The granule-based anammox process is a promising biotechnology for nitrogen removal; however, it is challenging to achieve a high rate and efficiency simultaneously. In this study, we addressed this challenge by coupling two granule types with complementary kinetics in an anammox sludge bed reactor. Bright red granules (GR) exhibited higher maximum specific anammox activity (SAA) but lower substrate affinity; they predominantly occupied the reactor's lower section, where substrate concentrations are high, forming a high-capacity layer. Yellow-brown granules (GY) showed higher substrate affinity but lower maximum SAA; they mainly populated the upper low-substrate zone, forming an efficient substrate-scavenging layer. This self-organized granule stratification enabled both a high nitrogen removal rate (14.5 kg-N/(m3·d)) and high efficiency (90.2%). Physicochemical property and microbial community analyses of granules showed that the stratification of "affinity" was mainly governed by the granular structure and mass transfer rather than intrinsic microbial traits. By actively withdrawing excessive sludge from the fast-growing lower zone while preserving biomass in the upper zone, such stratification can be stably maintained. Collectively, these findings advance our understanding of granule heterogeneity in anammox sludge bed bioreactors and offer a practical strategy for performance optimization.

Water pollution remains a serious global challenge; hence, the efficient, low-cost, and environmentally friendly removal of pollutants from water has become a research hotspot. Photocatalytic microrobots can achieve autonomous movement and generate reactive oxygen species (ROS), presenting a great opportunity for water purification. Despite the excellent properties of g-C3N4, such as high photocatalytic activity, high surface area, tunable bandgap, and low cost, only a few studies have focused on g-C3N4-based microrobots. Herein, we developed g-C3N4/Ag Janus microrobots that display negative photogravitaxis and efficient photocatalytic activity. Silver modification promotes the generation and separation of charge carriers while suppressing their recombination, enabling the microrobots to move upward. This three-dimensional movement enhances mass transfer between pollutants and microrobots. We utilized the microrobots to degrade tetracycline with an efficiency of 88%, which is attributed to ROS generation and light-driven propulsion. This work not only demonstrates negative photogravitaxis in g-C3N4/Ag-based microrobots but also reveals their motion-enhanced photocatalytic mechanism for antibiotic degradation. These findings are expected to significantly advance the development of microrobotic systems for water purification and broader environmental remediation applications.

The growing contamination of water resources with persistent dyes and pharmaceuticals necessitates the development of rapid and energy‐efficient remediation technologies. We present a microfluidic purification reactor that synergistically integrates piezophotocatalysis with flow‐engineered microstructures to enable rapid pollutant degradation. The microreactor, fabricated from polymethyl methacrylate (PMMA) via laser micromachining, was optimized with strategically positioned micropillars to induce turbulence and enhance mass transfer, with COMSOL Multiphysics simulations validating flow behavior and vorticity patterns. Catalytic functionality was introduced through an electrospun polyvinylidene fluoride (PVDF) nanofiber membrane embedded with MoS2 and WS2 nanoparticles forming an active piezophotocatalytic interface within the reactor bed. Structural, compositional, and functional characterizations identified PM15 (15 wt% MoS2) and PW20 (20 wt% WS2) as optimal nanocomposites, with their electromechanical response validated by a piezoelectric nanogenerator generating ≥36 V. Under optimized operating conditions, flow rate of 50 µL/min, visible‐light irradiation, and ultrasonic excitation at 60 kHz, the integrated system achieved rapid degradation efficiencies of ≥94% for RhB and ≥90% for CIP within 252 s, outperforming conventional methods. A multiple linear regression model accurately predicted degradation efficiencies from key operational parameters, demonstrating the utility of data‐driven process optimization. Overall, the integrated microfluidic–piezophotocatalyst platform establishes a rapid, high‐throughput, and energy‐efficient approach for advanced water purification.

