| 1. |
|
|
| 2. |
- Keskinen, H., et al.
(författare)
-
Evolution of Nanoparticle Composition in CLOUD in Presence of Sulphuric Acid, Ammonia and Organics
- 2013
-
Ingår i: NUCLEATION AND ATMOSPHERIC AEROSOLS. - : American Institute of Physics (AIP). - 9780735411524 ; , s. 291-294
-
Konferensbidrag (refereegranskat)abstract
- In this study, we investigate the composition of nucleated nanoparticles formed from sulphuric acid, ammonia, amines, and oxidised organics in the CLOUD chamber experiments at CERN. The investigation is carried out via analysis of the particle hygroscopicity (size range of 15-63 nm), ethanol affinity (15-50nm), oxidation state (<50 nm), and ion composition (few nanometers). The organic volume fraction of particles increased with an increase in particle diameter in presence of the sulphuric acid, ammonia and organics. Vice versa, the sulphuric acid volume fraction decreased when the particle diameter increased. The results provide information on the size-dependent composition of nucleated aerosol particles.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Buerger, M., et al.
(författare)
-
Coolability of particulate beds in severe accidents : Status and remaining uncertainties
- 2010
-
Ingår i: Progress in nuclear energy (New series). - : Elsevier BV. - 0149-1970 .- 1878-4224. ; 52:1, s. 61-75
-
Tidskriftsartikel (refereegranskat)abstract
- Particulate debris beds may form during different stages of a severe core melt accident; e.g. in the degrading hot core, due to thermal stresses during reflooding, in the lower plenum, by melt flow from the core into water in the lower head, and in the cavity by melt flow out of a failing RPV into a wet cavity. Deep water pools in the cavity are used in Nordic BWRs as an accident management measure aiming at particulate debris formation and coolability. It has been elaborated in the joint work of the European Severe Accident Research Network (SARNET) in Work Package (WP) 11.1 that coolability of particulate debris, reflooding of hot debris as well as boil-off under decay heat (long-term coolability), is strongly favoured by 2D/3D effects in beds with non-homogeneous structure and shape. Especially, water inflow from the sides and via bottom regions strongly improves coolability as compared to 1D situations with top flooding, the latter being in the past the basis of analyses on coolability. Data from experiments included in the SARNET network (DEBRIS at IKE and STYX at VTT) and earlier ones (e.g. POMECO at KTH) have been used to validate key constitutive laws in 2D codes as WABE (IKE) and ICARE/CATHARE (IRSN), especially concerning flow friction and heat transfer. Major questions concern the need of the explicit use of interfacial friction to adequately treat the various flow situations in a unified approach, as well as the adequate characterization of realistic debris composed of irregularly shaped particles of different sizes. joint work has been supported by transfer of the WABE code to KTH and VTT. Concerning realistic debris, the formation from breakup of melt jets in water is investigated in the DEFOR experiments at KTH. Present results indicate that porosities in the debris might be much higher than previously assumed, which would strongly support attainment of coolability. Calculations have been performed with IKEJET/IKEMIX describing jet breakup, mixing and settling of resulting particles. Models about debris bed formation and porosity are developed at KTH. The codes have been applied to reactor conditions for analysing the potential for coolability in the different phases of a severe accident. Calculations have been performed with WABE (MEWA) implemented in ATHLET-CD and with ICARE/ICATHARE for degraded cores and debris beds in the lower plenum, under reflooding and boil-off. Ex-vessel situations have also been analysed. Strong effects of lateral water inflow and cooling by steam in hot areas have been demonstrated. In support, some typical basic configurations have been analysed, e.g. configurations with downcomers considered as possible AM measures. Melt pool formation or coolability of particulate debris is a major issue concerning melt retention in the core and the lower head. Present conclusions from those analyses for adequate modelling in ASTEC are outlined as well as remaining uncertainties. Experimental and analysis efforts and respective continued joint actions are discussed, which are needed to reach resolution of the coolability issue.
|
|
| 7. |
|
|
| 8. |
- Kaplan, Alexander, et al.
(författare)
-
Stress raising in laser clad components depending on geometry and defects
- 2013
-
Ingår i: 14th NOLAMP Conference. - Luleå : Luleå tekniska universitet. - 9789174396881 - 9789174396898 ; , s. 281-292
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The fatigue life of laser clad components is basically determined by stress raisers, which arehere studied by Finite Element Analysis. Cylindrical and square section bars are compared foraxial, bending and torsional load conditions, which induces the macro-stress field withcorresponding stress peaks. Defects from laser cladding such as pores, cracks or the surfaceroughness superimpose additional stress raising action on this stress field. The geometricalposition and orientation of the defects has strong impact on the induced maximum stresslevel. For surface pores it is demonstrated by the fractography that their occurrence within acritical azimuthal range can initiate fatigue cracking. The different conditions of samplegeometry, load situations, materials and defects are compared and discussed. In particular,advanced illustration methods are applied for improved and generalized documentation andexplanation of the trends, both qualitatively and quantitatively. Guidelines are presented, inparticular emphasizing critical defects and situations, such as surface pores that are difficult todetect because of inclusions, or pores just underneath the surface that generate particularlyhigh stress.
|
|
| 9. |
- Latvala, S., et al.
(författare)
-
Dynamin inhibition interferes with inflammasome activation and cytokine gene expression in Streptococcus pyogenes-infected human macrophages
- 2014
-
Ingår i: Clinical and Experimental Immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 178:2, s. 320-333
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, we have analysed the ability of Streptococcus pyogenes [Group A streptococcus (GAS)] to activate the NACHT-domain-, leucinerich repeat-and PYD-containing protein 3 (NALP3) inflammasome complex in human monocyte-derived macrophages and the molecules and signalling pathways involved in GAS-induced inflammatory responses. We focused upon analysing the impact of dynamin-dependent endocytosis and the role of major streptococcal virulence factors streptolysin O (SLO) and streptolysin S (SLS) in the immune responses induced by GAS. These virulence factors are involved in immune evasion by forming pores in host cell membranes, and aid the bacteria to escape from the endosome-lysosome pathway. We analysed cytokine gene expression in human primary macrophages after stimulation with live or inactivated wild-type GAS as well as with live SLO and SLS defective bacteria. Interleukin (IL)-1 beta, IL-10, tumour necrosis factor (TNF)-alpha and chemokine (C-X-C motif) ligand (CXCL)-10 cytokines were produced after bacterial stimulation in a dose-dependent manner and no differences in cytokine levels were seen between live, inactivated or mutant bacteria. These data suggest that streptolysins or other secreted bacterial products are not required for the inflammatory responses induced by GAS. Our data indicate that inhibition of dynamin-dependent endocytosis in macrophages attenuates the induction of IL-1 beta, TNF-alpha, interferon (IFN)-beta and CXCL-10 mRNAs. We also observed that pro-IL-1 beta protein was expressed and efficiently cleaved into mature-IL-1 beta via inflammasome activation after bacterial stimulation. Furthermore, we demonstrate that multiple signalling pathways are involved in GAS-stimulated inflammatory responses in human macrophages.
|
|
| 10. |
|
|
