JOURNAL OF SENSORY STUDIES, Issue 4 2009
MARISA BEATRIZ VÁZQUEZ
ABSTRACT The aims of this study were to formulate biscuits with 50% more fiber and 50% less added salt than classic formulations, to describe their sensory characteristics, to measure expectation/sensory acceptability, and to investigate if sensory acceptability for these biscuits was related to the interest in consuming food products with less salt and/or more fiber content. A 2 × 2 factorial design was used to develop four formulations: conventional fiber/conventional salt; conventional fiber/reduced salt; increased fiber/conventional salt; and increased fiber/reduced salt. Differences in the sensory profiles measured by a trained panel were of low magnitude, except for presence and taste of bran. Adolescent and adult consumers evaluated acceptability in three stages: blind with three-digit codes; expectation of the label only; and biscuit + label. The low salt formulations received the lowest scores in the expectation stage, but in the blind and biscuit + label stages acceptability of all formulations was similar. The variables that explained overall acceptance were: measurement stage; formulation salt level; interest in reducing consumption of high salt foods; and interest in consuming bakery products with fiber. PRACTICAL APPLICATIONS Increasing fiber content of biscuits by 40 to 50% helps achieve recommendations to increase fiber intake in daily diets. Also, as biscuits currently on the Argentine and other world markets present two extreme varieties , with or without added salt , formulating a biscuit with 50% less added salt facilitate sodium reduction. In our research we have found that these goals can be achieved without seriously affecting sensory acceptability. We propose the articulation of the necessary strategies with the food industry to market biscuits with less added salt and more fiber for the general population; and the use of these healthier biscuits by institutional food services. [source]

DIBER: protein, DNA or both?

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2010
Grzegorz Chojnowski
The program DIBER (an acronym for DNA and FIBER) requires only native diffraction data to predict whether a crystal contains protein, B-form DNA or both. In standalone mode, the classification is based on the cube root of the reciprocal unit-cell volume and the largest local average of diffraction intensities at 3.4,Å resolution. In combined mode, the Phaser rotation-function score (for the 3.4,Å shell and a canonical B-DNA search model) is also taken into account. In standalone (combined) mode, DIBER classifies 87.4 ± 0.2% (90.2 ± 0.3%) of protein, 69.1 ± 0.3% (78.8 ± 0.3%) of protein,DNA and 92.7 ± 0.2% (90.0 ± 0.2%) of DNA crystals correctly. Reliable predictions with a correct classification rate above 80% are possible for 36.8 ± 1.0% (60.2 ± 0.4%) of the protein, 43.6 ± 0.5% (59.8 ± 0.3%) of the protein,DNA and 83.3 ± 0.3% (82.6 ± 0.4%) of the DNA structures. Surprisingly, selective use of the diffraction data in the 3.4,Å shell improves the overall success rate of the combined-mode classification. An open-source CCP4/CCP4i -compatible version of DIBER is available from the authors' website at http://www.iimcb.gov.pl/diber and is subject to the GNU Public License. [source]

Carbon Long Fiber Reinforced Aluminum Matrix Composites , Parameter Studies and Numerical Simulations of the Infiltration Process,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Heiko Ballmes
Within this work, the development of a cost efficient and reliable production technique for infiltrating carbon fibers with aluminum using a conventional cold chamber die casting machine is reported. Results are presented that demonstrate the large potential of pressure die casting as a low cost manufacturing process for carbon fiber reinforced aluminum matrix composites. The influence of process parameters on the infiltration behaviour is investigated and compared to results gained by numerical simulation. [source]

Dedicated Applications of Carbon Fiber Reinforced Plastics in Machine Engineering

ADVANCED ENGINEERING MATERIALS, Issue 3 2004
B. Wielage
Machine engineering has an inherent potential concerning the use of high performance material like Carbon Fibre Reinforced Plastics. The authors show some successful substitutions of formerly conventionally designed components by CFRP-parts. The examples are taken from several branches of machine engineering, especially from textile machine engineering. [source]

Fabrication and Electromechanical Characterization of a Piezoelectric Structural Fiber for Multifunctional Composites

