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1.
  • Abbasi, Rasha, et al. (författare)
  • IceCube search for neutrinos from GRB 221009A
  • 2023
  • Ingår i: Proceedings of 38th International Cosmic Ray Conference (ICRC 2023). - : Sissa Medialab Srl.
  • Konferensbidrag (refereegranskat)abstract
    •  GRB 221009A is the brightest Gamma Ray Burst (GRB) ever observed. The observed extremelyhigh flux of high and very-high-energy photons provide a unique opportunity to probe the predictedneutrino counterpart to the electromagnetic emission. We have used a variety of methods to searchfor neutrinos in coincidence with the GRB over several time windows during the precursor, promptand afterglow phases of the GRB. MeV scale neutrinos are studied using photo-multiplier ratescalers which are normally used to search for galactic core-collapse supernovae neutrinos. GeVneutrinos are searched starting with DeepCore triggers. These events don’t have directionallocalization, but instead can indicate an excess in the rate of events. 10 GeV - 1 TeV and >TeVneutrinos are searched using traditional neutrino point source methods which take into accountthe direction and time of events with DeepCore and the entire IceCube detector respectively. The>TeV results include both a fast-response analysis conducted by IceCube in real-time with timewindows of T0 − 1 to T0 + 2 hours and T0 ± 1 day around the time of GRB 221009A, as well asan offline analysis with 3 new time windows up to a time window of T0 − 1 to T0 + 14 days, thelongest time period we consider. The combination of observations by IceCube covers 9 ordersof magnitude in neutrino energy, from MeV to PeV, placing upper limits across the range forpredicted neutrino emission.
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2.
  • Mansoor, Rashid, et al. (författare)
  • Haematological consequences of acute uncomplicated falciparum malaria : a WorldWide Antimalarial Resistance Network pooled analysis of individual patient data
  • 2022
  • Ingår i: BMC Medicine. - : Springer Nature. - 1741-7015. ; 20:1
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundPlasmodium falciparum malaria is associated with anaemia-related morbidity, attributable to host, parasite and drug factors. We quantified the haematological response following treatment of uncomplicated P. falciparum malaria to identify the factors associated with malarial anaemia.MethodsIndividual patient data from eligible antimalarial efficacy studies of uncomplicated P. falciparum malaria, available through the WorldWide Antimalarial Resistance Network data repository prior to August 2015, were pooled using standardised methodology. The haematological response over time was quantified using a multivariable linear mixed effects model with nonlinear terms for time, and the model was then used to estimate the mean haemoglobin at day of nadir and day 7. Multivariable logistic regression quantified risk factors for moderately severe anaemia (haemoglobin < 7 g/dL) at day 0, day 3 and day 7 as well as a fractional fall >= 25% at day 3 and day 7.ResultsA total of 70,226 patients, recruited into 200 studies between 1991 and 2013, were included in the analysis: 50,859 (72.4%) enrolled in Africa, 18,451 (26.3%) in Asia and 916 (1.3%) in South America. The median haemoglobin concentration at presentation was 9.9 g/dL (range 5.0-19.7 g/dL) in Africa, 11.6 g/dL (range 5.0-20.0 g/dL) in Asia and 12.3 g/dL (range 6.9-17.9 g/dL) in South America. Moderately severe anaemia (Hb < 7g/dl) was present in 8.4% (4284/50,859) of patients from Africa, 3.3% (606/18,451) from Asia and 0.1% (1/916) from South America. The nadir haemoglobin occurred on day 2 post treatment with a mean fall from baseline of 0.57 g/dL in Africa and 1.13 g/dL in Asia. Independent risk factors for moderately severe anaemia on day 7, in both Africa and Asia, included moderately severe anaemia at baseline (adjusted odds ratio (AOR) = 16.10 and AOR = 23.00, respectively), young age (age < 1 compared to >= 12 years AOR = 12.81 and AOR = 6.79, respectively), high parasitaemia (AOR = 1.78 and AOR = 1.58, respectively) and delayed parasite clearance (AOR = 2.44 and AOR = 2.59, respectively). In Asia, patients treated with an artemisinin-based regimen were at significantly greater risk of moderately severe anaemia on day 7 compared to those treated with a non-artemisinin-based regimen (AOR = 2.06 [95%CI 1.39-3.05], p < 0.001).ConclusionsIn patients with uncomplicated P. falciparum malaria, the nadir haemoglobin occurs 2 days after starting treatment. Although artemisinin-based treatments increase the rate of parasite clearance, in Asia they are associated with a greater risk of anaemia during recovery.
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3.
  • Moritz, Juliane, et al. (författare)
  • Electron beam powder bed fusion of γ‐titanium aluminide : Effect of processing parameters on part density, surface characteristics and aluminum content
  • 2021
  • Ingår i: Metals. - : MDPI. - 2075-4701. ; 11:7
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma titanium aluminides are very interesting for their use in high‐performance applications such as aircraft engines due to their low density, high stiffness and favorable hightemperature properties. However, the pronounced brittleness of these intermetallic alloys is a major challenge for their processing through conventional fabrication methods. Additive manufacturing by means of electron beam powder bed fusion (EB‐PBF) significantly improves the processability of titanium aluminides due to the high preheating temperatures and facilitates complex components. The objective of this study was to determine a suitable processing window for EB‐PBF of the TNM‐B1 alloy (Ti‐43.5Al‐4Nb‐1Mo‐0.1B), using an increased aluminum content in the powder raw material to compensate for evaporation losses during the process. Design of experiments was used to evaluate the effect of beam current, scan speed, focus offset, line offset and layer thickness on porosity. Top surface roughness was assessed through laser scanning confocal microscopy. Scanning electron microscopy, electron backscatter diffraction (EBSD) and energydispersive X‐ray spectroscopy (EDX) were used for microstructural investigation and to analyze aluminum loss depending on the volumetric energy density used in EB‐PBF. An optimized process parameter set for achieving part densities of 99.9% and smooth top surfaces was derived. The results regarding microstructures and aluminum evaporation suggest a solidification via the β‐phase.
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4.
  • Moritz, Juliane, et al. (författare)
  • Influence of Electron Beam Powder Bed Fusion Process Parameters at Constant Volumetric Energy Density on Surface Topography and Microstructural Homogeneity of a Titanium Aluminide Alloy
  • 2023
  • Ingår i: Advanced Engineering Materials. - : John Wiley & Sons. - 1438-1656 .- 1527-2648. ; 25:15
  • Tidskriftsartikel (refereegranskat)abstract
    • In powder bed fusion additive manufacturing, the volumetric energy density E V is a commonly used parameter to quantify process energy input. However, recent results question the suitability of E V as a design parameter, as varying the contributing parameters may yield different part properties. Herein, beam current, scan velocity, and line offset in electron beam powder bed fusion (PBF-EB) of the titanium aluminide alloy TNM–B1 are systematically varied while maintaining an overall constant E V. The samples are evaluated regarding surface morphology, relative density, microstructure, hardness, and aluminum loss due to evaporation. Moreover, the specimens are subjected to two different heat treatments to obtain fully lamellar (FL) and nearly lamellar (NLγ) microstructures, respectively. With a combination of low beam currents, low-to-intermediate scan velocities, and low line offsets, parts with even surfaces, relative densities above 99.9%, and homogeneous microstructures are achieved. On the other hand, especially high beam currents promote the formation of surface bulges and pronounced aluminum evaporation, resulting in inhomogeneous banded microstructures after heat treatment. The results demonstrate the importance of considering the individual parameters instead of E V in process optimization for PBF-EB.
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5.
  • Moritz, Juliane, et al. (författare)
  • Influence of Two-Step Heat Treatments on Microstructure and Mechanical Properties of a β-Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion
  • 2023
  • Ingår i: Advanced Engineering Materials. - : John Wiley & Sons. - 1438-1656 .- 1527-2648. ; 25:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Additive manufacturing technologies, particularly electron beam powder bed fusion (PBF-EB/M), are becoming increasingly important for the processing of intermetallic titanium aluminides. This study presents the effects of hot isostatic pressing (HIP) and subsequent two-step heat treatments on the microstructure and mechanical properties of the TNM-B1 alloy (Ti–43.5Al–4Nb–1Mo–0.1B) fabricated via PBF-EB/M. Adequate solution heat treatment temperatures allow the adjustment of fully lamellar (FL) and nearly lamellar (NL-β) microstructures. The specimens are characterized by optical microscopy and scanning electron microscopy (SEM), X-ray computed tomography (CT), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The mechanical properties at ambient temperatures are evaluated via tensile testing and subsequent fractography. While lack-of-fusion defects are the main causes of failure in the as-built condition, the mechanical properties in the heat-treated conditions are predominantly controlled by the microstructure. The highest ultimate tensile strength is achieved after HIP due to the elimination of lack-of-fusion defects. The results reveal challenges originating from the PBF-EB/M process, for example, local variations in chemical composition due to aluminum evaporation, which in turn affect the microstructures after heat treatment. For designing suitable heat treatment strategies, particular attention should therefore be paid to the microstructural characteristics associated with additive manufacturing.
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6.
