Small Wire Research Articles

EFFECTS OF CONFINED LO AND SO PHONON MODES ON POLARON IN FREESTANDING CYLINDRICAL QUANTUM WIRE WITH PARABOLIC CONFINEMENT

The electron self-energy and correction to the electron effective mass in a freestanding quantum wire with parabolic confining potential was investigated by the perturbation approach. Both the electron-confined longitudinal optical (LO) phonon and surface optical (SO) phonon interactions were considered. Results shows that, for small wire radius, the contributions of electron–LO phonon interaction to the electron self-energy and the correction to the electron effective mass are relatively small in compare with those of the electron–SO phonon interaction.

Gingival health and relapse tendency: a prospective study of two types of lower fixed retainers

Abstract Background Different types and diameters of wire are used in bonded lingual retainers. Some clinicians bond a small diameter multistrand wire to each tooth, while other clinicians bond a large diameter wire to the lingual surfaces of the lower canines. Aim To compare the gingival health, plaque accumulation, tooth stability and integrity of multistrand wire and round wire bonded lingual retainers. Methods Sixty-two subjects, who had completed treatment and who required fixed retention for the lower anterior segment, were assigned to either the Round wire retainer group or the Multistrand wire retainer group. In the Round wire retainer group, a 0.036 inch round, stainless steel wire was bonded to the lingual surfaces of both lower canines. The Multistrand retainer group had a 0.015 inch multistrand wire bonded to the lingual surfaces of all lower anterior teeth. At least 12 months after debonding, the subjects were recalled and the following variables were recorded: Oral Hygiene Index (OHI), Plaque Index (PI) of the lower anterior teeth, Gingival Index (GI) of the lower anterior teeth, Irregularity Index (IRI) of the lower anterior teeth, and the number of broken retainers. Results There were no significant differences between the PI (p = 0.165) and GI (p = 0.150) of the two groups. More plaque was found on the distal surfaces of the lower anterior teeth in the group with multistrand wire retainers (p = 0.02). The lower anterior teeth were significantly more irregular in the group with round wire retainers compared to the group with multistrand wire retainers (p = 0.002). Although the multistrand wire retainers fractured more frequently than the round wire retainers the difference was not statistically significant (p = 0.325). Conclusion More plaque accumulated on the distal surfaces of the lower anterior teeth in subjects with multistrand wire retainers than in subjects with round wire retainers. Multistrand wire retainers were better at maintaining incisor alignment than single span, round wire retainers.

Intrarenal artery superoxide is mainly NADPH oxidase-derived and modulates endothelium-dependent dilation in elderly patients

The present study was performed to investigate the contribution of NADPH oxidases (Nox) to superoxide formation in human renal proximal resistance arteries and to test whether superoxide formation contributes to acute vasoconstrictor responses and endothelium-dependent vasodilation in these vessels. Arcuate and proximal interlobular artery segments were from patients who underwent nephrectomy because of a renal tumour. Vessels were dissected from tumour-free parts of the kidneys. Additional intrarenal arteries were obtained from rats. Superoxide formation was measured by lucigenin-enhanced chemiluminescence, expression of Nox isoforms was analysed by RT-PCR, and functional studies were performed by small vessel wire myography. Sixty per cent of superoxide formation in human arcuate and proximal interlobular arteries was due to Nox activity. mRNA expression analyses revealed the presence of Nox2 and Nox4 but not Nox1. Phenylephrine and endothelin-1 induced powerful concentration-dependent vasoconstrictions that were unaffected by superoxide scavengers. Vasopressin elicited small and variable vasoconstrictions with signs of tachyphylaxis. Endothelium-dependent vasodilation was blunted by tiron and Nomega-nitro-L-arginine methyl ester but not by superoxide dismutase or catalase. Exogenous hydrogen peroxide elicited vasoconstriction. Nox activity is the major source of superoxide formation in renal proximal resistance arteries from elderly patients. Acute vasoconstrictor responses to alpha1-adrenoreceptor activation and to endothelin-1 do not depend on superoxide formation, while endothelium-dependent vasodilation in intrarenal arteries is reactive oxygen species-dependent.

