Predicting the cutter consumption and the exact time to replace the worn-out cutters in tunneling projects constructed with tunnel boring machine(TBM) is always a challenging issue. In this paper, we focus on the anal...Predicting the cutter consumption and the exact time to replace the worn-out cutters in tunneling projects constructed with tunnel boring machine(TBM) is always a challenging issue. In this paper, we focus on the analyses of cutter motion in the rock breaking process and trajectory of rock breaking point on the cutter edge in rocks. The analytical expressions of the length of face along which the breaking point moves and the length of spiral trajectory of the maximum penetration point are derived. Through observation of rock breaking process of disc cutters as well as analysis of disc rock interaction, the following concepts are proposed: the arc length theory of predicting wear extent of inner and center cutters, and the spiral theory of predicting wear extent of gage and transition cutters. Data obtained from5621 m-long Qinling tunnel reveal that among 39 disc cutters, the relative errors between cumulatively predicted and measured wear values for nine cutters are larger than 20%, while approximately 76.9% of total cutters have the relative errors less than 20%. The proposed method could offer a new attempt to predict the disc cutter's wear extent and changing time.展开更多
Silicate solubilizing bacteria (SSB) can play an efficient role in soil by solubilizing insoluble forms of silicates. In addition to this some SSB can also solubilize potassium and phosphates, hence increasing soil fe...Silicate solubilizing bacteria (SSB) can play an efficient role in soil by solubilizing insoluble forms of silicates. In addition to this some SSB can also solubilize potassium and phosphates, hence increasing soil fertility and enhancing plant defense mechanisms. A total of 111 bacterial strains were isolated from various habitats of Pakistan and screened for solubilization of silicate, phosphate and potassium on respective media. Out of these, 35 bacterial isolates were capable of solubilizing either silicate, phosphate or potassium. Amongst these 7 bacterial isolates were capable of solubilizing all three minerals tested. The highest silicate (zone diameter 54 mm) and phosphate solubilization (zone diameter 55 mm) was observed for bacterial isolate NR-2 while the highest potassium solubilization was observed for NE-4b (zone diameter 11 mm). Dual culture antagonistic assays were carried out by using these bacterial isolates against four plant pathogenic fungi Magnaporthae grisae, Rhizoctonia solani, Altarnaria alternata and Macrophomina pheasolina. Mean zone of inhibition of these bacterial isolates against the four pathogenic fungi ranged between 4 mm to 39 mm. The largest zone of inhibition against all four bacterial strains was recorded for bacterial isolate NR-2 followed by NE-4b. These strains will be further investigated for their plant growth promoting activities in the future.展开更多
Leaf functional traits play a pivotal role in understanding the adaptive strategy of plants in extreme environments, as well as in assessing their potential distribution range sizes and extinction risks under global c...Leaf functional traits play a pivotal role in understanding the adaptive strategy of plants in extreme environments, as well as in assessing their potential distribution range sizes and extinction risks under global climate change. However, the response of leaf functional traits to aridity in drylands remains unclear for plants with different range sizes. To fill this gap, we measured 10 leaf functional traits of 152 plant species across 172 dryland sites in China, and classified these species as either narrow-(NRS) or wide-ranging species(WRS) based on worldwide occurrence data. Our results showed that the NRS generally occurred in more severe arid areas, and had higher leaf water content(LWC) than WRS at high aridity levels(aridity>0.8). The scaling exponents between leaf volume(LV) and leaf dry weight(LDW) at high aridity levels were 1 for WRS and 1.56 for NRS, indicating that LV increased at a faster rate than LDW and therefore enabled NRS to store more water than WRS. Using moving window analysis, the above scaling exponents increased in NRS and decreased in WRS with increasing aridity at high aridity levels. Moreover, NRS with higher LWC tended to be more abundant at high aridity levels. Our results highlighted that NRS had higher LWC than WRS under high aridity, conferring them with a key advantage in adapting to extreme arid environments. These findings suggest that NRS and WRS use distinct adaptive strategies to cope with aridity. In the conservation of NRS in drylands, enhancing leaf water storage capacity is of particular importance.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51475163)the National Hightech R&D Program of China(Grant No.2012AA041803)
文摘Predicting the cutter consumption and the exact time to replace the worn-out cutters in tunneling projects constructed with tunnel boring machine(TBM) is always a challenging issue. In this paper, we focus on the analyses of cutter motion in the rock breaking process and trajectory of rock breaking point on the cutter edge in rocks. The analytical expressions of the length of face along which the breaking point moves and the length of spiral trajectory of the maximum penetration point are derived. Through observation of rock breaking process of disc cutters as well as analysis of disc rock interaction, the following concepts are proposed: the arc length theory of predicting wear extent of inner and center cutters, and the spiral theory of predicting wear extent of gage and transition cutters. Data obtained from5621 m-long Qinling tunnel reveal that among 39 disc cutters, the relative errors between cumulatively predicted and measured wear values for nine cutters are larger than 20%, while approximately 76.9% of total cutters have the relative errors less than 20%. The proposed method could offer a new attempt to predict the disc cutter's wear extent and changing time.
