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Fiber Bundles (fiber + bundle)

Distribution by Scientific Domains

Polymers and Materials Science	34%
Life Sciences	25%
Medical Sciences	21%

Selected Abstracts

Illustrative White Matter Fiber Bundles

COMPUTER GRAPHICS FORUM, Issue 3 2010
Ron Otten
Abstract Diffusion Tensor Imaging (DTI) has made feasible the visualization of the fibrous structure of the brain white matter. In the last decades, several fiber-tracking methods have been developed to reconstruct the fiber tracts from DTI data. Usually these fiber tracts are shown individually based on some selection criteria like region of interest. However, if the white matter as a whole is being visualized clutter is generated by directly rendering the individual fiber tracts. Often users are actually interested in fiber bundles, anatomically meaningful entities that abstract from the fibers they contain. Several clustering techniques have been developed that try to group the fiber tracts in fiber bundles. However, even if clustering succeeds, the complex nature of white matter still makes it difficult to investigate. In this paper, we propose the use of illustration techniques to ease the exploration of white matter clusters. We create a technique to visualize an individual cluster as a whole. The amount of fibers visualized for the cluster is reduced to just a few hint lines, and silhouette and contours are used to improve the definition of the cluster borders. Multiple clusters can be easily visualized by a combination of the single cluster visualizations. Focus+context concepts are used to extend the multiple-cluster renderings. Exploded views ease the exploration of the focus cluster while keeping the context clusters in an abstract form. Real-time results are achieved by the GPU implementation of the presented techniques. [source]

The Use of Optical Fiber Bundles Combined with Electrochemistry for Chemical Imaging

CHEMPHYSCHEM, Issue 2 2003
Sabine Szunerits Dr.
Abstract The present Review describes the progress made in using imaging optical fiber bundles for fluorescence and electrochemical-initiated chemiluminescence imaging. A novel optoelectrochemical micro-ring array has been fabricated and demonstrated for concurrent electrochemical and optical measurements. The device comprises optical fibers coated with gold via electroless gold deposition and assembled in a random array format. The design yielded an array of approximately 200 micro-ring electrodes, where interdiffusional problems were minimized. The inner diameter of the ring electrode is fixed by the diameter of the individual optical fibers (25 ,m), while the outer radius is determined by the thickness of the deposited gold. While all the fibers are optically addressable, they are not all electrochemically addressable. The resolution of this device is in the tens of micrometers range, determined by the diameter of the optical fiber (25 ,m) and by the spacing between each electrically connected fiber. For the purpose of having well-behaved microelectrode characteristics, this spacing was designed to be larger than 60 ,m. The array was characterized using ferrocyanide in aqueous solution as a model electroactive species to demonstrate that this microelectrode array format exhibits steady-state currents at short response times. This device has potential application to be used as an optoelectronic sensor, especially for the electrolytic generation and transmission of electrochemiluminescence, and was used to demonstrate that electrochemically generated luminescent products can be detected with the fiber assembly. [source]

Fabrication of a Macroporous Microwell Array for Surface-Enhanced Raman Scattering

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2009
Martina Zamuner
Abstract Here, a colloidal templating procedure for generating high-density arrays of gold macroporous microwells, which act as discrete sites for surface-enhanced Raman scattering (SERS), is reported. Development of such a novel array with discrete macroporous sites requires multiple fabrication steps. First, selective wet-chemical etching of the distal face of a coherent optical fiber bundle produces a microwell array. The microwells are then selectively filled with a macroporous structure by electroless template synthesis using self-assembled nanospheres. The fabricated arrays are structured at both the micrometer and nanometer scale on etched imaging bundles. Confocal Raman microscopy is used to detect a benzenethiol monolayer adsorbed on the macroporous gold and to map the spatial distribution of the SERS signal. The Raman enhancement factor of the modified wells is investigated and an average enhancement factor of 4,×,104 is measured. This demonstrates that such nanostructured wells can enhance the local electromagnetic field and lead to a platform of ordered SERS-active micrometer-sized spots defined by the initial shape of the etched optical fibers. Since the fabrication steps keep the initial architecture of the optical fiber bundle, such ordered SERS-active platforms fabricated onto an imaging waveguide open new applications in remote SERS imaging, plasmonic devices, and integrated electro-optical sensor arrays. [source]

