Mechanistic formulation of inorganic membranes at the air-liquid interface.

Freestanding functional inorganic membranes, beyond the limits of their organic and polymeric counterparts1, may unlock the potentials of advanced separation2, catalysis3, sensors4,5, memories6, optical filtering7 and ionic conductors8,9. However, the brittle nature of most inorganic materials, and the lack of surface unsaturated linkages10, mean that it is difficult to form continuous membranes through conventional top-down mouldings and/or bottom-up syntheses11. Up to now, only a few specific inorganic membranes have been fabricated from predeposited films by selective removal of sacrificial substrates4-6,8,9. Here we demonstrate a strategy to switch nucleation preferences in aqueous systems of inorganic precursors, resulting in the formation of various ultrathin inorganic membranes at the air-liquid interface. Mechanistic study shows that membrane growth depends on the kinematic evolution of floating building blocks, which helps to derive the phase diagram based on geometrical connectivity. This insight provides general synthetic guidance towards any unexplored membranes, as well as the principle of tuning membrane thickness and through-hole parameters. Beyond understanding  a complex dynamic system, this study comprehensively expands the traditional notion of membranes in terms of composition, structure and functionality.

Modularly Integrated System for Spatiotemporally Separated Solar Energy Storage and Release.

The sun is regarded as an endless source of clean energy. However, the intermittent supply and dynamically changeable demand of solar energy, as well as its uneven regional distribution, have been continually motivating the technological research of practical strategies to realize the spatiotemporally separated solar energy harvest and utilization. Accordingly, we here developed an integrated system for efficient solar energy capture, stable storage, and on-demand release, which corresponds to the intricate design of three distinct modules, namely, a photothermal conversion module, a latent heat storage module, and a mechanical trigger module. Moreover, efficient heat transfer and long-term supercooled stability necessitate interfacial passivation to coordinate the physical coupling of different modules. In addition to providing an integrated prototype that demonstrates a closed energy cycle in practice, this study may further inspire a new paradigm for advanced solar utilization in both theory and methodology.

Bibliometrics and visualization analysis regarding research on the development of microplastics.

Microplastics have caused considerable harm to the environment and threatened human health due to their strong adsorption and hard biodegradation. Therefore, the research of microplastic received increasing attention recently, producing numbers of related achievements. To comprehensively grasp the quantitative information of published papers on "microplastics," we analyzed the research progress and hotspots of "microplastics" through visualization software "VOSviewer." The results show that the number of literature on microplastics published from 2009 to 2019 increased exponentially (R2 = 0.9873). The top 10 cited references are mainly in "zooplankton ingesting microplastics," "microplastics in artificially cultivated bivalve," "microplastics in surface waters such as lakes," etc. The cutting-edge microplastics research is adsorption, biodegradation, ingestion and accumulation model, and toxicity analysis. In addition, the results predict that the combination of constructed wetland, biotechnology, and photocatalysis to remove microplastics will become new hotspots. The study provides researchers in microplastics with an overview of existing research and directional guidance for future research.

[3D Porous Photothermal Materials for High Salt Wastewater Treatment].

The treatment of high salinity wastewater is complex with high cost and energy consumption. Interfacial solar vapor generation technology because of its green, high efficiency and low energy consumption has become a hot spot in the field of water resource recovery and utilization. In this study, a novel three-dimensional porous graphene composite material (3D h-CN/r-GO) was designed by a hydrothermal reaction with fibrous carbon nitrogen (h-CN) modified graphene (r-GO), and its performance for adsorption of nitrobenzene and phenol as simulated contaminants via photothermal evaporation was studied. The results showed that 3D h-CN/r-GO has a broad-spectrum absorption and multistage channel structure and presents the characteristics of fast thermal response. Its light steam conversion efficiency can reach 90.4% under the condition of simulated sunlight. The adsorption of nitrobenzene, phenol, and other common volatile pollutants can be realized in the process of treatment, and its adsorption capacities of nitrobenzene and phenol were 67.6 mg·g-1 and 57.5 mg·g-1, respectively. Moreover, 3D h-CN/r-GO can realize efficient interfacial solar vapor generation with long-time stability, and its retention rate of pollutants and salts is up to 98%. The recovery and utilization of steam condensate meets the discharge standard. Therefore, this study provides a promising way for the treatment of high salinity wastewater with low energy consumption and cost.

Quantitative study on the fate of antibiotic emissions in China.

