End Of Wire Research Articles

Detecting Majorana modes in one-dimensional wires by charge sensing

The electron number-parity of the ground state of a semiconductor narowire proximity-coupled to a bulk superconductor can alternate between the quantised values $\pm 1$ if parameters such as the wire length $L$, the chemical potential $\mu$ or the magnetic field $B$ are varied inside the topological superconductor phase. % The parity jumps, which may be interpreted as changes in the occupancy of the fermion state formed from the pair of Majorana modes at opposite ends of the wire, are accompanied by jumps $\delta N$ in the charge of the nanowire, whose values decrease exponentially with the wire length. % We study theoretically the dependence of $\delta N$ on system parameters, and compare the locations in the $\mu$-$B$ plane of parity jumps when the nanowire is or is not proximity-coupled to a bulk superconductor. % We show that, despite the fact that the wave functions of the Majorana modes are localised near the two ends of the wire, the charge-density jumps have spatial distributions that are essentially uniform along the wire length, being proportional to the product of the two Majorana wave functions. % We explain how charge measurements, say by an external single-electron transistor, could reveal these effects. % Whereas existing experimental methods require direct contact to the wire for tunneling measurements, charge sensing avoids this issue and provides an orthogonal measurement to confirm recent experimental developments. % Furthermore, by comparing density of states measurements which show Majorana features at the wire ends with the uniformly-distributed charge measurements, one can rule out alternative explanations for earlier results. % We shed light on a new parameter regime for these wire-superconductor hybrid systems, and propose a related experiment to measure spin density.

Economical, Efficient, Simple Device for Controlled Annealing NiTi Archwire

In fixed orthodontic treatment, for the cinch back purpose, there is need of annealing of distal end of NiTi arch wire. During this procedure the area or length to be annealed is difficult to control. This inappropriate heating leads to deleterious effect on property of the wire. To prevent this problem a simple economical and efficient device was prepared that prevents annealing of excessive length of wire and thus prevents the deterioration of wire required for appropriate action.

A strange case involving partial fracture of percutaneous transluminal coronary angioplasty wire and its successful retrieval

angina of a critical lesion of the proximal left anterior descending artery. After negotiating with spring-type wire (balance middle-weight wire), a loop was formed. Due to excessive manipulation to unloop the wire, it partially fractured at the shaft and coil junction. As the proximal section was retrieved, a thin elongated filament of spring coil also came out from the Y-connector while the remainder of the coil was still trapped in the lesion. Two balance middle-weight wires were then placed distally, and the proximal ends of both wires were inserted together in a torque device, which were firmly screwed and rotated 45 to 55 times in a circular pattern. During this rotational motion, the broken segment along with thin filament was tangled within these rescue wires and all three wires were removed together using tangling technique. Following this, angioplasty was performed successfully. After reviewing the literature using PubMed, to the authors’ knowledge, this is the first incident of its kind to be reported.

High-gain effects minimized at the ends of the anodes in position sensitive gas proportional counters for SSM on ASTROSAT

The Scanning Sky Monitor (SSM) on ASTROSAT is a position-sensitive gas-filled proportional counter with a wide field of view. The science objective of SSM is to scan the sky to detect and locate transient X-ray sources in the outburst phase. The energy range of operation of SSM is 2.5 to 10 keV. Gas-filled proportional counters are known to have distorted electric fields at the ends of the anodes inside the detector. The electric field and hence the gas gain is different at the ends of the anodes compared to that of the central region. In SSM, the ends of the anode wires were found to have high electric field values and hence high gas gain initially. These effects had to be minimized as they would result in huge charge collection for incidence of highly energetic photons and charged particles, leading to probable discharge effects which would limit the life time of the detector. They also result in undesirable signals, the amplitude of which may not be proportional to the energy of the incident photon. In this paper, we discuss the technique which we use to reduce the field at the ends of the anodes in SSM detectors.