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Yirong Lin
Abstract The use of piezoceramic materials for structural sensing and actuation is a fairly well developed practice that has found use in a wide variety of applications. However, just as advanced composites offer numerous benefits over traditional engineering materials for structural design, actuators that utilize the active properties of piezoelectric fibers can improve upon many of the limitations encountered when using monolithic piezoceramic devices. Several new piezoelectric fiber composites have been developed; however, almost all studies have implemented these devices such that they are surface-bonded patches used for sensing or actuation. This paper will introduce a novel active piezoelectric structural fiber that can be laid up in a composite material to perform sensing and actuation, in addition to providing load bearing functionality. The sensing and actuation aspects of this multifunctional material will allow composites to be designed with numerous embedded functions, including structural health monitoring, power generation, vibration sensing and control, damping, and shape control through anisotropic actuation. This effort has developed a set of manufacturing techniques to fabricate the multifunctional fiber using a SiC fiber core and a BaTiO3 piezoelectric shell. The electromechanical coupling of the fiber is characterized using an atomic force microscope for various aspect ratios and is compared to predictions made using finite element modeling in ABAQUS. The results show good agreement between the finite element analysis model and indicate that the fibers could have coupling values as high as 68% of the active constituent used. [source]

Influence of Structural Principles on the Mechanics of a Biological Fiber-Based Composite Material with Hierarchical Organization: The Exoskeleton of the Lobster Homarus americanus

ADVANCED MATERIALS, Issue 4 2009
Helge-Otto Fabritius
Abstract The cuticle of the lobster Homarus americanus is a nanocomposite, such as most structural biological materials. It consists of a matrix of chitin-protein fibers associated with various amounts of crystalline and amorphous calcium carbonate in the rigid parts of the body, and is organized hierarchically at all length scales. One prominent design principle found in the hierarchical structure of such biological fibrous composite materials is the twisted plywood structure. In the lobster cuticle, it is formed by superimposing and gradually rotating planes of parallel aligned chitin-protein fibers. To adjust the mechanical properties to the requirements on the macroscopic level, the spatial arrangement and the grade of mineralization of the fibers can be modified. A second design principle of lobster cuticle is its honeycomb-like structure, generated by the well-developed pore canal system, whose twisted ribbon-shaped canals penetrate the cuticle perpendicular to its surface. Due to the hierarchical structure, the mechanical properties of the lobster cuticle have to be investigated at different length scales, which is essential for the understanding of the structure,mechanical function relations of mineralized tissues (e.g., potentially also bone and teeth). In order to investigate the influence of the structural principles on the mechanical properties on the macroscopic scale miniaturized tensile, compression, and shear tests were carried out to obtain integral mechanical data. Characterization of the microstructure included scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) measurements. [source]

Fiber Shaped Light Emitting Device,

ADVANCED MATERIALS, Issue 22 2007
B. O'Connor
A fiber based organic light emitting device (OLED) is demonstrated. Electrically, the device performs similarly to planar analogs, but unlike the planar devices, the fiber OLED exhibits an emission spectrum that is independent of the observation angle. This property may find application in OLED structures for display and lighting applications. The flexible fiber geometry potentially allows for new low cost manufacturing approaches. [source]

A Glass Hook Allows Fishing of Hexa- peri -hexabenzocoronene Graphitic Nanotubes: Fabrication of a Macroscopic Fiber with Anisotropic Electrical Conduction,

ADVANCED MATERIALS, Issue 10 2006
Y. Yamamoto
Fishing of graphitic nanotubes with a macroscopic glass hook: A ,30,mm long fiber (see figure and cover) is readily processed from a suspension of self-assembled nanotubes with one-handed helical chirality, formed from the (R)- or (S)-enantiomer of chiral amphiphile 2. The majority of the nanotubes in the fiber are unidirectionally oriented along the fiber axis. Upon doping with I2, the fiber displays an anisotropic electrical conduction along the fiber axis more than an order of magnitude greater than that across the fiber axis. [source]

Modeling and simulation of mixed traffic on a prioritized shared medium

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2003
Jeffrey J. Evans
Network access systems (NAS) such as digital loop carriers (DLC) are increasingly utilizing a shared medium, such as Hybrid Fiber Coax (HFC) to provide point-to-multi-point access from the public switched telephone network (PSTN) to the end user (consumer). New services, such as direct access to the packet switched network (PSN, WWW) have been added to DLC equipment in such a way as to provide for a prioritized set of services over a shared medium in an effort to take advantage of otherwise unused bandwidth. The introduction of such services requires the modeling and analysis of these network access systems. This becomes complex when considering the variability in different service type traffic characteristics. This work identifies a traffic engineering problem of prioritized circuit switched and packet switched (PSTN/PSN) traffic over the same shared medium as it may relate to "perceived" quality of service (QoS). Copyright © 2002 John Wiley & Sons, Ltd. [source]

