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Global demand for vegetable oil is projected to expand to 28 Mt by 2028. Oilseed rape (OSR) is the predominant oilseed crop in Europe. Its nutritional value is determined by seed oil content and fatty acids (FAs) composition. Insect pollination increases seed oil content, however, its benefit on FAs composition remains unknown. In this study, we address this gap by investigating the variation of OSR seed oil content and FAs composition along a gradient of bee abundance in farmed OSR fields. We used a pollinator exclusion experiment to disentangle the contribution of pollination processes, i.e. wind, self and insect pollination. We show that bees improved OSR nutritional value by increasing amount of poly-unsaturated FAs and decreasing the amount saturated and trans-saturated FAs. In addition, oil content was higher in seeds with than without access to pollinators. Our study provides for the first time, to the best of our knowledge, evidence that insect pollination enhances the quality value of OSR oil by affecting FAs composition. Such effect implies potential negative consequences with any further decline of pollinator abundance. More investigations are also needed to better understand the mechanisms by which insect pollination affects FAs composition, and the way to enhance such mechanisms.

High Entropy Alloys (HEAs) are prospective materials for nuclear fusion reactors and were irradiated in this study at a broad range of energetic ion fluences. Different ion masses (Cu and Au ions) and energies (3 and 5 MeV) were selected to investigate dpa (displacement per atom) development, radiation defect accumulation based on prevailing collision processes (Au ions) and ionization processes (Cu ions) in various HEAs. The studied HEAs differ in terms of elemental composition, internal morphology (grain structure) and other modifiers. Dpa values of 1 to ∼66 were achieved at Cu and Au ion fluences from 4 × 1014 to 1.3 × 1016 ions.cm−2 at room temperature, which generated varying levels of lattice damage. Theoretical simulations were performed to estimate the energy stopping and dpa depth distribution using SRIM code and compared with Au-concentration depth profiles determined by Rutherford backscattering spectrometry for Au-ions with 3 MeV ion energy. The prevailing energy losses of ions via ionization processes for Cu-5 MeV ions were found to increase the damage through lattice strain and probable lattice distortion, although the main defect introduction is expected to occur via collisions during nuclear stopping. Structural modification and defect accumulation were investigated by positron annihilation spectroscopy (PAS), which revealed a broader damaged layer with defects, where HEA-Nb (NbCrFeMnNi) exhibited the least damage accumulation from chosen alloys with no strong relation to the Au-5 MeV ion implantation fluence, whereas strong defect accumulation was recorded in the Au-ion implanted Eurofer97 used for comparison and HEA-Co (CoCrFeMnNi). PAS analysis also allowed defect sizes to be determined as an additional structural characteristic. The observed trends were also confirmed by thermal property analysis, with a worsening of thermal effusivity recorded after the irradiation in HEA-Co and Eurofer97. The worsening of the thermal properties was confirmed by the layer thickness, where the layer identified by PAS was found to be broader than the SRIM theoretical predictions. Nanoindentation measurements confirmed less pronounced radiation hardening of HEA-Nb relative to that observed in HEA-Co and Eurofer97. Transmission Electron Microscopy (TEM) analysis revealed layer thicknesses in reasonable agreement with the dpa depth profiles. The thermal effusivity decreased in the surface-irradiated layer in all investigated samples, the least influenced material was HEA-Nb.

For a future commercial fusion reactor, the joining of tungsten and steel will be of vital importance, covering the main part of the plasma facing area. However, the large difference, of more than a factor of 2, in the coefficient of thermal expansion (CTE) of W and steel results in high thermal stresses at their interface. The cyclic nature of the operation can cause fatigue effects and could result in a premature failure of the joint.One possible solution is the insertion of a functionally graded material (FGM), with varying the CTE, as an interlayer between tungsten and steel, which could reduce these stresses. In this study, two processes, atmospheric plasma spraying (APS) and spark plasma sintering (SPS), are utilized to manufacture such FGMs. The gradation was accomplished by using two or three layers with a thickness of 0.5 mm each.Another principle is the insertion of a ductile metal interlayer, which reduces the stress by plastic deformation. Vanadium and titanium foils of varying thickness were chosen, as both have a CTE in between W and steel and V forms a solid solution with W and Fe. These and a direct W-steel joint as baseline reference were made by current-assisted diffusion bonding. All samples consist of 3 mm thick W and steel tiles allowing a direct comparison of the different technologies.An efficient high heat flux benchmark test procedure was developed and performed to investigate and compare the potential of the different joining technologies. For this, the complete stacks were brazed on actively cooled copper cooling modules and tested with high stationary heat loads of up to 5 MW/m2 with 200 cycles at each level in the JUDITH 2 facility. Detailed thermal analysis including comparison with prediction based on FEM simulation are presented to understand the cause of the failure and track the degradation. This study allows to help focusing the further development of W-steel joining technologies.

Nuclear fusion is a potential pathway to finding a sustainable, carbon-free energy source. Some critical components of the fusion reactors are planned to be coated by tungsten. For the task, thermal spraying in vacuum or protective atmosphere can be employed, offering several advantages such as easy preparation of advanced feedstock for deposition of functionally graded composites. Such coatings could be a viable approach to avoid the thermal expansion coefficient mismatch between the W coating and the steel components. In this study, radio-frequency inductively-coupled plasma spray method was used to deposit W-steel composite coatings of three different W ratios, as well as a functionally graded coating consisting of the three composites and a pure W top coat. The coatings exhibited a high-quality microstructure, without intermetallic or oxide phases formation. Thermal diffusivity and conductivity of the coatings was measured at 100 °C and 600 °C, with the values falling into range between the bulk steel and plasma sprayed W. In conclusion, we have shown that the RF-ICP technology is suitable for preparation of tungsten-steel graded deposits and the outputs are now prepared for other testing and a following upscaling to the industry-relevant size.

