International Nuclear Information System (INIS)

To compare clinical effectiveness of Viabil-covered stents versus uncovered metallic Wallstents, for palliation of malignant jaundice due to extrahepatic cholangiocarcinoma, 60 patients were enrolled in a prospective and randomized study. In half of the patients a bare Wallstent was used, and in the other half a Viabil biliary stent. Patients were followed up until death. Primary patency, survival, complication rates, and mean cost were calculated in both groups. Stent dysfunction occurred in 9 (30%) patients in the bare stent group after a mean period of 133.1 days and in 4 (13.3%) patients in the covered stent group after a mean of 179.5 days. The incidence of stent dysfunction was significantly lower in the covered stent group (P = 0.046). Tumor ingrowth occurred exclusively ...

UK PubMed Central (United Kingdom)

BackgroundPaclitaxel-eluting stents decrease angiographic and clinical restenosis following percutaneous coronary intervention compared to bare metal stents. TAXUS Element is a third-generation...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Self-expanding metallic stent insertion has been widely applied for the palliative treatment of malignant esophageal strictures. Although it is known as an easy, safe, and effective procedure, complications are well known and include things such as stent migration and esophageal stent occlusion caused by tumor in growth. However, metallic stent fractures have been rarely reported in the esophagus, especially for nitinol stents. We report a case of a stent fracture associated with migration in a patient with a malignant esophageal stricture near the gastroesophageal junction. It is highly probable that the stent fracture was due to chemical erosion of the stent caused by gastric juice

UK PubMed Central (United Kingdom)

BackgroundVascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundAirway complications are among the most challenging problems after lung transplantation, and Self-Expandable Metallic Stents (SEMS) are used to treat airway complications...Full Text Available

Science.gov (United States)

The mechanical properties of metal stents are important parameters in the consideration of stent design, matched to resist arterial recoil and vascular spasm. The purpose of this study was to develop a system for a standardized quantitative evaluation of the mechanical characteristics of various coronary stents. Several types of stents were compressed by external hydrostatic pressure. The stent diameter was assessed by placing a pair of small ultrasonic sono-crystals on the stent. From pressure-strain diagrams the ultimate strength and radial stiffness for each stent were determined. For all stents, except the MICRO-II and the Wiktor stent, the diameter decreased homogeneously until an ultimate compressive strength was exceeded, causing an abrupt collapse. Expanded to 3 mm, the ...

International Nuclear Information System (INIS)

Repassivation resulting from the bared metal surface is a critical process for judging whether or not material suffers from corroding or immunizing. Nickel based alloys with high chromium content were developed to increase the corrosion resistant to sulphur compounds. Active humps resulting from active dissolution of nickel were obtained by creating the bared metal surfaces in thiosulphate solutions. The lower the Cr content the higher is the dissolution rate. The passive films formed on the bared metal surface were examined by ac impedance. Results suggest the formation of multi-layers oxide which were affected by active dissolution reactions during repassivation. (author).

International Nuclear Information System (INIS)

Objective: To evaluate the clinical efficacy of multiple stents placement in the management of hilar cholangiocarcinoma, especially in the complex cases of which the hepatic ducts are invaded. Methods: Forty-five consecutive patients with hilar cholangiocarcinoma were treated with percutaneous transhepatic placement of two or three self-expandable metallic endoprostheses. The cause of hilar obstructions in these patients were all cholangiocarcinoma, including Bismuth classification type II (n 12), IIIa (n 17), IIIb (n 10), and IV (n 6). Two or 3 stents were placed in the configuration of T, Y or X over the strictures. Results: Stent placement with 2 or 3 endoprostheses was successful in all patients. All patients showed significant decrease in serum bilirubin level. The mortality rate within 30 days of stent placement was 2.2% (1/45). The mean survival and stent ...

UK PubMed Central (United Kingdom)

Photodynamic therapy (PDT) is an established endoscopic technique for ablating Barrett’s esophagus with high-grade dysplasia or early-stage intraepithelial neoplasia. The most common clinically...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In this first quarterly technical report for DOE Contract No. DE-AC22-87PC79654, a description of the background, technology, and application is provided. The design and fabrication of advanced combustion chambers were completed during this period. Initial testing on both the bare metal and refractory lined advanced chambers were initiated. The units were tested initially with gas but primarily with coal. A Pittsburgh No. 8 pulverized coal was used for these test activities. Both advanced chambers pulsed well.

Energy Technology Data Exchange (ETDEWEB)

Inferior vena cava (IVC) obstruction is a well-described clinical entity. Most IVC obstructions from malignant neoplasms are a direct result of tumor compression [Oviedo J, Cerda S. Vascular invasion by hepatocellular carcinoma. Arch Pathol Lab Med 2001;125: 454-5; Furui S, Sawada S, et al. Gianturco stent placement in malignant caval obstruction: analysis of factors for predicting the outcome. Radiology 1995;195:147-52; Fletcher WS, Lakin PC, et al. Results of treatment of inferior vena cava syndrome with expandable metallic stents. Arch Surg 1998;133:935-8]. The symptoms of IVC obstruction include progressive ascites, scrotal edema and lower body edema. These constellations of symptoms are described as IVC syndrome and are devastating to a patient with end-stage cancer. We describe a palliative therapy utilizing Luminexx nitinol self-expanding stents to treat intracaval hepatoma thrombus obstructing ...

Energy Technology Data Exchange (ETDEWEB)

In this first quarterly technical report for DOE Contract No. DE-AC22-87PC79654, a description of the background, technology, and application is provided. The design and fabrication of advanced combustion chambers were completed during this period. Initial testing on both the bare metal and refractory lined advanced chambers were initiated. The units were tested initially with gas but primarily with coal. A Pittsburgh No. 8 pulverized coal was used for these test activities. Both advanced chambers pulsed well.

Science.gov (United States)

Coronary Bifurcation Lesion

Energy Technology Data Exchange (ETDEWEB)

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 0.2mm nitinol wire in a tubular configuration: an uncovered stent 18mm in diameter and a covered stent 16mm in diameter. 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. Under fluoroscopic guidance, the stent was placed in 29 consecutive patients (20 men and 9 women, mean age: 65 years) who were suffering with malignant gastric ...

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Purpose: To evaluate MR artifacts of carotid artery stents and to optimize stent properties and sequence parameters. Material and Methods: Four carotid artery stents - Wallstent (mediloy), Precise (nitinol), ACCULINK (nitinol) and a stent prototype (nitinol) - were investigated in a flow model of the cervical vessels. The model was made of silicon tubing and a flow pump that produces realistic flow curves of the carotid artery. To investigate the effects of magnetic susceptibility and radiofrequency induced shielding artifacts, turbo spin echo and gradient echo sequences as well as CE-MRAs were measured. To improve the visualization of the stent lumen in a CE-MRA, flip angle as well as geometry and covering of the stent prototype were altered. Results: Susceptibility artifacts in stents of the carotid artery only influence the lumen ...

UK PubMed Central (United Kingdom)

AIM: To find out whether a newly designed big cup nitinol stent is suitable for treatment of patients with gastric outlet obstruction resulting from gastric cancer.METHODS: The new stent is composed...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Despite advances in polymer and drug technology, the underlying stent platform remains a key determinant of clinical outcome. A clear understanding of stent design and the differences between various stent platforms are of increasing importance for the interventional cardiologist. Reduction in stent strut thickness has been associated with improved stent deliverability, improved procedural outcome, and lower rates of subsequent restenosis. Newer-generation 316L-SS stent designs have enabled reduced strut thickness while retaining radial strength and minimizing recoil, but with significant loss of radiopacity, leading to reduced visibility. Cobalt chromium alloys have enabled a reduction in stent strut thickness to around 80?90 mm while retaining modest radiopacity, but due to higher elasti...

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The aim of this study was to qualitatively and quantitatively study MR artifacts of various stents on the basis of in vitro experiments. We were particularly interested whether sequence type and orientation of the stent with respect to the static magnetic field influences the artifact. We examined 18 stents of different material (nitinol, stainless steel, cobalt alloy), different design of the stent meshes (AccuLink, OmniLink, DynaLink, Xact, Protoge, Wallstent Monorail), different diameter (5-10 mm) and different length (18-58 mm) with a turbo spin echo (TSE), a 2D-fast low angle shot (FLASH) and a 3D-FLASH sequence. The MR images were examined qualitatively with respect to possible artifacts. Furthermore we examined the MR data quantitatively: The contrast-noise-ratio (CNR) was determined both within the stent and outside (within the tube); based on these values we calculated the ...

Energy Technology Data Exchange (ETDEWEB)

Electrochemical noise generated during stress corrosion cracking (SCC) of type 304 stainless steel (UNS S30400) and {alpha}-brass were studied. Noise patterns showed common characteristics (i.e., a quick drop and slow recovery of the potential). The quick drop corresponded to the initiation of localized events where fresh metal was exposed. The slow recovery corresponded to the repassivation process of the exposed bare metal. The potential drop rate and recovery rate were almost constant during the SCC process for a given SCC system. For random noise, rates of potential rise and drop were similar. Frequency of the noise generated during SCC increased with an increase in applied stress. SCC initiation could be monitored and determined according to noise characteristics and distribution. Since the shift of background potentials had an obvious influence on characteristics of power spectrum density (PSD), the direct current ...

Energy Technology Data Exchange (ETDEWEB)

A steady-state mathematical model was developed for a bare collector. Results obtained by previous authors for heat transfer and friction in rectangular ducts with periodic disturbances were employed to evaluate the effect of such disturbances on bare collector efficiency and on its pressure drop. An effective efficiency, which takes into account extra heat obtained and additional mechanical (electric) energy consumption for moving air when heat-transfer augmentation devices are employed, was defined. Simulation results are given for a bare collector, with and without perturbations, showing efficiency and effective efficiency dependence on collector dimensions, solar radiation intensity, disturbance diameter and pitch for collector performance optimization. (author).

Energy Technology Data Exchange (ETDEWEB)

To evaluate the feasibility and clinical effectiveness of using a polyurethane-covered expandable nitinol stent in the palliative treatment of malignant duodenal obstruction. Under fluoroscopic guidance, a polyurethane-covered expandable nitinol stent was placed in 12 consecutive patients with malignant duodenal obstructions. All presented with severe nausea and recurrent vomiting. The underlying causes of obstruction were duodenal carcinoma (n=4), pancreatic carcinoma (n=4), gall bladder carcinoma (n=2), distal CBD carcinoma (n=1), and uterine cervical carcinoma (n=1). The sites of obstruction were part I (n=1), part II (n=8), and III (n=3). Due to pre-existing jaundice, eight patients with part II obstructions underwent biliary decompression prior to stent placement. An introducer sheath with a 6-mm outer diameter and stents 16 mm in diameter were employed, and to place the stent, ...

