Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surf...Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surfaces.Meanwhile,the doping effect of metallic surfaces is inevitably present and can significantly tune their electronic and magnetic properties.Here,we investigate the zigzag end states of open-shell 7-armchair graphene nanoribbons(7-AGNRs)on Au(111),Au(100)and Ag(111)surfaces.Combined with the manipulation of a scanning tunneling microscope,we demonstrate that the end states can be tuned from empty states to singly occupied states and to doubly occupied states by substrate doping.Furthermore,the singly occupied states can be finely tuned,with the occupancy number of the states and related magnetic behaviors uncovered by experiments at different temperatures and magnetic fields.Our results provide a comprehensive study of the magnetic response of open-shell GNs on metallic surfaces at different doping levels.展开更多
BACKGROUND： Studies have demonstrated that the risk factors of vascular dementia following stroke are greatly different in region, race and other aspects. OBJECTIVE： To analyze the conditions and incidental risk fac...BACKGROUND： Studies have demonstrated that the risk factors of vascular dementia following stroke are greatly different in region, race and other aspects. OBJECTIVE： To analyze the conditions and incidental risk factors of vascular dementia in patients with acute cerebral infarction from Chongqing City. DESIGN： Case analysis. SETTING： Department of Neurology, Daping Hospital, Third Military Medical University of Chinese PLA. PARTICIPANTS： Altogether 546 inpatients with acute ischemic stroke admitted to Department of Neurology, Daping Hospital, Third Military Medical University of Chinese PLA between May 1999 and December 2002 were involved in this study. The involved patients, including 295 males and 251 females, aged 55 - 94 years, dwelled in Chongqing over 5 years. They were admitted to hospital within 48 hours of attack of acute ischemic stroke, and survived for over 3 months. Informed consents were obtained from all the involved subjects. METHODS： ① Following the same standard, cognitive and social function evaluations were conducted by one physician on admission and 3 months after admission, Unified questionnaire, consisting of general characteristics, vascular risk factors, stroke characteristics, neurological physical sign, and other 28 factors of involved subjects, was used in all the patients. According to the investigation results, the patients were assigned into 2 groups： dementia group and non-dementia group. ②Ischemic stroke was diagnosed according to acute ischemic brain disorder 〉 24 hours and CT or MRI imageology.③ Neurophysiological examination was conducted in all the patients at 7 to l0 days after stroke （score was two SD less than or equaled to normal level was considered as abnormal）. ④Diagnosis and statistics of dementia were carried out with Mini-Mental State Examination and The Diagnostic and Statistical Manual of Mental Disorders-Ⅳ （published by American Psychiatric Association） on admission and 3 months after admission. Neurologic deficit scoring was carried out with the National Institutes of Health Stroke Scale. ⑤ Chi-square test was used for categorical variable, and t test for quantitative variable between dementia group and non-dementia group. Dementia-related factors were performed multiple-factor Logistic regression model analysis. MAIN OUTCOME MEASURES： Incidence of dementia and dementia-related risk factors of patients. RESULTS： Altogether 546 patients with stroke were involved in this study, 403 of them participated in the final analysis, and 143 dropped out. A total of 342 were followed-up in the hospital and 61 at home. At 3 months after cerebral infarction, vascular dementia occurred in 87 （21.6%） of 403 patients. The main risk factors were age （OR 1.179; 95%CI 1.130 - 1.230）, low education level （OR 1.806; 95%CI 1.024 - 3.186）, daily alcohol drinking （OR 3.447; 95%（1/ 1.591 - 7.468）, stroke history （OR 2.531; 95%CI 1.419 - 4.512）, atrial fibrilation（OR 3.475; 95%CI 1.712 - 7.057）, dysphonia （OR 5.873; 95%6/2.620 - 13.163） and left carotid artery infarction （OR 1.975; 95%（1/1.152 - 3.388）. CONCLUSION： The incidence of vascular dementia is determined by synthetic action of multiple risk factors. Dysphonia is the most important influencing factor.展开更多
Wearable sensors have drawn vast interest for their convenience to be worn on body to monitor and track body movements or exercise activities in real time.However,wearable electronics rely on powering systems to funct...Wearable sensors have drawn vast interest for their convenience to be worn on body to monitor and track body movements or exercise activities in real time.However,wearable electronics rely on powering systems to function.Herein,a self-powered,porous,flexible,hydrophobic and breathable nanofibrous membrane based on electrospun polyvinylidene fluoride(PVDF)nanofiber has been developed as a tactile sensor with low-cost and simple fabrication for human body motion detection and recognition.Specifically,effects of multi-walled carbon nanotubes(CNT)and barium titanate(BTO)as additives to the fiber morphology as well as mechanical and dielectric properties of the piezoelectric nanofiber membrane were investigated.The fabricated BTO@PVDF piezoelectric nanogenerator(PENG)exhibits the highβ-phase content and best overall electrical performances,thus selected for the flexible sensing device assembly.Meanwhile,the nanofibrous membrane demonstrated robust tactile sensing performance that the device exhibits durability over 12,000 loading test cycles,holds a fast response time of 82.7 ms,responds to a wide pressure range of 0-5 bar and shows a high relative sensitivity,especially in the small force range of 11.6 V/bar upon pressure applied perpendicular to the surface.Furthermore,when attached on human body,its unique fibrous and flexible structure offers the tactile sensor to present as a health care monitor in a self-powered manner by translating motions of different movements to electrical signals with various patterns or sequences.展开更多
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030002)the National Natural Science Foundation of China(Grant Nos.11974431,and 11774434)the support from the Hundreds of Talents Program of Sun Yat-sen University and Guangdong Science and Technology Project(Grant No.2021QN02X859)。
文摘Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surfaces.Meanwhile,the doping effect of metallic surfaces is inevitably present and can significantly tune their electronic and magnetic properties.Here,we investigate the zigzag end states of open-shell 7-armchair graphene nanoribbons(7-AGNRs)on Au(111),Au(100)and Ag(111)surfaces.Combined with the manipulation of a scanning tunneling microscope,we demonstrate that the end states can be tuned from empty states to singly occupied states and to doubly occupied states by substrate doping.Furthermore,the singly occupied states can be finely tuned,with the occupancy number of the states and related magnetic behaviors uncovered by experiments at different temperatures and magnetic fields.Our results provide a comprehensive study of the magnetic response of open-shell GNs on metallic surfaces at different doping levels.
