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A betting vice president bettingsports lotterysweepor office pool if done pool betting definition work, is a form of gamblingspecifically a variant of parimutuel betting influenced by lotterieswhere gamblers pay a fixed price into a pool from which taxes and a house "take" or "vig" are removedand then make a selection on an outcome, usually related to sport. In an informal game, the vig is usually quite small or non-existent. The pool is evenly divided between those that have made the correct selection. There are no odds involved; each winner's payoff depends simply on the number of gamblers and the number of winners. True parimutuel bettingwhich was historically referred to as pool betting, involves both odds calculations and variable wager amounts.

Eric bettinger angiologue strasbourg

Total energy for closure was determined. Suitable laser parameters pulse duration, power per pulse, distance between tip of the laser fiber and prosthesis were assessed. Specific laser-prosthesis interactions were recorded. Especially the diode laser was found to be an appropriate energy source.

Energy should be transmitted through a laser fiber equipollent to the prosthesis band diameter. Specific deformation characteristics due to the zonal prosthesis composition have to be taken into account. Lasers Surg. A year-old woman presented with a large femoropopliteal aneurysm. A covered nitinol stent was implanted successfully and complete exclusion of the aneurysm was achieved. At follow-up 5 months later the stent was still patent and the patient was free of symptoms.

However, moderate stenosis was seen at the proximal end of the stent. This dissertation was motivated by the alarming number of biomedical device failures reported in the literature, coupled with the growing trend towards the use of Nitinol for endovascular stents. The research is aimed at addressing two of the primary failure modes in Nitinol endovascular stents: fatigue-crack growth and overload fracture.

The small dimensions of stents, coupled with their complex geometries and variability among manufacturers, make it virtually impossible to determine generic material constants associated with specific devices. Instead, the research utilizes a hybrid of standard test techniques fracture mechanics and x-ray micro-diffraction and custom-designed testing apparatus for the determination of the fracture properties of specimens that are suitable representations of self-expanding Nitinol stents.

Specifically, the role of texture crystallographic alignment of atoms and the austenite-to-martensite phase transformation on the propagation of cracks in Nitinol was evaluated under simulated body conditions and over a multitude of stresses and strains. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents. Laser cutting is the dominant process for manufacturing Nitinol stents.

Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone HAZ , and recast layer. To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed.

The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters. Fu, C. Use of nitinol self-expandable stents in 26 dogs with tracheal collapse. A study was designed to describe a novel approach to the treatment of tracheal collapse TC in dogs using self-expandable nitinol stents.

Medical records were reviewed retrospectively for 26 client owned dogs in which nitinol stents were deployed. The entire length of trachea was supported independently of the extent of TC. Two overlapping stents were used instead of one in cases where one stent was not spanning the entire trachea adequately. The diameter of the cranial radiolucent portion of trachea, just behind the cricoid cartilage, was measured as a specific landmark to select the appropriate size of the stent.

Two self-expandable nitinol stents were inserted in 9 of 26 dogs; the trachea in the rest of the cases was supported with only one stent. A follow up tracheoscopy was performed in 10 of 26 cases with recurrent clinical signs. Secondary tracheal stenosis in these cases was caused by stent fracture, granuloma or excessive stent shortening. Additional stents were placed successfully to expand the stenotic lumen.

A support of the entire trachea may decrease risk of nitinol fracture at the end of the implant. Multiscale electrochemical analysis of the corrosion of titanium and nitinol for implant applications. Izquierdo, J. SECM was operated in feedback and redox competition modes as a function of potential applied to the substrate. The kinetics of the electron transfer rate on both materials was characterized by mathematical modelling of the Z-approach curves monitored under feedback conditions.

The rate constant values greatly depended on the characteristics of the passive layers formed over the metals under potentiostatic control. A more insulating film was found on nitinol when biased at low polarizations, resulting in smaller tip current increments during tip approach to the investigated surface under positive feedback and competition operation modes. However, at higher anodic polarizations, nitinol passive layers experience breakdown, and therefore tip current values reflect the release of metal cations from the biomaterial surface.

Materials and Methods. Eighteen patients underwent PTA of focal atherosclerotic occlusive disease of distal abdominal aorta. Two symptomatic occlusions and 16 stenoses in 10 male and 8 female patients mean age No complications associated with the procedure occurred.

During the Endovascular treatment primary self-expandable nitinol stent placement of focal atherosclerotic lesions of distal abdominal aorta is a safe method with excellent primary technical and clinical success rates and favourable Long term results. In that evaluation, most specimens were exposed for a year. Nitinol 60 was added to the test program in High-resolution 3D X-ray imaging of intracranial nitinol stents.

Snoeren, Rudolph M. To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out. Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations.

We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values. Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom.

We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2. We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values.

Experimental results compare well with imaging simulations. Treatment of malignant gastroduodenal obstruction with using a newly designed complex expandable nitinol stent: initial experiences. We wanted to evaluate the usefulness of a new type of a complex expandable nitinol stent that was designed to reduce the stent's propensity to migration during the treatment of malignant gastroduodenal obstructions. Two types of expandable nitinol stent were constructed by weaving a single thread of 0.

Both ends of the covered stent were fabricated by coaxially inserting the covered stent into the tubular uncovered stent and then attaching the two stents together with using nylon monofilament. Clinical improvement was assessed by comparing the food intake capacity before and after the procedure. The complications were investigated during the follow up period. Stent placement was successful in all the patients. After stent placement, the symptoms improved in all but one patient. Despite the stent migration, the patient was able to resume a soft diet.

Six patients developed recurrent symptoms of obstruction with tumor overgrowth at a mean of days after the procedure; all the patients underwent coaxial placement of an additional stent with good results. One patient showed recurrence of obstruction due to tumor in-growth, and this was treated by placement of a second stent.

Two patients with stent placement in the duodenum suffered from jaundice 26 days and 65 days, respectively, after their procedures. Placement of the newly designed complex expandable nitinol stent seems to be effective for the palliative treatment of malignant gastroduodenal obstructions. The new stent also seems to help overcome the.

Management of stent dislodgment in coarctoplasty of aorta with three overlapping self-expandable nitinol stents. We describe a case of native coarctation of aorta managed with three self-expandable nitinol stents. After balloon pre-dilation, the first and second stents were dislodged. The coarcted area was successfully treated with the third stent overlapped with the previous stents.

During follow up 30 months , the patient was free of complications. It seems that implantation of multiple overlapping self-expandable stents in aortic coarctation patients, if needed, is safe and possible. Full Text Available This paper presents nano-impact low cycle fatigue behavior of as-deposited amorphous nitinol TiNi thin film deposited on Si wafer. The nitinol film was 3. Each nano-impact test was conducted for a total of fatigue cycles.

Depth sensing approach was adapted to understand the mechanisms of film failure. Based on the depth-time data and surface observations of films using atomic force microscope, it is concluded that the shape of the indenter test probe is critical in inducing the localized indentation stress and film failure. The measurement technique proposed in this paper can be used to optimize the design of nitinol thin films. Transcatheter aortic value implantation with self-expandable nitinol valved stent: an experimental study in sheep.

Objective: to determine the feasibility and safety of transcatheter aortic valve implantation with domestic self-expandable nitinol valved stent in experimental sheep. Methods: A fresh pig pericardium was cross-linked with a 0. Ten healthy sheep of Under general anesthesia, the device was delivered through catheter into the native aortic valve of the sheep via the femoral artery or abdominal aorta. The animals were followed up for three months.

Results: Six devices were successfully delivered at the desired position in six sheep with no occurrence of complications. Angiographic and hemodynamic studies confirmed that the stents were fixed at correct position with competent valve function immediately and 90 days after the procedure. Technical failure or fatal complications occurred in the remaining four sheep.

Conclusion: Implantation of a domestic nitinol self-expandable stent at the aortic valve position through a transcatheter approach is feasible in experimental sheep. Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease PAD due to its minimally invasive nature and associated reductions in short-term morbidity and mortality.

The mechanical properties of the superelastic Nitinol alloy have played a major role in the explosion of peripheral artery stenting, with modern stents demonstrating reasonable resilience and durability. Yet in the superficial femoral and popliteal arteries, even the newest generation Nitinol stents continue to demonstrate clinical outcomes that leave significant room for improvement.

Restenosis and progression of native arterial disease often lead to recurrence of symptoms and reinterventions that increase morbidity and health care expenditures. One of the main factors thought to be associated with stent failure in the femoropopliteal artery FPA is the unique and highly dynamic mechanical environment of the lower limb.

Clinical and experimental data demonstrate that the FPA undergoes significant deformations with limb flexion. It is hypothesized that the inability of many existing stent designs to conform to these deformations likely plays a role in reconstruction failure, as repetitive movements of the leg and thigh combine with mechanical mismatch between the artery and the stent and result in mechanical damage to both the artery and the stent.

In this review we will identify challenges and provide a mechanical perspective of FPA stenting, and then discuss current research directions with promise to provide a better understanding of Nitinol , specific features of stent design, and improved characterization of the biomechanical environment of the FPA to facilitate development of better stents for patients with PAD. Nitinol is used as a metallic biomaterial in medical devices due to its shape memory and pseudoelastic properties.

The clinical performance of nitinol depends on factors which include the surface finish, the local environment, and the mechanical loads to which the device is subjected. Preclinical evaluations of device durability are performed with fatigue tests while electrochemical characterization methods such as ASTM F are employed to evaluate corrosion susceptibility by determining the rest potential and breakdown potential. However, it is well established that the rest potential of a metal surface can vary with the local environment.

