Light-Dependent Electrogenic Activity of Cyanobacteria

Cyanobacteria account for 20-30% of Earth's primary photosynthetic productivity and convert solar energy into biomass-stored chemical energy at the rate of approximately 450 TW [1]. These single-cell microorganisms are resilient predecessors of all higher oxygenic phototrophs and can be found in self-sustaining, nitrogen-fixing communities the world over, from Antarctic glaciers to the Sahara desert [2].Here we show that diverse genera of cyanobacteria including biofilm-forming and pelagic strains have a conserved light-dependent electrogenic activity, i.e. the ability to transfer electrons to their surroundings in response to illumination. Naturally-growing biofilm-forming photosynthetic consortia also displayed light-dependent electrogenic activity, demonstrating that this phenomenon is not limited to individual cultures. Treatment with site-specific inhibitors revealed the electrons originate at the photosynthetic electron transfer chain (P-ETC). Moreover, electrogenic activity was observed upon illumination only with blue or red but not green light confirming that P-ETC is the source of electrons. The yield of electrons harvested by extracellular electron acceptor to photons available for photosynthesis ranged from 0.05% to 0.3%, although the efficiency of electron harvesting likely varies depending on terminal electron acceptor.The current study illustrates that cyanobacterial electrogenic activity is an important microbiological conduit of solar energy into the biosphere. The mechanism responsible for electrogenic activity in cyanobacteria appears to be fundamentally different from the one exploited in previously discovered electrogenic bacteria, such as Geobacter, where electrons are derived from oxidation of organic compounds and transported via a respiratory electron transfer chain (R-ETC) [3], [4]. The electrogenic pathway of cyanobacteria might be exploited to develop light-sensitive devices or future technologies that convert solar energy into limited amounts of electricity in a self-sustainable, CO(2)-free manner

A modified ‘skeleton/skin’ strategy for designing CoNiP nanosheets arrayed on graphene foam for on/off switching of NaBH4_{4} hydrolysis

CoNiP nanosheet array catalysts were successfully prepared on three-dimensional (3D) graphene foam using hydrothermal synthesis. These catalysts were prepared using 3D Ni–graphene foam (Ni/GF), comprising nickel foam as the ‘skeleton’ and reduced graphene oxide as the ‘skin’. This unique continuous modified ‘skeleton/skin’ structure ensure that the catalysts had a large surface area, excellent conductivity, and sufficient surface functional groups, which promoted in situ CoNiP growth, while also optimizing the hydrolysis of sodium borohydride. The nanosheet arrays were fully characterized and showed excellent catalytic performance, as supported by density functional theory calculations. The hydrogen generation rate and activation energy are 6681.34 mL min$_{−1}$ g$_{−1}$ and 31.2 kJ mol$_{−1}$, respectively, outperforming most reported cobalt-based catalysts and other precious metal catalysts. Furthermore, the stability of mockstrawberry-like CoNiP catalyst was investigated, with 74.9% of the initial hydrogen generation rate remaining after 15 cycles. The catalytic properties, durability, and stability of the catalyst were better than those of other catalysts reported previously

Formation of MXene-Derived/NiCoFe-LDH Heterostructures for Supercapacitor Applications

In this study, MXene-derived/NiCoFe-LDH heterostructures with three-dimensional interconnected porous network microstructures were prepared, leveraging the excellent electrical conductivity and growth platform provided by the MXene material. The remarkable specific capacitance of metal oxides was fully exploited. The composite exhibited high specific capacitance and excellent stability, with a specific capacitance of 1305 F g−1 at 1 A g−1 and a capacitance of 85.7% of the initial performance after 6000 charge/discharge tests at 10 A g−1. A two-electrode assembly was constructed using activated carbon as the negative electrode material corresponding to 49.5 Wh kg−1 at 800 W kg−1, indicating that the electrodes could achieve rapid charge/discharge. The findings of this study indicate that the composite material comprising LDH/MXene has significant potential for supercapacitor applications

Analysis of Fowl Adenovirus 4 Transcriptome by De Novo ORF Prediction Based on Corrected Nanopore Full-Length cDNA Sequencing Data

