In this work,a novel one-time-programmable memory unit based on a Schottky-type p-GaN diode is proposed.During the programming process,the junction switches from a high-resistance state to a low-resistance state throu...In this work,a novel one-time-programmable memory unit based on a Schottky-type p-GaN diode is proposed.During the programming process,the junction switches from a high-resistance state to a low-resistance state through Schottky junction breakdown,and the state is permanently preserved.The memory unit features a current ratio of more than 10^(3),a read voltage window of 6 V,a programming time of less than 10^(−4)s,a stability of more than 108 read cycles,and a lifetime of far more than 10 years.Besides,the fabrication of the device is fully compatible with commercial Si-based GaN process platforms,which is of great significance for the realization of low-cost read-only memory in all-GaN integration.展开更多
BACKGROUND Rectal prolapse occurs most commonly in children and middle-aged and elderly women and is relatively rare in young men and is occasionally caused by bladder stones.Severe rectal prolapse,bilateral hydroneph...BACKGROUND Rectal prolapse occurs most commonly in children and middle-aged and elderly women and is relatively rare in young men and is occasionally caused by bladder stones.Severe rectal prolapse,bilateral hydronephrosis,and renal insufficiency caused by bladder stones are rare in a 30-year-old man.CASE SUMMARY We report the case of a 30-year-old male patient with cerebral palsy who presented with a large bladder stone that resulted in severe rectal prolapse,bilateral hydronephrosis,and renal insufficiency.Following a definitive diagnosis,the bladder stone was successfully removed,and his kidney function returned to normal.We assessed the patient’s nutritional status and stone composition and concluded that the main cause was malnutrition.CONCLUSION Rectal prolapse is a rare clinical manifestation of bladder stones,particularly in young adults.Cerebral palsy patients are a vulnerable group in society because of their intellectual disabilities and communicative impairments.Accordingly,besides taking care of their daily diet,abnormal signs in their bodies should receive the doctors’attention in a timely manner.展开更多
The Zone of Avoidance(ZoA)is a region of low galactic latitude that is heavily obscured by the Milky Way.Observations with radio telescopes are basically unaffected by dust extinction and can unveil the structure behi...The Zone of Avoidance(ZoA)is a region of low galactic latitude that is heavily obscured by the Milky Way.Observations with radio telescopes are basically unaffected by dust extinction and can unveil the structure behind it through the Milky Way.One of the scientific goals of the Five-hundred-meter Aperture Spherical radio Telescope(FAST)is to search for the neutral hydrogen and understand the large-scale physics to explore the origin and evolution of the universe.We take the 15,500 IRAS(the Infrared Astronomical Satellite)galaxies from PSCz(“Point Source Catalog”)survey to reconstruct the density field of the local universe,obtain the distribution of the relative density of galaxies in the ZoA region with a redshift z below 0.07,and the number of detectable galaxies with FAST is estimated by using the neutral hydrogen mass function of the ALFA(Arecibo L-band Feed Array)survey.We conclude that FAST can observe more than 2000 ZoA galaxies within a distance of 300 Mpc h_(70)^(-1),and present preliminary results of the partial GPPS(the FAST Galactic Plane Pulsar Snapshot survey)data,compared with ALFA ZoA(The Arecibo L-band Feed Array Zone of Avoidance),show that FAST has a higher detection sensitivity to search for HI galaxies in the ZoA area.展开更多
As the elderly population continues to grow, the number of patients with low back pain is gradually increasing. Among them, Lumbar Degenerative Diseases (LDD) is one of the major contributors to low back pain. Biomech...As the elderly population continues to grow, the number of patients with low back pain is gradually increasing. Among them, Lumbar Degenerative Diseases (LDD) is one of the major contributors to low back pain. Biomechanical in vivo studies of the lumbar spine are mainly performed by implants or imaging data to record the real-time changes of form and stress on the intervertebral disc during motion. However, the current developments are slow due to the technological and ethical limitations. In vitro experiments include animal experiments and cadaver experiments, which are difficult to operate or differ greatly from normal human structures, and the results still need to be verified repeatedly to test their accuracy. As for finite element method, it is relatively low cost and can repeat the experimental results. Therefore, we believe that finite element analysis plays an extremely important role in biomechanical research, especially in analyzing the relationship between different surgical models and the degeneration caused by different mechanics.展开更多
