Pyridinic N is widely regarded as the active center while pyrrolic N has low‐activity in metal‐free N‐doped carbon for electrocatalytic CO_(2) reduction reaction(CO_(2)RR)to CO,but this viewpoint remains open to qu...Pyridinic N is widely regarded as the active center while pyrrolic N has low‐activity in metal‐free N‐doped carbon for electrocatalytic CO_(2) reduction reaction(CO_(2)RR)to CO,but this viewpoint remains open to question.In this study,through density functional theoretical calculations,we first illustrate that the intrinsic activity of pyrrolic N is high enough for effectively catalyzing CO_(2)RR,however,due to the interplay with the neighboring pyridinic N sites,the activity of pyrrolic N is dramatically suppressed.Then,experimentally,metal‐free N‐doped carbon spheres(NCS)electrocatalysts without significant pyridinic N content are prepared for CO_(2)RR.The pyrrolic N in NCS shows a direct‐positive correlation with the performance for CO_(2)RR,representing the active center with high activity.The optimum NCS could produce syngas with a wide range of CO/H_(2) ratio(0.09 to 12)in CO_(2)RR depending on the applied potential,meanwhile,the best selectivity of 71%for CO can be obtained.Intentionally adding a small amount of pyridinic N to the optimum NCS dramatically decreases the activity for CO_(2)RR,further verifying the suppressed activity of pyrrolic N sites by the neighboring pyridinic N sites.This work reveals the interaction between a variety of N species in N‐doped carbon,and the potential of pyrrolic N as the new type of active site for electrocatalysts,which can improve our understanding of the electrocatalysis mechanism and be helpful for the rational design of high‐efficient electrocatalysts.展开更多
Regulating the surface instability of thin film/substrate structures has been successfully applied to prepare new ductile electronic devices.However,such electronic devices need to be subjected to external loads durin...Regulating the surface instability of thin film/substrate structures has been successfully applied to prepare new ductile electronic devices.However,such electronic devices need to be subjected to external loads during operation,which can easily induce delamination of the thin-film electronic device from the substrate.This study aims to investigate the instability characteristics of hard films on flexible substrate surfaces from theoretical analysis and numerical simulation perspectives.Considering finite-thickness substrates,this paper establishes theoretical models for pure bending,bent wrinkle,partial delamination,and total delamination buckling of film/substrate structures based on the nonlinear Euler–Bernoulli beam theory and the principle of minimum energy;then the effects of material and geometric parameters of the structure,interfacial adhesion strength,and pre-strain on the evolutionary path of the four patterns are discussed.The study results show that:the greater Young’s modulus of the substrate is,the larger the parameter region where partial delamination of the film/substrate structure occurs,and the smaller the parameter region where bent wrinkle occurs.By varying Young’s modulus,thickness of the film and substrate,interfacial adhesion coefficient,and pre-strain,the buckling pattern of the structure can be predicted and regulated.The parametric design intervals for each pattern are summarized in the phase diagram.The results of this paper provide theoretical support for the design and reliability evaluation of flexible electronic devices.展开更多
High-precision time interval measurement is a fundamental technique in many advanced applications,including time and distance metrology,particle physics,and ultra-precision machining.However,many of these applications...High-precision time interval measurement is a fundamental technique in many advanced applications,including time and distance metrology,particle physics,and ultra-precision machining.However,many of these applications are confined by the imprecise time interval measurement of electrical signals,restricting the performance of the ultimate system to a few picoseconds,which limits ultrahigh precision applications.Here,we demonstrate an optical means for the time interval measurement of electrical signals that can successfully achieve femtosecond(fs)level precision.The setup is established using the optical frequency comb(OFC)based linear optical sampling(LOS)technique to realize timescale-stretched measurement.We achieve a measurement precision of 82 fs for a single LOS scan measurement and 3.05 fs for the 100-times average with post-processing,which is three orders of magnitude higher than the results of older electrical methods.The high-precision time interval measurement of electrical signals can substantially improve precision measurement technologies.展开更多
Activation of inflammatory responses regulates the transmission of pain pathways through an integrated network in the peripheral and central nervous systems.The immunopotentiator thymosin alpha-1(Tal)has recently been...Activation of inflammatory responses regulates the transmission of pain pathways through an integrated network in the peripheral and central nervous systems.The immunopotentiator thymosin alpha-1(Tal)has recently been reported to have anti-inflammatory and neuroprotective functions in rodents.However,how Tα1 affects inflammatory pain remains unclear.In the present study,intraperitoneal injection of Tal attenuated complete Freund's adjuvant(CFA)-induced pain hypersensitivity,and decreased the up-regulation of pro-inflammatory cytokines(TNF-α,IL-1β,and IL-6)in inflamed skin and the spinal cord.We found that CFA-induced peripheral inflammation evoked strong microglial activation,but the effect was reversed by Tα1.Notably,Tα1 reversed the CFA-induced up-regulation of vesicular glutamate transporter(VGLUT)and down-regulated the vesicular γ-aminobutyric acid transporter(VGAT)in the spinal cord.Taken together,these results suggest that Tα1 plays a therapeutic role in inflammatory pain and in the modulation of microgliainduced pro-inflammatory cytokine production in addition to mediation of VGLUT and VGAT expression in the spinal cord.展开更多
