The long-term stability of rocks is crucial for ensuring safety in deep engineering,where the prolonged influence of shear loading is a key factor in delayed engineering disasters.Despite its significance,research on ...The long-term stability of rocks is crucial for ensuring safety in deep engineering,where the prolonged influence of shear loading is a key factor in delayed engineering disasters.Despite its significance,research on time-dependent shear failures under true triaxial stress to reflect in situ stress conditions remains limited.This study presents laboratory shear creep measurements on intact sandstone samples under constant normal load(CNL)and constant normal stiffness(CNS)conditions,which are typical of shallow and deep engineering cases,respectively.Our investigation focuses on the effects of various lateral stresses and boundary conditions on the mechanical behaviors and failure modes of the rock samples.Results indicate that lateral stress significantly reduces shear creep deformation and decreases creep rates.Without lateral stress constraints,the samples are prone to lateral tensile fractures leading to macroscopic spalling,likely due to“shear-induced tensile”stress.This failure behavior is mitigated under lateral stress constraints.Additionally,compared to CNL condition,samples under CNS condition demonstrate enhanced long-term shear resistance,reduced shear creep rates,and rougher shear failure surfaces.These findings suggest the need to improve our understanding of rock mass stability and to develop effective disaster prevention and mitigation strategies in engineering applications.展开更多
Accurate atomic mass data hold significant application value in various research fields,in which Penning trap mass spectrometry is considered the most precise experimental method.A cryogenic detection system is a key ...Accurate atomic mass data hold significant application value in various research fields,in which Penning trap mass spectrometry is considered the most precise experimental method.A cryogenic detection system is a key component for reading out the image charge of charged particles in Penning traps using the Fourier transform ion cyclotron resonance technique.In this paper,we present the development and characteristics of this detection system,which includes a superconducting resonator and cryogenic low-noise amplifiers.The resonator consists of delicately woven thin NbTi wires configured into a multilayer helical coil,offering a quality factor of 98004 at around 1 MHz.Low-noise amplifiers are developed based on GaAs field effect transistors,exhibiting amplification factors greater than 27 dB with a power consumption of approximately 6 mW in the frequency range of 0.1 to 10 MHz.The lowest input voltage noise is 0.8√Hz at 1 MHz.The fabrication process,operation,and measurements are elucidated in detail.展开更多
Deep engineering disasters,such as rockbursts and collapses,are more related to the shear slip of rock joints.A novel multifunctional device was developed to study the shear failure mechanism in rocks.Using this devic...Deep engineering disasters,such as rockbursts and collapses,are more related to the shear slip of rock joints.A novel multifunctional device was developed to study the shear failure mechanism in rocks.Using this device,the complete shearedeformation process and long-term shear creep tests could be performed on rocks under constant normal stiffness(CNS)or constant normal loading(CNL)conditions in real-time at high temperature and true-triaxial stress.During the research and development process,five key technologies were successfully broken through:(1)the ability to perform true-triaxial compressioneshear loading tests on rock samples with high stiffness;(2)a shear box with ultra-low friction throughout the entire stress space of the rock sample during loading;(3)a control system capable of maintaining high stress for a long time and responding rapidly to the brittle fracture of a rock sample as well;(4)a refined ability to measure the volumetric deformation of rock samples subjected to true triaxial shearing;and(5)a heating system capable of maintaining uniform heating of the rock sample over a long time.By developing these technologies,loading under high true triaxial stress conditions was realized.The apparatus has a maximum normal stiffness of 1000 GPa/m and a maximum operating temperature of 300C.The differences in the surface temperature of the sample are constant to within5C.Five types of true triaxial shear tests were conducted on homogeneous sandstone to verify that the apparatus has good performance and reliability.The results show that temperature,lateral stress,normal stress and time influence the shear deformation,failure mode and strength of the sandstone.The novel apparatus can be reliably used to conduct true-triaxial shear tests on rocks subjected to high temperatures and stress.展开更多
