| 1. |
|
|
| 2. |
- Chen, Jr-Tai, et al.
(författare)
-
Growth optimization of AlGaN/GaN HEMT structure on 100 mm SiC substrate : Utilizing bottom-to-top approach
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The structure of high electron mobility transistors (HEMTs) based on group-III nitride materials generally consists of three important blocks; a nucleation layer, a semi-insulating (SI) GaN buffer layer, and active layers. In this work, we present an overall growth optimization, which leads to superior crystalline quality and ultra-low thermal boundary resistance (TBR) of a 35-nm AlN nucleation layer, excellent crystalline quality of carbon-doped GaN buffer layer, and high mobility (> 2000 cm2/Vs) of two-dimensional gas (2DEG) in a simple AlGaN/GaN heterostructure grown on a SI SiC substrate.
|
|
| 3. |
- Chen, Jr-Tai, et al.
(författare)
-
Room-Temperature mobility above 2200 cm2/V.s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure
- 2015
-
Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 106:25
-
Tidskriftsartikel (refereegranskat)abstract
- A high mobility of 2250 cm2/V·s of a two-dimensional electron gas (2DEG) in a metalorganic chemical vapor deposition-grown AlGaN/GaN heterostructure was demonstrated. The mobility enhancement was a result of better electron confinement due to a sharp AlGaN/GaN interface, as confirmed by scanning transmission electron microscopy analysis, not owing to the formation of a traditional thin AlN exclusion layer. Moreover, we found that the electron mobility in the sharp-interface heterostructures can sustain above 2000 cm2/V·s for a wide range of 2DEG densities. Finally, it is promising that the sharp-interface AlGaN/GaN heterostructure would enable low contact resistance fabrication, less impurity-related scattering, and trapping than the AlGaN/AlN/GaN heterostructure, as the high-impurity-contained AlN is removed.
|
|
| 4. |
- Hansson, Bengt, et al.
(författare)
-
Byggledning : produktion
- 2017
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Lärobok för ingenjörsutbildningar som inriktas på produktionsskedet av ett byggporjekt
|
|
| 5. |
- Kehoe, Laura, et al.
(författare)
-
Make EU trade with Brazil sustainable
- 2019
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- Persson, Lennart, et al.
(författare)
-
Leaky lysosomes in lung transplant macrophages: azithromycin prevents oxidative damage
- 2012
-
Ingår i: Respiratory Research. - : BioMed Central. - 1465-9921 .- 1465-993X. ; 13:83
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Lung allografts contain large amounts of iron (Fe), which inside lung macrophages may promote oxidative lysosomal membrane permeabilization (LMP), cell death and inflammation. The macrolide antibiotic azithromycin (AZM) accumulates 1000-fold inside the acidic lysosomes and may interfere with the lysosomal pool of Fe. Objective: Oxidative lysosomal leakage was assessed in lung macrophages from lung transplant recipients without or with AZM treatment and from healthy subjects. The efficiency of AZM to protect lysosomes and cells against oxidants was further assessed employing murine J774 macrophages. Methods: Macrophages harvested from 8 transplant recipients (5 without and 3 with ongoing AZM treatment) and 7 healthy subjects, and J774 cells pre-treated with AZM, a high-molecular-weight derivative of the Fe chelator desferrioxamine or ammonium chloride were oxidatively stressed. LMP, cell death, Fe, reduced glutathione (GSH) and H-ferritin were assessed. Results: Oxidant challenged macrophages from transplants recipients without AZM exhibited significantly more LMP and cell death than macrophages from healthy subjects. Those macrophages contained significantly more Fe, while GSH and H-ferritin did not differ significantly. Although macrophages from transplant recipients treated with AZM contained both significantly more Fe and less GSH, which would sensitize cells to oxidants, these macrophages resisted oxidant challenge well. The preventive effect of AZM on oxidative LMP and J774 cell death was 60 to 300 times greater than the other drugs tested. Conclusions: AZM makes lung transplant macrophages and their lysososomes more resistant to oxidant challenge. Possibly, prevention of obliterative bronchiolitis in lung transplants by AZM is partly due to this action.
|
|
| 7. |
|
|
| 8. |
- Östgren, Carl Johan, et al.
(författare)
-
Prevalence of atherosclerosis in individuals with prediabetes and diabetes compared to normoglycaemic individuals-a Swedish population-based study.
