Fe-based superconductors represent a fascinating class of materials,extensively studied for their complex interplay of superconductivity,magnetism,spin density waves,and nematicity,along with the interactions among th...Fe-based superconductors represent a fascinating class of materials,extensively studied for their complex interplay of superconductivity,magnetism,spin density waves,and nematicity,along with the interactions among these orders.An intriguing yet unexplained phenomenon observed in Fe-based superconductors is the emergence of superconductivity below 25K in the non-superconducting parent compound SrFe_(2)As_(2)following exposure to water at its surface.In this study,we employed in situ angle-resolved photoemission spectroscopy and low-energy electron diffraction to meticulously examine the electronic structure evolution of SrFe_(2)As_(2)upon in situ water dosing.Our findings indicate that water dosing markedly attenuates the spin density wave phase and surface Sr reconstruction while preserving the nematic order in SrFe_(2)As_(2).Furthermore,we detected an enhancement in the spectral weight of bands near the Fermi level.Our observations highlight the critical role of the intricate interplay among various orders induced by water dosing,which effectively modifies the band structure and favors the emergence of superconductivity in SrFe_(2)As_(2).展开更多
Diagnostic Reference Levels (DRLs) are indicators that allow assessing the quality of equipment and procedures from the point of view of the doses delivered to patients and subsequently initiate corrective actions if ...Diagnostic Reference Levels (DRLs) are indicators that allow assessing the quality of equipment and procedures from the point of view of the doses delivered to patients and subsequently initiate corrective actions if necessary. The purpose of this study is to encourage health professionals to investigate patient radiation doses and to determine whether those doses comply with the principles of radiation protection in medical fields so as to improve practices by reducing patient exposure without reducing clinical effectiveness. To perform this work, we have investigated patient doses for different radiological examinations from six (6) medical centers in Dakar, including the following nine routine types: chest (PA), abdomen (AP), pelvis (AP), cervical spine (AP), lumbar spine (AP, Lat), hip (AP), thoracic spine (AP, Lat). Three types of data were collected, <em>i.e.</em>, X-ray tube machine data, patient data and output measurements. The data were analyzed statistically and the median, minimum, maximum, and third quartile values were calculated and displayed throughout boxplots graphs for all exams and medical centers. The two sigma range (95% confidence interval) was also checked. Comparison of third quartiles of Entrance Surface Dose (ESD) and Dose Area Product (DAP) by type of examination with recommended international DRLs was performed. The third quartile of ESD for pelvis (AP) and thoracic spine (AP) was up to 16% and 38% higher, respectively than their corresponding DRLs in the European Commission Report RP 180 Part 2. For all exams, except thoracic spine (lat), the third quartiles of the dose area product were higher than the corresponding DRLs in the above report. The source of dose variability between medical centers was related to many parameters such as poor radiographic techniques, lack of modern X-ray machines and adequately documented radiation protection practices. The results show the need to develop protocols for dose measurement as well as to carry out quality assurance programs and dose optimization in Senegal.展开更多
基金supported by the National Nature Science Foundation of China[Grant Nos.92365204 and 12274298(Z.K.Liu)]the National Key R&D program of China[Grant No.2022YFA1604400/03(Z.K.Liu)]Zhangjiang Laboratory(Y.M.Zhang).The authors thank BL02B at the Shanghai Synchrotron Radiation Facility supported by the National Natural Science Foundation of China(Contract No.11227902).
文摘Fe-based superconductors represent a fascinating class of materials,extensively studied for their complex interplay of superconductivity,magnetism,spin density waves,and nematicity,along with the interactions among these orders.An intriguing yet unexplained phenomenon observed in Fe-based superconductors is the emergence of superconductivity below 25K in the non-superconducting parent compound SrFe_(2)As_(2)following exposure to water at its surface.In this study,we employed in situ angle-resolved photoemission spectroscopy and low-energy electron diffraction to meticulously examine the electronic structure evolution of SrFe_(2)As_(2)upon in situ water dosing.Our findings indicate that water dosing markedly attenuates the spin density wave phase and surface Sr reconstruction while preserving the nematic order in SrFe_(2)As_(2).Furthermore,we detected an enhancement in the spectral weight of bands near the Fermi level.Our observations highlight the critical role of the intricate interplay among various orders induced by water dosing,which effectively modifies the band structure and favors the emergence of superconductivity in SrFe_(2)As_(2).
文摘Diagnostic Reference Levels (DRLs) are indicators that allow assessing the quality of equipment and procedures from the point of view of the doses delivered to patients and subsequently initiate corrective actions if necessary. The purpose of this study is to encourage health professionals to investigate patient radiation doses and to determine whether those doses comply with the principles of radiation protection in medical fields so as to improve practices by reducing patient exposure without reducing clinical effectiveness. To perform this work, we have investigated patient doses for different radiological examinations from six (6) medical centers in Dakar, including the following nine routine types: chest (PA), abdomen (AP), pelvis (AP), cervical spine (AP), lumbar spine (AP, Lat), hip (AP), thoracic spine (AP, Lat). Three types of data were collected, <em>i.e.</em>, X-ray tube machine data, patient data and output measurements. The data were analyzed statistically and the median, minimum, maximum, and third quartile values were calculated and displayed throughout boxplots graphs for all exams and medical centers. The two sigma range (95% confidence interval) was also checked. Comparison of third quartiles of Entrance Surface Dose (ESD) and Dose Area Product (DAP) by type of examination with recommended international DRLs was performed. The third quartile of ESD for pelvis (AP) and thoracic spine (AP) was up to 16% and 38% higher, respectively than their corresponding DRLs in the European Commission Report RP 180 Part 2. For all exams, except thoracic spine (lat), the third quartiles of the dose area product were higher than the corresponding DRLs in the above report. The source of dose variability between medical centers was related to many parameters such as poor radiographic techniques, lack of modern X-ray machines and adequately documented radiation protection practices. The results show the need to develop protocols for dose measurement as well as to carry out quality assurance programs and dose optimization in Senegal.
