Quantum interference device made by DNA templating of superconducting nanowires.
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The application of single molecules as templates for nanodevices is a promising direction for nanotechnology. We used a pair of suspended DNA molecules as templates for superconducting two-nanowire devices. Because the resulting wires are very thin, comparable to the DNA molecules themselves, they are susceptible to thermal fluctuations typical for one-dimensional superconductors and exhibit a nonzero resistance over a broad temperature range. We observed resistance oscillations in these two-nanowire structures that are different from the usual Little-Parks oscillations. Here, we provide a quantitative explanation for the observed quantum interference phenomenon, which takes into account strong phase gradients created in the leads by the applied magnetic field. (+info)
The mid-term efficacy and safety of a permanent nitinol IVC filter(TrapEase).
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OBJECTIVE: 1) To evaluate the mid-term efficacy and safety of a permanent nitinol inferior vena cava (IVC) filter; 2) to evaluate filter effectiveness, filter stability and caval occlusion. MATERIALS AND METHODS: A prospective evaluation of the TrapEase IVC filter was performed on 42 patients (eight men, 34 women) ranging in age from 22 to 78 years (mean age 66 years). All patients were ill with a high risk of pulmonary embolism (PE). Indications for filter placement were: 1) deep vein thrombosis with recurrent thromboembolism; 2) and/or free-floating thrombus with contraindication to anticoagulation; and 3) complications in achieving adequate anticoagulation. Follow-up evaluations (mean: 15.4 months, range: 2 to 28 months) were performed at 6- and 12-month intervals after the procedure and included clinical histories, chart reviews, plain film, Doppler ultrasounds, and contrasted abdominal CT scans. RESULTS: In follow-up evaluations, the data analysis revealed no cases of symptomatic PE. There were no cases of filter migration, insertion site thrombosis, filter fracture, or vessel wall perforation. During the study, there was one case of filter thrombosis; early symptomatic thrombosis that was successfully treated in the hospital. Of the 42 subjects, eight died. These deaths were not related to the filter device or the implantation procedure, but to the underlying disease. CONCLUSION: This study demonstrates that the TrapEase permanent IVC filter is a safe and an effective device with low complication rates and is best used in patients with thromboembolic disease with a high risk of PE. (+info)
The electrochemical behaviour of various non-precious Ni and Co based alloys in artificial saliva.
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Five non-precious Ni-Co based alloys were analyzed with respect to their corrosion behaviour. The correlation between the amount of the elements Cr, Mo, V and the corrosion behaviour, expressed by the PREN (pitting resistance equivalent number) index in the case of the allied steels, was extended for Ni-Cr and Co-Cr dental alloys characterization. Open circuit potential, corrosion current densities, as a measure of the corrosion rate, and main parameters of the corrosion process were evaluated from linear and cyclic polarization curves, for five Ni-Cr or Co-Cr alloys in an Afnor type artificial saliva. The maintenance times of the alloy in the corrosive medium influence the corrosion rate; the corrosion current values decrease with the maintenance time due to their passivation in solution. The microscopic analysis of the alloy surfaces shows that this passivation in solution does not modify the corrosion type. The alloys with PREN +info)
Steps toward the percutaneous replacement of atrioventricular valves an experimental study.
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OBJECTIVES: The goal of this study was to develop a device for percutaneous replacement of the tricuspid valve in animals. BACKGROUND: Percutaneous valve replacement has recently been introduced, and early clinical experience has been reported. To date, this technique is limited to the replacement of pulmonary and aortic valves in selected patients. METHODS: A newly designed nitinol stent, forming two large disks separated by a cylinder with a diameter of 18 mm, was specially designed for the purpose of this study. An 18-mm bovine valve was mounted in the central part of the stent, and a polytetrafluoroethylene membrane was sutured onto the ventricular disk. Eight ewes were equally divided into two groups (group 1, acute study; group 2, killed at one month). RESULTS: Seven of eight devices were successfully delivered in the desired position. In one animal, the device was trapped in tricuspid cordae, leading to its incomplete opening. A significant paravalvular leak was noticed in one animal of group 2. Mean right atrial pressure increased from 5 to 7 mm Hg and did not change during the follow-up. At autopsy, examination confirmed the good position of devices in successfully implanted animals. CONCLUSIONS: Implantation of a semi-lunar valve in the tricuspid position is possible in ewes through a transcatheter approach. A disk-based nitinol stent is needed to allow valve implantation in the atrioventricular position. These studies open new perspectives into tricuspid as well as mitral valve replacement. (+info)
Hysteroscopic permanent tubal sterilization using a nitinol-dacron intratubal device without anaesthesia in the outpatient setting: procedure feasibility and effectiveness.
