| 1. |
- Andersen, Ken, et al.
(författare)
-
B-10 multi-grid proportional gas counters for large area thermal neutron detectors
- 2013
-
Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002 .- 1872-9576. ; 720, s. 116-121
-
Tidskriftsartikel (refereegranskat)abstract
- He-3 was a popular material in neutrons detectors until its availability dropped drastically in 2008. The development of techniques based on alternative convertors is now of high priority for neutron research institutes. Thin films of B-10 or (B4C)-B-10 have been used in gas proportional counters to detect neutrons, but until now, only for small or medium sensitive area. We present here the multi-grid design, introduced at the ILL and developed in collaboration with ESS for LAN (large area neutron) detectors. Typically thirty (B4C)-B-10 films of 1 mu m thickness are used to convert neutrons into ionizing particles which are subsequently detected in a proportional gas counter. The principle and the fabrication of the multi-grid are described and some preliminary results obtained with a prototype of 200 cm x 8 cm are reported; a detection efficiency of 48% has been measured at 2.5 angstrom with a monochromatic neutron beam line, showing the good potential of this new technique. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Niemelä, Matti, et al.
(författare)
-
Randomized Comparison of Final Kissing Balloon Dilatation Versus No Final Kissing Balloon Dilatation in Patients With Coronary Bifurcation Lesions Treated With Main Vessel Stenting : The nordic-baltic bifurcation study III
- 2011
-
Ingår i: Circulation. - 0009-7322 .- 1524-4539. ; 123:1, s. 79-86
-
Tidskriftsartikel (refereegranskat)abstract
- Background-It is unknown whether the preferred 1-stent bifurcation stenting approach with stenting of the main vessel (MV) and optional side branch stenting using drug-eluting stents should be finalized by a kissing balloon dilatation (FKBD). Therefore, we compared strategies of MV stenting with and without FKBD. Methods and Results-We randomized 477 patients with a bifurcation lesion to FKBD (n=238) or no FKBD (n=239) after MV stenting. The primary end point was major adverse cardiac events: cardiac death, non-procedure-related index lesion myocardial infarction, target lesion revascularization, or stent thrombosis within 6 months. The 6-month major adverse cardiac event rates were 2.1% and 2.5% (P=1.00) in the FKBD and no-FKBD groups, respectively. Procedure and fluoroscopy times were longer and more contrast media was needed in the FKBD group than in the no-FKBD group. Three hundred twenty-six patients had a quantitative coronary assessment. At 8 months, the rate of binary (re) stenosis in the entire bifurcation lesion (MV and side branch) was 11.0% versus 17.3% (P=0.11), in the MV was 3.1% versus 2.5% (P=0.68), and in the side branch was 7.9% versus 15.4% (P=0.039) in the FKBD versus no-FKBD groups, respectively. In patients with true bifurcation lesions, the side branch restenosis rate was 7.6% versus 20.0% (P=0.024) in the FKBD and no-FKBD groups, respectively. Conclusions-MV stenting strategies with and without FKBD were associated with similar clinical outcomes. FKBD reduced angiographic side branch (re) stenosis, especially in patients with true bifurcation lesions. The simple no-FKBD procedures resulted in reduced use of contrast media and shorter procedure and fluoroscopy times. Long-term data on stent thrombosis are needed. Clinical Trial Registration-URL: http://clinicaltrials.gov. Unique identifier: NCT00914199. (Circulation. 2011;123:79-86.)
|
|
| 3. |
- Hsiao, Ching-Lien, et al.
(författare)
-
Room-temperature heteroepitaxy of single-phase Al1-xInxN films with full composition range on isostructural wurtzite templates
- 2012
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 524, s. 113-120
-
Tidskriftsartikel (refereegranskat)abstract
- Al1-xInxN heteroepitaxial layers covering the full composition range have been realized by magnetron sputter epitaxy on basal-plane AlN, GaN, and ZnO templates at room temperature (RT). Both Al1-xInxN single layers and multilayers grown on these isostructural templates show single phase, single crystal wurtzite structure. Even at large lattice mismatch between the film and the template, for instance InN/AlN (similar to 13% mismatch), heteroepitaxy is achieved. However, RT-grown Al1-xInxN films directly deposited on non-isostructural c-plane sapphire substrate exhibit a polycrystalline structure for all compositions, suggesting that substrate surface structure is important for guiding the initial nucleation. Degradation of Al1-xInxN structural quality with increasing indium content is attributed to the formation of more point-and structural defects. The defects result in a prominent hydrostatic tensile stress component, in addition to the biaxial stress component introduced by lattice mismatch, in all RT-grown Al1-xInxN films. These effects are reflected in the measured in-plane and out-of-plane strains. The effect of hydrostatic stress is negligible compared to the effects of lattice mismatch in high-temperature grown AlN layers thanks to their low amount of defects. We found that Vegards rule is applicable to determine x in the RT-grown Al1-xInxN epilayers if the lattice constants of RT-sputtered AlN and InN films are used instead of those of the strain-free bulk materials.
|
|
| 4. |
- Höglund, Carina, et al.