Very little is known regarding the influence of voltage on fatigue life of nitinol. In this study, we developed a fatigue testing method in which an electrochemical system was integrated with a rotary bend wire fatigue tester. Samples were fatigued at various strain levels at electropotentials anodic and cathodic to the rest potential to determine if it could influence fatigue life.

Wires at potentials negative to the rest potential had a significantly higher number of cycles to fracture than wires held at potentials above the breakdown potential. For wires for which no potential was applied, they had fatigue life similar to wires at negative potentials. Purpose: To evaluate the immediate and long-term results in ten patients with malignant biliary obstruction using a polyurethane-covered, self-expandable nitinol stent.

Methods: A nitinol stent, fully covered with high-elasticity polyurethane, with an unconstrained diameter of 10 mm and a total length of mm, was placed transhepatically under fluoroscopic guidance in ten patients. The length of the biliary obstruction varied between mm. The follow-up examination included a clinical assessment, serum bilirubin measurement, and ultrasound examinations at one-month intervals in all patients. Results: Initial stent deployment was successful in eight patients.

Two patients experienced proximal migration,which was solved by insertion of two, uncovered Wallstents. One patient had the stent removed after two weeks because of severe nausea and vomiting. One patient had delayed migration of the covered stent after 40 weeks. The follow-up duration was weeks Mean: Seven patients died weeks and three patients survived weeks.

The bilirubin measurements in all patients had significantly decreased one week after stent insertion. The levels of amylase and lipase had did not increase after stent insertion. Conclusions: Apolyurethane-covered, self-expandable nitinol stent can be used effectively and safely in the treatment of malignant biliary obstruction. The preliminary results are favorable, but there is a need for further large studies to determine both long-term survival and patency.

Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease PAD due to its minimally invasive nature and associated reductions in short-termmorbidity and mortality. We wanted to determine the technical and clinical efficacy of using a PTFE-covered self-expandable nitinol stent for the palliative treatment of malignant biliary obstruction. Thirty-seven patients with common bile duct strictures caused by malignant disease were treated by placing a total of 37 nitinol PTFE stents.

These stents were covered with PTFE with the exception of the last 5 mm at each end; the stent had an unconstrained diameter of 10 mm and a total length of 50 80 mm. The patient survival rate and stent patency rate were calculated by performing Kaplan-Meier survival analysis. The bilirubin, serum amylase and lipase levels before and after stent placement were measured and then compared using a Wilcoxon signed-rank test. The average follow-up duration was Placement was successful in all cases.

There were no immediate complications. Three patients demonstrated stent sludge occlusion that required PTBD percutaneous transhepatic biliary drainage irrigation. Two patients experienced delayed stent migration with stone formation at 7 and 27 weeks of follow-up, respectively.

The bilirubin levels were significantly reduced one week after stent insertion p nitinol stent is safe to use with acceptable complication rates. This study is similar to the previous studies with regard to comparing the patency rates and survival rates. Self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty.

The feasibility of self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty was assessed. Options for lower limb percutaneous revascularization are limited, especially for complex vessel obstruction. Until recently, no self-expanding stent for the use in the infragenicular arteries was available. This is the first report of the results for 18 consecutive patients who received 4F sheath compatible self-expanding nitinol stents following unsuccessful PTA or early restenosis.

Stent implantation was feasible in all cases. No complications occurred. At follow-up, the patency could be assessed in 14 stented arteries. The use of self-expanding nitinol stents in tibioperoneal and popliteal arteries is a safe and feasible option for the treatment of unsuccessful PTA.

The 6-months patency is high. A patient suffering from esophagorespiratory fistula after bougienage of a benign stricture at the site of the anastomosis between a jejunal interposition and the esophagus was referred for interventional treatment. A prototype nitinol stent centrally covered with Dacron was implanted under regional anesthesia and fluoroscopic guidance. The self-expanding prosthesis dilated the stenosis completely and closed the fistula, with consequent improvement in respiratory and nutritional status and thus the general quality of life.

The patient was able to eat and drink normally until death 3 months later due to progression of his underlying malignant disease. Specimens of 60 NiTi were heat treated in air at degC for 30 min or 2 hr, then quench cooled by one of seven different methods. The microstructure and hardness of this material was examined post heat treatment. The results indicated that the quench method had little effect on the resulting hardness and microstructure of 60 NiTi.

To retrospectively review the patency of endovascular interventions with nitinol stent placement for symptomatic central venous occlusions in hemodialysis patients. A retrospective review of all patients who underwent endovascular interventions for dysfunctional hemodialysis grafts and fistulas was performed from April to August The study group consisted of 3 men and 3 women with a mean age of Of these 6 patients, 1 had a graft and 5 had fistulas in the left arm.

The primary indication for nitinol stent placement was technical failure of angioplasty following successful traversal of occluded central venous segments. Patency was assessed from repeat fistulograms and central venograms performed when patients redeveloped symptoms or were referred for access dysfunction determined by the ultrasound dilution technique. No patients were lost to follow-up.

In 1 patient, incorrect stent positioning resulted in partial migration to the superior vena cava requiring restenting to prevent further migration. Over the follow-up period, 2 patients underwent repeat intervention with angioplasty alone. Primary patency was Mean primary patency was No complications related to recanalization of the occluded central venous segments were observed. Our initial experience has demonstrated that use of nitinol stents for central venous occlusion in hemodialysis patients is.

Surface modification and fatigue behavior of nitinol for load bearing implants. Musculoskeletal disorders are recognized amongst the most significant human health problems that exist today. Even though considerable research and development has gone towards understanding musculoskeletal disorders, there is still lack of bone replacement materials that are appropriate for restoring lost structures and functions, particularly for load-bearing applications.

Many materials on the market today, such as titanium and stainless steel, suffer from significantly higher modulus than natural bone and low bioactivity leading to stress shielding and implant loosening over longer time use. Nitinol NiTi is an equiatomic intermetallic compound of nickel and titanium whose unique biomechanical and biological properties contributed to its increasing use as a biomaterial.

An innovative method for creating dense and porous net shape NiTi alloy parts has been developed to improve biological properties while maintaining comparable or better mechanical properties than commercial materials that are currently in use. Porous implants are known to promote cell adhesion and have a low elastic modulus, a combination that can significantly increase the life of an implant. However, porosity can significantly reduce the fatigue life of an implant, and very little work has been reported on the fatigue behavior of bulk porous metals, specifically on porous nitinol alloy.

In cyclic compression loading, plastic strain increased with increasing porosity and it was evident that maximum strain was achieved during the first cycles and remained constant throughout the remaining loading. When subjected. Predictive parameters for fistula healing using this technique remain uncertain. Comparison of visibility for four self-expanding nitinol bare stents in vitro.

Background Sufficient radiopacity of stents is a prerequisite for safe interventions and minimization of the radiation dose for the patient and the interventionist. Modern nitinol stents are considered less radiopaque compared to formerly used stents. Purpose To evaluate the objective detection rate ODR and the subjective radiopacity score SRS of four self-expanding nitinol stents with their markers on a phantom human pelvis.

Stents were placed on a phantom human pelvis and images of the stents were taken in four different positions right and left lumbosacral joint and near the right and left limbus acetabuli using the following modes: spotfilm, pulsed fluoroscopy 4, 7.

Dose area products DAPs were assessed. On phase transformation models for thermo-mechanically coupled response of Nitinol. Fully coupled thermomechanical models for Nitinol at the grain level are developed in this work to capture the inter-dependence between deformation and temperature under non-isothermal conditions. The martensite transformation equations are solved using a novel algorithm which imposes all relevant constraints on the volume fractions.

The numerical implementation of the resulting models within the finite element method is effected by the monolithic solution of the momentum and energy equations. Validation of the models is achieved by means of thin-tube experiments at different strain rates. Polyorethaoe-covered nitinol strecker stents as primary palliative treatment of malignant biliary obstruction.

Purpose: To evaluate the clinical efficacy of the polyure-thane-covered Nitinol Strecker stent in the treatment of patients with malignant biliary obstruction. Methods: Twenty-three covered stents produced by us were placed in 18 patients with malignant biliary obstruction. Resulrs: The mean patency period of the Stents was Adequate biliary drainage over 50 weeks or until death was achieved in 17 of 18 patients Late cholangitis was observed in two patients whose stents bridged the ampulla of Vater.

Other late severe complications were not encountered. Conclusion: Although more study is necessary, our results suggest the clinical efficacy of our covered Nitinol Strecker stent in the management of obstructive jaundice caused by malignant diseases.

Nitinol alloys have been used in various biological applications due to their superior properties. In this study, a bipolar pulsed current electrodeposition technique was applied to produce a hydroxyapatite HA film on the Nitinol alloy. Also, the protection performance of the coating was evaluated on both abraded and thermochemically modified alloy. According to obtained data, reducing the electrocrystallization rate by the pulse deposition technique can promote HA formation on both abraded and modified substrates.

Based on scanning electron microscopy and high-resolution transmission electron microscopy data, the HA coatings revealed a flake-like morphology and each flake was composed of nano-crystalline grains. Atomic force microscopy images revealed that flakes on the abraded substrate were smaller in size than that of the modified alloy.

