Deciphering the antibiotic resistome and microbial community in municipal wastewater treatment plants at different elevations in eastern and western China.

Antibiotic resistance genes (ARGs) as emerging environmental contaminants pose severe global risks to public health and ecosystems. Municipal wastewater treatment plants (WWTPs) are crucial transmitters for the dissemination and propagation of ARGs into receiving water bodies via mobile genetic elements (MGEs). However, the comprehensive and deep deciphering of the diversity, abundance, and potential hosts of ARGs in two distinct altitudinal WWTPs is scarce. In this work, we revealed the elevational distribution characteristics of the resistance genes and microbial community of six WWTPs from two distinct geographical zones: a low-elevation (LE) region (Shandong, 10-22 m above sea level) and a high-elevation (HE) region (Gansu, 1,520-1,708 m above sea level). Significant elevational variations in the diversity and relative abundance of resistance genes were observed. Wastewater treatment could significantly reduce the concentrations of ARGs and MGEs by about 1-2 and 2-3 orders of magnitude, respectively. However, above 69.95% of resistance genes were enriched in effluent. In particular, 24 ARG subtype, 3 MGE subtypes, and 59 bacterial genera were persistent in all samples. More potential hosts for ARGs in LE region and more abundant human gut microbiota in HE region were identified. This work provides helpful information for controlling the spread of ARGs for their management and assessment, thereby mitigating the risks of ARGs in WWTPs.

Cluster-derived TiO2 nanocrystals with multiple carbon coupling for interfacial pseudo-capacitive lithium storage.

TiO2 is one of the most promising anode materials for lithium ion batteries (LIBs) due to its safe working potentials and small volume changes during lithium insertion/extraction. However, its inherently poor electronic and ionic conductivities have restricted its practical applications. Herein, well-defined TiO2 nanocrystals were prepared from an atomically precise titanium-oxo cluster (Ti8Ph) and then coupled with carbon layers and graphene nanosheets. When used as anode materials for LIBs, the TiO2-C-rGO composite delivered a high capacity of 834 mA h g-1 at 0.1 A g-1 after 300 cycles and 398 mA h g-1 at 5.0 A g-1 after 600 cycles, which are far superior to those of the control samples (TiO2-C, TiO2-rGO and TiO2) and most other reported TiO2-based nanostructures. The exposed facets of TiO2 nanocrystals were favorable for lithium diffusion and the carbon coupling was beneficial for the electron transfer. The latter also enhanced the structural robustness and hence the cycling stability of the composite. Moreover, the abundant three-phase interfaces between the carbon species and the TiO2 nanocrystals endowed the material with rich adsorption sites and substantially boosted pseudo-capacitive lithium storage. This work offered an alternative route to rationally design versatile nanostructures from clusters and contributed to the development of high-efficiency energy materials.

Facet and d-band center engineering of CuNi nanocrystals for efficient nitrate electroreduction to ammonia.

Electrocatalytic nitrate reduction offers a sustainable route to ammonia synthesis and wastewater treatment. However, the nitrate-to-ammonia conversion remains inefficient due to the sluggish kinetics and diverse side reactions. Herein, well-faceted CuNi nanocrystals with Ni-rich surfaces and favorable d-band centres were synthesized with the assistance of γ-cyclodextrin via a solvothermal process. When used as catalysts for nitrate electroreduction, they delivered an ammonia yield of 1.374 mmol h-1 mg-1 (0.5496 mmol h-1 cm-2) at -0.3 V with the faradaic efficiency and selectivity reaching 94.5% and 65.0%, respectively, surpassing pure Cu or Ni nanocrystals and most reported catalysts. Such excellent performances originated from the optimal geometric and electronic structures and special element distribution, which optimized the adsorption behaviors and accelerated the reaction kinetics. A NO3--NO2--NH3 pathway was proposed with the chemical process following the initial electron transfer process as the rate-determining step. This work sheds light on the design of efficient catalysts to achieve carbon neutrality through simultaneous geometric and electronic structure modulation.

Elevating the p-band centre of SnO2 nanosheets through W incorporation for promoting CO2 electroreduction.

SnO2 is one of the most promising catalysts for CO2 electroreduction. However, the intrinsic low electrical conductivity and weak CO2 adsorption and activation capability have rendered the reaction kinetically sluggish and inefficient. To surmount these hurdles, herein, W was incorporated into SnO2 nanosheets to modulate the electronic structures. Compared with pristine SnO2, the p-band centre of W-doped SnO2 was elevated towards the Fermi level, accompanied by the reduction in the band gap and work function. As a result, both the CO2 adsorption and the electron transfer process were promoted, thus lowering the activation energy barrier for CO2 reduction. Benefitting from these, a maximum faradaic efficiency of 87.8% was achieved for HCOOH at -0.9 V vs. the RHE. Meanwhile, the current density and energy efficiency approached 20.92 mA cm-2 and 60%, respectively. Such performances could sustain for 14 h without obvious fading and exceeded pristine SnO2 and most reported Sn-based catalysts. Tafel slope and reaction order analyses further suggested that the reaction proceeded following a stepwise electron-proton transfer pathway with the formation of CO2˙- as the rate determining step. This work demonstrated the effectiveness of electronic structure tuning in promoting the catalytic performances of p-block metal oxides and contributed to the development of efficient catalysts for sustainable energy conversion and carbon neutrality.