(författare)
-
B4C thin films for neutron detection
- 2012
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 111:10
-
Tidskriftsartikel (refereegranskat)abstract
- Due to the very limited availability of He-3, new kinds of neutron detectors, not based on 3He, are urgently needed. Here, we present a method to produce thin films of (B4C)-B-10, with maximized detection efficiency, intended to be part of a new generation of large area neutron detectors. B4C thin Films have been deposited onto Al-blade and Si wafer substrates by dc magnetron sputtering from (B4C)-B-nat and (B4C)-B-10 targets in an Ar discharge, using an industrial deposition system. The films were characterized with scanning electron microscopy, elastic recoil detection analysis, x-ray reflectivity, and neutron radiography. We show that the film-substrate adhesion and film purity are improved by increased substrate temperature and deposition rate. A deposition rate of 3.8 angstrom/s and substrate temperature of 400 degrees C result in films with a density close to bulk values and good adhesion to film thickness above 3 mu m. Boron-10 contents of almost 80 at. % are obtained in 6.3 m(2) of 1 mu m thick (B4C)-B-10 thin films coated on Al-blades. Initial neutron absorption measurements agree with Monte Carlo simulations and show that the layer thickness, number of layers, neutron wavelength, and amount of impurities are determining factors. The study also shows the importance of having uniform layer thicknesses over large areas, which for a full-scale detector could be in total similar to 1000 m(2) of two-side coated Al-blades with similar to 1 mu m thick (B4C)-B-10 films.
|
|
| 5. |
- Höglund, Carina, et al.
(författare)
-
Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions
- 2010
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 81:22, s. 224101-
-
Tidskriftsartikel (refereegranskat)abstract
- Thin solid films of metastable rocksalt structure (c-) Sc1-xAlxN and Ti1-xAlxN were employed as model systems to investigate the relative influence of volume mismatch and electronic structure driving forces for phase separation. Reactive dual magnetron sputtering was used to deposit stoichiometric Sc0.57Al0.43N(111) and Ti0.51Al0.49N(111) thin films, at 675 °C and 600 °C, respectively, followed by stepwise annealing to a maximum temperature of 1100 °C. Phase transformations during growth and annealing were followed in situ using X-ray scattering. The results show that the as-deposited Sc0.57Al0.43N films phase separate at 1000 °C – 1100 °C into non-isostructural c-ScN and wurtzite-structure (w-) AlN, via nucleation and growth at domain boundaries. Ti0.51Al0.49N, however, exhibits spinodal decomposition into isostructural coherent c-TiN and c-AlN, in the temperature interval of 800 °C – 1000 °C. X-ray pole figures show the coherency between c-ScN and w-AlN, with AlN(0001) || ScN(001) and AlN<01ɸ10> || ScN<1ɸ10>. First principles calculations of mixing energy-lattice spacing curves explain the results on a fundamental physics level and open a route for design of novel metastable pseudobinary phases for hard coatings and electronic materials.
|
|
| 6. |
- Jensen, Ulf J., et al.
(författare)
-
The role of a simulator-based course in coronary angiography on performance in real life cath lab
- 2014
-
Ingår i: BMC Medical Education. - : Springer Science and Business Media LLC. - 1472-6920. ; 14, s. 49-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The aim of this study was to explore if a course consisting of lectures combined with simulator training in coronary angiography (CA) could accelerate the early learning curve when performing CA on patients. Knowledge in performing CA is included in the curriculum for the general cardiologist. The method, according to American College of Cardiology and European Society of Cardiology guidelines, for this training is not well defined but simulator training is proposed to be an option. However, the transfer effect from a CA simulator to performance in real world cath lab is not validated. Methods: Fifty-four residents without practical skills in CA completed the course and 12 continued to training in invasive cardiology. These residents were tracked in the Swedish Coronary Angiography and Angioplasty Registry and compared to a control group of 46 novel operators for evaluation of performance metrics. A total of 4472 CAs were analyzed. Results: Course participants demonstrated no consistent acceleration in the early learning curve in real world cath lab. They had longer fluoroscopy time compared to controls (median 360 seconds (IQR 245-557) vs. 289 seconds (IQR 179-468), p < 0.001). Safety measures also indicated more complications appearing at the ward, in particular when using the femoral approach (6.25% vs. 2.53%, p < 0.001). Conclusions: Since the results of this retrospective non-randomized study were negative, the role of a structured course including simulator training for skills acquisition in CA is still uncertain. Randomized transfer studies are warranted to justify further use of simulators for training in CA
|
|
| 7. |
- Jensen, Ulf J., et al.
