Excess activation and expression of large-conductance Ca^2＋-activated K^＋ channels（BKCa channels） may be an important mechanism for delayed neuronal death after cerebral ischemia/reperfusion injury. Electroacupunc...Excess activation and expression of large-conductance Ca^2＋-activated K^＋ channels（BKCa channels） may be an important mechanism for delayed neuronal death after cerebral ischemia/reperfusion injury. Electroacupuncture can regulate BKCa channels after cerebral ischemia/reperfusion injury, but the precise mechanism remains unclear. In this study, we established a rat model of cerebral ischemia/reperfusion injury. Model rats received electroacupuncture of 1 m A and 2 Hz at Shuigou（GV26） for 10 minutes, once every 12 hours for a total of six times in 72 hours. We found that in cerebral ischemia/reperfusion injury rats, ischemic changes in the cerebral cortex were mitigated after electroacupuncture. Moreover, BKCa channel protein and m RNA expression were reduced in the cerebral cortex and neurological function noticeably improved. These changes did not occur after electroacupuncture at a non-acupoint（5 mm lateral to the left side of Shuigou）. Thus, our findings indicate that electroacupuncture at Shuigou improves neurological function in rats following cerebral ischemia/reperfusion injury, and may be associated with down-regulation of BKCa channel protein and m RNA expression. Additionally, our results suggest that the Shuigou acupoint has functional specificity.展开更多
When two three-dimensional topological insulators （TIs） are brought close to each other with their surfaces aligned, the surfaces form a line junction. Similarly, three TI surfaces, not lying in a single plane, can ...When two three-dimensional topological insulators （TIs） are brought close to each other with their surfaces aligned, the surfaces form a line junction. Similarly, three TI surfaces, not lying in a single plane, can form an atomic-scale nanostep junction. In this paper, Andreev reflection in a TI-TI-superconductor nanostep junction is investigated theoretically. Be- cause of the existence of edge states along each line junction, the conductance for a nanostep junction is suppressed. When the incident energy （e） of an electron is larger than the superconductor gap （A）, the Andreev conductance in a step junction is less than unity while for a plane junction it is unity. The Andreev conductance is found to depend on the height of the step junction. The Andreev conductance exhibits oscillatory behavior as a function of the junction height with the amplitude of the oscillations remaining unchanged when e = 0, but decreasing for e = A, which is different from the case of the plane junction. The height of the step is therefore an important parameter for Andreev reflection in nanostep junctions, and plays a role similar to that of the delta potential barrier in normal metal-superconductor plane junctions.展开更多
La-based binary or ternary compounds have recently attracted a great deal of attention as a potential candidate to replace the currently used Hf-based dielectrics in future transistor and capacitor devices for sub-22 ...La-based binary or ternary compounds have recently attracted a great deal of attention as a potential candidate to replace the currently used Hf-based dielectrics in future transistor and capacitor devices for sub-22 generation. However,the hygroscopic nature of La2O3 hampers its application as dielectrics in electron devices. To cope with this challenge,ultraviolet（UV） ozone post treatment is proposed to suppress the moisture absorption in the H2O-based atomic layer deposition（ALD） La2O3/Al2O3 nanolaminates which is related to the residual hydroxyl/hydrogen groups after annealing.The x-ray photoelectron spectroscopy（XPS） and conductive atomic force microscopy（AFM） results indicate that the moisture absorption of the H2O-based ALD La2O3/Al2O3 nanolaminates is efficiently suppressed after 600？C annealing,and the electrical characteristics are greatly improved.展开更多
Current-voltage electrical characteristics of Er silicide/Si（001） nanocontacts are measured in situ in a scanning tunneling microscopy system. Introduced as a new technique to suppress surface leakage conduction on...Current-voltage electrical characteristics of Er silicide/Si（001） nanocontacts are measured in situ in a scanning tunneling microscopy system. Introduced as a new technique to suppress surface leakage conduction on Si（001）,a silver wetting layer is evaporated onto the substrate surface kept at room temperature with Er Si2 nanoislands already existing. The effects of the silver layer on the current-voltage characteristics of nanocontacts are discussed.Our experimental results reveal that the silver layer at coverage of 0.4–0.7 monolayer can suppress effectively the current contribution from the surface conduction path. After the surface leakage path of nanocontacts is obstructed, the ideality factor and the Schottky barrier height are determined using the thermionic emission theory, about 2 and 0.5 eV, respectively. The approach adopted here could shed light on the intrinsic transport properties of metal-semiconductor nanocontacts.展开更多
