CMOS-compatible RF/microwave devices,such as filters and amplifiers,have been widely used in wireless communication systems.However,secondary-electron emission phenomena often occur in RF/microwave devices based on si...CMOS-compatible RF/microwave devices,such as filters and amplifiers,have been widely used in wireless communication systems.However,secondary-electron emission phenomena often occur in RF/microwave devices based on silicon(Si)wafers,especially in the high-frequency range.In this paper,we have studied the major factors that influence the secondary-electron yield(SEY)in commercial Si wafers with different doping concentrations.We show that the SEY is suppressed as the doping concentration increases,corresponding to a relatively short effective escape depthλ.Meanwhile,the reduced narrow band gap is beneficial in suppressing the SEY,in which the absence of a shallow energy band below the conduction band will easily capture electrons,as revealed by first-principles calculations.Thus,the new physical mechanism combined with the effective escape depth and band gap can provide useful guidance for the design of integrated RF/microwave devices based on Si wafers.展开更多
Multilayered van der Waals(vdW)materials have attracted increasing interest because of the manipulability of their superior optical,electrical,thermal,and mechanical properties.A mass-spring model(MSM)for elastic wave...Multilayered van der Waals(vdW)materials have attracted increasing interest because of the manipulability of their superior optical,electrical,thermal,and mechanical properties.A mass-spring model(MSM)for elastic wave propagation in multilayered vdW metamaterials is reported in this paper.Molecular dynamics(MD)simulations are adopted to simulate the propagation of elastic waves in multilayered vdW metamaterials.The results show that the graphene/MoS_(2)metamaterials have an elastic wave bandgap in the terahertz range.The MSM for the multilayered vdW metamaterials is proposed,and the numerical simulation results show that this model can well describe the dispersion and transmission characteristics of the multilayered vdW metamaterials.The MSM can predict elastic wave transmission characteristics in multilayered vdW metamaterials stacked with different two-dimensional(2D)materials.The results presented in this paper offer theoretical help for the vibration reduction of multilayered vdW semiconductors.展开更多
Background and Aims:Colorectal cancer is associated with non-alcoholic fatty liver disease(NAFLD)and other metabolic syndromes,such as obesity,abnormal blood glucose,and dyslipidemia.The relationship of NAFLD and colo...Background and Aims:Colorectal cancer is associated with non-alcoholic fatty liver disease(NAFLD)and other metabolic syndromes,such as obesity,abnormal blood glucose,and dyslipidemia.The relationship of NAFLD and colorectal adenoma,which is the precursor of colorectal cancer,is worthy of discussion.The aim of this study was to investigate the association between colorectal adenoma and NAFLD,colorectal adenoma and metabolic syndrome in a Chinese Han population.Methods:This retrospective study analyzed the relationship between NAFLD and colorectal adenoma in 1089 patients in Qingdao municipal hospital.Subjects were divided into a colorectal adenoma group(n=267)and a control group(n=822).NAFLD and the controlled attenuation parameter(CAP)value were determined by abdominal ultrasound and FibroScan.Results:Patients with NAFLD in the colorectal adenoma group and the control group represented 142 cases(53.2%)and 360 cases(43.8%),respectively.The mean CAP value in the colorectal adenoma group was significantly higher than that in the control group.The values of body mass index,triglyceride,high-density lipoprotein cholesterol,aspartate aminotransferase,fasting plasma glucose,and uric acid were also significantly higher in the colorectal adenoma group than in the control group.Multifactor logistic regression analysis showed that the sex,NAFLD,CAP,body mass index,triglyceride,aspartate aminotransferase,and fasting plasma glucose were significant risk factors for colorectal adenoma.Besides,NAFLD and CAP value were significant risk factors for colorectal adenoma in males but not in females.Conclusions:NAFLD and metabolic syndrome were tightly associated with the risk of colorectal adenoma in this Chinese Han population.The effect of NAFLD on colorectal adenoma was prominent in males rather than in females.展开更多
基金Project supported by the Administration of Science,Technology and Industry of National Defense of China (Grant No.HTKJ2021KL504001)the National Natural Science Foundation of China (Grant Nos.12004297 and 12174364)+3 种基金the China Postdoctoral Science Foundation (Grant No.2022M712507)the Fundamental Research Funds for the Central Universities (Grant No.xzy01202003)the National 111 Project of China (Grant No.B14040)the support from the Instrument Analysis Center of Xi’an Jiaotong University。
文摘CMOS-compatible RF/microwave devices,such as filters and amplifiers,have been widely used in wireless communication systems.However,secondary-electron emission phenomena often occur in RF/microwave devices based on silicon(Si)wafers,especially in the high-frequency range.In this paper,we have studied the major factors that influence the secondary-electron yield(SEY)in commercial Si wafers with different doping concentrations.We show that the SEY is suppressed as the doping concentration increases,corresponding to a relatively short effective escape depthλ.Meanwhile,the reduced narrow band gap is beneficial in suppressing the SEY,in which the absence of a shallow energy band below the conduction band will easily capture electrons,as revealed by first-principles calculations.Thus,the new physical mechanism combined with the effective escape depth and band gap can provide useful guidance for the design of integrated RF/microwave devices based on Si wafers.