Effects of Grazing on Bituminaria bituminosa (L) Stirton: A Potential Forage Crop in Mediterranean Grasslands

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2006
M. Sternberg
Abstract Plant traits of Bituminaria bituminosa, as affected by different intensities of cattle grazing, were studied in a Mediterranean grassland in Israel. B. bituminosa is a widespread Mediterranean perennial legume species that may potentially serve as a fodder crop in Mediterranean grasslands. The aims of the present study were: (i) to evaluate the responses of B. bituminosa to different cattle grazing intensities; (ii) to study functional traits associated with grazing tolerance; and (iii) to evaluate its potential as an alternative forage crop in the region. A total of 100 B. bituminosa plants were monitored in field conditions. During the growing season each individual was sampled five times and the following plant traits were monitored each time: (i) aboveground biomass production, (ii) plant height, (iii) specific leaf area (SLA), (iv) number of flowers, (v) seed mass and size, (vi) tannin concentration in leaves, (vii) total nitrogen in leaves, (viii) fibre concentration in leaves (Neutral Detergent Fiber), and (ix) in vitro dry matter digestibility. The results showed that grazing intensity and history of grazing affected B. bituminosa performance. Plant biomass, height, and flower and seed production were all reduced when plants were exposed to cattle grazing. However, under moderate grazing intensities, its plant cover remained relatively stable indicating a potential tolerance under this stocking rate. The nutritious characteristics of B. bituminosa leaves were good, and the condensed tannins concentration found indicated favourable conditions for digestion. Moreover, the in vitro digestibility studies indicated relatively high values (46,51 %) of digestion. B. bituminosa may be considered as a potential crop for cattle feeding in Mediterranean grasslands. Growing this plant in dense stands in rotational paddocks may provide alternative sources of natural fodder protein, reducing the potential costs of artificial feed supplements. [source]

Latent Mahaim Fiber as a Cause of Antidromic Reciprocating Tachycardia: Recognition and Successful Radiofrequency Ablation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2002
M.R.C.P., NEIL C. DAVIDSON M.B.
Latent Mahaim Fiber. The term "Mahaim fiber" usually is applied to an atriofascicular fiber that inserts distally into the right bundle branch and forms the anterograde limb of a reciprocating tachycardia. One of the features that has been used to describe the physiology of Mahaim fibers is the presence of anterograde preexcitation. We describe two patients who had a clinical tachycardia consistent with a "Mahaim tachycardia" in whom there was no evidence or minimal evidence of anterograde preexcitation during sinus rhythm or atrial pacing. In both patients, the tachycardia was rendered noninducible by radiofrequency ablation at the site of Mahaim potentials at the tricuspid annulus, and a long-term cure was achieved. This is the first description of a "latent Mahaim fiber" that does not cause preexcitation but which can support antidromic reciprocating tachycardia. [source]

BAKING PROPERTIES OF MILK PROTEIN-COATED WHEAT BRAN,

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2008
CHARLES I. ONWULATA
ABSTRACT Increasing the dietary fiber content of formulated foods will benefit the health and nutrition of consumers. The problem is that it is difficult to add substantial amounts of dietary fiber to formulated foods. Fiber absorbs significant amounts of water from surrounding ingredients creating texture problems such as soggy and dry patches in the foods. In this study, red wheat bran milled and sieved smaller than 140 microns was coated by spraying with a 50/50 emulsion of whey protein isolates (WPIs) and casein. WPI and casein emulsion was produced first by blending and shearing the milk proteins in ice and water and then evaporating under partial vacuum for 75 min at 45C. Cookies and muffins made with the milk protein-coated red wheat (MPCF) bran and the noncoated wheat bran (NCF), replacing 5, 10 and 15 wt % of the flour, were compared to control cookies and muffins made without added fiber. The water-holding capacity (WHC) of the MPCF and NCF was determined along with their moisture, color, hardness, and volume in the baked cookies and muffins. There was a significant (P < 0.01) improvement (250%) in loss of WHC of MPCF over NCF. In cookies, MPCF absorbed significantly less water and was slightly darker at 5 wt % substitution than NCF, but was between 12 to 60% higher in baked volume than the control. MPCF muffins were lighter in color and harder except for the 5 wt % muffins that were softer and higher in percent baked volume. Adding up to 15-g MPCF per 100 g batter can be added to baked cookies and muffins to increase fiber content and improve WHC and volume. PRACTICAL APPLICATIONS This study determined that coating wheat bran with specially treated dairy proteins reduced the amount of water the bran can absorb when added up to 15 wt% to formulations, or in the finished products, helping to maintain textural integrity of products. The intact wheat bran remains available for its functional health enhancing roles when consumed and digested. This knowledge allows the creation of nutritious high-fiber products with desirable texture. [source]

