Form Of Ribbons Research Articles

Magnetic moments of Fe and Y in the FeBY glass forming system

The new Fe71.2B24Y4.8 glassy alloy has been prepared in amorphous ribbon form via melt spinning and splat cooling. The high degree of sample homogeneity and structural quality of the ribbon is revealed by the observation of narrow linewidths in the spectra of the field derivatives of the absorbed microwave power in ferromagnetic resonance experiments. Combination of vibrating sample magnetometry and element-specific X-ray magnetic circular dichroism experiments at the L3,2-edges of Y revealed an induced magnetic moment of 0.065μB/atom for Y antiparallel oriented to an Fe magnetic moment of 1.83μB/atom.

Effect of Inoculation of Pectinolytic Mixed Bacterial Culture on Improvement of Ribbon Retting of Jute and Kenaf

Jute and kenaf are among the annually renewable fibre crops mainly grown over tropical and subtropical Asian countries. They are possibly the world's largest source of lignocellulosic bast fibre which is extracted from plants by a natural microbial process known as retting. But acute shortage of water for retting and the environmental pollution created from conventional system of retting has demanded for new method of retting. The new method of retting launched has been recognized as ribbon retting. In ribbon retting barks are removed from jute and kenaf plants mechanically or manually in the form of ribbon. The ribbons are coiled and then allowed for retting in water with or without using a microbial inoculum. Ribbon retting has the following advantages over conventional retting: (1) It requires lesser volume of water, (2) it is faster, (3) it produces lesser environmental pollution, and (4) it produces improved quality fibre. Addition of efficient pectinolytic microbial inoculum may further boost up or improve the ribbon retting process. From the present study it is understood that inoculation of a specific mixed bacterial culture in combination with 0.5% urea as N-supplement caused faster ribbon retting of jute and kenaf. Ribbon retting conducted in cement retting tank was faster than that in polythene tank. The mixed bacterial culture in combination with urea produced stronger, finer and brighter coloured jute and kenaf fibre in comparison to uninoculated control. One hundred twenty-day-old plant was found most suitable for ribbon retting. Ribbon retted fibre with pectinolytic mixed bacterial culture in combination with urea obtained higher grade in comparison to uninoculated control. Such ribbon retted fibres produced standard and regular quality yarn.

Microstructure and low field magnetic properties of bulk Fe61Co10Hf2.5Zr2.5Ti2W2B20 amorphous and partially crystallized alloy

The microstructure, initial magnetic susceptibility and its disaccommodation of the amorphous and partially crystallized Fe61Co10Hf2.5Zr2.5Ti2W2B20 alloy are investigated. From Mössbauer spectroscopy, X-ray diffraction and electron microscopy studies we have found that the samples in the as-quenched state are fully amorphous. Moreover, we have stated that in the annealed samples the crystalline α-FeCo phase shows the long range order of atoms. The amorphous rod exhibits the lower intensity of disaccommodation than the sample in the form of ribbon. It is due to annealing out of some free volumes during preparation.

Structure of cholesterol helical ribbons and self-assembling biological springs.

We report the results of x-ray-scattering studies of individual helical ribbons formed in multicomponent solutions of cholesterol solubilized by various surfactants. The solutions were chemically defined lipid concentrate (CDLC) and model bile. In these and many analogous multicomponent surfactant-cholesterol solutions, helical ribbons of two well defined pitch angles, namely 11 degrees and 54 degrees, are formed. We have suggested previously that this remarkable stability results from an underlying crystalline structure of the sterol ribbon strips. Using a synchrotron x-ray source, we have indeed observed Bragg reflections from individual ribbons having 11 degrees pitch angle. We have been able to deduce the parameters of the unit cell. The crystal structure of these ribbons is similar to that of cholesterol monohydrate, with the important difference that the length of the unit cell perpendicular to the cholesterol layers is tripled. We discuss possible origins for this triplication as well as the connection between the crystalline structure and the geometrical form of the helical ribbons.