Fabrication of Aligned Poly(L -lactide) Fibers by Electrospinning and Drawing

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2009
Amalina M. Afifi
Abstract A new target collector was designed for taking up aligned nanofibers by electrospinning. The collector consists of a rotor around which several fins were attached for winding electrospun filaments continuously in large amounts. The alignment of the nanofibers wound on the collector was affected by the electrospinning conditions, such as the needle-to-collector distance and the applied voltage, but not by the rotation speed of the collector. At a voltage of 0.5,kV,·,cm,1, about 60% of the fibers were found to be aligned within an angle of,±,5° relative to the rotational direction of the collector. The fiber alignment was improved to 90% by drawing the fiber bundle 2,3 times at 110,°C. The drawing was also effective for crystal orientation of the fibers as revealed by WAXD. The drawn fibers show improved mechanical properties. [source]

Multispectral fluorescence lifetime imaging by TCSPC

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 5 2007
Wolfgang Becker
Abstract We present a fluorescence lifetime imaging technique with simultaneous spectral and temporal resolution. The technique is fully compatible with the commonly used multiphoton microscopes and nondescanned (direct) detection. An image of the back-aperture of the microscope lens is projected on the input of a fiber bundle. The input of the fiber bundle is circular, and the output is flattened to match the input slit of a spectrograph. The spectrum at the output of the spectrograph is projected on a 16-anode PMT module. For each detected photon, the encoding logics of the PMT module deliver a timing pulse and the number of the PMT channel in which the photon was detected. The photons are accumulated by a multidimensional time-correlated single photon counting (TCSPC) process. The recording process builds up a four-dimensional photon distribution over the times of the photons in the excitation pulse period, the wavelengths of the photons, and the coordinates of the scan area. The method delivers a near-ideal counting efficiency and is capable of resolving double-exponential decay functions. We demonstrate the performance of the technique for autofluorescence imaging of tissue. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source]

Finite element analysis of plain weave composites for flexural failure

POLYMER COMPOSITES, Issue 4 2010
Ömer Soykasap
This article presents finite element analysis for flexural behavior of woven composites considering the fiber and the matrix and their interactions. Finite element model using Abaqus program is developed to predict the homogenized properties of plain-weave T300/LTM45 composite. Initially, curved beam elements are used to model each resin-infiltrated fiber bundle. Geometrically, nonlinear analyses of the model with periodic boundary conditions are carried out to obtain effective in-plane and bending properties of the composite. Statistical analysis is presented to study the stiffness variability. The flexural failure of a single-ply composite is estimated based on the homogenized material properties, and is compared with previously published data. The model is able to correct the significant errors in the stiffnesses of the composite and captures the failure behavior accurately. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source]

Wetting of a fiber bundle in fibrous structures

POLYMER COMPOSITES, Issue 3 2003
David Lukas
In this paper we dealt with the problem of wetting and ascending of a liquid along a fiber bundle. Two issues are first addressed including the criterion for complete wetting of the fiber bundle and the ascension liquid profile on a partially dipped vertical fiber bundle. Both topics are studied theoretically by deriving a mathematical theory by which predictions are generated and important parametric analyses are carried out. Further, a 3D Ising model is used for computer modeling to simulate the fiber wetting and liquid ascending processes on a partially dipped single fiber. The significance and potential applications of the study are also summarized. [source]

