| 1. |
- Bässler, Ralph, et al.
(författare)
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Electrochemical Techniques to Detect Corrosion Stage of Reinforcement in Concrete Structures : Suistainable Bridges. Background document SB3.9
- 2007
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Rapport (refereegranskat)abstract
- In order to initiate necessary rehabilitation measures at the right moment from the safety aspectas well as the economic point of view non-destructively determined information on the current corrosion behavior of the reinforcing steel have a high importance. For that various electrochemical measurement techniques are available, like measurement of corrosion potential, determination of short-circuit currents on corrosion cells, and external controlled electrochemical investigations. In passive conditions the rebar potentials can fluctuate in a wide range depending on different parameters. In some potential areas a clear classification of active (corroding) or passive conditions is not possible. In such cases measurements by Galvanostatic Pulse Method (GPM) might be supportive. Evaluation of the results enables a much better classification regarding the situation at the reinforcement. However the applicability is being discussed controversially. Basing on differences of own and literature results gathered on park decks and bridges as well as in special laboratory approaches it is necessary to evaluate the limitations on real structures. Right now there is a big skepticism in terms of correct applicability of corrosion rate measurement devices. A very good evaluation of the reinforcement corrosion behavior has been achieved in laboratory. In potential ranges, where a clear assignment to passivity or activity could not be made, GPM-technique allows a better evaluation. It can be stated, that GPM is suitable for evaluation of the corrosion rate on uniformly corroding small specimens. In case of very local corrosion spots and wide passive zones on a test plate, also a good qualitative evaluation of the corrosion stage could be achieved using potential mapping. Here it turned out that relatively small corrosion spots only can be detected by a narrow measurement grid. However an evaluation of corrosion behavior in these conditions by GPM seems to be impossible. The GPM-technique is applicable if corrosion conditions on the object are relatively uniform. Only very local corrosion spots on an almost passive structure limit the usability of the achieved values. The limitation and applicability of the technique on real structures have been evaluated on a bridge without significant corrosion.
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| 2. |
- Eich, Andreas, et al.
(författare)
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Positive association between epiphytes and competitiveness of the brown algal genus Lobophora against corals
- 2019
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Observations of coral-algal competition can provide valuable information about the state of coral reef ecosystems. Here, we report contact rates and apparent competition states for six shallow lagoonal reefs in Fiji. A total of 81.4% of examined coral perimeters were found to be in contact with algae, with turf algae (54.7%) and macroalgae of the genus Lobophora (16.8%) representing the most frequently observed contacts. Turf algae competitiveness was low, with 21.8% of coral-turf contacts being won by the algae (i.e. overgrowth or bleaching of coral tissue). In contrast, Lobophora competitiveness against corals was high, with 62.5% of contacts being won by the alga. The presence of epiphytic algae on Lobophora was associated with significantly greater algal competitiveness against corals, with 75.8% and 21.1% of interactions recorded as algal wins in the presence and absence of epiphytes, respectively. Sedimentation rate, herbivorous fish biomass, and coral colony size did not have a significant effect on Lobophora-coral interactions. This research indicates a novel and important role of epiphytes in driving the outcome of coral-algal contacts.
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| 3. |
- Kamber, Umut, et al.
(författare)
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Self-induced spin glass state in elemental and crystalline neodymium
- 2020
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 368:6494
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Tidskriftsartikel (refereegranskat)abstract
- Spin glasses are a highly complex magnetic state of matter intricately linked to spin frustration and structural disorder. They exhibit no long-range order and exude aging phenomena, distinguishing them from quantum spin liquids. We report a previously unknown type of spin glass state, the spin-Q glass, observable in bulk-like crystalline metallic neodymium thick films. Using spin-polarized scanning tunneling microscopy combined with ab initio calculations and atomistic spin-dynamics simulations, we visualized the variations in atomic-scale noncolinear order and its response to magnetic field and temperature. We quantified the aging phenomena relating the glassiness to crystalline symmetry and the energy landscape. This result not only resolves the long-standing debate of the magnetism of neodymium, but also suggests that glassiness may arise in other magnetic solids lacking extrinsic disorder.
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| 4. |
- McAndrews, Ryan S., et al.
