多孔电磁波吸收材料

近年来,通过改善孔结构来提升材料的电磁波吸收性能成为研究热点。多孔结构既有利于电磁波进入材料的内部,又能有效地调整材料的电磁参数,提高材料与电磁波间的阻抗匹配,进而增大材料对电磁波的吸收;此外,在电磁波吸收材料中生成的不同尺度的孔隙可以对入射电磁波产生多重散射和反射,延长其传播路径从而增加了损耗过程;同时,多孔材料的相对密度小,为许多性能高但受限于密度太大而不能在电磁波吸收领域高效应用的材料提供了解决问题的途径。基于此,本文综述了零维和三维多孔电磁波吸收材料(PEMAM)的研究现状及亟待解决的问题,同时也展望了多孔电磁波吸收材料未来可能的研究热点及发展方向。

Defect Engineering in g‑C_(3)N_(4)Quantum‑Dot‑Modified TiO_(2)Nanofiber:Uncovering Novel Mechanisms for the Degradation of Tetracycline in Coexistence with Cu^(2+)

Herein,g-C_(3)N_(4)quantum-dot-modified TiO_(2)nanofibers were fabricated and used as an efficient photocatalyst for the investigation of the influence of Cu^(2+)and the interaction mechanism between Cu^(2+)and surface defects in tetracycline degradation.Results showed that the effect of Cu^(2+)switched from promoting to inhibiting the tetracycline degradation as the amount of Cu^(2+)accumulated on the catalyst surface increased.The introduction of surface defects can prevent the inhibiting effect of Cu^(2+),resulting in the more complete degradation of tetracycline in contrast to the non-defective sample.Theoretical calculations further revealed that the defects can be used to tune the conduction band of the composite,inducing the reduction reaction of Cu^(2+)and inhibiting the accumulation of Cu on the surface of catalysts.Moreover,the Cu introduced to the catalyst surface provided new active sites,thereby promoting photocatalytic degradation.These findings provide new insights into the design of advanced fiber materials for water purification in complex environments.

The alteration in the architecture of a T-DNA insertion rice mutant osmtd1 is caused by up-regulation of Micro RNA156f

Plant architecture is an important factor for crop production. Some members of microRNA156 (miR156) and their target genes SQUAMOSA Promoter-Binding Protein-Like (SPL) were identified to play essential roles in the establishment of plant architecture. However, the roles and regulation of miR156 is not well understood yet. Here, we identified a T-DNA insertion mutant Osmtd1 (Oryza sativa multi-tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T-DNA insertion in Osmtd1. Further analysis revealed that the T-DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and OsmiR156f was significantly upregulated in Osmtd1. Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of OsmiR156f in wild-type rice phenocopied Osmtd1. We showed that the expression of OsSPL3, OsSPL12, and OsSPL14 were significantly downregulated in Osmtd1 or OsmiR156f overexpressed lines, indicating that OsSPL3, OsSPL12, and OsSPL14 were possibly direct target genes of OsmiR156f. Our results suggested that OsmiR156f controlled plant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.

Arabidopsis transcription factor TCP4 represses chlorophyll biosynthesis to prevent petal greening

Green petals pose a challenge for pollinators to distinguish flowers from leaves,but they are valuable as a specialty flower trait.However,little is understood about the molecular mechanisms that underlie the development of green petals.Here,we report that CINCINNATA(CIN)-like TEOSINTE BRANCHED 1/CYCLOIDEA/PCF(TCP)proteins play key roles in the control of petal color.The septuple tcp2/3/4/5/10/13/17 mutant produced flowers with green petals due to chlorophyll accumulation.Expression of TCP4 complemented the petal phenotype of tcp2/3/4/5/10/13/17.We found that chloroplasts were converted into leucoplasts in the distal parts of wild-type petals but not in the proximal parts during flower development,whereas plastid conversion was compromised in the distal parts of tcp2/3/4/5/10/13/17 petals.TCP4 and most CIN-like TCPs were predominantly expressed in distal petal regions,consistent with the green–white pattern in wild-type petals and the petal greening observed in the distal parts of tcp2/3/4/5/10/13/17 petals.RNA-sequencing data revealed that most chlorophyll biosynthesis genes were downregulated in the white distal parts of wild-type petals,but these genes had elevated expression in the distal green parts of tcp2/3/4/5/10/13/17 petals and the green proximal parts of wild-type petals.We revealed that TCP4 repressed chlorophyll biosynthesis by directly binding to the promoters of PROTOCHLOROPHYLLIDE REDUCTASE(PORB),DIVINYL REDUCTASE(DVR),and SUPPRESSOR OF OVEREXPRESSION OF CO 1(SOC1),which are known to promote petal greening.We found that the conversion of chloroplasts to leucoplasts and the green coloration in the proximal parts of petals appeared to be conserved among plant species.Our findings uncover a major molecular mechanism that underpins the formation of petal color patterns and provide a foundation for the breeding of plants with green flowers.