Generation of intense, fully coherent radiation with wide spectral coverage has been a long-standing challenge for laser technologies. Several techniques have been developed in recent years to extend the spectral cove...Generation of intense, fully coherent radiation with wide spectral coverage has been a long-standing challenge for laser technologies. Several techniques have been developed in recent years to extend the spectral coverage in optical physics, but none of them hold the potential to produce X-ray laser pulses with very high-peak power. Urgent demands for intense X-ray light sources have prompted the development of free-electron lasers(FELs), which have been proved to be very useful tools in many scientific areas. In this paper, we give an overview of the basic principle of FELs, techniques for realizing fully coherent FELs, and the development of fully coherent FEL facilities in China.展开更多
AIM: To evaluate transjugular intrahepatic portosystemic shunt(TIPS) with covered stents for hepatocellular carcinoma(HCC) with main portal vein tumor thrombus(PVTT). METHODS: Eleven advanced HCC patients(all male, ag...AIM: To evaluate transjugular intrahepatic portosystemic shunt(TIPS) with covered stents for hepatocellular carcinoma(HCC) with main portal vein tumor thrombus(PVTT). METHODS: Eleven advanced HCC patients(all male, aged 37-78 years, mean: 54.3 ± 12.7 years) presented with acute massive upper gastrointestinal bleeding(n = 9) or refractory ascites(n = 2) due to tumor thrombus in the main portal vein. The diagnosis of PVTT was based on contrast-enhanced computed tomography and color Doppler sonography. The patients underwent TIPS with covered stents. Clinical characteristics and average survival time of 11 patients were analyzed. Portal vein pressure was assessed before and after TIPS. The follow-up period was 2-18 mo. RESULTS: TIPS with covered stents was successfully completed in all 11 patients. The mean portal vein pressure was reduced from 32.0 to 11.8 mmHg(t = 10.756, P = 0.000). Gastrointestinal bleeding was stopped in nine patients. Refractory ascites completely disappeared in one patient and was alleviated in another. Hepatic encephalopathy was observed in six patients and was resolved with drug therapy. During the follow-up, ultrasound indicated the patency of the shunt and there was no recurrence of symptoms. Death occurred 2-14 mo(mean: 5.67 mo) after TIPS in nine cases, which were all due to multiple organ failure. In the remaining two cases, the patients were still alive at the 16- and 18-mo follow-up, respectively. CONCLUSION: TIPS with covered stents for HCC patients with tumor thrombus in the main portal vein is technically feasible, and short-term efficacy is favorable.展开更多
A two-stage echo-enabled harmonic generation(EEHG)scheme is proposed for a superconducting linacdriven FEL to produce coherent hard X-rays.Electron beams of quite different bunch lengths are separately used in each st...A two-stage echo-enabled harmonic generation(EEHG)scheme is proposed for a superconducting linacdriven FEL to produce coherent hard X-rays.Electron beams of quite different bunch lengths are separately used in each stage of EEHG,and a monochromator is designed to purify the radiation from the first stage for seeding the second stage.Theoretical analysis and 3D simulations indicate that the proposed scheme can generate high-repetition-rate coherent hard X-ray pulses directly from a conventional UV seed laser.展开更多
In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potenti...In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potential of application in pump–probe techniques, two-color X-ray free electron laser, high-gradient witness bunch acceleration in a plasma, etc. Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in a linear accelerator. Comparisons are made between the new method and existing ways.展开更多
The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstation...The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstations covering a range of 100–620 eV for ultrafast X-ray science.Two undulator lines are designed and constructed,based on different lasing modes:self-amplified spontaneous emission and echo-enabled harmonic generation.The coherent scattering and imaging(CSI)endstation is the first of five endstations to be commissioned online.It focuses on high-resolution single-shot imaging and the study of ultrafast dynamic processes using coherent forward scattering techniques.Both the single-shot holograms and coherent diffraction patterns were recorded and reconstructed for nanoscale imaging,indicating the excellent coherence and high peak power of the SXFEL and the possibility of‘‘diffraction before destruction’’experiments at the CSI endstation.In this study,we report the first commissioning results of the CSI endstation.展开更多