(författare)
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Algae sediment dynamics are mediated by herbivorous fishes on a nearshore coral reef
- 2019
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Ingår i: Coral reefs (Print). - : Springer Science and Business Media LLC. - 0722-4028 .- 1432-0975. ; 38:3, s. 431-441
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Tidskriftsartikel (refereegranskat)abstract
- Epilithic algae are a ubiquitous component of coral reefs. Components of the epilithic algal matrix (EAM) can have a significant influence on coral settlement and benthic feeding by fishes. We employed a herbivore exclusion experiment on a fringing reef in Viti Levu, Fiji, to investigate the functional role of herbivorous fishes in affecting the EAM between different habitat types and levels of community-based fishing restriction. We surveyed the herbivorous fish community and deployed experimental tiles on the reef flat and lagoonal slope and inside and outside of an area where fishing is restricted (tabu). Tiles were deployed for 3months, half within cages to exclude herbivorous fishes. We then identified algal type and quantified epilithic algal turf height, sediment dry weight, and detritus within the EAM on each tile. EAM that developed under herbivory was remarkably similar, regardless of the differences in habitat or fishing restriction. In contrast, EAM within cages was characterised by longer turf, heavier sediment load, and high variance in turf length and sediment load. Habitat type played a strong role in determining EAM characteristics where herbivores were excluded. Caged EAM on the reef flat was characterised by algal turf and fleshy macroalgae, whereas EAM in cages on the lagoonal slope was overwhelmingly dominated by filamentous and mat-forming cyanobacteria. The results presented here demonstrate the importance of herbivorous fishes in maintaining a benthic environment favourable to coral settlement and survival. Our results suggest that herbivore biomass per se is not a reliable predictor of foraging activity. Moreover, these results show that the absence of herbivore foraging can have different consequences depending on the habitat type, even within the same reef.
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| 5. |
- Rechl, Victor, et al.
(författare)
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Factors Influencing the Outcome of Patients with Primary Ewing Sarcoma of the Sacrum.
- 2024
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Ingår i: Sarcoma. - 1357-714X. ; 2024
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Tidskriftsartikel (refereegranskat)abstract
- Ewing sarcoma (EwS) is a rare and highly malignant bone tumor primarily affecting children, adolescents, and young adults. The pelvis, trunk, and lower extremities are the most common sites, while EwS of the sacrum as a primary site is very rare, and only few studies focusing on this location are published. Due to the anatomical condition, local treatment is challenging in sacral malignancies. We analyzed factors that might influence the outcome of patients suffering from sacral EwS.We retrospectively analyzed data of the GPOH EURO-E.W.I.N.G 99 trial and the EWING 2008 trial, with a cohort of 124 patients with localized or metastatic sacral EwS. The study endpoints were overall survival (OS) and event-free survival (EFS). OS and EFS were calculated using the Kaplan-Meier method, and univariate comparisons were estimated using the log-rank test. Hazard ratios (HRs) with respective 95% confidence intervals (CIs) were estimated in a multivariable Cox regression model.The presence of metastases (3y-EFS: 0.33 vs. 0.68; P < 0.001; HR=3.4, 95% CI 1.7 to 6.6; 3y-OS: 0.48 vs. 0.85; P < 0.001; HR=4.23, 95% CI 1.8 to 9.7), large tumor volume (≥200ml) (3y-EFS: 0.36 vs. 0.69; P=0.02; HR=2.1, 95% CI 1.1 to 4.0; 3y-OS: 0.42 vs. 0.73; P=0.04; HR=2.1, 95% CI 1.03 to 4.5), and age ≥18years (3y-EFS: 0.41 vs. 0.60; P=0.02; HR=2.6, 95% CI 1.3 to 5.2; 3y-OS: 0.294 vs. 0.59; P=0.01; HR=2.92, 95% CI 1.29 to 6.6) were revealed as adverse prognostic factors.Young age seems to positively influence patients` survival, especially in patients with primary metastatic disease. In this context, our results support other studies, stating that older age has a negative impact on survival. Tumor volume, metastases, and the type of local therapy modality have an impact on the outcome of sacral EwS. Level of evidence: Level 2. This trial is registered with NCT00020566 and NCT00987636.
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