Antibiotic susceptibility of Vibrio parahaemolyticus isolated from prawns and oysters marketed in Zhanjiang, China.

To evaluate the antibiotic susceptibility of Vibrio parahaemolyticus from prawns and oysters marketed in Zhanjiang, Guangdong, China. 84 strains of V. parahaemolyticus were isolated from prawns and oysters sampled from 9 major markets. The results showed that 84 V. parahaemolyticus strains had the highest rate of antibiotic resistance to oxytetracycline (69.05 %, 58/84) and the lowest rate of antibiotic resistance to enrofloxacin (1.19 %, 1/84), ciprofloxacin (4.76 %, 4/84) and norfloxacin (7.14 %, 6/84) in quinolone. Meanwhile, 96.42 % of the strains showed multiple antibiotic resistance (MAR). PCR results showed that the resistance phenotype was closely related to the antibiotic resistance genes and efflux pump genes (p < 0.01), and the efflux pump gene was the key causing MAR. The combination of antibiotics significantly eliminated multidrug resistance. In addition, efflux pump inhibitors also reduce MAR. This study may provide information on antibiotic susceptibility, antibiotic resistance and strategies for the control of V. parahaemolyticus.

Cadmium-chelating ability of the siderophore DHBS secreted by Leclercia adecarboxylata FCH-CR2 and its action mechanism.

As one of the most accumulative toxic heavy metals, cadmium (Cd) poses a major threat to human health. Bacterial siderophores, as small molecules with metal-absorbing ability, have great potential activity for Cd-reduction. In this study, the siderophore-producing bacterialstrain FCH-CR2 was isolated from a high-Cd contaminated soil using the CAS method. Leclercia adecarboxylata was identified through 16S rRNA sequence, homology analysis, colony morphology, physiological and biochemical tests. A siderophore, catechol type 2,3-dihydroxy-N-benzoyl-l-serine (DHBS) secreted by FCH-CR2, was purified using RP-HPLC and identified by LC-MS/MS. Intraperitoneal injection of DHBS significantly increased fecal Cd levels, and reduced Cd accumulation in organs. In density flooding theory (DFT) analysis, DHBS may bind to Cd via the hydroxyl site on the benzene ring. Besides, the isothermal titration calorimetry (ITC) assay revealed that the formation of Cd-DHBS is a spontaneous and endothermic reaction with ΔG = -21.4 kJ/mol and ΔH = 1.51 ± 0.142 kJ/mol.

Construction of Single-Atom Platinum Catalysts Enabled by CsPbBr3 Nanocrystals.

Lead halide perovskite nanocrystals (CsPbX3 NCs) have been regarded as promising materials in photocatalysis. Combining metal single atoms with CsPbX3 NCs may be a practical way in exploring perovskite-based catalysts. However, such hybrids have not been achieved experimentally yet, mainly due to the weak interaction between the metal atom and the CsPbX3 surface. Here, we demonstrate that Pt single atoms can be deposited on CsPbBr3 NCs through a photoassisted approach, in which the surface was partially oxidized first, followed by the anchoring of Pt single atoms through the formation of Pt-O and Pt-Br bonds. The deposition of Pt single atoms can significantly change the photophysical properties of CsPbBr3 NCs by inducing the generation of deep trap states in the band gap. The as-prepared Pt-SA/CsPbBr3 can be used as efficient and durable catalysts for photocatalytic semi-hydrogenation of propyne. A CsPbBr3 nanocrystal might be a suitable substrate for anchoring other metal single atoms, such as Cu, Au, Ag, Pd, and so on.

Soil fertility evaluation and spatial distribution of grasslands in Qilian Mountains Nature Reserve of eastern Qinghai-Tibetan Plateau.

The study assessed the overall soil characteristics of grasslands on Qilian Mountains and rated the soil nutrient status with classification standard of the second national soil survey of China. Nemerow index method was used to evaluate the soil fertility of different grassland types. GIS was used to analyze the spatial distribution of the soil nutrients and provided a database for the grassland's ecological protection and restoration. The study graded the soil organic matter (SOM), total N, and available K at level 2 (high) or above for most regions, available soil-P at level 4, while the soil bulk density, total porosity and pH were 0.77-1.32 g cm-3, 35.36-58.83% and 7.63-8.54, respectively. The rank of comprehensive soil fertility index was temperate steppe (TS) > alpine meadow (AM) > alpine steppe (AS) >upland meadow (UM) >alpine desert (AD)> lowland meadow (LM)> temperate desert steppe (TDS)> temperate desert (TD). The areas with high, medium and low soil fertility accounted for 63.19%, 34.24% and 2.57% of the total grassland area. Soil fertility of different grassland types had different main limiting factors, for instance, the pH, total N and SOM were the main factors limiting soil fertility in LM, while pH and available P were the main factors limiting soil fertility in UM, AM, TS and AS. In summary, the grassland soil fertility was generally at the mid-upper level, and the main limiting factors were found in the different types of the grasslands and their spatial distributions were figured out. Our findings also indicated that the typical grasslands and meadows may require phosphorus application, while for desert grasslands, both nitrogen and phosphorus were required to improve their comprehensive soil fertility and grassland productivity.

