Continuous Wire Research Articles

Preparation of Zr-based Metallic Glass Wire for Biomedical Application

AbstractNew Zr based metallic glass wires without bio-toxic elements of Ni, Al and Be were devel-oped for the further application as biomaterials by arc-melting type melt-extraction method. The continuous metallic glass wires with a good white luster and smooth surface were obtained in Zr-Ti-Al-Co, Zr-Al-Co-Cu, Zr-Al-Co and Zr-Ti-Co alloys. The Zr-based metallic glass wires show high tensile strength reaching 1000MPa. Furthermore, the wires exhibit good bending duc-tility and can be bent through 180 degrees without fracture. The Zr-based metallic glass wires achieve simultaneously high tensile strength, good bending ductility and high thermal stability.

Electromagnetic behaviour of left-handed materials

Using periodic materials composed of split-ring resonators (SRRs) and continuous wires is, up to now, the most common way of obtaining left-handed behaviour in the microwaves regime. In this work, using transmission simulations and measurements, we examine the electromagnetic behaviour of those materials, focusing mainly on their response to an external electric field and its crucial role in the achievement of left-handed behaviour. Moreover, we examine and theoretically demonstrate the possibility of the SRRs&wires design to give left-handed behaviour in the infrared and optical regime, as well as the possibility of obtaining left-handed behaviour using an alternative for the SRRs&wires design composed of pairs of short wires.

Dispersion Characteristics of a Cylindrical Electromagnetic Band Gap Structure

In this letter, a new analytical expression for the dispersion equation of radially periodic structures is derived. The periodic structure is considered as a set of parallel cylindrical frequency selective surfaces, and the dispersion equation is calculated by using a transmission line model. Using this result, the dispersion proprieties of cylindrical electromagnetic bandgap structures composed of continuous or discontinuous metallic wires are presented. It is shown that the band structures of these materials can be determined by using the proposed dispersion equation. Cylindrical periodic materials have potential applications for designing directive antennas, circular high impedance surfaces, or agile antennas

Fabrication by electron beam induced deposition and transmission electron microscopic characterization of sub-10-nm freestanding Pt nanowires

We present a method to reduce the size and improve the crystal quality of freestanding nanowires grown by electron beam induced deposition from a platinum metal organic precursor in a dual beam system. By freestanding horizontal growth and subsequent electron irradiation in a transmission electron microscope, sub-10-nm polycrystalline platinum nanowires have been obtained. A combined transmission electron microscopy–electron energy loss analysis has shown that the amorphous carbon, mixed to nanocrystalline platinum in the as-deposited material, is removed from the wires during irradiation. The same treatment progressively transforms nanocrystals dispersed in the amorphous matrix in a continuous polycrystalline platinum wire.

Negative index materials using simple short wire pairs

Negative refraction is currently achieved by a combination of artificial ``electric atoms'' (metallic wires with negative electrical permittivity $\ensuremath{\epsilon}$) and artificial ``magnetic atoms'' (split-ring resonators with negative magnetic permeability $\ensuremath{\mu}$). Both $\ensuremath{\epsilon}$ and $\ensuremath{\mu}$ must be negative at the same frequency, which is not easy to achieve at higher than THz frequencies. We introduce improved and simplified structures made of periodic arrays of pairs of short metal wires and continuous wires that offer a potentially simpler approach to building negative index materials. Using simulations and microwave experiments, we have investigated the negative index $n$ properties of short wire-pair structures. We have measured experimentally both the transmittance and the reflectance properties and found unambiguously that $nl0$. The same is true for $\ensuremath{\epsilon}$ and $\ensuremath{\mu}$. Our results show that short wire-pair arrays can be used very effectively in producing materials with negative refractive indices.

Au Nano-Wiring on Si Wafer with NaAuCl4-Ethanol Solution

Fabrication processes of Au nanometer wiring circuit was proposed, which is plated on doped Si wafer through resist windows or nano-insulation beds. The resist windows are fabricated with using negative resist by an electron-beam lithography process. After the Au plating, Au wired circuits is realized by oxidizing the resist and the Si substrate. The nano-insulation beds are fabricated by the special processes on the semi-conductive Si wafer, which have flat surface with conductive and insulating area. The Au plating is performed on the conductive area and the plated Au wire is insulated from base substrate by oxidizing Si surface area. Au plating is performed on the negatively biased Si wafer at 9V with using NaAuCl4 dissolved in ethanol at 0.5 mol%. The Au plated area on the Si wafer through resist window showed doted line. However continuous Au wire with 500 nm wide was successfully plated on the Si wafer, which was under coated with 1 nm thick semi-conductive carbon-sulfur-gold (C-S-Au) film.