Comparing the corrosion resistance of the bare substrates revealed that the modified alloy has a higher corrosion resistance than the abraded alloy and the modified surface is well passivized during anodic polarization in Ringer's solution. However, this condition is reversed after the deposition of HA film. It seems that because of the lower crystallization sites on the abraded alloy, the produced HA film is denser and more protective against the corrosive mediums as compared to the coating on the modified alloy.

Although the HA coating can improve the bioactivity of both substrates, the resulted film on the oxidized alloy is porous and deteriorates the implant permanence in the vicinity of body fluids. Sesterhenn, Andreas M. We assessed the results of self-expanding metallic stent insertion into benign proximal tracheal stenosis in patients not appropriate or unfit for surgical repair.

Proximal benign tracheal stenoses had occurred in 11 patients 7 men, 4 women, mean age Fourteen self-expanding nitinol stents were placed in the patients under general anesthesia with endoscopical and fluoroscopical guidance. Stent insertion was successful in all cases and led to immediate relief of the morphological and functional airway obstruction. No immediate complications were noted.

During the mean follow-up period of Both complications were successfully treated with additional stent insertion in one case and laser resection of granulomas in the other. Self-expanding nitinol stents should be considered for the treatment of benign proximal tracheal obstruction in selected patients for whom surgical repair is contraindicated. Biomedical engineering in design and application of nitinol stents with shape memory effect.

Our studies in the field of endosurgery in collaboration with the physicians of the National Research Center of Surgery of the Academy of Medical Sciences are carried out beginning in These studies laid the foundation for the new direction of X-ray surgery--X-ray Nitinol stenting of vessels and tubular structures. X-ray nitinol stents are unique self-fixing shells based on the shape memory effect and superelasticity of nickel-titanium alloys self- reconstructed under human body temperature.

Applied for stenting of arteries in cases of stenosis etc. The purpose of stenting is restoration of the shape of artery or tubular structure by a cylinder frame formation. The especially elaborated original method of stenting allows to avoid the traditional surgical operation, i. The stent to be implanted is transported into the affected zone through the puncture under the X-ray control.

Clinical applications of X-ray endovascular stenting has been started in March During this period nearly operations on stenting have been performed on femoral, iliac, brachio-cephalic, subclavian arteries, bile ducts, tracheas, digestive tract and cervical canal uterus. Wireless implantable chip with integrated nitinol -based pump for radio-controlled local drug delivery. We demonstrate an active, implantable drug delivery device embedded with a microfluidic pump that is driven by a radio-controlled actuator for temporal drug delivery.

The rectangular-shaped spiral-coil actuator based on nitinol , a biocompatible shape-memory alloy, is developed to perform cantilever-like actuation for pumping operation. The nitinol -coil actuator itself forms a passive MHz resonant circuit that serves as a self-heat source activated via RF power transfer to enable frequency-selective actuation and pumping.

Experimental wireless operation of fabricated prototypes shows successful release of test agents from the devices placed in liquid and excited by radiating tuned RF fields with an output power of 1. The thermal behavior of the activated device is also reported in detail. This proof-of-concept prototype validates the effectiveness of wireless RF pumping for fully controlled, long-lasting drug delivery, a key step towards enabling patient-tailored, targeted local drug delivery through highly miniaturized implants.

Nitinol laser cutting: microstructure and functional properties of femtosecond and continuous wave laser processing. Thermal processing can affect the properties of smart materials, and the correct selection of the best manufacturing technology is fundamental for producing high tech smart devices, containing embedded functional properties. In this work cutting of thin superelastic Nitinol plates using a femtosecond fs and continuous wave CW laser was studied. Diamond shaped elements were cut to characterize the kerf qualitative features; microstructural analysis of the cross sections allowed identification of thermal damage characteristics introduced into the material during the laser processes.

A thermally undamaged microstructure was observed for fs laser cutting, while CW was seen to be characterized by a large heat-affected zone. Functional properties were investigated by differential scanning calorimetry and tensile testing of laser cut microelements and of the reference material. It was seen that the martensitic transformation behavior of Nitinol is not affected by fs regime, while cw cutting provokes an effect equivalent to a high temperature thermal treatment in the material surrounding the cutting kerf, degradating the material properties.

Finally, tensile testing indicated that superelastic performances were guaranteed by fs regime, while strong reduction of the recoverable strain was detected in the CW processed sample. Dysphagia with malignant stricture of esophagogastric junction: treatment with self-expandable nitinol stent.

To evaluate the effectiveness, patency and safety of a self-expandable nitinol stent for palliative treatment of malignant stricture of gastroesophageal junction. An esophageal stent was inserted in five consecutive patients with malignant stricture of esophagogastric junction. Histologically, four cases were adenocarcinoma, and one was squamous cell carcinoma. The location and severity of stricture were evaluated with gastrografin just before stent insertion. In one patient with past subtotal gastrectomy, esophagography revealed fistulous fract at stricture site.

No technical failure or procedural complications occurred, and improvement of dysphagia was noted in all patients soon after stent insertion. On follow up esophagograms performed 3 to 7 days after stent insertion, all stents were completely expanded and unchanged in positions. In one patient with fistulous connection at stricture site, esophagogram immediately after the procedure revealed complete occlusion of the fistula. Three patients died within 4, 7 and 8 consecutive months after stent insertion.

Two patients are alive maintaining adequate body weight and passing most diet. Seft-expandable nitinol stent with it's good longitudinal flexibility and efficient radial force was effective in the palliative treatment of dysphagia in patient with malignant stricture at esophagogastric junction. Effect of biologically active coating on biocompatibility of Nitinol devices designed for the closure of intra-atrial communications.

Anti-thrombogenicity and rapid endothelialisation are prerequisites for the use of closure devices of intra-atrial communications in order to reduce the risk of cerebral embolism. The purpose of this study was therefore to assess the effect of bioactive coatings on biocompatibility of Nitinol coils. Self-expanding nanoplatinum-coated nitinol devices for atrial septal defect and patent ductus arteriosus closure: a swine model. Our purpose was to evaluate self-expanding nanoplatinum-coated nitinol devices for transcatheter closure of atrial septal defects and patent ductus arteriosus in a swine model.

The devices were braided from platinum-activated nitinol wires and filled with polyester to enhance thrombogenicity. The platinum activation of the nitinol wires was carried out with the help of Nanofusion technology. The coating of platinum covers the exposed surface of the nitinol wires and prevents the release of nickel into the blood stream after the implantation of the device but does not affect its shape memory, which makes the device self-expanding after it is loaded from the catheter.

Atrial septal defects were created in 12 piglets by balloon dilation of the patent foramen ovale. The size of the device was selected on the basis of the diameter of the balloon and the size of the defect, measured by transthoracic echocardiography.

The devices were successfully deployed in all 12 piglets under fluoroscopic study. Transthoracic color Doppler echocardiograms showed complete closure of the atrial septal defect within 15 minutes of device implantation. Twelve patent ductus arteriosus closure devices were deployed in the right or left subclavian arteries in 10 piglets.

Angiograms showed complete occlusion of the subclavian arteries within a few minutes of device deployment. In the atrial septal defect cases, the autopsy findings showed complete organizing fibrin thrombus formation and complete neo-endothelialization on the outer surface of the devices within one week and six weeks of implantation, respectively.

The use of self-expanding nanoplatinum-coated nitinol devices for the transcatheter closure of atrial septal defects and patent ductus arteriosus is feasible. The excellent occlusion result and complete neo-endothelialization of the devices in the swine model is an indication of the potential of these devices in human application. Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity. The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported.

The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree.

The highest amount of silver was deposited when the coated electrode was prepolarised at Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. A year-old woman presenting with gastrointestinal bleeding hematocrit The arterial tear supplying the pseudoaneurysm was excluded using a 5.

Within 6 days of the procedure, a gradual increase in hemoglobin levels and a prompt improvement in the clinical condition were observed. Multislice CT angiograms performed immediately, 5 days, 30 days and 3 months after the procedure confirmed the complete exclusion of the pseudoaneurysm. Study of critical dependence of stable phases in Nitinol on heat treatment using electrical resistivity probe. The stabilisation of austenitic, rhombohedral and martensitic phases is shown to critically depend on the temperatures of heat treatment by the analysis of temperature dependence of electrical resistivity in heating and cooling parts of the cycle.

Characteristic values of electrical resistivity of the stable phases are determined. The R-phase has been found to form continuously with increasing heat-treatment temperature starting from room temperature and to suddenly disappear beyond heat-treatment at K. The observed presence or absence of R-phase is confirmed by heat capacity measurements as a function of temperature. Mechanical stability of the diamond-like carbon film on nitinol vascular stents under cyclic loading.

The mechanical stability of diamond-like carbon DLC films coated on nitinol vascular stents was investigated under cyclic loading condition by employing a stent crimping system. DLC films were coated on the vascular stent of a three dimensional structure by using a hybrid ion beam system with rotating jig.

The cracking or delamination of the DLC coating occurred dominantly near the hinge connecting the V-shaped segments of the stent where the maximum strain was induced by a cyclic loading of contraction and extension. However the failures were significantly suppressed as the amorphous Si a-Si buffer layer thickness increased. Interfacial adhesion strength was estimated from the spalled crack size in the DLC coating for various values of the a-Si buffer layer thickness.

A year-old man, who had undergone right hepatectomy extended to the caudate lobe with terminolateral Roux-en-Y left hepatojejunostomy for a Klatskin tumor, developed bilioptysis 3 weeks postoperatively due to bronchobiliary fistula.

