Wires Length Research Articles

Design and kinematics of a tube-shaped multidirectional bending robotic device using slackened SMA wires for transurethral ureterolithotripsy.

The complex and elaborate structure of the urinary system presents surgeons with difficulty in using a ureteroscope with a fixed optical fiber to reach the targeted calculus. To address this challenge, a robotic device is required to control the direction of laser irradiation position independently in ureteroscopes. A continuum robotic device was designed and fabricated. The device is constructed with three slackened shape memory alloy (SMA) wires to control the laser irradiation position of the optical fiber combined with the view of the camera on the tip of the ureteroscope. Kinematics analysis and experimental evaluation reveal the capability of the device. The structure of the device is the same as a single-joint continuum robot. This device is unique because of the tiny diameter of 1.1mm which can be used inside the ureteroscope through a Ø1.2mm inner channel into the kidney for transurethral ureterolithotripsy. Kinematic analysis revealed the relationship among space coordinates, angles of bending, and direction and SMA wires length. The maximum bending angle was around 25° when the current value was 350mA on a single SMA wire. The device could achieve multi-directional bending by allocating the values of current on SMA wires, separately. This device offers a major advancement in small size and dexterity in medical robotics. Combined with a proper control system, this device could simplify the operation and improve the efficiency of the transurethral ureterolithotripsy.

Tailoring Magneto-Static Interactions Through Interwire Separation and Morphology in Planar Nanowire Arrays of Co

Abstract We study the influence of magnetostatic interactions occurring due to interwire separation and nanowire (NW) morphology on the magnetic properties of planar nanowire arrays of Co. The Co nanowire arrays were grown on step-bunched Si (111) templates grown using atomic terrace low-angle shadowing (ATLAS) method. We find that the magnetic anisotropy is dominated by the shape anisotropy, which keeps the easy axis in-plane and along the wires length. The coercivity and remanence magnetization increase significantly with increased interwire separation. Morphology is found to have a strong influence on the effective magnetic anisotropy leading to an easy axis behaviour across the wire length (step-edges) for a sample grown at elevated temperature.

Development and Validation of a Method for Measurement of Root Length in 2D Images

The plant root system analysis using traditional methods is complex, time-consuming, and in most cases does not provide the required accuracy. Therefore, new methods using digital image processing has been proposed. This paper presents a new algorithm for estimate the length of washed roots using digital image processing. First the algorithm loaded the image and extracted its resolution. Then the image was converted to grayscale and binarized. The objects from binary image were detected using its contours. The binary image was also used to thin the objects. After that the length was estimated based on resulting skeletons from previous procedure. The proposed algorithm was validated using copper wires. The copper wires length were measured using a caliper, and compared to estimated length by proposed algorithm and a method from literature, with different angles of inclination. When comparing estimated lengths from proposed algorithm and literature method, the proposed algorithm got the best results in 67,03% of test cases. Since plant roots are normally randomly arranged in the images, it is the greatest importance to develop a method of measuring root length that is invariant or has low sensitivity to rotation, and which is still precise and accurate.

Applicability of superelastic materials in seismic protection systems: a parametric study of performance in isolation of structures

The dynamic response to different seismic inputs of an isolated structure disposed on a sliding layer and connected to the ground with a superelastic NiTi device was analyzed. The device allows wires of NiTi to be mechanically cycled by supporting externally applied tension/compression forces exploiting both dissipative and self-centering capabilities associated with superelasticity. Simulations were carried out modifying the wires length and the structural mass. Both parameters were varied over two orders of magnitude with the aim of evaluating the type of response, the mitigation level that can be accomplished and the combination of parameters resulting in an optimal response. Results indicate that the proposed device is suitable for seismic protection of isolated structures and it is demonstrated that the protective action is more related with the restraining and self-centering properties of the NiTi superelastic wires than with its damping capacity.

