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

Cryo-transmission electron microscopy structure of a gigadalton peptide fiber of de novo design

PubMed Central

Sharp, Thomas H.; Bruning, Marc; Mantell, Judith; Sessions, Richard B.; Thomson, Andrew R.; Zaccai, Nathan R.; Brady, R. Leo; Verkade, Paul; Woolfson, Derek N.

2012-01-01

Nature presents various protein fibers that bridge the nanometer to micrometer regimes. These structures provide inspiration for the de novo design of biomimetic assemblies, both to address difficulties in studying and understanding natural systems, and to provide routes to new biomaterials with potential applications in nanotechnology and medicine. We have designed a self-assembling fiber system, the SAFs, in which two small α-helical peptides are programmed to form a dimeric coiled coil and assemble in a controlled manner. The resulting fibers are tens of nm wide and tens of μm long, and, therefore, comprise millions of peptides to give gigadalton supramolecular structures. Here, we describe the structure of the SAFs determined to approximately 8 Å resolution using cryotransmission electron microscopy. Individual micrographs show clear ultrastructure that allowed direct interpretation of the packing of individual α-helices within the fibers, and the construction of a 3D electron density map. Furthermore, a model was derived using the cryotransmission electron microscopy data and side chains taken from a 2.3 Å X-ray crystal structure of a peptide building block incapable of forming fibers. This was validated using single-particle analysis techniques, and was stable in prolonged molecular-dynamics simulation, confirming its structural viability. The level of self-assembly and self-organization in the SAFs is unprecedented for a designed peptide-based material, particularly for a system of considerably reduced complexity compared with natural proteins. This structural insight is a unique high-resolution description of how α-helical fibrils pack into larger protein fibers, and provides a basis for the design and engineering of future biomaterials. PMID:22847414

Highly phosphorescent hollow fibers inner-coated with tungstate nanocrystals

NASA Astrophysics Data System (ADS)

Ng, Pui Fai; Bai, Gongxun; Si, Liping; Lee, Ka I.; Hao, Jianhua; Xin, John H.; Fei, Bin

2017-12-01

In order to develop luminescent microtubes from natural fibers, a facile biomimetic mineralization method was designed to introduce the CaWO4-based nanocrystals into kapok lumens. The structure, composition, and luminescence properties of resultant fibers were investigated with microscopes, x-ray diffraction, thermogravimetric analysis, and fluorescence spectrometry. The yield of tungstate crystals inside kapok was significantly promoted with a process at high temperature and pressure—the hydrothermal treatment. The tungstate crystals grown on the inner wall of kapok fibers showed the same crystal structure with those naked powders, but smaller in crystal size. The resultant fiber assemblies demonstrated reduced phosphorescence intensity in comparison to the naked tungstate powders. However, the fibers gave more stable luminescence than the naked powders in wet condition. This approach explored the possibility of decorating natural fibers with high load of nanocrystals, hinting potential applications in anti-counterfeit labels, security textiles, and even flexible and soft optical devices.

A new approach for high performance fiber manufacturing via simultaneous fiber spinning and UV initiated polymerization

NASA Astrophysics Data System (ADS)

Ellison, Chris

Synthetic fibers have been manufactured for decades using solvents or heat to reduce the viscosity of pre-formed polymers and promote drawing. However, nature has engineered spiders and silkworms with benign ways of making silk fibers with high strength and toughness. Conceptually, their approach of chemically linking small functional units (i.e., proteins) into long chain molecules and solid fibrillar structures ``on-demand'' is fundamentally different from current synthetic fiber manufacturing methods. Drawing inspiration from nature, a method will be described that uses light to trigger a thiol-ene photopolymerization to rapidly transform reactive liquid mixtures into solid thread-like structures as they are forced out of a capillary at high speeds. Besides being manufactured without using solvents/volatile components or heat, these fibers are mechanically robust and have excellent chemical and thermal stability due to their crosslinked nature. During processing, the balance between curing kinetics, fiber flight time, and monomer mixture viscoelasticity is essential for the formation of defect free fibers. This work focuses on developing a universal operating diagram to show how the intricate interplay of gel time, flight time, and fluid relaxation time leads to the formation of uniform fibers and other undesirable fiber morphologies such as beads-on-string, fused fibers, non-uniform fibers, and droplets. This predictive capability enables adaptation of this spinning concept to all existing fiber spinning platforms, and customization of monomer formulations to target desired properties.

Amyloid fibril formation from sequences of a natural beta-structured fibrous protein, the adenovirus fiber.

PubMed

Papanikolopoulou, Katerina; Schoehn, Guy; Forge, Vincent; Forsyth, V Trevor; Riekel, Christian; Hernandez, Jean-François; Ruigrok, Rob W H; Mitraki, Anna

2005-01-28

Amyloid fibrils are fibrous beta-structures that derive from abnormal folding and assembly of peptides and proteins. Despite a wealth of structural studies on amyloids, the nature of the amyloid structure remains elusive; possible connections to natural, beta-structured fibrous motifs have been suggested. In this work we focus on understanding amyloid structure and formation from sequences of a natural, beta-structured fibrous protein. We show that short peptides (25 to 6 amino acids) corresponding to repetitive sequences from the adenovirus fiber shaft have an intrinsic capacity to form amyloid fibrils as judged by electron microscopy, Congo Red binding, infrared spectroscopy, and x-ray fiber diffraction. In the presence of the globular C-terminal domain of the protein that acts as a trimerization motif, the shaft sequences adopt a triple-stranded, beta-fibrous motif. We discuss the possible structure and arrangement of these sequences within the amyloid fibril, as compared with the one adopted within the native structure. A 6-amino acid peptide, corresponding to the last beta-strand of the shaft, was found to be sufficient to form amyloid fibrils. Structural analysis of these amyloid fibrils suggests that perpendicular stacking of beta-strand repeat units is an underlying common feature of amyloid formation.

Natural Kenaf Fiber Reinforced Composites as Engineered Structural Materials

NASA Astrophysics Data System (ADS)

Dittenber, David B.

The objective of this work was to provide a comprehensive evaluation of natural fiber reinforced polymer (NFRP)'s ability to act as a structural material. As a chemical treatment, aligned kenaf fibers were treated with sodium hydroxide (alkalization) in different concentrations and durations and then manufactured into kenaf fiber / vinyl ester composite plates. Single fiber tensile properties and composite flexural properties, both in dry and saturated environments, were assessed. Based on ASTM standard testing, a comparison of flexural, tensile, compressive, and shear mechanical properties was also made between an untreated kenaf fiber reinforced composite, a chemically treated kenaf fiber reinforced composite, a glass fiber reinforced composite, and oriented strand board (OSB). The mechanical properties were evaluated for dry samples, samples immersed in water for 50 hours, and samples immersed in water until saturation (~2700 hours). Since NFRPs are more vulnerable to environmental effects than synthetic fiber composites, a series of weathering and environmental tests were conducted on the kenaf fiber composites. The environmental conditions studied include real-time outdoor weathering, elevated temperatures, immersion in different pH solutions, and UV exposure. In all of these tests, degradation was found to be more pronounced in the NFRPs than in the glass FRPs; however, in nearly every case the degradation was less than 50% of the flexural strength or stiffness. Using a method of overlapping and meshing discontinuous fiber ends, large mats of fiber bundles were manufactured into composite facesheets for structural insulated panels (SIPs). The polyisocyanurate foam cores proved to be poorly matched to the strength and stiffness of the NFRP facesheets, leading to premature core shear or delamination failures in both flexure and compressive testing. The NFRPs were found to match well with the theoretical stiffness prediction methods of classical lamination theory, finite element method, and Castigliano's method in unidirectional tension and compression, but are less accurate for the more bond-dependent flexural and shear properties. With the acknowledged NFRP matrix bonding issues, the over-prediction of these theoretical models indicates that the flexural stiffness of the kenaf composite may be increased by up to 40% if a better bond between the fiber and matrix can be obtained. The sustainability of NFRPs was examined from two perspectives: environmental and socioeconomic. While the kenaf fibers themselves possess excellent sustainability characteristics, costing less while possessing a lesser environmental impact than the glass fibers, the vinyl ester resin used in the composites is environmentally hazardous and inflated the cost and embodied energy of the composite SIPs. Consistent throughout all the designs was a correlation between the respective costs of the raw materials and the respective environmental impacts. The socioeconomic study looked at the sustainability of natural fiber reinforced composite materials as housing materials in developing countries. A literature study on the country of Bangladesh, where the fibers in this study were grown, showed that the jute and kenaf market would benefit from the introduction of a value-added product like natural fiber composites. The high rate of homeless and inadequately housed in Bangladesh, as well as in the US and throughout the rest of the world, could be somewhat alleviated if a new, affordable, and durable material were introduced. While this study found that natural fiber composites possess sufficient mechanical properties to be adopted as primary structural members, the two major remaining hurdles needing to be overcome before natural fiber composites can be adopted as housing materials are the cost and sustainability of the resin system and the moisture resistance/durability of the fibers. (Abstract shortened by UMI.)

Structure and morphology of regenerated silk nano-fibers produced by electrospinning

NASA Astrophysics Data System (ADS)

Zarkoob, Shahrzad

The impressive physical and mechanical properties of natural silk fiberssp1 and the possibility of producing these proteins using biotechnology,sp2 have provided the impetus for recent efforts in both the biosynthesissp{3,4} and the spinning of these protein based biopolymers.sp{5,6,7} The question still remains: whether fibers spun from solutions with similar chemical makeup can produce fibers with similar structures and therefore with the possibility of improved properties. Since genetically engineered silk solutions were not readily available, the first objective of this project was to completely dissolve the Bombyx mori cocoon and the Nephila clavipes dragline silk while maintaining the molecular weight integrity of the polymer. The second objective was to develop a system for re-spinning from very small amount of the resulting silk solutions by the process of electrospinning. The third objective was, to produce regenerated silk fibers with diameters that are several orders of magnitude smaller than the original fibers, suitable for direct observation and analysis by transmission electron microscopy and electron diffraction. And finally, to compare these results to structural information obtained from natural (as spun by the organism) fibers to see if the regenerated solutions are able to form the same structure as the original fibers. Both types of silk fibers were successfully dissolved while maintaining the polymer integrity. Small quantities (25-50 mul) of these solutions were used to electrospin fibers with diameters ranging from 8nm-200nm. The fibers were observed by optical, scanning electron, and transmission electron microscopy. These nano fibers showed optical retardation, appeared to have a circular cross-section, and were dimensionally stable at temperatures above 280sp°C. Electron diffraction patterns of annealed electrospun fibers of B. mori and N. clavipes showed reflections, demonstrating orientational and semicrystalline order in the material comparable to natural silk. In addition, electron diffraction was also obtained form extended microtomed single dragline fibers of N. clavipes, and the d-spacings agreed well with thoes obtained from WAXD of dragline fiber bundles.

Probabilistic analysis of the behavior of polymer matrix composite materials reinforced by different types of fibers

NASA Astrophysics Data System (ADS)

Harb, N.; Bezzazi, B.; Mehraz, S.; Hamitouche, K.; Dilmi, H.

2017-11-01

The requests of lightening of the structures and gains in performance lead to search for new materials and the associated processes for aeronautical and space applications. Long-fiber composites have been used for many years for these applications; they make it possible to reduce the mass of the structures because of their excellent compromise of mass/rigidity / resistance. The materials in general contain defects which are essentially due to their nature and their mode of elaboration. To this purpuse, we carried out a probabilistic analysis of the mechanical behavior in three-point bending of composite materials with a thermosetting matrix in order to highlight the influence of the number of folds of the fibers and the nature of the fibers on the dispersion of the defects in the stratified structures fiberglass, carbon fiber laminates and hybrid (carbon / glass) laminates. From the results obtained, the dispersion of the defects is lower in the laminates of greater number of plies of the fibers and the hybrid laminates; the more the number of folds increases the more the mechanical characteristics increase; the hybrid laminates exhibit better mechanical properties compared to laminates of the same type of fiber. Finally, a morphological analysis of fracture structures and facies was investigated by scanning electron microscope (SEM) observations.

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.

Biological natural retting for determining the hierarchical structuration of banana fibers.

PubMed

Gañán, Piedad; Zuluaga, Robin; Velez, Juan Manuel; Mondragon, Iñaki

2004-10-20

Extraction processes of natural fibers can be performed by different procedures that include mechanical, chemical and biological methods. Each method presents different advantages or drawbacks according to the amount of fiber produced or the quality and properties of fiber bundles obtained. In this study, biological natural retting was satisfactorily used for obtaining banana fibers from plant bunches. However, the most important contribution of this work refers to the description of the hierarchical microstructural ordering present in banana fiber bundles in both bundle surface and inner region. The chemical composition of banana fiber bundles has been evaluated by FTIR spectroscopy. Through exposure time, the fiber bundle configuration presents small variations in composition. The main changes are related to hemicellulose and pectins as they conform the outer walls of the bundle. Hierarchical helicoidal ordering in the bundle surface as well as orientation on the longitudinal axis of the bundle were observed by optical microscopy (OM) and scanning electron microscopy (SEM) for 3-4 microm surface fibers and 10-15 microm inner elementary fibers, respectively. With increasing exposure time, fiber bundle walls lose integrity, as reflected in their mechanical behavior.

Hybrid Aluminum and Natural Fiber Composite Structure for Crash Safety Improvement

NASA Astrophysics Data System (ADS)

Helaili, S.; Chafra, M.; Chevalier, Y.

There is a growing interest on pedestrian's protection in automotive safety standards. Pedestrians head impact is one of the most important tests. In this paper, a hybrid composite structure made from natural fiber and aluminum, which improve the head protection when impact is taken place, is presented. The structure is made from a honeycomb composite made from unidirectional and woven composites and a thin aluminum layer. A head impact model is developed. The number of hexagonal layers is fixed and the thickness of the aluminum layer of the honeycomb structure is varied. The specific absorption energy is then calculated.

Structure/function relations of hemostatic nonwoven dressings based on greige cotton

USDA-ARS?s Scientific Manuscript database

A variety of natural and synthetic fibers are employed in hemostatic dressings. Here we demonstrate the use of greige cotton as a functional fiber, which when combined with hydrophilic and hydrophobic fibers in hydroentangled nonwoven materials, promotes accelerated clotting. A biophysical approach...

Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites.

PubMed

Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

2012-01-01

Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades.

Review of natural fiber composites

NASA Astrophysics Data System (ADS)

Rohan, T.; Tushar, B.; T, Mahesha G.

2018-02-01

Development of new alternative materials to the existing traditional metals, alloys and synthetic materials is the new buzz in recent research activities at the academic and industrial level taking place all over the world. Earning carbon credits by minimizing the atmospheric pollution is getting an increase in attention by industries. One small step to conserve the atmosphere around us is to use natural resources in making fully bio degradable or partially bio degradable composite materials. Such prepared alternative materials can find applications in interior housing, automotive, marine, domestic, and other applications. Composites made by using appropriate natural fibers as reinforcements is a possibility that ensures such a reality as they can be well received in multiple disciplines of engineering. Results published from various research activities illustrates that natural fiber composites can successfully be adapted for non-structural, moderate load bearing indoor applications. Further, the few deficiencies in the natural fibers can be overcome by subjecting them to morphological changes by various physical or chemical treatment methods. The overall objective of this paper is to provide a comprehensive overview of the property profiles of Natural Fiber Composites.

Photonic-structured fibers assembled from cellulose nanocrystals with tunable polarized selective reflection.

PubMed

Meng, Xin; Pan, Hui; Lu, Tao; Chen, Zhixin; Chen, Yanru; Zhang, Di; Zhu, Shenmin

2018-08-10

Fibers with self-assembled photonic structures are of special interest due to their unique photonic properties and potential applications in the smart textile industry. Inspired by nature, the photonic-structured fibers were fabricated through the self-assembly of chiral nematic cellulose nanocrystals (CNCs) and the fibers showed tunably brilliant and selectively reflected colors under crossed-polarization. A simple wet-spinning method was applied to prepare composite fibers of the mixed CNC matrix and polyvinyl alcohol (PVA) additions. During the processing, a cholesteric CNC phase formed photonic fibers through a self-assembly process. The selective color reflection of the composite fibers in the polarized condition showed a typical red-shift tendency with an increase in the PVA content, which was attributed to the increased helical pitch of the CNC. Furthermore, the polarized angle could also alter the reflected colors. Owing to their excellent selective reflection properties under the polarized condition, CNC-based photonic fibers are promising as the next-generation of smart fibers, applied in the fields of specific display and sensing.

ALL NATURAL COMPOSITE SANDWICH BEAMS FOR STRUCTURAL APPLICATIONS. (R829576)

EPA Science Inventory

As part of developing an all natural composite roof for housing application,
structural panels and unit beams were manufactured out of soybean oil based resin
and natural fibers (flax, cellulose, pulp, recycled paper, chicken feathers)
using vacuum assisted resin tran...

Exploring the atomic structure and conformational flexibility of a 320 Å long engineered viral fiber using X-ray crystallography.

PubMed

Bhardwaj, Anshul; Casjens, Sherwood R; Cingolani, Gino

2014-02-01

Protein fibers are widespread in nature, but only a limited number of high-resolution structures have been determined experimentally. Unlike globular proteins, fibers are usually recalcitrant to form three-dimensional crystals, preventing single-crystal X-ray diffraction analysis. In the absence of three-dimensional crystals, X-ray fiber diffraction is a powerful tool to determine the internal symmetry of a fiber, but it rarely yields atomic resolution structural information on complex protein fibers. An 85-residue-long minimal coiled-coil repeat unit (MiCRU) was previously identified in the trimeric helical core of tail needle gp26, a fibrous protein emanating from the tail apparatus of the bacteriophage P22 virion. Here, evidence is provided that an MiCRU can be inserted in frame inside the gp26 helical core to generate a rationally extended fiber (gp26-2M) which, like gp26, retains a trimeric quaternary structure in solution. The 2.7 Å resolution crystal structure of this engineered fiber, which measures ∼320 Å in length and is only 20-35 Å wide, was determined. This structure, the longest for a trimeric protein fiber to be determined to such a high resolution, reveals the architecture of 22 consecutive trimerization heptads and provides a framework to decipher the structural determinants for protein fiber assembly, stability and flexibility.

Mechanical and Thermal Characterization of Alkali Treated Kenaf Fibers

NASA Astrophysics Data System (ADS)

Abdullah, S. A. S.; Zuhudi, N. Z. M.; Anuar, NIS; Isa, M. D.

2018-05-01

Research on bio composite for automotive and aerospace application has been extensive with the advancement of natural fiber yarn and woven technology. Malaysia has marked kenaf as its main crop commodity by 2020. Surface modification of natural fibers is one of the significant areas in current biocomposite research. Alkali treatment removes certain amount of lignin, hemicellulose, and wax on the surface of fiber, besides depolymerizing cellulose structure and increasing percentage of crystallinity. Surface modification with NaOH of 3%, 6% and 9% concentration with various lengths of immersion time was conducted. The effect of alkali treatment on the mechanical strength and thermal degradation of kenaf fibre were investigated by means of fiber bundle tensile test and thermogravimetric analyser (TGA). Alkali treatment strongly modifies the thermal behaviour of the fibers, being particularly effective in the removal of noncellulosic matter. In addition, the mechanical properties of kenaf fibers revealed higher tensile strength for NaOH treated fibers.

The study about the use of the natural fibres in composite materials

NASA Astrophysics Data System (ADS)

Hristian, L.; Ostafe, M. M.; Manea, L. R.; Leon, A. L.

2016-08-01

The current technological development, the crises of raw materials and energy, the increased aggression towards the environment have led to the development of the new materials and unconventional technologies. The composite materials have both many important advantages compared to the traditional materials and provide many functional advantages: low weight, mechanical resistance, low maintenance costs. The main advantage of the composites lies in their ability to combine the physical properties of components to achieve new structural functionalities, so the modulation of the properties and finally, to obtain a wide variety of materials which may be used in all areas of activities. Some biodegradable fibers, flax, hemp, may provide the specific mechanical properties compared to those of the glass fiber, due to their high strength and low density of their volume. To make the right choice, even if the natural fibers have very low power consumption compared with the synthetic fibers, such as glass or carbon, it should be considered a careful assessment of the environmental impact. The present study shows that the validity of the replacement of the synthetic fibers with natural fibers, depends on the reinforcement type and the complexity of the problems due to the processing of natural fibers.

Exploring the atomic structure and conformational flexibility of a 320 Å long engineered viral fiber using X-ray crystallography

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

Bhardwaj, Anshul; Casjens, Sherwood R.; Cingolani, Gino, E-mail: gino.cingolani@jefferson.edu

2014-02-01

This study presents the crystal structure of a ∼320 Å long protein fiber generated by in-frame extension of its repeated helical coiled-coil core. Protein fibers are widespread in nature, but only a limited number of high-resolution structures have been determined experimentally. Unlike globular proteins, fibers are usually recalcitrant to form three-dimensional crystals, preventing single-crystal X-ray diffraction analysis. In the absence of three-dimensional crystals, X-ray fiber diffraction is a powerful tool to determine the internal symmetry of a fiber, but it rarely yields atomic resolution structural information on complex protein fibers. An 85-residue-long minimal coiled-coil repeat unit (MiCRU) was previously identifiedmore » in the trimeric helical core of tail needle gp26, a fibrous protein emanating from the tail apparatus of the bacteriophage P22 virion. Here, evidence is provided that an MiCRU can be inserted in frame inside the gp26 helical core to generate a rationally extended fiber (gp26-2M) which, like gp26, retains a trimeric quaternary structure in solution. The 2.7 Å resolution crystal structure of this engineered fiber, which measures ∼320 Å in length and is only 20–35 Å wide, was determined. This structure, the longest for a trimeric protein fiber to be determined to such a high resolution, reveals the architecture of 22 consecutive trimerization heptads and provides a framework to decipher the structural determinants for protein fiber assembly, stability and flexibility.« less

Effect of Manufacturing Method to Tensile Properties of Hybrid Composite Reinforced by Natural (Agel Leaf Fiber) and Glass Fibers

NASA Astrophysics Data System (ADS)

Nugroho, A.; Abdurohman, K.; Kusmono; Hestiawan, H.; Jamasri

2018-04-01

This paper described the effect of different type of manufacturing method to tensile properties of hybrid composite woven agel leaf fiber and glass fiber as an alternative of LSU structure material. The research was done by using 3 ply of woven agel leaf fiber (ALF) and 3 ply of glass fiber (wr200) while the matrix was using unsaturated polyester. Composite manufacturing method used hand lay-up and vacuum bagging. Tensile test conducted with Tensilon universal testing machine, specimen shape and size according to standard size ASTM D 638. Based on tensile test result showed that the tensile strength of agel leaf fiber composite with unsaturated polyester matrix is 54.5 MPa by hand lay-up and 84.6 MPa with vacuum bagging method. From result of tensile test, hybrid fiber agel composite and glass fiber with unsaturated polyester matrix have potential as LSU structure.

Silkworm cocoons inspire models for random fiber and particulate composites

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

Chen Fujia; Porter, David; Vollrath, Fritz

The bioengineering design principles evolved in silkworm cocoons make them ideal natural prototypes and models for structural composites. Cocoons depend for their stiffness and strength on the connectivity of bonding between their constituent materials of silk fibers and sericin binder. Strain-activated mechanisms for loss of bonding connectivity in cocoons can be translated directly into a surprisingly simple yet universal set of physically realistic as well as predictive quantitative structure-property relations for a wide range of technologically important fiber and particulate composite materials.

Silkworm cocoons inspire models for random fiber and particulate composites

NASA Astrophysics Data System (ADS)

Chen, Fujia; Porter, David; Vollrath, Fritz

2010-10-01

The bioengineering design principles evolved in silkworm cocoons make them ideal natural prototypes and models for structural composites. Cocoons depend for their stiffness and strength on the connectivity of bonding between their constituent materials of silk fibers and sericin binder. Strain-activated mechanisms for loss of bonding connectivity in cocoons can be translated directly into a surprisingly simple yet universal set of physically realistic as well as predictive quantitative structure-property relations for a wide range of technologically important fiber and particulate composite materials.

Shrinkage modeling of concrete reinforced by palm fibres in hot dry environments

NASA Astrophysics Data System (ADS)

Akchiche, Hamida; Kriker, Abdelouahed

2017-02-01

The cement materials, such as concrete and conventional mortar present very little resistance to traction and cracking, these hydraulic materials which induces large withdrawals on materials and cracks in structures. The hot dry environments such as: the Saharan regions of Algeria, Indeed, concrete structures in these regions are very fragile, and present high shrinkage. Strengthening of these materials by fibers can provide technical solutions for improving the mechanical performance. The aim of this study is firstly, to reduce the shrinkage of conventional concrete with its reinforcement with date palm fibers. In fact, Algeria has an extraordinary resources in natural fibers (from Palm, Abaca, Hemp) but without valorization in practical areas, especially in building materials. Secondly, to model the shrinkage behavior of concrete was reinforced by date palm fibers. In the literature, several models for still fiber concrete were founded but few are offers for natural fiber concretes. To do so, a still fiber concretes model of YOUNG - CHERN was used. According to the results, a reduction of shrinkage with reinforcement by date palm fibers was showed. A good ability of molding of shrinkage of date palm reinforced concrete with YOUNG - CHERN Modified model was obtained. In fact, a good correlation between experimental data and the model data was recorded.

Dynamic Structural Health Monitoring of slender structures using optical sensors.

PubMed

Antunes, Paulo; Travanca, Rui; Rodrigues, Hugo; Melo, José; Jara, José; Varum, Humberto; André, Paulo

2012-01-01

In this paper we summarize the research activities at the Instituto de Telecomunicações--Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures' natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior.

Hole-pin joining structure with fiber-round-hole distribution of lobster cuticle and biomimetic study.

PubMed

Chen, Bin; Fan, Jinghong; Gou, Jihua; Lin, Shiyun

2014-12-01

Observations of the cuticle of the Boston Spiny Lobster using scanning electron microscope (SEM) show that it is a natural biocomposite consisting of chitin fibers and sclerotic-protein matrix with hierarchical and helicoidal structure. The SEM images also indicate that there is a hole-pin joining structure in the cuticle. In this joining structure, the chitin fibers in the neighborhood of the joining holes continuously round the holes to form a fiber-round-hole distribution. The maximum pullout force of the fibers in the fiber-round-hole distribution, which is closely related to the fracture toughness of the cuticle, is investigated and compared with that of the fibers in non-fiber-round-hole distribution based on their representative models. It is revealed that the maximum pullout force of the fibers in the fiber-round-hole distribution is significantly larger than that of the fibers in the non-fiber-round-hole distribution, and that a larger diameter of the hole results in a larger difference in the maximum pullout forces of the fibers between the two kinds of the fiber distributions. Inspired by the fiber-round-hole distribution found in the cuticle, composite specimens with the fiber-round-hole distribution were fabricated with a special mold and process to mirror the fiber-round-hole distribution. The fracture toughness of the biomimetic composite specimens is tested and compared with that of the conventional composite specimens with the non-fiber-round-hole distribution. It is demonstrated that the fracture toughness of the biomimetic composite specimens with the fiber-round-hole distribution is significantly larger than that of the conventional composite specimens with the non-fiber-round-hole distribution. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamic Structural Health Monitoring of Slender Structures Using Optical Sensors

PubMed Central

Antunes, Paulo; Travanca, Rui; Rodrigues, Hugo; Melo, José; Jara, José; Varum, Humberto; André, Paulo

2012-01-01

In this paper we summarize the research activities at the Instituto de Telecomunicações—Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures' natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior. PMID:22778661

Control of fibroin conformation: Toward the development of a biomimetic spinning process for silk fibers

NASA Astrophysics Data System (ADS)

Carlson, Kimberly Ann Trabbic

1999-09-01

Nature has shown that silks are sophisticated structural materials with remarkable mechanical properties; however, they are produced using far milder conditions than high-performance synthetic polymer fibers. While recent advances in molecular biotechnology have taken great strides toward the production of proteinaceous biopolymers, little is known about the processing conditions needed to spin fibers with the correct microstructures and mechanical properties. It is the purpose of this research to gain a fundamental understanding about how processing conditions affect the molecular structure of a model protein biopolymer, Bombyx mori silkworm fibroin, the structural protein of cocoon silk. Fibers of B. mori fibroin were wet spun from 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) into a methanol coagulation bath. X-ray fiber diffraction and quantitative Raman spectroscopy were used to determine that both naturally- and synthetically-spun fibers contain a high degree of beta-sheet (~50%). Fibers subjected to a post-spinning draw exhibited a preferential molecular alignment parallel to the fiber axis resulting in increased strength, stiffness, and extensibility. Fibers with microstructures and mechanical properties most similar to those of naturally-spun fibers were reproduced in synthetically-spun fibers with a draw ratio of 3.5. The transformation of helical fibroin in HFIP to beta-sheet sheet fibroin in synthetically-spun fibers was determined to be caused by the methanol coagulation bath. The kinetics beta-sheet fibroin crystallization from aqueous solution was investigated by monitoring the sigmoidal progression of gel formation using turbidity and Raman spectroscopy. Gelation kinetics were evaluated by measuring lag time, maximum gelation rate, and optical density to determine the effects of protein concentration, detergent concentration (nucleating agent), headgroup chemistry, ionic strength, pH, and temperature. An optimal molar ratio between SDS and fibroin (100:1) was found to produce gels with minimum lag times and maximum gelation rates. Fluorescence spectroscopy and a two-step denaturation and aggregation model for gelation were used to explore the mechanism of fibroin gelation. Conditions that lead to fibroin expansion (dilute fibroin, low ionic strength, highly charged fibroin, or increased temperature) result in decreased lag times. The results presented in this dissertation should aid in developing biomimetic spinning techniques for proteinaceous, biopolymers through the use of amphiphilic sheet nucleating agents.

Self-Assembly of Large Amyloid Fibers

NASA Astrophysics Data System (ADS)

Ridgley, Devin M.

Functional amyloids found throughout nature have demonstrated that amyloid fibers are potential industrial biomaterials. This work introduces a new "template plus adder" cooperative mechanism for the spontaneous self-assembly of micrometer sized amyloid fibers. A short hydrophobic template peptide induces a conformation change within a highly alpha-helical adder protein to form beta-sheets that continue to assemble into micrometer sized amyloid fibers. This study utilizes a variety of proteins that have template or adder characteristics which suggests that this mechanism may be employed throughout nature. Depending on the amino acid composition of the proteins used the mixtures form amyloid fibers of a cylindrical ( 10 mum diameter, 2 GPa Young's modulus) or tape (5- 10 mum height, 10-20 mum width and 100-200 MPa Young's modulus) morphology. Processing conditions are altered to manipulate the morphology and structural characteristics of the fibers. Spectroscopy is utilized to identify certain amino acid groups that contribute to the self-assembly process. Aliphatic amino acids (A, I, V and L) are responsible for initiating conformation change of the adder proteins to assemble into amyloid tapes. Additional polyglutamine segments (Q-blocks) within the protein mixtures will form Q hydrogen bonds to reinforce the amyloid structure and form a cylindrical fiber of higher modulus. Atomic force microscopy is utilized to delineate the self-assembly of amyloid tapes and cylindrical fibers from protofibrils (15-30 nm width) to fibers (10-20 mum width) spanning three orders of magnitude. The aliphatic amino acid content of the adder proteins' alpha-helices is a good predictor of high density beta-sheet formation within the protein mixture. Thus, it is possible to predict the propensity of a protein to undergo conformation change into amyloid structures. Finally, Escherichia coli is genetically engineered to express a template protein which self-assembles into large amyloid fibers when combined with extracellular myoglobin, an adder protein. The goal of this thesis is to produce, manipulate and characterize the self-assembly of large amyloid fibers for their potential industrial biomaterial applications. The techniques used throughout this study outline various methods to design and engineer amyloid fibers of a tailored modulus and morphology. Furthermore, the mechanisms described here may offer some insight into naturally occurring amyloid forming systems.

Evaluation of ionic liquid treated sisal (agave sisalana) fiber as sorbent in biodiesel spill

NASA Astrophysics Data System (ADS)

Costa, E.; Silva, A.; Mattedi, S.

2018-04-01

The global economic development continually demands the use of energy resources, among which various types of oils are widely used. Despite their undeniable economic importance, environmental accidents with these occur frequently. Thus, the search for efficient and low-cost mitigating measures is recurrent. In this context, techniques that use natural adsorbents, such as vegetable fibers, have been studied, since they combine efficiency, selectivity, low cost and sustainability. Studies have been carried out using various types of fibers, natural or chemically treated. The interest in treating the fiber lies in the fact that, changing the chemical structure of the fiber, its oil sorption capacity is increased. Due to the offered advantages, an alternative and promising type of surface treatment using ionic liquids was performed, to the detriment of traditional treatments. Thus, the technical feasibility of the use of sisal fiber treated with ionic liquid for adsorption of biodiesel was studied.

The effects of corn zein protein coupling agent on mechanical properties of flax fiber reinforced composites

NASA Astrophysics Data System (ADS)

Whitacre, Ryan John

In the field of renewable materials, natural fiber composites demonstrate the capacity to be a viable structural material. When normalized by density, flax fiber mechanical properties are competitive with E-glass fibers. However, the hydrophilic nature of flax fibers reduces the interfacial bond strength with polymer thermosets, limiting composite mechanical properties. Corn zein protein was selected as a natural bio-based coupling agent because of its combination of hydrophobic and hydrophilic properties. Zein was deposited on the surface of flax, which was then processed into unidirectional composite. The mechanical properties of zein treated samples where measured and compared against commonly utilized synthetic treatments sodium hydroxide and silane which incorporate harsh chemicals. Fourier transform infrared spectroscopy, chemical analysis, and scanning electron microscopy were also used to determine analyze zein treatments. Results demonstrate the environmentally friendly zein treatment successfully increased tensile strength 8%, flexural strength 17%, and shear strength 30% compared to untreated samples.

Nondestructive testing of externally reinforced structures for seismic retrofitting using flax fiber reinforced polymer (FFRP) composites

NASA Astrophysics Data System (ADS)

Ibarra-Castanedo, C.; Sfarra, S.; Paoletti, D.; Bendada, A.; Maldague, X.

2013-05-01

Natural fibers constitute an interesting alternative to synthetic fibers, e.g. glass and carbon, for the production of composites due to their environmental and economic advantages. The strength of natural fiber composites is on average lower compared to their synthetic counterparts. Nevertheless, natural fibers such as flax, among other bast fibers (jute, kenaf, ramie and hemp), are serious candidates for seismic retrofitting applications given that their mechanical properties are more suitable for dynamic loads. Strengthening of structures is performed by impregnating flax fiber reinforced polymers (FFRP) fabrics with epoxy resin and applying them to the component of interest, increasing in this way the load and deformation capacities of the building, while preserving its stiffness and dynamic properties. The reinforced areas are however prompt to debonding if the fabrics are not mounted properly. Nondestructive testing is therefore required to verify that the fabric is uniformly installed and that there are no air gaps or foreign materials that could instigate debonding. In this work, the use of active infrared thermography was investigated for the assessment of (1) a laboratory specimen reinforced with FFRP and containing several artificial defects; and (2) an actual FFRP retrofitted masonry wall in the Faculty of Engineering of the University of L'Aquila (Italy) that was seriously affected by the 2009 earthquake. Thermographic data was processed by advanced signal processing techniques, and post-processed by computing the watershed lines to locate suspected areas. Results coming from the academic specimen were compared to digital speckle photography and holographic interferometry images.

Self-Assembling Multi-Component Nanofibers for Strong Bioinspired Underwater Adhesives

PubMed Central

Zhong, Chao; Gurry, Thomas; Cheng, Allen A; Downey, Jordan; Deng, Zhengtao; Stultz, Collin M.; Lu, Timothy K

2014-01-01

Many natural underwater adhesives harness hierarchically assembled amyloid nanostructures to achieve strong and robust interfacial adhesion under dynamic and turbulent environments. Despite recent advances, our understanding of the molecular design, self-assembly, and structure-function relationship of those natural amyloid fibers remains limited. Thus, designing biomimetic amyloid-based adhesives remains challenging. Here, we report strong and multi-functional underwater adhesives obtained from fusing mussel foot proteins (Mfps) of Mytilus galloprovincialis with CsgA proteins, the major subunit of Escherichia coli amyloid curli fibers. These hybrid molecular materials hierarchically self-assemble into higher-order structures, in which, according to molecular dynamics simulations, disordered adhesive Mfp domains are exposed on the exterior of amyloid cores formed by CsgA. Our fibers have an underwater adhesion energy approaching 20.9 mJ/m2, which is 1.5 times greater than the maximum of bio-inspired and bio-derived protein-based underwater adhesives reported thus far. Moreover, they outperform Mfps or curli fibers taken on their own at all pHs and exhibit better tolerance to auto-oxidation than Mfps at pH ≥7.0. This work establishes a platform for engineering multi-component self-assembling materials inspired by nature. PMID:25240674

Durability of pulp fiber-cement composites

NASA Astrophysics Data System (ADS)

Mohr, Benjamin J.

Wood pulp fibers are a unique reinforcing material as they are non-hazardous, renewable, and readily available at relatively low cost compared to other commercially available fibers. Today, pulp fiber-cement composites can be found in products such as extruded non-pressure pipes and non-structural building materials, mainly thin-sheet products. Although natural fibers have been used historically to reinforce various building materials, little scientific effort has been devoted to the examination of natural fibers to reinforce engineering materials until recently. The need for this type of fundamental research has been emphasized by widespread awareness of moisture-related failures of some engineered materials; these failures have led to the filing of national- and state-level class action lawsuits against several manufacturers. Thus, if pulp fiber-cement composites are to be used for exterior structural applications, the effects of cyclical wet/dry (rain/heat) exposure on performance must be known. Pulp fiber-cement composites have been tested in flexure to examine the progression of strength and toughness degradation. Based on scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), energy dispersive spectroscopy (EDS), a three-part model describing the mechanisms of progressive degradation has been proposed: (1) initial fiber-cement/fiber interlayer debonding, (2) reprecipitation of crystalline and amorphous ettringite within the void space at the former fiber-cement interface, and (3) fiber embrittlement due to reprecipitation of calcium hydroxide filling the spaces within the fiber cell wall structure. Finally, as a means to mitigate kraft pulp fiber-cement composite degradation, the effects of partial portland cement replacement with various supplementary cementitious materials (SCMs) has been investigated for their effect on mitigating kraft pulp fiber-cement composite mechanical property degradation (i.e., strength and toughness losses) during wet/dry cycling. SCMs have been found to be effective in mitigating composite degradation through several processes, including a reduction in the calcium hydroxide content, stabilization of monosulfate by maintaining pore solution pH, and a decrease in ettringite reprecipitation accomplished by increased binding of aluminum in calcium aluminate phases and calcium in the calcium silicate hydrate (C-S-H) phase.

Effect of low velocity impact damage on the natural frequency of composite plates

NASA Astrophysics Data System (ADS)

Chok, E. Y. L.; Majid, D. L. A. A.; Harmin, M. Y.

2017-12-01

Biodegradable natural fibers have been suggested to replace the hazardous synthetic fibers in many aerospace applications. However, this notion has been limited due to their low mechanical properties, which leads to the idea of hybridizing the two materials. Many aircraft components such as radome, aft body and wing are highly susceptible to low velocity impact damage while in-service. The damages degrade the structural integrity of the components and change their dynamic characteristics. In worst case scenario, the changes can lead to resonance, which is an excessive vibration. This research is conducted to study the dynamic characteristic changes of low velocity impact damaged hybrid composites that is designed for aircraft radome applications. Three materials, which are glass fiber, kenaf fiber and kenaf/glass fiber hybrid composites, have been impacted with 3J, 6J and 9J of energy. Cantilevered and also vertically clamped boundary conditions are used and the natural frequencies are extracted for each of the specimens. The obtained results show that natural frequency decreases with increasing impact level. Cantilevered condition is found to induce lower modes due to the gravitational pull. To eliminate mass and geometrical effects, normalized modes are computed. Among the three materials considered, glass fiber composites have displayed the highest normalized frequency that reflects on its higher stiffness compared to the other two materials. As the damage level is increased, glass fiber composites have shown the highest frequency reduction to a maximum of 35% while kenaf composites have the least frequency reduction in the range of 1 - 18%. Thus, kenaf fiber is taken to be helpful in stalling the damage progression and reducing the effect of damage. This has been proven when the percentage frequency decrement shown by kenaf/glass fiber composite lies between glass fiber and kenaf fiber composites.

Electrospinning β-SiC fibers from SiC nanoparticles dispersed in various polymer solutions as the electrospinning agents

NASA Astrophysics Data System (ADS)

Fuad, A.; Fatriani, N.; Yogihati, C. I.; Taufiq, A.; Latifah, E.

2018-04-01

Silicon carbide (SiC) fibers were synthesized by electrospinning method from SiC nanoparticles dispersed in polymer solutions, i.e., polyethylene glycol (PEG) and polyvinyl alcohol (PVA). The SiC nanoparticle used in this research was synthesized from sucrose and natural silica via a sonochemical method. The natural silica was extracted from local pyrophyllite by a sol-gel method. The characterization was performed via x-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM). The XRD characterization results showed that the sample possessed a β-SiC phase and formed a cubic-structured crystal with a lattice parameter of a = b = c = 4.3448 Å. The use of PEG and PVA in the electrospinning process resulted in fractal and fiber structured SiC, respectively.

Identification of tensile strength properties of abaca fiber by weakest-linkage approach-statistic property of fiber diameter

NASA Astrophysics Data System (ADS)

Suardi; Homma, H.; Abubakar

2018-02-01

Fiber reinforced plastics or metals (FRPor FRM) are usually ecological materials, because their specific strength defined as the strengthperunit mass is much larger than metal, and weight ofmachines and structuresfor transport made ofFRP can be significantly reduced so that the consumption of fossil fuel scan be saved to result in tremendous reduction of CO2emissions. However, when we consider life cycle assessment (LCA) of synthetic fibers like carbon fiber and glass fiber, we can recognize much CO2 emission in production of these fibers. Therefore, more ecological reinforcement fibers must be developed. For this end, we should utilization cellulose fibers derived from plant tissue structure as an alternative fibers for synthetic fibers, which are considered as carbon neutral materials, and natural degraded material. This study selectsabaca fiber, which is a natural fiber and is abundant in Indonesia, but its usagehas not been optimized for engineering material. The purpose of this study is to identify the mechanical strength of a single abaca fiber by statistical approach. First, weakest link theory and Weibull theory are used to discuss experimental data. 90 specimens of almost identical geometry and biological aspects are tested under tension. These data are analyzed by Weibull theory or other statistical theory. Final target is to look into optimal method to reduce scatter ratio, ratio of standard deviation to mean value, of less than 0.1, which is the level of metallic materials. If we can reduce scatter ration to such level, we can design machines and structures using abaca fiber in the same way as carbon fibers or glass fibers. Summary of Diameter Measurement the all mean value is 0.1 and standardeviasi. The t-Test showed that mean value of each part is estimated as sampling from group with the same mean value, at confidence level of 99%.

Time-evolving collagen-like structural fibers in soft tissues: biaxial loading and spherical inflation

NASA Astrophysics Data System (ADS)

Topol, Heiko; Demirkoparan, Hasan; Pence, Thomas J.; Wineman, Alan

2017-02-01

This work considers a previously developed constitutive theory for the time dependent mechanical response of fibrous soft tissue resulting from the time dependent remodeling of a collagen fiber network that is embedded in a ground substance matrix. The matrix is taken to be an incompressible nonlinear elastic solid. The remodeling process consists of the continual dissolution of existing fibers and the creation of new fibers. Motivated by experimental reports on the enzyme degradation of collagen fibers, the remodeling is governed by first order chemical kinetics such that the dissolution rate is dependent upon the fiber stretch. The resulting time dependent mechanical response is sensitive to the natural configuration of the fibers when they are created, and different assumptions on the nature of the fiber's stress free state are considered here. The response under biaxial loading, a type of loading that has particular significance for the characterization of biological materials, is studied. The inflation of a spherical membrane is then analyzed in terms of the equal biaxial stretch that occurs in the membrane approximation. Different assumptions on the natural configuration of the fibers, combined with their time dependent dissolution and reforming, are shown to emulate alternative forms of creep and relaxation response. This formal similarity to viscoelastic phenomena occurs even though the underlying mechanisms are fundamentally different from the mechanism of macromolecular reconfiguration that one typically associates with viscoelastic response.

A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2006-01-01

A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis - Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales improves the quality of the simulation by enabling failure at locations other than those associated with structural level stress risers.

A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2007-01-01

A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis-Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales improves the quality of the simulation by enabling failure at locations other than those associated with structural level stress risers.

Fiber-reinforced scaffolds in soft tissue engineering

PubMed Central

Wang, Wei; Fan, Yubo; Wang, Xiumei; Watari, Fumio

2017-01-01

Abstract Soft tissue engineering has been developed as a new strategy for repairing damaged or diseased soft tissues and organs to overcome the limitations of current therapies. Since most of soft tissues in the human body are usually supported by collagen fibers to form a three-dimensional microstructure, fiber-reinforced scaffolds have the advantage to mimic the structure, mechanical and biological environment of natural soft tissues, which benefits for their regeneration and remodeling. This article reviews and discusses the latest research advances on design and manufacture of novel fiber-reinforced scaffolds for soft tissue repair and how fiber addition affects their structural characteristics, mechanical strength and biological activities in vitro and in vivo. In general, the concept of fiber-reinforced scaffolds with adjustable microstructures, mechanical properties and degradation rates can provide an effective platform and promising method for developing satisfactory biomechanically functional implantations for soft tissue engineering or regenerative medicine. PMID:28798872

Review the role of terminal domains during storage and assembly of spider silk proteins.

PubMed

Eisoldt, Lukas; Thamm, Christopher; Scheibel, Thomas

2012-06-01

Fibrous proteins in nature fulfill a wide variety of functions in different structures ranging from cellular scaffolds to very resilient structures like tendons and even extra-corporal fibers such as silks in spider webs or silkworm cocoons. Despite their different origins and sequence varieties many of these fibrous proteins share a common building principle: they consist of a large repetitive core domain flanked by relatively small non-repetitive terminal domains. Amongst protein fibers, spider dragline silk shows prominent mechanical properties that exceed those of man-made fibers like Kevlar. Spider silk fibers assemble in a spinning process allowing the transformation from an aqueous solution into a solid fiber within milliseconds. Here, we highlight the role of the non-repetitive terminal domains of spider dragline silk proteins during storage in the gland and initiation of the fiber assembly process. Copyright © 2011 Wiley Periodicals, Inc.

Click chemistry modification of natural keratin fibers for sustained shrink-resist performance.

PubMed

Yu, Dan; Cai, Jackie Y; Church, Jeffrey S; Wang, Lijing

2015-01-01

This paper introduces a novel chemical treatment for achieving sustained shrink-resist performance on natural keratin fibers. The new treatment involves the controlled reduction of keratin in the cuticle region of the fiber, and the application of a water soluble diacrylate, namely glycerol 1,3-diglycerolate diacrylate (GDA), on the reduced keratin substrate. The acrylate groups of the GDA react with cysteine residues in the reduced keratin through thiol-ene click reactions at room temperature, leading to GDA grafting and the formation of GDA crosslinks in the keratin structure. The modified substrates were characterized by infrared spectroscopy and scanning electron microscopy, and assessed for its shrink-resistance and wet burst strength. This chemical modification has shown to alter the fiber surface morphology and hydrophilicity, resulting in substantially improved shrink-resistance with good fiber strength retention. Possible shrink-resistance mechanisms were also discussed. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Passively stabilized 215-W monolithic CW LMA-fiber laser with innovative transversal mode filter

NASA Astrophysics Data System (ADS)

Stutzki, Fabian; Jauregui, Cesar; Voigtländer, Christian; Thomas, Jens U.; Limpert, Jens; Nolte, Stefan; Tünnermann, Andreas

2010-02-01

We report on the development of a high power monolithic CW fiber oscillator with an output power of 215 W in a 20μm core diameter few-mode Large Mode Area fiber (LMA). The key parameters for stable operation are reviewed. With these optimizations the root mean square of the output power fluctuations can be reduced to less than 0.5 % on a timescale of 20 s, which represents an improvement of more than a factor 5 over a non-optimized fiber laser. With a real-time measurement of the mode content of the fiber laser it can be shown that the few-mode nature of LMA fibers is the main factor for the residual instability of our optimized fiber laser. The root of the problem is that Fiber Bragg Gratings (FBGs) written in multimode fibers exhibit a multi-peak reflexion spectrum in which each resonance corresponds to a different transversal mode. This reflectivity spectrum stimulates multimode laser operation, which results in power and pointing instabilities due to gain competition between the different transversal modes . To stabilize the temporal and spatial behavior of the laser output, we propose an innovative passive in-fiber transversal mode filter based on modified FBG-Fabry Perot structure. This structure provides different reflectivities to the different transversal modes according to the transversal distribution of their intensity profile. Furthermore, this structure can be completely written into the active fiber using fs-laser pulses. Moreover, this concept scales very well with the fiber core diameter, which implies that there is no performance loss in fibers with even larger cores. In consequence this structure is inherently power scalable and can, therefore, be used in kW-level fiber laser systems.

Engineering on the straight and narrow: the mechanics of nanofibrous assemblies for fiber-reinforced tissue regeneration.

PubMed

Mauck, Robert L; Baker, Brendon M; Nerurkar, Nandan L; Burdick, Jason A; Li, Wan-Ju; Tuan, Rocky S; Elliott, Dawn M

2009-06-01

Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation.

Engineering on the Straight and Narrow: The Mechanics of Nanofibrous Assemblies for Fiber-Reinforced Tissue Regeneration

PubMed Central

Baker, Brendon M.; Nerurkar, Nandan L.; Burdick, Jason A.; Li, Wan-Ju; Tuan, Rocky S.; Elliott, Dawn M.

2009-01-01

Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation. PMID:19207040

Analysis of flavonoids and the flavonoid structural genes in brown fiber of upland cotton.

PubMed

Feng, Hongjie; Tian, Xinhui; Liu, Yongchang; Li, Yanjun; Zhang, Xinyu; Jones, Brian Joseph; Sun, Yuqiang; Sun, Jie

2013-01-01

As a result of changing consumer preferences, cotton (Gossypium Hirsutum L.) from varieties with naturally colored fibers is becoming increasingly sought after in the textile industry. The molecular mechanisms leading to colored fiber development are still largely unknown, although it is expected that the color is derived from flavanoids. Firstly, four key genes of the flavonoid biosynthetic pathway in cotton (GhC4H, GhCHS, GhF3'H, and GhF3'5'H) were cloned and studied their expression profiles during the development of brown- and white cotton fibers by QRT-PCR. And then, the concentrations of four components of the flavonoid biosynthetic pathway, naringenin, quercetin, kaempferol and myricetin in brown- and white fibers were analyzed at different developmental stages by HPLC. The predicted proteins of the four flavonoid structural genes corresponding to these genes exhibit strong sequence similarity to their counterparts in various plant species. Transcript levels for all four genes were considerably higher in developing brown fibers than in white fibers from a near isogenic line (NIL). The contents of four flavonoids (naringenin, quercetin, kaempferol and myricetin) were significantly higher in brown than in white fibers and corresponding to the biosynthetic gene expression levels. Flavonoid structural gene expression and flavonoid metabolism are important in the development of pigmentation in brown cotton fibers.

Structure and properties of novel fibers spun from cellulose in NaOH/thiourea aqueous solution.

PubMed

Ruan, Dong; Zhang, Lina; Zhou, Jinping; Jin, Huiming; Chen, Hui

2004-12-15

Cellulose was dissolved rapidly in a NaOH/thiourea aqueous solution (9.5:4.5 in wt.-%) to prepare a transparent cellulose solution, which was employed, for the first time, to spin a new class of regenerated cellulose fibers by wet spinning. The structure and mechanical properties of the resulting cellulose fibers were characterized, and compared with those of commercially available viscose rayon, cuprammonium rayon and Lyocell fibers. The results from wide angle X-ray diffraction and CP/MAS 13C NMR indicated that the novel cellulose fibers have a structure typical for a family II cellulose and possessed relatively high degrees of crystallinity. Scanning electron microscopy (SEM) and optical microscopy images revealed that the cross-section of the fibers is circular, similar to natural silk. The new fibers have higher molecular weights and better mechanical properties than those of viscose rayon. This low-cost technology is simple, different from the polluting viscose process. The dissolution and regeneration of the cellulose in the NaOH/thiourea aqueous solutions were a physical process and a sol-gel transition rather than a chemical reaction, leading to the smoothness and luster of the fibers. This work provides a potential application in the field of functional fiber manufacturing.

Recycling of ligno-cellulosic and polyethylene wastes from agricultural operations in thermoplastic composites

USDA-ARS?s Scientific Manuscript database

In the US, wood plastic composites (WPC) represent one of the successful markets for natural fiber-filled thermoplastic composites. The WPC typically use virgin or recycled thermoplastic as the substrate and wood fiber as the filler. A major application of the WPC is in non-structural building appli...

Comparative evaluation of in vivo biocompatibility and biodegradability of regenerated silk scaffolds reinforced with/without natural silk fibers.

PubMed

Mobini, Sahba; Taghizadeh-Jahed, Masoud; Khanmohammadi, Manijeh; Moshiri, Ali; Naderi, Mohammad-Mehdi; Heidari-Vala, Hamed; Ashrafi Helan, Javad; Khanjani, Sayeh; Springer, Armin; Akhondi, Mohammad-Mehdi; Kazemnejad, Somaieh

2016-01-01

Nowadays, exceptional advantages of silk fibroin over synthetic and natural polymers have impelled the scientists to application of this biomaterial for tissue engineering purposes. Recently, we showed that embedding natural degummed silk fibers in regenerated Bombyx mori silk-based scaffold significantly increases the mechanical stiffness, while the porosity of the scaffolds remains the same. In the present study, we evaluated degradation rate, biocompatibility and regenerative properties of the regenerated 2% and 4% wt silk-based composite scaffolds with or without embedded natural degummed silk fibers within 90 days in both athymic nude and wild-type C57BL/6 mice through subcutaneous implantation. In all scaffolds, a suitable interconnected porous structure for cell penetration was seen under scanning electron microscopy. Compressive tests revealed a functional relationship between fiber reinforcement and compressive modulus. In addition, the fiber/fibroin composite scaffolds support cell attachment and proliferation. On days 30 to 90 after subcutaneous implantation, the retrieved tissues were examined via gross morphology, histopathology, immunofluorescence staining and reverse transcription-polymerase chain reaction as shown in Figure 1. Results showed that embedding the silk fibers within the matrix enhances the biodegradability of the matrix resulting in replacement of the composite scaffolds with the fresh connective tissue. Fortification of the composites with degummed fibers not only regulates the degradation profile but also increases the mechanical performance of the scaffolds. This report also confirmed that pore size and structure play an important role in the degradation rate. In conclusion, the findings of the present study narrate key role of additional surface area in improving in vitro and in vivo biological properties of the scaffolds and suggest the potential ability of these fabricated composite scaffolds for connective tissue regeneration. spjba;30/6/793/FIG10885328215601925F1fig1-0885328215601925Figure 1.Illustrative summary of the main methods and findings.RS: regenerated silk; RSF: regenerated fibroin/ silk fiber composite scaffolds; H&E: Hematoxylin and eosin; COX-1: Cyclooxygenase. © The Author(s) 2015.

Increased NIH 3T3 fibroblast functions on cell culture dishes which mimic the nanometer fibers of natural tissues.

PubMed

Bhardwaj, Garima; Webster, Thomas J

2015-01-01

Traditional flat tissue cell culture dishes have consisted of polystyrene treated with plasma gases for growing, subculturing, and studying cell behavior in vitro. However, increasingly it has been observed that mimicking natural tissue properties (such as chemistry, three-dimensional structure, mechanical properties, etc) in vitro can lead to a better correlation of in vitro to in vivo cellular functions. The following studies compared traditional NIH 3T3 fibroblasts' functions on XanoMatrix scaffolds to standard tissue culture polystyrene. Results found significantly greater fibroblast adhesion and proliferation on XanoMatrix cell culture dishes which mimic the nanoscale geometry of natural tissue fibers with true, tortuous fiber beds creating a robust, consistent, and versatile growth platform. In this manner, this study supports that cell culture dishes which mimic features of natural tissues should be continually studied for a wide range of applications in which mimicking natural cellular functions are important.

Structure of a pentameric virion-associated fiber with a potential role in Orsay virus entry to host cells

PubMed Central

Yuan, Wang; Zhou, Ying; Wang, Tao; Demeler, Borries; Zhong, Weiwei; Tao, Yizhi J.

2017-01-01

Despite the wide use of Caenorhabditis elegans as a model organism, the first virus naturally infecting this organism was not discovered until six years ago. The Orsay virus and its related nematode viruses have a positive-sense RNA genome, encoding three proteins: CP, RdRP, and a novel δ protein that shares no homology with any other proteins. δ can be expressed either as a free δ or a CP-δ fusion protein by ribosomal frameshift, but the structure and function of both δ and CP-δ remain unknown. Using a combination of electron microscopy, X-ray crystallography, computational and biophysical analyses, here we show that the Orsay δ protein forms a ~420-Å long, pentameric fiber with an N-terminal α-helical bundle, a β-stranded filament in the middle, and a C-terminal head domain. The pentameric nature of the δ fiber has been independently confirmed by both mass spectrometry and analytical ultracentrifugation. Recombinant Orsay capsid containing CP-δ shows protruding long fibers with globular heads at the distal end. Mutant viruses with disrupted CP-δ fibers were generated by organism-based reverse genetics. These viruses were found to be either non-viable or with poor infectivity according to phenotypic and qRT-PCR analyses. Furthermore, addition of purified δ proteins to worm culture greatly reduced Orsay infectivity in a sequence-specific manner. Based on the structure resemblance between the Orsay CP-δ fiber and the fibers from reovirus and adenovirus, we propose that CP-δ functions as a cell attachment protein to mediate Orsay entry into worm intestine cells. PMID:28241071

Enhancement of acoustical performance of hollow tube sound absorber

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

Putra, Azma, E-mail: azma.putra@utem.edu.my; Khair, Fazlin Abd, E-mail: fazlinabdkhair@student.utem.edu.my; Nor, Mohd Jailani Mohd, E-mail: jai@utem.edu.my

This paper presents acoustical performance of hollow structures utilizing the recycled lollipop sticks as acoustic absorbers. The hollow cross section of the structures is arranged facing the sound incidence. The effects of different length of the sticks and air gap on the acoustical performance are studied. The absorption coefficient was measured using impedance tube method. Here it is found that improvement on the sound absorption performance is achieved by introducing natural kapok fiber inserted into the void between the hollow structures. Results reveal that by inserting the kapok fibers, both the absorption bandwidth and the absorption coefficient increase. For testmore » sample backed by a rigid surface, best performance of sound absorption is obtained for fibers inserted at the front and back sides of the absorber. And for the case of test sample with air gap, this is achieved for fibers introduced only at the back side of the absorber.« less

Enhancement of acoustical performance of hollow tube sound absorber

NASA Astrophysics Data System (ADS)

Putra, Azma; Khair, Fazlin Abd; Nor, Mohd Jailani Mohd

2016-03-01

This paper presents acoustical performance of hollow structures utilizing the recycled lollipop sticks as acoustic absorbers. The hollow cross section of the structures is arranged facing the sound incidence. The effects of different length of the sticks and air gap on the acoustical performance are studied. The absorption coefficient was measured using impedance tube method. Here it is found that improvement on the sound absorption performance is achieved by introducing natural kapok fiber inserted into the void between the hollow structures. Results reveal that by inserting the kapok fibers, both the absorption bandwidth and the absorption coefficient increase. For test sample backed by a rigid surface, best performance of sound absorption is obtained for fibers inserted at the front and back sides of the absorber. And for the case of test sample with air gap, this is achieved for fibers introduced only at the back side of the absorber.

Spider Silks-Biomimetics Beyond Silk Fibers: Hydrogels, films & Adhesives from Aqueous Recombinant Spider Silk dopes: A Synchrotron X-Ray Nano-Structural Study

NASA Astrophysics Data System (ADS)

Sampath, Sujatha; Jones, Justin; Harris, Thomas; Lewis, Randolph

2015-03-01

With a combination of high strength and extensibility, spider silk's (SS) mechanical properties surpass those of any man made fiber. The superior properties are due to the primary protein composition and the complex hierarchical structural organization from nanoscale to macroscopic length scales. Considerable progress has been made to synthetically mimic the production of fibers based on SS proteins. We present synchrotron x-ray micro diffraction (SyXRD) results on new fibers and gels (hydrogels, lyogels) from recombinant SS protein water-soluble dopes. Novelty in these materials is two-fold: water based rather than widely used HFIP acid synthesis, makes them safe in medical applications (replacement for tendons & ligaments). Secondly, hydrogels morphology render them as excellent carriers for targeted drug delivery biomedical applications. SyXRD results reveal semi-crystalline structure with ordered beta-sheets and relatively high degree of axial orientation in the fibers, making them the closest yet to natural spider silks. SyXRD on the gels elucidate the structural transformations during the self-recovery process through mechanical removal and addition of water. Studies correlating the observed structural changes to mechanical properties are underway.

Aggregation of asbestos fibers in water: role of solution chemistry

NASA Astrophysics Data System (ADS)

Wu, L.; Ortiz, C. P.; Jerolmack, D. J.

