UV-modification of Ag nanoparticles on α-MoCx for interface polarization engineering in electromagnetic wave absorption.

The design of electromagnetic wave absorbing materials (EWAMs) has aroused great attention with the express development of electromagnetic devices, which pose a severe EM pollution risk to human health. Herein, an Ag-doped MoCx composite was designed and constructed through a UV-light-induced self-reduction process. The UV-reduction time was controlled on the α-MoC polymer for 0.5-2 hours for modifying different amounts of Ag. As a result, α-MoC@Ag-1.5 exhibited the strongest RLmin of -56.51 dB at 8.8 GHz under a thickness of 3.0 mm and the widest EAB of 4.96 GHz (12.16-17.12 GHz) covering a substantial portion of the Ku-band at a thickness of 2.0 mm due to the synergy of the conductivity loss and abundant interfacial polarization sites. Additionally, a new strategy for computer simulation technology was proposed to simulate substantial radar cross-sectional reduction values with real far-field conditions, whereby absorbing coatings with α-MoC@Ag-1.5 were proved to contribute to a remarkable radar cross-sectional reduction of 37.4 dB m2.

Three-dimensional ordered macroporous ZIF-8 nanoparticle-derived nitrogen-doped hierarchical porous carbons for high-performance lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries have attracted considerable attention due to their ultra-high specific capacity and energy density. However, there are still problems to be resolved such as poor conductivity of sulfur cathodes and dissolution of polysulfides in organic electrolytes. Herein, a novel ZIF-8-derived nitrogen-doped connected ordered macro-microporous carbon (COM-MPC) was developed by a dual solvent-assisted in situ crystallization method within a face-centered cubic stacking sphere template, which acts as an advanced sulfur host for enhanced Li-S battery performance. Compared with the conventional predominant microporous C-ZIF-8, the unique hierarchical macro-microporous structure with nitrogen doping not only renders polysulfide intermediates enhanced entrapment by confining the effect of micropores and chemisorption of doping N atoms, but also facilitates electrolyte accessibility and efficient ion transport owing to the ordered macroporous structure. Benefitting from this, the COM-MPC@S cathode delivers a high initial specific capacity of 1498.5 mA h g-1 and a reversible specific capacity of 1118.9 mA h g-1. Moreover, the COM-MPC@S cathode exhibits 82.3% of capacity retention within 10th to 50th cycle at 0.5C and a large capacity of 608.5 mA h g-1 after 50 cycles at a higher rate of 1C, and this enhanced cycling stability and rate capability demonstrate great practical application potential in Li-S battery systems.

Activation of PhoBR under phosphate-rich conditions reduces the virulence of Xanthomonas oryzae pv. oryzae.

The two-component signal transduction system PhoBR regulates the adaptation to phosphate limitation and the virulence of many animal bacterial pathogens. However, PhoBR in phytopathogens has rarely been investigated. In this study, we found that PhoBR in Xanthomonas oryzae pv. oryzae (Xoo), the pathogen of rice bacterial leaf blight, also regulates the adaptation to phosphate starvation. Unexpectedly, rice leaves infected by the phoBR-deleted mutant and wild-type PXO99A showed similar lesions, indicating that PhoBR is unnecessary for the virulence of Xoo. phoBR was found to be silenced during host infection, whereas artificially constitutive PhoBR expression attenuated virulence on host rice and growth in phosphate-rich media. RNA-sequencing (RNA-seq) was then performed to investigate the global effect caused by constitutive PhoBR activation. RNA-seq and further experiments revealed that the PhoBR regulon in Xoo comprised a wide range of genes. Nutrient transport and metabolism readjustments that resulted from PhoBR regulon activation may be responsible for growth attenuation. Our findings suggest that growth reduction regulated by PhoBR is a fitness cost of adaptation to phosphate starvation. PhoBR in Xoo is activated under phosphate-limited conditions, which could exist in epiphytic and saprophytic surviving phases, and is strictly repressed within phosphate-rich host plants to minimize fitness costs.

The global strategy employed by Xanthomonas oryzae pv. oryzae to conquer low-oxygen tension.

Xanthomonas oryzae pv. oryzae (Xoo) is a notorious rice pathogen that causes bacterial leaf blight (BLB), a destructive rice disease. Low-oxygen tension in the xylem vessels of rice stresses Xoo during infection. In this study, differentially expressed proteins under normoxic and hypoxic conditions were identified using high-performance liquid chromatography (HPLC) coupled with LC-MS/MS to investigate the global effects of low oxygen environment on Xoo PXO99A. A statistically validated list of 187 (normoxia) and 140 (hypoxia) proteins with functional assignments was generated, allowing the reconstruction of central metabolic pathways. Ten proteins involved in aromatic amino acid biosynthesis, glycolysis, butanoate metabolism, propanoate metabolism and biological adhesion were significantly modulated under low-oxygen tension. The genes encoded by these proteins were in-frame deleted, and three of them were determined to be required for full virulence in Xoo. The contributions of these three genes to important virulence-associated functions, including extracellular polysaccharide, cell motility and antioxidative ability, are presented. BIOLOGICAL SIGNIFICANCE: To study how Xanthomonas oryzae pv. oryzae (Xoo) conquers low-oxygen tension in the xylem of rice, we identified differentially expressed proteins under normoxic and hypoxia. We found 140 proteins that uniquely expressed under the hypoxia were involved in 33 metabolism pathways. We identified 3 proteins were required for full virulence in Xoo and related to the ability of extracellular polysaccharide, cell motility, and antioxidative. This study is helpful for broadening our knowledge of the metabolism processed of Xoo in the xylem of rice.

A two-domain protein triggers heat shock pathway and necrosis pathway both in model plant and nematode.

The entomopathogen Bacillus thuringiensis is equipped with multiple virulent factors. The genome sequence of B. thuringiensis YBT1520 revealed the presence of a two-domain protein named Nel which is composed of a necrosis-inducing phytophthora protein 1-like domain found in phytopathogens and a ricin B-like lectin domain. The merging of two distantly related domains is relatively rare. Nel induced necrosis and pathogen-triggered immunity (PTI) on model plants. The Nel also exhibited inhibition activity to nematode. Microscopic observation showed that the toxicity of Nel to nematodes targets the intestine. Quantitative proteomics revealed that Nel stimulated the host defence. The Nel thus possesses dual roles, as both toxin and elicitor. Remarkably, the Nel protein triggered a similar response, induction of the heat shock pathway and the necrosis pathway, in both model plants and nematodes. The unusual ability of Nel to function across kingdom suggests a highly conserved mechanism in eukaryotes that predates the divergence of plants and animal. It is also speculated that the two-domain protein is the result of horizontal gene transfer (HGT) between phytopathogens and entomopathogens. Our results provide an example that HGT occurs between members of different species or even genera with lower frequency are particularly important for evolution of new bacterial pathogen lineages with new virulence. Bacillus thuringiensis occupies the same ecological niches, plant and soil, as phytopathogens, providing the opportunity for gene exchange.