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Ribbons
Kinds of Ribbons Selected AbstractsOrganic Single-Crystalline Ribbons of a Rigid "H"-type Anthracene Derivative and High-Performance, Short-Channel Field-Effect Transistors of Individual Micro/Nanometer-Sized Ribbons Fabricated by an "Organic Ribbon Mask" Technique,ADVANCED MATERIALS, Issue 14 2008Lang Jiang The synthesis of a rigid, planar H-type anthracene derivative is described. Single-crystalline ribbons at micro- and nanometer sizes can be controllably produced and transistors based on an individual ribbon can be fabricated in situ through a newly developed "organic ribbon mask" method, in which the channel length of the transistors can be easily scaled down to sub-micrometer level. [source] Mesoporous Silicas by Self-Assembly of Lipid Molecules: Ribbon, Hollow Sphere, and Chiral MaterialsCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2008Haiying Jin Abstract Using lipids (N -acyl amino acids) and 3-aminopropyltriethoxysilane as structure- and co-structure-directing agents, mesoporous silicas with four different morphologies, that is, helical ribbon (HR), hollow sphere, circular disk, and helical hexagonal rod, were synthesized just by changing the synthesis temperature from 0,°C to 10, 15, or 20,°C. The structures were studied by electron microscopy. It was found that 1),the structures have double-layer disordered mesopores in the HR, radially oriented mesopores in the hollow sphere, and highly ordered straight and chiral 2D-hexagonal mesopores in the disklike structure and helical rod, respectively; 2),these four types of mesoporous silica were transformed from the flat bilayered lipid ribbon with a chain-interdigitated layer phase through a solid,solid transformation for HR formation and a dissolving procedure transformation for the synthesis of the hollow sphere, circular disk, and twisted morphologies; 3),the mesoporous silica helical ribbon was exclusively right-handed and the 2D-hexagonal chiral mesoporous silica was excessively left-handed when the L -form N -acyl amino acid was used as the lipid template; 4),the HR was formed only by the chiral lipid molecules, whereas the 2D-hexagonal chiral mesoporous silicas were formed by chiral, achiral, and racemic lipids. Our findings give important information for the understanding of the formation of chiral materials at the molecular level and will facilitate a more efficient and systematic approach to the generation of rationalized chiral libraries. [source] Micrometer- and Nanometer-Sized, Single-Crystalline Ribbons of a Cyclic Triphenylamine Dimer and Their Application in Organic TransistorsADVANCED MATERIALS, Issue 16 2009Rongjin Li A cyclic triphenylamine dimer with high crystallinity is demonstrated. Micrometer- and nanometer-sized single-crystalline ribbons are easily produced by a physical vapor transport technique. Field-effect transistors of the ribbons exhibit mobilities up to 0.05,cm2 V,1 s,1. The mobility of the devices depends greatly on the size of the ribbons: the smaller the ribbons, the higher the mobility. [source] Organic Single-Crystalline Ribbons of a Rigid "H"-type Anthracene Derivative and High-Performance, Short-Channel Field-Effect Transistors of Individual Micro/Nanometer-Sized Ribbons Fabricated by an "Organic Ribbon Mask" Technique,ADVANCED MATERIALS, Issue 14 2008Lang Jiang The synthesis of a rigid, planar H-type anthracene derivative is described. Single-crystalline ribbons at micro- and nanometer sizes can be controllably produced and transistors based on an individual ribbon can be fabricated in situ through a newly developed "organic ribbon mask" method, in which the channel length of the transistors can be easily scaled down to sub-micrometer level. [source] Macroscopic Fibers of Oriented Vanadium Oxide Ribbons and Their Application as Highly Sensitive Alcohol Microsensors,ADVANCED MATERIALS, Issue 24 2005L. Biette Vanadium oxide macroscopic fibers (see Figure) are obtained by an extrusion process. The fibers consist of nanoscopic ribbons with a preferential orientation and a longitudinal Young's modulus of around 15,GPa. As well as showing high sensitivity, the fibers reversibly cycle between insulating and semiconducting upon exposure to alcohol vapor sources, with signature responses to different alcohols. [source] ChemInform Abstract: La8Br7Ni4: Ribbons of Ni Hexagons in Condensed La6 Trigonal Prisms.CHEMINFORM, Issue 10 2009Chong Zheng Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Magnetocaloric Effect in LaFe11.8-xCoxSi1.2 Melt-Spun Ribbons.CHEMINFORM, Issue 14 2008A. Yan Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Rare-Earth Gallium Antimonides La13Ga8Sb21 and Ln12Ga4Sb23 (Ln: La,Nd, Sm): Linking Sb Ribbons by Ga6 -Rings or Ga2 -Pairs.CHEMINFORM, Issue 2 2001Allison M. Mills Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Rigid,Flexible Block Molecules Based on a Laterally Extended Aromatic Segment: Hierarchical Assembly into Single Fibers, Flat Ribbons, and Twisted RibbonsCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2008Eunji