Research regarding the influence of driving-wires length change on positioning precision of a robotic arm

The paper emphasise positioning precision of an elephant's trunk robotic arm which has joints driven by wires with variable length while operating The considered 5 degrees of freedom robotic arm has a particular structure of joint that makes possible inner actuation with wire-driven mechanism. We analyse solely the length change of wires as a consequence due inner winding and unwinding on joints for certain values of rotational angles. Variations in wires length entail joint angular displacements. We analyse positioning precision by taking into consideration equations from inverse kinematics of the elephant's trunk robotic arm. The angular displacements of joints are considered into computational method after partial derivation of positioning equations. We obtain variations of wires length at about tenths of micrometers. These variations employ angular displacements which are about minutes of sexagesimal degree and, thus, define positioning precision of elephant's trunk robotic arms. The analytical method is used for determining aftermath design structure of an elephant's trunk robotic arm with inner actuation through wires on positioning precision. Thus, designers could take suitable decisions on accuracy specifications limits of the robotic arm.

Drug diffusion, integration, and stability of nanoengineered drug-releasing implants in bone ex-vivo.

To treat skeletal conditions such as bone infections, osteoporotic fractures, and osteosarcoma, it would be ideal to introduce drugs directly to the affected site. Localized drug delivery from the bone implants is a promising alternative to systemic drug administration. In this study we investigated electrochemically nanoengineered Ti wire implants with titania nanotubes (TNTs), as minimally invasive drug-releasing implants for the delivery of drugs directly into the bone tissue. Since trabecular bone in vivo contains a highly interconnected bone marrow, we sought to determine the influence of marrow on drug release and diffusion. Electrochemical anodization of Ti wires (length 10 mm) was performed to create an oxide layer with TNTs on the surface, followed by loading with a fluorescent model drug, Rhodamine B (RhB). Cores of bovine trabecular bone were generated from the sternum of a young steer, and were processed to have an intact bone marrow, or the marrow was removed. RhB-loaded TNTs/Ti wires were inserted into the bone cores, which were then cultured ex vivo using the ZetOS™ bioreactor system to maintain bone viability. Release and diffusion of RhB inside the bone was monitored using fluorescence imaging and different patterns of drug transport in the presence or absence of marrow were observed. Scanning electron microscopy of the implants after retrieval from bone cores confirmed survival of the TNTs structures. Histological investigation showed the presence of bone cells adherent on the implants. This study shows a potential of Ti drug-releasing implants based on TNTs technology towards localized bone therapy. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 714-725, 2016.

Various Methods for Synthesis of Bulk and Nano Thallium(III) Oxide

Thallium(III) oxide, a degenerate n-type semiconductor, is a highly insoluble thermally stable thallium source suitable for glass, optic and ceramic applications. Although thallium oxide is an important metal oxide, its synthesis has only been sporadically studied. This review gives an overview of all reported synthetic routes for the preparation of both bulk and nanostructured thallium(III) oxide. These methods include electrochemical methods, thermal method, chemical vapor deposition (CVD), microwave irradiation, sol–gel method and one recently chemical route using potassium superoxide. In electrochemical methods, both bulk and nanostructures of thallium(III) oxide can be prepared and the amount of the deposited material, thickness of the layer or wires length depends on the deposition time matrix structure. Thermal methods are simple and effective techniques which include thermal decomposition and calcination of various precursors. By CVD and microwave irradiation we be able to synthesis bulk and nanostructures of thallium(III) oxide, respectively. A one-step, room temperature, solution synthesis of thallium(III) oxide nanoparticles with a size of about 10 nm is reported by using potassium superoxide.