China, the largest producer and user of antibiotics in the world, discharges excessive amounts of these substances into the environment, without prior treatment. This results in ubiquitous distribution of these substances, as well as increased levels of drug-resistant bacteria, that will eventually cause unimaginable consequences to the environment and to humans. However, most of the research on antibiotics has focused on residue analysis of single medium such as wastewater and landfills. There is paucity of research that systematically investigates the fate of antibiotics after excretion, and specifically of end-treatment processes. In this paper, the fate of antibiotic emissions is systematically calculated. The results show that human and livestock feces account for 57.6% and 42.6% of the discharge of medicinal antibiotics and veterinary antibiotics, respectively. Of these feces types, pig feces accounted for 98.7% of antibiotic residues in livestock feces. The above conclusions can be used to clarify the direction of the tracking and supervision of antibiotic residues and provide new ideas for the treatment of antibiotics, especially their terminal removal.

Continuous hydrogen production from food waste by anaerobic digestion (AD) coupled single-chamber microbial electrolysis cell (MEC) under negative pressure.

Increased generation of food waste (FW) poses significant risks to the social environment, and therefore it is critical that efficient technology be developed for effective waste valorization. This study used an integrated reactor to combine single-chamber microbial electrolysis cell (MEC) treatment and anaerobic digestion (AD) to achieve efficient hydrogen recovery using FW as substrate. Hydrogen production during continuous AD-MEC operation (511.02 ml H2 g-1 VS) was higher than that achieved by AD (49.39 ml H2 g-1 VS). The hydrogen recovery and electrical energy recovery in AD-MEC were as high as 96% and 238.7 ± 5.8%, respectively. To explore the mechanism of hydrogen production increase, the main components of FW [lipids, volatile fatty acids (VFAs), carbohydrates, and protein] were analyzed to investigate the utilization of organic matter. Compared with AD treatment, the removal rates of carbohydrates and proteins in the soluble phase in AD-MEC were increased by 4 times and 2.3 times, respectively. The removal of VFAs by AD-MEC was increased by 4.7 times, which indicated that the AD reactor coupled with MEC technology improved the utilization of the main organic components and thus increased hydrogen production. This study demonstrates the possibilities of reducing FW quantities along with the production of bio-hydrogen.

Toward Efficient Preconcentrating Photocatalysis: 3D g-C3N4 Monolith with Isotype Heterojunctions Assembled from Hybrid 1D and 2D Nanoblocks.

The macroscopic integration of the microscopic catalyst is one of the most promising strategies for photocatalytic technology in facing practical applications. However, in addition to the unsatisfactory photoactivated exciton separation, a new problem restricting the catalytic efficiency is the unmatched kinetics between the reactant diffusion and the photochemical reaction. Here, we report an isotype heterojunctional three-dimensional g-C3N4 monolith which is assembled from the hybrid building blocks of the nanowires and nanosheets. Benefiting from its hierarchically porous network and abundant heterojunctions, this catalytic system exhibits inherently promoted efficiency in light absorption and exciton separation, thus leading to a desirably improved photocatalytic performance. Furthermore, thanks to the structural and functional advantages of the constructed g-C3N4 monolith, a novel strategy of preconcentrating photocatalysis featuring the successive filtration, adsorption, and photocatalysis has been further developed, which could technically coordinate the kinetic differences and result in over-ten-time enhancement on the efficiency compared with the traditional photocatalytic system. Beyond providing new insights into the structural design and innovative application of the monolithic photocatalyst, this work may further open up novel technological revolutions in sewage treatment, air purification, microbial control, etc.

Cryogenic Exfoliation of Non-layered Magnesium into Two-Dimensional Crystals.

Physical exfoliation of layered precursors is one of the most prevailing techniques to prepare two-dimensional (2D) crystals, which, however, is considered to be intrinsically inapplicable to non-layered bulks. Now, plane cleavage differentiation is identified in metallic magnesium at cryogenic temperature (CT), and a cryogenic exfoliation strategy of non-layered magnesium into 2D crystals is developed. The cleavage anisotropy of the Mg lattice in response to the external mechanical stress originates from the CT-induced specific inactivation of basal slip, which results in the basal cleavage perpendicular to c axis. The exfoliated novel 2D Mg crystals exhibit remarkable localized surface plasmon resonances, holding great promise for the applications in harvesting and converting solar energy. Beyond creating a new member for the burgeoning 2D family, this study may provide a useful tool for the physical exfoliations of various non-layered materials.

Validation of effective roles of non-electroactive microbes on recalcitrant contaminant degradation in bioelectrochemical systems.

Bioelectrochemical systems (BESs) have been widely investigated for recalcitrant waste treatment mainly because of their waste removal effectiveness. Electroactive microbes (EMs) have long been thought to contribute to the high effectiveness by interacting with electrodes via electron chains. However, this work demonstrated the dispensable role of EMs for enhanced recalcitrant contamination degradation in BESs. We revealed enhanced p-fluoronitrobenzene (p-FNB) degradation in a BES by observing a defluorination efficiency that was three times higher than that in biodegradation or electrochemical processes. Such an improvement was achieved by the collaborative roles of electrode biofilms and planktonic microbes, as their individual contributions to p-FNB degradation were found to be similarly stimulated by electricity. However, no bioelectrochemical activity was found in either the electrode biofilms or the planktonic microbes during stimulated p-FNB degradation; because no biocatalytically reductive or oxidative turnovers were observed on cyclic voltammetry curves. The non-involvement of EMs was further proven by the similar microbial community evolution for biofilms and planktonic microbes. In summary, we proposed a mechanism for indirect electrical stimulation of microbial metabolism by electrochemically generating the active mediator p-fluoroaniline (p-FA) and further degradation by a sequential combination of electrochemical p-FNB reduction and biological p-FA oxidation by non-EMs.