基金supported by the National Natural Science Foundation of China,No.81173339,81303020the Program for Changjiang Scholars and Innovative Research Team in University of Chinathe Key Project of the Natural Science Foundation of Tianjin of China,No.11JCZDJC19800
文摘Excess activation and expression of large-conductance Ca^2＋-activated K^＋ channels（BKCa channels） may be an important mechanism for delayed neuronal death after cerebral ischemia/reperfusion injury. Electroacupuncture can regulate BKCa channels after cerebral ischemia/reperfusion injury, but the precise mechanism remains unclear. In this study, we established a rat model of cerebral ischemia/reperfusion injury. Model rats received electroacupuncture of 1 m A and 2 Hz at Shuigou（GV26） for 10 minutes, once every 12 hours for a total of six times in 72 hours. We found that in cerebral ischemia/reperfusion injury rats, ischemic changes in the cerebral cortex were mitigated after electroacupuncture. Moreover, BKCa channel protein and m RNA expression were reduced in the cerebral cortex and neurological function noticeably improved. These changes did not occur after electroacupuncture at a non-acupoint（5 mm lateral to the left side of Shuigou）. Thus, our findings indicate that electroacupuncture at Shuigou improves neurological function in rats following cerebral ischemia/reperfusion injury, and may be associated with down-regulation of BKCa channel protein and m RNA expression. Additionally, our results suggest that the Shuigou acupoint has functional specificity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204065 and 11474085)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2013205168 and A2014205005)
文摘When two three-dimensional topological insulators （TIs） are brought close to each other with their surfaces aligned, the surfaces form a line junction. Similarly, three TI surfaces, not lying in a single plane, can form an atomic-scale nanostep junction. In this paper, Andreev reflection in a TI-TI-superconductor nanostep junction is investigated theoretically. Be- cause of the existence of edge states along each line junction, the conductance for a nanostep junction is suppressed. When the incident energy （e） of an electron is larger than the superconductor gap （A）, the Andreev conductance in a step junction is less than unity while for a plane junction it is unity. The Andreev conductance is found to depend on the height of the step junction. The Andreev conductance exhibits oscillatory behavior as a function of the junction height with the amplitude of the oscillations remaining unchanged when e = 0, but decreasing for e = A, which is different from the case of the plane junction. The height of the step is therefore an important parameter for Andreev reflection in nanostep junctions, and plays a role similar to that of the delta potential barrier in normal metal-superconductor plane junctions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61604016 and 51501017)the Fundamental Research Funds for the Central Universities,China(Grant No.310831161003)
文摘La-based binary or ternary compounds have recently attracted a great deal of attention as a potential candidate to replace the currently used Hf-based dielectrics in future transistor and capacitor devices for sub-22 generation. However,the hygroscopic nature of La2O3 hampers its application as dielectrics in electron devices. To cope with this challenge,ultraviolet（UV） ozone post treatment is proposed to suppress the moisture absorption in the H2O-based atomic layer deposition（ALD） La2O3/Al2O3 nanolaminates which is related to the residual hydroxyl/hydrogen groups after annealing.The x-ray photoelectron spectroscopy（XPS） and conductive atomic force microscopy（AFM） results indicate that the moisture absorption of the H2O-based ALD La2O3/Al2O3 nanolaminates is efficiently suppressed after 600？C annealing,and the electrical characteristics are greatly improved.
基金Supported by the National Natural Science Foundation of China under Grant No 11374058
文摘Current-voltage electrical characteristics of Er silicide/Si（001） nanocontacts are measured in situ in a scanning tunneling microscopy system. Introduced as a new technique to suppress surface leakage conduction on Si（001）,a silver wetting layer is evaporated onto the substrate surface kept at room temperature with Er Si2 nanoislands already existing. The effects of the silver layer on the current-voltage characteristics of nanocontacts are discussed.Our experimental results reveal that the silver layer at coverage of 0.4–0.7 monolayer can suppress effectively the current contribution from the surface conduction path. After the surface leakage path of nanocontacts is obstructed, the ideality factor and the Schottky barrier height are determined using the thermionic emission theory, about 2 and 0.5 eV, respectively. The approach adopted here could shed light on the intrinsic transport properties of metal-semiconductor nanocontacts.