The present study established rat models of middle cerebral artery ischemia/reperfusion using the thread method. Rats performed willed-movement （climbing a ladder or wall in a box） when induced by food and water. Re...The present study established rat models of middle cerebral artery ischemia/reperfusion using the thread method. Rats performed willed-movement （climbing a ladder or wall in a box） when induced by food and water. Results revealed that Longa scores of neurological deficits significantly decreased in the willed-movement group at 15 days after reperfusion, while expression of glial fibrillary acidic protein, neurotrophic factor-3, and growth-associated protein-43 significantly increased at 7 and 15 days after reperfusion. Results suggested that willed-movement ameliorated neurological deficits by increasing expression of glial fibriliary acidic protein, neurotrophic factor-3, and growth-associated protein-43.展开更多
Herein, a feasible method is proposed to compensate the high-order effect during bunch length compression, thereby enhancing the peak current of a highrepetition-rate X-ray free-electron laser source. In the proposed ...Herein, a feasible method is proposed to compensate the high-order effect during bunch length compression, thereby enhancing the peak current of a highrepetition-rate X-ray free-electron laser source. In the proposed method, the corrugated structure is inserted downstream of the high-order harmonic cavities to function as a passive linearizer and enhance the longitudinal profile of the electron beam. Three-dimensional simulations are performed to analyze the evolution of the longitudinal phase space, and the results demonstrate that the profile of the electron beam is improved and the peak current can be easily optimized to over 2 kA with a bunch charge of 100 pC.展开更多
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFB3604400in part by the Youth Innovation Promotion Association of Chinese Academy Sciences (CAS)+4 种基金in part by the CAS-Croucher Funding Scheme under Grant CAS22801in part by National Natural Science Foundation of China under Grant 62334012, Grant 62074161, Grant 62004213, Grant U20A20208, and Grant 62304252in part by the Beijing Municipal Science and Technology Commission project under Grant Z201100008420009 and Grant Z211100007921018in part by the University of CASin part by the IMECAS-HKUST-Joint Laboratory of Microelectronics
文摘In this work,a novel one-time-programmable memory unit based on a Schottky-type p-GaN diode is proposed.During the programming process,the junction switches from a high-resistance state to a low-resistance state through Schottky junction breakdown,and the state is permanently preserved.The memory unit features a current ratio of more than 10^(3),a read voltage window of 6 V,a programming time of less than 10^(−4)s,a stability of more than 108 read cycles,and a lifetime of far more than 10 years.Besides,the fabrication of the device is fully compatible with commercial Si-based GaN process platforms,which is of great significance for the realization of low-cost read-only memory in all-GaN integration.
基金Supported by Bureau of Science and Technology in Xiaoshan District,Hangzhou,China,NO.2020210。
文摘BACKGROUND Rectal prolapse occurs most commonly in children and middle-aged and elderly women and is relatively rare in young men and is occasionally caused by bladder stones.Severe rectal prolapse,bilateral hydronephrosis,and renal insufficiency caused by bladder stones are rare in a 30-year-old man.CASE SUMMARY We report the case of a 30-year-old male patient with cerebral palsy who presented with a large bladder stone that resulted in severe rectal prolapse,bilateral hydronephrosis,and renal insufficiency.Following a definitive diagnosis,the bladder stone was successfully removed,and his kidney function returned to normal.We assessed the patient’s nutritional status and stone composition and concluded that the main cause was malnutrition.CONCLUSION Rectal prolapse is a rare clinical manifestation of bladder stones,particularly in young adults.Cerebral palsy patients are a vulnerable group in society because of their intellectual disabilities and communicative impairments.Accordingly,besides taking care of their daily diet,abnormal signs in their bodies should receive the doctors’attention in a timely manner.
