| 1. |
- de Jong, R. S., et al.
(författare)
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4MOST : Project overview and information for the First Call for Proposals
- 2019
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Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
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| 2. |
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The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
- 2022
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.
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| 3. |
- Geisler, D., et al.
(författare)
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CAPOS : The bulge Cluster APOgee Survey I. Overview and initial ASPCAP results
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 652
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Tidskriftsartikel (refereegranskat)abstract
- Context. Bulge globular clusters (BGCs) are exceptional tracers of the formation and chemodynamical evolution of this oldest Galactic component. However, until now, observational difficulties have prevented us from taking full advantage of these powerful Galactic archeological tools. Aims. CAPOS, the bulge Cluster APOgee Survey, addresses this key topic by observing a large number of BGCs, most of which have only been poorly studied previously. Even their most basic parameters, such as metallicity, [alpha/Fe], and radial velocity, are generally very uncertain. We aim to obtain accurate mean values for these parameters, as well as abundances for a number of other elements, and explore multiple populations. In this first paper, we describe the CAPOS project and present initial results for seven BGCs. Methods. CAPOS uses the APOGEE-2S spectrograph observing in the H band to penetrate obscuring dust toward the bulge. For this initial paper, we use abundances derived from ASPCAP, the APOGEE pipeline. Results. We derive mean [Fe/H] values of -0.85 +/- 0.04 (Terzan 2), -1.40 +/- 0.05 (Terzan 4), -1.20 +/- 0.10 (HP 1), -1.40 +/- 0.07 (Terzan 9), -1.07 +/- 0.09 (Djorg 2), -1.06 +/- 0.06 (NGC 6540), and -1.11 +/- 0.04 (NGC 6642) from three to ten stars per cluster. We determine mean abundances for eleven other elements plus the mean [alpha/Fe] and radial velocity. CAPOS clusters significantly increase the sample of well-studied Main Bulge globular clusters (GCs) and also extend them to lower metallicity. We reinforce the finding that Main Bulge and Main Disk GCs, formed in situ, have [Si/Fe] abundances slightly higher than their accreted counterparts at the same metallicity. We investigate multiple populations and find our clusters generally follow the light-element (anti)correlation trends of previous studies of GCs of similar metallicity. We finally explore the abundances of the iron-peak elements Mn and Ni and compare their trends with field populations. Conclusions. CAPOS is proving to be an unprecedented resource for greatly improving our knowledge of the formation and evolution of BGCs and the bulge itself.
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| 4. |
- Ericsson, A., et al.
(författare)
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Crystallization of a Zr-based metallic glass produced by laser powder bed fusion and suction casting
- 2021
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 571
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Tidskriftsartikel (refereegranskat)abstract
- The crystallization behaviour during low temperature annealing of samples of the Zr59.3Cu28.8Al10.4Nb1.5 (at%) bulk metallic glass produced by suction casting and the laser powder bed fusion (LPBF) process were studied with small angle neutron scattering (SANS), X-ray diffraction and scanning electron microscopy. The in-situ SANS measurements during isothermal annealing reveals that the phase separation in the LPBF processed material proceeds at a smaller characteristic length-scale than the cast material. Quantitative analysis of the SANS data shows that, while the crystallization process in both materials proceed through rapid nucleation followed by diffusion limited growth, the LPBF processed material crystallizes with a smaller cluster size and at a higher rate. The smaller cluster size is attributed to the elevated oxygen content in the LPBF processed material which reduces the nucleation barrier and thus the thermal stability.
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| 5. |
- Ivarsson, Stefan, et al.
(författare)
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Improved oscillator strengths and wavelengths for Os I and Ir I, and new results on early r-process nucleosynthesis
- 2003
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 409:3, s. 1141-1149
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Tidskriftsartikel (refereegranskat)abstract
- The radioactive decay of 238U and 232Th has recently been used to determine ages for some of the oldest stars in the Universe. This has highlighted the need for accurate observational constraints on production models for the heaviest r-process elements which might serve as stable references, notably osmium and iridium. In order to provide a firmer basis for the observed abundances, we have performed laser-induced fluorescence measurements and Fourier Transform Spectroscopy to determine new radiative lifetimes and branching fractions for selected levels in Os I and Ir I. From these data, we determine new absolute oscillator strengths and improved wavelengths for18 Os I and 4 Ir I lines. A reanalysis of VLT spectra of CS 31082-001and new results for other stars with Os and Ir detections show that (i):the lines in the UV and lambda 4260 yield reliable Os abundances, while those at lambda lambda 4135, 4420 are heavily affected by blending; (ii): the Os and Ir abundances are identical in all the stars; (iii): the heavy-element abundances in very metal-poor stars conform closely to the scaled solar r-process pattern throughout the range 56 <= Z <= 77; and (iv): neither Os or Ir nor any lighter species are suitable as reference elements for the radioactive decay of Th and U.Based in part on observations obtained with the Very Large Telescope of the European Southern Observatory at Paranal, Chile.
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| 6. |
- Martin, R, et al.