  • Moritz, Juliane, et al. (författare)
  • Locally Adapted Microstructures in an Additively Manufactured Titanium Aluminide Alloy Through Process Parameter Variation and Heat Treatment
  • 2023
  • Ingår i: Advanced Engineering Materials. - : John Wiley & Sons. - 1438-1656 .- 1527-2648. ; 25:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Electron beam powder bed fusion (PBF-EB/M) has been attracting great research interest as a promising technology for additive manufacturing of titanium aluminide alloys. However, challenges often arise from the process-induced evaporation of aluminum, which is linked to the PBF-EB/M process parameters. This study applies different volumetric energy densities during PBF-EB/M processing to deliberately adjust the aluminum contents in additively manufactured Ti–43.5Al–4Nb–1Mo–0.1B (TNM-B1) samples. The specimens are subsequently subjected to hot isostatic pressing (HIP) and a two-step heat treatment. The influence of process parameter variation and heat treatments on microstructure and defect distribution are investigated using optical and scanning electron microscopy, as well as X-ray computed tomography (CT). Depending on the aluminum content, shifts in the phase transition temperatures can be identified via differential scanning calorimetry (DSC). It is confirmed that the microstructure after heat treatment is strongly linked to the PBF-EB/M parameters and the associated aluminum evaporation. The feasibility of producing locally adapted microstructures within one component through process parameter variation and subsequent heat treatment can be demonstrated. Thus, fully lamellar and nearly lamellar microstructures in two adjacent component areas can be adjusted, respectively.
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7.
  • Trunschke, Annette, et al. (författare)
  • Towards Experimental Handbooks in Catalysis
  • 2020
  • Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 63:19-20, s. 1683-1699
  • Tidskriftsartikel (refereegranskat)abstract
    • The “Seven Pillars” of oxidation catalysis proposed by Robert K. Grasselli represent an early example of phenomenological descriptors in the field of heterogeneous catalysis. Major advances in the theoretical description of catalytic reactions have been achieved in recent years and new catalysts are predicted today by using computational methods. To tackle the immense complexity of high-performance systems in reactions where selectivity is a major issue, analysis of scientific data by artificial intelligence and data science provides new opportunities for achieving improved understanding. Modern data analytics require data of highest quality and sufficient diversity. Existing data, however, frequently do not comply with these constraints. Therefore, new concepts of data generation and management are needed. Herein we present a basic approach in defining best practice procedures of measuring consistent data sets in heterogeneous catalysis using “handbooks”. Selective oxidation of short-chain alkanes over mixed metal oxide catalysts was selected as an example.
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8.
  • Willner, Robin, et al. (författare)
  • Potential and challenges of additive manufacturing for topology optimized spacecraft structures
  • 2020
  • Ingår i: Journal of laser applications. - : American Institute of Physics (AIP). - 1042-346X .- 1938-1387. ; 32:3
  • Tidskriftsartikel (refereegranskat)abstract
    • This study focused on the potential of topology optimization (TO) for metallic tertiary structures of spacecrafts produced by the additive manufacturing (AM) technique laser powder bed fusion. First, a screening of existing conventionally manufactured products was carried out to evaluate the benefits of a redesign concerning product performance and the associated economic impact. As a result of the study, the most suitable demonstrator was selected. This reference structure was redesigned by TO taking into consideration the AM process constraints. Another major aim of this work was to evaluate the possibilities and challenges of AM (accuracies, surface quality, process parameters, postmachining, and mechanical properties) in addition to the redesign process. A comprehensive approach was implemented including detailed analysis of the powder, mechanical properties, in-process parameters, and nondestructive inspection (NDI). All measured values were used for a back loop to the design process, thereby providing a final robust redesign. Finally, the fine-tuned demonstrator was built up in an iterative process. The parts were tested under representative conditions for the application to verify the performance. The demonstrator qualification test campaign contained thermal cycling, vibration testing, static load testing, and NDI. Thus, an improvement in technology readiness level up to "near flight qualified" was reached.
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9.
  • Abbafati, Cristiana, et al. (författare)
  • 2020
  • Tidskriftsartikel (refereegranskat)
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10.
  • Arndt, Christoph, et al. (författare)
  • Laser Applications to Chemical, Security, and Environmental Analysis : introduction to the feature issue
  • 2023
  • Ingår i: Applied Optics. - 1559-128X. ; 62:6, s. 1-3
  • Tidskriftsartikel (refereegranskat)abstract
    • The eighteenth topical meeting on Laser Applications to Chemical, Security, and Environmental Analysis (LACSEA) was held in Vancouver, Canada from 11–15 July 2022, as part of the Optica Optical Sensors and Sensing Congress in a hybrid format allowing on-site and online attendance. The meeting featured a broad range of distinguished papers focusing on recent advances in laser and optical spectroscopy. A total of 52 contributed and invited papers were presented during the meeting, including topics such as photo-acoustic spectroscopy, imaging, non-linear technologies, frequency combs, remote sensing, environmental monitoring, aerosols, combustion diagnostics, hypersonic flow diagnostics, nuclear diagnostics, fs/ps applications, and machine learning and computational sensing.
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11.
  • Arnold, Natalie, et al. (författare)
  • C-reactive protein modifies lipoprotein(a)-related risk for coronary heart disease : the BiomarCaRE project
  • 2024
  • Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 45:12, s. 1043-1054
  • Tidskriftsartikel (refereegranskat)abstract
    • Background and Aims: Recent investigations have suggested an interdependence of lipoprotein(a) [Lp(a)]-related risk for cardiovascular disease with background inflammatory burden. The aim the present analysis was to investigate whether high-sensitive C-reactive protein (hsCRP) modulates the association between Lp(a) and coronary heart disease (CHD) in the general population.Methods: Data from 71 678 participants from 8 European prospective population-based cohort studies were used (65 661 without/6017 with established CHD at baseline; median follow-up 9.8/13.8 years, respectively). Fine and Gray competing risk-adjusted models were calculated according to accompanying hsCRP concentration (<2 and ≥2 mg/L).Results: Among CHD-free individuals, increased Lp(a) levels were associated with incident CHD irrespective of hsCRP concentration: fully adjusted sub-distribution hazard ratios [sHRs (95% confidence interval)] for the highest vs. lowest fifth of Lp(a) distribution were 1.45 (1.23-1.72) and 1.48 (1.23-1.78) for a hsCRP group of <2 and ≥2 mg/L, respectively, with no interaction found between these two biomarkers on CHD risk (Pinteraction = 0.82). In those with established CHD, similar associations were seen only among individuals with hsCRP ≥ 2 mg/L [1.34 (1.03-1.76)], whereas among participants with a hsCRP concentration <2 mg/L, there was no clear association between Lp(a) and future CHD events [1.29 (0.98-1.71)] (highest vs. lowest fifth, fully adjusted models; Pinteraction = 0.024).Conclusions: While among CHD-free individuals Lp(a) was significantly associated with incident CHD regardless of hsCRP, in participants with CHD at baseline, Lp(a) was related to recurrent CHD events only in those with residual inflammatory risk. These findings might guide adequate selection of high-risk patients for forthcoming Lp(a)-targeting compounds.
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12.
  • Arnold, Natalie, et al. (författare)
  • Impact of lipoprotein(a) level on low-density lipoprotein cholesterol– or apolipoprotein B–related risk of coronary heart disease
  • 2024
  • Ingår i: Journal of the American College of Cardiology. - : Elsevier. - 0735-1097 .- 1558-3597. ; 84:2, s. 165-177
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Conventional low-density lipoprotein cholesterol (LDL-C) quantification includes cholesterol attributable to lipoprotein(a) (Lp(a)-C) due to their overlapping densities.Objectives: The purposes of this study were to compare the association between LDL-C and LDL-C corrected for Lp(a)-C (LDLLp(a)corr) with incident coronary heart disease (CHD) in the general population and to investigate whether concomitant Lp(a) values influence the association of LDL-C or apolipoprotein B (apoB) with coronary events.Methods: Among 68,748 CHD-free subjects at baseline LDLLp(a)corr was calculated as “LDL-C—Lp(a)-C,” where Lp(a)-C was 30% or 17.3% of total Lp(a) mass. Fine and Gray competing risk-adjusted models were applied for the association between the outcome incident CHD and: 1) LDL-C and LDLLp(a)corr in the total sample; and 2) LDL-C and apoB after stratification by Lp(a) mass (≥/<90th percentile).Results: Similar risk estimates for incident CHD were found for LDL-C and LDL-CLp(a)corr30 or LDL-CLp(a)corr17.3 (subdistribution HR with 95% CI) were 2.73 (95% CI: 2.34-3.20) vs 2.51 (95% CI: 2.15-2.93) vs 2.64 (95% CI: 2.26-3.10), respectively (top vs bottom fifth; fully adjusted models). Categorization by Lp(a) mass resulted in higher subdistribution HRs for uncorrected LDL-C and incident CHD at Lp(a) ≥90th percentile (4.38 [95% CI: 2.08-9.22]) vs 2.60 [95% CI: 2.21-3.07]) at Lp(a) <90th percentile (top vs bottom fifth; Pinteraction0.39). In contrast, apoB risk estimates were lower in subjects with higher Lp(a) mass (2.43 [95% CI: 1.34-4.40]) than in Lp(a) <90th percentile (3.34 [95% CI: 2.78-4.01]) (Pinteraction0.49).Conclusions: Correction of LDL-C for its Lp(a)-C content provided no meaningful information on CHD-risk estimation at the population level. Simple categorization of Lp(a) mass (≥/<90th percentile) influenced the association between LDL-C or apoB with future CHD mostly at higher Lp(a) levels.
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13.
  • Backes, Claudia, et al. (författare)
  • Production and processing of graphene and related materials
  • 2020
  • Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results. Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs,
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14.
