The characteristics of low frequency electrical noise, voltage current ( V I ) and electrical derivation for 980 nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditi...The characteristics of low frequency electrical noise, voltage current ( V I ) and electrical derivation for 980 nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low frequency electrical noise with surface non radiative current of devices is discussed. The results indicate the low frequency electrical noise of 980 nm DQWLs with high power is mainly 1/ f noise and has good relation with the device surface current at low injection.展开更多
Objective To describe a new noncontact balloon catheter mapping system and to assess the clinical utility of this system for guiding endocardial mapping and ablation of tachycardia.Methods Five patients with tachycard...Objective To describe a new noncontact balloon catheter mapping system and to assess the clinical utility of this system for guiding endocardial mapping and ablation of tachycardia.Methods Five patients with tachycardia underwent endocardial mapping and radiofrequency ablation using the noncontact balloon catheter mapping system. A 9 French, 64-electrode balloon catheter and a conventional 7 French electrode catheter for mapping and ablation were positioned in the same ventricular chamber. Ventricular three-dimensional geometry was established by the computerized mapping system. Using a boundary element inverse solution, 3360 virtual endocardial electrograms were computerized and used to derive isopotential maps. The earliest endocardial activation site, the exit site and the activation sequence of tachycardia or the critical isthmus of the reentry circuit were identified. Radiofrequency ablation with circular or linear lesion was performed at the target sites guided by the locator system.Results Six clinical types of tachycardia, 5 of which were ventricular tachycardia and one was concealed fasciculoventricular fiber mediated tachycardia, were induced by programmed stimulation. The mean cycle length of these tachycardias was 336.6±42.69 msec. The earliest activation site and the exit site of 5 mapped tachycardias were all identified using the system. One type of ventricular tachycardia was hemodynamically unstable and difficult to terminate, and could not be mapped. Among the 6 types of tachycardias, radiofrequency ablation was successful in 4. There was no complication during and after the procedure. During the mean follow-up of 6 months, no tachycardia recurred in the patients with a successful ablation.Conclusions The noncontact mapping system described in this study has advantage over conventional mapping techniques for refractory tachycardia. It is not only helpful for understanding the electrophysiologic mechanism of a complex case, but also suitable for mapping hemodynamically-intolerated and nonsustained ventricular tachycardia.展开更多
The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By usin...The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By using a hydrothermal ion-exchange method,we have successfully grown crystals of(Li_(1-x) Fe_x)OHFe Se. X-ray diffraction on the sample shows the single crystalline Pb O-type structure with the c-axis preferential orientation. Magnetic susceptibility and resistive measurements show an onset superconducting transition at around T c=38.3 K. Using the magnetization hysteresis loops and Bean critical state model, a large critical current J s is observed in low temperature region. The critical current density is suppressed exponentially with increasing magnetic field.Temperature dependencies of resistivity under various currents and fields are measured, revealing a robust superconducting current density and bulk superconductivity.展开更多
文摘The characteristics of low frequency electrical noise, voltage current ( V I ) and electrical derivation for 980 nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low frequency electrical noise with surface non radiative current of devices is discussed. The results indicate the low frequency electrical noise of 980 nm DQWLs with high power is mainly 1/ f noise and has good relation with the device surface current at low injection.
文摘Objective To describe a new noncontact balloon catheter mapping system and to assess the clinical utility of this system for guiding endocardial mapping and ablation of tachycardia.Methods Five patients with tachycardia underwent endocardial mapping and radiofrequency ablation using the noncontact balloon catheter mapping system. A 9 French, 64-electrode balloon catheter and a conventional 7 French electrode catheter for mapping and ablation were positioned in the same ventricular chamber. Ventricular three-dimensional geometry was established by the computerized mapping system. Using a boundary element inverse solution, 3360 virtual endocardial electrograms were computerized and used to derive isopotential maps. The earliest endocardial activation site, the exit site and the activation sequence of tachycardia or the critical isthmus of the reentry circuit were identified. Radiofrequency ablation with circular or linear lesion was performed at the target sites guided by the locator system.Results Six clinical types of tachycardia, 5 of which were ventricular tachycardia and one was concealed fasciculoventricular fiber mediated tachycardia, were induced by programmed stimulation. The mean cycle length of these tachycardias was 336.6±42.69 msec. The earliest activation site and the exit site of 5 mapped tachycardias were all identified using the system. One type of ventricular tachycardia was hemodynamically unstable and difficult to terminate, and could not be mapped. Among the 6 types of tachycardias, radiofrequency ablation was successful in 4. There was no complication during and after the procedure. During the mean follow-up of 6 months, no tachycardia recurred in the patients with a successful ablation.Conclusions The noncontact mapping system described in this study has advantage over conventional mapping techniques for refractory tachycardia. It is not only helpful for understanding the electrophysiologic mechanism of a complex case, but also suitable for mapping hemodynamically-intolerated and nonsustained ventricular tachycardia.
基金supported by the National Natural Science Foundation of China(Grant No.11534005)the Ministry of Science and Technology of China(Grant Nos.2011CBA00102 and 2012CB821403)
文摘The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By using a hydrothermal ion-exchange method,we have successfully grown crystals of(Li_(1-x) Fe_x)OHFe Se. X-ray diffraction on the sample shows the single crystalline Pb O-type structure with the c-axis preferential orientation. Magnetic susceptibility and resistive measurements show an onset superconducting transition at around T c=38.3 K. Using the magnetization hysteresis loops and Bean critical state model, a large critical current J s is observed in low temperature region. The critical current density is suppressed exponentially with increasing magnetic field.Temperature dependencies of resistivity under various currents and fields are measured, revealing a robust superconducting current density and bulk superconductivity.