基金the GPPS sky survey project of the National Astronomical Observatories of the Chinese Academy of Sciences(NAOC)。
文摘The Zone of Avoidance(ZoA)is a region of low galactic latitude that is heavily obscured by the Milky Way.Observations with radio telescopes are basically unaffected by dust extinction and can unveil the structure behind it through the Milky Way.One of the scientific goals of the Five-hundred-meter Aperture Spherical radio Telescope(FAST)is to search for the neutral hydrogen and understand the large-scale physics to explore the origin and evolution of the universe.We take the 15,500 IRAS(the Infrared Astronomical Satellite)galaxies from PSCz(“Point Source Catalog”)survey to reconstruct the density field of the local universe,obtain the distribution of the relative density of galaxies in the ZoA region with a redshift z below 0.07,and the number of detectable galaxies with FAST is estimated by using the neutral hydrogen mass function of the ALFA(Arecibo L-band Feed Array)survey.We conclude that FAST can observe more than 2000 ZoA galaxies within a distance of 300 Mpc h_(70)^(-1),and present preliminary results of the partial GPPS(the FAST Galactic Plane Pulsar Snapshot survey)data,compared with ALFA ZoA(The Arecibo L-band Feed Array Zone of Avoidance),show that FAST has a higher detection sensitivity to search for HI galaxies in the ZoA area.
文摘As the elderly population continues to grow, the number of patients with low back pain is gradually increasing. Among them, Lumbar Degenerative Diseases (LDD) is one of the major contributors to low back pain. Biomechanical in vivo studies of the lumbar spine are mainly performed by implants or imaging data to record the real-time changes of form and stress on the intervertebral disc during motion. However, the current developments are slow due to the technological and ethical limitations. In vitro experiments include animal experiments and cadaver experiments, which are difficult to operate or differ greatly from normal human structures, and the results still need to be verified repeatedly to test their accuracy. As for finite element method, it is relatively low cost and can repeat the experimental results. Therefore, we believe that finite element analysis plays an extremely important role in biomechanical research, especially in analyzing the relationship between different surgical models and the degeneration caused by different mechanics.
基金supported by the National Key Research and Development Program of China(No.2016YFA0401900)the National Natural Science Foundation of China(Nos.11475250 and11775293)+1 种基金the Young Elite Scientist Sponsorship Program of CAST(2015QNRC001)the Ten Thousand Talent Program
文摘Generation of intense, fully coherent radiation with wide spectral coverage has been a long-standing challenge for laser technologies. Several techniques have been developed in recent years to extend the spectral coverage in optical physics, but none of them hold the potential to produce X-ray laser pulses with very high-peak power. Urgent demands for intense X-ray light sources have prompted the development of free-electron lasers(FELs), which have been proved to be very useful tools in many scientific areas. In this paper, we give an overview of the basic principle of FELs, techniques for realizing fully coherent FELs, and the development of fully coherent FEL facilities in China.
基金Supported by Science and Technology Planning Project of Guangdong Province,China,No.2012B010200027The Key Technologies RD Program of Guangzhou,ChinaThe Presidential Foundation of the Nanfang Hospital,Southern Medical University,Guangzhou,China,No.2011B006
文摘AIM: To evaluate transjugular intrahepatic portosystemic shunt(TIPS) with covered stents for hepatocellular carcinoma(HCC) with main portal vein tumor thrombus(PVTT). METHODS: Eleven advanced HCC patients(all male, aged 37-78 years, mean: 54.3 ± 12.7 years) presented with acute massive upper gastrointestinal bleeding(n = 9) or refractory ascites(n = 2) due to tumor thrombus in the main portal vein. The diagnosis of PVTT was based on contrast-enhanced computed tomography and color Doppler sonography. The patients underwent TIPS with covered stents. Clinical characteristics and average survival time of 11 patients were analyzed. Portal vein pressure was assessed before and after TIPS. The follow-up period was 2-18 mo. RESULTS: TIPS with covered stents was successfully completed in all 11 patients. The mean portal vein pressure was reduced from 32.0 to 11.8 mmHg(t = 10.756, P = 0.000). Gastrointestinal bleeding was stopped in nine patients. Refractory ascites completely disappeared in one patient and was alleviated in another. Hepatic encephalopathy was observed in six patients and was resolved with drug therapy. During the follow-up, ultrasound indicated the patency of the shunt and there was no recurrence of symptoms. Death occurred 2-14 mo(mean: 5.67 mo) after TIPS in nine cases, which were all due to multiple organ failure. In the remaining two cases, the patients were still alive at the 16- and 18-mo follow-up, respectively. CONCLUSION: TIPS with covered stents for HCC patients with tumor thrombus in the main portal vein is technically feasible, and short-term efficacy is favorable.