The Crystallization of (NiCu)ZrTiAlSi Glass/Crystalline Composite

Alloys of composition (Ni1–xCux)60Zr18Ti13A15Si4 were investigated in the form of ribbons and massive samples. The microstructure of the massive samples consists of dendritic crystals in the amorphous or nanocrystalline matrix. The amount of the amorphous phase is the lowest in the sample with the highest Cu content. The segregation in the liquid phase, leading to the local differences in density and the composition of the crystallizing dendrites in the samples crystallized in the copper mould was shown. The typical compositions of the multi-component crystals could be distinguished; one with the increased content of aluminum, the second with the high content of silicon and third, with the high content of (NiCu) and (ZrTi). The cubic phase Ni(Cu)Ti(Zr) with Cu and Zr dissolved could be identified.

Analysis of SMA Hybrid Composite Structures in MSC.Nastran and ABAQUS

A thermoelastic constitutive model for shape memory alloy (SMA) actuators embedded in a composite structure, termed an SMA hybrid composite (SMAHC), was recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model can be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature-dependent material properties. The model is also relatively easy to use, and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by a discussion of implementation and usage in commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types: a beam clamped at each end and a cantilever beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilever beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from commercial codes are compared with those from a research code as validation of commercial implementations; excellent correlation is achieved in all the cases.

Surface morphology in amorphous Fe–Mo–Cu–B ribbon system

Ribbons of (Fe–Co) 79Mo 8Cu 1B 12 with Co/Fe ratio of 0, 1/12, 1/9 and 1/3 were prepared in amorphous state in form of ribbons ∼20 μm thick and 6 mm wide by planar flow casting method. The as-quenched state of the samples was checked by X-ray diffraction. Sample surfaces were analyzed using confocal microscopy. The effect of variation of Co/Fe ratio and temperature of the master alloy melt was investigated with respect to the values of micro-roughness. Samples were also investigated for surface texture of eventual quenched-in crystalline phases by X-ray diffraction; the presence of texture was observed in certain cases, disappearing with increasing Co-content.

Soft magnetic properties of a high temperature CoFeSiBNb nanocrystalline alloy

We have investigated the magnetic properties of a Co 36 Fe 36 Si 4 B 20 Nb 4 alloy developed for high temperature soft magnetic applications. Studies of the crystallization of the alloy, prepared in the form of amorphous ribbons by melt-spinning, were performed using differential scanning calorimetry and X-ray diffraction. These studies, and further validation by transmission electron microscopy, suggested the formation of ( CoFe ) 2 Si nanoparticles dispersed in an amorphous matrix during the first stage of crystallization which occurred at around 845 K. The formation of this nanocrystalline state by annealing at temperatures between 825 and 875 K not only raised the Curie temperature of the material to above 1000 K but also gave superior soft magnetic properties with a coercivity less than 50 A/m (625 mOe). However, at higher annealing temperatures, formation of strongly anisotropic phases with out of plane domain magnetization, observed by magnetic force microscopy, resulted in deterioration of the soft magnetic properties.

A potential Co36Fe36Si4B20Nb4 nanocrystalline alloy for high temperature soft magnetic applications

The paper addresses the structural, crystallization, soft magnetic and Curie temperature behaviour of Co36Fe36Si4B20Nb4 alloy. The material, prepared in the form of ribbons by melt-spinning technique, was amorphous in the as-cast state. Differential scanning calorimetry (DSC) showed two stages of crystallization whereas thermal variation of electrical resistivity (TER) carried out to a higher range of temperature indicated three stages of crystallization. The first crystallization stage, which occurred at 845 K and 825 K in DSC and TER, respectively, was due to the formation of nanophase (CoFe)2Si as evidenced by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The formation of these nanoparticles reduced the magnetocrystalline anisotropy, thereby revealing good soft magnetic properties in the samples annealed between 825 K and 875 K with coercivity less than 49.9 A m−1 (627 mOe) and susceptibility ∼ 0.72 × 103. In this optimum nanocrystalline state, the material also exhibited a high Curie temperature above 1100 K, opening the scope of the present nanocrystalline alloy for high temperature applications.

