| 1. |
- Giri, Asis, et al.
(författare)
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Analysis of bubble dynamics in explosive boiling of droplet with fine fragmentation
- 2005
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 29:3, s. 295-303
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Tidskriftsartikel (refereegranskat)abstract
- If a high temperature liquid comes into contact with cold and volatile liquid, rapid (or explosive) evaporation may occur spontaneously or triggered by the impact of a pressure wave. This event generating a shock wave is called a steam explosion. It involves many multiphase flow and heat transfer phenomena. One of the more important phenomena in a steam explosion is the fine fragmentation of the hot liquid, which determines the explosive heat transfer from the hot liquid to the cold liquid and the vaporisation rate of the cold liquid. When a small hot single drop (similar to1 mm) interacts with the coolant, a vapour bubble is formed around the drop. It was observed experimentally that these vapour bubbles grow and collapse. During this process, the small hot droplet fragments and generates finer particles. To understand the fine fragmentation process during a steam explosion, in this study, this phenomenon was examined by using non-linear stability analysis of vapour bubble dynamics based on a concept developed by Inoue et al. [Chem. Eng. Commun. 118 (1992) 189]. From the analysis, it was observed that higher spherical modes were very much unstable during collapse process, which decided the size of the fragmented particles. Vapour shell between molten metal and coolant was considered unstable if the amplitude of one of the spherical modes was greater than vapour shell thickness. In addition, the mass of fragmented particles during each cycle of vapour bubble dynamics was predicted from the analysis. The calculated results were found to be in reasonable agreement with the previously reported [J. Non-Equil. Thermodyn. 13 (1988) 27] experimental results.
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| 2. |
- Gudbjartsson, Daniel F., et al.
(författare)
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Sequence variants affecting eosinophil numbers associate with asthma and myocardial infarction
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 41:3, s. 342-347
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Tidskriftsartikel (refereegranskat)abstract
- Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of inflammatory responses and thus have important roles in the pathogenesis of inflammatory diseases. Here we describe a genome-wide association scan for sequence variants affecting eosinophil counts in blood of 9,392 Icelanders. The most significant SNPs were studied further in 12,118 Europeans and 5,212 East Asians. SNPs at 2q12 (rs1420101), 2q13 (rs12619285), 3q21 (rs4857855), 5q31 (rs4143832) and 12q24 (rs3184504) reached genome-wide significance (P = 5.3 x 10(-14), 5.4 x 10(-10), 8.6 x 10(-17), 1.2 x 10(-10) and 6.5 x 10(-19), respectively). A SNP at IL1RL1 associated with asthma (P = 5.5 x 10(-12)) in a collection of ten different populations (7,996 cases and 44,890 controls). SNPs at WDR36, IL33 and MYB that showed suggestive association with eosinophil counts were also associated with atopic asthma (P = 4.2 x 10(-6), 2.2 x 10(-5) and 2.4 x 10(-4), respectively). We also found that a nonsynonymous SNP at 12q24, in SH2B3, associated significantly (P = 8.6 x 10(-8)) with myocardial infarction in six different populations (6,650 cases and 40,621 controls).
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| 3. |
- Hansson Concilio, Roberta, et al.
(författare)
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Dynamics and preconditioning in a single drop vapor explosion
- 2007
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Ingår i: Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12. - 0894480588 - 9780894480584
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Konferensbidrag (refereegranskat)abstract
- In order to develop a mechanistic understanding of the thermal-hydraulic processes in vapor explosion, it is paramount to characterize the dynamics of the hot liquid (melt) drop fragmentation and the volatile liquid (coolant) vaporization. In the present study, these intricate phenomena are investigated by performing well-controlled, externally triggered, single-drop experiments, employing a high-speed digital visualization system with synchronized cinematography and X-ray radiography system called SHARP (Simultaneous High-speed Acquisition of X-ray Radiography and Photography). The processed images, after an elaborate image processing, revealed the internal structure and dynamic evolution of the hot liquid fragmentation and related vaporization of the coolant. Such data gives way to new insights into the physics of the vapor explosion phenomena and quantification of the associated dynamic micro interactions. Analysis of the experimental results shows that, followed an external perturbation (trigger), a high temperature molten material (tin) drop underwent deformation and partial fragmentation already during the first cycle of bubble growth. Analysis of the SHARP data reveals correlation between the drop's dynamics in the first bubble cycle and energetics of the subsequent explosive evaporation in the second cycle. This finding provides a basis to suggest a so-called melt drop preconditioning i.e. deformation/ pre-fragmentation of a hot melt drop immediately following the pressure trigger, being instrumental to the subsequent coolant entrainment and resulting energetics of the so-triggered drop explosion.
