| 1. |
- Niemi, MEK, et al.
(author)
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- 2021
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swepub:Mat__t
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| 2. |
- Kanai, M, et al.
(author)
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- 2023
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swepub:Mat__t
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| 10. |
- Vanzella, E., et al.
(author)
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An extremely metal-poor star complex in the reionization era : Approaching Population III stars with JWST
- 2023
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 678
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Journal article (peer-reviewed)abstract
- We present JWST/Near Infrared Spectrograph (NIRSpec) integral field spectroscopy (IFS) of a lensed Population III candidate stellar complex (dubbed Lensed And Pristine 1, LAP1), with a lensing-corrected stellar mass of ≲104 M⊙ and an absolute luminosity of MUV > −11.2 (mUV > 35.6), confirmed at redshift 6.639 ± 0.004. The system is strongly amplified (μ ≳ 100) by straddling a critical line of the Hubble Frontier Field galaxy cluster MACS J0416. Although the stellar continuum is currently not detected in the Hubble and JWST/Near Infrared Camera (NIRCam) and Near Infrared Imager and Slitless Spectrograph (NIRISS) imaging, arclet-like shapes of Lyman and Balmer lines, Lyα, Hγ, Hβ and Hα are detected with NIRSpec IFS with signal-to-noise ratios (S/N) of approximately 5 − 13 and large equivalent widths (> 300 − 2000 Å), along with a remarkably weak [O III]λλ4959, 5007 at S/N ≃ 4. LAP1 shows a large ionizing photon production efficiency, log(ξion[erg Hz−1]) > 26. From the metallicity indexes R23 = ([O III] + [O II])/Hβ ≲ 0.74 and R3 = ([O III]/Hβ) = 0.55 ± 0.14, we derive an oxygen abundance of 12 + log(O/H)≲6.3. Intriguingly, the Hα emission is also measured in mirrored subcomponents where no [O III] is detected, providing even more stringent upper limits on the metallicity if in situ star formation is ongoing in this region (12 + log(O/H) < 6). The formal stellar mass limit of the subcomponents would correspond to ∼103 M⊙ or MUV fainter than −10. Alternatively, this metal-free, pure line-emitting region could be the first case of a fluorescing H I gas region induced by transverse escaping ionizing radiation from a nearby star complex. The presence of large equivalent-width hydrogen lines and the deficiency of metal lines in such a small region make LAP1 the most metal-poor star-forming region currently known in the reionization era and a promising site that may host isolated, pristine stars.
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| 11. |
- Béthermin, Matthieu, et al.
(author)
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The ALMA-ALPINE [CII] survey: Kennicutt-Schmidt relation in four massive main-sequence galaxies at z ~ 4.5
- 2023
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 680
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Journal article (peer-reviewed)abstract
- Aims. The Kennicutt-Schmidt (KS) relation between the gas and the star formation rate (SFR) surface density (Σgas - ΣSFR) is essential to understand star formation processes in galaxies. To date, it has been measured up to z ~ 2.5 in main-sequence galaxies. In this Letter our aim is to put constraints at z ~ 4.5 using a sample of four massive main-sequence galaxies observed by ALMA at high resolution. Methods. We obtained ~0.3″-resolution [CII] and continuum maps of our objects, which we then converted into gas and obscured SFR surface density maps. In addition, we produced unobscured SFR surface density maps by convolving Hubble ancillary data in the rest-frame UV. We then derived the average ΣSFR in various Σgas bins, and estimated the uncertainties using a Monte Carlo sampling. Results. Our galaxy sample follows the KS relation measured in main-sequence galaxies at lower redshift, and is slightly lower than the predictions from simulations. Our data points probe the high end both in terms of Σgas and ΣSFR, and gas depletion timescales (285-843 Myr) remain similar to z ~ 2 objects. However, three of our objects are clearly morphologically disturbed, and we could have expected shorter gas depletion timescales (≲100 Myr) similar to merger-driven starbursts at lower redshifts. This suggests that the mechanisms triggering starbursts at high redshift may be different than in the low- and intermediate-z Universe.
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| 12. |
- Batista, A. M., et al.