Protein Folding Determinants: Structural Features Determining Alternative Disulfide Pairing in α- and χ/λ-Conotoxins,

Alpha-conotoxins isolated from Conus venoms contain 11-19 residues and preferentially fold into the globular conformation that possesses a specific disulfide pairing pattern (C1-3, C2-4). We and others isolated a new family of chi-conotoxins (also called lambda conotoxins) with the conserved cysteine framework of alpha-conotoxins but with alternative disulfide pairing (C1-4, C2-3) resulting in the ribbon conformation. In both families, disulfide pairing and hence folding are important for their biological potency. By comparing the structural differences, we identified potential structural determinants responsible for the folding tendencies of these conotoxins. We examined the role of conserved proline in the first intercysteine loop and the conserved C-terminal amide on folding patterns of synthetic analogues of ImI conotoxin by comparing the isoforms with the regiospecifically synthesized conformers. Deamidation at the C-terminus and substitution of proline in the first intercysteine loop switch the folding pattern from the globular form of alpha-conotoxins to the ribbon form of chi/lambda-conotoxins. The findings are corroborated by reciprocal folding of CMrVIA chi/lambda-conotoxins. Substitution of Lys-6 from the first intercysteine loop of CMrVIA conotoxin with proline, as well as the inclusion of an amidated C-terminal shifted the folding preference of CMrVIA conotoxin from its native ribbon conformation toward the globular conformation. Binding assays of ImI conotoxin analogues with Aplysia and Bulinus acetylcholine binding protein indicate that both these substitutions and their consequent conformational change substantially impact the binding affinity of ImI conotoxin. These results strongly indicate that the first intercysteine loop proline and C-terminal amidation act as conformational switches in alpha- and chi/lambda-conotoxins.

Effects of plastic deformation and hydrogen charging on the internal friction in bulk and ribbon metallic glasses Zr52.5Cu17.9Ni14.6Al10Ti5 and Pd40Cu30Ni10P20

Two different types of metallic glasses, a metal-metal-based and a metal-metalloid-based one, in both bulk and ribbon form (i.e., produced with very different quenching rates) are compared with respect to their structural relaxation behavior during continuous heating (2 K/min) in a vibrating-reed set-up (frequencies 0.2–5 kHz). The variation of damping as a function of temperature, time, and strain amplitude is shown as a measure of the content of structural relaxation centers, whose nature is studied by means of artificially introduced irregularities into the amorphous structure (i.e., by cold rolling and by hydrogen charging). The results indicate that the hydrogen damping peak, which is only observed in the Zr-based glass, is more probably due to hydrogen reorientation jumps than due to reorientation of hydrogen-related, dislocation-like distortion fields although the latter cannot be ruled out. A pronounced deformation damping peak could not be found in contrast to earlier results in the literature, probably owing to the selected degrees of deformation.

Synthesis and magnetic properties of Sm 3(Fe, Ti) 29 compound

Sm 3Fe 27.5Ti 1.5 alloy produced in the form of ribbon by the melt-spinning technique consisted of the Sm(Fe, Ti) 7 phase. Annealing of the Sm 3Fe 27.5Ti 1.5 melt-spun ribbon at high temperatures resulted in the formation of the Sm 3(Fe, Ti) 29 phase. The Sm–Fe–Ti melt-spun ribbon with the Sm 3(Fe, Ti) 29 phase exhibited a maximum coercivity of 240 kA m −1, exceeding that of the ribbon with the Sm(Fe, Ti) 7 phase.

