Nano-sized graphene flakes: insights from experimental synthesis and first principles calculations.

In this study, we proposed a cost-effective method for preparing graphene nano-flakes (GNFs) derived from carbon nanotubes (CNTs) via three steps (pressing, homogenization and sonication exfoliation processes). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), laser scattering, as well as ultraviolet-visible and photoluminescence (PL) measurements were carried out. The results indicated that the size of as-synthesized GNFs was approximately 40-50 nm. Furthermore, we also used first principles calculations to understand the transformation from CNTs to GNFs from the viewpoints of the edge formation energies of GNFs in different shapes and sizes. The corresponding photoluminescence measurements of GNFs were carried out in this work.

Functional characterization of Nicotiana benthamiana chromomethylase 3 in developmental programs by virus-induced gene silencing.

DNA methylation is essential for normal developmental processes and genome stability. DNA methyltransferases are key enzymes catalyzing DNA methylation. Chromomethylase (CMT) genes are specific to the plant kingdom and encode chromodomain-containing methyltransferases. However, the function of CMT genes in plants remains elusive. In this study, we isolated and characterized a CMT gene from Nicotiana benthamiana, designated NbCMT3. Alignment of the NbCMT3 amino acid sequence with other plant CMT3s showed conservation of bromo-adjacent-homology and methyltransferase catalytic domains. We investigated the expression patterns of NbCMT3 and its function in developmental programs. NbCMT3 was expressed predominately in proliferating tissues such as apical shoots and young leaves. NbCMT3 protein showed a nuclear location, which could be related to its putative cellular functions. Knocking down NbCMT3 expression by virus-induced gene silencing revealed its vital role(s) in leaf morphogenesis. The formation of palisade cells was defective in NbCMT3-silenced plants as compared with controls. NbCMT3 has a role in developmental programs.

Facile and Green Process to Synthesize a Three-Dimensional Network Few-Layer Graphene/Carbon Nanotube Composite for Electromagnetic Interference Shielding.

We propose an environmentally friendly liquid exfoliation approach and subsequent freeze-drying process for constructing a three-dimensional (3D) carbon-based network by using few-layer graphene (FLG) and carbon nanotubes (CNTs) for electromagnetic interference (EMI) shielding applications. Systematic characterizations-such as X-ray diffraction, scanning electron microscopy, and transmission electron microscopy-as well as Raman characterization and EMI shielding tests were performed. The results indicated that the as-synthesized 3D-FLG/CNT composite obtained through the freeze-drying process exhibited excellent electromagnetic interference shielding. The shielding effect of FLG could be improved from 15 to 22 dB by introducing CNTs. The CNTs inhibited restacking of FLG in the structure. We also compared two drying processes: oven drying and freeze-drying. The freeze-drying technique markedly improved the shielding effect of FLG/CNTs from 22 to 36 dB. The composition-optimized 3D-FLG/CNT composite could be a candidate material for use in EMI shielding.

Phellodendron chinense Schneid: A novel yellow-emitting luminescent material for white light-emitting diodes.

To facilitate the next generation of environmental material for white light emitting diodes, the discovery of natural luminesce is essential. In this study, we disclose a rare-earth free and yellow-emission phosphor, Phellodendron, which could be both excited by near ultraviolet light and blue light. The new yellow phosphor is obtained by extraction of Phellodendron chinense Schneid. The emission wavelength, full width at half maximum and CIE coordinates of extracted Phellodendron are 540 nm, 120 nm and (0.41, 0.55), respectively. The corresponding luminescent properties of Phellodendron are characterized by PL, PLE, reflection spectra, FITR and decay lifetime. Surprising thing is luminous intensity of Phellodendron phosphors excited at 380 nm was stronger than YAG:Ce phosphor by more than 139%. In addition, we firstly introduce the yellow phosphor in white LED fabrication by combining blue chip and Y3Al5O12:Ce3+ phosphor, to create warm white. For comparison, red-emission CaAlSiN3:Eu2+ phosphors are also introduced for LED package tests. The results demonstrate that Phellodendron is a potential candidate for white LED applications.