Magnetization reversal mechanism of ramified and compact Co islands on Pt(111)

We report on the magnetization reversal mechanism of Co islands on Pt(111) as a function of their size and shape. We measure the zero-field susceptibility chi(T) and low-temperature magnetization curves M(H) with in situ magneto-optical Kerr effect. Together with the island morphology deduced from scanning tunneling microscopy, this creates sufficient information to determine both the magnetization reversal mechanism and the distribution of anisotropy energies between perimeter and surface atoms. We find a transition from quasicoherent rotation to domain wall nucleation and propagation with a critical size of 350 atoms for ramified, and of 600 atoms for compact islands

The consolidated European synthesis of CO2 emissions and removals for the European Union and United Kingdom:1990-2020

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).</p

The consolidated European synthesis of CO2 emissions and removals for the European Union and United Kingdom: 1990–2020

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 926 ± 13 Tg C yr−1, while eight other BU sources report a mean value of 948 [937,961] Tg C yr−1 (25th, 75th percentiles). The sole top-down inversion of fossil emissions currently available accounts for 875 Tg C 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 −91 ± 32 Tg C yr−1, while six other BU approaches reported a mean sink of −62 [] Tg C yr−1, and a 15-member ensemble of dynamic global vegetation models (DGVMs) reported −69 [] Tg C yr−1. The 5-year mean of three TD regional ensembles combined with one non-ensemble inversion of −73 Tg C yr−1 has a slightly smaller spread (0th–100th percentiles of [] Tg C yr−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) Tg C yr−2 can be ruled out for the NGHGI. In addition, a gap on the order of 1000 Tg C yr−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 https://doi.org/10.5281/zenodo.8148461 (McGrath et al., 2023)

Decompression and Fracturing Caused by Magmatically Induced Thermal Stresses

Studies of host rock deformation around magmatic intrusions usually focus on the development of stresses directly related to the intrusion process. This is done either by considering an inflating region that represents the intruding body, or by considering multiphase deformation. Thermal processes, especially volume changes caused by thermal expansion are typically ignored. We show that thermal stresses around upper crustal magma bodies are likely to be significant and sufficient to create an extensive fracture network around the magma body by brittle yielding. At the same time, cooling induces decompression within the intrusion, which can promote the appearance of a volatile phase. Volatile phases and the development of a fracture network around the inclusion may thus be the processes that control magmatic‐hydrothermal alteration around intrusions. This suggests that thermal stresses likely play an important role in the development of magmatic systems. To quantify the magnitude of thermal stresses around cooling intrusions, we present a fully compressible 2D visco‐elasto‐plastic thermo‐mechanical numerical model. We utilize a finite difference staggered grid discretization and a graphics processing unit based pseudo‐transient solver. First, we present purely thermo‐elastic solutions, then we include the effects of viscous relaxation and plastic yielding. The dominant deformation mechanism in our models is determined in a self‐consistent manner, by taking into account stress, pressure, and temperature conditions. Using experimentally determined flow laws, the resulting thermal stresses can be comparable to or even exceed the confining pressure. This suggests that thermal stresses alone could result in the development of a fracture network around magmatic bodies.Plain Language Summary: Quantifying the stresses that magma bodies exert on the surrounding rocks is an important part of understanding mechanical processes that control the evolution of magmatic systems and volcanic eruptions. Previous analytical or numerical models typically describe the mechanical response to changes in magma volume due to intrusion or extraction of magma. However, volume changes related to thermal expansion/contraction around a cooling magma body are often neglected. Here, we develop a new software which runs on modern graphics processing unit machines, to quantity the effect of this process. The results show that stresses due to thermal expansion/contraction are significant, and often large enough to fracture the rocks nearby the magma body. Such fracture networks may form permeable pathways for the magma or for fluids such as water and CO2, thus influencing the evolution of magmatic and hydrothermal systems. Finally we show that cooling and shrinking of magma bodies causes significant decompression which can influence the chemical evolution of the magma during crystallization and devolatilization.Key Points: We present a numerical quantification of the effect of thermal stresses in visco‐elasto‐plastic rock with tensile and dilatant shear failure. The pressure drop in thermally contracting upper crustal magma bodies can exceed 100 MPa, potentially triggering devolatilization. Thermal cracking can create an extensive fracture network around an upper crustal magma body.European Research Council http://dx.doi.org/10.13039/501100000781https://zenodo.org/record/6958273https://doi.org/10.5281/zenodo.695827

Damage Analysis of Ship Collisions with Offshore Wind Turbine Foundations

Nowadays, a large number of wind turbines are being installed offshore due to more stable and steady flow of wind at sea and also less noise and visual impact compared to onshore wind farms. With the growing number of offshore wind installations, particular attention should be paid to the safe operation of assets. Offshore wind assets are subject to extreme environmental conditions and high dynamic stresses caused by wind, waves and currents. More importantly, they are largely exposed to hazards associated with collision with either commercial ships or infield support vessels passing closely at high speeds. To date, the damage analysis of collisions between infield support vessels and offshore wind turbine foundations has received very limited attention. In this study, a numerical nonlinear finite element analysis (NLFEA) approach is developed to evaluate the damage to wind turbine foundations when stricken by an offshore support vessel. The model is applied to a case study where 4000 tons class vessels collide with two common types of fixed-bottom foundations, namely monopile and jacket structure in shallow and deep waters respectively. Various accident scenarios are identified and the resulting damage to wind turbine foundations are analyzed. The number, location and the extent of damage to the members in each scenario are determined and the effects of reinforcement on the structure response are evaluated. The results of this research provide a good understanding of the factors that affect magnitude of damage caused by ship-wind turbine collision accidents and give an insight on how the next generation of wind turbine foundations can be designed in a more “collision-friendly” way

Oxidative stability and microbial growth of turkey breast fillets during refrigerated storage as influenced by feed supplementation with olive leaves, oregano and/or alpha-tocopheryl acetate

1. The aim of this study was to evaluate the inhibitory potential of feed supplementation with olive leaves, oregano and/or alpha-tocopheryl acetate on microbial growth and lipid oxidation of turkey breast fillets during refrigerated storage. 2. A total of 40 turkeys, allocated to 5 groups of 8 birds each, were fed on diets supplemented with olive leaves at 10 g/kg, oregano at 10 g/kg or alpha-tocopheryl acetate at 150 or 300 mg/kg. Following slaughter, fillets from breast were stored at 4 degrees C in the dark for 12 d, and lipid oxidation and microbial growth were assessed. 3. Results showed that dietary olive leaves were more effective than oregano at inhibiting lipid oxidation, but were inferior to dietary supplementation of 300 mg alpha-tocopheryl acetate/kg. In turn, -tocopheryl acetate supplementation at 150 mg/kg was effective at inhibiting lipid oxidation compared to the control but inferior to oregano supplementation. 4. Total viable counts, lactic acid bacteria, Enterobacteriaceae and psychrotrophic bacteria counts were all increased in breast fillets of all groups throughout the refrigerated storage. Diet supplementation with alpha-tocopheryl acetate had no effect on the bacterial counts recorded in the control group, but diet supplementation with olive leaves or oregano resulted in a decrease of all bacterial counts at d 2 of storage and thereafter; during this period, oregano was more effective at inhibiting bacterial growth compared with olive leaves. 5. Therefore, if shown clinically to be safe and having beneficial effects invivo, olive leaves and oregano might be utilised in novel applications as nutritional supplements or functional food components