| 1. |
- Kleineidam, Luca, et al.
(författare)
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Midlife occupational cognitive requirements protect cognitive function in old age by increasing cognitive reserve
- 2022
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Several lifestyle factors promote protection against Alzheimer's disease (AD) throughout a person's lifespan. Although such protective effects have been described for occupational cognitive requirements (OCR) in midlife, it is currently unknown whether they are conveyed by brain maintenance (BM), brain reserve (BR), or cognitive reserve (CR) or a combination of them. Methods: We systematically derived hypotheses for these resilience concepts and tested them in the population-based AgeCoDe cohort and memory clinic-based AD high-risk DELCODE study. The OCR score (OCRS) was measured using job activities based on the O*NET occupational classification system. Four sets of analyses were conducted: (1) the interaction of OCR and APOE-ε4 with regard to cognitive decline (N = 2,369, AgeCoDe), (2) association with differentially shaped retrospective trajectories before the onset of dementia of the Alzheimer's type (DAT; N = 474, AgeCoDe), (3) cross-sectional interaction of the OCR and cerebrospinal fluid (CSF) AD biomarkers and brain structural measures regarding memory function (N = 873, DELCODE), and (4) cross-sectional and longitudinal association of OCR with CSF AD biomarkers and brain structural measures (N = 873, DELCODE). Results: Regarding (1), higher OCRS was associated with a reduced association of APOE-ε4 with cognitive decline (mean follow-up = 6.03 years), consistent with CR and BR. Regarding (2), high OCRS was associated with a later onset but subsequently stronger cognitive decline in individuals converting to DAT, consistent with CR. Regarding (3), higher OCRS was associated with a weaker association of the CSF Aβ42/40 ratio and hippocampal volume with memory function, consistent with CR. Regarding (4), OCR was not associated with the levels or changes in CSF AD biomarkers (mean follow-up = 2.61 years). We found a cross-sectional, age-independent association of OCRS with some MRI markers, but no association with 1-year-change. OCR was not associated with the intracranial volume. These results are not completely consistent with those of BR or BM. Discussion: Our results support the link between OCR and CR. Promoting and seeking complex and stimulating work conditions in midlife could therefore contribute to increased resistance to pathologies in old age and might complement prevention measures aimed at reducing pathology.
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| 2. |
- Lii, Neal Y., et al.
(författare)
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Exodex Adam—A Reconfigurable Dexterous Haptic User Interface for the Whole Hand
- 2022
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Ingår i: Frontiers Robotics AI. - : Frontiers Media SA. - 2296-9144. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Applications for dexterous robot teleoperation and immersive virtual reality are growing. Haptic user input devices need to allow the user to intuitively command and seamlessly “feel” the environment they work in, whether virtual or a remote site through an avatar. We introduce the DLR Exodex Adam, a reconfigurable, dexterous, whole-hand haptic input device. The device comprises multiple modular, three degrees of freedom (3-DOF) robotic fingers, whose placement on the device can be adjusted to optimize manipulability for different user hand sizes. Additionally, the device is mounted on a 7-DOF robot arm to increase the user’s workspace. Exodex Adam uses a front-facing interface, with robotic fingers coupled to two of the user’s fingertips, the thumb, and two points on the palm. Including the palm, as opposed to only the fingertips as is common in existing devices, enables accurate tracking of the whole hand without additional sensors such as a data glove or motion capture. By providing “whole-hand” interaction with omnidirectional force-feedback at the attachment points, we enable the user to experience the environment with the complete hand instead of only the fingertips, thus realizing deeper immersion. Interaction using Exodex Adam can range from palpation of objects and surfaces to manipulation using both power and precision grasps, all while receiving haptic feedback. This article details the concept and design of the Exodex Adam, as well as use cases where it is deployed with different command modalities. These include mixed-media interaction in a virtual environment, gesture-based telemanipulation, and robotic hand–arm teleoperation using adaptive model-mediated teleoperation. Finally, we share the insights gained during our development process and use case deployments.
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| 3. |
- 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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| 4. |
- Chernyshev, Alexander N., et al.
(författare)
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Solubilization of Ni(II) and Eu(III) through complexation with a polyaryl ether based superplasticizer in alkaline media
- 2021
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 263
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Tidskriftsartikel (refereegranskat)abstract
- Solubilisation of Ni(II) and Eu(III) by complexation with a polyaryl ether based superplasticizer (PAE SP) in alkaline solutions was studied. The solubilization was investigated in two types of artificial cement pore waters simulating different stages of cement degradation at a pH of 12.4 and 13.3, respectively. The solubility of Ni(II) and Eu(III) increased as the concentration of superplasticizer was increased from 0.04 to 0.4 wt%. When the concentration of SP was increased from 0.4 to 4%, the solubility of Eu(III) and Ni(II) increased in the pore water with a pH of 12.4, while the concentrations decreased in the pore water with a pH of 13.3. This is explained by a more rapid degradation of the superplasticizer at higher pH leading to a release of phosphate groups and thereby precipitation of Eu(III) and Ni(II) as phosphates. Based on results of the solubilisation of Ni(II) and Eu(III) by model compounds (anisole and PEG 400) and 31P NMR spectroscopy it was confirmed that the complexation of the studied metals with the PAE polymer occurs via the phosphate group of the superplasticizer.