Fabrication of Self-Aligned Sub-100 nm Iron Wires by Selective Chemical Vapor Deposition

We have demonstrated the ability to fabricate and self-align sub-100 nm iron wires using a combination of silicon nitride spacer technology and selective deposition of iron and tungsten by chemical vapor deposition (CVD). The discovery of selective deposition of CVD iron, from pentacarbonyl [Fe(CO) 5 ] precursor, on silicon nitride surfaces over tungsten surfaces is the key factor that allows the self-alignment of iron wires. The density and conductivity of the CVD iron layers improved as the deposition temperature increased. Deposition time of 1 min was sufficient to deposit a perfectly aligned, continuous iron wire. The deposited iron layer shows 100% selectivity.

Shape Flow Casting and In-rotating-liquid-spinning Processes for the Continuous Production of Wires and of High-strength and Soft Magnetic Metallic Fibres

Computer-controlled facilities for continuous casting of metallic fibres and wires performing in-rotating-liquid-spinning (INROLISP) and shape flow casting (SFC) were designed and installed to determine and control the near-net-shape casting processes over an extended production period. In particular, the flow behaviour of the melt jet was experimentally investigated and theoretically described using fluid dynamic equations. The controlling process parameters, such as the velocity of the melt jet, the stable free flight length, the nozzle geometry and cooling rate, were examined and optimised. Several pure metals as well as microcrystalline and amorphous alloys were cast into continuous fibres and wires of high quality. Microstructural features and mechanical properties of rapidly quenched fibres and thin wires were also evaluated. Of great potential application is the production of amorphous softmagnetic Fe base and Co base thin wires with diameters of about 30 to 50 μm. These microwires are used as sensor cores in highly sensitive novel magnetic field sensors based on a magneto-electric effect.Direct casting of wires with diameters up to 3 mm is carried out using the shape flow casting technique. The SFC facility is an highly instrumented modified meltspin facility, performing rapid substrate quenching. The process principles of the SFC technology, which enable a flexible production of steel, nickel base alloy wires and other novel materials are presented. The microstructural features are correlated with the process parameters.

Technique for Reducing the Power Supply in Reconfigurable Cylindrical Electromagnetic Bandgap Structures

In this letter, a new design of cylindrical electromagnetic bandgap (CEBG) structures is proposed in order to reduce the power supply used to control active elements in EBG-based reconfigurable antennas. The proposed configuration uses structures of discontinuous wires with defects consisting of continuous wires. To examine its performances, numerical simulations were carried out using a finite-difference time-domain (FDTD) code, for the structure without active elements. The obtained results show that the new configuration allows to obtain a directive beam in the pass-band of the all continuous-wires structure. This work has potential application for designing an antenna with a directive pattern able to turn over 360deg range

Fluid Flow, Heat Transfer and Inclusion Motion in a Four‐Strand Billet Continuous Casting Tundish

Inclusions in the steel in a four‐strand continuous casting tundish, billet and wire products are firstly investigated with industrial trials, and the fraction of inclusions removed in terms of total oxygen in the tundish is measured. Then the 3‐dimenional fluid flow, heat transfer and inclusion motion in the tundish are numerically simulated. The κ‐∊ two‐equation model is used to model turbulence. Inclusion motion and trajectories are calculated by considering drag force and buoyancy force, coupling the effect of turbulent fluctuation (Random Walk Model). The effect of strands‐blocking on the fluid flow, heat transfer and inclusion removal is studied. A new design of tundish is proposed focusing on removing more inclusions from the molten steel.