(författare)
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High-Resolution X-ray Photoelectron Spectroscopy of an IrO2(110) Film on Ir(100)
- 2020
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 11:17, s. 7184-7189
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) were used to characterize IrO2(110) films on Ir(100) with stoichiometric as well as OH-rich terminations. Core-level Ir 4f and O 1s peaks were identified for the undercoordinated Ir and O atoms and bridging and on-top OH groups at the IrO2(110) surfaces. Peak assignments were validated by comparison of the core-level shifts determined experimentally with those computed using DFT, quantitative analysis of the concentrations of surface species, and the measured variation of the Ir 4f peak intensities with photoelectron kinetic energy. We show that exposure of the IrO2(110) surface to O2 near room temperature produces a large quantity of on-top OH groups because of reaction of background H2 with the surface. The peak assignments made in this study can serve as a foundation for future experiments designed to utilize XPS to uncover atomic-level details of the surface chemistry of IrO2(110).
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| 7. |
- Petrlova, Jitka, et al.
(författare)
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Aggregation of thrombin-derived C-terminal fragments as a previously undisclosed host defense mechanism
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:21, s. E4213-E4222
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Tidskriftsartikel (refereegranskat)abstract
- Effective control of endotoxins and bacteria is crucial for normal wound healing. During injury, the key enzyme thrombin is formed, leading to generation of fibrin. Here, we show that human neutrophil elastase cleaves thrombin, generating 11-kDa thrombin-derived C-terminal peptides (TCPs), which bind to and form amorphous amyloid-like aggregates with both bacterial lipopolysaccharide (LPS) and gram-negative bacteria. In silico molecular modeling using atomic resolution and coarse-grained simulations corroborates our experimental observations, altogether indicating increased aggregation through LPS-mediated intermolecular contacts between clusters of TCP molecules. Upon bacterial aggregation, recombinantly produced TCPs induce permeabilization of Escherichia coli and phagocytic uptake. TCPs of about 11 kDa are present in acute wound fluids as well as in fibrin sloughs from patients with infected wounds. We noted aggregation and colocalization of LPS with TCPs in such fibrin material, which indicates the presence of TCP-LPS aggregates under physiological conditions. Apart from identifying a function of proteolyzed thrombin and its fragments, our findings provide an interesting link between the coagulation system, innate immunity, LPS scavenging, and protein aggregation/amyloid formation.
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| 8. |
- Raphel, J., et al.
(författare)
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Engineered protein coatings to improve the osseointegration of dental and orthopaedic implants
- 2016
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 83, s. 269-282
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Tidskriftsartikel (refereegranskat)abstract
- Here we present the design of an engineered, elastin-like protein (ELP) that is chemically modified to enable stable coatings on the surfaces of titanium-based dental and orthopaedic implants by novel photocrosslinking and solution processing steps. The ELP includes an extended RGD sequence to confer bio-signaling and an elastin-like sequence for mechanical stability. ELP thin films were fabricated on cpTi and Ti6A14V surfaces using scalable spin and dip coating processes with photoactive covalent cross linking through a carbene insertion mechanism. The coatings withstood procedures mimicking dental screw and hip replacement stem implantations, a key metric for clinical translation. They promoted rapid adhesion of MG63 osteoblast-like cells, with over 80% adhesion after 24 h, compared to 38% adhesion on uncoated Ti6A14V. MG63 cells produced significantly more mineralization on ELP coatings compared to uncoated Ti6A14V. Human bone marrow mesenchymal stem cells (hMSCs) had an earlier increase in alkaline phosphatase activity, indicating more rapid osteogenic differentiation and mineral deposition on adhesive ELP coatings. Rat tibia and femur in vivo studies demonstrated that cell -adhesive ELP-coated implants increased bone-implant contact area and interfacial strength after one week. These results suggest that ELP coatings withstand surgical implantation and promote rapid osseointegration, enabling earlier implant loading and potentially preventing micromotion that leads to aseptic loosening and premature implant failure.
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| 9. |
- Areitioaurtena, Maialen, et al.
(författare)
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Influence of induction hardening residual stresses on rolling contact fatigue lifetime
- 2022
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Ingår i: International Journal of Fatigue. - : Elsevier. - 0142-1123 .- 1879-3452. ; 159
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Tidskriftsartikel (refereegranskat)abstract
- Rolling contact fatigue is a unique mode of fatigue that components under cyclic contact loading experience. In this work, the impact of induction hardening residual stresses in rolling contact fatigue lifetime is investigated experimentally and numerically using the Dang Van multiaxial criterion. Various residual stress fields from induction hardening are simulated using the finite element method and are mapped into a classical monocontact finite element model. The impact of induction hardened residual stresses on the lifetime of a component has been investigated, and the importance of incorporating the residual stress profile into fatigue life assessments is affirmed.
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| 10. |
- Areitioaurtena, Maialen, et al.
(författare)
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Numerical and experimental investigation of residual stresses during the induction hardening of 42CrMo4 steel
- 2022
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Ingår i: European journal of mechanics. A, Solids. - : Elsevier. - 0997-7538 .- 1873-7285. ; 96
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Tidskriftsartikel (refereegranskat)abstract
- The usage of induction hardening in the industry has increased in the last years due to its efficiency and repeatability. Induction hardening produces a hard martensitic layer on the specimen surface, which is accompanied by the generation of compressive residual stresses in the hardened case and tensile stresses in the untreated core. Residual stresses generated by induction hardening greatly impact on fatigue performance, as they act as crack growth retardants. In this work, a multiphysical coupled finite element model is developed to simulate induction hardening and compute the final residual stress state of the specimens along the microstructural transformations and hardness evolution. The impact of the transformation induced plasticity strain in the stress-state of the specimen during the process is also studied. The experimental validation shows that considering the transformation induced plasticity in induction hardening simulations improves the residual stress predictions, concluding that this effect should be included to achieve good residual stress predictions, especially in the subsurface region.
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