Nitrogen doping and multiplicity of stacking faults in SiC

This paper reports on the strong enhancement of stacking fault (SF) formation in 4H–SiC by heavy nitrogen doping. The paper consists of two separate observations. The first part reports on localized but severe deformation bands observed in certain regions of 4H–SiC wafers that had undergone high temperature processing during device fabrication. Using a combination of dynamic secondary ion mass spectroscopy (SIMS) and conventional, weak-beam (WB) and high-resolution (HR) transmission electron microscopy (TEM), the affected regions of the wafers were found to have a much higher concentration of nitrogen and to contain a high density of stacking faults. In contrast, in the non-affected regions of the wafers, the nitrogen concentration was lower and no lattice defects could be observed by TEM, indicating that the severely deformed morphology of the affected regions was due to the high stacking fault content. Moreover, the stacking faults in the affected regions were found to be invariably double and not single-layered, formed by the glide of two leading partial dislocations on adjacent (0001) planes. The second part of the paper reports on the occurrence of stacking faults during deformation tests on heavily nitrogen-doped 4H–SiC. Combining optical microscopy, HR and weak-beam (WB) TEM, the generated faults were found to be double-layered as well. It is interesting that in neither type of experiment, trailing partials were observed: it appears that the SFs were not in the form of ribbons bound by leading and trailing partials but rather in the form of faulted loops on two adjacent planes, each loop bound by a leading Shockley partial of the same Burgers vector. The results of the two observations are explained by the stabilization of double-layer stacking faults (DSFs) when the Fermi level of the faulted crystal is pushed up by nitrogen doping to above the stacking fault energy level.

Preparation and mechanical properties of dispersed-ZrN glassy composite alloys containing pores

Glassy composite alloys containing dispersed ZrN particles and pores were successfully prepared for the first time by a powder compact melting and liquid quenching process using Zr–Al–Ni–Cu glassy alloy and AlN powders as the starting materials. The alloys were produced both in ribbon and rod forms by means of conventional single-roll spinning and casting techniques. The ZrN particles were of approximately micrometer sizes and synthesized by an AlN decomposition reaction. It was found that they had a regular morphology and high crystallinity, suggesting single crystals. The pores were spherical with a diameter of ∼10 μm and a porosity of about 2%. The rod alloys had a compressive fracture strength of about 2 GPa which is higher than that of the matrix of the Zr–Al–Ni–Cu glassy alloy.

Magnetic properties of Fe-based bulk ferromagnetic glasses

Several Fe-based ferromagnetic bulk amorphous alloys, having compositions Fe 61Co 10Zr 5W 4B 20; Fe 61Co 10Zr 5W 2Nb 2B 20; Fe 61Co 10Zr 2.5Hf 2.5W 2Nb 2B 20, have been prepared by suction casting, in the form of 1 mm diameter rods, and by melt spinning in the form of thick ribbons (thickness ∼200 μm). All these glasses have a large supercooled region T x – T g, ranging from 51 to 70 K, consistent with a large glass forming ability, that is promoted by the substantial differences in the atomic sizes of the constituent elements. We have obtained a saturation polarisation (μ 0M S) of ∼0.8 T for Fe 61Co 10Zr 5W 4B 20 and 0.9 T for Fe 61Co 10Zr 5W 2Nb 2B 20 and Fe 61Co 10Zr 2.5Hf 2.5W 2Nb 2B 20, for both rod and ribbon forms. The coercivities of the samples range from 25 to 50 A/m, for ribbon and from 100 to 300 A/m for rods, when measured at 5 Hz. The coercivity is a parameter that is very sensitive to magnetic inhomogeneity and the data indicate some degree of such inhomogeneity in the samples, especially for the rods. Magnetoelastic resonance experiments were also performed, giving values of Young modulus of about 160 GPa, and magnetostriction coefficients of about 10 −5.

Soft magnetic powder-core composites of Fe90Zr7B3 and Fe49Co21Al5Ga2P9.65C5.75B4.6Si3 alloys

Amorphous and nanocrystalline alloys in ribbon form exhibit excellent soft magnetic properties, but their forms are limited to tape wound cores. Complex shapes require the implementation of a powder metallurgical approach resulting in reduced permeabilities. The present study investigates Fe-based Fe90Zr7B3 (C1) and Fe49Co21Al5Ga2P9.65C5.75B4.6Si3 (C2) melt-spun ribbons as precursors for compacted powder cores. Single-roller melt spinning of C1 produced partially crystallized structures while C2 resulted in amorphous ribbons. Annealing studies were carried out based on the crystallization temperatures of various phases extracted from M(T) measurements. In ribbon form and under optimum annealing conditions, C1 revealed a 1.88T saturation flux density (Bs) and 44A∕m coercivity (Hc), while C2 exhibited a Bs of 0.78T and Hc of 2.4A∕m.