KoreaScience (Korea)

Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Biodegradable helicoidal stent prototypes made up of layers of poly-L-lactic acid (PLLA) and poly(L-lactic-co-glycolic acid) (PLGA) polymers were fabricated by temperature conditioning the stents at different stages of fabrication. The process incorporated elastic memory, or self-expandability in the stent, which is desirable to minimize stent recoil. The collapse pressures of such stents were studied, with and without in vitro degradation. The effects of thickness and the composition of each layer on the collapse pressure were modeled using the simple series model. Results of the in vitro studies for over 3 months showed that collapse pressure of the stents depended mainly on the degradation and other side-effects brought about by the degradation of different polymer compositions. General...

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To evaluate the efficacy of a paclitaxel-eluting nitinol stent on the inhibition of pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt. Twelve pigs were used in this study. Two types of 10-mm diameter and 60-mm long nitinol stents were made for a transjugular intrahepatic portosystemic shunt by coating them with a polyurethane solution, with and without paclitaxel. Each transjugular intrahepatic portosystemic shunt was created successfully in the 12 swine with 7 paclitaxel-eluting stents and 5 polyurethane stents. Five swine in each group were followed-up for 14 days due to the death of 2 swine given the paclitaxel-eluting stents. The proliferation of the pseudointima was evaluated on both follow-up portograms and histopathology examinations. The mean maximum pseudointimal hyperplasia is expressed as the percentage of the stent radius. ...

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To investigate the problems of the Hanaro stent (Solco Intermed, Seoul, Korea) when used in the palliative treatment of patients with inoperable malignant biliary obstruction. Between January 2000 and May 2001, the treatment of 46 patients with malignant biliary obstruction involved percutaneous placement of the Hanaro stent. Five patients encountered problems during removal of the stent's introduction system. The causes of obstruction were pancreatic carcinoma (n=2), cholangiocarcinoma (n=2), and gastric carcinoma with biliary invasion (n=1). In one patient, percutaneous transhepatic cholangiography and stent insertion were performed as a one-step procedure, while the others underwent conventional percutaneous transhepatic biliary drainage for at least two days prior to stent insertion. A self-expandable Hanaro stent, 8-10 mm in deameter and 50-100 mm ...

International Nuclear Information System (INIS)

We present our initial experience with a new biodegradable (BD) esophageal stent in two patients, one for a therapy-resistant benign esophageal stricture, and the other as a temporary measure during curative radiotherapy for oesophageal carcinoma. The BD stents need to be loaded into a conventional pull-back delivery system but are then placed in a standard fashion. Pre-dilatation should be avoided to reduce the risk of migration, however if migration occurs the stents can be left to dissolve in the stomach. The stents are radiolucent but easily identified on CT with minimal artefact and thus might even aid with radiotherapy planning. BD stents offer an exciting new strategy for therapy-resistant benign strictures as well as a supportive measure for oesophageal cancer undergoing non-surgical treatment. (orig.)

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AIM: The purpose of the study was to evaluate the percutaneous use of the new nitinol SMARTeR stents in patients with biliary obstruction. MATERIALS AND METHODS: Four stents were placed in three patients percutaneously under ultrasound and fluoroscopic guidance. RESULTS: The deployment of the stents was successful in all three patients. All stents maintained their patency and position after short-term follow-up. CONCLUSION: The nitinol SMARTeR stent is useful in the management of patients with biliary obstruction although accurate placement across the ampulla was found to be technically more difficult than with the Wallstent. Larger, long-term follow-up studies are required to evaluate the long-term patency of these new devices.

Energy Technology Data Exchange (ETDEWEB)

Alloy 600 is commonly used in the primary systems of PWR plants because of its excellent resistance to a stress corrosion cracking and pitting. But a stress corrosion cracking and pitting corrosion are occasionally observed under PWR conditions, which may be correlated with the passive film on the Alloy 600 surface. There is little information on the composition of films growing on the surface of Alloy 600 at high temperature. Therefore, an understanding of the basic electrochemical behaviors about an anodic dissolution and the passivation of the bare surface of metals and alloys provides important information about localized corrosions like a SCC and pitting. Oxide on the steel surfaces in an aqueous solution above 100 .deg. C is composed of a duplex film structure. The inner layer of the oxide is dense and less porous, which is formed by a growth of the oxide layer on the metal surface. Outer layer of the oxide is less ...

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We wanted to evaluate the status of self-expandable nitinol stents implanted in the P2 and P3 segments of the popliteal artery in Korean patients. We retrospectively analyzed 189 consecutive patients who underwent endovascular treatment for steno occlusive lesions in the femoropopliteal artery from July 2003 to March 2009, and 18 patients who underwent stent placement in popliteal arterial P2 and P3 segments were finally enrolled. Lesion patency was evaluated by ultrasound or CT angiography, and stent fracture was assessed by plain X-rays at 1, 3, 6 and 12 months and annually thereafter. At the 1-month follow-up, stent fracture (Type 2) was seen in one limb (up to P3, 1 of 18, 6%) and it was identified in seven limbs at the 3-month follow-up (Type 2, Type 3, Type 4) (n = 1: up to P2: n = 6: P3). At the 6-month follow-up, one more fracture (Type 1) (up to P3) was noted. At the 1-year follow-up, there ...

UK PubMed Central (United Kingdom)

To treat or prevent some of the 795,000 annual strokes in the U.S., self-expanding endo-vascular stents deployed under fluoroscopic image guidance are often used. Neuro-interventionalists need...Full Text Available

UK PubMed Central (United Kingdom)

Restenosis remains the main complication of balloon angioplasty and/or stent implantation. Preclinical testing of new pharmacologic agents preventing restenosis largely rely on porcine models, where...Full Text Available

Medline Plus

... m going to have a kink or a hinge point right behind it, I'll -- we'll ...

UK PubMed Central (United Kingdom)

Background and ObjectivesClopidogrel resistance or low-responsiveness may be associated with recurrent atherothrombotic events after drug-eluting stent (DES) implantation. We prospectively...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Objective: To evaluate technical feasibility and acute and subacute radiotolerance of a self-expandable stent loaded with {sup 125}I seeds in the rabbit esophagus. Methods: A self-expandable stent designed for esophageal application was made of 0.16 mm nitinol wire and loaded with {sup 125}I seeds (CIAE-6711). Twenty-seven stents with three different radioactive dosages (n = 9 in each dosage group) were implanted in the esophagus of healthy rabbits, while nine stents alone were used as controls. The stents were perorally deployed into the esophagus under fluoroscopic guidance. Radiological follow-up included plain chest film, CT scan, and barium esophagography which were undertaken in all rabbits of each group at 2, 4, and 8 weeks, respectively, which were correlated to histopathological findings. The stented esophageal segments along with their adjacent tissues ...

Science.gov (United States)

green (both light and dark tones) and purple, bare areas are seen in ...... spatial scale continue to plague such efforts. Knowledge of the spatial ...

Energy Technology Data Exchange (ETDEWEB)

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.

Energy Technology Data Exchange (ETDEWEB)

Objective: To evaluate the treatment of malignant biliary stenoses and occlusions using a new stent. Methods: In a prospective study, 25 patients with malignant obstructive jaundice were treated with SMART stents. The handling and the quality of stent expansion were documented. Stent function was assessed 2-4 days after intervention by cholangiography and laboratory tests. A follow-up was performed three months, after stent placement. Results: All lesions were treated successfully, with a total of 35 stents implanted. In 14 patients a further balloon dilatation was performed after stent placement (8-10 mm diameter/40-80 mm length). The mean serum bilirubin level decreased significantly from 11.6 mg/dl to 4.6 mg/dl after intervention (p<0.05). The follow-up showed a mean serum bilirubin level at 4.0 mg/dl. In 4 cases (16%) a further ...

Energy Technology Data Exchange (ETDEWEB)

The objective of this study was to compare contrast-enhanced magnetic resonance angiography (CE MRA) and multislice computed tomographic angiography (MS CTA) in the follow-up of thoracic stent-graft placement. The CE MRA and MS CTA were performed following nitinol stent-graft treatment due to thoracic aneurysm (n=4), intramural bleeding (n=2) and type-B aortic dissection (n=5). Corresponding evaluation of arterial-phase imaging characteristics focused on the stent-graft morphology and leakage assessment. Stent-graft and aneurysm extensions were comparable between both techniques. Complete exclusion (aneurysm, n=4; dissection, n=2) was assessed with high confidence with CE MRA and MS CTA. Incomplete exclusion (intramural bleeding, n=2; dissection, n=3) was assigned to lower confidence scores on CE MRA compared with MS CTA. On CE MRA the stent-graft lumen demonstrated an inhomogeneous ...

Energy Technology Data Exchange (ETDEWEB)

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 ...

Energy Technology Data Exchange (ETDEWEB)

The permeation of hydrogen through steam generator tubes at high temperatures ({approx} 300 degrees C) has been studied using an electrochemical technique. With this technique, hydrogen is generated on one side of the tube and monitored on the other side. The time for the hydrogen to reach the other side is used to determine the diffusion coefficient of hydrogen in the tube. Boundary conditions at the entry and exit sides have been investigated separately. Preliminary studies were performed on Stainless Steel 316 and Nickel Alloy 800 to better understand the influence of the solution chemistry on the electrochemical evolution of hydrogen. The surface phenomena effect and the trapping effect are discussed to account for differences observed in the permeation response. The hydrogen permeation through oxides at the exit side has been studied. Two nickel alloys (Alloy 800 and Alloy 600), materials widely used for steam generator tubes, have been investigated. The tubes were prefilmed using ...

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate the success rates of the implantation of stent grafts in the treatment of peripheral aneurysms. Materials and methods: in 13 patients with 15 aneurysms at the common iliac artery (n = 6), external iliac artery (n = 1), hypogastric artery (n = 2), femoral artery (n = 2) or popliteal artery (n = 4), implantation of dacron-covered nitinol stents was performed. The patients were followed up for three to 20 months (mean, 8.8 months) with intravenous digital subtraction angiography, CT or colour-coded Doppler sonography. Results: In all cases, the aneurysm was successfully occluded after stent implantation. In one case with a popliteal aneurysm, kinking of the vessel caused thrombosis of the stent. The stent was successfully reopened. The aneurysm however, had to be surgically treated 9 months later. The primary and secondary patency rates at 6 months were 93% and ...