Lee Abstract Self-assembling rigid,flexible block molecules consisting of a laterally extended aromatic segment and different lengths of hydrophilic coils were synthesized and characterized. The block molecule based on a long poly(ethylene oxide) coil (1), in the melt state, shows an unidentified columnar structure, whereas the molecule with a shorter poly(ethylene oxide) coil (2) self-organizes into an oblique columnar structure. Further decrease in the poly(ethylene oxide) coil length as in the case of 3, on heating, induces a rectangular columnar structure in addition to an oblique columnar mesophase. In diethyl ether, 1 and 2 were observed to self-assemble into uniform nanofibers with bilayer packing. Remarkably, these elementary fibers were observed to further aggregate in a lateral way to form well-defined flat ribbons (1) and twisted ribbons (2) with solvent exchange of diethyl ether into methanol. Furthermore, the ribbons formed in methanol dissociated into elementary fibers in response to the addition of aromatic guest molecules. This transformation between ribbons and single fibers in response to the addition of guest molecules is attributed to the intercalation of aromatic substrates within the rigid segments and subsequent loosening of the aromatic stacking interactions. These results demonstrate that the introduction of a laterally extended aromatic segment into an amphiphilic molecular architecture can lead to the hierarchical formation from elementary fibers of nanoribbons with a tunable twist through controlled lateral interactions between aromatic segments. [source] Self-Assembly of Amylin(20,29) Amide-Bond Derivatives into Helical Ribbons and Peptide Nanotubes rather than FibrilsCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2006Ronald C. Elgersma Abstract Uncontrolled aggregation of proteins or polypeptides can be detrimental for normal cellular processes in healthy organisms. Proteins or polypeptides that form these amyloid deposits differ in their primary sequence but share a common structural motif: the (anti)parallel , sheet. A well-accepted approach for interfering with ,-sheet formation is the design of soluble ,-sheet peptides to disrupt the hydrogen-bonding network; this ultimately leads to the disassembly of the aggregates or fibrils. Here, we describe the synthesis, spectroscopic analysis, and aggregation behavior, imaged by electron microscopy, of several backbone-modified amylin(20,29) derivatives. It was found that these amylin derivatives were not able to form fibrils and to some extent were able to inhibit fibril growth of native amylin(20,29). However, two of the amylin peptides were able to form large supramolecular assemblies, like helical ribbons and peptide nanotubes, in which ,-sheet formation was clearly absent. This was quite unexpected since these peptides have been designed as soluble ,-sheet breakers for disrupting the characteristic hydrogen-bonding network of (anti)parallel , sheets. The increased hydrophobicity and the presence of essential amino acid side chains in the newly designed amylin(20,29) derivatives were found to be the driving force for self-assembly into helical ribbons and peptide nanotubes. This example of controlled and desired peptide aggregation may be a strong impetus for research on bionanomaterials in which special shapes and assemblies are the focus of interest. [source] Axonemal localization of Chlamydomonas PACRG, a homologue of the human Parkin -coregulated gene productCYTOSKELETON, Issue 11 2007Kazuho Ikeda Abstract A homologue of mammalian PACRG was identified in Sarkosyl-extracted Chlamydomonas axonemes as a protein that may interact with Rib72 (a component of the protofilament ribbon within the outer doublet microtubules). PACRG is a protein whose expression is co-regulated with the Parkin gene implicated in Parkinson's disease. Although subsequent analyses did not confirm a Rib72-PACRG interaction, both proteins display similar localization in the axoneme. Immuno-localization of PACRG required pretreatment of the axoneme with Sarkosyl, suggesting that the antigen is buried in the wall of the microtubule. Indirect immunofluorescence localized PACRG to the entire length of the axoneme and the basal body, and immuno-electron microscopy showed that the PACRG antigen is densely distributed along the outer doublets in frayed axonemes. In thin-section images, the PACRG signals were frequently found between the A- and B-tubules of adjacent outer doublets. From these and other results, we propose that PACRG is a structural component of the doublet and triplet microtubules possibly involved in inter-tubule linkage. Cell Motil. Cytoskeleton, 2007. © 2007 Wiley-Liss, Inc. [source] An alternative method for splinting of traumatized teeth: case reportsDENTAL TRAUMATOLOGY, Issue 6 2006Gülsün Yildirim Öz Abstract,,, Injuries to the dentoalveolar complex are fairly common and can be caused by a number of reasons. There are many techniques for repositioning and stabilizing traumatically luxated or avulsed teeth. Many of the splinting techniques