Flame spread over electrical wire with AC electric fields: Internal circulation, fuel vapor-jet, spread rate acceleration, and molten insulator dripping

The effect of electric field on the characteristics of flame spread along a polyethylene (PE) insulated electrical wire was investigated experimentally by varying the AC frequency and voltage applied to the wire. The results showed that the flame spread rate was accelerated due to the convergence of electric flux near the end of wire, having three distinct regimes depending on applied voltage. In each regime, several subregimes could be identified depending on AC frequency. Flame shape (height and width) and slanted direction of the spreading flame were influenced differently. Fuel-vapor jets were ejected from the molten PE surface even for the baseline case without the application of an electric field; this could be attributed to the bursting of fuel vapor bubbles generated from internal boiling at the molten PE surface. An internal circulation of molten-PE was also observed as a result of non-uniform heating by the spreading flame. In the high voltage regime with a high AC frequency, excessive dripping of molten PE led to flame extinction.

More uniform Pd distribution in free-air balls of Pd-coated Cu bonding wire using movable flame-off electrode

The currently high price of gold wire has led to the development of bonding wire made from palladium-coated-copper as a lower cost alternative. Increasing the uniformity of the Pd distribution in free-air balls, formed by melting the wire end with an electric spark, is of interest as it can influence the uniformity of process and reliability. To study this Pd distribution, free-air balls are made using four distinct electrical flame-off (spark) processes with short and long spark times from wire bonders with fixed and movable electrodes. Elemental analysis of the free-air ball surfaces reveal a higher Pd concentration on the movable electrode free-air balls than on the fixed electrode free-air balls. Elemental analysis of cross-sections show that the Pd distribution in free-air balls made with a fixed electrode has Pd trails flowing from the neck into the Cu ball center. Furthermore, micro- and nano-voids are observed to follow the Pd trails. In contrast, free-air balls made with a movable electrode exhibit less severe voiding and retain a uniform, thin Pd layer along the surface up to the tip of the free-air ball (shorter spark time). This can help to increase process consistency and reliability.

Towards a solution of the wires' slippage problem of the Ilizarov external fixator.

Clinical experience has indicated that many complications during treatment with the Ilizarov method, and mainly tract infection, are related to decreased wire tension. The aim of this work was to evaluate biomechanically a novel wire tensioning and clamping system that will minimise or even diminish the reduction of the wire pretension during treatment. The proposed approach is based on threading of the wire end in a sufficient length. The wire pretension is applied by twisting a nut on the threaded part of the wires against the ring and is recorded by an incorporated force sensor. For biomechanical evaluation, the frame, consisting of a polyethylene bar, simulating the bone fragment, suspended on two rings, was subjected to a dynamic load of 0-800 N at a frequency of 0.5 Hz. After dynamic loading for 20 min, loss of the initial wire pretension for the novel clamping system ranged between 12 and 16%. The average loss for conventionally clamped wires was 75%. The advantages of the novel clamping system were the much greater ability to sustain the transverse load and the easy and effectual wire re-tensioning. Although wire slippage has been avoided with the novel system, wire material yield is still responsible for a pretension loss.

Stress Forming of Fine Metal Wire Based on Ultrasonic Vibration

The assembling process of the flex lead of an accelerometer can bring in internal stress, which causes drift error and affects the precision of the accelerometer. The paper introduces a method using ultrasonic vibration to reduce the internal stress, discusses the theory of ultrasonic stress relief on fine wires, shows ultrasonic stress relief experimental apparatus which uses an optimized ultrasonic tool head to inflict ultrasonic vibration to fine wires. By introducing the displacements of the fine wire ends into ANSYS, changes of the internal stress of the fine wire can be obtained. The experiment studies the performance of ultrasonic vibration to fine wire internal stress and deals with the relationship between infliction time and results. The experiment results confirmed that by selecting the suitable experiment parameters, ultrasonic vibration is an effective way to internal stress relief, the internal stress decline as infliction time increase then stays.

Time-reversal invariant parafermions in interacting Rashba nanowires

We propose a scheme to generate pairs of time-reversal invariant parafermions. Our setup consists of two quantum wires with opposite Rashba spin orbit interactions coupled to an $s$-wave superconductor, in the presence of electron-electron interactions. The zero-energy bound states localized at the wire ends arise from the interplay between two types of proximity induced superconductivity: the usual intrawire superconductivity and the interwire superconductivity due to crossed Andreev reflections. If the latter dominates, which is the case for strong electron-electron interactions, the system supports Kramers pair of parafermions. Moreover, the scheme can be extended to a two-dimensional sea of time-reversal invariant parafermions.