  • Baumeister, Hannah, et al. (författare)
  • A generalizable data-driven model of atrophy heterogeneity and progression in memory clinic settings
  • 2024
  • Ingår i: Brain : a journal of neurology. - 1460-2156. ; 147:7, s. 2400-2413
  • Tidskriftsartikel (refereegranskat)abstract
    • Memory clinic patients are a heterogeneous population representing various aetiologies of pathological aging. It is unknown if divergent spatiotemporal progression patterns of brain atrophy, as previously described in Alzheimer's disease (AD) patients, are prevalent and clinically meaningful in this group of older adults. To uncover distinct atrophy subtypes, we applied the Subtype and Stage Inference (SuStaIn) algorithm to baseline structural MRI data from 813 participants enrolled in the DELCODE cohort (mean ± SD age = 70.67 ± 6.07 years, 52% females). Participants were cognitively unimpaired (CU; n = 285) or fulfilled diagnostic criteria for subjective cognitive decline (SCD; n = 342), mild cognitive impairment (MCI; n = 118), or dementia of the Alzheimer's type (n = 68). Atrophy subtypes were compared in baseline demographics, fluid AD biomarker levels, the Preclinical Alzheimer Cognitive Composite (PACC-5), as well as episodic memory and executive functioning. PACC-5 trajectories over up to 240 weeks were examined. To test if baseline atrophy subtype and stage predicted clinical trajectories before manifest cognitive impairment, we analysed PACC-5 trajectories and MCI conversion rates of CU and SCD participants. Limbic-predominant and hippocampal-sparing atrophy subtypes were identified. Limbic-predominant atrophy first affected the medial temporal lobes, followed by further temporal and, finally, the remaining cortical regions. At baseline, this subtype was related to older age, more pathological AD biomarker levels, APOE ε4 carriership, and an amnestic cognitive impairment. Hippocampal-sparing atrophy initially occurred outside the temporal lobe with the medial temporal lobe spared up to advanced atrophy stages. This atrophy pattern also affected individuals with positive AD biomarkers and was associated with more generalised cognitive impairment. Limbic-predominant atrophy, in all and in only unimpaired participants, was linked to more negative longitudinal PACC-5 slopes than observed in participants without or with hippocampal-sparing atrophy and increased the risk of MCI conversion. SuStaIn modelling was repeated in a sample from the Swedish BioFINDER-2 cohort. Highly similar atrophy progression patterns and associated cognitive profiles were identified. Cross-cohort model generalizability, both on the subject and group level, were excellent, indicating reliable performance in previously unseen data. The proposed model is a promising tool for capturing heterogeneity among older adults at early at-risk states for AD in applied settings. The implementation of atrophy subtype- and stage-specific end-points may increase the statistical power of pharmacological trials targeting early AD.
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15.
  • Brandau, Benedikt, et al. (författare)
  • Absorbance study of powder conditions for laser additive manufacturing
  • 2022
  • Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 216
  • Tidskriftsartikel (refereegranskat)abstract
    • Absorbance is often used for simulations or validation of process parameters for powder-based laser materials processing. In this work, the absorbance of 39 metal powders for additive manufacturing is determined at 20 laser wavelengths. Different grain sizes and aging states for: steels, aluminum alloys, titanium alloys, Nitinol, high entropy alloy, chromium, copper, brass and iron ore were analyzed. For this purpose, the absorbance spectrum of the powders was determined via a dual-beam spectrometer in the range of λ = 330 - 1560 nm. At the laser wavelengths of λ = 450 nm, 633 nm and 650 nm, the absorbance averaged over all materials was found to increase by a factor of 2.4 up to 3.3 compared to the usual wavelength of λ = 1070 nm, with minimal variations in absorbance between materials. In the investigation of the aged or used powders, a loss of absorbance was detectable. Almost no changes from the point of view of processing aged and new AlSi10Mg powders, is expected for laser sources with λ = 450 nm. The resulting measurements provide a good basis for process parameters for a variety of laser wavelengths and materials, as well as a data set for improved absorbance simulations.
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16.
  • Catalano, Calogerina, et al. (författare)
  • Epistatic effect of TLR3 and cGAS-STING-IKKε-TBK1-IFN signaling variants on colorectal cancer risk
  • 2020
  • Ingår i: Cancer Medicine. - : Wiley. - 2045-7634. ; 9:4, s. 1473-1484
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: The TLR3/cGAS-STING-IFN signaling has recently been reported to be disturbed in colorectal cancer due to deregulated expression of the genes involved. Our study aimed to investigate the influence of potential regulatory variants in these genes on the risk of sporadic colorectal cancer (CRC) in a Czech cohort of 1424 CRC patients and 1114 healthy controls. Methods: The variants in the TLR3, CGAS, TMEM173, IKBKE, and TBK1 genes were selected using various online bioinformatic tools, such as UCSC browser, HaploReg, Regulome DB, Gtex Portal, SIFT, PolyPhen2, and miRNA prediction tools. Results: Logistic regression analysis adjusted for age and sex detected a nominal association between CRC risk and three variants, CGAS rs72960018 (OR: 1.68, 95% CI: 1.11-2.53, P-value =.01), CGAS rs9352000 (OR: 2.02, 95% CI: 1.07-3.84, P-value =.03) and TMEM173 rs13153461 (OR: 1.53, 95% CI: 1.03-2.27, P-value =.03). Their cumulative effect revealed a threefold increased CRC risk in carriers of 5-6 risk alleles compared to those with 0-2 risk alleles. Epistatic interactions between these genes and the previously genotyped IFNAR1, IFNAR2, IFNA, IFNB, IFNK, IFNW, IRF3, and IRF7 genes, were computed to test their effect on CRC risk. Overall, we obtained nine pair-wise interactions within and between the CGAS, TMEM173, IKBKE, and TBK1 genes. Two of them remained statistically significant after Bonferroni correction. Additional 52 interactions were observed when IFN variants were added to the analysis. Conclusions: Our data suggest that epistatic interactions and a high number of risk alleles may play an important role in CRC carcinogenesis, offering novel biological understanding for the CRC management.
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17.
  • Charmpilas, Nikolaos, et al. (författare)
  • Acyl-CoA-binding protein (ACBP) : a phylogenetically conserved appetite stimulator
  • 2020
  • Ingår i: Cell Death and Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, we reported that, in mice, hunger causes the autophagy-dependent release of a protein called acyl-CoA-binding protein or diazepam binding inhibitor (ACBP/DBI) from cells, resulting in an increase in plasma ACBP concentrations. Administration of extra ACBP is orexigenic and obesogenic, while its neutralization is anorexigenic in mice, suggesting that ACBP is a major stimulator of appetite and lipo-anabolism. Accordingly, obese persons have higher circulating ACBP levels than lean individuals, and anorexia nervosa is associated with subnormal ACBP plasma concentrations. Here, we investigated whether ACBP might play a phylogenetically conserved role in appetite stimulation. We found that extracellular ACBP favors sporulation in Saccharomyces cerevisiae, knowing that sporulation is a strategy for yeast to seek new food sources. Moreover, in the nematode Caenorhabditis elegans, ACBP increased the ingestion of bacteria as well as the frequency pharyngeal pumping. These observations indicate that ACBP has a phylogenetically ancient role as a 'hunger factor' that favors food intake.
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18.
  • Conlon, Thomas M, et al. (författare)
  • Inhibition of LTβR signalling activates WNT-induced regeneration in lung
  • 2020
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 588:7836, s. 151-156
  • Tidskriftsartikel (refereegranskat)abstract
    • Lymphotoxin β-receptor (LTβR) signalling promotes lymphoid neogenesis and the development of tertiary lymphoid structures1,2, which are associated with severe chronic inflammatory diseases that span several organ systems3-6. How LTβR signalling drives chronic tissue damage particularly in the lung, the mechanism(s) that regulate this process, and whether LTβR blockade might be of therapeutic value have remained unclear. Here we demonstrate increased expression of LTβR ligands in adaptive and innate immune cells, enhanced non-canonical NF-κB signalling, and enriched LTβR target gene expression in lung epithelial cells from patients with smoking-associated chronic obstructive pulmonary disease (COPD) and from mice chronically exposed to cigarette smoke. Therapeutic inhibition of LTβR signalling in young and aged mice disrupted smoking-related inducible bronchus-associated lymphoid tissue, induced regeneration of lung tissue, and reverted airway fibrosis and systemic muscle wasting. Mechanistically, blockade of LTβR signalling dampened epithelial non-canonical activation of NF-κB, reduced TGFβ signalling in airways, and induced regeneration by preventing epithelial cell death and activating WNT/β-catenin signalling in alveolar epithelial progenitor cells. These findings suggest that inhibition of LTβR signalling represents a viable therapeutic option that combines prevention of tertiary lymphoid structures1 and inhibition of apoptosis with tissue-regenerative strategies.
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19.
  • Dorigo, Wouter, et al. (författare)
  • The International Soil Moisture Network : Serving Earth system science for over a decade
  • 2021
  • Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 25:11, s. 5749-5804
  • Forskningsöversikt (refereegranskat)abstract
    • In 2009, the International Soil Moisture Network (ISMN) was initiated as a community effort, funded by the European Space Agency, to serve as a centralised data hosting facility for globally available in situ soil moisture measurements . The ISMN brings together in situ soil moisture measurements collected and freely shared by a multitude of organisations, harmonises them in terms of units and sampling rates, applies advanced quality control, and stores them in a database. Users can freely retrieve the data from this database through an online web portal (https://ismn.earth/en/, last access: 28 October 2021). Meanwhile, the ISMN has evolved into the primary in situ soil moisture reference database worldwide, as evidenced by more than 3000 active users and over 1000 scientific publications referencing the data sets provided by the network. As of July 2021, the ISMN now contains the data of 71 networks and 2842 stations located all over the globe, with a time period spanning from 1952 to the present. The number of networks and stations covered by the ISMN is still growing, and approximately 70 % of the data sets contained in the database continue to be updated on a regular or irregular basis. The main scope of this paper is to inform readers about the evolution of the ISMN over the past decade, including a description of network and data set updates and quality control procedures. A comprehensive review of the existing literature making use of ISMN data is also provided in order to identify current limitations in functionality and data usage and to shape priorities for the next decade of operations of this unique community-based data repository.
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20.