(author)
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Quantification of torque teno virus (TTV) DNA in saliva and plasma samples in patients at short time before and after kidney transplantation
- 2022
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In: Journal of Oral Microbiology. - : Informa UK Limited. - 2000-2297. ; 14:1
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Journal article (peer-reviewed)abstract
- Background Several reports have proposed that the viral load of torque teno virus (TTV) in plasma is a biomarker of immune function in solid organ transplantation (SOT) and in allogeneic hematopoietic stem cell transplantation. Additionally, for the latter one, TTV-DNA quantification in saliva has also been suggested. Aim to investigate the correlation between the TTV viral load and immune function in paired saliva and plasma samples in patients on kidney transplantation. Materials and Methods TTV-DNA viral load was quantified in paired samples of saliva and plasma from 71 patients before and a short-time after renal-transplantation by real-time PCR. Results The data obtained from 213 paired samples showed a slight consistency in the comparison between saliva and plasma, with prevalence of TTV-DNA being 58%, 52% and 60% in saliva samples and 60%, 73% and 90% in plasma samples before and at 15-20 and 45-60 days after transplantation, respectively. Additionally, a high TTV viral load was observed in plasma at 15-20 and 45-60 days after transplantation compared to that observed in saliva at the same time. Conclusions Overall, monitoring TTV-DNA in saliva samples could be an additional fast non-invasive option to assess the immune functionality in SOT populations.
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| 13. |
- Caporale, N., et al.
(author)
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From cohorts to molecules: Adverse impacts of endocrine disrupting mixtures
- 2022
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375:6582
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Journal article (peer-reviewed)abstract
- Convergent evidence associates exposure to endocrine disrupting chemicals (EDCs) with major human diseases, even at regulation-compliant concentrations. This might be because humans are exposed to EDC mixtures, whereas chemical regulation is based on a risk assessment of individual compounds. Here, we developed a mixture-centered risk assessment strategy that integrates epidemiological and experimental evidence. We identified that exposure to an EDC mixture in early pregnancy is associated with language delay in offspring. At human-relevant concentrations, this mixture disrupted hormone-regulated and disease-relevant regulatory networks in human brain organoids and in the model organisms Xenopus leavis and Danio rerio, as well as behavioral responses. Reinterrogating epidemiological data, we found that up to 54% of the children had prenatal exposures above experimentally derived levels of concern, reaching, for the upper decile compared with the lowest decile of exposure, a 3.3 times higher risk of language delay. © 2022 American Association for the Advancement of Science. All rights reserved.
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| 14. |
- Ahmadkhaniha, Donya, et al.
(author)
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Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg
- 2017
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Conference paper (peer-reviewed)abstract
- High-pressure torsion (HPT) processing was applied to cast pure Mg pieces and its effects on microstructure, hardness and tensile properties as well as corrosion resistance were evaluated. The microstructure of the processed samples was examined by electron backscatter diffraction (EBSD) and the mechanical properties were determined by microhardness and tensile tests. Corrosion resistance of the samples was studied via electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results showed that HPT refined the grain size of Mg very effectively from millimeters in the cast structure to a few micrometers homogeneously through the thickness and created a basal texture on the surface. One or five turns of HPT produced no significant difference in the grain size of the processed Mg but the hardness was a maximum after one turn. The yield strength of the cast Mg was increased by seven times whereas the corrosion resistance was not affected by the HPT processing.
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| 15. |
- Kessous, I. M., et al.
(author)
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Pollinators drive floral evolution in an Atlantic Forest genus
- 2020
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In: Aob Plants. - : Oxford University Press (OUP). - 2041-2851. ; 12:5
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Journal article (peer-reviewed)abstract
- Pollinators are important drivers of angiosperm diversification at both micro- and macroevolutionary scales. Both hummingbirds and bats pollinate the species-rich and morphologically diverse genus Vriesea across its distribution in the Brazilian Atlantic Forest. Here, we (i) determine if floral traits predict functional groups of pollinators as documented, confirming the pollination syndromes in Vriesea and (ii) test if genetic structure in Vriesea is driven by geography (latitudinal and altitudinal heterogeneity) or ecology (pollination syndromes). We analysed 11 floral traits of 58 Vriesea species and performed a literature survey of Vriesea pollination biology. The genealogy of haplotypes was inferred and phylogenetic analyses were performed using chloroplast (rps16-trnk and matK) and nuclear (PHYC) molecular markers. Floral traits accurately predict functional groups of pollinators in Vriesea. Genetic groupings match the different pollination syndromes. Species with intermediate position were found between the groups, which share haplotypes and differ morphologically from the typical hummingbird- and bat-pollinated flowers of Vriesea. The phylogeny revealed moderately to well-supported clades which may be interpreted as species complexes. Our results suggest a role of pollinators driving ecological isolation in Vriesea clades. Incipient speciation and incomplete lineage sorting may explain the overall low genetic divergence within and among morphologically defined species, precluding the identification of clear species boundaries. The intermediate species with mixed floral types likely represent a window into shifts between pollinator syndromes. This study reports the morphological-genetic continuum that may be typical of ongoing pollinator-driven speciation in biodiversity hotspots.
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| 16. |
- Neves, B., et al.