2016-12-01

Aggregation kinetics and stability of colloidal particles have been extensively studied using bulk techniques such as dynamic light scattering; these techniques involve large ensembles of particles and interpretation of results is difficult when particles are non-spherical and poorly characterized, as is always the case with non-ideal natural hazardous materials such as asbestos fibers. These difficulties hinder greatly progress on fundamental understanding of whether the classic colloidal aggregation theories can be applied to natural materials and how the heterogeneity of particles (e.g., shape) affects the colloidal aggregation kinetics and structure. By using in-situ microscopy and particle tracking techniques, we were able to observe the particle-by-particle growth of aggregated formed by elongated particles (synthetic glass rods and natural asbestos fibers) and demonstrated the rod-shaped geometry induced novel structures and growth dynamics that challenge existing theory. In this study, we continue to use asbestos as model system of elongated colloidal contaminant, and investigate the effects of changing solution chemistry (e.g., ionic strength, pH, and natural organic matter (NOM)), on growth dynamics and aggregates structure. The results show that aggregate growth curves are self-similar with a characteristic timescale that increases with increasing pH. By varying ionic strength for fixed pH values, we determine that the ccc is sensitive to pH. Fractal dimension decreases slightly with increasing pH and decreasing ionic strength, indicating that stronger inter-particle repulsion create sparser aggregates; however, the magnitude of the solution chemistry effects is much smaller than that of colloid shape. In monovalent solutions, regardless of their concentration, HA drastically reduces the aggregation kinetics of asbestos fiber. This work may lead to enhanced prediction of the colloidal contaminants' mobility in the environment, bioavailability, and toxicity to organisms.

Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures

PubMed Central

López-Alba, Elías; Díaz, Francisco

2018-01-01

The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack) made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen) and PLA (polylactic acid) matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets) were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA) as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack) seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD-PE matrix. PMID:29534003

Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures.

PubMed

López-Alba, Elías; Schmeer, Sebastian; Díaz, Francisco

2018-03-13

The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack) made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen) and PLA (polylactic acid) matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets) were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA) as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack) seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD-PE matrix.

Natural triple beta-stranded fibrous folds.

PubMed

Mitraki, Anna; Papanikolopoulou, Katerina; Van Raaij, Mark J

2006-01-01

A distinctive family of beta-structured folds has recently been described for fibrous proteins from viruses. Virus fibers are usually involved in specific host-cell recognition. They are asymmetric homotrimeric proteins consisting of an N-terminal virus-binding tail, a central shaft or stalk domain, and a C-terminal globular receptor-binding domain. Often they are entirely or nearly entirely composed of beta-structure. Apart from their biological relevance and possible gene therapy applications, their shape, stability, and rigidity suggest they may be useful as blueprints for biomechanical design. Folding and unfolding studies suggest their globular C-terminal domain may fold first, followed by a "zipping-up" of the shaft domains. The C-terminal domains appear to be important for registration because peptides corresponding to shaft domains alone aggregate into nonnative fibers and/or amyloid structures. C-terminal domains can be exchanged between different fibers and the resulting chimeric proteins are useful as a way to solve structures of unknown parts of the shaft domains. The following natural triple beta-stranded fibrous folds have been discovered by X-ray crystallography: the triple beta-spiral, triple beta-helix, and T4 short tail fiber fold. All have a central longitudinal hydrophobic core and extensive intermonomer polar and nonpolar interactions. Now that a reasonable body of structural and folding knowledge has been assembled about these fibrous proteins, the next challenge and opportunity is to start using this information in medical and industrial applications such as gene therapy and nanotechnology.

The polymorphisms of the chromatin fiber

NASA Astrophysics Data System (ADS)

Boulé, Jean-Baptiste; Mozziconacci, Julien; Lavelle, Christophe

2015-01-01

In eukaryotes, the genome is packed into chromosomes, each consisting of large polymeric fibers made of DNA bound with proteins (mainly histones) and RNA molecules. The nature and precise 3D organization of this fiber has been a matter of intense speculations and debates. In the emerging picture, the local chromatin state plays a critical role in all fundamental DNA transactions, such as transcriptional control, DNA replication or repair. However, the molecular and structural mechanisms involved remain elusive. The purpose of this review is to give an overview of the tremendous efforts that have been made for almost 40 years to build physiologically relevant models of chromatin structure. The motivation behind building such models was to shift our representation and understanding of DNA transactions from a too simplistic ‘naked DNA’ view to a more realistic ‘coated DNA’ view, as a step towards a better framework in which to interpret mechanistically the control of genetic expression and other DNA metabolic processes. The field has evolved from a speculative point of view towards in vitro biochemistry and in silico modeling, but is still longing for experimental in vivo validations of the proposed structures or even proof of concept experiments demonstrating a clear role of a given structure in a metabolic transaction. The mere existence of a chromatin fiber as a relevant biological entity in vivo has been put into serious questioning. Current research is suggesting a possible reconciliation between theoretical studies and experiments, pointing towards a view where the polymorphic and dynamic nature of the chromatin fiber is essential to support its function in genome metabolism.

Porosity Assessment for Different Diameters of Coir Lignocellulosic Fibers

NASA Astrophysics Data System (ADS)

da Luz, Fernanda Santos; Paciornik, Sidnei; Monteiro, Sergio Neves; da Silva, Luiz Carlos; Tommasini, Flávio James; Candido, Verônica Scarpini

2017-10-01

The application of natural lignocellulosic fibers (LCFs) in engineering composites has increased interest in their properties and structural characteristics. In particular, the inherent porosity of an LCF markedly affects its density and the adhesion to polymer matrices. For the first time, both open and closed porosities of a natural LCF, for different diameter ranges, were assessed. Fibers extracted from the mesocarp of the coconut fruit were investigated by nondestructive methods of density measurements and x-ray microtomography (microCT). It was found that, for all diameter ranges, the closed porosity is significantly higher than the open porosity. The total porosity increases with diameter to around 60% for coir fibers with more than 503 μm in diameter. The amount and characteristics of these open and closed porosities were revealed by t test and Weibull statistics as well as by microCT.

Bonelike apatite formation on ethylene-vinyl alcohol copolymer modified with silane coupling agent and calcium silicate solutions.

PubMed

Oyane, Ayako; Kawashita, Masakazu; Nakanishi, Kazuki; Kokubo, Tadashi; Minoda, Masahiko; Miyamoto, Takeaki; Nakamura, Takashi

2003-05-01

An ethylene-vinyl alcohol copolymer (EVOH) was treated with a silane coupling agent and calcium silicate solutions, and then soaked in a simulated body fluid (SBF) with ion concentrations approximately equal to those of human blood plasma. A smooth and uniform bonelike apatite layer was successfully formed on both the EVOH plate and the EVOH-knitted fibers in SBF within 2 days. Part of the structure of the resulting apatite-EVOH fiber composite was similar to that of natural bone. If this kind of composite can be fabricated into a three-dimensional structure similar to natural bone, the resultant composite is expected to exhibit both mechanical properties analogous to those of natural bone and bone-bonding ability. Hence, it has great potential as a bone substitute. Copyright 2003 Elsevier Science Ltd.

Hemicellulose and lignin removal on typha fiber by alkali treatment

NASA Astrophysics Data System (ADS)

Ikramullah; Rizal, Samsul; Thalib, Sulaiman; Huzni, Syifaul

2018-05-01

One of the methods commonly utilized to alter the surfaces of natural fibers for improving the interface compatibility among fiber and polymer matrix is by alkali treatment. Several natural fibers have been experimented with alkali treatments such as abaca, borassus and kenaf. There is a relatively few of literature that reports the FTIR investigation of Typha fibers. The purpose of this study is to determine the effect of alkali treatment on Typha fiber. Two of three bundle fibers are immersed in a 5% NaOH solution for one and two hours. The chemical structure of alkali-treated and untreated fibers are both being analyzed by Fourier Transform Infrared Spectroscopy (FTIR) instrument. The emergence of peak at 1155.36 cm-1 in strong intensity denotes the C-O-C asymmetric stretching in cellulose compound. The lignin composition of the fiber is typified by the stretching band of C-O group at 1247 cm-1. Meanwhile, the peak at 1735.03 cm-1 wavenumber is allegedly C=O stretching evidencing the existence of hemicelluloses and pectin. The peaks which are suspected to be hemicellulose, lignin and pectin are no longer visible in alkali treated Typha fiber. Giving alkali treatment to Typha fiber has been successfully removed impurities (hemicelluloses and lignin), as approved by the FTIR analysis. This will lead to a better contact and bonding mechanism between fiber and polymer matrix.

Investigation some characteristics of chicken feather’s rachis

NASA Astrophysics Data System (ADS)

Paşayev, N.; Kocatepe, S.; Maraş, N.; Soylak, M.; Erol, M.

2017-10-01

In recent years, obtaining the natural protein fibers from chicken feathers, which are obtained as a by-product in the production of chicken meat and which cause environmental pollution and important part is waste, has been drawn to the perspective of scientists. So, the investigations about the chicken feather fibers reveal important properties of these fibers. Chicken feather fibers are obtained by mechanical cutting of the barbs which have fibrous structure, the structure branched from rachis and constitute the body of the feather. The rachis part of chicken feather constitutes approximately half of the weight of the feathers. So, it is necessary to examine the properties of the chicken feathers in order to gain their industrialization. This study is concerned with the mechanical and physical properties of the material that is taken as a by-product in the production of fibers from chicken feathers and constitutes the rachis part of the feathers.

Investigation on dynamic performance of concrete column crumb rubber steel and fiber concrete

NASA Astrophysics Data System (ADS)

Siti Nurul Nureda, M. Z.; Mariyana, A. K.; Khiyon, M. Iqbal; Rahman, M. S. Abdul; Nurizaty, Z.

2017-11-01

In general the Normal Concrete (NC) are by quasi-brittle failure, where, the nearly complete loss of loading capacity, once failure is initiated especially under dynamic loadings. The significance of this study is to improve the damping properties of concrete structure by utilization of the recycled materials from waste tires to be used in concrete as structural materials that improve seismic performance. In this study, the concrete containing 10% of fine crumb rubber and 1 % volume fraction of steel fiber from waste tires is use to investigate the dynamic performance (natural frequency and damping ratio).A small scale column were fabricated from Treated Crumb Rubber and Steel Fiber Concrete (TCRSFC) and NC were cast and cured for 28 days to investigate the dynamic performance. Based on analysis, dynamic modulus, damping ratio and natural frequency of TCRSFC has improved considerably by 5.18%, 109% and 10.94% when compared with NC. The TCRSFC producing concrete with the desired properties as well as to introduce the huge potential as dynamic resistance structure from severe damage especially prevention on catastrophic failure.

Analysis of Flavonoids and the Flavonoid Structural Genes in Brown Fiber of Upland Cotton

PubMed Central

Liu, Yongchang; Li, Yanjun; Zhang, Xinyu; Jones, Brian Joseph; Sun, Yuqiang; Sun, Jie

2013-01-01

Backgroud As a result of changing consumer preferences, cotton (Gossypium Hirsutum L.) from varieties with naturally colored fibers is becoming increasingly sought after in the textile industry. The molecular mechanisms leading to colored fiber development are still largely unknown, although it is expected that the color is derived from flavanoids. Experimental Design Firstly, four key genes of the flavonoid biosynthetic pathway in cotton (GhC4H, GhCHS, GhF3′H, and GhF3′5′H) were cloned and studied their expression profiles during the development of brown- and white cotton fibers by QRT-PCR. And then, the concentrations of four components of the flavonoid biosynthetic pathway, naringenin, quercetin, kaempferol and myricetin in brown- and white fibers were analyzed at different developmental stages by HPLC. Result The predicted proteins of the four flavonoid structural genes corresponding to these genes exhibit strong sequence similarity to their counterparts in various plant species. Transcript levels for all four genes were considerably higher in developing brown fibers than in white fibers from a near isogenic line (NIL). The contents of four flavonoids (naringenin, quercetin, kaempferol and myricetin) were significantly higher in brown than in white fibers and corresponding to the biosynthetic gene expression levels. Conclusions Flavonoid structural gene expression and flavonoid metabolism are important in the development of pigmentation in brown cotton fibers. PMID:23527031

Study on structure and morphology (Boehmeria nivea) in the irregular and regular parts of the fiber after biodegumming

NASA Astrophysics Data System (ADS)

Wulandari, A. P.; Septarini, D.; Zainuddin, A.

2017-05-01

Ramie is a natural fiber that is very potential to be developed in Indonesia. Decorticated-fiber which has been known as china grass produce different structures irregular part but shows a long straight section in the middle. This study aims to determine differences in chemical components, morphology and microstructure of two different parties after biodegumming process. China grass has been processed to remove gum using pectinolytic fungus. The microstructure of the treated was further tested by Fourier Transform InfraRed (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscope (SEM). The FTIR study indicated that during the biodegumming process, chemical bonding of non-cellulose components most removed by the activity of pectinase from the fungus. XRD analysis reflects an increase in the crystallinity of the fiber after biodegumming. Scanning electron microscopy (SEM) was used to confirm a reduction in the size of the fiber after biodegumming either in the irregular and regular part of the fiber after biodegumming.

Formation of highly stable chimeric trimers by fusion of an adenovirus fiber shaft fragment with the foldon domain of bacteriophage t4 fibritin.

PubMed

Papanikolopoulou, Katerina; Forge, Vincent; Goeltz, Pierrette; Mitraki, Anna

2004-03-05

The folding of beta-structured, fibrous proteins is a largely unexplored area. A class of such proteins is used by viruses as adhesins, and recent studies revealed novel beta-structured motifs for them. We have been studying the folding and assembly of adenovirus fibers that consist of a globular C-terminal domain, a central fibrous shaft, and an N-terminal part that attaches to the viral capsid. The globular C-terminal, or "head" domain, has been postulated to be necessary for the trimerization of the fiber and might act as a registration signal that directs its correct folding and assembly. In this work, we replaced the head of the fiber by the trimerization domain of the bacteriophage T4 fibritin, termed "foldon." Two chimeric proteins, comprising the foldon domain connected at the C-terminal end of four fiber shaft repeats with or without the use of a natural linker sequence, fold into highly stable, SDS-resistant trimers. The structural signatures of the chimeric proteins as seen by CD and infrared spectroscopy are reported. The results suggest that the foldon domain can successfully replace the fiber head domain in ensuring correct trimerization of the shaft sequences. Biological implications and implications for engineering highly stable, beta-structured nanorods are discussed.

Nondestructive Evaluation of Advanced Fiber Reinforced Polymer Matrix Composites: A Technology Assessment

NASA Technical Reports Server (NTRS)

Yolken, H. Thomas; Matzkanin, George A.

2009-01-01

Because of their increasing utilization in structural applications, the nondestructive evaluation (NDE) of advanced fiber reinforced polymer composites continues to receive considerable research and development attention. Due to the heterogeneous nature of composites, the form of defects is often very different from a metal and fracture mechanisms are more complex. The purpose of this report is to provide an overview and technology assessment of the current state-of-the-art with respect to NDE of advanced fiber reinforced polymer composites.

Tightening slip knots in raw and degummed silk to increase toughness without losing strength.

PubMed

Pantano, Maria F; Berardo, Alice; Pugno, Nicola M

2016-02-12

Knots are fascinating topological elements, which can be found in both natural and artificial systems. While in most of the cases, knots cannot be loosened without breaking the strand where they are tightened, herein, attention is focused on slip or running knots, which on the contrary can be unfastened without compromising the structural integrity of their hosting material. Two different topologies are considered, involving opposite unfastening mechanisms, and their influence on the mechanical properties of natural fibers, as silkworm silk raw and degummed single fibers, is investigated and quantified. Slip knots with optimized shape and size result in a significant enhancement of fibers energy dissipation capability, up to 300-400%, without affecting their load bearing capacity.

Tightening slip knots in raw and degummed silk to increase toughness without losing strength

PubMed Central

Pantano, Maria F.; Berardo, Alice; Pugno, Nicola M.

2016-01-01

Knots are fascinating topological elements, which can be found in both natural and artificial systems. While in most of the cases, knots cannot be loosened without breaking the strand where they are tightened, herein, attention is focused on slip or running knots, which on the contrary can be unfastened without compromising the structural integrity of their hosting material. Two different topologies are considered, involving opposite unfastening mechanisms, and their influence on the mechanical properties of natural fibers, as silkworm silk raw and degummed single fibers, is investigated and quantified. Slip knots with optimized shape and size result in a significant enhancement of fibers energy dissipation capability, up to 300–400%, without affecting their load bearing capacity. PMID:26868855

Use of green chemistry methods in the extraction of dietary fibers from cactus rackets (Opuntia ficus indica): Structural and microstructural studies.

PubMed

Cheikh Rouhou, Marwa; Abdelmoumen, Souhir; Thomas, Sabu; Attia, Hamadi; Ghorbel, Dorra

2018-05-23

This work aims to compare the development of three green chemistry methods in the extraction of cactus (Opuntia ficus indica) dietary fibers. The influence of extraction conditions (solvent nature: water, lemon juice and ethanol; extraction process: maceration and steam explosion; extraction time: 30 min, 1 h, 3 h, 5 h) on the chemical and structural composition was studied. Fourier Transform Infrared (FTIR) spectroscopy proved that all treatments do not affect the cellulose structure and could induce the reduction of hemicelluloses and lignin content. The steam treatment with lemon juice was the best treatment in term of quality of the fibers extracted. Through X-ray Diffraction (XRD) analysis, it was demonstrated that this treatment contributed to the destruction of the amorphous phase with preservation of the crystalline phase. Scanning electron microscopy (SEM) showed that the microstructure of the sample surface was uniform and contains arranged fibers. Atomic Force Microscopy (AFM) revealed fibers with 80 nm of diameter. Copyright © 2018. Published by Elsevier B.V.

Functional and structural microanatomy of the fetal sciatic nerve.

PubMed

Creze, Maud; Zaitouna, Mazen; Krystel, Nyangoh Timoh; Diallo, Djibril; Lebacle, Cédric; Bellin, Marie-France; Ducreux, Denis; Benoit, Gérard; Bessede, Thomas

2017-10-01

The ultrastructure of a nerve has implications for surgical nerve repair. The aim of our study was to characterize the fascicular versus fibrillar anatomy and the autonomic versus somatic nature of the fetal sciatic nerve (SN). Immunohistochemistry for vesicular acetylcholine transporter, tyrosine hydroxylase, and peripheral myelin protein 22 was performed to identify cholinergic, adrenergic, and somatic axons, respectively, in the human fetal SN. Two-dimensional (2D) analysis and 3D reconstructions were performed. The fetal SN is composed of one-third stromal tissue and two-thirds neural tissue. Autonomic fibers are predominant over somatic fibers within the neural tissue. The distribution of somatic fibers is initially random, but then become topographically organized after intra- and interfascicular rearrangements have occurred within the nerve. The fetal model presents limitations but enables illustration of the nature of the nerve fibers and the 3D fascicular anatomy of the SN. Muscle Nerve 56: 787-796, 2017. © 2017 Wiley Periodicals, Inc.

Development and Characterization of Polymer Eco-Composites Based on Natural Rubber Reinforced with Natural Fibers.

PubMed

Stelescu, Maria-Daniela; Manaila, Elena; Craciun, Gabriela; Chirila, Corina

2017-07-11

Natural rubber composites filled with short natural fibers (flax and sawdust) were prepared by blending procedure and the elastomer cross-linking was carried out using benzoyl peroxide. The microbial degradation of composites was carried out by incubating with Aspergillus niger recognized for the ability to grow and degrade a broad range of substrates. The extent of biodegradation was evaluated by weight loss and cross-linking degree study of composites after 2 months incubation in pure shake culture conditions. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) have proved to be precious and valuable instruments for morphological as well as structural characterization of the composites before and after incubation with Aspergillus niger .

Development and Characterization of Polymer Eco-Composites Based on Natural Rubber Reinforced with Natural Fibers

PubMed Central

Stelescu, Maria-Daniela; Manaila, Elena; Craciun, Gabriela; Chirila, Corina

2017-01-01

Natural rubber composites filled with short natural fibers (flax and sawdust) were prepared by blending procedure and the elastomer cross-linking was carried out using benzoyl peroxide. The microbial degradation of composites was carried out by incubating with Aspergillus niger recognized for the ability to grow and degrade a broad range of substrates. The extent of biodegradation was evaluated by weight loss and cross-linking degree study of composites after 2 months incubation in pure shake culture conditions. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) have proved to be precious and valuable instruments for morphological as well as structural characterization of the composites before and after incubation with Aspergillus niger. PMID:28773145

Computational strategies to address chromatin structure problems

NASA Astrophysics Data System (ADS)

Perišić, Ognjen; Schlick, Tamar

2016-06-01

While the genetic information is contained in double helical DNA, gene expression is a complex multilevel process that involves various functional units, from nucleosomes to fully formed chromatin fibers accompanied by a host of various chromatin binding enzymes. The chromatin fiber is a polymer composed of histone protein complexes upon which DNA wraps, like yarn upon many spools. The nature of chromatin structure has been an open question since the beginning of modern molecular biology. Many experiments have shown that the chromatin fiber is a highly dynamic entity with pronounced structural diversity that includes properties of idealized zig-zag and solenoid models, as well as other motifs. This diversity can produce a high packing ratio and thus inhibit access to a majority of the wound DNA. Despite much research, chromatin’s dynamic structure has not yet been fully described. Long stretches of chromatin fibers exhibit puzzling dynamic behavior that requires interpretation in the light of gene expression patterns in various tissue and organisms. The properties of chromatin fiber can be investigated with experimental techniques, like in vitro biochemistry, in vivo imagining, and high-throughput chromosome capture technology. Those techniques provide useful insights into the fiber’s structure and dynamics, but they are limited in resolution and scope, especially regarding compact fibers and chromosomes in the cellular milieu. Complementary but specialized modeling techniques are needed to handle large floppy polymers such as the chromatin fiber. In this review, we discuss current approaches in the chromatin structure field with an emphasis on modeling, such as molecular dynamics and coarse-grained computational approaches. Combinations of these computational techniques complement experiments and address many relevant biological problems, as we will illustrate with special focus on epigenetic modulation of chromatin structure.

Dietary fiber type reflects physiological functionality: comparison of grain fiber, inulin, and polydextrose.

PubMed

Raninen, Kaisa; Lappi, Jenni; Mykkänen, Hannu; Poutanen, Kaisa

2011-01-01

Dietary fiber is a nutritional concept based not on physiological functions but on defined chemical and physical properties. Recent definitions of dietary fiber differentiate inherent plant cell wall-associated fiber from isolated or synthetic fiber. For the latter to be defined as fiber, beneficial physiological effects should be demonstrated, such as laxative effects, fermentability, attenuation of blood cholesterol levels, or postprandial glucose response. Grain fibers are a major natural source of dietary fiber worldwide, while inulin, a soluble indigestible fructose polymer isolated from chicory, and polydextrose, a synthetic indigestible glucose polymer, have more simple structures. Inulin and polydextrose show many of the same functionalities of grain fiber in the large intestine, in that they are fermentable, bifidogenic, and laxative. The reported effects on postprandial blood glucose and fasting cholesterol levels have been modest, but grain fibers also show variable effects. New biomarkers are needed to link the physiological functions of specific fibers with long-term health benefits. © 2011 International Life Sciences Institute.

An optical fiber spool for laser stabilization with reduced acceleration sensitivity to 10-12/g

NASA Astrophysics Data System (ADS)

Hu, Yong-Qi; Dong, Jing; Huang, Jun-Chao; Li, Tang; Liu, Liang

2015-10-01

Environmental vibration causes mechanical deformation in optical fibers, which induces excess frequency noise in fiber-stabilized lasers. In order to solve such a problem, we propose an ultralow acceleration sensitivity fiber spool with symmetrically mounted structure. By numerical analysis with the finite element method, we obtain the optimal geometry parameters of the spool with which the horizontal and vertical acceleration sensitivity can be reduced to 3.25 × 10-12/g and 5.38 × 10-12/g respectively. Moreover, the structure features the insensitivity to the variation of geometry parameters, which will minimize the influence from numerical simulation error and manufacture tolerance. Project supported by the National Natural Science Foundation of China (Grant Nos. 11034008 and 11274324) and the Key Research Program of the Chinese Academy of Sciences (Grant No. KJZD-EW-W02).

Animal Hairs as Water-stimulated Shape Memory Materials: Mechanism and Structural Networks in Molecular Assemblies

NASA Astrophysics Data System (ADS)

Xiao, Xueliang; Hu, Jinlian

2016-05-01

Animal hairs consisting of α-keratin biopolymers existing broadly in nature may be responsive to water for recovery to the innate shape from their fixed deformation, thus possess smart behavior, namely shape memory effect (SME). In this article, three typical animal hair fibers were first time investigated for their water-stimulated SME, and therefrom to identify the corresponding net-points and switches in their molecular and morphological structures. Experimentally, the SME manifested a good stability of high shape fixation ratio and reasonable recovery rate after many cycles of deformation programming under water stimulation. The effects of hydration on hair lateral size, recovery kinetics, dynamic mechanical behaviors and structural components (crystal, disulfide and hydrogen bonds) were then systematically studied. SME mechanisms were explored based on the variations of structural components in molecular assemblies of such smart fibers. A hybrid structural network model with single-switch and twin-net-points was thereafter proposed to interpret the water-stimulated shape memory mechanism of animal hairs. This original work is expected to provide inspiration for exploring other natural materials to reveal their smart functions and natural laws in animals including human as well as making more remarkable synthetic smart materials.

Animal Hairs as Water-stimulated Shape Memory Materials: Mechanism and Structural Networks in Molecular Assemblies

PubMed Central

Xiao, Xueliang; Hu, Jinlian

2016-01-01

Animal hairs consisting of α-keratin biopolymers existing broadly in nature may be responsive to water for recovery to the innate shape from their fixed deformation, thus possess smart behavior, namely shape memory effect (SME). In this article, three typical animal hair fibers were first time investigated for their water-stimulated SME, and therefrom to identify the corresponding net-points and switches in their molecular and morphological structures. Experimentally, the SME manifested a good stability of high shape fixation ratio and reasonable recovery rate after many cycles of deformation programming under water stimulation. The effects of hydration on hair lateral size, recovery kinetics, dynamic mechanical behaviors and structural components (crystal, disulfide and hydrogen bonds) were then systematically studied. SME mechanisms were explored based on the variations of structural components in molecular assemblies of such smart fibers. A hybrid structural network model with single-switch and twin-net-points was thereafter proposed to interpret the water-stimulated shape memory mechanism of animal hairs. This original work is expected to provide inspiration for exploring other natural materials to reveal their smart functions and natural laws in animals including human as well as making more remarkable synthetic smart materials. PMID:27230823

Biomimetic Branched Hollow Fibers Templated by Self-assembled Fibrous Polyvinylpyrrolidone (PVP) Structures in Aqueous Solution

PubMed Central

Qiu, Penghe; Mao, Chuanbin

2010-01-01

Branched hollow fibers are common in nature, but to form artificial fibers with a similar branched hollow structure is still a challenge. We discovered that polyvinylpyrrolidone (PVP) could self-assemble into branched hollow fibers in an aqueous solution after aging the PVP solution for about two weeks. Based on this finding, we demonstrated two approaches by which the self-assembly of PVP into branched hollow fibers could be exploited to template the formation of branched hollow inorganic fibers. First, inorganic material such as silica with high affinity against the PVP could be deposited on the surface of the branched hollow PVP fibers to form branched hollow silica fibers. To extend the application of PVP self-assembly in templating the formation of hollow branched fibers, we then adopted a second approach where the PVP molecules bound to inorganic nanoparticles (using gold nanoparticles as a model) co-self-assemble with the free PVP molecules in an aqueous solution, resulting in the formation of the branched hollow fibers with the nanoparticles embedded in the PVP matrix constituting the walls of the fibers. Heating the resultant fibers above the glass transition temperature of PVP led to the formation of branched hollow gold fibers. Our work suggests that the self-assembly of the PVP molecules in the solution can serve as a general method for directing the formation of branched hollow inorganic fibers. The branched hollow fibers may find potential applications in microfluidics, artificial blood vessel generation, and tissue engineering. PMID:20158250

Towards a Pharmacophore for Amyloid

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

Landau, Meytal; Sawaya, Michael R.; Faull, Kym F.

2011-09-16

Diagnosing and treating Alzheimer's and other diseases associated with amyloid fibers remains a great challenge despite intensive research. To aid in this effort, we present atomic structures of fiber-forming segments of proteins involved in Alzheimer's disease in complex with small molecule binders, determined by X-ray microcrystallography. The fiber-like complexes consist of pairs of {beta}-sheets, with small molecules binding between the sheets, roughly parallel to the fiber axis. The structures suggest that apolar molecules drift along the fiber, consistent with the observation of nonspecific binding to a variety of amyloid proteins. In contrast, negatively charged orange-G binds specifically to lysine sidemore » chains of adjacent sheets. These structures provide molecular frameworks for the design of diagnostics and drugs for protein aggregation diseases. The devastating and incurable dementia known as Alzheimer's disease affects the thinking, memory, and behavior of dozens of millions of people worldwide. Although amyloid fibers and oligomers of two proteins, tau and amyloid-{beta}, have been identified in association with this disease, the development of diagnostics and therapeutics has proceeded to date in a near vacuum of information about their structures. Here we report the first atomic structures of small molecules bound to amyloid. These are of the dye orange-G, the natural compound curcumin, and the Alzheimer's diagnostic compound DDNP bound to amyloid-like segments of tau and amyloid-{beta}. The structures reveal the molecular framework of small-molecule binding, within cylindrical cavities running along the {beta}-spines of the fibers. Negatively charged orange-G wedges into a specific binding site between two sheets of the fiber, combining apolar binding with electrostatic interactions, whereas uncharged compounds slide along the cavity. We observed that different amyloid polymorphs bind different small molecules, revealing that a cocktail of compounds may be required for future amyloid therapies. The structures described here start to define the amyloid pharmacophore, opening the way to structure-based design of improved diagnostics and therapeutics.« less

[Histological structure of the trabecular meshwork in the eyeball: challenging the traditional concept and preliminary findings in rabbits, rats and mice].

PubMed

Shi, Yun; Zhou, Fan-Qi; Luo, Zhou-Cai; Chen, Ying-Hua; Chen, Yu; Dong, Wei-Ren

2017-10-20

To verify that the trabecular meshwork (TM) in the wall of the eyeball consists of smooth muscle fibers instead of collagen fibers or endothelial cells. Eighteen fresh eyeballs from 3 rabbits, 3 SD rats and 3 mice were sectioned along the sagittal plane and sliced after paraffin embedding for HE staining, VG staining, Masson staining, α-SMA immunohistochemistry or CD31 immunohistochemistry. These slices were observed under microscope and the structure of the TM was compared with those of scleral collagen fibers, ciliary muscles and endothelial cells. HE staining of the eyeball slices from the 3 animal species resulted in purplish red staining of the TM, which was highly consistent with ciliary muscle fibers. The cell?like structures on the surface of the TM were not clearly outlined, with flat nuclei showing a dark purple staining; these structures did not show obvious boundaries from the TM. Ciliary muscle fibers, which were smooth muscle cells in nature, were aligned in bundles in various directions. The longitudinally sectioned cells were flat and contained purplish cytoplasm and highly flattened nuclei. Scleral collagen fibers were stained dark red with a few fibroblasts sandwiched among them. The long axis of the fibroblasts was in parallel with that of the collagen fibers. The outline of the fibroblast was not clear and the nucleus was flat in dark blue. The vascular endothelial cells presented with different morphologies and contained light purplish cytoplasm and dark nuclei, protruding into the vascular cavity. VG staining of the TM revealed a pale red filamentous structure, and the collagen fibers were stained bright red. Masson staining of the TM showed a reticular structure consisting mainly of dark red fibers intermingled with thin green fibers. Scleral collagen fibers presented with a cord?like green wavy structure. The endothelial cells were green and flat, while the ciliary smooth muscle fibers were purple. In immunohistochemistry for α?SMA, the TM and the ciliary smooth muscle fibers showed a strong positivity in the cytoplasm, while the scleral collagen fibers and vascular endothelial cells showed negative staining; immunohistochemistry for CD31 showed no obvious positive staining in the TM, collagen fibers or ciliary smooth muscle cells from all the animals in spite of slight differences among them. The TM consists mainly of smooth muscle fibers with a thin layer of peripheral endomysium without endothelial cells.

The Weibull probabilities analysis on the single kenaf fiber

NASA Astrophysics Data System (ADS)

Ibrahim, I.; Sarip, S.; Bani, N. A.; Ibrahim, M. H.; Hassan, M. Z.

2018-05-01

Kenaf fiber has a great potential to be replaced with the synthetic composite due to their advantages such as environmentally friendly and outstanding performance. However, the main issue of this natural fiber that to be used in structural composite is inconsistency of their mechanical properties. Here, the influence of the gage length on the mechanical properties of single kenaf fiber was evaluated. This fiber was tested using the Universal testing machine at a loading rate of 1mm per min following ASTM D3822 standard. In this study, the different length of treated fiber including 20, 30 and 40mm were being tested. Following, Weibull probabilities analysis was used to characterize the tensile strength and Young modulus of kenaf fiber. The predicted average tensile strength from this approach is in good agreement with experimental results for the obtained parameter.

Droplets on bent fibers

NASA Astrophysics Data System (ADS)

Weyer, Floriane; Pan, Zhao; Pitt, William; Truscott, Tadd; Vandewalle, Nicolas

Droplets on fibers are part of our everyday lives. Many phenomena involve drops and fibers such as the formation of dew droplets on a spiderweb, the trapping of water droplets on cactus spines or the motion of droplets on wetted moss hairs. These topics have been widely studied. In particular, Lorenceau et al. determined the critical volume of a water droplet hanging on a horizontal fiber. Here, we address a similar question : we try to find out the maximum droplet size on bent fibers, which are able to hold significantly more water than horizontal fibers. Indeed, we noticed that, in nature, some specific plants can hold large rain droplets thanks to their Y-shaped leaves. We try to mimic these structures with nylon fibers, of different diameters, bent with various angles. For each set-up, the critical water volume is determined. Finally, we propose models of the physics involved in determining droplet size that could be implemented in future fiber-based microfluidic devices.

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

Processing and characterization of natural cellulose fibers/thermoset polymer composites.

PubMed

Thakur, Vijay Kumar; Thakur, Manju Kumari

2014-08-30

Recently natural cellulose fibers from different biorenewable resources have attracted the considerable attraction of research community all around the globe owing to their unique intrinsic properties such as biodegradability, easy availability, environmental friendliness, flexibility, easy processing and impressive physico-mechanical properties. Natural cellulose fibers based materials are finding their applications in a number of fields ranging from automotive to biomedical. Natural cellulose fibers have been frequently used as the reinforcement component in polymers to add the specific properties in the final product. A variety of cellulose fibers based polymer composite materials have been developed using various synthetic strategies. Seeing the immense advantages of cellulose fibers, in this article we discuss the processing of biorenewable natural cellulose fibers; chemical functionalization of cellulose fibers; synthesis of polymer resins; different strategies to prepare cellulose based green polymer composites, and diverse applications of natural cellulose fibers/polymer composite materials. The article provides an in depth analysis and comprehensive knowledge to the beginners in the field of natural cellulose fibers/polymer composites. The prime aim of this review article is to demonstrate the recent development and emerging applications of natural cellulose fibers and their polymer materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Brownian dynamics simulation of sickle hemoglobin bundle formation

NASA Astrophysics Data System (ADS)

Liu, Ya; Gunton, James; Chakrabarti, Amit

2010-03-01

The physical properties of biopolymer fibers, such as their stability and degree of aggregation, are implicated in many diseases, including sickle cell anemia. The natural chirality of protofilaments plays a crucial role in the formation of sickle hemoglobin fiber which leads to the permanent blockage of microvessels. We use Brownian dynamics to investigate the kinetics of fiber aggregation. The geometrical helical structure and chirality of the filaments are modeled by anisotropic patch-like interactions. We present the kinetics of fiber formation and study the possibility of a finite critical fiber bundle size. We compare our results with various experimental and theoretical results. This work is supported by grants from the NSF and the G. Harold and Leila Y. Mathers Foundation.

Structural analysis of Gossypium hirsutum fibers grown under greenhouse and hydroponic conditions.

PubMed

Natalio, Filipe; Tahir, Muhammad Nawaz; Friedrich, Norman; Köck, Margret; Fritz-Popovski, Gerhard; Paris, Oskar; Paschke, Reinhard

2016-06-01

Cotton is the one of the world's most important crops. Like any other crop, cotton growth/development and fiber quality is highly dependent on environmental factors. Increasing global weather instability has been negatively impacting its economy. Cotton is a crop that exerts an intensive pressure over natural resources (land and water) and demands an overuse of pesticides. Thus, the search for alternative cotton culture methods that are pesticide-free (biocotton) and enable customized standard fiber quality should be encouraged. Here we describe a culture of Gossypium hirsutum ("Upland" Cotton) utilizing a greenhouse and hydroponics in which the fibers are morphological similar to conventional cultures and structurally fit into the classical two-phase cellulose I model with 4.19nm crystalline domains surrounded by amorphous regions. These fibers exhibit a single crystalline form of cellulose I-Iß, monoclinic unit cell. Fiber quality bulk analysis shows an improved length, strength, whiteness when compared with soil-based cultures. Finally, we show that our fibers can be spun, used for production of non-woven fabrics and indigo-vat stained demonstrating its potential in industrial and commercial applications. Copyright © 2016 Elsevier Inc. All rights reserved.

What does nitric acid really do to carbon nanofibers? [What nitric acid really does to carbon nanofibers

DOE PAGES

Sainio, S.; Nordlund, D.; Gandhiraman, R.; ...

2016-09-15

Understanding the chemical nature of the surface of carbon nanofibers (CNF) is critical in assessing their fundamental properties and tailoring them for the right application. To gain such knowledge, we present here a detailed X-ray adsorption spectroscopy (XAS) study accompanied by high resolution transmission electron microscopy (TEM) micrographs of two morphologically different CNF pairs (tetrahedral amorphous carbon (ta-C) grown “open structured” fibers and traditional bamboo-like “closed structured” fibers), where the surface chemical properties and structural features of the fibers are investigated in depth and the effects of nitric acid treatment on the fibers are revealed. The morphology of the fibermore » and/or the original seed- and adhesion layers markedly affect the response of the fibers to the acid treatment. Results also show that the nitric acid treatment increases the observed sp 2 intensity and modifies the two types of fibers to become more-alike both structurally and with respect to their oxygen functionalities. Furthermore, the XAS and HRTEM results confirm that a short nitric acid treatment does not remove the Ni catalyst particle but, instead, oxidizes their surfaces, especially in the case of ta-C grown fibers.« less

What does nitric acid really do to carbon nanofibers? [What nitric acid really does to carbon nanofibers

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

Sainio, S.; Nordlund, D.; Gandhiraman, R.

Understanding the chemical nature of the surface of carbon nanofibers (CNF) is critical in assessing their fundamental properties and tailoring them for the right application. To gain such knowledge, we present here a detailed X-ray adsorption spectroscopy (XAS) study accompanied by high resolution transmission electron microscopy (TEM) micrographs of two morphologically different CNF pairs (tetrahedral amorphous carbon (ta-C) grown “open structured” fibers and traditional bamboo-like “closed structured” fibers), where the surface chemical properties and structural features of the fibers are investigated in depth and the effects of nitric acid treatment on the fibers are revealed. The morphology of the fibermore » and/or the original seed- and adhesion layers markedly affect the response of the fibers to the acid treatment. Results also show that the nitric acid treatment increases the observed sp 2 intensity and modifies the two types of fibers to become more-alike both structurally and with respect to their oxygen functionalities. Furthermore, the XAS and HRTEM results confirm that a short nitric acid treatment does not remove the Ni catalyst particle but, instead, oxidizes their surfaces, especially in the case of ta-C grown fibers.« less

Non-woven Textile Materials from Waste Fibers for Cleanup of Waters Polluted with Petroleum and Oil Products

NASA Astrophysics Data System (ADS)

Neznakomova, Margarita; Boteva, Silvena; Tzankov, Luben; Elhag, Mohamed

2018-04-01

The aim of this work was to investigate the possibility of using non-woven materials (NWM) from waste fibers for oil spill cleanup and their subsequent recovery. Manufacture of textile and readymade products generates a significant amount of solid waste. A major part of it is deposited in landfills or disposed of uncontrollably. This slowly degradable waste causes environmental problems. In the present study are used two types of NWM obtained by methods where waste fibers are utilized. Thus, real textile products are produced (blankets) with which spills are covered and removed by adsorption. These products are produced by two methods: the strengthening of the covering from recovered fibers is made by entanglement when needles of special design pass through layers (needle-punching) or by stitching with thread (technology Maliwatt). Regardless of the random nature of the fiber mixture, the investigated products are good adsorbents of petroleum products. The nature of their structure (a significant void volume and developed surface) leads to a rapid recovery of the spilled petroleum products without sinking of the fiber layer for the sampled times. The used NWM can be burned under special conditions.

A search for applications of Fiber Optics in early warning systems for natural hazards.

NASA Astrophysics Data System (ADS)

Wenker, Koen; Bogaard, Thom

2013-04-01

In order to reduce the societal risk associated with natural hazards novel technologies could help to advance in early warning systems. In our study we evaluate the use of multi-sensor technologies as possible early-warning systems for landslides and man-made structures, and the integration of the information in a simple Decision Support System (DSS). In this project, particular attention will be paid to some new possibilities available in the field of distributed monitoring systems of relevant parameters for landslide and man-made structures monitoring (such as large dams and bridges), and among them the distributed monitoring of temperature, strain and acoustic signals by FO cables. Fiber Optic measurements are becoming more and more popular. Fiber optic cables have been developed in the telecommunication business to send large amounts of information over large distances with the speed of light. Because of the commercial application, production costs are relatively low. Using fiber optics for measurements has several advantages. This novel technology is, for instance, immune to electromagnetic interference, appears stable, very accurate, and has the potential to measure several independent physical properties in a distributed manner. The high resolution spatial and temporal distributed information on e.g. temperature or strain (or both) make fiber optics an interesting measurement technique. Several applications have been developed in both engineering as science and the possibilities seem numerous. We will present a thorough literature review that was done to assess the applicability and limitations of FO cable technology. This review was focused but not limited to application in landslide research. Several examples of current practices will be shown, also from outside the natural hazard practice and possible application will be discussed.

The effect of weathering on ecopersistence, reactivity, and potential toxicity of naturally occurring asbestos and asbestiform minerals.

PubMed

Enrico Favero-Longo, Sergio; Turci, Francesco; Tomatis, Maura; Compagnoni, Roberto; Piervittori, Rosanna; Fubini, Bice

2009-01-01

The mechanisms underlying asbestos toxicity mainly rely on experiments performed on "laboratory" fibers, but little data is available on naturally occurring asbestos (NOA). Human exposure to NOA is subject to their ecopersistence and the modulation of their potential toxicity following weathering. The effect of weathering on three fibrous minerals from the Italian Western Alps, chrysotile, tremolite, and balangeroite-a Fe-rich asbestiform mineral-was investigated by mimicking more than 100 yr of physical (freezing-thawing/wetting-drying cycles in a climatic chamber) and biochemical forces (incubation with oxalic acid). Ion release, evaluated by means of inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and variation in chemical composition, evaluated by scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), indicated that weathering modified the fibers in the series: chrysotile > balangeroite > tremolite. Kinetics of ion release from the fibers (Mg, Fe, and Si) revealed different ion removal pathways. Tremolite was poorly affected. Chrysotile preferentially released cations up to a plateau, with physical and biochemical forces acting competitively. Conversely, for balangeroite, upon which weathering forces acted synergistically, the initial loss of ions facilitated further dissolution and more Si than Mg was released, suggesting an ongoing collapse of the crystal structure. Depletion of redox-reactive ions produced a significant reduction in fiber-derived *OH radicals (EPR, spin-trapping technique), but the fibrous nature was always retained. Despite weathered fibers appearing less toxic than "stored/laboratory" ones, NOA is to be considered far from safe because of fibrous nature and residual surface reactivity. Risk assessment needs to consider the effect of weathering on exposures. Both tremolite and balangeroite may contaminate, in some areas, chrysotile asbestos. However, in contrast to tremolite, balangeroite exhibits a low ecopersistence, similar to chrysotile behavior. Any contribution of balangeroite to chrysotile toxicity will thus be related to its quantitative occurrence and not to higher structural stability.

Fiber-reinforced concretes with a high fiber volume fraction — a look in future. Can a design determine the fiber amount in concrete in real time in every part of a structure in production?

NASA Astrophysics Data System (ADS)

Tepfers, R.

2010-09-01

In near future, when the control of the load-bearing capacity of fiber-only-reinforced concrete members will be safely guaranteed, the deletion of the ordinary continuous steel reinforcing bars might be possible. For the time being, it is difficult to change the fiber amount during the casting with today's techniques. Therefore, the fiber concentration has to be determined by the maximum tensile stress in concrete structural members, resulting in an unnecessary fiber addition in compressed zones. However, if the right amount of fibers could be regulated and added to concrete in real time at the pump outlet, a future vision could be to design and produce a structure by using FEM-controlled equipment. The signals from calculation results could be transmitted to a concrete casting system for addition of a necessary amount of fibers to take care of the actual tensile stresses in the right position in the structure. The casting location could be determined by using a GPS for positioning the pump outlet for targeting the casting location horizontally and a laser vertically. The addition of fibers to concrete at the outlet of a concrete pump and proportioning them there according to the actual needs of the stress situation in a structure, given by a FEM analysis in real time, is a future challenge. The FEM analysis has to be based on material properties of fiber-only-reinforced concrete. This means that the resistance and stiffness of different-strength concrete members with a varying fiber content has to be determined in tests and conveyed to the FEM analysis. The FEM analysis has to be completed before the casting and controlled. Then it can be used as the base for adding a correct amount of fibers to concrete in every part of the structure. Thus, a system for introducing a correct amount of fibers into concrete has to be developed. The fibers have to be added at the outlet of concrete pump. Maybe a system to shotcrete concrete with electronically controlled fiber addition is to be preferred? The target point where the concrete comes to rest into a structure has to be electronically noted and sent to the FEM system. The FEM analysis should then immediately send back the information for the correct amount of fibers at that point. This requires the elaboration of an appropriate signal system, which should not be impossible. An integrated system for the design and production of concrete structures could be developed excluding the heavy and time-consuming work with steel reinforcing bars. The result could be: no evaluation of moments and shear forces from a FEM analysis for determining the bar reinforcement; no bar anchorage requirements and reinforcement detailing; no reinforcement drawings; no reinforcing bars; no heavy work with the reinforcement. Finally, investigations have to be performed concerning the demolition of fiber-reinforced concrete structures and the reuse of the material. The fragments of fiber-reinforced concrete might be sticky and cause problems for nature. The recirculation of material has also to be solved.

Burning characteristics and fiber retention of graphite/resin matrix composites

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1980-01-01

Graphite fiber reinforced resin matrix composites were subjected to controlled burning conditions to determine their burning characteristics and fiber retention properties. Two types of burning equipment were used. Small samples were burned with a natural gas fired torch to study the effects of fiber orientation and structural flaws such as holes and slits that were machined into the laminates. Larger laminate samples were burned in a Heat Release Rate Calorimeter. Unidirectional epoxy/graphite and polyimide/graphite composites and boron powder filled samples of each of the two composite systems were burn tested and exposed to a thermal radiation. The effects of fiber orientation, flaws, and boron filler additives to the resins were evaluated. A high char forming polyimide resin was no more effective in retaining graphite fibers than a low char forming epoxy resin when burning in air.

Static Strength of Adhesively-bonded Woven Fabric Kenaf Composite Plates

NASA Astrophysics Data System (ADS)

Hilton, Ahmad; Lee, Sim Yee; Supar, Khairi

2017-06-01

Natural fibers are potentially used as reinforcing materials and combined with epoxy resin as matrix system to form a superior specific strength (or stiffness) materials known as composite materials. The advantages of implementing natural fibers such as kenaf fibers are renewable, less hazardous during fabrication and handling process; and relatively cheap compared to synthetic fibers. The aim of current work is to conduct a parametric study on static strength of adhesively bonded woven fabric kenaf composite plates. Fabrication of composite panels were conducted using hand lay-up techniques, with variation of stacking sequence, over-lap length, joint types and lay-up types as identified in testing series. Quasi-static testing was carried out using mechanical testing following code of practice. Load-displacement profiles were analyzed to study its structural response prior to ultimate failures. It was found that cross-ply lay-up demonstrates better static strength compared to quasi-isotropic lay-up counterparts due to larger volume of 0° plies exhibited in cross-ply lay-up. Consequently, larger overlap length gives better joining strength, as expected, however this promotes to weight penalty in the joining structure. Most samples showed failures within adhesive region known as cohesive failure modes, however, few sample demonstrated interface failure. Good correlations of parametric study were found and discussed in the respective section.

Light Like a Feather: A Fibrous Natural Composite with a Shape Changing from Round to Square.

PubMed

Wang, Bin; Meyers, Marc André

2017-03-01

Only seldom are square/rectangular shapes found in nature. One notable exception is the bird feather rachis, which raises the question: why is the proximal base round but the distal end square? Herein, it is uncovered that, given the same area, square cross sections show higher bending rigidity and are superior in maintaining the original shape, whereas circular sections ovalize upon flexing. This circular-to-square shape change increases the ability of the flight feathers to resist flexure while minimizes the weight along the shaft length. The walls are themselves a heterogeneous composite with the fiber arrangements adjusted to the local stress requirements: the dorsal and ventral regions are composed of longitudinal and circumferential fibers, while lateral walls consist of crossed fibers. This natural avian design is ready to be reproduced, and it is anticipated that the knowledge gained from this work will inspire new materials and structures for, e.g., manned/unmanned aerial vehicles.

Light Like a Feather: A Fibrous Natural Composite with a Shape Changing from Round to Square

PubMed Central

Wang, Bin

2016-01-01

Only seldom are square/rectangular shapes found in nature. One notable exception is the bird feather rachis, which raises the question: why is the proximal base round but the distal end square? Herein, it is uncovered that, given the same area, square cross sections show higher bending rigidity and are superior in maintaining the original shape, whereas circular sections ovalize upon flexing. This circular‐to‐square shape change increases the ability of the flight feathers to resist flexure while minimizes the weight along the shaft length. The walls are themselves a heterogeneous composite with the fiber arrangements adjusted to the local stress requirements: the dorsal and ventral regions are composed of longitudinal and circumferential fibers, while lateral walls consist of crossed fibers. This natural avian design is ready to be reproduced, and it is anticipated that the knowledge gained from this work will inspire new materials and structures for, e.g., manned/unmanned aerial vehicles. PMID:28331789

Investigation on Suitability of Natural Fibre as Replacement Material for Table Tennis Blade

NASA Astrophysics Data System (ADS)

Arifin, A. M. T.; Fahrul Hassan, M.; Ismail, A. E.; Zulafif Rahim, M.; Rasidi Ibrahim, M.; Haq, R. H. Abdul; Rahman, M. N. A.; Yunos, M. Z.; Amin, M. H. M.

2017-08-01

This paper presents an investigation of suitability natural fibre as replacement material for table tennis blade, due to low cost, lightweight and apparently environmentally. Nowadays, natural fibre are one of the materials often used in replaced the main material on manufacturing sector, such as automotive, and construction. The objective of this study is to investigate and evaluate the suitability natural fiber materials to replace wood as a structure on table tennis blade. The mechanical properties of the different natural fibre material were examined, and correlated with characteristic of table tennis blade. The natural fibre selected for the study are kenaf (Hibiscus Cannabinus), jute, hemp, sisal (Agave Sisalana) and ramie. A further comparison was made with the corresponding properties of each type of natural fiber using Quality Function Deployment (QFD) and Theory of Inventive Problem Solving (TRIZ). TRIZ has been used to determine the most appropriate solution in producing table tennis blade. The results showed the most appropriate solution in producing table tennis blade using natural fibre is kenaf natural fibre. The selected on suitability natural fibre used as main structure on table tennis blade are based on the characteristics need for good performance of table tennis blade, such as energy absorption, lightweight, strength and hardness. Therefore, it shows an opportunity for replacing existing materials with a higher strength, lower cost alternative that is environmentally friendly.

Impact analysis of natural fiber and synthetic fiber reinforced polymer composite

NASA Astrophysics Data System (ADS)

Sangamesh, Ravishankar, K. S.; Kulkarni, S. M.

2018-05-01

Impact analysis of the composite structure is essential for many fields like automotive, aerospace and naval structure which practically difficult to characterize. In the present study impact analysis of carbon-epoxy (CE) and jute-epoxy (JE) laminates were studied for three different thicknesses. The 3D finite element model was adopted to study the impact forces experienced, energy absorption and fracture behavior of the laminated composites. These laminated composites modeled as a 3D deformable solid element and an impactor at a constant velocity were modeled as a discrete rigid element. The energy absorption and fracture behaviors for various material combinations and thickness were studied. The fracture behavior of these composite showed progressive damage with matrix failure at the initial stage followed by complete fiber breakage.

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.

Experimental Investigations on Thermal Conductivity of Fenugreek and Banana Composites

NASA Astrophysics Data System (ADS)

Pujari, Satish; Venkatesh, Talari; Seeli, Hepsiba

2018-04-01

The use of composite materials in manufacturing has significantly increased in the past decade. Research is being done to identify natural fibers that can be used as composites. Several natural fibers are already being used in the industry as composites. The appealing advantages of using natural fibers are reflected in lower density when compared to synthetic fibers and also in saving costs. This research paper highlights the experiment that analyses the use of biodegradable fenugreek composite as natural fiber and concludes that fenugreek natural fibers are an excellent substitute to the synthetic fibers in terms of reinforcement properties for the polymers. These fenugreek fibers are naturally sourced, renewable, cost effective and bio-friendly. In thermal energy storage systems as well as in air conditioning systems, thermal insulators are predominantly used to enhance the storage properties. An experiment was created to investigate the thermal properties of fenugreek banana composites for different fiber concentrations. The experimental results showed that the thermal conductivity of the composites decrease with an increase in the fiber content. The experimental results were compared with the theoretical models to describe the variation of thermal conductivity with the volume fraction of the fiber. Good agreement between theoretical and experimental results was observed.

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

An, Bo; Jenkins, Janelle E; Sampath, Sujatha

Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders, N. clavipes and A. aurantia, indicates that MaSp1 proteins are more easily formed into β-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this behavior of natural silk proteins could be reproduced by recombinantly produced spider silk mimic protein, recombinant MaSp1/MaSp2 mixed fibers as well asmore » chimeric silk fibers from MaSp1 and MaSp2 sequences in a single protein were produced based on the variable ratio and conserved motifs of MaSp1 and MaSp2 in native silk fiber. Mechanical properties, solid-state NMR, and XRD results of tested synthetic fibers indicate the differing roles of MaSp1 and MaSp2 in the fiber and verify the importance of postspin stretching treatment in helping the fiber to form the proper spatial structure.« less

Design of vibration sensor based on fiber Bragg grating

NASA Astrophysics Data System (ADS)

Zhang, Zhengyi; Liu, Chuntong

2017-12-01

Fiber grating is a kind of new type of fiber optic light source device which has been rapidly changing in the refractive index of the core in recent years. Especially, it can realize the high precision of the external parameters by means of the special structure design and the encapsulation technology [1, 2]. In this paper, a fiber grating vibration sensor which is suitable for vibration monitoring in key areas is designed based on the technical background of vibration monitoring system. The sensor uses a single beam structure and pastes the fiber Bragg grating (FBG) to measure the vibration wavelength on the surface. When the vibration is simply harmonic vibration, the Bragg reflection wavelength will change periodically, and the periodic variation of the wavelength curve can be measured by the fiber grating demodulator, then the correctness of the experimental results is verified. In this paper, through the analysis of the data measured by the demodulator, the MATLAB software is used to verify the data, and the different frequency domains, the modes, and the phase frequency curves are obtained. The measurement range is 0 Hz-100 Hz, and the natural frequency is 90.6 Hz.

Towards Silk Fiber Optics: Refractive Index Characterization, Fiber Spinning, and Spinneret Analysis

NASA Astrophysics Data System (ADS)

Spitzberg, Joshua David

Of the many biologically derived materials, whose historical record of use by humans underscores an ex-vivo utility, silk is interesting for it's contemporary repurposing from textile to biocompatible substrate. And while even within this category silk is one of several materials studied for novel repurposing, it has the unique character of being evolutionarily developed specifically for fiber spinning in vivo. The work discussed here is inspired by taking what nature has given, to explore the in vitro spinning of silk towards biocompatible fiber optics applications. A common formulation of silk used in biomedical studies for re-forming it into the various structures begins with the silkworm cocoon, which is degummed and dissolved into an aqueous solution of its miscible protein, fibroin, and post-treated to fabricate solid structures. In the first aim, the optical refractive index (RI) of various post-treatment methods is discussed towards determining RI design techniques. The methods considered in this work for re-forming a solid fiber from the reconstituted silk fibroin (RSF) solution borrow from the industrial techniques of gel spinning, and dry-spinning. In the second aim, methods are applied to RSF and quality of the spun fibers discussed. A feature common to spinning techniques is passing the (silk) material through a spinneret of specific shape. In the third aim, fluid flow through a simplified native silkworm spinneret is modeled towards bio-inspired lessons in design. In chapter 1 the history, reconstitution, are discussed towards understanding the fabrication of several optical device examples. Chapter 2 then prefaces the experiments and measurements in fiber optics by reviewing electromagnetic theory of waveguide function, and loss factors, to be considered in actual device fabrication. Chapter 3 presents results and discussion for the first aim, understanding design principles for the refractive index of RSF. From this point, industrial fiber-spinning approaches are reviewed from a theoretical and methodological perspective in chapter 4. Thus, chapter 5 presents results for the second aim, efforts to apply these techniques using RSF. Chapter 6 discusses the third aim, understanding the design of the silkworm spinneret by an idealized model of natural and reconstituted silk fibroin flow. While the ultimate goal of a structurally and optically smooth and uniform fiber remains elusive, this work serves as a guide for future efforts.

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.

Quantification of collagen fiber organization in biological tissues at cellular and molecular scales using second-harmonic generation imaging

NASA Astrophysics Data System (ADS)

Ambekar Ramachandra Rao, Raghu

Collagen is the most abundant structural protein found in the human body, and is responsible for providing structure and function to tissues. Collagen molecules organize naturally into structures called fibers on the scale of the wavelength of light and lack inversion symmetry, thus allowing for the process of second harmonic generation (SHG) when exposed to intense incident light. We have developed two quantitative techniques: Fourier transform-second-harmonic generation (FT-SHG) imaging and generalized chi2 second-harmonic generation (chi2-SHG) imaging. In order to show that FT-SHG imaging can be used as a valuable diagnostic tool for real-world biological problems, we first investigate collagenase-induced injury in horse tendons. Clear differences in collagen fiber organization between normal and injured tendon are quantified. In particular, we observe that the regularly oriented organization of collagen fibers in normal tendons is disrupted in injured tendons leading to a more random organization. We also observe that FT-SHG microscopy is more sensitive in assessing tendon injury compared to the conventional polarized light microscopy. The second study includes quantifying collagen fibers in cortical bone using FT-SHG imaging and comparing it with scanning electron microscopy (SEM). Further, as an example study, we show how FT-SHG imaging could be used to quantify changes in bone structure as a function of age. Some initial work and future directions for extending FT-SHG to 3D are also discussed. The second technique, chi2-SHG imaging, takes advantage of the coherent nature of SHG and utilizes polarization to extract the second-order susceptibility (d elements) which provides information on molecular organization, i.e., it provides access to sub-diffractional changes "optically". We use chi2-SHG in combination with FT-SHG imaging to investigate a couple of biological problems. First, we quantify differences in collagen fiber organization between cornea and sclera of the eye in order to investigate their properties of transparency and opacity, respectively. We find from chi2-SHG imaging that there is no statistical difference in the values of d elements between cornea and sclera, indicating that the underlying collagen structure generating SHG from the two is similar at the level of detection of SHG microscopy. However, the difference lies in the spatial organization of these collagen fibers as observed from FT-SHG imaging. We find that cornea contains lamellae with patches of ordered and uniform diameter collagen fibers with axial order, which could be the reason for its transparent behavior. Conversely, there are no lamellae in sclera (i.e., no axial order), and fibers are thicker, denser, have inconsistent diameters, and possess relatively inhomogeneous orientations, leading to its opaque nature. We also utilized the two techniques to assess differences in stromal collagen fibers for several human breast tissue conditions: normal, hyperplasia, dysplasia, and malignant. Using FT-SHG imaging, we note differences between malignant and other pathological conditions through the metric A.I. ratio. Using generalized chi2-SHG imaging, we observe structural changes in collagen at the molecular scale, and a particular d element showed a more sensitive differentiation between breast tissue conditions, except between hyperplasia and normal/dysplasia. We also find that the trigonal symmetry (3m) is a more appropriate model to describe collagen fibers in malignant tissues as opposed to the conventionally used hexagonal symmetry (C6). Furthermore, the percentage of abnormal collagen fibers could potentially be used as a metric for differentiating breast tissue conditions. We also introduce a technique for extending chi2-SHG to fibers with curvature which is useful for generating chi2-image maps (in terms of d elements) instead of the conventional SHG intensity images. The spatial variations in d elements will provide additional information. For example, in breast cancer tissues, it may help in observing how fibers change from normal to malignant spatially, especially around region of cancerous cells. Finally, we discuss some of the interesting immediate and later future work of quantitative SHG imaging we aim to carry out in our lab. (Abstract shortened by UMI.)

16 CFR 1630.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 1-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

16 CFR 1630.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 1-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

16 CFR 1630.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 1-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

16 CFR 1631.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 2-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

16 CFR 1631.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 2-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

16 CFR 1631.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 2-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

The phosphatidylinositol synthase gene (GhPIS) contributes to longer, stronger, and finer fibers in cotton.

