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| 6. |
- Bruzzi, M, et al.
(författare)
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Radiation-hard semiconductor detectors for SuperLHC
- 2005
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 541:1-2, s. 189-201
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Tidskriftsartikel (refereegranskat)abstract
- An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016cm-2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.
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| 9. |
- Novak, R., et al.
(författare)
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Robotic fluidic coupling and interrogation of multiple vascularized organ chips
- 2020
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Ingår i: Nature Biomedical Engineering. - : Nature Research. - 2157-846X.
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Tidskriftsartikel (refereegranskat)abstract
- Organ chips can recapitulate organ-level (patho)physiology, yet pharmacokinetic and pharmacodynamic analyses require multi-organ systems linked by vascular perfusion. Here, we describe an ‘interrogator’ that employs liquid-handling robotics, custom software and an integrated mobile microscope for the automated culture, perfusion, medium addition, fluidic linking, sample collection and in situ microscopy imaging of up to ten organ chips inside a standard tissue-culture incubator. The robotic interrogator maintained the viability and organ-specific functions of eight vascularized, two-channel organ chips (intestine, liver, kidney, heart, lung, skin, blood–brain barrier and brain) for 3 weeks in culture when intermittently fluidically coupled via a common blood substitute through their reservoirs of medium and endothelium-lined vascular channels. We used the robotic interrogator and a physiological multicompartmental reduced-order model of the experimental system to quantitatively predict the distribution of an inulin tracer perfused through the multi-organ human-body-on-chips. The automated culture system enables the imaging of cells in the organ chips and the repeated sampling of both the vascular and interstitial compartments without compromising fluidic coupling.
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| 13. |
- Brandsma, Joost, et al.
(författare)
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Lipid phenotyping of lung epithelial lining fluid in healthy human volunteers
- 2018
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Ingår i: Metabolomics. - : Springer-Verlag New York. - 1573-3882 .- 1573-3890. ; 14:10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lung epithelial lining fluid (ELF)-sampled through sputum induction-is a medium rich in cells, proteins and lipids. However, despite its key role in maintaining lung function, homeostasis and defences, the composition and biology of ELF, especially in respect of lipids, remain incompletely understood. Objectives: To characterise the induced sputum lipidome of healthy adult individuals, and to examine associations between different ELF lipid phenotypes and the demographic characteristics within the study cohort.Methods: Induced sputum samples were obtained from 41 healthy non-smoking adults, and their lipid compositions analysed using a combination of untargeted shotgun and liquid chromatography mass spectrometry methods. Topological data analysis (TDA) was used to group subjects with comparable sputum lipidomes in order to identify distinct ELF phenotypes.Results: The induced sputum lipidome was diverse, comprising a range of different molecular classes, including at least 75 glycerophospholipids, 13 sphingolipids, 5 sterol lipids and 12 neutral glycerolipids. TDA identified two distinct phenotypes differentiated by a higher total lipid content and specific enrichments of diacyl-glycerophosphocholines, -inositols and -glycerols in one group, with enrichments of sterols, glycolipids and sphingolipids in the other. Subjects presenting the lipid-rich ELF phenotype also had significantly higher BMI, but did not differ in respect of other demographic characteristics such as age or gender.Conclusions: We provide the first evidence that the ELF lipidome varies significantly between healthy individuals and propose that such differences are related to weight status, highlighting the potential impact of (over)nutrition on lung lipid metabolism.
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| 14. |
- Brandsma, Joost, et al.
(författare)
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Stratification of asthma by lipidomic profiling of induced sputum supernatant
- 2023
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier. - 0091-6749 .- 1097-6825. ; 152:1, s. 117-125
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Tidskriftsartikel (refereegranskat)abstract
- Background: Asthma is a chronic respiratory disease with significant heterogeneity in its clinical presentation and pathobiology. There is need for improved understanding of respiratory lipid metabolism in asthma patients and its relation to observable clinical features.Objective: We performed a comprehensive, prospective, cross-sectional analysis of the lipid composition of induced sputum supernatant obtained from asthma patients with a range of disease severities, as well as from healthy controls.Methods: Induced sputum supernatant was collected from 211 adults with asthma and 41 healthy individuals enrolled onto the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes) study. Sputum lipidomes were characterized by semiquantitative shotgun mass spectrometry and clustered using topologic data analysis to identify lipid phenotypes.Results: Shotgun lipidomics of induced sputum supernatant revealed a spectrum of 9 molecular phenotypes, highlighting not just significant differences between the sputum lipidomes of asthma patients and healthy controls, but also within the asthma patient population. Matching clinical, pathobiologic, proteomic, and transcriptomic data helped inform the underlying disease processes. Sputum lipid phenotypes with higher levels of nonendogenous, cell-derived lipids were associated with significantly worse asthma severity, worse lung function, and elevated granulocyte counts.Conclusion: We propose a novel mechanism of increased lipid loading in the epithelial lining fluid of asthma patients resulting from the secretion of extracellular vesicles by granulocytic inflammatory cells, which could reduce the ability of pulmonary surfactant to lower surface tension in asthmatic small airways, as well as compromise its role as an immune regulator.
