Search results for "TUNNEL"
showing 10 items of 576 documents
Quantum Tunneling of Magnetization under Pressure in the High-Spin Mn12 Molecular System
2004
Experimental and theoretical investigations of quantum tunneling magnetization in the high-spin cluster [Mn 1 2 O 1 2 (CH 3 COO) 1 6 (H 2 O) 4 ].2CH 3 COOH.4H 2 O under pressure have been performed. The main observation is that the blocking temperature and hysteresis width decrease under the effect of pressure. However, the position of the steps in the magnetization versus field curve does not change noticeably as pressure increases. A theoretical examination of the pressure influence on the relaxation rate and magnetization has been carried out taking into consideration the quantum tunneling effects. The qualitative agreement between theory and experiment has been achieved both at atmosphe…
Carpal tunnel release surgery: small-area variation and impact of ambulatory surgery in the autonomous region of Valencia, Spain
2013
Objective: This study aimed to analyze variability in rates of carpal tunnel release surgery among the healthcare areas of the autonomous region of Valencia, and to evaluate the contribution of ambulatory surgery and referrals to private hospitals to the variability found. Methods: We carried out a cross-sectional, population-based study, describing the rates of carpal tunnel release surgery, standardized by age and sex, among areas in the region of Valencia in 2006. The observed variation was then analyzed using small-area analysis methods. Data from hospital admissions, referrals to private hospitals, population statistics and hospital resources were used to construct standardized rates, …
Importance of surgical history in diagnosing mucopolysaccharidosis type II (Hunter syndrome): data from the Hunter Outcome Survey.
2010
Purpose: To characterize surgical histories typical of patients with mucopolysaccharidosis type II, thereby broadening understanding of the natural history of these patients and helping physicians recognize the disease. Methods: Data on surgical interventions from the Hunter Outcome Survey—a multinational, observational database of patients with mucopolysaccharidosis type II—were analyzed. The study population comprised 527 patients for whom surgical data were reported on/before July 23, 2009. Results: Surgical interventions were performed in 83.7% of the study population. Patients underwent their first operation at a median age of 2.6 years. Tympanostomies, repairs of inguinal hernias, and…
Tunnelled Haemodialysis Catheter Removal: An Underappreciated Problem, Not Always Simple and Safe
2020
Background: Optimal care of patients treated with a central tunneled catheter (CTC) as vascular access for hemodialysis requires a number of procedures. One of them is CTC removal, usually carried out using mostly the cut-down method (CDM) and the traction method (TM). The procedure seems to be simple and safe
Endoscopic carpal tunnel release: results with special consideration to possible complications.
2000
Single-portal endoscopic carpal tunnel release (Agee technique) was carried out in 148 patients. Of these, 100 were examined clinically and electrophysiologically 1 day before surgery and 1 and 3 months thereafter. Ten patients experienced transient ulnar neuropraxia and two patients complained postoperatively of intense pain in the middle and ring fingers. Three patients suffered residual symptoms. In one of these an incomplete release of the distal portion of the retinaculum flexorum was suspected and later confirmed by magnetic resonance imaging. Another patient had applied for pension due to problems associated with a vertebral fracture in addition to his carpal tunnel symptoms. A third…
Preoperative evaluation of peripheral nerve injuries: What is the place for ultrasound?
2016
OBJECTIVE The purpose of this study was to evaluate the usefulness of ultrasound in the preoperative workup of peripheral nerve lesions and illustrate how nerve ultrasonography can be integrated in routine clinical and neurophysiological evaluation and in the management of focal peripheral nerve injuries. The diagnostic role and therapeutic implications of ultrasonography for different neuropathies are described. METHODS The authors analyzed the use of ultrasound in 119 entrapment, tumoral, posttraumatic, or postsurgical nerve injuries of limbs evaluated in 108 patients during 2013 and 2014. All patients were candidates for surgery, and in all cases the evaluation included clinical examina…
Low-temperature growth of n ++-GaN by metalorganic chemical vapor deposition to achieve low-resistivity tunnel junctions on blue light emitting diodes
2018
We report on low-resistivity GaN tunnel junctions (TJ) on blue light-emitting diodes (LEDs). Si-doped n ++-GaN layers are grown by metalorganic chemical vapor deposition directly on LED epiwafers. Low growth temperature (<800 °C) was used to hinder Mg-passivation by hydrogen in the p ++-GaN top surface. This allows achieving low-resistivity TJs without the need for post-growth Mg activation. TJs are further improved by inserting a 5 nm thick In0.15Ga0.85N interlayer (IL) within the GaN TJ thanks to piezoelectric polarization induced band bending. Eventually, the impact of InGaN IL on the internal quantum efficiency of blue LEDs is discussed.
On-Surface Synthesis of Antiaromatic and Open-Shell Indeno[2,1- b ]fluorene Polymers and Their Lateral Fusion into Porous Ribbons
2019
Polycyclic hydrocarbons have received great attention due to their potential role in organic electronics and, for open-shell systems with unpaired electron densities, in spintronics and da-ta storage. However, the intrinsic instability of polyradical hydrocarbons severely limits de-tailed investigations of their electronic structure. Here, we report the on-surface synthesis of conjugated polymers consisting of indeno[2,1-b]fluorene units, which are antiaromatic and open-shell biradicaloids. The observed reaction products, which also include a non-benzenoid porous ribbon arising from lateral fusion of unprotected indeno[2,1-b]fluorene chains, have been characterized via low temperature scann…
Microstructure Design for Fast Lifetime Measurements of Magnetic Tunneling Junctions
2019
The estimation of the reliability of magnetic field sensors against failure is a critical point concerning their application for industrial purposes. Due to the physical stochastic nature of the failure events, this can only be done by means of a statistical approach which is extremely time consuming and prevents a continuous observation of the production. Here, we present a novel microstructure design for a parallel measurement of the lifetime characteristics of a sensor population. By making use of two alternative designs and the Weibull statistical distribution function, we are able to measure the lifetime characteristics of a CoFeB/MgO/CoFeB tunneling junction population. The main param…
Liquid–solid interfaces: structure and dynamics from spectroscopy and simulations
2014
Liquid–solid interfaces play an important role in a number of phenomena encountered in biological, chemical and physical processes. Surface-induced changes of the material properties are not only important for the solid support but also for the liquid itself. In particular, it is now well established that water at the interface is substantially different from bulk water, even in the proximity of apparently inert surfaces such as a simple metal. The complex chemistry at liquid–solid interfaces is typically fundamental to heterogeneous catalysis and electrochemistry, and has become especially topical in connection with the search for new materials for energy production. A quite remarkable exa…