Flow Visualization Study of a Novel Respiratory Assist Catheter

ARTIFICIAL ORGANS, Issue 6 2009
Stephanus G. Budilarto
Abstract Respiratory assist using intravenous catheters may be a potential therapy for patients with acute and acute-on-chronic lung failure. An important design constraint is respiratory catheter size, and new strategies are needed that enable size reduction while maintaining adequate gas exchange. Our group is currently developing a percutaneous respiratory assist catheter (PRAC) that uses a rotating bundle of hollow fiber membranes to enhance CO2 removal and O2 supply with increasing bundle rotation rate. In this study, particle image velocimetry (PIV) was used to analyze the fluid flow patterns and velocity fields surrounding the rotating fiber bundle of the PRAC. The goal of the study was to assess the rotational flow patterns within the context of the gas exchange enhancement that occurs with increasing fiber bundle rotation. A PRAC prototype was placed in a 1-in. internal diameter test section of an in vitro flow loop designed specifically for PIV studies. The rotation rate of the PRAC was varied between 500 and 7000 rpm, and PIV was used to determine the velocity fields in the primary (r -,) and secondary (r - z) flow planes. The secondary flow exhibited time-varying and incoherent vortices that were consistent with the classical Taylor vortices expected for Taylor numbers (Ta) corresponding to the rotation speeds studied (2200 < Ta < 31 000). In the primary flow, the tangential velocity exhibited boundary layers of less than ½ mm adjacent to the fiber bundle and vessel wall. The estimated shear stress associated with the Taylor vortices was approximately 11 dyne/cm2 at 7000 rpm and was over 10 times smaller than the shear stress in the primary flow boundary layers. [source]

Electrochemical Modulation of Remote Fluorescence Imaging at an Ordered Opto-electrochemical Nanoaperture Array

CHEMPHYSCHEM, Issue 8 2004
Arnaud Chovin
Abstract An array of nanometer-sized apertures capable of electrochemically modulating the fluorescence of a model analyte is presented. The device, which combines near-field optical methods and ultramicroelectrode properties in an array format, is based on an etched coherent optical fiber bundle. Indeed, the fabrication steps produced an ordered array where each optical nanoaperture is surrounded by a ring-shaped gold nanoelectrode. The chronoamperometric behavior of the array shows stable diffusion-limited quasi-steady-state response. The model analyte, tris(2,2,-bipyridine) ruthenium, emits fluorescence in the Ru(II) state, but not in the oxidized Ru(III) state. Fluorescence is excited by visible light exiting from each nanoaperture since light is confined to the tip apex by the gold coating. A fraction of the isotropically emitted luminescence is collected by the same nanoaperture, transmitted by the corresponding fiber core and eventually detected by a charge-coupled device (CCD) camera. The array format provides a fluorescence image resolved at the nanometric scale which covers a large micrometric area. Therefore the high-density array plays a bridging role between these two fundamental scales. We established that the opto-electrochemical nanoapertures are optically independent. Fluorescence of the sample collected by each nanoaperture is modulated by changing the potential of the nanoring electrodes. Reversible electrochemical switching of remote fluorescence imaging is performed through the opto-electrochemical nanoaperture array itself. Eventually this ordered structure of nanometer light sources which are electrochemically manipulated provides promising photonic or electro-optical devices for various future applications. For example, such an array has potential in the development of a combined SNOM-electrochemical nanoprobe array to image a real sample concomitantly at the nanometer and micrometer scale. [source]

Documentation and three-dimensional modelling of human soleus muscle architecture

CLINICAL ANATOMY, Issue 4 2003
Anne M. Agur
Abstract The purpose of this study was to visualize and document the architecture of the human soleus muscle throughout its entire volume. The architecture was visualized by creating a three-dimensional (3D) manipulatable computer model of an entire cadaveric soleus, in situ, using B-spline solid to display muscle fiber bundles that had been serially dissected, pinned, and digitized. A database of fiber bundle length and angle of pennation throughout the marginal, posterior, and anterior soleus was compiled. The computer model allowed documentation of the architectural parameters in 3D space, with the angle of pennation being measured relative to the tangent plane of the point of attachment of a fiber bundle. Before this study, the only architectural parameters that have been recorded have been 2D. Three-dimensional reconstruction is an exciting innovation because it makes feasible the creation of an architectural database and allows visualization of each fiber bundle in situ from any perspective. It was concluded that the architecture is non-uniform throughout the volume of soleus. Detailed architectural studies may lead to the development of muscle models that can more accurately predict interaction between muscle parts, force generation, and the effect of pathologic states on muscle function. Clin. Anat. 16:285,293, 2003. © 2003 Wiley-Liss, Inc. [source]