The total absolute cross sections of single-and double-electron capture (SEC and DEC) in the collisions of He^(2+)with He and Ne^(8+)with O_(2),N_(2),and CH_(4) were studied in the energy ranges 3.5–50 keV/u and 2.8...The total absolute cross sections of single-and double-electron capture (SEC and DEC) in the collisions of He^(2+)with He and Ne^(8+)with O_(2),N_(2),and CH_(4) were studied in the energy ranges 3.5–50 keV/u and 2.8–40 keV/u,respectively.Through a deep analysis of the experimental systematic uncertainties in the measurement procedure and data evaluation,the error in the experimental results of the SEC cross sections is less than 9%.Within the uncertainties,the present results of the He^(2+)–He collision show good consistency with previous measurements,validating the experimental system and paving the way for precise measurements of EC cross sections for a variety of ions and neutral gases.The present measurements allow for a test of EC theory and provide crucial EC cross section data for the establishment of plasma models in fusion research and astrophysical X-ray studies.展开更多
BACKGROUND Infectious common femoral artery pseudoaneurysm caused by Klebsiellapulmonary infection is a relatively infrequent entity but is potentially life andlimb threatening. The management of infectious pseudoaneu...BACKGROUND Infectious common femoral artery pseudoaneurysm caused by Klebsiellapulmonary infection is a relatively infrequent entity but is potentially life andlimb threatening. The management of infectious pseudoaneurysm remainscontroversial.CASE SUMMARY We reported a 79-year-old man with previous Klebsiella pneumoniae pulmonaryinfection and multiple comorbidities who presented with a progressive pulsatemass at the right groin and with right lower limb pain. Computed tomographyangiography showed a 6 cm × 6 cm × 9 cm pseudoaneurysm of the right commonfemoral artery accompanied by occlusion of the right superficial femoral arteryand deep femoral artery. He underwent endovascular treatment (EVT) withstent–graft, and etiology of infectious pseudoaneurysm was confirmed. Then, 3-mo antibiotic therapy was given. One-year follow-up showed the stent–graft waspatent and complete removal of surrounding hematoma.CONCLUSION The femoral artery pseudoaneurysm can be caused by Klebsiella pneumoniaederiving from the pulmonary infection. Moreover, this unusual case highlights theuse of EVT and prolonged antibiotic therapy for infectious pseudoaneurysm.展开更多
基金support from the National Natural Science Foundation of China(Grant No.52209125).
文摘The long-term stability of rocks is crucial for ensuring safety in deep engineering,where the prolonged influence of shear loading is a key factor in delayed engineering disasters.Despite its significance,research on time-dependent shear failures under true triaxial stress to reflect in situ stress conditions remains limited.This study presents laboratory shear creep measurements on intact sandstone samples under constant normal load(CNL)and constant normal stiffness(CNS)conditions,which are typical of shallow and deep engineering cases,respectively.Our investigation focuses on the effects of various lateral stresses and boundary conditions on the mechanical behaviors and failure modes of the rock samples.Results indicate that lateral stress significantly reduces shear creep deformation and decreases creep rates.Without lateral stress constraints,the samples are prone to lateral tensile fractures leading to macroscopic spalling,likely due to“shear-induced tensile”stress.This failure behavior is mitigated under lateral stress constraints.Additionally,compared to CNL condition,samples under CNS condition demonstrate enhanced long-term shear resistance,reduced shear creep rates,and rougher shear failure surfaces.These findings suggest the need to improve our understanding of rock mass stability and to develop effective disaster prevention and mitigation strategies in engineering applications.
基金supported by the National Key R&D Program of China(No.2023YFA1606501)the National Natural Science Foundation of China(Nos.12204110 and 12474251)+2 种基金Shanghai Pujiang Program(No.22PJ1401100)Max-Planck Partner Group Projectthe Fudan University Yan Liyuan-EnSiKai Foundation(JX240003)。
文摘Accurate atomic mass data hold significant application value in various research fields,in which Penning trap mass spectrometry is considered the most precise experimental method.A cryogenic detection system is a key component for reading out the image charge of charged particles in Penning traps using the Fourier transform ion cyclotron resonance technique.In this paper,we present the development and characteristics of this detection system,which includes a superconducting resonator and cryogenic low-noise amplifiers.The resonator consists of delicately woven thin NbTi wires configured into a multilayer helical coil,offering a quality factor of 98004 at around 1 MHz.Low-noise amplifiers are developed based on GaAs field effect transistors,exhibiting amplification factors greater than 27 dB with a power consumption of approximately 6 mW in the frequency range of 0.1 to 10 MHz.The lowest input voltage noise is 0.8√Hz at 1 MHz.The fabrication process,operation,and measurements are elucidated in detail.
