Re-recognize early recurrence of persistent atrial fibrillation.

Aims: Few studies on early recurrence (ER) focused on patients with persistent atrial fibrillation (AF). We aimed to investigate the characteristics and clinical significance of ER in patients with persistent AF after catheter ablation (CA). Methods: A total of 348 consecutive patients who underwent first-time CA for persistent and long-standing persistent AF between January 2019 and May 2022 were investigated. Results: About 5/348 (1.44%) patients who failed to convert to sinus rhythm after CA were excluded. A total of 110/343 (32.1%) patients had ER, in which 98 (89.1%) were persistent and 50.9% occurred in the first 24 h after CA. Compared with the patients without ER, those with ER were more likely to have late recurrence (LR) (92.7% vs. 1.7%, P < 0.001) during a median follow-up of 13 (IQR 6-23) months. ER was the most significant independent predictor for LR (OR 120.5, 95% CI 41.5-349.8, P < 0.001). ER as atrial flutter (AFL) had a lower risk of LR when compared with ER as AF (P = 0.011) and both AF and AFL (P = 0.003). Early intervention of the patient with ER improved the short-term outcomes (P < 0.001), not long-term outcomes. Only 22/251 (8.76%) patients of LR appears among those who had no recurrence in the first month. Conclusions: Patients with persistent AF may not have a blanking period but rather have a risk period. Clinical significance of the blanking period should be given differential treatment between paroxysmal AF and persistent AF.

Novel monolithic catalysts for VOCs removal: A review on preparation, carrier and energy supply.

Volatile organic compounds (VOCs) are considered the culprit of secondary air pollution such as ozone, secondary organic aerosols, and photochemical smog. Among various technologies, catalytic oxidation is considered a promising method for the post-treatment of VOCs. Researchers are sparing no effort to develop novel catalysts to meet the requirements of the catalytic process. Compared with the powdered or granular catalysts, the monolithic catalysts have the advantages of low pressure drop, high utilization of active phases, and excellent mechanical properties. This review summarized the new design of monolithic catalysts (including new preparation methods, new supports, and new energy supply methods) for the post-treatment of VOCs. It addressed the advantages of the new designs in detail, and the scope of applicability for each new monolithic catalyst was also highlighted. Finally, the highly required future development trends of monolithic catalysts for VOCs catalytic oxidation are recommended. We expect this work can inspire and guide researchers from both academic and industrial communities, and help pave the way for breakthroughs in fundamental research and industrial applications in this field.

Acid Etching-Induced In Situ Growth of λ-MnO2 over CoMn Spinel for Low-Temperature Volatile Organic Compound Oxidation.

Surface lattice oxygen is crucial to the degradation of volatile organic compounds (VOCs) over transition metal oxides according to the Mars-van Krevelen mechanism. Herein, λ-MnO2 in situ grown on the surface of CoMn spinel was prepared by acid etching of corresponding spinel catalysts (CoMn-Hx-Ty) for VOC oxidation. Experimental and relevant theoretical exploration revealed that acid etching on the CoMn spinel surface could decrease the electron cloud density around the O atom and weaken the adjacent Mn-O bond due to the fracture of the surface Co-O bond, facilitating electron transfer and subsequently the activation of surface lattice oxygen. The obtained CoMn-H1-T1 exhibited an excellent catalytic performance with a 90% acetone conversion at 149 °C, which is 42 °C lower than that of CoMn spinel. Furthermore, the partially maintained spinel structure led to better stability than pure λ-MnO2. In situ diffuse reflectance infrared Fourier transform spectroscopy confirmed a possible degradation pathway where adsorptive acetone converted into formate and acetate species and into CO2, in which the consumption of acetate was identified as the rate-limiting step. This strategy can improve the catalytic performance of metal oxides by activating surface lattice oxygen, to broaden their application in VOC oxidation.

Recent Advances of Chlorinated Volatile Organic Compounds' Oxidation Catalyzed by Multiple Catalysts: Reasonable Adjustment of Acidity and Redox Properties.

The severe hazard of chlorinated volatile organic compounds (CVOCs) to human health and the natural environment makes their abatement technology a key topic of global environmental research. Due to the existence of Cl, the byproducts of CVOCs in the catalytic combustion process are complex and toxic, and the possible generation of dioxin becomes a potential risk to the environment. Well-qualified CVOC catalysts should process favorable low-temperature catalytic oxidation ability, excellent selectivity, and good resistance to poisoning, which are governed by the reasonable adjustment of acidity and redox properties. This review overviews the application of different types of multicomponent catalysts, that is, supported noble metal catalysts, transition metal oxide/zeolite catalysts, composite transition metal oxide catalysts, and acid-modified catalysts, for CVOC degradation from the perspective of balance between acidity and redox properties. This review also highlights the synergistic degradation of CVOCs and NOx from the perspective of acidity and redox properties. We expect this work to inspire and guide researchers from both the academic and industrial communities and help pave the way for breakthroughs in fundamental research and industrial applications in this field.

Defective Ultrafine MnOx Nanoparticles Confined within a Carbon Matrix for Low-Temperature Oxidation of Volatile Organic Compounds.