PubMed

Long, Qin; Yue, Fang; Liu, Ruochen; Song, Shuiqing; Li, Xianbi; Ding, Bo; Yan, Xingying; Pei, Yan

2018-05-11

Cotton fibers are the most important natural raw material used in textile industries world-wide. Fiber length, strength, and fineness are the three major traits which determine the quality and economic value of cotton. It is known that exogenous application of phosphatidylinositols (PtdIns), important structural phospholipids, can promote cotton fiber elongation. Here, we sought to increase the in planta production of PtdIns to improve fiber traits. Transgenic cotton plants were generated in which the expression of a cotton phosphatidylinositol synthase gene (i.e., GhPIS) was controlled by the fiber-specific SCFP promoter element, resulting in the specific up-regulation of GhPIS during cotton fiber development. We demonstrate that PtdIns content was significantly enhanced in transgenic cotton fibers and the elevated level of PtdIns stimulated the expression of genes involved in PtdIns phosphorylation as well as promoting lignin/lignin-like phenolic biosynthesis. Fiber length, strength and fineness were also improved in the transgenic plants as compared to the wild-type cotton, with no loss in overall fiber yield. Our data indicate that fiber-specific up-regulation of PtdIns synthesis is a promising strategy for cotton fiber quality improvement.

Tin anode for sodium-ion batteries using natural wood fiber as a mechanical buffer and electrolyte reservoir.

PubMed

Zhu, Hongli; Jia, Zheng; Chen, Yuchen; Weadock, Nicholas; Wan, Jiayu; Vaaland, Oeyvind; Han, Xiaogang; Li, Teng; Hu, Liangbing

2013-07-10

Sodium (Na)-ion batteries offer an attractive option for low cost grid scale storage due to the abundance of Na. Tin (Sn) is touted as a high capacity anode for Na-ion batteries with a high theoretical capacity of 847 mAh/g, but it has several limitations such as large volume expansion with cycling, slow kinetics, and unstable solid electrolyte interphase (SEI) formation. In this article, we demonstrate that an anode consisting of a Sn thin film deposited on a hierarchical wood fiber substrate simultaneously addresses all the challenges associated with Sn anodes. The soft nature of wood fibers effectively releases the mechanical stresses associated with the sodiation process, and the mesoporous structure functions as an electrolyte reservoir that allows for ion transport through the outer and inner surface of the fiber. These properties are confirmed experimentally and computationally. A stable cycling performance of 400 cycles with an initial capacity of 339 mAh/g is demonstrated; a significant improvement over other reported Sn nanostructures. The soft and mesoporous wood fiber substrate can be utilized as a new platform for low cost Na-ion batteries.

Synthetic spider silk production on a laboratory scale.

PubMed

Hsia, Yang; Gnesa, Eric; Pacheco, Ryan; Kohler, Kristin; Jeffery, Felicia; Vierra, Craig

2012-07-18

As society progresses and resources become scarcer, it is becoming increasingly important to cultivate new technologies that engineer next generation biomaterials with high performance properties. The development of these new structural materials must be rapid, cost-efficient and involve processing methodologies and products that are environmentally friendly and sustainable. Spiders spin a multitude of different fiber types with diverse mechanical properties, offering a rich source of next generation engineering materials for biomimicry that rival the best manmade and natural materials. Since the collection of large quantities of natural spider silk is impractical, synthetic silk production has the ability to provide scientists with access to an unlimited supply of threads. Therefore, if the spinning process can be streamlined and perfected, artificial spider fibers have the potential use for a broad range of applications ranging from body armor, surgical sutures, ropes and cables, tires, strings for musical instruments, and composites for aviation and aerospace technology. In order to advance the synthetic silk production process and to yield fibers that display low variance in their material properties from spin to spin, we developed a wet-spinning protocol that integrates expression of recombinant spider silk proteins in bacteria, purification and concentration of the proteins, followed by fiber extrusion and a mechanical post-spin treatment. This is the first visual representation that reveals a step-by-step process to spin and analyze artificial silk fibers on a laboratory scale. It also provides details to minimize the introduction of variability among fibers spun from the same spinning dope. Collectively, these methods will propel the process of artificial silk production, leading to higher quality fibers that surpass natural spider silks.

Synthetic Spider Silk Production on a Laboratory Scale

PubMed Central

Hsia, Yang; Gnesa, Eric; Pacheco, Ryan; Kohler, Kristin; Jeffery, Felicia; Vierra, Craig

2012-01-01

As society progresses and resources become scarcer, it is becoming increasingly important to cultivate new technologies that engineer next generation biomaterials with high performance properties. The development of these new structural materials must be rapid, cost-efficient and involve processing methodologies and products that are environmentally friendly and sustainable. Spiders spin a multitude of different fiber types with diverse mechanical properties, offering a rich source of next generation engineering materials for biomimicry that rival the best manmade and natural materials. Since the collection of large quantities of natural spider silk is impractical, synthetic silk production has the ability to provide scientists with access to an unlimited supply of threads. Therefore, if the spinning process can be streamlined and perfected, artificial spider fibers have the potential use for a broad range of applications ranging from body armor, surgical sutures, ropes and cables, tires, strings for musical instruments, and composites for aviation and aerospace technology. In order to advance the synthetic silk production process and to yield fibers that display low variance in their material properties from spin to spin, we developed a wet-spinning protocol that integrates expression of recombinant spider silk proteins in bacteria, purification and concentration of the proteins, followed by fiber extrusion and a mechanical post-spin treatment. This is the first visual representation that reveals a step-by-step process to spin and analyze artificial silk fibers on a laboratory scale. It also provides details to minimize the introduction of variability among fibers spun from the same spinning dope. Collectively, these methods will propel the process of artificial silk production, leading to higher quality fibers that surpass natural spider silks. PMID:22847722

Some Structural Observations of Self-Assembling, Fibrillar Gels Composed of Two-Directional Bolaform Arborols

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

Sun, J.

2005-01-12

Arborols are dumbbell shaped molecules (bolaform amphiphiles) in which a hydrophobic spacer separates two hydrophilic end groups. They are a valuable model for naturally occurring fibers, such as actin or amyloid. Applications to materials science can be envisioned. On cooling from warm aqueous or methanolic solutions, arborols spontaneously assemble into long fibers. When the solutions are above a certain concentration that depends on the hydrophilic/hydrophobic balance, this leads to thermally reversible gels stabilized by a mechanism that is poorly understood. With the help of wide angle X-ray scattering, details of the arborol fiber and gel structure were obtained on wetmore » gels. The characteristic dimensions of the fibers vary in a sensible fashion with the molecular specifics. Solvent character appears to affect the average domain length of arborols stacked into fibers. Fluorescently labeled arborols were prepared. The label does not prevent incorporation into the fibrillar structure, rendering fibril bundles visible in wet gels. Bundles are visible in concentrated gels, but not in less concentrated sols. These results are consistent with observations of dried arborols using atomic force microscopy and with previously published freeze-fracture electron microscopy and small angle X-ray scattering experiments on dried gels.« less

Experimental evaluation and simulation of volumetric shrinkage and warpage on polymeric composite reinforced with short natural fibers

NASA Astrophysics Data System (ADS)

Santos, Jonnathan D.; Fajardo, Jorge I.; Cuji, Alvaro R.; García, Jaime A.; Garzón, Luis E.; López, Luis M.

2015-09-01

A polymeric natural fiber-reinforced composite is developed by extrusion and injection molding process. The shrinkage and warpage of high-density polyethylene reinforced with short natural fibers of Guadua angustifolia Kunth are analyzed by experimental measurements and computer simulations. Autodesk Moldflow® and Solid Works® are employed to simulate both volumetric shrinkage and warpage of injected parts at different configurations: 0 wt.%, 20 wt.%, 30 wt.% and 40 wt.% reinforcing on shrinkage and warpage behavior of polymer composite. Become evident the restrictive effect of reinforcing on the volumetric shrinkage and warpage of injected parts. The results indicate that volumetric shrinkage of natural composite is reduced up to 58% with fiber increasing, whereas the warpage shows a reduction form 79% to 86% with major fiber content. These results suggest that it is a highly beneficial use of natural fibers to improve the assembly properties of polymeric natural fiber-reinforced composites.

Infrared spectroscopic investigations on the distribution of residual grease on textiles

NASA Astrophysics Data System (ADS)

Siedler, J.; Schumacher-Hamedat, Ursula; Hoecker, Hartwig

1992-03-01

Surface modification of textile materials is of major importance in the modern textile industry. Several methods are commonly applied to produce a broad range of coated materials. The adhesion between the coating polymers and the textile fibers often determines the quality. Improved adhesion of the coating is achieved by a chemical bonding (covalent or ionic) between the coating materials and the textile. The efficiency,however, is dependent on the orientation of the functional groups of the outmost molecular layers of the fibers. Therefore, we have used surface sensitive methods to analyze the surface structure of proteinaceous fibers. Homopoly(aminoacid) films like poly(-(gamma) -benzyl-L-glutamate) and poly(- (Beta) -benzyl-L-aspartate) have been chosen as models for natural fibers like wool.

Significant aspects on thermal degradation of hybrid biocomposite material

NASA Astrophysics Data System (ADS)

Bavan, D. Saravana; Kumar, G. C. Mohan

2013-06-01

Interest in use of bio fibers is increasing rapidly in structural and automotive applications because of few important properties such as low density, mechanical properties, renewability, biodegradation and sustainability. The present work is focused on fabricating a hybrid bio-composite material processed through compression molding technique. Natural fibers of maize and jute with bio polymeric resin of epoxidized soya bean oil are used as a matrix in obtaining a hybrid bio composite material. Thermal degradation of the prepared material is studied through Thermal gravimetric analyzer. Chemical treatment of the fibers was performed to have a better adhesion between the fibers and the matrix. The work is also surveyed on various parameters influencing the thermal properties and other aspects for a hybrid bio composite material.

Tensile Mechanical Property of Oil Palm Empty Fruit Bunch Fiber Reinforced Epoxy Composites

NASA Astrophysics Data System (ADS)

Ghazilan, A. L. Ahmad; Mokhtar, H.; Shaik Dawood, M. S. I.; Aminanda, Y.; Ali, J. S. Mohamed

2017-03-01

Natural, short, untreated and randomly oriented oil palm empty fruit bunch fiber reinforced epoxy composites were manufactured using vacuum bagging technique with 20% fiber volume composition. The performance of the composite was evaluated as an alternative to synthetic or conventional reinforced composites. Tensile properties such as tensile strength, modulus of elasticity and Poisson’s ratio were compared to the tensile properties of pure epoxy obtained via tensile tests as per ASTM D 638 specifications using Universal Testing Machine INSTRON 5582. The tensile properties of oil palm empty fruit bunch fiber reinforced epoxy composites were lower compared to plain epoxy structure with the decrement in performances of 38% for modulus of elasticity and 61% for tensile strength.

Biomimetic Structural Materials: Inspiration from Design and Assembly.

PubMed

Yaraghi, Nicholas A; Kisailus, David

2018-04-20

Nature assembles weak organic and inorganic constituents into sophisticated hierarchical structures, forming structural composites that demonstrate impressive combinations of strength and toughness. Two such composites are the nacre structure forming the inner layer of many mollusk shells, whose brick-and-mortar architecture has been the gold standard for biomimetic composites, and the cuticle forming the arthropod exoskeleton, whose helicoidal fiber-reinforced architecture has only recently attracted interest for structural biomimetics. In this review, we detail recent biomimetic efforts for the fabrication of strong and tough composite materials possessing the brick-and-mortar and helicoidal architectures. Techniques discussed for the fabrication of nacre- and cuticle-mimetic structures include freeze casting, layer-by-layer deposition, spray deposition, magnetically assisted slip casting, fiber-reinforced composite processing, additive manufacturing, and cholesteric self-assembly. Advantages and limitations to these processes are discussed, as well as the future outlook on the biomimetic landscape for structural composite materials.

Biomimetic Structural Materials: Inspiration from Design and Assembly

NASA Astrophysics Data System (ADS)

Yaraghi, Nicholas A.; Kisailus, David

2018-04-01

Nature assembles weak organic and inorganic constituents into sophisticated hierarchical structures, forming structural composites that demonstrate impressive combinations of strength and toughness. Two such composites are the nacre structure forming the inner layer of many mollusk shells, whose brick-and-mortar architecture has been the gold standard for biomimetic composites, and the cuticle forming the arthropod exoskeleton, whose helicoidal fiber-reinforced architecture has only recently attracted interest for structural biomimetics. In this review, we detail recent biomimetic efforts for the fabrication of strong and tough composite materials possessing the brick-and-mortar and helicoidal architectures. Techniques discussed for the fabrication of nacre- and cuticle-mimetic structures include freeze casting, layer-by-layer deposition, spray deposition, magnetically assisted slip casting, fiber-reinforced composite processing, additive manufacturing, and cholesteric self-assembly. Advantages and limitations to these processes are discussed, as well as the future outlook on the biomimetic landscape for structural composite materials.

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

Carbon Microfibers with Hierarchical Porous Structure from Electrospun Fiber-Like Natural Biopolymer

NASA Astrophysics Data System (ADS)

Liang, Yeru; Wu, Dingcai; Fu, Ruowen

2013-01-01

Electrospinning offers a powerful route for building one-dimensional (1D) micro/nanostructures, but a common requirement for toxic or corrosive organic solvents during the preparation of precursor solution has limited their large scale synthesis and broad applications. Here we report a facile and low-cost way to prepare 1D porous carbon microfibers by using an electrospun fiber-like natural product, i.e., silk cocoon, as precursor. We surprisingly found that by utilizing a simple carbonization treatment, the cocoon microfiber can be directly transformed into 1D carbon microfiber of ca. 6 μm diameter with a unique three-dimensional porous network structure composed of interconnected carbon nanoparticles of 10~40 nm diameter. We further showed that the as-prepared carbon product presents superior electrochemical performance as binder-free electrodes of supercapacitors and good adsorption property toward organic vapor.

Wavelength shifts of cladding-mode resonance in corrugated long-period fiber gratings under torsion.

PubMed

Ivanov, Oleg V; Wang, Lon A

2003-05-01

A finite deformation theory of elasticity and a theory of nonlinear photoelasticity are applied to describe the wavelength shifts of cladding-mode resonance in corrugated long-period fiber gratings under torsion. The deformation of fiber is found by use of the Murnaghan model of a solid elastic body. The quadratic photoelastic effect that is proportional to the second-order displacement gradient is investigated and compared with the classical photoelastic effect. The electromagnetic field in the twisted corrugated structure is presented as a superposition of circularly polarized modes of the etched fiber section. The wavelength shift is found to be proportional to the square of the twist angle. As predicted by our theory, a wavelength shift of the same nature has been found in a conventionally photoinduced long-period fiber grating.

In-Fiber Optic Salinity Sensing: A Potential Application for Offshore Concrete Structure Protection.

PubMed

Luo, Dong; Li, Peng; Yue, Yanchao; Ma, Jianxun; Yang, Hangzhou

2017-05-04

The protection of concrete structures against corrosion in marine environments has always been a challenge due to the presence of a saline solution-A natural corrosive agent to the concrete paste and steel reinforcements. The concentration of salt is a key parameter influencing the rate of corrosion. In this paper, we propose an optical fiber-based salinity sensor based on bundled multimode plastic optical fiber (POF) as a sensor probe and a concave mirror as a reflector in conjunction with an intensity modulation technique. A refractive index (RI) sensing approach is analytically investigated and the findings are in agreement with the experimental results. A maximum sensitivity of 14,847.486/RIU can be achieved at RI = 1.3525. The proposed technique is suitable for in situ measurement and monitoring of salinity in liquid.

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

Westman, Matthew P.; Fifield, Leonard S.; Simmons, Kevin L.

The need for renewable fiber reinforced composites has never been as prevalent as it currently is. Natural fibers offer both cost savings and a reduction in density when compared to glass fibers. Though the strength of natural fibers is not as great as glass, the specific properties are comparable. Currently natural fiber composites have two issues that need to be addressed: resin compatibility and water absorption. The following preliminary research has investigated the use of Kenaf, Hibiscus cannabinus, as a possible glass replacement in fiber reinforced composites.

Understanding the interdiffusion behavior and determining the long term stability of tungsten fiber reinforced niobium-base matrix composite systems

NASA Technical Reports Server (NTRS)

Tien, John K.

1990-01-01

The long term interdiffusional stability of tungsten fiber reinforced niobium alloy composites is addressed. The matrix alloy that is most promising for use as a high temperature structural material for reliable long-term space power generation is Nb1Zr. As an ancillary project to this program, efforts were made to assess the nature and kinetics of interphase reaction between selected beryllide intermetallics and nickel and iron aluminides.

Spider Gland Fluids: From Protein-Rich Isotropic Liquid to Insoluble Super Fiber

DTIC Science & Technology

2013-09-17

natural gland fluids with solid-state NMR can be used to guide the production of synthetic spider silk fibers that more closely match native spider silk...duct contents in combination with micro -imaging. An ability to conduct NMR spectroscopy in combination with MRI will provide us with a structural...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Arizona State University,Tempe,AZ,85281 8. PERFORMING ORGANIZATION

Coating applications to natural fiber composites to improve their physical, surface and water absorption characters

USDA-ARS?s Scientific Manuscript database

Natural (organic) fibers are used in reinforced composites and natural fiber composites (NFCs). These fibers have advantages over synthetic composites such as high mechanical properties, lower densities and biodegradablity. However, one major disadvantage of NFCs is their hydrophilicity. In this stu...

Effects of heat treatment on the mechanical properties of kenaf fiber

NASA Astrophysics Data System (ADS)

Carada, Paulo Teodoro D. L.; Fujii, Toru; Okubo, Kazuya

2016-05-01

Natural fibers are utilized in various ways. One specific application of it, is in the field natural fiber composite (NFC). Considerable amount of researches are conducted in this field due to rising concerns in the harmful effects of synthetic materials to the environment. Additionally, these researches are done in order to overcome the drawbacks which limit the wide use of natural fiber. A way to improve NFC is to look into the reinforcing component (natural fiber). Treatments, which are classified as mechanical or chemical in nature, can be done in order to improve the performance of the natural fiber. The aim of this study is to assess the effects of heat treatment in the mechanical properties of kenaf fiber. In addition, the response of mechanical properties after exposure to high moisture environment of heat-treated kenaf fibers was observed. Heat treatment was done for one hour with the following heating temperatures: 140, 160, 180, and 200 °C. X-ray diffraction analysis was done to calculate the crystallinity index of kenaf fibers after heat treatment. The results showed that increase in tensile strength can be attained when kenaf fibers are heat treated at 140 °C. However, the tensile modulus showed inconsistency with respect to heat treatment temperature. The computed crystallinity index of the fiber matched the tensile strength observed in non-treated and heat-treated kenaf fibers. The results obtained in this study can be used for applications where heat treatment on kenaf fibers is needed.

Effects of heat treatment on the mechanical properties of kenaf fiber

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

Carada, Paulo Teodoro D. L.; Fujii, Toru; Okubo, Kazuya

Natural fibers are utilized in various ways. One specific application of it, is in the field natural fiber composite (NFC). Considerable amount of researches are conducted in this field due to rising concerns in the harmful effects of synthetic materials to the environment. Additionally, these researches are done in order to overcome the drawbacks which limit the wide use of natural fiber. A way to improve NFC is to look into the reinforcing component (natural fiber). Treatments, which are classified as mechanical or chemical in nature, can be done in order to improve the performance of the natural fiber. Themore » aim of this study is to assess the effects of heat treatment in the mechanical properties of kenaf fiber. In addition, the response of mechanical properties after exposure to high moisture environment of heat-treated kenaf fibers was observed. Heat treatment was done for one hour with the following heating temperatures: 140, 160, 180, and 200 °C. X-ray diffraction analysis was done to calculate the crystallinity index of kenaf fibers after heat treatment. The results showed that increase in tensile strength can be attained when kenaf fibers are heat treated at 140 °C. However, the tensile modulus showed inconsistency with respect to heat treatment temperature. The computed crystallinity index of the fiber matched the tensile strength observed in non-treated and heat-treated kenaf fibers. The results obtained in this study can be used for applications where heat treatment on kenaf fibers is needed.« less

Portable Ultrasonic Guided Wave Inspection with MACRO Fiber Composite Actuators

NASA Astrophysics Data System (ADS)

Haig, A.; Mudge, P.; Catton, P.; Balachandran, W.

2010-02-01

The development of portable ultrasonic guided wave transducer arrays that utilize Macro Fiber Composite actuators (MFCs) is described. Portable inspection equipment can make use of ultrasonic guided waves to rapidly screen large areas of many types of engineering structures for defects. The defect finding performance combined with the difficulty of application determines how much the engineering industry makes use of this non-destructive, non-disruptive technology. The developments with MFCs have the potential to make considerable improvements in both these aspects. MFCs are highly efficient because they use interdigital electrodes to facilitate the extensional, d33 displacement mode. Their fiber composite design allows them to be thin, lightweight, flexible and durable. The flexibility affords them conformance with curved surfaces, which can facilitate good mechanical coupling. The suitability of a given transducer for Long Range Ultrasonic Testing is governed by the nature and amplitude of the displacement that it excites/senses in the contact area of the target structure. This nature is explored for MFCs through directional sensitivity analysis and empirical testing. Housing methods that facilitate non-permanent coupling techniques are discussed. Finally, arrangements of arrays of MFCs for the guided wave inspection of plates and pipes are considered and some broad design criteria are given.

Mechanical properties evaluation of single and hybrid composites polyester reinforced bamboo, PALF and coir fiber

NASA Astrophysics Data System (ADS)

Rihayat, T.; Suryani, S.; Fauzi, T.; Agusnar, H.; Wirjosentono, B.; Syafruddin; Helmi; Zulkifli; Alam, P. N.; Sami, M.

2018-03-01

This study aims to determine the composition fiber natural of bamboo, pineapple leaf and coir in single and hybrid composite to see the best characteristics of tensile strength and flexural test by using a Universal Testing Machine (UTM) and observe the effect on the microstructure of the composite through optical and scanning electron microscopy. Bamboo, Palf and coir have synthesis from natural fiber was used as reinforcement in polyester composite using hand lay up or a hot-compression moulding while filler:matrix was used (45%:55wt.%, 70%:30wt.% and 15%:85wt.%). From the variation of the volume fraction between filler and matrix show that mechanical properties of composites increased with increasing amount of filler in the matrix. This is evidenced by the high mechanical properties A:B:C/Ps in compositions 45%: 55wt.% 136 Mpa while flexural strength 93 N and good structure surface morphology. This research has produced a hybrid composite materials that have high mechanical properties and bending compared with conventional synthetic fibers and other materials.

Observation of triple helix motif on electrospun collagen nanofibers and its effect on the physical and structural properties

NASA Astrophysics Data System (ADS)

Bürck, Jochen; Aras, Onur; Bertinetti, Luca; Ilhan, Caner A.; Ermeydan, Mahmut A.; Schneider, Reinhard; Ulrich, Anne S.; Kazanci, Murat

2018-01-01

Collagen is a very popular natural biomaterial due to its high biocompatibility and bioactivity. Electrospinning is currently the only technique that allows the fabrication of continuous fibers with diameters down to a few nanometers. In order to regenerate collagen in the forms of nanofibers, it is necessary to dissolve it in suitable solvents. The solvents and electrospinning process cause unfolding of collagen nanofibers. It is proposed that acidic solvents preserve better the natural structure of collagen fibers. In this paper, the structures of collagen nanofibers were examined by using circular dichroism (CD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, differential scanning calorimetry (DSC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) methods in order to test this hypothesis. The increase in PP-II fraction, representing the triple helix structure in collagen, that was observed in CD analysis of HAc derived collagen nanofibers, for the first time was successfully confirmed and illustrated by using SEM and TEM methods. Furthermore, CD revealed the mostly detrimental effect of stabilization conditions such as heat, vacuum and UV treatment on the secondary structure of the collagen nanofibers.

16 CFR § 1630.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 1-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

16 CFR § 1631.61 - Hide carpets and rugs-alternative washing procedure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... natural “lay” of the hair structure for ten complete strokes. (8) Place test specimen in a circulating... procedure under FF 2-70 for testing the flammability of shearling and hide rugs that (1) consist of natural wool or hair attached to the hide with no synthetic fibers and (2) have been treated with a fire...

Nanoparticulate hollow TiO2 fibers as light scatterers in dye-sensitized solar cells: layer-by-layer self-assembly parameters and mechanism.

PubMed

Rahman, Masoud; Tajabadi, Fariba; Shooshtari, Leyla; Taghavinia, Nima

2011-04-04

Hollow structures show both light scattering and light trapping, which makes them promising for dye-sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO(2) fibers are prepared by layer-by-layer (LbL) self-assembly deposition of TiO(2) nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO(2) dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes (poly(diallyldimethylammonium chloride), PDDA). Decreasing the molecular weight of the polyelectrolyte results in more deposition of nanoparticles in each dip cycle with narrower pore size distribution. Fibers prepared by the deposition of crystalline TiO(2) nanoparticles show higher surface area and higher pore volume than amorphous nanoparticles. Scattering coefficients and backscattering properties of fibers are investigated and compared with those of commercial P25 nanoparticles. Composite P25-fiber films are electrophoretically deposited and employed as the photoanode in DSSC. Photoelectrochemical measurements showed an increase of around 50% in conversion efficiency. By employing the intensity-modulated photovoltage and photocurrent spectroscopy methods, it is shown that the performance improvement due to addition of fibers is mostly due to the increase in light-harvesting efficiency. The high surface area due to the nanoparticulate structure and strong light harvesting due to the hollow structure make these fibers promising scatterers in DSSCs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Engineering cellular fibers for musculoskeletal soft tissues using directed self-assembly.

PubMed

Schiele, Nathan R; Koppes, Ryan A; Chrisey, Douglas B; Corr, David T

2013-05-01

Engineering strategies guided by developmental biology may enhance and accelerate in vitro tissue formation for tissue engineering and regenerative medicine applications. In this study, we looked toward embryonic tendon development as a model system to guide our soft tissue engineering approach. To direct cellular self-assembly, we utilized laser micromachined, differentially adherent growth channels lined with fibronectin. The micromachined growth channels directed human dermal fibroblast cells to form single cellular fibers, without the need for a provisional three-dimensional extracellular matrix or scaffold to establish a fiber structure. Therefore, the resulting tissue structure and mechanical characteristics were determined solely by the cells. Due to the self-assembly nature of this approach, the growing fibers exhibit some key aspects of embryonic tendon development, such as high cellularity, the rapid formation (within 24 h) of a highly organized and aligned cellular structure, and the expression of cadherin-11 (indicating direct cell-to-cell adhesions). To provide a dynamic mechanical environment, we have also developed and characterized a method to apply precise cyclic tensile strain to the cellular fibers as they develop. After an initial period of cellular fiber formation (24 h postseeding), cyclic strain was applied for 48 h, in 8-h intervals, with tensile strain increasing from 0.7% to 1.0%, and at a frequency of 0.5 Hz. Dynamic loading dramatically increased cellular fiber mechanical properties with a nearly twofold increase in both the linear region stiffness and maximum load at failure, thereby demonstrating a mechanism for enhancing cellular fiber formation and mechanical properties. Tissue engineering strategies, designed to capture key aspects of embryonic development, may provide unique insight into accelerated maturation of engineered replacement tissue, and offer significant advances for regenerative medicine applications in tendon, ligament, and other fibrous soft tissues.

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.

Natural cellulose fiber as substrate for supercapacitor.

PubMed

Gui, Zhe; Zhu, Hongli; Gillette, Eleanor; Han, Xiaogang; Rubloff, Gary W; Hu, Liangbing; Lee, Sang Bok

2013-07-23

Cellulose fibers with porous structure and electrolyte absorption properties are considered to be a good potential substrate for the deposition of energy material for energy storage devices. Unlike traditional substrates, such as gold or stainless steel, paper prepared from cellulose fibers in this study not only functions as a substrate with large surface area but also acts as an interior electrolyte reservoir, where electrolyte can be absorbed much in the cellulose fibers and is ready to diffuse into an energy storage material. We demonstrated the value of this internal electrolyte reservoir by comparing a series of hierarchical hybrid supercapacitor electrodes based on homemade cellulose paper or polyester textile integrated with carbon nanotubes (CNTs) by simple solution dip and electrodeposited with MnO2. Atomic layer deposition of Al2O3 onto the fiber surface was used to limit electrolyte absorption into the fibers for comparison. Configurations designed with different numbers of ion diffusion pathways were compared to show that cellulose fibers in paper can act as a good interior electrolyte reservoir and provide an effective pathway for ion transport facilitation. Further optimization using an additional CNT coating resulted in an electrode of paper/CNTs/MnO2/CNTs, which has dual ion diffusion and electron transfer pathways and demonstrated superior supercapacitive performance. This paper highlights the merits of the mesoporous cellulose fibers as substrates for supercapacitor electrodes, in which the water-swelling effect of the cellulose fibers can absorb electrolyte, and the mesoporous internal structure of the fibers can provide channels for ions to diffuse to the electrochemical energy storage materials.

An applied investigation of kenaf-based fiber/polymer composites as potential lightweight materials for automotive components

NASA Astrophysics Data System (ADS)

Du, Yicheng

Natural fibers have the potential to replace glass fibers in fiber-reinforced composite applications. However, the natural fibers' intrinsic properties cause these issues: (1) the mechanical property variation; (2) moisture uptake by natural fibers and their composites; (3) lack of sound, cost-effective, environment-friendly fiber-matrix compounding processes; (4) incompatibility between natural fibers and polymer matrices; and (5) low heat-resistance of natural fibers and their composites. This dissertation systematically studied the use of kenaf bast fiber bundles, obtained via a mechanical retting method, as a light-weight reinforcement material for fiber-reinforced thermoset polymer composites for automotive applications. Kenaf bast fiber bundle tensile properties were tested, and the effects of locations in the kenaf plant, loading rates, retting methods, and high temperature treatments and their durations on kenaf bast fiber bundle tensile properties were evaluated. A process has been developed for fabricating high fiber loading kenaf bast fiber bundle-reinforced unsaturated polyester composites. The generated composites possessed high elastic moduli and their tensile strengths were close to specification requirements for glass fiber-reinforced sheet molding compounds. Effects of fiber loadings and lengths on resultant composite's tensile properties were evaluated. Fiber loadings were very important for composite tensile modulus. Both fiber loadings and fiber lengths were important for composite tensile strengths. The distributions of composite tensile, flexural and impact strengths were analyzed. The 2-parameter Weibull model was found to be the most appropriate for describing the composite strength distributions and provided the most conservative design values. Kenaf-reinforced unsaturated polyester composites were also proved to be more cost-effective than glass fiber-reinforced SMCs at high fiber loadings. Kenaf bast fiber bundle-reinforced composite's water absorption properties were tested. Surface-coating and edge-sealing significantly reduced composite water resistance properties. Encapsulation was a practical method to improve composite water resistance properties. The molding pressure and styrene concentrations on composite and matrix properties were evaluated. Laser and plasma treatment improved fiber-to-matrix adhesion.

Strength of small-diameter round and tapered bending members

Treesearch

Ron Wolfe; Joe Murphy

2005-01-01

An early focus on structural use of processed rather than round timber resulted in an underestimation of the structural advantages of retaining the natural form of small-diameter round timber. In the round and tapered form, timbers are not susceptible to the strength-reducing effects of diving grain and exposed juvenile wood. Fiber continuity around knots on the...

Experimental strain modal analysis for beam-like structure by using distributed fiber optics and its damage detection

NASA Astrophysics Data System (ADS)

Cheng, Liangliang; Busca, Giorgio; Cigada, Alfredo

2017-07-01

Modal analysis is commonly considered as an effective tool to obtain the intrinsic characteristics of structures including natural frequencies, modal damping ratios, and mode shapes, which are significant indicators for monitoring the health status of engineering structures. The complex mode indicator function (CMIF) can be regarded as an effective numerical tool to perform modal analysis. In this paper, experimental strain modal analysis based on the CMIF has been introduced. Moreover, a distributed fiber-optic sensor, as a dense measuring device, has been applied to acquire strain data along a beam surface. Thanks to the dense spatial resolution of the distributed fiber optics, more detailed mode shapes could be obtained. In order to test the effectiveness of the method, a mass lump—considered as a linear damage component—has been attached to the surface of the beam, and damage detection based on strain mode shape has been carried out. The results manifest that strain modal parameters can be estimated effectively by utilizing the CMIF based on the corresponding simulations and experiments. Furthermore, damage detection based on strain mode shapes benefits from the accuracy of strain mode shape recognition and the excellent performance of the distributed fiber optics.

Effect of kenaf fiber in reinforced concrete slab

NASA Astrophysics Data System (ADS)

Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.

2018-04-01

The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.

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.

The structure-mechanical relationship of palm vascular tissue.

PubMed

Wang, Ningling; Liu, Wangyu; Huang, Jiale; Ma, Ke

2014-08-01

The structure-mechanical relationship of palm sheath is studied with numerical and experimental methods. The cellular structure of the vascular tissue is rebuilt with an image-based reconstruction method and used to create finite element models. The validity of the models is firstly verified with the results from the tensile tests. Then, the cell walls inside each of the specific regions (fiber cap, vessel, xylem, etc.) are randomly removed to obtain virtually imperfect structures. By comparing the magnitudes of performance degradation in the different imperfect structures, the influences of each region on the overall mechanical performances of the vascular tissue are discussed. The longitudinal stiffness and yield strength are sensitive to the defects in the vessel regions. While in the transverse directions (including the radial and tangential directions), the parenchymatous tissue determines the mechanical properties of the vascular tissue. Moreover, the hydraulic, dynamic response and energy absorption behavior of the vascular tissue are numerically explored. The flexibility of natural palm tissue enhances its impact resistance. Under the quasi-static compression, the cell walls connecting the fiber cap and the vessel dissipate more energy. The dominant role of the fiber cap in the plastic energy dissipation under high-speed impact is observed. And the radially-arranged fiber cap also allows the palm tissue to improve its tangential mechanical performances under hydraulic pressure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Natural stiffening increases flaw tolerance of biological fibers

NASA Astrophysics Data System (ADS)

Giesa, Tristan; Pugno, Nicola M.; Buehler, Markus J.

2012-10-01

Many fibers in biomaterials such as tendon, elastin, or silk feature a nonlinear stiffening behavior of the stress-strain relationship, where the rigidity of the material increases severely as the material is being stretched. Here we show that such nonlinear stiffening is beneficial for a fiber's ability to withstand cracks, leading to a flaw tolerant state in which stress concentrations around cracks are diminished. Our findings, established by molecular mechanics and the derivation of a theoretical scaling law, explain experimentally observed fiber sizes in a range of biomaterials and point to the importance of nonlinear stiffening to enhance their fracture properties. Our study suggests that nonlinear stiffening provides a mechanism by which nanoscale mechanical properties can be scaled up, providing a means towards bioinspired fibrous material and structural design.

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions.

PubMed

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-04-04

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions

PubMed Central

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-01-01

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line. PMID:29617285

Aerogel Hybrid Composite Materials: Designs and Testing for Multifunctional Applications

NASA Technical Reports Server (NTRS)

Williams, Martha K.; Fesmire, James E.

2016-01-01

This webinar will introduce the broad spectrum of aerogel composites and their diverse performance properties such as reduced heat transfer to energy storage, and expands specifically on the aerogel/fiber laminate systems and testing methodologies. The multi-functional laminate composite system, AeroFiber, and its construction is designed by varying the type of fiber (e.g. polyester, carbon, Kevlar®, Spectra® or Innegral(TradeMark) and combinations thereof), the aerogel panel type and thickness, and overall layup configuration. The combination and design of materials may be customized and tailored to achieve a range of desired properties in the resulting laminate system. Multi-functional properties include structural strength, impact resistance, reduction in heat transfer, increased fire resistance, mechanical energy absorption, and acoustic energy dampening. Applications include aerospace, aircraft, automotive, boating, building and construction, lightweight portable structures, liquefied natural gas, cryogenics, transportation and energy, sporting equipment, and military protective gear industries.

Enzyme-mediated self-assembly of highly ordered structures from disordered proteins

NASA Astrophysics Data System (ADS)

Athamneh, Ahmad I.; Barone, Justin R.

2009-10-01

Wheat gluten is an amorphous storage protein. Trypsin hydrolysis of wheat gluten produced glutamine-rich peptides. Some peptides were able to self-assemble into fibrous structures extrinsic to native wheat gluten. The final material was an in situ formed peptide composite of highly ordered nanometer-sized fibrils and micron-sized fibers embedded in an unassembled peptide matrix. Fourier transform infrared spectroscopic and x-ray diffraction data suggested that the new structures resembled that of cross- β fibrils found in some insect silk and implicated in prion diseases. The largest self-assembled fibers were about 10 µm in diameter with right-handed helicity and appeared to be bundles of smaller nanometer-sized fibrils. Results demonstrated the potential for utilizing natural mechanisms of protein self-assembly to design advanced materials that can provide a wide range of structural and chemical functionality.

Production of fumaric acid by immobilized Rhizopus arrhizus RH 7-13-9# on loofah fiber in a stirred-tank reactor.

PubMed

Liu, Huan; Zhao, Shijie; Jin, Yuhan; Yue, Xuemin; Deng, Li; Wang, Fang; Tan, Tianwei

2017-11-01

Fumaric acid is an important building-block chemical. The production of fumaric acid by fermentation is possible. Loofah fiber is a natural, biodegradable, renewable polymer material with highly sophisticated and pore structure. This work investigated a new immobilization method using loofah fiber as carrier to produce fumaric acid in a stirred-tank reactor. Compared with other carriers, loofah fiber was proven to be efficiently and successfully used in the reactor. After the optimization process, 20g addition of loofah fiber and 400rpm agitation speed were chosen as the most suitable process conditions. 30.3g/L fumaric acid in the broth as well as 19.16g fumaric acid in the precipitation of solid was achieved, while the yield from glucose reached 0.211g/g. Three batches of fermentation using the same loofah fiber carrier were conducted successfully, which meant it provided a new method to produce fumaric acid in a stirred-tank reactor. Copyright © 2017. Published by Elsevier Ltd.

Fiber-optical sensor with intensity compensation model in college teaching of physics experiment

NASA Astrophysics Data System (ADS)

Su, Liping; Zhang, Yang; Li, Kun; Zhang, Yu

2017-08-01

Optical fiber sensor technology is one of the main contents of modern information technology, which has a very important position in modern science and technology. Fiber optic sensor experiment can improve students' enthusiasm and broaden their horizons in college physics experiment. In this paper the main structure and working principle of fiberoptical sensor with intensity compensation model are introduced. And thus fiber-optical sensor with intensity compensation model is applied to measure micro displacement of Young's modulus measurement experiment and metal linear expansion coefficient measurement experiment in the college physics experiment. Results indicate that the measurement accuracy of micro displacement is higher than that of the traditional methods using fiber-optical sensor with intensity compensation model. Meanwhile this measurement method makes the students understand on the optical fiber, sensor and nature of micro displacement measurement method and makes each experiment strengthen relationship and compatibility, which provides a new idea for the reform of experimental teaching.

Kenaf-glass fiber reinforced unsaturated polyester hybrid composites: Tensile properties

NASA Astrophysics Data System (ADS)

Zhafer, S. F.; Rozyanty, A. R.; Shahnaz, S. B. S.; Musa, L.; Zuliahani, A.

2016-07-01

The use of natural fibers in composite is rising in recent years due their lightweight, non-abrasive, combustible, non-toxic, low cost and biodegradable properties. However, in comparison with synthetic fibers, the mechanical properties of natural fibers are lower. Therefore, the inclusion of synthetic fibers could improve the mechanical performance of natural fiber based composites. In this study, kenaf bast fiber and glass fiber at different weight percentage loading were used as reinforcement to produce hybrid composites. Unsaturated polyester (UP) resin was used as matrix and hand lay-up process was performed to apply the UP resin on the hybrid kenaf bast/glass fiber composite. Effect of different fiber loading on tensile strength, tensile modulus and elongation at break of the hybrid composite was studied. It has been found that the highest value of tensile strength and modulus was achieved at 10 wt.% kenaf/10 wt.% glass fiber loading. It was concluded that addition of glass fiber has improved the tensile properties of kenaf bast fiber based UP composites.

Effect of BN coating on the strength of a mullite type fiber

NASA Astrophysics Data System (ADS)

Chawla, K. K.; Xu, Z. R.; Ha, J.-S.; Schmücker, M.; Schneider, H.

1997-09-01

Nextel 480 is a polycrystalline essentially mullite fiber (70 wt.-% Al2O3+28 wt.-% SiO2+2 wt.-% B2O3). Different thicknesses of BN were applied as coatings on this fiber. Optical, scanning electron, and transmission electron microscopy were used to characterize the microstructure of the coatings and fibers. The effects of coating and high temperature exposure on the fiber strength were investigated using two-parameter Weibull distribution. TEM examination showed that the BN coating has a turbostratic structure, with the basal planes lying predominantly parallel to the fiber surface. Such an orientation of coating is desirable for easy crack deflection and subsequent fiber pullout in a composite. The BN coated Nextel 480 fiber showed that Weibull mean strength increased first and then decreased with increasing coating thickness. This was due to the surface flaw healing effect of the coating (up to 0.3 μm) while in the case of thick BN coating (1 μm), the soft nature of the coating material had a more dominant effect and resulted in a decrease of the fiber strength. High temperature exposure of Nextel 480 resulted in grain growth, which led to a strength loss.

Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

NASA Astrophysics Data System (ADS)

Willcox, Patricia Jeanene

This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine cryogenic technology for sample preparation and direct observation by transmission electron microscopy with electron diffraction, atomic force microscopy, optical rheometry, X-ray scattering and optical microscopy. In order to explore the full range of structure formation in natural silk spinning, studies are conducted in vivo and in vitro. In vivo structural investigations are accomplished through the cryogenic quenching and subsequent microtoming of live silk-spinning animals, Nephila clavipes (spider) and Bombyx mori (silkworm). Observations made using transmission electron microscopy, electron diffraction and atomic force microscopy indicate a cholesteric liquid crystalline mesophase of aqueous silk fibroin in both species. The mechanism of structure formation in solution is studied in vitro using optical rheometry on aqueous solutions made from regenerated Bombyx mori cocoon silk. Concentrated solutions exhibit birefringence under flow, with a wormlike conformation of the silk molecules in concentrated salt solution. Changes in salt concentration and pH of the aqueous silk solutions result in differing degrees of alignment and aggregation. These results suggest that structural control in the natural silk spinning process is accomplished by chemical manipulation of the electrostatic interactions and hydrogen bonding between chains. Application of cryogenic methods in transmission electron microscopy also provides a unique look at hydration-dependent structures in gels of poly(vinyl alcohol) produced by freeze-thaw processing. Morphologies ranging from circular pores to fibrillar networks are observed in gels formed from aqueous PVOH solutions subjected to cycles of freezing and thawing. These morphologies can be directly associated with the progressive nature of the mechanism of gelation as it proceeds from liquid-liquid phase separation to crystallization with increased cycling. A comparison of the structures produced by cycling and by aging suggests that there is a similarity in structural changes, but a superposition of the effects of cycling and aging is not possible.

Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

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

Kan, Ze; Chen, Peng; Liu, Zhengying

Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, andmore » the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects.« less

Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

NASA Astrophysics Data System (ADS)

Kan, Ze; Chen, Peng; Liu, Zhengying; Feng, Jianmin; Yang, Mingbo

2015-05-01

Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, and the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects.

Advances in joining newer structural materials; Proceedings of the International Conference, Montreal, Canada, July 23-25, 1990

NASA Astrophysics Data System (ADS)

The present conference on advances in joining novel structural materials encompasses such material types as ceramics, plastics and composites, and new metallic materials. Specific issues addressed include the use of conductor electric explosion to join ceramics, the effects of brazing temperature on joint properties of SiC-fiber-reinforced Al-alloy-matrix composites, the in situ structure control of composite materials, and the weldability of polymeric materials that are heterogeneous as to chemical nature from the standpoint of morphology. Also addressed are the joining of the Al-Li alloy 8090, diffusion bonding of a creep-resistant Fe-ODS alloy, the adhesive bonding of zinc-coated steel sheets, welds in thermoplastic composite materials, and hot-melt joints for carbon-fiber-reinforced composites.

Bio-inspired multistructured conical copper wires for highly efficient liquid manipulation.

PubMed

Wang, Qianbin; Meng, Qingan; Chen, Ming; Liu, Huan; Jiang, Lei

2014-09-23

Animal hairs are typical structured conical fibers ubiquitous in natural system that enable the manipulation of low viscosity liquid in a well-controlled manner, which serves as the fundamental structure in Chinese brush for ink delivery in a controllable manner. Here, drawing inspiration from these structure, we developed a dynamic electrochemical method that enables fabricating the anisotropic multiscale structured conical copper wire (SCCW) with controllable conicity and surface morphology. The as-prepared SCCW exhibits a unique ability for manipulating liquid with significantly high efficiency, and over 428 times greater than its own volume of liquid could be therefore operated. We propose that the boundary condition of the dynamic liquid balance behavior on conical fibers, namely, steady holding of liquid droplet at the tip region of the SCCW, makes it an excellent fibrous medium to manipulate liquid. Moreover, we demonstrate that the titling angle of the SCCW can also affect its efficiency of liquid manipulation by virtue of its mechanical rigidity, which is hardly realized by flexible natural hairs. We envision that the bio-inspired SCCW could give inspiration in designing materials and devices to manipulate liquid in a more controllable way and with high efficiency.

Nanocontainers in and onto Nanofibers.

PubMed

Jiang, Shuai; Lv, Li-Ping; Landfester, Katharina; Crespy, Daniel

2016-05-17

Hierarchical structure is a key feature explaining the superior properties of many materials in nature. Fibers usually serve in textiles, for structural reinforcement, or as support for other materials, whereas spherical micro- and nanoobjects can be either highly functional or also used as fillers to reinforce structure materials. Combining nanocontainers with fibers in one single object has been used to increase the functionality of fibers, for example, antibacterial and thermoregulation, when the advantageous properties given by the encapsulated materials inside the containers are transferred to the fibers. Herein we focus our discussion on how the hierarchical structure composed of nanocontainers in nanofibers yields materials displaying advantages of both types of materials and sometimes synergetical effects. Such materials can be produced by first carefully designing nanocontainers with defined morphology and chemistry and subsequently electrospinning them to fabricate nanofibers. This method, called colloid-electrospinning, allows for marrying the properties of nanocontainers and nanofibers. The obtained fibers could be successfully applied in different fields such as catalysis, optics, energy conversion and production, and biomedicine. The miniemulsion process is a convenient approach for the encapsulation of hydrophobic or hydrophilic payloads in nanocontainers. These nanocontainers can be embedded in fibers by the colloid-electrospinning technique. The combination of nanocontainers with nanofibers by colloid-electrospinning has several advantages. (1) The fiber matrix serves as support for the embedded nanocontainers. For example, through combining catalysts nanoparticles with fiber networks, the catalysts can be easily separated from the reaction media and handled visually. This combination is beneficial for the reuse of the catalyst and the purification of products. (2) Electrospun nanofibers containing nanocontainers offer the active agents inside the nanocontainers a double protection by both the fiber matrix and the nanocontainers. Since the polymer of the fibers and the polymer of the nanocontainers have usually opposite polarities, the encapsulated substance, for example, catalysts, dyes, or drugs, can be protected against a large variety of environmental influences. (3) Electrospun nanofibers exhibit unique advantages for tissue engineering and drug delivery that are a structural similarity to the extracellular matrix of biological tissues, large specific surface area, high and interconnected porosity which enhances cell adhesion, proliferation, drug loading, and mass transfer properties, as well as the flexibility in selecting the raw materials. Moreover, the nanocontainer-in-nanofiber structure allows multidrug loading and programmable release of each drug, which are very important to achieve synergistic effects in tissue engineering and disease therapy. The advantages offered by these materials encourage us to further understand the relationship between colloidal properties and fibers, to predict the morphology and properties of the fibers obtained by colloid-electrospinning, and to explore new possible combination of properties offered by nanoparticles and nanofibers.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

PubMed

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-12-16

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

PubMed Central

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-01-01

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

Regenerated silk materials for functionalized silk orthopedic devices by mimicking natural processing

PubMed Central

Li, Chunmei; Hotz, Blake; Ling, Shengjie; Guo, Jin; Haas, Dylan S.; Marelli, Benedetto; Omenetto, Fiorenzo; Lin, Samuel J.; Kaplan, David L.

2016-01-01

Silk fibers spun by silkworms and spiders exhibit exceptional mechanical properties with a unique combination of strength, extensibility and toughness. In contrast, the mechanical properties of regenerated silk materials can be tuned through control of the fabrication process. Here we introduce a biomimetic, all-aqueous process, to obtain bulk regenerated silk-based materials for the fabrication of functionalized orthopedic devices. The silk materials generated in the process replicate the nano-scale structure of natural silk fibers and possess excellent mechanical properties. The biomimetic materials demonstrated excellent machinability, providing a path towards the fabrication of a new family of resorbable orthopedic devices where organic solvents are avoided, thus allowing functionalization with bioactive molecules to promote bone remodeling and integration. PMID:27697669

Evaluating the effect of some mechanical properties for chemically treated various natural fibers reinforced polyester composite

NASA Astrophysics Data System (ADS)

Salih, Wafaa Mahdi; Abdulkader, Niveen Jamal; Salih, Sana Mahdi

2018-05-01

This research were studied the effect of some mechanical properties for composite materials reinforced fiber and prepared from material (polyester with various natural fibers) then studied the effect of chemical treatment on the same fiber immerse in 10% NaOH solution for half an hour and then compared, the results of the same test of composite materials without and with chemical treatment and the results proved that there is a clear effect when treat the fiber compared to non-chemical treatment of the fibers also noted that hemp fibers loaded the stress higher than other fibers for both cases to distinguish them that the hemp fiber has continuous fibers either the other fibers are characterized by the type of cross linking or chopped types in tensile test, and the results of the same test of composite materials without and with chemical treatment and the results proved that the hardness of the fiber composite while the treated fiber composite samples better than the untreated fiber, and from the figures the palm leaf has the highest value than lufa fiber, hemp fiber and the smallest value is in sisal fiber because of the nature of formation fibers materials.

The applications of carbon nanomaterials in fiber-shaped energy storage devices

NASA Astrophysics Data System (ADS)

Wu, Jingxia; Hong, Yang; Wang, Bingjie

2018-01-01

As a promising candidate for future demand, fiber-shaped electrochemical energy storage devices, such as supercapacitors and lithium-ion batteries have obtained considerable attention from academy to industry. Carbon nanomaterials, such as carbon nanotube and graphene, have been widely investigated as electrode materials due to their merits of light weight, flexibility and high capacitance. In this review, recent progress of carbon nanomaterials in flexible fiber-shaped energy storage devices has been summarized in accordance with the development of fibrous electrodes, including the diversified electrode preparation, functional and intelligent device structure, and large-scale production of fibrous electrodes or devices. Project supported by the National Natural Science Foundation of China (Nos. 21634003, 21604012).

Scale-up of nature's tissue weaving algorithms to engineer advanced functional materials.

PubMed

Ng, Joanna L; Knothe, Lillian E; Whan, Renee M; Knothe, Ulf; Tate, Melissa L Knothe

2017-01-11

We are literally the stuff from which our tissue fabrics and their fibers are woven and spun. The arrangement of collagen, elastin and other structural proteins in space and time embodies our tissues and organs with amazing resilience and multifunctional smart properties. For example, the periosteum, a soft tissue sleeve that envelops all nonarticular bony surfaces of the body, comprises an inherently "smart" material that gives hard bones added strength under high impact loads. Yet a paucity of scalable bottom-up approaches stymies the harnessing of smart tissues' biological, mechanical and organizational detail to create advanced functional materials. Here, a novel approach is established to scale up the multidimensional fiber patterns of natural soft tissue weaves for rapid prototyping of advanced functional materials. First second harmonic generation and two-photon excitation microscopy is used to map the microscopic three-dimensional (3D) alignment, composition and distribution of the collagen and elastin fibers of periosteum, the soft tissue sheath bounding all nonarticular bone surfaces in our bodies. Then, using engineering rendering software to scale up this natural tissue fabric, as well as multidimensional weaving algorithms, macroscopic tissue prototypes are created using a computer-controlled jacquard loom. The capacity to prototype scaled up architectures of natural fabrics provides a new avenue to create advanced functional materials.

Natural Fiber Cut Machine Semi-Automatic Linear Motion System for Empty Fiber Bunches: Re-designing for Local Use

NASA Astrophysics Data System (ADS)

Asfarizal; Kasim, Anwar; Gunawarman; Santosa

2017-12-01

Empty Palm bunches of fiber is local ingredient in Indonesia that easy to obtain. Empty Palm bunches of fiber can be obtained from the palm oil industry such as in West Pasaman. The character of the empty Palm bunches of fiber that is strong and pliable has high-potential for particle board. To transform the large quantities of fiber become particles in size 0-10 mm requires a specially designed cut machine. Therefore, the machine is designed in two-stage system that is mechanical system, structure and cutting knife. Components that have been made, assembled and then tested to reveal the ability of the machine to cut. The results showed that the straight back and forth motion cut machine is able to cut out the empty oil palm bunches of fiber with a length 0-1 cm, 2 cm, 8 cm and the surface of the cut is not stringy. The cutting capacity is at a length of 2 cm in the result 24.4 (kg/h) and 8 cm obtained results of up to 84 (kg/h)

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.

Fiber-reinforced dielectric elastomer laminates with integrated function of actuating and sensing

NASA Astrophysics Data System (ADS)

Li, Tiefeng; Xie, Yuhan; Li, Chi; Yang, Xuxu; Jin, Yongbin; Liu, Junjie; Huang, Xiaoqiang

2015-04-01

The natural limbs of animals and insects integrate muscles, skins and neurons, providing both the actuating and sensing functions simultaneously. Inspired by the natural structure, we present a novel structure with integrated function of actuating and sensing with dielectric elastomer (DE) laminates. The structure can deform when subjected to high voltage loading and generate corresponding output signal in return. We investigate the basic physical phenomenon of dielectric elastomer experimentally. It is noted that when applying high voltage, the actuating dielectric elastomer membrane deforms and the sensing dielectric elastomer membrane changes the capacitance in return. Based on the concept, finite element method (FEM) simulation has been conducted to further investigate the electromechanical behavior of the structure.

The narwhal (Monodon monoceros) cementum-dentin junction: a functionally graded biointerphase.

PubMed

Grandfield, Kathryn; Chattah, Netta Lev-Tov; Djomehri, Sabra; Eidelmann, Naomi; Eichmiller, Frederick C; Webb, Samuel; Schuck, P James; Nweeia, Martin; Ho, Sunita P

2014-08-01

In nature, an interface between dissimilar tissues is often bridged by a graded zone, and provides functional properties at a whole organ level. A perfect example is a "biological interphase" between stratified cementum and dentin of a narwhal tooth. This study highlights the graded structural, mechanical, and chemical natural characteristics of a biological interphase known as the cementum-dentin junction layer and their effect in resisting mechanical loads. From a structural perspective, light and electron microscopy techniques illustrated the layer as a wide 1000-2000 μm graded zone consisting of higher density continuous collagen fiber bundles from the surface of cementum to dentin, that parallels hygroscopic 50-100 μm wide collagenous region in human teeth. The role of collagen fibers was evident under compression testing during which the layer deformed more compared to cementum and dentin. This behavior is reflected through site-specific nanoindentation indicating a lower elastic modulus of 2.2 ± 0.5 GPa for collagen fiber bundle compared to 3 ± 0.4 GPa for mineralized regions in the layer. Similarly, microindentation technique illustrated lower hardness values of 0.36 ± 0.05 GPa, 0.33 ± 0.03 GPa, and 0.3 ± 0.07 GPa for cementum, dentin, and cementum-dentin layer, respectively. Biochemical analyses including Raman spectroscopy and synchrotron-source microprobe X-ray fluorescence demonstrated a graded composition across the interface, including a decrease in mineral-to-matrix and phosphate-to-carbonate ratios, as well as the presence of tidemark-like bands with Zn. Understanding the structure-function relationships of wider tissue interfaces can provide insights into natural tissue and organ function. © IMechE 2014.

Mixture of natural fiber with gypsum to improve the fire resistance rating of a fire door: The effect of kapok fiber

NASA Astrophysics Data System (ADS)

Azieyanti, N. A.; Hakim, Alif; Hasini, Hasril

2017-10-01

A composite mixture of gypsum and natural fibers has been considered in this study to enhance the fire resistance rating of a fire door. Previously the materials used to make a fire door are gypsum and fiber wool where it acts as a protective coating. Normally this fire door must be compact and able to close on its own. Natural fibers have the ability to replace glass fiber cotton because of its features that are available in fiber glass wool. When using fiberglass, it can cause health problem once it is swallowed and inhaled, and may remain in the lungs indefinitely. It also can contribute to lungs cancer. Kapok fiber has been used in this experiment as natural fibers. The objective of the experiment is to analyze the fire resistant rating of the composite mixture of gypsum with kapok fiber. The scopes of the experiment consist of a preparation of composite mixture samples of gypsum with kapok fiber with different composition and thickness, and the fabrication of a fire resistant testing furnace. A testing of samples which were conducted in accordance with the standard MS 1073: PART 2:1996.

Nanostructured biomaterials from electrospun demineralized bone matrix: a survey of processing and crosslinking strategies.

PubMed

Leszczak, Victoria; Place, Laura W; Franz, Natalee; Popat, Ketul C; Kipper, Matt J

2014-06-25

In the design of scaffolds for tissue engineering biochemical function and nanoscale features are of particular interest. Natural polymers provide a wealth of biochemical function, but do not have the processability of synthetic polymers, limiting their ability to mimic the hierarchy of structures in the natural extracellular matrix. Thus, they are often combined with synthetic carrier polymers to enable processing. Demineralized bone matrix (DBM), a natural polymer, is allograft bone with inorganic material removed. DBM contains the protein components of bone, which includes adhesion ligands and osteoinductive signals, such as important growth factors. Herein we describe a novel method for tuning the nanostructure of DBM through electrospinning without the use of a carrier polymer. This work surveys solvents and solvent blends for electrospinning DBM. Blends of hexafluoroisopropanol and trifluoroacetic acid are studied in detail. The effects of DBM concentration and dissolution time on solution viscosity are also reported and correlated to observed differences in electrospun fiber morphology. We also present a survey of techniques to stabilize the resultant fibers with respect to aqueous environments. Glutaraldehyde vapor treatment is successful at maintaining both macroscopic and microscopic structure of the electrospun DBM fibers. Finally, we report results from tensile testing of stabilized DBM nanofiber mats, and preliminary evaluation of their cytocompatibility. The DBM nanofiber mats exhibit good cytocompatibility toward human dermal fibroblasts (HDF) in a 4-day culture; neither the electrospun solvents nor the cross-linking results in any measurable residual cytotoxicity toward HDF.

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

NASA Astrophysics Data System (ADS)

McDaniel, Preston B.

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

Spatiotemporally Controlled Microchannels of Periodontal Mimic Scaffolds

PubMed Central

Park, C.H.; Kim, K.H.; Rios, H.F.; Lee, Y.M.; Giannobile, W.V.; Seol, Y.J.

2014-01-01

Physiologic bioengineering of the oral, dental, and craniofacial complex requires optimized geometric organizations of fibrous connective tissues. A computer-designed, fiber-guiding scaffold has been developed to promote tooth-supporting periodontal tissue regeneration and functional restoration despite limited printing resolution for the manufacture of submicron-scaled features. Here, we demonstrate the use of directional freeze-casting techniques to control pore directional angulations and create mimicked topographies to alveolar crest, horizontal, oblique, and apical fibers of natural periodontal ligaments. For the differing anatomic positions, the gelatin displayed varying patterns of ice growth, determined via internal pore architectures. Regardless of the freezing coordinates, the longitudinal pore arrangements resulted in submicron-scaled diameters (~50 µm), along with corresponding high biomaterial porosity (~90%). Furthermore, the horizontal + coronal ((x→−y→) freezing orientation facilitated the creation of similar structures to major fibers in the periodontal ligament interface. This periodontal tissue-mimicking microenvironment is a potential tissue platform for the generation of naturally oriented ligamentous tissues consistent with periodontal ligament neogenesis. PMID:25216511

The effect of cellulases on the biodegradation and morphology of naturally colored cotton fibers

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

Evans, B.R.; Lee, I.; Woodward, J.

We have investigated the effect of cellulases on the biodegradation and structure of natural colored cotton (Foxfibre{reg_sign}). Compared to the white cotton and palo verde (sage green) varieties, buffalo (mocha brown) and coyote (reddish brown) varieties were quite resistant to hydrolysis by Trichoderma reesei celluclast and purified cellobiohydrolase I (CBH I) under the conditions of the assay, but binding of CBH I to buffalo cotton was unaffected. Sodium hydroxide extracts of all the colored cotton varieties were found to be strong inhibitors of cellulase activity and the buffalo cotton was labile in that the inhibitory effect decreased over time inmore » the presence of cellulase; incubation of {beta}-glucosidase with the extract also decreased the inhibition. The chemical composition of the inhibitor is currently under investigation. Atomic force microscopy of the colored cotton fibers with bound cellulase components should prove useful in the context of elucidating the effect of binding on the morphology of cellulose fibers.« less

Combination of natural fiber Boehmeria nivea (ramie) with matrix epoxide for bullet proof vest body armor

NASA Astrophysics Data System (ADS)

Anggoro, Didi Dwi; Kristiana, Nunung

2015-12-01

Ballistic protection equipment, such as a bulletproof vest, is a soldier's most important means of preserving life and survivability in extreme combat conditions. The bulletproof vests are designed to protect the user's chest from injury without disturbing the ability to perform his duties. Aromatic polyamide or aramid fibers known under the trade name Kevlar, Trawon and so is synthetic fiber materials commonly used in the manufacture of bulletproof vests. This synthetic fibers have high tensile strength and ductility. Kevlar is expensive and imported material. In this study, will introduce local natural raw materials, ramie fiber (Boehmeria nivea) which is cheaper and environmentally friendly. It has enough tenacity and tensile strength as a bulletproof vest. This experiment uses two panels, there are Panel A as front surface of Panel B. Panel A is a combination of ramie and epoxide matrix, while panel B is only ramie. From several variations of experimental combinations between Panel A and Panel B, optimal combination obtained with 16 layers of panel A and 31-34 layers of panel B which is able to protect againts cal. 7.65 mm × 17 mm (.32 ACP) bullet fired through pistol .32 Pindad from a distance of 20 meters. Panel with a size of 20 cm × 20 cm has a total thickness between 12,922 to13,745 mm and a total weight between 506,26 to 520,926gram. Scanning electron microscopy (SEM) observations indicated that the porosity and surface area of the ramie fiber is smooth, fiber surfaces showed topography with micropores. SEM also showed well-arranged structure of fibers bonding. Energy Dispersive X-ray (EDX) analysis indicated 100 % carbon contents in ramie fiber. Test result indicates that panel from composite ramie-epoxide can reach the level 1of International Standard of NIJ - 010104. Compared to panel from polyester fiber, the panel from composite ramie-epoxide (0,50-0,52 kg) is lighter weight than panel polyester fiber (1,642 kg).