Illustrative White Matter Fiber Bundles

Asynchrony of the early maturation of white matter bundles in healthy infants: Quantitative landmarks revealed noninvasively by diffusion tensor imaging

HUMAN BRAIN MAPPING, Issue 1 2008
Jessica Dubois
Abstract Normal cognitive development in infants follows a well-known temporal sequence, which is assumed to be correlated with the structural maturation of underlying functional networks. Postmortem studies and, more recently, structural MR imaging studies have described qualitatively the heterogeneous spatiotemporal progression of white matter myelination. However, in vivo quantification of the maturation phases of fiber bundles is still lacking. We used noninvasive diffusion tensor MR imaging and tractography in twenty-three 1,4-month-old healthy infants to quantify the early maturation of the main cerebral fascicles. A specific maturation model, based on the respective roles of different maturational processes on the diffusion phenomena, was designed to highlight asynchronous maturation across bundles by evaluating the time-course of mean diffusivity and anisotropy changes over the considered developmental period. Using an original approach, a progression of maturation in four relative stages was determined in each tract by estimating the maturation state and speed, from the diffusion indices over the infants group compared with an adults group on one hand, and in each tract compared with the average over bundles on the other hand. Results were coherent with, and extended previous findings in 8 of 11 bundles, showing the anterior limb of the internal capsule and cingulum as the most immature, followed by the optic radiations, arcuate and inferior longitudinal fascicles, then the spinothalamic tract and fornix, and finally the corticospinal tract as the most mature bundle. Thus, this approach provides new quantitative landmarks for further noninvasive research on brain-behavior relationships during normal and abnormal development. Hum Brain Mapp, 2008. © 2007 Wiley-Liss, Inc. [source]

On the vascularization and structure of the skin of a Korean bullhead Pseudobagrus brevicorpus (Bagridae, Teleostei) based on its entire body and appendages

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2010
J. Y. Park
Summary To investigate the vascularization and structure of the skin and its relationship to cutaneous respiration in Pseudobagrus brevicorpus, a histological study by light microscopy was carried out on 15 regions of the skin, including eight body regions, six fins and the barbel. The skin consisted of the epidermis, dermis and subcutis in all regions, except for the barbel that had a relatively thin dermis and subcutis. The epidermis was composed of the outermost layer, the middle layer and the stratum germinativum. There were two kinds of gland cells: the unicellular mucus cells and large club cells. The middle layer had a small number of fine blood capillaries accompanied by dermal collagen in all regions; the mean number of blood capillaries ranged from 0.9 to 5.9. The mean diffusion distance between the capillary endothelial cells and the surface of the epidermis ranged from 50.6 to 126.8 ,m. Based on these intra-epithelial blood capillaries, the relative surface area of the respiratory epithelium ranged from 0.1 to a maximum value of 1.2%. The dermis lacking scales had collagen bundles arranged parallel to each other, but vertical fiber bundles around the dorso-lateral regions were seen at intervals. Sensory organs such as taste buds, pit organs and lateral canals were found whereby the taste buds in particular were more abundant in the epidermis of the barbel. The vascularization of the skin may be closely related to an additional respiratory system used to deal with an extreme hypoxic condition during dry seasons. [source]

Characterization of liquefied wood residues from different liquefaction conditions