The development of catalysts for volatile organic compound (VOC) treatment by catalytic oxidation is of great significance to improve the atmospheric environment. Size-effect and oxygen vacancy engineering are effective strategies for designing high-efficiency heterogeneous catalysts. Herein, we explored the in situ carbon-confinement-oxidation method to synthesize ultrafine MnOx nanoparticles with adequately exposed defects. They exhibited an outstanding catalytic performance with a T90 of 167 °C for acetone oxidation, which is 73 °C lower than that of bulk MnOx (240 °C). This excellent catalytic activity was primarily ascribed to their high surface area, rich oxygen vacancies, abundant active oxygen species, and good reducibility at low temperatures. Importantly, the synthesized ultrafine MnOx exhibited impressive stability in long-term, cycling and water-resistance tests. Moreover, the possible mechanism for acetone oxidation over MnOx-NA was revealed. In this work, we not only prepared a promising material for removing VOCs but also provided a new strategy for the rational design of ultrafine nanoparticles with abundant defects.

Synthesis of Silanol-Rich MCM-48 with Mixed Surfactants and Their Application in Acetone Adsorption: Equilibrium, Kinetic, and Thermodynamic Studies.

Mesoporous silica MCM-48 with rich silanol was prepared using polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) as mixed templates, and the dynamic adsorption performance of acetone was evaluated by testing breakthrough curves. The mixed micelle formed by CTAB and PVP, as well as the hydrogen bond between the carbonyl group of PVP and silanol group affected the condensation process of Si-OH group during the formation of mesoporous structure, resulting in the increase of Si-OH group number on the surface of MCM-48. Compared with MCM-48 synthesized by single template (CTAB), the acetone adsorption capacity of MCM-48 (1:3) synthesized by mixed templates (PVP:CTAB = 1:3) improved by 23.86%, which was attributed to the increase of silanol group amount and the decrease of pore size. In addition, Bangham model had the highest goodness of fit to describe the adsorption process among four kinetic models for the adsorbents, conforming to the mechanism of pore diffusion. The Langmuir and Freundlich models were used to fit the adsorption isotherm data, and the Freundlich model could better describe the adsorption of acetone. Freundlich model fitting results showed that MCM-48 with rich silanol had a strong affinity for acetone, and the adsorption of acetone on MCM-48 belonged to multilayer adsorption. The thermodynamic results showed that the adsorption of MCM-48 for acetone was physical adsorption, and the adsorption behavior was exothermic. This work provided insight into how the inherent properties of an adsorbent and environmental factors (including initial concentration and adsorption temperature) affected the adsorption performance of ketones, thus more ideas could be provided for the accurate design of adsorbents. Furthermore, silanol-rich MCM-48 synthesized by mixed templates is expected to be a promising adsorbent for acetone removal.

Oxidation of acetone over Co-based catalysts derived from hierarchical layer hydrotalcite: Influence of Co/Al molar ratios and calcination temperatures.

In order to enhance catalytic performance for acetone, Co-based catalysts prepared under different Co/Al molar ratios and calcination temperatures have been studied in this work. The results indicated that the catalytic activities of the catalysts firstly increased and then decreased with the increase of the Co/Al molar ratio and decreased with the increase of the calcination temperature. Based on the catalytic activities, TG/DTA, XRD, TPR and XPS characterization results, it can be found that catalytic activities of the catalysts with various Co/Al molar ratios were effected by the good crystallization structure of catalyst precursor, surface Co3+/Co2+ molar ratio, low temperature reducibility, and Oads/Olatt molar ratio of the catalysts. Meanwhile, the catalytic activities of the catalysts with different calcination temperatures depended on the low temperature reducibility, surface Co3+/Co2+ molar ratio, porous structure and crystallization structure of the catalyst. Among different synthetic composition, 5:1 CoAlO-300 catalyst (T90% = 225 °C) and 5:1 CoAlO-200 catalyst (T90% = 222 °C) exhibited the efficient acetone oxidation.

Contamination source apportionment and health risk assessment of heavy metals in soil around municipal solid waste incinerator: A case study in North China.

Few studies have comprehensively taken into account the source apportionment and human health risk of soil heavy metals in the vicinity of municipal solid waste incinerator (MSWI) in high population density area. In this study, 8 elements (Cr, Pb, Cu, Ni, Zn, Cd, Hg, and As) in fly ash, soil samples from different functional areas and vegetables collected surrounding the MSWI in North China were determined. The single pollution index, integrated Nemerow pollution index, principal component analysis (PCA), absolute principle component score-multiple linear regression (APCS-MLR) model and dose-response model were used in this study. The results showed that the soils around the MSWI were moderately polluted by Cu, Pb, Zn, and Hg, and heavily polluted by As and Cd. MSWI had a significant influence on the distribution of soil heavy metals in different distances from MSWI. The source apportionment results showed that MSWI, natural source, industrial discharges and coal combustion were the four major potential sources for heavy metals in the soils, with the contributions of 36.08%, 29.57%, 10.07%, and 4.55%, respectively. MSWI had a major impact on Zn, Cu, Pb, Cd, and Hg contamination in soil. The non-carcinogenic risk and carcinogenic risk posed by soil heavy metals surrounding the MSWI were unacceptable. The soil heavy metals concentrations and health risks in different functional areas were distinct. MSWI was the predominate source of non-carcinogenic risk with the average contribution rate of 36.99% and carcinogenic risk to adult male, adult female and children with 4.23×10-4, 4.57×10-4, and 1.41×10-4 respectively, implying that the impact of MSWI on human health was apparent. This study provided a new insight for the source apportionment and health risk assessment of soil heavy metals in the vicinity of MSWI.