Addition of Soluble Soybean Polysaccharides to Dairy Products as a Source of Dietary Fiber

JOURNAL OF FOOD SCIENCE, Issue 6 2010
Wenpu Chen
Abstract:, Increasing consumption of dietary fiber in food leads to many important health benefits: for example, reduction in blood cholesterol, reduced risk of diabetes, and improved laxation. Water soluble soybean polysaccharide (SSPS) is a dietary fiber extracted and refined from okara, a byproduct of soy manufacturing. It was incorporated into 3 categories of dairy-based products, thickened milkshake-style beverages, puddings, and low-fat ice cream, to the maximum amount without over-texturing the food. Rheological measurements and sensory tests were used to develop desirable SSPS-fortified products. From the rheological data, 4% SSPS-fortified dairy beverages and 4% SSPS -fortified puddings were in the range of commercial products. From sensory analyses, 4% SSPS-fortified dairy beverage with 0.015%,,carrageenan, 4% SSPS-fortified pudding with 0.1%,,carrageenan, and 2% SSPS-fortified low-fat ice cream gained the highest scores in consumer hedonic rating. Panelists also indicated their willingness to consume those products if they were available commercially. Practical Application:, Since the dietary fiber intake of many people is below their suggested adequate intake values, strategies to successfully fortify foods with fiber may help alleviate this gap. We have developed 3 dairy products, a beverage, a pudding, and a low-fat ice cream, that have been fortified with soluble soybean polysaccharide at levels of 4%, 4%, and 2%, respectively. These products were within acceptable ranges of rheological parameters and other physical stability measurements and were judged to be acceptable by sensory analyses. [source]

Extraction and Application of Dietary Fiber and Cellulose from Pineapple Cores

JOURNAL OF FOOD SCIENCE, Issue 4 2002
T. Prakongpan
Pineapple core dietary fiber (PDF) was obtained by alcoholic extraction; pineapple core cellulose (PC) was a product of alkali extraction with a bleaching process. Total dietary fiber content of PDF and PC was 99.8% and 95.2% (dry basis), respectively, and their water activity was 0.25. PC contained 91.2% cellulose with a pH value of 4.0, while that of PDF was 6.2. The fiber product with large particle size gave higher values than the product with smaller particles for pH, water and oil retention capacity, settling volume and emulsifying activity. Both had rough, pitted surfaces and presented showed good functions in cake-type doughnuts, golden layer cake and beef burgers. [source]

Characteristics of Hollow TiO2 Fibers Via Replication of Sisal Fiber

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2007
Guangqin Li
Here we report a facile method to fabricate hollow TiO2 fibers in micro-scale via faithfully replication of sisal fiber. The length of the as-synthesized fibers could reach several millimeters and consist of a bundle of hollow sub-fibers. The fibers have node, pits, and crevices on their surface, which faithfully sustain the characteristics of the template. The phase transformation and photocatalytic activity of the fibers were also studied. [source]

Thermal Stability of a Chemically Vapor Deposited Multilayer Coating Containing Amorphous Silica and Rutile Titania on Hi-Nicalon Fiber

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2003
Jinil Lee
A multilayer coating consisting of consecutive layers of amorphous-silica, rutile-titania, and amorphous-silica was prepared on Hi-Nicalon fiber by chemical vapor deposition at 1050°C. It appeared that the silica and titania layers were strongly bonded to each other with no evidence of detachment and crack deflection at the interface region. The layered structure became morphologically unstable because of the growth of titania grains, the crystallization of the silica layers, and the oxidation of the fiber on exposure to 1200°C in air for 92 h. [source]

