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Lithium-ion batteries (LIBs) are widely used as important energy storage and energy supply devices. The porous design and heteroatomization modification of carbon-based anode materials are crucial for achieving high-capacity and reversible energy storage in LIBs. Sol-gel method and pyrolysis treatment were used to obtain silica/silver composite particles used as templates. Polyphosphazene-coated silica/silver composite composite carbon materials (SiO2/Ag@PZS-C) were synthesized through in-situ self-assembly and carbonization of polyphosphazene. The electrochemical behavior and lithium storage mechanism of SiO2/Ag@PZS-C was also studied. The results reveal that the composite exhibited high specific capacity, stable cycling and superior rate performance. The double modification of silver nanoparticles and polyphosphazene carbon significantly improves the conductivity of silica and reduces the volume change. Moreover, the carbon shell of polyphosphazene facilitated the formation of a stable solid electrolyte interface film (SEI), preventing direct contact between the active material and the electrolyte, thereby substantially enhancing lithium storage performance. [ABSTRACT FROM AUTHOR]

Single-atom cobalt (Co-N-C) catalyst has been proposed as a superior catalyst, but the symmetrical structure of Co-N4 shows unfavorable energetics, leading to much debate on its chemical nature responsible for its high activity. We found that the axial coordination between the well-defined Co-N4 site (pentafluorophenyl-porphyrin cobalt, CoTFP) and polarizable N-doped graphene (NG) can alter the spatial structure of Co-N4 site and lead to the transformation of Co(II) to monovalent Co(I) as the active center (defined as CoITFP@NG). Taking the electroreduction of nitrobenzene (NB) on the as-prepared catalyst as a model reaction, CoITFP@NG showed an increase of about three times the reaction kinetics and turnover frequencies (TOFs) compared with those of CoIITFP@OG, where CoTFP was immobilized on O-doped graphene (OG) via regular p-p stacking interactions. Augmented by density functional theory (DFT) calculations, axial bonds can serve as communication channels for electron transfer, deriving a decrease in the redox potential and then contributing to the catalytic reduction of NB. Intelligently prefabricating an axial coordination for Co-N4 sites represents an effective and feasible means for the rational ligand-field engineering of single-atom catalysts. [ABSTRACT FROM AUTHOR]

Segregation induced by size, shape, or density difference of the granular material is inevitable in both natural and industrial processes; unfortunately, the underlying mechanism is still not fully understood. In view of the ubiquitous continuous particle size distributions, this study builds on the considerable knowledge gained so far from binary-size mixtures and extends it to a ternary-size mixture to understand the impact of the presence of a third particle size in the three-dimensional rotating drum operating in the rolling flow regime. The discrete element method is employed. The evolution of segregation, the active-passive interface, and the dynamical response of the particle-scale characteristics of the different particle types in the two regions are investigated. The results reveal that the medium particles are spatially sandwiched in between the large and small particles in both the radial and axial directions and therefore exhibit behaviors intermediate to the other two particle types. Compared to the binary-size mixture, the presence of the medium particles leads to (i) higher purity of small particles in the innermost of the radial core, causing a decrease of the translational velocity of small particles; (ii) decrease and increase of the collision forces exerted on, respectively, the large and small particles in both regions; and (iii) increase in the relative ratio of the active-passive exchange rates of small to large particles. The results obtained in the current study therefore provide valuable insights regarding the size-segregation dynamics of granular mixtures with constituents of different sizes. [ABSTRACT FROM AUTHOR]

Granular materials are ubiquitous in our daily life and inherent in multitudinous industrial processes. Differences in the granular properties such as size and density inevitably induce segregation. By means of the discrete element method, a binary-size mixture in a three-dimensional rotating drum is numerically simulated to explore the segregation dynamics of the granular material along the axial direction. Snapshots of the distribution of the two particle types in the rotating drum are presented with respect to time to illustrate the spatial evolution of the size-induced segregation structure. The space-time plots of various axial characteristics indicate that (i) radial segregation does not affect the axial distribution of total mass and mass fraction, but axial segregation leads to the formation of axial bands; (ii) greater non-dimensionalized collision forces for both the large and small particles develop where the large particles dominate; and (iii) axial segregation gives rise to the variation of the gyration radii of both particle types along the drum length. In addition, axial flow of both particle types in both directions indicates the dynamic axial exchanges, and the effect of the end walls on the axial flow direction is limited to less than 25% of the drum length from the end walls. [ABSTRACT FROM AUTHOR]

The submerged membrane filtration concept is well-established for low-pressure microfiltration (MF) and ultrafiltration (UF) applications in the water industry, and has become a mainstream technology for surface-water treatment, pretreatment prior to reverse osmosis (RO), and membrane bioreactors (MBRs). Compared to submerged flat sheet (FS) membranes, submerged hollow fiber (HF) membranes are more common due to their advantages of higher packing density, the ability to induce movement by mechanisms such as bubbling, and the feasibility of backwashing. In view of the importance of submerged HF processes, this review aims to provide a comprehensive landscape of the current state-of-the-art systems, to serve as a guide for further improvements in submerged HF membranes and their applications. The topics covered include recent developments in submerged hollow fiber membrane systems, the challenges and developments in fouling-control methods, and treatment protocols for membrane permeability recovery. The highlighted research opportunities include optimizing the various means to manipulate the hydrodynamics for fouling mitigation, developing online monitoring devices, and extending the submerged HF concept beyond filtration. [ABSTRACT FROM AUTHOR]

The article details research on bubbling, gas-fluidized bed experiments that involve Geldart Group B particles. The study found that although monodisperse Geldart Group D particles cannot be completely fluidized, their presence allows all particles to be fluidized. The need for wide particle-size distributions (PSD's) to span more than one Geldart group is mentioned.

Because α-glycine grows 500 times faster than γ-glycine, the small thermodynamic preference for γ-glycine is difficult to predict, detect and exploit. [ABSTRACT FROM AUTHOR]