Evolution of catalytic activity driven by structural fusion of icosahedral gold cluster cores

Atomically precise gold cluster catalysts have emerged as a new frontier in catalysis science,owing to their unexpected catalytic properties.In this work,we explore the evolution of the catalytic activity of clusters formed by the structural fusion of icosahedral Au13 units,namely Au25(SR)18,Au38(SR)24,and Au25(PPh3)10(SC2H4Ph)5Cl2,in the oxidation of pyrrolidine toγ-butyrolactam.We demonstrate that the structural fusion of icosahedral Au13 units,forming vertex-fused(vf),face-fused(ff),and body-fused(bf)clusters,can induce a decrease in the catalytic activity in the following order:Aubf>Auff>Auvf.The structural fusion of icosahedral Au13 units in the clusters does not distinguish the adsorption modes of pyrrolidine over the three clusters from each other,but modulates the chemical adsorption capacity and electronic properties of the three clusters,which is likely to be the key reason for the observed changes in catalytic reactivity.Our results are expected to be extendable to study and design atomically defined catalysts with elaborate structural patterns,in order to produce desired products.

Electromagnetic–thermal–structural coupling analysis of the ITER edge localized mode coil with flexible supports

In a fusion reactor, the edge localized mode（ELM） coil has a mitigating effect on the ELMs of the plasma. The coil is placed close to the plasma between the vacuum vessel and the blanket to reduce its design power and improve its mitigating ability. The coil works in a high-temperature,high-nuclear-heat and high-magnetic-field environment. Due to the existence of outer superconducting coils, the coil is subjected to an alternating electromagnetic force induced by its own alternating current and the outer magnetic field. The design goal for the ELM coil is to maintain its structural integrity in the multi-physical field. Taking as an example the middle ELM coil（with flexible supports） of ITER（the International Thermonuclear Fusion Reactor）, an electromagnetic–thermal–structural coupling analysis is carried out using ANSYS. The results show that the flexible supports help the three-layer casing meet the static and fatigue design requirements. The structural design of the middle ELM coil is reasonable and feasible. The work described in this paper provides the theoretical basis and method for ELM coil design.

Investigation of system structure and information processing mechanism for cognitive skywave over-the-horizon radar

Based on the cognitive radar concept and the basic connotation of cognitive skywave over-the-horizon radar（SWOTHR）, the system structure and information processingmechanism about cognitive SWOTHR are researched. Amongthem, the hybrid network system architecture which is thedistributed configuration combining with the centralized cognition and its soft/hardware framework with the sense-detectionintegration are proposed, and the information processing framebased on the lens principle and its information processing flowwith receive-transmit joint adaption are designed, which buildand parse the work law for cognition and its self feedback adjustment with the lens focus model and five stages informationprocessing sequence. After that, the system simulation andthe performance analysis and comparison are provided, whichinitially proves the rationality and advantages of the proposedideas. Finally, four important development ideas of futureSWOTHR toward ＂high frequency intelligence information processing system＂ are discussed, which are scene information fusion, dynamic reconfigurable system, hierarchical and modulardesign, and sustainable development. Then the conclusion thatthe cognitive SWOTHR can cause the performance improvement is gotten.

Recrystallization Behavior of the New Ni-Co-Based Superalloy with Fusion Structure Produced by Electron Beam Smelting Layered Solidification Technology

The new Ni-Co-based superalloy featuring a"fusion structure"was produced utilizing electron beam smelting layered solidification technology(EBSL).Experimental examination of hot compression deformation with varied settings for EBSL and conventional duplex process melting Ni-Co superalloys was performed.As per the study,EBSL-Ni-Co superalloys exhibited enhanced recrystallization susceptibility during hot deformation.Furthermore,elevating deformation temperature,lowering strain rate,and augmenting strain collectively contribute to enlarging the volume fraction of dynamically recrystallized grains.Aberrant growth of grains occurred when the deformation temperature equaledγ′sub-solvus temperature and the strain rate was slower.Moreover,exceeding theγ′solvus temperature during deformation significantly increases the particle size of dynamic recrystallization(DRX)grains.Theγ′phase can effectively modulate the DRX grain size through the pegging effect.Additionally,it was revealed that the presence of the fusion structure aids in the generation of continuous dynamic recrystallization,discontinuous dynamic recrystallization,and twinning-induced dynamic recrystallization while the alloy undergoes hot deformation.This mechanism promotes DRX granule formation and permits complete recrystallization.Ultimately,the fusion structure was identified as playing a catalytic role in the dynamic recrystallization process of the new Ni-Co superalloy.