文摘Silicate solubilizing bacteria (SSB) can play an efficient role in soil by solubilizing insoluble forms of silicates. In addition to this some SSB can also solubilize potassium and phosphates, hence increasing soil fertility and enhancing plant defense mechanisms. A total of 111 bacterial strains were isolated from various habitats of Pakistan and screened for solubilization of silicate, phosphate and potassium on respective media. Out of these, 35 bacterial isolates were capable of solubilizing either silicate, phosphate or potassium. Amongst these 7 bacterial isolates were capable of solubilizing all three minerals tested. The highest silicate (zone diameter 54 mm) and phosphate solubilization (zone diameter 55 mm) was observed for bacterial isolate NR-2 while the highest potassium solubilization was observed for NE-4b (zone diameter 11 mm). Dual culture antagonistic assays were carried out by using these bacterial isolates against four plant pathogenic fungi Magnaporthae grisae, Rhizoctonia solani, Altarnaria alternata and Macrophomina pheasolina. Mean zone of inhibition of these bacterial isolates against the four pathogenic fungi ranged between 4 mm to 39 mm. The largest zone of inhibition against all four bacterial strains was recorded for bacterial isolate NR-2 followed by NE-4b. These strains will be further investigated for their plant growth promoting activities in the future.
基金supported by the National Key Research and Development Program of China (2023YFF0805600)the National Natural Science Foundation of China (32225032, 31901087, 32001192)+3 种基金the Innovation Base Project (2021YFF0703904)Major Science and Technology Special Projects (23ZDKA0010, 23ZDNA009) of Gansu ProvinceNatural Science Foundation of Gansu Province (21JR1RA138, 22JR5RA525, 23JRRA1157)supported by the Guazhou Desert Ecosystem Field Observation Research Station。
文摘Leaf functional traits play a pivotal role in understanding the adaptive strategy of plants in extreme environments, as well as in assessing their potential distribution range sizes and extinction risks under global climate change. However, the response of leaf functional traits to aridity in drylands remains unclear for plants with different range sizes. To fill this gap, we measured 10 leaf functional traits of 152 plant species across 172 dryland sites in China, and classified these species as either narrow-(NRS) or wide-ranging species(WRS) based on worldwide occurrence data. Our results showed that the NRS generally occurred in more severe arid areas, and had higher leaf water content(LWC) than WRS at high aridity levels(aridity>0.8). The scaling exponents between leaf volume(LV) and leaf dry weight(LDW) at high aridity levels were 1 for WRS and 1.56 for NRS, indicating that LV increased at a faster rate than LDW and therefore enabled NRS to store more water than WRS. Using moving window analysis, the above scaling exponents increased in NRS and decreased in WRS with increasing aridity at high aridity levels. Moreover, NRS with higher LWC tended to be more abundant at high aridity levels. Our results highlighted that NRS had higher LWC than WRS under high aridity, conferring them with a key advantage in adapting to extreme arid environments. These findings suggest that NRS and WRS use distinct adaptive strategies to cope with aridity. In the conservation of NRS in drylands, enhancing leaf water storage capacity is of particular importance.
