Nonlinear Conductivity and Space Charge Characteristics of SiC/Silicone Rubber Nanocomposites.

To achieve a preferable compatibility between liquid silicone rubber (LSR) and cable main insulation in a cable accessory, we developed SiC/LSR nanocomposites with a significantly higher conductivity nonlinearity than pure LSR, whilst representing a notable improvement in space charge characteristics. Space charge distributions in polarization/depolarization processes and surface potentials of SiC/LSR composites are analyzed to elucidate the percolation conductance and charge trapping mechanisms accounting for nonlinear conductivity and space charge suppression. It is verified that SiC/LSR composites with SiC content higher than 10 wt% represent an evident nonlinearity of electric conductivity as a function of the electric field strength. Space charge accumulations can be inhibited by filling SiC nanoparticles into LSR, as illustrated in both dielectric polarization and depolarization processes. Energy level and density of shallow traps increase significantly with SiC content, which accounts for expediting carrier hopping transport and surface charge decay. Finite-element multiphysics simulations demonstrate that nonlinear conductivity acquired by 20 wt% SiC/LSR nanocomposite could efficiently homogenize an electric field distributed in high-voltage direct current (HVDC) cable joints. Nonlinear conductivities and space charge characteristics of SiC/LSR composites discussed in this paper suggest a feasible modification strategy to improve insulation performances of direct current (DC) cable accessories.

Complete chloroplast genome of the grain Chenopodium quinoa Willd., an important economical and dietary plant.

The grain Chenopodium quinoa Willd. is the main traditional food of Inca aboriginal, which was a native grain in South American Andes Mountains, the edible and cultivation history of which has been more than five thousand years. In this study, we sequenced the complete chloroplast genome of C. quinoa on the Illumina platform by shotgun genome skimming method. The complete chloroplast genome of C. quinoa was 152,087 bp in length with the GC content 37.2%, which was comprised of a large single copy (LSC) region of 83,570 bp, a small single copy (SSC) region of 18,107 bp, and a pair of inverted repeats (IRA/IRB) of 25,205 bp. The chloroplast genome encoded 133 genes including 88 protein-coding genes, 37 tRNA genes and eight rRNA genes. Phylogenetic analysis constructed using the maximum likelihood (ML) method strongly supported the monophyly of each genus in the family Chenopodiaceae, and the genus Chenopodium is sister to Spinacia as a cluster, which closely grouped to Dysphania.