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Steroid-based drugs are now mainly produced by the microbial transformation of phytosterol, and a two-step bioprocess is adopted to reach high space-time yields, but byproducts are frequently observed during the bioprocessing. In this study, the catabolic switch between the C19- and C22-steroidal subpathways was investigated in resting cells of Mycobacterium neoaurum NRRL B-3805, and a dose-dependent transcriptional response toward the induction of phytosterol with increased concentrations was found in the putative node enzymes including ChoM2, KstD1, OpccR, Sal, and Hsd4A. Aldolase Sal presented a dominant role in the C22 steroidal side-chain cleavage, and the byproduct was eliminated after sequential deletion of opccR and sal. Meanwhile, the molar yield of androst-1,4-diene-3,17-dione (ADD) was increased from 59.4 to 71.3%. With the regard of insufficient activity of rate-limiting enzymes may also cause byproduct accumulation, a chromosomal integration platform for target gene overexpression was established supported by a strong promoter L2 combined with site-specific recombination in the engineered cell. Rate-limiting steps of ADD bioconversion were further characterized and overcome. Overexpression of the kstD1 gene further strengthened the bioconversion from AD to ADD. After subsequential optimization of the bioconversion system, the directed biotransformation route was developed and allowed up to 82.0% molar yield with a space-time yield of 4.22 g·L-1·day-1. The catabolic diversion elements and the genetic overexpression tools as confirmed and developed in present study offer new ideas of M. neoaurum cell factory development for directed biotransformation for C19- and C22-steroidal drug intermediates from phytosterol. KEY POINTS: ⢠Resting cells exhibited a catabolic switch between the C19- and C22-steroidal subpathways. ⢠The C22-steroidal byproduct was eliminated after sequential deletion of opccR and sal. ⢠Rate-limiting steps were overcome by promoter engineering and chromosomal integration.
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Aldeído Liases , Fitosteróis , Androstadienos , Diferenciação Celular , PolienosRESUMO
The combination of new noble metal nanomaterials and surface enhanced Raman scattering (SERS) technology has become a new strategy to solve the problem of low sensitivity in the detection of traditional Chinese medicine. In this work, taking natural cicada wing (C.w.) as a template, by optimizing the magnetron sputtering experimental parameters for the growth of Ag nanoparticles (NPs) on vanadium-titanium (V-Ti) nanorods, the nanogaps between the nanorods were effectively regulated and the Raman signal intensity of the Ag15/V-Ti20/C.w. substrate was improved. The proposed homogeneous nanostructure exhibited high SERS activity through the synergistic effect of the electromagnetic enhancement mechanism at the nanogaps between the Ag NPs modified V-Ti nanorods. The analytical enhancement factor (AEF) value was as high as 1.819 × 108, and the limit of detection (LOD) was 1 × 10-11 M for R6G. The large-scale distribution of regular electromagnetic enhancement "hot spots" ensured the good reproducibility with the relative standard deviation (RSD) value less than 7.31%. More importantly, the active compound of Artemisinin corresponded the pharmacological effect of Artemisia annua was screened out by SERS technology, and achieved a LOD of 0.01â mg/l. This reliable preparation technology was practically applicable to produce SERS-active substrates in detection of pharmacodynamic substance in traditional Chinese medicine.
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Artemisininas , Nanopartículas Metálicas , Nanotubos , Animais , Análise Espectral Raman , Titânio/química , Nanopartículas Metálicas/química , Prata/química , Vanádio , Reprodutibilidade dos Testes , Nanotubos/químicaRESUMO
Solar-driven selective oxygen reduction reaction on polymeric carbon nitride framework is one of the most promising approaches toward sustainable H2 O2 production. Potassium poly(heptazine imide) (PHI), with regular metal sites in the framework and favorable crystalline structure, is highly active for photocatalytic selective 2e oxygen reduction to produce H2 O2 . By introducing NH4 Cl into the eutectic KCl-LiCl salt mixture, the PHI framework exhibits a remarkable performance for photocatalytic production of H2 O2 , for example, a record high H2 O2 photo-production rate of 29.5â µmol h-1 â mg-1 . The efficient photocatalytic performance is attributed to the favorable properties of the new PHI framework, such as improved porosity, negatively shifted LUMO position, enhanced exciton dissociation and charges migration properties. A mechanistic investigation by quenching and electron spin resonance technique reveals the critical role of superoxide radicals for the formation singlet oxygen, and the singlet oxygen is one of the critical intermediates towards the formation of the H2 O2 by proton extraction from the ethanol.