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BioTechniquesVol. 40, No. 2 WebWatchOpen AccessWebWatchKevin AhernKevin AhernSearch for more papers by this authorPublished Online:21 May 2018https://doi.org/10.2144/06402WW01AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail The Vision ThingYou may not realize it, but macular degeneration is the leading cause of blindness in people over the age of 55. That's a scary thought for a rapidly aging group of baby boomers. The Foundation Fighting Blindness is a charitable organization aimed at preventing, treating, and curing a broad spectrum of retinal diseases, including macular degeneration, retinitis pigmentosa (degeneration of photoreceptor cells), Stargardt disease (juvenile macular degeneration), and Usher syndrome (hearing impairment at birth followed by retinitis pigmentosa). The site abounds with educational content about each of these diseases, as well as clinical trial summaries, and descriptions of experimental therapies. A site with a mission to inform and serve.www.blindness.orgOrientation ExpressLook in the Protein Data Bank (PDB) and you'll find thousands of structures of proteins embedded in or associated with the cell's phospholipid bilayer. Search for information about how these proteins are oriented in the membrane, and you'll draw a blank. That didn't sit well with Andrei Lomize and coworkers, so they developed a computational approach to optimize the spatial arrangement of proteins in membranes and then applied it to all known transmembrane complexes in PDB. Abracadabra! Thus was the Orientations of Proteins in Membranes (OPM) database born. At the OPM site, you'll discover 162 proteins from over 60 species grouped according to type, class, family, superfamily, and localization site. Click on a desired protein, and you can view it in ribbon form or in 3-D relative to the membrane it resides in.opm.phar.umich.eduSearching SmartsTalk to Tom Sharpton, cofounder of the interesting Siphs site, and you'll discover a young scientist bursting with enthusiasm. It's no surprise that these qualities carry over entirely into the design of his web site. With a dogged determination to put scientists together to share important information, Siphs’ philosophy is rooted in sharing the expertise of its users. Towards this end, newcomers identify their areas of expertise on registration, and questions are posted to these areas. Siphs’ users answer each other's questions using a bulletin board style of format along with the assistance of a search engine. Bringing together a community of scholars in this way is a brilliant idea—who better knows the ins and outs of a problem than one working on it?www.siphs.com/ate/index.jspAnimal SentinelsFor detecting lethal, odorless gases like carbon monoxide in mines, a canary was a miner's best friend because if it died or got sick, it was time to make serious plans for exit. Besides canaries, other organisms also provide important information relating to human health. The Canary Database, currently in beta testing at Yale, is a great place to learn more about, for example, birds as an early warning system for an avian flu epidemic. From information on an animal's exposure to reagents to linkages between human and animal health outcomes, the Canary Database is chock full of data from over 1600 curated, peer-reviewed articles that will be welcomed by environmental health specialists.canarydatabase.orgGenome Du JourCan it possibly be 10 years since the complete sequence of the first organismal genome, that of Haemophilus influenzae, was determined? Since that momentous event, over 330 genomes have been completed and published, representing a new genome about every 11 days. One of the more interesting genomic projects currently underway (of approximately 1700 in progress) is the Salamander Genome Project, hosted at the University of Kentucky. Salamanders are model vertebrate organisms for vision, renal function, embryogenesis and, perhaps most interestingly, tissue/limb regeneration. At the site, visitors can follow the progress of this project, check out the expressed sequence tag (EST) database, access linkage map information, and much more. If one day we learn to regenerate human organs, it may come as a result of information from the salamander.salamander.uky.eduFiguresReferencesRelatedDetails Vol. 40, No. 2 Follow us on social media for the latest updates Metrics Downloaded 137 times History Published online 21 May 2018 Published in print February 2006 Information© 2006 Author(s)PDF download

Effects of Additional Hf on the Thermal Stability and Mechanical Properties of Cu-Zr-Ag Bulk Glassy Alloys