Percutaneous transhepatic cholangiography revealed a non-dilated biliary system with contrast medium extravasation to the right subphrenic space through a resected anomalous right posterior segmental duct. After initial unsuccessful internal-external biliary drainage, the fistula was sealed with a VIATORR covered self-expanding nitinol stent-graft placed with its distal uncovered region in the hepatojejunal anastomosis and the proximal ePTFE-lined region in the left hepatic duct. A month follow-up revealed no recurrence of bilioptysis and confirmed the complete exclusion of the bronchobiliary fistula.

Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration. Gotman, Irena, E-mail: gotman technion. The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy Nitinol scaffolds in a critical-size defect CSD model. New Zealand white rabbits received bone defect in right radius and were divided in four groups randomly.

In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: i as produced, ii loaded with bone marrow aspirate BMA , and iii biomimetically CaP-coated. The animals were sacrificed after 12 weeks.

The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images. Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1—1.

The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects. The data revealed that the hydroxyapatite coating is composed of one-dimensional nano sized flakes and the polymer coating is uniformly covered the sublayer.

Also, High resolution TEM studies on the hydroxyapatite samples revealed that each flake contains nano-crystalline grains with a diameter of about 15 nm. However, the flakes were weak against applied external forces because of their ultra-fine thickness. It was shown that, the polymer coating has a great influence on toughening the hydroxyapatite coating. SEM studies on the samples revealed that the beneath layer of hydroxyapatite appears after 72 h without any visible change in morphology.

It seems that, application of a biodegradable polymer film on the nanostructured hydroxyapatite coating is a good way to support the coating during implantation processes. Pan- nitinol occluder and special delivery device for closure of patent ductus arteriosus: a canine-model feasibility study. The aim of this study was to evaluate a new type of occluder for patent ductus arteriosus.

Patent ductus arteriosus was established in a canine model by anastomosing a length of autologous jugular vein to the descending aorta and the left pulmonary artery in an end-to-side fashion. Transcatheter closure of each patent ductus arteriosus was performed on 10 dogs, which were then monitored for as long as 6 months with aortography, echocardiography, and histologic evaluation.

Transcatheter closure with use of the novel pan- nitinol device was successful in all canine models. Postoperative echocardiography showed that the location and shape of the occluders were normal, without any residual shunting. Further histologic evaluation confirmed that the occluder surface was completely endothelialized 3 months after implantation. Transcatheter patent ductus arteriosus closure with the pan- nitinol occluder can be performed safely and successfully in a canine model and shows good biological compatibility and low mortality rates.

Safety and efficacy of nano lamellar TiN coatings on nitinol atrial septal defect occluders in vivo. Atrial septal defect ASD occlusion devices made of nickel—titanium NiTi have a major shortcoming in that they release nickel into the body. Nano lamellar titanium—nitrogen TiN coatings were formed on the surfaces of the occluders.

The safety and efficacy of the modified NiTi occluders were evaluated in animal model. Fibrous capsules formed on the surfaces of the devices. Gradual endothelialization took place through the attachment of endothelial progenitor cells from the blood and the migration of endothelial cells from adjacent endocardium. The neo-endocardium formed more quickly in the coated group than in the uncoated group, as indicated by the evaluation of the six month study group.

After TiN coating, there was no significant difference in endothelial cell cycle. TiN coating significantly reduced the release of nickel in both in vivo and in vitro indicating an improved biocompatibility of the nitinol ASD occluders. Superior and modified ASD occluders may provide a good choice for people with nickel allergies after sFDA registration, which is expected in one to two years. Attempts have been made to investigate the effect of slip time of nitinol artificial esophagus for forming neo-esophageal stenosis after replacement of a thoracic esophagus with nitinol artificial esophagus in 20 experimental pigs.

The pigs whose slip time was less than 90 days postoperatively had severe dysphagia Bown's III immediately after they were fed, and the dysphagia aggravated gradually later on Bown's III-IV. The relationship between nitinol artificial esophagus slip time and neo-esophageal stenosis showed a positive correlation. After replacement of a thoracic esophagus with nitinol artificial esophagus, the artificial esophageal slip time not only affected the original diameter of the neo-esophagus immediately, but also affected the neo-esophageal scar stricture forming process later on.

The narrowing of neo-esophagus is caused by overgrowth of scar tissue. But there is the positive correlation between artificial esophagus slip time and neo-esophageal stenosis, so this can be a way of overcoming neo-esophageal stenosis by delaying slip time of artificial esophagus.

Carbon fibre and nitinol needles for MRI-guided interventions: First in vitro and in vivo application. Thomas, Christoph, E-mail: Christoph. Objective: To assess the artefact properties of a MR-compatible carbon fibre needle with a nitinol mandrin in vitro and to report first clinical experiences.

Artefact width, needle intensity contrast and needle tip location errors were assessed. In vivo, lumbar periradicular corticosteroid injections and one sclerotherapy were performed with carbon fibre needles 10 procedures and with titanium alloy needles 2 procedures. The artefact sizes and contrasts were measured. Results: In vitro, artefact diameters of the carbon fibre needle ranged from 3.

Needle tip location errors of Decreasing angles to the main field lead to smaller artefacts. Zhang, Zhi xiong, E-mail: Top Methods: Treatment results of 70 patients with degenerative lumbar scoliosis aged 40 to 82 were analyzed. In all cases pedicle screws and nitinol rods with a diameter of 5. Thirty patients underwent fixation at L1-S1 and 40 patients underwent fixation at L1-L5. Spinal fusion was not performed. The minimum follow-up period for all patients was 2. For the control group, consisting of 72 patients, pedicle fixation with titanium rods and interbody fusion in the lumbosacral region were performed.

The analysis of X-ray and CT-scans revealed a single patient with implant instability, two patients with bone resorption around the screws and one patient with rod fractures. Functional radiography 2. There were no problems at the adjacent levels. Conclusions: The use of nitinol rods in spinal deformity surgery is promising. This technology is an alternative to rigid fixation.

Continued gathering of clinical data and its further evaluation is necessary. Self-expandable polytetrafluoroethylene PTFE -covered nitinol stent for the palliative treatment of malignant biliary obstruction. We wanted to determine the technical and clinical efficacy of placing a self-expandable PTFE-covered nitinol stent for the management of inoperable malignant biliary obstruction. Thirty six patients with inoperable malignant biliary obstructions were treated by placement of self-expandable PTFE-covered nitinol stents S and G Biotech Corporation, Seongnam, Korea.

Clinical evaluation was done with assessment of the serum bilirubin and alkaline phosphatase levels, which were measured before and after stent placement within 1 week, at 1 month and at 3 months. The patient survival rate and stent patency rate were calculated with performing Kaplan-Meier survival analysis.

Successful stent placement was achieved in all the patients without procedure-related complication. Pancreatitis as an early complication occurred in two cases. The serum bilirubin and alkaline phosphatase levels were significantly decreased after the procedure. During the follow-up, recurrent obstructive jaundice occurred in six cases; stent migration occurred in four cases and tumor overgrowth occurred in two cases.

Self-expandable PTFE-covered nitinol stent placement seems to be technically feasible and effective for the palliative treatment of malignant biliary obstruction. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. Bleeding after expandable nitinol stent placement in patients with esophageal and upper gastrointestinal obstruction: incidence, management, and predictors. Placement of self-expandable nitinol stents is useful for the treatment of esophageal and upper gastrointestinal GI obstruction.

However, complications such as stent migration, tumor overgrowth, and bleeding occur. Although stent migration and tumor overgrowth are well documented in previous studies, the occurrence of bleeding has not been fully evaluated. To evaluate the incidence, management strategies, and predictors of bleeding after placement of self-expandable nitinol stents in patients with esophageal and upper GI obstruction. We retrospectively reviewed the medical records and results of computed tomography and endoscopy of consecutive patients with esophageal and upper GI obstructions who underwent fluoroscopically guided stent placement.

Bleeding occurred in 25 of 1. Bleeding is a rare complication after placement of expandable nitinol stents in patients with esophageal and upper GI obstruction, but patients with early bleeding may require embolization for control. Care must be exercised on placing stents in patients who have received prior radiotherapy or chemotherapy.

Transcatheter closure of membranous ventricular septal defects with home-made nitinol occluder. Changhai Hospital, Dept. Objective: To evaluate the feasibility and efficacy of transcatheter perimembranous ventricular septal defects VSD occlusion with home-made nitinol occluder. Methods: Transcatheter closure was attempted in patients with perimembranous VSD. The diameter of VSD measured by echocardiography was 3 to 15 mm, mean 4.

The angiographic diameter of the VSD was 3 to 6 mm, mean 3. A F delivery sheath was advanced across the perimembranous VSD over a wire from femoral vein to deploy the occluder with the guidance of echocardiography and fluoroscopy. The device diameter selected was from 4 to 20 mm, mean 6. The aminoacetonitrile is an interesting compound because it was detected in SgrB2, hence could be a precursor of the smallest amino acid molecule, glycine, in astrophysical environments.

Infrared spectroscopy and mass spectroscopy are then used to identify the aminoacetonitrile formation. During the ice warming, this reaction leads to the formation of poly methylene-imine polymers. In a methanimine excess, long polymers are formed. Therefore, these results demonstrate that aminoacetonitrile can be formed through the second step of the Strecker synthesis in astrophysical-like conditions.