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| 5. |
- Li, Junyi, et al.
(författare)
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Stability of Studtite in Aqueous Suspension : Impact of HCO3- and Ionizing Radiation on the Dynamics of Dissolution
- 2020
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Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 3:1, s. 352-357
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Tidskriftsartikel (refereegranskat)abstract
- In a geological repository for spent nuclear fuel, studtite (UO2)O-2(H2O)(4) may form on the fuel surface when in contact with groundwater under certain conditions. Studtite has a very low solubility and could thereby reduce the reactivity of spent nuclear fuel toward radiolytic oxidants. This would inhibit the dissolution of the fuel matrix and thereby also the spreading of radionuclides. It is therefore important to investigate the stability of studtite under conditions that may influence its stability. In this work we have studied the kinetics of studtite dissolution in aqueous suspensions containing no added HCO3- and with 10 mM HCO3-. The same type of experiment was performed also with solutions containing 0.2 mM H2O2. The solubility of studtite in the suspensions containing no added HCO3- is very low as expected, while the solubility in solutions containing 10 mM HCO3- is significantly higher. This is attributed to the formation of uranyl-carbonate and uranyl-peroxo-carbonate complexes. In 0.2 mM H2O2 and 10 mM HCO3- the observed solubility of U(VI) seems unaffected by the presence of H2O2. Again, this can be rationalized by the formation of uranyl-peroxo-carbonate complexes. It is interesting to note that H2O2 appears to be catalytically decomposed in solutions containing uranyl-carbonate complexes. In addition, gamma-radiation-induced dissolution of studtite in HCO3- deficient solutions and in 10 mM HCO3- was studied. The dissolution rate was found to be extremely high in HCO3- under gamma-irradiation. This is attributed to a combination of radiolytic degradation of H2O2 and the formation of uranyl-peroxo-carbonate complexes keeping the concentration of free H2O2 at a very low level and thereby driving the dissolution process.
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| 6. |
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| 7. |
- Maier, Annika Carolin, et al.
(författare)
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Confirming the Formation of Hydroxyl Radicals in the Catalytic Decomposition of H2O2 on Metal Oxides Using Coumarin as a Probe
- 2019
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Ingår i: ChemCatChem. - : WILEY-V C H VERLAG GMBH. - 1867-3880 .- 1867-3899. ; 11:22, s. 5435-5438
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen peroxide can be catalytically decomposed to O-2 and H2O on metal oxide surfaces in contact with aqueous solutions containing H2O2. The initial step in this process has been proposed to be the formation of surface-bound hydroxyl radicals which has recently been verified using tris as a radical scavenger. Here, we make use of the unique fluorescent product 7-hydroxycoumarin formed in the reaction between hydroxyl radicals and coumarin to probe the formation of surface-bound hydroxyl radicals. The experiments clearly show that 7-hydroxycoumarin is formed upon catalytic decomposition of H2O2 in aqueous suspensions containing ZrO2-particles and coumarin, thereby confirming the formation of surface-bound hydroxyl radicals in this process. The results are quantitatively compared to results on the same system using tris as a probe for hydroxyl radicals. The effects of the two probes on the system under study are compared and it is concluded that coumarin has a significantly lower impact on the system.
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| 8. |
- Maier, Annika Carolin
(författare)
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Dynamics of Spent Nuclear Fuel Dissolution : Impact of Catalysis, Matrix Composition and Time Evolution
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Worldwide, nuclear power produces a large portion of the electricity that we consume every day. While nuclear energy comes with certain advantages, waste originating from its use is of particular concern. As of today, most countries are planning to store spent nuclear fuel in deep geological repositories to protect humans and the environment from this highly radiotoxic waste. Through a number of natural and engineered barriers, a repository is designed to remain intact and keep the radionuclides contained for millennia to come. To assess the safety of a repository, long-term predictions based on model systems are required. Given that one day the barriers of a repository fail, groundwater intrusion is inevitable. Once spent fuel is in contact with groundwater, the mobility of radionuclides in the environment is significantly enhanced. Spent nuclear fuel is a complex material which consists to around 95 % of UO2. The remainders are fission products and heavier actinides. In this thesis a bottom up approach is used to study dissolution of UO2 based model systems with a particular focus on dissolution induced by H2O2. H2O2 forms upon water radiolysis and can enhance UO2 dissolution. The mechanism for H2O2 consumption on metals and metal oxides is therefore revisited. It was found that the mechanism for catalytic decomposition of H2O2 on Pd differs from that on metal oxides. In addition, coumarin was demonstrated to be an efficient scavenger for reaction intermediates i.e. HO . To simulate longterm dissolution under repository conditions, UO2 and Gd-doped UO2 pellets were leached to reach high H2O2 exposures. Surface passivation reducing the dissolution of UO2 pellets was found to be accompanied by the formation of an oxidized layer. Studtite, a urnayl peroxide mineral can passivate the UO2 surface under certain conditions. Upon exposure to g-radiation studtite was found to dissolve readily, inhibiting passivation of real spent fuel by this surface precipitate.
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