot size converter length (450μm), the mode is first gradually confined in a single SiOxNy waveguide by tapering its width. Then, the mode is adiabatically coupled to a SOI waveguide underneath the structure through a SOI inverted taper. The shapes of SiOxNy and SOI tapers are optimized to minimize coupling loss and structure length, and to ensure adiabatic mode evolution along the structure, thus improving the design robustness to fabrication process errors. A tolerance analysis based on conservative microfabrication capabilities suggests that coupling loss penalty from fabrication errors can be maintained below 0.3dB. The proposed spot size converter is fully compliant to industry standard microfabrication processes available at INO.

Fiber-optic polarization diversity detection for rotary probe optical coherence tomography.

PubMed

Lee, Anthony M D; Pahlevaninezhad, Hamid; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre

2014-06-15

We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways.

Simulation studies on the effect of positioning tolerances on optical coupling efficiency

NASA Astrophysics Data System (ADS)

Pamidighantam, Ramana V.; Yeo, Yongkee; Sudharsanam, Krishnamachari; Lee, Sik Pong; Iyer, Mahadevan K.

2002-08-01

The development of Optoelectronic components for communications is converging towards access networks where device cost makes a significant impact on the market acceptance. Thus, the device design engineer needs to input assembly, fabrication and process constraints into the design at an early stage. The present study is part of a Project on Packaging of Optical Components that IME, Singapore has initiated as part of an ongoing Electronics Packaging Research Consortium with industry partnership. In the present study, the coupling of optical radiation from a laser diode to optical fiber is simulated for a fiber optic transmitter component development project. Different optical configurations based on direct coupling, spherical ball lenses, integral lensed fibers and thermally expanded fibers are created within the commercially available transmitter package space. The effect of optical element variables on the placement tolerance is analyzed and will be reported. The effect of alignment tolerances on the optical coupling is analyzed. Simulation results are presented recommending realizable alignment and placement tolerances to develop a low cost short range link distance transmitter.

Engineered plant biomass feedstock particles

DOEpatents

Dooley, James H [Federal Way, WA; Lanning, David N [Federal Way, WA; Broderick, Thomas F [Lake Forest Park, WA

2011-10-11

A novel class of flowable biomass feedstock particles with unusually large surface areas that can be manufactured in remarkably uniform sizes using low-energy comminution techniques. The feedstock particles are roughly parallelepiped in shape and characterized by a length dimension (L) aligned substantially with the grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. The particles exhibit a disrupted grain structure with prominent end and surface checks that greatly enhances their skeletal surface area as compared to their envelope surface area. The L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers. The W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers. The L.times.W dimensions define a pair of substantially parallel top surfaces characterized by some surface checking between longitudinally arrayed fibers. The feedstock particles are manufactured from a variety of plant biomass materials including wood, crop residues, plantation grasses, hemp, bagasse, and bamboo.

Orientational alignment in solids from bidimensional isotropic-anisotropic nuclear magnetic resonance spectroscopy: applications to the analysis of aramide fibers.

PubMed

Sachleben, J R; Frydman, L

1997-02-01

The use of two-dimensional isotropic-anisotropic correlation spectroscopy for the analysis of orientational alignment in solids is presented. The theoretical background and advantages of this natural-abundance 13C NMR method of measurement are discussed, and demonstrated with a series of powder and single-crystal variable-angle correlation spectroscopy (VACSY) experiments on model systems. The technique is subsequently employed to analyze the orientational distributions of three polymer fibers: Kevlar 29, Kevlar 49 and Kevlar 149. Using complementary two-dimensional NMR data recorded on synthetic samples of poly(p-phenyleneterephthalamide), the precursor of Kevlar, it was found that these commercial fibers possess molecules distributed over a very narrow orientational range with respect to the macroscopic director. The widths measured for these director distribution arrangements were (12 +/- 1.5) degrees for Kevlar 29, (15 +/- 1.5) degrees for Kevlar 49, and (8 +/- 1.5) degrees for Kevlar 149. These figures compare well with previous results obtained for non-commercial fiber samples derived from the same polymer.

Triple-Layer Vascular Grafts Fabricated by Combined E-Jet 3D Printing and Electrospinning.

PubMed

Huang, Ruiying; Gao, Xiangkai; Wang, Jian; Chen, Haoxiang; Tong, Chunyi; Tan, Yongjun; Tan, Zhikai

2018-05-29

Small-diameter tissue-engineered vascular grafts are urgently needed for clinic arterial substitute. To simulate the structures and functions of natural blood vessels, we designed a novel triple-layer poly(ε-caprolactone) (PCL) fibrous vascular graft by combining E-jet 3D printing and electrospinning techniques. The resultant vascular graft consisted of an interior layer comprising 3D-printed highly aligned strong fibers, a middle layer made by electrospun densely fibers, and an exterior structure composed of mixed fibers fabricated by co-electrospraying. The biocompatible triple-layer graft was used for in vivo implantation, and results demonstrated that the longitudinally-aligned fibers within the lumen of the graft could enhance the proliferation and migration of endothelial cells, while maintained good mechanical properties. The exterior layer provided a pathway that encouraged cells to migrate into the scaffold after implantation. This experimental graft overcame the limitations of conventionally electrospun vascular grafts of inadequate porosity and lowly cell penetration. The unique structure of the triple-layer vascular graft promoted cell growth and infiltration in vivo, thus provided an encouraging substitute for in situ tissue engineering.

Formation of contractile networks and fibers in the medial cell cortex through myosin-II turnover, contraction, and stress-stabilization

PubMed Central

Nie, Wei; Wei, Ming-Tzo; Ou-Yang, Daniel H.; Jedlicka, Sabrina S.; Vavylonis, Dimitrios

2015-01-01

The morphology of adhered cells depends crucially on the formation of a contractile meshwork of parallel and cross-linked fibers along the contacting surface. The motor activity and minifilament assembly of non-muscle myosin-II is an important component of cortical cytoskeletal remodeling during mechanosensing. We used experiments and computational modeling to study cortical myosin-II dynamics in adhered cells. Confocal microscopy was used to image the medial cell cortex of HeLa cells stably expressing myosin regulatory light chain tagged with GFP (MRLC-GFP). The distribution of MRLC-GFP fibers and focal adhesions was classified into three types of network morphologies. Time-lapse movies show: myosin foci appearance and disappearance; aligning and contraction; stabilization upon alignment. Addition of blebbistatin, which perturbs myosin motor activity, leads to a reorganization of the cortical networks and to a reduction of contractile motions. We quantified the kinetics of contraction, disassembly and reassembly of myosin networks using spatio-temporal image correlation spectroscopy (STICS). Coarse-grained numerical simulations include bipolar minifilaments that contract and align through specified interactions as basic elements. After assuming that minifilament turnover decreases with increasing contractile stress, the simulations reproduce stress-dependent fiber formation in between focal adhesions above a threshold myosin concentration. The STICS correlation function in simulations matches the function measured in experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness. PMID:25641802

Modeling and characterization of dielectrophoretically structured piezoelectric composites using piezoceramic particle inclusions with high aspect ratios

NASA Astrophysics Data System (ADS)

van den Ende, D. A.; Maier, R. A.; van Neer, P. L. M. J.; van der Zwaag, S.; Randall, C. A.; Groen, W. A.

2013-01-01

In this work, the piezoelectric properties at high electric fields of dielectrophoretically aligned PZT—polymer composites containing high aspect ratio particles (such as short fibers) are presented. Polarization and strain as a function of electric field are evaluated. The properties of the composites are compared to those of PZT-polymer composites with equiaxed particles, continuous PZT fiber-polymer composites, and bulk PZT ceramics. From high-field polarization and strain measurements, the effective field dependent permittivity and piezoelectric charge constant in the poling direction are determined for dielectrophoresis structured PZT-polymer composites, continuous PZT fiber-polymer composites, and bulk PZT ceramics. The changes in dielectric properties of the inclusions and the matrix at high fields influence the dielectric and piezoelectric properties of the composites. It is found that the permittivity and piezoelectric charge constants increase towards a maximum at an applied field of around 2.5-5 kV/mm. The electric field at which the maximum occurs depends on the aspect ratio and degree of alignment of the inclusions. Experimental values of d33 at low and high applied fields are compared to a model describing the composites as a continuous polymer matrix containing PZT particles of various aspect ratios arranged into chains. Thickness mode coupling factors were determined from measured impedance data using fitted equivalent circuit model simulations. The relatively high piezoelectric strain constants, voltage constants, and thickness coupling factors indicate that such aligned short fiber composites could be useful as flexible large area transducers.

Controle de l'alignement des nanotubes de carbone multiparois a l'interieur d'un polymere et d''un materiau composite multi-echelles a l'aide d'un champ electrique

NASA Astrophysics Data System (ADS)

Arguin, Maxime

Composite materials are lightweight and have very good mechanical properties which make them a good alternative to metallic structures traditionally used in aircraft. However, these materials have a very low electrical conductivity compared to metal which limits their use for electrical application such as current return network. For example, carbon fiber composites have relatively good in-plane conductivity but a resistance between each ply, generated by the epoxy, reduced the conductivity through the thickness of the material by a thousand. The anisotropy results in a poor current diffusion through each layer of the composite and heat generation at surface when an electric current is applied on a composite panel. For this reason, the electrical conductivity of carbon fibers composite must be improved to be used for electrical applications. This thesis shows a new procedure to enhance the electrical conductivity of composite material in a preferential way (i.e., through the thickness). Multi-walled carbon nanotubes (MWCNTs) were added to the epoxy matrix of a composite to create multiscale composite. An electric field was also used to control the global distribution of the NTCs. Alignment results made on a UV epoxy reinforced with 0.01wt.% of MWCNTs showed a decrease of the resistivity by four orders of magnitude. This decrease of resistivity was also associated with formation of a filamentary microstructure that goes from one electrode to the others creating preferential conduction pathways. Afterwards, a hand lay-up process was modified to incorporate electric field alignment during the manufacturing of the composite. An improvement of the conductivity of 36% and 99% were obtained when an electric of 60V/mm were used to align the nanoparticles in multiscale composites containing 0.01wt.% and 0.1wt.% of MWCNTs, respectively. However, these modest improvements were still not enough to reach a complete current diffusion through the thickness but this technique is still a potential way to achieve it. Finally, the project shows the potential of using electric field induced alignment of the MWCNTs to improve the conductivity of multiscale composite. Furthermore, this technique has the advantage to be suitable to other common manufacturing processes using in the industry.

The effect of robo-horseback riding therapy on spinal alignment and associated muscle size in MRI for a child with neuromuscular scoliosis: an experimenter-blind study.

PubMed

Lee, Dong Ryul; Lee, Nam Gi; Cha, Hyun Jung; Yun Sung, O; You, Sung Joshua Hyun; Oh, Jin Hwan; Bang, Hyo Seong

2011-01-01

This case study was conducted to highlight the clinical and radiological features of a patient with progressive neuromuscular scoliosis before and after robo-horseback riding therapy (HBRT). A clinical, laboratory, and radiological analysis of a single case. An 11-year-old child, dignosed right thoracolumbar neuromuscular scoliosis secondary to cerebral palsy. The child received a 5-week course of robo-HBRT, comprising of 60-minute periods a day, five times a week. Postural alignment was determined by Cobb's method. A real-time magnetic resonance imaging (MRI) was performed to determine the robo-HBRT-induced changes in cross-sectional area (CSA) of bilateral thoracic (T2) and lumbar (L2) paraspinalis. Clinical tests including the standard Gross Motor Function Measure (GMFM) and manual muscle testing (MMT) with the Lafayette Manual Muscle Tester were used to compare the intervention-related changes in motor performance and power. The surface EMG was also used to examine therapy-induced changes in muscle activity amplitude for bilateral T2 and L2 paraspinalis and rectus abdominis muscles. Clinical motor and strength scores increased after the intervention. Radiographic Cobb's angle, MRI, and electromyographic amplitude data demonstrated notably enhanced spinal alignment and muscle fiber CSA and symmetry, respectively. This is the first study to provide evidence of the therapeutic efficacy of a novel form of robo-HBRT on motor function and associated structural and motor control improvements, thus suggesting a method of augmenting therapy in neuromuscular scoliosis.

Superporous thermo-responsive hydrogels by combination of cellulose fibers and aligned micropores.

PubMed

Halake, Kantappa S; Lee, Jonghwi

2014-05-25

In the area of artificial hydrogels, simultaneous engineering of the volume transition characteristics and mechanical properties of stimuli-responsive hydrogels is an important subject. By unrestricted architecting of hierarchical structures, natural hydrogels are able to provide a wide range of swelling and mechanical properties, beyond the limits of artificial hydrogels. Herein, a combination of nanostructures and microstructures was developed to construct superporous hydrogels. Fibers of microfibrillated cellulose (MFC), an eco-friendly reinforcing material, were used as nanostructures, aligned micropores were used as microstructures, and in situ photopolymerization was used to immobilize the two structures together within the gel networks of poly(N-isopropyl acrylamide) (PNIPAm). The introduction of MFC distinctly enhanced volume transition, mainly by decreasing the swelling ratios above the transition. The introduction of directional micropores increased the swelling ratio below the transition and decreased the swelling ratio above the transition, thereby also enhancing the volume transition. Additionally, the formation of aligned micropores achieved fast water infiltration, which is beneficial for superabsorbent applications. The introduction of aligned micropores reduced the elastic modulus, but this could partially be compensated for by reinforcement with MFC. This combination of crystalline nanofibers and aligned micropores has great potential for the development of stimuli-responsive superporous hydrogels outperforming current artificial hydrogels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Delamination toughness characterization of out-of-autoclave vacuum-bag-only polymer matrix composites enhanced by z-aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Brewer, John S.

Brewer, John S., M. S., University of South Alabama, May 2015. Delamination Toughness Characterization of Out-of-Autoclave Vacuum-Bag-Only Polymer Matrix Composites Enhanced by z-aligned Carbon Nanofibers. Chair of Committee: Kuang-Ting Hsiao, Ph.D. In the last few decades, the use of composite materials has revolutionized materials manufacturing. Now, carbon fiber materials are at the forefront of engineering and manufacturing technology. One of the chief failure modes of composite materials is delamination. For this reason, this study employed the Mode-I Interlaminar Fracture Toughness Test (ASTM D 5528-01) to characterize how the inclusion of z-aligned carbon nanofibers (CNF) in Carbon Fiber Reinforced Polymers (CFRP) affects delamination strength. CFRP with z-aligned CNF in concentrations of 0.3% and 0.6% by weight were compared to control CFRP samples and CFRP samples modified with 0.3 weight percent unaligned CNF. The largest improvement was seen in the 0.3 weight percent aligned composite with a mean interlaminar fracture toughness increase of over 35%, while the uncertainty was decreased. A standard deviation of 3.3% was observed which equates to an uncertainty value 30% better than the control samples. Data and microscopy are included and discussed.

New method of writing long-period fiber gratings using high-frequency CO2 laser

NASA Astrophysics Data System (ADS)

Guo, Gao-Ran; Song, Ying; Zhang, Wen-Tao; Jiang, Yue; Li, Fang

2016-11-01

In the paper, the Long period fiber gratings (LPFG) were fabricated in a single-mode fiber using a high frequency CO2 laser system with the point-to-point technique. The experimental setup consists of a CO2 laser controlling system, a focusing system located at a motorized linear stage, a fiber alignment stage, and an optical spectrum analyzer to monitor the transmission spectrum of the LPFG. The period of the LPFG is precisely inscribed by periodically turning on/off the laser shutter while the motorized linear stage is driven to move at a constant speed. The efficiency of fiber writing process is improved.

Use of polarized spectroscopy as a tool for examining the microstructure of cellulosic textile fibers.

PubMed

Garside, Paul; Wyeth, Paul

2007-05-01

Textile artifacts form a vital part of our cultural heritage. In order to determine appropriate methods of conservation, storage, and display, it is important to understand the current physical state of an artifact, as effected by the microstructure of the component fibers. The semi-crystalline nature of the constituent polymer aggregates, the degree of crystallinity, and the crystallite orientation have a significant influence on mechanical properties. The value of polarized Fourier transform infrared (FT-IR) spectroscopy in probing these aspects of cellulosic fibers has been assessed. A variety of representative fibers (both natural plant fibers and regenerated materials) were examined by polarized attenuated total reflection spectroscopy (Pol-ATR) and polarized infrared microspectroscopy (Pol-microIR); the former is a surface sampling technique and the latter is a transmission technique. The introduction of a polarizer into the system allows the alignment as well as the nature of bonds to be determined, and thus the presence and extent of crystallinity or long range ordering can be investigated. Using the data from the Pol-ATR experiments, it was found to be possible to derive the principle alignment of the cellulose polymer with respect to the fiber axis, along with an indication of the total cellulose crystallinity of the material, as measured by a crystallinity parameter, Chi. The Pol-microIR spectra, on the other hand, yielded more limited information, particularly when considering plant fibers with more complex microstructures.

Combined use of bFGF and GDF-5 enhances the healing of medial collateral ligament injury

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

Saiga, Kenta; Furumatsu, Takayuki, E-mail: matino@md.okayama-u.ac.jp; Yoshida, Aki

Research highlights: {yields} bFGF/GDF-5 treatment increases cellular proliferation and migration of MCL fibroblasts. {yields} bFGF/GDF-5 hydrogels stimulate the healing of MCL injury in vivo. {yields} bFGF/GDF-5 hydrogels stimulate Col1a1 expression and type I collagen synthesis. {yields} Combined use of bFGF/GDF-5 enhances MCL healing. -- Abstract: Basic fibroblast growth factor (bFGF) and growth and differentiation factor (GDF)-5 stimulate the healing of medial collateral ligament (MCL) injury. However, the effect of isolated and combined use of bFGF/GDF-5 remains still unclear. We investigated cellular proliferation and migration responding to bFGF/GDF-5 using rabbit MCL fibroblasts. Rabbit MCL injury was treated by bFGF and/or GDF-5more » with peptide hydrogels. Gene expression and deposition of collagens in healing tissues were evaluated. bFGF/GDF-5 treatment additively enhanced cell proliferation and migration. bFGF/GDF-5 hydrogels stimulated Col1a1 expression without increasing Col3a1 expression. Combined use of bFGF/GDF-5 stimulated type I collagen deposition and the reorganization of fiber alignment, and induced better morphology of fibroblasts in healing MCLs. Our study indicates that combined use of bFGF/GDF-5 might enhance MCL healing by increasing proliferation and migration of MCL fibroblasts, and by regulating collagen synthesis and connective fiber alignment.« less

Nanopatterned muscle cell patches for enhanced myogenesis and dystrophin expression in a mouse model of muscular dystrophy.

PubMed

Yang, Hee Seok; Ieronimakis, Nicholas; Tsui, Jonathan H; Kim, Hong Nam; Suh, Kahp-Yang; Reyes, Morayma; Kim, Deok-Ho

2014-02-01

Skeletal muscle is a highly organized tissue in which the extracellular matrix (ECM) is composed of highly-aligned cables of collagen with nanoscale feature sizes, and provides structural and functional support to muscle fibers. As such, the transplantation of disorganized tissues or the direct injection of cells into muscles for regenerative therapy often results in suboptimal functional improvement due to a failure to integrate with native tissue properly. Here, we present a simple method in which biodegradable, biomimetic substrates with precisely controlled nanotopography were fabricated using solvent-assisted capillary force lithography (CFL) and were able to induce the proper development and differentiation of primary mononucleated cells to form mature muscle patches. Cells cultured on these nanopatterned substrates were highly-aligned and elongated, and formed more mature myotubes as evidenced by up-regulated expression of the myogenic regulatory factors Myf5, MyoD and myogenin (MyoG). When transplanted into mdx mice models for Duchenne muscular dystrophy (DMD), the proposed muscle patches led to the formation of a significantly greater number of dystrophin-positive muscle fibers, indicating that dystrophin replacement and myogenesis is achievable in vivo with this approach. These results demonstrate the feasibility of utilizing biomimetic substrates not only as platforms for studying the influences of the ECM on skeletal muscle function and maturation, but also to create transplantable muscle cell patches for the treatment of chronic and acute muscle diseases or injuries. Copyright © 2013 Elsevier Ltd. All rights reserved.

All fiber nonlinear microscopy at 1550 nm using a double-clad fiber coupler

NASA Astrophysics Data System (ADS)

Perrillat-Bottonet, Thomas; Strupler, Mathias; Leduc, Mikael; Majeau, Lucas; Godbout, Nicolas; Boudoux, Caroline

2017-02-01

Nonlinear microscopy has already shown its impact in biological research, namely in the fields of neurobiology, immunology, cancer research and embryology. Typically, these microscopes operate under free space propagation, using a dichroic mirror to separate the nonlinear signals from the excitation laser. While powerful such implementations are difficult to translate from the laboratory to a clinical setting where the environment is less controlled. Therefore, we propose an alignment-free all-fiber nonlinear microscopy system at 1550 nm based on double-clad fibers (DCF). As sectioning is performed through nonlinear effects, nonlinear microscopy does not require a detection pinhole, and. the DCF inner cladding can be used for efficient collection of nonlinear signals. The built system allows for multiplexing second harmonic generation (SHG) and two-photon excitation fluorescence (2PEF), collected from the inner cladding; and reflectance confocal microscopy (RCM), detected from the core acting as the confocal pinhole. Finally, an asymmetric double-clad fiber coupler (DCFC) is used to address efficiently both DCF channels. This all-fiber system is more compact and less sensitive to alignment, but requires carefully managing the transmission of the femtosecond pulse in the fiber. This is addressed using dispersion compensation fiber, pulse compression and solitonic propagation. Additionally, with a source centered at 1550 nm, we benefit from reduced sample scattering thus increasing the depth of field in comparison with systems operating at 800 nm. Overall we believe that the developed system could be transferred in clinics to enable in-vivo and in-situ imaging of human patient.

Multifunctional composites for energy storage

NASA Astrophysics Data System (ADS)

Shuvo, Mohammad Arif I.; Karim, Hasanul; Rajib, Md; Delfin, Diego; Lin, Yirong

2014-03-01

Electrochemical super-capacitors have become one of the most important topics in both academia and industry as novel energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been an increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles and portable electronics. These multifunctional structural super-capacitors provide lighter structures combining energy storage and load bearing functionalities. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area and fast ion diffusion rates. Scanning Electron Microscopy (SEM) and XRay Diffraction (XRD) measurements were used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing has been performed using a potentio-galvanostat. The results show that gold sputtered nanowire hybrid carbon fiber provides 65.9% better performance than bare carbon fiber cloth as super-capacitor.

Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

NASA Technical Reports Server (NTRS)

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1999-01-01

A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

Carbon fiber on polyimide ultra-microelectrodes

NASA Astrophysics Data System (ADS)

Gillis, Winthrop F.; Lissandrello, Charles A.; Shen, Jun; Pearre, Ben W.; Mertiri, Alket; Deku, Felix; Cogan, Stuart; Holinski, Bradley J.; Chew, Daniel J.; White, Alice E.; Otchy, Timothy M.; Gardner, Timothy J.

2018-02-01

Objective. Most preparations for making neural recordings degrade over time and eventually fail due to insertion trauma and reactive tissue response. The magnitudes of these responses are thought to be related to the electrode size (specifically, the cross-sectional area), the relative stiffness of the electrode, and the degree of tissue tolerance for the material. Flexible carbon fiber ultra-microelectrodes have a much smaller cross-section than traditional electrodes and low tissue reactivity, and thus may enable improved longevity of neural recordings in the central and peripheral nervous systems. Only two carbon fiber array designs have been described previously, each with limited channel densities due to limitations of the fabrication processes or interconnect strategies. Here, we describe a method for assembling carbon fiber electrodes on a flexible polyimide substrate that is expected to facilitate the construction of high-density recording and stimulating arrays. Approach. Individual carbon fibers were aligned using an alignment tool that was 3D-printed with sub-micron resolution using direct laser writing. Indium deposition on the carbon fibers, followed by low-temperature microsoldering, provided a robust and reliable method of electrical connection to the polyimide interconnect. Main results. Spontaneous multiunit activity and stimulation-evoked compound responses with SNR  >10 and  >120, respectively, were recorded from a small (125 µm) peripheral nerve. We also improved the typically poor charge injection capacity of small diameter carbon fibers by electrodepositing 100 nm-thick iridium oxide films, making the carbon fiber arrays usable for electrical stimulation as well as recording. Significance. Our innovations in fabrication technique pave the way for further miniaturization of carbon fiber ultra-microelectrode arrays. We believe these advances to be key steps to enable a shift from labor intensive, manual assembly to a more automated manufacturing process.

Carbon fiber on polyimide ultra-microelectrodes.

PubMed

Gillis, Winthrop F; Lissandrello, Charles A; Shen, Jun; Pearre, Ben W; Mertiri, Alket; Deku, Felix; Cogan, Stuart; Holinski, Bradley J; Chew, Daniel J; White, Alice E; Otchy, Timothy M; Gardner, Timothy J

2018-02-01

Most preparations for making neural recordings degrade over time and eventually fail due to insertion trauma and reactive tissue response. The magnitudes of these responses are thought to be related to the electrode size (specifically, the cross-sectional area), the relative stiffness of the electrode, and the degree of tissue tolerance for the material. Flexible carbon fiber ultra-microelectrodes have a much smaller cross-section than traditional electrodes and low tissue reactivity, and thus may enable improved longevity of neural recordings in the central and peripheral nervous systems. Only two carbon fiber array designs have been described previously, each with limited channel densities due to limitations of the fabrication processes or interconnect strategies. Here, we describe a method for assembling carbon fiber electrodes on a flexible polyimide substrate that is expected to facilitate the construction of high-density recording and stimulating arrays. Individual carbon fibers were aligned using an alignment tool that was 3D-printed with sub-micron resolution using direct laser writing. Indium deposition on the carbon fibers, followed by low-temperature microsoldering, provided a robust and reliable method of electrical connection to the polyimide interconnect. Spontaneous multiunit activity and stimulation-evoked compound responses with SNR  >10 and  >120, respectively, were recorded from a small (125 µm) peripheral nerve. We also improved the typically poor charge injection capacity of small diameter carbon fibers by electrodepositing 100 nm-thick iridium oxide films, making the carbon fiber arrays usable for electrical stimulation as well as recording. Our innovations in fabrication technique pave the way for further miniaturization of carbon fiber ultra-microelectrode arrays. We believe these advances to be key steps to enable a shift from labor intensive, manual assembly to a more automated manufacturing process.

Nanowire modified carbon fibers for enhanced electrical energy storage

NASA Astrophysics Data System (ADS)

Shuvo, Mohammad Arif Ishtiaque; (Bill) Tseng, Tzu-Liang; Ashiqur Rahaman Khan, Md.; Karim, Hasanul; Morton, Philip; Delfin, Diego; Lin, Yirong

2013-09-01

The study of electrochemical super-capacitors has become one of the most attractive topics in both academia and industry as energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles, and portable electronics. These multifunctional structural super-capacitors provide structures combining energy storage and load bearing functionalities, leading to material systems with reduced volume and/or weight. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires, which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area thus fast ion diffusion rates. Scanning Electron Microscopy and X-Ray Diffraction measurements are used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing is performed using a potentio-galvanostat. The results show that gold sputtered nanowire carbon fiber hybrid provides 65.9% higher energy density than bare carbon fiber cloth as super-capacitor.