(author)
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Drivers of bromeliad leaf and floral bract variation across a latitudinal gradient in the Atlantic Forest
- 2020
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In: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 47:1, s. 261-274
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Journal article (peer-reviewed)abstract
- Aim Understanding the complex interaction and relative contributions of factors involved in species and trait diversification is crucial to gain insights into the evolution of Neotropical biodiversity. Here, we investigated the drivers of morphological variation in bromeliads along a latitudinal gradient in a biodiversity hotspot. Location Atlantic Forest, Brazil. Taxon A species complex in the genus Vriesea (Bromeliaceae). Methods We measured shape and size variation for 208 floral bracts and 176 leaves in individuals from 14 localities using geometric morphometrics. We compiled data for two chloroplast regions (matK and trnL-F) from 89 individuals to assess genetic diversity, population structure and phylogenetic relationships. We tested the influence of climate, altitude and genetic distance on morphological traits using linear statistical models. Results Temperature seasonality is a main driver of floral bract shape. Together with precipitation, it also explains changes in leaf size across the latitudinal gradient. Shifts in morphological traits are correlated with genetic structure and partly support the recent taxonomic delimitation proposed for the species complex. The species started to diversify in the Pliocene ca. 5 Mya. We detected a phylogeographical break in species distribution into northern and southern clades between the Bocaina region and the southern portion of the Atlantic Forest. Main Conclusions We identify how geography and environmental changes through time shape floral bracts and leaves in similar ways. At highly seasonal sites with lower annual precipitation (in the southern subtropical portion of the Atlantic Forest), leaves are larger and floral bracts are wide-elliptic, making them better suited for increased water accumulation. In contrast, at less seasonal sites (in the tropical north, where rainfall is more abundant and temperatures are higher), leaves are narrower and floral bracts are lanceolate-shaped, facilitating water drainage. The biogeographical break we identified suggests a role of tectonic activity and climatic oscillations in promoting species divergence and diversification.
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| 17. |
- State, S. P., et al.
(author)
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Electrodeposited Sn-Cu-Ni alloys as lead-free solders on copper substrate using deep eutectic solvents : The influence of electrodeposition mode on the morphology, composition and corrosion behaviour
- 2024
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In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 477
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Journal article (peer-reviewed)abstract
- In this work we present the pulsed current (PC) electrodeposition of Sn-Cu-Ni alloy as lead-free solder candidate, from choline chloride – ethylene glycol eutectic mixtures (1:2 molar ratio) onto copper metallic substrates. Electrolytes containing Sn2+, Cu2+ and Ni2+ salts in the selected deep eutectic solvent have been considered. The effect of the applied frequency of PC on the morphology, composition and melting point of the alloy is discussed and compared to the ones obtained using direct current (DC) plating mode. A refinement of the grain size and lower melting temperature of the alloy were noticed when pulsed current was applied. A comparative analysis of the electrochemical corrosion behaviour at macro- and micro- scale has been performed in 0.5 M and 0.1 M NaCl solutions involving potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode (SVET) techniques. Furthermore, an analysis after 96 h of exposure to salt mist test simulating a corrosive attack in harsh environment is presented, too. The obtained results showed enhanced corrosion resistance of the ternary alloys electrodeposited under PC conditions (the best for 1.67 Hz frequency) as compared to those using DC. Additionally, Raman spectroscopy evidenced the presence of tin oxi/hydroxy chloride and tin oxides as surface corrosion products. A corrosion mechanism has been proposed.
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| 18. |
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| 19. |
- Atefi, S., et al.
(author)
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A study on microstructure development and mechanical properties of pure copper subjected to severe plastic deformation by the ECAP-Conform process
- 2022
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In: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T. - : Elsevier. - 2238-7854. ; 21, s. 1614-1629
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Journal article (peer-reviewed)abstract
- Commercially pure copper rod was successfully subjected to severe plastic deformation by applying the continuous equal channel angular pressing (ECAP-Conform) method at room temperature. Microstructural characterizations of copper rod samples at various stages of plastic deformation were carried out by optical microscopy and electron backscatter diffraction methods. X-ray diffractometry and Kernal average misorientation were used for dislocation density estimations. Microstructural evaluations revealed grain size change of 30 mm for the initial annealed copper rod to less than 5 mm and even 100 nm for severely deformed samples. Mechanical behaviors of samples after different deformation stages were characterized using tensile and hardness tests. The ultimate tensile strength of the severely deformed copper rod was increased threefold by ECAP-Conform while elongation halved in comparison to the initial annealed copper. Low-temperature annealing of severely plastic deformed samples led to bi-modal grain size distribution and lowering of strength accompanied by the increase of elongation. Tensile properties of severely deformed and then annealed copper samples showed around a 40% increase in both ultimate tensile strength and elongation in comparison to the initial annealed copper rod.