Abstract The stability of binary mass transfer is a critical problem for binary evolution. We systematically calculate the adiabatic mass-loss model for naked helium stars with masses ranging from 10 M ⊙ to 80 M ⊙ to study the critical mass ratio ( q crit ) of Wolf–Rayet binaries. We set up two prescriptions about Wolf–Rayet stellar wind and consider the isotropic reemission effect during adiabatic mass loss. Results of the critical mass ratio for conserved dynamically unstable mass transfer show that most of the no-wind helium stars in the main sequence (HeMS) have 0.7 < q crit < 3.0 and helium stars on the Hertzsprung gap (HeHG) have 1.5 < q crit < 27. With the Wolf–Rayet star wind effect, the q crit gets lower on a certain evolutionary stage. With the isotropic reemission effect, the q crit gets larger for early evolutionary stage helium stars and lower for late-evolutionary stage helium stars. Based on fully nonconserved mass transfer, the criteria for HeMS stars are 1.0 < q crit < 2.8 and HeHG stars are 1.5 < q crit < 5.0. Compared with the widely used criterion q crit = 3 (HeMS) and q crit = 4 (HeHG), our result becomes more unstable for the HeMS stars and more stable for the HeHG stars. Our work could be applied to the binary mass-transfer stage of massive helium binaries, such as Wolf–Rayet star binaries and high-mass X-ray binaries with Wolf–Rayet star companions. It can be applied to the binary population synthesis studies for the formation of special objects, such as double black hole mergers.

Microfluidic technologies have emerged as powerful tools in pharmaceutical sciences, offering precise control over fluid handling, mixing, and mass transfer at the microscale. These unique characteristics have enabled significant advances in controlled pharmaceutical formulation and drug screening, addressing key limitations of conventional bulk-scale methods, such as poor reproducibility, high material consumption, and limited physiological relevance. This review provides a comprehensive overview of recent progress in microfluidics for pharmaceutical applications, with a focus on formulation control, nanocarrier and advanced drug delivery system fabrication, controlled release, and stability enhancement. The role of microfluidic platforms in high-throughput and physiologically relevant drug screening, including cell-based and organon-chip models, is critically discussed. Furthermore, the integration of microfluidics with emerging technologies such as automation, artificial intelligence, digital microfluidics, and advanced analytical tools is highlighted as a driver of datadriven and continuous pharmaceutical development. Key challenges related to scalability, standardization, regulatory acceptance, and ethical considerations are also examined. Finally, future perspectives emphasize the growing translational potential of microfluidics in continuous manufacturing, personalized medicine, and precision therapeutics. Overall, this review underscores the transformative impact of microfluidic technologies on modern pharmaceutical formulation and drug screening, positioning them as integral components of next-generation drug development pipelines.

Evidence for the shallow cycling of calcium carbonate in the global ocean is mounting, but the mechanisms driving the dissolution of thermodynamically stable polymorphs, like aragonite and calcite, in the surface ocean remain unconstrained. Here, we quantify how microbial metabolism creates acidic microenvironments in marine particles that enhance the local dissolution of calcite despite supersaturated conditions in bulk waters. A temporal decoupling of particle deoxygenation and acidification suggests that respiration-derived carbon dioxide is not the sole driver of the observed undersaturation. Rapid dissolution occurs in particles exhibiting bacterial growth, with rates exceeding abiotic dissolution at the same bulk saturation by more than an order of magnitude. We observe the highest particle-associated dissolution rates at intermediate settling velocities, indicating that a trade-off between elevated mass transfer due to settling and bacterial respiration governs the ensuing dissolution rates. Translation of our experiments to the water column suggests that microbially driven undersaturation in marine particles may dissolve sufficient calcite in the mesopelagic ocean to extend particle transit times by eliminating this vital ballast mineral, reducing the efficiency of organic carbon sequestration.

Conventional hydrochloric acid (HCl) acidizing in carbonate reservoirs is often limited by excessively rapid acid–rock reactions and preferential flow through high-permeability paths, resulting in shallow penetration and inefficient stimulation. Viscoelastic surfactant (VES)-based diverting acids have been widely applied to address these challenges; however, the intrinsic relationship between reaction retardation and diversion efficiency, particularly under varying shear conditions, remains insufficiently clarified. In this study, a VES-based diverting acid system formulated with erucamidopropyl hydroxysultaine (EH50) was systematically investigated through multiscale experiments, including rotating disk reaction kinetics, rheological characterization, porous core flooding, and fracture-scale plate flow tests. The results reveal a pronounced shear-dependent transition in the governing mechanism of the system. Under low-shear conditions, the VES system significantly reduces the apparent acid–rock reaction rate, with a maximum reduction of 77.3%, and exhibits a synergistic retardation effect in the presence of Ca2+, indicating mass transfer limitation. However, under high-shear porous media flow, the intrinsic retarding effect is substantially weakened due to partial disruption of the viscoelastic structure. Despite this attenuation of chemical retardation, effective diversion performance persists under dynamic flow conditions, manifested by pressure plateau behavior, enhanced flow redistribution, more distributed wormhole networks, and greater overall dissolution. Fracture-scale experiments further demonstrate that the diversion acid suppresses excessive inlet etching and promotes spatially distributed etching patterns favorable for fracture conductivity maintenance. These findings clarify that reaction retardation and diversion are distinct yet dynamically coupled mechanisms, whose relative dominance depends on shear intensity and ionic environment. The proposed shear-responsive mechanism framework provides new insight into the design and optimization of VES diverting acid systems for carbonate reservoir stimulation.