Design of practical alignment device in KSTAR Thomson diagnostic

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

Lee, J. H., E-mail: jhlee@nfri.re.kr; University of Science and Technology; Lee, S. H.

2016-11-15

The precise alignment of the laser path and collection optics in Thomson scattering measurements is essential for accurately determining electron temperature and density in tokamak experiments. For the last five years, during the development stage, the KSTAR tokamak’s Thomson diagnostic system has had alignment fibers installed in its optical collection modules, but these lacked a proper alignment detection system. In order to address these difficulties, an alignment verifying detection device between lasers and an object field of collection optics is developed. The alignment detection device utilizes two types of filters: a narrow laser band wavelength for laser, and a broadmore » wavelength filter for Thomson scattering signal. Four such alignment detection devices have been successfully developed for the KSTAR Thomson scattering system in this year, and these will be tested in KSTAR experiments in 2016. In this paper, we present the newly developed alignment detection device for KSTAR’s Thomson scattering diagnostics.« less

Design of practical alignment device in KSTAR Thomson diagnostic.

PubMed

Lee, J H; Lee, S H; Yamada, I

2016-11-01

The precise alignment of the laser path and collection optics in Thomson scattering measurements is essential for accurately determining electron temperature and density in tokamak experiments. For the last five years, during the development stage, the KSTAR tokamak's Thomson diagnostic system has had alignment fibers installed in its optical collection modules, but these lacked a proper alignment detection system. In order to address these difficulties, an alignment verifying detection device between lasers and an object field of collection optics is developed. The alignment detection device utilizes two types of filters: a narrow laser band wavelength for laser, and a broad wavelength filter for Thomson scattering signal. Four such alignment detection devices have been successfully developed for the KSTAR Thomson scattering system in this year, and these will be tested in KSTAR experiments in 2016. In this paper, we present the newly developed alignment detection device for KSTAR's Thomson scattering diagnostics.

Stripping and splicing polyimide-coated fibers

NASA Astrophysics Data System (ADS)

Duke, Douglas; Kanda, Yoshiharu; Tobita, Kenyo; Yamauchi, Ryozo

2011-05-01

Polyimide is often used as a coating material for optical fibers used in high temperature environments such as aerospace or oil and gas sensor applications. Unfortunately, polyimide coating is very difficult to strip by conventional mechanical stripping methods. The glass fiber is easily damaged if the stripping process is not extremely well controlled. Stripping the polyimide coating by heating with a flame or arc typically results in a significant reduction in fiber strength. Strength may be maintained by using hot acid stripping, however the use of the strong hot acid presents safety hazards and also requires controlled and safe waste disposal. Another issue with polyimide coating is variability of the coating diameter from various manufacturers or due to different polyimide coating processes. This not only complicates the polyimide stripping issue, but also presents problems with precise clamping and alignment during splicing, especially when it is necessary to splice with a short cleave length. In this paper, we present new polyimide coating stripping technology. The significant feature of this stripping technology is achievement of good strength while avoiding the use of hot acid or heating. We also developed a new specialty fiber fusion splicer that enables precise alignment and splicing regardless of the variability of polyimide coating diameter, even when clamping on the coating.

Effects on diameter and morphology of polycaprolactone nanofibers infused with various concentrations of selenium nanoparticles

NASA Astrophysics Data System (ADS)

Kamaruzaman, Nurul Asyikin; Yusoff, Abdull Rahim Mohd; Buang, Nor Aziah; Salleh, Nik Ghazali Nik

2017-12-01

Electrospinning is one of the techniques used in the fabrication of nanofibers. Polycaprolactone (PCL), is a biodegradable polymer which was commonly electrospun without the presence of nanoparticles as additives and/or filler in the applications such as tissue engineering, biosensors, filtration, wound dressings, drug delivery and enzyme immobilization. In this study, via FESEM analyses, the effects on the diameter and morphology of PCL nanofibers was investigated with respect to various concentration of selenium nanoparticles (SeNP). Increasing the concentration of SeNP from 0.2 to 1.0% (w/v) resulted in increased of fiber diameter as well as the density of the nanofiber networking. Consequently, the formation of beads have also increased with the increment of the concentration of SeNP. The images from FESEM micrographs showed the formation of "aligned fibers" with the average size of less than 550 nm. The optimized concentration of SeNP obtained was 0.4 % w/v for the formation of aligned fibers with a uniform diameter in size and the least formation of beads in the matrices. Aligned nanofibers are biocompatible and can be used in tissue engineering and wound dressing applications. Meanwhile, nanofibers with beads are suitable for filtration design in water and gaseous applications.

Fluid Shear Stress-Induced JNK Activity Leads to Actin Remodeling for Cell Alignment

PubMed Central

Mengistu, Meron; Brotzman, Hannah; Ghadiali, Samir; Lowe-Krentz, Linda

2012-01-01

Fluid shear stress (FSS) exerted on endothelial cell surfaces induces actin cytoskeleton remodeling through mechanotransduction. This study was designed to determine whether FSS activates Jun N-terminal kinase (JNK), to examine the spatial and temporal distribution of active JNK relative to the actin cytoskeleton in endothelial cells exposed to different FSS conditions, and to evaluate the effects of active JNK on actin realignment. Exposure to 15 and 20 dyn/cm2 FSS induced higher activity levels of JNK than the lower 2 and 4 dyn/cm2 flow conditions. At the higher FSS treatments, JNK activity increased with increasing exposure time, peaking 30 minutes after flow onset with an 8-fold activity increase compared to cells in static culture. FSS-induced phospho-JNK co-localized with actin filaments at cell peripheries, as well as with stress fibers. Pharmacologically blocking JNK activity altered FSS-induced actin structure and distribution as a response to FSS. Our results indicate that FSS-induced actin remodeling occurs in three phases, and that JNK plays a role in at least one, suggesting that this kinase activity is involved in mechanotransduction from the apical surface to the actin cytoskeleton in endothelial cells. PMID:20626006

Tension-induced binding of semiflexible biopolymers

NASA Astrophysics Data System (ADS)

Benetatos, Panayotis; von der Heydt, Alice; Zippelius, Annette

2015-03-01

We investigate theoretically the effect of polymer tension on the collective behaviour of reversible cross-links. We use a model of two parallel-aligned, weakly-bending wormlike chains with a regularly spaced sequence of binding sites subjected to a tensile force. Reversible cross-links attach and detach at the binding sites with an affinity controlled by a chemical potential. In a mean-field approach, we calculate the free energy of the system and we show the emergence of a free energy barrier which controls the reversible (un)binding. The tension affects the conformational entropy of the chains which competes with the binding energy of the cross-links. This competition gives rise to a sudden increase in the fraction of bound sites as the polymer tension increases. The force-induced first-order transition in the number of cross-links implies a sudden force-induced stiffening of the effective stretching modulus of the polymers. This mechanism may be relevant to the formation and stress-induced strengthening of stress fibers in the cytoskeleton. We acknowledge support by the Deutsche Forschungsgemeinschaft (DFG) via grant SFB-937/A1.

Rugged fiber optic probe for raman measurement

DOEpatents

O'Rourke, Patrick E.; Toole, Jr., William R.; Nave, Stanley E.

1998-01-01

An optical probe for conducting light scattering analysis is disclosed. The probe comprises a hollow housing and a probe tip. A fiber assembly made up of a transmitting fiber and a receiving bundle is inserted in the tip. A filter assembly is inserted in the housing and connected to the fiber assembly. A signal line from the light source and to the spectrometer also is connected to the filter assembly and communicates with the fiber assembly. By using a spring-loaded assembly to hold the fiber connectors together with the in-line filters, complex and sensitive alignment procedures are avoided. The close proximity of the filter assembly to the probe tip eliminates or minimizes self-scattering generated by the optical fiber. Also, because the probe can contact the sample directly, sensitive optics can be eliminated.

Three-dimensional smoothed particle hydrodynamics simulation for injection molding flow of short fiber-reinforced polymer composites

NASA Astrophysics Data System (ADS)

He, Liping; Lu, Gang; Chen, Dachuan; Li, Wenjun; Lu, Chunsheng

2017-07-01

This paper investigates the three-dimensional (3D) injection molding flow of short fiber-reinforced polymer composites using a smoothed particle hydrodynamics (SPH) simulation method. The polymer melt was modeled as a power law fluid and the fibers were considered as rigid cylindrical bodies. The filling details and fiber orientation in the injection-molding process were studied. The results indicated that the SPH method could effectively predict the order of filling, fiber accumulation, and heterogeneous distribution of fibers. The SPH simulation also showed that fibers were mainly aligned to the flow direction in the skin layer and inclined to the flow direction in the core layer. Additionally, the fiber-orientation state in the simulation was quantitatively analyzed and found to be consistent with the results calculated by conventional tensor methods.

Vertically aligned TiO2 nanorods-woven carbon fiber for reinforcement of both mechanical and anti-wear properties in resin composite

NASA Astrophysics Data System (ADS)

Fei, Jie; Zhang, Chao; Luo, Dan; Cui, Yali; Li, Hejun; Lu, Zhaoqing; Huang, Jianfeng

2018-03-01

A series of TiO2 nanorods were successfully grown on woven carbon fiber by hydrothermal method to reinforce the resin composite. The TiO2 nanorods improved the mechanical interlocking among woven carbon fibers and resin matrix, resulting in better fibers/resin interfacial bonding. Compared with desized-woven carbon fiber, the uniform TiO2 nanorods array resulted in an improvement of 84.3% and 73.9% in the tensile and flexural strength of the composite. However, the disorderly TiO2 nanorods on woven carbon fiber leaded to an insignificant promotion of the mechanical strength. The enhanced performance of well-proportioned TiO2 nanorods-woven carbon fiber was also reflected in the nearly 56% decrease of wear rate, comparing to traditional woven carbon fiber reinforced composite.

Nondestructive evaluation of ceramic and metal matrix composites for NASA's HITEMP and enabling propulsion materials programs

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

1992-01-01

In a preliminary study, ultrasonic, x-ray opaque, and fluorescent dye penetrants techniques were used to evaluate and characterize ceramic and metal matrix composites. Techniques are highlighted for identifying porosity, fiber alignment, fiber uniformity, matrix cracks, fiber fractures, unbonds or disbonds between laminae, and fiber-to-matrix bond variations. The nondestructive evaluations (NDE) were performed during processing and after thermomechanical testing. Specific examples are given for Si3N4/SiC (SCS-6 fiber), FeCrAlY/Al2O3 fibers, Ti-15-3/SiC (SCS-6 fiber) materials, and Si3N4/SiC (SCS-6 fiber) actively cooled panel components. Results of this study indicate that the choice of the NDE tools to be used can be optimized to yield a faithful and accurate evaluation of advanced composites.

Microfluidic flow rate detection based on integrated optical fiber cantilever.

PubMed

Lien, Victor; Vollmer, Frank

2007-10-01

We demonstrate an integrated microfluidic flow sensor with ultra-wide dynamic range, suitable for high throughput applications such as flow cytometry and particle sorting/counting. A fiber-tip cantilever transduces flow rates to optical signal readout, and we demonstrate a dynamic range from 0 to 1500 microL min(-1) for operation in water. Fiber-optic sensor alignment is guided by preformed microfluidic channels, and the dynamic range can be adjusted in a one-step chemical etch. An overall non-linear response is attributed to the far-field angular distribution of single-mode fiber output.

Surface-mount sapphire interferometric temperature sensor.

PubMed

Zhu, Yizheng; Wang, Anbo

2006-08-20

A fiber-optic high-temperature sensor is demonstrated by bonding a 45 degrees -polished single-crystal sapphire fiber on the surface of a sapphire wafer, whose optical thickness is temperature dependent and measured by white-light interferometry. A novel adhesive-free coupling between the silica and sapphire fibers is achieved by fusion splicing, and its performance is characterized. The sensor's interference signal is investigated for its dependence on angular alignment between the fiber and the wafer. A prototype sensor is tested to 1,170 degrees C with a resolution of 0.4 degrees C, demonstrating excellent potential for high-temperature measurement.

Piezoelectrically and triboelectrically hybridized self-powered sensor with applications to smart window and human motion detection

NASA Astrophysics Data System (ADS)

Fuh, Yiin-Kuen; Li, Shan-Chien; Chen, Chun-Yu

2017-07-01

In this paper, we demonstrate a hybrid generator, derived from the concurrent adoption of piezoelectric and triboelectric mechanisms in one press-and-release cycle, called a Hybridized Self-Powered sensor (HSPS). A new integration of print circuit board (PCB) technology-based piezoelectric generator (PG) concurrently adopted the direct-write, near-field electrospun polyvinylidene fluoride (PVDF) nano/micro-fibers as piezoelectric source materials. On the other hand, triboelectric nanogenerators have the advantages of a high output performance with a simple structure which is also concurrently combined with the PG. The working mechanism of the HSPS includes the PCB-based substrate mounted with parallel aligned piezoelectric PVDF fibers in planar configuration which first bended and generated the electric potential via the effect of piezoelectricity. In what follows, the deformation of a cylindrical rolled-up piezoelectric structure is exercised, and finally, the triboelectric contact of Cu and PTFE layers is physically rubbed against each other with a separation to induce the triboelectric potential. This hybridized generator with a double domed shape design simultaneously combines piezoelectric output and triboelectric output and offers a built-in spacer with automatically spring back capability, which produces a peak output voltage of 100 V, a current of 4 μA, and a maximum power output of 450 nW. A self-powered smart window system was experimentally driven through finger-induced strain of HSPS, showing the optical properties with reversibly tunable transmittances. This research is a substantial advancement in the field of piezoelectric PVDF fibers integration toward the practical application of the whole self-powered system.

Apparatus for injecting high power laser light into a fiber optic cable

DOEpatents

Sweatt, William C.

1997-01-01

High intensity laser light is evenly injected into an optical fiber by the combination of a converging lens and a multisegment kinoform (binary optical element). The segments preferably have multi-order gratings on each which are aligned parallel to a radial line emanating from the center of the kinoform and pass through the center of the element. The grating in each segment causes circumferential (lateral) dispersion of the light, thereby avoiding detrimental concentration of light energy within the optical fiber.

Radiation detection system

DOEpatents

Nelson, Melvin A.; Davies, Terence J.; Morton, III, John R.

1976-01-01

A radiation detection system which utilizes the generation of Cerenkov light in and the transmission of that light longitudinally through fiber optic wave guides in order to transmit intelligence relating to the radiation to a remote location. The wave guides are aligned with respect to charged particle radiation so that the Cerenkov light, which is generated at an angle to the radiation, is accepted by the fiber for transmission therethrough. The Cerenkov radiation is detected, recorded, and analyzed at the other end of the fiber.

Automated fiber pigtailing machine

DOEpatents

Strand, Oliver T.; Lowry, Mark E.

1999-01-01

The Automated Fiber Pigtailing Machine (AFPM) aligns and attaches optical fibers to optoelectonic (OE) devices such as laser diodes, photodiodes, and waveguide devices without operator intervention. The so-called pigtailing process is completed with sub-micron accuracies in less than 3 minutes. The AFPM operates unattended for one hour, is modular in design and is compatible with a mass production manufacturing environment. This machine can be used to build components which are used in military aircraft navigation systems, computer systems, communications systems and in the construction of diagnostics and experimental systems.

Miniature mechanical transfer optical coupler

DOEpatents

Abel, Philip [Overland Park, KS; Watterson, Carl [Kansas City, MO

2011-02-15

A miniature mechanical transfer (MT) optical coupler ("MMTOC") for optically connecting a first plurality of optical fibers with at least one other plurality of optical fibers. The MMTOC may comprise a beam splitting element, a plurality of collimating lenses, and a plurality of alignment elements. The MMTOC may optically couple a first plurality of fibers disposed in a plurality of ferrules of a first MT connector with a second plurality of fibers disposed in a plurality of ferrules of a second MT connector and a third plurality of fibers disposed in a plurality of ferrules of a third MT connector. The beam splitting element may allow a portion of each beam of light from the first plurality of fibers to pass through to the second plurality of fibers and simultaneously reflect another portion of each beam of light from the first plurality of fibers to the third plurality of fibers.

Integrating MRI-based geometry, composition and fiber architecture in a finite element model of the human intervertebral disc.

PubMed

Stadelmann, Marc A; Maquer, Ghislain; Voumard, Benjamin; Grant, Aaron; Hackney, David B; Vermathen, Peter; Alkalay, Ron N; Zysset, Philippe K

2018-05-17

Intervertebral disc degeneration is a common disease that is often related to impaired mechanical function, herniations and chronic back pain. The degenerative process induces alterations of the disc's shape, composition and structure that can be visualized in vivo using magnetic resonance imaging (MRI). Numerical tools such as finite element analysis (FEA) have the potential to relate MRI-based information to the altered mechanical behavior of the disc. However, in terms of geometry, composition and fiber architecture, current FE models rely on observations made on healthy discs and might therefore not be well suited to study the degeneration process. To address the issue, we propose a new, more realistic FE methodology based on diffusion tensor imaging (DTI). For this study, a human disc joint was imaged in a high-field MR scanner with proton-density weighted (PD) and DTI sequences. The PD image was segmented and an anatomy-specific mesh was generated. Assuming accordance between local principal diffusion direction and local mean collagen fiber alignment, corresponding fiber angles were assigned to each element. Those element-wise fiber directions and PD intensities allowed the homogenized model to smoothly account for composition and fibrous structure of the disc. The disc's in vitro mechanical behavior was quantified under tension, compression, flexion, extension, lateral bending and rotation. The six resulting load-displacement curves could be replicated by the FE model, which supports our approach as a first proof of concept towards patient-specific disc modeling. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrospinning fundamentals: optimizing solution and apparatus parameters.

PubMed

Leach, Michelle K; Feng, Zhang-Qi; Tuck, Samuel J; Corey, Joseph M

2011-01-21

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form - although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques.

Magnetically-induced solid-phase microextraction fiber actuation system for quantitative headspace and liquid sampling

DOEpatents

Harvey, Chris; Carter, Jerry; Chambers, David M.

2017-05-23

A magnetically-induced SPME fiber actuation system includes a SPME fiber holder and a SPME fiber holder actuator, for holding and magnetically actuating a SPME fiber assembly. The SPME fiber holder has a plunger with a magnetic material to which the SPME fiber assembly is connected, and the magnetic SPME fiber holder actuator has an elongated barrel with a loading chamber for receiving the SPME fiber assembly-connected SPME fiber holder, and an external magnet which induces axial motion of the magnetic material of the plunger to extend/retract the SPME fiber from/into the protective needle of the SPME fiber assembly.

Flow-aligned, single-shot fiber diffraction using a femtosecond X-ray free-electron laser

DOE PAGES

Popp, David; Loh, N. Duane; Zorgati, Habiba; ...

2017-06-02

A major goal for X-ray free-electron laser (XFEL) based science is to elucidate structures of biological molecules without the need for crystals. Filament systems may provide some of the first single macromolecular structures elucidated by XFEL radiation, since they contain one-dimensional translational symmetry and thereby occupy the diffraction intensity region between the extremes of crystals and single molecules. Here, we demonstrate flow alignment of as few as 100 filaments ( Escherichia coli pili, F-actin, and amyloid fibrils), which when intersected by femtosecond X-ray pulses result in diffraction patterns similar to those obtained from classical fiber diffraction studies. We also determinemore » that F-actin can be flow-aligned to a disorientation of approximately 5 degrees. Using this XFEL-based technique, we determine that gelsolin amyloids are comprised of stacked β-strands running perpendicular to the filament axis, and that a range of order from fibrillar to crystalline is discernable for individual α-synuclein amyloids.« less

Flow-aligned, single-shot fiber diffraction using a femtosecond X-ray free-electron laser

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

Popp, David; Loh, N. Duane; Zorgati, Habiba

A major goal for X-ray free-electron laser (XFEL) based science is to elucidate structures of biological molecules without the need for crystals. Filament systems may provide some of the first single macromolecular structures elucidated by XFEL radiation, since they contain one-dimensional translational symmetry and thereby occupy the diffraction intensity region between the extremes of crystals and single molecules. Here, we demonstrate flow alignment of as few as 100 filaments ( Escherichia coli pili, F-actin, and amyloid fibrils), which when intersected by femtosecond X-ray pulses result in diffraction patterns similar to those obtained from classical fiber diffraction studies. We also determinemore » that F-actin can be flow-aligned to a disorientation of approximately 5 degrees. Using this XFEL-based technique, we determine that gelsolin amyloids are comprised of stacked β-strands running perpendicular to the filament axis, and that a range of order from fibrillar to crystalline is discernable for individual α-synuclein amyloids.« less

Polarized emission from CsPbBr3 nanowire embedded-electrospun PU fibers

NASA Astrophysics Data System (ADS)

Güner, Tuğrul; Topçu, Gökhan; Savacı, Umut; Genç, Aziz; Turan, Servet; Sari, Emre; Demir, Mustafa M.

2018-04-01

Interest in all-inorganic halide perovskites has been increasing dramatically due to their high quantum yield, band gap tunability, and ease of fabrication in compositional and geometric diversity. In this study, we synthesized several hundreds of nanometer long and ˜4 nm thick CsPbBr 3 nanowires (NWs). They were then integrated into electrospun polyurethane (PU) fibers to examine the polarization behavior of the composite fiber assembly. Aligned electrospun fibers containing CsPbBr 3 NWs showed a remarkable increase in the degree of polarization from 0.17-0.30. This combination of NWs and PU fibers provides a promising composite material for various applications such as optoelectronic devices and solar cells.

A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold

PubMed Central

Kalaitzidou, Kyriaki; Fukushima, Hiroyuki; Drzal, Lawrence T.

2010-01-01

Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape), intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment.

Melt dispersion and electrospinning of non-functionalized multiwalled carbon nanotubes in thermoplastic polyurethane.

PubMed

Hunley, Matthew T; Pötschke, Petra; Long, Timothy E

2009-12-16

Nanoscale fibers with embedded, aligned, and percolated non-functionalized multiwalled carbon nanotubes (MWCNTs) were fabricated through electrospinning dispersions based on melt-compounded thermoplastic polyurethane/MWCNT nanocomposite, with up to 10 wt.-% MWCNTs. Transmission electron microscopy indicated that the nanotubes were highly oriented and percolated throughout the fibers, even at high MWCNT concentrations. The coupling of efficient melt compounding with electrospinning eliminated the need for intensive surface functionalization or sonication of the MWCNTs, and the high aspect ratio as well as the electrical and mechanical properties of the nanotubes were retained. This method provides a more efficient technique to generate one-dimensional nanofibers with aligned MWCNTs. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using aligned poly(3-hexylthiophene)/poly(methyl methacrylate) blend fibers to detect volatile organic compounds

NASA Astrophysics Data System (ADS)

Chan, Shun-Hsiang; Lin, Tz-Feng; Wu, Ming-Chung; Chen, Shih-Hsuan; Su, Wei-Fang; Lai, Chao-Sung

2018-04-01

In this study, we developed a novel sensing material fabricated using a poly(3-hexylthiophene) (P3HT)/poly(methyl methacrylate) (PMMA) blend fiber on a glass substrate. The sensing materials can easily be used for sensing toluene vapor detected from extinction spectral changes. The extinction spectra variation is noted from the absorption of volatile organic compounds in a highly specific surface area of fibrous coating. An electrospinning technique is applied to generate a nonwoven structure and uniaxial orientation by fibrous coating. The response of the uniaxially orientated fibrous film is even improved at several toluene vapor concentrations. The best detection limit of this well-aligned fibrous film is up to 200 ppm for toluene vapor.

A three-dimensional collagen-fiber network model of the extracellular matrix for the simulation of the mechanical behaviors and micro structures.

PubMed

Dong, Shoubin; Huang, Zetao; Tang, Liqun; Zhang, Xiaoyang; Zhang, Yongrou; Jiang, Yi

2017-07-01

The extracellular matrix (ECM) provides structural and biochemical support to cells and tissues, which is a critical factor for modulating cell dynamic behavior and intercellular communication. In order to further understand the mechanisms of the interactive relationship between cell and the ECM, we developed a three-dimensional (3D) collagen-fiber network model to simulate the micro structure and mechanical behaviors of the ECM and studied the stress-strain relationship as well as the deformation of the ECM under tension. In the model, the collagen-fiber network consists of abundant random distributed collagen fibers and some crosslinks, in which each fiber is modeled as an elastic beam and a crosslink is modeled as a linear spring with tensile limit, it means crosslinks will fail while the tensile forces exceed the limit of spring. With the given parameters of the beam and the spring, the simulated tensile stress-strain relation of the ECM highly matches the experimental results including damaged and failed behaviors. Moreover, by applying the maximal inscribed sphere method, we measured the size distribution of pores in the fiber network and learned the variation of the distribution with deformation. We also defined the alignment of the collagen-fibers to depict the orientation of fibers in the ECM quantitatively. By the study of changes of the alignment and the damaged crosslinks against the tensile strain, this paper reveals the comprehensive mechanisms of four stages of 'toe', 'linear', 'damage' and 'failure' in the tensile stress-strain relation of the ECM which can provide further insight in the study of cell-ECM interaction.

Material properties of CorCap passive cardiac support device.

PubMed

Chitsaz, Sam; Wenk, Jonathan F; Ge, Liang; Wisneski, Andrew; Mookhoek, Aart; Ratcliffe, Mark B; Guccione, Julius M; Tseng, Elaine E

2013-01-01

Myocardial function deteriorates during ventricular remodeling in patients with congestive heart failure (HF). Ventricular restraint therapy using a cardiac support device (CSD) is designed to reduce the amount of stress inside the dilated ventricles, which in turn halts remodeling. However, as an open mesh surrounding the heart, it is unknown what the mechanical properties of the CSD are in different fiber orientations. Composite specimens of CorCap (Acorn Cardiovascular, Inc, St. Paul, MN) CSD fabric and silicone were constructed in different fiber orientations and tested on a custom-built biaxial stretcher. Silicone controls were made and stretched to detect the parameters of the matrix. CSD coefficients were calculated using the composite and silicone matrix stress-strain data. Stiffness in different fiber orientations was determined. Silicone specimens exerted a linear behavior, with stiffness of 2.57 MPa. For the composites with 1 fiber set aligned with respect to the stretch axes, stiffness in the direction of the aligned fiber set was higher than that in the cross-fiber direction (14.39 MPa versus 5.66 MPa), indicating greater compliance in the cross-fiber direction. When the orientation of the fiber sets in the composite were matched to the expected clinical orientation of the implanted CorCap, the stiffness in the circumferential axis (with respect to the heart) was greater than in the longitudinal axis (10.55 MPa versus 9.70 MPa). The mechanical properties of the CorCap demonstrate directionality with greater stiffness circumferentially than longitudinally. Implantation of the CorCap clinically should take into account the directionality of the biomechanics to optimize ventricular restraint. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Fabrication and preliminary study of a biomimetic tri-layer tubular graft based on fibers and fiber yarns for vascular tissue engineering.

