GaN-based p-channel heterostructure field-effect transistors(p-HFETs)face significant constraints on on-state currents compared with n-channel high electron mobility transistors.In this work,we propose a novel double ...GaN-based p-channel heterostructure field-effect transistors(p-HFETs)face significant constraints on on-state currents compared with n-channel high electron mobility transistors.In this work,we propose a novel double heterostructure which introduces an additional p-GaN insertion layer into traditional p-HFETs.The impact of the device structure on the hole densities and valence band energies of both the upper and lower channels is analyzed by using Silvaco TACD simulations,including the thickness of the upper AlGaN layer and the doping impurities and concentration in the GaN buffer layer,as well as the thickness and Mg-doping concentration in the p-GaN insertion layer.With the help of the p-GaN insertion layer,the C-doping concentration in the GaN buffer layer can be reduced,while the density of the two-dimensional hole gas in the lower channel is enhanced at the same time.This work suggests that a double heterostructure with a p-GaN insertion layer is a better approach to improve p-HFETs compared with those devices with C-doped buffer layer alone.展开更多
Objective: To investigate the clinical effect of liposuction combined with subareolar incision glandectomy in the treatment of Simon Grade Ⅲ adipo-glandular gynecomastia (GYN). Methods: From March 2021 to March 2022,...Objective: To investigate the clinical effect of liposuction combined with subareolar incision glandectomy in the treatment of Simon Grade Ⅲ adipo-glandular gynecomastia (GYN). Methods: From March 2021 to March 2022, the data of patients with Simon Grade Ⅲ adipo-glandular GYN treated by liposuction combined with glandectomy in the Department of Plastic Surgery, Zhongshan Hospital Affiliated to Dalian University and Henan Plastic Surgery and Aesthetic Hospital were retrospectively analyzed. Based on the medical records, color ultrasound was performed on the patient’s breast before surgery, which was determined to be GYN (more than 50% glandular tissue). A 3 mm long incision was made at the lower boundary of the surgical range, through which the adipose tissue in the hypertrophic region of the breast was repeatedly aspirated until a satisfactory thickness was achieved. The residual glandular tissue was removed by a semicircular arc incision under the areola, and then the areola incision was sutured in position. The blood flow, sensation, and wound healing of bilateral nipples and areola were observed after surgery, and the morphology of bilateral thorax and scar of incision were followed up. Results: A total of 15 GYN patients aged 18 to 35 years with body mass index of 23.8 to 26.5 kg/m2 (mean = 24.8 kg/m2) were included in this study. The average intraoperative liposuction volume of unilateral breast was 170 mL (150-200 mL), the average glandectomy volume was 115 g (95-125 g), and the average blood loss was about 40 mL (15-75 mL). Postoperative hypertrophic breast volume decreased significantly, and no complications such as hematoma, infection, skin ischemic necrosis, or sensory disturbance occurred in the nipple and areola, during the healing process. The patients were followed up for 3 to 6 months, and the bilateral thorax was smooth, symmetrical, and natural in contour. The incision was concealed, and the scar was not obvious. Conclusion: Liposuction combined with subareolar incision glandectomy in the treatment of Simon Grade Ⅲ adipo-glandular GYN is safe. The postoperative chest contour is smooth and natural, and the scar is small and invisible, which achieves good aesthetics.展开更多
目的探讨不同入路行双平面假体隆乳术的效果。方法回顾性分析2020年1月—2023年1月新乡市中心医院收治的629例行双平面假体隆乳术患者的临床资料,按其手术入路的不同将其分为2组,其中经乳晕入路行手术的329例患者纳入对照组,经腋窝入路...目的探讨不同入路行双平面假体隆乳术的效果。方法回顾性分析2020年1月—2023年1月新乡市中心医院收治的629例行双平面假体隆乳术患者的临床资料,按其手术入路的不同将其分为2组,其中经乳晕入路行手术的329例患者纳入对照组,经腋窝入路行手术的300例患者纳入观察组,术后均随访6个月。对比2组手术相关指标、乳房形态变化、隆胸效果、并发症。结果观察组切口愈合时间[(7.30±1.25)d]短于对照组[(9.21±1.69)d],并发症发生率(1.67%)低于对照组(4.86%),差异有统计学意义(P<0.05)。2组术中出血量、手术时间、住院时间、术后数字评分法(numeric rating scale,NRS)评分、隆胸效果相比,差异无统计学意义(P>0.05)。术前、术后2组乳头-乳房下皱襞的经皮距离(nipple to inframammaryfold,N-IMF)、胸骨切迹-乳头距离(sternal notch to nipple,S-N)、乳头-正中线距离(nipple to midline,N-M)、乳房总体积相比,差异无统计学意义(P>0.05)。结论经乳晕入路、经腋窝入路行双平面假体隆乳术均能够取得优良的隆胸效果,但经腋窝入路行手术更能够促进切口愈合,降低并发症发生率。文章的研究结果为临床后期选择双平面假体隆乳术的入路提供了借鉴内容,具有一定的运用价值。展开更多