Energy Technology Data Exchange (ETDEWEB)

A method for the determination of different ''bare'' characteristics of the one-particle motion and one-particle basis in magic nuclei is described. The method is based on separating out the mixing with phonons from the phenomenological one-particle characteristics. By means of a generalization of the procedure for localization of the mass operator, relations linking the bare and phenomenological characteristics are obtained. The radial dependence of these characteristics in finite nuclei and the influence of the quasiparticle--phonon interaction on the phenomenological characteristics are studied. Calculations are performed for the neutrons in /sup 208/Pb.

UK PubMed Central (United Kingdom)

ObjectiveWe wanted to evaluate the status of self-expandable nitinol stents implanted in the P2 and P3 segments of the popliteal artery in Korean patients.Materials...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate the initial and mid-term results of a new self-expanding low strut profile nitinol stent for treatment of atherosclerotic lesions stenoses and occlusions in the superficial femoral artery (SFA). Materials and Methods: In 8 patients (4 male, 4 female, mean age 74.8 {+-} 8.8 years) with SFA lesions and non-satisfying results after PTA treatment alone, 10 self-expanding nitinol Xpert stents were deployed via a 4 F sheath. Stent characteristics and handling were graded by the interventionalist. Fontaine classification, duplex flow measurements and ankle brachial index (ABI) at rest and stress were taken prior and one day after stent placement. Patients were followed 3, 6 and 12 months after the procedure obtaining the same parameters at each appointment. Results: Initial stent treatment was successful in all patients. Stent handling and ...

UK PubMed Central (United Kingdom)

BACKGROUNDSeveral carotid endarterectomy (CEA) randomized controlled trials (RCTs) and series have reported higher perioperative stroke and death rates for women...Full Text Available

International Nuclear Information System (INIS)

The endovascular treatment of atherosclerotic intracranial arterial stenoses has previously been based on balloon dilatation or the deployment of a balloon expandable stent. Both methods have advantages (balloon: flexibility; balloon expandable stent: high radial force) and drawbacks (balloon: risk of elastic recoil and dissection; balloon expandable stent: limited flexibility, risk of injury to the vessel due to excessive straightening, overexpansion at ends of stent). A new combination of balloon dilatation, followed by the deployment of a self-expanding microstent has been applied in 15 patients with atherosclerotic arterial stenoses, symptomatic despite medical treatment. An anatomically and clinically adequate result was achieved in all patients. The initial degree of stenosis was 72% (mean). Balloon dilatation resulted in an average residual stenosis of 54% (mean), reduced further to a mean of 38% ...

International Nuclear Information System (INIS)

Chronic mesenteric arterial ischemia is an uncommon condition associated a high morbidity and mortality. It is most Commonly caused by atherosclerotic occlusive disease. Patients may suffer epigastric or periumbilical postprandial pain ten to thirty minutes after eating. A case of chronic mesenteric artery stenosis, the diagnosis was performance with colonoscopy and biopsy. We present a case report of a patient with chronic mesenteric ischemia. Mesenteric arteriography was performed and documented estenosis of the mesenteric superior artery. Then percutaneous arteriography with angioplasty and implant of stent was performed. The patients became completely asymptomatic and normal colon mucous is observed in control colonoscopy. The purpose of this report is to present the case endoscopy, clinic and radiological features and to describe the percutaneous angioplasty and implant of stent. We believe that angioplasty treatment offers and improvement ...

British Library Electronic Table of Contents (United Kingdom)

PurposeTo evaluate the safety and effectiveness of the Zilver vascular stent in the treatment of de novo or restenotic lesions in the external and common iliac arteries.Materials and MethodsRegardless of the results of an initial percutaneous transluminal angioplasty (PTA), 151 consecutive patients were implanted with Zilver vascular stents (Cook, Bloomington, Ind) in up to two stenotic (?10 cm) or occluded (?5 cm) atherosclerotic lesions of the external or common iliac arteries. The primary endpoint was the rate of major adverse events within 9 months after the procedure. Major adverse events were defined as death, myocardial infarction, target lesion revascularization, and limb loss. Secondary endpoints included acute procedural success, 30-day clinical success, 9-month pat...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study was to evaluate the usefulness of a multifunctional gastrointestinal coil catheter for stent placement in 98 patients with colorectal strictures. The catheter was used in 98 consecutive patients for stent placement in the rectum (n = 24), recto-sigmoid (n = 13), sigmoid (n = 38), descending (n = 6), transverse (n = 11), splenic flexure (n = 3), hepatic flexure (n = 2), and ascending (n = 1) colon. The catheter was made of a stainless steel coil (1.3 mm in inner diameter), a 0.4-mm nitinol wire, a polyolefin tube, and a hemostasis valve. Usefulness of the catheter was evaluated depending on whether the catheter could pass a stricture over a guide wire and whether measurement of the stricture length was possible. The passage of the catheter over a guide wire beyond the stricture was technically successful and well tolerated in 93 (94.9%) of 98 patients. In the failed five patients, it was not possible to negotiate the ...

UK PubMed Central (United Kingdom)

Leakage after oesophageal anastomosis or perforation remains a challenge for the surgeon. Traditional management has been operative repair or intensive conservative management. Both treatments are...Full Text Available

UK PubMed Central (United Kingdom)

Incidence of esophageal cancer (EC) is rising more rapidly in the Western world than that of any other cancer. Despite advances in therapy, more than 50% of patients have incurable disease at the time...Full Text Available

UK PubMed Central (United Kingdom)

Gastrointestinal perforations are conservatively managed at endoscopy by through-the-scope endoclips and covered self expandable stents, according to the size and tissue features of the perforation....Full Text Available

UK PubMed Central (United Kingdom)

BackgroundObservational clinical studies have shown that patients with diabetes have less favorable results after percutaneous coronary intervention compared with the non-diabetic...Full Text Available

UK PubMed Central (United Kingdom)

A 57-year-old man with a history of coronary artery disease and placement of an implantable cardioverter-defibrillator presented at our emergency room with an anterior ST-elevation myocardial infarction....Full Text Available

UK PubMed Central (United Kingdom)

Pseudoaneurysms related to the superior mesenteric artery (SMA) are a recognised complication of trauma to the vessel, and successful treatment with stenting has been previously described. We report...Full Text Available

UK PubMed Central (United Kingdom)

IntroductionIntrarenal pseudoaneurysm is a rare, yet clinically significant, complication of percutaneous nephrolithotomy. A high index of clinical suspicion is necessary in order...Full Text Available

UK PubMed Central (United Kingdom)

IntroductionFlow diversion is a new approach to the endovascular treatment of intracranial aneurysms which uses a high density mesh stent to induce sac thrombosis. These devices...Full Text Available

UK PubMed Central (United Kingdom)

Carotid artery stenosis is a major risk factor for stroke, and treatments for this condition to decrease the risk of stroke include medical therapy, carotid endarterectomy (CEA), and, more recently,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The behaviour of bare aluminium is studied in atmospheric exposure at 11 natural testing stations with salinity levels ranging between 2.1 and 684 mg Cl''- m''-2 d''-1. In atmospheres of low or moderate aggressivity aluminium behaves as a passive material, though the insignificant corrosion that is produced is sufficient to spoil its appearance. In contrast, at salinity levels of 50 mg Cl''- m''-2 ''-1 or above, aluminium is susceptible to pitting corrosion even in the first year of atmospheric exposure, or in the second year at salinities of {<=} 10 mg Cl''- m''-2 d''-1. For comparative purposes, results are included for aluminium protected with an anodic film of 28 {mu}m thickness exposed at the same testing stations. A 28 {mu}m anodic film, correctly sealed, prevents the risk of localised ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study was to investigate the feasibility and the optimal conditions of radiofrequency (RF) ablation by using the stent-type electrode upon the saphenous vein of goats for the endovenous treatment of varicose veins. A self-expandable nitinol stent electrode (6 mm diameter, 2 cm length, cell size; 1.3 x 2 mm) was designed to expose the distal 1 cm segment to allow for contact with the venous wall. The proximal part of the electrode was connected to the RF generator by insulated copper wires located within the stent electrode introducer. Initially, to optimize the power setting, ablation of 6 saphenous veins in 3 goats was performed with power settings of 10, 20 and 30 W. Pull back rate of the electrode was 2 and 4 cm/min for each power level, respectively. The goats were sacrificed 4-6 weeks later and histologic examinations of the saphenous veins were done. For the second part of the experiment, RF ...

British Library Electronic Table of Contents (United Kingdom)

Riparian agricultural environments in eastern Australia are widely used for cattle grazing, but are also preferred habitat for native, soil-disturbing mammals such as the bare-nosed wombat (Vombatus ursinus). We examined the effects of mound construction by wombats, and track development by cattle and wombats, on soil displacement in a riparian landscape at high and low levels of cattle usage. Splash erosion was measured on mounds and inter-mounds with splashboards, and changes in the profiles of cattle-wombat tracks were assessed using a profilemeter. Twice as much soil was detached by splash erosion from mounds than inter-mounds, irrespective of cattle usage, and about three-times more coarse sand and 40% more fine sand was detached from mounds and inter-mounds at the high cattle sites. ...

Energy Technology Data Exchange (ETDEWEB)

Corona from bare conductors of electrical overhead power lines is studied in this article. Its origin, as well as, its bad influences over communication systems are both studied, yet. Line`s models are defined, in order to be able the examination of Corona on line`s cables. Formulas for the surface electrical gradient calculations are shown. (author) 2 refs.

International Nuclear Information System (INIS)

Objective: To evaluate the diagnostic value of 64 multidetector-row CT angiography for internal carotid artery (ICA) stenosis and the application in the follow-up of carotid endarterectomy and percutaneous transluminal stenting. Methods: Forty transient ischemic attack (TIA) patients with interpretable CTA and DSA of the cervical carotid arteries were selected from May 2005 to December 2005. This yielded a total of 80 vessels. The CTA curved planar reformations (CPR) and DSA images referenced to the distal cervical internal carotid were graded by two senior neuroradiologists blindly, according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) guidelines. The paired-t test was used to verify the statistical significant difference between pre-operating and post-operating of carotid endarterectomy or percutaneous transluminal stenting in measuring the vascular diameter and area of cross section using CTA. Results: When the ...

