By using the fixed point theorem under the case structure, we study the existence of sign-changing solutions of A class of second-order differential equations three-point boundary-value problems, and a positive soluti...By using the fixed point theorem under the case structure, we study the existence of sign-changing solutions of A class of second-order differential equations three-point boundary-value problems, and a positive solution and a negative solution are obtained respectively, so as to popularize and improve some results that have been known.展开更多
The stress intensity factor(SIF) is a critical parameter associated with the fracture behaviour of materials. In this paper, we select the displacement function around a crack tip as the shape function of the digital ...The stress intensity factor(SIF) is a critical parameter associated with the fracture behaviour of materials. In this paper, we select the displacement function around a crack tip as the shape function of the digital image correlation(DIC), which makes it possible to directly calculate the SIF by the correlation scheme. Moreover, we use a non-rectangular subset, which can reduce the influence of plastic deformation and crack width on the DIC measurement accuracy. We measured the SIF of a mode I crack in a super-hard aluminium alloy specimen to verify the performance of the proposed method. Our experimental results show that a DIC with a specific shape function can be used to accurately and efficiently calculate the SIF.Furthermore, we also present a practical application of our proposed method for determining the SIF, crack propagation angle and crack tip displacement.展开更多
The increasing prevalence of diabetes has become a global public health concern in the 21st century.In 2021,it was estimated that 537 million people had diabetes,and this number is projected to reach 643 million by 20...The increasing prevalence of diabetes has become a global public health concern in the 21st century.In 2021,it was estimated that 537 million people had diabetes,and this number is projected to reach 643 million by 2030,and 783 million by 2045[1].Such a huge burden of diabetes brings great challenges in its prevention and management,including early diagnosis,timely interventions,and regular monitoring of risk factor control and complications screening.Continuous self-care support and patient empowerment can enhance clinical and psychobehavioural outcomes[2],although these require additional resources including manpower,infrastructure(hard and technology),and finances.The emergence of digital health technologies(DHTs),especially artificial intelligence(AI),may help address these obstacles and alleviate the burden of diabetes[3].Large language models(LLMs),a generative AI that can accept image and text inputs and produce text outputs,have shown promise in various aspects of medical care.展开更多
The accumulation of multiple surface holes is considered to be the key to efficient photoelectrochemical(PEC)water oxidation.Previous PEC water oxidation studies commonly apply high potentials(>1.2 VRHE)to achieve ...The accumulation of multiple surface holes is considered to be the key to efficient photoelectrochemical(PEC)water oxidation.Previous PEC water oxidation studies commonly apply high potentials(>1.2 VRHE)to achieve this key.But how to complete multi-hole transfer under low bias(<1.2 VRHE)remains unknown.Herein,we find that,on a typical visible-light photoanode,hematite(α-Fe_(2)O_(3)),UV excitation plays a indispensable role in driving multi-hole water oxidation under low bias.Compared with the visible-light excitation,the UV excitation promotes the formation of adjacent surface-trapped holes onα-Fe_(2)O_(3) at 0.9VRHE,thereby increasing the reaction order of surface holes from~1 to~2 and improving the PEC water oxidation activity by one order of magnitude.The UV irradiation reduces the formation probability of self-trapped excitons and results in~3 to 5-fold increase of surface holes.These advantages enable the UV excitation to contribute about 40%to the total photocurrent under 1 solar illumination,even though its energy only occupies 6%of the incident light.This mechanism is also applicable to boost selective two-hole oxidation of thioether at 0.1 VFc/Fc+and nitrite at 0.9 VRHE.展开更多
Identifying the active catalytic centers on catalyst surface is significant for exploring the catalytic reaction mechanism and further guiding the synthesis of high-performance catalysts.However,it remains a challange...Identifying the active catalytic centers on catalyst surface is significant for exploring the catalytic reaction mechanism and further guiding the synthesis of high-performance catalysts.However,it remains a challange in developing the site-specific technology for the identification of the active catalytic centers.Herein,in-situ infrared spectroscopy of adsorbed CO,photocatalytic hydrogen evolution reaction(HER)test and theoretical simulation were used to distinguish and quantify the different surface sites and their H2-production catalytic activity on TiO2-supported Pt nanoparticles(Pt NPs).Two different types of surface Pt sites,tip Pt(Pttip)and edge/terrace Ptedge/terrace,on TiO2-supported Pt nanoparticles(Pt NPs)were identified.The photocatalytic H2-production activity of TiO2-supported Pt NPs shows a linear functional relationship with the number of Pttip sites.However,the number of Ptedge/terracesites produced little effect on the activity of TiO2-supported Pt NPs.First-principle simulations confirmed that H2-evolution at the Pttipsites owns a lower energy barrier than that at Ptedge/terrace.This findings would be helpful for the fabrication of high-performance Pt catalysts.展开更多
基金supported by the National Natural Science Foundation of China(21525729,21590811,21521062,2177168)the "Strategic Priority Research Program" of the Chinese Academy of Sciences(XDA09030200)the "CAS Interdisciplinary Innovation Team Program"~~
文摘By using the fixed point theorem under the case structure, we study the existence of sign-changing solutions of A class of second-order differential equations three-point boundary-value problems, and a positive solution and a negative solution are obtained respectively, so as to popularize and improve some results that have been known.