(författare)
-
The use of fluoroscopy to construct learning curves for coronary angiography
- 2012
-
Ingår i: Catheterization and cardiovascular interventions. - : Wiley. - 1522-1946 .- 1522-726X. ; 80:4, s. 564-569
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives:The aim of this study was to assess learning curves for coronary angiography using registry data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR).Background:ACC and ESC guidelines for cardiologists in training recommend 200300 coronary angiographies as primary operator. Whether this is safe or sufficient to reach an adequate proficiency level is not known. The development of learning curves and factors that can determine progress is not yet clearly stated.Methods:We extracted data from SCAAR 20052009 and identified 20 novel and 21 expert operators in coronary angiography during this observation period. Metrics possibly influenced by proficiency level were compared between the two groups. Learning curves were then identified with the expert's performance as reference defined as interquartile range (IQR).Results:Data from a total of 24,000 coronary angiographies were examined. Beginners used similar volumes of contrast but had longer fluoroscopy time compared with experts. Fluoroscopy time appeared to be a metric that demonstrated a clear learning curve and beginners reached experts IQR in 50 % (median) of the procedures after similar to 140 coronary angiographies. The risk of complications was independently associated with fluoroscopy time.Conclusions:Fluoroscopy time seems to be the best metric to determine coronary angiography performance level and might therefore be a good proficiency measure during training. On the basis of our results we recommend the trainee to perform at least 150 coronary angiographies during supervision before proceeding with unsupervised procedures. It is not clear if the suggested number of procedures will result in decreased number of complications but the data suggests that fluoroscopy time might be a surrogate marker for complications.
|
|
| 8. |
- Jensen, Ulf, et al.
(författare)
-
Technical Skills Assessment in a Coronary Angiography Simulator for Construct Validation.
- 2013
-
Ingår i: Simulation in Healthcare: the Journal of the Society for Simulation in Healthcare. - 1559-713X. ; 8:5, s. 324-328
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The aim of this study was to evaluate technical skills in a coronary angiography (CA) simulator to establish the performance level of trainees and experts in virtual CA.The traditional master-apprentice way of learning CA is by practicing on patients despite a known risk for complications during training. Safe CA training is warranted, and simulators might be one possibility. Simulators used must be validated regarding their ability to separate trainees from experts. Construct validation of a CA simulator, to our knowledge, has not yet been published. METHODS: Ten cardiology residents without experience in CA, 4 intermediate, and 10 CA experts performed 5 CAs in the Mentice VIST (Vascular Intervention Simulation Trainer). Metrics reflecting proficiency skills such as total procedure time, fluoroscopy time, and contrast volume were extracted from the simulator computer and compared between the groups. All examinations were videotaped, and the number of handling errors was examined. The videos were evaluated by 2 experts blinded to the test object's performance level. RESULTS: Experts outperformed trainees in all metrics measured by the simulator. Improvement was demonstrated in all metrics through all 5 CAs. Furthermore, beginners had more handling errors compared with experts. CONCLUSIONS: Mentice VIST simulator can distinguish between trainees and experts in CA in the metrics extracted from the computer and therefore prove the concept of construct validity.
|
|
| 9. |
- Junaid, Muhammad, et al.
(författare)
-
Electronic-grade GaN(0001)/Al2O3(0001) grown by reactive DC-magnetron sputter epitaxy using a liquid Ga target
- 2011
-
Ingår i: Applied Physics Letters. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 98:14, s. 141915-
-
Tidskriftsartikel (refereegranskat)abstract
- Electronic-grade GaN (0001) epilayers have been grown directly on Al2O3 (0001) substrates by reactive DC-magnetron sputter epitaxy (MSE) from a liquid Ga sputtering target in an Ar/N2 atmosphere. The as-grown GaN epitaxial film exhibit low threading dislocation density on the order of ≤ 1010 cm-2 obtained by transmission electron microscopy and modified Williamson-Hall plot. X-ray rocking curve shows narrow fullwidth at half maximum (FWHM) of 1054 arcsec of the 0002 reflection. A sharp 4 K photoluminescence peak at 3.474 eV with a FWHM of 6.3 meV is attributed to intrinsic GaN band edge emission. The high structural and optical qualities indicate that MSEgrown GaN epilayers can be used for fabricating high-performance devices without the need of any buffer layer.
|
|
| 10. |
- Kerdsongpanya, Sit, et al.
(författare)
-
Anomalously high thermoelectric power factor in epitaxial ScN thin films
- 2011
-
Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 99:23, s. 232113-
-
Tidskriftsartikel (refereegranskat)abstract
- Thermoelectric properties of ScN thin films grown by reactive magnetron sputtering on Al2O3(0001) wafers are reported. X-ray diffraction and elastic recoil detection analyses show that the composition of the films is close to stoichiometry with trace amounts (similar to 1 at. % in total) of C, O, and F. We found that the ScN thin-film exhibits a rather low electrical resistivity of similar to 2.94 mu Omega m, while its Seebeck coefficient is approximately similar to-86 mu V/K at 800 K, yielding a power factor of similar to 2.5 x 10(-3) W/mK(2). This value is anomalously high for common transition-metal nitrides.
|
|