The transcriptome of fowl adenovirus has not been comprehensively revealed. Here, we attempted to analyze the fowl adenovirus 4 (FAdV-4) transcriptome by deep sequencing. RNA samples were extracted from chicken LMH cells at 12, 18 or 26 h post-FAdV-4 infection, and subjected to Illumina strand-specific RNA-seq or nanopore full-length PCR-cDNA sequencing. After removing the reads of host cells, the data of FAdV-4 nanopore full-length cDNAs (transcripts) were corrected with reads from the Illumina RNA-seq, mapped to the viral genome and then used to predict viral open reading frames (ORFs). Other than 42 known ORFs, 39 novel ORFs were annotated to the FAdV-4 genome. Different from human adenovirus 5, one FAdV-4 ORF was often encoded by several transcripts, and more FAdV-4 ORFs were located on two exons. With these data, 18 major transcription start sites and 15 major transcription termination sites were defined, implying 18 viral promoters and 15 polyadenylation signals. The temporal cascade of viral gene transcription was observed in FAdV-4-infected cells, with six promoters possessing considerable activity in the early phase. Unexpectedly, four promoters, instead of one major late promoter, were engaged in the transcription of the viral genus-common genes on the forward strand. The clarification of the FAdV-4 transcriptome laid a solid foundation for the study of viral gene function, virulence and virus evolution, and it would help construct FAdV-4 as a gene transfer vehicle. The strategy of de novo ORF prediction could be used to parse the transcriptome of other novel adenoviruses

In Situ Growth of Nickel–Cobalt Metal Organic Frameworks Guided by a Nickel–Molybdenum Layered Double Hydroxide with Two-Dimensional Nanosheets Forming Flower-Like Struc-Tures for High-Performance Supercapacitors

Metal organic frameworks (MOFs) are a kind of porous coordination polymer supported by organic ligands with metal ions as connection points. They have a controlled structure and porosity and a significant specific surface area, and can be used as functional linkers or sacrificial templates. However, long diffusion pathways, low conductivity, low cycling stability, and the presence of few exposed active sites limit the direct application of MOFs in energy storage applications. The targeted design of MOFs has the potential to overcome these limitations. This study proposes a facile method to grow and immobilize MOFs on layered double hydroxides through an in situ design. The proposed method imparts not only enhanced conductivity and cycling stability, but also provides additional active sites with excellent specific capacitance properties due to the interconnectivity of MOF nanoparticles and layered double hydroxide (LDH) nanosheets. Due to this favorable heterojunction hook, the NiMo-LDH@NiCo-MOF composite exhibits a large specific capacitance of 1536 F·g−1 at 1 A·g−1. In addition, the assembled NiMo-LDH@NiCo-MOF//AC asymmetric supercapacitor can achieve a high-energy density value of 60.2 Wh·kg−1 at a power density of 797 W·kg−1, indicating promising applications

Synthesis of NiMoO₄/NiMo@NiS Nanorods for Efficient Hydrogen Evolution Reactions in Electrocatalysts

As traditional energy structures transition to new sources, hydrogen is receiving significant research attention owing to its potential as a clean energy source. The most significant problem with electrochemical hydrogen evolution is the need for highly efficient catalysts to drive the overpotential required to generate hydrogen gas by electrolyzing water. Experiments have shown that the addition of appropriate materials can reduce the energy required for hydrogen production by electrolysis of water and enable it to play a greater catalytic role in these evolution reactions. Therefore, more complex material compositions are required to obtain these high-performance materials. This study investigates the preparation of hydrogen production catalysts for cathodes. First, rod-like NiMoO4/NiMo is grown on NF (Nickel Foam) using a hydrothermal method. This is used as a core framework, and it provides a higher specific surface area and electron transfer channels. Next, spherical NiS is generated on the NF/NiMo4/NiMo, thus ultimately achieving efficient electrochemical hydrogen evolution. The NF/NiMo4/NiMo@NiS material exhibits a remarkably low overpotential of only 36 mV for the hydrogen evolution reaction (HER) at a current density of 10 mA·cm−2 in a potassium hydroxide solution, indicating its potential use in energy-related applications for HER processes