In early life, the immune system plays an essential role in brain development. In our study, the immunopotentiator thymosin alpha-1（Ta1） was peripherally administered to neonatal mice to explore whether the peripher...In early life, the immune system plays an essential role in brain development. In our study, the immunopotentiator thymosin alpha-1（Ta1） was peripherally administered to neonatal mice to explore whether the peripheral immunopotentiator affects neurodevelopment and cognition, and to further investigate the relevant mechanism. Compared with the control group, the Ta1 mice displayed better cognitive abilities in early life. The numbers of 5-bromodeoxyuridine（Brd U）＋, nestin＋,T-box transcription factor 2（Tbr2）＋, Brd U＋/doublecortin（DCX）＋, Brd U＋/ionized calcium-binding adaptor molecule 1（Iba1）＋, and Brd U＋/neuronal nuclei（Neu N）＋ cells in the hippocampus were increased in the Ta1 group,accompanied by increased interleukin-4（IL-4）, interferon-gamma, brain-derived neurotrophic factor, nerve growth factor, and insulin-like growth factor-1 as well as decreased IL-6 and tumor necrosis factor-a. Furthermore, the Ta1-group showed a Th1-polarized immune response, and the neurotrophic factors were positively associated with the Th1/Th2 ratio. More importantly, administration of Ta1 blocked lipopolysaccharide-induced impairment of hippocampal neurogenesis in early life. These findings suggest that peripheral Ta1 contributes to neurogenesis and cognition probably through a systemic Th1 bias, as well as neuroprotection against LPS infection by Ta1.展开更多
LiFePO_(4)/C cathode materials were synthesized by a combination of co-precipitation and microwave heat-ing using polyethylene glycol(PEG)as a carbon resource and the influence of microwave heating time on the struc-t...LiFePO_(4)/C cathode materials were synthesized by a combination of co-precipitation and microwave heat-ing using polyethylene glycol(PEG)as a carbon resource and the influence of microwave heating time on the struc-ture and electrochemical performance of the materials was also discussed.The samples were characterized by X-ray diffraction(XRD),TEM,particle-size analysis and con-stant current charge-discharge experiment.The results show that the LiFePO_(4)/C heated for 9 min has a pure olive-type phase and excellent electrochemical perform-ance.The initial discharge capacities of this sample are 154.3,139.7,123.9 mAh/g at the rates 0.1C,0.2C,1C at room temperature,respectively,and after 20 cycles remain 152.3,134.3,118.5 mAh/g,respectively.展开更多
文摘Pyridinic N is widely regarded as the active center while pyrrolic N has low‐activity in metal‐free N‐doped carbon for electrocatalytic CO_(2) reduction reaction(CO_(2)RR)to CO,but this viewpoint remains open to question.In this study,through density functional theoretical calculations,we first illustrate that the intrinsic activity of pyrrolic N is high enough for effectively catalyzing CO_(2)RR,however,due to the interplay with the neighboring pyridinic N sites,the activity of pyrrolic N is dramatically suppressed.Then,experimentally,metal‐free N‐doped carbon spheres(NCS)electrocatalysts without significant pyridinic N content are prepared for CO_(2)RR.The pyrrolic N in NCS shows a direct‐positive correlation with the performance for CO_(2)RR,representing the active center with high activity.The optimum NCS could produce syngas with a wide range of CO/H_(2) ratio(0.09 to 12)in CO_(2)RR depending on the applied potential,meanwhile,the best selectivity of 71%for CO can be obtained.Intentionally adding a small amount of pyridinic N to the optimum NCS dramatically decreases the activity for CO_(2)RR,further verifying the suppressed activity of pyrrolic N sites by the neighboring pyridinic N sites.This work reveals the interaction between a variety of N species in N‐doped carbon,and the potential of pyrrolic N as the new type of active site for electrocatalysts,which can improve our understanding of the electrocatalysis mechanism and be helpful for the rational design of high‐efficient electrocatalysts.
基金funded by the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University(Grant No.2021201712).
文摘Regulating the surface instability of thin film/substrate structures has been successfully applied to prepare new ductile electronic devices.However,such electronic devices need to be subjected to external loads during operation,which can easily induce delamination of the thin-film electronic device from the substrate.This study aims to investigate the instability characteristics of hard films on flexible substrate surfaces from theoretical analysis and numerical simulation perspectives.Considering finite-thickness substrates,this paper establishes theoretical models for pure bending,bent wrinkle,partial delamination,and total delamination buckling of film/substrate structures based on the nonlinear Euler–Bernoulli beam theory and the principle of minimum energy;then the effects of material and geometric parameters of the structure,interfacial adhesion strength,and pre-strain on the evolutionary path of the four patterns are discussed.The study results show that:the greater Young’s modulus of the substrate is,the larger the parameter region where partial delamination of the film/substrate structure occurs,and the smaller the parameter region where bent wrinkle occurs.By varying Young’s modulus,thickness of the film and substrate,interfacial adhesion coefficient,and pre-strain,the buckling pattern of the structure can be predicted and regulated.The parametric design intervals for each pattern are summarized in the phase diagram.The results of this paper provide theoretical support for the design and reliability evaluation of flexible electronic devices.