Fabrication of double-dot single-electron transistor in silicon nanowire

We propose a simple method for fabricating Si single-electron transistors (SET) with coupled dots by means of a pattern-dependent-oxidation (PADOX) method. The PADOX method is known to convert a small one-dimensional Si wire formed on a silicon-on-insulator (SOI) substrate into a SET automatically. We fabricated a double-dot Si SET when we oxidized specially designed Si nanowires formed on SOI substrates. We analyzed the measured electrical characteristics by fitting the measurement and simulation results and confirmed the double-dot formation and the position of the two dots in the Si wire.

Reflection of Cylindrical Surface Waves

The reflection of the radially polarized surface wave on a metal wire at an abrupt end is derived. This theory allows for straightforward calculation of the reflection coefficient, including the phase and the amplitude, which will prove useful to the many applications in nanoplasmonics and terahertz spectroscopy. The theory shows excellent quantitative agreement with past comprehensive numerical simulations for small wires and for predicting the minima in reflection for larger wires. Using this theory, the wavelength dependent reflection is calculated for gold rods of diameter 10 nm, 26 nm and 85 nm, from which the Fabry-Perot resonance wavelengths are found. The Fabry-Perot resonances show good agreement with experimentally measured surface plasmon resonances in nanorods. This demonstrates the predictive ability of the theory for applications involving widely-used nanorods, optical antennas and plasmonic resonators.

Instrumentation-Specific Infection After Anterior Cruciate Ligament Reconstruction

Background:Anterior cruciate ligament (ACL) reconstruction is uncommonly complicated by postoperative infections, the causes of which are rarely identified.Hypothesis/Purpose:The goal of this study was to characterize the relationship between methodological sterilization failure and ACL reconstruction infection at an army medical center.Study Design:Case series.Methods:Demographic, clinical, and laboratory data were collected on 5 postoperative infections during a 14-week period in 2003. All ACL reconstructions completed within the past 6 years at the institution were reviewed to establish a baseline infection rate.Results:There was a 14-week period in which 5 cases of infection occurred postoperatively, an infection rate of 12.2%. Previous and subsequent to the identified period, the established rate of infection after ACL reconstruction was 0.3%. There were no violations of sterile technique noted in any of the identified cases. All cases utilized hamstring autograft. All cases also used the DePuy Mitek Intrafix system for tibial fixation of the graft. Two of these cases had positive cultures.Conclusions:An isolated series of increased infection rate led to an investigation into the sterile technique. This revealed gross biomaterial remaining inside instrumentation common to all the cases, the DePuy Mitek Intrafix system. The modular cannulated hex driver, made to fit over a small caliber wire, had no wire brushes of a small-enough diameter for the cleaning and sterilization procedure. After recognition of infection, all patients were treated with surgical irrigation and debridement of the affected knee, as well as individualized antibiotic therapy. Patients were followed postoperatively and no patients required revision ACL reconstruction or radical debridement of the graft.

All-electric quantum point contact spin-polarizer

The controlled creation, manipulation and detection of spin-polarized currents by purely electrical means remains a central challenge of spintronics. Efforts to meet this challenge by exploiting the coupling of the electron orbital motion to its spin, in particular Rashba spin-orbit coupling, have so far been unsuccessful. Recently, it has been shown theoretically that the confining potential of a small current-carrying wire with high intrinsic spin-orbit coupling leads to the accumulation of opposite spins at opposite edges of the wire, though not to a spin-polarized current. Here, we present experimental evidence that a quantum point contact -- a short wire -- made from a semiconductor with high intrinsic spin-orbit coupling can generate a completely spin-polarized current when its lateral confinement is made highly asymmetric. By avoiding the use of ferromagnetic contacts or external magnetic fields, such quantum point contacts may make feasible the development of a variety of semiconductor spintronic devices.

