It had been demonstrated that stromal cell-derived factor-1α (SDF-1α) could promote in situ tendon regeneration by recruiting endogenous cells. However, native SDF-1α diffuses too fast in vivo, ...reducing its local concentration and efficacy. In this study, we prepared a recombinant SDF-1α containing a collagen-binding domain (CBD-SDF-1α) and developed a functional collagen scaffold by tethering CBD-SDF-1α on the collagen scaffold for in situ tendon regeneration. CBD-SDF-1α could induce the migration of mesenchymal stem cells, dermal fibroblasts and Achilles tendon fibroblasts in vitro, and achieve controlled release from the collagen scaffold. In a rat Achilles tendon defect model, the functional scaffold could increase the recruitment of CXCR4 positive fibroblast-like cells and the deposition of Tenascin-C at 7 days after implantation. After 4 and 12 weeks, the functional collagen scaffold could promote the expression of type I collagen, increase the diameters of collagen fibrils and improve the mechanical properties of regenerated tendons. Hence, the functional scaffold increased the efficacy of tendon regeneration by controlling release of SDF-1α, enhancing the recruitment of fibroblast-like cells and providing instructive microenvironment and mechanical support for tendon regeneration. Therefore, CBD-SDF-1α-modified collagen scaffold could serve as a practical application for tendon regeneration.
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•LFMO perovskite modified by spirulina biochar for catalytic ozonation of m-cresol.•Deactivation and regeneration mechanism of LFMO-xBiochar catalyst under pilot scale.•Catalyst ...deactivation mainly resulted from surface organic pollutants and deposits.•Water flushing can re-exposure the active sites and restore some pores.•Catalyst regeneration using water flushing is a convenient and effective process.
In this study, a LaFe0.26Mn0.74O3-δ perovskite catalyst modified using spirulina biochar (LFMO-xBiochar) was used to compare the effects of water flushing on the ozonation performance on a pilot scale. The results showed that timely water flushing operation could effectively extend the service life of LFMO-xBiochar and maintain the chemical oxygen demand (COD) removal rate above 60% for nearly 40 h during the reaction. Density functional theory (DFT) calculations showed that the protonated Fe, Mn, and oxygen vacancies on the catalyst surface were the main active sites. Combined with SEM/EDS mapping, BET, FTIR and XPS measurements, the results showed that organic pollutants and deposits hindered the ozone decomposition at the active sites on the catalyst surface, leading to its final deactivation. However, timely water flushing could effectively remove the organic pollutants and inorganic salts adsorbed onto the catalyst surface during the initial deactivation stage. Additionally, water flushing loosened or removed surface deposits, re-exposing the active sites and restoring some pores, thereby promoting the catalyst regeneration and prolonging its service life. This study provides new insights into the deactivation and regeneration of ozonation catalysts, which can support practical industrial applications of this process.
Electrochemical carbon dioxide (CO2) reduction (ECR) into valuable products such as formate is a compelling approach to managing excessive CO2 emissions. Tin (Sn)-based catalysts have been used for ...selective CO2 reduction to formate. However, they are often unstable for long-term ECR operation, especially at high reaction rates. In this work, we report highly selective Sn-based catalysts for CO2 reduction to formate at high current densities. The catalysts were prepared by depositing a layer of Sn nanoparticles on the surface of sputtered Ag on a polymer membrane. The catalysts exhibited over 90% Faradaic efficiency toward formate in the current density range of 50–300 mA/cm2 and were stable for over 20 h at a current density of 100 mA/cm2. Characterization of catalysts after ECR reaction reveals significant changes in catalyst morphology during ECR. To extend ECR operation time, we developed an in-situ catalyst regeneration strategy in which the catalysts are periodically oxidized during the reduction reaction. Using this approach, the operation time of Sn-catalysts was extended to more than 150 h with a selectivity over 90%, at the current density of 100 mA/cm2.
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•Sn/Ag/PTFE electrodes are selective for CO2-to-formate conversion.•Sn particle morphology changes drastically during CO2 reduction reaction.•In-situ Sn oxidation extends lifetime of the catalysts.•150-hour stability at 100 mA/cm2 is achieved with in-situ catalyst regeneration.
