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The cycling mechanism of Li2MnO3 cathode materials synthesized by conventional solid-state methods at high temperatures (800-900 °C) has been intensively investigated. Previous studies showed that CO2 and O2 gas evolution accounts for most of the charge capacity, followed by some Mn reduction during discharge. In this work, we analyze the effects of ball milling on the structure, surface contaminant, and electrochemical capacity of Li2MnO3 cathode material, with or without a graphitic fluoride (C-F) additive. At the same time, C-F is added to form a protective coating layer that reduces unwanted reactions with the electrolyte during later electrochemical cycling. We find that the C-F ball-milled material shows Li2MnO3/LiMnO2 composite phases, while the purely ball-milled material shows a single Li2MnO3 phase. Furthermore, we characterize surface species and gas evolution during the first cycle, which reveals the decomposition of Li2CO3 and the carbonate electrolyte during the first charge, especially during the high potential region (>4.4 V), and the electrochemical reduction of only a small fraction of the evolved gas on the first discharge (

Establishing a simple molecular design and synthesis strategy for blue multi-resonance (MR) fluorescence emitters remains a crucial yet challenging task. Herein, we develop two MR blue emitters, namely OBN-1 and OBN-2, through fusing benzofuran fragments within B/N skeletons based on a one-shot borylation synthesis method. These MR blue emitters show new π-conjugated structures with alternate arrangements of HOMO–LUMO and extensive overlap distributions of HOMO–LUMO, and high oscillator strengths (f) as well as high photoluminescence quantum yields (PLQYs) up to 99.4% and 99.9% in toluene. Peripheral auxiliary aryl/heteroaryl amine substituents are introduced into MR emitters for reduction of intermolecular interactions. The electroluminescent devices utilizing OBN-1 and OBN-2 as fluorescent emitters show high external quantum efficiencies (EQEs) of 5.9% and 5.7% and blue emissions at 458 and 455 nm with CIE coordinates of (0.135, 0.155) and (0.139, 0.121). This work presents a one-pot synthesis method to construct a new type of MR core structure for the development of high-performance blue MR emitters. [ABSTRACT FROM AUTHOR]

Due to assembling, manufacturing errors, and wear, irregular rough surfaces inevitably exist in joints, which will increase the contact stiffness nonlinearity at the joint of the spatial developable mechanism, and the traditional contact force model is difficult to accurately predict the contact force change of irregular rough surface clearance. Aiming at the difficulty of accurately predicting the dynamic behavior of the spatial developable mechanism caused by rough joint clearance, an improved clearance contact force modeling method based on an uncoordinated contact model is proposed in this paper. The influence of rough peak distribution on the contact area is analyzed. The stiffness of the traditional Hertz model is modified based on the probability distribution density function of the rough peak, and an improved contact force model based on dynamic contact stiffness is established. Based on the Lagrange multiplier method, the dynamics model of spatial developable mechanism is constructed. Based on the model, the dynamic analysis of the spatial expansion mechanism is carried out, and the influence of the roughness of the contact surface and the size of the clearance on the dynamic characteristics of the system are explored; as well, the influence of different clearance parameters on the dynamic characteristics of the development mechanism is revealed. Through the analysis, this paper provides a theoretical basis for predicting the effect of a spatial revolute clearance joint on the dynamic characteristics of the mechanism and lays a good foundation for the manufacture and application of the mechanism. [ABSTRACT FROM AUTHOR]

The intrinsic activity assessment of transition metal oxides (TMOs) as key electrocatalysts for the oxygen evolution reaction (OER) has not been standardized due to uncertainties regarding their structure and composition, difficulties in accurately measuring their electrochemically active surface area (ECSA), and deficiencies in mass‐transfer (MT) rates in conventional measurements. To address these issues, we utilized an electrodeposition‐thermal annealing method to precisely synthesize single‐particle TMOs with well‐defined structure and composition. Concurrently, we engineered low roughness, spherical surfaces for individual particles, enabling precise measurement of their ECSA. Furthermore, by constructing a conductor‐core semiconductor‐shell structure, we evaluated the inherent OER activity of perovskite‐type semiconductor materials, broadening the scope beyond just conductive TMOs. Finally, using single‐particle nanoelectrode technique, we systematically measured individual TMO particles of various sizes for OER, overcoming MT limitations seen in conventional approaches. These improvements have led us to propose a precise and reliable approach to evaluating the intrinsic activity of TMOs, not only validating the accuracy of theoretical calculations but also revealing a strong correlation of OER activity on the melting point of TMOs. This discovery holds significant importance for future high‐throughput material research and applications, offering valuable insights in electrocatalysis. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a well-established and extensively studied photosensitizer for photodynamic therapy (PDT), since it can generate singlet oxygen with a high quantum yield upon irradiation within the phototherapeutic (600–950 nm) window. However, its activity can decrease due to the formation of dimers or higher aggregates, which can take place in an aqueous solution at relatively high concentrations. The incorporation of this molecule into a matrix can avoid this aggregation and increase its activity relative to PDT. Silica porous nanoparticles are chosen here as a matrix to host MB. The size and pore geometry are tuned in order to decrease MB leaching while maintaining good singlet oxygen generation and colloidal stability for further applications in nanomedicine. In addition, phenyl functions are grafted on the pores of the silica matrix in order to avoid MB aggregation, thereby increasing the activity of the photosensitizer in the singlet oxygen generation. DFT calculations give insight in the structure of the aggregation of the MB units, and the roles of water and organic environments are investigated through time-dependent calculations on UV-vis spectra. [ABSTRACT FROM AUTHOR]