基金China Postdoctoral Science Foundation(2020TQ0016)National Natural Science Foundation of China(61531003,62201012)。
文摘High-precision time interval measurement is a fundamental technique in many advanced applications,including time and distance metrology,particle physics,and ultra-precision machining.However,many of these applications are confined by the imprecise time interval measurement of electrical signals,restricting the performance of the ultimate system to a few picoseconds,which limits ultrahigh precision applications.Here,we demonstrate an optical means for the time interval measurement of electrical signals that can successfully achieve femtosecond(fs)level precision.The setup is established using the optical frequency comb(OFC)based linear optical sampling(LOS)technique to realize timescale-stretched measurement.We achieve a measurement precision of 82 fs for a single LOS scan measurement and 3.05 fs for the 100-times average with post-processing,which is three orders of magnitude higher than the results of older electrical methods.The high-precision time interval measurement of electrical signals can substantially improve precision measurement technologies.
基金supported by the Foundation for Distinguished Young Talents in Higher Education of Guangdong Province, China (2016KQNCX019 and 2016KQNCX027)the National Natural Science Foundation of China (31571041)+1 种基金the Guangdong Provincial Department of Education Innovating Strong National Engineering Major Project (2014GKXM031)Guangdong Provincial Universities and Colleges Pearl River Scholar Funded Scheme (2016)
文摘Activation of inflammatory responses regulates the transmission of pain pathways through an integrated network in the peripheral and central nervous systems.The immunopotentiator thymosin alpha-1(Tal)has recently been reported to have anti-inflammatory and neuroprotective functions in rodents.However,how Tα1 affects inflammatory pain remains unclear.In the present study,intraperitoneal injection of Tal attenuated complete Freund's adjuvant(CFA)-induced pain hypersensitivity,and decreased the up-regulation of pro-inflammatory cytokines(TNF-α,IL-1β,and IL-6)in inflamed skin and the spinal cord.We found that CFA-induced peripheral inflammation evoked strong microglial activation,but the effect was reversed by Tα1.Notably,Tα1 reversed the CFA-induced up-regulation of vesicular glutamate transporter(VGLUT)and down-regulated the vesicular γ-aminobutyric acid transporter(VGAT)in the spinal cord.Taken together,these results suggest that Tα1 plays a therapeutic role in inflammatory pain and in the modulation of microgliainduced pro-inflammatory cytokine production in addition to mediation of VGLUT and VGAT expression in the spinal cord.
基金supported by the Natural Science Foundation of Guangdong Province, China (2014A030310343, 2015A030313153, and 2016A030313253)the Medical Scientific Research Foundation of Guangdong Province, China (A2015382)the Doctoral Program of Guangzhou Medical University, China (2014C19)
文摘In early life, the immune system plays an essential role in brain development. In our study, the immunopotentiator thymosin alpha-1（Ta1） was peripherally administered to neonatal mice to explore whether the peripheral immunopotentiator affects neurodevelopment and cognition, and to further investigate the relevant mechanism. Compared with the control group, the Ta1 mice displayed better cognitive abilities in early life. The numbers of 5-bromodeoxyuridine（Brd U）＋, nestin＋,T-box transcription factor 2（Tbr2）＋, Brd U＋/doublecortin（DCX）＋, Brd U＋/ionized calcium-binding adaptor molecule 1（Iba1）＋, and Brd U＋/neuronal nuclei（Neu N）＋ cells in the hippocampus were increased in the Ta1 group,accompanied by increased interleukin-4（IL-4）, interferon-gamma, brain-derived neurotrophic factor, nerve growth factor, and insulin-like growth factor-1 as well as decreased IL-6 and tumor necrosis factor-a. Furthermore, the Ta1-group showed a Th1-polarized immune response, and the neurotrophic factors were positively associated with the Th1/Th2 ratio. More importantly, administration of Ta1 blocked lipopolysaccharide-induced impairment of hippocampal neurogenesis in early life. These findings suggest that peripheral Ta1 contributes to neurogenesis and cognition probably through a systemic Th1 bias, as well as neuroprotection against LPS infection by Ta1.
基金supported by Shanghai Leading Academic Discipline Project(No.B502).
文摘LiFePO_(4)/C cathode materials were synthesized by a combination of co-precipitation and microwave heat-ing using polyethylene glycol(PEG)as a carbon resource and the influence of microwave heating time on the struc-ture and electrochemical performance of the materials was also discussed.The samples were characterized by X-ray diffraction(XRD),TEM,particle-size analysis and con-stant current charge-discharge experiment.The results show that the LiFePO_(4)/C heated for 9 min has a pure olive-type phase and excellent electrochemical perform-ance.The initial discharge capacities of this sample are 154.3,139.7,123.9 mAh/g at the rates 0.1C,0.2C,1C at room temperature,respectively,and after 20 cycles remain 152.3,134.3,118.5 mAh/g,respectively.