A note on the measurement of temperature in reciprocating engines using thermocouples

This paper presents a theoretical analysis of the response of a thermocouple placed in a reciprocating engine. The manner in which the temperatures recorded by the thermocouple lag behind and are attenuated from the fluctuating fluid temperatures because of thermal inertia of the thermocouple is analysed. A method is suggested for computing the true fluid temperatures from the measured temperatures in an engine under both motoring and operating conditions. This compensation technique allows the use of larger, more robust thermocouples without losing the rapid time response of very small thermocouple wires.

Study on Filtration Performance of Cylinder Metal Rubber Filtering Material

As a novel porous functional material, metal rubber (MR) had many advantages of high loading capacity, high anti-blocked capacity and adjustable porosity with outside pressure made the MR more suitable as filtration material. However, there was no related study and successful application nowadays except in Russia. This study detailed investigated the filtration performance of MR including the influence of wire line diameter, porosity and molding thickness on initial pressure drop under clean liquid condition and their effects on pressure drop-flow rate property and filtration efficiency under contaminated liquid condition. The results indicate that the initial pressure drop increased with the decrease of porosity and wire line diameter, however decreased with the decrease of molding thickness when the flow was constant. Filtration drop increased significantly with the decrease of porosity. MR material made of small diameter wires showed a high filtration efficiency and large pressure drop because of its’ fine micro-pore. Filtration drop rose with the increase of molding thickness however, the filtration efficiency was little affected. These results provide a suitable guideline for further MR filter appliance and MR material research.

Interface elasticity in nanostructured silicon

We investigate through atomistic simulations the mechanical behavior of a c-Si nanowire embedded in an elastically different c-Si. The results are compared with the continuum predictions based on the elasticity theory. The observed deviations between the two approaches are due to the presence of the disordered interface in the atom-resolved system which, for small wires, induces sizable prestrain into the sample, also in absence of any external loads. Finally, we develop a continuum model fully exploiting such interface effects provided by the atomistic simulations.

Combination of Fine Wire Fixation and Limited Internal Fixation for High-Energy Tibial Plateau Fractures: Functional Results at Minimum 5-Year Follow-up

To assess knee function and the development of knee arthrosis, at 3 and 5 years postoperatively, in high-energy tibial plateau fractures that were treated with minimal internal fixation augmented by small wire circular frames. Level II trauma hospital. : Retrospective study. Between October 1988 and December 1999, 145 consecutive high-energy tibial plateau fractures were treated with hybrid fixation including small wire circular or hybrid frames, minimal internal fixation, and occasionally provisional extension of the external fixation to the distal femur. One hundred twenty-seven patients with 129 fractures (89%) were included in the study. There were 68 (53%) C1, 20 (15%) C2, and 41 (32%) C3 fractures. Forty-seven (36.5%) of the total were open fractures. Clinical, subjective, objective, and radiographic results were evaluated at the time of union, at a minimum 3 years postoperatively, and at final minimum follow-up of 5 years. Results were assessed according to the Honkonen-Jarvinen criteria. An excellent or good subjective result was noted in 106 fractures (82%) at a minimum 3-year follow-up, whereas an excellent or good score was achieved in 101 fractures (78%) at a minimum 5 years. A statistically significant deterioration (P = 0.001) of the post-traumatic radiographic arthritis was recorded at 5 years postoperatively. High-energy tibial plateau fractures treated with minimal internal fixation augmented by small wire external fixation frames yielded a high percentage of cases exhibiting radiographic post-traumatic arthritis. However, because all the objectives of fracture treatment seemed to be obtained, the functional results remain satisfactory over time.

Multiobjective optimization for small meander wire dipole antennas in a fixed area using ant colony system

Fixed area meander line antennas designed on a 5 × 5 rectangular grid were optimized for efficiency and resonant frequency. The Pareto front was developed using ant colony optimization and the numerical electromagnetic code. The lowest frequency antenna fits an area of 0.11λ0 × 0.05λ0 with an efficiency of 88%. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.