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007
Hui Pan
Abstract The amount of wood residue is used as a measurement of the extent of wood liquefaction. Characterization of the residue from wood liquefaction provides a new approach to understand some fundamental aspects of the liquefaction reaction. Residues were characterized by wet chemical analyses, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Klason lignin content of the residues decreased, while the holocellulose and ,-cellulose contents increased as the phenol to wood ratio (P/W) increased. A peak at 1735 cm,1, which was attributed to the ester carbonyl group in xylan, disappeared in the FTIR spectra of the residues from liquefied wood under a sealed reaction system, indicating significantly different effects of atmospheric versus sealed liquefaction. The crystallinity index of the residues was higher than that of the untreated wood particles and slightly increased with an increase in the P/W ratio. The SEM images of the residues showed that the fiber bundles were reduced to small-sized bundles or even single fibers as the P/W ratio increased from 1/1 to 3/1, which indicated that the lignin in the middle lamella had been dissolved prior to the cellulose during liquefaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source]

The musculotendinous system of an anguilliform swimmer: Muscles, myosepta, dermis, and their interconnections in Anguilla rostrata

JOURNAL OF MORPHOLOGY, Issue 1 2008
Nicole Danos
Abstract Eel locomotion is considered typical of the anguilliform swimming mode of elongate fishes and has received substantial attention from various perspectives such as swimming kinematics, hydrodynamics, muscle physiology, and computational modeling. In contrast to the extensive knowledge of swimming mechanics, there is limited knowledge of the internal body morphology, including the body components that contribute to this function. In this study, we conduct a morphological analysis of the collagenous connective tissue system, i.e., the myosepta and skin, and of the red muscle fibers that sustain steady swimming, focusing on the interconnections between these systems, such as the muscle-tendon and myosepta-skin connections. Our aim is twofold: (1) to identify the morphological features that distinguish this anguilliform swimmer from subcarangiform and carangiform swimmers, and (2) to reveal possible pathways of muscular force transmission by the connective tissue in eels. To detect gradual morphological changes along the trunk we investigated anterior (0.4L), midbody (0.6L), and posterior body positions (0.75L) using microdissections, histology, and three-dimensional reconstructions. We find that eel myosepta have a mediolaterally oriented tendon in each the epaxial and hypaxial regions (epineural or epipleural tendon) and two longitudinally oriented tendons (myorhabdoid and lateral). The latter two are relatively short (4.5,5% of body length) and remain uniform along a rostrocaudal gradient. The skin and its connections were additionally analyzed using scanning electron microscopy (SEM). The stratum compactum of the dermis consists of ,30 layers of highly ordered collagen fibers of alternating caudodorsal and caudoventral direction, with fiber angles of 60.51 ± 7.05° (n = 30) and 57.58 ± 6.92° (n = 30), respectively. Myosepta insert into the collagenous dermis via fiber bundles that pass through the loose connective tissue of the stratum spongiosum of the dermis and either weave into the layers of the stratum compactum (weaving fiber bundles) or traverse the stratum compactum (transverse fiber bundles). These fiber bundles are evenly distributed along the insertion line of the myoseptum. Red muscles insert into lateral and myorhabdoid myoseptal tendons but not into the horizontal septum or dermis. Thus, red muscle forces might be distributed along these tendons but will only be delivered indirectly into the dermis and horizontal septum. The myosepta-dermis connections, however, appear to be too slack for efficient force transmission and collagenous connections between the myosepta and the horizontal septum are at obtuse angles, a morphology that appears inadequate for efficient force transmission. Though the main modes of undulatory locomotion (anguilliform, subcarangiform, and carangiform) have recently been shown to be very similar with respect to their midline kinematics, we are able to distinguish two morphological classes with respect to the shape and tendon architecture of myosepta. Eels are similar to subcarangiform swimmers (e.g., trout) but are substantially different from carangiform swimmers (e.g., mackerel). This information, in addition to data from kinematic and hydrodynamic studies of swimming, shows that features other than midline kinematics (e.g., wake patterns, muscle activation patterns, and morphology) might be better for describing the different swimming modes of fishes. J. Morphol., 2008. © 2007 Wiley-Liss, Inc. [source]

Immunohistochemical and electron microscopic study of invasion and differentiation in spinal cord lesion of neural stem cells grafted through cerebrospinal fluid in rat