Computational fluid dynamics（CFD） can give a lot of potentially very useful information for hydraulic optimization design of pumps, however, it cannot directly state what kind of modification should be made to impro...Computational fluid dynamics（CFD） can give a lot of potentially very useful information for hydraulic optimization design of pumps, however, it cannot directly state what kind of modification should be made to improve such hydrodynamic performance. In this paper, a more convenient and effective approach is proposed by combined using of CFD, multi-objective genetic algorithm（MOGA） and artificial neural networks（ANN） for a double-channel pump＇s impeller, with maximum head and efficiency set as optimization objectives, four key geometrical parameters including inlet diameter, outlet diameter, exit width and midline wrap angle chosen as optimization parameters. Firstly, a multi-fidelity fitness assignment system in which fitness of impellers serving as training and comparison samples for ANN is evaluated by CFD, meanwhile fitness of impellers generated by MOGA is evaluated by ANN, is established and dramatically reduces the computational expense. Then, a modified MOGA optimization process, in which selection is performed independently in two sub-populations according to two optimization objectives, crossover and mutation is performed afterword in the merged population, is developed to ensure the global optimal solution to be found. Finally, Pareto optimal frontier is found after 500 steps of iterations, and two optimal design schemes are chosen according to the design requirements. The preliminary and optimal design schemes are compared, and the comparing results show that hydraulic performances of both pumps 1 and 2 are improved, with the head and efficiency of pump 1 increased by 5.7% and 5.2%, respectively in the design working conditions, meanwhile shaft power decreased in all working conditions, the head and efficiency of pump 2 increased by 11.7% and 5.9%, respectively while shaft power increased by 5.5%. Inner flow field analyses also show that the backflow phenomenon significantly diminishes at the entrance of the optimal impellers 1 and 2, both the area of vortex and intensity of vortex decreases in the whole flow channel. This paper provides a promising tool to solve the hydraulic optimization problem of pumps＇ impellers.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62104184,62234009,62090014,62188102,62104178,and 62104179)the Fundamental Research Funds for the Central Universities of China(Grant Nos.YJSJ23019,XJSJ23047,and ZDRC2002)+1 种基金the China National Postdoctoral Program for Innovative Talents(Grant No.BX20200262)the China Postdoctoral Science Foundation(Grant No.2021M692499)。
文摘GaN-based p-channel heterostructure field-effect transistors(p-HFETs)face significant constraints on on-state currents compared with n-channel high electron mobility transistors.In this work,we propose a novel double heterostructure which introduces an additional p-GaN insertion layer into traditional p-HFETs.The impact of the device structure on the hole densities and valence band energies of both the upper and lower channels is analyzed by using Silvaco TACD simulations,including the thickness of the upper AlGaN layer and the doping impurities and concentration in the GaN buffer layer,as well as the thickness and Mg-doping concentration in the p-GaN insertion layer.With the help of the p-GaN insertion layer,the C-doping concentration in the GaN buffer layer can be reduced,while the density of the two-dimensional hole gas in the lower channel is enhanced at the same time.This work suggests that a double heterostructure with a p-GaN insertion layer is a better approach to improve p-HFETs compared with those devices with C-doped buffer layer alone.