Improved photophysical properties and durability of CsPbBr3 NCs endowed by inorganic oxoacid and bromide ions.

All-inorganic lead halide perovskite nanocrystals (NCs) have been promising candidates in various optoelectrical fields. It is still challenging to further enhance their optical properties and stability to meet the requirements of practical applications. Herein, we develop a passivation strategy towards CsPbBr3 NCs by using inorganic phosphate and bromide anions. Phosphate can coordinate with lead ions on CsPbBr3 NCs as capping ligands; meanwhile, excess bromide can strengthen the repair of surface trapping sites. The treated NCs exhibit near-unity quantum yield and boosted radiative recombination. In addition, obvious enhancement has been realized in their durability against polar solvents. A white light emitting diode (WLED) has been fabricated by employing the passivated NCs as a green light source, which possesses high luminous efficiency and operational stability.

Fabricating MAPbI3/MoS2 Composites for Improved Photocatalytic Performance.

Although lead halide perovskites are demonstrated to be promising photocatalysts for hydrogen evolution from hydrogen halide splitting, it still remains challenging to fabricate efficient and stable catalysts. Here MoS2 nanoflowers with abundant active sites are assembled with methylammonium lead iodide (MAPbI3) microcrystals to form a new heterostructure. Its hydrogen evolution rate can reach up to about 30 000 µmol g-1 h-1, which is more than 1000-fold higher than pristine MAPbI3 under visible light irradiation (λ ≥ 420 nm). Importantly, the solar HI splitting efficiency reaches 7.35%, one of the highest efficiencies so far. The introduction of MoS2 with proper band alignment and unsaturated species can efficiently promote the charge separation and afford more active sites for H2 production. This finding not only provides a highly efficient and stable photocatalyst for hydrogen evolution but also offers a useful modification strategy on lead halide perovskites.

A High Capacity, Good Safety and Low Cost Na2FeSiO4-Based Cathode for Rechargeable Sodium-Ion Battery.

Rechargeable sodium-ion batteries (SIBs) are receiving intense interest because the resource abundance of sodium and its lithium-like chemistry make them low cost alternatives to the prevailing lithium-ion batteries in large-scale energy storage devices. Two typical classes of materials including transition metal oxides and polyanion compounds have been under intensive investigation as cathodes for SIBs; however, they are still limited to poor stability or low capacity of the state-of-art. Herein, we report a low cost carbon-coated Na2FeSiO4 with simultaneous high capacity and good stability, owing to the highly pure Na-rich triclinic phase and the carbon-incorporated three-dimensional network morphology. The present carbon-coated Na2FeSiO4 demonstrates the highest reversible capacity of 181.0 mAh g-1 to date with multielectron redox reaction that occurred among various polyanion-based SIBs cathodes, which achieves a close-to-100% initial Coulombic efficiency and a stable cycling with 88% capacity retention up to 100 cycles. In addition, such an electrode shows excellent stability either charged at a high voltage of 4.5 V or heated up to 800 °C. The present work might open up the possibility for developing high capacity, good safety and low cost polyanion-based cathodes for rechargeable SIBs.

SnS2 Nanowall Arrays toward High-Performance Sodium Storage.

Cost-effective sodium ion batteries (SIBs) are emerging as a desirable alternative choice to lithium ion batteries in terms of application in large-scale energy storage devices. SnS2 is regarded as a potential anode material for SIBs because of its unique layered structure and high theoretical specific capacity. However, the development of SnS2 was hindered by the sluggish kinetics of the diffusion process and the inevitable volume change during repeated sodiation-desodiation processes. In this work, SnS2 with a unique nanowall array (NWA) structure is fabricated by one-step pulsed spray evaporation chemical vapor deposition (PSE-CVD), which could be used directly as binder-free and carbon-free anodes for SIBs. The SnS2 NWA electrode achieves a high reversible capacity of 576 mAh g-1 at 500 mA g-1 and enhanced cycling stability. Attractively, an excellent rate capability is demonstrated with ∼370 mAh g-1 at 5 A g-1, corresponding to a capacity retention of 64.2% at 500 mA g-1. The superior sodium storage capability of the SnS2 NWA electrode could be attributed to outstanding electrode design and a rational growth process, which favor fast electron and Na-ion transport, as well as provide steady structure for elongated cycling.