Passive base isolation with superelastic nitinol SMA helical springs. Seismic isolation of structures such as multi-story buildings, nuclear reactors, bridges, and liquid storage tanks should be designed to preserve structural integrity. By implementing seismic isolation technology, the deformation of superstructures can be dramatically reduced, consequently helping to protect their safety as well.

In this paper, an innovative type of passive base isolation system, which is mainly composed of superelastic nitinol SMA helical springs, is developed. In order to verify the effectiveness of the proposed system, a two-story experimental steel frame model is constructed, and two superelastic SMA helical springs are thermo-mechanically built in the laboratory.

To describe the nonlinear mechanical properties of the superelastic SMA helical springs under reciprocating load, a phenomenological model is presented in terms of a series of tensile tests. Afterwards, a numerical model of the two-story frame with the suggested isolation system is set up to simulate the response of the isolated frame subjected to an earthquake. Both the experimental and the numerical simulation results indicate that the proposed base isolation system can remarkably suppress structural vibrations and has improved isolation effects when compared with a steel spring isolation system.

Due to the capabilities of energy dissipation as well as fully re-centering, it is very applicable to utilize the suggested isolation system in base isolated structures to resist earthquakes. Nitinol stents in the treatment of benign proximal tracheal stenosis or tracheomalacia. Nitinol stents have been used in the treatment of benign tracheal stenosis. A retrospective review of five patients treated at Stobhill Hospital over the last six and a half years is presented.

Age at presentation ranged from 17 to 76 years. The minimum follow-up period was 23 months and the maximum was 78 months. All our patients were successfully decannulated, with none requiring recannulation. Four patients developed granulation tissue related to the stent at intervals ranging from three weeks to 41 months post stenting. Topical mitomycin C application has been useful after resection of granulations using the carbon dioxide CO2 laser.

Stent migration occurred in one patient three weeks after insertion. Nitinol stents are easy to insert and effective in the treatment of tracheal stenosis, but can have associated morbidity. Their use should be considered carefully, as insertion should be regarded as permanent. Publications reporting experience and outcome with the use of Nitinol stents in the trachea are reviewed. To evaluate the patency and the freedom of target lesion revascularization of the 4-French Pulsar self-expandable SE nitinol stent for the treatment of long femoropopliteal occlusive disease in a two-center, prospective, all-comers registry with a follow-up period of 12 months.

This registry enrolled 36 patients with symptomatic femoropopliteal long lesions for recanalization and implantation of the 4-French Pulsar SE nitinol stent. Routine follow-up examination including duplex ultrasound was performed after 6 and 12 months. Primary patency was defined as no binary restenosis on duplex ultrasound Peak systolic velocitiy ration PSVR Pulsar SE nitinol stent for endovascular intervention of femoropopliteal disease with a mean lesion length of Diabetes and renal insufficiency had no negative impact on the patency rate.

Laser shape setting of superelastic nitinol wires: Functional properties and microstructure. Shape setting is one of the most important steps in the production route of Nitinol Shape Memory Alloys SMAs , as it can fix the functional properties, such as the shape memory effect and the superelasticity SE.

In this work, a laser beam was adopted for performing straight shape setting on commercially available austenitic Nitinol thin wires. The laser beam, at different power levels, was moved along the wire length for inducing the functional performances. Calorimetric, pseudo-elastic and microstructural features of the laser annealed wires were studied through differential scanning calorimetry, tensile testing and high energy X-ray diffraction, respectively.

It can be stated that the laser technology can induce SE in thin Nitinol wires: the wire performances can be modulated in function of the laser power and improved functional properties can be obtained. Simon nitinol vena cava filters: effectiveness and complications. Purpose: The aim of this retrospective analysis was to evaluate the clinical safety and effectiveness of the simon nitinol inferior vena cava filter SNF for prevention of pulmonary embolism. Patients and Methods: patients 63 male, 54 female; aged Patient reports were retrospectively analysed for complications during and after implantation and deep venous thrombosis DVT and pulmonary embolism before and after implantation.

Helical-CT with contrast media and plain abdominal radiography were performed on 35 patients, helical-CT alone on two patients. We checked the position and configuration of the SNF and looked for a perforation of the filter legs through the wall of the inferior vena cava IVC.

The IVC and deep pelvic veins were analysed for patency. There was no significant increase in thrombosis of the deep pelvic veins and the IVC after implantation. Pulmonary re-embolism PE was documented in 9 out of patients 7. One out of the 35 examined patients 2.

Dislocation of the SNF more than 10 mm occurred in one out of 35 patients 2. We found no occlusion of the IVC. Laser-assisted fixation of a nitinol stapes prosthesis. Otosclerosis is an inner ear bone disease characterized by fixation of the stapes and consequently progressive hearing loss.

One treatment option is the surgical replacement of the stapes by a prosthesis. When so called "smart materials" like nitinol are used, prosthesis fixation can be performed using a laser without manual crimping on the incus. However, specific laser-prosthesis interactions have not been described yet.

Total energy for closure was determined. Suitable laser parameters pulse duration, power per pulse, distance between tip of the laser fiber and prosthesis were assessed. Specific laser-prosthesis interactions were recorded. Especially the diode laser was found to be an appropriate energy source. Energy should be transmitted through a laser fiber equipollent to the prosthesis band diameter.

Specific deformation characteristics due to the zonal prosthesis composition have to be taken into account. Lasers Surg. A year-old woman presented with a large femoropopliteal aneurysm. A covered nitinol stent was implanted successfully and complete exclusion of the aneurysm was achieved. At follow-up 5 months later the stent was still patent and the patient was free of symptoms. However, moderate stenosis was seen at the proximal end of the stent. This dissertation was motivated by the alarming number of biomedical device failures reported in the literature, coupled with the growing trend towards the use of Nitinol for endovascular stents.

The research is aimed at addressing two of the primary failure modes in Nitinol endovascular stents: fatigue-crack growth and overload fracture. The small dimensions of stents, coupled with their complex geometries and variability among manufacturers, make it virtually impossible to determine generic material constants associated with specific devices. Instead, the research utilizes a hybrid of standard test techniques fracture mechanics and x-ray micro-diffraction and custom-designed testing apparatus for the determination of the fracture properties of specimens that are suitable representations of self-expanding Nitinol stents.

Specifically, the role of texture crystallographic alignment of atoms and the austenite-to-martensite phase transformation on the propagation of cracks in Nitinol was evaluated under simulated body conditions and over a multitude of stresses and strains. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents.

Laser cutting is the dominant process for manufacturing Nitinol stents. Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone HAZ , and recast layer.

To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed. The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters.

Fu, C. Use of nitinol self-expandable stents in 26 dogs with tracheal collapse. A study was designed to describe a novel approach to the treatment of tracheal collapse TC in dogs using self-expandable nitinol stents. Medical records were reviewed retrospectively for 26 client owned dogs in which nitinol stents were deployed. The entire length of trachea was supported independently of the extent of TC.

Two overlapping stents were used instead of one in cases where one stent was not spanning the entire trachea adequately. The diameter of the cranial radiolucent portion of trachea, just behind the cricoid cartilage, was measured as a specific landmark to select the appropriate size of the stent.

Two self-expandable nitinol stents were inserted in 9 of 26 dogs; the trachea in the rest of the cases was supported with only one stent. A follow up tracheoscopy was performed in 10 of 26 cases with recurrent clinical signs. Secondary tracheal stenosis in these cases was caused by stent fracture, granuloma or excessive stent shortening.

Additional stents were placed successfully to expand the stenotic lumen. A support of the entire trachea may decrease risk of nitinol fracture at the end of the implant. Multiscale electrochemical analysis of the corrosion of titanium and nitinol for implant applications. Izquierdo, J. SECM was operated in feedback and redox competition modes as a function of potential applied to the substrate. The kinetics of the electron transfer rate on both materials was characterized by mathematical modelling of the Z-approach curves monitored under feedback conditions.

The rate constant values greatly depended on the characteristics of the passive layers formed over the metals under potentiostatic control. A more insulating film was found on nitinol when biased at low polarizations, resulting in smaller tip current increments during tip approach to the investigated surface under positive feedback and competition operation modes.

However, at higher anodic polarizations, nitinol passive layers experience breakdown, and therefore tip current values reflect the release of metal cations from the biomaterial surface. Materials and Methods. Eighteen patients underwent PTA of focal atherosclerotic occlusive disease of distal abdominal aorta. Two symptomatic occlusions and 16 stenoses in 10 male and 8 female patients mean age No complications associated with the procedure occurred.

During the Endovascular treatment primary self-expandable nitinol stent placement of focal atherosclerotic lesions of distal abdominal aorta is a safe method with excellent primary technical and clinical success rates and favourable Long term results. In that evaluation, most specimens were exposed for a year. Nitinol 60 was added to the test program in High-resolution 3D X-ray imaging of intracranial nitinol stents.

Snoeren, Rudolph M. To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out. Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations.

We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values.

Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom. We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2.

We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values.

Experimental results compare well with imaging simulations. Treatment of malignant gastroduodenal obstruction with using a newly designed complex expandable nitinol stent: initial experiences. We wanted to evaluate the usefulness of a new type of a complex expandable nitinol stent that was designed to reduce the stent's propensity to migration during the treatment of malignant gastroduodenal obstructions.