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| 17. |
- Goss, J.P., et al.
(författare)
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Interstitial aggregates in diamond
- 2001
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Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 10:3, s. 434-438
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical modelling of magnetic resonance signals lead to convincing models for the first three self-interstitial aggregates in diamond. These in turn suggest the manner in which larger more stable aggregates including the platelet, observed in annealed type I diamonds, are formed.
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| 18. |
- Goss, J.P., et al.
(författare)
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Self-interstitial aggregation in diamond
- 2001
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 63:19, s. 195208-
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Tidskriftsartikel (refereegranskat)abstract
- First-principles methods are used to investigate the self-interstitial and its aggregates in diamond. The experimental assignment of the spin-1 R2 EPR center to the single interstitial has been questioned because of the small fine-structure term observed. We calculate the spin-spin interaction tensor for the three interstitial defects I1〈001〉, I2NN, and I3 and compare with the experimental D tensors. The results give support for the assignments of the single and di-interstitials to microscopic models and allow us to conclusively identify a recently observed EPR center, O3, with I3. This identification, in turn, suggests a low-energy structure for I4 and a generic model for an extended defect called the platelet. We also determine the optical properties of I1〈001〉 as well as its piezospectroscopic or stress tensor and find these to be in agreement with experiment. Several multi-interstitial defects are found to possess different structural forms which may coexist. We propose that a different form of the charged I2 defect gives rise to the 3H optical peak. Several structures of the platelet are considered, and we find that the lowest-energy model is consistent with microscopic and infrared studies.
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| 19. |
- Jönsson, Bo-Anders, et al.
(författare)
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EMERALD & EMIT – worldwide computer aided education and training packages in medical physics
- 2005
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Ingår i: CAL-laborate. - 1443-4482. ; 13:June, s. 10-15
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the development of two web based education and training packages EMERALD and EMIT designed to meet the training needs of professional medical physicists. The programme has been developed over a number of years by collaboration between hospitals and universities across Europe. The programme concentrates on assisting competence development in five initial areas; diagnostic radiology, nuclear medicine, magnetic resonance tomography, ultrasound and radiotherapy. Each of the topic areas includes around 50 training tasks in 5 hypertext workbooks, which are supplemented by an image database relevant to each topic. The training materials have been extensively refereed during their development and are now in use in 65 countries across the globe. Initial evaluation has shown that the material enhances the training experience and produces a more consistent output.
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| 21. |
- Pinto, H., et al.
(författare)
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First-principles studies of the effect of (001) surface terminations on the electronic properties of the negatively charged nitrogen-vacancy defect in diamond
- 2012
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 86:4
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Tidskriftsartikel (refereegranskat)abstract
- Density functional calculations have been carried out on (001)-orientated slabs of diamond with different surface terminations. A negatively charged nitrogen-vacancy defect (NV-) is placed in the middle of the slab approximately 1 nm from each surface and the effect of the surface on the internal optical transition in NV- investigated. The calculations show that the chemical nature of the surface is important. We find that although the clean surface does not lead to charge transfer between the defect and the surface, there is a splitting of the empty excited state, the final state in optical absorption, arising from a strong hybridization of the surface and defect bands. This leads to a broadening of the 1.945-eV transition of the NV- defect. OH- and F-terminated surfaces have no surface states in the band gap and again charge transfer between the defect and surface does not occur. The splitting of the e levels responsible for the optical transitions for OH or F termination is similar to that found in periodic boundary condition simulations for bulk diamond where the defects are separated by 1 nm, and thus the calculations show that hydroxylated or fluorinated surfaces give favorable optical properties.
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| 22. |
- Pinto, H., et al.
(författare)
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On the diffusion of NV defects in diamond
- 2012
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 209:9, s. 1765-1768
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Tidskriftsartikel (refereegranskat)abstract
- Besides their importance for quantum information processing, NV defects are crucial agents for the diffusion and aggregation of nitrogen in diamond. In the absence of transition metals, it is thought that the first stage of nitrogen aggregation, where close neighbour nitrogen pairs are formed, is mediated by NV defects. Here we use density functional theory to explore the barriers to NV diffusion. We conclude that the barrier is around 5 eV when there is a ready source of vacancies and that this barrier is weakly dependent on pressure.
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| 23. |
- Pinto, H., et al.
(författare)
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Theory of the surface effects on the luminescence of the NV(-) defect in nanodiamond
- 2011
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 208:9, s. 2045-2050
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Tidskriftsartikel (refereegranskat)abstract
- A vacancy with one of the carbon neighbours replaced by a nitrogen atom in diamond (the NV centre) is a defect of particular interest due to its many potential applications. In the negatively charged state, the defect is paramagnetic with spin 1 and under optical excitation it exhibits an intense luminescence with a zero-phonon line at 1.945eV. This fluorescence is found in nanodiamonds even as small as 5nm and an important question is the effect of the surface of the nanodiamond on the optical emission of NV-.Density functional calculations are used in this work to investigate the effect of the bare (001) and (001)-OH diamond surfaces on the electronic structure of NV-. We show that the (001)-OH diamond surface has the minimum interaction with the defect and is the ideal terminating surface of nanodiamonds, while the bare (001) diamond surface has a strong effect on broadening the emission.