  • Fedina, Tatiana, et al. (författare)
  • Laser-assisted reduction of iron ore using aluminum powder
  • 2023
  • Ingår i: Journal of laser applications. - : American Institute of Physics (AIP). - 1042-346X .- 1938-1387. ; 35:2
  • Tidskriftsartikel (refereegranskat)abstract
    • This study reports on the laser-assisted reduction of iron ore waste using Al powder as areducing agent. Due to climate change and the global warming situation, it has become ofparamount importance to search for and/or develop green and sustainable processes for ironand steel production. In this regard, a new method for iron ore utilization is proposed in thiswork, investigating the possibility of iron ore waste reduction via metallothermic reaction withAl powder. Laser processing of iron ore fines was performed, focusing on the Fe2O3-Alinteraction behavior and extent of the iron ore reduction. The reaction between the materialsproceeded in a rather intense uncontrolled manner which led to a formation of Fe-rich domainsand alumina as two separate phases. In addition, a combination of Al2O3 and Fe2O3 melts aswell as transitional areas such as intermetallics were observed, suggesting the occurrence ofincomplete reduction reaction in isolated regions. The reduced iron droplets were prone toacquire a sphere-like shape and concentrated mainly near the surface of the Al2O3 melt or at theinterface with the iron oxide. Both SEM, EDS and WDS analyses were employed to analyzechemical composition, microstructure and morphological appearances of the reaction products.High-speed imaging was used to study the process phenomena and observe differences in themovement behavior of the particles. Furthermore, the measurements acquired from X-raycomputed microtomography revealed that approximately 2.4 % of iron was reduced during thelaser processing of Fe2O3-Al powder bed, most likely due to insufficient reaction time orinappropriate equivalence ratio of the two components.
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21.
  • Gruber, Samira, et al. (författare)
  • Comparison of dimensional accuracy and tolerances of powder bed based and nozzle based additive manufacturing processes
  • 2020
  • Ingår i: Journal of laser applications. - : American Institute of Physics (AIP). - 1042-346X .- 1938-1387. ; 32:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Additive manufacturing processes have the potential to produce near-net shaped complex final parts in various industries such as aerospace, medicine, or automotive. Powder bed based and nozzle based processes like laser metal deposition (LMD), laser powder bed fusion (LPBF), and electron beam melting (EBM) are commercially available, but selecting the most suitable process for a specific application remains difficult and mainly depends on the individual know-how within a certain company. Factors such as the material used, part dimension, geometrical features, as well as tolerance requirements contribute to the overall manufacturing costs that need to be economically reasonable compared to conventional processes. Within this contribution, the quantitative analysis of basic geometrical features such as cylinders, thin walls, holes, and cooling channels of a special designed benchmark demonstrator manufactured by LMD; LPBF and EBM are presented to compare the geometrical accuracy within and between these processes to verify existing guidelines, connect the part quality to the process parameters, and demonstrate process-specific limitations. The fabricated specimens are investigated in a comprehensive manner with 3D laser scanning and CT scanning with regard to dimensional and geometrical accuracy of outer and inner features. The obtained results will be discussed and achievable as-built tolerances for assessed demonstrator parts will be classified according to general tolerance classes described [DIN ISO 2768-1,Allgemeintoleranzen-Teil 1: Toleranzen fur Langen- und Winkelmasse ohne einzelne Toleranzeintragung(1991). Accessed 26 February 2018; DIN ISO 2768-2,Allgemeintoleranzen-Teil 2: Toleranzen fur Form und Lage ohne einzelne Toleranzeintragung(1991). Accessed 26 February 2018].
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22.
  • Gruber, Samira, et al. (författare)
  • Physical and Geometrical Properties of Additively Manufactured Pure Copper Samples Using a Green Laser Source
  • 2021
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 14:13
  • Tidskriftsartikel (refereegranskat)abstract
    • So far, copper has been difficult to process via laser powder bed fusion due to low absorption with the frequently used laser systems in the infrared wavelength range. However, green laser systems have emerged recently and offer new opportunities in processing highly reflective materials like pure copper through higher absorptivity. In this study, pure copper powders from two suppliers were tested using the same machine parameter sets to investigate the influence of the powder properties on the material properties such as density, microstructure, and electrical conductivity. Samples of different wall thicknesses were investigated with the eddy-current method to analyze the influence of the sample thickness and surface quality on the measured electrical conductivity. The mechanical properties in three building directions were investigated and the geometrical accuracy of selected geometrical features was analyzed using a benchmark geometry. It could be shown that the generated parts have a relative density of above 99.95% and an electrical conductivity as high as 100% International Annealed Copper Standard (IACS) for both powders could be achieved. Furthermore, the negative influence of a rough surface on the measured eddy-current method was confirmed.
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23.
  • Gruber, Samira, et al. (författare)
  • Process development for laser powder bed fusion of GRCop-42 using a 515 nm laser source
  • 2023
  • Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 35:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Copper is widely used in high heat flux and electrical applications because of its excellent electrical and thermal conductivity properties. Alloying elements such as chromium or nickel are added to strengthen the material, especially for higher temperatures. Cu4Cr2Nb, also known as GRCop-42, is a dispersion-strengthened copper-chromium-niobium alloy developed by NASA for high-temperature applications with high thermal and mechanical stresses such as rocket engines. Additive manufacturing (AM) enables applications with complex functionalized geometries and is particularly promising in the aerospace industry. In this contribution, a parametric study was performed for GRCop-42 and the AM process laser powder bed fusion (PBF-LB/M) using a green laser source for two-layer thicknesses of 30 and 60 µm. Density, electrical conductivity, hardness, microstructure, and static mechanical properties were analyzed. Various heat treatments ranging from 400 to 1000 °C and 30 min to 4 h were tested to increase the electrical conductivity and hardness. For both layer thicknesses, dense parameter sets could be obtained with resulting relative densities above 99.8%. Hardness and electrical conductivity could be tailored in the range of 103-219 HV2 and 24%-88% International Annealed Copper Standard (IACS) depending on the heat treatment. The highest ultimate tensile strength (UTS) obtained was 493 MPa. An aging temperature of 700 °C for 30 min showed the best combination of room temperature properties such as electrical conductivity of 83.76%IACS, UTS of 481 MPa, elongation at break (A) at 24%, and hardness of 125 HV2.
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24.
  • Haack, Maximilian, et al. (författare)
  • Comprehensive study on the formation of grain boundary serrations in additively manufactured Haynes 230 alloy
  • 2020
  • Ingår i: Materials Characterization. - : Elsevier. - 1044-5803 .- 1873-4189. ; 160
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, grain boundary serrations have been introduced in conventionally processed Haynes 230 through a slow-cooling heat treatment. The aim of this work was to utilize these heat treatments to introduce serrations in additively manufactured (Laser Metal Deposition) Haynes 230. Contrary to expectations, serrations already formed during the fast-cooling of the Laser Metal Deposition process. Electron Backscatter Diffraction was used to elucidate the underlying phenomenon for the emergence of serrations during fast-cooling. As a result, a hypothesis regarding a new mechanism responsible for the formation of grain boundary serrations was formulated. Additionally, specific characteristics of the Laser Metal Deposition process have been identified. This includes a columnar-to-equiaxed transition (CET) for slower feed rates, leading to smaller grains despite lower cooling rates; the observation of an abrupt increase in grain growth for a raised solution annealing temperature; the fact that serrations hinder uncontrolled grain growth and finally that the LMD-process leads to a finer carbide morphology compared to conventional manufacturing methods, potentially leading to an increased precipitation strengthening effect.
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25.
  • Heidowitzsch, Maximilian, et al. (författare)
  • Grain size manipulation by wire laser direct energy deposition of 316L with ultrasonic assistance
  • 2023
  • Ingår i: Journal of laser applications. - : AIP Publishing. - 1042-346X .- 1938-1387. ; 35:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The epitaxial growth of coarse and columnar grain structures along the build direction of additive manufactured metals is a usual phenomenon. As a result, as-built components often exhibit pronounced anisotropic mechanical properties, reduced ductility, and, hence, a high cracking susceptibility. To enhance the mechanical properties and processability of additive manufactured parts, the formation of equiaxed and fine grained structures is thought to be most beneficial. In this study, the potential of grain refinement by ultrasonic excitation of the melt pool during laser wire additive manufacturing has been investigated. An ultrasound system was developed and integrated in a laser wire deposition machine. AISI 316L steel was used as a substrate and feedstock material. A conversion of coarse, columnar grains (d(m) = 284.5 mu m) into fine, equiaxed grains (d(m) = 130.4 mu m) and a weakening of typical -fiber texture with increasing amplitude were verified by means of light microscopy, scanning electron microscopy, and electron backscatter diffraction analysis. It was demonstrated that the degree of grain refinement could be controlled by the regulation of ultrasound amplitude. No significant changes in the dendritic structure have been observed. The combination of sonotrode/melt pool direct coupling and the laser wire deposition process represents a pioneering approach and promising strategy to investigate the influence of ultrasound on grain refinement and microstructural tailoring.
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26.
  • Hendl, Julius, et al. (författare)
  • In Situ CT Tensile Testing of an Additively Manufactured and Heat-Treated Metastable ß-Titanium Alloy (Ti-5Al-5Mo-5V-3Cr)
  • 2021
  • Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 11:21
  • Tidskriftsartikel (refereegranskat)abstract
    • Additive manufacturing has been considered a suitable process for developing high-performance parts of medical or aerospace industries. The electron beam powder bed fusion process, EB-PBF, is a powder bed fusion process carried out in a vacuum, in which the parts are melted using a highly focused electron beam. The material class of metastable β-titanium alloys, and especially Ti-5Al-5Mo-5V-3Cr, show great potential for use as small and highly complex load-bearing parts. Specimens were additively manufactured with optimised process parameters and different heat treatments used in order to create tailored mechanical properties. These heat-treated specimens were analysed with regard to their microstructure (SEM) and their mechanical strength (tensile testing). Furthermore, in situ tensile tests, using a Deben CT5000 and a YXLON ff35 industrial µ-CT, were performed and failure-critical defects were detected, analysed and monitored. Experimental results indicate that, if EB-PBF-manufactured Ti-5553 is heat-treated differently, a variety of mechanical properties are possible. Regarding their fracture mechanisms, failure-critical defects can be detected at different stages of the tensile test and defect growth behaviour can be analysed.