Confining Chainmail-Bearing Ni Nanoparticles in N-doped Carbon Nanotubes for Robust and Efficient Electroreduction of CO2.

It still remains challenging to simultaneously achieve high stability, selectivity, and activity in CO2 reduction. Herein, a dual chainmail-bearing nickel-based catalyst (Ni@NC@NCNT) was fabricated via a solvothermal-evaporation-calcination approach. In situ encapsulated N-doped carbon layers (NCs) and nanotubes (NCNTs) gave a dual protection to the metallic core. The confined space well maintained the local alkaline pH value and suppressed hydrogen evolution. Large surface area and abundant pyridinic N and Niδ+ sites ensured high CO2 adsorption capacity and strength. Benefitting from these, it delivered a CO faradaic efficiency of 94.1 % and current density of 48.0 mA cm-2 at -0.75 and -1.10 V, respectively. Moreover, the performance remained unchanged after continuous electrolysis for 43 h, far exceeding Ni@NC with single chainmail, Ni@NC/NCNT with Ni@NC sitting on the walls of NCNT, bare NCNT and most state-of-the-art catalysts, demonstrating structural superiority of Ni@NC@NCNT. This work sheds light on designing unique architectures to improve electrochemical performances.

Numerical simulation of transport and adhesion of thermogenic nano-carriers in microvessels.

Externally triggered thermogenic nanoparticles (NPs) are potential drug carriers and heating agents for drug delivery and hyperthermia. A good understanding of the transport and adhesion behaviors of NPs in microvessels is conducive to improving the efficiency of NP-mediated treatment. Given the thermogenesis of NPs and interactions of NP-blood flow, NP-NP, NP-red blood cell (RBC) and ligand-receptor, the movement of NPs in blood flow was modeled using a hybrid immersed boundary and coupled double-distribution-function lattice Boltzmann method. Results show that the margination probability of NPs toward the vessel wall was evidently increased by NP thermogenesis owing to the noticeable variation in blood flow velocity distribution, thereby enhancing their adhesion to the target region. NP-RBC collision can promote NP movement to the acellular layer in microvessels to increase the NP adhesion rate. The number of adhered smaller NPs was larger than that of the larger NPs having the same ligand density due to the enhancement of Brownian force although their adhesion was relatively less firm. Compared with the NPs with a regular shape, the irregularly shaped NPs can adhere to the vessel wall more readily and strongly as a result of the higher turbulence levels caused by NP-blood flow interaction and relatively higher ligand density, which led to a higher rate of NP adhesion.

[Analysis of the Effect of Temperature on the Microbial Flora Structure During the Nitrite Oxidation Process Using 16S rRNA High-throughput Sequencing].

In order to further understand the influence of high temperature shock on the microbial community structure of activated sludge during the process of nitrite oxidation, the enriched nitrifying activated sludge under different NO2--N concentration was taken as the research object in this study. 16S rRNA high-throughput sequencing technology was used to analyze the changes in the microbial community abundance and structural characteristics of activated sludge by changing the environmental temperature. The results of high-throughput sequencing showed that microorganisms were more likely to grow at 25℃, and the diversity of the microbial community in the activated sludge was the most abundant. With increased temperature, the richness, evenness, and diversity of the flora in the system decreased. In addition, it was found that the main nitrifying bacterium in the system was Nitrospira of Nitrospirae, whereby 35℃ was more suitable for its growth. Meanwhile, a higher temperature also caused differences in the structure of non-nitrifying functional microorganisms (e.g., Bacteroidetes, Chlorofulexi, Halomonas, and Pseudomonas) in the activated sludge. The results of this study provide some theoretical reference for the investigation of the distribution characteristics of microbial flora during the process of nitrite oxidation under high temperature shock, and can also be used as reference for relevant high temperature shock tests.

Impact Behavior of Hydrophilic Micron Particles on a Planar Gas-Liquid Interface.

The behavior of hydrophilic micron particles impacting on the gas-liquid interface has been further experimentally studied using a high-speed camera at different surface tensions and dynamic viscosities of liquids. The results show that the impact behavior exhibits suspension and submergence modes, whose boundary cannot be clearly identified because the overlap between the impact velocity ranges occurs because of the unstable pinning of the three-phase contact line on the surface of hydrophilic particles. The liquid properties have little effect on the wettability of hydrophilic particles but greatly influence the hydrodynamic and capillary force exerted on the particles, leading to the expansion of the suspension mode range. In addition, the penetration probability changes little with the decrease in surface tension, while it significantly reduces with the increase in dynamic viscosity. A penetration probability model is predicted as an exponential function of the inertial and supporting forces, and the experimental values agree well with the predicted values. The outcomes of this research will be helpful for understanding the mechanism of particle-interface interaction and providing guidance for enhancing the separation of hydrophilic fine ash via a bubble scrubbing system.