Two types of expandable nitinol stent were constructed by weaving a single thread of 0. Both ends of the covered stent were fabricated by coaxially inserting the covered stent into the tubular uncovered stent and then attaching the two stents together with using nylon monofilament. Clinical improvement was assessed by comparing the food intake capacity before and after the procedure.

The complications were investigated during the follow up period. Stent placement was successful in all the patients. After stent placement, the symptoms improved in all but one patient. Despite the stent migration, the patient was able to resume a soft diet. Six patients developed recurrent symptoms of obstruction with tumor overgrowth at a mean of days after the procedure; all the patients underwent coaxial placement of an additional stent with good results.

One patient showed recurrence of obstruction due to tumor in-growth, and this was treated by placement of a second stent. Two patients with stent placement in the duodenum suffered from jaundice 26 days and 65 days, respectively, after their procedures. Placement of the newly designed complex expandable nitinol stent seems to be effective for the palliative treatment of malignant gastroduodenal obstructions.

The new stent also seems to help overcome the. Management of stent dislodgment in coarctoplasty of aorta with three overlapping self-expandable nitinol stents. We describe a case of native coarctation of aorta managed with three self-expandable nitinol stents.

After balloon pre-dilation, the first and second stents were dislodged. The coarcted area was successfully treated with the third stent overlapped with the previous stents. During follow up 30 months , the patient was free of complications. It seems that implantation of multiple overlapping self-expandable stents in aortic coarctation patients, if needed, is safe and possible.

Full Text Available This paper presents nano-impact low cycle fatigue behavior of as-deposited amorphous nitinol TiNi thin film deposited on Si wafer. The nitinol film was 3. Each nano-impact test was conducted for a total of fatigue cycles. Depth sensing approach was adapted to understand the mechanisms of film failure. Based on the depth-time data and surface observations of films using atomic force microscope, it is concluded that the shape of the indenter test probe is critical in inducing the localized indentation stress and film failure.

The measurement technique proposed in this paper can be used to optimize the design of nitinol thin films. Transcatheter aortic value implantation with self-expandable nitinol valved stent: an experimental study in sheep. Objective: to determine the feasibility and safety of transcatheter aortic valve implantation with domestic self-expandable nitinol valved stent in experimental sheep.

Methods: A fresh pig pericardium was cross-linked with a 0. Ten healthy sheep of Under general anesthesia, the device was delivered through catheter into the native aortic valve of the sheep via the femoral artery or abdominal aorta.

The animals were followed up for three months. Results: Six devices were successfully delivered at the desired position in six sheep with no occurrence of complications. Angiographic and hemodynamic studies confirmed that the stents were fixed at correct position with competent valve function immediately and 90 days after the procedure.

Technical failure or fatal complications occurred in the remaining four sheep. Conclusion: Implantation of a domestic nitinol self-expandable stent at the aortic valve position through a transcatheter approach is feasible in experimental sheep. Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease PAD due to its minimally invasive nature and associated reductions in short-term morbidity and mortality. The mechanical properties of the superelastic Nitinol alloy have played a major role in the explosion of peripheral artery stenting, with modern stents demonstrating reasonable resilience and durability.

Yet in the superficial femoral and popliteal arteries, even the newest generation Nitinol stents continue to demonstrate clinical outcomes that leave significant room for improvement. Restenosis and progression of native arterial disease often lead to recurrence of symptoms and reinterventions that increase morbidity and health care expenditures. One of the main factors thought to be associated with stent failure in the femoropopliteal artery FPA is the unique and highly dynamic mechanical environment of the lower limb.

Clinical and experimental data demonstrate that the FPA undergoes significant deformations with limb flexion. It is hypothesized that the inability of many existing stent designs to conform to these deformations likely plays a role in reconstruction failure, as repetitive movements of the leg and thigh combine with mechanical mismatch between the artery and the stent and result in mechanical damage to both the artery and the stent.

In this review we will identify challenges and provide a mechanical perspective of FPA stenting, and then discuss current research directions with promise to provide a better understanding of Nitinol , specific features of stent design, and improved characterization of the biomechanical environment of the FPA to facilitate development of better stents for patients with PAD. Nitinol is used as a metallic biomaterial in medical devices due to its shape memory and pseudoelastic properties.

The clinical performance of nitinol depends on factors which include the surface finish, the local environment, and the mechanical loads to which the device is subjected. Preclinical evaluations of device durability are performed with fatigue tests while electrochemical characterization methods such as ASTM F are employed to evaluate corrosion susceptibility by determining the rest potential and breakdown potential.

However, it is well established that the rest potential of a metal surface can vary with the local environment. Very little is known regarding the influence of voltage on fatigue life of nitinol. In this study, we developed a fatigue testing method in which an electrochemical system was integrated with a rotary bend wire fatigue tester.

Samples were fatigued at various strain levels at electropotentials anodic and cathodic to the rest potential to determine if it could influence fatigue life. Wires at potentials negative to the rest potential had a significantly higher number of cycles to fracture than wires held at potentials above the breakdown potential. For wires for which no potential was applied, they had fatigue life similar to wires at negative potentials. Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease PAD due to its minimally invasive nature and associated reductions in short-termmorbidity and mortality.

We wanted to determine the technical and clinical efficacy of using a PTFE-covered self-expandable nitinol stent for the palliative treatment of malignant biliary obstruction. Thirty-seven patients with common bile duct strictures caused by malignant disease were treated by placing a total of 37 nitinol PTFE stents.

These stents were covered with PTFE with the exception of the last 5 mm at each end; the stent had an unconstrained diameter of 10 mm and a total length of 50 80 mm. The patient survival rate and stent patency rate were calculated by performing Kaplan-Meier survival analysis.

The bilirubin, serum amylase and lipase levels before and after stent placement were measured and then compared using a Wilcoxon signed-rank test. The average follow-up duration was Placement was successful in all cases. There were no immediate complications. Three patients demonstrated stent sludge occlusion that required PTBD percutaneous transhepatic biliary drainage irrigation. Two patients experienced delayed stent migration with stone formation at 7 and 27 weeks of follow-up, respectively.

The bilirubin levels were significantly reduced one week after stent insertion p nitinol stent is safe to use with acceptable complication rates. This study is similar to the previous studies with regard to comparing the patency rates and survival rates.

Self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty. The feasibility of self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty was assessed. Options for lower limb percutaneous revascularization are limited, especially for complex vessel obstruction.

Until recently, no self-expanding stent for the use in the infragenicular arteries was available. This is the first report of the results for 18 consecutive patients who received 4F sheath compatible self-expanding nitinol stents following unsuccessful PTA or early restenosis.

Stent implantation was feasible in all cases. No complications occurred. At follow-up, the patency could be assessed in 14 stented arteries. The use of self-expanding nitinol stents in tibioperoneal and popliteal arteries is a safe and feasible option for the treatment of unsuccessful PTA. The 6-months patency is high. A patient suffering from esophagorespiratory fistula after bougienage of a benign stricture at the site of the anastomosis between a jejunal interposition and the esophagus was referred for interventional treatment.

A prototype nitinol stent centrally covered with Dacron was implanted under regional anesthesia and fluoroscopic guidance. The self-expanding prosthesis dilated the stenosis completely and closed the fistula, with consequent improvement in respiratory and nutritional status and thus the general quality of life.

The patient was able to eat and drink normally until death 3 months later due to progression of his underlying malignant disease. Specimens of 60 NiTi were heat treated in air at degC for 30 min or 2 hr, then quench cooled by one of seven different methods. The microstructure and hardness of this material was examined post heat treatment. The results indicated that the quench method had little effect on the resulting hardness and microstructure of 60 NiTi. To retrospectively review the patency of endovascular interventions with nitinol stent placement for symptomatic central venous occlusions in hemodialysis patients.

A retrospective review of all patients who underwent endovascular interventions for dysfunctional hemodialysis grafts and fistulas was performed from April to August The study group consisted of 3 men and 3 women with a mean age of Of these 6 patients, 1 had a graft and 5 had fistulas in the left arm. The primary indication for nitinol stent placement was technical failure of angioplasty following successful traversal of occluded central venous segments.

Patency was assessed from repeat fistulograms and central venograms performed when patients redeveloped symptoms or were referred for access dysfunction determined by the ultrasound dilution technique. No patients were lost to follow-up. In 1 patient, incorrect stent positioning resulted in partial migration to the superior vena cava requiring restenting to prevent further migration.

Over the follow-up period, 2 patients underwent repeat intervention with angioplasty alone. Primary patency was Mean primary patency was No complications related to recanalization of the occluded central venous segments were observed. Our initial experience has demonstrated that use of nitinol stents for central venous occlusion in hemodialysis patients is.

Surface modification and fatigue behavior of nitinol for load bearing implants. Musculoskeletal disorders are recognized amongst the most significant human health problems that exist today. Even though considerable research and development has gone towards understanding musculoskeletal disorders, there is still lack of bone replacement materials that are appropriate for restoring lost structures and functions, particularly for load-bearing applications.

Many materials on the market today, such as titanium and stainless steel, suffer from significantly higher modulus than natural bone and low bioactivity leading to stress shielding and implant loosening over longer time use.

Nitinol NiTi is an equiatomic intermetallic compound of nickel and titanium whose unique biomechanical and biological properties contributed to its increasing use as a biomaterial. An innovative method for creating dense and porous net shape NiTi alloy parts has been developed to improve biological properties while maintaining comparable or better mechanical properties than commercial materials that are currently in use.