A precise water displacement method for estimating egg volume

Relationships between egg volume and an array of life-history traits have been identified for many bird species. Despite the importance of egg volume and the need for precise and accurate measurements, egg volume is usually estimated using a mathematical model that incorporates length and width measurements along with a shape variable. We developed an instrument that provides precise estimates of egg volume and can be easily used in the field. Using Clapper Rail {Rallus longirostris) eggs, we compared egg volumes measured using our instrument with estimates based on linear measurements. We found our instrument to be both precise and accurate. Compared with a method based on linear measurements of eggs, use of our instrument reduced variation in egg volume estimates by 1.6 cm3, approximately 8% of the volume of a Clapper Rail's egg. Further advantages of our technique include ease of use, increased accuracy of field-based volume estimates, and increased resolution of variation in egg volume estimates. In addition, our technique does not require postdata collection processing time and did not influence hatching success. Also, for Clapper Rails and similar species, our technique can be combined with other techniques (e.g., egg flotation) so that both egg volume and embryonic stage can be estimated at the same time.

Fine and ultra‐fine pitch wire bonding: challenges and solutions

Purpose – The purpose of this paper is to review recent advances in fine and ultra‐fine pitch wire bonding.Design/methodology/approach – Dozens of journal and conference articles published recently are reviewed.Findings – The problems/challenges such as possible wire sweep and decreased bonding strength due to small wire sizes, non‐sticking, metal pad peeling, narrow process windows, wire open and short tail defects are analysed. The solutions to the problems and recent findings/developments in fine and ultra‐fine pitch wire bonding are discussed.Research limitations/implications – Because of the page limitation, only brief discussions are given in this paper. Further reading is needed for more details.Originality/value – This paper attempts to provide an introduction to recent developments and the trends in fine and ultra‐fine pitch wire bonding. With the references provided, readers may explore more deeply by reading the original articles.

Dose perturbations from implanted helical gold markers in proton therapy of prostate cancer

Implanted gold fiducial markers are widely used in radiation therapy to improve targeting accuracy. Recent investigations have revealed that metallic fiducial markers can cause severe perturbations in dose distributions for proton therapy, suggesting smaller markers should be considered. The objective of this study was to estimate the dosimetric impact of small gold markers in patients receiving proton therapy for prostate cancer. Small, medium, and large helical wire markers with lengths of 10 mm and helix diameters of 0.35 mm, 0.75 mm, and 1.15 mm, respectively, were implanted in an anthropomorphic phantom. Radiographic visibility was confirmed using a kilovoltage x‐ray imaging system, and dose perturbations were predicted from Monte Carlo simulations and confirmed by measurements. Monte Carlo simulations indicated that size of dose perturbation depended on marker size, orientation, and distance from the beam's end of range. Specifically, the perturbation of proton dose for the lateral‐opposed‐pair treatment technique was 31% for large markers and 23% for medium markers in a typical oblique orientation. Results for perpendicular and parallel orientations were respectively lower and higher. Consequently, these markers are not well suited for use in patients receiving proton therapy for prostate cancer. Dose perturbation was not observed for the small markers, but these markers were deemed too fragile for transrectal implantation in the prostate.PACS number: 87.53.Pb

Size Effects in Mechanical Deformation and Fracture of Cantilevered Silicon Nanowires

Elastic modulus and fracture strength of vertically aligned Si [111] nanowires (ø = 100-700 nm) in an as-grown state have been measured using a new, multipoint bending protocol in an atomic force microscope. All wires showed linear elastic behavior, spring constants which scale with (length)(3), and brittle failure at the wire-substrate junction. The "effective" Young's modulus increased slightly (100 --> 160-180 GPa) as wire diameter decreased, but fracture strength increased by 2-3 orders of magnitude (MPa --> GPa). These results indicate that vapor-liquid-solid grown wires are relatively free of extended volume defects and that fracture strength is likely controlled by twinning and interfacial effects at the wire foot. Small wires (100 nm) grown with a colloidal catalyst were the best performers with high modulus ( approximately 180 GPa) and fracture stress >1 GPa.