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2002
Sufan Wu
Abstract Neurospheres were obtained by culturing hippocampal cells from transgenic rat fetuses (E16) expressing green fluorescent protein (GFP). The neurosphere cells were injected into the cerebrospinal fluid (CSF) through the 4th ventricle of young rats (4 weeks old) that had been given a contusion injury at T8,9 of the spinal cord. The injected neural stem cells were transported through the CSF to the spinal cord, attached to the pial surface at the lesion, and invaded extensively into the spinal cord tissue as well as into the nerve roots. The grafted stem cells survived well in the host spinal cord for as long as 8 months after transplantation. Immunohistochemical study showed that many grafted stem cells had differentiated into astrocytes at 1,4 months, and some into oligodendrocytes at 8 months postoperatively. Immunoelectron microscopy showed that the grafted stem cells were well integrated into the host tissue, extending their processes around nerve fibers in the same manner as astrocytes. In addition, grafted stem cells within nerve roots closely surrounded myelinated fibers or were integrated into unmyelinated fiber bundles; those associated with myelinated fibers formed basal laminae on their free surface, whereas those associated with unmyelinated fibers were directly attached to axons and Schwann cells, indicating that grafted stem cells behaved like Schwann cells in the nerve roots. © 2002 Wiley-Liss, Inc. [source]

Transcallosal White Matter Degradation Detected With Quantitative Fiber Tracking in Alcoholic Men and Women: Selective Relations to Dissociable Functions

ALCOHOLISM, Issue 7 2010
Adolf Pfefferbaum
Introduction:, Excessive alcohol consumption can adversely affect white matter fibers and disrupt transmission of neuronal signals. Here, we examined six anatomically defined transcallosal white matter fiber bundles and asked whether any bundle was specifically vulnerable to alcohol, what aspect of white matter integrity was most affected, whether women were more vulnerable than men, and whether evidence of compromise in specific bundles was associated with deficits in balance, sustained attention, associative learning, and psychomotor function, commonly affected in alcoholics. Methods:, Diffusion tensor imaging quantitative fiber tracking assessed integrity of six transcallosal white matter bundles in 87 alcoholics (59 men, 28 women) and 88 healthy controls (42 men, 46 women). Measures included orientational diffusion coherence (fractional anisotropy, FA) and magnitude of diffusion, quantified separately for axial (longitudinal; ,L) and radial (transverse; ,T) diffusivity. The Digit Symbol Test and a test of ataxia were also administered. Results:, Alcoholism negatively affected callosal FA and ,T of all but the sensory-motor bundle. Women showed no evidence for greater vulnerability to alcohol than men. Multiple regression analyses confirmed a double dissociation: higher diffusivity in sensory-motor and parietal bundles was associated with poorer balance but not psychomotor speed, whereas higher diffusivity in prefrontal and temporal bundles was associated with slower psychomotor speed but not balance. Conclusions:, This study revealed stronger alcohol effects for FA and radial diffusivity than axial diffusivity, suggesting myelin degradation, but no evidence for greater vulnerability to alcohol in women than men. The presence of brain-behavior relationships provides support for the role of alcoholism-related commissural white matter degradation as a substrate of cognitive and motor impairment. Identification of a double dissociation provides further support for the role of selective white matter integrity in specific domains of performance. [source]

Biological Natural Retting for Determining the Hierarchical Structuration of Banana Fibers

MACROMOLECULAR BIOSCIENCE, Issue 10 2004
Piedad Gañán
Abstract Summary: 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 ,m surface fibers and 10,15 ,m inner elementary fibers, respectively. With increasing exposure time, fiber bundle walls lose integrity, as reflected in their mechanical behavior. [source]

Ionized-Air-Treated Curaua Fibers as Reinforcement for Phenolic Matrices

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2008
Wanderson Gonçalves Trindade
Abstract Curaua fibers were treated with ionized air to improve the fiber/phenolic matrix adhesion. The treatment with ionized air did not change the thermal stability of the fibers. The impact strength increased with increase in the fiber treatment time. SEM micrographs of the fibers showed that the ionized air treatment led to separation of the fiber bundles. Treatment for 12 h also caused a partial degradation of the fibers, which prompted the matrix to transfer the load to a poorer reinforcing agent during impact, thereby decreasing the impact strength of the related composite. The composites reinforced with fibers treated with ionized air absorbed less water than those reinforced with untreated fibers. [source]