- 2023
-
Ingår i: Cardiovascular diabetology. - : BioMed Central (BMC). - 1475-2840. ; 22:1
-
Tidskriftsartikel (refereegranskat)abstract
- Patients with type 2 diabetes have an increased risk of death and cardiovascular events and people with diabetes or prediabetes have been found to have increased atherosclerotic burden in the coronary and carotid arteries. This study will estimate the cross-sectional prevalence of atherosclerosis in the coronary and carotid arteries in individuals with prediabetes and diabetes, compared with normoglycaemic individuals in a large population-based cohort.The 30,154 study participants, 50-64years, were categorized according to their fasting glycaemic status or self-reported data as normoglycaemic, prediabetes, and previously undetected or known diabetes. Prevalence of affected coronary artery segments, severity of stenosis and coronary artery calcium score (CACS) were determined by coronary computed tomography angiography. Total atherosclerotic burden was assessed in the 11 clinically most relevant segments using the Segment Involvement Score and as the presence of any coronary atherosclerosis. The presence of atherosclerotic plaque in the carotid arteries was determined by ultrasound examination.Study participants with prediabetes (n=4804, 16.0%) or diabetes (n=2282, 7.6%) had greater coronary artery plaque burden, more coronary stenosis and higher CACS than normoglycaemic participants (all, p<0.01). Among male participants with diabetes 35.3% had CACS≥100 compared to 16.1% among normoglycaemic participants. For women, the corresponding figures were 8.9% vs 6.1%. The prevalence of atherosclerosis in the coronary arteries was higher in participants with previously undetected diabetes than prediabetes, but lower than in patients with known diabetes. The prevalence of any plaque in the carotid arteries was higher in participants with prediabetes or diabetes than in normoglycaemic participants.In this large population-based cohort of currently asymptomatic people, the atherosclerotic burden in the coronary and carotid arteries increased with increasing degree of dysglycaemia. The finding that the atherosclerotic burden in the coronary arteries in the undetected diabetes category was midway between the prediabetes category and patients with known diabetes may have implications for screening strategies and tailored prevention interventions for people with dysglycaemia in the future.
|
|
| 9. |
- Alin, Niklas, 1963, et al.
(författare)
-
3D Unsteady Computations for Submarine-Like Bodies
- 2005
-
Ingår i: 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, Jan. 10-13, 2005. ; , s. 353-369
-
Konferensbidrag (refereegranskat)abstract
- Results from a computational study using Unsteady Reynolds Averaged Navier Stokes (URANS) models and Large Eddy Simulation (LES) of flows past submarine-like bodies are here presented. The aims are to evaluate URANS and LES for high-Re number hydrodynamic flows, to investigate the influence of the turbulence and subgrid turbulence modeling, and to discuss some features of submarine hydrodynamics. For this purpose we have chosen to examine the flow past a prolate spheroid at 10° and 20° angle of attack at a body length Re number of 4-106, and the flow past the DARPA-2 Suboff bare hull and fully appended hull configurations at a body length Re number of 12-106. For both cases experimental data is available for comparison. One finite element and one finite volume flow solver has been used - both with the capability of employing a range of turbulence models and with the capacity of using unstructured and hybrid grids. Better agreement between predictions and experimental data is obtained with LES than with the URANS models, but at a considerably higher price, due to the finer grids and finer temporal resolution in LES.
|
|
| 10. |
- Averfalk, Helge, 1988-
(författare)
-
Enhanced District Heating Technology : Maintaining Future System Feasibility
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- When heat demand and high temperature heat supply gradually decreases in the future, then it will effect district heating systems ability to compete on the heat market. A good way to mitigate less district heating feasibility is to operate systems with lower temperature levels and the most conceivable way to achieve lower temperature levels is to decrease return temperatures.Thus, this thesis emphasise temperature errors embedded in district heating systems. Only a selection of temperature errors are analysed in this thesis. First, the temperature error that occurs due to recirculation in distribution networks at low heat demands. Second, the temperature error that occurs due to hot water circulation in multi-family buildings. Third, the temperature error that occurs due to less than possible heat transfer in heat exchangers, i.e. too short thermal lengths.In order to address these temperature errors three technology changes have been proposed (i) three-pipe distribution network to separate the recirculation return flow from the delivery return flow, (ii) apartment substations to eliminate hot water circulation utilisation, and (iii) improved heat exchangers for lower return temperatures at a constant scenario. Analysis of proposed changes has resulted in annual average return temperatures between 17-21 °C.Furthermore, rapid introduction of intermittent renewable electricity supply in the energy system has prompted an increased necessity of power system balancing capacities. Large-scale conversion of power-to-heat in electric boilers and heat pumps is a feasible alternative to achieve such balancing capacities. Analysis of the unique Swedish experience with utilisation of large heat pumps installations connected to district heating systems show that since the 1980s 1527 MW of heat power has been installed, about 80 % of the capacity was still in use by 2013. Thus, a cumulative value of over three decades of operation and maintenance exists within Swedish district heating systems.The two papers presented in this thesis are related to future district heating systems through the five abilities of fourth generation district heating (4GDH), which are documented in the definition paper of 4GDH.
|
|
