Lanzhou University of Technology

The extensive use of antibiotics leading to the rapid spread of antibiotic resistance poses high health risks to humans, but to date there is still lack of a quantitative model to properly assess the risks. Concerns over the health risk of antibiotic residues in the environment are mainly (1) the potential hazard of ingested antibiotic residues in the environment altering the human microbiome and promoting emergence and selection for bacteria resistance inhabiting the human body, and (2) the potential hazard of creating a selection pressure on environmental microbiome and leading to reservoirs of antibiotic resistance in the environment. We provide a holistic view of health risk assessment of antibiotic resistance associated with antibiotic residues in the environment in contrast with that of the antibiotic resistant bacteria and discuss the main knowledge gaps and the future research that should be prioritized to achieve the quantitative risk assessment. We examined and summarized the available data and information on the four core elements of antibiotic resistance associated with antibiotic residues in the environment: hazard identification, exposure assessment, dose-response assessment, and risk characterization. The data required to characterize the risks of antibiotic residues in the environment is severely limited. The main future research needs have been identified to enable better assessments of antibiotic resistance associated with antibiotic residues in the environment: (1) establishment of a standardized monitoring guide of antibiotic residues and antibiotic resistance in the environment, (2) derivation of the relationship between antibiotic levels and pathogenic antibiotic-resistance development in different settings, and (3) establishment of the dose-response relationship between pathogenic antibiotic resistant bacteria and various infection diseases. After identification of key risk determinant parameters, we propose a conceptual framework of human health risk assessments of antibiotic residues in the environment. CAPSULE: A holistic view of human health risk assessment of antibiotic residues in the environment was provided.

The proton exchange membrane (PEM) water electrolysis is one of the most promising hydrogen production techniques. The oxygen evolution reaction (OER) occurring at the anode dominates the overall efficiency. Developing active and robust electrocatalysts for OER in acid is a longstanding challenge for PEM water electrolyzers. Most catalysts show unsatisfied stability under strong acidic and oxidative conditions. Such a stability challenge also leads to difficulties for a better understanding of mechanisms. This review aims to provide the current progress on understanding of OER mechanisms in acid, analyze the promising strategies to enhance both activity and stability, and summarize the state-of-the-art catalysts for OER in acid. First, the prevailing OER mechanisms are reviewed to establish the physicochemical structure-activity relationships for guiding the design of highly efficient OER electrocatalysts in acid with stable performance. The reported approaches to improve the activity, from macroview to microview, are then discussed. To analyze the problem of instability, the key factors affecting catalyst stability are summarized and the surface reconstruction is discussed. Various noble-metal-based OER catalysts and the current progress of non-noble-metal-based catalysts are reviewed. Finally, the challenges and perspectives for the development of active and robust OER catalysts in acid are discussed.

Plants are constantly challenged by various abiotic stresses that negatively affect growth and productivity worldwide. During the course of their evolution, plants have developed sophisticated mechanisms to recognize external signals allowing them to respond appropriately to environmental conditions, although the degree of adjustability or tolerance to specific stresses differs from species to species. Overproduction of reactive oxygen species (ROS; hydrogen peroxide, H2O2; superoxide, [Formula: see text]; hydroxyl radical, OH(⋅) and singlet oxygen, (1)O2) is enhanced under abiotic and/or biotic stresses, which can cause oxidative damage to plant macromolecules and cell structures, leading to inhibition of plant growth and development, or to death. Among the various ROS, freely diffusible and relatively long-lived H2O2 acts as a central player in stress signal transduction pathways. These pathways can then activate multiple acclamatory responses that reinforce resistance to various abiotic and biotic stressors. To utilize H2O2 as a signaling molecule, non-toxic levels must be maintained in a delicate balancing act between H2O2 production and scavenging. Several recent studies have demonstrated that the H2O2-priming can enhance abiotic stress tolerance by modulating ROS detoxification and by regulating multiple stress-responsive pathways and gene expression. Despite the importance of the H2O2-priming, little is known about how this process improves the tolerance of plants to stress. Understanding the mechanisms of H2O2-priming-induced abiotic stress tolerance will be valuable for identifying biotechnological strategies to improve abiotic stress tolerance in crop plants. This review is an overview of our current knowledge of the possible mechanisms associated with H2O2-induced abiotic oxidative stress tolerance in plants, with special reference to antioxidant metabolism.