PubMed

Wu, Tong; Zhang, Jialing; Wang, Yuanfei; Li, Dandan; Sun, Binbin; El-Hamshary, Hany; Yin, Meng; Mo, Xiumei

2018-01-01

Designing a biomimetic and functional tissue-engineered vascular graft has been urgently needed for repairing and regenerating defected vascular tissues. Utilizing a multi-layered vascular scaffold is commonly considered an effective way, because multi-layered scaffolds can easily simulate the structure and function of natural blood vessels. Herein, we developed a novel tri-layer tubular graft consisted of Poly(L-lactide-co-caprolactone)/collagen (PLCL/COL) fibers and Poly(lactide-co-glycolide)/silk fibroin (PLGA/SF) yarns via a three-step electrospinning method. The tri-layer vascular graft consisted of PLCL/COL aligned fibers in inner layer, PLGA/SF yarns in middle layer, and PLCL/COL random fibers in outer layer. Each layer possessed tensile mechanical strength and elongation, and the entire tubular structure provided tensile and compressive supports. Furthermore, the human umbilical vein endothelial cells (HUVECs) and smooth muscle cells (SMCs) proliferated well on the materials. Fluorescence staining images demonstrated that the axially aligned PLCL/COL fibers prearranged endothelium morphology in lumen and the circumferential oriented PLGA/SF yarns regulated SMCs organization along the single yarns. The outside PLCL/COL random fibers performed as the fixed layer to hold the entire tubular structure. The in vivo results showed that the tri-layer vascular graft supported cell infiltration, scaffold biodegradation and abundant collagen production after subcutaneous implantation for 10weeks, revealing the optimal biocompatibility and tissue regenerative capability of the tri-layer graft. Therefore, the specially designed tri-layer vascular graft will be beneficial to vascular reconstruction. Copyright © 2017. Published by Elsevier B.V.

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

Comparison of self-written waveguide techniques and bulk index matching for low-loss polymer waveguide interconnects

NASA Astrophysics Data System (ADS)

Burrell, Derek; Middlebrook, Christopher

2016-03-01

Polymer waveguides (PWGs) are used within photonic interconnects as inexpensive and versatile substitutes for traditional optical fibers. The PWGs are typically aligned to silica-based optical fibers for coupling. An epoxide elastomer is then applied and cured at the interface for index matching and rigid attachment. Self-written waveguides (SWWs) are proposed as an alternative to further reduce connection insertion loss (IL) and alleviate marginal misalignment issues. Elastomer material is deposited after the initial alignment, and SWWs are formed by injecting ultraviolet (UV) light into the fiber or waveguide. The coupled UV light cures a channel between the two differing structures. A suitable cladding layer can be applied after development. Such factors as longitudinal gap distance, UV cure time, input power level, polymer material selection and choice of solvent affect the resulting SWWs. Experimental data are compared between purely index-matched samples and those with SWWs at the fiber-PWG interface. It is shown that < 1 dB IL per connection can be achieved by either method and results indicate lowest potential losses associated with a fine-tuned self-writing process. Successfully fabricated SWWs reduce overall processing time and enable an effectively continuous low-loss rigid interconnect.

Laser illumination of multiple capillaries that form a waveguide

DOEpatents

Dhadwal, Harbans S.; Quesada, Mark A.; Studier, F. William

1998-08-04

A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis.

Laser illumination of multiple capillaries that form a waveguide

DOEpatents

Dhadwal, H.S.; Quesada, M.A.; Studier, F.W.

1998-08-04

A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis. 35 figs.

Perturbation of cytosolic calcium by 2-aminoethoxydiphenyl borate and caffeine affects zebrafish myofibril alignment.

PubMed

Wu, Hsin-Ju; Fong, Tsorng-Harn; Chen, Shen-Liang; Wei, Jen-Cheng; Wang, I-Jong; Wen, Chi-Chung; Chang, Chao-Yuan; Chen, Xing-Guang; Chen, Wei-Yu; Chen, Hui-Min; Horng, Juin-Lin; Wang, Yun-Hsin; Chen, Yau-Hung

2015-03-01

The objective of the current study was to investigate the effects of Ca(2+) levels on myofibril alignment during zebrafish embryogenesis. To investigate how altered cytoplasmic Ca(2+) levels affect myofibril alignment, we exposed zebrafish embryos to 2-aminothoxyldiphenyl borate (2-APB; an inositol 1,4,5-trisphosphate receptor inhibitor that reduces cytosolic Ca(2+) levels) and caffeine (a ryanodine receptor activator that enhances cytosolic Ca(2+) levels). The results demonstrated that the most evident changes in zebrafish embryos treated with 2-APB were shorter body length, curved trunk and malformed somite boundary. In contrast, such malformed phenotypes were evident neither in untreated controls nor in caffeine-treated embryos. Subtle morphological changes, including changes in muscle fibers, F-actin and ultrastructures were easily observed by staining with specific monoclonal antibodies (F59 and α-laminin), fluorescent probes (phalloidin) and by transmission electron microscopy. Our data suggested that: (1) the exposure to 2-APB and/or caffeine led to myofibril misalignment; (2) 2-APB-treated embryos displayed split and short myofibril phenotypes, whereas muscle fibers from caffeine-treated embryos were twisted and wavy; and (3) zebrafish embryos co-exposed to 2-APB and caffeine resulted in normal myofibril alignment. In conclusion, we proposed that cytosolic Ca(2+) is important for myogenesis, particularly for myofibril alignment. Copyright © 2014 John Wiley & Sons, Ltd.

Zinc-mediated attenuation of hippocampal mossy fiber long-term potentiation induced by forskolin.

PubMed

Ando, Masaki; Oku, Naoto; Takeda, Atsushi

2010-11-01

The rise in presynaptic calcium induced by high-frequency stimulation activates the calcium-calmodulin-sensitive adenylyl cyclase (AC) 1 followed by the induction of long-term potentiation (LTP) at the hippocampal mossy fiber-CA3 synapse. Zinc is released with glutamate from mossy fiber terminals. However, the role of the zinc in mossy fiber LTP is controversial. In the present study, the mechanism of zinc-mediated attenuation of mossy fiber LTP was examined in that induced by forskolin, an AC activator. Mossy fiber LTP induced by tetanic stimulation (100 Hz for 1 s) was attenuated in the presence of 5 microM ZnCl(2), whereas that induced by forskolin under test stimulation (0.1 Hz) was not attenuated. Forskolin-induced mossy fiber LTP was attenuated by perfusion with 100 microM ZnCl(2) prior to the induction. However, the zinc (100 microM) pre-perfusion did not attenuate mossy fiber LTP induced by Sp-cAMPS, an activator of protein kinase A, under test stimulation. Zinc is necessary to be taken up into mossy fiber boutons for effectively inhibiting AC activity. In hippocampal slices labeled with ZnAF-2 DA, a membrane-permeable zinc indicator, intracellular ZnAF-2 signal was increased during tetanic stimulation in the presence of 5 microM ZnCl(2), but not under test stimulation. Intracellular ZnAF-2 signal was increased under test stimulation in the presence of 100 microM ZnCl(2). These results suggest that zinc taken up into mossy fibers attenuates forskolin-induced mossy fiber LTP via inhibition of AC activity. The significance of endogenous zinc uptake by mossy fibers is discussed focused on tetanus-induced mossy fiber LTP. Copyright 2010 Elsevier Ltd. All rights reserved.

The deterministic optical alignment of the HERMES spectrograph

NASA Astrophysics Data System (ADS)

Gers, Luke; Staszak, Nicholas

2014-07-01

The High Efficiency and Resolution Multi Element Spectrograph (HERMES) is a four channel, VPH-grating spectrograph fed by two 400 fiber slit assemblies whose construction and commissioning has now been completed at the Anglo Australian Telescope (AAT). The size, weight, complexity, and scheduling constraints of the system necessitated that a fully integrated, deterministic, opto-mechanical alignment system be designed into the spectrograph before it was manufactured. This paper presents the principles about which the system was assembled and aligned, including the equipment and the metrology methods employed to complete the spectrograph integration.

Optimization of GRIN lenses coupling system for twin-core fiber interconnection with single core fibers

NASA Astrophysics Data System (ADS)

Chen, Gongdai; Deng, Hongchang; Yuan, Libo

2018-07-01

We aim at a more compact, flexible, and simpler core-to-fiber coupling approach, optimal combinations of two graded refractive index (GRIN) lenses have been demonstrated for the interconnection between a twin-core single-mode fiber and two single-core single-mode fibers. The optimal two-lens combinations achieve an efficient core-to-fiber separating coupling and allow the fibers and lenses to coaxially assemble. Finally, axial deviations and transverse displacements of the components are discussed, and the latter increases the coupling loss more significantly. The gap length between the two lenses is designed to be fine-tuned to compensate for the transverse displacement, and the good linear compensation relationship contributes to the device manufacturing. This approach has potential applications in low coupling loss and low crosstalk devices without sophisticated alignment and adjustment, and enables the channel separating for multicore fibers.

AVIRIS foreoptics, fiber optics and on-board calibrator

NASA Technical Reports Server (NTRS)

Chrisp, Michael P.; Chrien, Thomas G.; Steimle, L.

1987-01-01

The foreoptics, fiber optic system and calibration source of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) are described. The foreoptics, based on a modified Kennedy scanner, is coupled by optical fibers to the four spectrometers. The optical fibers allow convenient positioning of the spectrometers in the limited space and enable simple compensation of the scanner's thermal defocus (at the -23 C operating temp) by active control of the fiber focal plane position. A challenging requirement for the fiber optic system was the transmission to the spectral range 1.85 to 2.45 microns at .45 numerical aperture. This was solved with custom fluoride glass fibers from Verre Fluore. The onboard calibration source is also coupled to the spectrometers by the fibers and provides two radiometric levels and a reference spectrum to check the spectrometers' alignment. Results of the performance of the assembled subsystems are presented.

An electromagnetically actuated fiber optic switch using magnetized ferromagnetic materials

NASA Astrophysics Data System (ADS)

Pandojirao-S, Praveen; Dhaubanjar, Naresh; Phuyal, Pratibha C.; Chiao, Mu; Chiao, J.-C.

2008-03-01

This paper presents the design, fabrication and testing of a fiber optic switch actuated electromagnetically. The ferromagnetic gel coated optical fiber is actuated using external electromagnetic fields. The ferromagnetic gel consists of ferromagnetic powders dispersed in epoxy. The fabrication utilizes a simple cost-effective coating setup. A direct fiberto-fiber alignment eliminates the need for complementary optical parts and the displacement of fiber switches the laser coupling. The magnetic characteristics of magnetized ferromagnetic materials are performed using alternating gradient magnetometer and the magnetic hysteresis curves are measured for different ferromagnetic materials including iron, cobalt, and nickel. Optical fiber switches with various fiber lengths are actuated and their static and dynamic responses for the same volume of ferromagnetic gel are summarized. The highest displacement is 1.345 mm with an input current of 260mA. In this paper, the performance of fiber switches with various coating materials is presented.

Effects of mold geometry on fiber orientation of powder injection molded metal matrix composites

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

Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Aslam, Muhammad, E-mail: klaira73@gmail.com; Altaf, Khurram, E-mail: khurram.altaf@petronas.com.my

2015-07-22

Fiber orientations in metal matrix composites have significant effect on improving tensile properties. Control of fiber orientations in metal injection molded metal composites is a difficult task. In this study, two mold cavities of dimensions 6x6x90 mm and 10x20x180 mm were used for comparison of fiber orientation in injection molded metal composites test parts. In both mold cavities, convergent and divergent flows were developed by modifying the sprue dimensions. Scanning electron microscope (SEM) was used to examine the fiber orientations within the test samples. The results showed highly aligned fiber in injection molded test bars developed from the convergent melt flow. Randommore » orientation of fibers was noted in the composites test bars produced from divergent melt flow.« less

Optical apparatus for laser scattering by objects having complex shapes

DOEpatents

Ellingson, William A.; Visher, Robert J.

2006-11-14

Apparatus for observing and measuring in realtime surface and subsurface characteristics of objects having complex shapes includes an optical fiber bundle having first and second opposed ends. The first end includes a linear array of fibers, where the ends of adjacent fibers are in contact and are aligned perpendicular to the surface of the object being studied. The second ends of some of the fibers are in the form of a polished ferrule forming a multi-fiber optical waveguide for receiving laser light. The second ends of the remaining fibers are formed into a linear array suitable for direct connection to a detector, such as a linear CMOS-based optical detector. The output data is analyzed using digital signal processing for the detection of anomalies such as cracks, voids, inclusions and other defects.

Coupling loss reducing for fiber Raman gas detection technology

NASA Astrophysics Data System (ADS)

Hu, Jialin; Jiang, Shubo; Zhang, Xiumei

2017-01-01

During the design of the photonic crystal fiber Raman gas detection device and taking the cost and practicability in to consideration, we choose to use a stainless steel tube as a connector for the connecting of the HCPCF and SMF to replace the fiber fusing splice. Basis on the measurement to reduce coupling loss, we calculated the optimum fiber gap for maximum light coupling and to reduce Fresnel loss. Using the stainless steel tube not only result in low loss but also benefit input of the sample gas and recycling of the fiber which is very expensive. By adjusting the central alignment of the stainless steel tube we can easily control the fiber deviation loss for specific type of SMF and HCPCF. The mode mismatch is also demonstrated.

Maximum-performance fiber-optic irradiation with nonimaging designs.

PubMed

Fang, Y; Feuermann, D; Gordon, J M

1997-10-01

A range of practical nonimaging designs for optical fiber applications is presented. Rays emerging from a fiber over a restricted angular range (small numerical aperture) are needed to illuminate a small near-field detector at maximum radiative efficiency. These designs range from pure reflector (all-mirror), to pure dielectric (refractive and based on total internal reflection) to lens-mirror combinations. Sample designs are shown for a specific infrared fiber-optic irradiation problem of practical interest. Optical performance is checked with computer three-dimensional ray tracing. Compared with conventional imaging solutions, nonimaging units offer considerable practical advantages in compactness and ease of alignment as well as noticeably superior radiative efficiency.

Polymer surfaces structured with random or aligned electrospun nanofibers to promote the adhesion of blood platelets.

PubMed

Wan, Ling-Shu; Xu, Zhi-Kang

2009-04-01

Fibrous membranes (nonwoven meshes) prepared via electrospinning technique have great potential in tissue engineering. This work is the first study on the behaviors of blood platelets at the nanostructured surface generated by electrospinning. Poly[acrylonitrile-co-(N-vinyl-2-pyrrolidone)] (PANCNVP) that shows excellent antiplatelet adhesion ability was directly electrospun onto its dense membrane surface. Polyacrylonitrile (PAN) samples were used as controls. The depth as well as the density of the nanofibers can be easily controlled. The results showed that the PANCNVP dense membrane certainly suppressed the activation and adhesion of platelets. However, whether the nanofibers and underlying membranes were composed of PAN or PANCNVP, the nanostructured surfaces promoted the activation, adhesion, and orientation of platelets. It was also found that, if the space between fibers was too large or the depth of fibers was too small, the nanostructured surface did not change the property of antiplatelet adhesion of PANCNVP. The promotion of activation and adhesion of platelets was obviously due to the presence of nanofibers, which induced the changes of surface topography and charge. Copyright 2008 Wiley Periodicals, Inc.

Tuning the shear viscosity of a dilute suspension using particle shapes that inhibit rotation

NASA Astrophysics Data System (ADS)

Sinai Borker, Neeraj; Stroock, Abraham; Koch, Donald

2017-11-01

We show that a suspension of slender, rigid-particles that attain an equilibrium orientation in a simple shear flow have a much smaller intrinsic viscosity relative to a suspension of tumbling particles with the same aspect ratio. An axisymmetric particle, such as a ring or a fiber, with certain cross-sections can attain an equilibrium orientation in a low Reynolds number simple shear flow without application of external forces (Singh et al., J. Fluid Mech., 2013; Bretherton, J. Fluid Mech., 1962 a). These particles align such that the slender dimension(s) of the particle is/are almost perpendicular to the velocity gradient direction of the simple shear flow and thus they have much smaller stresslets compared to the time averaged stresslet of a rotating slender particle. While slender fibers, also remain aligned in a similar state for a long time, the major contribution to the average stresslet occurs when the fiber is flipping. Using slender body theory and boundary element method calculations we demonstrate that particle alignment could significantly reduce the intrinsic viscosity of the suspension relative to a suspension of rotating particles. By choosing particle shapes that can be fabricated using manufacturing techniques such as photolithography or 3-D printing, our results open new pathways to control the rheological properties of a particle suspension by altering the shape of the particle. This research was funded by NSF Grant CBET-1435013.

SPHERE: SPherical Harmonic Elastic REgistration of HARDI Data

PubMed Central

Yap, Pew-Thian; Chen, Yasheng; An, Hongyu; Yang, Yang; Gilmore, John H.; Lin, Weili

2010-01-01

In contrast to the more common Diffusion Tensor Imaging (DTI), High Angular Resolution Diffusion Imaging (HARDI) allows superior delineation of angular microstructures of brain white matter, and makes possible multiple-fiber modeling of each voxel for better characterization of brain connectivity. However, the complex orientation information afforded by HARDI makes registration of HARDI images more complicated than scalar images. In particular, the question of how much orientation information is needed for satisfactory alignment has not been sufficiently addressed. Low order orientation representation is generally more robust than high order representation, although the latter provides more information for correct alignment of fiber pathways. However, high order representation, when naïvely utilized, might not necessarily be conducive to improving registration accuracy since similar structures with significant orientation differences prior to proper alignment might be mistakenly taken as non-matching structures. We present in this paper a HARDI registration algorithm, called SPherical Harmonic Elastic REgistration (SPHERE), which in a principled means hierarchically extracts orientation information from HARDI data for structural alignment. The image volumes are first registered using robust, relatively direction invariant features derived from the Orientation Distribution Function (ODF), and the alignment is then further refined using spherical harmonic (SH) representation with gradually increasing orders. This progression from non-directional, single-directional to multi-directional representation provides a systematic means of extracting directional information given by diffusion-weighted imaging. Coupled with a template-subject-consistent soft-correspondence-matching scheme, this approach allows robust and accurate alignment of HARDI data. Experimental results show marked increase in accuracy over a state-of-the-art DTI registration algorithm. PMID:21147231

Modeling the two-way feedback between contractility and matrix realignment reveals a nonlinear mode of cancer cell invasion

PubMed Central

Ahmadzadeh, Hossein; Webster, Marie R.; Behera, Reeti; Jimenez Valencia, Angela M.; Wirtz, Denis; Weeraratna, Ashani T.; Shenoy, Vivek B.

2017-01-01

Cancer cell invasion from primary tumors is mediated by a complex interplay between cellular adhesions, actomyosin-driven contractility, and the physical characteristics of the extracellular matrix (ECM). Here, we incorporate a mechanochemical free-energy–based approach to elucidate how the two-way feedback loop between cell contractility (induced by the activity of chemomechanical interactions such as Ca2+ and Rho signaling pathways) and matrix fiber realignment and strain stiffening enables the cells to polarize and develop contractile forces to break free from the tumor spheroids and invade into the ECM. Interestingly, through this computational model, we are able to identify a critical stiffness that is required by the matrix to break intercellular adhesions and initiate cell invasion. Also, by considering the kinetics of the cell movement, our model predicts a biphasic invasiveness with respect to the stiffness of the matrix. These predictions are validated by analyzing the invasion of melanoma cells in collagen matrices of varying concentration. Our model also predicts a positive correlation between the elongated morphology of the invading cells and the alignment of fibers in the matrix, suggesting that cell polarization is directly proportional to the stiffness and alignment of the matrix. In contrast, cells in nonfibrous matrices are found to be rounded and not polarized, underscoring the key role played by the nonlinear mechanics of fibrous matrices. Importantly, our model shows that mechanical principles mediated by the contractility of the cells and the nonlinearity of the ECM behavior play a crucial role in determining the phenotype of the cell invasion. PMID:28196892

A Fiber Optic Probe for Monitoring Protein Aggregation, Nucleation, and Crystallization

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Suh, Kwang I.; Arabshahi, Alireza; Wilson, William W.; Bray, Terry L.; DeLucas, Lawrence J.

1996-01-01

Protein crystals are experimentally grown in hanging drops in microgravity experiments on-board the Space Shuttle orbiter. The technique of dynamic light scattering (DLS) can be used to monitor crystal growth process in hanging droplets (approx. 30 (L)) in microgravity experiments, but elaborate instrumentation and optical alignment problems have made in-situ applications difficult. In this paper we demonstrate that such experiments are now feasible. We apply a newly developed fiber optic probe to various earth and space (micro- gravity) bound protein crystallization system configurations to test its capability. These include conventional batch (cuvette or capillary) systems, hanging drop method in a six-pack hanging drop vapor diffusion apparatus (HDVDA), a modified HDVDA for temperature- induced nucleation and aggregation studies, and a newly envisioned dynamically controlled vapor diffusion system (DCVDS) configuration. Our compact system exploits the principles of DLS and offers a fast (within a few seconds) means of quantitatively and non-invasively monitoring the various growth stages of protein crystallization. In addition to DLS capability, the probe can also be used for performing single-angle static light scattering measurements. It utilizes extremely low levels of laser power (approx. few (W)) without a need of having any optical alignment and vibration isolation. The compact probe is also equipped with a miniaturized microscope for visualization of macroscopic protein crystals. This new optical diagnostic system opens up enormous opportunity for exploring new ways to grow good quality crystals suitable for x-ray crystallographic analysis and may help develop a concrete scientific basis for understanding the process of crystallization.

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.

EMTA-NLA

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

2009-10-14

EMTA-NLA is a computer program for analyzing the nonlinear stiffness, strength, and thermo-elastic properties of discontinuous fiber composite materials. Discontinuous fiber composites are chopped-fiber reinforced polymer materials that are formed by injection molding or compression molding techniques. The fibers tend to align during forming as the composite flows and fills the mold. EMTA-NLA can read the fiber orientation data from the molding software, Autodesk Moldflow Plastics Insight, and calculate the local material properties for accurately analyzing the warpage, stiffness, and strength of the as-formed composite part using the commercial NLA software. Therefore, EMTA-NLA is a unique assembly of mathematical algorithmsmore » that provide a one-of-a-kind composites constitutive model that links these two powerful commercial software packages.« less

All fiber-coupled, long-term stable timing distribution for free-electron lasers with few-femtosecond jitter

PubMed Central

Şafak, K.; Xin, M.; Callahan, P. T.; Peng, M. Y.; Kärtner, F. X.

2015-01-01

We report recent progress made in a complete fiber-optic, high-precision, long-term stable timing distribution system for synchronization of next generation X-ray free-electron lasers. Timing jitter characterization of the master laser shows less than 170-as RMS integrated jitter for frequencies above 10 kHz, limited by the detection noise floor. Timing stabilization of a 3.5-km polarization-maintaining fiber link is successfully achieved with an RMS drift of 3.3 fs over 200 h of operation using all fiber-coupled elements. This all fiber-optic implementation will greatly reduce the complexity of optical alignment in timing distribution systems and improve the overall mechanical and timing stability of the system. PMID:26798814

Squid pen-inspired chitinous functional materials: Hierarchical chitin fibers by centrifugal jet-spinning and transparent chitin fiber-reinforced composite

NASA Astrophysics Data System (ADS)

Jeong, Seung-Hwan; Kim, Joong-Kwon; Lim, Young-Woo; Hwang, Hyun-Bin; Kwon, Hee-Young; Bae, Byeong-Soo; Jin, Jungho

2018-01-01

Here, inspired by the fibrous composite structure of a squid pen, we introduce hierarchical chitin fibers (herein, termed "Chiber") and their transparent composites and demonstrate the potential of these chitinous functional materials as a sustainable separation-membrane and reinforcing filler for composites. We employ a centrifugal jet-spinning process to fabricate Chiber with aligned chitin nanofibrillar architectures, for which we discuss the processing-morphology relationship. A nonwoven fiber-mat made of Chiber exhibits excellent adsorbing performance for a toxic ionic dye (Congo Red), and has a low coefficient of thermal expansion comparable to that of glass fibers. Finally, we demonstrate a squid pen-mimetic transparent composite using Chiber and investigate its optical property.

Automated fiber pigtailing machine

DOEpatents

Strand, O.T.; Lowry, M.E.

1999-01-05

The Automated Fiber Pigtailing Machine (AFPM) aligns and attaches optical fibers to optoelectronic (OE) devices such as laser diodes, photodiodes, and waveguide devices without operator intervention. The so-called pigtailing process is completed with sub-micron accuracies in less than 3 minutes. The AFPM operates unattended for one hour, is modular in design and is compatible with a mass production manufacturing environment. This machine can be used to build components which are used in military aircraft navigation systems, computer systems, communications systems and in the construction of diagnostics and experimental systems. 26 figs.

Overcoming low-alignment signal contrast induced alignment failure by alignment signal enhancement

NASA Astrophysics Data System (ADS)

Lee, Byeong Soo; Kim, Young Ha; Hwang, Hyunwoo; Lee, Jeongjin; Kong, Jeong Heung; Kang, Young Seog; Paarhuis, Bart; Kok, Haico; de Graaf, Roelof; Weichselbaum, Stefan; Droste, Richard; Mason, Christopher; Aarts, Igor; de Boeij, Wim P.

2016-03-01

Overlay is one of the key factors which enables optical lithography extension to 1X node DRAM manufacturing. It is natural that accurate wafer alignment is a prerequisite for good device overlay. However, alignment failures or misalignments are commonly observed in a fab. There are many factors which could induce alignment problems. Low alignment signal contrast is one of the main issues. Alignment signal contrast can be degraded by opaque stack materials or by alignment mark degradation due to processes like CMP. This issue can be compounded by mark sub-segmentation from design rules in combination with double or quadruple spacer process. Alignment signal contrast can be improved by applying new material or process optimization, which sometimes lead to the addition of another process-step with higher costs. If we can amplify the signal components containing the position information and reduce other unwanted signal and background contributions then we can improve alignment performance without process change. In this paper we use ASML's new alignment sensor (as was introduced and released on the NXT:1980Di) and sample wafers with special stacks which can induce poor alignment signal to demonstrate alignment and overlay improvement.

Modeling, Simulation, and Analysis of a Decoy State Enabled Quantum Key Distribution System

DTIC Science & Technology

2015-03-26

through the fiber , we assume Alice and Bob have correct basis alignment and timing control for reference frame correction and precise photon detection...optical components ( laser , polarization modulator, electronic variable optical attenuator, fixed optical attenuator, fiber channel, beamsplitter...generated by the laser in the CPG propagate through multiple optical components, each with a unique propagation delay before reaching the OPM. Timing

Clinical utility of LC3 and p62 immunohistochemistry in diagnosis of drug-induced autophagic vacuolar myopathies: a case-control study.