Magnetic domain wall motion in notch patterned permalloy nanowire devices

We report a study of magnetization reversal process of notch-patterned permalloy (Py) nanowires (NWs) by using an in-situ magnetic force microscopy (MFM). Three neighboring straight NWs and an individual straight NW with discs connected to the wires ends are fabricated by standard electron beam lithography through a lift-off technique. MFM images are taken in the presence of an in-plane magnetic field applied along the wires length. As a result, the nucleation, pinning and depinning of domain walls (DWs) along the NW are observed. The artificial constraints (notch) in such symmetrical geometry of NWs indeed serve as pinning sites to pin the DWs. The nature of magnetization reversal, pinning field and depinning field for the DWs that are observed in these permalloy NWs, indicate the key roles of notch depth, the terminal connection structure of NW end and the inter-wire interaction among the NWs. The in-situ MFM measurements are examined with the micromagnetic simulations. Consequently, good agreements are obtained for the DW structures and the effect of DWs pining/depinning, however a dissimilarity in experimental and simulation observations for the direction of propagation of DWs in NWs needs further investigation.

Cooperative microwave-assisted magnetization reversal with pulsed fields in 2-µm-wide nickel–iron wires at nanosecond time scales

The switching dynamics of nickel–iron wires (length, 100 µm; width, 2 µm) were investigated by magnetization reversal under a combined 20-ns-wide microwave impulse and a 2-ns-wide pulsed field. The switching field was clearly reduced by cooperative switching and was independent of the pulsed field width (for widths between 2 and 10 ns). This result suggests that magnetization assisted by the combined microwave field occurs within 2 ns.

Conductance of Well-Defined Porphyrin Self-Assembled Molecular Wires up to 14 nm in Length

We show that molecular wires up to 14 nm in length composed by zinc-porphyrins bridged by bipyridines stand efficient electrical transport. Self-assembled molecular wires were prepared step-by-step, alternating up to 13 units of zinc-octaethylporphyrin with axially coordinated 4,4′-bipyridine, on highly oriented pyrolytic graphite (HOPG). A combination of molecular resolution imaging and scanning tunneling spectroscopy allowed us to follow molecules self-assembly in real time during wire fabrication and to measure wires current, respectively. A statistical analysis of hundreds of current–voltage curves was carried out to determine the conductance of individual porphyrin/bipyridine wires. From the conductance dependence on the wires length an ultra low attenuation factor (β = 0.015 ± 0.006 A–1) was obtained for shorter wires, with a transition in conduction regime occurring at ca. 6.5 nm long wires.

Advanced MgB2 wire made by internal magnesium diffusion process

Single- and four-core MgB2 wires have been manufactured by internal magnesium diffusion (IMD) into boron. Longitudinal uniformity of the composite wires has been checked by X-ray micro-tomography measuring the MgB2 cross section area along the wires length. High density of MgB2 was evaluated by micro-hardness measurements. It was found that the filament’s density has a direct effect on the critical current density (Jc). The highest Jc was measured for the wire having the boron core densified by cold isostatic pressing with 1.9GPa applied prior to final heat treatment. Presented results showed that high current density can be reached in MgB2 wires obtained by IMD, which are very interesting for the future practical applications of MgB2 superconductors.

Structural investigation of silicon nanowires with grazing incidence small angle X-ray scattering

Presented is a structural investigation of silicon nanowires, which is conducted with grazing incidence small angle X-ray scattering. The morphology of the wires is analysed following experimental measurements. Three diameters (50, 100 and 200 nm) are investigated in relation to the aspect ratio of the wires (length 25 µm). Periodic fringes because of the weak distribution of the diameter are observed on the experimental images. The asymptotic behaviour of the scattering signal along the qy direction is also analysed and presented.

Magnetic characterization of FeCo nanowire arrays by first-order reversal curves

FeCo nanowire arrays have been obtained by current pulse electrodeposition into nanoporous alumina templates. First-order reversal curve (FORC) diagrams have been used to investigate magnetostatic interaction and average coercivity of individual FeCo nanowires embedded in porous alumina templates. The FeCo nanowires with a wires length up to 3 μm and wires diameter ranging from 25 to 50 nm showed interacting single-domain behavior. Using FORC diagrams, the spread of coercivity distribution was seen to be almost independent of the wires diameter, but with increase in diameter the inter-wire magnetostatic interaction was increased. It was found that for arrays with higher diameter, the coercivity of the arrays is lower than the average coercivity of the individual wires. It was detected that an increase in wire diameter results in a considerable increase in the spread of the distribution in the Hu direction of FORC distribution. Curve fitting on the experimental data proved a relatively linear relation between interaction field and square diameter of the nanowires.