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•The in-situ zeolite regeneration achieves sustainable NH4+-N removal.•The NOx−-N removal process is explained by the leaching-readsorption cycle.•The stratification of adsorbed ...substances causes the inhibition of denitrification.•The two-way influent mode balances the nitrification and denitrification processes.
Tidal flow constructed wetlands (TFCWs) offer a promising method to treat domestic wastewater in rural areas. However, TFCWs are usually severely restricted by denitrification. This study aimed to explain the nitrogen removal process in TFCWs and provide an effective method to increase nitrogen removal. TFCWs filled zeolite (Z-TFCW) was established in this work, and its pollutants (NH4+-N, NOx−-N, and COD) removal performance, layered effect, microbial community characteristics, the in-situ regeneration process of Z-TFCW, and the two-way influent mechanisms were investigated. The results showed that under the downflow influent, the Z-TFCW effluent NH4+-N, NOx−-N, and COD concentrations were 9.79 ± 0.62 mg·L−1, 24.25 ± 1.53 mg·L−1, and 24.04 ± 2.68 mg·L−1, respectively. In the influent and flood period, NH4+-N was adsorbed rapidly by zeolite. Then, they were released into the biofilm and oxidized to NOx−-N during the drain period. The generated NOx−-N was leached to the bottom layer during the next cycle of influent, and most of them were adsorbed by the bottom biofilm for denitrification. Furthermore, the proportion of COD/NOx−-N in the top, middle, and bottom layers of Z-TFCW was 12.9, 3.1, and 1.0, respectively. Layered effect and microbial community analysis represented that COD limited the denitrification of Z-TFCW. The two-way influent optimized the distribution path of carbon sources for denitrification in Z-TFCW and enhanced nitrogen removal. Therefore, the NOx−-N effluent concentration decreased by 50.31 %.
This study proposed an innovative method, that biomass catalytic pyrolysis for 4-vinyl phenol under NH3 atmosphere with nitrogen-doped biochar catalyst, which could realize the in-situ regeneration ...of the catalyst. Results indicated that NH3 and nitrogen-doped biochar catalyst could significantly increase the bio-oil yield (up to 68 wt%) and the phenols content (80%). The selectivity and absolute yield of 4-vinyl phenol were 28% and 5.85 wt%, respectively. N/O-containing groups in the catalyst and free radicals from NH3 promoted the break of ester bonds and β-O-4 bonds, and converted phenols intermediates to 4-vinyl phenol. Meanwhile, NH3 also acted as activator and nitrogen dopant, which realized the in-situ regeneration of the catalyst. The regeneration rate of nitrogen content and SBET of the catalyst was up to 84.5%-150% and 72.9%-85.4%, respectively. In addition, the nitrogen-doped biochar catalyst also showed good stability and reusability, and the yield of 4-vinyl phenol was still as high as5.85–6.05 wt% after repeated use of BC10 catalyst for 3 times.
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•Catalytic pyrolysis for phenols with in-situ regeneration of catalyst was studied.•The content of phenols reached 80% with 5.85 wt% valuable 4-vinyl phenol.•NH3 regenerated N-doped biochar catalyst in situ as activator and nitrogen dopant.•Amount of N-doped biochar increased rather than reduced after catalytic pyrolysis.•Formation pathways of 4-vinyl phenol under NH3 with N-doped biochar was proposed.
In the strategy of in situ bone regeneration, it used to be difficult to specifically recruit bone marrow mesenchymal stem cells (BM-MSCs) by a single marker. Recently, CD271 has been considered to ...be one of the most specific markers to isolate BM-MSCs; however, the effectiveness of CD271 antibodies in recruiting BM-MSCs has not been explored yet. In this study, we developed novel CD271 antibody-functionalized chitosan (CS) microspheres with the aid of polydopamine (PDA) coating to recruit endogenous BM-MSCs for in situ bone regeneration. The CS microspheres were sequentially modified with PDA and CD271 antibody through dopamine self-polymerization and bioconjugation, respectively. In vitro studies showed that the CD271 antibody-functionalized microspheres selectively captured significantly more BM-MSCs from a fluorescently labeled heterotypic cell population than non-functionalized controls. In addition, the PDA coating was critical for supporting stable adhesion and proliferation of the captured BM-MSCs. Effective early recruitment of CD271+ stem cells by the functionalized microspheres at bone defect site of SD rat was observed by the CD271/DAPI immunofluorescence staining, which led to significantly enhanced new bone formation in rat femoral condyle defect over long term. Together, findings from this study have demonstrated, for the first time, that the CD271 antibody-functionalized CS microspheres are promising for in situ bone regeneration.
