Influence of transmutation-induced Re/Os content on defect evolution in neutron-irradiated W

The microstructure of neutron irradiated tungsten (0.1 dpa - 0.8dpa at Tirr = 1200 ◦ C,) was analyzed by transmission electron microscopy applying high-sensitivity energy dispersive X-ray spectroscopy, which enables the visualization of the distribution of transmutation induced Re and Os. The study demonstrates the dose-dependent evolution of radiation-induced defects such as voids and dislocation loops as well as segregation behavior of Re and Os at these defects. Re segregation around voids occurs at the lowest damage dose of 0.1 dpa, while their enrichment on dislocation loops was detected at 0.2 dpa. Further generation of Re and Os leads to the formation of the χ-phase ((Re,Os)3 W) precipitates with a needle shape on voids and on dislocation loops. The formation of Os-rich nuclei within Re clouds around loops or voids is crucial for the onset of precipitate for- mation. It could be shown that the subsequent formation of precipitates on dislocation loops causes the disap- pearance of the loops. Based on these results, a modification of a well-known defect formation diagram in W has been proposed as a function of the Re/Os content. This would provide a comparison of defect evolution in W irradiated in reactors with different transmutation rates. It would also allow a prediction of the microstructural evolution in W under fusion condition

Concomitant bladder tumor is a risk factor for bladder recurrence but not upper tract

Objective: To evaluate the clinical outcomes of UTUC patients with or without concurrent bladder tumor. Design, Setting, and Participants: The Clinical Research Office of the Endourology Society-Urothelial Carcinomas of the Upper Tract (CROES-UTUC) Registry included 1134 UTUC patients with or without concurrent bladder tumor treated between 2014 and 2019. Results: In 218 (19.2%) cases, concurrent bladder tumor was present, while in 916 (80.8%) patients, no bladder cancer was found. In the multivariable Cox regression analysis, concomitant bladder tumor (hazard ratio (HR) 1.562, 95% confidence interval (CI) 0.954-2.560, p = 0.076) indicated a trend associated with recurrence-free survival for UTUC. Further data dissection confirmed that concomitant bladder tumor is a risk factor of bladder recurrence (HR 1.874, 95% CI 1.104-3.183, p = 0.020) but not UTUC recurrence (HR 0.876, 95% CI 0.292-2.625, p = 0.812). Kidney-sparing surgery (KSS) (HR 3.940, 95% CI 1.352-11.486, p = 0.012), pathological T staging >= pT2 (HR 2.840, 95% 1.039-7.763, p = 0.042) were significantly associated with UTUC recurrence. KSS does not affect bladder recurrence (HR 0.619, 95% CI 0.242-1.580, p = 0.315). A limitation is the retrospective nature of the present study analysis. Conclusions: The presence of concomitant bladder tumor does not increase risk of UTUC recurrence, but it results in an increased risk of bladder recurrence. KSS does not affect bladder recurrence and can still be considered in patients with concomitant bladder tumor

Optimising the future Belgian offshore wind farm monitoring programme

Six years of monitoring triggered a reflection on how to best continue with the monitoring programme. The basic monitoring has to be rationalised at the level of the likelihood of impact detection, the meaningfulness of impact size and representativeness of the findings. Targeted monitoring should continue to disentangle processes behind the observed impact, for instance the overarching artificial reef effect created by wind farms. The major challenge however remains to achieve a reliable assessment of the cumulative impacts. Continuing consultation and collaboration within the Belgian offshore wind farm monitoring team and with foreign marine scientists and managers will ensure an optimisation of the future monitoring programme

Endothelin-1-induced constriction in the coronary resistance vessels and abdominal aorta of the guinea pig

The purpose of this study was to examine contractile properties of endothelin-1, a newly discovered vasoactive peptide, in guinea pig coronary resistance vessels and abdominal aorta. Changes in perfusion pressure after injections of endothelin-1 were measured using a constant-flow modified Langendorff preparation. The ED 10 values of coronary perfusion pressure were about 100-fold less for endothelin-1 than for prostaglandin F 2α . After the endothelium was damaged by exposure to free radicals, maximal coronary constriction in response to endothelin-1 (10 −9 moles) was not altered, whereas dilator responses to low doses of endothelin-1 were converted to constrictor responses. Removal of the endothelium from aortic rings significantly increased responsiveness to endothelin-1 and the maximal response to the peptide. In calcium-free medium, endothelin-1 induced small increases both in perfusion pressure in coronary vessles and in tension in the aorta. Reintroduction of calcium in the coronary and aortic preparations produced a rapid increase in perfusion pressure and tension, respectively. Further, endothelin-1-induced coronary constriction was inhibited 59%±7% by nifedipine (10 −7 moles). We conclude that endothelin-1 is a more potent constrictor than prostaglandin F 2α in the coronary vasculature. Endothelin-1-induced constriction in the coronary vasculature of the guinea pig is not mediated through an endogenous constricting factor released from the endothelium or a constrictor prostaglandin. Further, endothelin-1-induced dilation in the coronary vasculature and attenuation of endothelin-1-induced contraction in the abdominal aorta of the guinea pig are mediated through the release of a factor from the endothelium. Endothelin-1-induced coronary constriction and abdominal aortic contraction require extracellular calcium, entering, in part, through nifedipine-sensitive channels.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41586/1/380_2005_Article_BF02058691.pd

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

Impact of ICRF on the scrape-off layer and on plasma wall interactions: From present experiments to fusion reactor

Recent achievements in studies of the effects of ICRF (Ion Cyclotron Range of Frequencies) power on the SOL (Scrape-Off Layer) and PWI (Plasma Wall Interactions) in ASDEX Upgrade (AUG), Alcator C-Mod, and JET-ILW are reviewed. Capabilities to diagnose and model the effect of DC biasing and associated impurity production at active antennas and on magnetic field connections to antennas are described. The experiments show that ICRF near-fields can lead not only to E×B convection, but also to modifications of the SOL density, which for Alcator C-Mod are limited to a narrow region near antenna. On the other hand, the SOL density distribution along with impurity sources can be tailored using local gas injection in AUG and JET-ILW with a positive effect on reduction of impurity sources. The technique of RF image current cancellation at antenna limiters was successfully applied in AUG using the 3-strap AUG antenna and extended to the 4-strap Alcator C-Mod field-aligned antenna. Multiple observations confirmed the reduction of the impact of ICRF on the SOL and on total impurity production when the ratio of the power of the central straps to the total antenna power is in the range 0.6<P$_{cen}$/P$_{total}$<0.8. Near-field calculations indicate that this fairly robust technique can be applied to the ITER ICRF antenna, enabling the mode of operation with reduced PWI. On the contrary, for the A2 antenna in JET-ILW the technique is hindered by RF sheaths excited at the antenna septum. Thus, in order to reduce the effect of ICRF power on PWI in a future fusion reactor, the antenna design has to be optimized along with design of plasmafacing components

Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum

The identification of the sources of atomic tungsten and the measurement of their radiation distribution in front of all plasma-facing components has been performed in JET with the help of two digital cameras with the same two-dimensional view, equipped with interference filters of different bandwidths centred on theW I (400.88 nm) emission line. A new algorithm for the subtraction of the continuum radiation was successfully developed and is now used to evaluate the W erosion even in the inner divertor region where the strong recombination emission is dominating over the tungsten emission. Analysis of W sputtering and W redistribution in the divertor by video imaging spectroscopy with high spatial resolution for three different magnetic configurations was performed. A strong variation of the emission of the neutral tungsten in toroidal direction and corresponding W erosion has been observed. It correlates strongly with the wetted area with a maximal W erosion at the edge of the divertor tile