Refraction Indices of Non-Uniform Systems from the First Principles

ABSTRACTA novel, first-principle theoretical approach and synergetic computational methods designed to predict electronic and magnetic transport properties of strongly spatially inhomogeneous systems, including small quantum dots and wires (QDs and QWs, respectively), and molecules, have been developed recently. This approach is based on a many-body quantum theoretical formalism - a projection operator method due to Zubarev and Tserkovnikov (ZT) - formulated in terms of the equilibrium, two-time temperature Green functions (or TTGFs). There are several significant advantages of this approach, as compared to traditional non-equilibrium two-time thermodynamic and field-theoretical Green's function (NGF) methods that are currently used to study electronic and magnetic transport properties of strongly spatially inhomogeneous systems. In particular, the TTGFs are directly related to experimentally assessable microscopic charge, spin and microcurrent densities.In the work reported here the TTGF-based approach has been used to derive a fundamental, yet tractable expression for the space-time Fourier transform of the tensor of quasi-local refraction indices (TRI) from the first principles. The TTGFs necessary to predict TRI can be calculated using quantum statistical mechanical means, modeling and simulations, and experimental data. Applications of the theoretical predictions for TRI open new prospects in materials design. In particular, the derived theoretical expression for TRI can be used to guide experimental synthesis of structured materials and systems with both direction- and position-dependent indices of refraction in desirable frequency ranges.

Electronic and Magnetic Properties of Small Co-O Quantum Wires

AbstractElectronic and magnetic properties of small Co-O atomic clusters (“quantum wires”) have been studied in the framework of the Hartree-Fock (HF) method. The obtained results indicate that non-stoichiometric Co - O molecules with more than two O atoms possess at least one remarkably stretchable O-O bond that may facilitate significant re-construction of such molecules to larger structures. This re-construction may result in energetically favorable spin re-alignment in “antiferromagnetic” HF singlet Co-O molecules converting the singlets to larger “ferromagnetic” HF triplets and pentets. Such a spin re-alignment is energetically favorable, and may happen at the antiferromagnet-ferromagnet interface in “critical” core (Co) – shell (CoO) exchange-biased nanoclusters, providing for minimization of the surface energy, and leading to a loss of exchange bias. The obtained results are in agreement with available experimental and computational data.

Delivering More Than Charge

CHEMISTRY A small platinum or carbon wire inserted into a solution environment can yield substantial chemical insight through charge exchange with local compounds. One limitation of such electrode sensing, however, is that only electrons can be shuttled back and forth. Chen et al. have engineered a microfluidic apparatus, which they term a chemistrode, that can deliver or remove complex molecules from specific sites with a spatial resolution of 15 μm. The system relies on a fluorocarbon carrier fluid that pulls well-separated aqueous droplets through a channel that briefly opens to contact a substrate surface for molecular exchange. Analytes absorbed from the substrate can then be subjected to a wide range of traditional spectrometric probing techniques. The authors demonstrate the device through a measurement of insulin secretion kinetics by murine islet of Langerhans cells. — JSY Proc. Natl. Acad. Sci. U.S.A. 105 , 16843 (2008).

Electromagnetic Wave Absorbing Material Based on Magnetic Microwires

In this paper, we present an experimental investigation related to an electromagnetic radiation absorber for a preselected frequency range between 5 and 20 Ghz. It consists in an absorbent sheet located such that, in the absorber use position, said electromagnetic radiation falls on the absorbent sheet. The absorbent sheet is made up of a dielectric material containing amorphous magnetic microwires of which magnetic permeability in the preselected frequency range has an imaginary part mu which is at least 100 times greater than that of the corresponding real part mu'. The small wire diameter, compared to the skin depth, guarantees the full penetration of the electromagnetic fields inside the microwires. In order to elucidate the contribution of electrical resonance to the absorption, absorbent sheets of dielectric material containing copper microwires have been also characterized at high frequency.