Located in southwestern China, Jiuzhaigou National Park is one of the most popular tourism destinations in China, famous for its unique aquatic ecosystems and beautiful forests. However, plants in the park may be at h...Located in southwestern China, Jiuzhaigou National Park is one of the most popular tourism destinations in China, famous for its unique aquatic ecosystems and beautiful forests. However, plants in the park may be at high ozone risk as a result of the intensive use of diesel tour buses in the park. In addition, Jiuzhaigou is close to a region with relatively high regional anthropogenic NOn emissions. During the growing season, also the peak season of tourism, we measured ozone concentration at two sites within the Park and these were： Jiuzhaigou Bureau （JB） and Long Lake （LL）. The results indicate that ozone concentrations were not high enough to cause foliar injury during the monitoring period, although the risk of ozone to plants was higher in spring than in summer and autumn. Diurnal ozone cycles at JB and LL displayed significantly higher ozone concentrations in the daytime than in the nighttime, suggesting photochemical production of ozone during the day and ozone deposition during the night as a result of the nocturnal boundary layer. In parallel with the seasonal change of background surface ozone in the Northern Hemisphere, maximum daily 8-h average ozone concentration （MDA8） and daily ozone concentration decreased from spring to autumn at the two sites. This temporal variation in Jiuzhaigou wasmost likely associated with the downward mixing of ozone-rich air from the free troposphere, because all the high-ozone events （MDA8 〉 70.0 ppb） were observed in spring and ozone-rich air from the free troposphere was the dominant cause. In summary, our data suggest that ozone concentrations in Jiuzhaigou were more affected by the regional-scale of background pattern in air quality and meteorological conditions than by local tourist activities.展开更多
Osteoarthritis(OA)is one of the most prevalent joint diseases with prominent symptoms affecting the daily life of millions of middle aged and elderly people.Despite this,there are no successful medical interventions t...Osteoarthritis(OA)is one of the most prevalent joint diseases with prominent symptoms affecting the daily life of millions of middle aged and elderly people.Despite this,there are no successful medical interventions that can prevent the progressive destruction of OA joints.The onset of pathological changes in OA is associated with deviant activity of mesenchymal stem cells(MSCs),the multipotent precursors of connective tissue cells that reside in joints.Current therapies for OA have resulted in poor clinical outcomes without repairing the damaged cartilage.Intra-articular delivery of culture-expanded MSCs has opened new avenues of OA treatment.Pre-clinical and clinical trials demonstrated the feasibility,safety,and efficacy of MSC therapy.The Wnt/β-catenin,bone morphogenetic protein 2,Indian hedgehog,and Mitogen-activated protein kinase signaling pathways have been demonstrated to be involved in OA and the mechanism of action of MSC therapies.展开更多
基金funded by the International Program of the Ministry of Science and Technology of China (2010DFA91280) 111 Project(B08037)
文摘Located in southwestern China, Jiuzhaigou National Park is one of the most popular tourism destinations in China, famous for its unique aquatic ecosystems and beautiful forests. However, plants in the park may be at high ozone risk as a result of the intensive use of diesel tour buses in the park. In addition, Jiuzhaigou is close to a region with relatively high regional anthropogenic NOn emissions. During the growing season, also the peak season of tourism, we measured ozone concentration at two sites within the Park and these were： Jiuzhaigou Bureau （JB） and Long Lake （LL）. The results indicate that ozone concentrations were not high enough to cause foliar injury during the monitoring period, although the risk of ozone to plants was higher in spring than in summer and autumn. Diurnal ozone cycles at JB and LL displayed significantly higher ozone concentrations in the daytime than in the nighttime, suggesting photochemical production of ozone during the day and ozone deposition during the night as a result of the nocturnal boundary layer. In parallel with the seasonal change of background surface ozone in the Northern Hemisphere, maximum daily 8-h average ozone concentration （MDA8） and daily ozone concentration decreased from spring to autumn at the two sites. This temporal variation in Jiuzhaigou wasmost likely associated with the downward mixing of ozone-rich air from the free troposphere, because all the high-ozone events （MDA8 〉 70.0 ppb） were observed in spring and ozone-rich air from the free troposphere was the dominant cause. In summary, our data suggest that ozone concentrations in Jiuzhaigou were more affected by the regional-scale of background pattern in air quality and meteorological conditions than by local tourist activities.
文摘Osteoarthritis(OA)is one of the most prevalent joint diseases with prominent symptoms affecting the daily life of millions of middle aged and elderly people.Despite this,there are no successful medical interventions that can prevent the progressive destruction of OA joints.The onset of pathological changes in OA is associated with deviant activity of mesenchymal stem cells(MSCs),the multipotent precursors of connective tissue cells that reside in joints.Current therapies for OA have resulted in poor clinical outcomes without repairing the damaged cartilage.Intra-articular delivery of culture-expanded MSCs has opened new avenues of OA treatment.Pre-clinical and clinical trials demonstrated the feasibility,safety,and efficacy of MSC therapy.The Wnt/β-catenin,bone morphogenetic protein 2,Indian hedgehog,and Mitogen-activated protein kinase signaling pathways have been demonstrated to be involved in OA and the mechanism of action of MSC therapies.