Natural-Synthetic Hybrid Polymers Developed via Electrospinning: The Effect of PET in Chitosan/Starch System

PubMed Central

Espíndola-González, Adolfo; Martínez-Hernández, Ana Laura; Fernández-Escobar, Francisco; Castaño, Victor Manuel; Brostow, Witold; Datashvili, Tea; Velasco-Santos, Carlos

2011-01-01

Chitosan is an amino polysaccharide found in nature, which is biodegradable, nontoxic and biocompatible. It has versatile features and can be used in a variety of applications including films, packaging, and also in medical surgery. Recently a possibility to diversify chitosan properties has emerged by combining it with synthetic materials to produce novel natural-synthetic hybrid polymers. We have studied structural and thermophysical properties of chitosan + starch + poly(ethylene terephthalate) (Ch + S + PET) fibers developed via electrospinning. Properties of these hybrids polymers are compared with extant chitosan containing hybrids synthesized by electrospinning. Molecular interactions and orientation in the fibers are analyzed by infrared and Raman spectroscopies respectively, morphology by scanning electron microscopy and thermophysical properties by thermogravimetric analysis and differential scanning calorimetry. Addition of PET to Ch + S systems results in improved thermal stability at elevated temperatures. PMID:21673930

Researches on the development of new composite materials complete / partially biodegradable using natural textile fibers of new vegetable origin and those recovered from textile waste

NASA Astrophysics Data System (ADS)

Todor, M. P.; Bulei, C.; Heput, T.; Kiss, I.

2018-01-01

The objective of the research is to develop new fully / partially biodegradable composite materials by using new natural fibers and those recovered from various wastes. Thus, the research aims to obtain some composites with matrix of various types of polymeric materials and the reinforcement phase of textile materials (of different natures, morphologies and composites) so that the resulting products to be (bio)degradable. The textile inserts used as raffle are ecological, non-toxic and biodegradable and they contain (divided or in combination) bast fibers (flax, hemp, jute) and other vegetable fibers (cotton, wool) as plain yarn or fabric, which can replace fibers of glass commonly used in polymeric composites. The main activities described in this article are carried out during the first phase of the research (phase I - initiation of research) and they are oriented towards the choice of types of textile inserts from which the composites will be obtained (the materials needed for the raffle), the choice of the types of polymers (the necessary materials for matrices) and choosing the variants of composites with different types and proportions of the constituent content (proposals and working variants) and choosing the right method for obtaining samples of composite materials (realization technology). The purpose of the research is to obtain composite materials with high structural, thermo-mechanical and / or tribological performances, according to ecological norms and international requirements in order to replace the existing classical materials, setting up current, innovative and high performance solutions, for applications in top areas such as automotive industry and not only.

Dynamic Analysis with Fibre Optic Sensors for Structural Health Monitoring

DTIC Science & Technology

2006-10-01

cracked thick aluminum plate repaired with a bonded composite patch using transmission-type extrinsic Fabry – Perot interferometric optical fiber...and optical filtering have been used to demodulate returned Bragg signals. Due to the passive nature of the interrogation unit, system bandwidth is

Transition Metal Ions Enable the Transition from Electrospun Prolamin Protein Fibers to Nitrogen-Doped Freestanding Carbon Films for Flexible Supercapacitors.

PubMed

Wang, Yixiang; Yang, Jingqi; Du, Rongbing; Chen, Lingyun

2017-07-19

Flexible carbon ultrafine fibers are highly desirable in energy storage and conversion devices. Our previous finding showed that electrospun hordein/zein fibers stabilized by Ca 2+ were successfully transferred into nitrogen-doped carbon ultrafine fibers for supercapacitors. However, their relatively brittle nature needed to be improved. Inspired by this stabilizing effect of Ca 2+ , in this work, four transition metal divalent cations were used to assist the formation of flexible hordein/zein-derived carbon ultrafine fibers. Without alteration of the electrospinnability, adequate amounts of zinc acetate and cobalt acetate supported the fibrous structure during pyrolysis. This resulted in flexible freestanding carbon films consisting of well-defined fibers with nitrogen-doped graphitic layers and hierarchical pores. These carbon films were easily cut into small square pieces and directly applied as working electrode in the three-electrode testing system without the need for polymer binders or conducting agents. Notably, the hz-Zn0.3-p electrode, synthesized with 0.3 mol/L Zn 2+ and post-acid treatment, exhibited a specific capacitance of 393 F/g (at 1 A/g), a large rate capability (72.3% remained at 20 A/g), and a capacitance retention of ∼98% after 2000 charging-discharging cycles at 10 A/g. These superior electrochemical properties were attributed to the synergistic effects of the well-developed graphitic layers induced by Zn 2+ , the nitrogen-decorated carbon structure, and the interconnected channels generated by HCl treatment. This research advances potential applications for prolamin proteins as nitrogen-containing raw materials in developing carbon structures for high-performance supercapacitors.

21 CFR 895.101 - Prosthetic hair fibers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... fibers are devices intended for implantation into the human scalp to simulate natural hair or conceal... modacrylic, polyacrylic, and polyester; and natural fibers, such as processed human hair. Excluded from the banned device are natural hair transplants, in which a person's hair and its surrounding tissue are...

21 CFR 895.101 - Prosthetic hair fibers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... fibers are devices intended for implantation into the human scalp to simulate natural hair or conceal... modacrylic, polyacrylic, and polyester; and natural fibers, such as processed human hair. Excluded from the banned device are natural hair transplants, in which a person's hair and its surrounding tissue are...

21 CFR 895.101 - Prosthetic hair fibers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... fibers are devices intended for implantation into the human scalp to simulate natural hair or conceal... modacrylic, polyacrylic, and polyester; and natural fibers, such as processed human hair. Excluded from the banned device are natural hair transplants, in which a person's hair and its surrounding tissue are...

21 CFR 895.101 - Prosthetic hair fibers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... fibers are devices intended for implantation into the human scalp to simulate natural hair or conceal... modacrylic, polyacrylic, and polyester; and natural fibers, such as processed human hair. Excluded from the banned device are natural hair transplants, in which a person's hair and its surrounding tissue are...

Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

NASA Technical Reports Server (NTRS)

Needles, H. L.

1985-01-01

The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

A biologically inspired artificial muscle based on fiber-reinforced and electropneumatic dielectric elastomers

NASA Astrophysics Data System (ADS)

Liu, Lei; Zhang, Chi; Luo, Meng; Chen, Xi; Li, Dichen; Chen, Hualing

2017-08-01

Dielectric elastomers (DEs) have great potential for use as artificial muscles because of the following characteristics: electrical activity, fast and large deformation under stimuli, and softness as natural muscles. Inspired by the traditional McKibben actuators, in this study, we developed a cylindrical soft fiber-reinforced and electropneumatic DE artificial muscle (DEAM) by mimicking the spindle shape of natural muscles. Based on continuum mechanics and variation principle, the inhomogeneous actuation of DEAMs was theoretically modeled and calculated. Prototypes of DEAMs were prepared to validate the design concept and theoretical model. The theoretical predictions are consistent with the experimental results; they successfully predicted the evolutions of the contours of DEAMs with voltage. A pneumatically supported high prestretch in the hoop direction was achieved by our DEAM prototype without buckling the soft fibers sandwiched by the DE films. Besides, a continuously tunable prestretch in the actuation direction was achieved by varying the supporting pressure. Using the theoretical model, the failure modes, maximum actuations, and critical voltages were analyzed; they were highly dependent on the structural parameters, i.e., the cylinder aspect ratio, prestretch level, and supporting pressure. The effects of structural parameters and supporting pressure on the actuation performance were also investigated to optimize the DEAMs.

New twist on artificial muscles.

PubMed

Haines, Carter S; Li, Na; Spinks, Geoffrey M; Aliev, Ali E; Di, Jiangtao; Baughman, Ray H

2016-10-18

Lightweight artificial muscle fibers that can match the large tensile stroke of natural muscles have been elusive. In particular, low stroke, limited cycle life, and inefficient energy conversion have combined with high cost and hysteretic performance to restrict practical use. In recent years, a new class of artificial muscles, based on highly twisted fibers, has emerged that can deliver more than 2,000 J/kg of specific work during muscle contraction, compared with just 40 J/kg for natural muscle. Thermally actuated muscles made from ordinary polymer fibers can deliver long-life, hysteresis-free tensile strokes of more than 30% and torsional actuation capable of spinning a paddle at speeds of more than 100,000 rpm. In this perspective, we explore the mechanisms and potential applications of present twisted fiber muscles and the future opportunities and challenges for developing twisted muscles having improved cycle rates, efficiencies, and functionality. We also demonstrate artificial muscle sewing threads and textiles and coiled structures that exhibit nearly unlimited actuation strokes. In addition to robotics and prosthetics, future applications include smart textiles that change breathability in response to temperature and moisture and window shutters that automatically open and close to conserve energy.

New twist on artificial muscles

PubMed Central

Haines, Carter S.; Li, Na; Spinks, Geoffrey M.; Aliev, Ali E.; Di, Jiangtao; Baughman, Ray H.

2016-01-01

Lightweight artificial muscle fibers that can match the large tensile stroke of natural muscles have been elusive. In particular, low stroke, limited cycle life, and inefficient energy conversion have combined with high cost and hysteretic performance to restrict practical use. In recent years, a new class of artificial muscles, based on highly twisted fibers, has emerged that can deliver more than 2,000 J/kg of specific work during muscle contraction, compared with just 40 J/kg for natural muscle. Thermally actuated muscles made from ordinary polymer fibers can deliver long-life, hysteresis-free tensile strokes of more than 30% and torsional actuation capable of spinning a paddle at speeds of more than 100,000 rpm. In this perspective, we explore the mechanisms and potential applications of present twisted fiber muscles and the future opportunities and challenges for developing twisted muscles having improved cycle rates, efficiencies, and functionality. We also demonstrate artificial muscle sewing threads and textiles and coiled structures that exhibit nearly unlimited actuation strokes. In addition to robotics and prosthetics, future applications include smart textiles that change breathability in response to temperature and moisture and window shutters that automatically open and close to conserve energy. PMID:27671626

Old Cellulose for New Multifunctional Networks

NASA Astrophysics Data System (ADS)

Yong, Geng

Cellulose is considered to be the most abundant and renewable natural polymer on earth. It is the main component of plant cells. The exploration of the utility and applications of this material and its derivatives has never stopped since human's birth. It is well known that cellulose based materials can generate films and fibers, which can be, for instance, produced from cellulosic solutions. The Cellulose rich chemical structure allows different behaviors of the polymer in solution, which is the driving force for diverse films and fibers features. The main goal of this work is the manufacture and characterization of new application of the renewable cellulosic-based materials, which are at the origin of stimuli-responsive and/or functional soft films and fibers. The several materials obtained have in common the main chain cellulose backbone but present different liquid crystalline properties. Firstly rheology coupled to nuclear magnetic resonance techniques (rheo-NMR) were used to characterize a cellulose-water based liquid crystalline solution in order to establish structure/properties relationships, which were the basis to improve the design of films and fibers produced in the framework of this work. The results achieved were at the origin of a paper published in Macromolecules. Then films were produced and due to their structure and enhanced mechanical properties, different applications were realized by producing cellulosic gratings, which mimic the periodic structures that can be found in some petals of plants and a soft cellulose moisture motor was built for the first time. Two manuscripts were published, one related to the grating mimics, in Macromolecular Chemistry and Physics, and the other one dedicated to the mechanical properties and the bending of a cellulosic film controlled by moisture action in Scientific Reports (Nature Publishing Group). Concerning cellulosic fibers, two methods were selected to fabricate micro/nano networks. In order to produce suspended aligned arrays, electrospinning was chosen due to its versatility. On the obtained nano/micro cylinders, nematic and cholesteric droplets were threaded producing necklaces of liquid crystal beads for the first time. The fiber changes not only the topology of the droplet but also distorts its spherical shape to an approximately ellipsoidal droplet. An additional cylindrical surface with planar anchoring along the droplet's long axis was also added. Designing nematic and cholesteric liquid crystal microdroplets on thin long threads opened new routes to produce fiber waveguides decorated with complex microresonators. Two Soft Matter scientific papers were published based on this work (One was chosen as the cover of that issue). Finally, nano-fibers produced by cellulose acid hydrolises were prepared and a new electro-optical sensor was built up and characterized and the results published in Liquid Crystals journal. Throughout this work Landau-de-Gennes theory was used in order to interpret and understand some of the experimental results achieved.

A Study On the effect of Surface treatment on the Physical and Mechanical properties of date-palm stem liber embedded epoxy composites

NASA Astrophysics Data System (ADS)

Tripathy, Satchidananda; Dehury, Janaki; Mishra, Debasmita

2016-02-01

Natural fiber reinforced polymer composites are being used frequently for variety of engineering applications due to many of their advantages like ease of availability, low density, low production cost and good mechanical properties but natural fibers are more or less hydrophilic in nature. Therefore, an investigation has been carried out to make better utilization of a class of natural fiber that is date palm stem fiber, for making a wide range of products. Attempts have been made in this research work to study the effect of fiber loading on the physical, mechanical and water absorption behaviour of treated and untreated short fiber based epoxy composites. Composites of various compositions of different amounts of fiber loading are fabricated by simple hand lay-up technique. It has been observed that there is a significant effect of surface treatment of fibers on the overall properties of composites. Further enhancement of properties with lower water absorption rate was attained with glass fiber-epoxy based hybrid composites.

A Review on the Perforated Impact Energy Absorption of Kenaf Fibres Reinforced Composites

NASA Astrophysics Data System (ADS)

Ismail, Al Emran; Khalid, S. N. A.; Nor, Nik Hisyamudin Muhd

2017-10-01

This paper reviews the potential of mechanical energy absorption of natural fiber reinforced composites subjected to perforated impact. According to literature survey, several research works discussing on the impact performances on natural fiber reinforced composites are available. However, most of these composite fibers are randomly arranged. Due to high demand for sustainable materials, many researches give high attention to enhance the mechanical capability of natural fiber composites especially focused on the fiber architecture. Therefore, it is important to review the progress of impact energy absorption on woven fiber composite in order to identify the research opportunities in the future.

Fibrous scaffolds fabricated by emulsion electrospinning: from hosting capacity to in vivo biocompatibility

NASA Astrophysics Data System (ADS)

Spano, F.; Quarta, A.; Martelli, C.; Ottobrini, L.; Rossi, R. M.; Gigli, G.; Blasi, L.

2016-04-01

Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post-implantation.Electrospinning is a versatile method for preparing functional three-dimensional scaffolds. Synthetic and natural polymers have been used to produce micro- and nanofibers that mimic extracellular matrices. Here, we describe the use of emulsion electrospinning to prepare blended fibers capable of hosting aqueous species and releasing them in solution. The existence of an aqueous and a non-aqueous phase allows water-soluble molecules to be introduced without altering the structure and the degradation of the fibers, and means that their release properties under physiological conditions can be controlled. To demonstrate the loading capability and flexibility of the blend, various species were introduced, from magnetic nanoparticles and quantum rods to biological molecules. Cellular studies showed the spontaneous adhesion and alignment of cells along the fibers. Finally, in vivo experiments demonstrated the high biocompatibility and safety of the scaffolds up to 21 days post-implantation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00782a

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.

Oil sorption and retention capacities of thermally-bonded hybrid nonwovens prepared from cotton, kapok, milkweed and polypropylene fibers.

PubMed

Thilagavathi, G; Praba Karan, C; Das, Dipayan

2018-08-01

This work reports on a series of thermally-bonded, hybrid and oil-sorbent nonwovens developed from binary and tertiary mixing of cotton, kapok, and three varieties of milkweed fibers (Asclepias Syriaca, Calotropis Procera and Calotropis Gigantea) and polypropylene fibers. The physical and chemical properties of the fibers were investigated to examine their oleophilic character. It was observed that all the fiber surfaces were covered with natural wax. Further, kapok and milkweed fibers were found to have less cell wall thickness and high void ratio. Oil sorption and retention characteristics of these fibers were studied in loose fibrous form as well as in structured assembly form (thermally-bonded nonwovens) using high density oil and diesel oil. The effects of fiber diameter, fiber cross-sectional shape, fiber surface area and porosity on the oil sorption behavior were discussed. An excellent and a selective oil sorption behavior of milkweed fibers (Calotropis Procera and Calotropis Gigantea) blended with cotton and polypropylene fibers were observed. The maximum oil sorption capacity of the developed thermal bonded nonwoven was 40.16 g/g for high density (HD) oil and 23.00 g/g for diesel oil. Further, a high porosity combined with high surface area played a major role in deciding the oil sorption and retention characteristics. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dynamic characterization of small fibers based on the flexural vibrations of a piezoelectric cantilever probe

NASA Astrophysics Data System (ADS)

Zhang, Xiaofei; Ye, Xuan; Li, Xide

2016-08-01

In this paper, we present a cantilever-probe system excited by a piezoelectric actuator, and use it to measure the dynamic mechanical properties of a micro- and nanoscale fiber. Coupling the fiber to the free end of the cantilever probe, we found the dynamic stiffness and damping coefficient of the fiber from the resonance frequency and the quality factor of the fiber-cantilever-probe system. The properties of Bacillus subtilis fibers measured using our proposed system agreed with tensile measurements, validating our method. Our measurements show that the piezoelectric actuator coupled to cantilever probe can be made equivalent to a clamped cantilever with an effective length, and calculated results show that the errors of measured natural frequency of the system can be ignored if the coupled fiber has an inclination angle of alignment of less than 10°. A sensitivity analysis indicates that the first or second resonant mode is the sensitive mode to test the sample’s dynamic stiffness, while the damping property has different sensitivities for the first four modes. Our theoretical analysis demonstrates that the double-cantilever probe is also an effective sensitive structure that can be used to perform dynamic loading and characterize dynamic response. Our method has the advantage of using amplitude-frequency curves to obtain the dynamic mechanical properties without directly measuring displacements and forces as in tensile tests, and it also avoids the effects of the complex surface structure and deformation presenting in contact resonance method. Our method is effective for measuring the dynamic mechanical properties of fiber-like one-dimensional (1D) materials.

Extraction of cellulose microcrystalline from galam wood for biopolymer

NASA Astrophysics Data System (ADS)

Ismail, Ika; Sa'adiyah, Devy; Rahajeng, Putri; Suprayitno, Abdi; Andiana, Rocky

2018-04-01

Consumption of plastic raw materials tends to increase, but until now the meet of the consumption of plastic raw are still low, even some are still imported. Nowadays, Indonesia's plastic needs are supported by petrochemicals where raw materials are still dependent abroad and petropolymer raw materials are derived from petroleum which will soon be depleted due to rising petroleum needs. Therefore, various studies have been conducted to develop natural fiber-based polymers that are biodegradable and abundant in nature. It is because the natural polymer production process is very efficient and very environmentally friendly. There have been many studies of biopolymers especially natural fiber-based polymers from plants, due to plants containing cellulose, hemicellulose and lignin. However, cellulose is the only one who has crystalline structures. Cellulose has a high crystality compared to amorphous lignin and hemicellulose. In this study, extracted cellulose as biopolymer and amplifier on composite. The cellulose is extracted from galam wood from East Kalimantan. Cellulose extraction will be obtained in nano / micro form through chemical and mechanical treatment processes. The chemical treatment of cellulose extraction is alkalinization process using NaOH solution, bleaching using NaClO2 and acid hydrolysis using sulfuric acid. After chemical treatment, ultrasonic mechanical treatment is made to make cellulose fibers into micro or nano size. Besides, cellulose results will be characterized. Characterization was performed to analyze molecules of cellulose compounds extracted from plants using Fourier Transformation Infra Red (FTIR) testing. XRD testing to analyze cellulose crystallinity. Scanning Electron Microscope (SEM) test to analyze morphology and fiber size.

Evaluation of tensile strength of hybrid fiber (jute/gongura) reinforced hybrid polymer matrix composites

NASA Astrophysics Data System (ADS)

Venkatachalam, G.; Gautham Shankar, A.; Vijay, Kumar V.; Chandan, Byral R.; Prabaharan, G. P.; Raghav, Dasarath

2015-07-01

The polymer matrix composites attract many industrial applications due to its light weight, less cost and easy for manufacturing. In this paper, an attempt is made to prepare and study of the tensile strength of hybrid (two natural) fibers reinforced hybrid (Natural + Synthetic) polymer matrix composites. The samples were prepared with hybrid reinforcement consists of two different fibers such as jute and Gongura and hybrid polymer consists of polyester and cashew nut shell resins. The hybrid composites tensile strength is evaluated to study the influence of various fiber parameters on mechanical strength. The parameters considered here are the duration of fiber treatment, the concentration of alkali in fiber treatment and nature of fiber content in the composites.

Optical solitons to the resonance nonlinear Schrödinger equation by Sine-Gordon equation method

NASA Astrophysics Data System (ADS)

Inc, Mustafa; Aliyu, Aliyu Isa; Yusuf, Abdullahi; Baleanu, Dumitru

2018-01-01

In this paper, we examined the optical solitons to the resonant nonlinear Schrödinger equation (R-NLSE) which describes the propagation of solitons through optical fibers. Three types of nonlinear media fibers are studied. They are; quadratic-cubic law, Kerr law and parabolic law. Dark, bright, dark-bright or combined optical and singular soliton solutions are derived using the sine-Gordon equation method (SGEM). The constraint conditions that naturally fall out of the solution structure which guarantee the existence of these solitons are also reported.

Combined pretreatment with hot compressed water and wet disk milling opened up oil palm biomass structure resulting in enhanced enzymatic digestibility.

PubMed

Zakaria, Mohd Rafein; Hirata, Satoshi; Fujimoto, Shinji; Hassan, Mohd Ali

2015-10-01

Combined pretreatment with hot compressed water and wet disk milling was performed with the aim to reduce the natural recalcitrance of oil palm biomass by opening its structure and provide maximal access to cellulase attack. Oil palm empty fruit bunch and oil palm frond fiber were first hydrothermally pretreated at 150-190° C and 10-240 min. Further treatment with wet disk milling resulted in nanofibrillation of fiber which caused the loosening of the tight biomass structure, thus increasing the subsequent enzymatic conversion of cellulose to glucose. The effectiveness of the combined pretreatments was evaluated by chemical composition changes, power consumption, morphological alterations by SEM and the enzymatic digestibility of treated samples. At optimal pretreatment process, approximately 88.5% and 100.0% of total sugar yields were obtained from oil palm empty fruit bunch and oil palm frond fiber samples, which only consumed about 15.1 and 23.5 MJ/kg of biomass, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of impregnation pressure and time on the porosity, structure and properties of polyacrylonitrile-fiber based carbon composites

NASA Astrophysics Data System (ADS)

Venugopalan, Ramani; Roy, Mainak; Thomas, Susy; Patra, A. K.; Sathiyamoorthy, D.; Tyagi, A. K.

2013-02-01

Carbon-carbon composites may find applications in critical parts of advanced nuclear reactors. A series of carbon-carbon composites were prepared using polyacrylonitrile (PAN) based carbon fibers. The materials were densified by impregnating two-dimensional (2D) preforms with liquid phenol formaldehyde resin at different pressures and for different periods of time and then carbonizing those by slowly heating at 1000 °C. Effects of the processing parameters on the structure of the composites were extensively studied. The study showed conclusively that open porosity decreased with increasing impregnation pressure, whereas impregnation time had lesser effect. Matrix-resin bonding also improved at higher pressure. d002 spacing decreased and ordering along c-axis increased with concomitant increase in sp2-carbon fraction at higher impregnation pressures. The fiber reinforced composites exhibited short range ordering of carbon atoms and satisfied structural conditions (d002 values) of amorphous carbon according to the turbostratic model for non-graphitic carbon materials. The composites had pellet-density of ˜85% of the theoretical value, low thermal expansion and negligible neutron-poisoning. They maintained structural integrity and retained disordered nature even on heat-treatment at ca. 1800 °C.

Structural health monitoring system/method using electroactive polymer fibers

NASA Technical Reports Server (NTRS)

Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor)

2013-01-01

A method for monitoring the structural health of a structure of interest by coupling one or more electroactive polymer fibers to the structure and monitoring the electroactive responses of the polymer fiber(s). Load changes that are experienced by the structure cause changes in the baseline responses of the polymer fiber(s). A system for monitoring the structural health of the structure is also provided.

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

USDA-ARS?s Scientific Manuscript database

The interactions of nanoparticles with polymer hosts have important implications for directing the macroscopic properties of composite fibers, yet little is known about such interactions with hierarchically ordered natural polymers due to the difficulty of achieving uniform dispersion of nanoparticl...

Collagen a natural scaffold for biology and engineering

USDA-ARS?s Scientific Manuscript database

Collagen, the most abundant protein in mammals, constitutes a quarter of the animal's total weight. The unique structure of fibrous collagens, a long triple helix that further associates into fibers, provides an insoluble scaffold that gives strength and form to the skin, tendons, bones, cornea and...

Single Honeybee Silk Protein Mimics Properties of Multi-Protein Silk

PubMed Central

Sutherland, Tara D.; Church, Jeffrey S.; Hu, Xiao; Huson, Mickey G.; Kaplan, David L.; Weisman, Sarah

2011-01-01

Honeybee silk is composed of four fibrous proteins that, unlike other silks, are readily synthesized at full-length and high yield. The four silk genes have been conserved for over 150 million years in all investigated bee, ant and hornet species, implying a distinct functional role for each protein. However, the amino acid composition and molecular architecture of the proteins are similar, suggesting functional redundancy. In this study we compare materials generated from a single honeybee silk protein to materials containing all four recombinant proteins or to natural honeybee silk. We analyse solution conformation by dynamic light scattering and circular dichroism, solid state structure by Fourier Transform Infrared spectroscopy and Raman spectroscopy, and fiber tensile properties by stress-strain analysis. The results demonstrate that fibers artificially generated from a single recombinant silk protein can reproduce the structural and mechanical properties of the natural silk. The importance of the four protein complex found in natural silk may lie in biological silk storage or hierarchical self-assembly. The finding that the functional properties of the mature material can be achieved with a single protein greatly simplifies the route to production for artificial honeybee silk. PMID:21311767

Aging-associated modifications of collagen affect its degradation by matrix metalloproteinases.

PubMed

Panwar, Preety; Butler, Georgina S; Jamroz, Andrew; Azizi, Pouya; Overall, Christopher M; Brömme, Dieter

2018-01-01

The natural aging process and various pathologies correlate with alterations in the composition and the structural and mechanical integrity of the connective tissue. Collagens represent the most abundant matrix proteins and provide for the overall stiffness and resilience of tissues. The structural changes of collagens and their susceptibility to degradation are associated with skin wrinkling, bone and cartilage deterioration, as well as cardiovascular and respiratory malfunctions. Here, matrix metalloproteinases (MMPs) are major contributors to tissue remodeling and collagen degradation. During aging, collagens are modified by mineralization, accumulation of advanced glycation end-products (AGEs), and the depletion of glycosaminoglycans (GAGs), which affect fiber stability and their susceptibility to MMP-mediated degradation. We found a reduced collagenolysis in mineralized and AGE-modified collagen fibers when compared to native fibrillar collagen. GAGs had no effect on MMP-mediated degradation of collagen. In general, MMP digestion led to a reduction in the mechanical strength of native and modified collagen fibers. Successive fiber degradation with MMPs and the cysteine-dependent collagenase, cathepsin K (CatK), resulted in their complete degradation. In contrast, MMP-generated fragments were not or only poorly cleaved by non-collagenolytic cathepsins such as cathepsin V (CatV). In conclusion, our data indicate that aging and disease-associated collagen modifications reduce tissue remodeling by MMPs and decrease the structural and mechanic integrity of collagen fibers, which both may exacerbate extracellular matrix pathology. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of natural fibers on the phase transitions in high-density polyethylene composites using dynamic mechanical analysis

Treesearch

Mehdi Tajvidi; Robert H. Falk; John C. Hermanson; Colin Felton

2003-01-01

Dynamic mechanical analysis was employed to evaluate the performance of various natural fibers in high-density polyethylene composites. Kenaf, newsprint, rice hulls, and wood flour were sources of fiber. Composites were made at 25 percent and 50 percent by weight fiber contents. Maleic anhydride modified polyethylene was also added at 1:25 ratio to the fiber....

Regenerated silk materials for functionalized silk orthopedic devices by mimicking natural processing.

PubMed

Li, Chunmei; Hotz, Blake; Ling, Shengjie; Guo, Jin; Haas, Dylan S; Marelli, Benedetto; Omenetto, Fiorenzo; Lin, Samuel J; Kaplan, David L

2016-12-01

Silk fibers spun by silkworms and spiders exhibit exceptional mechanical properties with a unique combination of strength, extensibility and toughness. In contrast, the mechanical properties of regenerated silk materials can be tuned through control of the fabrication process. Here we introduce a biomimetic, all-aqueous process, to obtain bulk regenerated silk-based materials for the fabrication of functionalized orthopedic devices. The silk materials generated in the process replicate the nano-scale structure of natural silk fibers and possess excellent mechanical properties. The biomimetic materials demonstrate excellent machinability, providing a path towards the fabrication of a new family of resorbable orthopedic devices where organic solvents are avoided, thus allowing functionalization with bioactive molecules to promote bone remodeling and integration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanical Characterization of Baslat Based Natural Hybrid Composites for Aerospace Applications

NASA Astrophysics Data System (ADS)

Alexander, J.; Elphej Churchill, S. J.

2017-05-01

Advanced composites have attracted aircraft designers due to its high strength to weight ratio, high stiffness to weight ratio, tailoring properties, hybridization of opposites etc. Moreover the cost reduction is also another important requirement of structural components. Basalt fibers are new entry in structural field which has excellent properties more or less equivalent to GFRP composites. Using these basalt fibres, new hybrid composites were developed by combining basalt fibres with natural fibres. The mechanical and thermal properties were determined and compared with BFRP and GFRP composites. Results proved that hybrid composites have some good qualities.

Temperature measurement and damage detection in concrete beams exposed to fire using PPP-BOTDA based fiber optic sensors

NASA Astrophysics Data System (ADS)

Bao, Yi; Hoehler, Matthew S.; Smith, Christopher M.; Bundy, Matthew; Chen, Genda

2017-10-01

In this study, Brillouin scattering-based distributed fiber optic sensor is implemented to measure temperature distributions and detect cracks in concrete structures subjected to fire for the first time. A telecommunication-grade optical fiber is characterized as a high temperature sensor with pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA), and implemented to measure spatially-distributed temperatures in reinforced concrete beams in fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9%. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

LOW-COST COMPOSITES IN VEHICLE MANUFACTURE - Natural-fiber-reinforced polymer composites in automotive applications.

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

Holbery, Jim; Houston, Dan

In the last decade, natural fiber composites have experienced rapid growth in the European automotive market, and this trend appears to be global in scale, provided the cost and performance is justified against competing technologies. However, mass reduction, recyclability, and performance requirements can be met today by competing systems such as injection-molded unreinforced thermoplastics; natural fiber composites will continue to expand their role in automotive applications only if such technical challenges as moisture stability, fiber-polymer interface compatibility, and consistent, repeatable fiber sources are available to supply automotive manufacturers. Efforts underway by Tier I and II automotive suppliers to explore hybridmore » glass-natural fiber systems, as well as applications that exploit such capabilities as natural fiber sound dampening characteristics, could very well have far-reaching effects. In addition, the current development underway of bio-based resins such as Polyhydroxyalkanoate (PHA) biodegradable polyesters and bio-based polyols could provide fully bio-based composite options to future automotive designers. In short, the development of the natural fiber composite market would make a positive impact on farmers and small business owners on a global scale, reduce US reliance on foreign oil, improve environmental quality through the development of a sustainable resource supply chain, and achieve a better CO2 balance over the vehicle?s lifetime with near-zero net greenhouse gas emissions.« less

Performance Using Bamboo Fiber Ash Concrete as Admixture Adding Superplasticizer

NASA Astrophysics Data System (ADS)

Vasudevan, Gunalaan

2017-06-01

The increasing demand on natural resources for housing provisions in developing countries have called for sourcing and use of sustainable local materials for building and housing delivery. Natural materials to be considered sustainable for building construction should be ‘green’ and obtained from local sources, including rapidly renewable plant materials like palm fronds and bamboo, recycled materials and other products that are reusable and renewable. Each year, tens of millions of tons of bamboo are utilized commercially, generating a vast amount of waste. Besides that, bamboo fiber is easy availability, low density, low production cost and satisfactory mechanical properties. One solution is to activate this waste by using it as an additive admixture in concrete to keep it out of landfills and save money on waste disposal. The research investigates the mechanical and physical properties of bamboo fiber powder in a blended Portland cement. The structural value of the bamboo fiber powder in a blended Portland cement was evaluated with consideration for its suitability in concrete. Varied percentage of bamboo fiber powder (BFP) at 0%, 5%, 10%, 15%, and 20% as an admixture in 1:2:4 concrete mixes. The workability of the mix was determined through slump; standard consistency test was carried on the cement. Compressive strength of hardened cured (150 x 150 x 150) mm concrete cubes at 7days, 14days and 28days were tested.

Cytocompatible and water stable ultrafine protein fibers for tissue engineering

NASA Astrophysics Data System (ADS)

Jiang, Qiuran

This dissertation proposal focuses on the development of cytocompatible and water stable protein ultrafine fibers for tissue engineering. The protein-based ultrafine fibers have the potential to be used for biomedicine, due to their biocompatibility, biodegradability, similarity to natural extracellular matrix (ECM) in physical structure and chemical composition, and superior adsorption properties due to their high surface to volume ratio. However, the current technologies to produce the protein-based ultrafine fibers for biomedical applications still have several problems. For instance, the current electrospinning and phase separation technologies generate scaffolds composed of densely compacted ultrafine fibers, and cells can spread just on the surface of the fiber bulk, and hardly penetrate into the inner sections of scaffolds. Thus, these scaffolds can merely emulate the ECM as a two dimensional basement membrane, but are difficult to mimic the three dimensional ECM stroma. Moreover, the protein-based ultrafine fibers do not possess sufficient water stability and strength for biomedical applications, and need modifications such as crosslinking. However, current crosslinking methods are either high in toxicity or low in crosslinking efficiency. To solve the problems mentioned above, zein, collagen, and gelatin were selected as the raw materials to represent plant proteins, animal proteins, and denatured proteins in this dissertation. A benign solvent system was developed specifically for the fabrication of collagen ultrafine fibers. In addition, the gelatin scaffolds with a loose fibrous structure, high cell-accessibility and cell viability were produced by a novel ultralow concentration phase separation method aiming to simulate the structure of three dimensional (3D) ECM stroma. Non-toxic crosslinking methods using citric acid as the crosslinker were also developed for electrospun or phase separated scaffolds from these three proteins, and proved to be efficient to enhance the strength and water stability of scaffolds. The crosslinked protein scaffolds showed higher cytocompatibility than the polylactic acid scaffolds and the fibers crosslinked by glutaraldehyde. The potential of using these protein-based ultrafine fibers crosslinked by citric acid for tissue engineering has been proved in this dissertation.

Physical characterization of functionalized spider silk: electronic and sensing properties

PubMed Central

Steven, Eden; Park, Jin Gyu; Paravastu, Anant; Lopes, Elsa Branco; Brooks, James S; Englander, Ongi; Siegrist, Theo; Kaner, Papatya; Alamo, Rufina G

2011-01-01

This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof-of-concept applications of functionalized spider silk are presented for thermoelectric (Seebeck) effects and incandescence in iodine-doped pyrolized silk fibers, and metallic conductivity and flexibility of micron-sized gold-sputtered silk fibers. In the latter case, we demonstrate the application of gold-sputtered neat spider silk to make four-terminal, flexible, ohmic contacts to organic superconductor samples. PMID:27877440

Fatigue damage evaluation of short fiber CFRP based on phase information of thermoelastic temperature change

NASA Astrophysics Data System (ADS)

Sakagami, Takahide; Shiozawa, Daiki; Nakamura, Yu; Nonaka, Shinichi; Hamada, Kenichi

2017-05-01

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to the evaluation of fatigue damage in short carbon fiber composites. The distributions of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damages was detected from distributions of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was clearly detected than ever by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the nature that carbon fiber show opposite phase thermoelastic temperature change.

Characterization of aerosols and fibers emitted from composite materials combustion.

PubMed

Chivas-Joly, C; Gaie-Levrel, F; Motzkus, C; Ducourtieux, S; Delvallée, A; De Lagos, F; Nevé, S Le; Gutierrez, J; Lopez-Cuesta, J-M

2016-01-15

This work investigates the aerosols emitted during combustion of aircraft and naval structural composite materials (epoxy resin/carbon fibers and vinyl ester/glass fibers and carbon nanotubes). Combustion tests were performed at lab-scale using a modified cone calorimeter. The aerosols emitted have been characterized using various metrological devices devoted to the analysis of aerosols. The influence of the nature of polymer matrices, the incorporation of fibers and carbon nanotubes as well as glass reinforcements on the number concentration and the size distribution of airborne particles produced, was studied in the 5 nm-10 μm range. Incorporation of carbon fibers into epoxy resin significantly reduced the total particle number concentration. In addition, the interlaced orientation of carbon fibers limited the particles production compared to the composites with unidirectional one. The carbon nanotubes loading in vinyl ester resin composites influenced the total particles production during the flaming combustion with changes during kinetics emission. Predominant populations of airborne particles generated during combustion of all tested composites were characterized by a PN50 following by PN(100-500). Copyright © 2015 Elsevier B.V. All rights reserved.

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

Driscoll, Mark S.; Smith, Jennifer L.; Woods, Sean

One of the main problems associated with the use of natural fibers as reinforcing agents in composites is their uptake of moisture. Many natural fibers are lignocellulosic, which causes them to swell and shrink as the amount of available moisture changes. Swelling and shrinking can cause composites to prematurely fail. This paper presents the results of a preliminary study that considers the use of two different low molecular weight monomers, hydroxyethyl methacrylate (HEMA) and hydroxyethyl acrylate (HEA), polymerized by electron beam ionizing radiation, to dimensionally stabilize natural fibers. Eight different treatments consisting of varying amounts of monomer, encapsulating agent, andmore » cross-linkers, were evaluated for their ability to dimensionally stabilize sisal fiber. Results indicate that both polymerized HEA and HEMA can reduce the swelling of sisal fiber. The effectiveness of HEA and HEMA can be further enhanced with the use of a cross-linker (SR 454). The use of hydroxylated monomers to dimensionally stabilize natural fibers may play an important role in reducing delamination and improving fiber-resin adhesion in composites.« less

Effect of natural fibers on mechanical properties of green cement mortar

NASA Astrophysics Data System (ADS)

AL-Zubaidi, Aseel B.

2018-05-01

Natural fibers of banana, reed, palm and coconut were used to reinforce cement composite. Optical microscopy showed that the prepared fibers are different in size and morphology. Nearly equiaxed, ribbon-like and nearly cylindrical morphologies were observed. Each of the utilized natural fibers was incorporated in the cement matrix at 0, 0.25, 0.5, 0.75 and 1.0 wt% and cured for 28 days. The scanning electron micrographs for the 1.0 wt% -reinforced composite showed differences in porosity, grain size and shape. Each of the utilized fibers has different effect on the microstructure of the cement composite that depends on the fiber size and morphology. Water absorption, thermal conductivity, bending strength, hardness and compression strengths were measured for the reinforced cement composite. It is found that the final physical and mechanical properties of the set cement composite depend on the fiber content and fiber type through the differences in their sizes and morphologies.

Rotational 3D printing of damage-tolerant composites with programmable mechanics.

PubMed

Raney, Jordan R; Compton, Brett G; Mueller, Jochen; Ober, Thomas J; Shea, Kristina; Lewis, Jennifer A

2018-02-06

Natural composites exhibit exceptional mechanical performance that often arises from complex fiber arrangements within continuous matrices. Inspired by these natural systems, we developed a rotational 3D printing method that enables spatially controlled orientation of short fibers in polymer matrices solely by varying the nozzle rotation speed relative to the printing speed. Using this method, we fabricated carbon fiber-epoxy composites composed of volume elements (voxels) with programmably defined fiber arrangements, including adjacent regions with orthogonally and helically oriented fibers that lead to nonuniform strain and failure as well as those with purely helical fiber orientations akin to natural composites that exhibit enhanced damage tolerance. Our approach broadens the design, microstructural complexity, and performance space for fiber-reinforced composites through site-specific optimization of their fiber orientation, strain, failure, and damage tolerance. Copyright © 2018 the Author(s). Published by PNAS.

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

PubMed Central

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

2012-01-01

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

Extreme Light Management in Mesoporous Wood Cellulose Paper for Optoelectronics.

PubMed

Zhu, Hongli; Fang, Zhiqiang; Wang, Zhu; Dai, Jiaqi; Yao, Yonggang; Shen, Fei; Preston, Colin; Wu, Wenxin; Peng, Peng; Jang, Nathaniel; Yu, Qingkai; Yu, Zongfu; Hu, Liangbing

2016-01-26

Wood fibers possess natural unique hierarchical and mesoporous structures that enable a variety of new applications beyond their traditional use. We dramatically modulate the propagation of light through random network of wood fibers. A highly transparent and clear paper with transmittance >90% and haze <1.0% applicable for high-definition displays is achieved. By altering the morphology of the same wood fibers that form the paper, highly transparent and hazy paper targeted for other applications such as solar cell and antiglare coating with transmittance >90% and haze >90% is also achieved. A thorough investigation of the relation between the mesoporous structure and the optical properties in transparent paper was conducted, including full-spectrum optical simulations. We demonstrate commercially competitive multitouch touch screen with clear paper as a replacement for plastic substrates, which shows excellent process compatibility and comparable device performance for commercial applications. Transparent cellulose paper with tunable optical properties is an emerging photonic material that will realize a range of much improved flexible electronics, photonics, and optoelectronics.

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

NASA Astrophysics Data System (ADS)

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

2009-07-01

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

Production And Characterization Of Synthetic Spider Silks Based On Nephila Clavipes Major Ampullate Silk Proteins

NASA Astrophysics Data System (ADS)

An, Bo

The extraordinary mechanical properties of orb-weaving spider silks have served spiders for over 400 million years. However, only in the late 20th century did we start to understand the molecular nature of spider silk that contributes to its incredible properties as biomaterials. Among all seven types of spider silks, major ampullate silk from typical orb-weaving spiders is the toughest of all, it consists of primarily two proteins: MaSp1 and MaSp2. Variable ratios and conserved motifs of these two proteins in all the native spider silks demonstrate the significant role of MaSp1 and MaSp2 in controlling the mechanical properties of the fiber. The amino acid sequences of the orb weaving spider silk proteins have remained almost unchanged for more than 100 million years. Interestingly, MaSp1 and MaSp2 are the only two components in all studied dragline silk fibers from these spiders. The mechanical properties of native dragline silk vary slightly between species, which are believed to relate to the ratio of MaSp1 to MaSp2 in the silk. Both of these facts clearly indicate the importance of these two proteins to the mechanical properties of the fiber. Various types of synthetic spider silk fibers have been produced and studied in an effort to mass-produce man-made fibers with qualities comparable to native spider silk. To investigate the roles of MaSp1 and MaSp2 in silk fiber, synthetic MaSp1 (major abundant protein in Nephila clavipes major ampullate silks) only fibers, MaSp1/MaSp2 protein mixture fibers and chimeric protein fibers with both MaSp1 and MaSp2 sequence features have been produced and tested for mechanical properties. Solid-State Nuclear Magnetic Resonance was used to characterize the structure of silk fibers and reveal the relation between fiber spatial structure and mechanical properties.

Burning characteristics and fiber retention of graphite/resin matrix composites

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1980-01-01

Graphite fiber reinforced resin matrix composites were subjected to controlled burning conditions to determine their burning characteristics and fiber retention properties. Small samples were burned with a natural gas fired torch to study the effects of fiber orientation and structural flaws such as holes and slits that were machined into the laminates. Larger laminate samples were burned in a modified heat release rate calorimeter. Unidirectional epoxy/graphite and polyimide/graphite composites and boron powder filled samples of each of the two composite systems were burn tested. The composites were exposed to a thermal radiation of 5.3 Btu/sq ft-sec in air. Samples of each of the unfilled composite were decomposed anaerobically in the calorimeter. Weight loss data were recorded for burning and decomposition times up to thirty-five minutes. The effects of fiber orientation, flaws, and boron filler additives to the resins were evaluated. A high char forming polyimide resin was no more effective in retaining graphite fibers than a low char forming epoxy resin when burned in air. Boron powder additions to both the polyimide and the epoxy resins stabilized the chars and effectively controlled the fiber release.

Evaluation of agave fiber delignification by means of microscopy techniques and image analysis.

PubMed

Hernández-Hernández, Hilda M; Chanona-Pérez, Jorge J; Calderón-Domínguez, Georgina; Perea-Flores, María J; Mendoza-Pérez, Jorge A; Vega, Alberto; Ligero, Pablo; Palacios-González, Eduardo; Farrera-Rebollo, Reynold R

2014-10-01

Recently, the use of different types of natural fibers to produce paper and textiles from agave plants has been proposed. Agave atrovirens can be a good source of cellulose and lignin; nevertheless, the microstructural changes that happen during delignification have scarcely been studied. The aim of this work was to study the microstructural changes that occur during the delignification of agave fibers by means of microscopy techniques and image analysis. The fibers of A. atrovirens were obtained from leaves using convective drying, milling, and sieving. Fibers were processed using the Acetosolv pulping method at different concentrations of acetic acid; increasing acid concentration promoted higher levels of delignification, structural damage, and the breakdown of fiber clumps. Delignification followed by spectrometric analysis and microstructural studies were carried out by light, confocal laser scanning and scanning electron microscopy and showed that the delignification process follows three stages: initial, bulk, and residual. Microscopy techniques and image analysis were efficient tools for microstructural characterization during delignification of agave fibers, allowing quantitative evaluation of the process and the development of linear prediction models. The data obtained integrated numerical and microstructural information that could be valuable for the study of pulping of lignocellulosic materials.

Healthy hair: what is it?

PubMed

Sinclair, Rodney D

2007-12-01

Shiny hair with a smooth texture and clean-cut ends or tapered tips is generally perceived to be healthy. Hair texture and shine relate to hair surface properties, whereas the integrity of hair ends relates to the hair cortex. Hair can be straight, wavy or curly, blonde, black, brown, red, gray white, and its natural variations are important to our identity. Manipulation of the normal structure of the hair shaft is epidemic and dictated by culture, fashion, and above all, celebrity. Although cosmetic procedures are intrinsically safe, there is potential for damage to the hair. Loss of lustre, frizz, split ends, and other hair problems are particularly prevalent among people who repeatedly alter the natural style of their hair or among people with hair that is intrinsically weak. This may be due to individual or racial variation or less commonly an inherited structural abnormality in hair fiber formation. Hair health is also affected by common afflictions of the scalp as well as age-related phenomena such as graying and androgenetic alopecia. Hair products that improve the structural integrity of hair fibers and increase tensile strength are available, as are products that increase hair volume, reduce frizz, improve hair manageability, and stimulate new hair growth.

Characterization of new natural cellulosic fiber from Lygeum spartum L.

PubMed

Belouadah, Z; Ati, A; Rokbi, M

2015-12-10

Integration of new natural fibers in polymer composites field can contribute to increase the production of natural reinforcements and expand their use into new applications. In the present work, new cellulosic fibers were extracted from Lygeum spartum L. plant using an eco-friendly method. The morphological, physico-chemical, thermal and mechanical properties of L. spartum L. fibers were reported for the first time in this paper. The stem anatomy and fiber SEM micrographs showed a strong presence of fiber cells. ATR-FTIR and X-ray analysis proved that these fibers are rich in cellulose content with crystallinity index of 46.19%. The thermogravimetric analysis indicates that the L. spartum fibers are thermally stable until 220 °C with apparent activation energy of 68.77 kJ/mol. Young's modulus, tensile strength and strain at failure were determined from the single fiber tensile test as 13.2 GPa, 280 MPa, and 3.7% respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Neuropathy-induced spinal GAP-43 expression is not a main player in the onset of mechanical pain hypersensitivity.

PubMed

Jaken, Robby J; van Gorp, Sebastiaan; Joosten, Elbert A; Losen, Mario; Martínez-Martínez, Pilar; De Baets, Marc; Marcus, Marco A; Deumens, Ronald

2011-12-01

Structural plasticity within the spinal nociceptive network may be fundamental to the chronic nature of neuropathic pain. In the present study, the spatiotemporal expression of growth-associated protein-43 (GAP-43), a protein which has been traditionally implicated in nerve fiber growth and sprouting, was investigated in relation to mechanical pain hypersensitivity. An L5 spinal nerve transection model was validated by the presence of mechanical pain hypersensitivity and an increase in the early neuronal activation marker cFos within the superficial spinal dorsal horn upon innocuous hindpaw stimulation. Spinal GAP-43 was found to be upregulated in the superficial L5 dorsal horn from 5 up to 10 days after injury. GAP-43 was co-localized with calcitonin-gene related peptide (CGRP), but not vesicular glutamate transporter-1 (VGLUT-1), IB4, or protein kinase-γ (PKC-γ), suggesting the regulation of GAP-43 in peptidergic nociceptive afferents. These GAP-43/CGRP fibers may be indicative of sprouting peptidergic fibers. Fiber sprouting largely depends on growth factors, which are typically associated with neuro-inflammatory processes. The putative role of neuropathy-induced GAP-43 expression in the development of mechanical pain hypersensitivity was investigated using the immune modulator propentofylline. Propentofylline treatment strongly attenuated the development of mechanical pain hypersensitivity and glial responses to nerve injury as measured by microglial and astroglial markers, but did not affect neuropathy-induced levels of spinal GAP-43 or GAP-43 regulation in CGRP fibers. We conclude that nerve injury induces structural plasticity in fibers expressing CGRP, which is regarded as a main player in central sensitization. Our data do not, however, support a major role of these structural changes in the onset of mechanical pain hypersensitivity.

Strain of optic-fiber/giant magnetostrictive film structure in magnetic field by finite element analysis

NASA Astrophysics Data System (ADS)

Hu, Jiafei; Pan, Mengchun; Xin, Jianguang; Chen, Dixiang

2008-12-01

The magnetostrictive transducer is the most important part of the optic-fiber magnetic field sensor, and the optic-fiber/giant magnetostrictive(GMS) film coupled structure is a novel coupling form of the magnetostrictive transducer. Always we analyze the coupled structure based on the entire coupled structure being sputtered GMS material without tail-fibers. In practical application, the coupled structure has tail-fibers without films at two ends. When the entire coupled structure is immersed in the detected magnetic field, the detected magnetic field causes the GMS film strain then causing optic-fiber strain. This strain transmission process is different from it in the coupled structure entirely with GMS films without tail-fibers. The strain transmission relationship can be calculated theoretically in the coupled structure without tail-fibers, but it's complicated to theoretically calculate the strain transmission relationship in the coupled structure with tail-fibers. After large numbers of calculations and analyses by ANSYS software, we figure out some relationships of the two strain transmission processes in the respective structures and the stress distribution in the tail-fibers. These results are helpful to the practical application of the optic-fiber/ GMS film coupled structure.

Holographic imaging of natural-fiber-containing materials

DOEpatents

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

2010-12-21

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

Nde of Lumber and Natural Fiber Based Products with Air Coupled Ultrasound

NASA Astrophysics Data System (ADS)

Hsu, David K.; Utrata, David; Kuo, Monlin

2010-02-01

Due to the porous nature of wood and natural fiber based products, conventional fluid or gel coupled ultrasonic inspection is unsuitable. Air-coupled ultrasonic transmission scanning, being non-contact, is ideally suited for inspecting lumber, wood and natural fiber based products. We report here several successful applications of air-coupled ultrasound for the inspection of wood. Air-coupled ultrasonic scan at 120 kHz can easily detect "sinker-stock" lumber in which bacterial damage of ray tissue cells had occurred during anaerobic pond storage. Channels in ash lumber board caused by insect bore were imaged in transmission scan. Delamination and material inhomogeneities were mapped out in manufactured wood and natural fiber products including medium density fiberboards, compression molded shredded waste wood with formaldehyde resin, and acoustic panels molded with kenaf fibers. The study has demonstrated some of the capabilities of air-coupled ultrasound in the NDE of forest products.

Experimental Investigation and Analysis of Mercerized and Citric Acid Surface Treated Bamboo Fiber Reinforced Composite

NASA Astrophysics Data System (ADS)

De, Jyotiraman; Baxi, R. N., Dr.

2017-08-01

Mercerization or NaOH fiber surface treatment is one of the most popular surface treatment processes to make the natural fibers such as bamboo fibers compatible for use as reinforcing material in composites. But NaOH being a chemical is hazardous and polluting to the nature. This paper explores the possibility of use of naturally derived citric acid for bamboo fiber surface treatment and its comparison with NaOH treated Bamboo Fiber Composites. Untreated, 2.5 wt% NaOH treated and 5 wt% citric acid treated Bamboo Fiber Composites with 5 wt% fiber content were developed by Hand Lay process. Bamboo mats made of bamboo slivers were used as reinforcing material. Mechanical and physical characterization was done to compare the effects of NaOH and citric acid bamboo fiber surface treatment on mechanical and physical properties of Bamboo Fiber Composite. The experiment data reveals that the tensile and flexural strength was found to be highest for citric acid and NaOH treated Bamboo Fiber Composite respectively. Water absorption tendency was found more than the NaOH treated Bamboo Fiber Composites. SEM micrographs used to analyze the morphology of fracture surface of tensile test specimens confirm improvement in fiber-matrix interface bonding due to surface treatment of bamboo fibers.

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

Rotational 3D printing of damage-tolerant composites with programmable mechanics

PubMed Central

Raney, Jordan R.; Compton, Brett G.; Ober, Thomas J.; Shea, Kristina; Lewis, Jennifer A.

2018-01-01

Natural composites exhibit exceptional mechanical performance that often arises from complex fiber arrangements within continuous matrices. Inspired by these natural systems, we developed a rotational 3D printing method that enables spatially controlled orientation of short fibers in polymer matrices solely by varying the nozzle rotation speed relative to the printing speed. Using this method, we fabricated carbon fiber–epoxy composites composed of volume elements (voxels) with programmably defined fiber arrangements, including adjacent regions with orthogonally and helically oriented fibers that lead to nonuniform strain and failure as well as those with purely helical fiber orientations akin to natural composites that exhibit enhanced damage tolerance. Our approach broadens the design, microstructural complexity, and performance space for fiber-reinforced composites through site-specific optimization of their fiber orientation, strain, failure, and damage tolerance. PMID:29348206

Modified natural fibrils for structural hybrid composites: Towards an investigation of textile reduction

NASA Astrophysics Data System (ADS)

Ufodike, Chukwuzubelu Okenwa

Recently, the interest for renewable resources for fibers particularly of plant origin has been increasing. Reduction of use of traditional textile materials is now considered more critical due to the increasing environmental concern. Natural fibers are renewable, biodegradable, recyclable, and lightweight materials with high specific modulus, in competition with man-made fossil materials and fiberglass. Natural fibers are used for preparation of functionalized textiles to achieve smart and intelligent properties. However, the incorporation of these fibers in composite systems has been challenging due to their hydrophilic nature. Nevertheless, the fact that these biodegradable materials can be manipulated at a nano-scale to complement desired objective and application has made them a favorable option. The idea behind this project is to explore ways to convert green waste to high value materials and to utilize natural building blocks to design textile reinforcement materials. In this work, cellulose nanofibrils (CNF) supplied from the University of Maine were hydrophobized by silylation and characterized using Fourier-Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, and Thermogravimetric analysis (TGA). Results from FTIR spectroscopy showed a formation of Si-O-C bonds, indicating better fiber-matrix adhesion. Raman spectroscopy showed disruption of hydrogen bonding which indicates interference of parallel nanocellulose fiber adhesion to neighboring fibrils. The TGA suggests that the thermal stability of the functionalized CNF is higher than that of the corresponding neat sample, which could be a result of stable Si bond formation. The raw materials (neat and functionalized) were encapsulated in a polystyrene matrix through a solvent and non-solvent precipitation process, and then extruded using single and dual heat processing. The extruded thin filaments were tested according to the ASTM D638 (tensile test of plastics). Results showed an increasing Ultimate Tensile Strength (UTS) and Elastic Modulus, with peak values attributed to the dual-heat processing up to 79% and 69% increase respectively at 5wt% loading. Further increase was seen at 10wt% loading up to 112MPa UTS, and modulus up to 10.7GPa for the dual-heat processing. The UTS increase is assumed to be a result of linear arrangement of CNF in the matrix during the extrusion process. The results revealed the strong reinforcing ability of CNF and their compatibility with thermoplastic matrix if functionalized.

Influence of heating procedures on the surface structure of stabilized polyacrylonitrile fibers

NASA Astrophysics Data System (ADS)

Zhao, Rui-Xue; Sun, Peng-fei; Liu, Rui-jian; Ding, Zhan-hui; Li, Xiang-shan; Liu, Xiao-yang; Zhao, Xu-dong; Gao, Zhong-min

2018-03-01

The stabilized polyacrylonitrile (PAN) fibers were obtained after heating the precursor PAN fibers under air atmosphere by different procedures. The surface structures and compositions of as-prepared stabilized PAN fibers have been investigated by SEM, SSNMR, XPS and Raman spectroscopy. The results show that 200 °C, 220 °C, 250 °C, and 280 °C are key temperatures for the preparation of stabilized PAN fibers. The effect of heating gradient on the structure of stabilized PAN fibers has been studied. The possible chemical structural formulas for the PAN fibers is provided, which include the stable and unstable structure. The stable structure (α-type) could endure the strong chemical reactions and the unstable structure (β- or γ-type) could mitigate the drastic oxidation reactions. The inferences of chemical formula of stabilized PAN fibers are benefit to the design of appropriate surface structure for the production for high quality carbon fibers.

On the Theory and Numerical Simulation of Cohesive Crack Propagation with Application to Fiber-Reinforced Composites

NASA Technical Reports Server (NTRS)

Rudraraju, Siva Shankar; Garikipati, Krishna; Waas, Anthony M.; Bednarcyk, Brett A.

2013-01-01

The phenomenon of crack propagation is among the predominant modes of failure in many natural and engineering structures, often leading to severe loss of structural integrity and catastrophic failure. Thus, the ability to understand and a priori simulate the evolution of this failure mode has been one of the cornerstones of applied mechanics and structural engineering and is broadly referred to as "fracture mechanics." The work reported herein focuses on extending this understanding, in the context of through-thickness crack propagation in cohesive materials, through the development of a continuum-level multiscale numerical framework, which represents cracks as displacement discontinuities across a surface of zero measure. This report presents the relevant theory, mathematical framework, numerical modeling, and experimental investigations of through-thickness crack propagation in fiber-reinforced composites using the Variational Multiscale Cohesive Method (VMCM) developed by the authors.

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.

Effects of Structural Properties of Electrospun TiO2 Nano-fiber Meshes on their Osteogenic Potential

PubMed Central

Wang, Xiaokun; Gittens, Rolando A.; Song, Rosemary; Tannenbaum, Rina; Olivares-Navarrete, Rene; Schwartz, Zvi; Chen, Haifeng; Boyan, Barbara D.

2011-01-01

Ideal outcomes in the field of tissue engineering and regenerative medicine involve biomaterials that can enhance cell differentiation and production of local factors for natural tissue regeneration without the use of systemic drugs. Biomaterials typically used in tissue engineering applications include polymeric scaffolds that mimic the 3-D structural environment of the native tissue, but these are often functionalized with proteins or small peptides to improve their biological performance. For bone applications, titanium (Ti) implants, or more appropriately the titania (TiO2) passive oxide layer formed on their surface, have been shown to enhance osteoblast differentiation in vitro and to promote osseointegration in vivo. In this study we evaluated the effect on osteoblast differentiation of pure TiO2 nano-fiber meshes with different surface micro-roughness and nano-fiber diameters, prepared by the electrospinning method. MG63 cells were seeded on TiO2 meshes, and cell number, differentiation markers and local factor production were analyzed. The results showed that cells grew throughout the entire surfaces and with similar morphology in all groups. Cell number was sensitive to surface micro-roughness, whereas cell differentiation and local factor production was regulated by both surface roughness and nano-fiber diameter. These results indicate that scaffold structural cues alone can be used to drive cell differentiation and create an osteogenic environment without the use of exogenous factors. PMID:22075122

Regeneration of Bombyx mori silk nanofibers and nanocomposite fibrils by the electrospinning process

NASA Astrophysics Data System (ADS)

Ayutsede, Jonathan Eyitouyo

In recent years, there has been significant interest in the utilization of natural materials for novel nanoproducts such as tissue engineered scaffolds. Silkworm silk fibers represent one of the strongest natural fibers known. Silkworm silk, a protein-based natural biopolymer, has received renewed interest in recent years due to its unique properties (strength, toughness) and potential applications such as smart textiles, protective clothing and tissue engineering. The traditional 10--20 mum diameter, triangular-shaped Bombyx mori fibers have remained unchanged over the years. However, in our study, we examine the scientific implication and potential applications of reducing the diameter to the nanoscale, changing the triangular shape of the fiber and adding nanofillers in the form of single wall carbon nanotubes (SWNT) by the electrospinning process. The electrospinning process preserves the natural conformation of the silk (random and beta-sheet). The feasibility of changing the properties of the electrospun nanofibers by post processing treatments (annealing and chemical treatment) was investigated. B. mori silk fibroin solution (formic acid) was successfully electrospun to produce uniform nanofibers (as small as 12 nm). Response Surface Methodology (RSM) was applied for the first time to experimental results of electrospinning, to develop a processing window that can reproduce regenerated silk nanofibers of a predictable size (d < 100nm). SWNT-silk multifunctional nanocomposite fibers were fabricated for the first time with anticipated properties (mechanical, thermal and electrically conductive) that may have scientific applications (nerve regeneration, stimulation of cell-scaffold interaction). In order to realize these applications, the following areas need to be addressed: a systematic investigation of the dispersion of the nanotubes in the silk matrix, a determination of new methodologies for characterizing the nanofiber properties and establishing the nature of the silk-SWNT interactions. A new visualization system was developed to characterize the transport properties of the nanofibrous assemblies. The morphological, chemical, structural and mechanical properties of the nanofibers were determined by field emission environmental scanning microscopy, Fourier transform infrared and Raman spectroscopy, wide angle x-ray diffraction and microtensile tester respectively.