基金financial support from the National Natural Science Foundation of China(Grant Nos.52209125 and 51839003).
文摘Deep engineering disasters,such as rockbursts and collapses,are more related to the shear slip of rock joints.A novel multifunctional device was developed to study the shear failure mechanism in rocks.Using this device,the complete shearedeformation process and long-term shear creep tests could be performed on rocks under constant normal stiffness(CNS)or constant normal loading(CNL)conditions in real-time at high temperature and true-triaxial stress.During the research and development process,five key technologies were successfully broken through:(1)the ability to perform true-triaxial compressioneshear loading tests on rock samples with high stiffness;(2)a shear box with ultra-low friction throughout the entire stress space of the rock sample during loading;(3)a control system capable of maintaining high stress for a long time and responding rapidly to the brittle fracture of a rock sample as well;(4)a refined ability to measure the volumetric deformation of rock samples subjected to true triaxial shearing;and(5)a heating system capable of maintaining uniform heating of the rock sample over a long time.By developing these technologies,loading under high true triaxial stress conditions was realized.The apparatus has a maximum normal stiffness of 1000 GPa/m and a maximum operating temperature of 300C.The differences in the surface temperature of the sample are constant to within5C.Five types of true triaxial shear tests were conducted on homogeneous sandstone to verify that the apparatus has good performance and reliability.The results show that temperature,lateral stress,normal stress and time influence the shear deformation,failure mode and strength of the sandstone.The novel apparatus can be reliably used to conduct true-triaxial shear tests on rocks subjected to high temperatures and stress.
基金supported by the National Key R&D Program of China (No. 2022YFA1602504)the National Natural Science Foundation of China (Nos. 12204110 and U1832201)Shanghai Leading Academic Discipline Project (Project No. B107)。
文摘The total absolute cross sections of single-and double-electron capture (SEC and DEC) in the collisions of He^(2+)with He and Ne^(8+)with O_(2),N_(2),and CH_(4) were studied in the energy ranges 3.5–50 keV/u and 2.8–40 keV/u,respectively.Through a deep analysis of the experimental systematic uncertainties in the measurement procedure and data evaluation,the error in the experimental results of the SEC cross sections is less than 9%.Within the uncertainties,the present results of the He^(2+)–He collision show good consistency with previous measurements,validating the experimental system and paving the way for precise measurements of EC cross sections for a variety of ions and neutral gases.The present measurements allow for a test of EC theory and provide crucial EC cross section data for the establishment of plasma models in fusion research and astrophysical X-ray studies.
基金Supported by Sichuan Foundationof Science and Technology, No.2019YJ0066.
文摘BACKGROUND Infectious common femoral artery pseudoaneurysm caused by Klebsiellapulmonary infection is a relatively infrequent entity but is potentially life andlimb threatening. The management of infectious pseudoaneurysm remainscontroversial.CASE SUMMARY We reported a 79-year-old man with previous Klebsiella pneumoniae pulmonaryinfection and multiple comorbidities who presented with a progressive pulsatemass at the right groin and with right lower limb pain. Computed tomographyangiography showed a 6 cm × 6 cm × 9 cm pseudoaneurysm of the right commonfemoral artery accompanied by occlusion of the right superficial femoral arteryand deep femoral artery. He underwent endovascular treatment (EVT) withstent–graft, and etiology of infectious pseudoaneurysm was confirmed. Then, 3-mo antibiotic therapy was given. One-year follow-up showed the stent–graft waspatent and complete removal of surrounding hematoma.CONCLUSION The femoral artery pseudoaneurysm can be caused by Klebsiella pneumoniaederiving from the pulmonary infection. Moreover, this unusual case highlights theuse of EVT and prolonged antibiotic therapy for infectious pseudoaneurysm.