Fabrication of Arsenic Selenide Optical Fiber with Low Hydrogen Impurities

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2002
Vinh Q. Nguyen
Arsenic selenide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of 0.1 wt% tellurium tetrachloride (TeCl4) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to give very low H,Se impurity content. Consequently, the H,Se absorption band centered at 4.57 ,m has been reduced from tens of dB/m to 0.2 dB/m. [source]

Fabrication of Arsenic Sulfide Optical Fiber with Low Hydrogen Impurities

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2002
Vinh Q. Nguyen
Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl4) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m). [source]

Alkoxide Sol-Gel-Processed Cordierite Fiber

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2002
Mu-Tsun Tsai
An alkoxide sol-gel route was developed to prepare stoichometric cordierite fibers. The influences of the aging treatment and heating rate on the sinterability of the gel fibers were also examined. X-ray diffraction analysis revealed that the unaged and aged fibrous gels all remained amorphous <800&, but began crystallization into ,-cordierite and ,-cordierite at ,900°C and 1050°C, respectively; single-phase ,-cordierite fibers were obtained at 1300°C. Heating the unaged fibers yielded denser microstructures, with fine grain sizes of ,0.2,0.4 ,m, whereas the aged fibers exhibited porous microstructures following heating at 1300°C. A higher heating rate and aging treatment resulted in a higher open porosity of the fired fiber. [source]

Coarsening of Lamellar Microstructures in Directionally Solidified Yttrium Aluminate/Alumina Eutectic Fiber

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2001
Deok-Yong Park
Coarsening of the fine lamellar structure of a directionally solidified Y3Al5O12 (yttrium aluminum garnet, YAG)/Al2O3 eutectic fiber at elevated temperatures was investigated. The fibers were grown continuously by an edge-defined film-fed growth (EFG) technique. To study the thermal stability of the lamellar structure, the fibers were heat-treated in air at 1360°,1460°C for up to 200 h. X-ray diffractometry and scanning electron microscopy were used to characterize the microstructures of the fibers. Image analysis was used to measure the length of the interface line between Y3Al5O12 and Al2O3 phases. The kinetics of coarsening and the rate-controlling mechanisms were investigated. Also, the Graham and Kraft model for describing the coarsening behavior of the lamellar Al-CuAl2 eutectic alloy was used to explain the coarsening behavior of Y3Al5O12/Al2O3 eutectic fiber. [source]

Characterization of Methyl Methacrylate Grafting onto Preirradiated Biodegradable Lignocellulose Fiber by , -Radiation

MACROMOLECULAR BIOSCIENCE, Issue 1 2005
Ferdous Khan
Abstract Summary: Gamma-radiation-induced graft copolymerization of methyl methacrylate onto natural lignocellulose (jute) fiber was carried out by the preirradiation method in an aqueous medium by using octylphenoxy-polyethoxyethanol as an emulsifier. The different factors that influenced the graft copolymer reaction process were investigated. In the case of radiation-dose-dependent grafting, samples irradiated in the presence of air produced up to 73% graft weight compared to 53% obtained in the case of irradiation in a nitrogen environment. By assuming Arrhenius reaction kinetics, the activation energy (Ea) of the grafting reaction process was evaluated for different reaction temperatures. Moreover, the graft copolymer reaction was controlled by incorporating a homopolymer-inhibiting agent and three different chain-transfer agents in the reaction medium. The mechanical and thermal properties of jute fiber ,as received' and jute- graft -poly(methyl methacrylate) were also investigated. The results showed that the percentage of grafting with jute fiber has a significant effect on the properties. The kinetic parameters were evaluated from TGA thermograms by using Broido's method in the temperature range 240,350,°C. Scanning electron micrographs show that the structural changes on the surface of jute fibers were induced by graft copolymerization of methyl methacrylate monomer. Fiber-fiber surface friction was measured in terms of the average maximum load and the kinetic friction. SEM of jute- graft -poly(methyl methacrylate). [source]

