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Biogenic amines (BAs), deriving from the microbial decarboxylation of free amino acids (FAAs) in fish products, have toxicological effects on human health. This study selected two Lactobacillus plantarum strains to reduce BAs accumulation in salted mackerel (Scomberomorus niphonius). Compared with BAs in spontaneously fermented salted S. niphonius , the concentration of BAs in samples inoculated with L. plantarum YC-5 and YC-6 strains decreased by 17.9% and 53.8%, while the histamine contents decreased by 96.9% and 86.5%, respectively. The histamine contents in samples inoculated with L. plantarum YC-5 were lower than the safety level during the entire process, although the precursor (histidine) was available at this stage. Then, the antibacterial activity of the L. plantarum strains was analyzed. The cell-free supernatant (CFS) of the L. plantarum reduced the biomass of the histamine-producing Morganella morganii and displayed stability at different pH and temperatures. Resequencing and bioinformatic analysis demonstrated that the L. plantarum strains contained plantaricin EF and JK encoding gene clusters. This study provided two promising LAB starters to reduce BAs accumulation in salted S. niphonius and elucidated their possible elimination mechanism of BAs, contributing to the safe production of salted fish. • L. plantarum YC-5 and YC-6 could effectively reduce BAs content in salted fish S. niphonius. • L. plantarum strains could inhibit the growth of the BAs-producing bacteria. • L. plantarum YC-5 and YC-6 contained plantaricin EF and JK encoding genes clusters. [ABSTRACT FROM AUTHOR]

A heterostructured Co-based electrocatalyst is successfully synthesized using bifunctional ligand Co metal–organic frameworks as precursors. The bifunctional ligands provide enough N and O atoms that can simultaneously convert Co ions into CoN x moieties, Co nanoparticles and Co oxides via one-step pyrolysis. The obtained electrocatalysts with heterostructured CoO x /Co nanoparticles encapsulated by porous conductive carbon rich in CoN x active sites deliver remarkable oxygen reduction reaction and oxygen evolution reaction activities. With the synergistic effects among these multifunctional components, a rechargeable zinc–air battery built with this electrocatalyst exhibits a high-power density and long-lasting rechargeability. [Display omitted] Rational construction of efficient and robust bifunctional oxygen electrocatalysts is key but challenging for the widespread application of rechargeable zinc-air batteries (ZABs). Herein, bifunctional ligand Co metal–organic frameworks were first explored to fabricate a hybrid of heterostructured CoO x /Co nanoparticles anchored on a carbon substrate rich in CoN x sites (CoO x /Co@Co N C) via a one-step pyrolysis method. Such a unique heterostructure provides abundant CoN x and CoO x /Co active sites to drive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively. Besides, their positive synergies facilitate electron transfer and optimize charge/mass transportation. Consequently, the obtained CoO x /Co@Co N C exhibits a superior ORR activity with a higher half-wave potential of 0.88 V than Pt/C (0.83 V vs. RHE), and a comparable OER performance with an overpotential of 346 mV at 10 mA cm−2 to the commercial RuO 2. The assembled ZAB using CoO x /Co@Co N C as a cathode catalyst displays a maximum power density of 168.4 mW cm−2, and excellent charge–discharge cyclability over 250 h at 5 mA cm−2. This work highlights the great potential of heterostructures in oxygen electrocatalysis and provides a new pathway for designing efficient bifunctional oxygen catalysts toward rechargeable ZABs. [ABSTRACT FROM AUTHOR]

Hollow O v -CeO 2 /CdS photocatalyst with atomic-level intimate interface has been synthesized via a defect-induced strategy and exhibits a high hydrogen production rate ∼12.6 mmol·g−1·h−1. [Display omitted] Construction of Z-scheme heterojunction catalysts with high-speed charge transfer channels for efficient photocatalytic hydrogen production from water splitting is still a challenge. In this work, a lattice-defect-induced atom migration strategy is proposed to construct an intimate interface. The oxygen vacancies of cubic CeO 2 obtained from a Cu 2 O template are used to induce lattice oxygen migration and form S O bonds with CdS to form a close contact heterojunction with a hollow cube. The hydrogen production efficiency reaches ∼12.6 mmol·g−1·h−1 and maintains a high value over 25 h. A series of photocatalytic tests combined with density functional theory (DFT) calculations show that the close contact heterostructure not only promotes the separation/transfer of photogenerated electron-hole pairs but also regulates the intrinsic catalytic activity of the surface. A large number of oxygen vacancies and S O bonds at the interface participate in charge transfer, which accelerates the migration of photogenerated carriers. The hollow structure improves the ability to capture visible light. Therefore, the synthesis strategy proposed in this work, as well as the in-depth discussion of the interface chemical structure and charge transfer mechanism, provides new theoretical support for the further development of photolytic hydrogen evolution catalysts. [ABSTRACT FROM AUTHOR]

Aspergillus flavus and the produced aflatoxins are common hazardous contaminants in grains and food, which generated great damage to food security and human health. Acetyl-CoA carboxylase (ACC), catalyzing acetyl-CoA to malonyl-CoA, is the first and speed-determining step in fatty acid biosynthesis (cell membrane composition) and aflatoxins biosynthesis process in A. flavus. Here, we demonstrated that dimethyl trisulfide (DMTS), emitted from bacteria, could interact with ACC, decrease the enzymatic activity from 377.62 to 191.42 kat/g in vitro , down-regulate the expression of ACC and other important genes in fatty acid and aflatoxin biosynthesis pathway, reduce the content of hexadecanoic acid, octadecanoic acid and eicosanoic acid, and finally prevent A. flavus growth and aflatoxins production. Two binding sites containing 19 amino acids were detected between DMTS and ACC through molecular docking analysis. These amino acids were highly conserved in different filamentous fungi, which accounted for the broad antifungal spectrum of DMTS. Therefore, we concluded that ACC is the molecular target of DMTS on A. flavus growth and aflatoxins production. These results elucidate the inhibitory mechanism of DMTS on fungal pathogens, and provide basic theories for the development of novel antifungal agents. [Display omitted] • Acetyl-CoA carboxylase (ACC) is key for A. flavus growth and aflatoxin production. • Dimethyl trisulfide (DMTS) reduced the ACC activity, down-regulated ACC expression. • DMTS significantly decreased the content of fatty acid and aflatoxin in A. flavus. • ACC is potential target of DMTS against A. flavus growth and aflatoxin production. [ABSTRACT FROM AUTHOR]

