Thick GaN films were grown on GaN/sapphire template in a vertical HVPE reactor. Various material characterization techniques,including AFM, SEM, XRD, RBS/Channeling, CL, PL, and XPS, were used to characterize these Ga...Thick GaN films were grown on GaN/sapphire template in a vertical HVPE reactor. Various material characterization techniques,including AFM, SEM, XRD, RBS/Channeling, CL, PL, and XPS, were used to characterize these GaN epitaxial films. It was found that stepped/terraced structures appeared on the film surface,which were indicative of a nearly step-flow mode of growth for the HVPE GaN despite the high growth rate. A few hexagonal pits appeared on the surface, which have strong light emission. After being etched in molten KOH, the wavy steps disappeared and hexagonal pits with {1010} facets appeared on the surface. An EPD of only 8 ×10^6cm^-2 shows that the GaN film has few dislocations. Both XRD and RBS channeling indicate the high quality of the GaN thick films. Sharp band-edge emission with a full width at half maximum（FWHM）of 67meV was observed, while the yellow and infrared emissions were also found. These emissions are likely caused by native defects and C and O impurities.展开更多
In order to systematically investigate the chemical constituents of Citri Reticulatae Folium （leaves of ＇Fuju＇）, an analytical method that included high-performance liquid chromatography, diode array detection, el...In order to systematically investigate the chemical constituents of Citri Reticulatae Folium （leaves of ＇Fuju＇）, an analytical method that included high-performance liquid chromatography, diode array detection, electrospray ionization, and ion-trap time-of-flight mass spectrometry （HPLC-DAD-ESI-MSn） was used to separate and identify the individual chemical components of Citri Reticulatae Folium. As a result, 96 compounds were tentatively identified in this study： including 31 phenolic acids, 4 flavonoid aglycones, 6 flavonoid mono-O-glycosides, 10 flavonoid-O-diglycosides, 5 flavonoid mono-C-glycosides, 5 flavonoid di-C-glycosides, 6 flavonoid O,C-glycosides, 5 （3-hydroxy-3-methylglutaryl） glycosyl flavonoids, 1 flavan-3-ol, and 2 alkaloids. In addition, 21 polymethoxy flavonoids （PMFs） were identified in this paper. Among these compounds, 52 compounds, which were previously found in other Citrus plants, have been identified for the first time in Citri Reticulatae Folium. 15 compounds have not been previously found in the Citrus genus were identified. Moreover, 9 potentially new compounds have also been detected in this paper. This is the first report of the full characterization of chemical components of Citri Reticulatae Folium （leaves of＇Fuju＇） by HPLC-DAD-ESI-MSn.展开更多
The Pinus taiwanensis trees of a Chinese endemic species form pure forests at infertile sites in humid subtropical China, which can aid soil reservation and ecological resiliency at such sites. Herein, we used dendroc...The Pinus taiwanensis trees of a Chinese endemic species form pure forests at infertile sites in humid subtropical China, which can aid soil reservation and ecological resiliency at such sites. Herein, we used dendrochronological methods to investigate the growth patterns and their relationship with climate by analyzing 158 cores of 79 P. taiwanensis trees at 4 sites in their southernmost distribution in China's Mainland at Daiyun Mountain in Fujian Province. Tree growths at sites with favor- able conditions generally showed an age-related growth trend, which decreased from approximately 5 mm to 0.5 mm in about a century. Trees in moderately stressed environments established high growth in their juvenile periods but were highly suscep- tible to environmental stresses such as a sharp growth decline in the 1990s. The temperature in February and the moisture in July are the major limiting factors for most of the tree growths, except for a few extremely stressed P. taiwanensis trees. The growth of the dwarf P. taiwanensis trees, with all ring diameters of the first 20 years less than 4 ram, is mainly limited by the dry climate in May. Under the potential future warming trend, drought stress can be particularly threatening to these dwarf P. taiwanensis trees, which are likely to be the germplasm resources for this species in this region.展开更多
文摘Thick GaN films were grown on GaN/sapphire template in a vertical HVPE reactor. Various material characterization techniques,including AFM, SEM, XRD, RBS/Channeling, CL, PL, and XPS, were used to characterize these GaN epitaxial films. It was found that stepped/terraced structures appeared on the film surface,which were indicative of a nearly step-flow mode of growth for the HVPE GaN despite the high growth rate. A few hexagonal pits appeared on the surface, which have strong light emission. After being etched in molten KOH, the wavy steps disappeared and hexagonal pits with {1010} facets appeared on the surface. An EPD of only 8 ×10^6cm^-2 shows that the GaN film has few dislocations. Both XRD and RBS channeling indicate the high quality of the GaN thick films. Sharp band-edge emission with a full width at half maximum（FWHM）of 67meV was observed, while the yellow and infrared emissions were also found. These emissions are likely caused by native defects and C and O impurities.
文摘In order to systematically investigate the chemical constituents of Citri Reticulatae Folium （leaves of ＇Fuju＇）, an analytical method that included high-performance liquid chromatography, diode array detection, electrospray ionization, and ion-trap time-of-flight mass spectrometry （HPLC-DAD-ESI-MSn） was used to separate and identify the individual chemical components of Citri Reticulatae Folium. As a result, 96 compounds were tentatively identified in this study： including 31 phenolic acids, 4 flavonoid aglycones, 6 flavonoid mono-O-glycosides, 10 flavonoid-O-diglycosides, 5 flavonoid mono-C-glycosides, 5 flavonoid di-C-glycosides, 6 flavonoid O,C-glycosides, 5 （3-hydroxy-3-methylglutaryl） glycosyl flavonoids, 1 flavan-3-ol, and 2 alkaloids. In addition, 21 polymethoxy flavonoids （PMFs） were identified in this paper. Among these compounds, 52 compounds, which were previously found in other Citrus plants, have been identified for the first time in Citri Reticulatae Folium. 15 compounds have not been previously found in the Citrus genus were identified. Moreover, 9 potentially new compounds have also been detected in this paper. This is the first report of the full characterization of chemical components of Citri Reticulatae Folium （leaves of＇Fuju＇） by HPLC-DAD-ESI-MSn.
基金supported by the National Natural Science Foundation of China(Grant Nos.41471172U1405231+2 种基金and 41171039)Non-profit Research Funds of Fujian Province(Grant No.2014R1034-2)the Fellowship for Distinguished Young Scholars of Fujian Province(Grant No.2015J06008)in addition to students’training program of Fujian Province
文摘The Pinus taiwanensis trees of a Chinese endemic species form pure forests at infertile sites in humid subtropical China, which can aid soil reservation and ecological resiliency at such sites. Herein, we used dendrochronological methods to investigate the growth patterns and their relationship with climate by analyzing 158 cores of 79 P. taiwanensis trees at 4 sites in their southernmost distribution in China's Mainland at Daiyun Mountain in Fujian Province. Tree growths at sites with favor- able conditions generally showed an age-related growth trend, which decreased from approximately 5 mm to 0.5 mm in about a century. Trees in moderately stressed environments established high growth in their juvenile periods but were highly suscep- tible to environmental stresses such as a sharp growth decline in the 1990s. The temperature in February and the moisture in July are the major limiting factors for most of the tree growths, except for a few extremely stressed P. taiwanensis trees. The growth of the dwarf P. taiwanensis trees, with all ring diameters of the first 20 years less than 4 ram, is mainly limited by the dry climate in May. Under the potential future warming trend, drought stress can be particularly threatening to these dwarf P. taiwanensis trees, which are likely to be the germplasm resources for this species in this region.
