航天器运行在恶劣的空间环境中容易引发充放电现象,而叠加电磁场会导致其在较低的充电电位下发生放电,严重威胁航天器的安全运行。为揭示强电磁场诱发真空沿面放电的机理并提出抑制方法,该文采用离子交换方法对聚酰亚胺(polyimide,PI)...航天器运行在恶劣的空间环境中容易引发充放电现象,而叠加电磁场会导致其在较低的充电电位下发生放电,严重威胁航天器的安全运行。为揭示强电磁场诱发真空沿面放电的机理并提出抑制方法,该文采用离子交换方法对聚酰亚胺(polyimide,PI)薄膜表面进行改性处理,并基于搭建的强电磁场诱发真空沿面放电平台,结合表面陷阱、二次电子发射系数(secondary electron emission yields,SEEY)等表征手段,系统分析表面改性对抑制强电磁场诱发PI薄膜沿面放电的机理。结果表明:改性后的PI表面引入大量浅陷阱,显著降低PI薄膜的表面电阻率和SEEY,并提升了材料表面电荷的积聚与消散速率。同时,浅陷阱的引入降低了PI薄膜的SEEY和直流场下的极化能,抑制气体的解吸附与电离及二次电子倍增过程,从而显著提升了PI薄膜在抑制强电磁场诱发真空沿面放电方面的能力。该研究有望为强电磁场诱发航天器表面沿面放电的防护设计提供参考。展开更多
Pholis fangi is an ecologically important fish species inhabiting Chinese coastal waters of Yellow Sea and Bohai Sea. To investigate the genetic diversity and population genetic structure of P. fangi, a fragment of 48...Pholis fangi is an ecologically important fish species inhabiting Chinese coastal waters of Yellow Sea and Bohai Sea. To investigate the genetic diversity and population genetic structure of P. fangi, a fragment of 487 bp in the first hypervariable region (HVR-1) of the mitochondrial DNA (mtDNA) control region was sequenced for 181 individuals collected from Bohai Sea and Yel- low Sea. A total of 18 polymorphic sites were detected, which defined 25 haplotypes. A moderate level of haplotype diversity (h = 0.7052) and a low level of nucleotide diversity (π= 0.0028) were detected. Both the phylogenetic tree and the haplotype network showed no significant genealogical structure difference among sampling locations. Pairwise FST comparison and hierarchical mo- lecular variance analysis (AMOVA) revealed that no significant genetic structure difference existed throughout the investigated re- gions, suggesting a high gene exchange among different populations. The results of neutrality test and mismatch distribution analysis indicated that a late Pleistocene population expansion (38000 127000 years ago) happened. Seasonal schooling migration may con- tribute to the genetically homogeneous population structure of the species.展开更多
Recently,surface-enhanced Raman scattering(SERS)has been successfully used in the non-invasive detection of bladder tumor(BCa).The internal standard method was considered as an effective ratiometric strategy for calib...Recently,surface-enhanced Raman scattering(SERS)has been successfully used in the non-invasive detection of bladder tumor(BCa).The internal standard method was considered as an effective ratiometric strategy for calibrating signal fluctuation originated from the interference of measurement conditions and samples.However,it is still difficult to detect the target mRNA quantitatively using the current ratiometric SERS nanosensors.In this study,we developed an internal reference based ratiometric SERS assay.Two kinds of molecular beacons(MB)carrying Raman reporter molecules were anchored on sea-urchinlike Au nanoclusters(AuNCs).Thymidine kinase1(TK1)MBs with hexachlorofluorescein(HEX)were used to capture tumor biomarker TK1 mRNA,and glyceraldehyde 3-phosphate dehydrogenase(GAPDH)MBs with 5(6)-carboxyfluorescein(FAM)were used to offer internal standard signals.The internal reference GAPDH MB can reflect the consistent content of the GAPDH mRNA in single cells.The ratiometric method(I745/I645)can more accurately reflect the content of target mRNA in single cells.The ratiometric nanoprobes had excellent stability(coefficient of variation:0.3%),high sensitivity(detection limit:3.4 pM),high specificity(capable of single-base mismatch recognition)and ribozyme-resistant stability.Notably,the nanoprobes can effectively distinguish BCa cells from normal cells,and it was easy to contour the single BCa cell using the ratiometric method.By combining asymmetric polymerase chain reaction(PCR)and ratiometric nanoprobes,it was easy to distinguish the SERS ratio(I_(745)/I_(645))as low concentration as 10-14 M.Further clinical detection in urine samples from patients with BCa confirmed its potential for early noninvasive diagnosis of BCa with the sensitivity of 80%and specificity of 100%,which is superior to the current urine cytological method.展开更多