Sustainable synthesis of novel carbon microwires for the modification of a Ti mesh anode in bioelectrochemical systems.

Herein, an effective method was developed to integrate carbon microwires on Ti mesh (denoted as CM/TiM) to fabricate high-performance anodes with long-time stability in microbial fuel cell. CM/TiM was synthesized by colonizing filamentous fungi on the bread modified Ti mesh followed by carbonization, which could convert the attached mycelium into carbon microwires (denoted as CM). Benefiting from the biocompatibility and 3D interlaced structure of carbon microwires, the biomass accumulation (1027 ±â€¯83 µg cm-2) of CM/TiM have been significantly improved nearly 3 folds, thus the fabricated CM/TiM demonstrated 2-fold higher current density (12.19 ±â€¯0.07 A m-2) with significantly increased stability compared with TiM. Therefore, the present high power output, chemical stability and hydrophilic carbon microwires make CM/TiM stable, scalable and environmentally sustainable anodes in bioelectrochemical systems.

Sewage sludge-derived carbon-doped manganese as efficient cathode catalysts in microbial fuel cells.

Searching for efficient and inexpensive catalysts to replace precious metal-based catalyst in air-cathode microbial fuel cells is crucial for the practical application and commercialization in wastewater treatment and energy generation. Here, through a simple pyrolysis process, sewage sludge could be converted into carbon material with hierarchically porous structure, which demonstrates oxygen reduction reaction (ORR) catalytic performance. Subsequently, co-doping Mn and N species on the carbonized sewage sludge matrix could further improve the ORR catalytic performance, which even demonstrates comparable performance to the commercial expensive Pt/C catalyst in air-cathode microbial fuels cells (MFC). The highest maximum power density of MFC with Mn-N/SC air-cathode is as high as 1,120 mW m-2, which is similar to the power density of the air-cathode MFC equipped commercialized Pt/C catalyst (1,240 mW m-2). Considering the simple operation, significant cost-saving and easy scale-up of the proposed 'trash-to-treasure' method, it is promising to convert harmful sewage sludge into efficient non-platinum cathode catalysts in microbial fuel cells.

Surface Nonpolarization of g-C3 N4 by Decoration with Sensitized Quantum Dots for Improved CO2 Photoreduction.

Photocatalytic conversion of CO2 can provide a solution for simultaneously addressing global warming and solar fuel generation. However, its applicability is presently limited by the unsatisfactory photoconversion efficiency of the state-of-art photocatalysts. In this regard, enhancing CO2 adsorption through surface modification could be an efficient way to improve the photoconversion efficiency. Herein, doping of nonpolar carbon quantum dots (CQDs) onto g-C3 N4 is reported for the construction of a metal-free heterojunction photocatalyst (CQDs/g-C3 N4 ). CQDs offer several advantages such as band-gap reduction and electron-withdrawing effect to improve light absorption and photocarrier separation efficiency. However, this study reveals that nonpolar CQDs could also improve CO2 adsorption, photoinduced H2 production, reaction kinetics, and alter CO2 photoreduction pathways to generate CH4 . Consequently, the CQDs/g-C3 N4 could generate six times more CO and CH4 without detectable H2 compared to pristine g-C3 N4 , under similar conditions. Therefore, this study demonstrates a promising strategy for efficient adsorption, activation, and subsequent photoreduction of CO2 by nonpolar surface modification of g-C3 N4 .

Capillary Effect-Enabled Water Electrolysis for Enhanced Electrochemical Ozone Production by Using Bulk Porous Electrode.

A significant overpotential necessary for the electrochemical oxygen evolution reaction (OER) is one of the most serious disadvantages in water electrolysis, which, on the contrary, gives the probability to electrochemically produce ozone alternative to the common corona discharge. To effectively suppress the competitive OER and improve gaseous ozone escaping, here we present a capillary effect-enabled electrolysis strategy by employing an unusual partial-submersed mode of anode composed of a ß-PbO2 cuboids-loaded bulk porous Pb, and realize a much enhanced electrocatalytic gaseous ozone production in comparison to the cases of solid Pb counterpart and/or usual submersion operation. Detailed study reveals a capillary pressure-induced "molecular oxygen-locking effect" in the electrolyte fully filled in the porous structure of the electrode area above the electrolyte pool level, which unexpectedly leads to the production of unusual ·O3- intermediate. Distinctive from the traditional electrochemical ozone production (EOP) mechanism dependent on the essential reaction between the atomic oxygen and molecular oxygen, the ·O3- intermediate generation favors the EOP process in the special case where the capillary action is relevant for a porous bulk anode.