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Lithium-ion diffusion ability in solid electrolytes is crucial for the performance and safety of lithium-ion batteries. However, the lithium-ion diffusion coefficient of Li6.75La3Zr1.5Ta0.5O12 (LLZTO) measured experimentally is much lower than that simulated theoretically because LLZTO exists widely in the polycrystalline form rather than in the single-crystal form. Herein, we focus on the construction of grain boundaries in polycrystalline materials to address this key issue. An amorphous structure is created by randomly throwing atoms into a virtual box, where the chemical bonds are broken and rearranged through continuous heating and annealing operations, resulting in a stable framework structure. The lithium-ion diffusion coefficients of polycrystalline LLZTO and single-crystal LLZTO calculated via Ab initio molecular dynamics (AIMD) are consistent with the experimental data in trend. Furthermore, the analysis of the grain boundary composed of the secondary phase in polycrystalline LLZTO reveals that the continuous -O-M-O- metal oxide grid with low formation energy per atom restricts the lithium-ion migration. The lithium-ion migration barriers calculated utilizing density functional theory (DFT) also demonstrate the obstacle of the grain boundary from another perspective.
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In this study, the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soil washing solution containing Tween 80 was conducted using native mixed bacteria (Pseudomonas sp. Z1, Sphingobacterium sp. Z2, and Klebsiella sp. K) embedded in polyvinyl alcohol-sodium alginate-nano alumina (PVA-SA-ALNPs) gel beads. The optimal dosage of immobilized beads and embedded biomass for the biodegradation of phenanthrene (PHE), fluoranthene (FLU), and pyrene (PYR) were 10 % (v/v) and 20 % (v/v), respectively. SEM analysis showed that the porous structure of the immobilized beads was a cross-linked network with abundant pores that provided many potential adhesion sites for microorganisms. The beads with the immobilized mixed bacteria maintained a high activity during batch experiments and could even be reused for 3 cycles (90 d). Compared with the beads containing individual immobilized strain, the immobilized mixed bacteria showed a more efficient biodegradation of PHE (91.67 %), FLU (88.6 %), and PYR (88.5 %) in synthetic soil washing effluent within 30 d. The first-order kinetic model suitably described the degradation process of the three target PAHs. By adding Tween 80 to the synthetic eluent, the degradation of PHE, FLU, and PYR increased by 16.39 %, 22.25 %, and 21.29 %, respectively, indicating that Tween 80 promoted PAHs biodegradation, even though it was also rapidly degraded during the reaction cycle. These findings suggest that the developed mixed bacteria embedded in PVA-SA-ALNPs gel beads has great potential for PAHs remediation.
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Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Alginatos , Óxido de Alumínio , Bactérias , Biodegradação Ambiental , Álcool de Polivinil , SoloRESUMO
Normal temperature catalytic ozonation (NTCO) is a promising yet challenging method for the removal of volatile organic compounds (VOCs) because of limited activity of the catalysts at ambient temperature. Here, we report a series of Pt/FeOx catalysts prepared by the co-precipitation method for NTCO of gaseous methanol. All samples were found to be active and among them, the Pt/FeOx-400 (calcined at 400 °C) catalyst with a Pt cluster loading of 0.2% exhibited the highest activity, able to completely convert methanol into CO2 and H2O at 30 °C. Extensive experimental research suggested that the superior catalytic activity could be attributed to the highly dispersed Pt clusters and an appropriate molar ratio of Pt0/Pt2+. Furthermore, electron paramagnetic resonance and density functional theory computational studies revealed the mechanism that the Pt/FeOx-400 catalyst could activate O3 and water effectively to produce hydroxyl radicals responsible for the catalytic oxidation of methanol. The findings of this work may foster the development of technologies for normal temperature abatement of VOCs with low energy consumption.
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Metanol , Ozônio , Catálise , Platina , TemperaturaRESUMO
Large-scale datasets with point-wise semantic and instance labels are crucial to 3D instance segmentation but also expensive. To leverage unlabeled data, previous semi-supervised 3D instance segmentation approaches have explored self-training frameworks, which rely on high-quality pseudo labels for consistency regularization. They intuitively utilize both instance and semantic pseudo labels in a joint learning manner. However, semantic pseudo labels contain numerous noise derived from the imbalanced category distribution and natural confusion of similar but distinct categories, which leads to severe collapses in self-training. Motivated by the observation that 3D instances are non-overlapping and spatially separable, we ask whether we can solely rely on instance consistency regularization for improved semi-supervised segmentation. To this end, we propose a novel self-training network InsTeacher3D to explore and exploit pure instance knowledge from unlabeled data. We first build a parallel base 3D instance segmentation model DKNet, which distinguishes each instance from the others via discriminative instance kernels without reliance on semantic segmentation. Based on DKNet, we further design a novel instance consistency regularization framework to generate and leverage high-quality instance pseudo labels. Experimental results on multiple large-scale datasets show that the InsTeacher3D significantly outperforms prior state-of-the-art semi-supervised approaches.