previously advocated were time-consuming. Not only were the splints difficult to fabricate and difficult to remove, they also contributed to injury of the soft and hard supporting tissues. Ribbond (Ribbond Inc., Seattle, Wash) is basically a reinforced ribbon which is made from ultrahigh molecular weight polyethylene fiber having an ultrahigh modulus. It is used in dentistry for various purposes. The use of Ribbond appears to be an adequate and easy method for stabilization and fixation. It can be used in the treatment of dental injuries. In this article the use of Ribbond for the treatment of dentoalveolar injuries is described. [source] Genital system anatomy and development of Ovatella myosotis by three-dimensional computer visualizationACTA ZOOLOGICA, Issue 2 2009Bernhard Ruthensteiner Abstract Adult anatomy as well as organogenesis of the genital system of the ellobiid pulmonate Ovatella myosotis is investigated in detail by means of serial sectioning and three-dimensional computer reconstruction and visualization. From the middle portion of the adult, which has four nidamental glands, a spermoviduct leads to a common genital aperture. From here two separate structures, the vas deferens and a groove on the body surface, lead anteriorly. The latter is termed the egg groove because it carries the egg ribbon anteriorly, a function that is recognized here for the first time in the Ellobiidae. The evolution of this structure is discussed. In development, the organ system arises from four separate anlagen: (1) the ovotestis anlage, (2) the pallial anlage giving rise to the hermaphrodite duct, fertilization pouch,spermatheca complex, nidamental glandular complex and spermoviduct, (3) the bursa copulatrix anlage and (4) the anlage of the copulatory organ, vas deferens and egg groove. This development mode strongly resembles that of the siphonariid Williamia radiata, supporting its interpretation as a plesiomorphy in Pulmonata. Similarities in development of primitive pulmonates and evolution in gastropods lead to the assumption that ontogenesis of this organ system reflects evolution to some degree. [source] Systematic and morphological studies of the genus Chaetopleurophora Schmitz (Diptera: Phoridae) occurring in JapanENTOMOLOGICAL SCIENCE, Issue 4 2007Hiroto NAKAYAMA Abstract Japanese species of the genus Chaetopleurophora are reviewed. All belong to the C. erythronota group. The following three species from Japan are described: C. rhomboidea sp. nov., C. pygidialis Schmitz and C. dividua sp. nov. The male and female genitalia are studied and further examples of unique characters of the genus including asymmetric features are added. The male aedeagus of the genus is illustrated for the first time. The aedeagus of the species treated in this study consists of only two components, the inner core plate and the outer jacket plate. The jacket plate wraps sinistrally around the core plate. The combination of the core plate and the jacket plate forms complex, asymmetric features of the aedeagus in the Phoridae. The structure around the genital opening in the female genitalia protrudes posteriorly under the segment IX + X, and shows asymmetric features in C. rhomboidea sp. nov. with a bilaterally different degree of sclerotization, shifted genital opening to the right side and a membranous ribbon just on the left side. In addition, C. dividua sp. nov. is different from most of the species in the C. erythronota group, and very closely related to C. multiseriata (known in North America) in the male and female genitalia, wing venation and bristle formation on the scutellum. It is suggested that C. dividua sp. nov. forms a monophyletic group with C. multiseriata and the related species. [source] Cysteine-string protein in inner hair cells of the organ of Corti: synaptic expression and upregulation at the onset of hearingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2002Michel Eybalin Abstract Cysteine-string protein is a vesicle-associated protein that plays a vital function in neurotransmitter release. We have studied its expression and regulation during cochlear maturation. Both the mRNA and the protein were found in primary auditory neurons and the sensory inner hair cells. More importantly, cysteine-string protein was localized on synaptic vesicles associated with the synaptic ribbon in inner hair cells and with presynaptic differentiations in lateral and medial olivocochlear terminals , the cell bodies of which lie in the auditory brainstem. No cysteine-string protein was expressed by the sensory outer hair cells suggesting that the distinct functions of the two cochlear hair cell types imply different mechanisms of neurotransmitter release. In developmental studies in the rat, we observed that cysteine-string protein was present beneath the inner hair cells at birth and beneath outer hair cells by postnatal day 2 only. We found no expression in the inner hair cells before about postnatal day 12, which corresponds to the period during which the first cochlear action potentials could be recorded. In conclusion, the