The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexpone...The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexponential distribution of open times. One scheme is mathematically strict based on generator matrix theory, while the other one has a clear physical explanation according to an approximation process with numerical simulation of Markovian channel dynamics. Our comparison results suggest that even for biologically complex channels, in addition to carrying out a stochastic simulation, the strict theoretical analysis should be considered to understand the multiple exponential distributions of open times.展开更多
Background The diagnosis of liver fibrosis is a difficult task at any time using conventional clinical imaging.Intravoxel incoherent motion （IVIM） can be used to investigate both diffusion and perfusion changes in t...Background The diagnosis of liver fibrosis is a difficult task at any time using conventional clinical imaging.Intravoxel incoherent motion （IVIM） can be used to investigate both diffusion and perfusion changes in tissues.This study was designed to determine the value of IVIM in the diagnosis and staging of liver fibrosis.Methods IVIM examinations were performed on a GE 3.0T MR scanner in 25 patients with liver fibrosis and 25 healthy volunteers as the control group.Patients with liver fibrosis diagnosis were confirmed by pathology and staged on a scale of F0-4.The standard ADC values and the values of a biexponential model （slow ADC （Dslow）,fast ADC （Dfast） and fraction of fast ADC （FF）） were measured in three liver regions per person.The mean standard ADC values,Dslow values,Dfast values and FF values from the study group were compared among the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Receiver Operating Characteristic （ROC） curves and independent-samples t-tests were used to calculate the mean standard ADC values,Dslow values,Dfast values and FF values from the study group and the control group.Spearman rho correlation analysis was used for the stage of liver fibrosis.The liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 were compared.Results Among the liver fibrosis,there was no significant difference in the mean standard ADC values,Dslow values,Dfast values,and FF values obtained from the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Using ROC analysis,the Area Under the Curve （AUC） values of standard ADC,Dslow,Dfast,FF were all between 0.7 to 0.9.The mean standard ADC values,Dslow values,Dfast values and FF values of the liver in the study group were significantly lower than the values in the control group （P ＜0.05）.As the stage of the fibrosis increased,the values decreased by Spearman rho correlation analysis.The mean values （standard ADC,Dslow,Dfast,and FF） of liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 showed significant differences （P＜0.05）.Conclusions IVIM can reflect the conditions of perfusion and diffusion in liver fibrosis and thus distinguish between normal liver and liver fibrosis.The IVIM technique may serve as a valuable tool for detecting and characterizing liver fibrosis,and monitoring its progression in a noninvasive manner.展开更多
Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A...Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A retrospective study was performed in 54 patients with pathologically confirmed malignant tumors(n=30),benign lesions(n=34)and normal fibroglandular展开更多
Inverted perovskite solar cells(PSCs)have attracted increasing attention in recent years owing to their low-temperature fabrication proces s.However,they suffer from a limited number of electron transport materials av...Inverted perovskite solar cells(PSCs)have attracted increasing attention in recent years owing to their low-temperature fabrication proces s.However,they suffer from a limited number of electron transport materials available with[6,6]-phenyl C61 butyric acid methyl ester(PCBM)to be the most widely studied based on its appropriate energy levels and high electron mobility.The low relative permittivity and aggregation tendency upon illumination of PCBM,however,compromises the solar cell efficiency whereas its modest hydrophobicity negatively impacts on the device stability.Alternative electron transport materials with desired properties and appropriate degree of hydrophobicity are thus desirable for further developments in inverted PSCs.Herein,we synthesize a triethyleneglycol C60 mono-adduct derivative(termed as EPF03)and test it as a novel electron transport material to replace PCBM in inverted PSCs based on a quadruple cation(RbCsMAFA)perovskite.We also compare this derivative with two novel fullerenes decorated with two(EPF01)or one dodecyl(EPF02)long side chains.The latter two fail to perform efficiently in inverted PSCs whereas the former enabled a power conversion efficiency of 18.43%,which represents a 9%improvement compared to the reference device using PCBM(17.21%).The enhanced performance mainly stems from improved electron extraction and reduced recombination enabled by the insertion of the large relative permittivity amongst other properties of EPF03.Furthermore,our results indicate that triethylene glycol side chains can also passivate perovskite trap states,suppress ion migration and enhance photostability and long-term stability of EPF03 based perovskite solar cells.展开更多
Information about the exact location of topological and cohesional entanglements at molecular level has been obtained by 13C NMR relaxation analysis. The results show that about 20% of the carbon atoms in the main cha...Information about the exact location of topological and cohesional entanglements at molecular level has been obtained by 13C NMR relaxation analysis. The results show that about 20% of the carbon atoms in the main chain are entangled in the 25% (by weight) solution, which is independent of the content of the 1,2-segment in polybutadiene and of the kind of solvent. However, the entanglement of the carbon atone on the end group of the side chain is very weak, they behave as slipping freely at the junctions.展开更多
基金Project supported by the National Natural Science Foundations of China(Grant Nos.11504214,31370830,and 11675134)the 111 Project,China(Grant No.B16029)the China Postdoctoral Science Foundation(Grant No.2016M602071)
文摘The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexponential distribution of open times. One scheme is mathematically strict based on generator matrix theory, while the other one has a clear physical explanation according to an approximation process with numerical simulation of Markovian channel dynamics. Our comparison results suggest that even for biologically complex channels, in addition to carrying out a stochastic simulation, the strict theoretical analysis should be considered to understand the multiple exponential distributions of open times.