PubMed

Lee, Han S; Daniels, Brianne H; Salas, Eduardo; Bollen, Andrew W; Debnath, Jayanta; Margeta, Marta

2012-01-01

Some patients treated with chloroquine, hydroxychloroquine, or colchicine develop autophagic vacuolar myopathy, the diagnosis of which currently requires electron microscopy. The goal of the current study was to develop an immunohistochemical diagnostic marker for this pathologic entity. Microtubule-associated protein light chain 3 (LC3) has emerged as a robust marker of autophagosomes. LC3 binds p62/SQSTM1, an adapter protein that is selectively degraded via autophagy. In this study, we evaluated the utility of immunohistochemical stains for LC3 and p62 as diagnostic markers of drug-induced autophagic vacuolar myopathy. The staining was performed on archival muscle biopsy material, with subject assignment to normal control, drug-treated control, and autophagic myopathy groups based on history of drug use and morphologic criteria. In all drug-treated subjects, but not in normal controls, LC3 and p62 showed punctate staining characteristic of autophagosome buildup. In the autophagic myopathy subjects, puncta were coarser and tended to coalesce into linear structures aligned with the longitudinal axis of the fiber, often in the vicinity of vacuoles. The percentage of LC3- and p62-positive fibers was significantly higher in the autophagic myopathy group compared to either the normal control (p<0.001) or the drug-treated control group (p<0.05). With the diagnostic threshold set between 8% and 15% positive fibers (depending on the desired level of sensitivity and specificity), immunohistochemical staining for either LC3 or p62 could be used to identify subjects with autophagic vacuolar myopathy within the drug-treated subject group (p ≤ 0.001). Immunohistochemistry for LC3 and p62 can facilitate tissue-based diagnosis of drug-induced autophagic vacuolar myopathies. By limiting the need for electron microscopy (a time consuming and costly technique with high specificity, but low sensitivity), clinical use of these markers will improve the speed and accuracy of diagnosis, resulting in significantly improved clinical care.

Self-healable electrically conducting wires for wearable microelectronics.

PubMed

Sun, Hao; You, Xiao; Jiang, Yishu; Guan, Guozhen; Fang, Xin; Deng, Jue; Chen, Peining; Luo, Yongfeng; Peng, Huisheng

2014-09-01

Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next-generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high-performance conducting wires that can self-heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self-healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self-healable wire-shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self-healing. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Feasibility of Coupling Between a Single-Mode Elliptical-Core Fiber and a Single Mode Rib Waveguide Over Temperature. Ph.D. Thesis - Akron Univ., Aug. 1995

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.

1995-01-01

To determine the feasibility of coupling the output of an optical fiber to a rib waveguide in a temperature environment ranging from 20 C to 300 C, a theoretical calculation of the coupling efficiency between the two was investigated. This is a significant problem which needs to be addressed to determine whether an integrated optic device can function in a harsh temperature environment. Because the behavior of the integrated-optic device is polarization sensitive, a polarization-preserving optic fiber, via its elliptical core, was used to couple light with a known polarization into the device. To couple light energy efficiently from an optical fiber into a channel waveguide, the design of both components should provide for well-matched electric field profiles. The rib waveguide analyzed was the light input channel of an integrated-optic pressure sensor. Due to the complex geometry of the rib waveguide, there is no analytical solution to the wave equation for the guided modes. Approximation or numerical techniques must be utilized to determine the propagation constants and field patterns of the guide. In this study, three solution methods were used to determine the field profiles of both the fiber and guide: the effective-index method (EIM), Marcatili's approximation, and a Fourier method. These methods were utilized independently to calculate the electric field profile of a rib channel waveguide and elliptical fiber at two temperatures, 20 C and 300 C. These temperatures were chosen to represent a nominal and a high temperature that the device would experience. Using the electric field profile calculated from each method, the theoretical coupling efficiency between the single-mode optical fiber and rib waveguide was calculated using the overlap integral and results of the techniques compared. Initially, perfect alignment was assumed and the coupling efficiency calculated. Then, the coupling efficiency calculation was repeated for a range of transverse offsets at both temperatures. Results of the calculation indicate a high coupling efficiency can be achieved when the two components were properly aligned. The coupling efficiency was more sensitive to alignment offsets in the y direction than the x, due to the elliptical modal profile of both components. Changes in the coupling efficiency over temperature were found to be minimal.

CODEX-aligned dietary fiber definitions help to bridge the ‘fiber gap’

PubMed Central

2014-01-01

A comprehensive dietary fiber (DF) definition was adopted by the CODEX Alimentarius Commission (CAC) (1) to reflect the current state of knowledge about DF, (2) to recognize that all substances that behave like fiber regardless of how they are produced can be named as DF if they show physiological benefits, and (3) to promote international harmonization for food labeling and food composition tables. This review gives the history and evolution of the state of DF knowledge as looked at by refinements in DF methods and definitions subsequent to the launch of the DF hypothesis. The refinements parallel both interventional and epidemiological research leading to better understanding of the role of DF in contributing to the numerous physiological benefits imparted by all the various digestion resistant carbohydrates. A comparison of the CODEX definition (including its footnote that authorizes the inclusion of polymers with DP 3–9) and approved CODEX Type 1 methods with other existing definitions and methods will point out differences and emphasize the importance of adoption of CODEX-aligned definitions by all jurisdictions. Such harmonization enables comparison of nutrition research, recommendations, food composition tables and nutrition labels the world over. A case will be made that fibers are analogous to vitamins, in that they vary in structure, function and amount needed, but each when present in the right amount contributes to optimal health. Since the intake of DF is significantly below recommended levels throughout the world, the recognition that ‘all fibers fit’ is an important strategy in bridging the ‘fiber gap’ by enfranchising and encouraging greater intake of foods with inherent and added DF. Fortifying foods with added DF makes it easier to increase intakes while maintaining calories at recommended levels. PMID:24725724

CODEX-aligned dietary fiber definitions help to bridge the 'fiber gap'.

PubMed

Jones, Julie Miller

2014-04-12

A comprehensive dietary fiber (DF) definition was adopted by the CODEX Alimentarius Commission (CAC) (1) to reflect the current state of knowledge about DF, (2) to recognize that all substances that behave like fiber regardless of how they are produced can be named as DF if they show physiological benefits, and (3) to promote international harmonization for food labeling and food composition tables. This review gives the history and evolution of the state of DF knowledge as looked at by refinements in DF methods and definitions subsequent to the launch of the DF hypothesis. The refinements parallel both interventional and epidemiological research leading to better understanding of the role of DF in contributing to the numerous physiological benefits imparted by all the various digestion resistant carbohydrates. A comparison of the CODEX definition (including its footnote that authorizes the inclusion of polymers with DP 3-9) and approved CODEX Type 1 methods with other existing definitions and methods will point out differences and emphasize the importance of adoption of CODEX-aligned definitions by all jurisdictions. Such harmonization enables comparison of nutrition research, recommendations, food composition tables and nutrition labels the world over. A case will be made that fibers are analogous to vitamins, in that they vary in structure, function and amount needed, but each when present in the right amount contributes to optimal health. Since the intake of DF is significantly below recommended levels throughout the world, the recognition that 'all fibers fit' is an important strategy in bridging the 'fiber gap' by enfranchising and encouraging greater intake of foods with inherent and added DF. Fortifying foods with added DF makes it easier to increase intakes while maintaining calories at recommended levels.

A method to integrate patterned electrospun fibers with microfluidic systems to generate complex microenvironments for cell culture applications

PubMed Central

Wallin, Patric; Zandén, Carl; Carlberg, Björn; Hellström Erkenstam, Nina; Liu, Johan; Gold, Julie

2012-01-01

The properties of a cell’s microenvironment are one of the main driving forces in cellular fate processes and phenotype expression invivo. The ability to create controlled cell microenvironments invitro becomes increasingly important for studying or controlling phenotype expression in tissue engineering and drug discovery applications. This includes the capability to modify material surface properties within well-defined liquid environments in cell culture systems. One successful approach to mimic extra cellular matrix is with porous electrospun polymer fiber scaffolds, while microfluidic networks have been shown to efficiently generate spatially and temporally defined liquid microenvironments. Here, a method to integrate electrospun fibers with microfluidic networks was developed in order to form complex cell microenvironments with the capability to vary relevant parameters. Spatially defined regions of electrospun fibers of both aligned and random orientation were patterned on glass substrates that were irreversibly bonded to microfluidic networks produced in poly-dimethyl-siloxane. Concentration gradients obtained in the fiber containing channels were characterized experimentally and compared with values obtained by computational fluid dynamic simulations. Velocity and shear stress profiles, as well as vortex formation, were calculated to evaluate the influence of fiber pads on fluidic properties. The suitability of the system to support cell attachment and growth was demonstrated with a fibroblast cell line. The potential of the platform was further verified by a functional investigation of neural stem cell alignment in response to orientation of electrospun fibers versus a microfluidic generated chemoattractant gradient of stromal cell-derived factor 1 alpha. The described method is a competitive strategy to create complex microenvironments invitro that allow detailed studies on the interplay of topography, substrate surface properties, and soluble microenvironment on cellular fate processes. PMID:23781291

Composite strengthening. [of nonferrous, fiber reinforced alloys

NASA Technical Reports Server (NTRS)

Stoloff, N. S.

1976-01-01

The mechanical behavior of unidirectionally reinforced metals is examined, with particular attention to fabrication techniques for artificial composites and eutectic alloys and to principles of fiber reinforcement. The properties of artificial composites are discussed in terms of strength of fiber composites, strength of ribbon-reinforced composites, crack initiation, crack propagation, and creep behavior. The properties of eutectic composites are examined relative to tensile strength, compressive strength, fracture, high-temperature strength, and fatigue. In the case of artificial composites, parallelism of fibers, good bonding between fibers and matrix, and freedom of fibers from damage are all necessary to ensure superior performance. For many eutectic systems there are stringent boundary conditions relative to melt purity and superheat, atmosphere control, temperature gradient, and growth rate in order to provide near-perfect alignment of the reinforcements with a minimum of growth defects.

Very low-loss passive fiber-to-chip coupling with tapered fibers.

PubMed

Paatzsch, T; Smaglinski, I; Abraham, M; Bauer, H D; Hempelmann, U; Neumann, G; Mrozynski, G; Kerndlmaier, W

1997-07-20

A novel passive fiber-to-chip coupling based on the use of fiber tapers embedded in a guiding structure is proposed. By beam-propagation calculations it is verified that this new coupling method exhibits a very low insertion loss. Major advantages of the proposed method compared with butt coupling are demonstrated by simulation results: first, tolerance requirements for the fibers, e.g., diameter variations and core eccentricity, and for fabrication of the alignment structure are reduced by at least 1 order of magnitude. Second, coupling to waveguides of nearly arbitrary dimensions and refractive indices seems to be possible. Experimental results on thermal drawing of fiber tapers are presented and used as input data for the simulations. A concept for fabrication of the new coupling method with the Lithographic Galvanik Abformung (LIGA) technique is presented.

Method for optical and mechanically coupling optical fibers

DOEpatents

Toeppen, J.S.

1996-10-01

A method and apparatus are disclosed for splicing optical fibers. A fluorescing solder glass frit having a melting point lower than the melting point of first and second optical fibers is prepared. The solder glass frit is then attached to the end of the first optical fiber and/or the end of the second optical fiber. The ends of the optical fibers are aligned and placed in close proximity to each other. The solder glass frit is then heated to a temperature which is lower than the melting temperature of the first and second optical fibers, but which is high enough to melt the solder glass frit. A force is applied to the first and second optical fibers pushing the ends of the fibers towards each other. As the solder glass flit becomes molten, the layer of molten solder glass is compressed into a thin layer between the first and second optical fibers. The thin compressed layer of molten solder glass is allowed to cool such that the first and second optical fibers are bonded to each other by the hardened layer of solder glass. 6 figs.

Method for optical and mechanically coupling optical fibers

DOEpatents

Toeppen, John S.

1996-01-01

A method and apparatus for splicing optical fibers. A fluorescing solder glass frit having a melting point lower than the melting point of first and second optical fibers is prepared. The solder glass frit is then attached to the end of the first optical fiber and/or the end of the second optical fiber. The ends of the optical fibers are aligned and placed in close proximity to each other. The solder glass frit is then heated to a temperature which is lower than the melting temperature of the first and second optical fibers, but which is high enough to melt the solder glass frit. A force is applied to the first and second optical fibers pushing the ends of the fibers towards each other. As the solder glass flit becomes molten, the layer of molten solder glass is compressed into a thin layer between the first and second optical fibers. The thin compressed layer of molten solder glass is allowed to cool such that the first and second optical fibers are bonded to each other by the hardened layer of solder glass.

Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics.

PubMed

Ye, Dong; Ding, Yajiang; Duan, Yongqing; Su, Jiangtao; Yin, Zhouping; Huang, Yong An

2018-05-01

Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of ecofriendly polyethylene fiber from plastic bag waste

NASA Astrophysics Data System (ADS)

Soekoco, Asril S.; Noerati, Komalasari, Maya; Kurniawan, Hananto, Agus

2017-08-01

This paper presents the characterization of fiber morphology, fiber count and tenacity of polyethylene fiber which is made from plastic bag waste. Recycling plastic bag waste into textile fiber has not developed yet. Plastic bag waste was recycled into fiber by melt spinning using laboratory scale melt spinning equipment with single orifice nozzle and plunger system. The basic principle of melt spinning is by melting materials and then extruding it through small orifice of a spinning nozzle to form fibers. Diameter and cross section shape of Recycled polyethylene fiber were obtained by using scanning electron microscope (SEM) instrumentation. Linear density of the recycled fiber were analyzed by calculation using denier and dTex formulation and The mechanical strength of the fibers was measured in accordance with the ASTM D 3379-75 standard. The cross section of recycled fiber is circular taking the shape of orifice. Fiber count of 303.75 denier has 1.84 g/denier tenacity and fiber count of 32.52 has 3.44 g/denier tenacity. This conditions is affected by the growth of polymer chain alignment when take-up axial velocity become faster. Recycled polyethylene fiber has a great potential application in non-apparel textile.

A Hough Transform Global Probabilistic Approach to Multiple-Subject Diffusion MRI Tractography

DTIC Science & Technology

2010-04-01

distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT A global probabilistic fiber tracking approach based on the voting process provided by...umn.edu 2 ABSTRACT A global probabilistic fiber tracking approach based on the voting process provided by the Hough transform is introduced in...criteria for aligning curves and particularly tracts. In this work, we present a global probabilistic approach inspired by the voting procedure provided

Engineered plant biomass feedstock particles

DOEpatents

Dooley, James H [Federal Way, WA; Lanning, David N [Federal Way, WA; Broderick, Thomas F [Lake Forest Park, WA

2011-10-18

A novel class of flowable biomass feedstock particles with unusually large surface areas that can be manufactured in remarkably uniform sizes using low-energy comminution techniques. The feedstock particles are roughly parallelepiped in shape and characterized by a length dimension (L) aligned substantially with the grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. The particles exhibit a disrupted grain structure with prominent end and surface checks that greatly enhances their skeletal surface area as compared to their envelope surface area. The L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers. The W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers. The L.times.W dimensions define a pair of substantially parallel top surfaces characterized by some surface checking between longitudinally arrayed fibers. At least 80% of the particles pass through a 1/4 inch screen having a 6.3 mm nominal sieve opening but are retained by a No. 10 screen having a 2 mm nominal sieve opening. The feedstock particles are manufactured from a variety of plant biomass materials including wood, crop residues, plantation grasses, hemp, bagasse, and bamboo.

Optimization strategies for electrospun silk fibroin tissue engineering scaffolds

PubMed Central

Meinel, Anne J.; Kubow, Kristopher E.; Klotzsch, Enrico; Garcia-Fuentes, Marcos; Smith, Michael L.; Vogel, Viola; Merkle, Hans P.; Meinel, Lorenz

2013-01-01

As a contribution to the functionality of scaffolds in tissue engineering, here we report on advanced scaffold design through introduction and evaluation of topographical, mechanical and chemical cues. For scaffolding, we used silk fibroin (SF), a well established biomaterial. Biomimetic alignment of fibers was achieved as a function of the rotational speed of the cylindrical target during electrospinning of a SF solution blended with polyethylene oxide. Seeding fibrous SF scaffolds with human mesenchymal stem cells (hMSC) demonstrated that fiber alignment could guide hMSC morphology and orientation demonstrating the impact of scaffold topography on the engineering of oriented tissues. Beyond currently established methodologies to measure bulk properties, we assessed the mechanical properties of the fibers by conducting extension at breakage experiments on the level of single fibers. Chemical modification of the scaffolds was tested using donor/acceptor fluorophore labeled fibronectin. Fluorescence resonance energy transfer imaging allowed to assess the conformation of fibronectin when adsorbed on the SF scaffolds, and demonstrated an intermediate extension level of its subunits. Biological assays based on hMSC showed enhanced cellular adhesion and spreading as a result of fibronectin adsorbed on the scaffolds. Our studies demonstrate the versatility of SF as a biomaterial to engineer modified fibrous scaffolds and underscore the use of biofunctionally relevant analytical assays to optimize fibrous biomaterial scaffolds. PMID:19233463

Simultaneously precise frequency transfer and time synchronization using feed-forward compensation technique via 120 km fiber link.

PubMed

Chen, Xing; Lu, Jinlong; Cui, Yifan; Zhang, Jian; Lu, Xing; Tian, Xusheng; Ci, Cheng; Liu, Bo; Wu, Hong; Tang, Tingsong; Shi, Kebin; Zhang, Zhigang

2015-12-22

Precision time synchronization between two remote sites is desired in many applications such as global positioning satellite systems, long-baseline interferometry, coherent radar detection and fundamental physics constant measurements. The recently developed frequency dissemination technologies based on optical fiber link have improved the transfer instability to the level of 10(-19)/day at remote location. Therefore it is possible to keep clock oscillation at remote locations continuously corrected, or to reproduce a "virtual" clock on the remote location. However the initial alignment and the correction of 1 pps timing signal from time to time are still required, besides the highly stabilized clock frequency transfer between distant locations. Here we demonstrate a time synchronization based on an ultra-stable frequency transfer system via 120-km commercial fiber link by transferring an optical frequency comb. Both the phase noise compensation in frequency dissemination and temporal basis alignment in time synchronization were implemented by a feed-forward digital compensation (FFDC) technique. The fractional frequency instability was measured to be 6.18 × 10(-20) at 2000 s. The timing deviation of time synchronization was measured to be 0.6 ps in 1500 s. This technique also can be applied in multi-node fiber network topology.

Simultaneously precise frequency transfer and time synchronization using feed-forward compensation technique via 120 km fiber link

PubMed Central

Chen, Xing; Lu, Jinlong; Cui, Yifan; Zhang, Jian; Lu, Xing; Tian, Xusheng; Ci, Cheng; Liu, Bo; Wu, Hong; Tang, Tingsong; Shi, Kebin; Zhang, Zhigang

2015-01-01

Precision time synchronization between two remote sites is desired in many applications such as global positioning satellite systems, long-baseline interferometry, coherent radar detection and fundamental physics constant measurements. The recently developed frequency dissemination technologies based on optical fiber link have improved the transfer instability to the level of 10−19/day at remote location. Therefore it is possible to keep clock oscillation at remote locations continuously corrected, or to reproduce a “virtual” clock on the remote location. However the initial alignment and the correction of 1 pps timing signal from time to time are still required, besides the highly stabilized clock frequency transfer between distant locations. Here we demonstrate a time synchronization based on an ultra-stable frequency transfer system via 120-km commercial fiber link by transferring an optical frequency comb. Both the phase noise compensation in frequency dissemination and temporal basis alignment in time synchronization were implemented by a feed-forward digital compensation (FFDC) technique. The fractional frequency instability was measured to be 6.18 × 10−20 at 2000 s. The timing deviation of time synchronization was measured to be 0.6 ps in 1500 s. This technique also can be applied in multi-node fiber network topology. PMID:26691731

Ultrasonic and radiographic evaluation of advanced aerospace materials: Ceramic composites

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

1990-01-01

Two conventional nondestructive evaluation techniques were used to evaluate advanced ceramic composite materials. It was shown that neither ultrasonic C-scan nor radiographic imaging can individually provide sufficient data for an accurate nondestructive evaluation. Both ultrasonic C-scan and conventional radiographic imaging are required for preliminary evaluation of these complex systems. The material variations that were identified by these two techniques are porosity, delaminations, bond quality between laminae, fiber alignment, fiber registration, fiber parallelism, and processing density flaws. The degree of bonding between fiber and matrix cannot be determined by either of these methods. An alternative ultrasonic technique, angular power spectrum scanning (APSS) is recommended for quantification of this interfacial bond.

Tunable arbitrary unitary transformer based on multiple sections of multicore fibers with phase control.

PubMed

Zhou, Junhe; Wu, Jianjie; Hu, Qinsong

2018-02-05

In this paper, we propose a novel tunable unitary transformer, which can achieve arbitrary discrete unitary transforms. The unitary transformer is composed of multiple sections of multi-core fibers with closely aligned coupled cores. Phase shifters are inserted before and after the sections to control the phases of the waves in the cores. A simple algorithm is proposed to find the optimal phase setup for the phase shifters to realize the desired unitary transforms. The proposed device is fiber based and is particularly suitable for the mode division multiplexing systems. A tunable mode MUX/DEMUX for a three-mode fiber is designed based on the proposed structure.

Guided waves and defect scattering in metal matrix composite plates

NASA Technical Reports Server (NTRS)

Datta, Subhendu K.; Bratton, Robert L.; Shah, Arvind H.

1989-01-01

Guided Rayleigh-Lamb waves in a continuous graphite fiber reinforced magnesium plate has been studied. The interest in this material arises from its high thermal stability and because it provides high strength-to-weight ratio. Previous studies have shown that for wavelengths much larger than the fiber diameters and spacing, the material can be characterized as transversely isotropic with the symmetry axis aligned with the fiber direction. Because of the high longitudinal stiffness of the graphite fibers, the material shows strong anisotropy, with very high modulus in the fiber direction. For this reason, dispersion of guided waves is strongly influenced by the deviation of the direction of propagation from the symmetry axis. Results are given for propagation in different directions and for scattering of antiplane shear waves by surface-breaking cracks and delaminations.

Multimode interference tapered fiber refractive index sensors.

PubMed

Biazoli, Claudecir R; Silva, Susana; Franco, Marcos A R; Frazão, Orlando; Cordeiro, Cristiano M B

2012-08-20

Real-time monitoring of the fabrication process of tapering down a multimode-interference-based fiber structure is presented. The device is composed of a pure silica multimode fiber (MMF) with an initial 125 μm diameter spliced between two single-mode fibers. The process allows a thin MMF with adjustable parameters to obtain a high signal transmittance, arising from constructive interference among the guided modes at the output end of the MMF. Tapered structures with waist diameters as low as 55 μm were easily fabricated without the limitation of fragile splices or difficulty in controlling lateral fiber alignments. The sensing device is shown to be sensitive to the external environment, and a maximum sensitivity of 2946 nm/refractive index unit in the refractive index range of 1.42-1.43 was attained.

Realization of fiber optic displacement sensors

NASA Astrophysics Data System (ADS)

Guzowski, Bartlomiej; Lakomski, Mateusz

2018-03-01

Fiber optic sensors are very promising because of their inherent advantages such as very small size, hard environment tolerance and impact of electromagnetic fields. In this paper three different types of Intensity Fiber Optic Displacement Sensors (I-FODS) are presented. Three configurations of I-FODS were realized in two varieties. In the first one, the cleaved multimode optical fibers (MMF) were used to collect reflected light, while in the second variety the MMF ended with ball lenses were chosen. To ensure an accurate alignment of optical fibers in the sensor head the MTP C9730 optical fiber ferrules were used. In this paper the influence of distribution of transmitting and detecting optical fibers on sensitivity and linear range of operation of developed I-FODS were investigated. We have shown, that I-FODS with ball lenses receive average 10.5% more reflected power in comparison to the cleaved optical fibers and they increase linearity range of I-FODS by 33%. In this paper, an analysis of each type of the realized sensor and detailed discussion are given.

Mallow Fiber-Reinforced Epoxy Composites in Multilayered Armor for Personal Ballistic Protection

NASA Astrophysics Data System (ADS)

Nascimento, Lucio Fábio Cassiano; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Lima, Édio Pereira; da Luz, Fernanda Santos

2017-10-01

Lighter and less expensive polymer composites reinforced with natural fibers have been investigated as possible components of a multilayered armor system (MAS) for personal protection against high-velocity ammunition. Their ballistic performance was consistently found comparable with that of conventional Kevlar® synthetic aramid fiber. Among the numerous existing natural fibers with the potential for reinforcing polymer composites to replace Kevlar® in MAS, mallow fiber has not been fully investigated. Thus, the objective of this work is to evaluate the ballistic performance of epoxy composites reinforced with 30 vol.% of aligned mallow fibers as a second MAS layer backing a front ceramic plate. The results using high-velocity 7.62 ammunition show a similar indentation to a Kevlar® layer with the same thickness. An impedance matching calculation supports the similar ballistic performance of mallow fiber composite and Kevlar®. Reduced MAS costs associated with the mallow fiber composite are practical advantages over Kevlar®.

Novel Structural Health Monitoring Schemes for Glass-Fiber Composites using Nanofillers

DTIC Science & Technology

2014-03-31

laminate with aligned carbon black. EIT has also been used to locate damage in a carbon nanofiber (CNF) filled epoxy composite. Methods of improving EIT...mm in diameter as well as impact damage to a GFRP laminate with aligned carbon black. EIT has also been used to locate damage in a carbon nanofiber...field applications, particularly ballistic armor and helicopter blades. The ability to detect matrix damage in composite laminates is extremely

Directing collagen fibers using counter-rotating cone extrusion.

PubMed

Hoogenkamp, Henk R; Bakker, Gert-Jan; Wolf, Louis; Suurs, Patricia; Dunnewind, Bertus; Barbut, Shai; Friedl, Peter; van Kuppevelt, Toin H; Daamen, Willeke F

2015-01-01

The bio-inspired engineering of tissue equivalents should take into account anisotropic morphology and the mechanical properties of the extracellular matrix. This especially applies to collagen fibrils, which have various, but highly defined, orientations throughout tissues and organs. There are several methods available to control the alignment of soluble collagen monomers, but the options to direct native insoluble collagen fibers are limited. Here we apply a controlled counter-rotating cone extrusion technology to engineer tubular collagen constructs with defined anisotropy. Driven by diverging inner and outer cone rotation speeds, collagen fibrils from bovine skin were extruded and precipitated onto mandrels as tubes with oriented fibers and bundles, as examined by second harmonic generation microscopy and quantitative image analysis. A clear correlation was found whereby the direction and extent of collagen fiber alignment during extrusion were a function of the shear forces caused by a combination of the cone rotation and flow direction. A gradual change in the fiber direction, spanning +50 to -40°, was observed throughout the sections of the sample, with an average decrease ranging from 2.3 to 2.6° every 10μm. By varying the cone speeds, the collagen constructs showed differences in elasticity and toughness, spanning 900-2000kPa and 19-35mJ, respectively. Rotational extrusion presents an enabling technology to create and control the (an)isotropic architecture of collagen constructs for application in tissue engineering and regenerative medicine. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanics of oriented electrospun nanofibrous scaffolds for annulus fibrosus tissue engineering.