ABSTRACT Deep eutectic solvents (DES) are efficient for separating cathode materials and current collectors from spent lithium‐ion batteries due to their high solubility and tunable properties. However, they suffer from slow reaction kinetics (>30 min) and high‐temperature requirement (>120°C). Herein, a dual‐function DES composed of diethyl (hydroxymethyl) phosphonate (DHP) and malonic acid (MA) with low temperature and faster kinetics was designed. The nucleophilic groups (─OH and alkoxy) on DHP and MA created extensive negative electrostatic potential regions, facilitating the degradation of polyvinylidene fluoride (PVDF) binder at low temperatures. Concurrently, the formed hydrogen‐bonding network weakened intermolecular interactions, reducing viscosity and enhancing mass transfer. For LiCoO 2 , a separation efficiency of >99% was achieved within 15 min at 60°C. Separation mechanism confirmed that PVDF degradation was triggered by the reaction of DHP–MA molecules with H‐atoms, forming solvent channels. Furthermore, with the penetration of H + and MA towards channels, the activation of the corrosion‐passivation reaction brought about the accelerated cathode material detachment. The separated material exhibited low impurity content (<0.026 wt%), minimal metal loss (<2 wt%), and a well‐preserved crystal structure, conducing to the repair of high‐performance materials. Similar results were achieved for LiFePO 4 and LiNi 0.3 Co 0.3 Mn 0.3 O 2 , offering a universal strategy for high‐quality cathode materials recycling.

In this work, we present the scale-up of a batch anaerobic fermentation system for the production of succinic acid from glycerol using A. succinogenes. The system has been successfully scaled up from an initial bioreactor working volume of 1 L (laboratory scale) to a working volume of 100 L (pilot scale). At the same time, we have developed a hybrid model, combining the intrinsic kinetics of the microbial growth, with a computational fluid dynamics model (CFD) of the bioreactor. The proposed model is able to predict the productivity drop, usually observed while scaling up a bioprocess. In our process, this is a result of the limitations on the mass transfer of CO2 between the gas and the liquid phase of the system. The model is successfully used to predict the amount of aeration needed in order to achieve increased succinic acid productivity. Using the model, the final succinic acid increased by 4.3%, and the succinic acid productivity increased by 8.5%, while the fermentation by-products decreased by approxiamtely 3% each.

Antibiotic resistance (AMR) is a global health crisis responsible for over five million deaths annually. Rapid antimicrobial susceptibility testing (RAST) is critical for timely clinical decision-making. This study develops a hydrogel-based 3D culture microfluidic platform enclosed within a PMMA box, enabling safe and rapid testing of highly pathogenic bacteria. The microfluidic chip employs a Christmas tree concentration gradient generator, capable of simultaneously delivering four distinct drug concentrations. Theoretical, finite-element method, and experimental analyses demonstrated precise gradient control by tuning inlet flow-rate ratios (Q1/Q0), concentration ratios (C0/C1), and absolute concentrations (C0). Optimizing hydrogel porosity (90%) and chamber height (200 μm) enhanced mass transfer, improving bacterial growth and drug delivery. Using Escherichia coli ATCC 25922 as a model, the system determined the minimum inhibitory concentration (MIC, 2 μg/mL) of gentamicin within 2 h─8 to 10-fold faster than standard methods, while matching conventional AST accuracy. From a fluid dynamics perspective, this work optimized the flow and mass transfer processes in AST, thereby enhancing the contact between nutrients, drugs, and bacteria. This hydrogel-based 3D microfluidic system provides a safe, efficient, and scalable RAST platform with strong potential for clinical applications against highly pathogenic and drug-resistant bacteria.