Relationship between Creeping Discharge along Aerial Insulated Cable and Duration of Wave Front of Inductive Lightning Surge

SUMMARYWe report the results obtained on the developing characteristics of creeping discharges along the insulated cable surface under inductive lightning surge voltages with various durations of wave front. The aerial insulated cables, usually, are supported by the post insulator and the binding wire at the reinforced concrete pole. When a lightning strikes near by the aerial insulated cables, the overvoltage due to the inductive lightning surge invades to the central line of the cable. The creeping discharge can develop along the cable surface from the free end of the binding wire just after a flashover of the post insulator at the cable supporting point. This creeping discharge may give rise to the accidents such as a melting or snapping of the cable. An important subject to prevent these accidents is to clarify the characteristics of creeping discharge along the cable surface and the developing mechanism of discharges. In this study, the impulse voltages with various durations of wave front are applied to the central line of the wire as the inductive lightning surge. The length and aspect of positive and negative creeping discharges developing along the cable surface are measured using a still camera with an image intensifier, and the developing mechanisms of creeping discharges are discussed on the basis of the models which are proposed taking into account the obtained results.

Quantum-state transfer in spin chains via isolated resonance of terminal spins

We propose a quantum-state transfer protocol in a spin chain that requires only the control of the spins at the ends of the quantum wire. The protocol is to a large extent insensitive to inhomogeneity caused by local magnetic fields and perturbation of exchange couplings. Moreover, apart from the free evolution regime, it allows one to induce an adiabatic spin transfer, which provides the possibility of performing the transfer on demand. We also show that the amount of information leaking into the central part of the chain is small throughout the whole transfer process (which protects the information sent from being eavesdropped) and can be controlled by the magnitude of the external magnetic field.

Subtle leakage of a Majorana mode into a quantum dot

The authors predict a resonance arising in a quantum dot connected to source and drain leads and side-coupled to a Kitaev wire sustaining Majorana end modes. The Majorana bound state in the wire's end leaks into the dot, generating a resonance pinned to the Fermi level of the leads. This may provide a means to detect Majorana modes.

Direct STM Studies of CO Adsorption and Oxidation on Pt(111) Electrodes: (1) Electrochemical Measurements and STM Observations