Shape matters: effects of silver nanospheres and wires on human alveolar epithelial cells

BackgroundIn nanotoxicology, the exact role of particle shape, in relation to the composition, on the capacity to induce toxicity is largely unknown. We investigated the toxic and immunotoxic effects of silver wires (length: 1.5 - 25 μm; diameter 100 - 160 nm), spherical silver nanoparticles (30 nm) and silver microparticles (<45 μm) on alveolar epithelial cells (A549).MethodsWires and nanoparticles were synthesized by wet-chemistry methods and extensively characterized. Cell viability and cytotoxicity were assessed and potential immunotoxic effects were investigated. To compare the effects on an activated and a resting immune system, cells were stimulated with rhTNF-α or left untreated. Changes in intracellular free calcium levels were determined using calcium imaging. Finally, ion release from the particles was assessed by ICP-MS and the effects of released ions on cell viability and cytotoxicity were tested.ResultsNo effects were observed for the spherical particles, whereas the silver wires significantly reduced cell viability and increased LDH release from A549 cells. Cytokine promoter induction and NF-κB activation decreased in a concentration dependent manner similar to the decrease seen in cell viability. In addition, a strong increase of intracellular calcium levels within minutes after addition of wires was observed. This toxicity was not due to free silver ions, since the samples with the highest ion release did not induce toxicity and ion release control experiments with cells treated with pre-incubated medium did not show any effects either.ConclusionsThese data showed that silver wires strongly affect the alveolar epithelial cells, whereas spherical silver particles had no effect. This supports the hypothesis that shape is one of the important factors that determine particle toxicity.

Transport through quantum dots in mesoscopic circuits.

We study the transport through a quantum dot, in the Kondo Coulomb blockade valley, embedded in a mesoscopic device with finite wires. The quantization of states in the circuit that hosts the quantum dot gives rise to finite size effects. These effects make the conductance sensitive to the ratio of the Kondo screening length to the wires length and provide a way of measuring the Kondo cloud. We present results obtained with the numerical renormalization group for a wide range of physically accessible parameters.

Enhancement of gas phase heat transfer by acoustic field application

This study discusses a possibility for enhancement of heat transfer between solids and ambient gas by application of powerful acoustic fields. Experiments are carried out by using preheated Pt wires (length 0.1–0.15 m, diameter 50 and 100 μm) positioned at the velocity antinode of a standing wave (frequency range 216–1031 Hz) or in the path of a travelling wave (frequency range 6.9–17.2 kHz). A number of experiments were conducted under conditions of gas flowing across the wire surface. Effects of sound frequency, sound strength, gas flow velocity and wire preheating temperature on the Nusselt number are examined with and without sound application. The gas phase heat transfer rate is enhanced with acoustic field strength. Higher temperatures result in a vigorous radiation from the wire surface and attenuate the effect of sound. The larger the gas flow velocity, the smaller is the effect of sound wave on heat transfer enhancement.

Properties of Metallic Nanowires: From Conductance Quantization to Localization

Material structures of reduced dimensions exhibit electrical and mechanical properties different from those in the bulk. Measurements of room-temperature electronic transport in pulled metallic nanowires are presented, demonstrating that the conductance characteristics depend on the length, lateral dimensions, state and degree of disorder, and elongation mechanism of the wire. Conductance during the elongation of short wires (length l approximately 50 angstroms) exhibits periodic quantization steps with characteristic dips, correlating with the order-disorder states of layers of atoms in the wire predicted by molecular dynamics simulations. The resistance R of wires as long as l approximately 400 angstroms exhibits localization characteristics with In R(l) approximately l(2).