Nonwoven production from agricultural okra wastes and investigation of their thermal conductivities

NASA Astrophysics Data System (ADS)

Duman, M. N.; Kocak, E. D.; Merdan, N.; Mistik, I.

2017-10-01

Nowadays bio-based composite materials have been used in rising amounts and demanded widely in industrial uses, as they provide cost reduction and weight loss in the end use products. Agricultural cellulose based wastes can be a good alternative to synthetic fibers and can be used in natural fiber reinforced composite production, as there is a huge (more than 40 million tons) potential for natural cellulose production from agricultural wastes. Okra is one of the most grown vegetables around the world with stems left on the fields after harvest. When the similarity of mechanical properties of okra fibers with traditional bast fibers (flax, kenaf, hemp) are considered, from an economical and an environmental point of view this research emphasizes the potential of agricultural biomass for natural fiber production. In this study, okra stem wastes used for natural cellulosic fiber production and treated with 10% NaOH at 60°C for 10, 20, 30 and 40 minutes. By alkali treatment, decrease in fiber diameter and weight, and increase in tensile strength and elongation % have been observed. Nonwoven production has been done from both the fibers with and without surface treatments. Thermal conductivity properties of both nonwovens have been investigated.

Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity.

PubMed

Xia, Changlei; Garcia, Andres C; Shi, Sheldon Q; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R; D'Souza, Nandika A; Nie, Xu

2016-10-05

Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m -1 K -1 , which was 72.3% higher than that (3.600 W m -1 K -1 ) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler's interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite's use as an engineered material.

Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity

NASA Astrophysics Data System (ADS)

Xia, Changlei; Garcia, Andres C.; Shi, Sheldon Q.; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R.; D'Souza, Nandika A.; Nie, Xu

2016-10-01

Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m-1 K-1, which was 72.3% higher than that (3.600 W m-1 K-1) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler’s interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite’s use as an engineered material.

Scale-up of nature’s tissue weaving algorithms to engineer advanced functional materials

NASA Astrophysics Data System (ADS)

Ng, Joanna L.; Knothe, Lillian E.; Whan, Renee M.; Knothe, Ulf; Tate, Melissa L. Knothe

2017-01-01

We are literally the stuff from which our tissue fabrics and their fibers are woven and spun. The arrangement of collagen, elastin and other structural proteins in space and time embodies our tissues and organs with amazing resilience and multifunctional smart properties. For example, the periosteum, a soft tissue sleeve that envelops all nonarticular bony surfaces of the body, comprises an inherently “smart” material that gives hard bones added strength under high impact loads. Yet a paucity of scalable bottom-up approaches stymies the harnessing of smart tissues’ biological, mechanical and organizational detail to create advanced functional materials. Here, a novel approach is established to scale up the multidimensional fiber patterns of natural soft tissue weaves for rapid prototyping of advanced functional materials. First second harmonic generation and two-photon excitation microscopy is used to map the microscopic three-dimensional (3D) alignment, composition and distribution of the collagen and elastin fibers of periosteum, the soft tissue sheath bounding all nonarticular bone surfaces in our bodies. Then, using engineering rendering software to scale up this natural tissue fabric, as well as multidimensional weaving algorithms, macroscopic tissue prototypes are created using a computer-controlled jacquard loom. The capacity to prototype scaled up architectures of natural fabrics provides a new avenue to create advanced functional materials.

Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment.

PubMed

Galan-Marin, Carmen; Rivera-Gomez, Carlos; Garcia-Martinez, Antonio

2016-06-13

During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy.

Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment

PubMed Central

Galan-Marin, Carmen; Rivera-Gomez, Carlos; Garcia-Martinez, Antonio

2016-01-01

During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy. PMID:28773586

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.

Functional Nanofibers via Electospinning: New Materials and Processes

NASA Astrophysics Data System (ADS)

Manasco, Joshua Lee

Cyclodextrins are fascinating, amphiphilic molecules that are of considerable interest due to their ability to be used in a variety of applications ranging from pharmaceuticals and cosmetics to foods and agriculture. These are ring-shaped sugar molecules possess a hydrophobic cavity and a hydrophilic exterior which imparts them water solubility. There are three main types of naturally occurring cyclodextrins namely alpha-, beta- and gamma- CD which have 6, 7 and 8 member rings, respectively. Owing to their hydrophobic interior, cyclodextrin molecules encapsulate hydrophobic guest molecules (from small to macromolecules) to form host-guest supermolecular structures. Chemically modified CDs are often preferred to the natural forms, particularly methylated (MbetaCD) and hydroxypropylated (HPbetaCD) cyclodextrins, for their enhanced solubility and chemical stability. Electrostatic spinning (electrospinning) of nanofibers has drawn significant research attention in recent decades. This technique involves the stretching of a polymer solution or melt in a high electric field to produce fibers on the nanoscale. These 1-Dimensional nanostructures possess extraordinary surface-to-weight ratio and find applications that vary from filtration membranes and tissue scaffolding materials to drug delivery and many others. The scope of this research attempts to leverage the unique features of CDs with the high aspect ratio of nanofibers to create functional nanomaterials. The present study can be divided into three sections. In the first part, we establish that CDs can be electrospun without the need for a "carrier" polymer. This discovery may serve to extend the horizon of what is currently considered "electrospinnable" from macromolecules now to small molecules. The ability to electrospin CDs led to their incorporation of other polymers to create bicomponent fibers with poly (vinyl alcohol) (PVA) and polyacrylonitrile (PAN). In the case of PVA we demonstrate the ability to not only to control the fiber properties based on PVA/CD ratio, but also crosslink these fibers to create water resistant fiber mats. Furthermore, the use of these fibers as rapid dissolving membranes for drug delivery is explored. Additionally, CDs are investigated for use as a porogen for PAN and carbon fibers. We find that CDs are particularly good candidates for us as porogens due to their amorphous nature and versatility to be dissolved in various solvent system. By nature, solution electrospinning is a low-throughput, solvent intensive process. In the last part we attempt to alleviate this issue by designing an extrusion based melt electrospinning device. We show that submicron fibers of polycaprolactone are possible through this technique without the use of organic solvents.

Activated Carbon Fibers For Gas Storage

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

Burchell, Timothy D; Contescu, Cristian I; Gallego, Nidia C

The advantages of Activated Carbon Fibers (ACF) over Granular Activated Carbon (GAC) are reviewed and their relationship to ACF structure and texture are discussed. These advantages make ACF very attractive for gas storage applications. Both adsorbed natural gas (ANG) and hydrogen gas adsorption performance are discussed. The predicted and actual structure and performance of lignin-derived ACF is reviewed. The manufacture and performance of ACF derived monolith for potential automotive natural gas (NG) storage applications is reported Future trends for ACF for gas storage are considered to be positive. The recent improvements in NG extraction coupled with the widespread availability ofmore » NG wells means a relatively inexpensive and abundant NG supply in the foreseeable future. This has rekindled interest in NG powered vehicles. The advantages and benefit of ANG compared to compressed NG offer the promise of accelerated use of ANG as a commuter vehicle fuel. It is to be hoped the current cost hurdle of ACF can be overcome opening ANG applications that take advantage of the favorable properties of ACF versus GAC. Lastly, suggestions are made regarding the direction of future work.« less

Timoshenko beam model for chiral materials

NASA Astrophysics Data System (ADS)

Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

2017-12-01

Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

Timoshenko beam model for chiral materials

NASA Astrophysics Data System (ADS)

Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

2018-06-01

Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

Chain Confinement in Electrospun Nanocomposites: using Thermal Analysis to Investigate Polymer-Filler Interactions

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

Q Ma; B Mao; P Cebe

2011-12-31

We investigate the interaction of the polymer matrix and filler in electrospun nanofibers using advanced thermal analysis methods. In particular, we study the ability of silicon dioxide nanoparticles to affect the phase structure of poly(ethylene terephthalate), PET. SiO{sub 2} nanoparticles (either unmodified or modified with silane) ranging from 0 to 2.0 wt% in PET were electrospun from hexafluoro-2-propanol solutions. The morphologies of both the electrospun (ES) nanofibers and the SiO{sub 2} powders were observed by scanning and transmission electron microscopy, while the amorphous or crystalline nature of the fibers was determined by real-time wide-angle X-ray scattering. The fractions of themore » crystal, mobile amorphous, and rigid amorphous phases of the non-woven, nanofibrous composite mats were quantified by using heat capacity measurements. The amount of the immobilized polymer layer, the rigid amorphous fraction, was obtained from the specific reversing heat capacity for both as-spun amorphous fibers and isothermally crystallized fibers. Existence of the rigid amorphous phase in the absence of crystallinity was verified in nanocomposite fibers, and two origins for confinement of the rigid amorphous fraction are proposed. Thermal analysis of electrospun fibers, including quasi-isothermal methods, provides new insights to quantitatively characterize the polymer matrix phase structure and thermal transitions, such as devitrification of the rigid amorphous fraction.« less

A microfabricated gecko-inspired controllable and reusable dry adhesive

NASA Astrophysics Data System (ADS)

Chary, Sathya; Tamelier, John; Turner, Kimberly

2013-02-01

Geckos utilize a robust reversible adhesive to repeatedly attach and detach from a variety of vertical and inverted surfaces, using structurally anisotropic micro- and nano-scale fibrillar structures. These fibers, when suitably articulated, are able to control the real area of contact and thereby generate high-to-low van der Waals forces. Key characteristics of the natural system include highly anisotropic adhesion and shear forces for controllable attachment, a high adhesion to initial preload force ratio (μ‧) of 8-16, lack of inter-fiber self-adhesion, and operation over more than 30 000 cycles without loss of adhesion performance. A highly reusable synthetic adhesive has been developed using tilted polydimethylsiloxane (PDMS) half-cylinder micron-scale fibers, retaining up to 77% of the initial value over 10 000 repeated test cycles against a flat glass puck. In comparison with other gecko-inspired adhesives tested over 10 000 cycles or more thus far, this paper reports the highest value of μ‧, along with a large shear force of ˜78 kPa, approaching the 88-226 kPa range of gecko toes. The anisotropic adhesion forces are close to theoretical estimates from the Kendall peel model, quantitatively showing how lateral shearing articulation in a manner similar to the gecko may be used to obtain adhesion anisotropy with synthetic fibers using a combination of tilt angle and anisotropic fiber geometry.

Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

NASA Technical Reports Server (NTRS)

Cox, Sarah; Lui, Donovan; Gou, Jihua

2014-01-01

The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed, to be cured, and be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000degC. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200degC, -SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Testing for this included thermal and mechanical testing per ASTM standard tests.

Enhanced Brain Connectivity in Long-term Meditation Practitioners

PubMed Central

Luders, Eileen; Clark, Kristi; Narr, Katherine L.; Toga, Arthur W.

2011-01-01

Very little is currently known about the cerebral characteristics that underlie the complex processes of meditation as only a limited number of studies have addressed this topic. Research exploring structural connectivity in meditation practitioners is particularly rare. We thus acquired diffusion tensor imaging (DTI) data of high angular and spatial resolution and used atlas-based tract mapping methods to investigate white matter fiber characteristics in a well-matched sample of long-term meditators and controls (n=54). A broad field mapping approach estimated the fractional anisotropy (FA) for twenty different fiber tracts (i.e., nine tracts in each hemisphere and two inter-hemispheric tracts) that were subsequently used as dependent measures. Results showed pronounced structural connectivity in meditators compared to controls throughout the entire brain within major projection pathways, commissural pathways, and association pathways. The largest group differences were observed within the corticospinal tract, the temporal component of the superior longitudinal fasciculus, and the uncinate fasciculus. While cross-sectional studies represent a good starting point for elucidating possible links between meditation and white matter fiber characteristics, longitudinal studies will be necessary to determine the relative contribution of nature and nurture to enhanced structural connectivity in long-term meditators. PMID:21664467

Biodegradable/Compostable Composites From Ligno-Cellulosic Fibers

USDA-ARS?s Scientific Manuscript database

The increased importance of renewable resources for raw materials and recyclabi1ity/biodegradability of the product at the end of the useful life are demanding a shift from petroleum-based synthetics to agro-based natural fibers in automotive interiors. Natural fiber composites can contribute greatl...

Effect of fibre treatments on tensile properties of ethylene vinyl acetate/natural rubber/mengkuang leaf fibre (EVA/NR/MLF) thermoplastic elastomer composites

NASA Astrophysics Data System (ADS)

Hashim, Faiezah; Ismail, Hanafi; Rusli, Arjulizan

2017-07-01

Nowadays, a great attention has been dedicated to natural fibers as reinforcement for polymer composites. Natural fibers, compared to glass fibers, exhibit better mechanical properties, such as stiffness, impact strength, flexibility and modulus. However, certain drawbacks, such as the incompatibility between fibers and polymer matrices, the tendency to form aggregates during processing and the poor resistance to moisture, reduce the use of these natural fibers as reinforcements in polymers. Several treatments and modifications are being used to improve the adhesion between fibre and matrix. In this work, the effect of bleaching treatments using hydrogen peroxide in the Mengkuang leaf fibre (MLF) was evaluated on tensile properties of Ethylene Vinyl Acetate (EVA)/Natural Rubber (NR)/MLF composites. Treated MLF were mixed with the EVA/NR blend in Haake internal mixer at 120 °C and rotor speed of 50 rpm for 10 minutes. Fibre morphology and the fibre/matrix interface ware further characterized by scanning electron microscopy (SEM). The tensile strength was increased by about 8% as compared to the composites with untreated fibers. The increased adhesion between fiber and matrix was also observed by SEM. Thus, EVA/NR/MLF composites reinforced with the treated fibres exhibited better tensile properties than untreated EVA/NR/MLF composites.

Method of making a continuous ceramic fiber composite hot gas filter

DOEpatents

Hill, Charles A.; Wagner, Richard A.; Komoroski, Ronald G.; Gunter, Greg A.; Barringer, Eric A.; Goettler, Richard W.

1999-01-01

A ceramic fiber composite structure particularly suitable for use as a hot gas cleanup ceramic fiber composite filter and method of making same from ceramic composite material has a structure which provides for increased strength and toughness in high temperature environments. The ceramic fiber composite structure or filter is made by a process in which a continuous ceramic fiber is intimately surrounded by discontinuous chopped ceramic fibers during manufacture to produce a ceramic fiber composite preform which is then bonded using various ceramic binders. The ceramic fiber composite preform is then fired to create a bond phase at the fiber contact points. Parameters such as fiber tension, spacing, and the relative proportions of the continuous ceramic fiber and chopped ceramic fibers can be varied as the continuous ceramic fiber and chopped ceramic fiber are simultaneously formed on the porous vacuum mandrel to obtain a desired distribution of the continuous ceramic fiber and the chopped ceramic fiber in the ceramic fiber composite structure or filter.

Cotton fiber cell walls of Gossypium hirsutum and Gossypium barbadense have differences related to loosely-bound xyloglucan.

PubMed

Avci, Utku; Pattathil, Sivakumar; Singh, Bir; Brown, Virginia L; Hahn, Michael G; Haigler, Candace H

2013-01-01

Cotton fiber is an important natural textile fiber due to its exceptional length and thickness. These properties arise largely through primary and secondary cell wall synthesis. The cotton fiber of commerce is a cellulosic secondary wall surrounded by a thin cuticulated primary wall, but there were only sparse details available about the polysaccharides in the fiber cell wall of any cotton species. In addition, Gossypium hirsutum (Gh) fiber was known to have an adhesive cotton fiber middle lamella (CFML) that joins adjacent fibers into tissue-like bundles, but it was unknown whether a CFML existed in other commercially important cotton fibers. We compared the cell wall chemistry over the time course of fiber development in Gh and Gossypium barbadense (Gb), the two most important commercial cotton species, when plants were grown in parallel in a highly controlled greenhouse. Under these growing conditions, the rate of early fiber elongation and the time of onset of secondary wall deposition were similar in fibers of the two species, but as expected the Gb fiber had a prolonged elongation period and developed higher quality compared to Gh fiber. The Gb fibers had a CFML, but it was not directly required for fiber elongation because Gb fiber continued to elongate rapidly after CFML hydrolysis. For both species, fiber at seven ages was extracted with four increasingly strong solvents, followed by analysis of cell wall matrix polysaccharide epitopes using antibody-based Glycome Profiling. Together with immunohistochemistry of fiber cross-sections, the data show that the CFML of Gb fiber contained lower levels of xyloglucan compared to Gh fiber. Xyloglucan endo-hydrolase activity was also higher in Gb fiber. In general, the data provide a rich picture of the similarities and differences in the cell wall structure of the two most important commercial cotton species.

Improvement of Characteristics of Clayey Soil Mixed with Randomly Distributed Natural Fibers

NASA Astrophysics Data System (ADS)

Maity, J.; Chattopadhyay, B. C.; Mukherjee, S. P.

2017-11-01

In subgrade construction for flexible road pavement, properties of clayey soils available locally can be improved by providing randomly distributed fibers in the soil. The fibers added in subgrade constructions are expected to provide better compact interlocking system between the fiber and the soil grain, greater resistance to deformation and quicker dissipation of pore water pressure, thus helping consolidation and strengthening. Many natural fibers like jute, coir, sabai grass etc. which are economical and eco-friendly, are grown in abundance in India. If suitable they can be used as additive material in the subgrade soil to result in increase in strength and decrease in deformability. Such application will also reduce the cost of construction of roads, by providing lesser thickness of pavement layer. In this paper, the efficacy of using natural jute, coir or sabai grass fibers with locally available clayey soil has been studied. A series of Standard Proctor test, Soaked and Unsoaked California Bearing Ratio (CBR) test, and Unconfined Compressive Strength test were done on locally available clayey soil mixed with different types of natural fiber for various length and proportion to study the improvement of strength properties of fiber-soil composites placed at optimum moisture content. From the test results, it was observed that there was a substantial increase in CBR value for the clayey soil when mixed with increasing percentage of all three types of randomly distributed natural fibers up to 2% of the dry weight of soil. The CBR attains maximum value when the length for all types of fibers mixed with the clay taken in this study, attains a value of 10 mm.

Fiber reinforced engineering plastics

Treesearch

Daniel F. Caulfield; Rodney E. Jacobson; Karl D. Sears; John H. Underwood

2001-01-01

Although natural fiber reinforced commodity thermoplastics have a wide range of nonstructural applications in the automotive and decking industries, there have been few reports of cellulosic fiber-reinforced engineering thermoplastics. The commonly held belief has been that the only thermoplastics amenable to natural-fibre reinforcement are limited to low-melting (...

Structural Health Monitoring of Composite Wound Pressure Vessels

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kaul, Raj; Taylor, Scott; Jackson, Kurt; Myers, George; Sharma, A.

2002-01-01

The increasing use of advanced composite materials in the wide range of applications including Space Structures is a great impetus to the development of smart materials. Incorporating these FBG sensors for monitoring the integrity of structures during their life cycle will provide valuable information about viability of the usage of such material. The use of these sensors by surface bonding or embedding in this composite will measure internal strain and temperature, and hence the integrity of the assembled engineering structures. This paper focuses on such a structure, called a composite wound pressure vessel. This vessel was fabricated from the composite material: TRH50 (a Mitsubishi carbon fiber with a 710-ksi tensile strength and a 37 Msi modulus) impregnated with an epoxy resin from NEWPORT composites (WDE-3D-1). This epoxy resin in water dispersed system without any solvents and it cures in the 240-310 degrees F range. This is a toughened resin system specifically designed for pressure applications. These materials are a natural fit for fiber sensors since the polyimide outer buffer coating of fiber can be integrated into the polymer matrix of the composite material with negligible residual stress. The tank was wound with two helical patterns and 4 hoop wraps. The order of winding is: two hoops, two helical and two hoops. The wall thickness of the composite should be about 80 mil or less. The tank should burst near 3,000 psi or less. We can measure the actual wall thickness by ultrasonic or we can burst the tank and measure the pieces. Figure 1 shows a cylinder fabricated out of carbon-epoxy composite material. The strain in different directions is measured with a surface bonded fiber Bragg gratings and with embedded fiber Bragg gratings as the cylinder is pressurized to burst pressures. Figure 2 shows the strain as a function of pressure of carbon-epoxy cylinder as it is pressurized with water. Strain is measured in different directions by multiple gratings oriented in both axial and hoops directions.

Preliminary Design and Experimental Investigation of a Novel Pneumatic Conveying Method to Disperse Natural Fibers in Thermoset Polymers

PubMed Central

Fahimian, Mahi; Kortschot, Mark; Sain, Mohini

2016-01-01

Natural fibers can be attractive reinforcing materials in thermosetting polymers due to their low density and high specific mechanical properties. Although the research effort in this area has grown substantially over the last 20 years, manufacturing technologies to make use of short natural fibers in high volume fraction composites; are still limited. Natural fibers, after retting and preprocessing, are discontinuous and easily form entangled bundles. Dispersion and mixing these short fibers with resin to manufacture high quality, high volume fraction composites presents a significant challenge. In this paper, a novel pneumatic design for dispersion of natural fibers in their original discontinuous form is described. In this design, compressed air is used to create vacuum to feed and convey fibres while breaking down fibre clumps and dispersing them in an aerosolized resin stream. Model composite materials, made using proof-of-concept prototype equipment, were imaged with both optical and X-ray tomography to evaluate fibre and resin dispersion. The images indicated that the system was capable of providing an intimate mixture of resin and detangled fibres for two different resin viscosities. The new pneumatic process could serve as the basis of a system to produce well-dispersed high-volume fraction composites containing discontinuous natural fibres drawn directly from a loosely packed source. PMID:28773670

Studies of Water Absorption Behavior of Plant Fibers at Different Temperatures

NASA Astrophysics Data System (ADS)

Saikia, Dip

2010-05-01

Moisture absorption of natural fiber plastic composites is one major concern in their outdoor applications. The absorbed moisture has many detrimental effects on the mechanical performance of these composites. A knowledge of the moisture diffusivity, permeability, and solubility is very much essential for the application of natural fibers as an excellent reinforcement in polymers. An effort has been made to study the water absorption behavior of some natural fibers such as bowstring hemp, okra, and betel nut at different temperatures to improve the long-term performance of composites reinforced with these fibers. The gain in moisture content in the fibers due to water absorption was measured as a function of exposure time at temperatures ranging from 300 K to 340 K. The thermodynamic parameters of the sorption process, such as diffusion coefficients and corresponding activation energies, were estimated.

Characterization of fiber-forming peptides and proteins by means of atomic force microscopy.

PubMed

Creasey, Rhiannon G; Gibson, Christopher T; Voelcker, Nicolas H

2012-05-01

The atomic force microscope (AFM) is widely used in biological sciences due to its ability to perform imaging experiments at high resolution in a physiological environment, without special sample preparation such as fixation or staining. AFM is unique, in that it allows single molecule information of mechanical properties and molecular recognition to be gathered. This review sets out to identify methodological applications of AFM for characterization of fiber-forming proteins and peptides. The basics of AFM operation are detailed, with in-depth information for any life scientist to get a grasp on AFM capabilities. It also briefly describes antibody recognition imaging and mapping of nanomechanical properties on biological samples. Subsequently, examples of AFM application to fiber-forming natural proteins, and fiber-forming synthetic peptides are given. Here, AFM is used primarily for structural characterization of fibers in combination with other techniques, such as circular dichroism and fluorescence spectroscopy. More recent developments in antibody recognition imaging to identify constituents of protein fibers formed in human disease are explored. This review, as a whole, seeks to encourage the life scientists dealing with protein aggregation phenomena to consider AFM as a part of their research toolkit, by highlighting the manifold capabilities of this technique.

Fugitive methane leak detection using mid-infrared hollow-core photonic crystal fiber containing ultrafast laser drilled side-holes

NASA Astrophysics Data System (ADS)

Karp, Jason; Challener, William; Kasten, Matthias; Choudhury, Niloy; Palit, Sabarni; Pickrell, Gary; Homa, Daniel; Floyd, Adam; Cheng, Yujie; Yu, Fei; Knight, Jonathan

2016-05-01

The increase in domestic natural gas production has brought attention to the environmental impacts of persistent gas leakages. The desire to identify fugitive gas emission, specifically for methane, presents new sensing challenges within the production and distribution supply chain. A spectroscopic gas sensing solution would ideally combine a long optical path length for high sensitivity and distributed detection over large areas. Specialty micro-structured fiber with a hollow core can exhibit a relatively low attenuation at mid-infrared wavelengths where methane has strong absorption lines. Methane diffusion into the hollow core is enabled by machining side-holes along the fiber length through ultrafast laser drilling methods. The complete system provides hundreds of meters of optical path for routing along well pads and pipelines while being interrogated by a single laser and detector. This work will present transmission and methane detection capabilities of mid-infrared photonic crystal fibers. Side-hole drilling techniques for methane diffusion will be highlighted as a means to convert hollow-core fibers into applicable gas sensors.

A specialized outer layer of the primary cell wall joins elongating cotton fibers into tissue-like bundles.

PubMed

Singh, Bir; Avci, Utku; Eichler Inwood, Sarah E; Grimson, Mark J; Landgraf, Jeff; Mohnen, Debra; Sørensen, Iben; Wilkerson, Curtis G; Willats, William G T; Haigler, Candace H

2009-06-01

Cotton (Gossypium hirsutum) provides the world's dominant renewable textile fiber, and cotton fiber is valued as a research model because of its extensive elongation and secondary wall thickening. Previously, it was assumed that fibers elongated as individual cells. In contrast, observation by cryo-field emission-scanning electron microscopy of cotton fibers developing in situ within the boll demonstrated that fibers elongate within tissue-like bundles. These bundles were entrained by twisting fiber tips and consolidated by adhesion of a cotton fiber middle lamella (CFML). The fiber bundles consolidated via the CFML ultimately formed a packet of fiber around each seed, which helps explain how thousands of cotton fibers achieve their great length within a confined space. The cell wall nature of the CFML was characterized using transmission electron microscopy, including polymer epitope labeling. Toward the end of elongation, up-regulation occurred in gene expression and enzyme activities related to cell wall hydrolysis, and targeted breakdown of the CFML restored fiber individuality. At the same time, losses occurred in certain cell wall polymer epitopes (as revealed by comprehensive microarray polymer profiling) and sugars within noncellulosic matrix components (as revealed by gas chromatography-mass spectrometry analysis of derivatized neutral and acidic glycosyl residues). Broadly, these data show that adhesion modulated by an outer layer of the primary wall can coordinate the extensive growth of a large group of cells and illustrate dynamic changes in primary wall structure and composition occurring during the differentiation of one cell type that spends only part of its life as a tissue.

Cellulose-Based Biomimetics and Their Applications.

PubMed

Almeida, Ana P C; Canejo, João P; Fernandes, Susete N; Echeverria, Coro; Almeida, Pedro L; Godinho, Maria H

2018-05-01

Nature has been producing cellulose since long before man walked the surface of the earth. Millions of years of natural design and testing have resulted in cellulose-based structures that are an inspiration for the production of synthetic materials based on cellulose with properties that can mimic natural designs, functions, and properties. Here, five sections describe cellulose-based materials with characteristics that are inspired by gratings that exist on the petals of the plants, structurally colored materials, helical filaments produced by plants, water-responsive materials in plants, and environmental stimuli-responsive tissues found in insects and plants. The synthetic cellulose-based materials described herein are in the form of fibers and films. Fascinating multifunctional materials are prepared from cellulose-based liquid crystals and from composite cellulosic materials that combine functionality with structural performance. Future and recent applications are outlined. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity

PubMed Central

Xia, Changlei; Garcia, Andres C.; Shi, Sheldon Q.; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R.; D’Souza, Nandika A.; Nie, Xu

2016-01-01

Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m−1 K−1, which was 72.3% higher than that (3.600 W m−1 K−1) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler’s interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite’s use as an engineered material. PMID:27703226

Interfacial contributions in lignocellulosic fiber-reinforced polyurethane composites

Treesearch

Timothy G. Rials; Michael P. Wolcott; John M. Nassar

2001-01-01

Whereas lignocellulosic fibers have received considerable attention as a rein- forcing agent in thermoplastic composites, their applicability to reactive polymer systems remains of considerable interest. The hydroxyl-rich nature of natural lignocellulosic fibers suggests that they are particularly useful in thermosetting systems such as polyurethanes. To further this...

Accelerated weathering of natural fiber-filled polyethylene composites

Treesearch

Thomas Lundin; Steven M. Cramer; Robert H. Falk; Colin Felton

2004-01-01

The resistance of natural fiber-filled high-density polyethylene composite specimens to ultraviolet- (UV) and moisture-induced degradation was evaluated by measuring changes to flexural properties. High-density polyethylene (HDPE) served as the polymer matrix for four formulations: two formulations without fiber filler and two formulations one containing wood flour and...

Correlation between polarization sensitive optical coherence tomography and SHG microscopy in articular cartilage

NASA Astrophysics Data System (ADS)

Zhou, Xin; Ju, Myeong Jin; Huang, Lin; Tang, Shuo

2017-02-01

Polarization-sensitive optical coherence tomography (PS-OCT) and second harmonic generation (SHG) microscopy are two imaging modalities with different resolutions, field-of-views (FOV), and contrasts, while they both have the capability of imaging collagen fibers in biological tissues. PS-OCT can measure the tissue birefringence which is induced by highly organized fibers while SHG can image the collagen fiber organization with high resolution. Articular cartilage, with abundant structural collagen fibers, is a suitable sample to study the correlation between PS-OCT and SHG microscopy. Qualitative conjecture has been made that the phase retardation measured by PS-OCT is affected by the relationship between the collagen fiber orientation and the illumination direction. Anatomical studies show that the multilayered architecture of articular cartilage can be divided into four zones from its natural surface to the subchondral bone: the superficial zone, the middle zone, the deep zone, and the calcified zone. The different zones have different collagen fiber orientations, which can be studied by the different slopes in the cumulative phase retardation in PS-OCT. An algorithm is developed based on the quantitative analysis of PS-OCT phase retardation images to analyze the microstructural features in swine articular cartilage tissues. This algorithm utilizes the depth-dependent slope changing of phase retardation A-lines to segment structural layers. The results show good consistency with the knowledge of cartilage morphology and correlation with the SHG images measured at selected depth locations. The correlation between PS-OCT and SHG microscopy shows that PS-OCT has the potential to analyze both the macro and micro characteristics of biological tissues with abundant collagen fibers and other materials that may cause birefringence.

The effect of woven and non-woven fiber structure on mechanical properties polyester composite reinforced kenaf

NASA Astrophysics Data System (ADS)

Ratim, S.; Bonnia, N. N.; Surip, S. N.

2012-07-01

The effects of woven and non-woven kenaf fiber on mechanical properties of polyester composites were studied at different types of perform structures. Composite polyester reinforced kenaf fiber has been prepared via hand lay-up process by varying fiber forms into plain weave, twill and mats structure. The reinforcing efficiency of different fiber structure was compared with control of unreinforced polyester sample. It was found that the strength and stiffness of the composites are largely affected by fiber structure. A maximum value for tensile strength of composite was obtained for twill weave pattern of fiber structure while no significant different for plain weave and mat structure. The elastic modulus of composite has shown some improvement on plain and twill weave pattern. Meanwhile, lower value of modulus elasticity achieved by mats structure composite as well as control sample. The modulus of rupture and impact resistance were also analyzed. The improvement of modulus of rupture value can be seen on plain and twill weave pattern. However impact resistance doesn't show significant improvement in all types of structure except for mat fiber. The mechanical properties of kenaf fiber reinforced polyester composite found to be increased with woven and non-woven fiber structures in composite.

Mechanical Property Evaluation of Palm/Glass Sandwiched Fiber Reinforced Polymer Composite in Comparison with few natural composites

NASA Astrophysics Data System (ADS)

Raja Dhas, J. Edwin; Pradeep, P.

2017-10-01

Natural fibers available plenty can be used as reinforcements in development of eco friendly polymer composites. The less utilized palm leaf stalk fibers sandwiched with artificial glass fibers was researched in this work to have a better reinforcement in preparing a green composite. The commercially available polyester resin blend with coconut shell filler in nano form was used as matrix to sandwich these composites. Naturally available Fibers of palm leaf stalk, coconut leaf stalk, raffia and oil palm were extracted and treated with potassium permanganate solution which enhances the properties. For experimentation four different plates were fabricated using these fibers adopting hand lay-up method. These sandwiched composite plates are further machined to obtain ASTM standards Specimens which are mechanically tested as per standards. Experimental results reveal that the alkali treated palm leaf stalk fiber based polymer composite shows appreciable results than the others. Hence the developed composite can be recommended for fabrication of automobile parts.

The picosecond structure of ultra-fast rogue waves

NASA Astrophysics Data System (ADS)

Klein, Avi; Shahal, Shir; Masri, Gilad; Duadi, Hamootal; Sulimani, Kfir; Lib, Ohad; Steinberg, Hadar; Kolpakov, Stanislav A.; Fridman, Moti

2018-02-01

We investigated ultrafast rogue waves in fiber lasers and found three different patterns of rogue waves: single- peaks, twin-peaks, and triple-peaks. The statistics of the different patterns as a function of the pump power of the laser reveals that the probability for all rogue waves patterns increase close to the laser threshold. We developed a numerical model which prove that the ultrafast rogue waves patterns result from both the polarization mode dispersion in the fiber and the non-instantaneous nature of the saturable absorber. This discovery reveals that there are three different types of rogue waves in fiber lasers: slow, fast, and ultrafast, which relate to three different time-scales and are governed by three different sets of equations: the laser rate equations, the nonlinear Schrodinger equation, and the saturable absorber equations, accordingly. This discovery is highly important for analyzing rogue waves and other extreme events in fiber lasers and can lead to realizing types of rogue waves which were not possible so far such as triangular rogue waves.

NDE standards for high temperature materials

NASA Technical Reports Server (NTRS)

Vary, Alex

1991-01-01

High temperature materials include monolithic ceramics for automotive gas turbine engines and also metallic/intermetallic and ceramic matrix composites for a range of aerospace applications. These are materials that can withstand extreme operating temperatures that will prevail in advanced high-efficiency gas turbine engines. High temperature engine components are very likely to consist of complex composite structures with three-dimensionality interwoven and various intermixed ceramic fibers. The thermomechanical properties of components made of these materials are actually created in-place during processing and fabrication stages. The complex nature of these new materials creates strong incentives for exact standards for unambiguous evaluations of defects and microstructural characteristics. NDE techniques and standards that will ultimately be applicable to production and quality control of high temperature materials and structures are still emerging. The needs range from flaw detection to below 100 micron levels in monolithic ceramics to global imaging of fiber architecture and matrix densification anomalies in composites. The needs are different depending on the processing stage, fabrication method, and nature of the finished product. The standards are discussed that must be developed in concert with advances in NDE technology, materials processing research, and fabrication development. High temperature materials and structures that fail to meet stringent specifications and standards are unlikely to compete successfully either technologically or in international markets.

Experimental research on continuous basalt fiber and basalt-fibers-reinforced polymers

NASA Astrophysics Data System (ADS)

Zhang, Xueyi; Zou, Guangping; Shen, Zhiqiang

2008-11-01

The interest for continuous basalt fibers and reinforced polymers has recently grown because of its low price and rich natural resource. Basalt fiber was one type of high performance inorganic fibers which were made from natural basalt by the method of melt extraction. This paper discusses basic mechanical properties of basalt fiber. The other work in this paper was to conduct tensile testing of continuous basalt fiber-reinforced polymer rod. Tensile strength and stress-strain curve were obtained in this testing. The strength of rod was fairly equal to rod of E-glass fibers and weaker than rod of carbon fibers. Surface of crack of rod was studied. An investigation of fracture mechanism between matrix and fiber was analyzed by SEM (Scanning electron microscopy) method. A poor adhesion between the matrix and fibers was also shown for composites analyzing SEM photos. The promising tensile properties of the presented basalt fibers composites have shown their great potential as alternative classical composites.

3D structural panels : a literature review

Treesearch

John F. Hunt

2004-01-01

The world population has surpassed the 6 billion mark and many of these people live in rapidly developing countries that are and will continue to place increasing pressure on the world's natural fiber resources. The total demand for raw material from the forest for housing, packaging, and for office and home furnishings, to name a few; are increasing. Traditional...

3D-QSPR Method of Computational Technique Applied on Red Reactive Dyes by Using CoMFA Strategy

PubMed Central

Mahmood, Uzma; Rashid, Sitara; Ali, S. Ishrat; Parveen, Rasheeda; Zaheer-ul-Haq; Ambreen, Nida; Khan, Khalid Mohammed; Perveen, Shahnaz; Voelter, Wolfgang

2011-01-01

Cellulose fiber is a tremendous natural resource that has broad application in various productions including the textile industry. The dyes, which are commonly used for cellulose printing, are “reactive dyes” because of their high wet fastness and brilliant colors. The interaction of various dyes with the cellulose fiber depends upon the physiochemical properties that are governed by specific features of the dye molecule. The binding pattern of the reactive dye with cellulose fiber is called the ligand-receptor concept. In the current study, the three dimensional quantitative structure property relationship (3D-QSPR) technique was applied to understand the red reactive dyes interactions with the cellulose by the Comparative Molecular Field Analysis (CoMFA) method. This method was successfully utilized to predict a reliable model. The predicted model gives satisfactory statistical results and in the light of these, it was further analyzed. Additionally, the graphical outcomes (contour maps) help us to understand the modification pattern and to correlate the structural changes with respect to the absorptivity. Furthermore, the final selected model has potential to assist in understanding the charachteristics of the external test set. The study could be helpful to design new reactive dyes with better affinity and selectivity for the cellulose fiber. PMID:22272108

Acid leaching of natural chrysotile asbestos to mesoporous silica fibers

NASA Astrophysics Data System (ADS)

Maletaškić, Jelena; Stanković, Nadežda; Daneu, Nina; Babić, Biljana; Stoiljković, Milovan; Yoshida, Katsumi; Matović, Branko

2018-04-01

Nanofibrous silica with a high surface area was produced from chrysotile by the acid-leaching method. Natural mineral chrysotile asbestos from Stragari, Korlace in Serbia was used as the starting material. The fibers were modified by chemical treatment with 1 M HCl and the mineral dissolution was monitored by transmission electron microscopy, X-ray powder diffraction, inductively coupled plasma spectrometry and low-temperature nitrogen adsorption techniques to highlight the effects of the leaching process. The results showed that the applied concentration of acid solution and processing time of 4 h were sufficient to effectively remove the magnesium hydroxide layer and transform the crystal structure of the hazardous starting chrysotile to porous SiO2 nanofibers. With prolonged acid leaching, the specific surface area, S BET, calculated by BET equation, was increased from 147 up to 435 m2 g- 1, with micropores representing a significant part of the specific surface.

Relationship between Fiber Furnish and the Structural Performance of MDF

Treesearch

Leslie H. Groom; Laurence Mott; Stephen Shaler

1999-01-01

The structural performance of medium density fiberboard (MDF) is attributable to three primary variables which are: physical and mechanical properties of individual wood fibers; fiber-to-fiber stress transfer; and fiber orientation. These origins of fiber properties and stress transfer can be traced to the fiber generation method wherein fiber orientation is associated...

Overhauser shift and dynamic nuclear polarization on carbon fibers

NASA Astrophysics Data System (ADS)

Herb, Konstantin; Denninger, Gert

2018-06-01

We report on the first experimental magnetic resonance determination of the coupling between electrons and nuclear spins (1H, 13C) in carbon fibers. Our results strongly support the assumption that the electronic spins are delocalized on graphene like structures in the fiber. The coupling between these electrons and the nuclei of the lattice results in dynamic nuclear polarization of the nuclei (DNP), enabling very sensitive NMR experiments on these nuclear spins. For possible applications of graphene in spintronics devices the coupling between nuclei and electrons is essential. We were able to determine the interactions down to 30 × 10-9(30 ppb) . We were even able to detect the coupling of the electrons to 13C (in natural abundance). These experiments open the way for a range of new double resonance investigations with possible applications in the field of material science.

Physical and combustion properties of nonwoven fabrics produced from conventional and naturally colored cottons

USDA-ARS?s Scientific Manuscript database

A comparative study was conducted to identify the effects of processing parameters on physical and combustion properties of needlepunched (NP) and hydroentangled (H-E) nonwoven fabrics produced from fibers of a standard Mid-South white fiber cotton and a naturally colored brown fiber cotton. The fl...

The hygroscopic behavior of plant fibers: a review.

PubMed

Célino, Amandine; Fréour, Sylvain; Jacquemin, Frédéric; Casari, Pascal

2013-01-01

Environmental concern has resulted in a renewed interest in bio-based materials. Among them, plant fibers are perceived as an environmentally friendly substitute to glass fibers for the reinforcement of composites, particularly in automotive engineering. Due to their wide availability, low cost, low density, high-specific mechanical properties, and eco-friendly image, they are increasingly being employed as reinforcements in polymer matrix composites. Indeed, their complex microstructure as a composite material makes plant fiber a really interesting and challenging subject to study. Research subjects about such fibers are abundant because there are always some issues to prevent their use at large scale (poor adhesion, variability, low thermal resistance, hydrophilic behavior). The choice of natural fibers rather than glass fibers as filler yields a change of the final properties of the composite. One of the most relevant differences between the two kinds of fiber is their response to humidity. Actually, glass fibers are considered as hydrophobic whereas plant fibers have a pronounced hydrophilic behavior. Composite materials are often submitted to variable climatic conditions during their lifetime, including unsteady hygroscopic conditions. However, in humid conditions, strong hydrophilic behavior of such reinforcing fibers leads to high level of moisture absorption in wet environments. This results in the structural modification of the fibers and an evolution of their mechanical properties together with the composites in which they are fitted in. Thereby, the understanding of these moisture absorption mechanisms as well as the influence of water on the final properties of these fibers and their composites is of great interest to get a better control of such new biomaterials. This is the topic of this review paper.

The hygroscopic behavior of plant fibers: a review

PubMed Central

Célino, Amandine; Fréour, Sylvain; Jacquemin, Frédéric; Casari, Pascal

2013-01-01

Environmental concern has resulted in a renewed interest in bio-based materials. Among them, plant fibers are perceived as an environmentally friendly substitute to glass fibers for the reinforcement of composites, particularly in automotive engineering. Due to their wide availability, low cost, low density, high-specific mechanical properties, and eco-friendly image, they are increasingly being employed as reinforcements in polymer matrix composites. Indeed, their complex microstructure as a composite material makes plant fiber a really interesting and challenging subject to study. Research subjects about such fibers are abundant because there are always some issues to prevent their use at large scale (poor adhesion, variability, low thermal resistance, hydrophilic behavior). The choice of natural fibers rather than glass fibers as filler yields a change of the final properties of the composite. One of the most relevant differences between the two kinds of fiber is their response to humidity. Actually, glass fibers are considered as hydrophobic whereas plant fibers have a pronounced hydrophilic behavior. Composite materials are often submitted to variable climatic conditions during their lifetime, including unsteady hygroscopic conditions. However, in humid conditions, strong hydrophilic behavior of such reinforcing fibers leads to high level of moisture absorption in wet environments. This results in the structural modification of the fibers and an evolution of their mechanical properties together with the composites in which they are fitted in. Thereby, the understanding of these moisture absorption mechanisms as well as the influence of water on the final properties of these fibers and their composites is of great interest to get a better control of such new biomaterials. This is the topic of this review paper. PMID:24790971

Carbon-based torsional and tensile artificial muscles driven by thermal expansion (presentation video)

NASA Astrophysics Data System (ADS)

Haines, Carter S.; Lima, Márcio D.; Li, Na; Spinks, Geoffrey M.; Foroughi, Javad; Madden, John D. W.; Kim, Shi-Hyeong; Fang, Shaoli; Jung de Andrade, Monica; Göktepe, Fatma; Göktepe, Ozer; Mirvakili, Seyed M.; Naficy, Sina; Lepró, Xavier; Oh, Jiyoung; Kozlov, Mikhail E.; Kim, Seon Jeong; Xu, Xiuru; Swedlove, Benjamin J.; Wallace, Gordon G.; Baughman, Ray H.

2014-03-01

High-performance artificial muscles have been produced from fibers having highly anisotropic thermal expansion. Inserting twist into these precursor fibers enables thermally-driven torsional actuation and can cause the formation of helical coils. Such coiled structures provide giant-stroke tensile actuation exceeding the 20% in-vivo contraction of natural muscles. This contraction is highly reversible, with over one million cycles demonstrated, and can occur without the hysteresis that plagues competing shape-memory and piezoelectric muscles. Several materials and composites are investigated, including low-cost, commercially-available muscle precursors, potentially facilitating thermally-responsive textiles that change porosity to provide wearer comfort.

Investigating the energy harvesting capabilities of a hybrid ZnO nanowires/carbon fiber polymer composite beam.

PubMed

Masghouni, N; Burton, J; Philen, M K; Al-Haik, M

2015-03-06

Hybrid piezoelectric composite structures that are able to convert mechanical energy into electricity have gained growing attention in the past few years. In this work, an energy harvesting composite beam is developed by growing piezoelectric zinc oxide nanowires on the surface of carbon fiber prior to forming structural composites. The piezoelectric behavior of the composite beam was demonstrated under different vibration sources such as water bath sonicator and permanent magnet vibration shaker. The beam was excited at its fundamental natural frequency (43.2 Hz) and the open circuit voltage and the short circuit current were measured to be 3.1 mV and 23 nA, respectively. Upon connecting an optimal resistor (1.2 kΩ) in series with the beam a maximum power output 2.5 nW was achieved.

SU-F-T-166: On the Nature of the Background Visible Light Observed in Fiber Optic Dosimetry of Proton Beams

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

Darafsheh, A; Kassaee, A; Finlay, J

Purpose: The nature of the background visible light observed during fiber optic dosimetry of proton beams, whether it is due to Cherenkov radiation or not, has been debated in the literature recently. In this work, experimentally and by means of Monte Carlo simulations, we shed light on this problem and investigated the nature of the background visible light observed in fiber optics irradiated with proton beams. Methods: A bare silica fiber optics was embedded in tissue-mimicking phantoms and irradiated with clinical proton beams with energies of 100–225 MeV at Roberts Proton Therapy Center. Luminescence spectroscopy was performed by a CCD-coupledmore » spectrograph to analyze in detail the emission spectrum of the fiber tip across the visible range of 400–700 nm. Monte Carlo simulation was performed by using FLUKA Monte Carlo code to simulate Cherenkov light and ionizing radiation dose deposition in the fiber. Results: The experimental spectra of the irradiated silica fiber shows two distinct peaks at 450 and 650 nm, whose spectral shape is different from that of Cherenkov radiation. We believe that the nature of these peaks are connected to the point defects of silica including oxygen-deficiency center (ODC) and non-bridging oxygen hole center (NBOHC). Monte Carlo simulations confirmed the experimental observations that Cherenkov radiation cannot be solely responsible for such a signal. Conclusion: We showed that Cherenkov radiation is not the dominant visible signal observed in bare fiber optics irradiated with proton beams. We observed two distinct peaks at 450 and 650 nm whose nature is connected with the point defects of silica fiber including oxygen-deficiency center and non-bridging oxygen hole center.« less

Microscopic mechanism of amino silicone oil modification and modification effect with different amino group contents based on molecular dynamics simulation

NASA Astrophysics Data System (ADS)

He, Liping; Li, Wenjun; Chen, Dachuan; Yuan, Jianmin; Lu, Gang; Zhou, Dianwu

2018-05-01

The microscopic mechanism of amino silicone oil (ASO) modification of natural fiber was investigated for the first time using molecular dynamics (MD) simulation at the atomic and molecular levels. The MD simulation results indicated that the ASO molecular interacted with the cellulose molecular within the natural fiber, mainly by intermolecular forces of Nsbnd Hsbnd O and Osbnd Hsbnd N hydrogen bonds and the molecular chain of ASO absorbed onto the natural fiber in a selective orientation, i.e., the hydrophobic alkyl groups (sbnd CnH2n+1) project outward and the polar amino groups (sbnd NH2) point to the surface of natural fiber. Consequently, the ASO modification changed the surface characteristic of natural fiber from hydrophilic to hydrophobic. Furthermore, the modification effects of the ASO modification layer with different amino group contents (m:n ratio) were also evaluated in this study by calculating the binding energy between the ASO modifier and natural fiber, and the cohesive energy density and free volume of the ASO modification layer. The results showed that the binding energy reached a maximum when the m:n ratio of ASO was of 8:4, suggesting that a good bonding strength was achieved at this m:n ratio. It was also found that the cohesive energy density enhanced with the increase in the amino group content, and the higher the cohesive energy density, the easier the formation of the ASO modification layer. However, the fraction free volume decreased with the increase in the amino group content. This is good for improving the water-proof property of natural fiber. The present work can provide an effective method for predicting the modification effects and designing the optimized m:n ratio of ASO modification.

Hierarchical, multilayered cell walls reinforced by recycled silk cocoons enhance the structural integrity of honeybee combs

PubMed Central

Zhang, Kai; Duan, Huiling; Karihaloo, Bhushan L.; Wang, Jianxiang

2010-01-01

We reveal the sophisticated and hierarchical structure of honeybee combs and measure the elastic properties of fresh and old natural honeycombs at different scales by optical microscope, environmental scanning electron microscope, nano/microindentation, and by tension and shear tests. We demonstrate that the comb walls are continuously strengthened and stiffened without becoming fragile by the addition of thin wax layers reinforced by recycled silk cocoons reminiscent of modern fiber-reinforced composite laminates. This is done to increase its margin of safety against collapse due to a temperature increase. Artificial engineering honeycombs mimic only the macroscopic geometry of natural honeycombs, but have yet to achieve the microstructural sophistication of their natural counterparts. The natural honeycombs serve as a prototype of truly biomimetic cellular materials with hitherto unattainable improvement in stiffness, strength, toughness, and thermal stability. PMID:20439765

Microstructure of the smart composite structures with embedded fiber optic sensing nerves

NASA Astrophysics Data System (ADS)

Liu, Jingyuan; Luo, Fei; Li, Changchun; Ma, Naibin

1997-11-01

The composite structures with embedded optical fiber sensors construct a smart composite structure system, which may have the characteristics of the in-service self-measurement, self- recognition and self-judgement action. In the present work, we studied the microstructures of carbon/epoxy composite laminates with embedded sensing optical fibers, and the integration of optical fiber with composites was also discussed. The preliminary experiment results show that because of the difference between the sensing optical fibers and the reinforcing fibers in their size, the microstructure of the composites with embedded optical fibers will produce partial local changes in the area of embedded optical fiber, these changes may affect the mechanical properties of composite structures. When the optical fibers are embedded parallel to the reinforcing fibers, due to the composite prepregs are formed under a press action during its curing process, the reinforcing fibers can be arranged equably around the optical fibers. But when the optical fibers are embedded perpendicularly to the reinforcement fibers, the resin rich pocket will appear in the composite laminates surrounding the embedded optical fiber. The gas holes will be easily produced in these zones which may produce a premature failure of the composite structure. The photoelastic experiments are also given in the paper.

An experimental study of mechanical behavior of natural fiber reinforced polymer matrix composites

NASA Astrophysics Data System (ADS)

Ratna, Sanatan; Misra, Sheelam

2018-05-01

Fibre-reinforced polymer composites have played a dominant role for a long time in a variety of applications for their high specific strength and modulus. The fibre which serves as a reinforcement in reinforced plastics may be synthetic or natural. Past studies show that only synthetic fibres such as glass, carbon etc., have been used in fibre reinforced plastics. Although glass and other synthetic fibre-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. In this connection, an investigation has been carried out to make use of horse hair, an animal fibre abundantly available in India. Animal fibres are not only strong and lightweight but also relatively very cheaper than mineral fibre. The present work describes the development and characterization of a new set of animal fiber based polymer composites consisting of horse hair as reinforcement and epoxy resin. The newly developed composites are characterized with respect to their mechanical characteristics. Experiments are carried out to study the effect of fibre length on mechanical behavior of these epoxy based polymer composites. Composite made form horse hair can be used as a potential reinforcing material for many structural and non-structural applications. This work can be further extended to study other aspects of such composites like effect of fiber content, loading pattern, fibre treatment on mechanical behavior of horse hair based polymer horse hair.

An SMS (single mode - multi mode - single mode) fiber structure for vibration sensing

NASA Astrophysics Data System (ADS)

Waluyo, T. B.; Bayuwati, D.

2017-04-01

We describe an SMS (single mode - multi mode - single mode) fiber structure to be used in a vibration sensing system. The fiber structure was fabricated by splicing a section (about 300 mm in length) of a step index multi mode fiber between two single mode fibers obtained from a communication grade fiber patchcord. Interference between higher order modes occurs while light from a narrow band light source travels along the multi mode fiber. When the multi mode fiber vibrates, the refractive index profile is changed because of the photo-elastics effect and the amplitude of the interference pattern is changed accordingly. To simulate a vibrating structure we used a loudspeaker to vibrate a wooden table. By using a digital oscilloscope, we recorded and analysed the vibrating signals obtained from the SMS fiber structure as well as from a GS-32CT geophone for referencing. We observed that this SMS fiber structure was potential to be used in a vibration sensing system with a measurement range from 30 to 180 Hz with inherent optical fiber sensor advantages such as light weight, immune to electromagnetic interference, and no electricity in the sensing part.

Fiber-based modeling of in situ ankle ligaments with consideration of progressive failure.

PubMed

Nie, Bingbing; Forman, Jason L; Panzer, Matthew B; Mait, Alexander R; Donlon, John-Paul; Kent, Richard W

2017-08-16

Ligament sprains account for a majority of injuries to the foot and ankle complex among athletic populations. The infeasibility of measuring the in situ response and load paths of individual ligaments has precluded a complete characterization of their mechanical behavior via experiment. In the present study a fiber-based modeling approach of in situ ankle ligaments was developed and validated for determining the heterogeneous force-elongation characteristics and the consequent injury patterns. Nine major ankle ligaments were modeled as bundles of discrete elements, corresponding functionally to the structure of collagen fibers. To incorporate the progressive nature of ligamentous injury, the limit strain at the occurrence of fiber failure was described by a distribution function ranging from 12% to 18% along the width of the insertion site. The model was validated by comparing the structural kinetic and kinematic response obtained experimentally and computationally under well-controlled foot rotations. The simulation results replicated the 6 degree-of-freedom bony motion and ligamentous injuries and, by implication, the in situ deformations of the ligaments. Gross stiffness of the whole ligament derived from the fibers was comparable to existing experimental data. The present modeling approach provides a biomechanically realistic, interpretable and computationally efficient way to characterize the in situ ligament slack, sequential and heterogeneous uncrimping of collagen fascicles and failure propagation as the external load is applied. Applications of this model include functional ankle joint mechanics, injury prevention and countermeasure design for athletes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Accelerated weathering of natural fiber-thermoplastic composites : effects of ultraviolet exposure on bending strength and stiffness

Treesearch

Thomas Lundin; Robert H. Falk; Colin Felton

2002-01-01

Mechanical properties of bending stiffness and yield stress were used to evaluate the effects of ultraviolet exposure on natural fiber-thermoplastic composites. Four different specimen formulations were evaluated. Injection molded high density polyethylene (HDPE) served as the polymer base for all formulations. Two lignocellulosic fillers, wood flour and kenaf fiber,...

Combined electromechanical impedance and fiber optic diagnosis of aerospace structures

NASA Astrophysics Data System (ADS)

Schlavin, Jon; Zagrai, Andrei; Clemens, Rebecca; Black, Richard J.; Costa, Joey; Moslehi, Behzad; Patel, Ronak; Sotoudeh, Vahid; Faridian, Fereydoun

2014-03-01

Electromechanical impedance is a popular diagnostic method for assessing structural conditions at high frequencies. It has been utilized, and shown utility, in aeronautic, space, naval, civil, mechanical, and other types of structures. By contrast, fiber optic sensing initially found its niche in static strain measurement and low frequency structural dynamic testing. Any low frequency limitations of the fiber optic sensing, however, are mainly governed by its hardware elements. As hardware improves, so does the bandwidth (frequency range * number of sensors) provided by the appropriate enabling fiber optic sensor interrogation system. In this contribution we demonstrate simultaneous high frequency measurements using fiber optic and electromechanical impedance structural health monitoring technologies. A laboratory specimen imitating an aircraft wing structure, incorporating surfaces with adjustable boundary conditions, was instrumented with piezoelectric and fiber optic sensors. Experiments were conducted at different structural boundary conditions associated with deterioration of structural health. High frequency dynamic responses were collected at multiple locations on a laboratory wing specimen and conclusions were drawn about correspondence between structural damage and dynamic signatures as well as correlation between electromechanical impedance and fiber optic sensors spectra. Theoretical investigation of the effect of boundary conditions on electromechanical impedance spectra is presented and connection to low frequency structural dynamics is suggested. It is envisioned that acquisition of high frequency structural dynamic responses with multiple fiber optic sensors may open new diagnostic capabilities for fiber optic sensing technologies.

Effect of liquid epoxidized natural rubber (LENR) on mechanical properties and morphology of natural rubber/high density polyethylene/mengkuang fiber (NR/HDPE/MK) bio-composite

NASA Astrophysics Data System (ADS)

Piah, Mohd Razi Mat; Baharum, Azizah

2016-11-01

The use of mengkuang fiber (MK) fibers in NR/HDPE (40/60) blend was studied via surface modification of fiber. The MK fiber was pre-washed with 5%wt/v sodium hydroxide solution prior to treatment with liquid epoxidized natural rubber (LENR). The concentration of LENR were varied from 5%-20%wt in toluene. The effects of LENR concentrations were studied in terms of mechanical properties and morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135°C temperature, 45 rpm rotor speed, 12 minutes processing time and at 20%wt MK fiber loading. The optimum LENR treatment concentration was obtained at 5%wt with tensile strength, tensile modulus, and impact strength of 10.3 MPa, 414.2 MPa and 14.4 kJ/m2 respectively. The tensile modulus of LENR-treated MK fiber filled NR/HDPE bio-composite has shown enhancement up to 16.7% higher than untreated MK fiber. The tensile and impact strength were decreased with increasing LENR concentration due to the broken of MK fibers to smaller particles and adhered to each other. FESEM micrographs confirmed the formation of fiber-fiber agglomeration in NR/HDPE blends. The optical microscope analysis shows MK fibers is shorter than original fiber lengths after NaOH-LENR surface modification. The internal bonding forces of MK fiber seems to be weaker than external force exerted on it, therefore, the MK fiber has broken to smaller particles and reduced the mechanical properties of NR/HDPE/MK(20%) bio-composite.

Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

NASA Technical Reports Server (NTRS)

Cox, Sarah B.; Lui, Donovan; Gou, Jihua

2014-01-01

The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

NASA Technical Reports Server (NTRS)

Cox, Sarah B.; Lui, Donovan; Wang, Xin; Gou, Jihua

2014-01-01

The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000 deg C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200 deg C, Beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

Optimization of Adaptive Intraply Hybrid Fiber Composites with Reliability Considerations

NASA Technical Reports Server (NTRS)

Shiao, Michael C.; Chamis, Christos C.

1994-01-01

The reliability with bounded distribution parameters (mean, standard deviation) was maximized and the reliability-based cost was minimized for adaptive intra-ply hybrid fiber composites by using a probabilistic method. The probabilistic method accounts for all naturally occurring uncertainties including those in constituent material properties, fabrication variables, structure geometry, and control-related parameters. Probabilistic sensitivity factors were computed and used in the optimization procedures. For actuated change in the angle of attack of an airfoil-like composite shell structure with an adaptive torque plate, the reliability was maximized to 0.9999 probability, with constraints on the mean and standard deviation of the actuation material volume ratio (percentage of actuation composite material in a ply) and the actuation strain coefficient. The reliability-based cost was minimized for an airfoil-like composite shell structure with an adaptive skin and a mean actuation material volume ratio as the design parameter. At a O.9-mean actuation material volume ratio, the minimum cost was obtained.

Acoustic transmission and radiation analysis of adaptive shape-memory alloy reinforced laminated plates

NASA Astrophysics Data System (ADS)

Liang, C.; Rogers, C. A.; Fuller, C. R.