文摘Background The diagnosis of liver fibrosis is a difficult task at any time using conventional clinical imaging.Intravoxel incoherent motion （IVIM） can be used to investigate both diffusion and perfusion changes in tissues.This study was designed to determine the value of IVIM in the diagnosis and staging of liver fibrosis.Methods IVIM examinations were performed on a GE 3.0T MR scanner in 25 patients with liver fibrosis and 25 healthy volunteers as the control group.Patients with liver fibrosis diagnosis were confirmed by pathology and staged on a scale of F0-4.The standard ADC values and the values of a biexponential model （slow ADC （Dslow）,fast ADC （Dfast） and fraction of fast ADC （FF）） were measured in three liver regions per person.The mean standard ADC values,Dslow values,Dfast values and FF values from the study group were compared among the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Receiver Operating Characteristic （ROC） curves and independent-samples t-tests were used to calculate the mean standard ADC values,Dslow values,Dfast values and FF values from the study group and the control group.Spearman rho correlation analysis was used for the stage of liver fibrosis.The liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 were compared.Results Among the liver fibrosis,there was no significant difference in the mean standard ADC values,Dslow values,Dfast values,and FF values obtained from the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Using ROC analysis,the Area Under the Curve （AUC） values of standard ADC,Dslow,Dfast,FF were all between 0.7 to 0.9.The mean standard ADC values,Dslow values,Dfast values and FF values of the liver in the study group were significantly lower than the values in the control group （P ＜0.05）.As the stage of the fibrosis increased,the values decreased by Spearman rho correlation analysis.The mean values （standard ADC,Dslow,Dfast,and FF） of liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 showed significant differences （P＜0.05）.Conclusions IVIM can reflect the conditions of perfusion and diffusion in liver fibrosis and thus distinguish between normal liver and liver fibrosis.The IVIM technique may serve as a valuable tool for detecting and characterizing liver fibrosis,and monitoring its progression in a noninvasive manner.
文摘Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A retrospective study was performed in 54 patients with pathologically confirmed malignant tumors(n=30),benign lesions(n=34)and normal fibroglandular
基金T.S.and E.R.S acknowledge funding from the DFG in the frame of the SPP2196(project numbers 424156582 and 423660474)G.C.V.and L.P.Z.acknowledge funding provided by the Special Account for Research Grants of the National and Kapodistrian University of Athens(research projects 14872,16294,16598,17168,and 17784)+2 种基金Dr.Eleftherios K.Pefkianakis and Anastasios Misichronis are acknowledged for some initial contributions in the synthesis of the fullerene derivatives.This work was also supported by the research project"HELIOKERAMOs"-MIS 5066858funded by the Operational Programme(EPAnEK)"Competitiveness,Entrepreneurship and Innovation"(NSRF2014-2020)under the special action"lndustrial Materials"and co-financed by Greece and the European Union(European Regional Development Fund).
文摘Inverted perovskite solar cells(PSCs)have attracted increasing attention in recent years owing to their low-temperature fabrication proces s.However,they suffer from a limited number of electron transport materials available with[6,6]-phenyl C61 butyric acid methyl ester(PCBM)to be the most widely studied based on its appropriate energy levels and high electron mobility.The low relative permittivity and aggregation tendency upon illumination of PCBM,however,compromises the solar cell efficiency whereas its modest hydrophobicity negatively impacts on the device stability.Alternative electron transport materials with desired properties and appropriate degree of hydrophobicity are thus desirable for further developments in inverted PSCs.Herein,we synthesize a triethyleneglycol C60 mono-adduct derivative(termed as EPF03)and test it as a novel electron transport material to replace PCBM in inverted PSCs based on a quadruple cation(RbCsMAFA)perovskite.We also compare this derivative with two novel fullerenes decorated with two(EPF01)or one dodecyl(EPF02)long side chains.The latter two fail to perform efficiently in inverted PSCs whereas the former enabled a power conversion efficiency of 18.43%,which represents a 9%improvement compared to the reference device using PCBM(17.21%).The enhanced performance mainly stems from improved electron extraction and reduced recombination enabled by the insertion of the large relative permittivity amongst other properties of EPF03.Furthermore,our results indicate that triethylene glycol side chains can also passivate perovskite trap states,suppress ion migration and enhance photostability and long-term stability of EPF03 based perovskite solar cells.
文摘Information about the exact location of topological and cohesional entanglements at molecular level has been obtained by 13C NMR relaxation analysis. The results show that about 20% of the carbon atoms in the main chain are entangled in the 25% (by weight) solution, which is independent of the content of the 1,2-segment in polybutadiene and of the kind of solvent. However, the entanglement of the carbon atone on the end group of the side chain is very weak, they behave as slipping freely at the junctions.
