Precisely Constructing Orbital-Coupled Fe─Co Dual-atom Sites for High-Energy-Efficiency Zn-Air/Iodide Hybrid Batteries.

Rechargeable Zn-air batteries (ZABs) are promising for energy storage and conversion. However, the high charging voltage and low energy efficiency hinder their commercialization. Herein, these challenges are addressed by employing precisely constructed multifunctional Fe-Co diatomic site catalysts (FeCo-DACs) and integrating iodide/iodate redox into ZABs to create Zinc-air/iodide hybrid batteries (ZAIHBs) with highly efficient multifunctional catalyst. The strong coupling between the 3d orbitals of Fe and Co weakens the excessively strong binding strength between active sites and intermediates, enhancing the catalytic activities for oxygen reduction/evolution reaction and iodide/iodate redox. Consequently, FeCo-DACs exhibit outstanding bifunctional oxygen catalytic activity with a small potential gap (ΔE = 0.66 V) and outstanding stability. Moreover, an outstanding catalytic performance toward iodide/iodate redox is obtained. Therefore, FeCo-DAC-based ZAIHBs exhibit high energy efficiency of up to 75% at 10 mA cm-2 and excellent cycling stability (72% after 500 h). This research offers critical insights into the rational design of DACs and paves the way for high-energy efficiency energy storage devices.

Comprehensively Understanding the Role of Anion Vacancies on K-Ion Storage: A Case Study of Se-Vacancy-Engineered VSe2.

Anion vacancy engineering (AVE) is widely used to improve the Li-ion and Na-ion storage of conversion-type anode materials. However, AVE is still an emerging strategy in K-ion batteries, which are promising for large-scale energy storage. In addition, the role of anion vacancies on ion storage is far from clear, despite several proposed explanations. Herein, by employing VSe2 as a model conversion-type anode material, Se vacancies are intentionally introduced (labeled as P-VSe2-x ) to investigate their effect on K+ storage. The P-VSe2-x shows excellent cyclability in half cells (143 mA h g-1 at 3.0 A g-1 after 1000 cycles) and high energy density in coin-type full cells (206.8 Wh kg-1 ). By applying various electrochemical techniques, the effects of Se vacancies on the redox potentials of K-ion insertion/extraction and the K-ion diffusion in electrodes upon cycling are uncovered. In addition, the structural evolution of Se vacancies during potassiation/de-potassiation using various operando and ex characterizations is revealed. Moreover, it is demonstrated that Se vacancies can facilitate the breaking of VSe bonds upon the P-VSe2-x conversion using theoretical calculations. This work comprehensively explains the role of anion vacancies in ion storage for developing high-performance conversion-type anode materials.

[Screening and characterization of antibacterial and cytotoxic marine bacteria associated with Karlodinium micrum].

OBJECTIVE: Antibacterial and cytotoxic activities were screened for marine bacteria which have been isolated from Karlodinium micrum, in order to obtain potential strains with antibacterial and cytotoxic activities. METHODS: In total 38 bacteria isolated from Karlodinium micrum were screened by agar-screening and MTT methods. The 16S rRNA genes were amplified from the genome DNA of those bacteria positive for both antibacterial and cytotoxic activities, which were cloned into pMD18-T vector for sequencing analysis. RESULTS: Twenty-five isolates had antimicrobial activity and 5 isolates (W-14-2, W-2-2, W-12, E-8-2 and W-4) had cytotoxicity. Molecular phylogenetic analysis of marine bacteria with cytotoxicity based on 16S rRNA sequences indicated that they exhibited the highest similarity (98%, 99%, 99%, 98% and 99%, respectively) to the 16S rRNA fragments of Alteromonas alvinellae, Stappia aggregata, Pelagibaca bermudensis, Marinobacter kribbensis and Maribacter dokdonensis. CONCLUSION: The bacteria with bioactivity in Karlodinium micrum were abundant. We obtained five strains positive for both antibacterial and cytotoxic activities, which provide a clue to understanding the mechanism of toxin biosynthesis in Karlodinium micrum based on epiphytic and endophytic bacteria.

Molecular phylogeny and modular structure of hybrid NRPS/PKS gene fragment of Pseudoalteromonas sp. NJ6-3-2 isolated from marine sponge Hymeniacidon perleve.