PubMed

Nerurkar, Nandan L; Elliott, Dawn M; Mauck, Robert L

2007-08-01

Engineering a functional replacement for the annulus fibrosus (AF) of the intervertebral disc is contingent upon recapitulation of AF structure, composition, and mechanical properties. In this study, we propose a new paradigm for AF tissue engineering that focuses on the reconstitution of anatomic fiber architecture and uses constitutive modeling to evaluate construct function. A modified electrospinning technique was utilized to generate aligned nanofibrous polymer scaffolds for engineering the basic functional unit of the AF, a single lamella. Scaffolds were tested in uniaxial tension at multiple fiber orientations, demonstrating a nonlinear dependence of modulus on fiber angle that mimicked the nonlinearity and anisotropy of native AF. A homogenization model previously applied to native AF successfully described scaffold mechanical response, and parametric studies demonstrated that nonfibrillar matrix, along with fiber connectivity, are key contributors to tensile mechanics for engineered AF. We demonstrated that AF cells orient themselves along the aligned scaffolds and deposit matrix that contributes to construct mechanics under loading conditions relevant to the in vivo environment. The homogenization model was applied to cell-seeded constructs and provided quantitative measures for the evolution of matrix and interfibrillar interactions. Finally, the model demonstrated that at fiber angles of the AF (28 degrees -44 degrees ), engineered material behaved much like native tissue, suggesting that engineered constructs replicate the physiologic behavior of the single AF lamella. Constitutive modeling provides a powerful tool for analysis of engineered AF neo-tissue and native AF tissue alike, highlighting key mechanical design criteria for functional AF tissue engineering.

Fiber/collagen composites for ligament tissue engineering: influence of elastic moduli of sparse aligned fibers on mesenchymal stem cells.

PubMed

Thayer, Patrick S; Verbridge, Scott S; Dahlgren, Linda A; Kakar, Sanjeev; Guelcher, Scott A; Goldstein, Aaron S

2016-08-01

Electrospun microfibers are attractive for the engineering of oriented tissues because they present instructive topographic and mechanical cues to cells. However, high-density microfiber networks are too cell-impermeable for most tissue applications. Alternatively, the distribution of sparse microfibers within a three-dimensional hydrogel could present instructive cues to guide cell organization while not inhibiting cell behavior. In this study, thin (∼5 fibers thick) layers of aligned microfibers (0.7 μm) were embedded within collagen hydrogels containing mesenchymal stem cells (MSCs), cultured for up to 14 days, and assayed for expression of ligament markers and imaged for cell organization. These microfibers were generated through the electrospinning of polycaprolactone (PCL), poly(ester-urethane) (PEUR), or a 75/25 PEUR/PCL blend to produce microfiber networks with elastic moduli of 31, 15, and 5.6 MPa, respectively. MSCs in composites containing 5.6 MPa fibers exhibited increased expression of the ligament marker scleraxis and the contractile phenotype marker α-smooth muscle actin versus the stiffer fiber composites. Additionally, cells within the 5.6 MPa microfiber composites were more oriented compared to cells within the 15 and 31 MPa microfiber composites. Together, these data indicate that the mechanical properties of microfiber/collagen composites can be tuned for the engineering of ligament and other target tissues. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1894-1901, 2016. © 2016 Wiley Periodicals, Inc.

Zero-gravity growth of a sodium chloride-lithium fluoride eutectic mixture

NASA Technical Reports Server (NTRS)

Yue, A. S.; Yeh, C. W.; Yue, B. K.

1982-01-01

Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on Earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convective current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and Earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.

An Advanced Electrospinning Method of Fabricating Nanofibrous Patterned Architectures with Controlled Deposition and Desired Alignment

NASA Astrophysics Data System (ADS)

Rasel, Sheikh Md

We introduce a versatile advanced method of electrospinning for fabricating various kinds of nanofibrous patterns along with desired alignment, controlled amount of deposition and locally variable density into the architectures. In this method, we employed multiple electrodes whose potentials have been altered in milliseconds with the help of microprocessor based control system. Therefore, key success of this method was that the electrical field as well as charge carrying fibers could be switched shortly from one electrode's location to another, as a result, electrospun fibers could be deposited on the designated areas with desired alignment. A wide range of nanofibrous patterned architectures were constructed using proper arrangement of multiple electrodes. By controlling the concurrent activation time of two adjacent electrodes, we demonstrated that amount of fibers going into the pattern can be adjusted and desired alignment in electrospun fibers can be obtained. We also revealed that the deposition density of electrospun fibers in different areas of patterned architectures can be varied. We showed that by controlling the deposition time between two adjacent electrodes, a number of functionally graded patterns can be generated with uniaxial alignment. We also demonstrated that this handy method was capable of producing random, aligned, and multidirectional nanofibrous mats by engaging a number of electrodes and switching them in desired patterns. A comprehensive study using finite element method was carried out to understand the effects of electrical field. Simulation results revealed that electrical field strength alters shortly based on electrode control switch patterns. Nanofibrous polyvinyl alcohol (PVA) scaffolds and its composite reinforced with wollastonite and wood flour were fabricated using rotating drum electrospinning technique. Morphological, mechanical, and thermal, properties were characterized on PVA/wollastonite and PVA/wood flour nanocomposites containing 0, 5, 10, and 20 wt % of fillers. Morphological analyses carried out by digital optical microscope, scanning electron microscopy, x-ray computed tomography, and Fourier transform infrared spectroscopy, confirmed the presence and well dispersion of fillers in the composites. In addition, improvement of mechanical properties with increased filler content further emphasized the adhesion between matrix and reinforcement. PVA with 20 wt % wollastonite composite exhibited the highest tensile strength (11.99 MPa) and tensile module (198 MPa) as compared to pure PVA (3.92 MPa and 83 MPa, respectively). Moreover, the thermal tests demonstrated that there is no major deviation in the thermal stability due to the addition of wollastonite in PVA scaffolds. Almost similar trend was observed in PVA/wood flour nanocomposites where tensile strength improved by 228 % for 20 wt % of reinforcement. The PVA/wollastonite and PVA/wood flour fibrous nanocomposite which poses higher mechanical properties might be potentially suitable for many advanced applications such as filtration, tissue engineering, and food processing. We believe this study will contribute to further scientific understanding of the patterning mechanism of electrospun nanofibers and to allow for variety of design of specific patterned nanofibrous architectures with desired functional properties. Therefore, this improved scheme of electrospinning can have significant impact in a broad range of applications including tissue engineering scaffolds, filtrations, and nanoelectronics.

Cyclic stretch-induced stress fiber dynamics - Dependence on strain rate, Rho-kinase and MLCK

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

Lee, Chin-Fu; Haase, Candice; Deguchi, Shinji

2010-10-22

Research highlights: {yields} Cyclic stretch induces stress fiber disassembly, reassembly and fusion perpendicular to the direction of stretch. {yields} Stress fiber disassembly and reorientation were not induced at low stretch frequency. {yields} Stretch caused actin fiber formation parallel to stretch in distinct locations in cells treated with Rho-kinase and MLCK inhibitors. -- Abstract: Stress fiber realignment is an important adaptive response to cyclic stretch for nonmuscle cells, but the mechanism by which such reorganization occurs is not known. By analyzing stress fiber dynamics using live cell microscopy, we revealed that stress fiber reorientation perpendicular to the direction of cyclic uniaxialmore » stretching at 1 Hz did not involve disassembly of the stress fiber distal ends located at focal adhesion sites. Instead, these distal ends were often used to assemble new stress fibers oriented progressively further away from the direction of stretch. Stress fiber disassembly and reorientation were not induced when the frequency of stretch was decreased to 0.01 Hz, however. Treatment with the Rho-kinase inhibitor (Y27632) reduced stress fibers to thin fibers located in the cell periphery which bundled together to form thick fibers oriented parallel to the direction of stretching at 1 Hz. In contrast, these thin fibers remained diffuse in cells subjected to stretch at 0.01 Hz. Cyclic stretch at 1 Hz also induced actin fiber formation parallel to the direction of stretch in cells treated with the myosin light chain kinase (MLCK) inhibitor ML-7, but these fibers were located centrally rather than peripherally. These results shed new light on the mechanism by which stress fibers reorient in response to cyclic stretch in different regions of the actin cytoskeleton.« less

Weak reversible cross links may decrease the strength of aligned fiber bundles.

PubMed

Nabavi, S Soran; Hartmann, Markus A

2016-02-21

Reversible cross-linking is an effective strategy to specifically tailor the mechanical properties of polymeric materials that can be found in a variety of biological as well as man-made materials. Using a simple model in this paper the influence of weak, reversible cross-links on the mechanical properties of aligned fiber bundles is investigated. Special emphasis in this analysis is put on the strength of the investigated structures. Using Monte Carlo methods two topologies of cross-links exceeding the strength of the covalent backbone are studied. Most surprisingly only two cross-links are sufficient to break the backbone of a multi chain system, resulting in a reduced strength of the material. The found effect crucially depends on the ratio of inter- to intra-chain cross-links and, thus, on the grafting density that determines this ratio.

Polymer optical fiber tapering using chemical solvent and polishing

NASA Astrophysics Data System (ADS)

Supian, L. S.; Syuhaimi Ab-Rahman, Mohd; Arsad, Norhana

2017-11-01

A method for developing polymer optical fiber (POF) directional coupler is introduced where the initial procedure includes using chemical solvent to remove the cladding, and bare out the core in order to align the unclad center of the fiber with other similar fiber to develop a coupler. The process is safe, simple, inexpensive and require low operation skill. The etched fiber offers improvement to the performance of various POF devices, i.e, couplers and sensors. Instead of relying only on silica or glass fiber, POF now can be used as an alternative to improve the network performance in short distance communication system. The measurement parameters laid out offer great outcomes. However, the couplers intended to be developed is yet to be realized, where deeper research and various experiments are needed in order to develop a simple but optimum performance coupler that can be used for various applications.

Bend-insensitive distributed sensing in singlemode-multimode-singlemode optical fiber structure by using Brillouin optical time-domain analysis.

PubMed

Xu, Pengbai; Dong, Yongkang; Zhang, Juwang; Zhou, Dengwang; Jiang, Taofei; Xu, Jinlong; Zhang, Hongying; Zhu, Tao; Lu, Zhiwei; Chen, Liang; Bao, Xiaoyi

2015-08-24

We propose a bend-insensitive distributed Brillouin optical fiber sensing by using a singlemode-multimode-singlemode optical fiber structure for the first time to the best of our knowledge. The sensing fiber is a graded-index multimode fiber (GI-MMF) sandwiched by two standard single-mode fibers (SMFs) with central-alignment splicing at the interface between GI-MMF and SMF to excite the fundamental mode in GI-MMF. The sensing system can resist a minimal bend radius of 1.25mm while maintain the measurement performance, with which the measured coefficients of strain and temperature are 421.6MHz/% and 0.826MHz/°C, respectively. We also demonstrate that the higher-order modes excited in GI-MMF can be easily influenced by bending, so that exciting the fundamental mode is essential for bend-insensitive distributed sensing.

Shear wave propagation in anisotropic soft tissues and gels

PubMed Central

Namani, Ravi; Bayly, Philip V.

2013-01-01

The propagation of shear waves in soft tissue can be visualized by magnetic resonance elastography (MRE) [1] to characterize tissue mechanical properties. Dynamic deformation of brain tissue arising from shear wave propagation may underlie the pathology of blast-induced traumatic brain injury. White matter in the brain, like other biological materials, exhibits a transversely isotropic structure, due to the arrangement of parallel fibers. Appropriate mathematical models and well-characterized experimental systems are needed to understand wave propagation in these structures. In this paper we review the theory behind waves in anisotropic, soft materials, including small-amplitude waves superimposed on finite deformation of a nonlinear hyperelastic material. Some predictions of this theory are confirmed in experimental studies of a soft material with controlled anisotropy: magnetically-aligned fibrin gel. PMID:19963987

Influence of fiber packing structure on permeability

NASA Technical Reports Server (NTRS)

Cai, Zhong; Berdichevsky, Alexander L.

1993-01-01

The study on the permeability of an aligned fiber bundle is the key building block in modeling the permeability of advanced woven and braided preforms. Available results on the permeability of fiber bundles in the literature show that a substantial difference exists between numerical and analytical calculations on idealized fiber packing structures, such as square and hexagonal packing, and experimental measurements on practical fiber bundles. The present study focuses on the variation of the permeability of a fiber bundle under practical process conditions. Fiber bundles are considered as containing openings and fiber clusters within the bundle. Numerical simulations on the influence of various openings on the permeability were conducted. Idealized packing structures are used, but with introduced openings distributed in different patterns. Both longitudinal and transverse flow are considered. The results show that openings within the fiber bundle have substantial effect on the permeability. In the longitudinal flow case, the openings become the dominant flow path. In the transverse flow case, the fiber clusters reduce the gap sizes among fibers. Therefore the permeability is greatly influenced by these openings and clusters, respectively. In addition to the porosity or fiber volume fraction, which is commonly used in the permeability expression, another fiber bundle status parameter, the ultimate fiber volume fraction, is introduced to capture the disturbance within a fiber bundle.

Fibrous nonlinear elasticity enables positive mechanical feedback between cells and ECMs

PubMed Central

Hall, Matthew S.; Alisafaei, Farid; Ban, Ehsan; Feng, Xinzeng; Hui, Chung-Yuen; Shenoy, Vivek B.; Wu, Mingming

2016-01-01

In native states, animal cells of many types are supported by a fibrous network that forms the main structural component of the ECM. Mechanical interactions between cells and the 3D ECM critically regulate cell function, including growth and migration. However, the physical mechanism that governs the cell interaction with fibrous 3D ECM is still not known. In this article, we present single-cell traction force measurements using breast tumor cells embedded within 3D collagen matrices. We recreate the breast tumor mechanical environment by controlling the microstructure and density of type I collagen matrices. Our results reveal a positive mechanical feedback loop: cells pulling on collagen locally align and stiffen the matrix, and stiffer matrices, in return, promote greater cell force generation and a stiffer cell body. Furthermore, cell force transmission distance increases with the degree of strain-induced fiber alignment and stiffening of the collagen matrices. These findings highlight the importance of the nonlinear elasticity of fibrous matrices in regulating cell–ECM interactions within a 3D context, and the cell force regulation principle that we uncover may contribute to the rapid mechanical tissue stiffening occurring in many diseases, including cancer and fibrosis. PMID:27872289

Microgroove fabrication with excimer laser ablation techniques for optical fiber array alignment purposes

NASA Astrophysics Data System (ADS)

Naessens, Kris; Van Hove, An; Coosemans, Thierry; Verstuyft, Steven; Vanwassenhove, Luc; Van Daele, Peter; Baets, Roel G.

2000-11-01

Currently, an ever increasing need for bandwidth, compactness and efficiency characterizes the world of interconnect and data communication. This tendency has already led to serial links being gradually replaced by parallel optical interconnect solutions. However, as the maximum capacity for the latter will be reached in the near future, new approaches are required to meet demand. One possible option is to switch to 2D parallel implementations of fiber arrays. In this paper we present the fabrication of a 2D connector for coupling a 4x8 array of plastic optical fibers to RCLED or VCSEL arrays. The connector consists primarily of dedicated PMMA plates in which arrays of 8 precisely dimensioned grooves at a pitch of 250 micrometers are introduced. The trenches are each 127 micrometers deep and their width is optimized to allow fixation of plastic optical fibers. We used excimer laser ablation for prototype fabrication of these alignment microstructures. In a later stage, the plates can be replicated using standard molding techniques. The laser ablation technique is extremely well suited for rapid prototyping and proves to be a versatile process yielding high accuracy dimensioning and repeatability of features in a wide diversity of materials. The dependency of the performance in terms of quality of the trenches (bottom roughness) and wall angle on various parameters (wavelength, energy density, pulse frequency and substrate material) is discussed. The fabricated polymer sheets with grooves are used to hold optical fibers by means of a UV-curable adhesive. In a final phase, the plates are stacked and glued in order to realize the 2D-connector of plastic optical fibers for short distance optical interconnects.

Electric-Field-Induced Alignment of Block Copolymer/Nanoparticle Blends

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

Liedel, Clemens; Schindler, Kerstin; Pavan, Mariela J.

External electric fi elds readily align birefringent block-copolymer mesophases. In this study the effect of gold nanoparticles on the electric-fi eld-induced alignment of a lamellae-forming polystyrene- block -poly(2-vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric-fi eldassisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such fi lms under benign experimental conditions.

Predicting the tensile strength of A UD basalt/ epoxy composite used for the confinement of concrete structures

NASA Astrophysics Data System (ADS)

Ciniņa, I.; Zīle, O.; Andersons, J.

2013-01-01

The principal aim of the present research was to predict the strength of UD basalt fiber/epoxy matrix composites in tension along the reinforcement direction. Tension tests on single basalt fibers were performed to determine the functional form of their strength distribution and to evaluate the parameters of the distribution. Also, microbond tests were carried out to assess the interfacial shear strength of the fibers and polymer matrix. UD composite specimens were produced and tested for the longitudinal tensile strength. The predicted strength of the composite was found to exceed the experimental values by ca. 20%, which can be explained by imperfections in the fiber alignment, impregnation, and adhesion in the composite specimens.

Electrically tunable zero dispersion wavelengths in photonic crystal fibers filled with a dual frequency addressable liquid crystal

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

Wahle, Markus, E-mail: markus.wahle@uni-paderborn.de; Kitzerow, Heinz-Siegfried

2015-11-16

We present a liquid crystal (LC) infiltrated photonic crystal fiber, which enables the electrical tuning of the position of zero dispersion wavelengths (ZDWs). A dual frequency addressable liquid crystal is aligned perpendicular on the inclusion walls of a photonic crystal fiber, which results in an escaped radial director field. The orientation of the LC is controlled by applying an external electric field. Due to the high index of the liquid crystal the fiber guides light by the photonic band gap effect. Multiple ZDWs exist in the visible and near infrared. The positions of the ZDWs can be either blue ormore » red shifted depending on the frequency of the applied voltage.« less

Dynamic light scattering homodyne probe

NASA Technical Reports Server (NTRS)

Meyer, William V. (Inventor); Cannell, David S. (Inventor); Smart, Anthony E. (Inventor)

2002-01-01

An optical probe for analyzing a sample illuminated by a laser includes an input optical fiber operably connectable to the laser where the input optical fiber has an entrance end and an exit end. The probe also includes a first beam splitter where the first beam splitter is adapted to transmit an alignment portion of a light beam from the input fiber exit end and to reflect a homodyning portion of the light beam from the input fiber. The probe also includes a lens between the input fiber exit end and the first beam splitter and a first and a second output optical fiber, each having an entrance end and an exit end, each exit end being operably connectable to respective optical detectors. The probe also includes a second beam splitter which is adapted to reflect at least a portion of the reflected homodyning portion into the output fiber entrance ends and to transmit light from the laser scattered by the sample into the entrance ends.

Mechanical properties of SiC fiber-reinforced reaction-bonded Si3N4 composites

NASA Technical Reports Server (NTRS)

Bhatt, R. T.

1985-01-01

The room temperature mechanical and physical properties of silicon carbide fiber reinforced reaction-bonded silicon nitride composites (SiC/RBSN) have been evaluated. The composites contained 23 and 40 volume fraction of aligned 140 micro m diameter chemically vapor deposited SiC fibers. Preliminary results for composite tensile and bend strengths and fracture strain indicate that the composites displayed excellent properties when compared with unreinforced RBSN of comparable porosity. Fiber volume fraction showed little influence on matrix first cracking strain but did influence the stressed required for matrix first cracking and for ultimate composite fracture strength. It is suggested that by reducing matrix porosity and by increasing the volume fraction of the large diameter SiC fiber, it should be possible to further improve the composite stress at which the matrix first cracks.

Practical method of waveguide-to-fiber connection: direct preparation of waveguide endface by cutting machine and reinforcement using ruby beads.

PubMed

Mekada, N; Seino, M; Kubota, Y; Nakajima, H

1990-12-01

We propose and demonstrate new practical methods of waveguide end fabrication and fiber attachment for Ti:LiNbO(3) waveguides. We fabricated waveguide endfaces with a cutting machine, which simplifies the manufacture of waveguide devices and provides a low excess loss of 0.3 dB or less. Our proposed fiber attachment method features fibers that protrude slightly from the reinforcement. It provides easy alignment, low excess loss (<0.1 dB), high strength (>600 gf), and high thermal stability (-10 to 60 degrees C). We also developed an easy way to reduce the backreflection from the joint without using anti-reflection coating. Instead, a tapered hemispherical end fiber and an angled waveguide endface are used. Backreflection is easily reduced to less than -30.

Natural Mallow Fiber-Reinforced Epoxy Composite for Ballistic Armor Against Class III-A Ammunition

NASA Astrophysics Data System (ADS)

Nascimento, Lucio Fabio Cassiano; Holanda, Luane Isquerdo Ferreira; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Gomes, Alaelson Vieira; Lima, Édio Pereira

2017-10-01

Epoxy matrix composites reinforced with up to 30 vol pct of continuous and aligned natural mallow fibers were for the first time ballistic tested as personal armor against class III-A 9 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared to those in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout and rupture as well as epoxy cracking. As compared to Kevlar™, the mallow fiber composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes the mallow fiber composites a promising material for personal ballistic protection.

Multispectral optical telescope alignment testing for a cryogenic space environment

NASA Astrophysics Data System (ADS)

Newswander, Trent; Hooser, Preston; Champagne, James

2016-09-01

Multispectral space telescopes with visible to long wave infrared spectral bands provide difficult alignment challenges. The visible channels require precision in alignment and stability to provide good image quality in short wavelengths. This is most often accomplished by choosing materials with near zero thermal expansion glass or ceramic mirrors metered with carbon fiber reinforced polymer (CFRP) that are designed to have a matching thermal expansion. The IR channels are less sensitive to alignment but they often require cryogenic cooling for improved sensitivity with the reduced radiometric background. Finding efficient solutions to this difficult problem of maintaining good visible image quality at cryogenic temperatures has been explored with the building and testing of a telescope simulator. The telescope simulator is an onaxis ZERODUR® mirror, CFRP metered set of optics. Testing has been completed to accurately measure telescope optical element alignment and mirror figure changes in a cryogenic space simulated environment. Measured alignment error and mirror figure error test results are reported with a discussion of their impact on system optical performance.

Contraction-induced injury to single permeabilized muscle fibers from normal and congenitally-clefted goat palates.

PubMed

Rader, Erik P; Cederna, Paul S; Weinzweig, Jeffrey; Panter, Kip E; Yu, Deborah; Buchman, Steven R; Larkin, Lisa M; Faulkner, John A

2007-03-01

Levator veli palatini muscles from normal palates of adult humans and goats are predominantly slow oxidative (type 1) fibers. However, 85% of levator veli palatini fibers from cleft palates of adult goats are physiologically fast (type 2). This fiber composition difference between cleft and normal palates may have implications in palatal function. For limb muscles, type 2 muscle fibers are more susceptible to lengthening contraction-induced injury than are type 1 fibers. We tested the hypothesis that, compared with single permeabilized levator veli palatini muscle fibers from normal palates of adult goats, those from cleft palates are more susceptible to lengthening contraction-induced injury. Congenital cleft palates were the result of chemically-induced decreased movement of the fetal head and tongue causing obstruction of palatal closure. Each muscle fiber was maximally activated and lengthened. Fiber type was determined by contractile properties and gel electrophoresis. Susceptibility to injury was assessed by measuring the decrease in maximum force following the lengthening contraction, expressed as a percentage of the initial force. Compared with fibers from normal palates that were all type 1 and had force deficits of 23 +/- 1%, fibers from cleft palates were all type 2 and sustained twofold greater deficits, 40 +/- 1% (p = .001). Levator veli palatini muscles from cleft palates of goats contain predominantly type 2 fibers that are highly susceptible to lengthening contraction-induced injury. This finding may have implications regarding palatal function and the incidence of velopharyngeal incompetence.

Evaporation-induced self-alignment and transfer of semiconductor nanowires by wrinkled elastomeric templates.

PubMed

Lee, Seung Goo; Kim, Haena; Choi, Hyun Ho; Bong, Hyojin; Park, Yeong Don; Lee, Wi Hyoung; Cho, Kilwon

2013-04-18

The evaporation-induced self-alignment of semiconductor nanowires is achieved using wrinkled elastomeric templates. The wrinkled templates, which have a surface topography that can be tuned via changes in the mechanical strain, are used as both a template to align the nanowires and as a stamp to transfer the aligned nanowires to target substrates. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determinants of Toxicity of Environmental Asbestos Fibers ...

EPA Pesticide Factsheets

Recent EPA-led studies have addressed the comparative toxicity and pathological mechanisms of environmental asbestos samples from Libby, Montana and other communities in the United States. Longer amosite fibers induce a 4-10 fold greater induction of pro-inflammatory mediators COX-2 and HO-1 than Libby fibers in human airway epithelial cells, as well as a number of other genes involved in cellular stress and toxicity. Similarly, equal mass doses of longer amosite fibers administered intratracheally to F344 rats cause greater pathological effects than Libby fibers, from 1 day to 2 years post-exposure. However, both intratracheal and inhalation studies show comparable effects of Libby fibers and shorter UICC amosite fibers. Dosimetry modeling and potency analysis studies are using these data to predict effects in humans. Libby fibers induce an acute phase response and systemic increases in selected markers of inflammation, and induce components of the NALP-3 inflammasome in the lung, while surface complexed iron inhibits these responses. Libby fibers alter genes involved in inflammation, immune regulation, and cell-cycle control, and also induce autoimmune responses in a rat model. Comparative toxicity studies showed that chrysotile fibers from Sumas Mountain, Washington caused greater lung interstitial fibrosis than Libby fibers, which were significantly more potent than tremolite fibers from El Dorado, California and actinolite “cleavage fragments” from

Vacuum-Compatible Wideband White Light and Laser Combiner Source System

NASA Technical Reports Server (NTRS)

Azizi, Alineza; Ryan, Daniel J.; Tang, Hong; Demers, Richard T.; Kadogawa, Hiroshi; An, Xin; Sun, George Y.

2010-01-01

For the Space Interferometry Mission (SIM) Spectrum Calibration Development Unit (SCDU) testbed, wideband white light is used to simulate starlight. The white light source mount requires extremely stable pointing accuracy (<3.2 microradians). To meet this and other needs, the laser light from a single-mode fiber was combined, through a beam splitter window with special coating from broadband wavelengths, with light from multimode fiber. Both lights were coupled to a photonic crystal fiber (PCF). In many optical systems, simulating a point star with broadband spectrum with stability of microradians for white light interferometry is a challenge. In this case, the cameras use the white light interference to balance two optical paths, and to maintain close tracking. In order to coarse align the optical paths, a laser light is sent into the system to allow tracking of fringes because a narrow band laser has a great range of interference. The design requirements forced the innovators to use a new type of optical fiber, and to take a large amount of care in aligning the input sources. The testbed required better than 1% throughput, or enough output power on the lowest spectrum to be detectable by the CCD camera (6 nW at camera). The system needed to be vacuum-compatible and to have the capability for combining a visible laser light at any time for calibration purposes. The red laser is a commercially produced 635-nm laser 5-mW diode, and the white light source is a commercially produced tungsten halogen lamp that gives a broad spectrum of about 525 to 800 nm full width at half maximum (FWHM), with about 1.4 mW of power at 630 nm. A custom-made beam splitter window with special coating for broadband wavelengths is used with the white light input via a 50-mm multi-mode fiber. The large mode area PCF is an LMA-8 made by Crystal Fibre (core diameter of 8.5 mm, mode field diameter of 6 mm, and numerical aperture at 625 nm of 0.083). Any science interferometer that needs a tracking laser fringe to assist in alignment can use this system.

