Compositional and Hollow Engineering of Silicon Carbide/Carbon Microspheres as High-Performance Microwave Absorbing Materials with Good Environmental Tolerance

Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow Si C/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach-60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.

An integrative analysis of metabolomics,DNA methylation and RNASeq data reveals key genes involved in albino tea'Haishun 2'

Albino tea,a type of tea closely associated with the chlorophyll-deficient phenotype is of great interest due to its multiple benefits to human health.To explore the potential mechanisms involved in albino tea,we performed metabolomics,DNA methylation and RNA-Seq analysis of green and albino leaves in a special tea mutant'Haishun 2'.The albino leaves accumulated significantly less catechins compared with the green leaves,which is closely associated with their difference in chlorophyll formation.A total of 385 candidate genes were identified by the integrative analysis.Two NAC transcription factors were less methylated and highly up regulated in the albino leaves of'Haishun 2',which was the first identification of the key roles of NAC transcription factors in albino tea and worth further study.Many genes involved in catechin biosynthesis were down regulated in albino leaves,such as 4-coumarate-CoA ligase,flavonol synthase and leucoanthocyanidin reductase genes,suggesting chlorophyll formation is important for catechin biosynthesis.Furthermore,CsMYB5 and CsGSTF11 were found to be differentially methylated and expressed in albino and green leaves,indicating their potential roles in catechin accumulation.This was the first report of the integrative analysis of transcriptome and DNA methylation data in tea plants and the results suggest that the integrative analysis is useful for exploring key genes associated with epigenetic changes in tea plants.

Microfluidic chemostatic bioreactor for high-throughput screening and sustainable co-harvesting of biomass and biodiesel in microalgae

As a renewable and sustainable source for energy,environment,and biomedical applications,microalgae and microalgal biodiesel have attracted great attention.However,their applications are confined due to the cost-efficiency of microalgal mass production.One-step strategy and continuous culturing systems could be solutions.However,current studies for optimization throughout microalgae-based biofuel production pipelines are generally derived from the batch culture process.Better tools are needed to study algal growth kinetics in continuous systems.A microfluidic chemostatic bioreactor was presented here,providing low-bioadhesive cultivations for algae in a cooperative environment of gas,nutrition,and temperature(GNT)involved with high throughput.The chip was used to mimic the continuous culture environment of bioreactors.It allowed simultaneously studying of 8×8 different chemostatic conditions on algal growth and oil production in parallel on a 7×7 cm^(2)footprint.On-chip experiments of batch and continuous cultures of Chlorella.sp.were performed to study growth and lipid accumulation under different nitrogen concentrations.The results demonstrated that microalgal cultures can be regulated to grow and accumulate lipids concurrently,thus enhancing lipid productivity in one step.The developed on-chip culturing condition screening,which was more suitable for continuous bioreactor,was achieved at a half shorter time,64-times higher throughput,and less reagent consumption.It could be used to establish chemostat cultures in continuous bioreactors which can dramatically accelerate the development of renewable and sustainable algal for CO_(2)fixation and biosynthesis and related systems for advanced sustainable energy,food,pharmacy,and agriculture with enormous social and ecological benefits.