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The study assessed a co-processing system segregating food waste (FW) with different impurities into liquid (slurry) and solid fractions and treated using anaerobic digestion (AD) and pyrolysis (Py), respectively, which is defined as ADCo-Py. Biomethane potential tests showed higher methane yield from the FW slurry fraction (572.88 mL/gVSFW) compared to the whole FW (294.37 mL/gVSFW). Pyrolyzing the FW solid fraction reduced nitrogen compounds in bio-oil by 62 % compared to the whole FW. The energy balance and economic feasibility of ADCo-Py were compared with stand-alone AD, Py, and AD integrated with incineration (ADCo-INC). While all systems required extra energy, stand-alone Py and ADCo-INC needed 3.8 and 2.8 times more energy than ADCo-Py, respectively. Techno-economic analysis favored ADCo-Py, with a net present value (NPV) of $15 million and an internal rate of return (IRR) of 34 %. These findings highlighted FW separation as a promising approach, aligning with energy and economic goals in sustainable FW management.
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Eliminação de Resíduos , Gerenciamento de Resíduos , Perda e Desperdício de Alimentos , Alimentos , Incineração , Metano , Anaerobiose , Reatores BiológicosRESUMO
Rapid, universal and accurate identification of chemical composition changes in multi-component traditional Chinese medicine (TCM) decoction is a necessary condition for elucidating the effectiveness and mechanism of pharmacodynamic substances in TCM. In this paper, SERS technology, combined with grating-like SERS substrate and machine learning method, was used to establish an efficient and sensitive method for the detection of TCM decoction. Firstly, the grating-like substrate prepared by magnetron sputtering technology was served as a reliable SERS sensor for the identification of TCM decoction. The enhancement factor (EF) of 4-ATP probe molecules was as high as 1.90 × 107 and the limit of detection (LOD) was as low as 1 × 10-10 M. Then, SERS technology combined with support vector machine (SVM), decision tree (DT), Naive Bayes (NB) and other machine learning algorithms were used to classify and identify the three TCM decoctions, and the classification accuracy rate was as high as 97.78 %. In summary, it is expected that the proposed method combining SERS and machine learning method will have a high development in the practical application of multi-component analytes in TCM.
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Lignin is an abundant renewable source of aromatics, but its complex heterogeneous structure poses challenges for its depolymerization and valorization. Heterogeneously catalyzed reductive depolymerization (HCRD) has emerged as a promising approach, utilizing heterogeneous catalysts to facilitate selective bond cleavage in lignin and hydrogen transfer to stabilize the products under mild conditions. This review provides a comprehensive understanding of the hydrogen transfer mechanisms in HCRD involving different hydrogen sources including molecular hydrogen, alcohols, formic acid, etc., and the native hydrogen donor groups in lignin. Recent advances in catalyst design for efficient lignin depolymerization are systematically discussed, focusing on precious metal-based (Pt, Ru, Pd) and non-precious metal-based catalysts. Factors influencing catalyst performance, such as metal-support interactions, promoters, and synergistic effects, are highlighted. The diverse array of high-value aromatic chemicals obtained from HCRD is overviewed. Finally, the significance of HCRD in the context of lignin valorization and the development of integrated biorefineries is discussed, underscoring its potential to contribute to a sustainable bioeconomy.
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Peroxydisulfate (PDS)-based Fenton-like reactions are promising advanced oxidation processes (AOPs) to degrade recalcitrant organic water pollutants. Current research predominantly focuses on augmenting the generation of reactive species (e.g., surface-activated PDS complexes (PDS*) to improve treatment efficiency, but overlooks the potential benefits of enhancing the reactivity of these species. Here, we enhanced PDS* generation and reactivity by incorporating Zn into CuO catalyst lattice, which resulted in 99% degradation of 4-chlorophenol within only 10 min. Zn increased PDS* generation by nearly doubling PDS adsorption while maintaining similar PDS to PDS* conversion efficiency, and induced higher PDS* reactivity than the common catalyst CuO, as indicated by a 4.1-fold larger slope between adsorbed PDS and open circuit potential of a catalytic electrode. Cu-O-Zn formation upshifts the d-band center of Cu sites and lowers the energy barrier for PDS adsorption and sulfate desorption, resulting in enhanced PDS* generation and reactivity. Overall, this study informs strategies to enhance PDS* reactivity and design highly active catalysts for efficient AOPs.
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This research conducted an environmental life cycle assessment (LCA) to evaluate an anaerobic digestion-co-pyrolysis (ADCo-Py) system in which pyrolysis was added to traditional food waste (FW) anaerobic digestion (AD) systems to treat the solid fraction and impurities separated from FW. The solid fraction, including impurities such as wooden chopsticks, plastics, eggshells, and bones, is usually incinerated, while pyrolysis can be a viable alternative to optimize FW treatment. The environmental impact of ADCo-Py was compared with stand-alone AD, pyrolysis, and ADCo-INC (AD with incineration of separated solids). The results indicated that both ADCo-Py (-1.726 kg CO2-Eq/kgFW) and ADCo-INC (-1.535 kg CO2-Eq/kgFW) outperform stand-alone AD (-0.855 kg CO2-Eq/kgFW) and pyrolysis (-0.181 kg CO2-Eq/kgFW) in mitigating global warming potential (GWP). Additionally, pretreatments were found to have the most significant influence on GWP, ecotoxicity potential (ETP), and acidification potential (AP). The two-step pretreatment in ADCo-Py, including the separation of solids and drying, significantly improved the environmental sustainability of the system when compared with standalone pyrolysis.
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Eliminação de Resíduos , Gerenciamento de Resíduos , Eliminação de Resíduos/métodos , Gerenciamento de Resíduos/métodos , Perda e Desperdício de Alimentos , Dióxido de Carbono , Pirólise , Anaerobiose , AlimentosRESUMO
A lamellar carbon nitride (CN) framework is one of the most promising materials for solar-driven hydrogen peroxide production. The low dielectric constant of the organic CN framework leads to severe recombination of the excitons, and the photon-to-chemical conversion efficiency is thus unsatisfactory. In this work, by polycondensation of the small molecules on the KCl crystal surface, K+-incorporated crystalline CN (CNK) frameworks show significantly extended periodicity of the stacking layers and in-plane orderly organized heptazine/triazine units. The crystalline CNK frameworks exhibit a series of favorable photophysical properties, such as enhanced photon absorption, negatively shifted LUMO potentials, and attenuated emissive decay of the excitons. The CNK frameworks thus present remarkable performance in the photocatalytic selective oxygen reduction reaction for hydrogen peroxide production, e.g., CNK framework from the polycondensation of NH4SCN on the KCl surface could produce hydrogen peroxide at a remarkable reaction rate of 26.7 mmol h-1 g-1 with a high apparent quantum yield of 25.0%, which is 23.5 times that on its counterpart synthesized in the absence of KCl. This method is generally applicable to all of the precursors for CN synthesis.
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Volatile organic compounds (VOCs) have caused a serious threat to the atmosphere and human health. Therefore, it is of great significance to exploit effective catalytic materials for the safe and effective catalytic elimination of VOCs. Herein, Ag-MnOx-ACF composite catalysts were constructed via a two-step impregnation strategy and used for catalytic toluene degradation. A remarkable low-temperature catalytic activity (T100 = 50â), excellent stability, as well as CO2 selectivity (80%) were achieved over the Ag-MnOx-ACF catalyst. A series of characterizations indicated that the unique manganese defects structure of birnessite phase manganese oxide played an essential role for toluene oxidation, which was conducive to generating surface adsorbed oxygen. The higher ratio of Mn3+/Mn4+, abundant surface adsorbed oxygen and highly dispersed Ag species were determined to significantly facilitate toluene degradation. The mechanism of efficient degradation of toluene at low temperature was proposed. O3 and H2O molecules were activated via surface hydroxyl and Mn defects on Ag-MnOx-ACF to produce sufficient â¢OH, enhancing the degradation performance of toluene. We provide a new idea for the catalytic oxidation of benzene VOCs at low even room temperatures.
