MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal...MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.展开更多
During railway operations,trains normally run as scheduled,but the occurrence of unexpected events will disrupt traffic flow and cause train deviation from the original timetable.In order to assist dispatchers in resc...During railway operations,trains normally run as scheduled,but the occurrence of unexpected events will disrupt traffic flow and cause train deviation from the original timetable.In order to assist dispatchers in rescheduling trains,this paper introduces an innovative Human-Computer Interaction framework.This framework enables train dispatchers to propose different timetable adjustment instructions to the original or adjusted timetable.These instructions will be processed,stored,analyzed,and digested by computer program,which finally lead to the modification and calculation of the embedded mathematical model,then a new adjusted timetable will be produced and provided to dispatchers for checking and modifying.This framework can iterate for unlimited times based on dispatchers'intentions,until the final results satisfy them.A demonstration system named RTARS(Real-time Timetable Automatic Rescheduling System)is developed based on this framework and it has been applied in Beijing Railway Administration,which shows its effectiveness in reality.展开更多
Aim Cerebral venous sinus thrombosis(CVST)is a less common cerebrovascular disease that predominantly affects young patients.The incidence of CVST is 2-5/10000000/year,accounting for 0.5%-1%of all stroke.To reduce mor...Aim Cerebral venous sinus thrombosis(CVST)is a less common cerebrovascular disease that predominantly affects young patients.The incidence of CVST is 2-5/10000000/year,accounting for 0.5%-1%of all stroke.To reduce mortality and morbidity associated with CVST,Chinese Stroke Association commissioned the authors to write the current guideline on the management of CVST.Methods PubMed(MEDLINE),CNKI and Wanfang database were searched for studies related to CVST from 1 January 1990 to 31 July 2019.Data were synthesised by evidence tables.Each recommendation was fully discussed by the writing group members and reviewed by Chinese Stroke Association Stroke Fellow Committees.Levels of evidence grading algorithm of Chinese Stroke Association was used to grade each recommendation.results This guideline mainly focuses on the diagnostic evaluation,therapeutic strategies and secondary prevention of CVST.CT/CTV and MRI/MRV are recommended in the initial imaging evaluation of patients with suspected CVST.Anticoagulation therapy with low-molecular weight heparin should be initiated in patients with CVST immediately.After the acute stage,warfarin is recommended for 3-6 months to prevent the recurrence of CVST and other venous thromboembolic events.Conclusions The guideline summarises the current evidence regarding the management of CVST,and provides references for diagnosis,treatment and secondary prevention of CVST in China.展开更多
Grey matter(GM)alterations may contribute to cognitive decline in individuals with white matter hyperintensities(WMH)but no consensus has yet emerged.Here,we investigated cortical thickness and grey matter volume in 2...Grey matter(GM)alterations may contribute to cognitive decline in individuals with white matter hyperintensities(WMH)but no consensus has yet emerged.Here,we investigated cortical thickness and grey matter volume in 23 WMH patients with mild cognitive impairment(WMH-MCI),43 WMH patients without cognitive impairment,and 55 healthy controls.Both WMH groups showed GM atrophy in the bilateral thalamus,fronto-insular cortices,and several parietal-temporal regions,and the WMH-MCI group showed more extensive and severe GM atrophy.The GM atrophy in the thalamus and fronto-insular cortices was associated with cognitive decline in the WMH-MCI patients and may mediate the relationship between WMH and cognition in WMH patients.Furthermore,the main results were well replicated in an independent dataset from the Alzheimer's Disease Neuroimaging Initiative database and in other control analyses.These comprehensive results provide robust evidence of specific GM alterations underlying WMH and subsequent cognitive impairment.展开更多
基金supported by the National Natural Science Foundation of China(21703147 and U1401248)the support of China Scholarship Council(2018SLJ022487)。
文摘MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.
基金supported by China Railway Research and Development(K2021x001)the Talent Fund of Beijing Jiaotong University(2023JBRC003).
文摘During railway operations,trains normally run as scheduled,but the occurrence of unexpected events will disrupt traffic flow and cause train deviation from the original timetable.In order to assist dispatchers in rescheduling trains,this paper introduces an innovative Human-Computer Interaction framework.This framework enables train dispatchers to propose different timetable adjustment instructions to the original or adjusted timetable.These instructions will be processed,stored,analyzed,and digested by computer program,which finally lead to the modification and calculation of the embedded mathematical model,then a new adjusted timetable will be produced and provided to dispatchers for checking and modifying.This framework can iterate for unlimited times based on dispatchers'intentions,until the final results satisfy them.A demonstration system named RTARS(Real-time Timetable Automatic Rescheduling System)is developed based on this framework and it has been applied in Beijing Railway Administration,which shows its effectiveness in reality.
文摘Aim Cerebral venous sinus thrombosis(CVST)is a less common cerebrovascular disease that predominantly affects young patients.The incidence of CVST is 2-5/10000000/year,accounting for 0.5%-1%of all stroke.To reduce mortality and morbidity associated with CVST,Chinese Stroke Association commissioned the authors to write the current guideline on the management of CVST.Methods PubMed(MEDLINE),CNKI and Wanfang database were searched for studies related to CVST from 1 January 1990 to 31 July 2019.Data were synthesised by evidence tables.Each recommendation was fully discussed by the writing group members and reviewed by Chinese Stroke Association Stroke Fellow Committees.Levels of evidence grading algorithm of Chinese Stroke Association was used to grade each recommendation.results This guideline mainly focuses on the diagnostic evaluation,therapeutic strategies and secondary prevention of CVST.CT/CTV and MRI/MRV are recommended in the initial imaging evaluation of patients with suspected CVST.Anticoagulation therapy with low-molecular weight heparin should be initiated in patients with CVST immediately.After the acute stage,warfarin is recommended for 3-6 months to prevent the recurrence of CVST and other venous thromboembolic events.Conclusions The guideline summarises the current evidence regarding the management of CVST,and provides references for diagnosis,treatment and secondary prevention of CVST in China.
基金This work was supported by the National Natural Science Foundation of China(81801146,81871438,and 81771341)the Natural Science Foundation of Hubei Province(2017CFB392)+2 种基金Beijing Natural Science Funds for Distinguished Young Scholars(JQ200036)the Flagship Program of Tongji Hospital,China(2019CR106).Data collection and sharing for this project was funded by the Alzheimer's Disease Neuroimaging Initiative(ADNI)(National Institutes of Health Grant U01 AG024904)DOD ADNI(Department of Defense Award number W81XWH-12-2-0012).
文摘Grey matter(GM)alterations may contribute to cognitive decline in individuals with white matter hyperintensities(WMH)but no consensus has yet emerged.Here,we investigated cortical thickness and grey matter volume in 23 WMH patients with mild cognitive impairment(WMH-MCI),43 WMH patients without cognitive impairment,and 55 healthy controls.Both WMH groups showed GM atrophy in the bilateral thalamus,fronto-insular cortices,and several parietal-temporal regions,and the WMH-MCI group showed more extensive and severe GM atrophy.The GM atrophy in the thalamus and fronto-insular cortices was associated with cognitive decline in the WMH-MCI patients and may mediate the relationship between WMH and cognition in WMH patients.Furthermore,the main results were well replicated in an independent dataset from the Alzheimer's Disease Neuroimaging Initiative database and in other control analyses.These comprehensive results provide robust evidence of specific GM alterations underlying WMH and subsequent cognitive impairment.