One of the critical problems in bladder cancer(BC)management is the local recurrence of disease.However,achieving the accurate delineation of tumor margins intraoperatively remains extremely difficult due to the lack ...One of the critical problems in bladder cancer(BC)management is the local recurrence of disease.However,achieving the accurate delineation of tumor margins intraoperatively remains extremely difficult due to the lack of effective tumor margin recognition technology.Herein,survivin molecular beacon(MB)and R11 peptide-linked spherical nucleic acids(SNAs)were synthesized as nanoprobes(AuNP-MB@R11)for sensitive detection of BC margins.Physicochemical properties proved that R11 peptides and survivin MB were successfully loaded onto the surface of SNAs.AuNP-MB@R11 had good stability against nuclease activity and high sensitivity and specificity to detect survivin single strand DNA(ssDNA)in vitro.According to cytology,R11 peptides could increase the BC targeting ability and membrane penetrability of SNAs.Notably,R11 peptides significantly promoted the disintegration of lysosomes and the release of SNAs to enhance fluorescence imaging quality.Further RNA sequencing proved that some genes and pathways related to endocytosis and lysosomes were significantly regulated,such as AGPAT5,GPD1L,and GRB2.In orthotopic BC models and a clinical sample from a patient with BC,AuNP-MB@R11 showed a more legible cancerous fluorescence margin and offered remarkably improved detection compared to those achieved by SNAs.R11 peptide-linked SNAs present promising potential to identify BC margin,which may help to improve the R0 resection rate in surgery and improve patients’quality of life.展开更多
文摘航天器运行在恶劣的空间环境中容易引发充放电现象,而叠加电磁场会导致其在较低的充电电位下发生放电,严重威胁航天器的安全运行。为揭示强电磁场诱发真空沿面放电的机理并提出抑制方法,该文采用离子交换方法对聚酰亚胺(polyimide,PI)薄膜表面进行改性处理,并基于搭建的强电磁场诱发真空沿面放电平台,结合表面陷阱、二次电子发射系数(secondary electron emission yields,SEEY)等表征手段,系统分析表面改性对抑制强电磁场诱发PI薄膜沿面放电的机理。结果表明:改性后的PI表面引入大量浅陷阱,显著降低PI薄膜的表面电阻率和SEEY,并提升了材料表面电荷的积聚与消散速率。同时,浅陷阱的引入降低了PI薄膜的SEEY和直流场下的极化能,抑制气体的解吸附与电离及二次电子倍增过程,从而显著提升了PI薄膜在抑制强电磁场诱发真空沿面放电方面的能力。该研究有望为强电磁场诱发航天器表面沿面放电的防护设计提供参考。
基金supported by the National Natural Science Foundation of China (No. 41776171)
文摘Pholis fangi is an ecologically important fish species inhabiting Chinese coastal waters of Yellow Sea and Bohai Sea. To investigate the genetic diversity and population genetic structure of P. fangi, a fragment of 487 bp in the first hypervariable region (HVR-1) of the mitochondrial DNA (mtDNA) control region was sequenced for 181 individuals collected from Bohai Sea and Yel- low Sea. A total of 18 polymorphic sites were detected, which defined 25 haplotypes. A moderate level of haplotype diversity (h = 0.7052) and a low level of nucleotide diversity (π= 0.0028) were detected. Both the phylogenetic tree and the haplotype network showed no significant genealogical structure difference among sampling locations. Pairwise FST comparison and hierarchical mo- lecular variance analysis (AMOVA) revealed that no significant genetic structure difference existed throughout the investigated re- gions, suggesting a high gene exchange among different populations. The results of neutrality test and mismatch distribution analysis indicated that a late Pleistocene population expansion (38000 127000 years ago) happened. Seasonal schooling migration may con- tribute to the genetically homogeneous population structure of the species.
