Theoretically,copper–niobium(Cu-Nb)composite superconducting cavities have excellent potential for high thermal and mechanical stability.They can appropriately exploit the high-gradient surface processing recipes dev...Theoretically,copper–niobium(Cu-Nb)composite superconducting cavities have excellent potential for high thermal and mechanical stability.They can appropriately exploit the high-gradient surface processing recipes developed for the bulk niobium(Nb)cavity and the thick copper(Cu)layer’s high thermal conductivity and rigidity,thereby enhancing the operational stability of the bulk Nb cavities.This study conducted a global review of the technical approaches employed for fabricating Cu-Nb composite superconducting cavities.We explored Cu-Nb composite superconducting cavities based on two technologies at the Institute of Modern Physics,Chinese Academy of Sciences(IMP,CAS),including their manufacturing processes,radio-frequency(RF)characteristics,and mechanical performance.These cavities exhibit robust mechanical stability.First,the investigation of several 1.3 GHz single-cell elliptical cavities using the Cu-Nb composite sheets indicated that the wavy structure at the Cu-Nb interface influenced the reliable welding of the Cu-Nb composite parts.We observed the generation and trapping of magnetic flux density during the T_c crossing of Nb in cooldown process.The cooling rates during the T_c crossing of Nb exerted a substantial impact on the performance of the cavities.Furthermore,we measured and analyzed the surface resistance R_(s)attributed to the trapped magnetic flux induced by the Seebeck effect after quenching events.Second,for the first time,a low-beta bulk Nb cavity was plated with Cu on its outer surface using electroplating technology.We achieved a high peak electric field E_(pk)of~88.8 MV/m at 2 K and the unloaded quality factor Q_(0)at the E_(pk)of 88.8 MV/m exceeded 1×10^(10).This demonstrated that the electroplating Cu on the bulk Nb cavity is a practical method of developing the Cu-Nb composite superconducting cavity with superior thermal stability.The results presented here provide valuable insights for applying Cu-Nb composite superconducting cavities in superconducting accelerators with stringent operational stability requirements.展开更多
BACKGROUND Preoperative distinguishing between benign and malignant gastrointestinal stromal tumors(GISTs)poses a challenge.Ultrasound elastography has emerged as a promising diagnostic tool;however,further investigat...BACKGROUND Preoperative distinguishing between benign and malignant gastrointestinal stromal tumors(GISTs)poses a challenge.Ultrasound elastography has emerged as a promising diagnostic tool;however,further investigation is needed to assess its diagnostic accuracy in evaluating GISTs.AIM To evaluate the accuracy of ultrasound elastography for differentiating between benign and malignant GISTs.METHODS This prospective study included 110 patients with 103 histopathologically confirmed GISTs between January 2021 and December 2023.All tumors underwent conventional ultrasound examination,strain elastography(SE),and shearwave elastography(SWE)before surgical resection.The study evaluated elastographic parameters such as strain ratio,elastographic patterns,mean elastic modulus,and heterogeneity index.Diagnostic performance was evaluated using receiver operating characteristic curve analysis,with histopathological diagnosis as the reference standard.RESULTS Of the 103 GISTs,45(43.7%)were benign and 58(56.3%)were malignant based on modified National Institutes of Health criteria.Malignant GISTs exhibited significantly higher strain ratios(4.82±1.73 vs 2.31±0.89;P<0.001)and mean elastic modulus values(45.6±15.8 kPa vs 21.3±8.4 kPa;P<0.001)than benign tumors.The optimal cutoff values were 3.45 for the strain ratio(sensitivity:84.5%,specificity:86.7%)and 32.5 kPa for the mean elastic modulus(sensitivity:87.9%,specificity:88.9%).The areas under the curve were 0.892 and 0.918,respectively.Interobserver agreement was excellent for both SE[intraclass correlation coefficient(ICC)=0.88]and SWE(ICC range:0.85-0.93)measurements.CONCLUSION Ultrasound elastography shows high diagnostic accuracy in distinguishing between benign and malignant GISTs.Combining SE and SWE provides complementary parameters for preoperative risk stratification.展开更多