Compression and incorporated graphene significantly improve light transmittances and charge transport properties of an opaque and poor internal-connected mesoporous photoanode, as well as improve the PCE of the corresponding device. Semi-transparent TiO 2 /graphene photoanodes are prepared at room temperature via an electrophoretic deposition method followed by compression and applied in dye-sensitized solar cells (DSSCs). Compression enhances the power conversion efficiency (PCE) of a DSSC, which constitutes up 18.4 times improvement compared to the uncompressed device. Incorporating graphene into the compressed film further improves the PCE by 28.8%. Simultaneously, compressing and graphene incorporating can greatly increase the film's transmittance at long wavelengths, benefiting to the use of DSSCs as front unit in tandem solar cells. Scanning electron microscopy, porosity measurements, electrochemical impedance spectroscopy and open circuit voltage decay are performed to investigate the mechanisms. It is demonstrated that compressing a film can reduce the porosity and improve the inter-particle connections, which accounts for the increased light transmittance and enhanced PCE. The incorporated graphene can provide extra charge carrier pathway due to its excellent charge transport properties, as well as protect TiO 2 nanostructure by preventing film cracking upon pressing due to its good flexibility, thus increases PCE to 6.75%, which, to our best knowledge, is the highest value among DSSCs with room-temperature prepared photoanodes. [ABSTRACT FROM AUTHOR]

Methylamine lead iodide (CH 3 NH 3 PbI 3) perovskite thin film solar cell has attracted much attention due to its low cost and high photoelectric conversion efficiency. Preparation of high quality perovskite thin film is the key to obtain high conversion efficiency of solar cells. Here, the pinhole-free CH 3 NH 3 PbI 3 layer with high coverage and smooth surface is prepared by the one-step solution method in air with ethylacetate as anti-solvent on an electron transport hybrid layer of TiO 2 nanoparticles coated porous carbon. The effect of ethylacetate as anti-solvent on the quality of perovskite thin film is studied in detail by comparing with chlorobenzene and ethylether. The high saturation and humidity resistance of ethylacetate in air control the nucleation and growing kinetics of perovskite crystals during the spin coating process, which facilitates the formation of uniform pinhole-free perovskite thin films. The perovskite solar cell based on the prepared high quality thin film achieves the highest conversion efficiency of 17.41% in ambient air with a relative humidity of 35%, which is superior to the perovskite thin films prepared with chlorobenzene and ethylether (conversion efficiency of 10.80% and 10.20%). The higher light-to-electric conversion efficiency is due to high coverage of the pinhole-free perovskite thin film and good contact with the electron transport layer and the hole transport layer. The high quality CH 3 NH 3 PbI 3 layer is prepared by the one-step solution method in air with ethylacetate as anti-solvent on an electron transport hybrid layer of TiO 2 nanoparticles coated porous carbon. The perovskite solar cell based on the prepared high quality thin film achieves the highest conversion efficiency of 17.41% in ambient air, which is due to high coverage of the pinhole-free perovskite thin film and good contact with the electron transport layer. Image 1 • Ethylacetate was used as anti-solvent to deposit high quality perovskite layer in air. • The saturation and humidity resistance of ethylacetate change the crystal kinetics. • The smooth pinhole-free perovskite layer with high coverage was prepared in air. • Perovskite solar cell based on the prepared film achieves the conversion efficiency of 17.41%. [ABSTRACT FROM AUTHOR]

Metal-Organic Frameworks (MOFs) have attracted much attention due to its large specific surface, flexible porosity and unsaturated coordination bonds. Cathodic deposition is a unique in-situ potential-driven synthesis method for the deposition of thin film MOFs; however, the gradually consumption of reactants during cathodic deposition might lead to unstable and uncontrollable reaction during thin-film MOF deposition. Herein, oxygen is selected as the initial reactant for the formation of OH−, which can result in gradually and successive formation of thin-film MAF-66 (Metal azolate framework-66), and the particle size and film thickness of the MAF-66 film can be easily tuned by the deposition time. Furthermore, the cathodic deposited thin-film MAF-66 show good adsorption property for heavy metal ions, with Cd2+ as a representative species. The adsorption capacity can reach 32.3 ​mg/g (removal ratio: 69%) and the deposited MAF-66 film can achieve a satisfactory recovery degree with structural and morphological stability. In this way, a novel, environmental-friendly, and controllable cathode deposition method is developed for preparation of thin-film MAF-66, which also show great promise as a candidate for heavy metal ions adsorbent. Schematic illustration of the cathodic deposition of thin-film MAF-66 and its application for Cd2+ Adsorption. [Display omitted] • A simple, environmental friendly, and sustainable cathode deposition method is developed to prepare MAF-66 film. • The particle size and film thickness of MAF-66 film can be easily tuned. • The MAF-66 film exhibits good adsorption capacity toward Cd2+ adsorption. [ABSTRACT FROM AUTHOR]