A Computational Study of the Closed and Open States of the Influenza A M2 Proton Channel

In this study, four possible conformations of the His-37 and Trp-41 residues for the closed state of the influenza M2 ion channel were identified by a conformation scan based on a solid-state NMR restraint. In the four conformations, the His-37 residue can be of either the t-160 or t60 rotamer, whereas Trp-41 can be of either the t-105 or t90 rotamer. These conformations were further analyzed by density functional theory calculations and molecular dynamics simulations, and the data indicate that the His-37 residue most likely adopts the t60 rotamer and should be monoprotonated at the δ-nitrogen site, whereas Trp-41 adopts the t90 rotamer. This result is consistent with published experimental data and points to a simple gating mechanism: in the closed state, the His-37 and Trp-41 residues adopt the (t60, t90) conformation, which nearly occludes the pore, preventing nonproton ions from passing through due to the steric and desolvation effects. Moreover, the His-37 tetrad interrupts the otherwise continuous hydrogen-bonding network of the pore water by forcing the water molecules above and below it to adopt opposite orientations, thus adding to the blockage of proton shuttling. The channel can be easily opened by rotating the His-37 χ 2 angle from 60 to 0°. This open structure allows pore water to penetrate the constrictive region and to form a continuous water wire for protons to shuttle through, while being still narrow enough to exclude other ions.

Aligning fast alternating current electroosmotic flow fields and characteristic frequencies with dielectrophoretic traps to achieve rapid bacteria detection

Tailor-designed alternating current electroosmotic (AC-EO) stagnation flows are used to convect bioparticles globally from a bulk solution to localized dielectrophoretic (DEP) traps that are aligned at the flow stagnation points. The multiscale trap, with a typical trapping time of seconds for a dilute 70 microL volume of 10(3) particles per cc sample, is several orders of magnitude faster than conventional DEP traps and earlier AC-EO traps with parallel, castellated, or finger electrodes. A novel serpentine wire capable of sustaining a high voltage, up to 2500 V(RMS), without causing excessive heat dissipation or Faradaic reaction in strong electrolytes is fabricated to produce the strong AC-EO flow with two separated stagnation lines, one aligned with the field minimum and one with the field maximum. The continuous wire design allows a large applied voltage without inducing Faradaic electrode reactions. Particles are trapped within seconds at one of the traps depending on whether they suffer negative or positive DEP. The particles can also be rapidly released from their respective traps by varying the frequency of the applied AC field below particle-distinct cross-over frequencies. Zwitterion addition to the buffer allows further geometric and frequency alignments of the AC-EO and DEP motions. The same device hence allows fast trapping, detection, sorting, and characterization on a sample with realistic conductivity, volume, and bacteria count.

Room temperature gas sensor based on metallic nanowires

Novel and cost effective methods of fabricating nanosturctures is very important in the current state of art of nanotechnology. Arrays of palladium nanowires have been electrodeposited from aqueous plating solution of Pd onto the step edges of highly oriented pyrolytic graphite (HOPG). The structural characterization of the nanowires was performed using atomic force microscope (AFM) and scanning electron microscope (SEM). The deposition of the continuous wires was achieved by optimizing the deposition parameters. The AFM studies revealed that the nanowires were granular in nature and the diameter of the grain was approximately 250 nm in order to form continuous nanowires. SEM images proved that the deposited wires on the substrate formed parallel arrays. The wires were transferred onto non-conducting polymer surfaces in order to study the electrical and the gas sensing properties. Silver contact pads across the nanowires were patterned by thermal evaporation using shadow masking. The electrodes silver contact pads were connected to the macroelectrodes for measuring the electrical characteristics and the sensing properties of the nanowires. The structural changes of the Pd nanowires in the presence of H 2 were carefully monitored using scanning electron microscopy. The sensor response to hydrogen was fast and resembled a switch with two-order magnitude change in the conductance. A sensor mechanism is proposed based on the SEM studies and the sensor response.

Isotropic three-dimensional left-handed metamaterials

We investigate three-dimensional left-handed and related meta-materials based on a fully symmetric multi-gap single-ring SRR design and crossing continuous wires. We demonstrate isotropic transmission properties of a SRR-only meta-material and the corresponding left-handed material which possesses a negative effective index of refraction due to simultaneously negative effective permeability and permittivity. Minor deviations from complete isotropy are due to the finite thickness of the meta-material.

