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- Danielsson, Erik, et al.
(författare)
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Simulation and electrical characterization of GaN/SiC and AlGaN/SiC heterodiodes
- 1999
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Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 61-62, s. 320-324
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Tidskriftsartikel (refereegranskat)abstract
- Heterojunctions on SiC is an area in rapid development, especially GaN/SiC and AlGaN/SiC heterojunctions. The heterojunction can improve the performance considerably for BJTs and FETs. In this work heterojunction diodes have been manufactured and characterized. The structure was a GaN or AlGaN n-type region on top of a 6H-SiC p-type substrate. Two different approaches of growing the n-type region were tested. The GaN was grown with the MBE technique using a polycrystalline GaN buffer, whereas the AlGaN was grown with CVD and an AlN buffer. The AlGaN had an aluminum mole fraction of around 0.1. Mesa structures were formed using Cl2 RIE of GaN/AlGaN, which showed good selectivity on 6H-SiC (about 1:6). A Ti metallization with subsequent RTA was used as contact to GaN and AlGaN, and the contact to 6H-SiC was liquid InGa. Both I-V and C-V measurements were performed on the heterojunction diode. The ideality factor of the diodes, doping concentration of the SiC, and the band alignment of the heterojunction were extracted. © 1999 Elsevier Science S.A.
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| 3. |
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| 4. |
- Breitholtz, E, et al.
(författare)
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Cognitions in generalized anxiety disorder and panic disorder patients. A prospective approach
- 1999
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Ingår i: BEHAVIOUR RESEARCH AND THERAPY. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0005-7967. ; 37:6, s. 533-544
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Self-observations of cognitions during episodes of anxiety were examined in 38 patients with generalized anxiety disorder and 36 patients with panic disorder. Two independent observers who where blind to the diagnoses categorised the cognitions. The inte
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| 5. |
- Breitholtz, M., et al.
(författare)
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Ten challenges for improved ecotoxicological testing in environmental risk assessment
- 2006
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 63:2, s. 324-335
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Forskningsöversikt (refereegranskat)abstract
- New regulations, in particular the new European chemicals legislation (REACH), will increase the demands on environmental risk assessment (ERA). The requirements on efficient ecotoxicological testing systems are summarized, and 10 major issues for the improvement of ERA practices are discussed, namely: (1) the choice of representative test species, (2) the development of test systems that are relevant for ecosystems in different parts of the world, (3) the inclusion of sensitive life stages in test systems, (4) the inclusion of endpoints on genetic variation in populations, (5) using mechanistic understanding of toxic effects to develop more informative and efficient test systems, (6) studying disruption in invertebrate endocrine mechanisms, that may differ radically from those we know from vertebrates, (7) developing standardized methodologies for testing of poorly water-soluble substances, (8) taking ethical considerations into account, in particular by reducing the use of vertebrates in ecotoxico logical tests, (9) using a systematic (statistical) approach in combination with mechanistic knowledge to combine tests efficiently into testing systems, and (10) developing ERA so that it provides the information needed for precautionary decision-making.
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| 8. |
- Di Paolo, Carolina, et al.
(författare)
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Bioassay battery interlaboratory investigation of emerging contaminants in spikedwater extracts : Towards the implementation of bioanalytical monitoring tools inwater quality assessment and monitoring
- 2016
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 104, s. 473-484
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Tidskriftsartikel (refereegranskat)abstract
- Bioassays are particularly useful tools to link the chemical and ecological assessments in water quality monitoring. Different methods cover a broad range of toxicity mechanisms in diverse organisms, and account for risks posed by non-target compounds and mixtures. Many tests are already applied in chemical and waste assessments, and stakeholders from the science-police interface have recommended their integration in regulatory water quality monitoring. Still, there is a need to address bioassay suitability to evaluate water samples containing emerging pollutants, which are a current priority in water quality monitoring. The presented interlaboratory study (ILS) verified whether a battery of miniaturized bioassays, conducted in 11 different laboratories following their own protocols, would produce comparable results when applied to evaluate blinded samples consisting of a pristine water extract spiked with four emerging pollutants as single chemicals or mixtures, i.e. triclosan, acridine, 17α-ethinylestradiol (EE2) and 3-nitrobenzanthrone (3-NBA). Assays evaluated effects on aquatic organisms from three different trophic levels (algae, daphnids, zebrafish embryos) and mechanism-specific effects using in vitro estrogenicity (ER-Luc, YES) and mutagenicity (Ames fluctuation) assays. The test battery presented complementary sensitivity and specificity to evaluate the different blinded water extract spikes. Aquatic organisms differed in terms of sensitivity to triclosan (algae > daphnids > fish) and acridine (fish > daphnids > algae) spikes, confirming the complementary role of the three taxa for water quality assessment. Estrogenicity and mutagenicity assays identified with high precision the respective mechanism-specific effects of spikes even when non-specific toxicity occurred in mixture. For estrogenicity, although differences were observed between assays and models, EE2 spike relative induction EC50 values were comparable to the literature, and E2/EE2 equivalency factors reliably reflected the sample content. In the Ames, strong revertant induction occurred following 3-NBA spike incubation with the TA98 strain, which was of lower magnitude after metabolic transformation and when compared to TA100. Differences in experimental protocols, model organisms, and data analysis can be sources of variation, indicating that respective harmonized standard procedures should be followed when implementing bioassays in water monitoring. Together with other ongoing activities for the validation of a basic bioassay battery, the present study is an important step towards the implementation of bioanalytical monitoring tools in water quality assessment and monitoring.
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| 9. |
- Galeckas, A., et al.
(författare)
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Application of optical emission microscopy for reliability studies in 4H-SiC p(+)/n(-)/n(+) diodes
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:2, s. 980-984
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Tidskriftsartikel (refereegranskat)abstract
- An optical emission microscopy technique with spatial and spectral resolution capabilities is applied for stability studies of 4H-SiC material properties. From the example of a 4H-SiC p(+)/n(-)/n(+) diode imaged at different stages of electrical overstress the mechanism of degrading performance is directly unveiled. We correlate this phenomenon with irreversible structural changes within the active region created by a nonuniform heating related stress. The stress-generated features are interpreted as multiple stacking faults spreading throughout the whole base region and nucleated in the vicinity of built-in defects and process-induced structural deficiencies.
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