British Library Electronic Table of Contents (United Kingdom)

ObjectivesThe SPIRIT V (A Clinical Evaluation of the XIENCE V Everolimus-Eluting Coronary Stent System in the Treatment of Patients With De Novo Coronary Artery Lesions) study is a post-market surveillance experience of the XIENCE V (Abbott Vascular, Santa Clara, California) everolimus-eluting stent (EES) in patients with higher-risk coronary anatomy. BackgroundPrevious pre-approval studies have shown the safety and efficacy of EES in highly selected groups of patients. MethodsThe SPIRIT V trial is a prospective, open label, single arm, multicenter study. Two thousand seven hundred patients with multiple de novo coronary artery lesions suitable for treatment with a planned maximum of 4 EES were enrolled at 93 centers in Europe, Asia Pacific, Canada, and South Africa. Lesions had a referenc...

British Library Electronic Table of Contents (United Kingdom)

PurposeWe objectively quantified the gain in urethral diameter and the effect of stenting after tubularized incised plate urethroplasty in a rabbit hypospadias model. Materials and MethodsWe created a hypospadias model in 12 New Zealand white male rabbits by excising the ventral urethra. A 3 cm tattoo line was made longitudinally in the dorsal urethral plate midline. Two weeks later a 2 cm relaxing incision was made in the middle part of the tattooed line. The stretched incision width between the tattooed edges was measured, followed by urethral plate tubularization. Six rabbits were stented and 6 were nonstented. Two weeks later the animals were sacrificed and the distance separating the tattoo was measured at the midpoint of the tattooed line. Transverse sections at this point were exami...

CERN Document Server

Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, $m_s$, $m_u$, and $m_d$, respectively. Perturbative matching is required in order to connect the lattice-regularized bare- quark masses to the masses as defined in the \\msbar scheme, and this is done here for the first time at next-to-next-to leading (or two-loop) order. The bare-quark masses required as input come from simulations by the MILC collaboration of a highly-efficient formalism (using so-called ``staggered'' quarks), with three flavors of light quarks in the Dirac sea; these simulations were previously analyzed in a joint study by the HPQCD and MILC collaborations, using degenerate $u$ and $d$ quarks, with masses as low as $m_s/8$, and two values of the lattice spacing, with chiral extrapolation/interpolation to the physical masses. With the new perturbation theory ...

CERN Document Server

A fundamental and very well studied region of the Erd\\"os-R\\'enyi process is the phase transition at n/2 edges in which a giant component suddenly appears. We examine the process beginning with an initial graph. We further examine the Bohman-Frieze process in which edges between isolated vertices are more likely. While the positions of the phase transitions vary, the three processes belong, roughly speaking, to the same universality class. In particular, the growth of the giant component in the barely supercritical region is linear in all cases.

Energy Technology Data Exchange (ETDEWEB)

The marine ram-type blowout preventer deployed from an offshore drilling rig has one serious disadvantage, its inaccessibility. A development to promote reliability of the subsea ram-type preventer and reduce the excess running and pulling to charge out rams, is the variable bare ram (VBR). Unlike the standard ram, the VBR has the ability to pack off a range of pipe sizes. Interest in VBR's has been revived and research and development in this equipment goes on at each of three manufacturer's facilities in Houston.

International Science & Technology Center (ISTC)

Metal Matrix Composites on the Basis of Nano-Materials

Energy Technology Data Exchange (ETDEWEB)

To understand the effect of heat treatment and mechanical polishing of a Nitinol wire on the chemical composition and physical morphology of the wire surface. Stents with a diameter of 1.0 cm, length of 8-10 cm, and composed of a Nitinol wire, were heat-treated at 500 .deg. C for 30 minutes, and mechanically polished with walnut shell granules. The wire surface morphology was studied with both an optical and a scanning electron microscope (SEM). In addition, an elemental analysis was performed by Energy Dispersive X-ray spectroscopy (EDX). Long microcracks along the wire direction and short microcracks across the wire were observed by SEM from the raw Nitinol wire. Upon heat treatment, the color of the wire turned blue, and Na, K, Cl, Si, Al atoms were seen from the EDX of the heat treated wire, which were absent in the original wire. The microcracks disappeared with the mechanical polishing, and the Na, K, Cl, Si, Al atoms all disappeared after the mechanical ...

UK PubMed Central (United Kingdom)

The interaction between two metals, which can be either synergistic or antagonistic, implies that the behavior of one is changed by the presence of the other. Possible mechanisms of these interactions,...Full Text Available

International Nuclear Information System (INIS)

Aim: To evaluate magnetic resonance cholangiography (MRC) with high-resolution dynamic gadolinium-enhanced magnetic resonance imaging (MRI) in determining the imaging features of hilar cholangiocarcinoma that relate to tumour extent and influence resectability. Materials and methods: Twenty-six patients that underwent resection were reviewed. Tumour location and extent, lobar atrophy, the degree of portal vein and hepatic artery involvement were recorded. The findings were correlated with surgical and histopathological findings. Results: Biliary assessment was concordant in 14 and discordant in eight of 14 stented and four of 12 non-stented patients. In 63/82 veins and 43/74 arteries results were fully concordant. The mean sensitivity, specificity, positive and negative predictive values (PPV, NPV) in predicting involvement of the main portal vein (MPV) at surgery were 83.3, 100, 100, and 92.5%; of the left main branch of the portal vein (LPV) ...

International Nuclear Information System (INIS)

Nuclear astrophysics seeks for a possible explanation of the observed abundance distribution of various elements and their isotopes in the universe. Most of the relevant nuclear reactions take place in thermally equilibrium environments with bare nuclei, rather than accelerated and head-on colliding situations with low ionisation states of reactant atoms and molecules that are emulated in the laboratories. Moreover, the temperature of the astrophysical environments is quite often low compared to the centre-of-mass energy of the projectile nuclides, that is required for the reaction to be meaningfully investigated in the laboratory. Therefore, an extrapolation of the data on the reaction cross sections to very low energies and to extremely high density situations is generally called for, which are substantially altered every now and then for a number of astrophysically important reactions. The radioactive ion beams will provide us important data on some of those ...

CERN Document Server

The Goldstone-Brueckner perturbation theory is extended to incorporate in a simple way correlations associated with large amplitude collective motions in nuclei. The new energy expansion making use of non-orthogonal vacua still allows to remove the divergences originating from the hard-core of the bare interaction. This is done through the definition of a new Brueckner matrix summing generalized Brueckner ladders. At the lowest-order, this formalism motivates variational calculations beyond the mean-field such as the Generator Coordinate Method (GCM) and the Projected Mean-Field Method from a perturbative point of view for the first time. Going to higher orders amounts to incorporate diabatic effects in the GCM and to extend the projection technique from product states to well-defined correlated states.

International Nuclear Information System (INIS)

The electron-phonon spectral distribution function #alpha#"2(#omega#) F (#omega#) has been calculated for niobium. The electron energy bands and wave functions were obtained from a self-consistent augmented-plane-wave muffin-tin potential, and the electron-phonon matrix elements were evaluated using the so-called rigid-ion approximation. With this approximation it is found that #alpha#"2(#omega#) is constant over the whole energy spectrum. The electron-phonon mass enhancement has also been calculated for local regions of the Fermi surface and found to be anisotropic. The calculated local values of the enhancement do not agree with experimental values available for different orbits from de Haas--van Alphen measurements. The discrepancy seems to arise because the bare-rigid-ion matrix elements are relatively small between states with nearly pure l = 2 character.

CERN Document Server

In this article we present the complete resummation of the leading chirally-enhanced corrections stemming from gluino-squark, chargino-sfermion and neutralino-sfermion loops in the MSSM with non-minimal sources of flavor-violation. We compute the finite renormalization of fermion masses and the CKM matrix induced by chirality-flipping self-energies. In the decoupling limit Msusy>>v, which is an excellent approximation to the full theory, we give analytic results for the effective gaugino(higgsino)-fermion-sfermion and the Higgs-fermion-fermion vertices. Using these vertices as effective Feynman rules, all leading chirally-enhanced corrections can consistently be included into perturbative calculations of Feynman amplitudes. We also give a generalized parametrization for the bare CKM matrix which extends the classic Wolfenstein parametrization to the case of complex parameters lambda and A.

Energy Technology Data Exchange (ETDEWEB)

An apparatus is described for measuring the total hemispherical emittance of pipes of a length suitable for use in a prototype solar collector. The calorimetric method used requires measurements of the temperatures of the surface of the test pipe and of a concentric outer cylinder and measurement of the electrical power used to heat the test pipe. Measurements were made of the total hemispherical emittance of black chrome, nickel, and bare steel pipes as a function of temperature. The emittance of the black chrome surfaces increased significantly from an extrapolated value of about 0.1 at 25 deg C to values on the order of 0.3-0.4 at 300 deg C. The extrapolated values for black chrome agreed with measurements made using other techniques at room temperature. The results for the nickel-plated pipe agreed with total emittance calculated from spectral reflectance data.

Science.gov (United States)

Hydrogen molecule adsorption on the (0001) surface of double hexagonal closed packed americium has been studied in detail within the framework of density functional theory. Weak molecular hydrogen adsorptions were observed. The most stable configuration corresponded to a Hor2 approach molecular adsorption at the one-fold top site where the molecule's approach is perpendicular to a lattice vector. Adsorption energies and adsorption geometries for different adsorption sites will be discussed. The change in work functions, magnetic moments, partial charges inside muffin-tins, difference charge density distributions and density of states for the bare Am slab and the Am slab after adsorption of the hydrogen molecule will be discussed. Reaction barrier for the dissociation of hydrogen molecule will be presented. The implications of adsorption on Am 5f electron localization-delocalization will be summarized.

KoreaScience (Korea)

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International Science & Technology Center (ISTC)

Development of Technology for Metal Surface Decontamination in Aqueous Solutions

Energy Technology Data Exchange (ETDEWEB)

NO abstract prepared.

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The preparation by sputtering of artificial metallic superlattices is described, as are the results of x-ray structural determinations. Tunneling and resistivity measurements on these materials are reported.

CERN Document Server

Metals and alloys : atmospheric corrosion testing : General requirements for field tests

Science.gov (United States)

... Title : Compressive and Shear Buckling Analysis of Metal Matrix Composite Sandwich Panels Under Different Thermal Environments. ...

Science.gov (United States)

... nent to the design and construction of metal-semiconductor solar cells, in that both the photovoltage and the efficiency of metal-semiconductor cells ...

International Nuclear Information System (INIS)

Full text: Semiconductor detectors coated with boron or lithium compounds have been studied for neutron detection for decades but, until recently, have been limited to thermal neutron detection efficiencies of less than 5%. We reported previously on development and simulation studies of perforated detectors whose perforations are filled with neutron-reactive material in order to produce higher detection efficiencies. Incorporation of bare and cadmium-backed detectors into battery-powered devices with low-power electronics enables us to produce compact personal neutron dosimeters that provide LED readout of counts, which can be related approximately to neutron dose. We report here on experimental studies with such compact devices; devices capable of direct readout in dose units are anticipated. The thermal and epithermal neutron flux densities from the tangential beam tube of the TRIGA Mark II reactor at Kansas State University were measured. Then, thermoluminescent ...