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27.
  • Hendl, Julius, et al. (författare)
  • NDE for Additive Manufacturing
  • 2022. - 1
  • Ingår i: Handbook of Nondestructive Evaluation 4.0. - Cham : Springer. - 9783030732066 - 9783030732059 ; , s. 665-696
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • By means of additive manufacturing (AM) complex-shaped parts can be manufactured using a broad range of different materials. The latter can be supplied in the form of powder, wire, paste material, or even as foil. Various technologies are covered by the term “Additive Manufacturing,” for example, direct energy deposition (DED), laser powder bed fusion (LPBF), fused filament fabrication (FFF), or binder jetting printing (BJP). In all varieties, parts are manufactured layer by layer which results in changed material properties compared to conventional manufacturing routes, for example, mechanical properties or fatigue life. To reach a conformal material deposition without defects such as lack of fusion, delamination or cracking, an optimal process window with well-chosen parameters (e.g., beam power, spot size, scanning speed) has to be identified.For nondestructive evaluation (NDE), different approaches can be used to classify AM manufactured parts regarding their defect structure and consequentially their performance:1.Process optimization and understanding of defect formation in order to prevent defects 2.In situ measurements by a variety of integrated sensors and (IR) cameras for direct process observations 3.Post-processing NDE methods such as ultrasonic testing, X-ray, or computer tomography (CT)If the three approaches are simultaneously executed, a prediction of the effect of defects can be made for certain cases.
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28.
  • Hickmann, Thomas, et al. (författare)
  • Exploring Global Climate Policy Futures and Their Representation in Integrated Assessment Models
  • 2022
  • Ingår i: Politics and Governance. - : Cogitatio. - 2183-2463. ; 10:3, s. 171-185
  • Tidskriftsartikel (refereegranskat)abstract
    • The Paris Agreement, adopted in 2015, paved the way for a new hybrid global climate governance architecture with both bottom-up and top-down elements. While governments can choose individual climate goals and actions, a global stocktake and a ratcheting-up mechanism have been put in place with the overall aim to ensure that collective efforts will prevent increasing adverse impacts of climate change. Integrated assessment models show that current combined climate commitments and policies of national governments fall short of keeping global warming to 1.5 °C or 2 °C above preindustrial levels. Although major greenhouse gas emitters, such as China, the European Union, India, the United States under the Biden administration, and several other countries, have made new pledges to take more ambitious climate action, it is highly uncertain where global climate policy is heading. Scenarios in line with long-term temperature targets typically assume a simplistic and hardly realistic level of harmonization of climate policies across countries. Against this backdrop, this article develops four archetypes for the further evolution of the global climate governance architecture and matches them with existing sets of scenarios developed by integrated assessment models. By these means, the article identifies knowledge gaps in the current scenario literature and discusses possible research avenues to explore the pre-conditions for successful coordination of national policies towards achieving the long-term target stipulated in the Paris Agreement.
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29.
  • Hoetger, Alexander, et al. (författare)
  • Gate-Switchable Arrays of Quantum Light Emitters in Contacted Monolayer MoS2 van der Waals Heterodevices
  • 2021
  • Ingår i: Nano letters (Print). - : AMER CHEMICAL SOC. - 1530-6984 .- 1530-6992. ; 21:2, s. 1040-1046
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate electrostatic switching of individual, site-selectively generated matrices of single photon emitters (SPEs) in MoS2 van der Waals heterodevices. We contact monolayers of MoS2 in field-effect devices with graphene gates and hexagonal boron nitride as the dielectric and graphite as bottom gates. After the assembly of such gate-tunable heterodevices, we demonstrate how arrays of defects, that serve as quantum emitters, can be site-selectively generated in the monolayer MoS2 by focused helium ion irradiation. The SPEs are sensitive to the charge carrier concentration in the MoS2 and switch on and off similar to the neutral exciton in MoS2 for moderate electron doping. The demonstrated scheme is a first step for producing scalable, gate-addressable, and gate-switchable arrays of quantum light emitters in MoS2 heterostacks.
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30.
  • Illini, Oliver, et al. (författare)
  • Mobocertinib in Patients with EGFR Exon 20 Insertion-Positive Non-Small Cell Lung Cancer (MOON): An International Real-World Safety and Efficacy Analysis
  • 2024
  • Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 25:7
  • Tidskriftsartikel (refereegranskat)abstract
    • EGFR exon 20 (EGFR Ex20) insertion mutations in non-small cell lung cancer (NSCLC) are insensitive to traditional EGFR tyrosine kinase inhibitors (TKIs). Mobocertinib is the only approved TKI specifically designed to target EGFR Ex20. We performed an international, real-world safety and efficacy analysis on patients with EGFR Ex20-positive NSCLC enrolled in a mobocertinib early access program. We explored the mechanisms of resistance by analyzing postprogression biopsies, as well as cross-resistance to amivantamab. Data from 86 patients with a median age of 67 years and a median of two prior lines of treatment were analyzed. Treatment-related adverse events (TRAEs) occurred in 95% of patients. Grade >= 3 TRAEs were reported in 38% of patients and included diarrhea (22%) and rash (8%). In 17% of patients, therapy was permanently discontinued, and two patients died due to TRAEs. Women were seven times more likely to discontinue treatment than men. In the overall cohort, the objective response rate to mobocertinib was 34% (95% CI, 24-45). The response rate in treatment-naive patients was 27% (95% CI, 8-58). The median progression-free and overall survival was 5 months (95% CI, 3.5-6.5) and 12 months (95% CI, 6.8-17.2), respectively. The intracranial response rate was limited (13%), and one-third of disease progression cases involved the brain. Mobocertinib also showed antitumor activity following EGFR Ex20-specific therapy and vice versa. Potential mechanisms of resistance to mobocertinib included amplifications in MET, PIK3CA, and NRAS. Mobocertinib demonstrated meaningful efficacy in a real-world setting but was associated with considerable gastrointestinal and cutaneous toxicity.
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31.
  • Jansen, Iris E, et al. (författare)
  • Genome-wide meta-analysis for Alzheimer's disease cerebrospinal fluid biomarkers.
  • 2022
  • Ingår i: Acta neuropathologica. - : Springer Science and Business Media LLC. - 1432-0533 .- 0001-6322. ; 144:5, s. 821-842
  • Tidskriftsartikel (refereegranskat)abstract
    • Amyloid-beta 42 (Aβ42) and phosphorylated tau (pTau) levels in cerebrospinal fluid (CSF) reflect core features of the pathogenesis of Alzheimer's disease (AD) more directly than clinical diagnosis. Initiated by the European Alzheimer & Dementia Biobank (EADB), the largest collaborative effort on genetics underlying CSF biomarkers was established, including 31 cohorts with a total of 13,116 individuals (discovery n=8074; replication n=5042 individuals). Besides the APOE locus, novel associations with two other well-established AD risk loci were observed; CR1 was shown a locus for Aβ42 and BIN1 for pTau. GMNC and C16orf95 were further identified as loci for pTau, of which the latter is novel. Clustering methods exploring the influence of all known AD risk loci on the CSF protein levels, revealed 4 biological categories suggesting multiple Aβ42 and pTau related biological pathways involved in the etiology of AD. In functional follow-up analyses, GMNC and C16orf95 both associated with lateral ventricular volume, implying an overlap in genetic etiology for tau levels and brain ventricular volume.
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32.
  • Khani, Sajjad, et al. (författare)
  • Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function
  • 2024
  • Ingår i: Nature Metabolism. - 2522-5812. ; 6:6, s. 1053-1075
  • Tidskriftsartikel (refereegranskat)abstract
    • Promoting brown adipose tissue (BAT) activity innovatively targets obesity and metabolic disease. While thermogenic activation of BAT is well understood, the rheostatic regulation of BAT to avoid excessive energy dissipation remains ill-defined. Here, we demonstrate that adenylyl cyclase 3 (AC3) is key for BAT function. We identified a cold-inducible promoter that generates a 5′ truncated AC3 mRNA isoform (Adcy3-at), whose expression is driven by a cold-induced, truncated isoform of PPARGC1A (PPARGC1A-AT). Male mice lacking Adcy3-at display increased energy expenditure and are resistant to obesity and ensuing metabolic imbalances. Mouse and human AC3-AT are retained in the endoplasmic reticulum, unable to translocate to the plasma membrane and lack enzymatic activity. AC3-AT interacts with AC3 and sequesters it in the endoplasmic reticulum, reducing the pool of adenylyl cyclases available for G-protein-mediated cAMP synthesis. Thus, AC3-AT acts as a cold-induced rheostat in BAT, limiting adverse consequences of cAMP activity during chronic BAT activation. 
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33.
  • Kledwig, Christian, et al. (författare)
  • A Study on the accuracy of Thermography-based Temperature measurement in Powder-fed directed energy deposition
  • 2020
  • Ingår i: 20th CIRP Conference on Electro Physical and Chemical Machining. - : Elsevier. ; , s. 35-41
  • Konferensbidrag (refereegranskat)abstract
    • Due to continuous development and increasingly deep understanding of the additive process, directed-energy deposition (DED) is becoming more and more interesting for industrial use. However, both the number of influencing factors and the process complexity, still require well-trained operators who can monitor and understand the machine tools. In order to facilitate the operators and to enable longer unattended processes, higher process safety, reliable monitoring systems and closed-loop controller are required. For example, despite a large number of investigations, the monitoring and control of the temperature distribution within the work piece still poses a big challenge.This study focusses on workpiece temperature measurement using a thermal imaging camera that observes the entire machining area. In order examine the measurement error caused by different viewing angles (φ = 0 … 75°), object temperatures (T = 333 … 1073K), surface conditions (welded and milled) and materials (316L, Inconel 718 and CuAl10) commonly used in DED, several approaches were followed using a thermal camera.It was found that surface condition and material cause the greatest measuring errors (up to +325K |−453K).). However, the measuring errors can be significantly reduced by suitable selection of the emissivity, so that it is possible to measure even the milled CuAl10 surface at a known viewing angle with a measuring error of +13.3% |−10.9%.