Vibrating Optical Fibers to Make Laser Speckle Disappear

NASA Technical Reports Server (NTRS)

McGill, Matthew; Scott, V. Stanley

2005-01-01

In optical systems in which laser illumination is delivered via multimode optical fibers, laser speckle can be rendered incoherent by a simple but highly effective technique. The need to eliminate speckle arises because speckle can make it difficult to observe edges and other sharp features, thereby making it difficult to perform precision alignment of optical components. The basic ideas of the technique is to vibrate the optical fiber(s) to cause shifting of electromagnetic modes within the fiber(s) and consequent shifting of the speckle pattern in the light emerging from the fiber(s). If the frequency of vibration is high enough, a human eye cannot follow the shifting speckle pattern, so that instead of speckle, a human observer sees a smoothed pattern of light corresponding to a mixture of many electromagnetic modes. If necessary, the optical fiber(s) could be vibrated manually. However, in a typical laboratory situation, it would be more practical to attach a vibrating mechanism to the fiber(s) for routine use as part of the fiber-optic illuminator. In experiments, a commercially available small, gentle, quiet, variable- speed vibratory device was used in this way, with the result that the appearance of speckle was eliminated, as expected. Figures 1 and 2 illustrate the difference.

Regional mechanics determine collagen fiber structure in healing myocardial infarcts.

PubMed

Fomovsky, Gregory M; Rouillard, Andrew D; Holmes, Jeffrey W

2012-05-01

Following myocardial infarction, the mechanical properties of the healing infarct are an important determinant of heart function and the risk of progression to heart failure. In particular, mechanical anisotropy (having different mechanical properties in different directions) in the healing infarct can preserve pump function of the heart. Based on reports of different collagen structures and mechanical properties in various animal models, we hypothesized that differences in infarct size, shape, and/or location produce different patterns of mechanical stretch that guide evolving collagen fiber structure. We tested the effects of infarct shape and location using a combined experimental and computational approach. We studied mechanics and collagen fiber structure in cryoinfarcts in 53 Sprague-Dawley rats and found that regardless of shape or orientation, cryoinfarcts near the equator of the left ventricle stretched primarily in the circumferential direction and developed circumferentially aligned collagen, while infarcts at the apex stretched similarly in the circumferential and longitudinal directions and developed randomly oriented collagen. In a computational model of infarct healing, an effect of mechanical stretch on fibroblast and collagen alignment was required to reproduce the experimental results. We conclude that mechanical environment determines collagen fiber structure in healing myocardial infarcts. Our results suggest that emerging post-infarction therapies that alter regional mechanics will also alter infarct collagen structure, offering both potential risks and novel therapeutic opportunities. Copyright © 2012 Elsevier Ltd. All rights reserved.

Control of cell growth on 3D-printed cell culture platforms for tissue engineering.

PubMed

Tan, Zhikai; Liu, Tong; Zhong, Juchang; Yang, Yikun; Tan, Weihong

2017-12-01

Biocompatible tissue growth has excellent prospects for tissue engineering. These tissues are built over scaffolds, which can influence aspects such as cell adhesion, proliferation rate, morphology, and differentiation. However, the ideal 3D biological structure has not been developed yet. Here, we applied the electro-hydrodynamic jet (E-jet) 3D printing technology using poly-(lactic-co-glycolic acid, PLGA) solution to print varied culture platforms for engineered tissue structures. The effects of different parameters (electrical voltage, plotting speed, and needle sizes) on the outcome were investigated. We compared the biological compatibility of the 3D printed culture platforms with that of random fibers. Finally, we used the 3D-printed PLGA platforms to culture fibroblasts, the main cellular components of loose connective tissue. The results show that the E-jet printed platforms could guide and improve cell growth. These highly aligned fibers were able to support cellular alignment and proliferation. Cell angle was consistent with the direction of the fibers, and cells cultured on these fibers showed a much faster migration, potentially enhancing wound healing performance. Thus, the potential of this technology for 3D biological printing is large. This process can be used to grow biological scaffolds for the engineering of tissues. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3281-3292, 2017. © 2017 Wiley Periodicals, Inc.

Calculated coupling efficiency between an elliptical-core optical fiber and an optical waveguide over temperature

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.; Weisshaar, Andreas; Li, Jian; Beheim, Glenn

1995-01-01

To determine the feasibility of coupling the output of a single-mode optical fiber into a single-mode rib waveguide in a temperature varying environment, a theoretical calculation of the coupling efficiency between the two was investigated. Due to the complex geometry of the rib guide, there is no analytical solution to the wave equation for the guided modes, thus, approximation and/or numerical techniques must be utilized to determine the field patterns of the guide. In this study, three solution methods were used for both the fiber and guide fields; the effective-index method (EIM), Marcatili's approximation, and a Fourier method. These methods were utilized independently to calculate the electric field profile of each component at two temperatures, 20 C and 300 C, representing a nominal and high temperature. Using the electric field profile calculated from each method, the theoretical coupling efficiency between an elliptical-core optical fiber and a rib waveguide was calculated using the overlap integral and the results were compared. It was determined that a high coupling efficiency can be achieved when the two components are aligned. The coupling efficiency was more sensitive to alignment offsets in the y direction than the x, due to the elliptical modal field profile of both components. Changes in the coupling efficiency over temperature were found to be minimal.

Regional Mechanics Determine Collagen Fiber Structure in Healing Myocardial Infarcts

PubMed Central

Fomovsky, Gregory M.; Rouillard, Andrew D.; Holmes, Jeffrey W.

2012-01-01

Following myocardial infarction, the mechanical properties of the healing infarct are an important determinant of heart function and the risk of progression to heart failure. In particular, mechanical anisotropy (having different mechanical properties in different directions) in the healing infarct can preserve pump function of the heart. Based on reports of different collagen structures and mechanical properties in various animal models, we hypothesized that differences in infarct size, shape, and/or location produce different patterns of mechanical stretch that guide evolving collagen fiber structure. We tested the effects of infarct shape and location using a combined experimental and computational approach. We studied mechanics and collagen fiber structure in cryoinfarcts in 53 Sprague-Dawley rats and found that regardless of shape or orientation, cryoinfarcts near the equator of the left ventricle stretched primarily in the circumferential direction and developed circumferentially aligned collagen, while infarcts at the apex stretched similarly in the circumferential and longitudinal direction and developed randomly oriented collagen. In a computational model of infarct healing, an effect of mechanical stretch on fibroblast and collagen alignment was required to reproduce the experimental results. We conclude that mechanical environment determines collagen fiber structure in healing myocardial infarcts. Our results suggest that emerging post-infarction therapies that alter regional mechanics will also alter infarct collagen structure, offering both potential risks and novel therapeutic opportunities. PMID:22418281

Characterization, mechanical behavior and in vitro evaluation of a melt-drawn scaffold for esophageal tissue engineering.

PubMed

Tan, Yu Jun; Yeong, Wai Yee; Tan, Xipeng; An, Jia; Chian, Kerm Sin; Leong, Kah Fai

2016-04-01

Tubular esophageal scaffolds with fiber diameter ranging from 13.9±1.7μm to 65.7±6.2μm were fabricated from the highly elastic poly(l-lactide-co-ε-caprolactone) (PLC) via a melt-drawing method. The morphology, crystallinity, thermal and mechanical properties of the PLC fibers were investigated. They were highly aligned and have a uniform diameter. PLC is found to be semicrystalline consisting of α- and β- lactide (LA) crystals. The crystallinity increases up to 16.8% with increasing melt-drawing speeds due to strain-induced crystallization. Modulus and strength increases while ductility decreases with an increase in crystallinity of the PLC samples. Moisture will not degrade the overall tensile properties but affect its tangent modulus at the low strain. L929 cells are able to attach and proliferate on the scaffolds very well. The cells seeded on the scaffolds show normal morphology with >90% cell viability after 6 days of culture. These results demonstrate that the PLC fibrous scaffold has good potential for use in esophageal tissue engineering application. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparison of laboratory calibrations of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at the beginning and end of the first flight season

NASA Technical Reports Server (NTRS)

Vane, Gregg; Chrien, Thomas G.; Reimer, John H.; Green, Robert O.; Conel, James E.

1988-01-01

Spectral and radiometric calibrations of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) were performed in the laboratory in June and November, 1987, at the beginning and end of the first flight season. Those calibrations are described along with changes in instrument characteristics that occurred during the flight season as a result of factors such as detachment of the optical fibers to two of the four AVIRIS spectrometers, degradation in the optical alignment of the spectrometers due to thermally-induced and mechanical warpage, and breakage of a thermal blocking filter in one of the spectrometers. These factors caused loss of signal in three spectrometers, loss of spectral resolution in two spectrometers, and added uncertainty in the radiometry of AVIRIS. Results from in-flight assessment of the laboratory calibrations are presented. A discussion is presented of improvements made to the instrument since the end of the first flight season and plans for the future. Improvements include: (1) a new thermal control system for stabilizing spectrometer temperatures, (2) kinematic mounting of the spectrometers to the instrument rack, and (3) new epoxy for attaching the optical fibers inside their mounting tubes.

Power generation from base excitation of a Kevlar composite beam with ZnO nanowires

NASA Astrophysics Data System (ADS)

Malakooti, Mohammad H.; Hwang, Hyun-Sik; Sodano, Henry A.

2015-04-01

One-dimensional nanostructures such as nanowires, nanorods, and nanotubes with piezoelectric properties have gained interest in the fabrication of small scale power harvesting systems. However, the practical applications of the nanoscale materials in structures with true mechanical strengths have not yet been demonstrated. In this paper, piezoelectric ZnO nanowires are integrated into the fiber reinforced polymer composites serving as an active phase to convert the induced strain energy from ambient vibration into electrical energy. Arrays of ZnO nanowires are grown vertically aligned on aramid fibers through a low-cost hydrothermal process. The modified fabrics with ZnO nanowires whiskers are then placed between two carbon fabrics as the top and the bottom electrodes. Finally, vacuum resin transfer molding technique is utilized to fabricate these multiscale composites. The fabricated composites are subjected to a base excitation using a shaker to generate charge due to the direct piezoelectric effect of ZnO nanowires. Measuring the generated potential difference between the two electrodes showed the energy harvesting application of these multiscale composites in addition to their superior mechanical properties. These results propose a new generation of power harvesting systems with enhanced mechanical properties.

Characterizing fiber-reinforced composite structures using AC-impedance spectroscopy (AC-IS)

NASA Astrophysics Data System (ADS)

Woo, Leta Y.

Property enhancement in composites depends largely on the reinforcement. For fiber-reinforced composites, the distribution of fibers is crucial in determining the electrical and mechanical performance. Image analysis methods for characterization can be time-consuming and/or destructive. This work explores the capability of AC-impedance spectroscopy (AC-IS), an electrical measurement technique, to serve as a rapid, non-destructive tool for characterizing composite microstructure. The composite requirements include a filler that is electrically conducting or semi-conducting with higher conductivity than the matrix, and a high-impedance interface or coating between the filler and the matrix. To establish an AC-IS characterization method, cement-matrix composites with steel reinforcement were employed as both a technologically important and a model system to investigate how fibers affect the electrical response. Beginning with spherical particulates and then fibers, composites were examined using composite theory and an "intrinsic conductivity" approach. The intrinsic conductivity approach applies to composites with low volume fractions of fibers (i.e., in the dilute regime) and relates how the composite conductivity varies relative to the matrix as a function of volume fraction. A universal equivalent circuit model was created to understand the AC-IS response of composites based on the geometry and volume fraction of the filler. Deviation from predicted behavior was assessed using a developed f-function, which quantifies how fibers contribute to the overall electrical response of the composite. Using the f-function, an AC-IS method for investigating fiber dispersion was established to characterize alignment, settling/segregation, and aggregation. Alignment was investigated using measurements made in three directions. A point-probe technique characterized settling and/or large-scale inhomogeneous mixing in samples. Aggregation was quantified using a "dispersion factor" that compared theoretical with measured values and served as an upper limit for how well the fibers were dispersed. The AC-IS method was then extended to two different cement-matrix composite systems, low resistivity fresh-paste cement composites (confirmed by time domain reflectometry) and high resistivity cement composites, both of which required additional analysis to apply the AC-IS characterization method.

Continuum Damage Mechanics Models for the Analysis of Progressive Failure in Open-Hole Tension Laminates

NASA Technical Reports Server (NTRS)

Song, Kyonchan; Li, Yingyong; Rose, Cheryl A.

2011-01-01

The performance of a state-of-the-art continuum damage mechanics model for interlaminar damage, coupled with a cohesive zone model for delamination is examined for failure prediction of quasi-isotropic open-hole tension laminates. Limitations of continuum representations of intra-ply damage and the effect of mesh orientation on the analysis predictions are discussed. It is shown that accurate prediction of matrix crack paths and stress redistribution after cracking requires a mesh aligned with the fiber orientation. Based on these results, an aligned mesh is proposed for analysis of the open-hole tension specimens consisting of different meshes within the individual plies, such that the element edges are aligned with the ply fiber direction. The modeling approach is assessed by comparison of analysis predictions to experimental data for specimen configurations in which failure is dominated by complex interactions between matrix cracks and delaminations. It is shown that the different failure mechanisms observed in the tests are well predicted. In addition, the modeling approach is demonstrated to predict proper trends in the effect of scaling on strength and failure mechanisms of quasi-isotropic open-hole tension laminates.

Measurements of orientation, sedimentation, and dispersal of ramified particles in isotropic turbulence

NASA Astrophysics Data System (ADS)

Voth, Greg A.; Kramel, Stefan; Menon, Udayshankar K.; Koch, Donald L.

2017-11-01

We experimentally measure the sedimentation of non-spherical particles in isotropic turbulence. We obtain time-resolved 3D orientations of the particles along with the fluid velocity field around them in a vertical water tunnel. An active jet array with 40 individually controllable jets enables us to adjust the turbulence intensity and observe the transition from strongly aligned to randomized particle orientations. We focus on the orientation statistics of ramified particles formed from several slender arms, including fibers and particles with three arms in planar symmetry (triads), which allows us to study alignment of both fibers and disk-like particles. We can predict the turbulent intensity at which the transition from aligned to randomized particle orientations occurs using a non-dimensional settling factor given by the ratio of rotation timescale of the turbulence at the scale of the particle to the rotation timescale of a particles in quiescent flow due to inertial torques. A model of ramified particle motion based on slender body theory provides accurate predictions of the vertical and horizontal particle velocities relative to the turbulent fluid. Supported by Army Research Office Grant W911NF1510205.

Genome-wide analysis of gene expression of EMS-induced short fiber mutant Ligon lintless-y (liy) in cotton (Gossypium hirsutum L.)

USDA-ARS?s Scientific Manuscript database

The length of cotton fiber is an important agronomic trait characteristic that directly affects the quality of yarn and fabric. Cotton fiber mutants have been useful tools to study the molecular processes of fiber development. In this work we describe a chemically-induced short fiber mutant Ligon-li...

Compact all-fiber quartz-enhanced photoacoustic spectroscopy sensor with a 30.72 kHz quartz tuning fork and spatially resolved trace gas detection

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

Ma, Yufei, E-mail: mayufei@hit.edu.cn; Post-doctoral Mobile Station of Power Engineering and Engineering Thermophysics, Harbin Institute of Technology, Harbin 150001; He, Ying

An ultra compact all-fiber quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor using quartz tuning fork (QTF) with a low resonance frequency of 30.72 kHz was demonstrated. Such a sensor architecture has the advantages of easier optical alignment, lower insertion loss, lower cost, and more compact compared with a conventional QEPAS sensor using discrete optical components for laser delivery and coupling to the QTF. A fiber beam splitter and three QTFs were employed to perform multi-point detection and demonstrated the potential of spatially resolved measurements.

Counterfeit-resistant materials and a method and apparatus for authenticating materials

DOEpatents

Ramsey, J. Michael; Klatt, Leon N.

2001-01-01

Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters, the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided&

Counterfeit-resistant materials and a method and apparatus for authenticating materials

DOEpatents

Ramsey, J. Michael; Klatt, Leon N.

2000-01-01

Fluorescent dichroic fibers randomly incorporated within a media provide an improved method for authentication and counterfeiting protection. The dichroism is provided by an alignment of fluorescent molecules along the length of the fibers. The fluorescent fibers provide an authentication mechanism of varying levels of capability. The authentication signature depends on four parameters; the x,y position, the dichroism and the local environment. The availability of so many non-deterministic variables makes production of counterfeit articles (e.g., currency, credit cards, etc.) essentially impossible. Counterfeit-resistant articles, an apparatus for authenticating articles, and a process for forming counterfeit-resistant media are also provided.

Slab-coupled optical sensor fabrication using side-polished Panda fibers.

PubMed

King, Rex; Seng, Frederick; Stan, Nikola; Cuzner, Kevin; Josephson, Chad; Selfridge, Richard; Schultz, Stephen

2016-11-01

A new device structure used for slab-coupled optical sensor (SCOS) technology was developed to fabricate electric field sensors. This new device structure replaces the D-fiber used in traditional SCOS technology with a side-polished Panda fiber. Unlike the D-fiber SCOS, the Panda fiber SCOS is made from commercially available materials and is simpler to fabricate. The Panda SCOS interfaces easier with lab equipment and exhibits ∼3  dB less loss at link points than the D-fiber SCOS. The optical system for the D-fiber is bandwidth limited by a transimpedance amplifier (TIA) used to amplify to the electric signal. The Panda SCOS exhibits less loss than the D-fiber and, as a result, does not require as high a gain setting on the TIA, which results in an overall higher bandwidth range. Results show that the Panda sensor also achieves comparable sensitivity results to the D-fiber SCOS. Although the Panda SCOS is not as sensitive as other side-polished fiber electric field sensors, it can be fabricated much easier because the fabrication process does not require special alignment techniques, and it is made from commercially available materials.

Ferroelectric hybrid fibers to develop flexible sensors for shape sensing of smart textiles and soft condensed matter bodies

NASA Astrophysics Data System (ADS)

Sebastian, Tutu; Lusiola, Tony; Clemens, Frank

2017-04-01

Piezoelectric fibers are widely used in composites for actuator and sensor applications due to its ability to convert electrical pulses into mechanical vibrations and transform the returned mechanical vibrations back into electrical signal. They are beneficial for the fabrication of composites especially 1-3 composites, active fiber composites (unidirectional axially aligned PZT fibers sandwiched between interdigitated electrodes and embedded in a polymer matrix) etc, with potential applications in medical imaging, structural health monitoring, energy harvesting, vibration and noise control. However, due to the brittle nature of PZT fibers, maximum strain is limited to 0.2% and cannot be integrated into flexible sensor applications. In this contribution, a new approach to develop flexible ferroelectric hybrid fibers for soft body shape sensing is investigated. Piezoelectric particles incorporated in a polymer matrix and extruded as fiber, 0-3 composite in fibrous form is studied. Commercially obtained calcined PZT and calcined BaTiO3 powders were used in the unsintered form to obtain flexible soft condensed matter ferroelectric hybrid fibers. The extruded fibers were subjected to investigation for their electromechanical behavior as a function of electric field. The hybrid fibers reached 10% of the maximum polarization of their sintered counterpart.

Realizations of highly heterogeneous collagen networks via stochastic reconstruction for micromechanical analysis of tumor cell invasion

NASA Astrophysics Data System (ADS)

Nan, Hanqing; Liang, Long; Chen, Guo; Liu, Liyu; Liu, Ruchuan; Jiao, Yang

2018-03-01

Three-dimensional (3D) collective cell migration in a collagen-based extracellular matrix (ECM) is among one of the most significant topics in developmental biology, cancer progression, tissue regeneration, and immune response. Recent studies have suggested that collagen-fiber mediated force transmission in cellularized ECM plays an important role in stress homeostasis and regulation of collective cellular behaviors. Motivated by the recent in vitro observation that oriented collagen can significantly enhance the penetration of migrating breast cancer cells into dense Matrigel which mimics the intravasation process in vivo [Han et al. Proc. Natl. Acad. Sci. USA 113, 11208 (2016), 10.1073/pnas.1610347113], we devise a procedure for generating realizations of highly heterogeneous 3D collagen networks with prescribed microstructural statistics via stochastic optimization. Specifically, a collagen network is represented via the graph (node-bond) model and the microstructural statistics considered include the cross-link (node) density, valence distribution, fiber (bond) length distribution, as well as fiber orientation distribution. An optimization problem is formulated in which the objective function is defined as the squared difference between a set of target microstructural statistics and the corresponding statistics for the simulated network. Simulated annealing is employed to solve the optimization problem by evolving an initial network via random perturbations to generate realizations of homogeneous networks with randomly oriented fibers, homogeneous networks with aligned fibers, heterogeneous networks with a continuous variation of fiber orientation along a prescribed direction, as well as a binary system containing a collagen region with aligned fibers and a dense Matrigel region with randomly oriented fibers. The generation and propagation of active forces in the simulated networks due to polarized contraction of an embedded ellipsoidal cell and a small group of cells are analyzed by considering a nonlinear fiber model incorporating strain hardening upon large stretching and buckling upon compression. Our analysis shows that oriented fibers can significantly enhance long-range force transmission in the network. Moreover, in the oriented-collagen-Matrigel system, the forces generated by a polarized cell in collagen can penetrate deeply into the Matrigel region. The stressed Matrigel fibers could provide contact guidance for the migrating cell cells, and thus enhance their penetration into Matrigel. This suggests a possible mechanism for the observed enhanced intravasation by oriented collagen.

Ballistic Impact of Braided Composites with a Soft Projectile

NASA Technical Reports Server (NTRS)

Roberts, Gary D.; Pereira, J. Michael; Revilock, Duane M., Jr.; Binienda, Wieslaw K.; Xie, Ming; Braley, Mike

2002-01-01

Impact tests using a soft gelatin projectile were performed to identify failure modes that occur at high strain energy density during impact loading. Failure modes were identified for aluminum plates and for composites plates and half-rings made from triaxial carbon fiber braid having a 0/+/- 60deg architecture. For aluminum plates, a large hole formed as a result of crack propagation from the initiation site at the center of the plate. For composite plates, fiber tensile failure occurred in the back ply at the center of the plate. Cracks then propagated from this site along the +/-60deg fiber directions until triangular flaps opened to form a hole. For composite half-rings fabricated with 0deg fibers aligned circumferentially, fiber tensile failure also occurred in the back ply. Cracks first propagated from this site perpendicular the 0deg fibers. The cracks then turned to follow the +/-60deg fibers and 0deg fibers until rectangular flaps opened to form a hole. Damage in the composites was localized near the impact site, while cracks in the aluminum extended to the boundaries.

Advances in sapphire optical fiber sensors

NASA Technical Reports Server (NTRS)

Wang, Anbo; Wang, George Z.; Gollapudi, Sridhar; May, Russell G.; Murphy, Kent A.; Claus, Richard O.

1993-01-01

We describe the development and testing of two sapphire fiber sensor designs intended for use in high temperature environments. The first is a birefringence-balanced polarimetric sapphire fiber sensor. In this sensor, two single crystal sapphire rods, acting as the birefringence sensing element, are connected to each other in such a way that the slow axis of the first rod is aligned along with the fast axis of the second rod, and the fast axis of the first rod is along the slow axis of the second rod. This sensor has been demonstrated for measurement of temperature up to 1500 C. The second is a sapphire-fiber-based intrinsic interferometric sensor. In this sensor, a length of uncoated, unclad, structural-graded multimode sapphire fiber is fusion spliced to a singlemode silica fiber to form a Fabry-Perot cavity. The reflections from the silica-to-sapphire fiber splice and the free endface of the sapphire fiber give rise to the interfering fringe output. This sensor has been demonstrated for the measurement of temperature above 1510 C, and a resolution of 0.1 C has been obtained.

Variable deflection response of sensitive CNT-on-fiber artificial hair sensors from CNT synthesis in high aspect ratio microcavities

NASA Astrophysics Data System (ADS)

Slinker, Keith; Maschmann, Matthew R.; Kondash, Corey; Severin, Benjamin; Phillips, David; Dickinson, Benjamin T.; Reich, Gregory; Baur, Jeff

2015-03-01

Crickets, locusts, bats, and many other animals detect changes in their environment with distributed arrays of flow-sensitive hairs. Here we discuss the fabrication and characterization of a relatively new class of pore-based, artificial hair sensors that take advantage of the mechanical properties of structural microfibers and the electromechanical properties of self-aligned carbon nanotube arrays to rapidly transduce changes in low speed air flow. The radially aligned nanotubes are able to be synthesized along the length of the fibers inside the high aspect ratio cavity between the fiber surface and the wall of a microcapillary pore. The growth self-positions the fibers within the capillary and forms a conductive path between detection electrodes. As the hair is deflected, nanotubes are compressed to produce a typical resistance change of 1-5% per m/s of air speed which we believe are the highest sensitivities reported for air velocities less than 10 m/s. The quasi-static response of the sensors to point loads is compared to that from the distributed loads of air flow. A plane wave tube is used to measure their dynamic response when perturbed at acoustic frequencies. Correlation of the nanotube height profile inside the capillary to a diffusion transport model suggests that the nanotube arrays can be controllably tapered along the fiber. Like their biological counterparts, many applications can be envisioned for artificial hair sensors by tailoring their individual response and incorporating them into arrays for detecting spatio-temporal flow patterns over rigid surfaces such as aircraft.

Four-probe charge transport measurements on individual vertically aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Zhang, Lan; Austin, Derek; Merkulov, Vladimir I.; Meleshko, Anatoli V.; Klein, Kate L.; Guillorn, Michael A.; Lowndes, Douglas H.; Simpson, Michael L.

2004-05-01

We report four-probe I-V measurements on individual vertically aligned carbon nanofibers (VACNFs). These measurements were enabled by the fabrication of multiple Ti/Au ohmic contacts on individual fibers that exhibited resistance of only a few kilohms. These measurements demonstrate that VACNFs exhibit linear I-V behavior at room temperature, with a resistivity of approximately 4.2×10-3 Ω cm. Our measurements are consistent with a dominant transport mechanism of electrons traveling through intergraphitic planes in the VACNFs.

LIMAO: Cross-platform software for simulating laser-induced alignment and orientation dynamics of linear-, symmetric- and asymmetric tops

NASA Astrophysics Data System (ADS)

Szidarovszky, Tamás; Jono, Maho; Yamanouchi, Kaoru

2018-07-01

A user-friendly and cross-platform software called Laser-Induced Molecular Alignment and Orientation simulator (LIMAO) has been developed. The program can be used to simulate within the rigid rotor approximation the rotational dynamics of gas phase molecules induced by linearly polarized intense laser fields at a given temperature. The software is implemented in the Java and Mathematica programming languages. The primary aim of LIMAO is to aid experimental scientists in predicting and analyzing experimental data representing laser-induced spatial alignment and orientation of molecules.

ISSLS prize winner: integrating theoretical and experimental methods for functional tissue engineering of the annulus fibrosus.