DEFF Research Database (Denmark)

BACKGROUND AND AIM OF THE STUDY: Abnormal flow conditions across aortic bioprosthetic valves may result in degenerative processes. Thus, it is important to implant biological valve prostheses with velocity profiles similar to those of native valves. The study aim was to compare blood velocity and velocity gradient profiles downstream of stented and stentless aortic valves implanted in pigs, and in native porcine valves. METHODS: Stented valve prostheses (Mitroflow, n = 7) or stentless valve prostheses (Solo, n = 5 or Toronto SPV, n = 7) were implanted into pigs; the native valve was retained in eight animals. After weaning the animals from cardiopulmonary bypass, cardiac magnetic resonance imaging was performed to determine the blood velocities and velocity gradient profiles. RESULTS: The native valves had a significantly lower peakvelocity (92 +/- 26 cm/s) than the artificial valves (Solo: 247 +/- 107 cm/s; Toronto: 252 +/- 41 cm/s; Mitroflow: ...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Although the esthetic outcome of a collarless metal ceramic restoration is superior to that of a restoration with a metal margin, its mechanical strength has not been evaluated. Purpose The purpose of this study was to evaluate and compare the fracture resistance of metal ceramic restorations with metal margins to that of metal ceramic restorations with circumferential porcelain margins, after exposure to masticatory simulation. Material and methods Twenty-four metal ceramic restorations were fabricated and paired with 24 cobalt-chrome tooth analogs. Twelve of the specimens had metal margins, while the remainder had circumferential porcelain margins. The restorations were cemented on the metal tooth analogs with a resin-modified glass ionomer luting agent (FujiCEM). Al...

Energy Technology Data Exchange (ETDEWEB)

The surface properties of copper-refractory metal (CU-RF) alloy bodies are modified by heat treatments which cause the refractory metal to form a coating on the exterior surfaces of the alloy body. The alloys have a copper matrix with particles or dendrites of the refractory metal dispersed therein, which may be niobium, vanadium, tantalum, chromium, molybdenum, or tungsten. The surface properties of the bodies are changed from those of copper to that of the refractory metal.

International Nuclear Information System (INIS)

High temperature fatigue crack growth (FCG) and creep crack growth (CCG) experiments have been conducted in air on weld metal, heat affected zone (HAZ) and base metal of the austenitic Alloy 800 and the nickel base Alloy 617. Tests were performed on specimens machined from pipes, in the temperature range 550-900 deg. C. The crack propagation mode was examined. At all temperatures and for both materials, FCG of base metal was found to be the highest, whereas the weld metal exhibited the lowest FCG rate. The FCG rate in the HAZ was found to lie in between of those observed for base and weld metal. The crack propagation mode remained transgranular in base metal and transdendritic in weld metal at all temperatures. CCG behaviour could be described using the energy rate integral C*. Base metal and weld ...

UK PubMed Central (United Kingdom)

The Δ- and Λ-isomerism of octahedral metal complexes is employed as a source of chirality for inducing chiral nematic phases. By applying a wide range of chiral metal complexes as a...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Accelerated aging tests on tin-oxide-coated anodized aluminium selective absorber surfaces have been performed. It is shown that the tin oxide layer provides excellent protection for the anodized surface. The thermal stability of the double layer is equal to, or better than, the stability of the bare anodized surface. Both surfaces degrade very slowly at 450deg C. The anodic layer is porous and therefore not very scratch resistant and it degrades when exposed to humidity, both acidic and alcaline. It is shown that the tin oxide film, which is hard and chemically very stable, almost completely protects the anodized surface from chemical degradation. The mechanical wear resistance is also considerably improved. The optical selectivity does not quite match that of the the anodized surface, but the remarkable stability together with the solar parameters of {alpha}=0.91 and hemispherical emittance {epsilon}= 0.16 (normal emittance {epsilon}{sub n}=0.12) make this ...

Energy Technology Data Exchange (ETDEWEB)

We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C{sub 14}), palmitic acid (C{sub 16}), stearic acid (C{sub 18}), and arachidic acid (C{sub 20}) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for higher molecular-weight gas, and we found ...

International Nuclear Information System (INIS)

Spherical nanostructured Si/C composite was prepared by spray drying technique, followed by heat treatment, in which nanosized silicon and fine graphite particles were homogeneously embedded in carbon matrix pyrolyzed by phenol formaldehyde resin. Cyclic voltammetry tests showed two pairs of redox peaks corresponding to lithiation and delithiation of Si/C composite. The Si/C composite exhibited a reversible capacity of 635 mAh g"-"1 and good cycle performance used in lithium ion batteries. To improve cycle performance of this Si/C composite further, the carbon-coated Si/C composite was synthesized by the second spray drying and heat treatment processing. The cycle performance of carbon-coated Si/C composite was improved significantly, which was attributed to the formation of stable SEI passivation layers on the outer surface of carbon shell which protected the bared silicon from exposing to electrolyte directly.

International Nuclear Information System (INIS)

Data by Wiesmann et al. on the temperature coefficient of the upper critical field, dH/sub c/2(T)/dT, and the normal-state resistivity rho_0 near the superconducting transition temperature T/sub c/ are analyzed to estimate the bare density of states N (E/sub F/) as a function of structural disorder and T/sub c/ in various #alpha#-particle irradiated samples of A-15 Nb_3Ge and Nb_3Sn. By taking into account the change in the electron-phonon coupling strength with T/sub c/ and the effect of mass enhancement arising from the electron-phonon interaction, the results of the new analysis indicate that (i) the drop in N (E/sub F/) for Nb_3Ge is relatively small as T/sub c/ changes from approx. 21 to approx. 4 K, in agreement with a recent low-temperature specific-heat measurement; (ii) the value of N (E/sub F/) in Nb_3Sn decreases by a factor of approx. 4 as T/sub c/ varies from approx. 18 to approx. 3 K. The implication of these findings is discussed in terms of the ...

International Nuclear Information System (INIS)

Contrary to previous plans for the preparation of diagnostic systems for D-T break-even experiments in the Tokamak Fusion Test Reactor (TFTR), it now appears that a limited Q#approx#1 demonstration can be carried out without constructing a close-fitting igloo radiation shield around the tokamak. In order to assess the impact of D-T operation of TFTR without an igloo shield, particularly with regard to hardening of diagonstic systems, we have mapped neutron and gamma fluxes inside the test cell and test cell basement, using a variety of radiation measurements. The measurements are sufficiently detailed to resolve massive hardware components, such as neutral beams and shielded diagnostic systems, and can be used to predict local fluxes. By comparing the measurements with transport code calculations for the case of a bare tokamak, we conclude that the models have substantially overestimated fluxes both inside and outside the TFTR shield walls. It may be possible to ...

Energy Technology Data Exchange (ETDEWEB)

Infrared astronomical instruments require absorptive coatings on internal surfaces to trap scattered and stray photons. This is typically accomplished with any one of a number of black paints. Although inexpensive and simple to apply, paint has several disadvantages. Painted surfaces can be fragile, prone to shedding particles, and difficult to clean. Most importantly, the vacuum performance is poor. Recently a plasma enhanced chemical vapor deposition (PECVD) process was developed to apply thick (30 {micro}m) diamond-like carbon (DLC) based protective coatings to the interior of oil pipelines. These DLC coatings show much promise as an infrared black for an ultra high vacuum environment. The coatings are very robust with excellent cryogenic adhesion. Their total infrared reflectivity of < 10% at normal incidence approaches that of black paints. We measured outgas rates of <10{sup -12} Torr liter/sec cm{sup 2}, comparable to bare stainless steel.

International Nuclear Information System (INIS)

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible ...

Energy Technology Data Exchange (ETDEWEB)

The application of the LBB technology to the newly constructed PWRs has been approved in Korea for several high energy systems that can meet rigorous acceptance criteria. The LBB evaluation had been initiated for Yong-Gwang 3 and 4 units (YGN 3 and 4) which are in service, and subsequently performed for Ul-Chin 3 and 4 units (UCN 3 and 4) which are in construction. The LBB application in Korea is based on the USNRC requirements. The LBB evaluation for YGN 3 and 4 is to eliminate the dynamic effects associated with the postulated DEGB from design basis loads as well as to eliminate pipe whip restraints and jet impingement barriers. There were several issues on the application of LBB to the primary coolant loop and the pressurizer surge line. Of concern were material properties of carbon steel for the primary coolant loop, estimation of crack opening area at the pipe-to-nozzle interface considering the asymmetry, and the leakage crack size which barely meets the ...

International Nuclear Information System (INIS)

Fully relativistic full-potential density functional calculations with an all-electron linearized augmented plane wave plus local orbitals method have been performed to investigate the electronic and geometric structures of atomic carbon, nitrogen, and oxygen chemisorption on the (1 0 0) surface of #delta#-Pu. For all chemisorption processes, the center adsorption site is found to be the most preferred site with chemisorption energies of 7.964, 7.665, and 8.335 eV for the C, N, and O adatoms, respectively. The respective optimized distances of the C, N, and O adatoms from the surface were found to be 0.26, 0.35, and 0.48 A. The work functions and the net magnet moments, respectively, increased and decreased in all cases compared with the bare #delta#-Pu (1 0 0) surface. In particular, the work function shift is largest for the least preferred top site and lowest for the most preferred center site. A detailed analysis of partial charges inside the atomic spheres, ...

Science.gov (United States)

... Abstract : Small metallic fragments can be trapped in combustible cartridge cases during manufacture and released into the interior-ballistic flow ...

UK PubMed Central (United Kingdom)

The causes of autoimmune responses leading to human kidney pathology remain unknown. However, environmental agents such as microorganisms and/or xenobiotics are good candidates for that role. Metals,...Full Text Available

International Nuclear Information System (INIS)

A method is described for immobilizing or solidifying waste material, which includes blending the waste material with powdered metal and subjecting the mixture of waste material and powdered metal to high pressure. (author).