基金supported by the National Science Fund for Distinguished Young Scholars of China(No.11925205)the National Natural Science Foundation of China(Nos.51921003 and U2341230)。
文摘Multilayered van der Waals(vdW)materials have attracted increasing interest because of the manipulability of their superior optical,electrical,thermal,and mechanical properties.A mass-spring model(MSM)for elastic wave propagation in multilayered vdW metamaterials is reported in this paper.Molecular dynamics(MD)simulations are adopted to simulate the propagation of elastic waves in multilayered vdW metamaterials.The results show that the graphene/MoS_(2)metamaterials have an elastic wave bandgap in the terahertz range.The MSM for the multilayered vdW metamaterials is proposed,and the numerical simulation results show that this model can well describe the dispersion and transmission characteristics of the multilayered vdW metamaterials.The MSM can predict elastic wave transmission characteristics in multilayered vdW metamaterials stacked with different two-dimensional(2D)materials.The results presented in this paper offer theoretical help for the vibration reduction of multilayered vdW semiconductors.
基金supported by grants from the National Natural Science Foundation of China(31770837)the Qingdao People's Livelihood Science and Technology Plan(18-6-1-68-nsh)
文摘Background and Aims:Colorectal cancer is associated with non-alcoholic fatty liver disease(NAFLD)and other metabolic syndromes,such as obesity,abnormal blood glucose,and dyslipidemia.The relationship of NAFLD and colorectal adenoma,which is the precursor of colorectal cancer,is worthy of discussion.The aim of this study was to investigate the association between colorectal adenoma and NAFLD,colorectal adenoma and metabolic syndrome in a Chinese Han population.Methods:This retrospective study analyzed the relationship between NAFLD and colorectal adenoma in 1089 patients in Qingdao municipal hospital.Subjects were divided into a colorectal adenoma group(n=267)and a control group(n=822).NAFLD and the controlled attenuation parameter(CAP)value were determined by abdominal ultrasound and FibroScan.Results:Patients with NAFLD in the colorectal adenoma group and the control group represented 142 cases(53.2%)and 360 cases(43.8%),respectively.The mean CAP value in the colorectal adenoma group was significantly higher than that in the control group.The values of body mass index,triglyceride,high-density lipoprotein cholesterol,aspartate aminotransferase,fasting plasma glucose,and uric acid were also significantly higher in the colorectal adenoma group than in the control group.Multifactor logistic regression analysis showed that the sex,NAFLD,CAP,body mass index,triglyceride,aspartate aminotransferase,and fasting plasma glucose were significant risk factors for colorectal adenoma.Besides,NAFLD and CAP value were significant risk factors for colorectal adenoma in males but not in females.Conclusions:NAFLD and metabolic syndrome were tightly associated with the risk of colorectal adenoma in this Chinese Han population.The effect of NAFLD on colorectal adenoma was prominent in males rather than in females.
基金supported by the National Science Fund for Distinguished Young Scholars (Grant No.11925205)the National Natural Science Foundation of China (Grant No.51921003).