In article number 2100971, Chiheng Chu and co‐workers introduce hierarchically ordered porous poly(2,6‐diaminopyridine) (PDAP) as a Pd nanoparticle support for hydrogenation removal of recalcitrant ...pollutants in water purification. The PDAP support acts as a sorbent and microreactor to enhance the proximity of targeted water pollutants and reactive hydrogen atom species. The PDAP support also acts as a catalyst in mediating peroxide‐activation for oxidative destruction of Pd poisons.
•A CO2 combined oxidant method for PRB regeneration is proposed for leachate–contaminated areas near landfill.•CO2 well-washing technology is used for improving PRBs permeability.•The optimal ratios ...of oxidants and PRB fillers are proposed to achieve the best regeneration effect.
Groundwater contamination near landfills is commonly caused by leachate leakage, and permeable reactive barriers (PRBs) are widely used for groundwater remediation. However, the deactivation and blockage of the reactive medium in PRBs limit their long-term effectiveness. In the current study, a new methodology was proposed for the in situ regeneration of PRB to remediate leachate-contaminated groundwater. CO2 coupled with oxidants was applied for the dispersion and regeneration of the fillers; by injecting CO2 to disperse the fillers, the permeability of the PRB was increased and the oxidants could flow evenly into the PRB. The results indicate that the optimum filler proportion was zero-valent iron (ZVI)/zeolites/activated carbon (AC) = 3:8:10 and the optimum oxidant proportion was COD/Na2S2O8/H2O2/Fe2+ = 1:5:6:5; the oxidation system of Fe2+/H2O2/S2O82− has a high oxidation efficiency and persistence. The average regeneration rate of zeolites was 72.71%, and the average regeneration rate of AC was 68.40%; the permeability of PRB also increased. This technology is effective for the remediation of landfills in China that have large contaminated areas, an uneven pollutant concentration distribution, and a long pollution duration. The purification mode of long-term adsorption and short-time in situ oxidation can be applied to the remediation of long-term high-concentration organically polluted groundwater, where pollution sources are difficult to cut off.
In this work, an electric field-enhanced heterogeneous catalytic ozonation (EHCO) was systematically investigated using a prepared FeOx/PAC catalyst. The EHCO process exhibited high sulfadiazine ...(SDZ) and TOC removal efficiency compared with electrocatalysis (EC) and heterogeneous catalytic ozonation (HCO) process. Almost 100% of SDZ was removed within 2 min, and the TOC removal reached approximately 85% within 60 min. Quenching experiments and EPR analysis suggested that the prominent SDZ and TOC removal performance is supported by the enhanced ·OH generation ability. Further study proved that H2O2 formed by O2 electrochemical reduction, peroxone reaction and electrochemical reduction of ozone contributed to improving ·OH generation. Furthermore, the EHCO system showed satisfactory stability and recyclability compared to conventional HCO systems, and the SDZ and TOC removal rates were maintained at ≥95% and ≥70% in 16 consecutive recycles, respectively. Meanwhile, XPS analysis and Boehm's titration for the FeOx/PAC catalyst used in HCO and EHCO process confirmed that the external electron supply could restrain the oxidation of surface functional groups of PAC and maintain a balance of the Fe(II)/Fe(III) ratio, which proved the critical role of cathode reduction in catalyst in situ regeneration during long consecutive recycles. In addition, the EHCO system could achieve more than 80% SDZ removal within 2 min in different water matrices. These results confirmed that the EHCO process has a wide application perspective for refractory organics removal in actual wastewater.
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•An electric field-enhanced heterogeneous catalytic ozonation (EHCO) was developed.•Sulfadiazine removal and mineralization efficiency reached almost 100% and 85% by EHCO process.•FeOx/PAC heterogeneous catalyst could be in situ regenerated by cathodic reduction.•A feasible application achieved for antibiotics removal in actual water.
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