The mechanism of the adsorption and electrochemical oxidation of CO in electrolyte solutions on Pt catalysts has long been studied. Significantly enhanced CO oxidation has been observed in the presence of a CO adlayer preadsorbed at low electrode potentials, giving rise to a well-known prepeak in the CO stripping voltammogram prior to the main CO oxidation peak. Evidence was presented to show an effect of the defect sites on the Pt(111) surface on the characteristics of the prepeak.1) Wieckowski and coworkers extensively investigated the role of defects for the CO electrooxidation in alkaline media,2) and Strmcnik et al. reported that platinum surfaces modified with platinum nanoislands have a high activity for CO oxidation at prepeaks.3) In the present study, the CO electrooxidation at Pt(111)-oriented surfaces with steps is investigated by combining electrochemical measurements and electrochemical (EC) STM.3) Single-crystal beads of Pt were made by crystallization of molten balls formed at the end of Pt wires in a hydrogen–oxygen flame. The (111)-oriented planes were exposed by mechanical polishing. The surfaces were then heat-treated in an infrared imaging furnace and cooled under hydrogen. The electrochemical measurements were carried out in 0.1 M HClO4. EC-STM measurements were carried out using a CO- or N2-saturated solution under a CO atmosphere. For the reference electrode, an RHE was used. Fig. 1(a) shows voltammograms obtained in CO-saturated HClO4 on Pt(111) with (111) steps The CO oxidation started at ca. 0.4 V in the prepeak region. After the electrochemical potential was cycled between 0.05 and 0.95 V 30 times, the prepeak observed at lower potentials completely disappeared.4) By examining CO stripping voltammograms with and without CO in solution (Fig. 1(b)), it was suggested that the origin of this prepeak is the oxidation of bulk CO in solution. Fig. 2 shows the STM images at a (111) step on Pt(111) recorded before and after the potential cycling. The (2x2) structure of the CO adlayer is clearly seen. Before the potential cycling, the step has defects, forming a zigzag line (Fig. 2(a)). After the potential cycling, the step became very straight running in the [110] direction, with no defects observed (Fig. 2(b)). The structure change at steps should be related to the reactivity. On Pt(20 19 19) with (100) steps, the prepeak was very small, and after the potential cycles disappeared completely. Fig. 3(a) shows an STM image on Pt(20 19 19) before cycling. The step is straight, which might explain the small prepeak on pristine Pt(20 19 19). Fig. 3(b) shows an image after the potential cycles. The (111) microsteps were introduced to the (100) step, and the step became zigzagged. From the results on Pt(111)-related surfaces with different steps, it can be understood that not every defect is active for the electrooxidation of CO in solution.This research was supported by MEXT and NEDO, Japan.ReferencesA. Lopez-Cudero, A. Cuesta, and C. Gutierrez, J. Electroanal. Chem. 579, 1 (2005).J. S. Spendelow, Q. Xu, J. D. Goodpaster, P. J. A. Kenis, and A. Wieckowski, J. Electrochem. Soc., 154, F238, (2007)D. S. Strmcnik, D. V. Tripkovic, D. van der Vliet, K.-C. Chang, V. Komanicky, H. You, G. Karapetrov, J. P. Greeley, V. R. Stamenkovic, and N. M. Markovic, J. Am. Chem. Soc., 130, 15332 (2008).J. Inukai, D. A. Tryk, T. Abe, M. Wakisaka, H. Uchida, and M. Watanabe, J. Am. Chem. Soc ., 135, 1476 (2013).

Diamond nanoprobes for electrical probing of nanoelectronics device structures

Electrical nanoprobing inside scanning electron microscopy (SEM) systems has become a routinely used characterization technique for electrically measuring prototypes of the most advanced nanoelectronics device structures. Tungsten wire needles with a sharpness of about 50–100nm are commonly used as probe tips in these measurements. They suffer unfortunately from tip oxidation effects and need to be initialized. Moreover, they are too soft to directly probe on semiconductor materials such as Si and Ge. Therefore, harder probe tips are required which can withstand high pressures (in GPa range) and oxidation. In order to meet these requirements, we have developed doped diamond tips and integrated them into metal cantilevers. They have an in-plane geometry which allows direct visibility in the SEM system of both the area to be contacted and the tip apex. Furthermore, the probes are mounted at the end of a metal wire which ensures compatibility with existing nanoprobing systems and allows for convenient probe handling. This paper describes the probe concept and discusses the probe fabrication process in detail. Manufactured probes are presented and their suitability for measurements on a Ge calibration structure is demonstrated. Our work shows that the developed diamond nanoprobes overcome the disadvantages of existing tungsten wire probes and enable the probing of semiconductor materials.

Kitaev spin models from topological nanowire networks

We show that networks of topological nanowires can realize the physics of exactly solvable Kitaev spin models with two-body interactions. This connection arises from the description of the low-energy theory of both systems in terms of a tight-binding model of Majorana modes. In Kitaev spin models the Majorana description provides a convenient representation to solve the model, whereas in an array of topological nanowires it arises, because the physical Majorana modes localized at wire ends permit tunnelling between wire ends and across different Josephson junctions. We explicitly show that an array of junctions of three wires -- a setup relevant to topological quantum computing with nanowires -- can realize the Yao-Kivelson model, a variant of Kitaev spin models on a decorated honeycomb lattice. Translating the results from the latter, we show that the network can be constructed to give rise to collective states characterized by Chern numbers \nu = 0, +/-1 and +/-2, and that defects in an array can be associated with vortex-like quasi-particle excitations. Finally, we analyze the stability of the collective states as well as that of the network as a quantum information processor. We show that decoherence inducing instabilities, be them due to disorder or phase fluctuations, can be understood in terms of proliferation of the vortex-like quasi-particles.