close association of cysteine-string protein with synaptic vesicles tethered to synaptic ribbons in inner hair cells and its synchronized expression with the appearance and maturation of the cochlear potentials strongly suggest that this protein plays a fundamental role in sound-evoked glutamate release by inner hair cells. This also suggests that this role may be common to ribbon synapses and conventional central nervous system synapses. [source] Ophiolite-bearing mélanges in southern ItalyGEOLOGICAL JOURNAL, Issue 2 2009Luigi Tortorici Abstract In southern Italy two ophiolite-bearing belts, respectively involved in the Adria-verging southern Apennines and in the Europe-verging thrust belt of the northern Calabrian Arc, represent the southward extension of the northern Apennines and of ,Alpine Corsica' ophiolitic units, respectively. They form two distinct suture zones, which are characterized by different age of emplacement and opposite sense of tectonic transport. The ophiolite-bearing units of the southern Apennines are represented by broken formation and tectonic mélange associated with remnants of a well-developed accretionary wedge emplaced on top of the Adria continental margin, with an overall NE direction of tectonic transport. These units consist of a Cretaceous-Oligocene matrix, which includes blocks of continental-type rocks and ophiolites with remnants of their original Upper Jurassic to Lower Cretaceous pelagic cover. The innermost portion of the accretionary wedge is represented by a polymetamorphosed and polydeformed tectonic units that underwent a Late Oligocene high pressure/low temperature (HP/LT) metamorphism. The northern Calabria ophiolitic-belt is indeed composed of west-verging tectonic slices of oceanic rocks which, embedded between platform carbonate units of a western continental margin at the bottom and the basement crystalline nappes of the Calabrian Arc at the top, are affected by a Late Eocene-Early Oligocene HP/LT metamorphism. The main tectonic features of these two suture zones suggest that they can be interpreted as the result of the closure of two branches of the western Neotethys separated by a continental block that includes the crystalline basement rocks of the Calabrian Arc. We thus suggest that the north-east verging southern Apennine suture constituted by a well-developed accretionary wedge is the result of the closure of a large Late Jurassic-Early Cretaceous oceanic domain (the Ligurian Ocean) located between the African (the Adria Block) and European continental margins. The northern Calabria suture derives indeed from the deformation of a very narrow oceanic-floored basin developed during the Mesozoic rifting stages within the European margin separating a small continental ribbon (Calabrian Block) from the main continent. Copyright © 2008 John Wiley & Sons, Ltd. [source] Single-Crystalline V2O5 Ultralong Nanoribbon WaveguidesADVANCED MATERIALS, Issue 23 2009Bin Yan High-aspect-ratio V2O5 nanoribbons are synthesized by thermal vapor deposition technique. Our results reveal that the nanoribbons can serve as effective active optical waveguides. In addition, the observation of strong Raman signals collected at the end of the ribbon indicate that the unique nanostructure could play a vital role in Raman amplifers and other nonlinear photonic components. [source] Bulk Heterojunction Solar Cells: The Role of Processing in the Fabrication and Optimization of Plastic Solar Cells (Adv. Mater.ADVANCED MATERIALS, Issue 14-15 200915/2009) Alan Heeger and co-workers report on page 1521 on the role of processing methodology in the fabrication and optimization of bulk heterojunction (BHJ) ,plastic' solar cells. Several techniques that have recently been used to optimize the BHJ nanomorphology are discussed and compared and some insights are given into the mechanisms behind these various techniques. The cover image depicts a multilayer solar cell ribbon along with the polymer, fullerene, and solvent additive, which were used to fabricate a low bandgap polymer solar cell with greater than 5% power conversion efficiency. [source] Organic Single-Crystalline Ribbons of a Rigid "H"-type Anthracene Derivative and High-Performance, Short-Channel Field-Effect Transistors of Individual Micro/Nanometer-Sized Ribbons Fabricated by an "Organic Ribbon Mask" Technique,ADVANCED MATERIALS, Issue 14 2008Lang Jiang The synthesis of a rigid, planar H-type anthracene derivative is described. Single-crystalline ribbons at micro- and nanometer sizes can be controllably produced and transistors based on an individual ribbon can be fabricated in situ through a newly developed "organic ribbon mask" method, in which the channel length of the transistors can be easily scaled down to sub-micrometer level. [source] Structural motifs in ,-pyridyl- and ,-furylcinnamic acid assemblies, A molecular modeling studyINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2001I. Pálinkó Abstract The aggregation properties of stereoisomeric 2-(3,-furyl)-3-phenylpropenoic acids (FU3E, FU3Z, ,-furylcinnamic acids) and 2-(4,-pyridyl)-3-phenylpropenoic acids (PY4E, PY4Z, ,-pyridylcinnamic acids) were studied by the PM3 semiempirical quantum chemical method. Calculations revealed that (aromatic)CH,N(O) hydrogen bonds made possible the attachment of dimer units; thus, virtually infinite chains can be built out of FU3Z, PY4E, and PY4Z. The energy-minimized structure had zig-zag configuration. PY4Z dimers allowed the formation of ribbonlike network; however, the number of structural units could not be increased infinitely. One of the furyl derivatives (FU3E) could not be stabilized either in the ribbon or the chain form; however, (aromatic)CH,, or (aromatic),,(aromatic), interactions contribute to the packing pattern of the two dimers. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 269,275, 2001 [source] SENSORY AND PHYSICAL CHARACTERISTICS AND STORAGE STABILITY OF HONEY-FLAVORED LOW-FAT EXTRUDED CHIPSJOURNAL OF FOOD QUALITY, Issue 1 2000JAMES F. FALLER ABSTRACT Consumer demand for low-fat "healthy" snacks challenges manufacturers to improve the health profile of their products while maintaining their appetizing taste. The objectives of this study were to: (1) investigate the effect of addition levels of honey on texture and consumer acceptability of extruded, baked low-fat/honey-flavored chips; (2) determine the degree of liking for the product; (3) and evaluate the influence of honey on storage stability. The product, consisting of grade A light amber honey (0, 6, 12, and 18%) in a corn masa/flour blend, was extrusion formed into a ribbon through a slit die. The product was baked, dried, packaged, and stored in an ambient environment. Increased honey level significantly increased flavor liking, sweetness and honey flavor intensity for the fresh and 10 week storage samples, and positively influenced consumer overall acceptability. [source] Vitreous cryo-sectioning of cells facilitated by a micromanipulatorJOURNAL OF MICROSCOPY, Issue 2 2006MARK S. LADINSKY Summary Sectioning vitrified cells and tissues for cryo-electron microscopy is more challenging than room-temperature sectioning of plastic-embedded samples. As the sample must be kept very cold (<,130 °C) and because there is no liquid upon which the sections can float as they are cut, transferring the sections from the knife edge to a grid is one of the more difficult steps in the process. We employed a micromanipulator to hold and control the cryo-sections as they come off the knife. This allows slower cutting speeds than are typically used in vitreous cryo-sectioning and contributes to better control during cutting, which facilitates repeatable placement of a ribbon of sections onto a grid. The ribbon is kept under tension during the entire cutting process, which may decrease folding and/or compression, features that are inherent to vitreous sections. Furthermore, the added control afforded by this technique makes it easier for multiple ribbons to be placed on a single grid, thereby increasing the number of sections that can be examined and imaged during a microscopy session. It even allows for serial cryo-electron microscopy. As such, this approach is an advance in the cryo-microtomy of vitreous sections. [source] Carbothermal Synthesis of ,-SiC Micro-RibbonsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2008Gleb N. Yushin We report the synthesis of microscopic ,-SiC ribbons (belts) on the surface of a graphite rod at 1800°,1900°C by a carbothermal process. The width of the ribbons produced ranged from 500 nm to 5 ,m and the aspect ratio was up to 400. The ribbon thickness ranged from 50 to 800 nm. Their growth mechanism was explained by accelerated growth along the twin boundary. SiC whiskers grew on the rod along with the ribbons. Frequently, ribbons were growing from the tip of a whisker or whiskers were growing from the edge of a ribbon. SiC ribbons may find applications in high-temperature sensors, photo-electronic devices, or robust cantilevers in micro (or nano) electro mechanical systems. Alternatively, they can be used as reinforcements in composite materials, conferring anisotropic mechanical properties, such as unidirectional flexibility, to the composite. [source] Segmental dystonia induced by wearing glasses with a ribbon: An unusual case of a reverse sensory geste,MOVEMENT DISORDERS, Issue 8 2004Christian Wider MD Abstract Craniocervical muscles are the most frequently involved in dystonia, which can be either focal of segmental. While often experiencing an increase in dystonia with voluntary motor activity, many patients report temporary relief with geste antagoniste. We describe a patient who presented a peculiar craniocervical segmental dystonia, triggered by putting on glasses with a ribbon. © 2004 Movement Disorder Society [source] The recovery of the shear viscosity of thermally aged bulk and ribbon glassy Pd40Cu30Ni10P20 by rapid quenching from the supercooled liquid statePHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 2-3 2009V. A. Khonik Abstract Isochronal (= linear heating) measurements of the shear viscosity below the glass transition of bulk and ribbon glassy Pd40Cu30Ni10P20 samples differing ,104 -fold in the production quenching rates have been performed. It has been found that heating up into the supercooled liquid region followed by slow cooling leads to a significant structural relaxation-induced viscosity increase upon subsequent testing. This increase, however, is not truly irreversible and the viscosity can be fully recovered (= decreased) by fast quenching from the supercooled liquid state. The effect is nearly independent of whether ribbon or bulk samples are used despite the fact that those latter are notably denser. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enhancement of magnetoimpedance effect in Co-based amorphous ribbon with a meander structurePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2010Lei Chen Abstract A model for the enhanced giant magnetoimpedance (GMI) effect in field-annealed Co-based ribbon with a meander structure is developed. Three different kinds of ribbon are fabricated by a MEMS method and the field dependence of the GMI effect is measured at 10,MHz. Good agreement between theory and experiment shows the validity of this model. A larger change of inductance L in the meander structure results in the increasing of impedance Z and the enhanced GMI effect. [source] The low-energy electronic properties of graphene ribbons in spatially modulated magnetic fieldsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2008J. Y. Wu Abstract The low energy magnetoelectronic structures for a nanographene ribbon under modulated magnetic fields are investigated through the Peierls tight-binding model. They are dominated by the field strength, period, phase, the ribbon width, and edge structure. The modulated magnetic field could add state degeneracy, modify energy dispersions, alter subband spacings, affect carrier-density distributions, create additional band-edge states, and extend the partial flat bands. The main features of energy bands are directly reflected in density of states, such as the position, the height, the structure, and the number of the prominent peaks. These results are compared with a zigzag ribbon under a uniform magnetic field. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Phase structure and crystallization of the bulk glassy FeCoZrWB alloysPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2010Katarzyna Pawlik Abstract In the present work, the high-energy X-ray diffraction (XRD) measurements performed using monochromatic synchrotron radiation of 112 keV (,=0.110696 Ĺ), were utilized to compare a phase constitution of melt-spun ribbon and suction-cast rods of Fe61Co10+xZr5W4,xB20 alloys (where x = 0, 2, 3 at.%). For bulk amorphous samples of the investigated alloys DSC studies allowed to determine the activation energies of crystal growth and differences in crystallization kinetics at constant heating rates. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of post-extrusion parameters on the final morphology of polystyrene/high density polyethylene blendsPOLYMER ENGINEERING & SCIENCE, Issue 10 2003H. Padilla-Lopez The deformation of the dispersed phase in polystyrene/high density polyethylene (PS/HDPE) blends produced by ribbon extrusion was studied numerically and experimentally. A mathematical model for the deformation of the dispersed phase in ribbon extrusion processing of polymer blends was developed assuming uniaxial deformation of the ribbon and the equilibrium shapes of the dispersed particles with a pressure balance over a drop. Simulated morphologies as function of the post-extrusion parameters were obtained and compared with experiments. The analysis of the ribbon extrusion process showed that parameters such as draw ratio (DR) and ribbon-water contact length (X) significantly influence the ribbon dimensions, the extensional stress, and the stretching force. The results also showed that deformation and coalescence of the dispersed phase in the ribbon extrusion processing of polymer blends increase at higher DR and/or lower X values. The comparison between the model and the experimental morphologies of PS/HDPE produced a good agreement. [source] Modeling a linear electric molten zone in a silicon ribbonPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 6 2009Miguel C. Brito 81·10.Fq,crystal growth from melts; zone melting and refining Abstract The linear electric molten zone produced by passing an electric current in a silicon ribbon may be used to create a floating molten zone specially suited for a recrystallization process. A one-dimensional heat transfer numerical model of a linear electric molten zone is developed. Simulation results show the electric current concentration mechanism, and describe the effect of parameters such as the auxiliary radiative input power, or the ribbon thermal conditioning and geometry on the temperature profile and the molten zone width. It is shown that producing a linear molten zone electrically, is about half as energy intensive as if this were done solely by radiative heating. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||