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34.
  • Kledwig, Christian, et al. (författare)
  • Image-based algorithm for nozzle adhesion detection in powder-fed directed-energy deposition
  • 2020
  • Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 32:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The rapidly growing technological innovation of directed energy deposition leads to an increase in part complexity as well as quality and mechanical properties of manufacturable components. However, the variety of process parameters and influencing factors still requires skilled operators, who observe the machine tools. For an unobserved use of deposition welding machines, well parametrized and validated monitoring systems have to analyze the process to detect irregularities and finally initiate a machine stop. This study focuses on nozzle adhesions that frequently occur when tool or high-speed steels are processed. This effect leads to decreasing quality or ultimately to a failure of the whole welding process. In this work, the authors present an algorithm and the corresponding parametrization to automatically detect nozzle adhesions based on images from a coaxial camera, integrated in the laser head. The algorithm is based on a detailed image analysis from which temporal and spatial patterns are derived. In particular, the algorithm calculates a nozzle adhesion indicator based on the heat intensity distribution in an experimentally derived shaped area on the inner nozzle boundary. It is parametrized in such a way that process-critical adhesions are detected. The algorithm was parametrized using an experimental setup with four materials: stainless steel (X2CrNiMo17-12-2), tool steel (X35CrMoMn7-2-1), high-speed steel (HS6-5-2C), and the nickel-based alloy NiCr19NbMo.
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35.
  • Klein, Julian, et al. (författare)
  • Engineering the Luminescence and Generation of Individual Defect Emitters in Atomically Thin MoS2
  • 2021
  • Ingår i: ACS Photonics. - : AMER CHEMICAL SOC. - 2330-4022. ; 8:2, s. 669-677
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate the on-demand creation and positioning of photon emitters in atomically thin MoS2 with very narrow ensemble broadening and negligible background luminescence. Focused helium-ion beam irradiation creates 100s to 1000s of such mono-typical emitters at specific positions in the MoS2 monolayers. Individually measured photon emitters show anti-bunching behavior with a g(2)(0) similar to 0.23 and 0.27. From a statistical analysis, we extract the creation yield of the He-ion induced photon emitters in MoS2 as a function of the exposed area, as well as the total yield of single emitters as a function of the number of He ions when single spots are irradiated by He ions. We reach probabilities as high as 18% for the generation of individual and spectrally clean photon emitters per irradiated single site. Our results firmly establish 2D materials as a platform for photon emitters with unprecedented control of position as well as photophysical properties owing to the all-interfacial nature.
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36.
  • Kleineidam, Luca, et al. (författare)
  • Midlife occupational cognitive requirements protect cognitive function in old age by increasing cognitive reserve
  • 2022
  • Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 13
  • 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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37.
  • Laj, Paolo, et al. (författare)
  • A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
  • 2020
  • Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 13:8, s. 4353-4392
  • Tidskriftsartikel (refereegranskat)abstract
    • Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in situ near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant in situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.
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38.
  • Lehman, Joel, et al. (författare)
  • The Surprising Creativity of Digital Evolution: A Collection of Anecdotes from the Evolutionary Computation and Artificial Life Research Communities
  • 2020
  • Ingår i: Artificial Life. - : MIT Press - Journals. - 1530-9185 .- 1064-5462. ; 26:2, s. 274-306
  • Tidskriftsartikel (refereegranskat)abstract
    • Evolution provides a creative fount of complex and subtle adaptations that often surprise the scientists who discover them. However, the creativity of evolution is not limited to the natural world: Artificial organisms evolving in computational environments have also elicited surprise and wonder from the researchers studying them. The process of evolution is an algorithmic process that transcends the substrate in which it occurs. Indeed, many researchers in the field of digital evolution can provide examples of how their evolving algorithms and organisms have creatively subverted their expectations or intentions, exposed unrecognized bugs in their code, produced unexpectedly adaptations, or engaged in behaviors and outcomes, uncannily convergent with ones found in nature. Such stories routinely reveal surprise and creativity by evolution in these digital worlds, but they rarely fit into the standard scientific narrative. Instead they are often treated as mere obstacles to be overcome, rather than results that warrant study in their own right. Bugs are fixed, experiments are refocused, and one-off surprises are collapsed into a single data point. The stories themselves are traded among researchers through oral tradition, but that mode of information transmission is inefficient and prone to error and outright loss. Moreover, the fact that these stories tend to be shared only among practitioners means that many natural scientists do not realize how interesting and lifelike digital organisms are and how natural their evolution can be. To our knowledge, no collection of such anecdotes has been published before. This article is the crowd-sourced product of researchers in the fields of artificial life and evolutionary computation who have provided first-hand accounts of such cases. It thus serves as a written, fact-checked collection of scientifically important and even entertaining stories. In doing so we also present here substantial evidence that the existence and importance of evolutionary surprises extends beyond the natural world, and may indeed be a universal property of all complex evolving systems.
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39.
  • Lootens, Laurens, et al. (författare)
  • Matrix product operator symmetries and intertwiners in string-nets with domain walls
  • 2021
  • Ingår i: SciPost Physics. - : SCIPOST FOUNDATION. - 2542-4653. ; 10:3
  • Tidskriftsartikel (refereegranskat)abstract
    • We provide a description of virtual non-local matrix product operator (MPO) symmetries in projected entangled pair state (PEPS) representations of string-net models. Given such a PEPS representation, we show that the consistency conditions of its MPO symmetries amount to a set of six coupled equations that can be identified with the pentagon equations of a bimodule category. This allows us to classify all equivalent PEPS representations and build MPO intertwiners between them, synthesising and generalising the wide variety of tensor network representations of topological phases. Furthermore, we use this generalisation to build explicit PEPS realisations of domain walls between different topological phases as constructed by Kitaev and Kong [Commun. Math. Phys. 313 (2012) 351-373]. While the prevailing abstract categorical approach is sufficient to describe the structure of topological phases, explicit tensor network representations are required to simulate these systems on a computer, such as needed for calculating thresholds of quantum error-correcting codes based on string-nets with boundaries. Finally, we show that all these string-net PEPS representations can be understood as specific instances of Turaev-Viro state-sum models of topological field theory on three-manifolds with a physical boundary, thereby putting these tensor network constructions on a mathematically rigorous footing.
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40.
  • McGrath, Matthew J., et al. (författare)
  • The consolidated European synthesis of CO2 emissions and removals for the European Union and United Kingdom : 1990-2020
  • 2023
  • Ingår i: Earth System Science Data. - 1866-3508. ; 15:10, s. 4295-4370
  • Tidskriftsartikel (refereegranskat)abstract
    • Quantification of land surface-atmosphere fluxes of carbon dioxide (CO2) and their trends and uncertainties is essential for monitoring progress of the EU27+UK bloc as it strives to meet ambitious targets determined by both international agreements and internal regulation. This study provides a consolidated synthesis of fossil sources (CO2 fossil) and natural (including formally managed ecosystems) sources and sinks over land (CO2 land) using bottom-up (BU) and top-down (TD) approaches for the European Union and United Kingdom (EU27+UK), updating earlier syntheses (Petrescu et al., 2020, 2021). Given the wide scope of the work and the variety of approaches involved, this study aims to answer essential questions identified in the previous syntheses and understand the differences between datasets, particularly for poorly characterized fluxes from managed and unmanaged ecosystems. The work integrates updated emission inventory data, process-based model results, data-driven categorical model results, and inverse modeling estimates, extending the previous period 1990-2018 to the year 2020 to the extent possible. BU and TD products are compared with the European national greenhouse gas inventory (NGHGI) reported by parties including the year 2019 under the United Nations Framework Convention on Climate Change (UNFCCC). The uncertainties of the EU27+UK NGHGI were evaluated using the standard deviation reported by the EU member states following the guidelines of the Intergovernmental Panel on Climate Change (IPCC) and harmonized by gap-filling procedures. Variation in estimates produced with other methods, such as atmospheric inversion models (TD) or spatially disaggregated inventory datasets (BU), originate from within-model uncertainty related to parameterization as well as structural differences between models. By comparing the NGHGI with other approaches, key sources of differences between estimates arise primarily in activities. System boundaries and emission categories create differences in CO2 fossil datasets, while different land use definitions for reporting emissions from land use, land use change, and forestry (LULUCF) activities result in differences for CO2 land. The latter has important consequences for atmospheric inversions, leading to inversions reporting stronger sinks in vegetation and soils than are reported by the NGHGI. For CO2 fossil emissions, after harmonizing estimates based on common activities and selecting the most recent year available for all datasets, the UNFCCC NGHGI for the EU27+UK accounts for 926g±g13gTggCgyr-1, while eight other BU sources report a mean value of 948 [937,961]gTggCgyr-1 (25th, 75th percentiles). The sole top-down inversion of fossil emissions currently available accounts for 875gTggC in this same year, a value outside the uncertainty of both the NGHGI and bottom-up ensemble estimates and for which uncertainty estimates are not currently available. For the net CO2 land fluxes, during the most recent 5-year period including the NGHGI estimates, the NGHGI accounted for -91g±g32gTggCgyr-1, while six other BU approaches reported a mean sink of -62 [-117,-49]gTggCgyr-1, and a 15-member ensemble of dynamic global vegetation models (DGVMs) reported -69 [-152,-5]gTggCgyr-1. The 5-year mean of three TD regional ensembles combined with one non-ensemble inversion of -73gTggCgyr-1 has a slightly smaller spread (0th-100th percentiles of [-135,+45]gTggCgyr-1), and it was calculated after removing net land-atmosphere CO2 fluxes caused by lateral transport of carbon (crop trade, wood trade, river transport, and net uptake from inland water bodies), resulting in increased agreement with the NGHGI and bottom-up approaches. Results at the category level (Forest Land, Cropland, Grassland) generally show good agreement between the NGHGI and category-specific models, but results for DGVMs are mixed. Overall, for both CO2 fossil and net CO2 land fluxes, we find that current independent approaches are consistent with the NGHGI at the scale of the EU27+UK. We conclude that CO2 emissions from fossil sources have decreased over the past 30 years in the EU27+UK, while land fluxes are relatively stable: positive or negative trends larger (smaller) than 0.07 (-0.61)gTggCgyr-2 can be ruled out for the NGHGI. In addition, a gap on the order of 1000gTggCgyr-1 between CO2 fossil emissions and net CO2 uptake by the land exists regardless of the type of approach (NGHGI, TD, BU), falling well outside all available estimates of uncertainties. However, uncertainties in top-down approaches to estimate CO2 fossil emissions remain uncharacterized and are likely substantial, in addition to known uncertainties in top-down estimates of the land fluxes. The data used to plot the figures are available at 10.5281/zenodo.8148461 (McGrath et al., 2023).