Enhancing the heat and mass transfer performance of working fluids remains a critical challenge to pursue sustainable and energy-efficient technologies. Although regular working fluids have superior thermo-physical properties to pure base fluids, they often face limitations that hinder their adoption in multifunctional applications. To overcome these challenges, this study develops a novel, comprehensive and physically consistent mathematical model for an unsteady, electrically conducting ternary hybrid nanofluid composed of graphene oxide (GO), cerium oxide (CeO[Formula: see text], and hexagonal boron nitride ([Formula: see text]-BN) suspended in an environmentally friendly ionic liquid (Ethyl-3-methylimidazolium tetrafluoroborate) [EMIM][BF 4 ]. The model integrates magnetic effects, radiation heat transfer, viscous dissipation, Joule heating, and coupled thermo-diffusion effects. A fractal–fractional derivative operator is employed to generalize the governing equations, while the local radial basis functions (RBF) scheme is used to solve them numerically. Computational and graphical results reveal that CeO 2 suppresses the fluid velocity due to increased inertial resistance, while the dispersion of [Formula: see text]-BN significantly enhanced the thermal profile, resulting in a higher Nusselt number. Furthermore, higher values of Dufour and Soret numbers enhance the coupled heat and mass transfer rates, indicating the model’s potential to design advanced heat exchangers and smart cooling devices. These findings provide valuable guidelines for designing compact heat exchangers and thermal energy storage systems for applications in renewable energy and microelectronics cooling.

Integrated UiO-66-bacterial composite for methylene blue removal: Mechanistic insights and detoxification.

Enhanced removal of Pb (II) and sulfate by immobilizing acid-tolerant sulfate-reducing bacteria on magnetic chitosan.

Fructus aurantii, a genuine traditional Chinese medicinal material, undergoes drying as a critical step to ensure the quality of its post-harvest processing at the origin. However, a major challenge in this process are the uneven drying rates between the surface and interior, which often leads to quality defects such as dry and wet spots. In severe cases, it can even cause localized mold growth, significantly compromising the processing quality and market value of the product. To address this issue, this study systematically characterized the microstructure of Fructus aurantii using CT scanning technology, developed a more realistic microstructure model, and accurately obtained key physical parameters including pore structure properties. Based on this microstructure characterization, a transient heat and mass transfer model for the drying process of Fructus aurantii was established and solved numerically. Model validation experiments were performed under drying condition at 55 °C, and the results showed that the maximum deviation between the simulated and experimental moisture ratio values was only 9.2%, confirming the model’s reliability. Using this basis, the dynamic evolution of internal temperature distribution, moisture content distribution, and water vapor partial pressure gradient during drying were thoroughly analyzed. It was found that the low-porosity structure of the Fructus aurantii surface significantly hinders moisture diffusion. Moisture accumulates at the interface between the surface and the fiber layer, leading to the formation of wet spots. Conversely, in the non-aggregated regions between the surface and internal fibers, dry spots tend to form due to restricted moisture diffusion combined with a high evaporation rate. This study systematically reveals the core mechanism of internal moisture migration during the drying of Fructus aurantii, providing important theoretical support for the optimal design of mold-prevention and quality-enhancement drying processes, as well as related engineering innovations for this medicinal material.

Noble-metal-free electrocatalysts are inexpensive and exhibit low onset potential, adequate stability, and excellent conductivity, making them highly attractive for advancing direct formic acid fuel cells. In this study, we modulated the surface electronic structure of copper aerogel by incorporating an ultra-low amount of nickel, resulting in the formation of a Cu98Ni2 aerogel catalyst. The compositional, morphological, structural, and electrochemical properties of the as-prepared electrocatalyst were extensively studied using XPS, TEM, SEM/EDX, SEM, XRD, ICP-OES, and CV techniques. The Cu98Ni2 aerogel exhibits mass activity values that are 13.3, 2.8, and 4.5 times higher than those of undoped Cu, Cu95Ni5, and Cu92Ni8 aerogels, respectively, along with onset potentials that are negatively shifted by 45, 25, and 12 mV. Notably, the Cu98Ni2 aerogel maintains about 82% of its initial steady-state current density after 10 hours of formic acid oxidation, indicating a significant improvement in catalyst performance. Furthermore, Cu98Ni2 attains the smallest Tafel slope (81.5 mV dec-1) and apparent activation energy (23.8 kJ mol-1), suggesting faster and easier charge transfer kinetics for formic acid oxidation compared to undoped Cu and Cu aerogels with higher Ni loading. The outstanding performance of the electrocatalyst in formic acid oxidation is mainly attributed to superior conductivity, effective mass and electron transfer, minimal CO poisoning, and the synergistic effects of its constituents. This study promotes the production of highly stable and efficient electrocatalysts made from non-precious metals.

