Genetic diversity and evolution of goose astrovirus in the east of China.

Goose astrovirus (GAstV), an agent of fatal visceral gout in goslings, has been widely circulating in eastern China since 2017, but little is known about its genetic diversity and systematic evolution. In this study, we isolated and sequenced nine nearly full-length GAstV genomes and conducted comprehensive genetic diversity and evolutionary analysis and compared them with other reported GAstV sequences. Our results indicated that two genotypic species of GAstV were circulating in China, and GAstV-2 subgenotype II-c had arisen as the dominant genotype in Shandong province and across the whole country. Multiple alignments of GAstV amino acid sequences revealed several characteristic mutations in GAstV-2 II-c strains, as well as additional residues in the nine new isolates which varied over time. Phylogenetic analysis of three open reading frames demonstrated different evolutionary histories. Evidence of natural recombination was also detected in GAstV, with most of the recombination occurring in the GAstV-2 II-c subgenotype. Molecular adaptation analyses revealed that the evolution of GAstV was shaped by strong negative selection, although a number of amino acids, which potentially affect host infection and cell entry, were subjected to positive pressure. Overall, these findings improve our understanding of the epidemiology and evolution of GAstV and may help in the development of vaccines and diagnostics.

Polymorphism of duck MHC class molecules.

Major histocompatibility complex class I (MHC I) molecules are critically involved in defense against pathogens, and their high polymorphism is advantageous to a range of immune responses, especially in duck displaying biased expression of one MHC I gene. Here, we examined MHC I polymorphism in two duck (Anas platyrhynchos) breeds from China: Shaoxing (SX) and Jinding (JD). Twenty-seven unique UAA alleles identified from the MHC I genes of these breeds were analyzed concerning amino acid composition, homology, and phylogenetic relationships. Based on amino acid sequence homology, allelic groups of Anas platyrhynchos MHC I (Anpl-MHC I) were established and their distribution was analyzed. Then, highly variable sites (HVSs) in peptide-binding domains (PBD) were estimated and located in the three-dimensional structure of Anpl-MHC I. The UAA alleles identified showed high polymorphism, based on full-length sequence homology. By adding the alleles found here to known Anpl-MHC I genes from domestic ducks, they could be divided into 17 groups and four novel groups were revealed for SX and JD ducks. The UAA alleles of the two breeds were not divergent from the MHC I of other duck breeds, and HVSs were mostly located in the peptide-binding groove (PBG), suggesting that they might determine peptide-binding characteristics and subsequently influence peptide presentation and recognition. The results from the present study enrich Anpl-MHC I polymorphism data and clarify the distribution of alleles with different peptide-binding specificities, which might also accelerate effective vaccine development and help control various infections in ducks.

Synthesis of hollow Cu1.8S nano-cubes for electromagnetic interference shielding.

The applications of inorganic semiconductor nano-structures as electromagnetic interference (EMI) shielding materials have been scarcely researched. Herein, we have designed hollow Cu1.8S nano-cubes via a mild anion exchange and etching process. These 30 wt% hollow Cu1.8S nano-cubes loaded in wax can display 30 dB of EMI shielding effectiveness (SE) in the whole tested frequency range of 2-18 GHz with a sample thickness of only 1 mm. This good EMI shielding performance can be attributed to the high electric conductivity, which leads to a high dielectric constant. This research opens up the possibility for the applications of inorganic semiconductor nano-structures as lightweight EMI shielding materials, especially in the areas of aerospace, automobile and sophisticated electronics.

In situ growth of MoS2 nanosheets on reduced graphene oxide (RGO) surfaces: interfacial enhancement of absorbing performance against electromagnetic pollution.

Electromagnetic pollution is rising all over the world. Compared with electromagnetic waves reflection, electromagnetic absorption (EA) is a better choice to balance electromagnetic applications and human health. The highly conductive networks in composites, as well as in species, and the intensity of defect polarization are the most important factors to improving the EA performance of a dielectric material. In this study, an in situ one-pot hydrothermal growth of MoS2 layers on reduced graphene oxide (RGO) surfaces was developed for the synthesis of RGO/MoS2 nanosheets. With a filler loading ratio of 20 wt%, the composite of the RGO/MoS2 nanosheets could build conductive networks and exhibited an effective EA bandwidth (lower than -10 dB) of 5.7 GHz and a minimum reflection loss (RL) of -60 dB. The results revealed that the as-prepared RGO/MoS2 nanosheets are promising EA materials, with broad and strong absorption properties at a low filler loading and low thickness.