The thermal stability, crystallization behavior and mechanical properties of the Cu45Zr45� xHfxAg10 (x ¼ 0 to 45 at%) glassy alloys have been investigated. The glass transition temperature (Tg), crystallization temperature (Tx), liquidus temperature (Tl) and the supercooled liquid regionTx (¼ TxTg) increase with increasing Hf content. The reduced glass transition temperature (Tg=Tl) values are in the range from 0.54 to 0.59. The Vicker's hardness (HV ), Young's modulus (E) and compressive fracture strength (� c,f) of the Cu45Zr45� xHfxAg10 (x ¼ 0 to 25 at%) bulk glassy alloys increase linearly with increasing Hf content and reach the maximum values of 554, 123 GPa and 2020 MPa, respectively, for Cu45Zr20Hf25Ag10 alloy. A different crystallization behavior is observed for Cu45Zr45Ag10 and Cu45Hf45Ag10 glassy alloys. (doi:10.2320/matertrans.47.1922) the thermal stability and mechanical properties of Cu-based Cu-Zr-Ag bulk glassy alloys. This paper presents the thermal stability, density and mechanical properties of the Cu-Zr-Hf- Ag glassy alloys. The effectiveness of substitution of Hf for Zr is also investigated. 2. Experimental Procedure Multi-component Cu-(Zr, Hf)-Ag alloy ingots with nom- inal compositions were prepared from the mixtures of pure Cu, Zr, Hf and Ag metals by arc melting in a Ti-gettered argon atmosphere. The purity of metals was over 99.9 mass%. Alloy ingots were re-melted four times to ensure chemical homogeneity. The glassy alloys in a ribbon form with a cross section of 0:02 � 1:5 mm 2 and in a cylindrical rod form with diameters up to 2.0 mm were prepared by melt spinning and copper mold casting, respectively. The glassy structure was identified by X-ray diffraction and the thermal stability associated with glass transition temperature (Tg) and crystallization temperature (Tx) was examined by differential scanning calorimetry (DSC) at a heating rate of 0.67 K/s. The liquidus temperature (Tl) was measured by differential thermal analyzer (DTA) at a heating rate of 0.33 K/s. The density was measured by Archimedes's principle by weigh- ing ingots in tetrabromoethane and in air. Vicker's hardness was measured using a microhardness tester. Mechanical properties were measured under a compressive load with an Instron testing machine. The gauge dimension of specimens was 2.0 mm in diameter and 4.0 mm in height and the strain rate was 5 � 10 � 4 s � 1 .

Antistatic thermoplastic blend of polyaniline and polystyrene prepared in a double-screw extruder

One of the major aims of research on intrinsically conducting polymers (ICP) is the production of blends combining the processing properties of thermoplastic polymers with the conductivity of conducting polymers. The main problem in applying ICP on a large scale in the plastic industry is the impossibility of plasticizing these polymers under heat and shear. However, the use of functionalized acids improves the thermal stability and processability of conductive polymers. In this work the doping process was carried out during processing, also denoted as “reactive processing”. This procedure reduces the number of steps to obtain the final product, PS/SBS/PAni. Blending of polystyrene with dodecylbenzenosulfonic acid doped polyaniline was carried in a double-screw extruder using the block copolymer of styrene and butadiene, SBS, as compatibilizer. A conductive thermoplastic ( σ = 10 −6–10 −2 S cm −1) was obtained in the form of ribbons, which were used to evaluate the thermal, mechanical, morphological and electrical properties. We used SBS as compatibilizer and different formulations were tested according to a statistical response surface method. The mechanical and electrical properties of these thermoplastic blends are adequate for antistatic applications.

Mechanical Behavior of Nanostructured Aluminum Alloys Containing Quasicrystalline Phase

Aluminum-based alloys containing quasicrystalline particles of 50 – 600 nm in diameter as a reinforcing phase were produced in the form of powder or ribbons by water atomization or melt spinning techniques, respectively. Rods were compacted from powders and some ribbons by severe plastic deformation without sintering. Structure and mechanical behavior of alloys are discussed.