1991-02-01

A theoretical analysis of sound transmission/radiation of shape-memory alloy (SMA) hybrid composite panels is presented. Unlike other composite materials, SMA hybrid composite is dynamically tunable by electrical activation of the SMA fibers and has numerous active control capabilities. Two of the concepts that will be briefly described and utilized in this paper are referred to as active property tuning (APT) and active strain energy tuning (ASET). Tuning or activating the embedded shape-memory alloy fibers in conventional composite materials changes the overall stiffness of the SMA hybrid composite structure and consequently changes natural frequency and mode shapes. The sound transmission and radiation from a composite panel is related to its frequency and mode shapes. Because of the capability to change both the natural frequency and mode shapes, the acoustic characteristics of SMA hybrid composite plates can be changed as well. The directivity pattern, radiation efficiency, and transmission loss of laminated composite materials are investigated based on 'composite' mode shapes in order to derive a basic understanding of the nature and authority of acoustic control by use of SMA hybrid composites.

Application of Analytic Hierarchy Process (AHP) in the analysis of the fuel efficiency in the automobile industry with the utilization of Natural Fiber Polymer Composites (NFPC)

NASA Astrophysics Data System (ADS)

Jayamani, E.; Perera, D. S.; Soon, K. H.; Bakri, M. K. B.

2017-04-01

A systematic method of material analysis aiming for fuel efficiency improvement with the utilization of natural fiber reinforced polymer matrix composites in the automobile industry is proposed. A multi-factor based decision criteria with Analytical Hierarchy Process (AHP) was used and executed through MATLAB to achieve improved fuel efficiency through the weight reduction of vehicular components by effective comparison between two engine hood designs. The reduction was simulated by utilizing natural fiber polymer composites with thermoplastic polypropylene (PP) as the matrix polymer and benchmarked against a synthetic based composite component. Results showed that PP with 35% of flax fiber loading achieved a 0.4% improvement in fuel efficiency, and it was the highest among the 27 candidate fibers.

Effect of Fungal Deterioration on Physical and Mechanical Properties of Hemp and Flax Natural Fiber Composites

PubMed Central

Crawford, Bryn; Pakpour, Sepideh; Kazemian, Negin; Klironomos, John; Stoeffler, Karen; Rho, Denis; Denault, Johanne; Milani, Abbas S.

2017-01-01

The development and application of bio-sourced composites have been gaining wide attention, yet their deterioration due to the growth of ubiquitous microorganisms during storage/manufacturing/in-service phases is still not fully understood for optimum material selection and design purposes. In this study, samples of non-woven flax fibers, hemp fibers, and mats made of co-mingled randomly-oriented flax or hemp fiber (50%) and polypropylene fiber (50%) were subjected to 28 days of exposure to (i) no water-no fungi, (ii) water only and (iii) water along with the Chaetomium globosum fungus. Biocomposite samples were measured for weight loss over time, to observe the rate of fungal growth and the respiration of cellulose components in the fibers. Tensile testing was conducted to measure mechanical properties of the composite samples under different configurations. Scanning electron microscopy was employed to visualize fungal hyphal growth on the natural fibers, as well as to observe the fracture planes and failure modes of the biocomposite samples. Results showed that fungal growth significantly affects the dry mass as well as the tensile elastic modulus of the tested natural fiber mats and composites, and the effect depends on both the type and the length scale of fibers, as well as the exposure condition and time. PMID:29088118

Faithful Tropicalization of Hypertoric Varieties

NASA Astrophysics Data System (ADS)

Kutler, Max B.

The hypertoric variety MA defined by an arrangement A of affine hyperplanes admits a natural tropicalization, induced by its embedding in a Lawrence toric variety. In this thesis, we explicitly describe the polyhedral structure of this tropicalization and calculate the fibers of the tropicalization map. Using a recent result of Gubler, Rabinoff, and Werner, we prove that there is a continuous section of the tropicalization map.

Effect of natural fibers and bio-resins on mechanical properties in hybrid and non-hybrid composites

NASA Astrophysics Data System (ADS)

Fragassa, Cristiano

2016-05-01

The aim of the present experimental investigation was to perform a comparative analysis concerning the influence on mechanical properties of natural fibers and/or bio-resins in reinforced thermoset composites. Flax and basalt fibers were selected as natural reinforcements, as single constituents or in hybrid combination. Glass synthetic fibers were used for comparison. Eco-friendly matrixes, both epoxy or vinylester, were considered and compared with composites based on traditional resins. Samples were fabricated by hand lay-up and resin infusion techniques. Cures were accelerated and controlled by applying heat and pressure in autoclave. Tensile, flexural and impact tests were carried out according to ASTM standards.

Validation of the CQUAD4 element for vibration and shock analysis of thin laminated composite plate structure

NASA Technical Reports Server (NTRS)

Lesar, Douglas E.

1992-01-01

The performance of the NASTRAN CQUAD4 membrane and plate element in the analysis of undamped natural vibration modes of thin fiber reinforced composite plates was evaluated. The element provides natural frequency estimates that are comparable in accuracy to alternative formulations, and, in most cases, deviate by less than 10 percent from experimentally measured frequencies. The predictions lie within roughly equal accuracy bounds for the two material types treated (GFRP and CFRP), and for the ply layups considered (unidirectional, cross-ply, and angle-ply). Effective elastic lamina moduli had to be adjusted for fiber volume fraction to attain this level of frequency. The lumped mass option provides more accurate frequencies than the consistent mass option. This evaluation concerned only plates with L/t ratios on the order of 100 to 150. Since the CQUAD4 utilizes first-order corrections for transverse laminate shear stiffness, the element should provide useful frequency estimates for plate-like structures with lower L/t. For plates with L/t below 20, consideration should be given to idealizing with 3-D solid elements. Based on the observation that natural frequencies and mode shapes are predicted with acceptable engineering accuracy, it is concluded that CQUAD4 should be a useful and accurate element for transient shock and steady state vibration analysis of naval ship

The effect of modified ijuk fibers to crystallinity of polypropylene composite

NASA Astrophysics Data System (ADS)

Prabowo, I.; Nur Pratama, J.; Chalid, M.

2017-07-01

Nowadays, plastics becomes concern associated with its degradation and environmental issues. It has led studies to develop an environmental-friendly material. To minimize the impact of those problems, recently the usage of natural fibers as a filler are introduced because of biodegradability and availability. The promising natural fiber is “ijuk” fiber from Arenga pinnata plant as a filler and polypropylene (PP) polymer as a matrix. Unfortunately, the natural fibers and polymers have the different properties on which polymers are polar while natural fibers are non-polar so that reducing the compatibility and resulting the poor crystallinity. To enhance the compatibility and crystallinity, ijuk fibers were prepared by multistage treatments including alkalinization with 5 and 10% sodium hydroxide (NaOH), oxidation with 3 and 6% sodium hypochlorite (NaClO) and hydrolysis with 20% sulphuric acid (H2SO4) in sequences. The purposes of multistage treatments are to remove the components such as lignin, wax, hemicellulose, to cause an oxidative fragmentation of remaining lignin and to annihilate the amorphous parts respectively. Fourier-Transform Infrared (FTIR) confirms the compatibility meanwhile Differential Scanning Calorimetry (DSC) reveals the crystallinity and Scanning Electron Microscope (SEM) displays surface morphology of polypropylene. The experiments were revealing that the effects of “ijuk” fibers by the multistage treatments of 5 and 10% NaOH resulting the crystallinity of polypropylene around 31.2 and 27.64% respectively compared to the crystallinity before adding the “ijuk” fibers for 16.8%. It indicates that the entire treatments increasing the compatibility and crystallinity of polypropylene. In addition, the use of 5% NaOH offers the better crystallinity than non-treated polypropylene. The experiments conclude that by adding alkalinized “ijuk” fibers of multistage treatments can increase the compatibility and crystallinity of polypropylene.

Automated determination of fibrillar structures by simultaneous model building and fiber diffraction refinement.

PubMed

Potrzebowski, Wojciech; André, Ingemar

2015-07-01

For highly oriented fibrillar molecules, three-dimensional structures can often be determined from X-ray fiber diffraction data. However, because of limited information content, structure determination and validation can be challenging. We demonstrate that automated structure determination of protein fibers can be achieved by guiding the building of macromolecular models with fiber diffraction data. We illustrate the power of our approach by determining the structures of six bacteriophage viruses de novo using fiber diffraction data alone and together with solid-state NMR data. Furthermore, we demonstrate the feasibility of molecular replacement from monomeric and fibrillar templates by solving the structure of a plant virus using homology modeling and protein-protein docking. The generated models explain the experimental data to the same degree as deposited reference structures but with improved structural quality. We also developed a cross-validation method for model selection. The results highlight the power of fiber diffraction data as structural constraints.

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

Krasnov, Igor, E-mail: Igor.Krasnov@hzg.de; Müller, Martin, E-mail: Martin.Mueller@hzg.de; Institute of Materials Research, Helmholtz-Zentrum Geesthacht

An optically active bio-material is created by blending natural silk fibers with photoisomerizable chromophore molecules—azobenzenebromide (AzBr). The material converts the energy of unpolarized light directly into mechanical work with a well-defined direction of action. The feasibility of the idea to produce optically driven microsized actuators on the basis of bio-material (silk) is proven. The switching behavior of the embedded AzBr molecules was studied in terms of UV/Vis spectroscopy. To test the opto-mechanical properties of the modified fibers and the structural changes they undergo upon optically induced switching, single fiber X-ray diffraction with a micron-sized synchrotron radiation beam was combined inmore » situ with optical switching as well as with mechanical testing and monitoring. The crystalline regions of silk are not modified by the presence of the guest molecules, hence occupy only the amorphous part of the fibers. It is shown that chromophore molecules embedded into fibers can be reversibly switched between the trans and cis conformation by illumination with light of defined wavelengths. The host fibers respond to this switching with a variation of the internal stress. The amplitude of the mechanical response is independent of the applied external stress and its characteristic time is shorter than the relaxation time of the usual mechanical response of silk.« less

Melt rheological properties of natural fiber-reinforced polypropylene

Treesearch

Jarrod J. Schemenauer; Tim A. Osswald; Anand R. Sanadi; Daniel F. Caulfield

2000-01-01

The melt viscosities and mechanical properties of 3 different natural fiber-polypropylene composites were investigated. Coir (coconut), jute, and kenaf fibers were compounded with polypropylene at 30% by weight content. A capillary rheometer was used to evaluate melt viscosity. The power-law model parameters are reported over a shear rate range between 100 to 1000 s–1...

Strain transfer analysis of optical fiber based sensors embedded in an asphalt pavement structure

NASA Astrophysics Data System (ADS)

Wang, Huaping; Xiang, Ping

2016-07-01

Asphalt pavement is vulnerable to random damage, such as cracking and rutting, which can be proactively identified by distributed optical fiber sensing technology. However, due to the material nature of optical fibers, a bare fiber is apt to be damaged during the construction process of pavements. Thus, a protective layer is needed for this application. Unfortunately, part of the strain of the host material is absorbed by the protective layer when transferring the strain to the sensing fiber. To account for the strain transfer error, in this paper a theoretical analysis of the strain transfer of a three-layered general model has been carried out by introducing Goodman’s hypothesis to describe the interfacial shear stress relationship. The model considers the viscoelastic behavior of the host material and protective layer. The effects of one crack in the host material and the sensing length on strain transfer relationship are been discussed. To validate the effectiveness of the strain transfer analysis, a flexible asphalt-mastic packaged distributed optical fiber sensor was designed and tested in a laboratory environment to monitor the distributed strain and appearance of cracks in an asphalt concrete beam at two different temperatures. The experimental results indicated that the developed strain transfer formula can significantly reduce the strain transfer error, and that the asphalt-mastic packaged optical fiber sensor can successfully monitor the distributed strain and identify local cracks.

Fabrication of nonwoven fabrics consisting of gelatin nanofibers cross-linked by glutaraldehyde or N-acetyl-d-glucosamine by aqueous method.

PubMed

Furuike, Tetsuya; Chaochai, Thitirat; Okubo, Tsubasa; Mori, Takahiro; Tamura, Hiroshi

2016-12-01

Since gelatin (Gel) undergoes a sol-gel transition, a novel dry-spinning procedure for Gel was used. Here, nonwoven fabrics of Gel were electrospun by applying the principles of dry spinning. The diameter of the fibers and the viscosity and flow rate of the solution were directly dependent on the concentration of Gel. Nonwoven fabrics spun with a 25% (w/w) Gel concentration only exhibited a nanoscale fiber diameter. In order to improve the properties of the nonwoven fabrics, they were cross-linked with glutaraldehyde (GTA) vapor after spinning or by the addition of N-acetyl-d-glucosamine (GlcNAc) to the Gel solution prior to spinning followed by heating these fibers. The developed nonwoven fibers were characterized using SEM, rheometry, FTIR, TGA, and mechanical tensile testing. The nonwoven fabrics cross-linked by the GTA vapor exhibited improved mechanical properties compared to those without cross-linking or with GlcNAc cross-linking. The swelling and water uptake ability resulted in no morphological changes in the fibers with GTA cross-linking. The TGA thermogram confirmed no phase change in the composite structure. Further, in vitro cytocompatibility studies using human mesenchymal stem cells showed the compatible nature of the developed nonwoven fibers. Our studies showed that these nonwoven fibers could be useful in medical care. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure and properties of polymeric composite materials during 1501 days outer space exposure at Salyut-7 orbital station

NASA Technical Reports Server (NTRS)

Startsev, Oleg V.; Nikishin, Eugene F.

1995-01-01

Specimens of polymeric composite materials for aviation and space applications such as glass fiber reinforced plastics (GFRP), carbon fiber reinforced plastics (CFRP), organic fiber reinforced plastics (OFRP), and hybrid plastics (HP) based on epoxy compounds were exposed to the space environment on the surface of Salyut-7 orbital station. The space exposure lasted 1501 days as a maximum. The data relating to the change in mechanical properties, mass losses, glass transition temperature, linear thermal expansion coefficient, and microstructure after various periods of exposure are given. It has been found that the change in properties is caused by the processes of binder postcuring and microerosion of the exposed surface of plastics. The phenomenon of strengthening of the surface layer of hybrid composites, due to which the nature of destruction changes at bending loads, has been revealed.

On the pull-out of fibers with fractal-tree structure and the interference of strength and fracture toughness of composites

NASA Astrophysics Data System (ADS)

Fe, Shaoyun; Zhou, Benlian; Lung, Chiwei

1992-06-01

An approximate theory of pull-out of fiber with fractal-tree structure from a matrix is developed with the aim of quantifying the effects of the fractal-tree structure of the fiber. In the experimental investigation of the pull-out of the synthetic fiber with fractal-tree structure, it was generally observed that the force and energy of fiber pullout increase with the branching angle. The application of this theory to experiment is successful. The strength and fracture toughness of composites reinforced by this kind of fiber are inferred to be greater than those of composites reinforced by plane fibers.

A forty-year history of fiber optic smart structures

NASA Astrophysics Data System (ADS)

Udd, Eric; Scheel, Ingrid U.

2017-04-01

In 1977 McDonnell Douglas Astronautics Company began a project on using fiber optic sensors to support the Delta Rocket program. This resulted in a series of fiber sensors to support the measurement of rotation, acoustics, vibration, strain, and temperature for a variety of applications and early work on fiber optic smart structures. The work on fiber optic smart structures transitioned in part to Blue Road Research in 1993 and continued in 2006 to the present at Columbia Gorge Research. This paper summarizes some of the efforts made by these companies to implement fiber optic smart structures over this forty year period.

USDA Flax fiber utilization research

USDA-ARS?s Scientific Manuscript database

The United States is pursuing natural fibers as sustainable, environmentally friendly sources for a variety of industrial applications. Flax (Linum usitatissimum L.) fiber offers many possibilities towards this goal. Research on flax fiber production, processing, and standards development is urgen...

Shrinkage deformation of cement foam concrete

NASA Astrophysics Data System (ADS)

Kudyakov, A. I.; Steshenko, A. B.

2015-01-01

The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

Characterizing the Collagen Fiber Orientation in Pericardial Leaflets Under Mechanical Loading Conditions

PubMed Central

Alavi, S. Hamed; Ruiz, Victor; Krasieva, Tatiana; Botvinick, Elliot L.; Kheradvar, Arash

2014-01-01

When implanted inside the body, bioprosthetic heart valve leaflets experience a variety of cyclic mechanical stresses such as shear stress due to blood flow when the valve is open, flexural stress due to cyclic opening and closure of the valve, and tensile stress when the valve is closed. These types of stress lead to a variety of failure modes. In either a natural valve leaflet or a processed pericardial tissue leaflet, collagen fibers reinforce the tissue and provide structural integrity such that the very thin leaflet can stand enormous loads related to cyclic pressure changes. The mechanical response of the leaflet tissue greatly depends on collagen fiber concentration, characteristics, and orientation. Thus, understating the microstructure of pericardial tissue and its response to dynamic loading is crucial for the development of more durable heart valve, and computational models to predict heart valves’ behavior. In this work, we have characterized the 3D collagen fiber arrangement of bovine pericardial tissue leaflets in response to a variety of different loading conditions under Second-Harmonic Generation Microscopy. This real-time visualization method assists in better understanding of the effect of cyclic load on collagen fiber orientation in time and space. PMID:23180029

Study on strength characteristics of concrete using M-Sand and coconut fibers

NASA Astrophysics Data System (ADS)

Neeraja, D.; Wani, Amir Iqbal; Kamili, Zainulabideen; Agarwal, Krishnakant

2017-11-01

In the current world, concrete has become a very important part of the construction industry and the materials which are used in making concrete have evolved due to better quality of cement and better grade of coarse aggregates. The sand is an important part of concrete. It is mainly procured from natural sources. Thus the grade of sand is not under our control. The methods of removing sand from river beds are causing various environmental issues and river sand is depleting at a faster rate than it is replaced by natural methods. Hence, various replacements for the river sand are being done, one of which is manufactured-sand. It is obtained from various granite quarries. Manufactured-sand or M-sand is slowly replacing the fine aggregate in the concrete as the sand is well graded and gives higher strength of concrete. There are various fibers used for reinforcing concrete which consist mainly of artificial or steel fibers. Some of these fibers are quite costly and sometimes difficult to obtain. So there are many natural fibers which can be used in place of these fibers, one of which is coconut fiber, extracted from the shell of a coconut. Coconut fibers are used in various industries like rope making, coir mattresses etc. Since these fibers are one of the strongest fibers among naturally occuring fibers, they can be used in the concrete mix to increase the resistance in concrete. They are also light weight and easily available and thus can be used in reinforcement of concrete. The studies up till now have tested the use of coconut fibers in normal concrete involving river sand but in this study a particular ratio of M-sand and river sand is used to get the maximum possible strength. Hence, in this project an attempt was made to use M-sand and coconut fiber in concrete. Based on the test results, it can be concluded that combination of M-sand and coconut fibers gave favorable results in strength criteria.

Experience-based training of students on concretes reinforced by recycled carbon fibers

NASA Astrophysics Data System (ADS)

Cosgun, Cumhur; Patlolla, Vamsidhar R.; Alzahrani, Naif; Zeineddine, Hatim F.; Asmatulu, Eylem

2017-04-01

Fiber reinforcement increases many properties of the concretes, such as toughness, strength, abrasion, and resistance to corrosion. Use of recycled carbon fibers from industrial waste offers many advantages because it will reduce the waste, contribute the economy, protect natural resources and improve the property of structural units. The City of Wichita, KS is known to be "Air Capital of the World" where many aircraft companies have been producing aircraft, parts and components. Due to the superior properties of composites (e.g., light weight, low density, high impact resistance), they have been highly used by aircraft industry. Prepreg is the most preferred combination of the fiber and resin due to the easy application, but it has a limited shelf life (e.g., three months to one year at most) and scrap has no use after all in the same industry. Every year tons of un-used prepreg or after use scrap are being collected in Wichita, KS. Recycling prepreg from the post-consumer waste offers great advantages of waste reduction and resource conservation in the city. Reusing the carbon fibers obtained from outdated prepreg composites for concrete reinforcement will offer double advantages for our environment and concrete structures. In this study, recycled carbon fibers of the outdated prepreg composites were collected, and then incorporated with concretes at different ratios prior to the molding and mechanical testing. An undergraduate student was involved in the project and observed all the process during the laboratory studies, as well as data collection, analysis and presentation. We believe that experience based learning will enhance the students' skills and interest into the scientific and engineering studies.

Functional grading of mineral and collagen in the attachment of tendon to bone.

PubMed

Genin, Guy M; Kent, Alistair; Birman, Victor; Wopenka, Brigitte; Pasteris, Jill D; Marquez, Pablo J; Thomopoulos, Stavros

2009-08-19

Attachment of dissimilar materials is a major challenge because high levels of localized stress may develop at their interfaces. An effective biologic solution to this problem exists at one of nature's most extreme interfaces: the attachment of tendon (a compliant, structural "soft tissue") to bone (a stiff, structural "hard tissue"). The goal of our study was to develop biomechanical models to describe how the tendon-to-bone insertion derives its mechanical properties. We examined the tendon-to-bone insertion and found two factors that give the tendon-to-bone transition a unique grading in mechanical properties: 1), a gradation in mineral concentration, measured by Raman spectroscopy; and 2), a gradation in collagen fiber orientation, measured by polarized light microscopy. Our measurements motivate a new physiological picture of the tissue that achieves this transition, the tendon-to-bone insertion, as a continuous, functionally graded material. Our biomechanical model suggests that the experimentally observed increase in mineral accumulation within collagen fibers can provide significant stiffening of the partially mineralized fibers, but only for concentrations of mineral above a "percolation threshold" corresponding to formation of a mechanically continuous mineral network within each collagen fiber (e.g., the case of mineral connectivity extending from one end of the fiber to the other). Increasing dispersion in the orientation distribution of collagen fibers from tendon to bone is a second major determinant of tissue stiffness. The combination of these two factors may explain the nonmonotonic variation of stiffness over the length of the tendon-to-bone insertion reported previously. Our models explain how tendon-to-bone attachment is achieved through a functionally graded material composition, and provide targets for tissue engineered surgical interventions and biomimetic material interfaces.

Effects of insoluble and soluble dietary fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus.

PubMed

Kimmel, S E; Michel, K E; Hess, R S; Ward, C R

2000-04-01

To evaluate the effects of diets differing in type and quantity of fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus. Prospective randomized crossover controlled trial. 7 dogs with well-regulated naturally occurring insulin-dependent diabetes mellitus. Dogs were fed 1 of 3 diets for 1 month each in 1 of 6 randomized diet sequences. Diets included a low-fiber diet (LF) and 2 high-fiber diets; 1 contained only insoluble fiber (HIF), and 1 contained soluble fiber in addition to insoluble fiber (HSF). Caloric intake was unchanged throughout the study. Glycemic control was assessed after each feeding trial by measuring serum fructosamine concentration and performing 5 serial measurements of blood glucose concentration every 2 hours after the morning feeding and insulin injection. Significant differences were not detected in body weight, required insulin dosage, or albumin concentration among dogs fed the HIF, HSF, and LF diets. Mean and maximum blood glucose concentrations and area under the blood glucose curve were significantly lower in dogs fed the HIF diet, compared with values in the same dogs fed the HSF or LF diet. Fructosamine concentration was significantly lower in dogs fed the HIF or HSF diet, compared with values in the same dogs fed the LF diet. In dogs with naturally occurring insulin-dependent diabetes mellitus, a dry, high insoluble-fiber diet may aid in glycemic control.

Hybrid Structure Multichannel All-Fiber Current Sensor.

PubMed

Jiang, Junzhen; Zhang, Hao; He, Youwu; Qiu, Yishen

2017-08-02

We have experimentally developed a hybrid-structure multi-channel all-fiber current sensor with ordinary silica fiber using fiber loop architecture. According to the rationale of time division multiplexing, the sensor combines parallel and serial structures. The purpose of the hybrid-structure multi-channel all-fiber current sensor is to get more information from the different measured points simultaneously. In addition, the hybrid-structure fiber current sensor exhibited a good linear response for each channel. A three-channel experiment was performed in the study and showed that the system could detect different current positions. Each channel could individually detect the current and needed a separate calibration system. Furthermore, the three channels will not affect each other.

Analysis of an all optical de-multiplexer architecture utilizing bevel design for spatially multiplexed optical fiber communication systems

NASA Astrophysics Data System (ADS)

Murshid, Syed H.; Finch, Michael F.; Lovell, Gregory L.

2014-09-01

Spatial domain multiplexing (SDM) is a system that allows multiple channels of light to traverse a single fiber, utilizing separate spatial regions inside the carrier fiber, thereby applying a new degree of photon freedom for optical fiber communications. These channels follow a helical pattern, the screen projection of which is viewable as concentric rings at the output end of the system. The MIMO nature of the SDM system implies that a typical pin-diode or APD will be unable to distinguish between these channels, as the diode will interpret the combination of the SDM signals from all channels as a single signal. As such, spatial de-multiplexing methods must be introduced to properly detect the SDM based MIMO signals. One such method utilizes a fiber consisting of multiple, concentric, hollow core fibers to route each channel independently and thereby de-mux the signals into separate fibers or detectors. These de-mux fibers consist of hollow core cylindrical structures with beveled edges on one side that gradually taper to route the circular, ring type, output energy patterns into a spot with the highest possible efficiency. This paper analyzes the beveled edge by varying its length and analyzing the total output power for each predetermined length allowing us to simulate ideal bevel length to minimize both system losses as well as total de-mux footprint. OptiBPM simulation engine is employed for these analyses.

Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications.

PubMed

Zhu, Hongli; Luo, Wei; Ciesielski, Peter N; Fang, Zhiqiang; Zhu, J Y; Henriksson, Gunnar; Himmel, Michael E; Hu, Liangbing

2016-08-24

With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much more to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interesting morphology-a distinctly mesoporous structure. Moreover, the walls of fiber cells are composed of thousands of fibers (or macrofibrils) oriented in a similar angle. Nanofibrils and nanocrystals can be further liberated from macrofibrils by mechanical, chemical, and enzymatic methods. The obtained nanocellulose has unique optical, mechanical, and barrier properties and is an excellent candidate for chemical modification and reconfiguration. Wood is naturally a composite material, comprised of cellulose, hemicellulose, and lignin. Wood is sustainable, earth abundant, strong, biodegradable, biocompatible, and chemically accessible for modification; more importantly, multiscale natural fibers from wood have unique optical properties applicable to different kinds of optoelectronics and photonic devices. Today, the materials derived from wood are ready to be explored for applications in new technology areas, such as electronics, biomedical devices, and energy. The goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies. The scope of the review covers multiscale materials and assemblies of cellulose, hemicellulose, and lignin as well as other biomaterials derived from wood, in regard to their major emerging applications. Structure-properties-application relationships will be investigated in detail. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of wood and wood-derived materials is advancing historical applications of these materials. This new level of understanding also enables a myriad of new and exciting applications, which motivate this review. There are excellent reviews already on the classical topic of woody materials, and some recent reviews also cover new understanding of these materials as well as potential applications. This review will focus on the uniqueness of woody materials for three critical applications: green electronics, biological devices, and energy storage and bioenergy.

Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications

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

Zhu, Hongli; Luo, Wei; Ciesielski, Peter N.

With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much moremore » to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interesting morphology--a distinctly mesoporous structure. Moreover, the walls of fiber cells are composed of thousands of fibers (or macrofibrils) oriented in a similar angle. Nanofibrils and nanocrystals can be further liberated from macrofibrils by mechanical, chemical, and enzymatic methods. The obtained nanocellulose has unique optical, mechanical, and barrier properties and is an excellent candidate for chemical modification and reconfiguration. Wood is naturally a composite material, comprised of cellulose, hemicellulose, and lignin. Wood is sustainable, earth abundant, strong, biodegradable, biocompatible, and chemically accessible for modification; more importantly, multiscale natural fibers from wood have unique optical properties applicable to different kinds of optoelectronics and photonic devices. Today, the materials derived from wood are ready to be explored for applications in new technology areas, such as electronics, biomedical devices, and energy. The goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies. The scope of the review covers multiscale materials and assemblies of cellulose, hemicellulose, and lignin as well as other biomaterials derived from wood, in regard to their major emerging applications. Structure-properties-application relationships will be investigated in detail. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of wood and wood-derived materials is advancing historical applications of these materials. This new level of understanding also enables a myriad of new and exciting applications, which motivate this review. There are excellent reviews already on the classical topic of woody materials, and some recent reviews also cover new understanding of these materials as well as potential applications. This review will focus on the uniqueness of woody materials for three critical applications: green electronics, biological devices, and energy storage and bioenergy.« less

Microscopic anthropogenic litter in terrestrial birds from Shanghai, China: Not only plastics but also natural fibers.

PubMed

Zhao, Shiye; Zhu, Lixin; Li, Daoji

2016-04-15

The level of contamination by microscopic anthropogenic litter (0.5-5mm) in terrestrial ecosystems is not well understood. After chemical digestion in 10% KOH, microscopic anthropogenic litter from the gastrointestinal tracts of 17 terrestrial birds was identified and categorized under a stereomicroscope based on its physical properties and melting tests. In total, 364 items from 16 birds were identified as microscopic anthropogenic litter, ranging in size from 0.5 to 8.5mm. No relationship between plastic load and body condition was found. Natural fibers, plastic fibers and fragmented plastics represented, respectively, 37.4% (136 items), 54.9% (200 items) and 7.7% (28 items) of total litter items. Small sample sizes limited our ability to draw strong conclusions about the metabolism of natural fibers, but the decline in the proportion of natural fibers from the esophagus to stomach to intestine suggested that they may be digestible. Particles smaller than 5mm represented more than 90% of the total number of pollutant items. Particles with colors in the mid-tones and fibrous shapes were overwhelmingly common particles. The results reflect pollution by microscopic anthropogenic litter in the terrestrial ecosystem of the study area. Microscopic natural fibers, which may disperse and adsorb chemical pollutants differently from microplastic and may pose an even greater risk, are in urgent need of further research. Copyright © 2016 Elsevier B.V. All rights reserved.

Tutorial for Collecting and Processing Images of Composite Structures to Determine the Fiber Volume Fraction

NASA Technical Reports Server (NTRS)

Conklin, Lindsey

2017-01-01

Fiber-reinforced composite structures have become more common in aerospace components due to their light weight and structural efficiency. In general, the strength and stiffness of a composite structure are directly related to the fiber volume fraction, which is defined as the fraction of fiber volume to total volume of the composite. The most common method to measure the fiber volume fraction is acid digestion, which is a useful method when the total weight of the composite, the fiber weight, and the total weight can easily be obtained. However, acid digestion is a destructive test, so the material will no longer be available for additional characterization. Acid digestion can also be difficult to machine out specific components of a composite structure with complex geometries. These disadvantages of acid digestion led the author to develop a method to calculate the fiber volume fraction. The developed method uses optical microscopy to calculate the fiber area fraction based on images of the cross section of the composite. The fiber area fraction and fiber volume fraction are understood to be the same, based on the assumption that the shape and size of the fibers are consistent in the depth of the composite. This tutorial explains the developed method for optically determining fiber area fraction performed at NASA Langley Research Center.

Structural basis for unique hierarchical cylindrites induced by ultrahigh shear gradient in single natural fiber reinforced poly(lactic acid) green composites.

PubMed

Xu, Huan; Xie, Lan; Jiang, Xin; Hakkarainen, Minna; Chen, Jing-Bin; Zhong, Gan-Ji; Li, Zhong-Ming

2014-05-12

A local shear flow field was feasibly generated by pulling the ramie fiber in single fiber reinforced poly(lactic acid) (PLA) composites. This was featured by an ultrahigh shear gradient with a maximum shear rate up to 1500 s(-1), a level comparable to that frequently occurring during the practical polymer processing. To distinguish shear-induced self-nucleation and ramie fiber-induced heterogeneous nucleation, the shear history was classified by pulling the fiber for 5 s (pulled sample) and pulling out the fiber during 10 s (pulled-out sample), while the static fiber-induced crystallization was carried out as the counterpart. As a result of the ultrahigh shear gradient, the combination of primary shear-induced nucleation in the central region and secondary nucleation in the outer layer assembled the unique hierarchical superstructures. By comparing the architectural configurations of interphases formed in the static, pulled, and pulled-out samples, it was shown that the hierarchical cylindrites underwent the process of self-nucleation driven by the applied shear flow, very different from the formation of fiber-induced transcrystallinity (TC) triggered by the heterogeneous nucleating sites at the static fiber surface. The twisting of transcrystallized lamellae may take place due to the spatial hindrance induced by the incredibly dense nuclei under the intense shearing flow, as observed in the synchrotron X-ray diffraction patterns. The influence of chain characteristics on the crystalline morphology was further explored by adding a small amount of poly(ethylene glycol) (PEG) to enhance the molecular mobility of PLA. It was of interest to find that the existence of PEG not only facilitated the growth rates of TC and cylindrites but also improved the preferential orientation of PLA chains and thus expanded the ordered regions. We unearthed lamellar units that were composed of rich fibrillar extended chain crystals (diameter of 50-80 nm). These results are of importance to shed light on tailoring crystalline morphology for natural fibers reinforced green composite materials. Of immense practical significance, too, is the crystalline evolution that has been tracked in the simple model penetrated with an ultrahigh shear gradient, which researchers have so far been unable to replicate during the practical melt processing, such as extrusion and injection molding.

All-Fiber Laser Curvature Sensor Using an In-Fiber Modal Interferometer Based on a Double Clad Fiber and a Multimode Fiber Structure

PubMed Central

Durán-Sánchez, Manuel; Prieto-Cortés, Patricia; Salceda-Delgado, Guillermo; Castillo-Guzmán, Arturo A.; Selvas-Aguilar, Romeo; Ibarra-Escamilla, Baldemar; Kuzin, Evgeny A.

2017-01-01

An all-fiber curvature laser sensor by using a novel modal interference in-fiber structure is proposed and experimentally demonstrated. The in-fiber device, fabricated by fusion splicing of multimode fiber and double-clad fiber segments, is used as wavelength filter as well as the sensing element. By including a multimode fiber in an ordinary modal interference structure based on a double-clad fiber, the fringe visibility of the filter transmission spectrum is significantly increased. By using the modal interferometer as a curvature sensitive wavelength filter within a ring cavity erbium-doped fiber laser, the spectral quality factor Q is considerably increased. The results demonstrate the reliability of the proposed curvature laser sensor with advantages of robustness, ease of fabrication, low cost, repeatability on the fabrication process and simple operation. PMID:29182527

All-Fiber Laser Curvature Sensor Using an In-Fiber Modal Interferometer Based on a Double Clad Fiber and a Multimode Fiber Structure.

PubMed

Álvarez-Tamayo, Ricardo I; Durán-Sánchez, Manuel; Prieto-Cortés, Patricia; Salceda-Delgado, Guillermo; Castillo-Guzmán, Arturo A; Selvas-Aguilar, Romeo; Ibarra-Escamilla, Baldemar; Kuzin, Evgeny A

2017-11-28

An all-fiber curvature laser sensor by using a novel modal interference in-fiber structure is proposed and experimentally demonstrated. The in-fiber device, fabricated by fusion splicing of multimode fiber and double-clad fiber segments, is used as wavelength filter as well as the sensing element. By including a multimode fiber in an ordinary modal interference structure based on a double-clad fiber, the fringe visibility of the filter transmission spectrum is significantly increased. By using the modal interferometer as a curvature sensitive wavelength filter within a ring cavity erbium-doped fiber laser, the spectral quality factor Q is considerably increased. The results demonstrate the reliability of the proposed curvature laser sensor with advantages of robustness, ease of fabrication, low cost, repeatability on the fabrication process and simple operation.

Thermal insulation attaching means. [adhesive bonding of felt vibration insulators under ceramic tiles

NASA Technical Reports Server (NTRS)

Leger, L. J. (Inventor)

1978-01-01

An improved isolation system is provided for attaching ceramic tiles of insulating material to the surface of a structure to be protected against extreme temperatures of the nature expected to be encountered by the space shuttle orbiter. This system isolates the fragile ceramic tiles from thermally and mechanically induced vehicle structural strains. The insulating tiles are affixed to a felt isolation pad formed of closely arranged and randomly oriented fibers by means of a flexible adhesive and in turn the felt pad is affixed to the metallic vehicle structure by an additional layer of flexible adhesive.

The GhTT2_A07 gene is linked to the brown color and natural flame retardancy phenotypes of Lc1 cotton (Gossypium hirsutum L.) fibers

USDA-ARS?s Scientific Manuscript database

Some naturally-colored brown cotton fibers from accessions of Gossypium hirsutum L. can be used to make textiles with enhanced flame retardancy (FR). Several independent brown fiber loci have been identified and mapped to chromosomes, but the underlying genes have not yet been identified, and the me...

On the Identification of Rayon/Viscose as a Major Fraction of Microplastics in the Marine Environment: Discrimination between Natural and Manmade Cellulosic Fibers Using Fourier Transform Infrared Spectroscopy

PubMed Central

Comnea-Stancu, Ionela Raluca; Wieland, Karin; Ramer, Georg; Schwaighofer, Andreas

2016-01-01

This work was sparked by the reported identification of man-made cellulosic fibers (rayon/viscose) in the marine environment as a major fraction of plastic litter by Fourier transform infrared (FT-IR) transmission spectroscopy and library search. To assess the plausibility of such findings, both natural and man-made fibers were examined using FT-IR spectroscopy. Spectra acquired by transmission microscopy, attenuated total reflection (ATR) microscopy, and ATR spectroscopy were compared. Library search was employed and results show significant differences in the identification rate depending on the acquisition method of the spectra. Careful selection of search parameters and the choice of spectra acquisition method were found to be essential for optimization of the library search results. When using transmission spectra of fibers and ATR libraries it was not possible to differentiate between man-made and natural fibers. Successful differentiation of natural and man-made cellulosic fibers has been achieved for FT-IR spectra acquired by ATR microscopy and ATR spectroscopy, and application of ATR libraries. As an alternative, chemometric methods such as unsupervised hierarchical cluster analysis, principal component analysis, and partial least squares-discriminant analysis were employed to facilitate identification based on intrinsic relationships of sample spectra and successful discrimination of the fiber type could be achieved. Differences in the ATR spectra depending on the internal reflection element (Ge versus diamond) were observed as expected; however, these did not impair correct classification by chemometric analysis. Moreover, the effects of different levels of humidity on the IR spectra of natural and man-made fibers were investigated, too. It has been found that drying and re-humidification leads to intensity changes of absorption bands of the carbohydrate backbone, but does not impair the identification of the fiber type by library search or cluster analysis. PMID:27650982

Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

NASA Astrophysics Data System (ADS)

Zhang, Hongrui; Yuan, Li; Liang, Guozheng; Gu, Aijuan

2014-11-01

Four hyperbranched polysiloxanes (HPSis) with different molecular weights and concentration ratios of double bonds to epoxy groups (1:6.5-1:0.7) were synthesized and characterized. Each HPSi was facilely grafted onto surfaces of Kevlar fibers (KFs) to develop novel modified fibers (HPSi-g-KFs). The structures and integrated properties of HPSi-g-KFs as well as the origin behind were systematically investigated. Results show that HPSi-g-KFs have much rougher surface morphologies, and their surface free energies are as high as about 1.7 times that of KFs, showing greatly improved wettability. Besides, HPSi-g-KFs have excellent UV resistance after 168 h UV irradiation, the retentions of tenacity, energy to break, modulus and break extension are as high as 92, 86, 95 and 96%, respectively, while those of KFs are 66-85%. In addition, compared with KFs, HPSi-g-KFs have higher tensile tenacity and energy to break with similar modulus and break extension, much better thermal stability and flame retardancy. The nature of HPSi has different influence on different property of fibers, the HPSi with smaller molecular weight and more epoxy groups is beneficial to prepare HPSi-g-KFs with better wettability, while that with larger molecular weight and more double bonds tends to prepare HPSi-g-KF with better flame retardancy and UV resistance.

Cellulose as an Architectural Element in Spatially Structured Escherichia coli Biofilms

PubMed Central

Serra, Diego O.; Richter, Anja M.

2013-01-01

Morphological form in multicellular aggregates emerges from the interplay of genetic constitution and environmental signals. Bacterial macrocolony biofilms, which form intricate three-dimensional structures, such as large and often radially oriented ridges, concentric rings, and elaborate wrinkles, provide a unique opportunity to understand this interplay of “nature and nurture” in morphogenesis at the molecular level. Macrocolony morphology depends on self-produced extracellular matrix components. In Escherichia coli, these are stationary phase-induced amyloid curli fibers and cellulose. While the widely used “domesticated” E. coli K-12 laboratory strains are unable to generate cellulose, we could restore cellulose production and macrocolony morphology of E. coli K-12 strain W3110 by “repairing” a single chromosomal SNP in the bcs operon. Using scanning electron and fluorescence microscopy, cellulose filaments, sheets and nanocomposites with curli fibers were localized in situ at cellular resolution within the physiologically two-layered macrocolony biofilms of this “de-domesticated” strain. As an architectural element, cellulose confers cohesion and elasticity, i.e., tissue-like properties that—together with the cell-encasing curli fiber network and geometrical constraints in a growing colony—explain the formation of long and high ridges and elaborate wrinkles of wild-type macrocolonies. In contrast, a biofilm matrix consisting of the curli fiber network only is brittle and breaks into a pattern of concentric dome-shaped rings separated by deep crevices. These studies now set the stage for clarifying how regulatory networks and in particular c-di-GMP signaling operate in the three-dimensional space of highly structured and “tissue-like” bacterial biofilms. PMID:24097954

Cellulose as an architectural element in spatially structured Escherichia coli biofilms.

PubMed

Serra, Diego O; Richter, Anja M; Hengge, Regine

2013-12-01

Morphological form in multicellular aggregates emerges from the interplay of genetic constitution and environmental signals. Bacterial macrocolony biofilms, which form intricate three-dimensional structures, such as large and often radially oriented ridges, concentric rings, and elaborate wrinkles, provide a unique opportunity to understand this interplay of "nature and nurture" in morphogenesis at the molecular level. Macrocolony morphology depends on self-produced extracellular matrix components. In Escherichia coli, these are stationary phase-induced amyloid curli fibers and cellulose. While the widely used "domesticated" E. coli K-12 laboratory strains are unable to generate cellulose, we could restore cellulose production and macrocolony morphology of E. coli K-12 strain W3110 by "repairing" a single chromosomal SNP in the bcs operon. Using scanning electron and fluorescence microscopy, cellulose filaments, sheets and nanocomposites with curli fibers were localized in situ at cellular resolution within the physiologically two-layered macrocolony biofilms of this "de-domesticated" strain. As an architectural element, cellulose confers cohesion and elasticity, i.e., tissue-like properties that-together with the cell-encasing curli fiber network and geometrical constraints in a growing colony-explain the formation of long and high ridges and elaborate wrinkles of wild-type macrocolonies. In contrast, a biofilm matrix consisting of the curli fiber network only is brittle and breaks into a pattern of concentric dome-shaped rings separated by deep crevices. These studies now set the stage for clarifying how regulatory networks and in particular c-di-GMP signaling operate in the three-dimensional space of highly structured and "tissue-like" bacterial biofilms.

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

DOEpatents

Bunch, Kyle J.; McMakin, Douglas L.

2012-09-04

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

Correlating Detergent Fiber Analysis and Dietary Fiber Analysis Data for Corn Stover

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

Wolfrum, E. J.; Lorenz, A. J.; deLeon, N.

There exist large amounts of detergent fiber analysis data [neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL)] for many different potential cellulosic ethanol feedstocks, since these techniques are widely used for the analysis of forages. Researchers working in the area of cellulosic ethanol are interested in the structural carbohydrates in a feedstock (principally glucan and xylan), which are typically determined by acid hydrolysis of the structural fraction after multiple extractions of the biomass. These so-called dietary fiber analysis methods are significantly more involved than detergent fiber analysis methods. The purpose of this study was to determinemore » whether it is feasible to correlate detergent fiber analysis values to glucan and xylan content determined by dietary fiber analysis methods for corn stover. In the detergent fiber analysis literature cellulose is often estimated as the difference between ADF and ADL, while hemicellulose is often estimated as the difference between NDF and ADF. Examination of a corn stover dataset containing both detergent fiber analysis data and dietary fiber analysis data predicted using near infrared spectroscopy shows that correlations between structural glucan measured using dietary fiber techniques and cellulose estimated using detergent techniques, and between structural xylan measured using dietary fiber techniques and hemicellulose estimated using detergent techniques are high, but are driven largely by the underlying correlation between total extractives measured by fiber analysis and NDF/ADF. That is, detergent analysis data is correlated to dietary fiber analysis data for structural carbohydrates, but only indirectly; the main correlation is between detergent analysis data and solvent extraction data produced during the dietary fiber analysis procedure.« less

Application of optical interferometric techniques for non-destructive evaluation of novel "green" composite materials

NASA Astrophysics Data System (ADS)

Pagliarulo, Vito; Russo, Pietro; Bianco, Vittorio; Ferraro, Pietro; Simeoli, Giorgio; Cimino, Francesca; Ruggiero, Berardo

2018-04-01

Nowadays the use of advanced composite materials in aeronautics, both civil and military, in automotive and in sport applications, citing some, is well established. The characteristics of composite materials in terms of weight, fatigue resistance and corrosion resistance make them competitive with respect to conventional ones. On the other side, the fabrication process of the most employed composites reinforced by carbon fibers or glass fibers, needs of complex steps that not always are environmental complaisant. Moreover, such fibers are not themselves "green". For these reasons, in the last decades, the use of natural reinforcing fibers has gained an increasing attention allowing the development of new materials with the same advantages of composite systems but respecting the environment. Furthermore, such materials for their structural complexity are not always compatible with the use of standard non-destructive evaluation as the ultrasounds methods. In this work the efficiency of the employment of optical interferometric techniques as nondestructive evaluation methods in full field modality is proved on novel "green" composite materials. In particular, Electronic Speckle Pattern Interferometry has been tested on different kinds of specimens after flexural tests.

Dual noise-like pulse and soliton operation of a fiber ring cavity

NASA Astrophysics Data System (ADS)

Bracamontes Rodríguez, Y. E.; Pottiez, O.; García Sanchez, E.; Lauterio Cruz, J. P.; Ibarra-Villalón, H.; Hernandez-Garcia, J. C.; Bello-Jimenez, M.; Beltrán-Pérez, G.; Ibarra-Escamilla, B.; Kuzin, E. A.

2017-03-01

Passively mode-locked fiber lasers (PML-FLs) are versatile sources that are capable of generating a broad variety of short and ultrashort optical pulses. Besides conservative solitons, PML-FLs allow the generation of different kinds of dissipative structures, usually called dissipative solitons, a concept that also encompasses more complex structures and collective behaviors such as soliton molecules, gas, rain of solitons, etc. In addition to this, PML-FLs are also able to generate even more complex objects, the so-called noise-like pulses (NLPs). A few recent research results revealed a connection between NLPs and solitons, a sign that deterministic ingredients enter into the composition of NLPs, whose nature is traditionally assumed to be random. Although it is usual that a fiber laser is able to generate either solitons or noise-like pulses, depending on pump power and adjustments in the cavity, these two regimes are rarely observed simultaneously. In this paper, a PML-FL in a ring configuration is presented, in which it is possible to observe and verify experimentally the simultaneous presence of NLPs and solitons. Interestingly, these two components are found in different spectral regions, which greatly facilitates their separation and individual study and characterization.

Hierarchically Structured Electrospun Fibers

DTIC Science & Technology

2013-01-07

polymeric materials such as ceramics and metals, can be fabricated into nanofibers via electrospinning . An assortment of natural polymers, such as the...are traditionally made by electrospinning of the core material, which serves as a template for the deposition of the shell layer via chemical vapor...been made from the contraction of a manganese oxide sol gel upon solvent evaporation, as well as from zinc oxide and silicon dioxide using vapor

Mechanical properties of untreated and alkaline treated fibers from zalacca midrib wastes

NASA Astrophysics Data System (ADS)

Raharjo, Wahyu Purwo; Soenoko, Rudy; Purnowidodo, Anindito; Choiron, Mochammad Agus; Triyono

2016-03-01

The environmental concern has been raised due to the abundance of waste from synthetic materials which cannot be biodegraded after their life-time. It provides opportunity to exploit natural resources which are neglected. For example, midrib wastes from zalacca plants after cutting are able to utilize as composite reinforcement. The aim of this research was to characterize the mechanical properties of zalacca midrib fibers. As other ones, zalacca midrib fibers consisted of cellulose, hemicellulose and lignin, which their compositions were 42.54, 34.35 and 28.01 % respectively. To raise their cellulose content, the zalacca fibers were alkaline treated by immersion in the sodium hydroxide for 2 hours and rinsing in the distilled water. The concentration of sodium hydroxide was varied 1 and 5%. To investigate the influence of alkaline treatment, the mechanical testing and morphological analysis was performed. The tensile testing was done to obtain ultimate strength, elastic modulus and strain to fracture. The surface morphology of fibers was observed by SEM. The average ultimate tensile strength of zalacca fibers ranged from 182.12 MPa (untreated) to 417.94 MPa (5%NaOH treated). The diameter measurement showed that the alkaline treatment reduce the average fiber diameters due to the decline of the hemicellulose and lignin content as fiber matrix. This caused the increase of the tensile strength and elastic modulus due to the reduction of diameters as divider meanwhile the cellulose content as structural supporter of the fibers was relatively constant. From the SEM analysis, it was shown that the alkaline treatment reduced the fiber matrix so that its surface morphology became rougher due to the microfibrils appearance.

Highly filled formaldehyde-free natural fiber polypropylene composites

Treesearch

Anand R. Sanadi; Daniel F. Caulfield

2000-01-01

Considerable interest has been generated in the use of lignocellulosic fibers and wastes (both agricultural and wood based) as fillers and reinforcements in thermoplastics. In general, present technologies limit fiber loading in thermoplastics to about 50% by weight of fiber. To produce high fiber content composites for commercial use while maintaining adequate...

Bridging classical and molecular genetics of cotton fiber quality and development

USDA-ARS?s Scientific Manuscript database

Cotton is the single most important natural fiber in the world and represents a vital agricultural commodity in the global economy. Ninety percent of cotton’s value resides in the lint fiber. Cotton fiber quality, defined by the physical properties of the lint fibers, is an important part of the cot...

Fibrin structural and diffusional analysis suggests that fibers are permeable to solute transport.

PubMed

Leonidakis, Kimon Alexandros; Bhattacharya, Pinaki; Patterson, Jennifer; Vos, Bart E; Koenderink, Gijsje H; Vermant, Jan; Lambrechts, Dennis; Roeffaers, Maarten; Van Oosterwyck, Hans

2017-01-01

Fibrin hydrogels are promising carrier materials in tissue engineering. They are biocompatible and easy to prepare, they can bind growth factors and they can be prepared from a patient's own blood. While fibrin structure and mechanics have been extensively studied, not much is known about the relation between structure and diffusivity of solutes within the network. This is particularly relevant for solutes with a size similar to that of growth factors. A novel methodological approach has been used in this study to retrieve quantitative structural characteristics of fibrin hydrogels, by combining two complementary techniques, namely confocal fluorescence microscopy with a fiber extraction algorithm and turbidity measurements. Bulk rheological measurements were conducted to determine the impact of fibrin hydrogel structure on mechanical properties. From these measurements it can be concluded that variations in the fibrin hydrogel structure have a large impact on the rheological response of the hydrogels (up to two orders of magnitude difference in storage modulus) but only a moderate influence on the diffusivity of dextran solutes (up to 25% difference). By analyzing the diffusivity measurements by means of the Ogston diffusion model we further provide evidence that individual fibrin fibers can be semi-permeable to solute transport, depending on the average distance between individual protofibrils. This can be important for reducing mass transport limitations, for modulating fibrinolysis and for growth factor binding, which are all relevant for tissue engineering. Fibrin is a natural biopolymer that has drawn much interest as a biomimetic carrier in tissue engineering applications. We hereby use a novel combined approach for the structural characterization of fibrin networks based on optical microscopy and light scattering methods that can also be applied to other fibrillar hydrogels, like collagen. Furthermore, our findings on the relation between solute transport and fibrin structural properties can lead to the optimized design of fibrin hydrogel constructs for controlled release applications. Finally, we provide new evidence for the fact that fibrin fibers may be permeable for solutes with a molecular weight comparable to that of growth factors. This finding may open new avenues for tailoring mass transport properties of fibrin carriers. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Single-mode annular chirally-coupled core fibers for fiber lasers

NASA Astrophysics Data System (ADS)

Zhang, Haitao; Hao, He; He, Linlu; Gong, Mali

2018-03-01

Chirally-coupled core (CCC) fiber can transmit single fundamental mode and effectively suppresses higher-order mode (HOM) propagation, thus improve the beam quality. However, the manufacture of CCC fiber is complicated due to its small side core. To decrease the manufacture difficulty in China, a novel fiber structure is presented, defined as annular chirally-coupled core (ACCC) fiber, replacing the small side core by a larger side annulus. In this paper, we designed the fiber parameters of this new structure, and demonstrated that the new structure has a similar property of single mode with traditional CCC fiber. Helical coordinate system was introduced into the finite element method (FEM) to analyze the mode field in the fiber, and the beam propagation method (BPM) was employed to analyze the influence of the fiber parameters on the mode loss. Based on the result above, the fiber structure was optimized for efficient single-mode transmission, in which the core diameter is 35 μm with beam quality M2 value of 1.04 and an optical to optical conversion efficiency of 84%. In this fiber, fundamental mode propagates in an acceptable loss, while the HOMs decay rapidly.

Poly(ɛ-caprolactone)/gelatin composite electrospun scaffolds with porous crater-like structures for tissue engineering.

PubMed

Hwang, Patrick T J; Murdock, Kyle; Alexander, Grant C; Salaam, Amanee D; Ng, Joshua I; Lim, Dong-Jin; Dean, Derrick; Jun, Ho-Wook

2016-04-01

Electrospinning has been widely used to fabricate scaffolds imitating the structure of natural extracellular matrix (ECM). However, conventional electrospinning produces tightly compacted nanofiber layers with only small superficial pores and a lack of bioactivity, which limit the usefulness of electrospinning in biomedical applications. Thus, a porous poly(ε-caprolactone) (PCL)/gelatin composite electrospun scaffold with crater-like structures was developed. Porous crater-like structures were created on the scaffold by a gas foaming/salt leaching process; this unique fiber structure had more large pore areas and higher porosity than the conventional electrospun fiber network. Various ratios of PCL/gelatin (concentration ratios: 100/0, 75/25, and 50/50) composite electrospun scaffolds with and without crater-like structures were characterized by their microstructures, surface chemistry, degradation, mechanical properties, and ability to facilitate cell growth and infiltration. The combination of PCL and gelatin endowed the scaffold with both structural stability of PCL and bioactivity of gelatin. All ratios of scaffolds with crater-like structures showed fairly similar surface chemistry, degradation rates, and mechanical properties to equivalent scaffolds without crater-like structures; however, craterized scaffolds displayed higher human mesenchymal stem cell (hMSC) proliferation and infiltration throughout the scaffolds after 7-day culture. Therefore, these results demonstrated that PCL/gelatin composite electrospun scaffolds with crater-like structures can provide a structurally and biochemically improved three-dimensional ECM-mimicking microenvironment. © 2016 Wiley Periodicals, Inc.

Poly(ε-caprolactone)/gelatin composite electrospun scaffolds with porous crater-like structures for tissue engineering

PubMed Central

Hwang, Patrick T.J.; Murdock, Kyle; Alexander, Grant C.; Salaam, Amanee D.; Ng, Joshua I.; Lim, Dong-Jin; Dean, Derrick; Jun, Ho-Wook

2016-01-01

Electrospinning has been widely used to fabricate scaffolds imitating the structure of natural extracellular matrix (ECM). However, conventional electrospinning produces tightly compacted nanofiber layers with only small superficial pores and a lack of bioactivity, which limit the usefulness of electrospinning in biomedical applications. Thus, a porous poly(ε-caprolactone) (PCL)/gelatin composite electrospun scaffold with crater-like structures was developed. Porous crater-like structures were created on the scaffold by a gas foaming/salt leaching process; this unique fiber structure had more large pore areas and higher porosity than the conventional electrospun fiber network. Various ratios of PCL/gelatin (concentration ratios: 100/0, 75/25, and 50/50) composite electrospun scaffolds with and without crater-like structures were characterized by their microstructures, surface chemistry, degradation, mechanical properties, and ability to facilitate cell growth and infiltration. The combination of PCL and gelatin endowed the scaffold with both structural stability of PCL and bioactivity of gelatin. All ratios of scaffolds with crater-like structures showed fairly similar surface chemistry, degradation rates, and mechanical properties to equivalent scaffolds without crater-like structures; however, craterized scaffolds displayed higher human mesenchymal stem cell (hMSC) proliferation and infiltration throughout the scaffolds after 7-day culture. Therefore, these results demonstrated that PCL/gelatin composite electrospun scaffolds with crater-like structures can provide a structurally and biochemically improved three-dimensional ECM-mimicking microenvironment. PMID:26567028

Optical fiber curvature sensor based on MMF-SCF-MMF structure

NASA Astrophysics Data System (ADS)

Wang, Qi; Liu, Yu

2018-07-01

A sensitive curvature sensor based on MMF-SCF-MMF (MMF: multimode fiber; SCF: seven core fiber) structure is proposed. The multimode fiber (MMF) are used to improve the light coupling efficiency between the input singlemode fiber (SMF) and the seven-core fiber (SCF), and the seven-core fiber is used as the main element for curvature measurement. Experimental results show that the best curvature sensitivity reaches 41.46453 nm/m-1 in the range of 0.094 m-1-0.567 m-1. The temperature sensitivity is up to 59.02 pm/°C in the range of 20 °C-55 °C. The optical curvature sensors are widely used for buildings structure health monitoring and mechanical engineering due to the advantages of compact structure, anti-electromagnetic interference, and low cost.

Fibrin Networks Support Recurring Mechanical Loads by Adapting their Structure across Multiple Scales.

PubMed

Kurniawan, Nicholas A; Vos, Bart E; Biebricher, Andreas; Wuite, Gijs J L; Peterman, Erwin J G; Koenderink, Gijsje H

2016-09-06

Tissues and cells sustain recurring mechanical loads that span a wide range of loading amplitudes and timescales as a consequence of exposure to blood flow, muscle activity, and external impact. Both tissues and cells derive their mechanical strength from fibrous protein scaffolds, which typically have a complex hierarchical structure. In this study, we focus on a prototypical hierarchical biomaterial, fibrin, which is one of the most resilient naturally occurring biopolymers and forms the structural scaffold of blood clots. We show how fibrous networks composed of fibrin utilize irreversible changes in their hierarchical structure at different scales to maintain reversible stress stiffening up to large strains. To trace the origin of this paradoxical resilience, we systematically tuned the microstructural parameters of fibrin and used a combination of optical tweezers and fluorescence microscopy to measure the interactions of single fibrin fibers for the first time, to our knowledge. We demonstrate that fibrin networks adapt to moderate strains by remodeling at the network scale through the spontaneous formation of new bonds between fibers, whereas they adapt to high strains by plastic remodeling of the fibers themselves. This multiscale adaptation mechanism endows fibrin gels with the remarkable ability to sustain recurring loads due to shear flows and wound stretching. Our findings therefore reveal a microscopic mechanism by which tissues and cells can balance elastic nonlinearity and plasticity, and thus can provide microstructural insights into cell-driven remodeling of tissues. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Evaluation of Mechanical Properties and Morphological Studies of Rice Husk (Treated/Untreated)-CaCO3 Reinforced Epoxy Hybrid Composites

NASA Astrophysics Data System (ADS)

Verma, Deepak; Joshi, Garvit; Gupta, Ayush

2016-10-01

Natural fiber reinforced composites are a very popular area of research because of the easy availability and biodegradability of these fibers. The manufacturing of natural fiber composite is done by reinforcing fibers in the particulate form, fiber form or in woven mat form. Natural fiber composites also utilize industrial wastes as a secondary reinforcements like fly ash, sludge etc. By keeping all these point of views in the present investigation the effect of rice husk flour (chemically treated/untreated) and micro sized calcium carbonate with epoxy resin have been evaluated. The diameter of rice husk flour was maintained at 600 µm through mechanical sieving machine. The husk flour was chemically treated with NaOH (5 % w/v). Mechanical properties like hardness, flexural impact and compression strength were evaluated and found to be superior in modified or chemically treated flour as compared to unmodified or untreated flour reinforced composites. Scanning electron microscopy (SEM) study was also undertaken for the developed composites. SEM study shows the distribution of the rice husk flour and calcium carbonate over the matrix.

Using different fibers to replace fat in sponge cakes: In vitro starch digestion and physico-structural studies.

PubMed

Diez-Sánchez, Elena; Llorca, Empar; Quiles, Amparo; Hernando, Isabel

2018-01-01

This study assessed the effect of substituting 30% of fat by soluble, insoluble fiber, or a mix of both fibers in sponge cake quality, structure, acceptability, and starch digestibility. The apparent viscosity of the different formulations was measured and micro-baking was simulated. Texture profile tests were carried out and the crumb structure was examined. In vitro digestion was performed to study the digestibility of starch and a sensory test was carried out to know consumer acceptance. The soluble fiber (maltodextrin) affected the structure and quality of the cakes less than the insoluble fiber (potato fiber) and the use of soluble fiber in the formulation resulted in lower glucose release under in vitro conditions. Moreover, the consumer did not find differences among the control cake and the cakes prepared with soluble fiber. Considering the results as a whole, soluble fiber may be used for partial replacement of fat in sponge cake formulations and may constitute an appropriate strategy for obtaining healthy sponge cakes.