基金This work was supported by the National Natural Science Foundation of China(No.81901838)the Key Research and Development Plan in Shaanxi Province(Nos.2020SF-123 and 2020SF-195)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LQ21H160041)the Medical Research Program of Department of Science and Technology of Xi’an,Shaanxi Province(No.2019115713YX012SF048(4)).
文摘Recently,surface-enhanced Raman scattering(SERS)has been successfully used in the non-invasive detection of bladder tumor(BCa).The internal standard method was considered as an effective ratiometric strategy for calibrating signal fluctuation originated from the interference of measurement conditions and samples.However,it is still difficult to detect the target mRNA quantitatively using the current ratiometric SERS nanosensors.In this study,we developed an internal reference based ratiometric SERS assay.Two kinds of molecular beacons(MB)carrying Raman reporter molecules were anchored on sea-urchinlike Au nanoclusters(AuNCs).Thymidine kinase1(TK1)MBs with hexachlorofluorescein(HEX)were used to capture tumor biomarker TK1 mRNA,and glyceraldehyde 3-phosphate dehydrogenase(GAPDH)MBs with 5(6)-carboxyfluorescein(FAM)were used to offer internal standard signals.The internal reference GAPDH MB can reflect the consistent content of the GAPDH mRNA in single cells.The ratiometric method(I745/I645)can more accurately reflect the content of target mRNA in single cells.The ratiometric nanoprobes had excellent stability(coefficient of variation:0.3%),high sensitivity(detection limit:3.4 pM),high specificity(capable of single-base mismatch recognition)and ribozyme-resistant stability.Notably,the nanoprobes can effectively distinguish BCa cells from normal cells,and it was easy to contour the single BCa cell using the ratiometric method.By combining asymmetric polymerase chain reaction(PCR)and ratiometric nanoprobes,it was easy to distinguish the SERS ratio(I_(745)/I_(645))as low concentration as 10-14 M.Further clinical detection in urine samples from patients with BCa confirmed its potential for early noninvasive diagnosis of BCa with the sensitivity of 80%and specificity of 100%,which is superior to the current urine cytological method.
基金the National Natural Science Foundation of China(No.81901838)Key research and development plan in Shaanxi province(Nos.2020SF-123 and 2020SF-195)+1 种基金Medical Technology Plan of Zhejiang Province(No.2021KY042)Medical research program of department of science and technology of Xi’an,Shaanxi Province(No.2019115713YX012SF048(4)).
文摘One of the critical problems in bladder cancer(BC)management is the local recurrence of disease.However,achieving the accurate delineation of tumor margins intraoperatively remains extremely difficult due to the lack of effective tumor margin recognition technology.Herein,survivin molecular beacon(MB)and R11 peptide-linked spherical nucleic acids(SNAs)were synthesized as nanoprobes(AuNP-MB@R11)for sensitive detection of BC margins.Physicochemical properties proved that R11 peptides and survivin MB were successfully loaded onto the surface of SNAs.AuNP-MB@R11 had good stability against nuclease activity and high sensitivity and specificity to detect survivin single strand DNA(ssDNA)in vitro.According to cytology,R11 peptides could increase the BC targeting ability and membrane penetrability of SNAs.Notably,R11 peptides significantly promoted the disintegration of lysosomes and the release of SNAs to enhance fluorescence imaging quality.Further RNA sequencing proved that some genes and pathways related to endocytosis and lysosomes were significantly regulated,such as AGPAT5,GPD1L,and GRB2.In orthotopic BC models and a clinical sample from a patient with BC,AuNP-MB@R11 showed a more legible cancerous fluorescence margin and offered remarkably improved detection compared to those achieved by SNAs.R11 peptide-linked SNAs present promising potential to identify BC margin,which may help to improve the R0 resection rate in surgery and improve patients’quality of life.