Avoiding wound infection and retaining an appropriate level of moisture around woundz are major challenges in wound care management. Therefore, designing hydrogels with desired antibacterial performance and good water‐maintaining ability is of particular significance to promote the development of wound dressing. Thus a series of hydrogels are prepared by crosslinking of Ag/graphene composites with acrylic acid and N , N ′‐methylene bisacrylamide at different mass ratios. The antibacterial performance and accelerated wound‐healing ability of hydrogel are systematically evaluated with the aim of attaining a novel and effective wound dressing. The as‐prepared hydrogel with the optimal Ag to graphene mass ratio of 5:1 (Ag5G1) exhibits stronger antibacterial abilities than other hydrogels. Meanwhile, Ag5G1 hydrogel exhibits excellent biocompatibility, high swelling ratio, and good extensibility. More importantly, in vivo experiments indicate that Ag5G1 hydrogel can significantly accelerate the healing rate of artificial wounds in rats, and histological examination reveals that it helps to successfully reconstruct intact and thickened epidermis during 15 day of healing of impaired wounds. In one word, the present approach can shed new light on designing of antibacterial material like Ag/graphene composite hydrogel with promising applications in wound dressing.

Abstract Photoelectrochemical (PEC) water splitting is a promising method for storing solar energy in the form of hydrogen fuel, but it is greatly hindered by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, a facile solution impregnation method is developed for growing ultrathin (2 nm) highly crystalline β‐FeOOH nanolayers with abundant oxygen vacancies on BiVO 4 photoanodes. These exhibited a remarkable photocurrent density of 4.3 mA cm −2 at 1.23 V (vs. reversible hydrogen electrode (RHE), AM 1.5 G), which is approximately two times higher than that of amorphous FeOOH fabricated by electrodeposition. Systematic studies reveal that the excellent PEC activity should be attributed to their ultrathin crystalline structure and abundant oxygen vacancies, which could effectively facilitate the hole transport/trapping and provide more active sites for water oxidation.

Abstract The development of highly active and stable oxygen evolution reaction (OER) electrocatalysts is crucial for improving the efficiency of water splitting and metal–air battery devices. Herein, an efficient strategy is demonstrated for making the oxygen vacancies dominated cobalt–nickel sulfide interface porous nanowires (NiS 2 /CoS 2 –O NWs) for boosting OER catalysis through in situ electrochemical reaction of NiS 2 /CoS 2 interface NWs. Because of the abundant oxygen vacancies and interface porous nanowires structure, they can catalyze the OER efficiently with a low overpotential of 235 mV at j = 10 mA cm −2 and remarkable long‐term stability in 1.0 m KOH. The home‐made rechargeable portable Zn–air batteries by using NiS 2 /CoS 2 –O NWs as the air–cathode display a very high open‐circuit voltage of 1.49 V, which can maintain for more than 30 h. Most importantly, a highly efficient self‐driven water splitting device is designed with NiS 2 /CoS 2 –O NWs as both anode and cathode, powered by two‐series‐connected NiS 2 /CoS 2 –O NWs‐based portable Zn–air batteries. The present work opens a new way for designing oxygen vacancies dominated interface nanowires as highly efficient multifunctional electrocatalysts for electrochemical reactions and renewable energy devices.

Superhydrophobic conjugated microporous polymers show good selectivity, fast adsorption kinetics, excellent recyclability and absorbencies for a wide range of organic solvents and oils, which make them the promising candidates for potential applications, including liquid–liquid separation, water treatment and so on.

All-solid-state, flexible, symmetric, and asymmetric microsupercapacitors are fabricated by a simple method in a scalable fashion from laser-induced graphene on commercial polyimide films, followed by electrodeposition of pseudocapacitive materials on the interdigitated in-plane architectures. These microsupercapacitors demonstrate comparable energy density to commercial lithium thin-film batteries, yet exhibit more than two orders of magnitude higher power density with good mechanical flexibility. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Abstract Nanometer-thick passive films on metals usually impart remarkable resistance to general corrosion but are susceptible to localized attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, several classic theories have been proposed and accepted, based on hypotheses and theoretical models, and oftentimes, not sufficiently nor directly corroborated by experimental evidence. Here we show experimental results on the structure of the passive film formed on a FeCr 15 Ni 15 single crystal in chloride-free and chloride-containing media. We use aberration-corrected transmission electron microscopy to directly capture the chloride ion accumulation at the metal/film interface, lattice expansion on the metal side, undulations at the interface, and structural inhomogeneity on the film side, most of which had previously been rejected by existing models. This work unmasks, at the atomic scale, the mechanism of chloride-induced passivity breakdown that is known to occur in various metallic materials.