Distributed Fiber Optic Sensors For The Monitoring Of A Tunnel Crossing A Landslide

NASA Astrophysics Data System (ADS)

Minardo, Aldo; Picarelli, Luciano; Zeni, Giovanni; Catalano, Ester; Coscetta, Agnese; Zhang, Lei; DiMaio, Caterina; Vassallo, Roberto; Coviello, Roberto; Macchia, Giuseppe Nicola Paolo; Zeni, Luigi

2017-04-01

Optical fiber distributed sensors have recently gained great attention in structural and environmental monitoring due to specific advantages because they share all the classical advantages common to all optical fiber sensors such as immunity to electromagnetic interferences, high sensitivity, small size and possibility to be embedded into the structures, multiplexing and remote interrogation capabilities [1], but also offer the unique feature of allowing the exploitation of a telecommunication grade optical fiber cable as the sensing element to measure deformation and temperature profiles over long distances, without any added devices. In particular, distributed optical fiber sensors based on stimulated Brillouin scattering through the so-called Brillouin Optical Time Domain Analysis (BOTDA), allow to measure strain and temperature profiles up to tens of kilometers with a strain accuracy of ±10µɛ and a temperature accuracy of ±1°C. These sensors have already been employed in static and dynamic monitoring of a variety of structures resulting able to identify and localize many kind of failures [2,3,4]. This paper deals with the application of BOTDA to the monitoring of the deformations of a railway tunnel (200 m long) constructed in the accumulation of Varco d'Izzo earthflow, Potenza city, in the Southern Italian Apennine. The earthflow, which occurs in the tectonized clay shale formation called Varicoloured Clays, although very slow, causes continuous damage to buildings and infrastructures built upon or across it. The railway tunnel itself had to be re-constructed in 1992. Since then, the Italian National Railway monitored the structure by means of localized fissure-meters. Recently, thanks to a collaboration with the rail Infrastructure Manager (RFI), monitoring of various zones of the landslide including the tunnel is based on advanced systems, among which the optical fiber distributed sensors. First results show how the sensing optical fiber cable is able to detect the formation of localized strains and cracks, following the evolution of their width and identifying their location along the tunnel walls. It is worth noticing that the distributed nature of the sensor makes it possible to perform the monitoring with no preliminary information about the possible location of concentrated deformation. The sensing cable is simply glued to the tunnel walls and the system will remotely detect and locate any deformation and fracture wherever they occur along the fiber path, so representing a powerful early warning system. [1] J. M. López-Higuera, L. R. Cobo, A. Q. Incera, A. Cobo, "Fiber Optic Sensors in Structural Health Monitoring", Journal of Lightwave Technology, 29, 2011. [2] L. Zeni, L. Picarelli, B. Avolio, A. Coscetta, R. Papa, G. Zeni, C. Di Maio, R. Vassallo, A. Minardo, "Brillouin Optical Time Domain Analysis for Geotechnical Monitoring", Journal of Rock Mechanics and Geotechnical Engineering, 7, 2015 [3] A. Minardo, G. Porcaro, D. Giannetta, R. Bernini, L. Zeni, "Real-time monitoring of railway traffic using slope-assisted Brillouin distributed sensors", Applied Optics, 52, 2013 [4] A. Minardo, A. Coscetta, S. Pirozzi, R. Bernini, L. Zeni, "Experimental modal analysis of an aluminum rectangular plate by use of the slope-assisted BOTDA method", Smart Materials & Structures, 22, 2014

Experimental and Numerical Evaluation of the Mechanical Behavior of Strongly Anisotropic Light-Weight Metallic Fiber Structures under Static and Dynamic Compressive Loading

PubMed Central

Andersen, Olaf; Vesenjak, Matej; Fiedler, Thomas; Jehring, Ulrike; Krstulović-Opara, Lovre

2016-01-01

Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted. PMID:28773522

Experimental and Numerical Evaluation of the Mechanical Behavior of Strongly Anisotropic Light-Weight Metallic Fiber Structures under Static and Dynamic Compressive Loading.

PubMed

Andersen, Olaf; Vesenjak, Matej; Fiedler, Thomas; Jehring, Ulrike; Krstulović-Opara, Lovre

2016-05-21

Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted.

Correlation Function Analysis of Fiber Networks: Implications for Thermal Conductivity

NASA Technical Reports Server (NTRS)

Martinez-Garcia, Jorge; Braginsky, Leonid; Shklover, Valery; Lawson, John W.

2011-01-01

The heat transport in highly porous fiber structures is investigated. The fibers are supposed to be thin, but long, so that the number of the inter-fiber connections along each fiber is large. We show that the effective conductivity of such structures can be found from the correlation length of the two-point correlation function of the local conductivities. Estimation of the parameters, determining the conductivity, from the 2D images of the structures is analyzed.

Tracking cotton fiber quality throughout a stipper harvester: Part II

USDA-ARS?s Scientific Manuscript database

Cotton fiber quality begins to degrade naturally with the opening of the boll and mechanical harvesting processes are perceived to exacerbate fiber degradation. Previous research indicates that stripper harvested cotton generally has lower fiber quality and higher foreign matter content than picker ...

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®.

On fiber rejection loss in flotation deinking

Treesearch

J.Y. Zhu; Freya Tan

2005-04-01

Reducing fiber rejection loss in flotation deinking is very important to conserve natural resources and reduce the cost of secondary fibers in paper recycling. This study examined two aspects of the problem, fiber consistency in the rejection stream and rate of Froth (or wet stream) rejection. Flotation experiments were conducted using both nylon and wood fibers in...

Trends in polymeric electrospun fibers and their use as oral biomaterials.

PubMed

Meireles, Agnes B; Corrêa, Daniella K; da Silveira, João Vw; Millás, Ana Lg; Bittencourt, Edison; de Brito-Melo, Gustavo Ea; González-Torres, Libardo A

2018-05-01

Electrospinning is one of the techniques to produce structured polymeric fibers in the micro or nano scale and to generate novel materials for biomedical proposes. Electrospinning versatility provides fibers that could support different surgical and rehabilitation treatments. However, its diversity in equipment assembly, polymeric materials, and functional molecules to be incorporated in fibers result in profusion of recent biomaterials that are not fully explored, even though the recognized relevance of the technique. The present article describes the main electrospun polymeric materials used in oral applications, and the main aspects and parameters of the technique. Natural and synthetic polymers, blends, and composites were identified from the available literature and recent developments. Main applications of electrospun fibers were focused on drug delivery systems, tissue regeneration, and material reinforcement or modification, although studies require further investigation in order to enable direct use in human. Current and potential usages as biomaterials for oral applications must motivate the development in the use of electrospinning as an efficient method to produce highly innovative biomaterials, over the next few years. Impact statement Nanotechnology is a challenge for many researchers that look for obtaining different materials behaviors by modifying characteristics at a very low scale. Thus, the production of nanostructured materials represents a very important field in bioengineering, in which the electrospinning technique appears as a suitable alternative. This review discusses and provides further explanation on this versatile technique to produce novel polymeric biomaterials for oral applications. The use of electrospun fibers is incipient in oral areas, mainly because of the unfamiliarity with the technique. Provided disclosure, possibilities and state of the art are aimed at supporting interested researchers to better choose proper materials, understand, and design new experiments. This work seeks to encourage many other researchers-Dentists, Biologists, Engineers, Pharmacists-to develop innovative materials from different polymers. We highlight synthetic and natural polymers as trends in treatments to motivate an advance in the worldwide discussion and exploration of this interdisciplinary field.

Study on structure, mechanical property and cell cytocompatibility of electrospun collagen nanofibers crosslinked by common agents.

PubMed

Luo, Xueshi; Guo, Zhenzhao; He, Ping; Chen, Tian; Li, Lihua; Ding, Shan; Li, Hong

2018-07-01

Collagen electrospun scaffolds properly reproduce the framework of the extracellular matrix (ECM) of tissues that are natural with the fibrous morphology of the protein by coupling large biomimetism of the biological material. However, traditional solvents employed for collagen electrospinning lead to poor mechanical attributes and bad hydro-stability. In this work, by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride with N-hydroxysulfosuccinimide (EDC-NHS), glutaraldehyde (GTA) and genipin (GP) respectively, electrospun collagen fibers cross-linked, effectively stabilized the fiber morphology over 2months and improved the mechanical properties in both dry and wet state, especially EDC-NHS with large ultimate tensile stress and ε b . The secondary structure of collagen structure still remained and had no obvious difference among various crosslinked samples according to FTIR. On the cell assessment, electrospun collagen fibers crosslinked by EDC-NHS, GTA and GP, were found to support cell adhesion, spreading and proliferation of MC3T3-E1. By contrast, GTA was more effective in preserving explicit fibrous morphology with a relatively lower cell viability both in FBS and BSA soaked mats. Interestingly, GP also had the similar cytocompatibility of MC3T3-E1 as EDC-NHS did. The study proved the feasibility of chemical crosslinker to electrospun collagen for biomedical application. Copyright © 2018. Published by Elsevier B.V.

Self-healing nanocomposite using shape memory polymer and carbon nanotubes

NASA Astrophysics Data System (ADS)

Liu, Yingtao; Rajadas, Abhishek; Chattopadhyay, Aditi

2013-04-01

Carbon fiber reinforced composites are used in a wide range of applications in aerospace, mechanical, and civil structures. Due to the nature of material, most damage in composites, such as delaminations, are always barely visible to the naked eye, which makes it difficult to detect and repair. The investigation of biological systems has inspired the development and characterization of self-healing composites. This paper presents the development of a new type of self-healing material in order to impede damage progression and conduct in-situ damage repair in composite structures. Carbon nanotubes, which are highly conductive materials, are mixed with shape memory polymer to develop self-healing capability. The developed polymeric material is applied to carbon fiber reinforced composites to automatically heal the delamination between different layers. The carbon fiber reinforced composite laminates are manufactured using high pressure molding techniques. Tensile loading is applied to double cantilever beam specimens using an MTS hydraulic test frame. A direct current power source is used to generate heat within the damaged area. The application of thermal energy leads to re-crosslinking in shape memory polymers. Experimental results showed that the developed composite materials are capable of healing the matrix cracks and delaminations in the bonded areas of the test specimens. The developed self-healing material has the potential to be used as a novel structural material in mechanical, civil, aerospace applications.

A micromorphic model for steel fiber reinforced concrete.

PubMed

Oliver, J; Mora, D F; Huespe, A E; Weyler, R

2012-10-15

A new formulation to model the mechanical behavior of high performance fiber reinforced cement composites with arbitrarily oriented short fibers is presented. The formulation can be considered as a two scale approach, in which the macroscopic model, at the structural level, takes into account the mesostructural phenomenon associated with the fiber-matrix interface bond/slip process. This phenomenon is contemplated by including, in the macroscopic description, a micromorphic field representing the relative fiber-cement displacement. Then, the theoretical framework, from which the governing equations of the problem are derived, can be assimilated to a specific case of the material multifield theory. The balance equation derived for this model, connecting the micro stresses with the micromorphic forces, has a physical meaning related with the fiber-matrix bond slip mechanism. Differently to previous procedures in the literature, addressed to model fiber reinforced composites, where this equation has been added as an additional independent ingredient of the methodology, in the present approach it arises as a natural result derived from the multifield theory. Every component of the composite is defined with a specific free energy and constitutive relation. The mixture theory is adopted to define the overall free energy of the composite, which is assumed to be homogeneously constituted, in the sense that every infinitesimal volume is occupied by all the components in a proportion given by the corresponding volume fraction. The numerical model is assessed by means of a selected set of experiments that prove the viability of the present approach.

Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers.

PubMed

Monier, M; Ayad, D M; Sarhan, A A

2010-04-15

The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction. 2009 Elsevier B.V. All rights reserved.

The weathering effect in natural environment on hybrid kenaf/glass fiber unsaturated polyester composite

NASA Astrophysics Data System (ADS)

Rozyanty, A. R.; Mohammed, M. M.; Musa, L.; Shahnaz, S. B. S.; Zuliahani, A.

2017-04-01

Kenaf and glass fiber hybrid composite was prepared by using hand lay-up process. The effect of weather on mechanical properties of kenaf/glass fiber hybrid composites was studied. The hybrid composite samples were exposed to natural weather. Tensile test was performed for samples at different weathering exposure time. Tensile strength of kenaf/glass fiber hybrid composite was 70.9 MPa and tensile modulus was at 30 GPa before expose to environment weather. Unfortunately, mechanical properties of hybrid composite decreased as exposure time increase due to the moisture absorption which further promotes weakness in interfacial bonding.

Nano polypeptide particles reinforced polymer composite fibers.

PubMed

Li, Jiashen; Li, Yi; Zhang, Jing; Li, Gang; Liu, Xuan; Li, Zhi; Liu, Xuqing; Han, Yanxia; Zhao, Zheng

2015-02-25

Because of the intensified competition of land resources for growing food and natural textile fibers, there is an urgent need to reuse and recycle the consumed/wasted natural fibers as regenerated green materials. Although polypeptide was extracted from wool by alkaline hydrolysis, the size of the polypeptide fragments could be reduced to nanoscale. The wool polypeptide particles were fragile and could be crushed down to nano size again and dispersed evenly among polymer matrix under melt extrusion condition. The nano polypeptide particles could reinforce antiultraviolet capability, moisture regain, and mechanical properties of the polymer-polypeptide composite fibers.

Chemical and Physical Properties, Safety and Application of Partially Hydrolized Guar Gum as Dietary Fiber

PubMed Central

Yoon, Seon-Joo; Chu, Djong-Chi; Raj Juneja, Lekh

2008-01-01

The ideal water-soluble dietary fiber for the fiber-enrichment of foods must be very low in viscosity, tasteless, odorless, and should produce clear solutions in beverages. Partially hydrolyzed guar gum (PHGG) produced from guar gum by enzymatic process has the same chemical structure with intact guar gum but less than one-tenth the original molecular length of guar gum, which make available to be used as film former, foam stabilizer and swelling agent. The viscosity of PHGG is about 10 mPa·s in 5% aqueous solution, whereas 1% solution of guar gum shows range from 2,000 to 3,000 mPa·s. In addition, PHGG is greatly stable against low pH, heat, acid and digestive enzyme. For these reasons, PHGG seems to be one of the most beneficial dietary fiber materials. It also showed that interesting physiological functions still fully exert the nutritional function of a dietary fiber. PHGG has, therefore, been used primarily for a nutritional purpose and became fully integrated food material without altering the rheology, taste, texture and color of final products. PHGG named as Benefiber® in USA has self-affirmation on GRAS status of standard grade PHGG. PHGG named as Sunfiber® is now being used in various beverages, food products and medicinal foods as a safe, natural and functional dietary fiber in all over the world. PMID:18231623

Fast response Fabry-Perot interferometer microfluidic refractive index fiber sensor based on concave-core photonic crystal fiber.

PubMed

Tian, Jiajun; Lu, Zejin; Quan, Mingran; Jiao, Yuzhu; Yao, Yong

2016-09-05

We report a fast response microfluidic Fabry-Perot (FP) interferometer refractive index (RI) fiber sensor based on a concave-core photonic crystal fiber (CPCF), which is formed by directly splicing a section CPCF with a section of single mode fiber. The CPCF is made by cleaving a section of multimode photonic crystal fiber with an axial tension. The shallow concave-core of CPCF naturally forms the FP cavity with a very short cavity length. The inherent large air holes in the cladding of CPCF are used as the open channels to let liquid sample come in and out of FP cavity. In order to shorten the liquid channel length and eliminate the harmful reflection from the outside end face of the CPCF, the CPCF is cleaved with a tilted tensile force. Due to the very small cavity capacity, the short length and the large sectional area of the microfluidic channels, the proposed sensor provides an easy-in and easy-out structure for liquids, leading to great decrement of the measuring time. The proposed sensor exhibits fast measuring speed, the measuring time is less than 359 and 23 ms for distilled water and pure ethanol, respectively. We also experimentally study and demonstrate the superior performances of the sensor in terms of high RI sensitivity, good linear response, low temperature cross-sensitivity and easy fabrication.

Control performance of paper-based blood analysis devices through paper structure design.

PubMed

Li, Lizi; Huang, Xiaolei; Liu, Wen; Shen, Wei

2014-12-10

In this work, we investigated the influence of paper structure on the performance of paper-based analytical devices that are used for blood analysis. The question that we aimed to answer is how the fiber type (i.e., softwood and hardwood fibers) influences the fiber network structure of the paper, which affects the transport of red blood cells (RBCs) in paper. In the experimental design, we isolated the influence of fiber types on the paper structure from all other possible influencing factors by removing the fines from the pulps and not using any additives. Mercury porosimetry was employed to characterize the pore structures of the paper sheets. The results show that papers with a low basis weight that are made with short hardwood fibers have a higher porosity (i.e., void fraction) and simpler pore structures compared with papers made with long softwood fibers. RBC transport in paper carried by saline solution was investigated in two modes: lateral chromatographic elution and vertical flow-through. The results showed that the complexity of the paper's internal pore structure has a dominant influence on the transport of RBCs in paper. Hardwood fiber sheets with a low basis weight have a simple internal pore structure and allow for the easy transport of RBCs. Blood-typing sensors built with low basis weight hardwood fibers deliver high-clarity assays. Softwood fiber papers are found to have a more complex pore structure, which makes RBC transport more difficult, leading to blood-typing results of low clarity. This study provides the principle of paper sheet design for paper-based blood analysis sensors.

Thermal Strain Analysis of Optic Fiber Sensors

PubMed Central

Her, Shiuh-Chuan; Huang, Chih-Ying

2013-01-01

An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating. PMID:23385407

Mechanically induced long period fiber gratings in Er3+ fiber for structural health monitoring

NASA Astrophysics Data System (ADS)

Pulido-Navarro, M. G.; Alvarez-Chavez, J. A.; Ceballos-Herrera, D. E.; Escamilla-Ambrosio, P. J.

2013-09-01

This work presents preliminary results on wavelength sensitivity due to mechanically induced long period fiber grating (LPFG) on both standard single-mode and Er-doped fibers. The work presents and compares results for both types of fibers under different torsion conditions. In order to apply the torsion one of the fiber ends is fixed while torsion is applied on the other end. A LPFG whose period is 503μm is used to press on the fiber after the torsion, this will allow for micro curvatures to be formed on the fiber, which will in turn generate a periodical index perturbation on it. Here, it was noted that the rejection band shifts to shorter wavelengths for Er-doped fibers. It was detected that for torsion of 6 turns applied to 10cm doped fiber the wavelength peaks can shift up to 25nm, which is longer than similar results reported on standard fibers. Therefore, by using Er-doped fibers this technique will give more sensitive and accurate results on the real conditions of the structure under study. These results can be employed for sensing applications, especially for small to medium size structures, being these structures mechanical, civil or aeronautical. Theoretical calculations and simulations are employed for experimental results validation.

Carbon fiber polymer-matrix structural composites tailored for multifunctionality by filler incorporation

NASA Astrophysics Data System (ADS)

Han, Seungjin

This dissertation provides multifunctional carbon fiber polymer-matrix structural composites for vibration damping, thermal conduction and thermoelectricity. Specifically, (i) it has strengthened and stiffened carbon fiber polymer-matrix structural composites by the incorporation of halloysite nanotubes, carbon nanotubes and silicon carbide whiskers, (ii) it has improved mechanical energy dissipation using carbon fiber polymer-matrix structural composites with filler incorporation, (iii) it has increased the through-thickness thermal conductivity of carbon fiber polymer-matrix composite by curing pressure increase and filler incorporation, and (iv) it has enhanced the thermoelectric behavior of carbon fiber polymer-matrix structural composites. Low-cost natural halloysite nanotubes (0.1 microm diameter) were effective for strengthening and stiffening continuous fiber polymer-matrix composites, as shown for crossply carbon fiber (5 microm diameter, ˜59 vol.%) epoxy-matrix composites under flexure, giving 17% increase in strength, 11% increase in modulus and 21% decrease in ductility. They were less effective than expensive multiwalled carbon nanotubes (0.02 microm diameter), which gave 25% increase in strength, 11% increase in modulus and 14% decrease in ductility. However, they were more effective than expensive silicon carbide whiskers (1 microm diameter), which gave 15% increase in strength, 9% increase in modulus and 20% decrease in ductility. Each filler, at ˜2 vol.%, was incorporated in the composite at every interlaminar interface by fiber prepreg surface modification. The flexural strength increase due to halloysite nanotubes incorporation related to the interlaminar shear strength increase. The measured values of the composite modulus agreed roughly with the calculated values based on the Rule of Mixtures. Continuous carbon fiber composites with enhanced vibration damping under flexure are provided by incorporation of fillers between the laminae. Exfoliated graphite (EG) as a sole filler is more effective than carbon nanotube (SWCNT/MWCNT), halloysite nanotube (HNT) or nanoclay as sole fillers in enhancing the loss tangent, if the curing pressure is 2.0 (not 0.5) MPa. The MWCNT, SiC whisker and halloysite nanotube as sole fillers are effective for increasing the storage modulus. The combined use of a storage-modulus-enhancing filler (CNT, SiC whisker or HNT) and a loss-tangent-enhancing filler (EG or nanoclay) gives the best performance. With EG, HNT and 2.0-MPa curing, the loss modulus is increased by 110%, while the flexural strength is decreased by 14% and the flexural modulus is not affected. With nanoclay, HNT and 0.5-MPa curing, the loss modulus is increased by 96%, while the flexural strength and modulus are essentially not affected. The low through-thickness thermal conductivity limits heat dissipation from continuous carbon fiber polymer-matrix composites. This conductivity is increased by up to 60% by raising the curing pressure from 0.1 to 2.0 MPa and up to 33% by incorporation of a filler (61.5 vol.%) at the interlaminar interface. The thermal resistivity is dominated by the lamina resistivity (which is contributed substantially by the intralaminar fiber--fiber interfacial resistivity), with the interlaminar interface thermal resistivity being unexpectedly negligible. The lamina resistivity and intralaminar fiber-fiber interfacial resistivity are decreased by up to 56% by raising the curing pressure and up to 36% by filler incorporation. Thermoelectric structural materials are potentially attractive for large-scale energy harvesting. Through filler incorporation and unprecedented decoupling of the bulk (laminae) and interfacial (interlaminar interfaces) contributions to the Seebeck voltage (through-thickness Seebeck voltage of a crossply continuous carbon fiber/epoxy composite laminate), this work provides thermoelectric power magnitudes at ˜70°C up to 110, 1670 and 11000 microV/K for the laminate, a lamina and an interlaminar interface respectively. The interface provides an apparent thermoelectric effect due to carrier backflow. The interfacial voltage is opposite in sign from the laminate and lamina voltages and is slightly lower in magnitude than the lamina voltage. The through-thickness thermoelectric behavior of continuous carbon fiber epoxy-matrix structural composites has been greatly improved by the use of tellurium particles (13 vol.% of composite), bismuth telluride particles (2 vol.%) and carbon black (2 vol.%) at the interlaminar interface. The thermoelectric power is increased from 8 to 163 microV/K, while the electrical resistivity is decreased from 0.17 to 0.02 O.cm, the thermal conductivity is decreased from 1.31 to 0.51 W/m.K, and the dimensionless thermoelectric figure of merit ZT at 70°C is increased from 9 x 10-6 to 9 x 10-2. Decrease in the curing pressure from 4.0 to 0.5 MPa decreases ZT slightly, mainly due to the increase in electrical resistivity.

Multi-channel measurement for hetero-core optical fiber sensor by using CMOS camera

NASA Astrophysics Data System (ADS)

Koyama, Yuya; Nishiyama, Michiko; Watanabe, Kazuhiro

2015-07-01

Fiber optic smart structures have been developed over several decades by the recent fiber optic sensor technology. Optical intensity-based sensors, which use LD or LEDs, can be suitable for the monitor system to be simple and cost effective. In this paper, a novel fiber optic smart structure with human-like perception has been demonstrated by using intensity-based hetero-core optical fiber sensors system with the CMOS detector. The optical intensity from the hetero-core optical fiber bend sensor is obtained as luminance spots indicated by the optical power distributions. A number of optical intensity spots are simultaneously readout by taking a picture of luminance pattern. To recognize the state of fiber optic smart structure with the hetero-core optical fibers, the template matching process is employed with Sum of Absolute Differences (SAD). A fiber optic smart glove having five optic fiber nerves have been employed to monitor hand postures. Three kinds of hand postures have been recognized by means of the template matching process. A body posture monitoring has also been developed by placing the wearable hetero-core optical fiber bend sensors on the body segments. In order for the CMOS system to be a human brain-like, the luminescent spots in the obtained picture were arranged to make the pattern corresponding to the position of body segments. As a result, it was successfully demonstrated that the proposed fiber optic smart structure could recognize eight kinds of body postures. The developed system will give a capability of human brain-like processing to the existing fiber optic smart structures.

Manufacturing of Smart Structures Using Fiber Placement Manufacturing Processes

NASA Technical Reports Server (NTRS)

Thomas, Matthew M.; Glowasky, Robert A.; McIlroy, Bruce E.; Story, Todd A.

1996-01-01

Smart structures research and development, with the ultimate aim of rapid commercial and military production of these structures, are at the forefront of the Synthesis and Processing of Intelligent Cost-Effective Structures (SPICES) program. As part of this ARPA-sponsored program, MDA-E is using fiber placement processes to manufacture integrated smart structure systems. These systems comprise advanced composite structures with embedded fiber optic sensors, shape memory alloys, piezoelectric actuators, and miniature accelerometers. Cost-effective approaches and solutions to smart material synthesis in the fiber-placement process, based upon integrated product development, are discussed herein.

Infrared Fibers for Use in Space-Based Smart Structures

NASA Technical Reports Server (NTRS)

Tucker, Dennis S.; Nettles, Alan T.; Brantley, Lott W. (Technical Monitor)

2001-01-01

Infrared optical fibers are finding a number of applications including laser surgery, remote sensing, and nuclear radiation resistant links. Utilizing these fibers in space-based structures is another application, which can be exploited. Acoustic and thermal sensing are two areas in which these fibers could be utilized. In particular, fibers could be embedded in IM7/8552 toughened epoxy and incorporated into space structures both external and internal. ZBLAN optical fibers are a candidate, which have been studied extensively over the past 20 years for terrestrial applications. For the past seven years the effects of gravity on the crystallization behavior of ZBLAN optical fiber has been studied. It has been found that ZBLAN crystallization is suppressed in microgravity. This lack of crystallization leads to a fiber with better transmission characteristics than its terrestrial counterpart.

Validation of In utero Tractography of Human Fetal Commissural and Internal Capsule Fibers with Histological Structure Tensor Analysis

PubMed Central

Mitter, Christian; Jakab, András; Brugger, Peter C.; Ricken, Gerda; Gruber, Gerlinde M.; Bettelheim, Dieter; Scharrer, Anke; Langs, Georg; Hainfellner, Johannes A.; Prayer, Daniela; Kasprian, Gregor

2015-01-01

Diffusion tensor imaging (DTI) and tractography offer the unique possibility to visualize the developing white matter macroanatomy of the human fetal brain in vivo and in utero and are currently under investigation for their potential use in the diagnosis of developmental pathologies of the human central nervous system. However, in order to establish in utero DTI as a clinical imaging tool, an independent comparison between macroscopic imaging and microscopic histology data in the same subject is needed. The present study aimed to cross-validate normal as well as abnormal in utero tractography results of commissural and internal capsule fibers in human fetal brains using postmortem histological structure tensor (ST) analysis. In utero tractography findings from two structurally unremarkable and five abnormal fetal brains were compared to the results of postmortem ST analysis applied to digitalized whole hemisphere sections of the same subjects. An approach to perform ST-based deterministic tractography in histological sections was implemented to overcome limitations in correlating in utero tractography to postmortem histology data. ST analysis and histology-based tractography of fetal brain sections enabled the direct assessment of the anisotropic organization and main fiber orientation of fetal telencephalic layers on a micro- and macroscopic scale, and validated in utero tractography results of corpus callosum and internal capsule fiber tracts. Cross-validation of abnormal in utero tractography results could be achieved in four subjects with agenesis of the corpus callosum (ACC) and in two cases with malformations of internal capsule fibers. In addition, potential limitations of current DTI-based in utero tractography could be demonstrated in several brain regions. Combining the three-dimensional nature of DTI-based in utero tractography with the microscopic resolution provided by histological ST analysis may ultimately facilitate a more complete morphologic characterization of axon guidance disorders at prenatal stages of human brain development. PMID:26732460

Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures

NASA Technical Reports Server (NTRS)

Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

2013-01-01

Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

Structure-based discovery of fiber-binding compounds that reduce the cytotoxicity of amyloid beta

DOE PAGES

Jiang, Lin; Liu, Cong; Leibly, David; ...

2013-07-16

Amyloid protein aggregates are associated with dozens of devastating diseases including Alzheimer’s, Parkinson’s, ALS, and diabetes type 2. While structure-based discovery of compounds has been effective in combating numerous infectious and metabolic diseases, ignorance of amyloid structure has hindered similar approaches to amyloid disease. Here we show that knowledge of the atomic structure of one of the adhesive, steric-zipper segments of the amyloid-beta (Aβ) protein of Alzheimer’s disease, when coupled with computational methods, identifies eight diverse but mainly flat compounds and three compound derivatives that reduce Aβ cytotoxicity against mammalian cells by up to 90%. Although these compounds bind tomore » Aβ fibers, they do not reduce fiber formation of Aβ. Structure-activity relationship studies of the fiber-binding compounds and their derivatives suggest that compound binding increases fiber stability and decreases fiber toxicity, perhaps by shifting the equilibrium of Aβ from oligomers to fibers.« less

Micro-poromechanics model of fluid-saturated chemically active fibrous media.

PubMed

Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2015-02-01

We have developed a micromechanics based model for chemically active saturated fibrous media that incorporates fiber network microstructure, chemical potential driven fluid flow, and micro-poromechanics. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's volume averaging. The advantage of this approach is that the resultant continuum model accounts for the discrete nature of the individual fibers while retaining a form suitable for porous materials. As a result, the model is able to predict the influence of micro-scale phenomena, such as the fiber pre-strain caused by osmotic effects and evolution of fiber network structure with loading, on the overall behavior and in particular, on the poromechanics parameters. Additionally, the model can describe fluid-flow related rate-dependent behavior under confined and unconfined conditions and varying chemical environments. The significance of the approach is demonstrated by simulating unconfined drained monotonic uniaxial compression under different surrounding fluid bath molarity, and fluid-flow related creep and relaxation at different loading-levels and different surrounding fluid bath molarity. The model predictions conform to the experimental observations for saturated soft fibrous materials. The method can potentially be extended to other porous materials such as bone, clays, foams and concrete.

Biohybrid Fibro-Porous Vascular Scaffolds: Effect of Crosslinking on Properties

PubMed Central

Nozik, Danna; Patel, Harsh; Singh, Raj K.; Vohra, Yogesh K.

2015-01-01

Tubular grafts were fabricated from blends of polycaprolactone (PCL) and poly(glycolide -co-caprolactone) (PGC) polymers and coated with an extracellular matrix containing collagens, laminin, and proteoglycans, but not growth factors (HuBiogel™). Multifunctional scaffolds from polymer blends and membrane proteins provide the necessary biomechanics and biological functions for tissue regeneration. Two crosslinking agents, a natural crosslinker namely genipin (Gp) and a carbodiimide reagent namely 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), were used for further stabilizing the protein matrix and the effect of crosslinking was evaluated for structural, morphological, mechanical properties using SEM, DSC and DMA. SEM images and fiber diameter distribution showed fiber-size between 0.2 µm to 1 µm with the majority of fiber diameters being under 500 nm, indicating upper range of protein fiber-sizes (for example, collagen fibers in extracellular matrix are in 50 to 500 nm diameter range). HB coating did not affect the mechanical properties, but increased its hydrophilicity of the graft. Overall data showed that PCL/PGC blends with 3:1 mass ratio exhibited mechanical properties comparable to those of human native arteries (tensile strength of 1–2 MPa and Young’s modulus of <10 MPa). Additionally, the effect of crosslinking on coating stability was investigated to assure the retention of proteins on scaffold for effective cell-matrix interactions. PMID:26082566

Biohybrid Fibro-Porous Vascular Scaffolds: Effect of Crosslinking on Properties.

PubMed

Thomas, Vinoy; Nozik, Danna; Patel, Harsh; Singh, Raj K; Vohra, Yogesh K

Tubular grafts were fabricated from blends of polycaprolactone (PCL) and poly(glycolide -co-caprolactone) (PGC) polymers and coated with an extracellular matrix containing collagens, laminin, and proteoglycans, but not growth factors (HuBiogel™). Multifunctional scaffolds from polymer blends and membrane proteins provide the necessary biomechanics and biological functions for tissue regeneration. Two crosslinking agents, a natural crosslinker namely genipin (Gp) and a carbodiimide reagent namely 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), were used for further stabilizing the protein matrix and the effect of crosslinking was evaluated for structural, morphological, mechanical properties using SEM, DSC and DMA. SEM images and fiber diameter distribution showed fiber-size between 0.2 µm to 1 µm with the majority of fiber diameters being under 500 nm, indicating upper range of protein fiber-sizes (for example, collagen fibers in extracellular matrix are in 50 to 500 nm diameter range). HB coating did not affect the mechanical properties, but increased its hydrophilicity of the graft. Overall data showed that PCL/PGC blends with 3:1 mass ratio exhibited mechanical properties comparable to those of human native arteries (tensile strength of 1-2 MPa and Young's modulus of <10 MPa). Additionally, the effect of crosslinking on coating stability was investigated to assure the retention of proteins on scaffold for effective cell-matrix interactions.

Reinforcing and Toughening Effects of Bamboo Pulp Fiber on Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Fiber Composites.

USDA-ARS?s Scientific Manuscript database

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/bamboo pulp fiber composites were melt-compounded and injection-molded. Tensile, impact and dynamic mechanical properties of the composites were studied. In contrast to many other short natural fiber reinforced biocomposites which demonstrate decre...

Molecular development of the mid-stage elongating cotton fiber

USDA-ARS?s Scientific Manuscript database

Cotton fiber is one of the leading natural textile fibers and is the leading value added crop in the USA. The annual business revenue from the cotton industry exceeds $120 billion. The growth of the cotton fiber is divided into four unique, yet overlapping stages; initiation, elongation, secondary w...

Miniature spinning: an improved cotton research tools

USDA-ARS?s Scientific Manuscript database

Cotton is a natural fiber and is highly variable. Researchers need to evaluate cotton fiber properties to aid in the development of improved varieties and to ensure that changes in agronomic practices do not harm fiber quality or processing propensity. There is a need for fiber quality evaluation be...

Natural sisal fibers derived hierarchical porous activated carbon as capacitive material in lithium ion capacitor

NASA Astrophysics Data System (ADS)

Yang, Zhewei; Guo, Huajun; Li, Xinhai; Wang, Zhixing; Yan, Zhiliang; Wang, Yansen

2016-10-01

Lithium-ion capacitor (LIC) is a novel advanced electrochemical energy storage (EES) system bridging gap between lithium ion battery (LIB) and electrochemical capacitor (ECC). In this work, we report that sisal fiber activated carbon (SFAC) was synthesized by hydrothermal treatment followed by KOH activation and served as capacitive material in LIC for the first time. Different particle structure, morphology, specific surface area and heteroatoms affected the electrochemical performance of as-prepared materials and corresponding LICs. When the mass ratio of KOH to char precursor was 2, hierarchical porous structured SFAC-2 was prepared and exhibited moderate specific capacitance (103 F g-1 at 0.1 A g-1), superior rate capability and cyclic stability (88% capacity retention after 5000 cycles at 1 A g-1). The corresponding assembled LIC (LIC-SC2) with optimal comprehensive electrochemical performance, displayed the energy density of 83 Wh kg-1, the power density of 5718 W kg-1 and superior cyclic stability (92% energy density retention after 1000 cycles at 0.5 A g-1). It is worthwhile that the source for activated carbon is a natural and renewable one and the synthesis method is eco-friendly, which facilitate that hierarchical porous activated carbon has potential applications in the field of LIC and other energy storage systems.

Facile fabrication of aloe vera containing PCL nanofibers for barrier membrane application.

PubMed

Carter, Princeton; Rahman, Shekh M; Bhattarai, Narayan

2016-01-01

Guided tissue regeneration (GTR) is a widely used method in dental surgical procedures that utilizes a barrier membrane to exclude migration of epithelium and ensure repopulation of periodontal ligament cells at the sites having insufficient gingiva. Commercial GTR membranes are typically composed of synthetic polymers that have had mild clinical success mostly because of their lack of proper bioactivity and appropriate degradation profile. In this study, a natural polymer, aloe vera was blended with polycaprolactone (PCL) to create nanofibrous GTR membranes by electrospinning. Aloe vera has proven anti-inflammatory properties and enhances the regeneration of periodontium tissues. PCL, a synthetic polymer, is well known to produce miscible polyblends nanofibers with natural polymers. Nanofibrous membranes with varying composition of PCL to aloe vera were fabricated, and several physicochemical and biological properties, such as fiber morphology, wettability, chemical structure, mechanical strength, and cellular compatibility of the membranes were analyzed. PCL/aloe vera membranes with ratios from 100/00 to 70/30 showed good uniformity in fiber morphology and suitable mechanical properties, and retained the integrity of their fibrous structure in aqueous solutions. Experimental results, using cell viability assay and cell attachment observation, showed that the nanofibrous membranes support 3T3 cell viability and could be a potential candidate for GTR therapy.

Froth conductivity for in situ monitoring of fiber (solid) and wet rejects in flotation deinking

Treesearch

J. Y. Zhu; M. Fleischmann; R. Gleisner

2006-01-01

Reduced fiber rejection in flotation deinking is very important to reduce the cost of secondary fibers in paper recycling and to conserve natural resources. Online monitoring of fiber rejection is a prerequisite to achieving process control for the reduction of fiber rejection in flotation deinking. It also can improve understanding of the effects of various operating...

Recent Trends in Sustainable Textile Waste Recycling Methods: Current Situation and Future Prospects.

PubMed

Pensupa, Nattha; Leu, Shao-Yuan; Hu, Yunzi; Du, Chenyu; Liu, Hao; Jing, Houde; Wang, Huaimin; Lin, Carol Sze Ki

2017-08-16

In recent years, there have been increasing concerns in the disposal of textile waste around the globe. The growth of textile markets not only depends on population growth but also depends on economic and fashion cycles. The fast fashion cycle in the textile industry has led to a high level of consumption and waste generation. This can cause a negative environmental impact since the textile and clothing industry is one of the most polluting industries. Textile manufacturing is a chemical-intensive process and requires a high volume of water throughout its operations. Wastewater and fiber wastes are the major wastes generated during the textile production process. On the other hand, the fiber waste was mainly created from unwanted clothes in the textile supply chain. This fiber waste includes natural fiber, synthetic fiber, and natural/synthetic blends. The natural fiber is mostly comprised of cellulosic material, which can be used as a resource for producing bio-based products. The main challenge for utilization of textile waste is finding the method that is able to recover sugars as monosaccharides. This review provides an overview of valorization of textile waste to value-added products, as well as an overview of different strategies for sugar recovery from cellulosic fiber and their hindrances.

Characterization, Long-Term Behavior Evaluation and Thermomechanical Properties of Untreated and Treated Flax Fiber-Reinforced Composites

NASA Astrophysics Data System (ADS)

Amiri, Ali

In recent years there has been a resurgence of interest in the usage of natural fiber reinforced composites in more advanced structural applications. Consequently, the need for improving their mechanical properties as well as service life and long-term behavior modeling and predictions has arisen. In a step towards further development of these materials, in this study, two newly developed biobased resins, derived from soybean oil, methacrylated epoxidized sucrose soyate and double methacrylated epoxidized sucrose soyate are combined with untreated and alkaline treated flax fiber to produce novel biocomposites. Vinyl ester reinforced with flax fiber is used as control in addition to comparing properties of biobased composites against commercial pultruded composites. Effects of alkaline treatment of flax fiber as well as addition of 1% acrylic resin to vinyl ester and the two mentioned biobased resins on mechanical properties are studied. Properties are evaluated in short-term and also, after being exposed to accelerated weathering (i.e. UV and moisture). Moreover, long-term creep of these novel biobased composites and effect of fiber and matrix treatment on viscoelastic behavior is investigated using Time-temperature superposition (TTS) principle. Based on the results of this study, the TTS provides an accelerated method for evaluation of mechanical properties of biobased composites, and satisfactory master curves are achieved by use of this principle. Also, fiber and matrix treatments were effective in increasing mechanical properties of biobased composites in short-term, and treatments delayed the creep response and slowed the process of creep in composites under study in the steady state region. Overall, results of this study reveal the successful production of biocomposites having properties that meet or exceed those of conventional pultruded members while maintaining high biocontent. Composites using treated flax fiber and newly developed resins showed less degradation in properties after accelerated weather exposure. Procedures and methods developed throughout this study, as well as results presented are essential to further development of these novel materials and utilizing them in more advanced structural applications. Results presented in this dissertation have been published as 5 peer reviewed journal articles, 2 book chapters and have been presented in 6 national and international conferences.

Natural fiber production, harvesting, and preliminary processing: options and opportunities

USDA-ARS?s Scientific Manuscript database

The utilization of natural fibers and plant oils in bio-products introduces numerous logistical challenges not typically encountered with non-agricultural resources. Once it has been determined that a plant material is suitable for commercial development, the production, harvesting, and processing s...

Structure of bacteriophage [phi]29 head fibers has a supercoiled triple repeating helix-turn-helix motif

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

Xiang, Ye; Rossmann, Michael G.

2011-12-22

The tailed bacteriophage {phi}29 capsid is decorated with 55 fibers attached to quasi-3-fold symmetry positions. Each fiber is a homotrimer of gene product 8.5 (gp8.5) and consists of two major structural parts, a pseudohexagonal base and a protruding fibrous portion that is about 110 {angstrom} in length. The crystal structure of the C-terminal fibrous portion (residues 112-280) has been determined to a resolution of 1.6 {angstrom}. The structure is about 150 {angstrom} long and shows three distinct structural domains designated as head, neck, and stem. The stem region is a unique three-stranded helix-turn-helix supercoil that has not previously been described.more » When fitted into a cryoelectron microscope reconstruction of the virus, the head structure corresponded to a disconnected density at the distal end of the fiber and the neck structure was located in weak density connecting it to the fiber. Thin section studies of Bacillus subtilis cells infected with fibered or fiberless {phi}29 suggest that the fibers might enhance the attachment of the virions onto the host cell wall.« less

Distributed Fiber Optic Sensor for Early Detection of Rocky Slopes Movements

NASA Astrophysics Data System (ADS)

Minardo, Aldo; Picarelli, Luciano; Coscetta, Agnese; Zeni, Giovanni; Esposito, Giuseppe; Sacchi, Marco; Matano, Fabio; Caccavale, Mauro; Luigi, Zeni

2014-05-01

Distributed optical fiber sensors have in recent years gained considerable attention in structural and environmental monitoring due to specific advantages that, apart from the classical advantages common to all optical fiber sensors such as immunity to electromagnetic interferences, high sensitivity, small size and possibility to be embedded into the structures, multiplexing and remote interrogation capabilities [1], offer the unique feature of allowing the exploitation of a telecommunication grade optical fiber cable as the sensing element to measure deformation and temperature profiles over very long distances. In particular, distributed optical fiber sensors based on stimulated Brillouin scattering (SBS) through the so-called Brillouin Optical Time Domain Analysis (BOTDA), allow to measure strain and temperature profiles up to tens of kilometers with a strain accuracy of ±10µɛ and a temperature accuracy of ±1°C [2]. They have already been successfully employed in the monitoring of large civil and geotechnical structures such as bridges, tunnels, dams, pipelines allowing to identify and localize any kind of failures that can occur during their construction and operation [3,4]. In this paper we present the application of BOTDA to the monitoring of movements in a rocky slope, showing how the sensing optical fiber cable is able to detect the formation and follow the growth of fractures, and to identify their location along the slope, as well. The experimental results have been achieved on a test field located in the area of Naples (Italy), where a single mode optical fiber sensing cable has been deployed along a yellow tuffs slope, by spot gluing the cable with epoxy adhesive. In order to assess the validity of the proposed approach, a few existing cracks have been artificially enlarged and the magnitude and location of the induced strain peaks have been clearly identified by the sensing device. It should be emphasized that, due to the distributed nature of the sensor, no preliminary information about the possible displacement locations of rocks are required in advance. The sensing cable can be simply deployed in a zig-zag pattern path along the slope, for hundreds of meters, and the system will remotely detect and locate any displacements wherever they occur along the fiber cable path, so representing a powerful tool for early warning against possible rock slides. [1] J. M. López-Higuera, L. R. Cobo, A. Q. Incera, A. Cobo, " Fiber Optic Sensors in Structural Health Monitoring", Journal of Lightwave Technology, Vol. 29, pp.586-608, 2011. [2] A. Minardo, R. Bernini, L. Zeni, "Numerical analysis of single pulse and differential pulse-width pair BOTDA systems in the high spatial resolution regime", Optics Express, vol. 19, pp. 19233-19244, 2011. [3] A. Minardo, R. Bernini, L. Amato, L. Zeni, "Bridge monitoring using Brillouin fiber-optic sensors", IEEE Sensor Journal, Vol. 12 (1), pp. 145-150, 2012. [4] R. Bernini, A. Minardo, S. Ciaramella, V. Minutolo, L. Zeni, "Distributed strain measurement along a concrete beam via stimulated Brillouin scattering in optical fibers", International Journal of Geophysics, Vol. 2011, pp. 1-5, doi:10.1155/2011/710941, 2011.

Numerical investigation of porous materials composites reinforced with natural fibers

NASA Astrophysics Data System (ADS)

Chikhi, M.; Metidji, N.; Mokhtari, F.; Merzouk, N. k.

2018-05-01

The present article tends to predict the effective thermal properties of porous biocomposites materials. The composites matrix consists on porous materials namely gypsum and the reinforcement is a natural fiber as date palm fibers. The numerical study is done using Comsol software resolving the heat transfer equation. The results are fitted with theoretical model and experimental results. The results of this study indicate that the porosity has an effect on the Effective thermal conductivity biocompoites.

Effects on the Physical and Mechanical Properties of Porous Concrete for Plant Growth of Blast Furnace Slag, Natural Jute Fiber, and Styrene Butadiene Latex Using a Dry Mixing Manufacturing Process.

PubMed

Kim, Hwang-Hee; Kim, Chun-Soo; Jeon, Ji-Hong; Park, Chan-Gi

2016-01-29

To evaluate the effects of industrial by-products materials on the performance of porous concrete for plant growth, this study investigated the physical, strength, and freeze/thaw resistances of porous concrete for plant growth, prepared by replacing cement with blast furnace slag powder at 60% by weight, and replacing natural stone aggregates with coarse blast furnace slag aggregates at rates of 0%, 20%, 40%, 60% and 100% by weight. In addition, the effects of adding natural jute fiber and styrene butadiene ( SB) latex to these concrete mixtures were evaluated. The void ratio, compressive strength, and freeze/thaw resistance of the samples were measured. With increasing replacement rate of blast furnace aggregates, addition of latex, and mixing of natural jute fiber the void ratio of the concrete was increased. Compressive strength decreased as the replacement rate of blast-furnace slag aggregates increased. The compressive strength decreased after 100 freeze/thaw cycles, regardless of the replacement rate of blast furnace slag aggregates or of the addition of natural jute fiber and latex. The addition of natural jute fiber and latex decreased the compressive strength after 100 freeze/thaw cycles. The test results indicate that the control mixture satisfied the target compressive strength of 10 MPa and the target void ratio of 25% at replacement rates of 0% and 20% for blast furnace aggregates, and that the mixtures containing latex satisfied the criteria up to an aggregate replacement rate of 60%. However, the mixtures containing natural jute fiber did not satisfy these criteria. The relationship between void ratio and residual compressive strength after 100 freeze/thaw cycles indicates that the control mixture and the mixtures containing jute fiber at aggregate replacement rates of 20% and 40% satisfied the target void ratio of 25% and the target residual compressive strength of over 80% after 100 freeze/thaw cycles. The mixtures containing latex and aggregate replacement rates up to 60% satisfied the target void ratio and compressive strength.

Effects on the Physical and Mechanical Properties of Porous Concrete for Plant Growth of Blast Furnace Slag, Natural Jute Fiber, and Styrene Butadiene Latex Using a Dry Mixing Manufacturing Process

PubMed Central

Kim, Hwang-Hee; Kim, Chun-Soo; Jeon, Ji-Hong; Park, Chan-Gi

2016-01-01

To evaluate the effects of industrial by-products materials on the performance of porous concrete for plant growth, this study investigated the physical, strength, and freeze/thaw resistances of porous concrete for plant growth, prepared by replacing cement with blast furnace slag powder at 60% by weight, and replacing natural stone aggregates with coarse blast furnace slag aggregates at rates of 0%, 20%, 40%, 60% and 100% by weight. In addition, the effects of adding natural jute fiber and styrene butadiene (SB) latex to these concrete mixtures were evaluated. The void ratio, compressive strength, and freeze/thaw resistance of the samples were measured. With increasing replacement rate of blast furnace aggregates, addition of latex, and mixing of natural jute fiber the void ratio of the concrete was increased. Compressive strength decreased as the replacement rate of blast-furnace slag aggregates increased. The compressive strength decreased after 100 freeze/thaw cycles, regardless of the replacement rate of blast furnace slag aggregates or of the addition of natural jute fiber and latex. The addition of natural jute fiber and latex decreased the compressive strength after 100 freeze/thaw cycles. The test results indicate that the control mixture satisfied the target compressive strength of 10 MPa and the target void ratio of 25% at replacement rates of 0% and 20% for blast furnace aggregates, and that the mixtures containing latex satisfied the criteria up to an aggregate replacement rate of 60%. However, the mixtures containing natural jute fiber did not satisfy these criteria. The relationship between void ratio and residual compressive strength after 100 freeze/thaw cycles indicates that the control mixture and the mixtures containing jute fiber at aggregate replacement rates of 20% and 40% satisfied the target void ratio of 25% and the target residual compressive strength of over 80% after 100 freeze/thaw cycles. The mixtures containing latex and aggregate replacement rates up to 60% satisfied the target void ratio and compressive strength. PMID:28787883

Revealing pathologies in the liquid crystalline structures of the brain by polarimetric studies (Presentation Recording)

NASA Astrophysics Data System (ADS)

Bakhshetyan, Karen; Melkonyan, Gurgen G.; Galstian, Tigran V.; Saghatelyan, Armen

2015-10-01

Natural or "self" alignment of molecular complexes in living tissue represents many similarities with liquid crystals (LC), which are anisotropic liquids. The orientational characteristics of those complexes may be related to many important functional parameters and their study may reveal important pathologies. The know-how, accumulated thanks to the study of LC materials, may thus be used to this end. One of the traditionally used methods, to characterize those materials, is the polarized light imaging (PLI) that allows for label-free analysis of anisotropic structures in the brain tissue and can be used, for example, for the analysis of myelinated fiber bundles. In the current work, we first attempted to apply the PLI on the mouse histological brain sections to create a map of anisotropic structures using cross-polarizer transmission light. Then we implemented the PLI for comparative study of histological sections of human postmortem brain samples under normal and pathological conditions, such as Parkinson's disease (PD). Imaging the coronal, sagittal and horizontal sections of mouse brain allowed us to create a false color-coded fiber orientation map under polarized light. In human brain datasets for both control and PD groups we measured the pixel intensities in myelin-rich subregions of internal capsule and normalized these to non-myelinated background signal from putamen and caudate nucleus. Quantification of intensities revealed a statistically significant reduction of fiber intensity of PD compared to control subjects (2.801 +/- 0.303 and 3.724 +/- 0.07 respectively; *p < 0.05). Our study confirms the validity of PLI method for visualizing myelinated axonal fibers. This relatively simple technique can become a promising tool for study of neurodegenerative diseases where labeling-free imaging is an important benefit.

A numerical approach to model and predict the energy absorption and crush mechanics within a long-fiber composite crush tube

NASA Astrophysics Data System (ADS)

Pickett, Leon, Jr.

Past research has conclusively shown that long fiber structural composites possess superior specific energy absorption characteristics as compared to steel and aluminum structures. However, destructive physical testing of composites is very costly and time consuming. As a result, numerical solutions are desirable as an alternative to experimental testing. Up until this point, very little numerical work has been successful in predicting the energy absorption of composite crush structures. This research investigates the ability to use commercially available numerical modeling tools to approximate the energy absorption capability of long-fiber composite crush tubes. This study is significant because it provides a preliminary analysis of the suitability of LS-DYNA to numerically characterize the crushing behavior of a dynamic axial impact crushing event. Composite crushing theory suggests that there are several crushing mechanisms occurring during a composite crush event. This research evaluates the capability and suitability of employing, LS-DYNA, to simulate the dynamic crush event of an E-glass/epoxy cylindrical tube. The model employed is the composite "progressive failure model", a much more limited failure model when compared to the experimental failure events which naturally occur. This numerical model employs (1) matrix cracking, (2) compression, and (3) fiber breakage failure modes only. The motivation for the work comes from the need to reduce the significant cost associated with experimental trials. This research chronicles some preliminary efforts to better understand the mechanics essential in pursuit of this goal. The immediate goal is to begin to provide deeper understanding of a composite crush event and ultimately create a viable alternative to destructive testing of composite crush tubes.

Activated carbon fibers and engineered forms from renewable resources

DOEpatents

Baker, Frederick S

2013-02-19

A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

Activated carbon fibers and engineered forms from renewable resources

DOEpatents

Baker, Frederick S.

2010-06-01

A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

Electronic Conductivity in Biomimetic α-Helical Peptide Nanofibers and Gels.

PubMed

Ing, Nicole L; Spencer, Ryan K; Luong, Son H; Nguyen, Hung D; Hochbaum, Allon I

2018-03-27

Examples of long-range electronic conductivity are rare in biological systems. The observation of micrometer-scale electronic transport through protein wires produced by bacteria is therefore notable, providing an opportunity to study fundamental aspects of conduction through protein-based materials and natural inspiration for bioelectronics materials. Borrowing sequence and structural motifs from these conductive protein fibers, we designed self-assembling peptides that form electronically conductive nanofibers under aqueous conditions. Conductivity in these nanofibers is distinct for two reasons: first, they support electron transport over distances orders of magnitude greater than expected for proteins, and second, the conductivity is mediated entirely by amino acids lacking extended conjugation, π-stacking, or redox centers typical of existing organic and biohybrid semiconductors. Electrochemical transport measurements show that the fibers support ohmic electronic transport and a metallic-like temperature dependence of conductance in aqueous buffer. At higher solution concentrations, the peptide monomers form hydrogels, and comparisons of the structure and electronic properties of the nanofibers and gels highlight the critical roles of α-helical secondary structure and supramolecular ordering in supporting electronic conductivity in these materials. These findings suggest a structural basis for long-range electronic conduction mechanisms in peptide and protein biomaterials.

Application of lightweight materials in structure concept design of large-scale solar energy unmanned aerial vehicle

NASA Astrophysics Data System (ADS)

Zhang, Wei; Lv, Shengli; Guan, XiQi

2017-09-01

Carbon fiber composites and film materials can be effectively used in light aircraft structures, especially for solar unmanned aerial vehicles. The use of light materials can reduce the weight of the aircraft, but also can effectively improve the aircraft's strength and stiffness. The structure of the large aspect ratio solar energy UAV was analyzed in detail, taking Solar-impulse solar aircraft as an example. The solar energy UAV has a wing aspect ratio greater than 20, and the detailed digital model of the wing structure including beam, ribs and skin was built, also the Finite Element Method was applied to analyze the static and dynamic performance of the structure. The upper skin of the wing is covered with silicon solar cells, while the lower skin is light and transparent film. The single beam truss form of carbon fiber lightweight material is used in the wing structure. The wing beam is a box beam with rectangular cross sections. The box beam connected the front parts and after parts of the ribs together. The fuselage of the aircraft was built by space truss structure. According to the static and dynamic analysis with Finite Element method, it was found that the aircraft has a small wingtip deflection relative to the wingspan in the level flight state. The first natural frequency of the wing structure is pretty low, which is closed to the gust load.

Fabrication and photoluminescence properties of graphite fiber/ZnO nanorod core-shell structures.

PubMed

Liu, Xianbin; Du, Hejun; Liu, Bo; Wang, Jianxiong; Sun, Xiao Wei; Sun, Handong

2011-08-01

Graphite fiber/ZnO nanorod core-shell structures were synthesized by thermal evaporation process. The core-shell hybrid architectures were comprised of ZnO nanorods grown on the surface of graphite fiber. In addition, Hollow ZnO hierarchical structure can be obtained by oxidizing the graphite fiber. Room temperature photoluminescence (PL) of the as-made graphite fiber/ZnO nanorod structures shows two UV peaks at around 3.274 eV and 3.181 eV. The temperature-dependent photoluminescence spectra demonstrate the two UV emissions are attributed to the intrinsic optical transitions and extrinsic defect-related emissions in ZnO. These hybrid structures may be used as the building block for fabrication of nanodevices.

New properties of a fiber optic sensor in application of a composite fence for critical infrastructure protection

NASA Astrophysics Data System (ADS)

Zyczkowski, M.; Szustakowski, M.; Markowski, P.

2015-09-01

This paper presents a new solution of using the composite fence with a novel fiber optic modalmetric sensor integrated within its structure. The modalmetric sensor is based on changes in a transverse modal field which is generated at the output of a multimode fiber. By a spatial limitation of the transverse modal field observation to its fragment thereof, changes' transformation in the modal distribution into changes of the output signal amplitude is made. Due to a constant analysis of the structure output signal, detection of an external disorder is possible. Integration of optical fibers with the fence structure allows for an accurate reproduction of the fence movement onto the optical fiber by significantly improving sensitivity of the modalmetric fiber sensor structure.

Interfacial contributions in lignocellulosic firber-reinforced polyurethane composites

Treesearch

Timothy G. Rials; Michael P. Wolcott; John M. Nassar

2001-01-01

Whereas lignocellulosic fibers have received considerable attention as a reinforcing agent in thermoplastic composites, their applicability to reactive polymer systems remains of considerable interest. The hydroxyl-rich nature of natural lignocellulosic fibers suggests that they are particularly useful in thermsetting systems such as polyurethanes. To further this...

Optimal Substitution of Cotton Burr and Linters in Thermoplastic Composites

USDA-ARS?s Scientific Manuscript database

A study was conducted to evaluate various substitutions of cotton burr and linters fractions of cotton gin waste (CGW) as a natural fiber source in ligno-cellulosic polymer composites (LCPC.) Samples were fabricated with approximately 50% natural fiber, 40% of high-density polyethylene (HDPE) powder...

Effect of gamma radiation on the mechanical properties of natural silk fiber and synthetic E-glass fiber reinforced polypropylene composites: A comparative study

NASA Astrophysics Data System (ADS)

Shubhra, Quazi T. H.; Alam, A. K. M. M.

2011-11-01

Silk is a strong natural proteinous fiber and E-glass is a very strong synthetic fiber. Compression molding method was used to fabricate B. mori silk fiber reinforced polypropylene (PP) matrix composites. The tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM) and impact strength (IS) of prepared composites were 55.1 MPa, 780 MPa, 56.3 MPa, 3450 MPa and 17 kJ/m 2, respectively. Synthetic E-glass fiber reinforced PP based composites were fabricated in the same way and TS, TM, BS, BM, IS of E-glass fiber reinforced polypropylene composites were found to be 128.7 MPa, 4350 MPa, 141.6 MPa, 6300 MPa and 19 kJ/m 2, respectively. Gamma radiation is high energy ionizing radiation and was applied to increase the mechanical properties of the composites. Application of gamma ray increases the mechanical properties of silk/PP composites to a greater extent than that of E-glass/PP composites.

Investigations of the mechanical properties of bi-layer and trilayer fiber reinforced composites

NASA Astrophysics Data System (ADS)

Jayakrishna, K.; Balasubramani, K.; Sultan, M. T. H.; Karthikeyan, S.

2016-10-01

Natural fibers are renewable raw materials with an environmental-friendly properties and they are recyclable. The mechanical properties of bi-layer and tri-layer thermoset polymer composites have been analyzed. The bi-layer composite consists of basalt and jute mats, while the tri-layer composite consists of basalt fiber, jute fiber and glass fiber mats. In both cases, the epoxy resin was used as the matrix and PTFE as a filler in the composites. The developed trilayer natural fiber composite can be used in various industrial applications such as automobile parts, construction and manufacturing. Furthermore, it also can be adopted in aircraft interior decoration and designed body parts. Flexural, impact, tensile, compression, shear and hardness tests, together with density measurement, were conducted to study the mechanical properties of both bi-layer and tri-layer composites. From the comparison, the tri-layer composite was found to perform in a better way in all tests.

Efficient Functionalization of Polyethylene Fibers for the Uranium Extraction from Seawater through Atom Transfer Radical Polymerization

DOE PAGES

Neti, Venkata S.; Das, Sadananda; Brown, Suree; ...