基金supported by the National Natural Science Foundation of China (No. 11502166 and No. 11372222)
文摘The stress intensity factor(SIF) is a critical parameter associated with the fracture behaviour of materials. In this paper, we select the displacement function around a crack tip as the shape function of the digital image correlation(DIC), which makes it possible to directly calculate the SIF by the correlation scheme. Moreover, we use a non-rectangular subset, which can reduce the influence of plastic deformation and crack width on the DIC measurement accuracy. We measured the SIF of a mode I crack in a super-hard aluminium alloy specimen to verify the performance of the proposed method. Our experimental results show that a DIC with a specific shape function can be used to accurately and efficiently calculate the SIF.Furthermore, we also present a practical application of our proposed method for determining the SIF, crack propagation angle and crack tip displacement.
基金supported by the National Key R&D Program of China(2022YFC2502800 and 2022YFC2407000)the National Natural Science Foundation of China(8238810007,82022012,81870598 and 62272298)+3 种基金the Shanghai Municipal Key Clinical SpecialtyShanghai Research Center for Endocrine and Metabolic Diseases(2022ZZ01002)the Chinese Academy of Engineering(2022-XY-08)the Innovative Research Team of High-level Local Universities in Shanghai(SHSMU-ZDCX20212700)。
文摘The increasing prevalence of diabetes has become a global public health concern in the 21st century.In 2021,it was estimated that 537 million people had diabetes,and this number is projected to reach 643 million by 2030,and 783 million by 2045[1].Such a huge burden of diabetes brings great challenges in its prevention and management,including early diagnosis,timely interventions,and regular monitoring of risk factor control and complications screening.Continuous self-care support and patient empowerment can enhance clinical and psychobehavioural outcomes[2],although these require additional resources including manpower,infrastructure(hard and technology),and finances.The emergence of digital health technologies(DHTs),especially artificial intelligence(AI),may help address these obstacles and alleviate the burden of diabetes[3].Large language models(LLMs),a generative AI that can accept image and text inputs and produce text outputs,have shown promise in various aspects of medical care.
基金supported by the National Natural Science Foundation of China(22072158)the National Key R&D Program of China(2022YFA1505000,2020YFC1808401)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)CAS Project for Young Scientists in Basic Research(YSBR-004).
文摘The accumulation of multiple surface holes is considered to be the key to efficient photoelectrochemical(PEC)water oxidation.Previous PEC water oxidation studies commonly apply high potentials(>1.2 VRHE)to achieve this key.But how to complete multi-hole transfer under low bias(<1.2 VRHE)remains unknown.Herein,we find that,on a typical visible-light photoanode,hematite(α-Fe_(2)O_(3)),UV excitation plays a indispensable role in driving multi-hole water oxidation under low bias.Compared with the visible-light excitation,the UV excitation promotes the formation of adjacent surface-trapped holes onα-Fe_(2)O_(3) at 0.9VRHE,thereby increasing the reaction order of surface holes from~1 to~2 and improving the PEC water oxidation activity by one order of magnitude.The UV irradiation reduces the formation probability of self-trapped excitons and results in~3 to 5-fold increase of surface holes.These advantages enable the UV excitation to contribute about 40%to the total photocurrent under 1 solar illumination,even though its energy only occupies 6%of the incident light.This mechanism is also applicable to boost selective two-hole oxidation of thioether at 0.1 VFc/Fc+and nitrite at 0.9 VRHE.
基金supported by the National Natural Science Foundation of China(21525729,21590811,21521062,21777168)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDY-SSW-SLH028)the CAS Interdisciplinary Innovation Team Program.
文摘Identifying the active catalytic centers on catalyst surface is significant for exploring the catalytic reaction mechanism and further guiding the synthesis of high-performance catalysts.However,it remains a challange in developing the site-specific technology for the identification of the active catalytic centers.Herein,in-situ infrared spectroscopy of adsorbed CO,photocatalytic hydrogen evolution reaction(HER)test and theoretical simulation were used to distinguish and quantify the different surface sites and their H2-production catalytic activity on TiO2-supported Pt nanoparticles(Pt NPs).Two different types of surface Pt sites,tip Pt(Pttip)and edge/terrace Ptedge/terrace,on TiO2-supported Pt nanoparticles(Pt NPs)were identified.The photocatalytic H2-production activity of TiO2-supported Pt NPs shows a linear functional relationship with the number of Pttip sites.However,the number of Ptedge/terracesites produced little effect on the activity of TiO2-supported Pt NPs.First-principle simulations confirmed that H2-evolution at the Pttipsites owns a lower energy barrier than that at Ptedge/terrace.This findings would be helpful for the fabrication of high-performance Pt catalysts.