In this work, α-MnO2 hollow spheres and hollow urchins are synthesized via a simple hydrothermal process without using any template or organic surfactant. The effect of the reaction time on the microstructure and morphology of samples is observed systemically. Meanwhile, the forming mechanism of hollow-structured α-MnO2 is carefully investigated by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The results of nitrogen adsorption−desorption experiments and electrochemical measurements show that the product obtained by hydrothermal reaction for 6 h has large specific surface area, uniform pore-size distribution, and excellent capacitance performance, which make it have a potential application as a supercapacitor electrode material.

Abstract Developing bifunctional efficient electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is in high demand for the development of overall water‐splitting devices. In particular, the electrocatalytic performance can be largely improved by designing positive nanoscale‐heterojunction with well‐tuned interfaces. Herein, a novel top‐down strategy is reported to construct the oxide/sulfide heterostructures (N‐NiMoO 4 /NiS 2 nanowires/nanosheets) as a multisite HER/OER catalyst. Starting with the NiMoO 4 nanowires, nitridation in a controlled manner enables activation of Ni sites in NiMoO 4 and then yields oxide/sulfide heterojunction by directly vulcanizing the highly composition‐segregated N‐NiMoO 4 nanowires. The abundant epitaxial heterogeneous interfaces at atomic‐level facilitate the electron transfer from N‐NiMoO 4 to NiS 2 , which further cooperate synergistically toward both the hydrogen and oxygen generation in alkali solution. Furthermore, with N‐NiMoO 4 /NiS 2 grown carbon fiber cloth as the engineering electrode, the assembled N‐NiMoO 4 /NiS 2 –N‐NiMoO 4 /NiS 2 system can deliver a current density of 10 mA cm −2 with the cell voltage of 1.60 V in the water‐splitting reaction. This current density is 3.39 times higher than that of the Pt–Ir set (2.95 mA cm −2 ). The excellent catalytic performance offered of N‐NiMoO 4 /NiS 2 nanowires/nanosheets presents a great example to demonstrate the significance of interface engineering in the field of electrocatalysis.

Abstract Solar steam generation has been proven to be one of the most efficient approaches for harvesting solar energy for diverse applications such as distillation, desalination, and production of freshwater. Here, the synthesis of monolithic carbon aerogels by facile carbonization of conjugated microporous polymer nanotubes as efficient solar steam generators is reported. The monolithic carbon‐aerogel networks consist of randomly aggregated hollow‐carbon‐nanotubes (HCNTs) with 100–250 nm in diameter and a length of up to several micrometers to form a hierarchically nanoporous network structure. Treatment of the HCNTs aerogels with an ammonium peroxydisulfate/sulfuric acid solution endows their superhydrophilic wettability which is beneficial for rapid transportation of water molecules. In combination with their abundant porosity (92%) with open channel structure, low apparent density (57 mg cm −3 ), high specific surface area (826 m 2 g −1 ), low thermal conductivity (0.192 W m −1 K −1 ), and broad light absorption (99%), an exceptionally high conversion efficiency of 86.8% is achieved under 1 sun irradiation, showing great potential as an efficient photothermal material for solar steam generation. The findings may provide a new opportunity for tailored design and creation of new carbon‐aerogels‐based photothermal materials with adjustable structure, tunable porosity, simple fabrication process, and high solar energy conversion efficiency for solar steam generation.

Abstract Transition‐metal sulfides (TMSs) have emerged as important candidates for oxygen evolution reaction (OER) electrocatalysts. Now a hybrid nanostructure has been decorated with CeO x nanoparticles on the surface of ZIF‐67‐derived hollow CoS through in situ generation. Proper control of the amount of CeO x on the surface of CoS can achieve precise tuning of Co 2+ /Co 3+ ratio, especially for the induced defects, further boosting the OER activity. Meanwhile, the formation of protective CeO x thin layer effectively inhibits the corrosion by losing cobalt ion species from the active surface into the solution. It is thus a rare example of a hybrid hetero‐structural electrocatalyst with CeO x NPs to improve the performance of the hollow TMS nanocage.

Abstract Involving eight electron transfer process and multiple intermediates of nitrate (NO 3 − ) reduction reaction leads to a sluggish kinetic and low Faradaic efficiency, therefore, it is essential to get an insight into the reaction mechanism to develop highly efficient electrocatalyst. Herein, a series of reduced‐graphene‐oxide‐supported RuCu alloy catalysts (Ru x Cu x /rGO) are fabricated and used for the direct reduction of NO 3 − to NH 3 . It is found that the Ru 1 Cu 10 /rGO shows the ammonia formation rate of 0.38 mmol cm −2 h −1 (loading 1 mg cm −2 ) and the ammonia Faradaic efficiency of 98% under an ultralow potential of −0.05 V versus Reversible Hydrogen Electode (RHE), which is comparable to Ru catalyst. The highly efficient activity of Ru 1 Cu 10 /rGO can be attributed to the synergetic effect between Ru and Cu sites via a relay catalysis, in which the Cu shows the exclusively efficient activity for the reduction of NO 3 − to NO 2 − and Ru exhibits the superior activity for NO 2 − to NH 3 . In addition, the doping of Ru into Cu tunes the d‐band center of alloy and effectively modulates the adsorption energy of the NO 3 − and NO 2 − , which promotes the direct reduction of NO 3 − to NH 3 . This synergetic electrocatalysis strategy opens a new avenue for developing highly efficient multifunctional catalysts.

