Microwave ultra-high temperature (UHT) processing is promising for liquid food sterilization, yet its inactivation mechanisms against thermophilic bacteria remain inadequately understood. This study investigated the bactericidal efficacy and mechanisms of microwave UHT treatment against vegetative cells of Geobacillus stearothermophilus ATCC 7953. Using a single-mode microwave system at 2450 MHz, bacterial suspensions were subjected to various power-time combinations achieving 136 ± 1 °C followed by immediate cooling. A nonlinear relationship between power and inactivation efficacy was observed: optimal reductions of approximately 5 log CFU∙mL^–1 were achieved at 150 W∙mL^–1 for 40 s and 300 W∙mL^–1 for 20 s, while intermediate powers yielded inferior outcomes. Mechanistic analyses revealed that microwave treatment induced significant membrane damage, suppressed metabolic activity, and dramatically elevated intracellular reactive oxygen species and malondialdehyde levels, with the 300 W∙mL^–1 treatment generating the highest oxidative stress. Scanning electron microscopy confirmed distinct morphological alterations without electroporation. The similar trends observed between oxidative markers and bactericidal efficacy suggest that oxidative stress-mediated lipid peroxidation may constitute a primary inactivation mechanism, with low-power prolonged exposure promoting cumulative damage and high-power short-duration treatment triggering acute oxidative burst. These findings elucidate the power-time synergistic mechanism of microwave UHT inactivation and provide a theoretical foundation for process optimization.

Droplets exhibit distinct wetting characteristics and transport behavior on solid substrates at the macroscopic and microscopic scales. This behavior is critical for understanding liquid mass transfer on fibrous membranes. To better understand and control the mass transfer of liquids on fibrous membranes, we combined in situ visualization techniques with multiphase flow simulations. This approach enabled us to systematically explore the effects of various factors, including fiber wettability, fiber diameter, and fiber spacing, on liquid transfer behavior. Furthermore, we successfully elucidated the transfer mechanisms governing droplet transport on individual fibers and between adjacent fibers. Based on our findings, we constructed composite fiber membranes with varying fiber diameters and wettability structures. The validity of the proposed approach was verified by comparing fog collection, droplet wetting, and liquid permeation efficiency. Consequently, this study establishes a transferable cross-scale framework and proposes a general design strategy for constructing fibrous membranes tailored to diverse application requirements.

Converting CO₂ into CO via reverse water gas shift (RWGS) reaction is a key step for carbon recycling. Molybdenum trioxide (MoO₃) is a promising precatalyst due to its high activity and near-unity CO selectivity, yet the role of support properties remains unclear. To address this, a series of MoO₃-based catalysts supported on MgO, γ-Al₂O₃, SiO₂, TiO₂, ZrO₂, and CeO₂ were prepared. Systematic characterizations show that MoO₃ undergoes in situ carburization to Mo₂C, and the extent of carburization correlates positively with catalytic activity. The formation of active Mo₂C is governed by the metal oxide-support interaction (MOSI): strong MOSI between MoO₃ and basic supports (MgO, CeO₂) promotes stable solid solutions that suppress carburization, whereas acidic and amphoteric supports preserve MoO₃ crystallites, enabling efficient carburization and high RWGS performance. Among all catalysts, MoO_xC_y/SiO₂ exhibits the weakest MOSI, the highest surface Mo₂C concentration, and thus superior mass-specific activity. The ionic potential of the support serves as a descriptor for MOSI strength, while the specific surface area introduces a certain deviation for amphoteric supports (γ-Al₂O₃, TiO₂, ZrO₂). This work provides clear support selection criteria and a theoretical foundation for rational design of high-performance Mo-based RWGS catalysts.