KoreaScience (Korea)

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Science.gov (United States)

Environmental monitoring data were collected at and around the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) at the Nevada Test Site. These data are associated with radiation exposure, air, groundwater, meteorology, vadose zone, subsidence, and biota. This report summarizes the 2006 environmental data to provide an overall evaluation of RWMS performance and to support environmental compliance and performance assessment (PA) activities. Some of these data (e.g., radiation exposure, air, and groundwater) are presented in other reports (U.S. Department of Energy, 2006; Warren and Grossman, 2007; National Security Technologies, LLC, 2007). Direct radiation monitoring data indicate that exposure levels around the RWMSs are at or below background levels. Air monitoring data at the Area 3 and Area 5 RWMSs indicate that tritium concentrations are slightly above background levels. There is no detectable man-made radioactivity by gamma spectroscopy, and concentrations of americium ...

International Nuclear Information System (INIS)

Purpose: To assess long-term outcomes following percutaneous transluminal angioplasty (PTA) of congenital aortic coarctation in adults.Methods: Seventeen patients underwent PTA for symptomatic adult coarctation of the aorta. Sixteen patients, with a mean age of 28 years (range 15-60 years), were reviewed at a mean interval after angioplasty of 7.3 years (range 1.5-11 years). Assessment included magnetic resonance imaging (MRI), Doppler echocardiography, and clinical examination. Current clinical measurements were compared with pre- and immediate post-angioplasty measurements.Results: At follow-up 16 patients were alive and well. The patient not included in follow-up had undergone surgical repair and excision of the coarctation segment following PTA. Mean brachial systolic blood pressure for the group decreased from 174 mmHg before angioplasty to 130 mmHg at follow-up (p 0.0001). The mean gradient had fallen significantly from 50.9 to 17.8 at follow-up (p = 0.001). The average number of ...

Environmental Research Database

ObjectivesObjectives Not AvailableDescriptionWe will study the electrodeposition of metals from solutions containing a~%~ mixture of metal cations, in order to discover the conditions which lead to the separation of the metals. Measurements will be made both using small glass cells and using a more realistic size (10 cm x 10 cm electrodes) of electrodeposition cell.~%~

Science.gov (United States)

Not Available

KoreaScience (Korea)

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International Science & Technology Center (ISTC)

Development of the Technology to Obtain Pure Metal Scandium by Thermal Decomposition of Scandium Iodide

KoreaScience (Korea)

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J-STORE (Japan)

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Energy Technology Data Exchange (ETDEWEB)

According to the present invention, a joined product is at least two ceramic parts, specifically bi-element carbide parts with a bond joint therebetween, wherein the bond joint has a metal silicon phase. The bi-element carbide refers to compounds of MC, M.sub.2 C, M.sub.4 C and combinations thereof, where M is a first element and C is carbon. The metal silicon phase may be a metal silicon carbide ternary phase, or a metal silicide.

KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

A decrease of inhibitor concentration in a medium is always desirable even if the inhibitor is not toxic. In this connection, a sharp increase in the protective effect of certain corrosion inhibitors when cathodic polarization was applied to the metal is reviewed. The importance of a simultaneous account of the chemical structure of inhibitor and the nature of the metal corrosion under cathodic polarization is outlined. Some examples of applying this combined protection of metals are discussed.

KoreaScience (Korea)

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International Nuclear Information System (INIS)

This patent describes the producing of a refractory metal wherein a sponge refractory metal is produced as an intermediate product by the use of magnesium with the incidental production of magnesium chloride, and wherein residual magnesium is separated from the magnesium chloride and from refractory metal to a vacuum distillation step which fractionally distills the magnesium, the magnesium chloride, and the metal sub-chlorides; the steps of: recovering fractionally distilled vapors of magnesium chloride and metal sub-chlorides from a sponge refractory metal; separately condensing the vapors as separately recovered; and recycling the separately recovered magnesium at a purity of at least about 96%.

Energy Technology Data Exchange (ETDEWEB)

Thermal hydraulics of a liquid metal is important to design the blanket of a magnetic confined fusion reactor. Since a liquid metal has high thermal and electrical conductivity, the flow characteristics are often different from those of an ordinary liquid like water especially in thermal convection and under a magnetic field. It is difficult to simulate such flows in a liquid metal cooled blanket by water. Flow visualization is a popular method to study thermal hydraulics. Since most of metals are visible by neutron rays, neutron radiography is available to the flow visualization of a liquid metal. The purpose of this study is to develop a visualization technique of the flow in a liquid metal by real-time neutron radiography using the tracer and the dye injection methods. A real-time thermal neutron radiography system of JRR-3M in Japan Atomic Energy Research ...

Energy Technology Data Exchange (ETDEWEB)

In order to develop the filler metal for Hastelloy alloy XR structure with thick wall, the weldability and high temperature strength properties of Hastelloy alloy XR weldment were investigated using the filler metals, which were alloy-designed on the basis of multiple regression analysis. The former was examined through the chemical analysis in the deposited metal, bend test, FISCO cracking test, optical microscopy and hardness measurement. The latter was investigated by means of tensile and creep test. It was found from these results that the crack susceptibility in the weldment was apparent to be lowered without degrading the high temperature strength properties. Therefore, it is concluded that these filler metals possess excellent performance as the filler metal for Hastelloy alloy XR structure with thick wall. (author).

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Titanium is the most biocompatible metal used for dental casting; however, there is concern about its marginal accuracy after porcelain application since this aspect has direct influence on marginal fit. Purpose The purpose of this study was to determine the effect that metal selection and the porcelain firing procedure have on the marginal accuracy of metal ceramic prostheses. Material and methods Cast CP Ti, milled CP Ti, cast Ti-6Al-7Nb, and cast Ni-Cr copings (n=5) were fired with compatible porcelains (Triceram for titanium-based metals and VITA VMK 95 for Ni-Cr alloy). The Ni-Cr alloy fired with its porcelain served as the control. Photographs of metal copings placed on a master die were made. Marginal discrepancy was determined on the photographs using an image ...

Energy Technology Data Exchange (ETDEWEB)

Estuaries and coastal regions are highly variable in the physical and hydrographic conditions. As a result of heavy urbanization and industrialization of the head waters of most estuaries, there are substantial localized inputs of contaminants to the estuary. These factors combined with the flushing characteristics of individual estuaries to create relatively unique features that result in variation in the typical levels of trace metals for these systems. This makes intercomparison of the estuaries difficult. Comparability among estuaries becomes even more difficult when metals analyses are conducted without proper control of field and laboratory contamination, now firmly established in the trace metal analytical literature as a prerequisite for reliable marine trace metals analysis. This paper compares the concentrations of selected trace metal (Ag, Cd, Cu, Ni, Pb, and Zn) ...

Energy Technology Data Exchange (ETDEWEB)

This patent describes a process for preparing of an ion exchanger, comprising: treating an ionically inert activated charcoal porous support with an aqueous solution of metal oxychloride selected from the group consisting of zirconium and titanium oxychlorides so as to impregnate the pores of the support with the solution; separating the treated support from excess metal oxychloride solution; converting the metal oxychloride to a hydrous metal oxide precipitate in the pores of the support at a pH above 8 and above the pH whereat the hydrous metal oxide and activated charcoal support have opposite zeta potentials and sufficient to hydrolyze the metal oxychloride. It also describes a process for preparing an ion exchanger comprising: treating granulated activated charcoal with a concentrated solution of a metal oxychloride from the group ...

International Nuclear Information System (INIS)

Benthic invertebrates can uptake metals through diffusion of free ion solutes, or ingestion of sediment-bound forms. This study investigated the efficacy of the metal chelating resin SIR 300TM in adsorbing porewater metals and isolating pathways of metal exposure. A field experiment (Botany Bay, Sydney, Australia) and a laboratory toxicity test each manipulated the availability of porewater metals within contaminated and uncontaminated sediments. It was predicted that within contaminated sediments, the resin would adsorb porewater metals and reduce toxicity to invertebrates, but in uncontaminated sediments, the resin would not significantly affect these variables. Whereas in the laboratory, the resin produced the predicted results, in the field the resin increased porewater metal concentrations of contaminated sediments for at least 34 days ...

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Abstract Introduction - It is estimated that about 70-80% of the world's population relies on non-conventional medicine, mainly of herbal origin. However, owing to the nature and sources of herbal medicines, they are sometimes contaminated with toxic heavy metals such as lead, arsenic, mercury and cadmium, which impose serious health risks to consumers. It is critical to analyse source materials for heavy metals in order to ensure that their concentrations meet the related standards or regulations limiting their concentrations in herbal medicines. In this review, different analytical methods for analysis of heavy metals in herbal medicines are discussed. Objective - To provide a comprehensive review of the current state of the art in analytical methods used to detect heavy metals in herbal...

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In this paper heavy metal pollution at an abandoned Italian pyrite mine has been investigated by comparing total concentrations and speciation of heavy metals (Fe, Cu, Mn, Zn, Pb and As) in a red mud sample and a river sediment. Acid digestions show that all the investigated heavy metals present larger concentrations in the sediment than in the tailing. A modified Tessier's procedure has been used to discriminate heavy metal bound to organic fraction from those originally present in the mineral sulphide matrix and to detect a possible trend of metal mobilisation from red mud to river sediment. Sequential extractions on bulk and size fractionated samples denote that sediment samples present larger percent concentrations of the investigated heavy metals in the first extractive steps (I-IV) especially in lower dimension size fractionated samples suggesting ...

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A field survey on cadmium, lead, copper, and zinc was performed in Semarang, the fifth largest city in Indonesia. Water, sediment, and fish samples were collected from 101 grids of 2 x 2 km. The objectives of the study were (1) to identify the spatial distribution of metals in the sediments of the greater Semarang area, (2) to estimate the background concentrations of the metals present in Semarang, (3) to provide a simple tool for deriving standards for metals in the sediment, and (4) to explore the potential use of the guppy (Lebistes reticulatus) as a bioindicator of urban metal pollution. To map the spatial distribution of the metals, concentrations of each metal in sediment were plotted against the corresponding city coordinate. On the basis of these plots, background concentrations of the metals were estimated. A combined pollution ...

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W have introduced template-synthesized metal phosphate nanoparticle labels for electrochemical immunoassay. Such use of an apoferritin template offers a simple and convenient route to prepare metallic nanoparticle labels for electrochemical immunoassays and avoid the complicated and time-consuming nanoparticle synthesis process (QD synthesis). Releasing metal ions from metal phosphate in an acetate buffer (pH 4.6) eliminates the harsh condition in the traditional metallic nanoparticle dissolution (e.g., strong acid dissolution of QDs and gold nanoparticles). This method is ultrasensitive and its DL is low to 77fM. The simultaneous detection of multiple protein targets is easily performed by using different metal phosphate nanoparticle labels (cadmium phosphate and lead phosphate). This approach can be extended to prepare multiple metal (such ...

