Latest ArticlesPersulfate-based advanced oxidation processes (AOPs) have obtained increasing attention due to the generation of sulfate radical (SO4•‒) with high reactivity for organic contaminants degradation. Numerous activation methods have been used to activate two common persulfates: peroxymonosulfate (PMS) and peroxydisulfate (PDS). However, the comparisons of activation methods and two oxidants in the comprehensive degradation performance of the target contaminant are still limited. Thus, taking norfloxacin (NOR) as the target contaminant, we proposed five key parameters (the observed pseudo-first-order rate constant, kobs; average mineralization rate, rm; utilization efficiency of catalyst, Ucat; utilization efficiency of oxidant, Uox; and net utilization efficiency of oxidant, Uox') to quantify the comprehensive degradation performance of NOR. The irradiation affected target pollutants, catalysts, and oxidants, leading to an improved degradation performance of NOR. Various heterogeneous catalysts were compared in terms of the key elements contained. Fe, Co, and Mn-based materials performed better, while carbon-based catalysts performed poorly on NOR degradation. The overall degradation performance of NOR was different for PMS and PDS, which can be ascribed to their varied reaction pathways towards NOR, but stemmed from different properties of PMS and PDS. Besides, the effect of pH on the degradation efficiency of NOR was investigated. A neutral solution was optimal for PMS system, while an acidic solution worked better for PDS system. Finally, we analyzed the molecule structure of NOR by density functional theory (DFT) calculation to study the sites easy to attack. Then, we summarized four typical degradation pathways of NOR in SO4•‒-based AOP systems, including defluorination, piperazine ring cleavage, piperazine ring oxidation, and quinoline group transformation.
A facile and efficient electrochemical method for sustainable constructing both selanyl phenanthrenes and selanyl polycyclic heteroaromatics (32 examples, 71%-97% yields) through the radical annulation of 2-alkynyl biaryls and 2-heteroaryl-substituted alkynyl benzenes with diselenides at ambient temperature under additive-, chemical oxidant-, catalyst-free and mild conditions was established.
A continuous flow bioreactor was operated for 300 days to investigate partial nitritation (PN) of mature landfill leachate, establishing the long-term performance of the system in terms of the microbial community composition, evolution, and interactions. The stable operation phase (31–300 d) began after a 30 days of start-up period, reaching an average nitrite accumulation ratio (NAR) of 94.43% and a ratio of nitrite nitrogen to ammonia nitrogen (NO2−-N/NH4+-N) of 1.16. Some fulvic-like and humic-like compounds and proteins were effectively degraded in anaerobic and anoxic tanks, which was consistent with the corresponding abundance of methanogens and syntrophic bacteria in the anaerobic tank, and organic matter degrading bacteria in the anoxic tank. The ammonia-oxidizing bacteria (AOB) Nitrosomonas was found to be the key functional bacteria, exhibiting an increase in abundance from 0.27% to 6.38%, due to its collaborative interactions with organic matter degrading bacteria. In-situ inhibition of nitrite-oxidizing bacteria (NOB) was achieved using a combination of free ammonia (FA) and free nitrous acid (FNA), low dissolved oxygen (DO) with fewer bioavailable organics conditions were employed to maintain stable PN and a specific ratio of NO2−-N/NH4+-N, without an adverse impact on AOB. The synergistic relationships between AOB and both denitrifying bacteria and organic matter degrading bacteria, were found to contribute to the enhanced PN performance and microbial community structure stability. These findings provide a theoretical guidance for the effective application of PN-Anammox for mature landfill leachate treatment.
The solid electrolyte interphase (SEI), a passivation film covering the electrode surface, is crucial to the lifetime and efficiency of the lithium-ion (Li-ion) battery. Understanding the Li-ion diffusion mechanism within possible components in the mosaic-structured SEI is an essential step to improve the Li-ion conductivity and thus the battery performance. Here, we investigate the Li-ion diffusion mechanism within three amorphous SEI components (i.e., the inorganic inner layer, organic outer layer, and their mixture with 1:1 molar ratio) via ab initio molecular dynamic (AIMD) simulations. Our simulations show that the Li-ion diffusion coefficient in the inorganic layer is two orders of magnitude faster than that in the organic layer. Therefore, the inorganic layer makes a major contribution to the Li-ion diffusion. Furthermore, we find that the Li-ion diffusivity in the organic layer decreases slightly with the increase of the carbon chain from the methyl to ethyl owing to the steric hindrance induced by large groups. Overall, our current work unravels the Li-ion diffusion mechanism, and provides an atomic-scale insight for the understanding of the Li-ion transport in the SEI components.