Among 12 marine bacterial strains from the China coast that exhibited interesting bioactivity (positive for both antimicrobial and cytotoxic activities), only four strains, namely, NJ6-3-1, NJ6-3-2, NB-6, and YTHM-17, had a KS domain or A domain when screened for PKS and NRPS genes using a PCR. Interestingly, two of these strains belonging to Pseudoalteromonas and associated with the marine sponge Hymeniacidon perleve were positive for both PKS and NRPS, whereas the other two strains of Pseudoalteromonas did not have a PKS or NRPS gene. A molecular phylogeny analysis and DGGE analysis of the Pseudoalteromonas sp. indicated that they had a specific affinity with the host marine sponge Hymeniacidon perleve. Furthermore, an analysis of a partial sequence of Pseudoalteromonas sp. NJ6-3-2 isolated from the marine sponge Hymeniacidon perleve obtained from genomic walking using a computational approach indicated a relatively complete PKS module including auxiliary domains (DH,KR,and Cy).

Toxicological studies of Karlodinium micrum (Dinophyceae) isolated from East China Sea.

Karlodinium micrum (Strain NMBjah047) was isolated from the water samples of East China Sea (ECS). The hemolytic, ichthyotoxic, and cytotoxic activities of the algae was characterized. Embryotoxicity of both intra and extracellular extracts were also tested on a local sea urchin species. The algal intracellular hemolytic toxicity averaged about 87.5% at different algal growth phases. However, extracellular hemolytic activity depended on the population growth phase. The toxicity increased with the increase in the population size, reaching the highest hemolytic activity during the stationary phase, and maintained a relatively high activity even when the population declined. Time and density dependent ichthyotoxicity to Lateolabrax maculates juveniles was also detected. The LD(50) in 24 h was 1.1 × 10(5) cells/mL. Inhibition of the fertilized egg hatching was also observed and estimated the IC(50) in 40 h with 3.5 × 10(4) cells/mL. Extracellular extracts of K. micrum dense culture also showed significant cytotoxic activity on HUVEC (IC(50) = 70.8 µg/mL). A dose dependent acute toxicity to embryos of sea urchin was also determined. The algal intracellular and extracellular extracts delayed or even restricted the embryological development of the sea urchin, illustrating the potential toxicity of K. micrum not only to vertebrates, but also to marine invertebrates. The hemolytic compounds in the ECS strain were extracted and analyzed. At least two fractions had significant hemolytic activities. A lipid-like compound, named Digalactosyldiacylglycerol (DGDG), was suggested to be responsible for the hemolytic activity in one of these fractions. From the results of the present studies, this strain of K. micrum isolated from the East China Sea might be considered a toxic strain with hemolytic activity, ichthyotoxicity, cytotoxicity and embryotoxicity.

Sequencing and modular analysis of the hybrid non-ribosomal peptide synthase - polyketide synthase gene cluster from the marine sponge Hymeniacidon perleve-associated bacterium Pseudoalteromonas sp. strain NJ631.

In the present study, we sought to confirm a putative non-ribosomal peptide synthase (NRPS) - polyketide synthase (PKS) gene cluster in marine sponge-associated bacterium with cytotoxic activity and elucidate the gene's structural information. The genomic library of the marine sponge Hymeniacidon perleve-associated bacterium Pseudoalteromonas sp. strain NJ631 was constructed using a pCC1FOS fosmid. Positive clones that covered the whole gene cluster region of hybrid NRPS-PKS were selected for shotgun sequencing. The results obtained from BlastX and open reading frame (ORF) analysis indicated that there are 3 big ORFs, NJA1, NJA2, and NJA3, that encoded proteins with similarities to amino acid adenylation, beta-ketoacyl synthase, and non-ribosomal peptide synthase, respectively, from different organisms. The results gave us a clue that there could be PKS or NRPS modules in the 3 ORFs. Further analysis demonstrated 3 ORFs encoding 2 NRPS modules, 1 PKS module, and 3 NRPS modules. Using the specificity-conferring selection rule, the substrate specificity of 4 adenylation (A) domains (A2, A3, A4, and A5) were successfully predicted, and the amino acids of the substrate specificity were glutamic acid - glutamine, serine, D-serine, and Aeo (2-amino-9,10-epoxy-8-oxodecanoic acid), respectively.