Promoting H2O2 production via 2-electron oxygen reduction by coordinating partially oxidized Pd with defect carbon.

Electrochemical synthesis of H2O2 through a selective two-electron (2e-) oxygen reduction reaction (ORR) is an attractive alternative to the industrial anthraquinone oxidation method, as it allows decentralized H2O2 production. Herein, we report that the synergistic interaction between partially oxidized palladium (Pdδ+) and oxygen-functionalized carbon can promote 2e- ORR in acidic electrolytes. An electrocatalyst synthesized by solution deposition of amorphous Pdδ+ clusters (Pd3δ+ and Pd4δ+) onto mildly oxidized carbon nanotubes (Pdδ+-OCNT) shows nearly 100% selectivity toward H2O2 and a positive shift of ORR onset potential by ~320 mV compared with the OCNT substrate. A high mass activity (1.946 A mg-1 at 0.45 V) of Pdδ+-OCNT is achieved. Extended X-ray absorption fine structure characterization and density functional theory calculations suggest that the interaction between Pd clusters and the nearby oxygen-containing functional groups is key for the high selectivity and activity for 2e- ORR

Fine structures of radio bursts from flare star AD Leo with FAST observations

Radio bursts from nearby active M-dwarfs have been frequently reported and extensively studied in solar or planetary paradigms. Whereas, their sub-structures or fine structures remain rarely explored despite their potential significance in diagnosing the plasma and magnetic field properties of the star. Such studies in the past have been limited by the sensitivity of radio telescopes. Here we report the inspiring results from the high time-resolution observations of a known flare star AD Leo with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We detected many radio bursts in the two days of observations with fine structures in the form of numerous millisecond-scale sub-bursts. Sub-bursts on the first day display stripe-like shapes with nearly uniform frequency drift rates, which are possibly stellar analogs to Jovian S-bursts. Sub-bursts on the second day, however, reveal a different blob-like shape with random occurrence patterns and are akin to solar radio spikes. The new observational results suggest that the intense emission from AD Leo is driven by electron cyclotron maser instability which may be related to stellar flares or interactions with a planetary companion.Comment: 25 pages, 12 figures, accepted for publication in Ap

Numerical Simulation of Combustion Chamber for Button Turbojet Engine

To provide reference data for ultra-micro combustor, a new type button turbojet engine was designed and simulated the combustion’s steady-state process. The boundary condition of inlet was calculated using isentropic numerical calculation, taken into turbulent chemical reaction, heat radiation, and so on, getting the combustion chamber’s steady-state of the velocity, temperature and component concentration distribution, analysis the fuel/air flow and backflow, combustion efficiency and total pressure recovery coefficient, and compared with the experimental data. The calculation results can accurately reflect the actual combustion. The results show that combustion chamber exit velocity is about 65m/s, outlet temperature is around 1000K, the simulation and experimental data are similar, combustion chamber structure design is reasonable, and this paper will provide a basis for the future improvement of the millimeter scale turbojet engine

Numerical Simulation of Combustion Chamber for Button Turbojet Engine

To provide reference data for ultra-micro combustor, a new type button turbojet engine was designed and simulated the combustion’s steady-state process. The boundary condition of inlet was calculated using isentropic numerical calculation, taken into turbulent chemical reaction, heat radiation, and so on, getting the combustion chamber’s steady-state of the velocity, temperature and component concentration distribution, analysis the fuel/air flow and backflow, combustion efficiency and total pressure recovery coefficient, and compared with the experimental data. The calculation results can accurately reflect the actual combustion. The results show that combustion chamber exit velocity is about 65m/s, outlet temperature is around 1000K, the simulation and experimental data are similar, combustion chamber structure design is reasonable, and this paper will provide a basis for the future improvement of the millimeter scale turbojet engine

Modelling Context Effects in Exit Choice for Building Evacuations

Understanding exit choice behaviour is essential for optimising safety management strategies in building evacuations. Previous research focused on contextual attributes, such as spatial information, influencing exit choice, often using utility models based on monotonic functions of attributes. However, during emergencies, evacuees typically make rapid, less calculated decisions. The choice of context can significantly impact the evaluation of attributes, leading to preference reversals within the same choice set but under varying context conditions. This cognitive psychological phenomenon, known as context effects, encompasses the compromise effect, the similarity effect, and the attraction effect. While researchers have long recognised the pivotal role of context effects in human decision making, their incorporation into computer-aided evacuation management remains limited. To address this gap, we introduce context effects (CE) in a social force (SF) model, CE-SF. Evaluating CE-SF’s performance against the UF-SF model, which considers only the utility function (UF), we find that CE-SF better replicates exit choice behaviour across urgency levels, highlighting its potential to enhance evacuation strategies. Notably, our study identifies three distinct context effects during evacuations, emphasising their importance in advancing safety measures

Current Challenges in Efficient Lithium-Ion Batteries’ Recycling: A Perspective

Li-ion battery (LIB) recycling has become an urgent need with rapid prospering of the electric vehicle (EV) industry, which has caused a shortage of material resources and led to an increasing amount of retired batteries. However, the global LIB recycling effort is hampered by various factors such as insufficient logistics, regulation, and technology readiness. Here, the challenges associated with LIB recycling and their possible solutions are summarized. Different aspects such as recycling/upcycling techniques, worldwide government policies, and the economic and environmental impacts are discussed, along with some practical suggestions to overcome these challenges for a promising circular economy for LIB materials. Some potential strategies are proposed to convert such challenges into opportunities to maintain the global expansion of the EV and other LIB-dependent industries

Experimental Investigation of Triboelectrification Behaviour in the Friction Process

The triboelectrification phenomenon can occur during the friction process of metal contact pairs. An in-depth understanding of triboelectrification behaviour is incredibly beneficial to controlling friction and wear. However, due to the complexity of the driving mechanism, it is still challenging to gain a thorough understanding of the triboelectrification behaviour of metal–metal contact pairs. To further reveal the triboelectrification behaviour during the friction process of metal pairs, wear experiments of GCr15 steel–cast iron were carried out on a CFT-I tribometer under oil-free and oil lubrication conditions. The triboelectric current signal was collected during the investigation, and its variation was discussed. The result shows that the varying trend of the triboelectric current was consistent with that of the friction coefficient in the friction process. The triboelectrification of similar metal contact pairs primarily driven by material transfer was closely related to friction and wear conditions

Current Challenges in Efficient Lithium‐Ion Batteries’ Recycling: A Perspective

Li-ion battery (LIB) recycling has become an urgent need with rapid prospering of the electric vehicle (EV) industry, which has caused a shortage of material resources and led to an increasing amount of retired batteries. However, the global LIB recycling effort is hampered by various factors such as insufficient logistics, regulation, and technology readiness. Here, the challenges associated with LIB recycling and their possible solutions are summarized. Different aspects such as recycling/upcycling techniques, worldwide government policies, and the economic and environmental impacts are discussed, along with some practical suggestions to overcome these challenges for a promising circular economy for LIB materials. Some potential strategies are proposed to convert such challenges into opportunities to maintain the global expansion of the EV and other LIB-dependent industries