PubMed

Nerurkar, Nandan L; Mauck, Robert L; Elliott, Dawn M

2008-12-01

Integrating theoretical and experimental approaches for annulus fibrosus (AF) functional tissue engineering. Apply a hyperelastic constitutive model to characterize the evolution of engineered AF via scalar model parameters. Validate the model and predict the response of engineered constructs to physiologic loading scenarios. There is need for a tissue engineered replacement for degenerate AF. When evaluating engineered replacements for load-bearing tissues, it is necessary to evaluate mechanical function with respect to the native tissue, including nonlinearity and anisotropy. Aligned nanofibrous poly-epsilon-caprolactone scaffolds with prescribed fiber angles were seeded with bovine AF cells and analyzed over 8 weeks, using experimental (mechanical testing, biochemistry, histology) and theoretical methods (a hyperelastic fiber-reinforced constitutive model). The linear region modulus for phi = 0 degrees constructs increased by approximately 25 MPa, and for phi = 90 degrees by approximately 2 MPa from 1 day to 8 weeks in culture. Infiltration and proliferation of AF cells into the scaffold and abundant deposition of s-GAG and aligned collagen was observed. The constitutive model had excellent fits to experimental data to yield matrix and fiber parameters that increased with time in culture. Correlations were observed between biochemical measures and model parameters. The model was successfully validated and used to simulate time-varying responses of engineered AF under shear and biaxial loading. AF cells seeded on nanofibrous scaffolds elaborated an organized, anisotropic AF-like extracellular matrix, resulting in improved mechanical properties. A hyperelastic fiber-reinforced constitutive model characterized the functional evolution of engineered AF constructs, and was used to simulate physiologically relevant loading configurations. Model predictions demonstrated that fibers resist shear even when the shearing direction does not coincide with the fiber direction. Further, the model suggested that the native AF fiber architecture is uniquely designed to support shear stresses encountered under multiple loading configurations.

An optically passive method that doubles the rate of 2-Ghz timing fiducials

NASA Astrophysics Data System (ADS)

Boni, R.; Kendrick, J.; Sorce, C.

2017-08-01

Solid-state optical comb-pulse generators provide a convenient and accurate method to include timing fiducials in a streak camera image for time base correction. Commercially available vertical-cavity surface-emitting lasers (VCSEL's) emitting in the visible currently in use can be modulated up to 2 GHz. An optically passive method is presented to interleave a time-delayed path of the 2-GHz comb with itself, producing a 4-GHz comb. This technique can be applied to VCSEL's with higher modulation rates. A fiber-delivered, randomly polarized 2-GHz VCSEL comb is polarization split into s-polarization and p-polarization paths. One path is time delayed relative to the other by twice the 2-GHz rate with +/-1-ps accuracy; the two paths then recombine at the fiber-coupled output. High throughput (>=90%) is achieved by carefully using polarization beam-splitting cubes, a total internal reflection beam-path-steering prism, and antireflection coatings. The glass path-length delay block and turning prism are optically contacted together. The beam polarizer cubes that split and recombine the paths are precision aligned and permanently cemented into place. We expect the palm-sized, inline fiber-coupled, comb-rate-doubling device to maintain its internal alignment indefinitely.

Novel optical interconnect devices applying mask-transfer self-written method

NASA Astrophysics Data System (ADS)

Ishizawa, Nobuhiko; Matsuzawa, Yusuke; Tokiwa, Yu; Nakama, Kenichi; Mikami, Osamu

2012-01-01

The introduction of optical interconnect technology is expected to solve problems of conventional electric wiring. One of the promising technologies realizing optical interconnect is the self-written waveguide (SWW) technology with lightcurable resin. We have developed a new technology of the "Mask-Transfer Self-Written (MTSW)" method. This new method enables fabrication of arrayed M x N optical channels at one shot of UV-light. Using this technology, several new optical interconnect devices and connection technologies have been proposed and investigated. In this paper, first, we introduce MTSW method briefly. Next, we show plug-in alignment approach using optical waveguide plugs (OWP) and a micro-hole array (MHA) which are made of the light-curable resin. Easy and high efficiency plug-in alignment between fibers and an optoelectronic-printed wiring board (OE-PWB), between a fiber and a VCSEL, so on will be feasible. Then, we propose a new three-dimensional (3D) branch waveguide. By controlling the irradiating angle through the photomask aperture, it will be possible to fabricate 2-branch and 4-branch waveguides with a certain branch angle. The 3D branch waveguide will be very promising in the future optical interconnects and coupler devices of the multicore optical fiber.

Method of manufacturing battery plate groups

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

Marui, T.; Uwani, T.

A method is described of manufacturing battery plate groups which comprises (a) providing a pliable, smooth, continuous glass fiber mat which has a predetermined thickness, (b) providing a pair of plastic rotors which are aligned in parallel, the rotors including circumferential surfaces and equal numbers of projections extending outwardly from their circumferential surfaces a distance of between 0.7 mm and 2mm, (c) spacing the rotors apart such that a clearance is provided between the projections on one rotor and the circumferential surface of the other rotor which is between 1/3 and 1/2 the predetermined thickness of the glass fiber mat,more » (d) rotating both the rotors such that the projections from one rotor are displaced by half a pitch from the projections from the other rotor, (e) passing the glass fiber mat between the rotors such that the projections thereon form alternately-directed folding habits therein at regular intervals along its length and to provide interconnected separator portions which are aligned in an accordion-like fashion, (f) providing an alternating series of positive and negative battery plates on only one side of the interconnected separator portions, and (g) sequentially inserting the positive and negative battery plates between adjacent separator portions.« less

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.

Seed crystals and catalyzed epitaxy of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Wang, Yuhuang

This thesis demonstrates the continued growth of single-walled carbon nanotubes (SWNTs) from seeded SWNTs in a way analogous to epitaxy or cloning; that is, the SWNTs grow as a seamless extension to the existing seeded SWNTs and have the same diameter and chirality as those of the SWNT seeds. The experiments were carried out in three key steps, including: (1) preparing a macroscopic array of open-ended SWNTs; (2) reductively docking transition metals as a catalyst to the nanometer-sized open ends; and then (3) heating the whole up to 700--850°C in the presence of a carbon feedstock such as ethanol or ethylene. The resulting SWNT ropes inherit the diameters and chirality from the seeded SWNTs, as indicated by the closely matched frequencies of Raman radial breathing modes before and after the growth. As a control, only sparse nanotubes grew from closed-ended SWNTs, ruling out spontaneous nucleation as a dominating mechanism in our experiments. This experiment proved for the first time the growth of SWNTs can be separated from the nucleation step. The ability to separate the typically inefficient nucleation step from the growth of SWNTs and to restart the growth opens the possibility of amplifying SWNTs with only the desired (n, m). The success in the continued growth was enabled with the creation of macroscopic arrays of open-ended SWNTs from a neat SWNT fiber. A variety of techniques including cryo-microtoming and surface etching chemistry have been developed to produce a macroscopic (˜1200mum2), aligned, and clean---largely free of amorphous carbon, oxides, and metal residuals---SWNT substrate with open-ended SWNTs aligned along the fiber axis. Alternatively, the fiber was milled perpendicular to the fiber axis with a gallium focused ion beam to produce a planar, free-standing, ultra-thin, "bed-of-nails" SWNT membrane---a single layer of parallel SWNTs densely packed and aligned along the normal of the membrane.

Method And Apparatus For Coupling Optical Elements To Optoelectronic Devices For Manufacturing Optical Transceiver Modules

DOEpatents

Anderson, Gene R.; Armendariz, Marcelino G.; Bryan, Robert P.; Carson, Richard F.; Chu, Dahwey; Duckett, III, Edwin B.; Giunta, Rachel Knudsen; Mitchell, Robert T.; McCormick, Frederick B.; Peterson, David W.; Rising, Merideth A.; Reber, Cathleen A.; Reysen, Bill H.

2005-06-14

A process is provided for aligning and connecting at least one optical fiber to at least one optoelectronic device so as to couple light between at least one optical fiber and at least one optoelectronic device. One embodiment of this process comprises the following steps: (1) holding at least one optical element close to at least one optoelectronic device, at least one optical element having at least a first end; (2) aligning at least one optical element with at least one optoelectronic device; (3) depositing a first non-opaque material on a first end of at least one optoelectronic device; and (4) bringing the first end of at least one optical element proximate to the first end of at least one optoelectronic device in such a manner that the first non-opaque material contacts the first end of at least one optoelectronic device and the first end of at least one optical element. The optical element may be an optical fiber, and the optoelectronic device may be a vertical cavity surface emitting laser. The first non-opaque material may be a UV optical adhesive that provides an optical path and mechanical stability. In another embodiment of the alignment process, the first end of at least one optical element is brought proximate to the first end of at least one optoelectronic device in such a manner that an interstitial space exists between the first end of at least one optoelectronic device and the first end of at least one optical element.

RhoA regulates Activin B-induced stress fiber formation and migration of bone marrow-derived mesenchymal stromal cell through distinct signaling.

PubMed

Wang, Xueer; Tang, Pei; Guo, Fukun; Zhang, Min; Chen, Yinghua; Yan, Yuan; Tian, Zhihui; Xu, Pengcheng; Zhang, Lei; Zhang, Lu; Zhang, Lin

2017-01-01

In our previous study, Activin B induced actin stress fiber formation and cell migration in Bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. However, the underlying molecular mechanisms are not well studied. RhoA is recognized to play a critical role in the regulation of actomyosin cytoskeletal organization and cell migration. Pull-down assay was performed to investigate the activity of RhoA. The dominant-negative mutants of RhoA (RhoA(N19)) was used to determine whether RhoA has a role in Activin B-induced cytoskeleton organization and cell migration in BMSCs. Cytoskeleton organization was examined by fluorescence Rhodamine-phalloidin staining, and cell migration by transwell and cell scratching assay. Western blot was carried out to investigate downstream signaling cascade of RhoA. Inhibitor and siRNAs were used to detect the role of downstream signaling in stress fiber formation and/or cell migration. RhoA was activated by Activin B in BMSCs. RhoA(N19) blocked Activin B-induced stress fiber formation and cell migration. ROCK inhibitor blocked Activin B-induced stress fiber formation but enhanced BMSCs migration. Activin B induced phosphorylation of LIMK2 and Cofilin, which was abolished by ROCK inhibition. Both of siRNA LIMK2 and siRNA Cofilin inhibited Activin B-induced stress fiber formation. RhoA regulates Activin B-induced stress fiber formation and migration of BMSCs. A RhoA-ROCK-LIMK2-Cofilin signaling node exists and regulates actin stress fiber formation. RhoA regulates Activin B-induced cell migration independent of ROCK. Better understanding of the molecular mechanisms of BMSCs migration will help optimize therapeutic strategy to target BMSCs at injured tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Using in-situ polymerization of conductive polymers to enhance the electrical properties of solution-processed carbon nanotube films and fibers.

PubMed

Allen, Ranulfo; Pan, Lijia; Fuller, Gerald G; Bao, Zhenan

2014-07-09

Single-walled carbon nanotubes/polymer composites typically have limited conductivity due to a low concentration of nanotubes and the insulating nature of the polymers used. Here we combined a method to align carbon nanotubes with in-situ polymerization of conductive polymer to form composite films and fibers. Use of the conducting polymer raised the conductivity of the films by 2 orders of magnitude. On the other hand, CNT fiber formation was made possible with in-situ polymerization to provide more mechanical support to the CNTs from the formed conducting polymer. The carbon nanotube/conductive polymer composite films and fibers had conductivities of 3300 and 170 S/cm, respectively. The relatively high conductivities were attributed to the polymerization process, which doped both the SWNTs and the polymer. In-situ polymerization can be a promising solution-processable method to enhance the conductivity of carbon nanotube films and fibers.

Cryogenic structural support

DOEpatents

Niemann, Ralph C.; Mataya, Karl F.; Gonczy, John D.

1982-01-01

A tensile support member is provided for use in a cryogenic environment. The member is in the form of a link formed of an epoxy glass laminate with at least one ply of the laminate having its fibers aligned circumferentially about the link.

Fabrication process for polymer PLC platforms with V-grooves for passive alignment

NASA Astrophysics Data System (ADS)

Park, Suntak; Lee, Jong-Moo; Ahn, Joon Tae; Baek, Yong-Soon

2005-12-01

A method for polymer planar lightwave circuit (PLC) devices fabricated on a substrate with V-grooves is developed for passive alignment of an optical fiber to a polymer waveguide. In order to minimize thickness nonuniformity of polymer layers caused by the V-grooves, dry film resist (DFR) is used. The V-grooves are covered with the DFR before the polymer layers are spin-coated on the substrate. The DFR prevents the polymer from being filled in the V-grooves as well as from being spin-coated nonuniformly on the substrate. This process provides a simple and cost-effective fabrication method of polymer PLCs or platforms for passive alignment.

Finite deformation of incompressible fiber-reinforced elastomers: A computational micromechanics approach

NASA Astrophysics Data System (ADS)

Moraleda, Joaquín; Segurado, Javier; LLorca, Javier

2009-09-01

The in-plane finite deformation of incompressible fiber-reinforced elastomers was studied using computational micromechanics. Composite microstructure was made up of a random and homogeneous dispersion of aligned rigid fibers within a hyperelastic matrix. Different matrices (Neo-Hookean and Gent), fibers (monodisperse or polydisperse, circular or elliptical section) and reinforcement volume fractions (10-40%) were analyzed through the finite element simulation of a representative volume element of the microstructure. A successive remeshing strategy was employed when necessary to reach the large deformation regime in which the evolution of the microstructure influences the effective properties. The simulations provided for the first time "quasi-exact" results of the in-plane finite deformation for this class of composites, which were used to assess the accuracy of the available homogenization estimates for incompressible hyperelastic composites.

Low frequency noise fiber delay stabilized laser with reduced sensitivity to acceleration

NASA Astrophysics Data System (ADS)

Argence, B.; Clivati, C.; Dournaux, J.-L.; Holleville, D.; Faure, B.; Lemonde, P.; Santarelli, G.

2017-11-01

Lasers with sub-hertz line-width and fractional frequency instability around 1×10-15 for 0.1 s to 10 s averaging time are currently realized by locking onto an ultra-stable Fabry-Perot cavity using the Pound-Drever-Hall method. This powerful method requires tight alignment of free space optical components, precise polarization adjustment and spatial mode matching. To circumvent these issues, we use an all-fiber Michelson interferometer with a long fiber spool as a frequency reference and a heterodyne detection technique with a fibered acousto optical modulator (AOM)1. At low Fourier frequencies, the frequency noise of our system is mainly limited by mechanical vibrations, an issue that has already been explored in the field of optoelectronic oscillators.2,3,4

Electrically and mechanically induced long period gratings in liquid crystal photonic bandgap fibers

NASA Astrophysics Data System (ADS)

Noordegraaf, Danny; Scolari, Lara; Lægsgaard, Jesper; Rindorf, Lars; Tanggaard Alkeskjold, Thomas

2007-06-01

We demonstrate electrically and mechanically induced long period gratings (LPGs) in a photonic crystal fiber (PCF) filled with a high-index liquid crystal. The presence of the liquid crystal changes the guiding properties of the fiber from an index guiding fiber to a photonic bandgap guiding fiber - a so called liquid crystal photonic bandgap (LCPBG) fiber. Both the strength and resonance wavelength of the gratings are highly tunable. By adjusting the amplitude of the applied electric field, the grating strength can be tuned and by changing the temperature, the resonance wavelength can be tuned as well. Numerical calculations of the higher order modes of the fiber cladding are presented, allowing the resonance wavelengths to be calculated. A high polarization dependent loss of the induced gratings is also observed.

Flexible and weaveable capacitor wire based on a carbon nanocomposite fiber.

PubMed

Ren, Jing; Bai, Wenyu; Guan, Guozhen; Zhang, Ye; Peng, Huisheng

2013-11-06

A flexible and weaveable electric double-layer capacitor wire is developed by twisting two aligned carbon nanotube/ordered mesoporous carbon composite fibers with remarkable mechanical and electronic properties as electrodes. This capacitor wire exhibits high specific capacitance and long life stability. Compared with the conventional planar structure, the capacitor wire is also lightweight and can be integrated into various textile structures that are particularly promising for portable and wearable electronic devices. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement and Optimization of Internal Damping in Fiber Reinforced Composite Materials

DTIC Science & Technology

1986-03-03

Resin Casting ............. 61 5.0 TESTS ON DISCONTINUOUS ALIGNED FIBER REINFORCED COMPOSITES . . . ...................... 63 5.1 Experimental...After some :x..iipulation [ 61 , the longitudinal storage modulus is given by: Vf -+-- -~V (2.9) Eý Eý E P9. t z[(R /r) - ] + cosha.t I-. . 10 where 1...the storage moduluii were fitted with a linear regression given by E . . 61 E’ = 571252.737 + 55.647 x f (psi) (4.1) m Where f is the frequency in

100 GB/S Time Division Multiplex (TDM) Access Nodes and Regenerators Based on Novel Loop Mirrors with High Nonlinearity Fibers

DTIC Science & Technology

2002-07-01

spectral components remain co-polarized. We confirmed that this was the case by passing the continuum through a polarizing beam splitter . The...propagation direction through polarization beam splitters and aligned along the other axis of the fiber. Co-propagating control and signal pulses...amplifier, PBS = polarization beam splitter . Figure 8. Eye diagram of header processor. This is the trace of the eye diagrams taken with the setup of Fig

Calculated Coupling Efficiency Between an Elliptical-Core Optical Fiber and a Silicon Oxynitride Rib Waveguide [Corrected Copy

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.; Beheim, Glenn

1995-01-01

The effective-index method and Marcatili's technique were utilized independently to calculate the electric field profile of a rib channel waveguide. Using the electric field profile calculated from each method, the theoretical coupling efficiency between a single-mode optical fiber and a rib waveguide was calculated using the overlap integral. Perfect alignment was assumed and the coupling efficiency calculated. The coupling efficiency calculation was then repeated for a range of transverse offsets.

Fibre Optic Connections And Method For Using Same

DOEpatents

Chan, Benson; Cohen, Mitchell S.; Fortier, Paul F.; Freitag, Ladd W.; Hall, Richard R.; Johnson, Glen W.; Lin, How Tzu; Sherman, John H.

2004-03-30

A package is described that couples a twelve channel wide fiber optic cable to a twelve channel Vertical Cavity Surface Emitting Laser (VCSEL) transmitter and a multiple channel Perpendicularly Aligned Integrated Die (PAID) receiver. The package allows for reduction in the height of the assembly package by vertically orienting certain dies parallel to the fiber optic cable and horizontally orienting certain other dies. The assembly allows the vertically oriented optoelectronic dies to be perpendicularly attached to the horizontally oriented laminate via a flexible circuit.

Mass Transfer and Rheology of Fiber Suspensions

NASA Astrophysics Data System (ADS)

Wang, Jianghui

Rheological and mass transfer properties of non-Brownian fiber suspensions are affected by fiber characteristics, fiber interactions, and processing conditions. In this thesis we develop several simulation methods to study the dynamics of single fibers in simple shear flow, as well as the rheology and mass transfer of fiber suspensions. Isolated, rigid, neutrally-buoyant, non-Brownian, slightly curved, nonchiral fibers in simple shear flow of an incompressible Newtonian fluid at low Reynolds number can drift steadily in the gradient direction without external forces or torques. The average drift velocity and direction depend on the fiber aspect ratio, curvature and initial orientation. The drift results from the coupling of rotational and translational dynamics, and the combined effects of flipping, scooping, and spinning motions of the fiber. Irreversible fiber collisions in the suspensions cause shear-induced diffusion. The shear-induced self-diffusivity of dilute suspensions of fibers increases with increasing concentration and increasing static friction between contacts. The diffusivities in both the gradient and vorticity directions are larger for suspensions of curved fibers than for suspensions of straight fibers. For suspensions of curved fibers, significant enhancements in the diffusivity in the gradient direction are attributed to fiber drift in the gradient direction. The shear-induced self-diffusivity of concentrated suspensions of fibers increases with increasing concentration before fiber networks or flocs are formed, after which the diffusivity decreases with increasing concentration. The diffusivity increases with increasing fiber equilibrium bending angle, effective stiffness, coefficient of static friction, and rate of collisions. The specific viscosity of fiber suspensions increases with increasing fiber curvature, friction coefficient between mechanical contacts, and solids concentration. The specific viscosity increases linearly with concentration in the dilute regime, and increases with the cube of the concentration in the semi-dilute regime. Concentrated fiber suspensions are highly viscous, shear thinning, and exhibit significant yield stresses and normal stress differences. Yield stresses scale with volume concentration and fiber aspect ratio in the same way as that observed in experiments. The first normal stress difference increases linearly with shear rate. The shear-induced diffusivity increases linearly with the derivative of the particle contribution to stress for dilute suspensions with respective to concentration. This correlation between rheology and shear-induced diffusion makes it possible to predict diffusivity from easily measured rheological properties.

Direct writing of half-meter long CNT based fiber for flexible electronics.

PubMed

Huang, Sihan; Zhao, Chunsong; Pan, Wei; Cui, Yi; Wu, Hui

2015-03-11

Rapid construction of flexible circuits has attracted increasing attention according to its important applications in future smart electronic devices. Herein, we introduce a convenient and efficient "writing" approach to fabricate and assemble ultralong functional fibers as fundamental building blocks for flexible electronic devices. We demonstrated that, by a simple hand-writing process, carbon nanotubes (CNTs) can be aligned inside a continuous and uniform polymer fiber with length of more than 50 cm and diameters ranging from 300 nm to several micrometers. The as-prepared continuous fibers exhibit high electrical conductivity as well as superior mechanical flexibility (no obvious conductance increase after 1000 bending cycles to 4 mm diameter). Such functional fibers can be easily configured into designed patterns with high precision according to the easy "writing" process. The easy construction and assembly of functional fiber shown here holds potential for convenient and scalable fabrication of flexible circuits in future smart devices like wearable electronics and three-dimensional (3D) electronic devices.

Nanoimprint of a 3D structure on an optical fiber for light wavefront manipulation.

PubMed

Calafiore, Giuseppe; Koshelev, Alexander; Allen, Frances I; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

2016-09-16

Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. In this paper we report the fabrication of a three-dimensional structure achieved by direct nanoimprint lithography on the facet of an optical fiber. Nanoimprint processes and tools were specifically developed to enable a high lithographic accuracy and coaxial alignment of the optical device with respect to the fiber core. To demonstrate the capability of this new approach, a 3D beam splitter has been designed, imprinted and optically characterized. Scanning electron microscopy and optical measurements confirmed the good lithographic capabilities of the proposed approach as well as the desired optical performance of the imprinted structure. The inexpensive solution presented here should enable advancements in areas such as integrated optics and sensing, achieving enhanced portability and versatility of fiber optic components.

Nanofiber Alignment Regulates NIH3T3 Cell Orientation and Cytoskeletal Gene Expression on Electrospun PCL+Gelatin Nanofibers.

PubMed

Fee, Timothy; Surianarayanan, Swetha; Downs, Crawford; Zhou, Yong; Berry, Joel

2016-01-01

To examine the influence of substrate topology on the behavior of fibroblasts, tissue engineering scaffolds were electrospun from polycaprolactone (PCL) and a blend of PCL and gelatin (PCL+Gel) to produce matrices with both random and aligned nanofibrous orientations. The addition of gelatin to the scaffold was shown to increase the hydrophilicity of the PCL matrix and to increase the proliferation of NIH3T3 cells compared to scaffolds of PCL alone. The orientation of nanofibers within the matrix did not have an effect on the proliferation of adherent cells, but cells on aligned substrates were shown to elongate and align parallel to the direction of substrate fiber alignment. A microarray of cyotoskeleton regulators was probed to examine differences in gene expression between cells grown on an aligned and randomly oriented substrates. It was found that transcriptional expression of eight genes was statistically different between the two conditions, with all of them being upregulated in the aligned condition. The proteins encoded by these genes are linked to production and polymerization of actin microfilaments, as well as focal adhesion assembly. Taken together, the data indicates NIH3T3 fibroblasts on aligned substrates align themselves parallel with their substrate and increase production of actin and focal adhesion related genes.

10-channel fiber array fabrication technique for parallel optical coherence tomography system

NASA Astrophysics Data System (ADS)

Arauz, Lina J.; Luo, Yuan; Castillo, Jose E.; Kostuk, Raymond K.; Barton, Jennifer

2007-02-01

Optical Coherence Tomography (OCT) shows great promise for low intrusive biomedical imaging applications. A parallel OCT system is a novel technique that replaces mechanical transverse scanning with electronic scanning. This will reduce the time required to acquire image data. In this system an array of small diameter fibers is required to obtain an image in the transverse direction. Each fiber in the array is configured in an interferometer and is used to image one pixel in the transverse direction. In this paper we describe a technique to package 15μm diameter fibers on a siliconsilica substrate to be used in a 2mm endoscopic probe tip. Single mode fibers are etched to reduce the cladding diameter from 125μm to 15μm. Etched fibers are placed into a 4mm by 150μm trench in a silicon-silica substrate and secured with UV glue. Active alignment was used to simplify the lay out of the fibers and minimize unwanted horizontal displacement of the fibers. A 10-channel fiber array was built, tested and later incorporated into a parallel optical coherence system. This paper describes the packaging, testing, and operation of the array in a parallel OCT system.

Innovative design of composite structures: Use of curvilinear fiber format to improve structural efficiency

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Charette, R. F.

1987-01-01

To increase the effectiveness and efficiency of fiber-reinforced materials, the use of fibers in a curvilinear rather than the traditional straightline format is explored. The capacity of a laminated square plate with a central circular hole loaded in tension is investigated. The orientation of the fibers is chosen so that the fibers in a particular layer are aligned with the principle stress directions in that layer. Finite elements and an iteration scheme are used to find the fiber orientation. A noninteracting maximum strain criterion is used to predict load capacity. The load capacities of several plates with different curvilinear fibers format are compared with the capacities of more conventional straightline format designs. It is found that the most practical curvilinear design sandwiches a group of fibers in a curvilinear format between a pair of +/-45 degree layers. This design has a 60% greater load capacity than a conventional quasi-isotropic design with the same number of layers. The +/-45 degree layers are necessary to prevent matrix cracking in the curvilinear layers due to stresses perpendicular to the fibers in those layers. Greater efficiencies are achievable with composite structures than now realized.

Composite Reinforcement by Magnetic Control of Fiber Density and Orientation.

PubMed

Goldberg, Omri; Greenfeld, Israel; Wagner, H Daniel

2018-05-08

The flexural rigidity of cylindrical specimens, composed of epoxy reinforced by short, magnetized glass fibers, was enhanced using weak magnetic fields (<100 mT). By spatially controlling the magnitude and direction of the field, and thereby the torques and forces acting locally on the fibers, the orientation and concentration of the fillers in the matrix could be tuned prior to curing. Unidirectional alignment of the fibers, achieved using an air-core solenoid, improved the contribution of the fibers to the flexure modulus by a factor of 3. When a ring-shaped permanent magnet was utilized, the glass fibers were migrated preferentially near the rod boundary, and as a result, the contribution of the fibers to the flexure modulus doubled. The fiber length, density, and orientation distributions were extracted by μCT image analysis, allowing comparison of the experimental flexure modulus to a modified rule of mixtures prediction. The ability to magnetically control the fiber distribution in reinforced composites demonstrated in this study may be applied in the fabrication of complex micro- and macroscale structures with spatially variable anisotropy, allowing features such as crack diversion, strengthening of highly loaded regions, as well as economic management of materials and weight.

