Thermotropic liquid crystalline with epoxy groups grafted graphene oxide (LCE-g-GO) was synthesized by graphene oxide (GO), hexamethylene diisocyanate (HDI), and 4,49-bis-(2-hydroxyhexoxy) biphenyl (BP 2 ) by using pyridine and dibutyltin dilaurate as catalyst and dimethylformamide (DMF) as solvent. In this work, the LCE-g-GO nanosheets were characterized by Fourier transform infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and polarizing optical microscopy (POM). The epoxy nanocomposites were fabricated by incorporating different LCE-g-GO loading using cast molding method. The results revealed that the incorporation of the LCE-g-GO resulted in a significant improvement in thermal and mechanical properties. The epoxy nanocomposite with 5 wt% LCE-g-GO produced an increase in the temperature for 5 wt% weight loss (T 5% ) by 47 uC and glass transition temperature (T g ) by 14 uC when compared with the neat epoxy. Moreover, at the addition of 5 wt% LCE-g-GO, the impact strength of the epoxy nanocomposite is 35.06 kJ m 22 , which is 2 times higher than that of the neat epoxy resin (17.49 kJ m 22 ). Meanwhile, the tensile strength of the nanocomposite is significantly increased to 92.5 MPa from 54.3 MPa, while the elongation at break is also increased to 42.9% from 25.7% of the neat epoxy, respectively. Therefore, the presence of the LCE-g-GO in the epoxy matrix could make epoxy not only stronger but also tougher.
The Jinchuan yak is a new yak population identified in Sichuan, China. This population has a special anatomical characteristic: an additional pair of ribs compared with other yak breeds. The genetic structure of this population is unknown. In the present study, we investigated the maternal phylogeny of this special yak population using the mitochondrial DNA variation. A total of 23 Jinchuan yaks were sequenced for a 823-bp fragment of D-loop control region and three individuals were sequenced for the whole mtDNA genome with a length of 16,371-bp. To compare with the data from other yaks, we extracted sequence data from Genebank, including D-loop of 398 yaks (from 12 breeds) and 55 wild yaks, and whole mitochondrial genomes of 53 yaks (from 12 breeds) and 21 wild yaks. A total of 127 haplotypes were defined, based on the D-loop data. Thirteen haplotypes were defined from 23 mtDNA D-loop sequences of Jinchuan yaks, six of which were shared only by Jinchuan, and one was shared by Jinchuan and wild yaks. The Jinquan yaks were found to carry clades A and B from lineage I and clade C of lineage II, respectively. It was also suggested that the Jinchuan population has no distinct different phylogenetic relationship in maternal inheritance with other breeds of yak. The highly haplotype diversity of the Pali breed, Jinchuan population, Maiwa breed and Jiulong breed suggested that the yak was first domesticated from wild yaks in the middle Himalayan region and the northern Hengduan Mountains. The special anatomic characteristic that we found in the Jinchuan population needs further studies based on nuclear data.
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