| 1. |
- Ioannidou, Chrysoula, et al.
(author)
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In-situ synchrotron X-ray analysis of metal Additive Manufacturing : Current state, opportunities and challenges
- 2022
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In: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 219, s. 110790-
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Journal article (peer-reviewed)abstract
- Additive Manufacturing (AM) is becoming an important technology for manufacturing of metallic materials. Laser-Powder Bed Fusion (L-PBF), Electron beam-Powder Bed Fusion (E-PBF) and Directed Energy Deposition (DED) have attracted significant interest from both the scientific community and the industry since these technologies offer great manufacturing opportunities for niche applications and complex geometries. Understanding the physics behind the complex and dynamic phenomena occurring during these processes is essential for overcoming the barriers that constrain the metal AM development. Insitu synchrotron X-ray characterization is suitable for investigating the microstructure evolution during processing and provides new profound insights. Here, we provide an overview of the research on metal PBF and DED using in-situ synchrotron X-ray imaging, diffraction and small-angle scattering, highlighting the state of the art, the instrumentation, the challenges and the gaps in knowledge that need to be filled. We aim at presenting a scientific roadmap for in-situ synchrotron analysis of metal PBF and DED where future challenges in instrumentation such as the development of experimental stations, sample environments and detectors as well as the need for further application oriented research are included.
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| 2. |
- König, Carolin, et al.
(author)
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Binding sites for luminescent amyloid biomarkers from non-biased molecular dynamics simulations
- 2018
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In: Chemical Communications. - : ROYAL SOC CHEMISTRY. - 1359-7345 .- 1364-548X. ; 54:24, s. 3030-3033
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Journal article (peer-reviewed)abstract
- A very stable binding site for the interaction between a pentameric oligothiophene and an amyloid-(1-42) fibril has been identified by means of non-biased molecular dynamics simulations. In this site, the probe is locked in an all-trans conformation with a Coulombic binding energy of 1200 kJ mol(-1) due to the interactions between the anionic carboxyl groups of the probe and the cationic epsilon-amino groups in the lysine side chain. Upon binding, the conformationally restricted probes show a pronounced increase in molecular planarity. This is in line with the observed changes in luminescence properties that serve as the foundation for their use as biomarkers.
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| 3. |
- König, Carolin, et al.
(author)
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Linear-scaling generation of potential energy surfaces using a double incremental expansion
- 2016
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In: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 145:6
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Journal article (peer-reviewed)abstract
- We present a combination of the incremental expansion of potential energy surfaces (PESs), known as n-mode expansion, with the incremental evaluation of the electronic energy in a many-body approach. The application of semi-local coordinates in this context allows the generation of PESs in a very cost-efficient way. For this, we employ the recently introduced flexible adaptation of local coordinates of nuclei (FALCON) coordinates. By introducing an additional transformation step, concerning only a fraction of the vibrational degrees of freedom, we can achieve linear scaling of the accumulated cost of the single point calculations required in the PES generation. Numerical examples of these double incremental approaches for oligo-phenyl examples show fast convergence with respect to the maximum number of simultaneously treated fragments and only a modest error introduced by the additional transformation step. The approach, presented here, represents a major step towards the applicability of vibrational wave function methods to sizable, covalently bound systems.
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| 4. |
- König, Hans-Henrik, et al.
(author)
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MiniMelt : An instrument for real-time tracking of electron beam additive manufacturing using synchrotron x-ray techniques
- 2023
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In: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 94:12
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Journal article (peer-reviewed)abstract
- The development of a sample environment for in situ x-ray characterization during metal Electron Beam Powder Bed Fusion (PBF-EB), called MiniMelt, is presented. The design considerations, the features of the equipment, and its implementation at the synchrotron facility PETRA III at Deutsches Elektronen-Synchrotron, Hamburg, Germany, are described. The equipment is based on the commercially available Freemelt ONE PBF-EB system but has been customized with a unique process chamber to enable real-time synchrotron measurements during the additive manufacturing process. Furthermore, a new unconfined powder bed design to replicate the conditions of the full-scale PBF-EB process is introduced. The first radiography (15 kHz) and diffraction (1 kHz) measurements of PBF-EB with a hot-work tool steel and a Ni-base superalloy, as well as bulk metal melting with the CMSX-4 alloy, using the sample environment are presented. MiniMelt enables time-resolved investigations of the dynamic phenomena taking place during multi-layer PBF-EB, facilitating process understanding and development of advanced process strategies and materials for PBF-EB.
