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The kinetics of mass transfer in a stagnant fluid layer next to an interface govern numerous dynamic reactions in diffusional micro/nanopores, such as catalysis, fuel cells, and chemical separation. However, the effect of the interplay between stagnant liquid and flowing fluid on the micro/nanoscopic mass transfer dynamics remains poorly understood. Here, by using liquid cell transmission electron microscopy (TEM), we directly tracked microfluid unit migration at the nanoscale. By tracking the trajectories, an unexpected mass transfer phenomenon in which fluid units in the stagnant liquid layer migrated two orders faster during gas-liquid interface updating was identified. Molecular dynamics (MD) simulations indicated that the chemical potential difference between nanoscale liquid layers led to convective flow, which greatly enhanced mass transfer on the surface. Our study opens up a pathway toward research on mass transfer in the surface liquid layers at high spatial and temporal resolutions.

Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min–1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d32) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d32 of 25–63 μm at a liquid flow rate of 1025 L·h–1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d32, and the predicted d32 was in good agreement with the experimental data with a deviation within ±15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

Nonlinear finite element analysis is widely used for structural optimization of the design and the reliability analysis of complex elastomeric components. However, high-precision numerical results cannot be achieved without reliable strain energy functions (SEFs) of the rubber or rubber nanocomposite material. Although hyperelastic constitutive models have been studied for nearly 80 years, selecting one that accurately describes rubber's mechanical response is still a challenge. This work reviews 85 isotropic SEFs based on both the phenomenological theory and the micromechanical network theory proposed from the 1940s to 2019. A fitting algorithm which can realize the automatic fitting optimization and determination of the parameters of all SEFs reviewed is developed. The ability of each SEF to reproduce the experimental data of both the unfilled and highly filled rubber nanocomposite is quantitatively assessed based on a new proposed evaluation index. The top 30 SEFs for the unfilled rubber and the top 14 SEFs for the highly filled rubber nanocomposite are presented in the ranking lists. Finally, some suggestions on how to select an appropriate hyperelastic constitutive model are given, and the perspective on the future progress of constitutive models is summarized.

Poly (ethylene glycol)-poly (n-butyl cyanoacrylate) (PEG-PBCA) is a remarkable drug delivery carrier for permeating blood-brain barrier. In this work, a novel high-gravity procedure was reported to intensify Knoevenagel condensation-Michael addition polymerization of PEG-PBCA. A series of PEG-PBCA containing different block ratios were synthesized with narrow molecular weight distribution of polydispersity indexes less than 1.1. Furthermore, the reaction time reduced 60% compared to conventional stirred tank reactor process. Chemical structures of as-prepared polymers were characterized. In vitro drug delivery performance was evaluated. The cytotoxicity of PEG-PBCA to brain microvessel endothelial cells (BMVEC) decreases with the extension of the PEG chain and the shortening of the PBCA chain. The polymer cellular uptake to BMVECs was better after improving hydrophilicity by PEG block. Results of blood-brain barrier permeability demonstrated that medium length of PBCA chain and short PEG chain are favorable for hydrophobic Nile red permeation, while long PEG chain and short PBCA chain are beneficial to delivery water-soluble doxorubicin hydrochloride (Dox). The average apparent permeability coefficient increased 1.7 and 0.25 times than that of raw Nile red and Dox, respectively. High-gravity intensified condensation polymerization should have great potential in brain drug delivery system.

Graphitic carbon nitride (g-C3N4) with transition metal phosphides has been studied extensively as potential photocatalysts for hydrogen evolution. However, in-situ approaches to realize intimate interfacial contacts have rarely been reported. In this study, Ni2P nanoparticles-decorated g-C3N4 photocatalysts were prepared via liquid exfoliation of g-C3N4 followed by in-situ loading of Ni2P nanoparticles in a rotating packed bed (RPB) reactor. The optimized Ni2P/g-C3N4 exhibits high performance in visible-light-driven (λ > 420 nm) hydrogen evolution (∼561 μmol g−1 h−1), which is 103 times higher than that of pristine g-C3N4. The superior photocatalytic performance and durability originate from the robust interfacial structure. Therefore, a Z-scheme route with enhanced transfer of photoinduced electron was proposed, and Ni2P/g-C3N4 composites with smaller bandgaps than those of g-C3N4 were realized. Due to the intensified mass transfer and mixing of RPB reactor, the adsorption and nucleation processes of Ni2P on g-C3N4 were enhanced, enabling scalable solar light-driven H2 production.

The coronavirus disease 2019 (COVID-19) pandemic has caused a surge in demand for face masks, with the massive consumption of masks leading to an increase in resource-related and environmental concerns. In this work, we fabricated meltblown polypropylene (mb-PP)-based high-performance planar face masks and investigated the effects of six commonly used disinfection methods and various mask-wearing periods on the reusability of these masks. The results show that, after three cycles of treatment using hot water at 70 °C for 30 min, which is one of the most scalable, user-friendly methods for viral disinfection, the particle filtration efficiency (PFE) of the mask remained almost unchanged. After mask wearing for 24 h and subsequent disinfection using the same treatment procedures, the PFE decreased to 91.3%; the average number of bacterial and fungal colonies was assessed to be 9.2 and 51.6 CFU∙g−1, respectively; and coliform and pyogenic bacteria were not detected. Both the PFE and the microbial indicators are well above the standard for reusable masks after disinfection. Schlieren photography was then used to assess the capabilities of used and disinfected masks during use; it showed that the masks exhibit a high performance in suppressing the spread of breathed air.