文摘Objective: To investigate the clinical effect of liposuction combined with subareolar incision glandectomy in the treatment of Simon Grade Ⅲ adipo-glandular gynecomastia (GYN). Methods: From March 2021 to March 2022, the data of patients with Simon Grade Ⅲ adipo-glandular GYN treated by liposuction combined with glandectomy in the Department of Plastic Surgery, Zhongshan Hospital Affiliated to Dalian University and Henan Plastic Surgery and Aesthetic Hospital were retrospectively analyzed. Based on the medical records, color ultrasound was performed on the patient’s breast before surgery, which was determined to be GYN (more than 50% glandular tissue). A 3 mm long incision was made at the lower boundary of the surgical range, through which the adipose tissue in the hypertrophic region of the breast was repeatedly aspirated until a satisfactory thickness was achieved. The residual glandular tissue was removed by a semicircular arc incision under the areola, and then the areola incision was sutured in position. The blood flow, sensation, and wound healing of bilateral nipples and areola were observed after surgery, and the morphology of bilateral thorax and scar of incision were followed up. Results: A total of 15 GYN patients aged 18 to 35 years with body mass index of 23.8 to 26.5 kg/m2 (mean = 24.8 kg/m2) were included in this study. The average intraoperative liposuction volume of unilateral breast was 170 mL (150-200 mL), the average glandectomy volume was 115 g (95-125 g), and the average blood loss was about 40 mL (15-75 mL). Postoperative hypertrophic breast volume decreased significantly, and no complications such as hematoma, infection, skin ischemic necrosis, or sensory disturbance occurred in the nipple and areola, during the healing process. The patients were followed up for 3 to 6 months, and the bilateral thorax was smooth, symmetrical, and natural in contour. The incision was concealed, and the scar was not obvious. Conclusion: Liposuction combined with subareolar incision glandectomy in the treatment of Simon Grade Ⅲ adipo-glandular GYN is safe. The postoperative chest contour is smooth and natural, and the scar is small and invisible, which achieves good aesthetics.
文摘目的探讨不同入路行双平面假体隆乳术的效果。方法回顾性分析2020年1月—2023年1月新乡市中心医院收治的629例行双平面假体隆乳术患者的临床资料,按其手术入路的不同将其分为2组,其中经乳晕入路行手术的329例患者纳入对照组,经腋窝入路行手术的300例患者纳入观察组,术后均随访6个月。对比2组手术相关指标、乳房形态变化、隆胸效果、并发症。结果观察组切口愈合时间[(7.30±1.25)d]短于对照组[(9.21±1.69)d],并发症发生率(1.67%)低于对照组(4.86%),差异有统计学意义(P<0.05)。2组术中出血量、手术时间、住院时间、术后数字评分法(numeric rating scale,NRS)评分、隆胸效果相比,差异无统计学意义(P>0.05)。术前、术后2组乳头-乳房下皱襞的经皮距离(nipple to inframammaryfold,N-IMF)、胸骨切迹-乳头距离(sternal notch to nipple,S-N)、乳头-正中线距离(nipple to midline,N-M)、乳房总体积相比,差异无统计学意义(P>0.05)。结论经乳晕入路、经腋窝入路行双平面假体隆乳术均能够取得优良的隆胸效果,但经腋窝入路行手术更能够促进切口愈合,降低并发症发生率。文章的研究结果为临床后期选择双平面假体隆乳术的入路提供了借鉴内容,具有一定的运用价值。
基金Supported by National Natural Science Foundation of China(Grant No.51109094)Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘Computational fluid dynamics（CFD） can give a lot of potentially very useful information for hydraulic optimization design of pumps, however, it cannot directly state what kind of modification should be made to improve such hydrodynamic performance. In this paper, a more convenient and effective approach is proposed by combined using of CFD, multi-objective genetic algorithm（MOGA） and artificial neural networks（ANN） for a double-channel pump＇s impeller, with maximum head and efficiency set as optimization objectives, four key geometrical parameters including inlet diameter, outlet diameter, exit width and midline wrap angle chosen as optimization parameters. Firstly, a multi-fidelity fitness assignment system in which fitness of impellers serving as training and comparison samples for ANN is evaluated by CFD, meanwhile fitness of impellers generated by MOGA is evaluated by ANN, is established and dramatically reduces the computational expense. Then, a modified MOGA optimization process, in which selection is performed independently in two sub-populations according to two optimization objectives, crossover and mutation is performed afterword in the merged population, is developed to ensure the global optimal solution to be found. Finally, Pareto optimal frontier is found after 500 steps of iterations, and two optimal design schemes are chosen according to the design requirements. The preliminary and optimal design schemes are compared, and the comparing results show that hydraulic performances of both pumps 1 and 2 are improved, with the head and efficiency of pump 1 increased by 5.7% and 5.2%, respectively in the design working conditions, meanwhile shaft power decreased in all working conditions, the head and efficiency of pump 2 increased by 11.7% and 5.9%, respectively while shaft power increased by 5.5%. Inner flow field analyses also show that the backflow phenomenon significantly diminishes at the entrance of the optimal impellers 1 and 2, both the area of vortex and intensity of vortex decreases in the whole flow channel. This paper provides a promising tool to solve the hydraulic optimization problem of pumps＇ impellers.