Cytoskeletal response of microvessel endothelial cells to an applied stress force at the submicrometer scale studied by atomic force microscopy

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 10 2006
Wanyun Ma
Abstract Cytoskeleton fibers form an intricate three-dimensional network to provide structure and function to microvessel endothelial cells. During accommodation to blood flowing, stress fiber bundles become more prominent and align with the direction of blood flow. This network either mechanically resists the applied shear stress (lateral force) or, if deformed, is dynamically remodeled back to a preferred architecture. However, the detailed response of these stress fiber bundles to applied lateral force at submicrometer scales are as yet poorly understood. In our in vitro study, the tip, topography probe in lateral force microscopy of atomic force microscopy, acted as a tool for exerting quantitative vertical and lateral force on the filaments of the cytoskeleton. Moreover, the authors developed a formula to calculate the value of lateral force exerted on every point of the filaments. The results show that cytoskeleton fibers of healthy tight junctions in rat cerebral microvessel endothelial cells formed a cross-type network, and were reinforced and elongated in the direction of scanning under lateral force of 15,42 nN. Under peroxidation (H2O2 of 300 ,mol/L), the cytoskeleton remodeled at intercellular junctions, and changed over the meshwork structures into a dense bundle, that redistributed the stress. Once mechanical forces were exerted on an area, the cells shrank and lost morphologic tight junctions. It would be useful in our understanding of certain pathological processes, such as cerebral ischemia/reperfusion injury, which maybe caused by biomechanical forces and which are overlooked in current disease models. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source]

Biochemical and morphological effects of bladder pumping on the urinary bladder in rats

NEUROUROLOGY AND URODYNAMICS, Issue 5 2002
Kimio Sugaya
Abstract Aims To study the influence of bladder pumping on the urinary bladder in 44 female rats. Methods Under halothane anesthesia, a urethral catheter was inserted into the bladder of 27 rats, and air (0.4,0.8 mL) was pumped in and out of the bladder at 0.5 cycles/second for a period of 5 minutes. Twenty-four hours after pumping, the bladder was harvested for measurement of the tissue levels of myosin, actin, and nerve growth factor, as well as for electron microscopy. In nine of the 27 rats, cystometry was performed without anesthesia before and 1, 7, 30, and 90 days after bladder pumping. The remaining 17 rats that did not undergo pumping were anesthetized and their bladders were harvested as a control. Results Bladder pumping increased the bladder capacity and decreased the maximum bladder contraction pressure, but did not increase the residual volume. Bladder pumping also increased the tissue level of nerve growth factor and decreased the levels of myosin and actin. Electron microscopy showed degeneration of bladder smooth muscle cells and nerve fibers after bladder pumping, as well as derangement and disruption of collagen fiber bundles in the bladder wall. These functional and morphological effects of pumping disappeared within 90 days. Conclusions Bladder pumping therapy appears to have various effects on the bladder wall collagen fiber bundles, smooth muscle cells, and nerves. Neurourol. Urodynam. 21:511,515, 2002. © Wiley-Liss, Inc. [source]

Factitious Purpura in a 10-Year-Old Girl

PEDIATRIC DERMATOLOGY, Issue 5 2009
Kayo Yamada M.D.
Both congenital and autoimmune hemorrhagic disorders were excluded based on her past medical history and physical and laboratory findings. Child abuse was also ruled out as purpura continued to develop after child,family separation. Histologic examination of the skin lesions revealed disruption of collagen fiber bundles. This finding indicated application of external force, leading to a definitive diagnosis of factitious purpura. Although it is very rare in school-age children, the diagnosis of factitious purpura should be included in the differential diagnosis of purpura in children. Histologic analysis of skin biopsies may aid in establishing the diagnosis. [source]

