Based on the action mechanism of linear shaped charge（ LSC ）, penetration performance of LSC on rock was studied. The optimal standoff and the vertex angle of LSC were studied and determined by lab experiments. Thro...Based on the action mechanism of linear shaped charge（ LSC ）, penetration performance of LSC on rock was studied. The optimal standoff and the vertex angle of LSC were studied and determined by lab experiments. Through cutting sand-cement grout samples, the spacing interval of boreholes can approach 17.5 times of the bore-hole＇ s diameter, and the result of the directional expansion of crack is satisfactory. The result of field experiment indicates cutting effect is very good, the ruggedness in fracture plane is less than 50 mm, the rate of half-hole marks is nearly 100 % , and the crack inspection shows that there is no damage in the internal of the cutting part. All these suggest that the orientation fracture blasting with LSC is a good means in directional fracture controlled blasting and is worth popularizing widely.展开更多
Understanding how the growth of two key native grass species of the Northern Great Plains （Western wheatgrass and blue grama） may be affected under drought and nitrogen deficiency is essential for future management ...Understanding how the growth of two key native grass species of the Northern Great Plains （Western wheatgrass and blue grama） may be affected under drought and nitrogen deficiency is essential for future management of these grasslands. The random complete block experimental design greenhouse study examined the effects of water and N addition on above-ground and below-ground harvested biomass of C3 （Western wheatgrass, WWG） and C4 （blue grama, BG） grass species for the purpose of gaining better understanding of drought responses for these two species. Compared with well-watered treatment （field capacity）, two water limited treatments （70% and 85% field capacity） decreased plant above- and below-ground biomass （WWG and BG）. For two N treatments （no N added, addition of 100 mg N kg^-1soil）, addition of N significantly improved plant above- and below-ground biomass of WWG and BG under water field capacity. Both above- and below-ground biomass of the two grass species increased linearly with increasing water supplied, but above- and below-ground biomass of WWG was always lower than BG for the same treatments （water or N addition）. The results demonstrated that BG seedlings had better adaptation than WWG to deal with the imposed drought or N deficient conditions.展开更多
Oiltea camellia （Camellia oleifera Abel.）, an aluminium （Al） hyperaccumulator, grows well on acid soils in tropical or subtropical areas. In this study, the growth of oiltea camellia in response to Al application ...Oiltea camellia （Camellia oleifera Abel.）, an aluminium （Al） hyperaccumulator, grows well on acid soils in tropical or subtropical areas. In this study, the growth of oiltea camellia in response to Al application and the characteristics of Al uptake and accumulation were investigated using laboratory and field experiments. The growth of oiltea camellia seedlings in the nutrient solution tended to be stimulated by addition of Al. Results of the field experiment showed that oiltea camellia accumulated 11 000 mg kg-1 Al in leaves within 10 months, and the average rate of Al accumulation in new leaves was about 1100 mg kg-1 month-1; however, the monthly rate varied and was highest in spring and autumn. The results of the laboratory experiment on Al uptake by oiltea camellia seedlings in CaC12 solutions with various forms of Al showed that large amounts of Al supplied as Al3＋ and Al complexes Al-malate （1：1） and Al-F （1：1） were infiuxed into oiltea camellia roots, whereas Al supplied as Al-citrate （1：1）, Al-F （1：6）, Al-oxalate （1：3）, and Al-oxalate （1：1） complexes exhibited low affinity to oiltea camellia roots. The kinetics of Al3＋ cumulative uptake in excised roots and intact plants showed a biphasic pattern, with an initial rapid phase followed by a slow phase. The Al cumulative uptake was unaffected by low temperature, which indicated that Al uptake in oiltea camellia was a passive process. The efficient influx of Al into the roots and the high transport rate in specific seasons were presumed to account for the plentiful Al accumulation in leaves of oiltea camellia.展开更多
文摘Based on the action mechanism of linear shaped charge（ LSC ）, penetration performance of LSC on rock was studied. The optimal standoff and the vertex angle of LSC were studied and determined by lab experiments. Through cutting sand-cement grout samples, the spacing interval of boreholes can approach 17.5 times of the bore-hole＇ s diameter, and the result of the directional expansion of crack is satisfactory. The result of field experiment indicates cutting effect is very good, the ruggedness in fracture plane is less than 50 mm, the rate of half-hole marks is nearly 100 % , and the crack inspection shows that there is no damage in the internal of the cutting part. All these suggest that the orientation fracture blasting with LSC is a good means in directional fracture controlled blasting and is worth popularizing widely.
文摘Understanding how the growth of two key native grass species of the Northern Great Plains （Western wheatgrass and blue grama） may be affected under drought and nitrogen deficiency is essential for future management of these grasslands. The random complete block experimental design greenhouse study examined the effects of water and N addition on above-ground and below-ground harvested biomass of C3 （Western wheatgrass, WWG） and C4 （blue grama, BG） grass species for the purpose of gaining better understanding of drought responses for these two species. Compared with well-watered treatment （field capacity）, two water limited treatments （70% and 85% field capacity） decreased plant above- and below-ground biomass （WWG and BG）. For two N treatments （no N added, addition of 100 mg N kg^-1soil）, addition of N significantly improved plant above- and below-ground biomass of WWG and BG under water field capacity. Both above- and below-ground biomass of the two grass species increased linearly with increasing water supplied, but above- and below-ground biomass of WWG was always lower than BG for the same treatments （water or N addition）. The results demonstrated that BG seedlings had better adaptation than WWG to deal with the imposed drought or N deficient conditions.
基金Supported by the National Natural Science Foundation of China (Nos.40901139, 41025005, and 30821140538)the Knowledge Innovation Program of the Chinese Academy of Sciences (No.ISSASIP0708)
文摘Oiltea camellia （Camellia oleifera Abel.）, an aluminium （Al） hyperaccumulator, grows well on acid soils in tropical or subtropical areas. In this study, the growth of oiltea camellia in response to Al application and the characteristics of Al uptake and accumulation were investigated using laboratory and field experiments. The growth of oiltea camellia seedlings in the nutrient solution tended to be stimulated by addition of Al. Results of the field experiment showed that oiltea camellia accumulated 11 000 mg kg-1 Al in leaves within 10 months, and the average rate of Al accumulation in new leaves was about 1100 mg kg-1 month-1; however, the monthly rate varied and was highest in spring and autumn. The results of the laboratory experiment on Al uptake by oiltea camellia seedlings in CaC12 solutions with various forms of Al showed that large amounts of Al supplied as Al3＋ and Al complexes Al-malate （1：1） and Al-F （1：1） were infiuxed into oiltea camellia roots, whereas Al supplied as Al-citrate （1：1）, Al-F （1：6）, Al-oxalate （1：3）, and Al-oxalate （1：1） complexes exhibited low affinity to oiltea camellia roots. The kinetics of Al3＋ cumulative uptake in excised roots and intact plants showed a biphasic pattern, with an initial rapid phase followed by a slow phase. The Al cumulative uptake was unaffected by low temperature, which indicated that Al uptake in oiltea camellia was a passive process. The efficient influx of Al into the roots and the high transport rate in specific seasons were presumed to account for the plentiful Al accumulation in leaves of oiltea camellia.