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Óxidos , Tolueno , Humanos , Temperatura , Tolueno/química , Óxidos/química , Oxirredução , Manganês , Oxigênio , CatáliseRESUMO
With the utilization of degradable plastics in the agricultural film and packaging industries, degradable microplastics (MPs) with strong mobility distributed in the underground environment may serve as carriers for heavy metals. It is essential to explore the interaction of (aged) degradable MPs with Cd(â ¡). The adsorption and co-transport behavior of different types of (aged) MPs (polylactic acid (PLA), polyvinyl chloride (PVC)) with Cd(â ¡) were investigated through batch adsorption experiments and column experiments under different conditions, respectively. The adsorption results showed that the adsorptive capacity of (aged) PLA with O-functional groups, polarity, and more negative charges was stronger than that of PVC and aged PVC, which was attributed to the binding of (aged) PLA to Cd(â ¡) through complexation and electrostatic attraction. The co-transport results indicated that the promotion of Cd(â ¡) transport by MPs followed the order of aged PLA > PLA > aged PVC > PVC. This facilitation was more pronounced under conditions of stronger transport of MPs and favorable attachment of Cd(â ¡) to MPs. Overall, the combination of strong adsorption affinity and high mobility helped (aged) PLA act as effective carriers for Cd(â ¡). The DLVO theory well explains the transport behavior of Cd(â ¡)-MPs. These findings provide new insights into the co-transport of degradable MPs and heavy metals in the subsurface environment.
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Metais Pesados , Poluentes Químicos da Água , Microplásticos , Plásticos , Cádmio , Adsorção , Porosidade , Poliésteres , Poluentes Químicos da Água/análiseRESUMO
Benzene and its aromatic derivatives are typical volatile organic compounds for indoor and outdoor air pollution, harmful to human health and the environment. It has been considered extremely difficult to break down benzene rings at ambient conditions without external energy input, due to the extraordinary stability of the aromatic structure. Here, we show one such solution that can thoroughly degrade benzene to basically water and carbon dioxide at 25 °C in air using atomically dispersed Fe in N-doped porous carbon, with almost 100% benzene conversion. Further experimental studies combined with molecular simulations reveal the mechanism of this catalytic reaction. Hydroxyl radicals (·OH) evolved on the atomically dispersed FeN4O2 catalytic centers were found responsible for initiating and completing the oxidation of benzene. This work provides a new chemistry to degrade aromatics at ambient conditions and also a pathway to generate active ·OH oxidant for generic remediation of organic pollutants.
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Background: China, which has the largest chronic hepatitis B virus (HBV) burden, may expand antiviral therapy to attain the World Health Organization (WHO)-2030 goal of 65% reduction in mortality. We evaluated health outcomes and cost-effectiveness of chronic HBV infection treatments based on alanine transaminase (ALT) antiviral treatment initiation thresholds and coverage in China to identify an optimal strategy. Methods: A decision-tree Markov state-transition model evaluated the cost-effectiveness of expanded antiviral treatment for chronic HBV infection by simulating 136 scenarios by ALT treatment initiation thresholds (40 U/L, 35 U/L for males and 25 U/L for females, 30 U/L for males and 19 U/L for females, and treating HBsAg+ individuals regardless of ALT values), population age groups (18-80, 30-80, and 40-80 years), implementation durations (2023, 2028, and 2033) under and treatment coverages (20%, 40%, 60%, and 80%). Deterministic and probabilistic sensitivity analyses explored model uncertainty. Findings: Besides the status quo, we finally simulated 135 treatment-expanding scenarios based on the cross combination of different thresholds of ALT, treatment coverages, population's age groups and implementation time. For the status quo, a cumulative incidence of 16,038-42,691 HBV-related complications and 3116-18,428 related deaths will happened between 2030 and 2050. When the treatment threshold is expanded to 'ALT > 35 in males & ALT > 25 in females' immediately without expanding treatment coverage, it will save 2554 HBV-related complications and 348 related deaths compared to the status quo among the whole cohort by 2030, and US$ 156 million more will be costed for gaining 2962 more QALYs. If we just expand the ALT threshold to ALT > 30 in males & ALT > 19 in females, 3247 HBV-related complications and 470 related deaths will be prevented by 2030 under the current treatment coverage of 20%, which will cost US$ 242 million, US$ 583 million or US$ 606 million more by the year of 2030, 2040 or 2050, respectively. Treatment expanded to HBsAg+ will save the largest number of HBV-related complications and death. This expanding strategy also results in large complications or death reduction when it is limited to patients older than 30 years or 40 years. Under this strategy, four scenarios (Treating HBsAg+ with coverage of 60% or 80% for patients older than 18 years or 30 years) showed the effectiveness in reaching the target before the year 2030. Among all the strategies, treatment expanded to HBsAg+ would cost the most while providing the highest total QALYs compared to other strategies with similar implementation scenarios. ALT thresholds of 30 U/L and 19 U/L for males and females, respectively, with 80% coverage for 18-80 years, can attain the goal by 2043. Interpretation: Treating HBsAg+ individuals with 80% coverage for 18-80 years is optimal; earlier implementation of expanded antiviral treatment with a modified ALT threshold could decrease HBV-related complications and deaths to support the global target of 65% reduction in viral hepatitis B deaths. Funding: This study was funded by Global Center for Infectious Disease and Policy Research (BMU2022XY030); Global Health and Infectious Diseases Group (BMU2022XY030); The Chinese Foundations for Hepatitis Control and Prevention (2021ZC032); National Science and Technology Project on Development Assistance for Technology, Developing China-ASEAN Public Health Research and Development Collaborating Center (KY202101004); in part by National Key R&D Program of China (2022YFC2505100).