基金partially supported by the National Development and Reform Commission([2013]2347)National Natural Science Foundation of China(No.11475250)the Youth Innovation Promotion Association CAS(2015209)
文摘A two-stage echo-enabled harmonic generation(EEHG)scheme is proposed for a superconducting linacdriven FEL to produce coherent hard X-rays.Electron beams of quite different bunch lengths are separately used in each stage of EEHG,and a monochromator is designed to purify the radiation from the first stage for seeding the second stage.Theoretical analysis and 3D simulations indicate that the proposed scheme can generate high-repetition-rate coherent hard X-ray pulses directly from a conventional UV seed laser.
基金partially supported by the Major State Basic Research Development Program of China(No.2011CB808300)the National Natural Science Foundation of China(Nos.11175240,11205234 and 11322550)
文摘In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potential of application in pump–probe techniques, two-color X-ray free electron laser, high-gradient witness bunch acceleration in a plasma, etc. Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in a linear accelerator. Comparisons are made between the new method and existing ways.
基金the Shanghai Soft X-ray Free-Electron Laser Facility beamline projectionfunded by the Major State Basic Research Development Program of China(No.2017YFA0504802)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 37040303)National Natural Science Foundation of China(No.21727817).
文摘The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstations covering a range of 100–620 eV for ultrafast X-ray science.Two undulator lines are designed and constructed,based on different lasing modes:self-amplified spontaneous emission and echo-enabled harmonic generation.The coherent scattering and imaging(CSI)endstation is the first of five endstations to be commissioned online.It focuses on high-resolution single-shot imaging and the study of ultrafast dynamic processes using coherent forward scattering techniques.Both the single-shot holograms and coherent diffraction patterns were recorded and reconstructed for nanoscale imaging,indicating the excellent coherence and high peak power of the SXFEL and the possibility of‘‘diffraction before destruction’’experiments at the CSI endstation.In this study,we report the first commissioning results of the CSI endstation.
基金the Science and Technology Projects from Science and Technology Agency,Hunan Province,China,No. 2011FJ3206
文摘The present study established rat models of middle cerebral artery ischemia/reperfusion using the thread method. Rats performed willed-movement （climbing a ladder or wall in a box） when induced by food and water. Results revealed that Longa scores of neurological deficits significantly decreased in the willed-movement group at 15 days after reperfusion, while expression of glial fibrillary acidic protein, neurotrophic factor-3, and growth-associated protein-43 significantly increased at 7 and 15 days after reperfusion. Results suggested that willed-movement ameliorated neurological deficits by increasing expression of glial fibriliary acidic protein, neurotrophic factor-3, and growth-associated protein-43.
基金supported by the National Natural Science Foundation of China(Nos.11675248 and 11775294)the Youth Innovation Promotion Association CAS(No.2018300)
文摘Herein, a feasible method is proposed to compensate the high-order effect during bunch length compression, thereby enhancing the peak current of a highrepetition-rate X-ray free-electron laser source. In the proposed method, the corrugated structure is inserted downstream of the high-order harmonic cavities to function as a passive linearizer and enhance the longitudinal profile of the electron beam. Three-dimensional simulations are performed to analyze the evolution of the longitudinal phase space, and the results demonstrate that the profile of the electron beam is improved and the peak current can be easily optimized to over 2 kA with a bunch charge of 100 pC.