Magnum wire for balloon recanalization of chronic total coronary occlusions

A new guidewire (Magnum wire, Schneider) was developed for balloon recanalization of chronic total coronary occlusions. This 0.021-inch solid-steel wire with a floppy tip equipped with a 1-mm diameter “olive” is used like an ordinary guidewire, fits conventional balloon catheters and provides excellent steerability. Magnum wires were used in 50 consecutive chronic total coronary occlusions (mean ± standard deviation duration 8 ± 21 months, range 1 day to 10 years; mean length 1.1 ± 0.8 cm, range 0.2 to 4.0). All occlusions were reached (in 23 right, 18 left anterior descending, 8 left circumflex coronary arteries and 1 diagonal branch) and 30 (60%) were recanalized (1 reoccluded during the procedure, and in 3 patients the Magnum wire did not completely cross the occlusion but enabled the previously impossible passage of a conventional wire). The mean age of the occlusion was 3 ± 4 months in successful and 17 ± 33 months in unsuccessful procedures (p = 0.04) and the mean length was 1.1 ± 0.9 and 1.3 ± 0.6 cm, respectively (p = 0.4). In 17 patients, conventional techniques had been exhausted before the Magnum wire attempt, which was successful in 8 (47%). In 33 patients the Magnum wire was tried first, with success in 22 (67%). Conventional techniques were subsequently tried in 9 of the 11 failures (none was successful). Of the 38 procedures carried out with a second, improved version of the Magnum wire, 26 (68%) were successful. In terms of complications, 2 distal clot embolizations, with a small creatine kinase increase in 1, occurred during or secondary to Magnum wire manipulations, whereas 3 proximal dissections with side branch occlusion in 2 (1 with a small creatine kinase increase) occurred during or secondary to attempts with conventional wires. The Magnum wire is a simple, safe and inexpensive tool for balloon recanalization of chronic total coronary occlusions. It is subject to the basic limitations of conventional wires (duration and length of the occlusion, subintimal passage) but yields a slightly higher success rate, probably due to superior pushing power and a more blunt approach that reduces the risk of subintimal passage. Evaluation of the Magnum wire for coronary lesions other than total occlusions is under way.

Restrike Mechanisms of Exploding Wire Discharges

The development of the early stages of restrike channels initiated by electrically exploded thin wires was studied, using high-speed Kerr-cell and rotating-mirror streak photographic techniques. The experiments were performed mainly with constantan and copper wires (length: 13.8 cm, diameter: 0.005 cm). Complementary measurements were also made on five lengths between 1.6 and 13.8 cm at voltages up to 23 kV. The results show that at low voltages the restrike is always initiated at the exterior of the exploded wire. At higher voltages, above a critical voltage, the restrike is initiated either at the exterior or in the interior of the exploded wire. The majority of the restrikes are initiated in the interior. Restrikes initiated at the exterior of the exploded wire always have much shorter dwell times than those initiated in the interior and a good dwell-time reproducibility. During the dwell-time which precedes these restrikes, luminous dots appear at the surface of the wire. The dots are distributed helicoidally along the whole wire length. The presence of these dots may indicate an intense local ionization on the wire surface due to the emission of thermal electrons from the wire material. The ionization increases to the point at which a thin helicoidal channel is built up near the surface and along the whole length of the exploded wire. The restrike starts and develops in this channel until it loses its form through instability. For restrikes initiated in the interior of the exploded wire, no local ionization was observed at the surface of the wire during the dwell time. This may have been due to the rapid vaporization of the wire material. During the dwell time the exploded wire shows a diffuse low luminosity, which increases when ionization by impact is initiated in the interior of the wire. The luminosity of the wire remains diffuse until the ionized medium contracts and the restrike starts in a very narrow channel near the axis of the wire. The channel expands with a very high velocity towards the inner shell of the exploded wire. The initial phase of the channel shows an helicoidal form. The channel tends to be straight when its diameter increases. The type of restrike which follows the wire explosion seems to be dictated by the vaporization rate of the wire material.