Selective hydrogenation plays an important role in chemical industries, yet its selectivity is usually limited by the mass transfer. In this work, the enhanced hydrogenation selectivity was achieved in a rotating packed bed (RPB) reactor with excellent mass transfer efficiency. Aiming to be used under the centrifugal filed, a monolithic catalyst Pd/γ-Al2O3/nickel foam suiting for the shape and size of the rotor of RPB reactor was prepared by the electrophoretic deposition method. The mechanical strength of the catalyst can meet the requirement of high centrifugal force in the RPB. The hydrogenation selectivity in the RPB reactor using the 3-methyl-1-pentyn-3-ol hydrogenation system was 3 ∼ 8 times higher than that in a stirred tank reactor under similar conditions. This work proves the feasibility of intensifying the selectivity of hydrogenation process in the RPB reactor.

The Suzuki polymerization of heterogeneous systems was strengthened in a rotating packed bed via a high-gravity technique. As a result, poly(9,9-dioctylfluorene) with low polydispersity was efficiently and conveniently obtained.

The non-uniform aggregation of fast-diffused Li on an anode surface would aggravate its tip-effect-induced nucleation/growth, leading to the notorious dendrite growth in Li metal batteries (LMBs). Tuning the Li diffusion on the anode surface has been regarded previously as a mainstream method to induce its uniform deposition, while the diffusion of Li in the anode bulk is usually ignored. Here, conceptually different from the classic surface modification, we propose a molecular tunnelling strategy to construct atomic channels in graphite bulk, which enables the fast diffusion of superdense Li. Density functional theory calculations and ab initio molecular dynamics simulations prove that the bulk diffusion through atomic channels could become a new and dominating path. Its reversible and efficient diffusion has been further visualized by in situ transmission electron microscopy. As a result, when coupled with high-loading LiFePO4 cathodes (20 mg cm−2), a high areal capacity and 100% capacity retention are achieved over 370 cycles. Through this work a new strategy is developed based on the bulk-diffusion of superdense Li for dendrite-free LMBs, which can be pervasive in other high-performance energy storage systems.

The rotating packed bed (RPB) has been widely used in gas-liquid flow systems as a process intensification device, exhibiting excellent mass transfer enhancement characteristics. However, the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods. In the past two decades, Computational Fluid Dynamics (CFD) has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design. This article covers the development of the CFD simulation of gas-liquid flow in RPB. Firstly, the improvement of the simulation method in the aspect of mathematical models, geometric models, and solving methods is introduced. Secondly, new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed, including pressure drop, velocity distribution, flow pattern, and concentration distribution, etc. Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works. In addition, the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications. The defects of current research and future development directions are also discussed at last.

Ultrasmall metal-organic frameworks (MOFs) may generate unique properties to expand the scope of applications. However, the synthesis is still a great challenge. Herein, we propose a strategy to synthesize ultrasmall MOFs by high gravity technology. With the aid of tremendous intensification of molecular mixing and mass transfer in high-gravity field, six typical MOFs were obtained instantaneously in a continuous way. These samples are monodispersed with sub-5 nm in size, smaller than the previously reported values and even close to the length of one crystal unit cell. As a proof-of-concept, catalytic activity for Knoevenagel reaction can be significantly enhanced using ultrasmall ZIF-8. Conversion time of benzaldehyde was decreased by 94 % or 75 % compared to those using conventional or hierarchically porous ZIF-8. More importantly, this approach is readily scalable with the highest space-time yield for nano-MOFs, which may promote the convenient synthesis and practical applications of ultrasmall MOFs in large-scale.

Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue. Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this issue. In this work, a plasma-assisted rotating disk reactor (plasma-RDR) and a photocatalyst—namely, titanium dioxide (TiO2)—were coupled for the treatment of metronidazole (MNZ). Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR, which contributed to the utilization of ultraviolet (UV) light radiation in the presence of TiO2. The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41% and 2.954 mg·L−1 as the rotational speed increased from 0 to 500 r·min−1. The synergistic effect of plasma-RDR plus TiO2 on the generation of hydroxyl radicals was evaluated. Major intermediate products were identified using three-dimensional (3D) excitation emission fluorescence matrices (EEFMs) and liquid chromatography–mass spectrometry (LC-MS), and a possible degradation pathway is proposed herein. This plasma-catalytic process has bright prospects in the field of antibiotics degradation.

OBJECTIVE The aim of the present study was to evaluate the cost-effectiveness ratio of surgical treatment options for small hepatocellular carcinoma (SHC) by using the decision tree model and providing a reference for the clinical therapeutic decisions for SHC. METHODS The data of 719 cases with SHC in the BCLC 0-A who were treated in the past were collected. The survival duration and treatment cost of patients in each experimental group after hepatic resection (HR), radiofrequency ablation (RFA), and orthotopic liver transplantation (OLT) were statistically analyzed. RESULTS For SHC with a diameter of less than 3.0 cm, HR, RFA, and OLT had similar cost-effectiveness ratios. OLT could achieve a longer life expectancy, but it was greatly affected by the dropout rate while waiting for the liver donor. RFA was preferred when the willingness to pay (WTP) 75,000 RMB/QALY, and HR was preferred when WTP was between the two. EXPERT OPINION HR in SHC with OLT had the longest life expectancy, but due to the limitations of organ sources, OLT was the preferred treatment option when the WTP was large enough.