Study on the Graft Reaction of Poly(propylene) Fiber with Acrylic Acid

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2006
Wei Wang
Abstract Summary: In this paper, the graft of poly(propylene) fiber with acrylic acid is investigated. The effects of grafting temperature, monomer concentration, and grafting time on the grafting degree of acrylic acid onto poly(propylene) fiber are discussed. In contrast to the conventional method of determining the grafting degree gravimetrically, the acid-base titration method used in this paper was more efficient, even at low grafting degree. High-performance liquid chromatography (HPLC) was used to estimate the averaged length of the grafted poly(acrylic acid) chains on each grafted site of poly(propylene) backbone. And also a mechanism for the grafting polymerization is proposed. Possible microstructures of two PP-g-AA samples at the same grafting degree. [source]

Mechanical Properties of a Single Electrospun Fiber and Its Structures

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 9 2005
Shu-Ying Gu
Abstract Summary: A method to measure the Young's modulus of a single electrospun polyacrylonitrile (PAN) fiber is reported. The Young's modulus can be calculated from the force-displacement curves obtained by the bending of a single fiber attached to an atomic force microscopy (AFM) cantilever. It is suggested that the high modulus of electrospun fibers is caused by the orientation of molecular chains, which is confirmed by wide-angle X-ray diffraction (WAXD) measurements. The communication will provide a basic understanding of the relationship between mechanical properties and structures of electrospun fibers. A PAN fiber was attached to a contact mode cantilever to facilitate the measurement of force-displacement curves and Young's modulus. [source]

Processing of a Strong Biodegradable Poly[(R)-3-hydroxybutyrate] Fiber and a New Fiber Structure Revealed by Micro-Beam X-Ray Diffraction with Synchrotron Radiation

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 11 2004
Tadahisa Iwata
Abstract Summary: Biodegradable poly[(R)-3-hydroxybutyrate] (P(3HB)) fibers with high tensile strength of 1.32 GPa were processed from ultra-high-molecular-weight P(3HB) by a method combining cold-drawing and two-step-drawing procedures at room temperature. The distribution of molecular structures in a mono-filament was analyzed by micro-beam X-ray diffraction with synchrotron radiation. It was revealed that the P(3HB) fiber has a new core-sheath structure consistent with two types of molecular conformations: a 21 helix conformation in the sheath region and a planar zigzag conformation in the core region. P(3HB) fiber processed by cold-drawing in ice water and two-step drawing at room temperature, and subsequently annealing at 50,°C. [source]

Polycarbonate Crystallization by Vapor-Grown Carbon Fiber with and without Magnetic Field

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2003
Tatsuhiro Takahashi
Abstract Polycarbonate (PC)/vapor-grown carbon fiber (VGCFÔ) composite was prepared through melt compounding. It was unexpectedly found from differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) that the crystallization of PC was substantially accelerated in the presence of the ordered graphite surface of VGCFÔ. To make an aligned structure of PC crystallization together with the orientation of VGCFÔ, a magnetic field of 2.4 T was applied to the composite under several temperature profiles. The WAXD pattern revealed that not only dispersed VGCFÔ but also matrix PC crystallization was magnetically aligned through the optimization of processes. The evidence for PC crystallization by VGCFÔ with and without magnetic force is described. Optical micrograph (a) and WAXD pattern (b) of PC/VGCFÔ (95:5 wt. ratio) composite which was treated under a magnetic field (vertical direction) of 2.4 T under an optimized heating profile. [source]

Theoretical and experimental study of polarization characteristics of polarization maintaining fiber based on wavelength-sweeping modulation

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2010
Zuo-Liang Duan
Abstract We analyze theoretically the polarization characteristics of polarization maintaining fiber and study the basic measurement principles of beat length and polarization extinction ratio of this kind of optical fiber. According to the dependence of the phase difference between two orthogonally polarized modes (denoted as HE and HE) transmitted in the polarization maintaining fiber on the light wavelength, we propose the wavelength-sweeping modulation method to measure the beat length and the model birefringence. Based on this technique, the beat length and polarization extinction ratio of the PANDA polarization maintaining fibers (PMFs) (provided by Yangtze Optical Fiber and Cable Company, Wuhan, China) were investigated in detail. Experimental results show good consistent with the theoretical ones. We find that this method shows high measurement precision with the advantages of clear measurement principle and easy to operate. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1466,1469, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25244 [source]