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Nano-confinement systems offer various extraordinary chemical/physical properties, due to the spatial restriction and the electronic interaction between the confined species and the surrounding medium. They are, therefore, providing rich opportunities for the design of efficient catalytic reaction systems for pollutant removal. Herein, a highly efficient mediated-electron transfer pathway is identified on a spatially-confined zero valent cobalt for abatement of the organic pollutants by PMS. The catalyst showed efficient catalytic performance in both batch and a flow reactor for degradation of various pollutants, e.g., a degradation reaction constant of 0.052 s-1 for sulfamethoxazole and 0.041 s-1 for BPA. Regulated by the spatial-confinement, a distinctive inverse relationship between PMS decomposition rate and the electron density of the pollutant molecule was experimentally substantiated, e.g., in the presence of the electron-rich sulfamethoxazole, PMS decomposed slower than that with BPA, while in the presence of electron deficient diphenhydramine, PMS decomposed faster than that with BPA. The unique reaction mechanism endows the spatially-confined cobalt with the capability of eliminating the priority pollutants in the complex water matrix with pervasive halide ions and natural organic matter (NOM) via PMS activation.
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(1) Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines were developed in only a short amount of time and were widely distributed. We conducted this meta-analysis to understand the safety of SARS-CoV-2 vaccines. (2) Methods: We searched the corresponding literature published from 1 January 2020 to 20 October 2021. Information of adverse events (AEs) of each selected work was collected. The quality and bias of studies was evaluated, and meta-analysis was carried out by using Stata 17.0. (3) Results: Totally, 11,451 articles were retrieved, and 53 of them were included for analysis. The incidence rate of AEs was 20.05-94.48%. The incidence rate of vascular events increased after viral vector vaccination, while the incidence rate of vascular events decreased after mRNA vaccination. Viral vector vaccine had a higher AE rate compared to mRNA vaccines and inactivated vaccines. In most circumstances, the incidence of AEs was higher in older people, female and after the second dose. The sensitivity of meta-analysis was acceptable; however, the literature was subject to a certain publication bias. (4) Conclusions: The safety of SARS-CoV-2 vaccines was acceptable. The incidence of allergic symptoms and cardiovascular and cerebrovascular symptoms was low. Viral vector vaccine had a higher risk of leading to thrombosis events. The understanding of SARS-CoV-2 vaccine AEs should be enhanced, so as to promote the vaccination.
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Normal temperature catalytic ozonation is an effective method for the removal of volatile organic compounds (VOCs). A series of TiO2-supported noble metal catalysts were synthesized by a facile impregnation method. The as-prepared catalysts were evaluated for the catalytic oxidation of toluene. It was determined that the 1â wt%Pt/TiO2 exhibited outstanding performance that 65% conversion of toluene was achieved with the space velocity of 30,000â h-1 even at room temperature (25°C). The structure-activity relationship of various catalysts was investigated via BET, XRD, SEM, TEM as well as XPS. The results indicated that the uniform dispersion of Pt nanoparticles, abundant surface adsorbed oxygen species as well as the strong interaction between Pt and TiO2 favoured toluene degradation at normal temperature. Based on FT-IR, a simplified reaction scheme was proposed: toluene was first oxidized to benzoate species then alcohol species, ketones, carboxyl acids, which was finally degraded into CO2 and H2O. The low activation energy of 1â wt%Pt/TiO2 determined to be 47â kJ mol-1 also benefited for toluene degradation at ambient temperature.