Do it yourself: building an ERCP training system within 30 minutes (with videos)

Ex vivo training of ERCP by using simulators is desirable before trainees perform endoscopy in patients. We aimed to construct a simple and inexpensive but realistic simulator for ERCP training. Construction and establishment of an ERCP simulator. Endoscopy suite. An ERCP simulator was assembled by using a polyvinylchloride hose, insulated wire end sleeves, a plastic board, and hose clamps. Application of the simulator for endoscopic training, with focus on endoscope maneuverability as well as on alignment and intubation of the papilla and assessment of simulator performance by a short questionnaire. Because of the sufficient diameter of the hose and varying orientations of the wire end sleeves, the system allows for realistic endoscope maneuvering and wire intubation of the "papillary orifices." Trainees feel better prepared and more confident in the technique before performing ERCP in patients for the first time. Extensive validation and statistical evaluation is lacking. The construction offers the opportunity to provide a readily available simulator for initial access to basic ERCP techniques.

Experimental Results for Concentricity in Wire Coating Processes

The wire coating thickness and quality depend on the wire speed, polymer viscosity, polymer melt temperature and the gap between the wire and exit end of the die. In this paper, results of experimental investigation are presented by comparing the coating quality on galvanized mild steel wire using EP 58 PVC molten is used as the coating material in a wire coating extrusion unit at different extruder temperatures and extruder speeds. The coating thickness and quality are also discussed for different wire speeds of up to 15 m/s.

Wire Joining by Rotary Swaging

A new wire joining process for wires with sub-millimeter diameters applying the rotary swaging was investigated. The basic idea is to join two wire ends by a tube segment. In the study different material combinations using steel (AISI304) and copper (CW004A) were examined. Further the realization of a form-locked joint was investigated. The formed samples were tested by optical microscopy and tensile testing and compared to spot welded samples.

Negative Creeping Discharge along Aerial Insulated Wire under Wet Condition

The aerial insulated wires are supported by post insulators and binding wires on the reinforced concrete pole. When a lightning flash strikes near by the wires, the overvoltage due to the indirect lightning surge induces to the conductive wire core. The creeping discharge can develop along the wire surface from the free end of the binding wire through post insulator and reinforced concrete pole compound when a flashover occurred at the post insulator and it also leads to damages on the wire such as melting or snapping. It could be occurred under both rainy and thunderstorm condition. In this case, it indicates that the wire surface is stressed by lightning impulse under wet condition. Consequently, it is an important subject to prevent the wire damages and to clarify the characteristics of creeping discharge along the wire surface under dry and wet condition. In the previous studies, we had observed the characteristics of creeping discharge along the wire surface under dry condition. In this study, we examined creeping discharges under both the impulse voltages with various durations of wave front and wet condition on the wire surface. Then, these voltages were applied to the conductive wire core as the inductive lightning surge. The length and phenomena of negative creeping discharge developing along the wire surface were measured using a still camera with an image intensifier. We report the developing characteristics of negative creeping discharge along the wire surface under wet condition.

Alternating-current losses in two-layer superconducting cables consisting of second-generation superconductors coated by U-shaped ferromagnetic materials

Alternating-current losses in a two-layer superconducting cable, each layer being composed of 15 closely-spaced rectangular wires made up of second-generation superconductors when the ends of wires are coated by either a non-magnetic or strong ferromagnetic material having a U profile is numerically investigated. Computations are carried out through the finite-element method. The alternating-current losses do not increase significantly if the relative permeability of the coating is increased three orders of magnitude, provided that the current amplitude is less than half of the critical current in a superconducting wire. However, the losses are much higher for ferromagnetic coating if the amplitude of the applied current oscillating at 50 Hz is close to the critical current. The ferromagnetic coating is seen to accumulate the magnetic field lines normally on its surfaces, while the field lines are parallel to the long axes of the wires, leading to more significant flux penetration in the coated regions. This facilitates a uniform low-loss current flow in the uncoated regions of the wires. In contrast, coating with a non-magnetic material gives rise to a considerably smaller current flow in the uncoated regions, whereas the low-loss flow is maintained in the coated regions. Moreover, the current flows in opposite directions in the coated and uncoated regions, where the direction in each region is converse for the two materials.