Vacuum residue (VR) upgrading was conducted in the environment of supercritical water (SCW) without oxygen addition in an attempt to yield a maximum of light oil. Simulated distillation of the liquid products from a set of orthogonal experiments shows that temperature should not be too high to restrict coke formation, and the most beneficial condition is found at (1) 420 °C for the temperature, (2) 0.15 g/cm3 for the water density, (3) 2 g/g for the H2O/oil ratio, and (4) 1 h for the reaction time. A simultaneous increase of the water density and H2O/oil would significantly improve the cracking behavior and the yield in light oil. Scattered coke particles between 10 and 100 μm were generated from VR cracking, which suggests the dispersion effect of SCW. The infrared spectrum analysis has indicated an increase in the H/C atomic ratio in the liquid product, which implies that hydrogen is generated from the condensation reactions rather than from water because no oxygen-containing group was detected.
For the accurate identification of medicinal licorice species, nucleotide sequences of four types of DNA regions were researched for 205 specimens, including three species used as licorice: Glycyrrhiza uralensis, Glycyrrhiza glabra, and Glycyrrhiza inflata. The four DNA regions were the internal transcribed spacer (ITS) on nuclear ribosomal DNA, the rbcL gene, the matK gene, and the trnH-psbA intergenic region on chloroplast DNA (cpDNA). Ten genotypes were consequently recognized as combinations of the sequence data obtained from the four DNA regions. Species-specific genotypes were defined from the frequency of the appearance of species in each genotype and from the phylogenetic relationships of the 10 genotypes. This revealed the possibility of identifying licorice species based on the 10 genotypes. Next, comparison of species identifications by each DNA region suggested that efficient identification of licorice species is possible using the genetic information obtained from the ITS and trnH-psbA intergenic region. Additionally, concerning the phylogenetic relationships of the Glycyrrhiza species used as licorice, it is suggested from the genetic information of the four types of DNA regions that G. glabra is more closely related to G. inflata than to G. uralensis. In the G. uralensis examined, four genotypes were recognized as intra specific variations. The appearance frequency of each genotype in G. uralensis differed according to the area in China. G. uralensis may have expanded its distribution areas from western to eastern China because many licorices with the phylogenetic ancestral genotype were observed in western areas, while many with the derivative genotype were observed in eastern areas.
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