Porous implants are known to promote cell adhesion and have a low elastic modulus, a combination that can significantly increase the life of an implant. However, porosity can significantly reduce the fatigue life of an implant, and very little work has been reported on the fatigue behavior of bulk porous metals, specifically on porous nitinol alloy.

In cyclic compression loading, plastic strain increased with increasing porosity and it was evident that maximum strain was achieved during the first cycles and remained constant throughout the remaining loading. When subjected. Predictive parameters for fistula healing using this technique remain uncertain.

Comparison of visibility for four self-expanding nitinol bare stents in vitro. Background Sufficient radiopacity of stents is a prerequisite for safe interventions and minimization of the radiation dose for the patient and the interventionist. Modern nitinol stents are considered less radiopaque compared to formerly used stents. Purpose To evaluate the objective detection rate ODR and the subjective radiopacity score SRS of four self-expanding nitinol stents with their markers on a phantom human pelvis.

Stents were placed on a phantom human pelvis and images of the stents were taken in four different positions right and left lumbosacral joint and near the right and left limbus acetabuli using the following modes: spotfilm, pulsed fluoroscopy 4, 7. Dose area products DAPs were assessed. On phase transformation models for thermo-mechanically coupled response of Nitinol.

Fully coupled thermomechanical models for Nitinol at the grain level are developed in this work to capture the inter-dependence between deformation and temperature under non-isothermal conditions. The martensite transformation equations are solved using a novel algorithm which imposes all relevant constraints on the volume fractions. The numerical implementation of the resulting models within the finite element method is effected by the monolithic solution of the momentum and energy equations.

Validation of the models is achieved by means of thin-tube experiments at different strain rates. Nitinol alloys have been used in various biological applications due to their superior properties. In this study, a bipolar pulsed current electrodeposition technique was applied to produce a hydroxyapatite HA film on the Nitinol alloy. Also, the protection performance of the coating was evaluated on both abraded and thermochemically modified alloy. According to obtained data, reducing the electrocrystallization rate by the pulse deposition technique can promote HA formation on both abraded and modified substrates.

Based on scanning electron microscopy and high-resolution transmission electron microscopy data, the HA coatings revealed a flake-like morphology and each flake was composed of nano-crystalline grains. Atomic force microscopy images revealed that flakes on the abraded substrate were smaller in size than that of the modified alloy.

Comparing the corrosion resistance of the bare substrates revealed that the modified alloy has a higher corrosion resistance than the abraded alloy and the modified surface is well passivized during anodic polarization in Ringer's solution. However, this condition is reversed after the deposition of HA film. It seems that because of the lower crystallization sites on the abraded alloy, the produced HA film is denser and more protective against the corrosive mediums as compared to the coating on the modified alloy.

Although the HA coating can improve the bioactivity of both substrates, the resulted film on the oxidized alloy is porous and deteriorates the implant permanence in the vicinity of body fluids. Sesterhenn, Andreas M. We assessed the results of self-expanding metallic stent insertion into benign proximal tracheal stenosis in patients not appropriate or unfit for surgical repair.

Proximal benign tracheal stenoses had occurred in 11 patients 7 men, 4 women, mean age Fourteen self-expanding nitinol stents were placed in the patients under general anesthesia with endoscopical and fluoroscopical guidance. Stent insertion was successful in all cases and led to immediate relief of the morphological and functional airway obstruction.

No immediate complications were noted. During the mean follow-up period of Both complications were successfully treated with additional stent insertion in one case and laser resection of granulomas in the other. Self-expanding nitinol stents should be considered for the treatment of benign proximal tracheal obstruction in selected patients for whom surgical repair is contraindicated.

Biomedical engineering in design and application of nitinol stents with shape memory effect. Our studies in the field of endosurgery in collaboration with the physicians of the National Research Center of Surgery of the Academy of Medical Sciences are carried out beginning in These studies laid the foundation for the new direction of X-ray surgery--X-ray Nitinol stenting of vessels and tubular structures.

X-ray nitinol stents are unique self-fixing shells based on the shape memory effect and superelasticity of nickel-titanium alloys self- reconstructed under human body temperature. Applied for stenting of arteries in cases of stenosis etc. The purpose of stenting is restoration of the shape of artery or tubular structure by a cylinder frame formation. The especially elaborated original method of stenting allows to avoid the traditional surgical operation, i.

The stent to be implanted is transported into the affected zone through the puncture under the X-ray control. Clinical applications of X-ray endovascular stenting has been started in March During this period nearly operations on stenting have been performed on femoral, iliac, brachio-cephalic, subclavian arteries, bile ducts, tracheas, digestive tract and cervical canal uterus.

Wireless implantable chip with integrated nitinol -based pump for radio-controlled local drug delivery. We demonstrate an active, implantable drug delivery device embedded with a microfluidic pump that is driven by a radio-controlled actuator for temporal drug delivery. The rectangular-shaped spiral-coil actuator based on nitinol , a biocompatible shape-memory alloy, is developed to perform cantilever-like actuation for pumping operation.

The nitinol -coil actuator itself forms a passive MHz resonant circuit that serves as a self-heat source activated via RF power transfer to enable frequency-selective actuation and pumping. Experimental wireless operation of fabricated prototypes shows successful release of test agents from the devices placed in liquid and excited by radiating tuned RF fields with an output power of 1.

The thermal behavior of the activated device is also reported in detail. This proof-of-concept prototype validates the effectiveness of wireless RF pumping for fully controlled, long-lasting drug delivery, a key step towards enabling patient-tailored, targeted local drug delivery through highly miniaturized implants. Nitinol laser cutting: microstructure and functional properties of femtosecond and continuous wave laser processing. Thermal processing can affect the properties of smart materials, and the correct selection of the best manufacturing technology is fundamental for producing high tech smart devices, containing embedded functional properties.

In this work cutting of thin superelastic Nitinol plates using a femtosecond fs and continuous wave CW laser was studied. Diamond shaped elements were cut to characterize the kerf qualitative features; microstructural analysis of the cross sections allowed identification of thermal damage characteristics introduced into the material during the laser processes.

A thermally undamaged microstructure was observed for fs laser cutting, while CW was seen to be characterized by a large heat-affected zone. Functional properties were investigated by differential scanning calorimetry and tensile testing of laser cut microelements and of the reference material. It was seen that the martensitic transformation behavior of Nitinol is not affected by fs regime, while cw cutting provokes an effect equivalent to a high temperature thermal treatment in the material surrounding the cutting kerf, degradating the material properties.

Finally, tensile testing indicated that superelastic performances were guaranteed by fs regime, while strong reduction of the recoverable strain was detected in the CW processed sample. Dysphagia with malignant stricture of esophagogastric junction: treatment with self-expandable nitinol stent. To evaluate the effectiveness, patency and safety of a self-expandable nitinol stent for palliative treatment of malignant stricture of gastroesophageal junction.

An esophageal stent was inserted in five consecutive patients with malignant stricture of esophagogastric junction. Histologically, four cases were adenocarcinoma, and one was squamous cell carcinoma. The location and severity of stricture were evaluated with gastrografin just before stent insertion. In one patient with past subtotal gastrectomy, esophagography revealed fistulous fract at stricture site. No technical failure or procedural complications occurred, and improvement of dysphagia was noted in all patients soon after stent insertion.

On follow up esophagograms performed 3 to 7 days after stent insertion, all stents were completely expanded and unchanged in positions. In one patient with fistulous connection at stricture site, esophagogram immediately after the procedure revealed complete occlusion of the fistula. Three patients died within 4, 7 and 8 consecutive months after stent insertion. Two patients are alive maintaining adequate body weight and passing most diet. Seft-expandable nitinol stent with it's good longitudinal flexibility and efficient radial force was effective in the palliative treatment of dysphagia in patient with malignant stricture at esophagogastric junction.

Effect of biologically active coating on biocompatibility of Nitinol devices designed for the closure of intra-atrial communications. Anti-thrombogenicity and rapid endothelialisation are prerequisites for the use of closure devices of intra-atrial communications in order to reduce the risk of cerebral embolism. The purpose of this study was therefore to assess the effect of bioactive coatings on biocompatibility of Nitinol coils.

Self-expanding nanoplatinum-coated nitinol devices for atrial septal defect and patent ductus arteriosus closure: a swine model. Our purpose was to evaluate self-expanding nanoplatinum-coated nitinol devices for transcatheter closure of atrial septal defects and patent ductus arteriosus in a swine model.

The devices were braided from platinum-activated nitinol wires and filled with polyester to enhance thrombogenicity. The platinum activation of the nitinol wires was carried out with the help of Nanofusion technology. The coating of platinum covers the exposed surface of the nitinol wires and prevents the release of nickel into the blood stream after the implantation of the device but does not affect its shape memory, which makes the device self-expanding after it is loaded from the catheter.

Atrial septal defects were created in 12 piglets by balloon dilation of the patent foramen ovale. The size of the device was selected on the basis of the diameter of the balloon and the size of the defect, measured by transthoracic echocardiography. The devices were successfully deployed in all 12 piglets under fluoroscopic study. Transthoracic color Doppler echocardiograms showed complete closure of the atrial septal defect within 15 minutes of device implantation.