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| 24. |
- Reed, B. P., et al.
(författare)
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Diamond (111) surface reconstruction and epitaxial graphene interface
- 2022
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Ingår i: Physical Review B. - 2469-9950. ; 105:20
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of the diamond (111) surface as it undergoes reconstruction and subsequent graphene formation is investigated with angle-resolved photoemission spectroscopy, low energy electron diffraction, and complementary density functional theory calculations. The process is examined starting at the C(111)-(2×1) surface reconstruction that occurs following detachment of the surface adatoms at 920 ∘C, and continues through to the liberation of the reconstructed surface atoms into a freestanding monolayer of epitaxial graphene at temperatures above 1000 ∘C. Our results show that the C(111)-(2×1) surface is metallic as it has electronic states that intersect the Fermi level. This is in strong agreement with a symmetrically π-bonded chain model and should contribute to resolving the controversies that exist in the literature surrounding the electronic nature of this surface. The graphene formed at higher temperatures exists above a newly formed C(111)-(2×1) surface and appears to have little substrate interaction as the Dirac point is observed at the Fermi level. Finally, we demonstrate that it is possible to hydrogen-terminate the underlying diamond surface by means of plasma processing without removing the graphene layer, forming a graphene-semiconductor interface. This could have particular relevance for doping the graphene formed on the diamond (111) surface via tuneable substrate interactions as a result of changing the terminating species at the diamond-graphene interface by plasma processing.
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| 25. |
- Tabakov, S, et al.
(författare)
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Development of educational image databases and e-books for medical physics training
- 2005
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Ingår i: Medical Engineering & Physics. - : Elsevier BV. - 1873-4030 .- 1350-4533. ; 27:7, s. 591-598
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Tidskriftsartikel (refereegranskat)abstract
- Medical physics education and training requires the use of extensive imaging material and specific explanations. These requirements provide an excellent background for application of e-Learning. The EU projects Consortia EMERALD and EMIT developed five volumes of such materials, now used in 65 countries. EMERALD developed e-Learning materials in three areas of medical physics (X-ray diagnostic radiology, nuclear medicine and radiotherapy). EMIT developed e-Learning materials in two further areas: ultrasound and magnetic resonance imaging. This paper describes the development of these e-Learning materials (consisting of e-books and educational image databases). The e-books include tasks helping studying of various equipment and methods. The text of these PDF e-books is hyperlinked with respective images. The e-books are used through the readers' own Internet browser. Each Image Database (IDB) includes a browser, which displays hundreds of images of equipment, block diagrams and graphs, image quality examples, artefacts, etc. Both the e-books and IDB are engraved on five separate CD-ROMs. Demo of these materials can be taken from www.emerald2.net.
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| 26. |
- Zhong, Cheng, et al.
(författare)
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Temporal Changes in Microbial Community Composition and Geochemistry in Flowback and Produced Water from the Duvernay Formation
- 2019
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Ingår i: ACS Earth and Space Chemistry. - : American Chemical Society (ACS). - 2472-3452. ; 3:6, s. 1047-1057
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Tidskriftsartikel (refereegranskat)abstract
- Microbial activity in flowback and produced water (FPW) may negatively influence shale oil and gas extraction. However, the impacts of using recycled produced water (RPW) for subsequent fracturing jobs are not well-understood. In this study, we compared time series of FPW samples from two horizontally fractured wells drilled into the Duvernay Formation in Alberta, Canada; well 1 used RPW in the makeup of the hydraulic fracturing fluid (HFF) whereas well 2 did not. 16S rRNA gene sequencing and live/dead cell enumeration were used to track microbial communities. Within 20 days of flowback, total dissolved solids in well 1 and well 2 increased from 5310 mg/L and 288 mg/L to over 150,000 mg/L, and FPW temperatures increased from 20 and 9 degrees C to 77 and 71 degrees C, respectively. Alkyl dimethyl benzyl ammonium chloride (biocide) in well 2 decreased from 25 mu g/L to below the detection limit of 0.5 mu g/L. Cellular biomass decreased from similar to 10(5) cells mL(-1) to less than the detection limit of 10(5) cells mL(-1) in both wells, and the community in the samples was initially diverse but rapidly shifted to become dominated by the sulfidogenic lineage Halanaerobium. Methanogens were detected at low relative abundance within archaea, with DNA concentrations in FPW after 20 days inadequate for sequencing. Comparing the two wells, the start time of Halanaerobium enrichment was considerably shortened in well 1 relative to well 2. Our results suggest that subsurface environmental parameters primarily drive the rapid enrichment of sulfidogenic and halotolerant bacteria and current recycling strategies can facilitate the growth of these bacteria, whereas biocide seems to be a less important factor in this shift.
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