2017-08-29

Brush-on-brush structures are proposed as one method to overcome support effects in grafted polymers. Utilizing glycidyl methacrylate (GMA) grafted on polyethylene (PE) fibers using radiation-induced graft polymerization (RIGP) provides a hydrophilic surface on the hydrophobic PE. When integrated with atom transfer radical polymerization (ATRP), the grafting of acrylonitrile (AN) and hydroxyethyl acrylate (HEA) can be controlled and manipulated more easily than with RIGP. Poly(acrylonitrile)-co-poly(hydroxyethyl acrylate) chains were grown via ATRP on PE-GMA fibers to generate an adsorbent for the extraction of uranium from seawater. The prepared adsorbents in this study demonstrated promise (159.9 g-U/kg of adsorbent) in laboratory screening testsmore » using a high uranium concentration brine and 1.24 g-U/Kg of adsorbent in the filtered natural seawater in 21-days. Here, the modest capacity in 21-days exceeds previous efforts to generate brush-on-brush adsorbents by ATRP while manipulating the apparent surface hydrophilicity of the trunk material (PE).« less

Efficient Functionalization of Polyethylene Fibers for the Uranium Extraction from Seawater through Atom Transfer Radical Polymerization

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

Neti, Venkata S.; Das, Sadananda; Brown, Suree

Brush-on-brush structures are proposed as one method to overcome support effects in grafted polymers. Utilizing glycidyl methacrylate (GMA) grafted on polyethylene (PE) fibers using radiation-induced graft polymerization (RIGP) provides a hydrophilic surface on the hydrophobic PE. When integrated with atom transfer radical polymerization (ATRP), the grafting of acrylonitrile (AN) and hydroxyethyl acrylate (HEA) can be controlled and manipulated more easily than with RIGP. Poly(acrylonitrile)-co-poly(hydroxyethyl acrylate) chains were grown via ATRP on PE-GMA fibers to generate an adsorbent for the extraction of uranium from seawater. The prepared adsorbents in this study demonstrated promise (159.9 g-U/kg of adsorbent) in laboratory screening testsmore » using a high uranium concentration brine and 1.24 g-U/Kg of adsorbent in the filtered natural seawater in 21-days. Here, the modest capacity in 21-days exceeds previous efforts to generate brush-on-brush adsorbents by ATRP while manipulating the apparent surface hydrophilicity of the trunk material (PE).« less

Efficient Functionalization of Polyethylene Fibers for the Uranium Extraction from Seawater through Atom Transfer Radical Polymerization

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

Neti, Venkata S.; Das, Sadananda; Brown, Suree

Brush-on-brush structures are proposed as one method to overcome support effects in grafted polymers. Utilizing glycidyl methacrylate (GMA) grafted on polyethylene (PE) fibers using radiation-induced graft polymerization (RIGP) provides a hydrophilic surface on the hydrophobic PE. When integrated with atom transfer radical polymerization (ATRP), the grafting of acrylonitrile (AN) and hydroxyethyl acrylate (HEA) can be controlled and manipulated more easily than with RIGP. Poly(acrylonitrile)-co-poly(hydroxyethyl acrylate) chains were grown via ATRP on PE-GMA fibers to generate an adsorbent for the extraction of uranium from seawater. The prepared adsorbents in this study demonstrated promise (159.9 g- U/kg of adsorbent) in laboratory screeningmore » tests using a high uranium concentration brine and 1.24 g-U/Kg of adsorbent in the filtered natural seawater in 21-days. The modest capacity in 21- days exceeds previous efforts to generate brush-on-brush adsorbents by ATRP while manipulating the apparent surface hydrophilicity of the trunk material (PE).« less

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.

Fibers in the NGC 1333 proto-cluster

NASA Astrophysics Data System (ADS)

Hacar, A.; Tafalla, M.; Alves, J.

2017-10-01

Are the initial conditions for clustered star formation the same as for non-clustered star formation? To investigate the initial gas properties in young proto-clusters we carried out a comprehensive and high-sensitivity study of the internal structure, density, temperature, and kinematics of the dense gas content of the NGC 1333 region in Perseus, one of the nearest and best studied embedded clusters. The analysis of the gas velocities in the position-position-velocity space reveals an intricate underlying gas organization both in space and velocity. We identified a total of 14 velocity-coherent, (tran-)sonic structures within NGC 1333, with similar physical and kinematic properties than those quiescent, star-forming (aka fertile) fibers previously identified in low-mass star-forming clouds. These fibers are arranged in a complex spatial network, build-up the observed total column density, and contain the dense cores and protostars in this cloud. Our results demonstrate that the presence of fibers is not restricted to low-mass clouds but can be extended to regions of increasing mass and complexity. We propose that the observational dichotomy between clustered and non-clustered star-forming regions might be naturally explained by the distinct spatial density of fertile fibers in these environments. Based on observations carried out under project number 169-11 with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).Based on observations with the 100-m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie) at Effelsberg.Molecular line observations (spectral cubes) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A123

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.

The immature fiber mutant phenotype of cotton (Gossypium hirsutum) is linked to a 22-bp frame-shift deletion in a mitochondria targeted pentatricopeptide repeat gene

USDA-ARS?s Scientific Manuscript database

Cotton seed trichomes are the globally most important source of natural fibers. The major fiber thickness properties influence the price of the raw material and the quality of the finished product. The recessive immature fiber (im) gene reduces the degree of fiber cell wall thickening by a process...

FIBER-TEX 1992: The Sixth Conference on Advanced Engineering Fibers and Textile Structures for Composites

NASA Technical Reports Server (NTRS)

Buckley, John D. (Editor)

1993-01-01

The FIBER-TEX 1992 proceedings contain the papers presented at the conference held on 27-29 Oct. 1992 at Drexel University. The conference was held to create a forum to encourage an interrelationship of the various disciplines involved in the fabrication of materials, the types of equipment, and the processes used in the production of advanced composite structures. Topics discussed were advanced engineering fibers, textile processes and structures, structural fabric production, mechanics and characteristics of woven composites, and the latest requirements for the use of textiles in the production of composite materials and structures as related to global activities focused on textile structural composites.

Capturing Structural Heterogeneity in Chromatin Fibers.

PubMed

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

2017-10-13

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

Use of FTIR spectroscopy technique in the determination of cotton fiber maturity and crystallinity

USDA-ARS?s Scientific Manuscript database

Cotton fiber consists of natural cellulose I component and its end-use qualities depend on the amount of cellulose deposited during the growth. The term fiber maturity has been used to describe the degree of cellulosic development or the secondary cell wall thickening of fibers. Useful information a...

Tunable ultra-broadband polarization filter based on three-core resonance of the fluid-infiltrated and gold-coated photonic crystal fiber

NASA Astrophysics Data System (ADS)

Liu, Yingchao; Chen, Hailiang; Ma, Mingjian; Zhang, Wenxun; Wang, Yujun; Li, Shuguang

2018-03-01

We propose a tunable ultra-broadband polarization filter based on three-core resonance of the fluid-infiltrated and gold-coated high birefringent photonic crystal fiber (HB-PCF). Gold film was applied to the inner walls of two cladding air holes and surface plasmon polaritons were generated on its surface. The two gold-coated cladding air holes acted as two defective cores. As the phase matching condition was satisfied, light transmitted in the fiber core and coupled to the two defective cores. The three-core PCF supported three super modes in two orthogonal polarization directions. The coupling characteristics among these modes were investigated using the finite-element method. We found that the coupling wavelengths and strength between these guided modes can be tuned by altering the structural parameters of the designed HB-PCF, such as the size of the voids, thickness of the gold-films and liquid infilling pattern. Under the optimized structural parameters, a tunable broadband polarization filter was realized. For one liquid infilling pattern, we obtained a broadband polarization filter which filtered out the light in y-polarization direction at the wavelength of 1550 nm. For another liquid infilling pattern, we filtered out light in the x-polarization direction at the wavelength of 1310 nm. Our studies on the designed HB-PCF made contributions to the further devising of tunable broadband polarization filters, which are extensively used in telecommunication and sensor systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505175 and 61475134) and the Natural Science Foundation of Hebei Province (Grant Nos. F2017203110 and F2017203193).

FIBER-TEX 1991: The Fifth Conference on Advanced Engineering Fibers and Textile Structures for Composites

NASA Technical Reports Server (NTRS)

Buckley, John D. (Editor)

1992-01-01

This document is a compilation of papers presented at a joint NASA/North Carolina State University/DoD/Clemson University/Drexel University conference on Fibers, Textile Technology, and Composites Structures held at the College of Textiles Building on Centennial Campus of North Carolina State University, Raleigh, North Carolina on October 15-17, 1991. Conference papers presented information on advanced engineering fibers, textile processes and structures, structural fabric production, mechanics and characteristics of woven composites, pultruded composites, and the latest requirements for the use of textiles in the production of composite materials and structures.

Electrospinning Robot for Regenerative Coating of Implants

NASA Astrophysics Data System (ADS)

Gerstenhaber, Jonathan A.

Electrospinning of nanofibrous mats and scaffolds enables generation of scaffolding that is not only highly porous, but also has a structure that essentially mimics the natural basement membrane. As a result, the method has proliferated extensively, and is commonly used for diverse applications such as water filtration or tissue engineering, the latter of which may involve the use of natural or synthetic materials. Common laboratory scale electrospinning setups can be built inexpensively with merely a syringe pump, a high voltage supply, and an aluminum foil target. These systems, however, are limited to flat target surface geometries that span several centimeters. While a scaffold can be cut or folded to conform to a bone or other biological surface, spinning directly onto a surface with significant peaks and troughs results in poor fiber uniformity. Furthermore, if an alteration of fiber properties is preferred, the high voltage setup limits user access and customization of parameters during the spinning period. Finally, control of the electric field is compromised by the proximity of grounded electrical components. As its first aim, this project develops a robotic control system to enable custom coatings of arbitrary surfaces. By augmenting the traditional electrospinning system with a three-dimensional robotic control system, electric field focusing fibers, and additional aerodynamic forces terms 'electroblowing', the device can be produced across targets with strong topographic anisotropy. The second aim continues to enhance these attributes with biocompatible soy based scaffolds. Craniofacial implants are often complex in geometry, and conformal bandages are particularly hard to produce in these areas. Soy based scaffolds will be produced for 3D-printed replicas of these situations. Finally, the methods developed across this aim enables the development and use of a handheld electrospinning system that combines a coaxial high velocity air flow with the high voltage spinning element to reduce effects of operator error. The final goal of the thesis is to test whether fiber control successfully reduces effects of fiber anisotropy in vitro and to use the enhanced fiber control mechanisms to produce scaffolds with significant anisotropy, depositing aligned fibers at a target point to eventually enable generation of scaffolds with programmable variable spatial alignment similar to tendon. When completed, the systems described will enable custom production of coatings or scaffolds for functionality as scaffolding on medically relevant surfaces. Specifically, this means first, that scaffolds can be used with confidence to improve fixation even of non-cylindrical implants and enhance local tissue integration, and second, that implants can be customized with areas of 'guidance' fibers or local drug depots to either promote regeneration and population by surrounding tissue or mimic natural anisotropic cues necessary for mechanical or biological functionality.

Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

NASA Technical Reports Server (NTRS)

Tan, Seng; Zhou, Jian-guo

2013-01-01

Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

Natural light illumination system.

PubMed

Whang, Allen Jong-Woei; Chen, Yi-Yung; Yang, Shu-Hua; Pan, Po-Hsuan; Chou, Kao-Hsu; Lee, Yu-Chi; Lee, Zong-Yi; Chen, Chi-An; Chen, Cheng-Nan

2010-12-10

In recent years, green energy has undergone a lot of development and has been the subject of many applications. Many research studies have focused on illumination with sunlight as a means of saving energy and creating healthy lighting. Natural light illumination systems have collecting, transmitting, and lighting elements. Today, most daylight collectors use dynamic concentrators; these include Sun tracking systems. However, this design is too expensive to be cost effective. To create a low-cost collector that can be easily installed on a large building, we have designed a static concentrator, which is prismatic and cascadable, to collect sunlight for indoor illumination. The transmission component uses a large number of optical fibers. Because optical fibers are expensive, this means that most of the cost for the system will be related to transmission. In this paper, we also use a prismatic structure to design an optical coupler for coupling n to 1. With the n-to-1 coupler, the number of optical fibers necessary can be greatly reduced. Although this new natural light illumination system can effectively guide collected sunlight and send it to the basement or to other indoor places for healthy lighting, previously there has been no way to manage the collected sunlight when lighting was not desired. To solve this problem, we have designed an optical switch and a beam splitter to control and separate the transmitted light. When replacing traditional sources, the lighting should have similar characteristics, such as intensity distribution and geometric parameters, to those of traditional artificial sources. We have designed, simulated, and optimized an illumination lightpipe with a dot pattern to redistribute the collected sunlight from the natural light illumination system such that it equals the qualities of a traditional lighting system. We also provide an active lighting module that provides lighting from the natural light illumination system or LED auxiliary sources, depending on circumstances. The system is controlled by a light detector. We used optical simulation tools to design and simulate the efficiency of the active module. Finally, we used the natural light illumination system to provide natural illumination for a traffic tunnel. This system will provide a great number of benefits for the people who use it.

Digital holographic microtomography of fusion spliced optical fibers

NASA Astrophysics Data System (ADS)

Deng, Yating; Xiao, Wen; Ma, Xichao; Pan, Feng

2017-03-01

In this paper, we report three-dimensional(3D) measurement results of structural parameters of fusion spliced optical fibers using digital holographic microtomography. A holographic setup in microscopy configuration with the sample-fixed and setup-rotating scheme is established. A series of holograms is recorded from various incident angles. Then the filtered backprojection algorithm is applied to reconstruct the 3D refractive index (RI) distributions of the fusion spliced optical fibers inserted in the index-matching liquid. Experimental results exhibit the internal and external shapes of three kinds of fusion splices between different fibers, including a single-mode fiber(SMF) and a multimode fiber, an SMF and a panda polarization maintaining fiber (Panda PMF), and an SMF and a bow-tie polarization maintaining fiber (Bow-Tie PMF). With 3D maps of RI, it is intuitive to observe internal structural details of fused fibers and evaluate the splicing quality. This paper describes a powerful method for non-invasive microscopic measurement of fiber splicing. Furthermore, it provides the possibility of detecting fiber splicing loss by 3D structures.

Robust composite silk fibers pulled out of silkworms directly fed with nanoparticles.

PubMed

Wu, GuoHua; Song, Peng; Zhang, DongYang; Liu, ZeYu; Li, Long; Huang, HuiMing; Zhao, HongPing; Wang, NanNan; Zhu, YanQiu

2017-11-01

This paper reports the impacts of direct feeding silkworms with different nanoparticles (Cu, Fe, and TiO 2 ) on the morphology, structures, and mechanical properties of the resulting silk fiber (SF). The contents of the Cu nanoparticles were 38 times higher in the posterior silk glands and only 2-3 times higher in the SF and in the middle silk glands compared with the controlled groups. Significant changes of the surface morphology, structures, and diameter of the Cu nanoparticle fed SF have been observed, which are attributed to a slight SF protein reconstruction or conformational change in the mixture of silk fibroin and sericin in the silk glands. The resulting Cu-containing SF exhibits good tensile strength of 360MPa and reaches a strain of 38%, which are 89% and 36% higher than those of the natural SF. This study offers a new green strategy for the easy modification to achieve robust composite SF. Copyright © 2017 Elsevier B.V. All rights reserved.

Micro- and nano-CT textural analysis of an experimental volcanic fulgurite.

NASA Astrophysics Data System (ADS)

Cimarelli, Corrado; Yilmaz, Tim; Colombier, Mathieu; Villanova, Julie; Höfer, Lucas; Hess, Kai-Uwe; Ruthensteiner, Bernhard; Dingwell, Donald

2017-04-01

Fulgurites are natural glasses formed by cloud to ground lightning discharges causing rapid heating into rocks or unconsolidated sediments. Volcanic lightning can determine the re-melting and even ablation of newly formed or just deposited volcanic tephra during explosive eruptions. In this case the pristine material is already constituted by glass that can be further modified by the discharge. Although volcanic lightning discharges are generally less energetic than those produced by thunderclouds, the high temperatures reached by the lightning channel are well in excess of the low melting temperature of glass material. Here we have experimentally reproduced a fulgurite by single impulse voltage discharges (134 kV, 331 A, 10.5 J) on a target glass material. We have chosen borosilicate glass fibers (180 microns nominal length) as starting material to better account for the structural and chemical modification of the single particles after discharge-melting. The structure of the small fulgurite is best resolved through X-ray micro- and nano-computed tomography. Micro-CT analysis was carried out on a phoenix nanotom m with a voxelsize of 1 µm3. Additionally a 3D reconstruction with a voxel size of 150 nm3 has been analyzed at the new nano-analysis beamline ID16B at the ESRF. 3D analysis was carried out using Avizo 9.2 software, which allows non-destructive analysis of the fragile structure of the sample. The sample shows the channel-like structure typical for natural fulgurites with an inner void channel and internal wall constituted by the melted fibers. About 33% of the total solid volume of the fulgurite is melted to form the inner wall. The inner wall is characterized by nano- to micro-metric vesicles determined by volatile exsolution (mainly H2O) during the instantaneous heating and trapped in the low viscosity melt by the subsequent rapid quenching. Progressively outward the fulgurite shows the intricate delicate structure of the pristine glass fibers. Our results demonstrate that structural and chemical alteration of low viscosity glass material is possible by small impulse discharges with relatively low currents, thus reproducing a plausible scenario for electrical discharges during volcanic eruptions. Our experiment opens the opportunity for systematic constrained experimental investigation of the modification induced by volcanic lightning on tephra.

Composites from wood and plastics

Treesearch

Craig Clemons

2010-01-01

Composites made from thermoplastics and fillers or reinforcements derived from wood or other natural fibers are a dynamic research area encompassing a wide variety of composite materials. For example, as the use of biopolymers grows, wood and other natural fiber sources are being investigated as renewable sources of fillers and reinforcements to modify performance....

Theme--Achieving 2020. Goal 3: All Students Are Conversationally Literate in Agriculture, Food, Fiber, and Natural Resource Systems.

ERIC Educational Resources Information Center

Trexler, Cary, Ed.

2000-01-01

Nine theme articles focus on the need for students to be conversationally literate about agriculture, food, fiber, and natural resources systems. Discusses the definition of conversational literacy, the human and institutional resources needed, and exemplary models for promoting literacy. (JOW)

Mechanical properties and micro-morphology of fiber posts.

PubMed

Zicari, F; Coutinho, E; Scotti, R; Van Meerbeek, B; Naert, I

2013-04-01

To evaluate flexural properties of different fiber posts systems and to morphologically characterize their micro-structure. Six types of translucent fiber posts were selected: RelyX Post (3M ESPE), ParaPost Taper Lux (Colthéne-Whaledent), GC Fiber Post (GC), LuxaPost (DMG), FRC Postec Plus (Ivoclar-Vivadent), D.T. Light-Post (RTD). For each post system and size, ten specimens were subjected to a three-points bending test. Maximum fracture load, flexural strength and flexural modulus were determined using a universal loading device (5848 MicroTester(®), Instron). Besides, for each system, three intact posts of similar dimensions were processed for scanning electron microscopy to morphologically characterize the micro-structure. The following structural characteristics were analyzed: fibers/matrix ratio, density of fibers, diameter of fibers and distribution of fibers. Data were statistically analyzed with ANOVA. Type and diameter of posts were found to significantly affect the fracture load, flexural strength and flexural modulus (p<0.05). Regarding maximum fracture load, it was found to increase with post diameter, in each post system (p<0.001). Regarding flexural strength and flexural modulus, the highest values were recorded for posts with the smallest diameter (p<0.001). Finally, structural characteristics significantly varied among the post systems tested. However, any correlation has been found between flexural strength and structural characteristics. Flexural strength appeared not to be correlated to structural characteristics of fiber posts, but it may rather be affected by mechanical properties of the resin matrix and the interfacial adhesion between fibers and resin matrix. Copyright © 2013. Published by Elsevier Ltd.

Crash-Energy Absorbing Composite Structure and Method of Fabrication

NASA Technical Reports Server (NTRS)

Kellas, Sotiris (Inventor); Carden, Huey D. (Inventor)

1996-01-01

A stand-alone, crash-energy absorbing structure and fabrication method are provided. A plurality of adjoining rigid cells are each constructed of resin-cured fiber reinforcement and are arranged in a geometric configuration. The fiber reinforcement can be in the form of a fabric or braided fibers wrapped about a core that is either left in place or removed from the ultimate cured structure. The geometric configuration of cells is held together with more fiber reinforcement (in the form of fabric or braided fibers) in order to integrate the cells in the geometric configuration. The additional fiber reinforcement is resin-cured to the cells. Curing of the cells and ultimate structure can occur in a single step. In applications where post-crash integrity is necessary, ductile fibers can be used to integrate the cells in the geometric configuration. The novelty of the present invention is that simple fabrication techniques are used to create structures that can be formed in a variety of net stable shapes without additional reinforcement and can withstand combined loading while crushing in a desired direction.

Optical resolution photoacoustic microscopy using novel high-repetition-rate passively Q-switched microchip and fiber lasers.

PubMed

Shi, Wei; Kerr, Shaun; Utkin, Ilya; Ranasinghesagara, Janaka; Pan, Lei; Godwal, Yogesh; Zemp, Roger J; Fedosejevs, Robert

2010-01-01

Optical-resolution photoacoustic microscopy (OR-PAM) is a novel imaging technology for visualizing optically absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, OR-PAM imaging speed is limited by both scanning speed and laser pulse repetition rate. Unfortunately, lasers with high repetition rates and suitable pulse durations and energies are not widely available and can be cost-prohibitive and bulky. We are developing compact, passively Q-switched fiber and microchip laser sources for this application. The properties of these lasers are discussed, and pulse repetition rates up to 100 kHz are demonstrated. OR-PAM imaging was conducted using a previously developed photoacoustic probe, which enabled flexible scanning of the focused output of the lasers. Phantom studies demonstrate the ability to image with lateral spatial resolution of 7±2 μm with the microchip laser system and 15±5 μm with the fiber laser system. We believe that the high pulse repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where real-time imaging performance is essential.

Optimal Damping Behavior of a Composite Sandwich Beam Reinforced with Coated Fibers

NASA Astrophysics Data System (ADS)

Lurie, S.; Solyaev, Y.; Ustenko, A.

2018-04-01

In the present paper, the effective damping properties of a symmetric foam-core sandwich beam with composite face plates reinforced with coated fibers is studied. A glass fiber-epoxy composite with additional rubber-toughened epoxy coatings on the fibers is considered as the material of the face plates. A micromechanical analysis of the effective properties of the unidirectional lamina is conducted based on the generalized self-consistent method and the viscoelastic correspondence principle. The effective complex moduli of composite face plates with a symmetric angle-ply structure are evaluated based on classical lamination theory. A modified Mead-Markus model is utilized to evaluate the fundamental modal loss factor of a simply supported sandwich beam with a polyurethane core. The viscoelastic frequency-dependent behaviors of the core and face plate materials are both considered. The properties of the face plates are evaluated based on a micromechanical analysis and found to implicitly depend on frequency; thus, an iterative procedure is applied to find the natural frequencies of the lateral vibrations of the beam. The optimal values of the coating thickness, lamination angle and core thickness for the best multi-scale damping behavior of the beam are found.

Fiber optic and laser sensors IV; Proceedings of the Meeting, Cambridge, MA, Sept. 22-24, 1986

NASA Technical Reports Server (NTRS)

De Paula, Ramon P. (Editor); Udd, Eric (Editor)

1987-01-01

The conference presents papers on industrial uses of fiber optic sensors, point and distributed polarimetric optical fiber sensors, fiber optic electric field sensor technology, micromachined resonant structures, single-mode fibers for sensing applications, and measurement techniques for magnetic field gradient detection. Consideration is also given to electric field meter and temperature measurement techniques for the power industry, the calibration of high-temperature fiber-optic microbend pressure transducers, and interferometric sensors for dc measurands. Other topics include the recognition of colors and collision avoidance in robotics using optical fiber sensors, the loss compensation of intensity-modulating fiber-optic sensors, and an embedded optical fiber strain tensor for composite structure applications.

Fabrication of locally micro-structured fiber Bragg gratings by fs-laser machining

NASA Astrophysics Data System (ADS)

Dutz, Franz J.; Stephan, Valentin; Marchi, Gabriele; Koch, Alexander W.; Roths, Johannes; Huber, Heinz P.

2018-06-01

Here, we describe a method for producing locally micro-structured fiber Bragg gratings (LMFGB) by fs-laser machining. This technique enables the precise and reproducible ablation of cladding material to create circumferential grooves inside the claddings of optical fibers. From initial ablation experiments we acquired optimized process parameters. The fabricated grooves were located in the middle of uniform type I fiber Bragg gratings. LMFBGs with four different groove widths of 48, 85, 135 and 205 μ { {m}} were produced. The grooves exhibited constant depths of about 30 μ {m} and steep sidewall angles. With the combination of micro-structures and fiber Bragg gratings, fiber optic sensor elements with enhanced functionalities can be achieved.

Highly Porous FeS/Carbon Fibers Derived from Fe-Carrageenan Biomass: High-capacity and Durable Anodes for Sodium-Ion Batteries.

PubMed

Li, Daohao; Sun, Yuanyuan; Chen, Shuai; Yao, Jiuyong; Zhang, Yuhui; Xia, Yanzhi; Yang, Dongjiang

2018-05-08

The nanostructured metal sulfides have been reported as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities but have suffered from the unsatisfactory electronic conductivity and poor structural stability during a charge/discharge process, thus limiting their applications. Herein, the one-dimensional (1D) porous FeS/carbon fibers (FeS/CFs) micro/nanostructures are fabricated through facile pyrolysis of double-helix-structured Fe-carrageenan fibers. The FeS nanoparticles are in situ formed by interacting with sulfur-containing group of natural material ι-carrageenan and uniformly embedded in the unique 1D porous carbon fibrous matrix, significantly enhancing the sodium-ion storage performance. The obtained FeS/CFs with optimized sodium storage performance benefits from the appropriate carbon content (20.9 wt %). The composite exhibits high capacity and excellent cycling stability (283 mAh g -1 at current density of 1 A g -1 after 400 cycles) and rate performance (247 mAh g -1 at 5 A g -1 ). This work provides a simple strategy to construct 1D porous FeS/CFs micro/nanostructures as high-performance anode materials for SIBs via a unique sustainable and environmentally friendly way.

Monitoring the Wobbe Index of Natural Gas Using Fiber-Enhanced Raman Spectroscopy.

PubMed

Sandfort, Vincenz; Trabold, Barbara M; Abdolvand, Amir; Bolwien, Carsten; Russell, Philip St. J; Wöllenstein, Jürgen; Palzer, Stefan

2017-11-24

The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical issues such as detection limit, gas exchange time and background Raman signals from the fiber material still pose obstacles to utilizing the scheme in real-world settings. This paper compares the performance of two types of hollow-core photonic crystal fiber (PCF), namely photonic bandgap PCF and kagomé-style PCF, and assesses their potential for online determination of the Wobbe index. In contrast to bandgap PCF, kagomé-PCF allows for reliable detection of Raman-scattered photons even below 1200 cm -1 , which in turn enables fast and comprehensive assessment of the natural gas quality of arbitrary mixtures.

Monitoring the Wobbe Index of Natural Gas Using Fiber-Enhanced Raman Spectroscopy

PubMed Central

Sandfort, Vincenz; Trabold, Barbara M.; Abdolvand, Amir; Bolwien, Carsten; Russell, Philip St. J.; Wöllenstein, Jürgen

2017-01-01

The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical issues such as detection limit, gas exchange time and background Raman signals from the fiber material still pose obstacles to utilizing the scheme in real-world settings. This paper compares the performance of two types of hollow-core photonic crystal fiber (PCF), namely photonic bandgap PCF and kagomé-style PCF, and assesses their potential for online determination of the Wobbe index. In contrast to bandgap PCF, kagomé-PCF allows for reliable detection of Raman-scattered photons even below 1200 cm−1, which in turn enables fast and comprehensive assessment of the natural gas quality of arbitrary mixtures. PMID:29186768

Structural Health Monitoring of Civil Infrastructure Using Optical Fiber Sensing Technology: A Comprehensive Review

PubMed Central

Ye, X. W.; Su, Y. H.; Han, J. P.

2014-01-01

In the last two decades, a significant number of innovative sensing systems based on optical fiber sensors have been exploited in the engineering community due to their inherent distinctive advantages such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. A lot of optical fiber sensor-based monitoring systems have been developed for continuous measurement and real-time assessment of diversified engineering structures such as bridges, buildings, tunnels, pipelines, wind turbines, railway infrastructure, and geotechnical structures. The purpose of this review article is devoted to presenting a summary of the basic principles of various optical fiber sensors, innovation in sensing and computational methodologies, development of novel optical fiber sensors, and the practical application status of the optical fiber sensing technology in structural health monitoring (SHM) of civil infrastructure. PMID:25133250

Structural health monitoring of civil infrastructure using optical fiber sensing technology: a comprehensive review.

PubMed

Ye, X W; Su, Y H; Han, J P

2014-01-01

In the last two decades, a significant number of innovative sensing systems based on optical fiber sensors have been exploited in the engineering community due to their inherent distinctive advantages such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. A lot of optical fiber sensor-based monitoring systems have been developed for continuous measurement and real-time assessment of diversified engineering structures such as bridges, buildings, tunnels, pipelines, wind turbines, railway infrastructure, and geotechnical structures. The purpose of this review article is devoted to presenting a summary of the basic principles of various optical fiber sensors, innovation in sensing and computational methodologies, development of novel optical fiber sensors, and the practical application status of the optical fiber sensing technology in structural health monitoring (SHM) of civil infrastructure.

Reconstruction and Visualization of Fiber and Laminar Structure inthe Normal Human Heart from Ex Vivo DTMRI Data

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

Rohmer, Damien; Sitek, Arkadiusz; Gullberg, Grant T.

2006-12-18

Background - The human heart is composed of a helicalnetwork of muscle fibers. These fibers are organized to form sheets thatare separated by cleavage surfaces. This complex structure of fibers andsheets is responsible for the orthotropic mechanical properties ofcardiac muscle. The understanding of the configuration of the 3D fiberand sheet structure is important for modeling the mechanical andelectrical properties of the heart and changes in this configuration maybe of significant importance to understand the remodeling aftermyocardial infarction.Methods - Anisotropic least square filteringfollowed by fiber and sheet tracking techniques were applied to DiffusionTensor Magnetic Resonance Imaging (DTMRI) data of the excisedmore » humanheart. The fiber configuration was visualized by using thin tubes toincrease 3-dimensional visual perception of the complex structure. Thesheet structures were reconstructed from the DTMRI data, obtainingsurfaces that span the wall from the endo- to the epicardium. Allvisualizations were performed using the high-quality ray-tracing softwarePOV-Ray. Results - The fibers are shown to lie in sheets that haveconcave or convex transmural structure which correspond to histologicalstudies published in the literature. The fiber angles varied depending onthe position between the epi- and endocardium. The sheets had a complexstructure that depended on the location within the myocardium. In theapex region the sheets had more curvature. Conclusions - A high-qualityvisualization algorithm applied to demonstrated high quality DTMRI datais able to elicit the comprehension of the complex 3 dimensionalstructure of the fibers and sheets in the heart.« less

Durability of Cement Composites Reinforced with Sisal Fiber

NASA Astrophysics Data System (ADS)

Wei, Jianqiang

This dissertation focuses mainly on investigating the aging mechanisms and degradation kinetics of sisal fiber, as well as the approaches to mitigate its degradation in the matrix of cement composites. In contrast to previous works reported in the literature, a novel approach is proposed in this study to directly determine the fiber's degradation rate by separately studying the composition changes, mechanical and physical properties of the embedded sisal fibers. Cement hydration is presented to be a crucial factor in understanding fiber degradation behavior. The degradation mechanisms of natural fiber consist of mineralization of cell walls, alkali hydrolysis of lignin and hemicellulose, as well as the cellulose decomposition which includes stripping of cellulose microfibrils and alkaline hydrolysis of amorphous regions in cellulose chains. Two mineralization mechanisms, CH-mineralization and self-mineralization, are proposed. The degradation kinetics of sisal fiber in the cement matrix are also analyzed and a model to predict the degradation rate of cellulose for natural fiber embedded in cement is outlined. The results indicate that the time needed to completely degrade the cellulose in the matrix with cement replacement by 30wt.% metakaolin is 13 times longer than that in pure cement. A novel and scientific method is presented to determine accelerated aging conditions, and to evaluating sisal fiber's degradation rate and durability of natural fiber-reinforced cement composites. Among the static aggressive environments, the most effective approach for accelerating the degradation of natural fiber in cement composites is to soak the samples or change the humidity at 70 °C and higher temperature. However, the dynamic wetting and drying cycling treatment has a more accelerating effect on the alkali hydrolysis of fiber's amorphous components evidenced by the highest crystallinity indices, minimum content of holocellulose, and lowest tensile strength. Based on the understanding of degradation mechanisms, two approaches are proposed to mitigate the degradation of sisal fiber in the cement matrix. In order to relieve the aggressive environment of hydrated cement, cement substitution by a combination of metakaolin and nanoclay, and a combination of rice husk ash and limestone are studied. Both metakaolin and nanoclay significantly optimize the cement hydration, while the combination of these two supplementary cementitious materials validates their complementary and synergistic effect at different stages of aging. The presented approaches effectively reduce the calcium hydroxide content and the alkalinity of the pore solution, thereby mitigating the fiber degradation and improving both the initial mechanical properties and durability of the fiber-cement composites. The role of rice husk ash in cement modification is mainly as the active cementitious supplementary material. In order to improve the degradation resistance of sisal fiber itself, two novel, simple, and economical pretreatments of the fibers (thermal and sodium carbonate treatment) are investigated. Both thermal treatment and Na 2CO3 treatment effectively improve the durability of sisal fiber-reinforced concrete. The thermal treatment achieves improvement of cellulose's crystallization, which ensures the initial strength and improved durability of sisal fiber. A layer consisting of calcium carbonate sediments, which protects the internals of a fiber from the strong alkali pore solution, is formed and filled in pits and cavities on the Na2CO3 treated sisal fiber's surface.

Influence of dietary fiber on inflammatory bowel disease and colon cancer: importance of fermentation pattern.

PubMed

Rose, Devin J; DeMeo, Mark T; Keshavarzian, Ali; Hamaker, Bruce R

2007-02-01

The benefits of dietary fiber on inflammatory bowel disease may be related to the fermentative production of butyrate in the colon, which appears to decrease the inflammatory response. The benefits of dietary fiber against colon cancer may be related to both fermentative and non-fermentative processes, although poorly fermentable fibers appear more influential. Dietary fiber fermentation profiles are important in determining optimal fibers for colonic health, and may be a function of structure, processing conditions, and other food components. A greater understanding of the relationships between fermentation rate and dietary fiber structure would allow for development of dietary fibers for optimum colonic health.

Single mode fibers with antireflective surface structures for high power laser applications

NASA Astrophysics Data System (ADS)

Busse, Lynda E.; Florea, Catalin M.; Shaw, L. Brandon; Aggarwal, Ishwar D.; Sanghera, Jasbinder S.

2014-03-01

We present results for increased transmission of ~99.5% in the near-IR through the end faces of silica single mode fibers by creating a random antireflective microstructure etched into the end face of the fiber. We demonstrate high laser damage thresholds for these fibers with AR structured surfaces.

Carbon fiber counting. [aircraft structures

NASA Technical Reports Server (NTRS)

Pride, R. A.

1980-01-01

A method was developed for characterizing the number and lengths of carbon fibers accidentally released by the burning of composite portions of civil aircraft structure in a jet fuel fire after an accident. Representative samplings of carbon fibers collected on transparent sticky film were counted from photographic enlargements with a computer aided technique which also provided fiber lengths.

Human epidemiology: A review of fiber type and characteristics in the development of malignant and nonmalignant disease

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

Merchant, J.A.

1990-08-01

Consideration of the human epidemiology of diseases arising from exposure to naturally occurring and man-made mineral fibers encompasses the several forms of asbestos, other naturally occurring silicates, and man-made mineral fibers. The diseases arising from exposures to some of these fibers include pleural thickening, pulmonary fibrosis, lung cancers, mesothelioma of the pleura and peritoneum, and other cancers. Risk factors important in assessing these diseases include assessment of latency, duration of exposure, cumulative exposure, fiber origin and characteristics, other possible confounding occupational or environmental exposures, and smoking. Methodological issues commonly presenting problems in evaluation of these data include assessment of themore » adequacy of environmental exposures, particularly in regard to fiber identification, distribution, and concentration over the duration of exposure, and the adequacy of study design to detect health effects. Research priorities include further assessment and standardization of pleural thickening relative to fiber exposure, uniform mesothelioma surveillance, further epidemiological assessment of certain silicate and man-made mineral fiber cohorts with emphasis given to assessment of tremolite and small diameter glass and ceramic fibers. Further assessment of possible health risks of the general public should await improved definition of relevant fiber exposure in ambient air.« less

Genome-wide identification of multifunctional laccase gene family in cotton (Gossypium spp.); expression and biochemical analysis during fiber development

PubMed Central

Balasubramanian, Vimal Kumar; Rai, Krishan Mohan; Thu, Sandi Win; Hii, Mei Mei; Mendu, Venugopal

2016-01-01

The single-celled cotton fibers, produced from seed coat epidermal cells are the largest natural source of textile fibers. The economic value of cotton fiber lies in its length and quality. The multifunctional laccase enzymes play important roles in cell elongation, lignification and pigmentation in plants and could play crucial role in cotton fiber quality. Genome-wide analysis of cultivated allotetraploid (G. hirsutum) and its progenitor diploid (G. arboreum and G. raimondii) cotton species identified 84, 44 and 46 laccase genes, respectively. Analysis of chromosomal location, phylogeny, conserved domain and physical properties showed highly conserved nature of laccases across three cotton species. Gene expression, enzymatic activity and biochemical analysis of developing cotton fibers was performed using G. arboreum species. Of the total 44, 40 laccases showed expression during different stages of fiber development. The higher enzymatic activity of laccases correlated with higher lignin content at 25 DPA (Days Post Anthesis). Further, analysis of cotton fiber phenolic compounds showed an overall decrease at 25 DPA indicating possible incorporation of these substrates into lignin polymer during secondary cell wall biosynthesis. Overall data indicate significant roles of laccases in cotton fiber development, and presents an excellent opportunity for manipulation of fiber development and quality. PMID:27679939

Development of natural fiber reinforced polylactide-based biocomposites

NASA Astrophysics Data System (ADS)

Arias Herrera, Andrea Marcela

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

NASA advanced design program: Analysis, design, and construction of a solar powered aircraft. B.S. Thesis

NASA Technical Reports Server (NTRS)

Chan, Agnes; Conley, Kristin; Javorski, Christian T.; Cheung, Kwok-Hung; Crivelli, Paul M.; Torrey, Nancy P.; Traver, Michael L.

1992-01-01

Increase in energy demands coupled with rapid depletion of natural energy resources have deemed solar energy as the most logical alternative source of power. The major objective of this project was to build a solar powered remotely controlled aircraft to demonstrate the feasibility of solar energy as an effective, alternate source of power. The final design was optimized for minimum weight and maximum strength of the structure. These design constraints necessitated a carbon fiber composite structure. Surya is a lightweight, durable aircraft capable of achieving level flight powered entirely by solar cells.

Fiber-optic push-pull sensor systems

NASA Technical Reports Server (NTRS)

Gardner, David L.; Brown, David A.; Garrett, Steven L.

1991-01-01

Fiber-optic push-pull sensors are those which exploit the intrinsically differential nature of an interferometer with concommitant benefits in common-mode rejection of undesired effects. Several fiber-optic accelerometer and hydrophone designs are described. Additionally, the recent development at the Naval Postgraduate School of a passive low-cost interferometric signal demodulator permits the development of economical fiber-optic sensor systems.

Impact toughness of cellulose-fiber reinforced polypropylene : influence of microstructure in laminates and injection molded composites

Treesearch

Craig Clemons; Daniel Caulfield; A. Jeffrey Giacomin

2003-01-01

Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness. Fiber lengths were reduced by one-half when compounded in a high-intensity...

Mechanical properties and surface chemistry of kenaf fiber for composite reinforcement – an insight into the retting process

USDA-ARS?s Scientific Manuscript database

Harnessing natural fibers to produce polymer composites requires processing of fibers from harvest to the dried state, which can then be dispersed in the polymer resin. Bast fibers are found in the bark layer of fibrous plants such as kenaf (Hibiscus cannabinus), jute (Corchorus olitorius), and flax...

Magnetic field sensor based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber and large core-offset splicing structure

NASA Astrophysics Data System (ADS)

Lv, Ri-qing; Qian, Jun-kai; Zhao, Yong

2018-03-01

A simple, compact optical fiber magnetic field sensor is proposed and experimentally demonstrated in this paper. It is based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber structure and large core-offset splicing structure. It was protected by a section of capillary tube and was sealed by UV glue. A sensing property study of the combined optical fiber structure and the proposed sensor were carried out. The experimental results show that the sensitivity of the refractive index of the optical fiber sensing structure is up to 156.63 nm/RIU and the magnetic field sensitivity of the proposed sensor is up to -97.24 pm/Oe in the range from 72.4 Oe to 297.8 Oe. The proposed sensor has several other advantages, such as simple structure, small size, easy fabrication and low cost.

Structure of the bacteriophage T4 long tail fiber receptor-binding tip

PubMed Central

Bartual, Sergio G.; Otero, José M.; Garcia-Doval, Carmela; Llamas-Saiz, Antonio L.; Kahn, Richard; Fox, Gavin C.; van Raaij, Mark J.

2010-01-01

Bacteriophages are the most numerous organisms in the biosphere. In spite of their biological significance and the spectrum of potential applications, little high-resolution structural detail is available on their receptor-binding fibers. Here we present the crystal structure of the receptor-binding tip of the bacteriophage T4 long tail fiber, which is highly homologous to the tip of the bacteriophage lambda side tail fibers. This structure reveals an unusual elongated six-stranded antiparallel beta-strand needle domain containing seven iron ions coordinated by histidine residues arranged colinearly along the core of the biological unit. At the end of the tip, the three chains intertwine forming a broader head domain, which contains the putative receptor interaction site. The structure reveals a previously unknown beta-structured fibrous fold, provides insights into the remarkable stability of the fiber, and suggests a framework for mutations to expand or modulate receptor-binding specificity. PMID:21041684

Highly Stretchable Waterproof Fiber Asymmetric Supercapacitors in an Integrated Structure.

PubMed

Guo, Kai; Wang, Xianfu; Hu, Lintong; Zhai, Tianyou; Li, Huiqiao; Yu, Neng

2018-06-01

Fiber supercapacitors have attracted tremendous attention as promising power source candidates for the next generation of wearable electronics, which are flexible, stretchable, and washable. Although asymmetric fiber supercapacitors with a high energy density have been achieved, their stretchability is no more than 200%, and they still face mechanical instability and an unreliable waterproof structure. This work develops a highly integrated structure for a waterproof, highly stretchable, and asymmetric fiber-shaped supercapacitor, which is assembled by integrating a helix-shaped asymmetric fiber supercapacitor into a bifunctional polymer. The asymmetric fiber supercapacitor demonstrates a working voltage of 1.6 V, a high energy density of 2.86 mW h/cm 3 , has unchanged capacitance after being immersed in water for 50 h, and retains 95% of its initial capacitance after 3000 cycles of stretching-releasing at a maximum strain of 400%. The extraordinary waterproof capability, the large stretching strain, and excellent stretching stability are attributed to the highly integrated structure design, which can also simplify the assembly process of stretchable, waterproof fiber supercapacitors.

Experimental testing and numerical simulation on natural composite for aerospace applications

NASA Astrophysics Data System (ADS)

Kumar, G. Raj; Vijayanandh, R.; Kumar, M. Senthil; Kumar, S. Sathish

2018-05-01

Nowadays polymers are commonly used in various applications, which make it difficult to avoid its usage even though it causes environmental problems. Natural fibers are best alternate to overcome the polymer based environmental issues. Natural fibers play an important role in developing high performing fully newline biodegradable green composites which will be a key material to solve environmental problems in future. In this paper deals the properties analysis of banana fiber is combined with epoxy resin in order to create a natural composite, which has special characteristics for aerospace applications. The objective of this paper is to investigate the characteristics of failure modes and strength of natural composite using experimental and numerical methods. The test specimen of natural composite has been fabricated as per ASTM standard, which undergoes tensile and compression tests using Tinius Olsen UTM in order to determine mechanical and physical properties. The reference model has been designed by CATIA, and then numerical simulation has been carried out by Ansys Workbench 16.2 for the given boundary conditions.

Synthesis and characterization of poly lactic acid and multiwall carbon nano-tubes mixtures

NASA Astrophysics Data System (ADS)

Kumar LG, Santhosh; del A. Cardona, Rocío; Berríos-Soto, Melvin; Santiago-Avilés, Jorge J.

2011-10-01

The motivation for this study is to reproduce processing conditions which lead to the formation of photo or photoinduced thermal actuation, combined with inexpensive, environmentally friendly (easily degradable) materials. Commercially available polymer, poly lactic acid (PLA), was used in our studies. PLA is a well know biodegradable polymer naturally obtained from corn. PLA was received as a solid resin in pellet form and dissolved in 1:3 acetone/chloroform solutions, to achieve the proper electrospinning kinematic viscosity. Once in the liquid phase, the material was mixed with commercially available multi-walled carbon nanotubes (MWCNTs) at varying concentrations and dispersed by severe sonication. The mixtures was electrospun at room temperature using a home built electrospinning apparatus capable of depositing randomly oriented fiber mats or oriented fibers onto different substrates, ranging from oxidized silicon wafers, alumina squares or glass microscope slides. The fibers diameters and lengths are statistically distributed following a log-normal distribution and the mean and dispersion are controlled by spinning parameters. Once the fibers were electrospun, they were compositionally, morphologically and structurally characterized by thermal and gravimetric analysis (TGA/DTA), rheology, imaging using a focused Ion Beam Scanning Electron Microscope (IBSEM), and IR /Raman methodologies. These studies can be used to explore PLA-MWCNTs mixtures suitability in applications such as super-capacitor technology, which would enable us to pursue further research in this field, while focusing on improving the electro spinning conditions so as to be able to better anticipate fiber morphology to generate a consistent regime of fibers.

Dietary Fiber-Induced Changes in the Structure and Thermal Properties of Gluten Proteins Studied by Fourier Transform-Raman Spectroscopy and Thermogravimetry.

PubMed

Nawrocka, Agnieszka; Szymańska-Chargot, Monika; Miś, Antoni; Wilczewska, Agnieszka Z; Markiewicz, Karolina H

2016-03-16

Interactions between gluten proteins and dietary fiber supplements at the stage of bread dough formation are crucial in the baking industry. The dietary fiber additives are regarded as a source of polysaccharides and antioxidants, which have positive effects on human health. The fiber enrichment of bread causes a significant reduction in its quality, which is connected with changes in the structure of gluten proteins. Changes in the structure of gluten proteins and their thermal properties induced by seven commercial dietary fibers (fruit, vegetable, and cereal) were studied by FT-Raman spectroscopy and thermogravimetry (TGA), respectively. For this aim the bread dough at 500 FU consistency was made of a blend of wheat starch and wheat gluten as well as the fiber, the content of which ranged from 3 to 18% w/w. The obtained results revealed that all dietary fibers apart from oat caused similar changes in the secondary structure of gluten proteins. The most noticeable changes were observed in the regions connected with hydrogen-bonded β-sheets (1614 and 1684 cm(-1)) and β-turns (1640 and 1657 cm(-1)). Other changes observed in the gluten structure, concerning other β-structures, conformation of disulfide bridges, and aromatic amino acid microenvironment, depend on the fibers' chemical composition. The results concerning structural changes suggested that the observed formation of hydrogen bonds in the β-structures can be connected with aggregation or abnormal folding. This hypothesis was confirmed by thermogravimetric results. Changes in weight loss indicated the formation of a more complex and strong gluten network.

Toward efficient fiber-based quantum interface (Conference Presentation)

NASA Astrophysics Data System (ADS)

Soshenko, Vladimir; Vorobyov, Vadim V.; Bolshedvorsky, Stepan; Lebedev, Nikolay; Akimov, Alexey V.; Sorokin, Vadim; Smolyaninov, Andrey

2016-04-01

NV center in diamond is attracting a lot of attention in quantum information processing community [1]. Been spin system in clean and well-controlled environment of diamond it shows outstanding performance as quantum memory even at room temperature, spin control with single shot optical readout and possibility to build up quantum registers even on single NV center. Moreover, NV centers could be used as high-resolution sensitive elements of detectors of magnetic or electric field, temperature, tension, force or rotation. For all of these applications collection of the light emitted by NV center is crucial point. There were number of approaches suggested to address this issue, proposing use of surface plasmoms [2], manufacturing structures in diamond [3] etc. One of the key feature of any practically important interface is compatibility with the fiber technology. Several groups attacking this problem using various approaches. One of them is placing of nanodiamonds in the holes of photonic crystal fiber [4], another is utilization of AFM to pick and place nanodiamond on the tapered fiber[5]. We have developed a novel technique of placing a nanodiamond with single NV center on the tapered fiber by controlled transfer of a nanodiamond from one "donor" tapered fiber to the "target" clean tapered fiber. We verify our ability to transfer only single color centers by means of measurement of second order correlation function. With this technique, we were able to double collection efficiency of confocal microscope. The majority of the factors limiting the collection of photons via optical fiber are technical and may be removed allowing order of magnitude improved in collection. We also discuss number of extensions of this technique to all fiber excitation and integration with nanostructures. References: [1] Marcus W. Doherty, Neil B. Manson, Paul Delaney, Fedor Jelezko, Jörg Wrachtrup, Lloyd C.L. Hollenberg , " The nitrogen-vacancy colour centre in diamond," Physics Reports, vol. 528, no. 1, p. 1-45, 2013. [2] A.V. Akimov, A. Mukherjee, C.L. Yu, D.E. Chang, A.S. Zibrov, P.R. Hemmer, H. Park and M.D. Lukin, "Generation of single optical plasmons in metallic nanowires coupled to quantum dots," Nature, vol. 450, p. 402-406, 2007. [3] Michael J. Burek , Yiwen Chu, Madelaine S.Z. Liddy, Parth Patel, Jake Rochman , Srujan Meesala, Wooyoung Hong, Qimin Quan, Mikhail D. Lukin and Marko Loncar High quality-factor optical nanocavities in bulk single-crystal diamond, Nature communications 6718 (2014) [4] Tim Schroder, Andreas W. Schell, Gunter Kewes, Thomas Aichele, and Oliver Benson Fiber-Integrated Diamond-Based Single Photon Source, Nano Lett. 2011, 11, 198-202 [5]Lars Liebermeister, et. al. "Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center", Appl. Phys. Lett. 104, 031101 (2014)

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

Anggoro, Didi Dwi, E-mail: anggorophd@gmail.com; Kristiana, Nunung, E-mail: nuna.c631@gmail.com

Ballistic protection equipment, such as a bulletproof vest, is a soldier’s most important means of preserving life and survivability in extreme combat conditions. The bulletproof vests are designed to protect the user’s chest from injury without disturbing the ability to perform his duties. Aromatic polyamide or aramid fibers known under the trade name Kevlar, Trawon and so is synthetic fiber materials commonly used in the manufacture of bulletproof vests. This synthetic fibers have high tensile strength and ductility. Kevlar is expensive and imported material. In this study, will introduce local natural raw materials, ramie fiber (Boehmeria nivea) which is cheapermore » and environmentally friendly. It has enough tenacity and tensile strength as a bulletproof vest. This experiment uses two panels, there are Panel A as front surface of Panel B. Panel A is a combination of ramie and epoxide matrix, while panel B is only ramie. From several variations of experimental combinations between Panel A and Panel B, optimal combination obtained with 16 layers of panel A and 31-34 layers of panel B which is able to protect againts cal. 7.65 mm × 17 mm (.32 ACP) bullet fired through pistol .32 Pindad from a distance of 20 meters. Panel with a size of 20 cm × 20 cm has a total thickness between 12,922 to13,745 mm and a total weight between 506,26 to 520,926gram. Scanning electron microscopy (SEM) observations indicated that the porosity and surface area of the ramie fiber is smooth, fiber surfaces showed topography with micropores. SEM also showed well-arranged structure of fibers bonding. Energy Dispersive X-ray (EDX) analysis indicated 100 % carbon contents in ramie fiber. Test result indicates that panel from composite ramie-epoxide can reach the level 1of International Standard of NIJ - 010104. Compared to panel from polyester fiber, the panel from composite ramie-epoxide (0,50-0,52 kg) is lighter weight than panel polyester fiber (1,642 kg)« less

Inflatable Column Structure

NASA Technical Reports Server (NTRS)

Hedgepeth, J. M.

1985-01-01

Lightweight structural member easy to store. Billowing between circumferential loops of fiber inflated column becomes series of cells. Each fiber subjected to same tension along entire length (though tension is different in different fibers). Member is called "isotensoid" column. Serves as jack for automobiles or structures during repairs. Also used as support for temporary bleachers or swimming pools.

Composite structural materials

NASA Technical Reports Server (NTRS)

Loewy, R. G.; Wiberley, S. E.

1985-01-01

Various topics relating to composite structural materials for use in aircraft structures are discussed. The mechanical properties of high performance carbon fibers, carbon fiber-epoxy interface bonds, composite fractures, residual stress in high modulus and high strength carbon fibers, fatigue in composite materials, and the mechanical properties of polymeric matrix composite laminates are among the topics discussed.

Design considerations for fiber composite structures

NASA Technical Reports Server (NTRS)

Chamis, C. C.

1972-01-01

An overview of the design methodology for designing structural components from fiber composites is presented. In particular, the need for new conceptual structural designs for the future is discussed and the evolution of conceptual design is illustrated. Sources of design data, analysis and design procedures, and the basic components of structural fiber composites are cited and described. Examples of tradeoff studies and optimum designs are discussed and a simple structure is described in some detail.

Effects of weathering on color loss of natural fiber thermoplastic composites

Treesearch

R.H. Falk; C. Felton; T. Lundin

2001-01-01

The technology currently exists to manufacture natural fiber thermoplastic composites from recycled materials. Development of commodity-building products from these composites would open up huge markets for waste-based materials in the US. To date, the construction industry has only accepted wood thermoplastic composite lumber (and only for limited applications). In...

Effects of weathering on color loss of natural fiber : thermoplastic composites

Treesearch

Robert H. Falk; Colin Felton; Thomas Lundin

2000-01-01

The technology currently exists to manufacture natural fiber-thermoplastic composites from recycled materials. Development of commodity building products from these composites would open huge markets for waste-based materials in the United States. To date, the construction industry has only accepted wood-thermoplastic composite lumber and only for limited applications...

Variation of mechanical and thermal properties of the thermoplastics reinforced with natural fibers by electron beam processing

NASA Astrophysics Data System (ADS)

Kim, Sok Won; Oh, Seungmin; Lee, Kyuse

2007-11-01

With restrictions for environmental protection being strengthened, the thermoplastics reinforced with natural fibers (NFs) such as jute, kenaf, flax, etc., appeared as an automobile interior material instead of the chemical plastics. Regardless of many advantages, one shortcoming is the deformation after being formed in high temperature of about 200 °C, caused by the poor adhesion between the natural fibers and thermoplastics. Also, the energy saving in connection with car air-conditioning becomes very important. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composing of 50% polypropylene (PP) and 50% natural fiber irradiated by the electron beam (energy: 0.5 MeV, dose: 0-20 kGy) were measured. The length and thickness of PP and NF are 80±10 mm and 40-120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum when the dose of electron beam is 10 kGy, and the deformation after the thermal cycle were reduced by the electron beam.

Distributed strain measurement and possible breakage detection of optical-fiber-embedded composite structure using slope-assisted Brillouin optical correlation-domain reflectometry

NASA Astrophysics Data System (ADS)

Lee, Heeyoung; Ochi, Yutaka; Matsui, Takahiro; Matsumoto, Yukihiro; Tanaka, Yosuke; Nakamura, Hitoshi; Mizuno, Yosuke; Nakamura, Kentaro

2018-07-01

Slope-assisted Brillouin optical correlation-domain reflectometry (SA-BOCDR) is a recently developed structural health monitoring technique for measurements of strain, temperature, and loss distributions along optical fibers. Although the basic operational principle of this method has been clarified, no measurements using optical fibers embedded in actual structures have been reported. As a first step towards such practical applications, in this study, we present an example of an SA-BOCDR-based diagnosis using a composite structure with carbon fiber-reinforced plastics. The system’s output agrees well with the actual strain distributions. We were also able to detect the breakage of the embedded fiber, thus demonstrating the promise of SA-BOCDR for practical applications.

Golden spiral photonic crystal fiber: polarization and dispersion properties.

PubMed

Agrawal, Arti; Kejalakshmy, N; Chen, J; Rahman, B M A; Grattan, K T V

2008-11-15

A golden spiral photonic crystal fiber (GS-PCF) design is presented in which air holes are arranged in a spiral pattern governed by the golden ratio, where the design has been inspired by the optimal arrangement of seeds found in nature. The birefringence and polarization properties of this fiber are analyzed using a vectorial finite-element method. The fiber that is investigated shows a large modal birefringence peak value of 0.016 at an operating wavelength of 1.55 microm and exhibits highly tuneable dispersion with multiple zero dispersion wavelengths and also large normal dispersion. The GS-PCF design has identical circular air holes that potentially simplify fabrication. In light of its properties, the GS-PCF could have application as a highly birefringent fiber and in nonlinear optics, and moreover the 2D chiral nature of the pattern could yield exotic properties.

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.

Production of flax fibers for biocomposites

USDA-ARS?s Scientific Manuscript database

Natural fibers for many and varied industrial uses are a current area of intense interest. Production of these fibers, furthermore, can add to farmer incomes and promote agricultural sustainability. Flax (Linum usitatissimum L.), which has been used for thousands of years, is unparalleled in supplyi...

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

Jiang, Lin; Liu, Cong; Leibly, David

Amyloid protein aggregates are associated with dozens of devastating diseases including Alzheimer’s, Parkinson’s, ALS, and diabetes type 2. While structure-based discovery of compounds has been effective in combating numerous infectious and metabolic diseases, ignorance of amyloid structure has hindered similar approaches to amyloid disease. Here we show that knowledge of the atomic structure of one of the adhesive, steric-zipper segments of the amyloid-beta (Aβ) protein of Alzheimer’s disease, when coupled with computational methods, identifies eight diverse but mainly flat compounds and three compound derivatives that reduce Aβ cytotoxicity against mammalian cells by up to 90%. Although these compounds bind tomore » Aβ fibers, they do not reduce fiber formation of Aβ. Structure-activity relationship studies of the fiber-binding compounds and their derivatives suggest that compound binding increases fiber stability and decreases fiber toxicity, perhaps by shifting the equilibrium of Aβ from oligomers to fibers.« less

Preparation and study on the structure of keratin/PVA membrane containing wool fibers

NASA Astrophysics Data System (ADS)

Wu, Min; Shen, Shuming; Yang, Xuhong; Tang, Rencheng

2017-10-01

The urea / sodium sulfide / sodium dodecyl sulfate (SDS) method was used to dissolve the wool in this study. Then the Wool fiber/keratin/PVA composites with different proportions were prepared, and the surface morphology, molecular structure, mechanical property of the composite films and the influence of the proportions on their structure and properties were studied. The results showed that, there are α-helix structure, β-sheet and random coil conformations in the pure keratin film, as well as in the wool fiber. Compared with wool fiber, the crystallinity of keratin decreased. PVA can obviously improve the mechanical property of the blended film. When the blended ratio of keratin/PVA is 20/80, the mechanical property of the blended film is greatly improved. The composite films with 8%-16% of wool fibers have better flexibility than those without wool fibers.

Effect of fabric structure and polymer matrix on flexural strength, interlaminar shear stress, and energy dissipation of glass fiber-reinforced polymer composites

USDA-ARS?s Scientific Manuscript database

We report the effect of glass fiber structure and the epoxy polymer system on the flexural strength, interlaminar shear stress (ILSS), and energy absorption properties of glass fiber-reinforced polymer (GFRP) composites. Four different GFRP composites were fabricated from two glass fiber textiles of...

Fiber-optic sensor applications in civil and geotechnical engineering

NASA Astrophysics Data System (ADS)

Habel, Wolfgang R.; Krebber, Katerina

2011-09-01

Different types of fiber-optic sensors based on glass or polymeric fibers are used to evaluate material behavior or to monitor the integrity and long-term stability of load-bearing structure components. Fiber-optic sensors have been established as a new and innovative measurement technology in very different fields, such as material science, civil engineering, light-weight structures, geotechnical areas as well as chemical and high-voltage substations. Very often, mechanical quantities such as deformation, strain or vibration are requested. However, measurement of chemical quantities in materials and structure components, such as pH value in steel reinforced concrete members also provides information about the integrity of concrete structures. A special fiber-optic chemical sensor for monitoring the alkaline state (pH value) of the cementitious matrix in steel-reinforced concrete structures with the purpose of early detection of corrosion-initiating factors is described. The paper presents the use of several fiber-optic sensor technologies in engineering. One example concerns the use of highly resolving concrete-embeddable fiber Fabry-Perot acoustic emission (AE) sensors for the assessment of the bearing behaviour of large concrete piles in existing foundations or during and after its installation. Another example concerns fiber Bragg grating (FBG) sensors attached to anchor steels (micro piles) to measure the strain distribution in loaded soil anchors. Polymer optical fibers (POF) can be — because of their high elasticity and high ultimate strain — well integrated into textiles to monitor their deformation behaviour. Such "intelligent" textiles are capable of monitoring displacement of soil or slopes, critical mechanical deformation in geotechnical structures (dikes, dams, and embankments) as well as in masonry structures during and after earthquakes.

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.

Development of eddy current probe for fiber orientation assessment in carbon fiber composites

NASA Astrophysics Data System (ADS)

Wincheski, Russell A.; Zhao, Selina

2018-04-01

Measurement of the fiber orientation in a carbon fiber composite material is crucial in understanding the load carrying capability of the structure. As manufacturing conditions including resin flow and molding pressures can alter fiber orientation, verification of the as-designed fiber layup is necessary to ensure optimal performance of the structure. In this work, the development of an eddy current probe and data processing technique for analysis of fiber orientation in carbon fiber composites is presented. A proposed directional eddy current probe is modeled and its response to an anisotropic multi-layer conductor simulated. The modeling results are then used to finalize specifications of the eddy current probe. Experimental testing of the fabricated probe is presented for several samples including a truncated pyramid part with complex fiber orientation draped to the geometry for resin transfer molding. The inductively coupled single sided measurement enables fiber orientation characterization through the thickness of the part. The fast and cost-effective technique can be applied as a spot check or as a surface map of the fiber orientations across the structure. This paper will detail the results of the probe design, computer simulations, and experimental results.