Influence of Dietary Fiber on Inflammatory Bowel Disease and Colon Cancer: Importance of Fermentation Pattern

NUTRITION REVIEWS, Issue 2 2007
Devin J. Rose MS
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. [source]

Dietary Fiber and Weight Regulation

NUTRITION REVIEWS, Issue 5 2001
Nancy C. Howarth M.Sc
The influence of dietary fiber on energy regulation remains controversial. This review summarizes published studies on the effects of dietary fiber on hunger, satiety, energy intake, and body composition in healthy individuals. Under conditions of fixed energy intake, the majority of studies indicate that an increase in either soluble or insoluble fiber intake increases postmeal satiety and decreases subsequent hunger. When energy intake is ad libitum, mean values for published studies indicate that consumption of an additional 14 g/day fiber for >2 days is associated with a 10% decrease in energy intake and body weight loss of 1.9 kg over 3.8 months. Furthermore, obese individuals may exhibit a greater suppression of energy intake and body weight loss (mean energy intake in all studies was reduced to 82% by higher fiber intake in overweight/obese people versus 94% in lean people; body weight loss was 2.4 kg versus 0.8 kg). These amounts are very similar to the mean changes in energy intake and body weight changes observed when dietary fat content is lowered from 38% to 24% of energy intake in controlled studies of nonobese and obese subjects. The observed changes in energy intake and body weight occur both when the fiber is from naturally high-fiber foods and when it is from a fiber supplement. In view of the fact that mean dietary fiber intake in the United States is currently only 15 g/day (i.e., approximately half the American Heart Association recommendation of 25,30 g/day), efforts to increase dietary fiber in individuals consuming >25 g/day may help to decrease the currently high national prevalence of obesity. [source]

Mesoscopic Structure and Properties of Liquid Crystalline Mesophase Pitch and Its Transformation into Carbon Fiber

THE CHEMICAL RECORD, Issue 2 2002
Isao Mochida
Abstract The history and present state of the art in the chemistry of mesophase pitch, which is an important precursor for carbon fiber and other high-performance industrial carbons, are reviewed relative to their structural properties. The structural concepts in both microscopic and macroscopic views are summarized in terms of the sp2 carbon hexagonal plane as a basic unit common to graphitic materials, its planar stacking in clusters, and cluster assembly into microdomains and domains, the latter of which reflect the isochromatic unit of optical anisotropy. Such a series of structural units is described in a semiquantitative manner corresponding to the same units of graphitic materials, although the size and stacking height of the hexagonal planes (graphitic sheets) are very different. Mesophase pitch is a liquid crystal material whose basic structural concepts are maintained in the temperature range of 250 to 350,°C. The melt flow and thermal properties are related to its micro- and mesoscopic structure. The structure of mesophase-pitch,based carbon fiber of high tensile strength, modulus, and thermal conductivity has been formed through spinning, and has inherited the same structural concepts of mesophase pitch. Stabilization settles the structure in successive heat treatments up to 3000,°C. Carbonization and graphitization enable growth of the hexagonal planes and their stacking into units of graphite. Such growth is governed and controlled by the alignment of micro- and mesoscopic structures in the mesophase pitch, which define the derived carbon materials as nanostructural materials. Their properties are controlled by the nanoscopic units that are expected to behave as nanomaterials when appropriately isolated or handled. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2:81,101, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10016 [source]

Collagen Fiber and Versican Distribution Within the Lamina Propria of Fetal Vocal Folds,

THE LARYNGOSCOPE, Issue 2 2008
Rogerio Borghi Buhler MD
Abstract Objectives: To analyze the presence and distribution of collagen fibers and versican in human vocal fold lamina propria of fetal larynges. Study Design: Cross sectional analysis of cadaveric vocal folds of human fetuses. Methods: Seven fetal larynges obtained from 28- to 36-week-old fetuses were analyzed with the Picrosirius-polarization method, immunohistochemistry, and image analysis. Results: Collagen fibers within the lamina propria exhibited a monolaminar distribution pattern and spatial arrangement in "wicker basket." Versican distribution was larger in the superficial and intermediate layers when compared to the deep layer. Conclusion: Our findings suggest that collagen and versican distribution and arrangement within the lamina propria in the developing fetus are important for vocalization at birth. [source]