基金supported by the Large Research Infrastructures China initiative Accelerator Driven System(No.2017-000052-75-01-000590)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2022422)+1 种基金the Young Scientists of National Natural Science Foundation of China(No.12005275)the Advanced Energy Science and Technology Guangdong Laboratory(No.HND22PTZZYY)。
文摘Theoretically,copper–niobium(Cu-Nb)composite superconducting cavities have excellent potential for high thermal and mechanical stability.They can appropriately exploit the high-gradient surface processing recipes developed for the bulk niobium(Nb)cavity and the thick copper(Cu)layer’s high thermal conductivity and rigidity,thereby enhancing the operational stability of the bulk Nb cavities.This study conducted a global review of the technical approaches employed for fabricating Cu-Nb composite superconducting cavities.We explored Cu-Nb composite superconducting cavities based on two technologies at the Institute of Modern Physics,Chinese Academy of Sciences(IMP,CAS),including their manufacturing processes,radio-frequency(RF)characteristics,and mechanical performance.These cavities exhibit robust mechanical stability.First,the investigation of several 1.3 GHz single-cell elliptical cavities using the Cu-Nb composite sheets indicated that the wavy structure at the Cu-Nb interface influenced the reliable welding of the Cu-Nb composite parts.We observed the generation and trapping of magnetic flux density during the T_c crossing of Nb in cooldown process.The cooling rates during the T_c crossing of Nb exerted a substantial impact on the performance of the cavities.Furthermore,we measured and analyzed the surface resistance R_(s)attributed to the trapped magnetic flux induced by the Seebeck effect after quenching events.Second,for the first time,a low-beta bulk Nb cavity was plated with Cu on its outer surface using electroplating technology.We achieved a high peak electric field E_(pk)of~88.8 MV/m at 2 K and the unloaded quality factor Q_(0)at the E_(pk)of 88.8 MV/m exceeded 1×10^(10).This demonstrated that the electroplating Cu on the bulk Nb cavity is a practical method of developing the Cu-Nb composite superconducting cavity with superior thermal stability.The results presented here provide valuable insights for applying Cu-Nb composite superconducting cavities in superconducting accelerators with stringent operational stability requirements.
文摘BACKGROUND Preoperative distinguishing between benign and malignant gastrointestinal stromal tumors(GISTs)poses a challenge.Ultrasound elastography has emerged as a promising diagnostic tool;however,further investigation is needed to assess its diagnostic accuracy in evaluating GISTs.AIM To evaluate the accuracy of ultrasound elastography for differentiating between benign and malignant GISTs.METHODS This prospective study included 110 patients with 103 histopathologically confirmed GISTs between January 2021 and December 2023.All tumors underwent conventional ultrasound examination,strain elastography(SE),and shearwave elastography(SWE)before surgical resection.The study evaluated elastographic parameters such as strain ratio,elastographic patterns,mean elastic modulus,and heterogeneity index.Diagnostic performance was evaluated using receiver operating characteristic curve analysis,with histopathological diagnosis as the reference standard.RESULTS Of the 103 GISTs,45(43.7%)were benign and 58(56.3%)were malignant based on modified National Institutes of Health criteria.Malignant GISTs exhibited significantly higher strain ratios(4.82±1.73 vs 2.31±0.89;P<0.001)and mean elastic modulus values(45.6±15.8 kPa vs 21.3±8.4 kPa;P<0.001)than benign tumors.The optimal cutoff values were 3.45 for the strain ratio(sensitivity:84.5%,specificity:86.7%)and 32.5 kPa for the mean elastic modulus(sensitivity:87.9%,specificity:88.9%).The areas under the curve were 0.892 and 0.918,respectively.Interobserver agreement was excellent for both SE[intraclass correlation coefficient(ICC)=0.88]and SWE(ICC range:0.85-0.93)measurements.CONCLUSION Ultrasound elastography shows high diagnostic accuracy in distinguishing between benign and malignant GISTs.Combining SE and SWE provides complementary parameters for preoperative risk stratification.