Random discontinuous carbon fiber preforms: Experimental permeability characterization and local modeling

POLYMER COMPOSITES, Issue 4 2010
A. Endruweit
Injection experiments indicate that for random discontinuous carbon fiber preforms, increasingly uneven flow fronts develop with increasing fiber bundle length and filament count. While at high propensity for fiber bundle splitting, the preform permeability increases continuously with increasing fiber length, no trend can be identified at low propensity. No clear influence of the virgin bundle filament count on the preform permeability was observed. Types of sizing used on the fibers and bundle cross-sectional shapes may vary and affect the intrinsic filamentization behavior, thus dominating the preform permeability. In a model for local preform permeability, interbundle voids, distributed randomly across the preform thickness, are approximated via a regular void structure. Simulated filling patterns are qualitatively similar to those observed experimentally, showing more pronounced features than those derived from a model based on local through-thickness homogenization of the filament distribution. A model based on an alternating arrangement of fiber bundles and voids allows prediction of global preform permeability values from series of injection simulations, showing quantitatively better agreement with corresponding experimental results than the homogenization model. For global permeability, agreement between simulated and experimental mean values improves with increasing fiber volume fraction, whereas calculated coefficients of variation show no strong dependence on the fiber volume fraction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source]

The role of intramuscular connective tissue in meat texture

ANIMAL SCIENCE JOURNAL, Issue 1 2010
Takanori NISHIMURA
ABSTRACT The structure, composition and amount of intramuscular connective tissue (IMCT) vary tremendously between muscles, species and breeds, and certainly contribute to meat texture. With animal growth, collagen crosslinks become more stable, and the structural integrity of IMCT increases. These changes increase the mechanical properties of IMCT, contributing to the toughening of meat. Intramuscular fat deposits, mainly in the perimysium between muscle fiber bundles, result in marbling. This causes the remodeling of IMCT structures and reduces the mechanical strength of IMCT, contributing to the tenderization of beef. The IMCT has been thought to be rather immutable compared to myofibrils during postmortem ageing of meat. However, recent studies have shown the disintegration of IMCT during postmortem ageing of meat and its relationship to tenderization of raw meat, although its contribution to cooked meat is still controversial. Given the large influence of IMCT on meat texture, further elucidations of molecular mechanisms which change the structural integrity of IMCT during chronological ageing of animals and postmortem ageing of meat are needed. [source]

The Use of Optical Fiber Bundles Combined with Electrochemistry for Chemical Imaging

Three-dimensional study of the musculotendinous architecture of supraspinatus and its functional correlations

CLINICAL ANATOMY, Issue 6 2007
Soo Y. Kim
Abstract The supraspinatus is most frequently involved in shoulder pathology. However, the musculotendinous architecture of the supraspinatus has not been well documented. Therefore, the purpose of this study is to investigate the detailed three-dimensional architecture of the supraspinatus throughout its volume. Ten male formalin embalmed cadaveric specimens (mean age 61.9 ± 16 years) without any evidence of rotator cuff pathology were used. Three-dimensional coordinates (x, y, and z) of the tendon and muscle fiber bundles were collected in situ, using serial dissection and digitization. The data was reconstructed into a three-dimensional model using MayaÔ. Fiber bundle lengths, pennation angles (PA), muscle volumes, and tendon dimensions for each architecturally distinct area were computed and then analyzed using paired t -tests and ANOVA (P < 0.05). The supraspinatus was found to consist of anterior and posterior regions, which were each further subdivided into superficial, middle, and deep parts. Mean PA were found to be significantly different between the distinct parts of the anterior region of the muscle. Medial PA was also found be significantly different between the superficial and middle, and superficial and deep parts of the posterior region. These results provide insight into the normal function of the muscle and its possible contribution to the initiation and progression of supraspinatus tendon tears. Clin. Anat. 20:648,655, 2007. © 2007 Wiley-Liss, Inc. [source]