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| 4. |
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| 5. |
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| 6. |
- Hansson, Roberta Concilio, et al.
(författare)
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Dynamics and preconditioning in a single-droplet vapor explosion
- 2009
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Ingår i: Nuclear Technology. - 0029-5450 .- 1943-7471. ; 167:1, s. 223-234
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to develop a mechanistic understanding of the thermal-hydraulic processes in a vapor explosion, which may occur in nuclear power plants during a hypothetical severe accident, involving interactions of high-temperature corium melt and volatile coolant. Dynamics of the hot liquid (melt) droplet and the volatile liquid (coolant) were investigated in the Micro-Interactions in Steam Explosion Experiments (MISTEE) facility by performing well-controlled, externally triggered, single-droplet experiments, using a high-speed visualization system with synchronized digital cinematography and continuous X-ray radiography, called Simultaneous High-speed Acquisition of X-ray Radiography and Photography (SHARP). After an elaborate image processing, the SHARP images depict the evolution of both melt material (dispersal) and coolant (bubble dynamics) and their microscale interactions. The analysis of the data shows a deficiency in using the bubble dynamics alone to provide a consistent explanation of the energetic behavior. In contrast, the SHARP data reveal a correlation between the droplet's dynamics in the bubble's first cycle and the energetics of the subsequent explosive evaporation in the bubble's second cycle. The finding provides a basis to suggest that a so-called melt-droplet preconditioning, i.e., deformation/prefragmentation of a hot melt droplet immediately following the pressure trigger, is instrumental to the subsequent coolant entrainment, evaporation, and energetics of the resulting vapor explosion.
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| 7. |
- Hansson, Roberta Concilio, et al.
(författare)
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Simultaneous high speed digital cinematographic and X-ray radiographic imaging of a intense multi-fluid interaction with rapid phase changes
- 2009
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 33:4, s. 754-763
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Tidskriftsartikel (refereegranskat)abstract
- As typical for the study of the vapor explosions, the qualitative and quantitative understanding of the phenomena requires visualization of both material and interface dynamics. A new approach to multifluid multiphase visualization is presented with the focus on the development of a synchronized highspeed visualization by digital cinematography and X-ray radiography. The developed system, named SHARP (simultaneous high-speed acquisition of X-ray radiography and photography), and its image processing methodology, directed to an image synchronization procedure and a separate quantification of vapor and molten material dynamics, is presented in this paper. Furthermore, we exploit an intrinsic property of the X-ray radiation, namely the differences in linear mass attenuation coefficients over the beam path through a multi-component system, to characterize the evolution of molten material distribution. Analysis of the data obtained by the SHARP system and image processing procedure developed granted new insights into the physics of the vapor explosion phenomena, as well as, quantitative information of the associated dynamic micro-interactions.
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| 8. |
- Ju, Jin Sung, et al.
(författare)
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A novel 40-kDa protein containing six repeats of an epidermal growth factor-like domain functions as a pattern recognition protein for lipopolysaccharide
- 2006
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 177:3, s. 1838-1845
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Tidskriftsartikel (refereegranskat)abstract
- Determination of structures and functions of pattern recognition proteins are important for understanding pathogen recognition mechanisms in host defense and for elucidating the activation mechanism of innate immune reactions. In this study, a novel 40-kDa protein, named LPS recognition protein (LRP), was purified to homogeneity from the cell-free plasma of larvae of the large beetle, Holotrichia diomphalia. LRP exhibited agglutinating activities on Escherichia coli, but not on Staphylococcus aureus and Candida albicans. This E. coli-agglutinating activity was preferentially inhibited by the rough-type LPS with a complete core oligosaccharide. LRP consists of 317 aa residues and six repeats of an epidermal growth factor-like domain-Recombinant LRP expressed in a baculovirus system also showed E. coli agglutination activity in vitro and was able to neutralize LPS by inhibition of LPS-induced IL-6 production in mouse bone marrow mast cells. Furthermore, E. coli coated with the purified LRP were more rapidly cleared in the Holotrichia larvae than only E. coli, indicating that this protein participates in the clearance of E. coli in vivo. The three amino-terminal epidermal growth factor-like domains of LRP, but not the three carboxyl epidermal growth factor-like domains, are involved in the LPS-binding activity. Taken together, this LRP functions as a pattern recognition protein for LPS and plays a role as an innate immune protein.
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| 9. |
- Kim, Chan-Hee, et al.
(författare)
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A three-step proteolytic cascade mediates the activation of the peptidoglycan-induced toll pathway in an insect
- 2008
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 283:12, s. 7599-7607
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Tidskriftsartikel (refereegranskat)abstract
- The recognition of lysine-type peptidoglycans (PG) by the PG recognition complex has been suggested to cause activation of the serine protease cascade leading to the processing of Spätzle and subsequent activation of the Toll signaling pathway. So far, two serine proteases involved in the lysine-type PG Toll signaling pathway have been identified. One is a modular serine protease functioning as an initial enzyme to be recruited into the lysine-type PG recognition complex. The other is the Drosophila Spätzle processing enzyme (SPE), a terminal enzyme that converts Spätzle pro-protein to its processed form capable of binding to the Toll receptor. However, it remains unclear how the initial PG recognition signal is transferred to Spätzle resulting in Toll pathway activation. Also, the biochemical characteristics and mechanism of action of a serine protease linking the modular serine protease and SPE have not been investigated. Here, we purified and cloned a novel upstream serine protease of SPE that we named SAE, SPE-activating enzyme, from the hemolymph of a large beetle, Tenebrio molitor larvae. This enzyme was activated by Tenebrio modular serine protease and in turn activated the Tenebrio SPE. The biochemical ordered functions of these three serine proteases were determined in vitro, suggesting that the activation of a three-step proteolytic cascade is necessary and sufficient for lysine-type PG recognition signaling. The processed Spätzle by this cascade induced antibacterial activity in vivo. These results demonstrate that the three-step proteolytic cascade linking the PG recognition complex and Spätzle processing is essential for the PG-dependent Toll signaling pathway.
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| 10. |
- Park, Hyun Sun, et al.
(författare)
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Fine fragmentation of molten droplet in highly subcooled water due to vapor explosion observed by X-ray radiography
- 2005
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 29:3, s. 351-361
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Tidskriftsartikel (refereegranskat)abstract
- Experimental investigation of the fine fragmentation process during vapor explosion was conducted in a single drop system employing continuous high-speed X-ray radiography and photography. A molten tine drop of 0.7 g at 1000 degreesC was dropped into a water pool, at highly subcooled temperatures of about 20 degreesC, and the explosion was triggered by an external shock pulse of about 1 MPa. X-ray radiographs show that a shell of finely fragmented melt particles accelerates to the vapor bubble boundary during the period of vapor bubble expansion in the explosion process. For tests with highly subcooled coolant, a local explosion due to an external trigger pulse resulted in the stratified explosion along the melt surface. An analysis to estimate mixing depth during the stratified explosion indicated that about 20% of droplet mass was fragmented due to the stratified explosion with a 1 MPa trigger pulse. Finely particles generated during the vapor explosion process were quantified from high-speed X-ray radiography images.
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