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| 20. |
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| 21. |
- Deflorian, F., et al.
(author)
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Stress corrosion cracking (SCC) failure in marine areas of fixed guards for climbing
- 2015
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In: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 50:6, s. 462-466
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Journal article (peer-reviewed)abstract
- This work studies the particular mechanism of environmental stress corrosion cracking (SCC) that has been described to interest stainless steel products, like climbing anchors, installed in sea areas. The failure analysis of several broken anchors was carried out. The samples were collected in different parts of the world, always from climbing structures close to the sea. The analysis confirmed the stress corrosion mechanism of degradation, giving also important information about the specific environments causing the metal fracture. These results are in agreement with a few previous works about this subject and are in the frame of the larger topic of SCC of austenitic stainless steel at room temperature. Moreover, some corrosion tests were carried out on stainless steel samples simulating the operation conditions, after contamination with electrolytes at different concentration. The tests are performed in order to better understand the degradation mechanism and to evaluate the influence of some environmental parameters over the susceptibility to SCC. With these experimental data, a possible interpretation model has been proposed together with some reasonable solutions for the material selection process, considering the problem's characteristics and the multiple alternatives available nowadays for climbing materials.
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| 22. |
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| 23. |
- Fedel, M., et al.
(author)
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Effect of the synthesis parameters of in situ grown Mg-Al LDHs on the filiform corrosion susceptibility of painted AA5005
- 2021
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In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 381
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Journal article (peer-reviewed)abstract
- Novel layered double hydroxides (LDHs) based coatings developed in-situ on aluminum alloys are recognized to provide the substrate with improved corrosion protection. LDH layers have gained prominent attention due to their barrier properties and ions exchange capability, together with compositional flexibility and low environmental impact. In this work, diverse MgAl LDHs layers are developed on AA5005 as a surface conversion treatment prior to applying an acrylic clearcoat. The work aims to assess the potential LDH layers of to improve the filiform corrosion (FFC) resistance of the AA500 substrate. The effect of the synthesis time and the presence of urea on the FFC susceptibility are investigated. The performance of the different synthesis conditions was compared and shown to be more effective to increase FFC resistance when well-defined crystals are formed. The findings suggest that MgAl-LDHs mitigate the extent of filiform corrosion of acrylic paint coated AA5005. The FFC inhibition was found to be qualitatively proportional to the pitting potential measured over the LDHs conversion layers.
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| 24. |
- Kohandel, M., et al.
(author)
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Kinematics of z ≥ 6 galaxies from [C II] line emission
- 2019
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 487:3, s. 3007-3020
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Journal article (peer-reviewed)abstract
- We study the kinematical properties of galaxies in the Epoch of Reionization via the [C ii]158 μm line emission. The line profile provides information on the kinematics as well as structural properties such as the presence of a disc and satellites. To understand how these properties are encoded in the line profile, first we develop analytical models from which we identify disc inclination and gas turbulent motions as the key parameters affecting the line profile. To gain further insights, we use 'Althæa', a highly resolved (30\, \rm pc) simulated prototypical Lyman-break galaxy, in the redshift range z = 6-7, when the galaxy is in a very active assembling phase. Based on morphology, we select three main dynamical stages: (I) merger, (II) spiral disc, and (III) disturbed disc. We identify spectral signatures of merger events, spiral arms, and extra-planar flows in (I), (II), and (III), respectively. We derive a generalized dynamical mass versus [C ii]-line FWHM relation. If precise information on the galaxy inclination is (not) available, the returned mass estimate is accurate within a factor 2 (4). A Tully-Fisher relation is found for the observed high-z galaxies, i.e. L[C ii] (FWHM)1.80 ± 0.35 for which we provide a simple, physically based interpretation. Finally, we perform mock ALMA simulations to check the detectability of [C ii]. When seen face-on, Althæa is always detected at >5σ; in the edge-on case it remains undetected because the larger intrinsic FWHM pushes the line peak flux below detection limit. This suggests that some of the reported non-detections might be due to inclination effects.
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| 25. |
- Lekka, M., et al.
(author)
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New European Training Network solving corrosion problems on micro- and nanoscale : mCBEEs
- 2017
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In: Transactions of the Institute of Metal Finishing. - : Informa UK Limited. - 0020-2967 .- 1745-9192. ; 95:6, s. 297-298
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Journal article (peer-reviewed)abstract
- mCBEEs is an acronym for: Advanced integrative solutions to Corrosion problems beyond micro-scale: towards long-term durability of miniaturised Biomedical, Electronic and Energy systems. It is a doctoral student training network funded by the European Commission under the Marie Sklodowska-Curie Action scheme in the same way as the recently reported training network SELECTA that is focusing on smart electrodeposited alloys for environmentally sustainable applications.1.
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