Objective To clarify the effects of repetitive transcranial magnetic stimulation (rTMS) on rat motor cortical excitabi- lity and neurofunction after cerebral ischemia-reperfusion injury. Methods After determined awake...Objective To clarify the effects of repetitive transcranial magnetic stimulation (rTMS) on rat motor cortical excitabi- lity and neurofunction after cerebral ischemia-reperfusion injury. Methods After determined awake resting motor threshold (MT) and motor evoked potentials (MEPs) of right hindlimbs, 20 Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) reperfusion injury, then rTMS were applied to rTMS group (n = 10) at different time, while control group (n = 10) received no stimulation. A week later, MT and MEPs were evaluated again, as well as neurological deficits and infarct volume. The effects of rTMS and MCAO reperfusion injury on these parameters were analyzed. Results After MCAO reperfusion, both MT level and neurological deficit scores increased, distinct focal infarction formed, and latency of MEP elongated. Compared with the control group, the increased extent of MT and neurological scores of rats receiving rTMS were significantly lower (P < 0.05), as well as the infarct volumes reduced significantly(P < 0.05). But MEP was not affected by rTMS obviously. There was a positive linear correlation between postinjury MT and infarct volume (r = 0.64, P < 0.05). Conclusion rTMS may facilitate neurofunction recovery after cerebral ischemia-reperfusion. Postinjury MT could provide prognostic information after MCAO reperfusion injury.展开更多
Modified cable bolts are commonly used in underground mines due to their superior performance in preventing bed separation when compared with plain strands. To better test the axial performance of a wide range of cabl...Modified cable bolts are commonly used in underground mines due to their superior performance in preventing bed separation when compared with plain strands. To better test the axial performance of a wide range of cable bolts,a new laboratory short encapsulation pull test(LSEPT) facility was developed. The facility simulates the interaction between cable bolts and surrounding rock mass,using artificial rock cylinders with a diameter of 300 mm in which the cable bolt is grouted. Furthermore,the joint where the load is applied is left unconstrained to allow shear slippage at the cable/grout or grout/rock interface.Based on this apparatus,a series of pull tests were undertaken using the MW9 modified bulb cable bolt.Various parameters including embedment length,test material strength and borehole size were evaluated. It was found that within a limited range of 360 mm,there is a linear relationship between the maximum bearing capacity of the cable bolt and embedment length. Beyond 360 mm,the peak capacity continues to rise but with a much lower slope. When the MW9 cable bolt was grouted in a weak test material,failure always took place along the grout/rock interface. Interestingly,increasing the borehole diameter from 42 to 52 m in weak test material altered the failure mode from grout/rock interface to cable/grout interface and improved the performance in terms of both peak and residual capacity.展开更多
文摘Objective To clarify the effects of repetitive transcranial magnetic stimulation (rTMS) on rat motor cortical excitabi- lity and neurofunction after cerebral ischemia-reperfusion injury. Methods After determined awake resting motor threshold (MT) and motor evoked potentials (MEPs) of right hindlimbs, 20 Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) reperfusion injury, then rTMS were applied to rTMS group (n = 10) at different time, while control group (n = 10) received no stimulation. A week later, MT and MEPs were evaluated again, as well as neurological deficits and infarct volume. The effects of rTMS and MCAO reperfusion injury on these parameters were analyzed. Results After MCAO reperfusion, both MT level and neurological deficit scores increased, distinct focal infarction formed, and latency of MEP elongated. Compared with the control group, the increased extent of MT and neurological scores of rats receiving rTMS were significantly lower (P < 0.05), as well as the infarct volumes reduced significantly(P < 0.05). But MEP was not affected by rTMS obviously. There was a positive linear correlation between postinjury MT and infarct volume (r = 0.64, P < 0.05). Conclusion rTMS may facilitate neurofunction recovery after cerebral ischemia-reperfusion. Postinjury MT could provide prognostic information after MCAO reperfusion injury.
文摘Modified cable bolts are commonly used in underground mines due to their superior performance in preventing bed separation when compared with plain strands. To better test the axial performance of a wide range of cable bolts,a new laboratory short encapsulation pull test(LSEPT) facility was developed. The facility simulates the interaction between cable bolts and surrounding rock mass,using artificial rock cylinders with a diameter of 300 mm in which the cable bolt is grouted. Furthermore,the joint where the load is applied is left unconstrained to allow shear slippage at the cable/grout or grout/rock interface.Based on this apparatus,a series of pull tests were undertaken using the MW9 modified bulb cable bolt.Various parameters including embedment length,test material strength and borehole size were evaluated. It was found that within a limited range of 360 mm,there is a linear relationship between the maximum bearing capacity of the cable bolt and embedment length. Beyond 360 mm,the peak capacity continues to rise but with a much lower slope. When the MW9 cable bolt was grouted in a weak test material,failure always took place along the grout/rock interface. Interestingly,increasing the borehole diameter from 42 to 52 m in weak test material altered the failure mode from grout/rock interface to cable/grout interface and improved the performance in terms of both peak and residual capacity.
