| 1. |
- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 2. |
- Romanelli, F, et al.
(författare)
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Overview of the JET results
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Tidskriftsartikel (refereegranskat)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
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| 3. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Birgisson, Hakon, et al.
(författare)
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Two new thermostable alpha-L-rhamnosidases from a novel thermophilic bacterium
- 2004
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 34:6, s. 561-571
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Tidskriftsartikel (refereegranskat)abstract
- Two new thermostable alpha-L-rhamnosidases with novel substrate hydrolysis pattern were cloned and expressed from a new thermophilic bacterium. Fragments of the two alpha-L-rhamnosidase genes, rhmA and rhmB were identified in a partially sequenced genome of the bacterium. Whole genes were recovered by amplifying flanking sequences with single specific primers and nonspecific walking primers. The recovered Genes were then cloned into Escherichia coli and their enzymes produced and purified. Both enzymes were dimers and the MW of the monomers. were 104 and 107 kDa for RhmA and RhmB, respectively. Both rhamnosidases had a temperature optimum at 70degreesC. RhmA had pH optimum at 7.9 and RhmB had a broad pH optimum of 5.0 to 6.9 and RhmA had over 50% activity in the pH interval 5.0 to 8.7 and RhmB in the pH interval 4.0 to 7.9. Both enzymes had over 20% residual activity after 24-h incubation at 60degreesC. RhmA and RhmB had K values of 0.46 and 0.66 mM and V-max values of 134 and 352 U mg(-1) respectively, on p-nitrophenyl-alpha-L-rhamnopyrano side. Both rhamnosidases were active on both alpha-1,2- and alpha-1,6-linkages to beta-D-glucoside. (C) 2004 Elsevier Inc. All rights reserved.
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| 5. |
- Bjork, I, et al.
(författare)
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Differential changes in the association and dissociation rate constants for binding of cystatins to target proteinases occurring on N-terminal truncation of the inhibitors indicate that the interaction mechanism varies with different enzymes
- 1994
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Ingår i: Biochemical Journal. - 0264-6021. ; 299, s. 219-225
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Tidskriftsartikel (refereegranskat)abstract
- The importance of the N-terminal region of human cystatin C or chicken cystatin for the kinetics of interactions of the inhibitors with four cysteine proteinases was characterized. The association rate constants for the binding of recombinant human cystatin C to papain, ficin, actinidin and recombinant rat cathepsin B were 1.1 x 10(7), 7.0 x 10(6), 2.4 x 10(6) and 1.4 x 10(6) M-1.s-1, whereas the corresponding dissociation rate constants were 1.3 x 10(-7), 9.2 x 10(-6), 4.6 x 10(-2) and 3.5 x 10(-4) s-1. N-Terminal truncation of the first ten residues of the inhibitor negligibly affected the association rate constant with papain or ficin, but increased the dissociation rate constant approx. 3 x 10(4)- to 2 x 10(6)-fold. In contrast, such truncation decreased the association rate constant with cathepsin B approx. 60-fold, while minimally affecting the dissociation rate constant. With actinidin, the truncated cystatin C had both an approx. 15-fold lower association rate constant and an approx. 15-fold higher dissociation rate constant than the intact inhibitor. Similar results were obtained for intact and N-terminally truncated chicken cystatin. The decreased affinity of human cystatin C or chicken cystatin for cysteine proteinases after removal of the N-terminal region is thus due to either a decreased association rate constant or an increased dissociation rate constant, or both, depending on the enzyme. This behaviour indicates that the contribution of the N-terminal segment of the two inhibitors to the interaction mechanism varies with the target proteinase as a result of structural differences in the active-site region of the enzyme.
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| 6. |
- Cardoso-Moreira, Margarida, et al.
(författare)
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Gene expression across mammalian organ development
- 2019
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Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 571:7766, s. 505-
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of gene expression in mammalian organ development remains largely uncharacterized. Here we report the transcriptomes of seven organs (cerebrum, cerebellum, heart, kidney, liver, ovary and testis) across developmental time points from early organogenesis to adulthood for human, rhesus macaque, mouse, rat, rabbit, opossum and chicken. Comparisons of gene expression patterns identified correspondences of developmental stages across species, and differences in the timing of key events during the development of the gonads. We found that the breadth of gene expression and the extent of purifying selection gradually decrease during development, whereas the amount of positive selection and expression of new genes increase. We identified differences in the temporal trajectories of expression of individual genes across species, with brain tissues showing the smallest percentage of trajectory changes, and the liver and testis showing the largest. Our work provides a resource of developmental transcriptomes of seven organs across seven species, and comparative analyses that characterize the development and evolution of mammalian organs.
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| 7. |
- Pavlova, A, et al.
(författare)
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Cystatin inhibition of cathepsin B requires dislocation of the proteinase occluding loop. Demonstration by release of loop anchoring through mutation of His110
- 2000
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Ingår i: FEBS Letters. - 1873-3468. ; 487:2, s. 156-156
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Tidskriftsartikel (refereegranskat)abstract
- Cystatins A and C were both shown to inhibit cathepsin B by a two-step mechanism, involving an initial weak interaction followed by a conformational change. Disruption of the major salt bridge anchoring the occluding loop of cathepsin B to the main body of the enzyme by mutation of His110 to Ala converted the binding to an apparent one-step reaction. The second step of cystatin binding to cathepsin B must therefore be due to the inhibitor having to alter the conformation of the enzyme by displacing the occluding loop to allow a tight complex to be formed. Cystatin A was appreciably less effective in displacing the loop than cystatin C, resulting in a considerably lower overall inhibition rate constant.
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