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41.
  • Metzendorf, Christoph, et al. (författare)
  • Transcriptomic and Proteomic Analysis of Clear Cell Foci (CCF) in the Human Non-Cirrhotic Liver Identifies Several Differentially Expressed Genes and Proteins with Functions in Cancer Cell Biology and Glycogen Metabolism
  • 2020
  • Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 25:18, s. 4141-
  • Tidskriftsartikel (refereegranskat)abstract
    • Clear cell foci (CCF) of the liver are considered to be pre-neoplastic lesions of hepatocellular adenomas and carcinomas. They are hallmarked by glycogen overload and activation of AKT (v-akt murine thymoma viral oncogene homolog)/mTOR (mammalian target of rapamycin)-signaling. Here, we report the transcriptome and proteome of CCF extracted from human liver biopsies by laser capture microdissection. We found 14 genes and 22 proteins differentially expressed in CCF and the majority of these were expressed at lower levels in CCF. Using immunohistochemistry, the reduced expressions of STBD1 (starch-binding domain-containing protein 1), USP28 (ubiquitin-specific peptidase 28), monad/WDR92 (WD repeat domain 92), CYB5B (Cytochrome b5 type B), and HSPE1 (10 kDa heat shock protein, mitochondrial) were validated in CCF in independent specimens. Knockout of Stbd1, the gene coding for Starch-binding domain-containing protein 1, in mice did not have a significant effect on liver glycogen levels, indicating that additional factors are required for glycogen overload in CCF. Usp28 knockout mice did not show changes in glycogen storage in diethylnitrosamine-induced liver carcinoma, demonstrating that CCF are distinct from this type of cancer model, despite the decreased USP28 expression. Moreover, our data indicates that decreased USP28 expression is a novel factor contributing to the pre-neoplastic character of CCF. In summary, our work identifies several novel and unexpected candidates that are differentially expressed in CCF and that have functions in glycogen metabolism and tumorigenesis.
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42.
  • Montagna, Paolo, et al. (författare)
  • Dissolved neodymium isotopes in the Mediterranean Sea
  • 2022
  • Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037. ; 322, s. 143-169
  • Tidskriftsartikel (refereegranskat)abstract
    • The neodymium isotopic composition (εNd) of seawater is one of the most important geochemical tracers to investigate water mass provenance, which can also serve as a proxy to reconstruct past variations in ocean circulation. Nd isotopes have recently also been used to reconstruct past circulation changes in the Mediterranean Sea on different time scales. However, the modern seawater εNd dataset for the Mediterranean Sea, which these reconstructions are based on, is limited and up to now only 160 isotopic measurements are available for the entire basin. The lack of present-day data also limits our understanding of the processes controlling the Nd cycle and Nd isotopic distribution in this semi-enclosed basin. Here we present new εNd data from 24 depth profiles covering all Mediterranean sub-basins, which significantly increases the available dataset in the Mediterranean Sea. The main goal of our study is to better characterize the relationship between the dissolved Nd isotope distributions and major water masses in the Mediterranean Sea and to investigate the impact and relative importance of local non-conservative modifications, which include input of riverine particles and waters, aeolian-derived material and exchange with the sediments at continental margins. This comprehensive εNd dataset reveals a clear εNd – salinity correlation and a zonal and depth gradient with εNd systematically increasing from the western to the eastern Mediterranean basin (average εNd = −8.8 ± 0.8 and −6.7 ± 1 for the entire water column, respectively), reflecting the large-scale basin circulation. We have evaluated the conservative εNd behaviour in the Mediterranean Sea and quantified the non-conservative components of the εNd signatures by applying an Optimum Multiparameter (OMP) analysis and results from the Parametric Optimum Multiparameter (POMP) analysis of Jullion et al. (2017). The results of the present study combined with previously published Nd isotope values indicate that dissolved εNd behaves overall conservatively in the open Mediterranean Sea and show that its water masses are clearly distinguishable by their Nd isotope signature. However, misfits between measured and OMP- and POMP-derived εNd values exist in almost all sub-basins, especially in the eastern Levantine Basin and Alboran Sea at intermediate-deep depths, which can be explained by the influence of detrital lithogenic εNd signatures through interaction with highly radiogenic Nile sourced volcanic fractions and unradiogenic sediments, respectively.The radiogenic signature acquired in the eastern Levantine Basin is carried by the Levantine Intermediate Water and transferred conservatively to the entire Mediterranean at intermediate depths. Our measured εNd values and OMP- and POMP-derived results indicate that non-conservative contributions originating from sediment sources are then propagated by water mass circulation (with distinct preformed εNd) along the Mediterranean Sea through advection and conservative mixing. Mediterranean εNd effectively traces the mixing between the different water masses in this semi-enclosed basin and is a suitable water mass tracer.
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43.
  • Monteil, Guillaume, et al. (författare)
  • The regional European atmospheric transport inversion comparison, EUROCOM : First results on European-wide terrestrial carbon fluxes for the period 2006-2015
  • 2020
  • Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 20:20, s. 12063-12091
  • Tidskriftsartikel (refereegranskat)abstract
    • Atmospheric inversions have been used for the past two decades to derive large-scale constraints on the sources and sinks of CO2 into the atmosphere. The development of dense in situ surface observation networks, such as ICOS in Europe, enables in theory inversions at a resolution close to the country scale in Europe. This has led to the development of many regional inversion systems capable of assimilating these high-resolution data, in Europe and elsewhere. The EUROCOM (European atmospheric transport inversion comparison) project is a collaboration between seven European research institutes, which aims at producing a collective assessment of the net carbon flux between the terrestrial ecosystems and the atmosphere in Europe for the period 2006 2015. It aims in particular at investigating the capacity of the inversions to deliver consistent flux estimates from the country scale up to the continental scale. The project participants were provided with a common database of in situ-observed CO2 concentrations (including the observation sites that are now part of the ICOS network) and were tasked with providing their best estimate of the net terrestrial carbon flux for that period, and for a large domain covering the entire European Union. The inversion systems differ by the transport model, the inversion approach, and the choice of observation and prior constraints, enabling us to widely explore the space of uncertainties. This paper describes the intercomparison protocol and the participating systems, and it presents the first results from a reference set of inversions, at the continental scale and in four large regions. At the continental scale, the regional inversions support the assumption that European ecosystems are a relatively small sink (-0:21 ± 0:2 Pg C yr-1). We find that the convergence of the regional inversions at this scale is not better than that obtained in state-of-the-art global inversions. However, more robust results are obtained for subregions within Europe, and in these areas with dense observational coverage, the objective of delivering robust countryscale flux estimates appears achievable in the near future.
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44.
  • Moritz, Juliane, et al. (författare)
  • Additive Manufacturing of Titanium with Different Surface Structures for Adhesive Bonding and Thermal Direct Joining with Fiber-Reinforced Polyether-Ether-Ketone (PEEK) for Lightweight Design Applications
  • 2021
  • Ingår i: Metals. - : MDPI. - 2075-4701. ; 11:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Hybrid joints consisting of metals and fiber-reinforced polymer composites exhibit highly desirable properties for many lightweight design applications. This study investigates the potential of additively manufactured surface structures for enhancing the bond strength of such joints in comparison to face milled and laser structured surfaces. Titanium samples with different surface structures (as-built surface, groove-, and pin-shaped structures) were manufactured via electron beam melting and joined to carbon fiber-reinforced polyether-ether-ketone (PEEK) via adhesive bonding and thermal direct joining, respectively. Bond strength was evaluated by tensile shear testing. Samples were exposed to salt spray testing for 1000 h for studying bond stability under harsh environmental conditions. The initial tensile shear strengths of the additively manufactured samples were competitive to or in some cases even exceeded the values achieved with laser surface structuring for both investigated joining methods. The most promising results were found for pin-shaped surface structures. However, the hybrid joints with additively manufactured structures tended to be more susceptible to degradation during salt spray exposure. It is concluded that additively manufactured structures can be a viable alternative to laser surface structuring for both adhesive bonding and thermal direct joining of metal-polymer hybrid joints, thus opening up new potentials in lightweight design.
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45.