The realization of the first wall (FW), which is composed of a protective tungsten (W) armor covering the structural steel material, is a critical challenge in the development of future fusion reactors. Due to the different coefficients of thermal expansion (CTE) of W and steel, the direct joining of them results in cyclic thermal stress at their bonding seam during the operation of the fusion reactor. To address this issue, this study benchmarks two joining concepts. The first concept uses an atmospheric plasma sprayed graded interlayer composed of W/steel composites with a varying content of W and steel to gradually change the CTE. The second concept uses a spark plasma sintered graded interlayer. Furthermore, in order to benchmark these concepts, a directly bonded W-steel reference joint as well as a W-steel joint featuring a vanadium interlayer were also tested. These joints were tested under steady-state high heat flux cyclic loading, starting from a heat flux of 1 MW/m2 up to 4.5 MW/m2, with stepwise increments of 0.5 MW/m2. At each heat flux level, 200 thermal cycles were performed. The joints featuring a sintered graded interlayer survived only until 1.5 MW/m2 of loading, while the joint featuring plasma sprayed graded interlayer and V interlayer survived until 3 MW/m2.

Management of perennial weeds has become increasingly complex with the reduction of herbicide use and tillage. Their capacity to store nutrients into vegetative organs and to regenerate to establish new individuals makes them very persistent and hard to control. A key aspect for managing perennial weeds is to minimise storage reserves to reduce vegetative regeneration. For that prospect, better knowledge of the regrowth capacities from storage organs is needed. Our work focused on the mechanistic understanding of belowground regrowth dynamics from fragments of Elymus repens rhizomes by analysing the effect of source and sink factors. The effect of rhizome fragment weight (i.e., source) and the number of regrowing buds and belowground shoots (i.e., sinks) was assessed for four mechanisms: sprouting, belowground shoot elongation, belowground shoot biomass to length conversion and biomass allocation to belowground shoots versus roots. Heavier fragments contributed to faster sprouting, faster belowground shoot elongation and increased the proportion of remobilised biomass allocated to belowground shoots. Higher belowground shoot density increased the proportion of remobilised biomass allocated to belowground shoots but decreased individual elongation rate. In other words, larger reserves resulted in a better regeneration capacity and a higher number of growing belowground shoots increased the competition for reserves among them. The belowground shoot that sprouted first on a fragment grew faster and dominated the other shoots on the same fragment. Dominant belowground shoots were located toward the apical end of the fragment. These findings support the fact that tillage should aim at cutting storage organs into the smallest fragments possible to reduce regeneration capacity. This study also emphasised that belowground regrowth mechanisms are complex, and further studies should investigate other species with different types of storage organs. [ABSTRACT FROM AUTHOR]

Permeation barriers represent one of the crucial fields in materials development for thermonuclear fusion. Primary objective of the barriers is to suppress the permeation of hydrogen isotopes (mainly tritium) from future thermonuclear fusion facilities. Secondary objective is to reduce hydrogen retention in structural materials, potentially also improving their corrosion resistance. Expected reactor conditions put high demands on the material, as well as on the final barrier quality. Key properties are tritium permeation reduction, absence of defects (especially cracks), high-temperature stability and corrosion resistance, and compatibility with structural materials (mostly ferritic-martensitic steels). Regarding industrial scale production, ability of the deposition method to coat large complex surfaces is desirable. Thin nitride layers, identified as promising permeation barriers, were prepared by diffusion-based nitridation and physical vapour deposition (PVD) and characterized.

Tungsten is considered as the most suitable material for the plasma-facing armour of future fusion reactors. However, in spite of many advantageous properties, pure tungsten has a major drawback, namely, brittleness at lower temperatures and embrittlement by neutron irradiation. Tungsten fibre-reinforced tungsten (Wf/W) composites are thought to be a promising candidate material for armour owing to the pseudo-toughness effect which is based on controlled cracking of coated interfaces. In this material concept, the reliability of the material during service relies on the fabrication quality as well as the stability of microstructure, particularly, of the interfacial coating under high-heat-flux loads. In this paper, the durability and chemical stability of Wf/W composite specimens under cyclic heat-flux loads up to 20 MW/m² (surface temperature: 1260 °C) was investigated using hydrogen neutral beam. The bulk material was fabricated by means of spark-plasma-sintering (SPS) method using fine tungsten powder and a stack of tungsten wire meshes as reinforcement where the surface of the wire was coated with zirconia thin film to produce an engineered interface. The impact of plasma beam irradiation on microstructure was examined for two kinds of specimens produced at different sintering temperatures, 1400 °C and 1700 °C. Results of microscopic (SEM) and chemical (EDX) analysis are presented comparing the microstructure and element distribution maps obtained before and after heat flux loading. Effects of different sintering temperatures on damage behaviour are discussed. The present composite materials are shown to be applicable as plasma-facing material for high-heat-flux components.