An “acetonitrile/water in salt” electrolyte with non-flammability, high conductivity, a high stability window and a wide applicable temperature range enables high-performance supercapacitors.

Abstract Ionogels offer great potential for diverse electric applications. However, it remains challenging to fabricate high‐performance ionogels with both good mechanical strength and high conductivity. Here, a new kind of transparent ionogel with both good mechanical strength and high conductivity is designed via locking a kind of free ionic liquid (IL), i.e., 1‐ethyl‐3‐methylimidazolium dicyanamide ([EMIm][DCA]), into charged poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PAMPS)‐based double networks. On the one hand, the charged PAMPS double network provides good mechanical strength and excellent recovery property. On the other hand, the free [EMIm][DCA] locked in the charged double network through electrostatic interaction offers ionic conductivity as high as ≈1.7–2.4 S m −1 at 25 °C. It is demonstrated that the designed ionogel can be successfully used for a flexible skin sensor even under harsh conditions. Considering the rationally designed chemical structures of ILs and the diversity of charged polymer networks, it is envisioned that this strategy can be extended to a broad range of polymer systems. Moreover, functional components such as conducting polymers, 0D nanoparticles, 1D nanowires, and 2D nanosheets can be introduced into the polymer systems to fabricate diverse novel ionogels with unique functions. It is believed that this design principle will provide a new opportunity to construct next‐generation multifunctional ionogels.

Supercapacitors, also known as electrochemical capacitors, have attracted more and more attention in recent decades due to their advantages of higher power density and long cycle life.

Abstract Thermal barrier coatings (TBCs) can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat. However, the continuous pursuit of a higher operating temperature leads to degradation, delamination, and premature failure of the top coat. Both new ceramic materials and new coating structures must be developed to meet the demand for future advanced TBC systems. In this paper, the latest progress of some new ceramic materials is first reviewed. Then, a comprehensive spalling mechanism of the ceramic top coat is summarized to understand the dependence of lifetime on various factors such as oxidation scale growth, ceramic sintering, erosion, and calcium-magnesium-aluminium-silicate (CMAS) molten salt corrosion. Finally, new structural design methods for high-performance TBCs are discussed from the perspectives of lamellar, columnar, and nanostructure inclusions. The latest developments of ceramic top coat will be presented in terms of material selection, structural design, and failure mechanism, and the comprehensive guidance will be provided for the development of next-generation advanced TBCs with higher temperature resistance, better thermal insulation, and longer lifetime.

The nickel oxide nano-flakes materials prepared by a facile approach maintain high power density at high rates of discharge and have excellent cycle life, suggesting their potential application in supercapacitors.

The key to solving fine-grained image categorization is finding discriminate and local regions that correspond to subtle visual traits. Great strides have been made, with complex networks designed specifically to learn part-level discriminate feature representations. In this paper, we show that it is possible to cultivate subtle details without the need for overly complicated network designs or training mechanisms - a single loss is all it takes. The main trick lies with how we delve into individual feature channels early on, as opposed to the convention of starting from a consolidated feature map. The proposed loss function, termed as mutual-channel loss (MC-Loss), consists of two channel-specific components: a discriminality component and a diversity component. The discriminality component forces all feature channels belonging to the same class to be discriminative, through a novel channel-wise attention mechanism. The diversity component additionally constraints channels so that they become mutually exclusive across the spatial dimension. The end result is therefore a set of feature channels, each of which reflects different locally discriminative regions for a specific class. The MC-Loss can be trained end-to-end, without the need for any bounding-box/part annotations, and yields highly discriminative regions during inference. Experimental results show our MC-Loss when implemented on top of common base networks can achieve state-of-the-art performance on all four fine-grained categorization datasets (CUB-Birds, FGVC-Aircraft, Flowers-102, and Stanford Cars). Ablative studies further demonstrate the superiority of the MC-Loss when compared with other recently proposed general-purpose losses for visual classification, on two different base networks.