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Recently, the development of shape memory alloy (SMA) actuators, in the forms of wire, thin film and stent have been found increasingly in the fields of materials science and smart structures and engineering. The increase in attraction for using these materials is due to their many unique materials, mechanical, thermal and thermal-mechanical properties, which in turn, evolve their subsequent shape memory, pseudo-elasticity and super-elasticity properties. In this paper, a common type of SMA actuator, Nitinol wires, were embedded into advanced composite structures to modulate the structural dynamic responses, in terms of natural frequency and damping ratio by using its shape memory and pseudo-elastic properties. A simple theoretical model is introduced to estimate the natural frequency of the structures before and after actuating the embedded SMA wires. The damping ratios of different SMA composite beams were measured through experimental approaches. The natural ...

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RADIANT{trademark} is manufactured by United States Surgical Corporation, Vascular Therapies Division, (formerly Progressive Angioplasty Systems). The system comprises a liquid {beta}-radiation source, a shielded isolation/transfer device (ISAT), modified over-the-wire or rapid exchange delivery balloons, and accessory kits. The liquid {beta}-source is Rhenium-188 in the form of sodium perrhenate (NaReO{sub 4}), Rhenium-188 is primarily a {beta}-emitter with a physical half-life of 17.0 hours. The maximum energy of the {beta}-particles is 2.1 MeV. The source is produced daily in the nuclear pharmacy hot lab by eluting a Tungsten-188/Rhenium-188 generator manufactured by Oak Ridge National Laboratory (ORNL). Using anion exchange columns and Millipore filters the effluent is concentrated to approximately 100 mCi/ml, calibrated, and loaded into the (ISAT) which is subsequently transported to the cardiac catheterization laboratory. The delivery catheters are modified Champion{trademark} ...

British Library Electronic Table of Contents (United Kingdom)

Metal iodates with a lone-pair containing I(V) that is in an asymmetric coordination geometry can form a diversity of unusual structures and many of them are promising new second homonic generation (SHG) materials. They exhibit wide transparency wavelength regions, large SHG coefficients and high optical-damage thresholds as well as moderately high thermal stability. In this paper, the structures and properties of the metal iodates are reviewed. The combination of d0 transition-metal cations with the iodate groups afforded a large number of metal iodates, with cations covering alkali metal, alkaline earth and lanthanide elements. Many of them are noncentrosymmetric (NCS) and display excellent SHG properties due to the additive effects of polarizations from both types of the asymmetric unit...

British Library Electronic Table of Contents (United Kingdom)

Iron, zinc, copper and manganese are essential metals for cellular enzyme functions while cadmium, mercury and the metalloid arsenic lack any biological function. Both, essential metals, at high concentrations, and non-essential metals and metalloids are extremely reactive and toxic. Therefore, plants have acquired specialized mechanisms to sense, transport and maintain essential metals within physiological concentrations and to detoxify non-essential metals and metalloids. This review focuses on the recent identification of transporters that sequester cadmium and arsenic in vacuoles and the mechanisms mediating the partitioning of these metal(loid)s between roots and shoots. We further discuss recent models of phloem-mediated long-distance transport, seed accumulation of Cd and As and rec...

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A metal matrix is inserted into a phase-change material to enhance the heat transfer during phase-change processes. The metal matrix tends to act like a heat transfer fin from the heated or cooled surface and to increase the effective thermal conductivity of the phase-change fluid. The scope of the study involves numerically modeling the heat transfer to and from constant-temperature cylindrical tubes surrounded by water during the freezing and melting processes. Comparisons of heat transfer with and without the metal matrix are made, with different porosities and densities of the metal matrix being examined. The results of this study are discussed in terms of the effectiveness of the metal matrix as a heat transfer enhancement device.

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The green mussel Perna viridis and the clam Ruditapes philippinarum have been frequently used as biomonitors of coastal contamination in subtropical and tropical waters, yet the physiological processes controlling metal uptake in these bivalves are unknown. Assimilation efficiency (AE) is an important physiological parameter quantifying metal bioavailability from ingested food. The authors determined the AEs of Cd, CR, and Zn in these bivalves feeding on five species of phytoplankton and one natural section. The influences of the cytoplasmic distribution of metals in the algal cells and the digestive physiology of bivalves on metal AEs were also examined. Among the three metals, Zn was generally assimilated at the highest efficiency, i.e., 21 to 36% in the mussels and 29 to 59% in the clams. Cr was the least assimilated metal, with AEs being 10 to 16% in the ...

UK PubMed Central (United Kingdom)

Disposable nappies (diapers) have been satisfactorily demineralized and used for the collection of excreta from infants and young children during mineral and trace metal balances. It was possible to...Full Text Available

UK PubMed Central (United Kingdom)

We have developed a method to extract and separate phytochelatins (PCs)—metal(loid) complexes using parallel metal(loid)-specific (inductively coupled plasma-mass spectrometry) and organic-specific...Full Text Available

International Nuclear Information System (INIS)

The variation in the superconducting properties of various binary alloys of transition metal-germanium systems was surveyed by studying sputter deposited samples prepared under various conditions. The primary interest has been to study the formation of the stoichiometric A-15 compounds T_3Ge.

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This paper addresses one source of degradation in OPV devices: the metal/organic interface. The basic approach was to study the completed device stability vs. the stability of the organic film itself as shown in subsequent devices fabricated from the films.

UK PubMed Central (United Kingdom)

The response of the dissimilatory metal-reducing bacterium Shewanella alga BrY to carbon and nitrogen starvation was examined. Starvation resulted in a gradual decrease in the mean cell volume from...Full Text Available

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Objective is to study the effects of local structure, interatomic forces, and atom size on the mobility of metal atoms in amorphous silica and at the silica surface. EXAFS studies of Zn and Pt in silica are reported. (DLC)

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The estimation of numerical values of the mean distance of closest approach of ions, a, of alkaline-earth metal ion salts in aqueous solutions, determined from activity coefficients, as well as from different theoretical approaches, is presented and discussed.

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Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are being investigated, developed, and characterized. The tasks comprising these investigations are outlined.

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The biological accumulation of heavy metals and cesium, strontium, and uranium in plants is discussed. The role of nutrient deficiencies and foliar treatments of manganese and iron compounds is described.

International Nuclear Information System (INIS)

A mathematical interaction model, validated by experimental results, was developed to modeling the metal uptake by plants and induced growth decrease, by knowing metal in soils. The model relates the dynamics of the uptake of metals from soil to plants. Also, two types of relationships are tested: total and available metal content. The model successfully fitted the experimental data and made it possible to predict the threshold values of total mortality with a satisfactory approach. Data are taken from soils treated with Cd and Ni for ryegrass (Lolium perenne, L.) and oats (Avena sativa L.), respectively. Concentrations are measured in the aboveground biomass of plants. In the latter case, the concentration of metals in different parts of the plants (tillering, shooting and earing) is also modeled. At low concentrations, the effects of metals are moderate, and ...

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A process for the generation of halogens from halide-containing solutions includes the step of conducting electrolysis of the solutions in an electrolytic cell having a platinum based amorphous metal alloy anode.

UK PubMed Central (United Kingdom)

BackgroundEvidence on human semen quality as it relates to exposure to various metals, both essential (e.g., zinc, copper) and nonessential (e.g., cadmium, lead), is inconsistent....Full Text Available

Science.gov (United States)

Methods of acidizing a subterranean well formation, acidizing compositions, and sequestering additives for preventing the precipitation of metal compounds in the formation are described. Use of the methods and chemicals described should lead to improved formation permeability as compared to use of previous methods and chemicals. 12 claims.

Science.gov (United States)

A detection theory is developed for point-contact metal-oxide-metal (MOM) systems. A system with heterogeneous oxide strongly bonded to the substrate is considered. It is shown that the form of the functional connection between the barrier heights and the ultimate compressive strength of the oxide has no substantial influence on the voltage-current characteristics of the system. Quantitative analysis indicates that a MOM system can behave as a tunnel diode and as a diode with a Schottky barrier. The model permits the determination of the optimum construction of long-life detectors based on MOM point-contacts.-

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A total of 272 tap water samples were collected from 68 homes throughout the city of Tehran. Analysis for cadmium, zinc, lead, copper, arsenic, iron and manganese showed some accumulation of these metals in household piping overnight. However, the concentration of all metals was in the parts per billion (ug/l) range and well below international standards. Heavy metals in Tehran's drinking water therefore, do not pose a significant acute health hazard. 19 references, 2 tables.

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Separations of metal ions on the basis of Donnan dialysis across anion-exchange membranes should be possible if the receiver electrolyte composition favors the formation of selected anionic complexes of the sample metal ions. Moreover, such a separation has the possibility of being better suited from some applications than batch or column experiments with anion-exchange resins. The above hypothesis are tested on the platinum-group metal ions, Pt(IV), Rh(III), Pd(II), Ir(III), and Ir(IV). 13 references, 4 tables.

International Nuclear Information System (INIS)

Slovak May 1981. p. 30. Czechoslovakia Sandrik, R. Kliment, V.

International Nuclear Information System (INIS)

Russian 2010 p. 382 Ukraine Yuferov, VB Ozerov, AN Ponomarev,

Energy Technology Data Exchange (ETDEWEB)

We report a study of the nonmetal-metal transition of free-standing Pd{sub N} clusters (2{<=}N{<=}21) carried out through two different theoretical approaches that are extensively employed in electronic structure calculations: a semi-empirical tight-binding (TB) model and an ab initio DFT pseudopotential model. The calculated critical size for the metallic transition decreases rapidly with the temperature and an oscillatory dependence with the cluster size is obtained, particularly in the DFT approach. The TB model describes the metallic behavior for cluster sizes beyond N{approx}12 well. Our obtained critical size at room temperature is of the order of the experimental estimation.

International Nuclear Information System (INIS)

... fast reactors fbr type reactors fuels liquid metal cooled reactors materials nuclear

International Nuclear Information System (INIS)

1999 p. 148 Lebanon Saad, Zeinab Commission Libanaise d'Energie Atomique,

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The Cu- and Ni-based bulk metallic glass matrix composites were fabricated by spark plasma sintering of a mixture of gas-atomized metallic glass powders and ductile brass powders. The brass powders added for the enhancement of plasticity are well distributed in the matrix after consolidation. The matrix of the composite materials remains as a fully amorphous phase after consolidation process. With increasing the brass content, the level of plasticity strain increased, although the level of strength decreased. The successful consolidation of metallic glass matrix composite with high density was attributed to viscous flow in the supercooled liquid state during spark plasma sintering.

