Reconfigurable integrated structures with functions of Fabry-Perot antenna and wideband liquid absorber for radar system stealth.

This paper proposes a functionally reconfigurable integrated structure of a Fabry-Perot (FP) antenna and wideband liquid absorber. First, a two-layer partial reflecting surface (PRS) has been designed. Then, a patch antenna is used to act as the source antenna. By combining the source antenna with the PRS, an FP antenna has been designed. What's more, taking full advantage of the reflective properties of PRS, a liquid broadband absorber is then designed. Last, the integrated structure with two functions has been realized. It can be used as the FP antenna or the liquid absorber through the extraction and injection of ethanol. In this way, it is effective to switch between stealth and detection states which can be used in different electromagnetic environments. The PRS is elaborately tailored to serve as both a component of the FP antenna and the metal ground of the broadband liquid absorber. Then the integrated structure is realized by combining the FP antenna with the liquid absorber. The PRS is composed of patches on the top layer of the substrate and the square loop on the bottom. The liquid absorber is composed of a 3-D printed container, 45% ethanol layer and the PRS is used to serve as the metal ground. The formula of Mie resonance theory has been extended and used to design the liquid absorber. The gain of the antenna is 19.7 dBi when the ethanol is extracted. When the ethanol is injected, a wideband liquid absorber is achieved. The absorption band (S11 < - 10 dB) ranges from 4 to 18 GHz. The absorption bandwidth is over 133%. The monostatic RCS reduction bands of the structure with ethanol range from 4 to 18 GHz and the average RCS reduction is 28.4 dBsm. The measured and simulated results are in good agreement.

Combined virome analysis and metagenomic sequencing to reveal the viral communities and risk of virus-associated antibiotic resistance genes during composting.

The issue of antibiotic resistance genes (ARGs) pollution in manure has garnered significant attention, with viruses now being recognized as crucial carriers and disseminators of ARGs. However, the virus-associated ARG profiles and potential health risks in composts are still unclear. In this study, the viral communities and associated ARGs in biogas residue and pig faeces composts were profiled by virome analysis. The viral communities were dominated by Caudovirales, and non-thermophilic viruses were inactivated during composting. The diversity and abundance of ARGs were lower in virome than in metagenome, while ARGs' risk was greater in virome than in metagenome. There were six bacterial genera identified as viral hosts at the genomic level, Pseudomonas and Clostridium carried high-risk ARGs. Virus-associated ARGs in viral hosts had a higher risk rank than non-virus-associated ARGs. Composting reduced the diversity, abundance and risk of viral ARGs. The risk of ARGs in biogas residues was significantly lower than that of pig faeces in the initial period of composting, and the two different substracts equally less harmful after composting. These results revealed that viruses play a non-negligible role in spreading ARGs, posing high risk to environmental and human health.

Co-composting with cow dung and subsequent vermicomposting improve compost quality of spent mushroom.

In order to determine a feasible degrading process for spent mushroom (SMS) with high lignin content, the present work used cow dung (CD), SMS, and a mixture of CD and SMS as substrates and evaluated the effects of vermicomposting on the microflora and the quality of composting products. Bacterial (R2 = 0.548, P = 0.001) and fungal (R2 = 0.314, P = 0.005) community both were different between composting and vermicomposting. Vermicomposting and substrates affected enzyme activities indirectly by affecting ammonium, pH, total carbon, richness, and bacterial community composition. These results suggested that appropriate regulation of environmental factors may increase microbial activity. An increase in ion-exchange capacity (up to 139.8%), pH (6.9%), and nitrate (71.1%) and a decrease in total carbon (31.2%) and carbon/nitrogen ratio (32.1%) in vermicomposting indicated that earthworms could further improve product quality. Co-composting with CD and integrated subsequent vermicomposting efficiently promoted the maturity of SMS.

Vaccination and Quarantine Effect on COVID-19 Transmission Dynamics Incorporating Chinese-Spring-Festival Travel Rush: Modeling and Simulations.

The COVID-19 pandemic has adversely affected the entire world. The effective implementation of vaccination strategy is critical to prevent the resurgence of the pandemic, especially during large-scale population migration. We establish a multiple patch coupled model based on the transportation network among the 31 provinces in China, under the combined strategies of vaccination and quarantine during large-scale population migration. Based on the model, we derive a critical quarantine rate to control the pandemic transmission and a vaccination rate to achieve herd immunity. Furthermore, we evaluate the influence of passenger flow on the effective reproduction number during the Chinese-Spring-Festival travel rush. Meanwhile, the spread of the COVID-19 pandemic is investigated for different control strategies, viz. global control and local control. The impact of vaccine-related parameters, such as the number, the effectiveness and the immunity period of vaccine, are explored. It is believed that the articulated models as well as the presented simulation results could be beneficial to design of feasible strategies for preventing COVID-19 transmission during the Chinese-Spring-Festival travel rush or the other future events involving large-scale population migration.

Conversion of rainforest into agroforestry and monoculture plantation in China: Consequences for soil phosphorus forms and microbial community.

Microbial communities and their associated enzyme activities affect quantity and quality of phosphorus (P) in soils. Land use change is likely to alter microbial community structure and feedback on ecosystem structure and function. This study presents a novel assessment of mechanistic links between microbial responses to land use and shifts in the amount and quality of soil phosphorus (P). We investigated effects of the conversion of rainforests into rubber agroforests (AF), young rubber (YR), and mature rubber (MR) plantations on soil P fractions (i.e., labile P, moderately labile P, occluded P, Ca P, and residual P) in Hainan Island, Southern China. Microbial community composition and microbial enzyme were assayed to assess microbial community response to forest conversion. In addition, we also identified soil P fractions that were closely related to soil microbial and chemical properties in these forests. Conversion of forest to pure rubber plantations and agroforestry system caused a negative response in soil microorganisms and activity. The bacteria phospholipid fatty acid (PLFAs) levels in young rubber, mature rubber and rubber agroforests decreased after forest conversion, while the fungal PLFAs levels did not change. Arbuscular mycorrhizal fungi (AMF) (16:1w5c) had the highest value of 0.246µmol(gOC)-1 in natural forest, followed by rubber agroforests, mature rubber and young rubber. Level of soil acid phosphatase activity declined soon (5 years) after forest conversion compared to natural forest, but it improved in mature rubber and agroforestry system. Labile P, moderately labile P, occluded P and residual P were highest in young rubber stands, while moderately labile, occluded and residual P were lowest in rubber agroforestry system. Soil P fractions such as labile P, moderately labile P, and Ca P were the most important contributors to the variation in soil microbial community composition. We also found that soil P factions differ significantly among the four transformation systems. Soil labile P faction and its potential sources (moderately labile P, occluded P, and residual P) were positively correlated with NO3-, but negatively correlated with AMF, suggesting that these properties play key roles in P transformation. Our study indicated that land use had an impact on microbial community composition and functions, which consequently influenced soil phosphorus availability and cycling.