  • Moritz, Juliane, et al. (författare)
  • Hybrid manufacturing of titanium Ti-6Al-4V combining laser metal deposition and cryogenic milling
  • 2020
  • Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 107:7-8, s. 2995-3009
  • Tidskriftsartikel (refereegranskat)abstract
    • Hybrid manufacturing, which, e.g., combines additive manufacturing with conventional machining processes, can be a way of overcoming limitations currently encountered in additive manufacturing. Cryogenic milling might be a viable option for hard-to-cut materials, as it leaves a contamination-free surface and can increase surface quality and tool life compared to conventional cooling concepts. In this study, the influence of cryogenic milling with carbon dioxide on titanium Ti-6Al-4V specimens manufactured with laser metal deposition (LMD) was investigated regarding tool wear and surface integrity in comparison to dry machining and machining with cooling lubricants. Moreover, additional layers of material were deposited on top of conventionally and cryogenically machined surfaces by means of LMD. The interface zone was then examined for defects. The milling process was closely monitored by means of thermal and high-speed imaging. Optical and tactile surface analysis provided evidence that lower roughness values and improved surface qualities could be obtained with cryogenic machining in comparison to dry machining. Moreover, significantly less tool wear was observed when a cryogenic cooling medium was applied. Although the utilization of conventional cooling lubricants resulted in satisfying surface qualities, substantial residual contamination on the milled surface was detected by means of fluorescence analysis. These contaminants are suspected to cause defects when the next layer of material is deposited. This is supported by the fact that pores were found in the weld bead applied on top of the milled specimens by means of LMD. Conversely, cryogenic machining resulted in very clean surfaces due to the residue-free evaporation of the coolant. Hence, a good metallurgical bonding between the weld bead and the milled substrate could be achieved. The results indicate the great potential of cryogenic milling in hybrid manufacturing, especially in terms of intermediate machining, as it provides residue-free surfaces for subsequent material deposition without an additional cleaning step and can significantly prolongate tool life.
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46.
  • Müller, Eike Christoph (författare)
  • Axionlike particles, quantum loops, and supernovae : The role of quantum loop corrections for astrophysical ALPs
  • 2022
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In this thesis the quantum field theory and astrophysical phenomenology of axionlike particles (ALPs) are studied. The effective field theory of ALPs is reviewed with a special focus on quantum loops, the renormalization group equations, and the equivalent forms of the interaction between ALPs and fermions.To study the phenomenology of ALPs, both as dark matter candidate in the first paper that this thesis is based on, and as they are produced in supernova explosions in the second paper, an effective coupling between ALPs and photons is defined. In this way, the full one-loop effect of ALP-electron interactions can straightforwardly be incorporated in phenomenological analyses.It is pointed out that the effective coupling is different in decay and ALP-photon conversion processes. Importantly, the resulting loop-induced ALP-photon conversion rate does not vanish for ALPs much lighter than the electron, as was often stated in the literature.With this field theoretical basis, it is pointed out in the first paper that the decay of ALPs into photons via quantum loops has severe consequences for direct detection searches of ALP dark matter. In a large part of the parameter space that these experiments are sensitive to, the ALP would either not be long-lived enough to be dark matter, or the x-rays or gamma-rays originating from the decays of the ALP relic density should have been observed by indirect detection searches. Hence, while more heavy and strongly interacting ALPs coupled to electrons cannot be dark matter, many relatively lighter and weaker interacting models are ruled out already by indirect detection constraints.Furthermore, ALPs can be produced efficiently in supernovae even if they interact only very weakly. The absence of anomalous cooling in SN1987A constrains the ALP-photon and ALP-electron interactions. Similarly, since no gamma-rays arrived on earth directly after the observation of the neutrino burst of SN1987A, further constraints can be derived.Using the effective loop-induced coupling, some of the strongest bounds on the coupling between electrons and ALPs in the keV and MeV mass range are calculated in the second paper. Additionally, some technical details of the calculation are discussed and improved.
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47.
  • Müller, Michael, et al. (författare)
  • Additive Manufacturing of β-NiAl by Means of Laser Metal Deposition of Pre-Alloyed and Elemental Powders
  • 2021
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 14:9
  • Tidskriftsartikel (refereegranskat)abstract
    • The additive manufacturing (AM) technique, laser metal deposition (LMD), combines the advantages of near net shape manufacturing, tailored thermal process conditions and in situ alloy modification. This makes LMD a promising approach for the processing of advanced materials, such as intermetallics. Additionally, LMD allows the composition of a powder blend to be modified in situ. Hence, alloying and material build-up can be achieved simultaneously. Within this contribution, AM processing of the promising high-temperature material β-NiAl, by means of LMD, with elemental powder blends, as well as with pre-alloyed powders, was presented. The investigations showed that by applying a preheating temperature of 1100 °C, β-NiAl could be processed without cracking. Additionally, by using pre-alloyed, as well as elemental powders, a single phase β-NiAl microstructure can be achieved in multi-layer build-ups. Major differences between the approaches were found within substrate near regions. For in situ alloying of Ni and Al, these regions are characterized by an inhomogeneous elemental distribution in a layerwise manner. However, due to the remelting of preceding layers during deposition, a homogenization can be observed, leading to a single-phase structure. This shows the potential of high temperature preheating and in situ alloying to push the development of new high temperature materials for AM.
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48.
  • Müller, Michael, et al. (författare)
  • Laser-based directed energy deposition and characterisation of cBN-reinforced NiAl-based coatings
  • 2024
  • Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Nature. - 0268-3768 .- 1433-3015. ; 134:1-2, s. 657-675
  • Tidskriftsartikel (refereegranskat)abstract
    • Within this study, the alloy NiAl–2.5Ta–7.5Cr is investigated as a new matrix material for cBN-reinforced abrasive turbine blade tip coatings as currently used NiCoCrAlY matrix alloys suffer from insufficient strength at the high operating temperatures. Laser-based directed energy deposition with blown powder was applied to produce cBN reinforced NiAl-based coatings on monocrystalline CMSX-4 substrates. For this, powdery titanium-coated cBN and NiAl–2.5Ta–7.5Cr material were co-injected into the process zone to achieve an in situ formation of a NiAl–2.5Ta–7.5Cr/cBN composite. In order to overcome challenges such as cracking susceptibility, inductive preheating of the substrate up to 800 °C was used. Optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, as well as electron backscatter diffraction were applied to analyse the fabricated samples’ microstructure. Additionally, the mechanical properties were evaluated by means of microhardness mappings. This work demonstrates the feasibility of in situ forming a metal matrix composite with a homogeneous distribution of cBN particles. The results show the beneficial effect of high-temperature preheating on the crack formation. However, the study also reveals challenges such as cracking induced by the injected cBN particles as well as severe intermixing of substrate and coating, which yields spatially resolved deviations in the chemical composition and resulting variations in microstructure and hardness.
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49.
  • Müller, Michael, et al. (författare)
  • Microstructure of NiAl-Ta-Cr in situ alloyed by induction-assisted laser-based directed energy deposition
  • 2024
  • Ingår i: Materials & design. - : Elsevier Ltd. - 0264-1275 .- 1873-4197. ; 238
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of new high temperature materials for coatings as well as structural components is an important topic to contribute to a higher efficiency and sustainability of e.g. gas turbine engines. One promising new class of high temperature materials are NiAl-based alloys. Within this study, the microstructure and microhardness of NiAl-Ta-Cr alloys with varying Cr and Ta content were investigated. Graded specimens were fabricated by laser-based directed energy deposition utilizing an in situ alloying approach by mixing elemental Ta and Cr as well as pre-alloyed NiAl powder. Thermodynamic calculations were performed to design the alloy compositions beforehand. Inductive preheating of the substrate was used to counter the challenge of cracking due to the high brittleness. The results show that the cracking decreases with increasing preheating temperature. However, even at 700 °C, the cracking cannot be fully eliminated. Scanning electron microscopy, X-ray diffraction and electron backscatter diffraction revealed the formation of the phases B2-NiAl, A2-Cr and C14-NiAlTa within NiAl-Ta and NiAl-Cr alloys. For NiAl-Ta-Cr compositions, deviations regarding the phase formation between calculation and experiment were observed. Maximum hardness values were achieved within the NiAl-Ta and NiAl-Ta-Cr systems for the eutectic compositions at 14 at.-% Ta with maximum values above 900 HV0.1.
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50.
  • Müller, Michael, et al. (författare)
  • Multimaterial Additive Manufacturing of graded Laves phase reinforced NiAlTa structures by means of Laser Metal Deposition
  • 2022
  • Ingår i: Advanced Engineering Materials. - : John Wiley & Sons. - 1438-1656 .- 1527-2648. ; 24:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, the Additive Manufacturing (AM) technology Laser Metal Deposition (LMD) has gained a lot of attention for processing crack prone high temperature materials such as nickel based superalloys or intermetallics. This contribution presents a feasibility study on LMD of a graded transition from binary ß-NiAl to Ni50Al42Ta8 with the aim to show the possibility of manufacturing ß-NiAl based structures with a spatially resolved microstructure and subsequently tailored mechanical properties. For achieving this the alloys Ni50Al50 and Ni50Al42Ta8 are co-injected into the process zone and the powder feeding rates are adapted in a layer-wise manner. Due to pre-heating temperatures of up to 1000 °C the transition can be manufactured with high relative density and a low degree of cold cracking. Scanning electron microscopy of the transition zone shows the formation of a fine dendritic microstructure consisting of ß-NiAl dendritic and NiAlTa interdendritic regions. Large area energy dispersive x-ray analysis reveals a gradient in NiAlTa Laves phase content with increasing build height. The observed volume fraction of Laves phase corresponds well to reported values from cast ingots. Finally, hardness measurements along the build-up direction show an increase in hardness from 300 HV0.1 to 680 HV0.1 indicating a tremendous increase in tensile strength.
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