Twelve patent ductus arteriosus closure devices were deployed in the right or left subclavian arteries in 10 piglets. Angiograms showed complete occlusion of the subclavian arteries within a few minutes of device deployment. In the atrial septal defect cases, the autopsy findings showed complete organizing fibrin thrombus formation and complete neo-endothelialization on the outer surface of the devices within one week and six weeks of implantation, respectively.

The use of self-expanding nanoplatinum-coated nitinol devices for the transcatheter closure of atrial septal defects and patent ductus arteriosus is feasible. The excellent occlusion result and complete neo-endothelialization of the devices in the swine model is an indication of the potential of these devices in human application.

Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity. The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree.

The highest amount of silver was deposited when the coated electrode was prepolarised at Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S.

A year-old woman presenting with gastrointestinal bleeding hematocrit The arterial tear supplying the pseudoaneurysm was excluded using a 5. Within 6 days of the procedure, a gradual increase in hemoglobin levels and a prompt improvement in the clinical condition were observed. Multislice CT angiograms performed immediately, 5 days, 30 days and 3 months after the procedure confirmed the complete exclusion of the pseudoaneurysm. Study of critical dependence of stable phases in Nitinol on heat treatment using electrical resistivity probe.

The stabilisation of austenitic, rhombohedral and martensitic phases is shown to critically depend on the temperatures of heat treatment by the analysis of temperature dependence of electrical resistivity in heating and cooling parts of the cycle. Characteristic values of electrical resistivity of the stable phases are determined. The R-phase has been found to form continuously with increasing heat-treatment temperature starting from room temperature and to suddenly disappear beyond heat-treatment at K.

The observed presence or absence of R-phase is confirmed by heat capacity measurements as a function of temperature. Mechanical stability of the diamond-like carbon film on nitinol vascular stents under cyclic loading.

The mechanical stability of diamond-like carbon DLC films coated on nitinol vascular stents was investigated under cyclic loading condition by employing a stent crimping system. DLC films were coated on the vascular stent of a three dimensional structure by using a hybrid ion beam system with rotating jig. The cracking or delamination of the DLC coating occurred dominantly near the hinge connecting the V-shaped segments of the stent where the maximum strain was induced by a cyclic loading of contraction and extension.

However the failures were significantly suppressed as the amorphous Si a-Si buffer layer thickness increased. Interfacial adhesion strength was estimated from the spalled crack size in the DLC coating for various values of the a-Si buffer layer thickness. A year-old man, who had undergone right hepatectomy extended to the caudate lobe with terminolateral Roux-en-Y left hepatojejunostomy for a Klatskin tumor, developed bilioptysis 3 weeks postoperatively due to bronchobiliary fistula.

Percutaneous transhepatic cholangiography revealed a non-dilated biliary system with contrast medium extravasation to the right subphrenic space through a resected anomalous right posterior segmental duct. After initial unsuccessful internal-external biliary drainage, the fistula was sealed with a VIATORR covered self-expanding nitinol stent-graft placed with its distal uncovered region in the hepatojejunal anastomosis and the proximal ePTFE-lined region in the left hepatic duct.

A month follow-up revealed no recurrence of bilioptysis and confirmed the complete exclusion of the bronchobiliary fistula. Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration. Gotman, Irena, E-mail: gotman technion. The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy Nitinol scaffolds in a critical-size defect CSD model.

New Zealand white rabbits received bone defect in right radius and were divided in four groups randomly. In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: i as produced, ii loaded with bone marrow aspirate BMA , and iii biomimetically CaP-coated. The animals were sacrificed after 12 weeks. The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images.

Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1—1. The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects.

The data revealed that the hydroxyapatite coating is composed of one-dimensional nano sized flakes and the polymer coating is uniformly covered the sublayer. Also, High resolution TEM studies on the hydroxyapatite samples revealed that each flake contains nano-crystalline grains with a diameter of about 15 nm.

However, the flakes were weak against applied external forces because of their ultra-fine thickness. It was shown that, the polymer coating has a great influence on toughening the hydroxyapatite coating. SEM studies on the samples revealed that the beneath layer of hydroxyapatite appears after 72 h without any visible change in morphology. It seems that, application of a biodegradable polymer film on the nanostructured hydroxyapatite coating is a good way to support the coating during implantation processes.

Pan- nitinol occluder and special delivery device for closure of patent ductus arteriosus: a canine-model feasibility study. The aim of this study was to evaluate a new type of occluder for patent ductus arteriosus. Patent ductus arteriosus was established in a canine model by anastomosing a length of autologous jugular vein to the descending aorta and the left pulmonary artery in an end-to-side fashion.

Transcatheter closure of each patent ductus arteriosus was performed on 10 dogs, which were then monitored for as long as 6 months with aortography, echocardiography, and histologic evaluation. Transcatheter closure with use of the novel pan- nitinol device was successful in all canine models. Postoperative echocardiography showed that the location and shape of the occluders were normal, without any residual shunting.

Further histologic evaluation confirmed that the occluder surface was completely endothelialized 3 months after implantation. Transcatheter patent ductus arteriosus closure with the pan- nitinol occluder can be performed safely and successfully in a canine model and shows good biological compatibility and low mortality rates. Safety and efficacy of nano lamellar TiN coatings on nitinol atrial septal defect occluders in vivo.

Atrial septal defect ASD occlusion devices made of nickel—titanium NiTi have a major shortcoming in that they release nickel into the body. Nano lamellar titanium—nitrogen TiN coatings were formed on the surfaces of the occluders. The safety and efficacy of the modified NiTi occluders were evaluated in animal model.

Fibrous capsules formed on the surfaces of the devices. Gradual endothelialization took place through the attachment of endothelial progenitor cells from the blood and the migration of endothelial cells from adjacent endocardium. The neo-endocardium formed more quickly in the coated group than in the uncoated group, as indicated by the evaluation of the six month study group. After TiN coating, there was no significant difference in endothelial cell cycle.

TiN coating significantly reduced the release of nickel in both in vivo and in vitro indicating an improved biocompatibility of the nitinol ASD occluders. Superior and modified ASD occluders may provide a good choice for people with nickel allergies after sFDA registration, which is expected in one to two years. Attempts have been made to investigate the effect of slip time of nitinol artificial esophagus for forming neo-esophageal stenosis after replacement of a thoracic esophagus with nitinol artificial esophagus in 20 experimental pigs.

The pigs whose slip time was less than 90 days postoperatively had severe dysphagia Bown's III immediately after they were fed, and the dysphagia aggravated gradually later on Bown's III-IV. The relationship between nitinol artificial esophagus slip time and neo-esophageal stenosis showed a positive correlation. After replacement of a thoracic esophagus with nitinol artificial esophagus, the artificial esophageal slip time not only affected the original diameter of the neo-esophagus immediately, but also affected the neo-esophageal scar stricture forming process later on.

The narrowing of neo-esophagus is caused by overgrowth of scar tissue. But there is the positive correlation between artificial esophagus slip time and neo-esophageal stenosis, so this can be a way of overcoming neo-esophageal stenosis by delaying slip time of artificial esophagus. Carbon fibre and nitinol needles for MRI-guided interventions: First in vitro and in vivo application.

Thomas, Christoph, E-mail: Christoph. Objective: To assess the artefact properties of a MR-compatible carbon fibre needle with a nitinol mandrin in vitro and to report first clinical experiences. Artefact width, needle intensity contrast and needle tip location errors were assessed. In vivo, lumbar periradicular corticosteroid injections and one sclerotherapy were performed with carbon fibre needles 10 procedures and with titanium alloy needles 2 procedures.

The artefact sizes and contrasts were measured. Results: In vitro, artefact diameters of the carbon fibre needle ranged from 3. Needle tip location errors of Decreasing angles to the main field lead to smaller artefacts. Zhang, Zhi xiong, E-mail: Top Methods: Treatment results of 70 patients with degenerative lumbar scoliosis aged 40 to 82 were analyzed. In all cases pedicle screws and nitinol rods with a diameter of 5.

Thirty patients underwent fixation at L1-S1 and 40 patients underwent fixation at L1-L5. Spinal fusion was not performed. The minimum follow-up period for all patients was 2.

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American Economic Journal: Economic Policy 5 2 , , Journal of Public Economics 90 , , American Economic Journal: Economic Policy 11 1 , , Addressing the needs of underprepared students in higher education does college remediation work? Long-term educational consequences of secondary school vouchers: Evidence from administrative records in Colombia J Angrist, E Bettinger, M Kremer American economic review 96 3 , , The effect of charter schools on charter students and public schools EP Bettinger Economics of Education Review 24 2 , , Do faculty serve as role models?

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Review of Economics and Statistics 94 3 , , Journal of Public Economics 91 , , American Economic Journal: Economic Policy 5 2 , , Journal of Public Economics 90 , , American Economic Journal: Economic Policy 11 1 , , Addressing the needs of underprepared students in higher education does college remediation work? Long-term educational consequences of secondary school vouchers: Evidence from administrative records in Colombia J Angrist, E Bettinger, M Kremer American economic review 96 3 , , The effect of charter schools on charter students and public schools EP Bettinger Economics of Education Review 24 2 , , Do faculty serve as role models?

Remediation at the community college: Student participation and outcomes EP Bettinger, BT Long New directions for community colleges , , Does cheaper mean better? Paying to learn: The effect of financial incentives on elementary school test scores EP Bettinger Review of Economics and Statistics 94 3 , , Fermer Privacy Overview This website uses cookies to improve your experience while you navigate through the website.

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