Isotopic evidence for anthropogenic impacts on aquatic food web dynamics and mercury cycling in a subtropical wetland ecosystem in the US.

Quantifying and predicting the food web consequences of anthropogenic changes is difficult using traditional methods (based on gut content analysis) because natural food webs are variable and complex. Here, stable and radioactive carbon isotopes are used, in conjunction with nitrogen isotopes and mercury (Hg) concentration data, to document the effects of land-use change on food webs and Hg bioaccumulation in the Everglades - a subtropical wetland ecosystem in the US. Isotopic signatures of largemouth bass and sunfish in reference (relatively pristine) wetlands indicate reliance on the food supply of modern primary production within the wetland. In contrast, both fish in areas impacted by agricultural runoff had radiocarbon ages as old as 540 years B.P., and larger isotopic variability than counterparts in reference wetlands, reflecting differences in the food web between impacted and reference wetlands. Consistent with this difference, particulate and dissolved organic matter in impacted areas had old radiocarbon ages (>600 years B.P.), indicating that old carbon derived from historic peat deposits in the Everglades Agricultural Area was passed along the food chain to consumers. Significant radiocarbon deficiencies in largemouth bass and sunfish, relative to mosquitofish, in impacted areas most likely indicate a reduced dependence on small fish. Furthermore, largemouth bass and sunfish from impacted areas had much lower Hg contents than those from reference wetlands. Taken together, these data suggest a shift toward lower trophic levels and a possible reduction in mercury methylation in impacted wetlands. Our study provides clear evidence that hydrological modification and land-use change in the Everglades have changed the system from one driven primarily by in-situ productivity to one that is partially dependent on allochthonous carbon input from peat soils in the agricultural area and altered the Hg biogeochemical cycle in the wetlands. The results have implications for the restoration and management of wetland ecosystems.

Anti-inflammatory activity of myricetin isolated from Myrica rubra Sieb. et Zucc. leaves.

MYRICA RUBRA Sieb. et Zucc. leaves are commonly used in folk medicine to treat inflammatory disorders in China. Present studies on the anti-inflammatory effect of myricetin from MYRICA RUBRA Sieb. et Zucc. leaves was evaluated with various IN VIVO models of both acute and chronic inflammations such as xylene-induced ear edema, acetic acid-induced vascular permeability, carrageenan-induced paw edema, leukocyte migration assay, and cotton pellet granuloma models. Myricetin showed a significant inhibition on ear edema and hind paw edema caused by xylene and carrageenan, respectively. Furthermore, it also inhibited the increase in capillary permeability induced by the production of acetic acid in the human body. Myricetin significantly decreased the serum levels of MDA and, in turn, increased the serum levels of SOD in the carrageenan-induced paw edema model. Concurrently, myricetin also significantly decreased leukocyte count. During chronic inflammation, myricetin inhibited the formation of granuloma tissue. These results, collectively, demonstrate that myricetin possesses a potent anti-inflammatory function on acute and chronic inflammation. Its anti-inflammatory mechanisms are probably associated with the inhibition of antioxidant activity. These results also support the claims of traditional Chinese medicine practitioners about the use of MYRICA RUBRA Sieb. et Zucc. leaves in the treatment of inflammatory diseases.

Bisurfactant-controlled synthesis of three-dimensional YBO3/Eu3+ architectures with tunable wettability.

Three-dimensional (3D) architectures of YBO(3)/Eu(3+) with different morphologies such as nest-like, rose-like, cruller-like, and flower-like, were hydrothermally synthesized by simply adjusting the ratios of surfactant polyethylene glycol-6000 (PEG-6000) to octadecylamine (ODA). These 3D architectures were all self-assembled by nanoflakes. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) spectra were used to characterize the morphology and structures of the samples. PEG-6000, ODA, and the ODA/PEG ratio played important roles in the formation process of various architectures. Rose-like architecture was chosen as a candidate, and the formation mechanism of the architecture was proposed on the basis of XRD analysis and SEM observation of the products at different reaction periods of time. As-synthesized samples displayed strong emission located at 591, 610, and 615 nm. Water contact angle measurements indicated that the films fabricated by the samples obtained under the different ratios of PEG-6000/ODA could exhibit tunable wettability ranging from superhydrophilicity to superhydrophobicity. This kind of one-pot bisurfactant-controlled hydrothermal synthesis method reported here provides a new strategy to realize the surfaces of functional materials with tunable wettability.