Identification of lymph nodes (LNs) is critical for studies of the structure, the role in disease development, and the efficacy of disease treatment. Carbonized polymer dots (CPDs) are expected to be potential LNs-targeted imaging agents due to their excellent properties with special structure, better photoluminescence (PL) and great biocompatibility. Herein, a red/near infrared (NIR) emission CPDs (RCPDs) with one and two-photon bioimaging based on citric acid (CA) and benzoylurea (BU) are prepared. Notably, the RCPDs are capable of targeting LNs for imaging. Lymphocyte homing has been demonstrated to be the cellular mechanism of RCPDs target LNs imaging. This work has developed a new nanomaterial for targeted imaging of LNs, while the biological applications of CPDs have been expanded and deepened.
On-tissue chemical derivatization (OTCD) effectively enhances ionization efficiency of low abundant and poorly ionized functional molecules to improve detection sensitivity and coverage of mass spectrometry imaging (MSI). Combination OTCD and MSI provides a novel strategy for visualizing previously undisclosed metabolic heterogeneity in tumor. Herein, we present a method to visualize heterogeneous metabolism of oxylipins within tumor by coupling OTCD with airflow-assisted desorption electrospray ionization (AFADESI)-MSI. Taking Girard's P as a derivatization reagent, easily ionized hydrazide and quaternary amine groups were introduced into the structure of carbonyl metabolites via condensation reaction. Oxylipins, including 127 fatty aldehydes (FALs) and 71 oxo fatty acids (FAs), were detected and imaged in esophageal cancer xenograft with AFADESI-MSI after OTCD. Then t-distributed stochastic neighbor embedding and random forest were exploited to precisely locate the distribution of oxylipins in heterogeneous tumor tissue. With this method, we surprisingly found almost all FALs and oxo FAs significantly accumulated in the core region of tumor, and exhibited a gradual increase trend in tumor over time. These results reveal spatiotemporal heterogeneity of oxylipins in tumor progression, highlighting the value of OTCD combined with MSI to gain deeper insights into understanding tumor metabolism.
Highly selective conversion of methane (CH4) to methanol (CH3OH) is an emerging attractive but challenging process for future development of hydrogen economy, which requires efficient catalysts. Herein, we systematically explore the catalytic properties of Pt(111) overlayer on transition metal oxides (TMOs) for CH4 conversion by first principles calculations. The Pt(111) monolayer supported by Ce-terminated CeO2(111) substrate exhibits high activity and selectivity for CH4 conversion to CH3OH, with the kinetic barrier of rate-limiting step of 1.05 eV. Intriguingly, the surface activity of Pt overlayer is governed by its d-band center relative to the energy of bonding states of adsorbed molecules, which in turn depends on the number of charge transfer between Pt(111) monolayer and underlying TMOs substrates. These results provide useful insights in the design of metal overlayers as catalysts with high-ultra performance and atomic utilization.
3D microgels with various mechanical properties have been important platforms tumor metastasis analysis, and widely adjustable stiffness is crucial for deeper researches. Herein, by mixing biodegradable polylactic acid (PLA) nanofibers in the modified alginate with different concentrations of Ca2+, we significantly enhance the stiffness range of microgels while retaining the pore size, which provides bionic microenvironment for tumor analysis. As a proof of concept, we simulated the mechanical characteristics of breast tumors by encapsulating cells in 3D microgels with diverse stiffness, and analyzed cellular behaviors of two typical breast cancer cell lines: MCF-7 and SUM-159. Results showed that with the addition of 2.0% (w/v) PLA short nanofibers, the Young's modulus of modified alginate increased more than three-fold. Besides preserving high survival and proliferation rates, both cells also displayed stronger migration ability in soft microgel spheres, where RT-qPCR analysis revealed the underlying changes at the genetic level. This systematic study demonstrated our method is powerful for creating widely adjustable 3D mechanical microenvironment, and the results of cellular behavior analysis shows its promising application prospects in tumorigenesis and progression.
While superhydrophobic coatings have shown promise as potential anti-icing coatings, the surface roughness of these coatings is prone to damage during repeated icing-deicing cycles. Herein, two kinds of superhydrophobic anti-icing coatings are prepared from organic resin and micro-nano particles using two strategies, and their excellent anti-icing properties are also investigated. However, superhydrophobic surface Ⅰ (SF1), prepared by first strategy, cannot be used for extended periods of time due to irreversible damage to the surface roughness during the icing–deicing process. Finite element simulations and experimental studies are preformed to investigate the fatal issue of such roughness damage. In contrast, the anti-icing properties of superhydrophobic surface Ⅱ (SF2), prepared by second strategy, can easily regain through a simple sandpaper abrasion treatment even the surface roughness was damaged during the icing–deicing process. These exploratory results and SF2 preparation strategy provide a facile design of anti-icing coating, and the derived restorable anti-icing coating is expected to be useful for a wide application.
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