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Objective of the project is characterization of electrode reactions in molten salt by using metal oxides and silica-based electrode. The scope of project are characterization of metal oxide properties in molten salt and miniaturization of 3-electrode electrochemical test cell. Electrochemical micro-cell for actinide-LiCl-KCl molten salt was newly designed. Electroless and electrochemical deposition technique was applied to Mo coating on quartz tube. From the design of electrode and 3-electrode electrochemical cell suitable for the tests in molten salt electrolyte, so it is anticipated to get the information on the electrochemical behavior of metallic electrode in molten salt and to secure the information on oxidation/reduction behavior of actinide

Science.gov (United States)

... reverse aeb 9 nescesmsy amI identify by block number) Provides procedures for evaluating metal, consumable, and combustible cartridge cases. ...

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A small scale biomass metal contacting experiment was performed to screen the optimal plant species for biosorption and bioaccumulation of cadmium, zinc, nickel, lead, and copper. Experiments were also conducted to test the ability of the biomass to lower the metal concentrations below the US Environmental Protection Agency surface water discharge criteria. The minimum residual concentration was 0.1 mg/L for zinc, 0.004 mg/L for lead, and about 0.01 mg/L for cadmium, nickel, and lead. Results indicate that water milfoil can be used for bioremoval of metals.

Science.gov (United States)

Decoupling force exerted by magnetic forming Be coil assembly on metallic plate during forming

Medline Plus

... energy. It consists of a stack of piezoelectric ceramics sandwiched under high pressure between two metal cylinders. ...

Science.gov (United States)

... Casting Explosive forming Forging Electrohydraulic forming Extruding Magnetic forming Rolling Electroforming Drawing Powdered metal forming ...

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The applicability of the electro-slag melting method for treating plutonium contaminated metallic waste was studied. A 100kg test furnace was built and simulated metallic waste was melted and solidified in this furnace. Waste volume was reduced to 1/25 with a decontamination factor of 25 and the slag and the copper mold are repeatedly usable. The process is expected to be employed in the project of PWTF (Plutonium contaminated Waste Treatment Facilities).

UK PubMed Central (United Kingdom)

Some acylhydrazine derived ONO donor Schiff bases and their Co(II) and Ni(II) complexes have been prepared having the same metal ion (cation) but different anions. These synthesized metal(II)...Full Text Available

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The addition of titanium to eutectic braze compositions causes these alloys to readily wet and bond to A1N ceramics. Electron microscopic characterizations of the metal-ceramic interfaces reveal the presence of TiN, along with other Ti- and Al-containing phases. The formation of such interfacial reaction products is an additional thermodynamic driving force for the creation of useful metal-ceramic bonds. 12 refs., 4 figs., 1 tab.

International Nuclear Information System (INIS)

Preparation and electrocatalytic reactions of nano porous materials in biodegradable fluids were studied. Electrochemical etching was conducted to selectively extract metallic elements from alloys to form porous structures. Electrocatalytic properties of the porous electrodes were characterized. Comparative studies on the electrochemical activities of the nano porous metallic electrodes with bulk metallic wire catalysts were performed. It is found that the current density at the nano porous electrode is three times higher than that of the bulk electrode

International Nuclear Information System (INIS)

Our studies on K#beta#/K#alpha# X-ray intensity ratios of some of the technologically important 3d-transition metal compounds have been reviewed. Comparison of the experimental results with single-configuration Dirac-Fock calculations provided important information on the valence states of the transition metals in various compounds, which can be helpful in understanding the nature of bonding in the compounds. (author)

International Nuclear Information System (INIS)

Technological processes of welding are significant sources of pollution in the working area. Evaluation of chemical quality of working area was made by means of radionuclide x-ray fluorescence analysis and activation analysis with fast neutrons. Welding aerosols were sampled by filtration method on Synpor 4 membrane ultra-filters. For selected types of welding filter metals, determination of heavy metals in aerosols was performed. (author).

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This document contains a listing of the written scientific information originating in the Materials Joining (formerly the Welding and Brazing Group), Metals and Ceramics Division, Oak Ridge National Laboratory during 1951 through June 1989. This registry of documents is as much as possible, in the order of issue date. A complete cross-referenced listing of the technical literature of the Metals and Ceramics Division is also available.

UK PubMed Central (United Kingdom)

PurposeTo identify those metallothionein and α-crystallin/small heat-shock genes induced by toxic metals in human lens cells and to evaluate...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The Cu/CeO{sub 2} and Cu/Cr/CeO{sub 2} catalysts synthesized using the impregnation method were employed to investigate the selective reduction of NO{sub x} with C{sub 3}H{sub 6} at 673.15K and 1atm. The activity of CeO{sub 2} was greatly induced by loading 4wt.% of Cu onto the bare support. The presence of C{sub 3}H{sub 6} was a crucial factor for elevating the NO{sub x} conversion under lean conditions. The modification of the optimal Cu(4)/CeO{sub 2} catalyst with 3wt.% of Cr steadily improved the performance of the catalysts. Both the optimal Cu(4)/CeO{sub 2} and Cu(4)/Cr(3)/CeO{sub 2} catalysts were characterized using XRD, SEM and TPR-H{sub 2}. The co-existence of CuO, Cr{sub 2}O{sub 3} and CuCr{sub 2}O{sub 4} was believed to grant the promising performance of the Cu(4)/Cr(3)/CeO{sub 2} catalyst in SCR-HC under net oxidizing conditions.

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The passivity and breakdown of passivity of 1018 carbon steel in propylene carbonate (PC) and 1,2-dimethoxyethane (DME) mixtures with 0.5 molar lithium hexafluoroarsenate supporting electrolyte were examined via several electrochemical and surface analytical methods. The PC-DME/0.5 M LiAsF{sub 6} mixtures ranged from 10 to 90 mol % PC. The results from the PC/DME mixtures were compared to passivating mechanisms found in pure PC and DME solutions. In PC-rich mixtures, the breakdown of passivity occurred near the oxidation potentials of either organic solvent. Premature breakdown of the carbon steel in PC-DME mixtures occurred at sulfide inclusions as was observed earlier in PC/0.5 M LiAsF{sub 6} solutions although passive films attempted to form at these inclusion sites in mixtures containing at least 10 mol % DME. As the DME content increased in the PC-DME mixtures, the passive films formed on bare steel surfaces possessed an increasing polymer film character. In ...

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Chromium nitride/Cr coating has been deposited on surface of 316L stainless steel to improve conductivity and corrosion resistance by physical vapor deposition (PVD) technology. Electrochemical behaviors of the chromium nitride/Cr coated 316L stainless steel are investigated in 0.05 M H{sub 2}SO{sub 4}+2 ppm F{sup -} simulating proton exchange membrane fuel cell (PEMFC) environments, and interfacial contact resistance (ICR) are measured before and after potentiostatic polarization at anodic and cathodic operation potentials for PEMFC. The chromium nitride/Cr coated 316L stainless steel exhibits improved corrosion resistance and better stability of passive film either in the simulated anodic or cathodic environment. In comparison to 316L stainless steel with air-formed oxide film, the ICR between the chromium nitride/Cr coated 316L stainless steel and carbon paper is about 30 m{omega} cm{sup 2} that is about one-third of bare 316L stainless steel at the compaction ...

International Nuclear Information System (INIS)

The evolution of metallic substance atomic structure is studied on temperature variation including crystal heating up to melting points, a crystal- liquid phase transition and initiation of a high-density liquid specific structure. It is marked that heat induced changes of simple metal structure can be described as changes around a natural elementary cell which is common for both a crystal and a liquid and consists of a central atom and Z_1 atoms of the first coordination sphere. On this basis the vacancy model of melting is verified. Concentrations of melting vacancies are determined by coordination numbers in the form of Z_1/(1+Z_1)"2 which are the same for both a crystal and a natural elementary cell. The size of natural elementary cells is in an agreement with that of the coordination sphere featured in the liquid and phase transition statistical theory. Calculated data are given for a number of metals, Cs, Eu, Ni, V ...

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Supercritical CO2 is used as a new solvent for immersion deposition, a galvanic displacement process traditionally carried out in aqueous HF solutions containing metal ions, to selectively develop metal films on featured or non-featured silicon substrates. Components of supercritical fluid immersion deposition (SFID) solutions for fabricating Cu and Pd films on silicon substrates are described along with the corresponding experimental setup and procedure. Only silicon substrates exposed and reactive to SFID solutions can be coated. The highly pressurized and gas-like supercritical CO2, combined with the galvanic displacement property of immersion deposition, enables the SFID technique to selectively deposit metal films in small features. SFID may also provide a new method to fabricate palladium silicide in small features or to metallize porous silicon.

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A method for preparing metal for heating by infrared radiance to enable uniform and consistent heating. The surface of one or more metal parts, such as aluminum or aluminum alloy parts, is treated to alter the surface finish to affect the reflectivity of the surface. The surface reflectivity is evaluated, such as by taking measurements at one or more points on the surface, to determine if a desired reflectivity has been achieved. The treating and measuring are performed until the measuring indicates that the desired reflectivity has been achieved. Once the treating has altered the surface finish to achieve the desired reflectivity, the metal part may then be exposed to infrared radiance to heat the metal part to a desired temperature, and that heating will be substantially consistent throughout by virtue of the desired reflectivity.

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The interfaces between metal electrodes and electroactive organic materials are important for the performance of organic electronic devices. One way of optimizing the anode/organic interface is the insertion of a (sub-)monolayer of molecular acceptors. Here we present an UPS study of new electron acceptor molecules deposited on Au(111), Cu(111) and Ag(111). This study intends to improve the understanding of how the interactions of specific electron withdrawing groups with metal surfaces are correlated with observed modifications of interfacial electron density distribution, work function change ({delta}{phi}), and the energy level alignment. We find that {delta}{phi}, which is the difference between the work function ({phi}) of the clean metal surface and {phi} after formation of a molecular monolayer, is a monotonic function of initial {phi} of the metal. Two different slopes were observed for ...

Wastenet

...ISO - ISO Standards - TC 156 - Corrosion of metals and alloys go to main navigation go to content area go to search International Standards for Business,...ISO Members FAQs Fr ISO Store Products ISO Standards By TC TC 156 Corrosion of metals and alloys ISO Store ISO Standards By ICS By ...aerospace standards Publications and e-products ISO Concept Database (ISO/CDB) Copyright TC 156 - Corrosion of metals and alloys Items to be displayed: Published ...responsibility of TC 156 Secretariat Standard and/or project Stage ICS 3ISO/WD 7441 Corrosion of metals and alloys Determination of bimetallic corrosion in outdoor ...

British Library Electronic Table of Contents (United Kingdom)