Responses of neuromuscular systems under gravity or microgravity environment.

PubMed

Ishihara, Akihiko; Kawano, Fuminori; Wang, Xiao Dong; Ohira, Yoshinobu

2004-11-01

Hindlimb suspension of rats induces induces fiber atrophy and type shift of muscle fibers. In contrast, there is no change in the cell size or oxidative enzyme activity of spinal motoneurons innervating muscle fibers. Growth-related increases in the cell size of muscle fibers and their spinal motoneurons are inhibited by hindlimb suspension. Exposure to microgravity induces atrophy of fibers (especially slow-twitch fibers) and shift of fibers from slow- to fast-twitch type in skeletal muscles (especially slow, anti-gravity muscles). In addition, a decrease in the oxidative enzyme activity of spinal motoneurons innervating slow-twitch fibers and of sensory neurons in the dorsal root ganglion is observed following exposure to microgravity. It is concluded that neuromuscular activities are important for maintaining metabolism and function of neuromuscular systems at an early postnatal development and that gravity effects both efferent and afferent neural pathways.

Fiber optic Cerenkov radiation sensor system to estimate burn-up of spent fuel: characteristic evaluation of the system using Co-60 source

NASA Astrophysics Data System (ADS)

Shin, S. H.; Jang, K. W.; Jeon, D.; Hong, S.; Kim, S. G.; Sim, H. I.; Yoo, W. J.; Park, B. G.; Lee, B.

2013-09-01

Cerenkov radiation occurs when charged particles are moving faster than the speed of light in a transparent dielectric medium. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the spectra of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, the intensities of Cerenkov radiation induced by gamma-rays generated from a cylindrical Co-60 source with or without lead shielding were measured using the fiberoptic Cerenkov radiation sensor system.

Optical-Fiber Leak Detector

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Kosten, Susan E.

1994-01-01

Proposed optical-fiber sensor detects small changes in pressure in elastomeric O-ring or similar pressure seal, which may indicate deterioration of seal and interpreted as indications of incipient failure. According to concept, length of optical fiber embedded in seal. Light-emitting diode illuminates one end of fiber; photodetector measures intensity of light emerging from other end. Pressure-induced changes in seal bend fiber slightly, altering microbending-induced loss of light from fiber and alter intensity of light at photodetector. Change in intensity approximately proportional to change in pressure.

Sickness behavior induced by endotoxin can be mitigated by the dietary soluble fiber, pectin, through up-regulation of IL-4 and Th2 polarization

PubMed Central

Sherry, Christina L.; Kim, Stephanie S.; Dilger, Ryan N.; Bauer, Laura L.; Moon, Morgan L.; Tapping, Richard I.; Fahey, George C.; Tappenden, Kelly A.; Freund, Gregory G.

2010-01-01

Peripheral activation of the immune system by infectious agents triggers the brain-cytokine system causing sickness behaviors which profoundly impact well-being. Dietary fiber is a beneficial foodstuff that, from a gastrointestinal tract perspective, exists in both insoluble and soluble forms. We show that a diet rich in soluble fiber protects mice from endotoxin-induced sickness behavior by polarizing mice Th2 when compared to a diet containing only insoluble fiber. Mice fed soluble fiber became less sick and recovered faster from endotoxin-induced sickness behaviors than mice fed insoluble fiber. In response to intraperitoneal endotoxin, mice fed soluble fiber had up-regulated IL-1RA and reduced IL-1βand TNF-αin the brain as compared to mice fed insoluble fiber. Importantly, mice fed soluble fiber had a basal increase in IL-4 in the ileum and spleen which was absent in MyD88 knockout mice. Con A stimulated splenocytes from mice fed soluble fiber showed increased IL-4 and IL-5 and decreased IL-2, IL-12 and IFN-γwhen compared to mice fed insoluble fiber. Likewise, endotoxin-stimulated macrophages from mice fed soluble fiber demonstrated decreased IL-1β, TNF-α, IFN-γ, IL-12 and nitrate and increased IL-1RA, arginase 1 and Ym1 when compared to mice fed insoluble fiber. Finally, the behavioral protection afforded by feeding mice soluble fiber was reduced in IL-4 knockout mice, as was the impact of soluble fiber on Con A stimulated splenocytes and endotoxin activated macrophages. These data show that a diet rich in soluble fiber protects against endotoxin-induced sickness behavior by polarizing mice Th2 and promoting alternative activation of macrophages. PMID:20138982

Comparison of behavior in muscle fiber regeneration after bupivacaine hydrochloride- and acid anhydride-induced myonecrosis.

PubMed

Akiyama, C; Kobayashi, S; Nonaka, I

1992-01-01

We compared the morphologic characteristics of muscle fiber necrosis and subsequent regeneration after injury induced by intramuscular injections of bupivacaine hydrochloride (BPVC) and a variety of solutions at acid and alkaline pH (acetic anhydride, citric acid buffer, and sodium carbonate buffer). After BPVC injection the necrotic muscle fibers were rapidly invaded by phagocytic cells, followed by active regeneration and very little fibrous scar formation. The regenerating muscle fibers increased rapidly in size and attained complete fiber type differentiation and regained their initial fiber diameter within 1 month. Both alkaline and acid solutions induced muscle fiber necrosis followed by regeneration. Fiber necrosis induced by alkaline buffers and acetic anhydride solutions above pH 5.0 produced changes quite similar to that induced by BPVC. However, injection with 0.1 M acetic anhydride at pH below 4.0 resulted in coagulative necrosis of the injured muscle with very little phagocytic infiltration with poor regenerative activity and dense fibrous tissue scarring. Thus, pH 4.0 appears to be the critical pH determining the type of muscle injury and subsequent poor phagocytic and regenerative activities. This model of acidic acetic anhydride injury may lead to the identification of factors which interfere with regeneration and cause fibrous tissue scarring in human muscular dystrophy.

Clinical Utility of LC3 and p62 Immunohistochemistry in Diagnosis of Drug-Induced Autophagic Vacuolar Myopathies: A Case-Control Study

PubMed Central

Lee, Han S.; Daniels, Brianne H.; Salas, Eduardo; Bollen, Andrew W.; Debnath, Jayanta; Margeta, Marta

2012-01-01

Background Some patients treated with chloroquine, hydroxychloroquine, or colchicine develop autophagic vacuolar myopathy, the diagnosis of which currently requires electron microscopy. The goal of the current study was to develop an immunohistochemical diagnostic marker for this pathologic entity. Methodology Microtubule-associated protein light chain 3 (LC3) has emerged as a robust marker of autophagosomes. LC3 binds p62/SQSTM1, an adapter protein that is selectively degraded via autophagy. In this study, we evaluated the utility of immunohistochemical stains for LC3 and p62 as diagnostic markers of drug-induced autophagic vacuolar myopathy. The staining was performed on archival muscle biopsy material, with subject assignment to normal control, drug-treated control, and autophagic myopathy groups based on history of drug use and morphologic criteria. Principal Findings In all drug-treated subjects, but not in normal controls, LC3 and p62 showed punctate staining characteristic of autophagosome buildup. In the autophagic myopathy subjects, puncta were coarser and tended to coalesce into linear structures aligned with the longitudinal axis of the fiber, often in the vicinity of vacuoles. The percentage of LC3- and p62-positive fibers was significantly higher in the autophagic myopathy group compared to either the normal control (p<0.001) or the drug-treated control group (p<0.05). With the diagnostic threshold set between 8% and 15% positive fibers (depending on the desired level of sensitivity and specificity), immunohistochemical staining for either LC3 or p62 could be used to identify subjects with autophagic vacuolar myopathy within the drug-treated subject group (p≤0.001). Significance Immunohistochemistry for LC3 and p62 can facilitate tissue-based diagnosis of drug-induced autophagic vacuolar myopathies. By limiting the need for electron microscopy (a time consuming and costly technique with high specificity, but low sensitivity), clinical use of these markers will improve the speed and accuracy of diagnosis, resulting in significantly improved clinical care. PMID:22558391

Aligned ovine diaphragmatic myoblasts overexpressing human connexin-43 seeded on poly (L-lactic acid) scaffolds for potential use in cardiac regeneration.

PubMed

Giménez, Carlos Sebastián; Locatelli, Paola; Montini Ballarin, Florencia; Orlowski, Alejandro; Dewey, Ricardo A; Pena, Milagros; Abraham, Gustavo Abel; Aiello, Ernesto Alejandro; Bauzá, María Del Rosario; Cuniberti, Luis; Olea, Fernanda Daniela; Crottogini, Alberto

2018-04-01

Diaphragmatic myoblasts (DMs) are precursors of type-1 muscle cells displaying high exhaustion threshold on account that they contract and relax 20 times/min over a lifespan, making them potentially useful in cardiac regeneration strategies. Besides, it has been shown that biomaterials for stem cell delivery improve cell retention and viability in the target organ. In the present study, we aimed at developing a novel approach based on the use of poly (L-lactic acid) (PLLA) scaffolds seeded with DMs overexpressing connexin-43 (cx43), a gap junction protein that promotes inter-cell connectivity. DMs isolated from ovine diaphragm biopsies were characterized by immunohistochemistry and ability to differentiate into myotubes (MTs) and transduced with a lentiviral vector encoding cx43. After confirming cx43 expression (RT-qPCR and Western blot) and its effect on inter-cell connectivity (fluorescence recovery after photobleaching), DMs were grown on fiber-aligned or random PLLA scaffolds. DMs were successfully isolated and characterized. Cx43 mRNA and protein were overexpressed and favored inter-cell connectivity. Alignment of the scaffold fibers not only aligned but also elongated the cells, increasing the contact surface between them. This novel approach is feasible and combines the advantages of bioresorbable scaffolds as delivery method and a cell type that on account of its features may be suitable for cardiac regeneration. Future studies on animal models of myocardial infarction are needed to establish its usefulness on scar reduction and cardiac function.

Photonomics: automation approaches yield economic aikido for photonics device manufacture

NASA Astrophysics Data System (ADS)

Jordan, Scott

2002-09-01

In the glory days of photonics, with exponentiating demand for photonics devices came exponentiating competition, with new ventures commencing deliveries seemingly weekly. Suddenly the industry was faced with a commodity marketplace well before a commodity cost structure was in place. Economic issues like cost, scalability, yield-call it all "Photonomics" -now drive the industry. Automation and throughput-optimization are obvious answers, but until now, suitable modular tools had not been introduced. Available solutions were barely compatible with typical transverse alignment tolerances and could not automate angular alignments of collimated devices and arrays. And settling physics served as the insoluble bottleneck to throughput and resolution advancement in packaging, characterization and fabrication processes. The industry has addressed these needs in several ways, ranging from special configurations of catalog motion devices to integrated microrobots based on a novel mini-hexapod configuration. This intriguing approach allows tip/tilt alignments to be automated about any point in space, such as a beam waist, a focal point, the cleaved face of a fiber, or the optical axis of a waveguide- ideal for MEMS packaging automation and array alignment. Meanwhile, patented new low-cost settling-enhancement technology has been applied in applications ranging from air-bearing long-travel stages to subnanometer-resolution piezo positioners to advance resolution and process cycle-times in sensitive applications such as optical coupling characterization and fiber Bragg grating generation. Background, examples and metrics are discussed, providing an up-to-date industry overview of available solutions.

Treadmill exercise alleviates nigrostriatal dopaminergic loss of neurons and fibers in rotenone-induced Parkinson rats.

PubMed

Shin, Mal-Soon; Kim, Tae-Woon; Lee, Jae-Min; Ji, Eun-Sang; Lim, Baek-Vin

2017-02-01

Parkinson disease is one of the common brain diseases caused by dopaminergic neuronal loss in the substantia nigra and dopaminergic fiber loss in the striatum. In the present study, the effects of treadmill exercise on motor performance, dopaminergic loss of neurons and fibers, and α-synuclein expression in the nigrostriatum were evaluated using rotenone-induced Parkinson rats. For the induction of Parkinson rats, 3-mg/kg rotenone was injected, once a day for 14 consecutive days. Treadmill running was conducted for 30 min once a day during 14 consecutive days. Rota-rod test for motor balance and coordination and immunohistochemistry for tyrosine hydroxylase and α-synuclein in the nigrostriatum were performed. In the present study, motor balance and coordination was disturbed by induction of rotenone-induced Parkinson disease, in contrast, treadmill exercise alleviated motor dysfunction in the rotenone-induced Parkinson rats. Nigrostriatal dopaminergic loss of neurons and fibers was occurred by induction of rotenone-induced Parkinson disease, in contrast, treadmill exercise alleviated nigrostriatal dopaminergic loss of neurons and fibers in the rotenone-induced Parkinson rats. α-Synuclein expression in the nigrostriatum was enhanced by induction of rotenone-induced Parkinson disease, in contrast, treadmill exercise suppressed α-synuclein expression in the rotenone-induced Parkinson rats. Treadmill exercise improved motor function through preservation of nigrostriatal dopaminergic neurons and fibers and suppression of nigrostriatal formation of Lewy bodies in rotenone-induced Parkinson rats.

Tropomodulin 1 Constrains Fiber Cell Geometry during Elongation and Maturation in the Lens Cortex

PubMed Central

Nowak, Roberta B.

2012-01-01

Lens fiber cells exhibit a high degree of hexagonal packing geometry, determined partly by tropomodulin 1 (Tmod1), which stabilizes the spectrin-actin network on lens fiber cell membranes. To ascertain whether Tmod1 is required during epithelial cell differentiation to fiber cells or during fiber cell elongation and maturation, the authors quantified the extent of fiber cell disorder in the Tmod1-null lens and determined locations of disorder by confocal microscopy and computational image analysis. First, nearest neighbor analysis of fiber cell geometry in Tmod1-null lenses showed that disorder is confined to focal patches. Second, differentiating epithelial cells at the equator aligned into ordered meridional rows in Tmod1-null lenses, with disordered patches first observed in elongating fiber cells. Third, as fiber cells were displaced inward in Tmod1-null lenses, total disordered area increased due to increased sizes (but not numbers) of individual disordered patches. The authors conclude that Tmod1 is required first to coordinate fiber cell shapes and interactions during tip migration and elongation and second to stabilize ordered fiber cell geometry during maturation in the lens cortex. An unstable spectrin-actin network without Tmod1 may result in imbalanced forces along membranes, leading to fiber cell rearrangements during elongation, followed by propagation of disorder as fiber cells mature. PMID:22473940

Electrospun Nanofibers: Solving Global Issues

NASA Astrophysics Data System (ADS)

Si, Yang; Tang, Xiaomin; Yu, Jianyong; Ding, Bin

Energy and environment will head the list of top global issues facing society for the next 50 years. Nanotechnology is responding to these challenges by designing and fabricating functional nanofibers optimized for energy and environmental applications. The route toward these nano-objects is based primarily on electrospinning: a highly versatile method that allows the fabrication of continuous fibers with diameters down to a few nanometers. The mechanism responsible for the fiber formation mainly includes the Taylor Cone theory and flight-instability theory, which can be predicted theoretically and controlled experimentally. Moreover, the electrospinning has been applied to natural polymers, synthetic polymers, ceramics, and carbon. Fibers with complex architectures, such as ribbon fiber, porous fiber, core-shell fiber, or hollow fiber, can be produced by special electrospinning methods. It is also possible to produce nanofibrous membranes with designed aggregate structure including alignment, patterning, and two-dimensional nanonets. Finally, the brief analysis of nanofibers used for advanced energy and environmental applications in the past decade indicates that their impact has been realized well and is encouraging, and will continually represent a key technology to ensure sustainable energy and preserve our environment for the future.

Technology Advancement for Active Remote Sensing of Carbon Dioxide from Space Using the ASCENDS CarbonHawk Experiment Simulator: First Results

NASA Technical Reports Server (NTRS)

Obland, Michael D.; Nehrir, Amin R.; Lin, Bing; Harrison, F. Wallace; Kooi, Susan; Choi, Yonghoon; Plant, James; Yang, Melissa; Antill, Charles; Campbell, Joel;

Optical-fiber-to-waveguide coupling using carbon-dioxide-laser-induced long-period fiber gratings.

PubMed

Bachim, Brent L; Ogunsola, Oluwafemi O; Gaylord, Thomas K

2005-08-15

Optical fibers are expected to play a role in chip-level and board-level optical interconnects because of limitations on the bandwidth and level of integration of electrical interconnects. Therefore, methods are needed to couple optical fibers directly to waveguides on chips and on boards. We demonstrate optical-fiber-to-waveguide coupling using carbon-dioxide laser-induced long-period fiber gratings (LPFGs). Such gratings can be written in standard fiber and offer wavelength multiplexing-demultiplexing performance. The coupler fabrication process and the characterization apparatus are presented. The operation and the wavelength response of a LPFG-based optical-fiber-to-waveguide directional coupler are demonstrated.

Collagen Matrix Remodeling in Stented Pulmonary Arteries after Transapical Heart Valve Replacement.

PubMed

Ghazanfari, Samaneh; Driessen-Mol, Anita; Hoerstrup, Simon P; Baaijens, Frank P T; Bouten, Carlijn V C

2016-01-01

The use of valved stents for minimally invasive replacement of semilunar heart valves is expected to change the extracellular matrix and mechanical function of the native artery and may thus impair long-term functionality of the implant. Here we investigate the impact of the stent on matrix remodeling of the pulmonary artery in a sheep model, focusing on matrix composition and collagen (re)orientation of the host tissue. Ovine native pulmonary arteries were harvested 8 (n = 2), 16 (n = 4) and 24 (n = 2) weeks after transapical implantation of self-expandable stented heart valves. Second harmonic generation (SHG) microscopy was used to assess the collagen (re)orientation of fresh tissue samples. The collagen and elastin content was quantified using biochemical assays. SHG microscopy revealed regional differences in collagen organization in all explants. In the adventitial layer of the arterial wall far distal to the stent (considered as the control tissue), we observed wavy collagen fibers oriented in the circumferential direction. These circumferential fibers were more straightened in the adventitial layer located behind the stent. On the luminal side of the wall behind the stent, collagen fibers were aligned along the stent struts and randomly oriented between the struts. Immediately distal to the stent, however, fibers on both the luminal and the adventitial side of the wall were oriented in the axial direction, demonstrating the stent impact on the collagen structure of surrounding arterial tissues. Collagen orientation patterns did not change with implantation time, and biochemical analyses showed no changes in the trend of collagen and elastin content with implantation time or location of the vascular wall. We hypothesize that the collagen fibers on the adventitial side of the arterial wall and behind the stent straighten in response to the arterial stretch caused by oversizing of the stent. However, the collagen organization on the luminal side suggests that stent-induced remodeling is dominated by contact guidance. © 2016 S. Karger AG, Basel.

Fabrication of microgrooves with excimer laser ablation techniques for plastic optical fiber array alignment purposes

NASA Astrophysics Data System (ADS)

Naessens, Kris; Van Hove, An; Coosemans, Thierry; Verstuyft, Steven; Ottevaere, Heidi; Vanwassenhove, Luc; Van Daele, Peter; Baets, Roel G.

2000-06-01

Laser ablation is extremely well suited for rapid prototyping and proves to be a versatile technique delivering high accuracy dimensioning and repeatability of features in a wide diversity of materials. In this paper, we present laser ablation as a fabrication method for micro machining in of arrays consisting of precisely dimensioned U-grooves in dedicated polycarbonate and polymethylmetacrylate plates. The dependency of the performance on various parameters is discussed. The fabricated plates are used to hold optical fibers by means of a UV-curable adhesive. Stacking and gluing of the plates allows the assembly of a 2D connector of plastic optical fibers for short distance optical interconnects.

Vertically aligned cobalt hydroxide nano-flake coated electro-etched carbon fiber cloth electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Cheng, Qian; Tang, Jie; Zhang, Han; Qin, Lu-Chang

2014-11-01

We describe preparation and characterization of nanostructured electrodes using Co(OH)2 nano-flakes and carbon fiber cloth for supercapacitors. Nanostructured Co(OH)2 flakes are produced by electrodeposition and they are coated onto the electro-etched carbon fiber cloth. A highest specific capacitance of 3404.8 F g-1 and an area-normalized specific capacitance of 3.3 F cm-2 have been obtained from such electrodes. Morphology and structure of the nanostructured electrodes have been characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties have been studied by cyclic voltammetry (CV), constant-current charge and discharge, electrochemical impedance spectroscopy (EIS), and long-time cycling.

Calibration results using highly aberrated images for aligning the JWST instruments to the telescope

NASA Astrophysics Data System (ADS)

Smith, Koby Z.; Acton, D. Scott; Gallagher, Ben B.; Knight, J. Scott; Dean, Bruce H.; Jurling, Alden S.; Zielinski, Thomas P.

2016-07-01

The James Webb Space Telescope (JWST) project is an international collaboration led by NASA's Goddard Space Flight Center (GSFC) in Greenbelt, MD. JWST is NASA's flagship observatory that will operate nearly a million miles away from Earth at the L2 Lagrange point. JWST's optical design is a three-mirror anastigmat with four main optical components; 1) the eighteen Primary Mirror Segment Assemblies (PMSA), 2) a single Secondary Mirror Assembly (SMA), 3) an Aft-Optics Subsystem (AOS) consisting of a Tertiary Mirror and Fine Steering Mirror, and 4) an Integrated Science Instrument Module consisting of the various instruments for JWST. JWST's optical system has been designed to accommodate a significant amount of alignment capability and risk with the PMSAs and SMA having rigid body motion available on-orbit just for alignment purposes. However, the Aft-Optics Subsystem (AOS) and Integrated Science Instrument Module (ISIM) are essentially fixed optical subsystems within JWST, and therefore the cryogenic alignment of the AOS to the ISIM is critical to the optical performance and mission success of JWST. In support of this cryogenic alignment of the AOS to ISIM, an array of fiber optic sources, known as the AOS Source Plate Assembly (ASPA), are placed near the intermediate image location of JWST (between the secondary and tertiary mirrors) during thermal vacuum ground-test operations. The AOS produces images of the ASPA fiber optic sources at the JWST focal surface location, where they are captured by the various science instruments. In this manner, the AOS provides an optical yardstick by which the instruments within ISIM can evaluate their relative positions to and the alignment of the AOS to ISIM can be quantified. However, since the ASPA is located at the intermediate image location of the JWST three-mirror anastigmat design, the images of these fiber optic sources produced by the AOS are highly aberrated with approximately 2-3μm RMS wavefront error consisting mostly of 3rd-order astigmatism and coma. This is because the elliptical tertiary mirror of the AOS is used off of its ideal foci locations without the compensating wavefront effects of the JWST primary and secondary mirrors. Therefore, the PSFs created are highly asymmetric with relatively complex structure and the centroid and encircled energy analyses traditionally used to locate images are not sufficient for ensuring the AOS to ISIM alignment. A novel approach combining phase retrieval and spatial metrology was developed to both locate the images with respect to the AOS and provide calibration information for eventual AOS to ISIM alignment verification. During final JWST OTE and ISIM (OTIS) testing, only a single thru-focus image will be collected by the instruments. Therefore, tools and processes were developed to perform single-image phase retrieval on these highly aberrated images such that any single image of the ASPA source can provide calibrated knowledge of the instruments' position relative to the AOS. This paper discusses the results of the methodology, hardware, and calibration performed to ensure that the AOS and ISIM are aligned within their respective tolerances at JWST OTIS testing.

Mechanisms of nascent fiber formation during avian skeletal muscle hypertrophy

NASA Technical Reports Server (NTRS)

McCormick, K. M.; Schultz, E.

1992-01-01

This study examined two putative mechanisms of new fiber formation in postnatal skeletal muscle, namely longitudinal fragmentation of existing fibers and de novo formation. The relative contributions of these two mechanisms to fiber formation in hypertrophying anterior latissimus dorsi (ALD) muscle were assessed by quantitative analysis of their nuclear populations. Muscle hypertrophy was induced by wing-weighting for 1 week. All nuclei formed during the weighting period were labeled by continuous infusion of 5-bromo-2'-deoxyuridine (BrdU), a thymidine analog, and embryonic-like fibers were identified using an antibody to ventricular-like embryonic (V-EMB) myosin. The number of BrdU-labeled and unlabeled nuclei in V-EMB-positive fibers were counted. Wing-weighting resulted in significant muscle enlargement and the appearance of many V-EMB+ fibers. The majority of V-EMB+ fibers were completely independent of mature fibers and had a nuclear density characteristics of developing fibers. Furthermore, nearly 100% of the nuclei in independent V-EMB+ fibers were labeled. These findings strongly suggest that most V-EMB+ fibers were nascent fibers formed de novo during the weighting period by satellite cell activation and fusion. Nascent fibers were found primarily in the space between fascicles where they formed a complex anastomosing network of fibers running at angles to one another. Although wing-weighting induced an increase in the number of branched fibers, there was no evidence that V-EMB+ fibers were formed by longitudinal fragmentation. The location of newly formed fibers in wing-weighted and regenerating ALD muscle was compared to determine whether satellite cells in the ALD muscle were unusual in that, if stimulated to divide, they would form fibers in the inter- and intrafascicular space. In contrast to wing-weighted muscle, nascent fibers were always found closely associated with necrotic fibers. These results suggest that wing-weighting is not simply another model of regeneration, but rather produces a unique environment which induces satellite cell migration and subsequent fiber formation in the interfascicular space. De novo fiber formation is apparently the principal mechanism for the hyperplasia reported to occur in the ALD muscle undergoing hypertrophy induced by wing-weighting.

Role of Mutagenicity in Asbestos Fiber-Induced Carcinogenicity and Other Diseases

PubMed Central

Huang, Sarah X. L.; Jaurand, Marie-Claude; Kamp, David W.; Whysner, John; Hei, Tom K.

2011-01-01

The cellular and molecular mechanisms of how asbestos fibers induce cancers and other diseases are not well understood. Both serpentine and amphibole asbestos fibers have been shown to induce oxidative stress, inflammatory responses, cellular toxicity and tissue injuries, genetic changes, and epigenetic alterations in target cells in vitro and tissues in vivo. Most of these mechanisms are believe to be shared by both fiber-induced cancers and noncancerous diseases. This article summarizes the findings from existing literature with a focus on genetic changes, specifically, mutagenicity of asbestos fibers. Thus far, experimental evidence suggesting the involvement of mutagenesis in asbestos carcinogenicity is more convincing than asbestos-induced fibrotic diseases. The potential contributions of mutagenicity to asbestos-induced diseases, with an emphasis on carcinogenicity, are reviewed from five aspects: (1) whether there is a mutagenic mode of action (MOA) in fiber-induced carcinogenesis; (2) mutagenicity/carcinogenicity at low dose; (3) biological activities that contribute to mutagenicity and impact of target tissue/cell type; (4) health endpoints with or without mutagenicity as a key event; and finally, (5) determinant factors of toxicity in mutagenicity. At the end of this review, a consensus statement of what is known, what is believed to be factual but requires confirmation, and existing data gaps, as well as future research needs and directions, is provided. PMID:21534089

Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

PubMed

Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

2015-01-01

The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

Smooth Muscle-Like Tissue Constructs with Circumferentially Oriented Cells Formed by the Cell Fiber Technology

PubMed Central

Hsiao, Amy Y.; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

2015-01-01

The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774