Mechanism of corrosion, scaling and failure of valves in drinking water distribution systems.

Gas-phase oxidation of volatile organic compounds (VOCs) with the aid of ozone can be an attractive, energy-efficient way of treating exhaust gas streams in a low-temperature process, enabling the sustainable operation of industrial installations in a natural environment. This work is focused on the efficiency and kinetics of toluene oxidation with ozone towards CO2 and H2O in the presence of a SiO2-supported cobalt catalyst. A kinetic model is proposed based on a simplified reaction mechanism, with the parameters determined from measurements carried out in a fixed-bed reactor at 40–65 °C under conditions ensuring negligible mass transfer resistance. The proposed model provided satisfactory agreement between the predicted and measured toluene and ozone conversion rates and the formation rate of CO2, as well as in conditions when mass transfer resistance due to internal diffusion in the catalyst pellet was necessary to consider. The discussed results provide an assessment of the space velocity and ozone usage necessary to achieve a given degree of toluene conversion and mineralization to CO2. The proposed model can be used for the design of a sustainable, low-temperature ozone-assisted catalytic process of VOC abatement.

High-entropy alloys (HEAs) exhibit excellent catalytic activity owing to their unique structure and chemical properties. The construction of hierarchical porous HEA catalysts via laser powder bed fusion (LPBF, a typical 3D printing technology) and dealloying techniques opens new avenues for boosting catalytic performance. This study reports the fabrication of a hierarchical porous FeCoNiCuAl HEA catalyst through a two-step strategy: LPBF and subsequent dealloying. The macroscopic triply periodic minimal surface (TPMS) structure of the HEA catalyst was constructed through LPBF, followed by dealloying to create a nanoporous structure on the catalyst surface. The hierarchical porous FeCoNiCuAl HEA catalyst exhibited a catalytic activity 4.33 times higher than that of the pristine, non-porous FeCoNiCuAl HEA (HEA-0). Furthermore, the catalyst maintained nearly 100% degradation efficiency for Acid Red G (ARG) after 20 consecutive catalytic cycles, demonstrating exceptional stability. This stepwise strategy for constructing hierarchical porous structures not only accelerates mass transfer via the macroporous framework but also significantly increases the density of accessible active sites through the nanoporous surface, thereby synergistically enhancing the catalytic activity of HEAs. This work provides a novel and scalable approach for developing high-performance porous HEA catalysts for wastewater treatment.

An analytical and numerical investigation of Rayleigh-Taylor instability has been carried out within a planner configuration under the influence of a vertically imposed magnetic field, through viscous potential flow theory. The instability is examined for the configuration in which a Walter's B viscoelastic fluid overlies a Newtonian viscous fluid embedded in a porous medium, with simultaneous heat and mass transfer permitted across the interface. The dispersion relation between perturbation growth rate and wave number is established via normal mode analysis. This relation is investigated using the Newton-Raphson method, which facilitates the identification of the influence of various non-dimensional physical parameters, determining whether they suppress or amplify the perturbation growth. The study reveals that a vertically oriented magnetic field and an increased porosity of the medium enhance the amplification of perturbations, while an increased thermal flux across the interface counteracts this tendency, thereby diminishing the growth of instability.

Methane hydrate formation in multiphase transportation pipelines represents a critical challenge to flow assurance under low-temperature conditions. Gaining insight into the kinetic effects of crude oil on hydrate formation aids in developing countermeasures for mixed oil–gas transportation. For this purpose, experiments were carried out at 50 vol% to 90 vol% water cut and pressure of 6.0–7.5 MPa under crude oil–methane–water systems. Results demonstrate that crude oil has kinetic inhibition on hydrate formation, which is caused by mass transfer resistance in emulsion gels. The gas consumption increased by 81.38% when the water cut increased from 60 vol% to 70 vol%. Tween-80 converts crude oil W/O emulsions into O/W emulsions. The addition of Tween-80 to a 50 vol% water cut system resulted in only a 10.04% increase in gas consumption compared to the 90% water cut condition. The results indicate that Tween-80 significantly promotes the formation of hydrates. Furthermore, analysis of gas consumption reveals that the O/W system is more conducive to hydrate growth than the W/O system. Observations through the viewing window revealed that lowering the temperature and hydrates synergistically disrupt the stability of the emulsion. This is caused by the phase transition of wax and asphaltene in crude oil. These findings provide insights for developing flow assurance strategies in crude oil multiphase transportation pipeline operations.