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| 5. |
- Madsen, Diana, et al.
(author)
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Anharmonic vibrational spectra from double incremental potential energy and dipole surfaces
- 2018
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 20:5, s. 3445-3456
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Journal article (peer-reviewed)abstract
- We extend the fragmentation-based double incremental expansion in FALCON coordinates (DIF) and its linear-scaling analogue [C. Konig and O. Christiansen, J. Chem. Phys., 2016, 145, 064105] to dipole surfaces. Thereby, we enable the calculation of intensities in vibrational absorption spectra from these cost-efficient property surfaces. We validate the obtained potential energy and dipole surfaces by vibrational spectra calculations employing damped response theory for correlated vibrational coupled cluster wave functions. Our largest calculation on a hexa-phenyl includes all 180 vibrational degrees of freedom of the system, which illustrates the potential of both the DIF schemes for property surface generation and the use of damped response theory from high-dimensional correlated vibrational wave functions. Generally, we obtain good agreement between the spectra calculated from the DIF property surfaces and the non-fragmented analogues. Moreover, when adopting suitable electronic structure methods, good agreement with respect to the experiment can be obtained, as shown for the example of 5-methylfurfural and RI-MP2. In conclusion, our results illustrate that the presented scheme with linearly scaling surfaces enables high quality spectra, as long as reasonably sized fragments can be defined. With this work, we push the realistic limits of vibrational spectra calculations from vibrational wave function methods and accurate electronic structure calculations to significantly larger systems than currently accessible.
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| 6. |
- Roca Rubio, Maria Fernanda, 1989-, et al.
(author)
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Associations between various markers of intestinal barrier and immune function after a high-intensity exercise challenge
- 2024
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In: Physiological Reports. - : John Wiley & Sons. - 2051-817X. ; 12:10
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Journal article (peer-reviewed)abstract
- Strenuous exercise can result in disruption of intestinal barrier function and occurrence of gastrointestinal symptoms. The aim of this exploratory study was to elucidate systemic effects of increased intestinal permeability after high-intensity exercise. Forty-one endurance-trained subjects performed a 60-min treadmill run at 80% VO2max. Small intestinal permeability was measured as urinary excretion ratio of lactulose/rhamnose (L/R). Blood, saliva and feces were analyzed for gut barrier and immune-related biomarkers. The exercise challenge increased several markers of intestinal barrier disruption, immune function and oxidative stress. We found a negative correlation between L/R ratio and uric acid (r = -0.480), as well as a positive correlation between the L/R ratio and fecal chromogranin A in male participants (r = 0.555). No significant correlations were found between any of the markers and gastrointestinal symptoms, however, perceived exertion correlated with the combination of IL-6, IL-10 and salivary cortisol (r = 0.492). The lack of correlation between intestinal permeability and gastrointestinal symptoms could be due to minor symptoms experienced in lab settings compared to real-life competitions. The correlation between L/R ratio and uric acid might imply a barrier-protective effect of uric acid, and inflammatory processes due to strenuous exercise seem to play an important role regarding physical exhaustion.
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| 7. |
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| 8. |
- Skånberg, Robin, et al.
(author)
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VIA-MD : Visual Interactive Analysis of Molecular Dynamics
- 2018
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In: MolVA 2018 - Workshop on Molecular Graphics and Visual Analysis of Molecular Data. - : The Eurographics Association. - 9783038680819 ; , s. 19-27
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Conference paper (peer-reviewed)abstract
- We present a visual exploration environment tailored for large-scale spatio-temporal molecular dynamics simulation data. The environment is referred to as VIA-MD (visual interactive analysis of molecular dynamics) and has been developed in a participatory design process with domain experts on molecular dynamics simulations of complex molecular systems. A key feature of our approach is the support for linked interactive 3D exploration of geometry and statistical analysis using dynamic temporal windowing and animation. Based on semantic level descriptions and hierarchical aggregation of molecular properties we enable interactive filtering, which enables the user to effectively find spatial, temporal and statistical patterns. The VIA-MD environment provides an unprecedented tool for analysis of complex microscopic interactions hidden in large data volumes. We demonstrate the utility of the VIA-MD environment with four use cases. The first two deal with simulation of amyloid plaque associated with development of Alzheimer's, and we study an aqueous solution of 100 probes and an amyloid fibril. The identification of interaction "hotspots" is achieved with the use of combined filter parameters connected with probe molecular planarity and probe-fibril interaction energetics. The third and fourth examples show the wide applicability of the environment by applying it to analysis of molecular properties in material design.
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