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BACKGROUND: Hysteroscopic permanent tubal sterilization has recently been introduced, resulting in a non-invasive, safe and effective technique. The aim of this study was to assess the feasibility of outpatient hysteroscopic tubal sterilization using a nitinol-dacron intratubal device without anaesthesia and to assess patient procedure compliance. MATERIALS AND METHODS: We untertook a prospective study of 36 consecutive cases of outpatient hysteroscopic tubal sterilization using a nitinol-dacron intratubal device without anaesthesia. Tubal sterilization was performed by placing the device with the aid of a 5.2-mm continuous-flow operative hysteroscope. At the end of the procedure women were asked to rate the pain experienced on a visual analogue scale (VAS) (0, no discomfort to 100, severe discomfort). Successful device placement was assessed after 3 months by hysterosalpingography and diagnostic hysteroscopy. RESULTS: Successful bilateral placement was obtained in 32 patients (88.9%); in one (2.8%) the placement was monolateral; and in three (8.3%) the procedure failed. Mean operating time was 8.6 +/- 5.3 min. A mean VAS of 36.1 +/- 23.9 was recorded. CONCLUSIONS: The nitinol-dacron intratubal device is safe, appears to be effective long-term, is non-invasive and can be used in the outpatient setting without anaesthesia. Low-level discomfort was experienced by the patients. Limitations of its use include that it is not effective immediately, it is irreversible, it requires special equipment and training, and it is difficult to use in cases of uterine anomalies. We conclude that this method may be offered to all woman asking for permanent tubal sterilization, particularly those who refuse or have contraindications for anaesthesia. (+info)
Initial clinical experience with a new self-expanding nitinol stent for the treatment of intracranial cerebral aneurysms: the Cordis Enterprise stent.
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BACKGROUND AND PURPOSE: A new neurovascular microstent, the Cordis Enterprise stent, composed of nitinol, with a closed cell design, was specifically developed for the treatment of wide-necked intracranial cerebral aneurysms. The purpose of this study was to evaluate the safety, feasibility, and initial clinical results of using this device in patients. METHODS: In clinical evaluation, five patients ranging in age from 54 to 71 years were electively treated. The smallest aneurysm measured 3.3 x 2.9 mm, and the largest aneurysm measured 10.6 x 8.5 mm (neck and height measurements). RESULTS: All five cases (100%) were technically successful without complications. In each case, the stent was accurately placed in the desired location, immediately followed by coil embolization to the desired degree of occlusion with a satisfactory result. The poststent and coil-occlusion angiogram demonstrated excellent blood flow across the stent, with satisfactory positioning of the coils within the aneurysm in all cases (100%). No patient suffered any clinical or neurologic complications, and all were discharged 1-3 days postprocedure, in stable condition with no new neurologic deficits. CONCLUSION: In early clinical studies, the Cordis Enterprise stent performed well. The stent was able to be well visualized, deployed easily, could be repositioned if needed, and was accurately placed without technical difficulties. The closed cell design allowed all coils to be placed within the aneurysm and remain outside the flow of the parent artery. No periprocedural complications were encountered. (+info)
Ni-Ti memory alloy clamp plate for fracture of short tubular bone.
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The clamp shape implant has a special memorial function. It consists of one main rod and 3 or 4 pairs of curved short arms located at both sides of the rod. Each pair of arms rolls into a circle, which can embrace 2/3 of the circumference of the fractured bone shaft, thus fixing fragmental bones at multiple points more securely without any limitation to the motion of adjacent joints. Therefore, clamp implant is especially useful for comminuted fracture of the short tubular bone, which is difficult to fix by other methods. (+info)
Microbiologically influenced corrosion: looking to the future.
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This review discusses the state-of-the-art of research into biocorrosion and the biofouling of metals and alloys of industrial usage. The key concepts needed to understand the main effects of microorganisms on metal decay, and current trends in monitoring and control strategies to mitigate the deleterious effects of biocorrosion and biofouling are also described. Several relevant cases of biocorrosion studied by our research group are provided as examples: (i) biocorrosion of aluminum and its alloys by fungal contaminants of jet fuels; (ii) sulfate-reducing bacteria (SRB)-induced corrosion of steel; (iii) biocorrosion and biofouling interactions in the marine environment; (iv) monitoring strategies for assessing biocorrosion in industrial water systems; (v) microbial inhibition of corrosion; (vi) use and limitations of electrochemical techniques for evaluating biocorrosion effects. Future prospects in the field are described with respect to the potential of innovative techniques in microscopy (environmental scanning electron microscopy, confocal scanning laser microscopy, atomic force microscopy), new spectroscopic techniques for the study of corrosion products and biofilms (energy dispersion X-ray analysis, X-ray photoelectron spectroscopy, electron microprobe analysis) and electrochemistry (electrochemical impedance spectroscopy, electrochemical noise analysis). (+info)