文摘BACKGROUND： Studies have demonstrated that the risk factors of vascular dementia following stroke are greatly different in region, race and other aspects. OBJECTIVE： To analyze the conditions and incidental risk factors of vascular dementia in patients with acute cerebral infarction from Chongqing City. DESIGN： Case analysis. SETTING： Department of Neurology, Daping Hospital, Third Military Medical University of Chinese PLA. PARTICIPANTS： Altogether 546 inpatients with acute ischemic stroke admitted to Department of Neurology, Daping Hospital, Third Military Medical University of Chinese PLA between May 1999 and December 2002 were involved in this study. The involved patients, including 295 males and 251 females, aged 55 - 94 years, dwelled in Chongqing over 5 years. They were admitted to hospital within 48 hours of attack of acute ischemic stroke, and survived for over 3 months. Informed consents were obtained from all the involved subjects. METHODS： ① Following the same standard, cognitive and social function evaluations were conducted by one physician on admission and 3 months after admission, Unified questionnaire, consisting of general characteristics, vascular risk factors, stroke characteristics, neurological physical sign, and other 28 factors of involved subjects, was used in all the patients. According to the investigation results, the patients were assigned into 2 groups： dementia group and non-dementia group. ②Ischemic stroke was diagnosed according to acute ischemic brain disorder 〉 24 hours and CT or MRI imageology.③ Neurophysiological examination was conducted in all the patients at 7 to l0 days after stroke （score was two SD less than or equaled to normal level was considered as abnormal）. ④Diagnosis and statistics of dementia were carried out with Mini-Mental State Examination and The Diagnostic and Statistical Manual of Mental Disorders-Ⅳ （published by American Psychiatric Association） on admission and 3 months after admission. Neurologic deficit scoring was carried out with the National Institutes of Health Stroke Scale. ⑤ Chi-square test was used for categorical variable, and t test for quantitative variable between dementia group and non-dementia group. Dementia-related factors were performed multiple-factor Logistic regression model analysis. MAIN OUTCOME MEASURES： Incidence of dementia and dementia-related risk factors of patients. RESULTS： Altogether 546 patients with stroke were involved in this study, 403 of them participated in the final analysis, and 143 dropped out. A total of 342 were followed-up in the hospital and 61 at home. At 3 months after cerebral infarction, vascular dementia occurred in 87 （21.6%） of 403 patients. The main risk factors were age （OR 1.179; 95%CI 1.130 - 1.230）, low education level （OR 1.806; 95%CI 1.024 - 3.186）, daily alcohol drinking （OR 3.447; 95%（1/ 1.591 - 7.468）, stroke history （OR 2.531; 95%CI 1.419 - 4.512）, atrial fibrilation（OR 3.475; 95%CI 1.712 - 7.057）, dysphonia （OR 5.873; 95%6/2.620 - 13.163） and left carotid artery infarction （OR 1.975; 95%（1/1.152 - 3.388）. CONCLUSION： The incidence of vascular dementia is determined by synthetic action of multiple risk factors. Dysphonia is the most important influencing factor.
基金National Research Foundation(Sustainable Tropical Data Centre Test bed:A-0009465-05-00)L.J.C would like to acknowledge the support from NUS Research Scholarship(GOSU00000042 PVO ARS-FOE 101 IS).
文摘Wearable sensors have drawn vast interest for their convenience to be worn on body to monitor and track body movements or exercise activities in real time.However,wearable electronics rely on powering systems to function.Herein,a self-powered,porous,flexible,hydrophobic and breathable nanofibrous membrane based on electrospun polyvinylidene fluoride(PVDF)nanofiber has been developed as a tactile sensor with low-cost and simple fabrication for human body motion detection and recognition.Specifically,effects of multi-walled carbon nanotubes(CNT)and barium titanate(BTO)as additives to the fiber morphology as well as mechanical and dielectric properties of the piezoelectric nanofiber membrane were investigated.The fabricated BTO@PVDF piezoelectric nanogenerator(PENG)exhibits the highβ-phase content and best overall electrical performances,thus selected for the flexible sensing device assembly.Meanwhile,the nanofibrous membrane demonstrated robust tactile sensing performance that the device exhibits durability over 12,000 loading test cycles,holds a fast response time of 82.7 ms,responds to a wide pressure range of 0-5 bar and shows a high relative sensitivity,especially in the small force range of 11.6 V/bar upon pressure applied perpendicular to the surface.Furthermore,when attached on human body,its unique fibrous and flexible structure offers the tactile sensor to present as a health care monitor in a self-powered manner by translating motions of different movements to electrical signals with various patterns or sequences.