Characterization of transition metal oxide ceramic material for continuous thermocouple and its use as NTC fire wire sensor

The ceramic powder prepared from the mixture of Mn 3O 4 and La 2O 3 have been characterized for NTC behavior and the same have been used as CT 2C (continuous thermocouple) sensor in the form of a thin metal cable to detect over-heating. These materials have mega ohm resistance at room temperature and showed exponential drop in resistance with the rise in temperature over a temperature range of 100–400 °C. It has been observed that as the concentration of La 2O 3 increases from 0 to 10% the NTC behavior drops from (400–260 °C) ±10%. The material was pressed into pellets and sintered at 700 °C for 3 h resulting in good bonding strength. Electrical characterization of the material was done by measuring the resistance over a temperature range of 100–400 °C. The material showed reproducible NTC characteristics over the temperature range 400, 370, 340, 280, and 260 °C with decreasing thermistor constant values ( B = 9588, 9210, 8500, 5170, 3330 K −1) and activation energy (Δ E = 826, 794, 733, 445, 287 meV), respectively. The decrease in activation energy of the ceramic powder with increase in La 2O 3 concentration makes it possible to fabricate thermal sensors which can be used in different temperature ranges. The microstructure was studied using SEM and evidence of a sintered body with grain size around 1 μm was observed in the material. XRD analysis indicated the single-phase tetragonal structure of the ceramic material. The process of using this ceramic material for fabrication of 10 ft continuous fire wire sensor has been explained.

Self-Metallization of Photocatalytic Porphyrin Nanotubes

Porphyrin nanotubes represent a new class of nanostructures for which the molecular building blocks can be altered to control their structural and functional properties. Nanotubes containing tin(IV) porphyrins are photocatalytically active and can reduce metal ions from aqueous solution. The metal is deposited selectively onto tube surfaces, producing novel composite nanostructures that have potential applications as nanodevices. Two examples presented here are nanotubes with a continuous gold wire in the core and a gold ball at the end and nanotubes coated with platinum nanoparticles mainly on their outer surfaces. The latter are capable of photocatalytic reduction of water to hydrogen.

Multi-Composite Wire for High Performance Pulsed Magnets

The multi-composite (MC) wire is a new concept in the pursuit of obtaining the ideal conductor for high performance pulsed magnets. The MC wire consists of a braided, insulating sleeve enclosing a bundle of thin wires: conductor (Cu, CuNb) and reinforcement (e.g., high strength steel), with all free spaces filled by a tight packing of high strength fibers that do not need to be insulating (e.g., carbon fibers). The MC concept is based on the fact that thin wires are inherently stronger. This concept allows winding around a small bore and much flexibility: the composition and geometry of the MC core can be varied even along the length of a continuous wire - to obtain the desired properties of strength and electrical conductivity. Prototype MC wires were made with soft Cu and carbon as core materials, with ultimate tensile strength of 1.2 GPa and 1.7 GPa and conductivity of 38% IACS at 300 K. Several coils were designed and manufactured with similar bore (18 mm) and pulse duration as our standard user coils with internal reinforcement. Although the coil structure was not yet optimized, fields in excess of 50 T were obtained, leaving much room for improvement.

Engineering of Superconductive Ceramics

Recently awarded U.S. patents and proven in the lab, our versatile high temperature superconductor (HTS) ceramic nanotechnology utilizes a novel material formulation of nanosize HTS ceramic powder and of multi-purpose silicone polymer additive. Inexpensive ceramic-silicone processing (CSP) of superconductor wire and other adhesion substrate coated materials, electronics and various bulk materials resulted in electricity throughput of up to 500× copper wire throughput at significantly decreased operating voltage and energy losses. All HTS-CSP materials have the required mechanical properties and durability and can be conveyor manufactured in any size and shape, including continuous flexible multi-strand round wire and electronics.

Experimental study of composite medium with simultaneously negative permeability and permittivity

This paper focuses on a composite medium structure that exhibits simultaneously negative values of effective permeability and permittivity, and our experimental study in an anechoic chamber. The experiment results show that the artificial medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous metallic wires, can have a simultaneously negative effective permeability and permittivity within a frequency region in the microwave regime under certain linearly polarized waves.

A 3D conjugate heat transfer model for continuous wire casting

A three-dimensional (3D) model of heat transfer and equilibrium-solidification for a continuous wire casting process has been established using a commercial fluid dynamics programme, Fluent ®. The melt/solid interface was not tracked explicitly. Instead a liquid fraction value was used for each control volume in the domain. Thermal profiles in the melt and throughout the casting assembly were calculated along with solid fraction profiles and fluid flow velocity vectors. 3D visualisation of the melt behaviour inside the casting channel was possible, thus enabling optimum processing windows to be predicted. Fluid flow visualisation also assists the improvement of casting channel design.