[Water sources of dominant sand-binding plants in dry season in southern Horqin Sandy Land, China]. / 科尔沁沙地南缘主要固沙植物旱季水分来源.

It's important to explore the water sources of sand-binding plants and their relationship to reveal the mechanism underling species coexistence and vegetation stability. In the present study, 12 sand-binding species in two typical habitats (fixed dune and dune slack) in southern Horqin Sandy Land were selected. The δD and δ18O values of plant water, rain water, ground water and soil water were determined, and the percentages of soil water at different depths used by plants were calculated with the IsoSource model. Our results showed that the δD and δ18O values of stem water were significantly different among various life forms in both habitats except for those of trees and shrubs in dune slack. From trees to grass, the depth of soil water contributed to main water source of plant became shallower in dune slack: trees and shrubs mainly used soil water in 50-150 cm or 30-50 cm layer, subshrubs mainly used soil water in 10-30 cm layer while grass relied on soil water of 0-10 cm layer. Shrubs mainly used soil water of 0-30 cm layer and subshrubs mainly used soil water around 50 cm at fixed dune. This study indicated that in dry season plants at fixed dune are more dependent on soil water of 0-50 cm layer compared with those in dune slack. The water sources of sand-binding plants are correlated with plant life form and root distribution range, and the later might play a more important role.

Facile and efficient one-pot synthesis of 2-arylbenzoxazoles using hydrogen tetrachloroaurate as catalyst under oxygen atmosphere.

In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl(4).4H(2)O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant.