Objective weather classification methods have been extensively applied to identify dominant ozone-favorable synoptic weather patterns(SWPs),however,the consistency of different classification methods is rarely examine...Objective weather classification methods have been extensively applied to identify dominant ozone-favorable synoptic weather patterns(SWPs),however,the consistency of different classification methods is rarely examined.In this study,we apply two widely-used objective methods,the self-organizing map(SOM)and K-means clustering analysis,to derive ozone-favorable SWPs at four Chinese megacities in 2015-2022.We find that the two algorithms are largely consistent in recognizing dominant ozone-favorable SWPs for four Chinese megacities.In the case of classifying six SWPs,the derived circulation fields are highly similar with a spatial correlation of 0.99 between the two methods,and the difference in themean frequency of each SWP is less than 7%.The six dominant ozone-favorable SWPs in Guangzhou are all characterized by anomaly higher radiation and temperature,lower cloud cover,relative humidity,and wind speed,and stronger subsidence compared to climatology mean.We find that during 2015-2022,the occurrence of ozone-favorable SWPs days increases significantly at a rate of 3.2 days/year,faster than the increases in the ozone exceedance days(3.0 days/year).The interannual variability between the occurrence of ozone-favorable SWPs and ozone exceedance days are generally consistent with a temporal correlation coefficient of 0.6.In particular,the significant increase in ozone-favorable SWPs in 2022,especially the Subtropical High type which typically occurs in September,is consistent with a long-lasting ozone pollution episode in Guangzhou during September 2022.Our results thus reveal that enhanced frequency of ozone-favorable SWPs plays an important role in the observed 2015-2022 ozone increase in Guangzhou.展开更多
In the mammalian central nervous system(CNS),astrocytes are the ubiquitous glial cells that have complex morphological and molecular characteristics.These fascinating cells play essential neurosupportive and homeostat...In the mammalian central nervous system(CNS),astrocytes are the ubiquitous glial cells that have complex morphological and molecular characteristics.These fascinating cells play essential neurosupportive and homeostatic roles in the healthy CNS and undergo morphological,molecular,and functional changes to adopt so-called‘reactive’states in response to CNS injury or disease.In recent years,interest in astrocyte research has increased dramatically and some new biological features and roles of astrocytes in physiological and pathological conditions have been discovered thanks to technological advances.Here,we will review and discuss the wellestablished and emerging astroglial biology and functions,with emphasis on their potential as therapeutic targets for CNS injury,including traumatic and ischemic injury.This review article will highlight the importance of astrocytes in the neuropathological process and repair of CNS injury.展开更多
Catalysts with asymmetric coordination exhibit excellent electrocatalytic activity due to changes in the active sites,which affect the arrangement of reactants and catalytic activity/selectivity.Hence,the exploration ...Catalysts with asymmetric coordination exhibit excellent electrocatalytic activity due to changes in the active sites,which affect the arrangement of reactants and catalytic activity/selectivity.Hence,the exploration of the inherent characteristics of active sites within diverse coordination environments holds great significance for the experimental design of catalytic structures.Single-atom catalysts(SACs)characterized by high coordination with four carbons(26 candidates)and low coordination with dinitrogen(27candidates)are constructed using nitrogen-doped graphdiyne derivatives(NGDY)as the substrate.Additionally,5 species of dual-atom catalysts(DACs)with coexistence of both high and low coordination sites are also developed and their nitrogen reduction reaction(NRR)activities are systematically investigated by density functional theory.The results indicate that metals with low coordination exhibit superior catalytic performance,such as Mo^(L)-NGDY(U_(L)=-0.30 V)and Nb^(L)-NGDY(U_(L)=-0.32 V).Furthermore,machine learning(ML)methods have deeply analyzed and elucidated the primary intrinsic characteristics that influence catalytic performance.These results not only unveil the underlying mechanisms behind the exceptional catalytic performance exhibited by low-coordination metal atoms,but also provide relevant and significant descriptors.More importantly,based on an investigation of the catalytic activity of a series of DACs,the“buffer and low-coordination accumulate”asymmetric coordination mechanism is proposed to unveil the long-range interactions between low and high coordination atoms.Due to this remote communication,MoNb-NGDY(U_(L)=-0.09/-0.37 V)exhibits the best NRR activity.This mechanism provides valuable insights into the origin of long-range bipartite interactions and inspires the design and synthesis of NRR catalysts with different coordination environments.展开更多
Pt(Ⅱ)-salophen complexes(S-1~S-4) and 9,10-diphenylanthracene(DPA) tethering pillar[5]arene derivatives(A-1 and A-2) were synthesized to act as sensitizers and annihilators for triplet-triplet annihilation upconversi...Pt(Ⅱ)-salophen complexes(S-1~S-4) and 9,10-diphenylanthracene(DPA) tethering pillar[5]arene derivatives(A-1 and A-2) were synthesized to act as sensitizers and annihilators for triplet-triplet annihilation upconversion(TTA-UC), respectively. It turned out that the pyridine cation served as a mask for the excited state of the sensitizer, the triplet states of S-2 and S-3 were significantly quenched by photo-induced electron transfer(PET) with phosphorescence quantum yield quenched from 24.4% for S-4 to 9.3% for S-3,and therefore, both S-2 and S-3 led to negligible UC emissions when traditional annihilator DPA was used as the annihilator. Delightfully, when supramolecular annihilator A-1 and A-2 were employed to include the pyridine cation, PET was significantly inhibited and the triplet states of the sensitizers were activated,TTA-UC emission was therefore boosted. The UC quantum yield of A-2/S-3 system was up to 130 times higher than that of DPA/S-3 system, and the UC emission was switchable by the addition of competitive vips.展开更多
Reservoir-induced landslides in China's Three Gorges Reservoir area are prone to tensile cracks due to the influenceof their own weight and fluctuationsin water levels.The presence of cracks indicates that the ten...Reservoir-induced landslides in China's Three Gorges Reservoir area are prone to tensile cracks due to the influenceof their own weight and fluctuationsin water levels.The presence of cracks indicates that the tensile stress in the area has exceeded the tensile strength of the soil,leading to local instability.To explore the impact of tensile failure behavior on the stability and failure modes of reservoir landslides,the Huangtupo Riverside Slump#1 is taken as a case study.By considering local tensile failure,potential tensile cracks are incorporated into the analysis via the limit equilibrium method and reliability theory.The reliability of landslides under different tensile failure scenarios is quantified.Strain-softening characteristics of the soil are combined to further analyze the failure transmission path of the landslide.Finally,these potential failure modes were validated through physical model tests.The results show that cracks developing at rear positions reduce the stability of the slope and increase the probability of instability.During the destruction process,retrogressive failures with multiple sliding surfaces are likely to occur.However,tensile failure at the forefront reduces the likelihood of an individual slide mass descending.Progressive failure results in both regular and skip transmission patterns.Additionally,cracks and water level changes can also lead to shifts in the positions of the most dangerous blocks.Therefore,in practical landslide analysis and prevention,it is necessary to consider local tensile damage and identify potential tensile crack locations in advance to optimize prevention measures and accurately evaluate landslide risk.展开更多
Glial scarring following severe tissue damage and inflammation after spinal cord injury （SCI） is due to an extreme, uncontrolled form of reactive astrogliosis that typically occurs around the injury site. The scarri...Glial scarring following severe tissue damage and inflammation after spinal cord injury （SCI） is due to an extreme, uncontrolled form of reactive astrogliosis that typically occurs around the injury site. The scarring process includes the misalignment of activated astrocytes and the deposition of inhibitory chondroitin sulfate proteoglycans. Here, we first discuss recent developments in the molecular and cellular features of glial scar formation, with special focus on the potential cellular origin of scar-forming cells and the molecular mechanisms underlying glial scar formation after SCI. Second, we discuss the role of glial scar formation in the regulation of axonal regeneration and the cascades of neuro-inflammation. Last, we summarize the physical and pharmacological approaches targeting the modulation of glial scarring to better understand the role of glial scar formation in the repair of SCI.展开更多
Olfactory ensheathing cells （OECs） are a unique type of glial cells that have axonal growth-promoting properties. OEC transplantation has emerged as a promising experimental therapy of axonal injuries and demyelinat...Olfactory ensheathing cells （OECs） are a unique type of glial cells that have axonal growth-promoting properties. OEC transplantation has emerged as a promising experimental therapy of axonal injuries and demyelinating diseases. However, some fundamental cellular properties of OECs remain unclear. In this study, we found that the distinct OEC subpopulations exhibited different migratory properties based on time-lapse imaging of single isolated cells, possibly due to their different cytoskeletal organizations. Moreover, OEC subpopulations displayed different attractive migratory responses to a gradient of lysophosphatidic acid （LPA） in single-cell migration assays. Finally, we found that OEC subpopulations transformed into each other spontaneously. Together, these results demonstrate, for the first time to our knowledge, that distinct OEC subpopulations display different migratory properties in vitro and provide new evidence to support the notion of OECs as a single cell type with malleable functional phenotypes.展开更多
This paper presents a novel sizing and optimization approach for the emerging serieshybrid unmanned convertiplane,which can be used to translate the top-level design requirements into the design parameters correspondi...This paper presents a novel sizing and optimization approach for the emerging serieshybrid unmanned convertiplane,which can be used to translate the top-level design requirements into the design parameters corresponding to the optimal power supply strategy and minimum total takeoff weight.The method comprehensively considers the design constraints in the rotor,fixedwing,and transition modes,and pays special attention to the characteristic response of Series Hybrid Electric System(S-HES)in complex application scenarios,especially the coupling of battery power,energy,and state-of-charge under high-power discharge conditions,the variation of fuel economy,and the adjustment of power supply strategy.With proposed method,it's possible to rapidly explore the design space in the initial design stage and find out the optimal design results with high confidence.A case study was proposed to verify the approach.The results reveal the particularity of convertiplane in terms of power requirements,and prove the necessity to consider detailed S-HES characteristic responses during parameter determination.The optimal design parameters were obtained through the hybrid control parameter optimization,which verified the effectiveness of proposed method.Possible errors and corresponding correction methods were also presented.展开更多
The correct differentiation of oligodendrocyte precursor cells(OPCs) is essential for the myelination and remyelination processes in the central nervous system.Determining the regulatory mechanism is fundamental to th...The correct differentiation of oligodendrocyte precursor cells(OPCs) is essential for the myelination and remyelination processes in the central nervous system.Determining the regulatory mechanism is fundamental to the treatment of demyelinating diseases. By analyzing the RNA sequencing data of different neural cells, we found that cyclin-dependent kinase 18(CDK18) is exclusively expressed in oligodendrocytes. In vivo studies showed that the expression level of CDK18 gradually increased along with myelin formation during development and in the remyelination phase in a lysophosphatidylcholine-induced demyelination model, and was distinctively highly expressed in oligodendrocytes. In vitro overexpression and interference experiments revealed that CDK18 directly promotes the differentiation of OPCs, without affecting their proliferation or apoptosis. Mechanistically, CDK18 activated the RAS/mitogen-activated protein kinase kinase1/extracellular signal-regulated kinase pathway, thus promoting OPC differentiation. The results of the present study suggest that CDK18 is a promising cell-type specific target to treat demyelinating disease.展开更多
Multiple sclerosis（MS） is a classical inflammatory demyelinating disease of the central nervous system（CNS）. Microglia are the main resident immune cells in the CNS and are closely associated with the pathogenesis...Multiple sclerosis（MS） is a classical inflammatory demyelinating disease of the central nervous system（CNS）. Microglia are the main resident immune cells in the CNS and are closely associated with the pathogenesis of MS.In the present study, we found that mi R-30 a was highly expressed in jellyfish-like microglia in chronic active lesions of MS patients, as well as in the microglia of mice with experimental autoimmune encephalomyelitis（EAE） at the chronic phase. In vitro, the conditioned supernatant of mouse microglia overexpressing miR-30 a promoted the apoptosis of oligodendrocyte precursor cells（OPCs）, and inhibited OPC differentiation. In vivo, overexpressing miR-30 a in transplanted microglia exacerbated the progression of EAE.Overexpression and knock-down experiments in primary cultured mouse microglia showed that mi R-30 a increased the expression of IL-1 b and i NOS, which are pro-inflammatory, while inhibiting the expression of Ym-1 and CD206.Mechanistically, mi R-30 a inhibited the expression of Ppargc1 b, which is the co-activator of peroxisome proliferator-activated receptor gamma, resulting in pro-inflammatory effects. Our work shows that mi R-30 a is an important regulator of the inflammatory response in microglia, and may be a promising therapeutic target for inflammatory diseases like MS in the CNS.展开更多
The design and synthesis of a phenoxazine-based metal-organic tetrahedro n(Zn4L4) as biomimetic lectin for selectively recognition of glucosamine(GlcN) was reported.Different from the free phenoxazinebased ligand(L),Z...The design and synthesis of a phenoxazine-based metal-organic tetrahedro n(Zn4L4) as biomimetic lectin for selectively recognition of glucosamine(GlcN) was reported.Different from the free phenoxazinebased ligand(L),Zn4L4 displayed the highest fluorescent intensity enhancement efficiency toward GlcN over other related natural mono-and disaccharides.Fluorescence titration demonstrated a 1:1 stoichiometric host-vip complex was formed with an association constant about 4.03 × 104 L/mol.1H NMR spectroscopic studies confirmed this selectivity resulted from the multiple hydrogen bonding interactions formed between GlcN and Zn4L4.The present results suggested that rational arrangement of recognition sites in the confined space of metal-organic cage is crucial for the selectivity toward target vips.展开更多
The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and...The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.展开更多
While prokaryotes play key roles in nutrient cycling and energy flow during Phaeocystis globosa blooms,the information on the spatial and diel temporal distribution of the prokaryotic community during Phaeocystis bloo...While prokaryotes play key roles in nutrient cycling and energy flow during Phaeocystis globosa blooms,the information on the spatial and diel temporal distribution of the prokaryotic community during Phaeocystis blooms remains scarce.In January 2019,we used high-throughput sequencing of the 16S rRNA gene to explore the spatial and diel variations of particle-attached(PA)and free-living(FL)prokaryotic communities during the blooming phase of P.globosa in Beibu Gulf,Guangxi,China.The results suggested a significant spatial variation pattern in the horizontal distribution of prokaryotic communities,while there was no significant difference in the vertical direction.Both spatial distance and environmental variables shaped the horizontal distribution of the prokaryotic community structure,while environmental variables,particularly the abundance of P.globosa colony and Chl a,showed more significant influence and were closely related to the structure and variation of the prokaryotic community.Strong vertical mixing of the water column disrupted the vertical structure heterogeneity of the prokaryotic community in winter.There were significant differences in the diel samples of PA prokaryotic communities,but not in the FL prokaryotic communities.Nitrate,ammonium and the abundance of P.globosa colony were the key environmental variables impacting the diel variations of prokaryotic communities over the sampling period.The present study provided valuable information to depict the spatial-temporal variations of the microbial community and its association with environmental parameters during P.globosa bloom in the tropical gulf.展开更多
To solve the problem of energy scarcity and widespread environmental contamination,it is necessary to design green and low-cost photocatalysts for water splitting.In this paper,a new penta-graphene/AlAs_(5)(PG/AlAss)v...To solve the problem of energy scarcity and widespread environmental contamination,it is necessary to design green and low-cost photocatalysts for water splitting.In this paper,a new penta-graphene/AlAs_(5)(PG/AlAss)van der Waals(vdW)heterostructure is proposed and its performance for photocatalytic hydrolysis is calculated using the first-principles method.The findings suggest that the PG/AIAss heterostructure belong to type-ll indirect semiconductor,and the edge position and band gap width of this heterostructure satisfy the requests of redox reaction.Furthermore,the oxidation reaction(OER)on the AIAss side and the hydrogen evolution reaction(HER)on the PG side are thermodynamically spontaneous under different conditions.Surprisingly,the introduction of strain engineering has changed the position of the band edge and light absorption performance of PG/AlAss heterostructure,which is powerful for the performance of photocatalytic water splitting.The PG/AlAs_(5) vdw heterostructure exhibits well visible light absorption intensity without applying strain and biaxial strain of 2%.In conclusion,the findings suggest that the PG/AlAss vdW heterostructure is a prospecting catalyst for visible-light hydrolysis.展开更多
Designing and developing the highly efficient photocatalysts is full of significance to achieve spontaneous photolysis water.In this work,using the first-principles calculations,we have performed a systematic theoreti...Designing and developing the highly efficient photocatalysts is full of significance to achieve spontaneous photolysis water.In this work,using the first-principles calculations,we have performed a systematic theoretical study of water splitting photocatalytic activity of the InS e/g-CN heterojunction.It is concluded that the In Se/g-CN heterojunction is a typical type-II semiconductor,whose electrons and holes can be effectively separated.And the potential of the conduction band minimum(CBM)and valence band maximum(VBM)satisfy the requirements for photolysis water.Moreover,the changes of Gibbs free energy(ΔG)of the oxygen evolution reaction(OER)and the hydrogen evolution reaction(HER)are calculated to investigate thermodynamic sustainability of photolysis water.The results show that when pH=7,the potential driving force provided by the InSe/g-CN heterojunction can ensure the spontaneous progress of HER and OER.In addition,it is found that the solar conversion efficiency(η;)of the In Se/g-CN heterojunction is up to 13.7%,which indicates it has broad commercial application prospects.Hence,the In Se/g-CN heterojunction is expected to be an excellent candidate for photolysis water.展开更多
The minimax path location problem is to find a path P in a graph G such that the maximum distance d_(G)(v,P)from every vertex v∈V(G)to the path P is minimized.It is a well-known NP-hard problem in network optimizatio...The minimax path location problem is to find a path P in a graph G such that the maximum distance d_(G)(v,P)from every vertex v∈V(G)to the path P is minimized.It is a well-known NP-hard problem in network optimization.This paper studies the fixed-parameter solvability,that is,for a given graph G and an integer k,to decide whether there exists a path P in G such that max v∈V(G)d_(G)(v,P)≤k.If the answer is affirmative,then graph G is called k-path-eccentric.We show that this decision problem is NP-complete even for k=1.On the other hand,we characterize the family of 1-path-eccentric graphs,including the traceable,interval,split,permutation graphs and others.Furthermore,some polynomially solvable special graphs are discussed.展开更多
基金supported by the Guangdong Basic and Applied Basic Research project (No.2020B0301030004)the Key-Area Research and Development Program of Guangdong Province (No.2020B1111360003)+1 种基金the National Natural Science Foundation of China (No.42105103)the Guangdong Basic and Applied Basic Research Foundation (No.2022A1515011554).
文摘Objective weather classification methods have been extensively applied to identify dominant ozone-favorable synoptic weather patterns(SWPs),however,the consistency of different classification methods is rarely examined.In this study,we apply two widely-used objective methods,the self-organizing map(SOM)and K-means clustering analysis,to derive ozone-favorable SWPs at four Chinese megacities in 2015-2022.We find that the two algorithms are largely consistent in recognizing dominant ozone-favorable SWPs for four Chinese megacities.In the case of classifying six SWPs,the derived circulation fields are highly similar with a spatial correlation of 0.99 between the two methods,and the difference in themean frequency of each SWP is less than 7%.The six dominant ozone-favorable SWPs in Guangzhou are all characterized by anomaly higher radiation and temperature,lower cloud cover,relative humidity,and wind speed,and stronger subsidence compared to climatology mean.We find that during 2015-2022,the occurrence of ozone-favorable SWPs days increases significantly at a rate of 3.2 days/year,faster than the increases in the ozone exceedance days(3.0 days/year).The interannual variability between the occurrence of ozone-favorable SWPs and ozone exceedance days are generally consistent with a temporal correlation coefficient of 0.6.In particular,the significant increase in ozone-favorable SWPs in 2022,especially the Subtropical High type which typically occurs in September,is consistent with a long-lasting ozone pollution episode in Guangzhou during September 2022.Our results thus reveal that enhanced frequency of ozone-favorable SWPs plays an important role in the observed 2015-2022 ozone increase in Guangzhou.
基金supported by the National Natural Science Foundation of China(82171386,81971161,and 82201536)the Shanghai Science and Technology Development Foundation(22YF1458600)+1 种基金the Scientifc Foundation from Naval Medical University(2021QN08)the STI2030-Major Projects from Ministry of Science and Technology of China(2022ZD0204700).
文摘In the mammalian central nervous system(CNS),astrocytes are the ubiquitous glial cells that have complex morphological and molecular characteristics.These fascinating cells play essential neurosupportive and homeostatic roles in the healthy CNS and undergo morphological,molecular,and functional changes to adopt so-called‘reactive’states in response to CNS injury or disease.In recent years,interest in astrocyte research has increased dramatically and some new biological features and roles of astrocytes in physiological and pathological conditions have been discovered thanks to technological advances.Here,we will review and discuss the wellestablished and emerging astroglial biology and functions,with emphasis on their potential as therapeutic targets for CNS injury,including traumatic and ischemic injury.This review article will highlight the importance of astrocytes in the neuropathological process and repair of CNS injury.
基金supports by the National Natural Science Foundation of China(NSFC,Grant No.52271113)the Natural Science Foundation of Shaanxi Province,China(2020JM 218)the Fundamental Research Funds for the Central Universities(CHD300102311405)。
文摘Catalysts with asymmetric coordination exhibit excellent electrocatalytic activity due to changes in the active sites,which affect the arrangement of reactants and catalytic activity/selectivity.Hence,the exploration of the inherent characteristics of active sites within diverse coordination environments holds great significance for the experimental design of catalytic structures.Single-atom catalysts(SACs)characterized by high coordination with four carbons(26 candidates)and low coordination with dinitrogen(27candidates)are constructed using nitrogen-doped graphdiyne derivatives(NGDY)as the substrate.Additionally,5 species of dual-atom catalysts(DACs)with coexistence of both high and low coordination sites are also developed and their nitrogen reduction reaction(NRR)activities are systematically investigated by density functional theory.The results indicate that metals with low coordination exhibit superior catalytic performance,such as Mo^(L)-NGDY(U_(L)=-0.30 V)and Nb^(L)-NGDY(U_(L)=-0.32 V).Furthermore,machine learning(ML)methods have deeply analyzed and elucidated the primary intrinsic characteristics that influence catalytic performance.These results not only unveil the underlying mechanisms behind the exceptional catalytic performance exhibited by low-coordination metal atoms,but also provide relevant and significant descriptors.More importantly,based on an investigation of the catalytic activity of a series of DACs,the“buffer and low-coordination accumulate”asymmetric coordination mechanism is proposed to unveil the long-range interactions between low and high coordination atoms.Due to this remote communication,MoNb-NGDY(U_(L)=-0.09/-0.37 V)exhibits the best NRR activity.This mechanism provides valuable insights into the origin of long-range bipartite interactions and inspires the design and synthesis of NRR catalysts with different coordination environments.
基金supported by the National Natural Science Foundation of China (Nos. 22171194, 21971169, 92056116 and 21871194)the Fundamental Research Funds for the Central Universities (No. 20826041D4117)the Science & Technology Department of Sichuan Province (Nos. 2022YFH0095 and 2021ZYD0052)。
文摘Pt(Ⅱ)-salophen complexes(S-1~S-4) and 9,10-diphenylanthracene(DPA) tethering pillar[5]arene derivatives(A-1 and A-2) were synthesized to act as sensitizers and annihilators for triplet-triplet annihilation upconversion(TTA-UC), respectively. It turned out that the pyridine cation served as a mask for the excited state of the sensitizer, the triplet states of S-2 and S-3 were significantly quenched by photo-induced electron transfer(PET) with phosphorescence quantum yield quenched from 24.4% for S-4 to 9.3% for S-3,and therefore, both S-2 and S-3 led to negligible UC emissions when traditional annihilator DPA was used as the annihilator. Delightfully, when supramolecular annihilator A-1 and A-2 were employed to include the pyridine cation, PET was significantly inhibited and the triplet states of the sensitizers were activated,TTA-UC emission was therefore boosted. The UC quantum yield of A-2/S-3 system was up to 130 times higher than that of DPA/S-3 system, and the UC emission was switchable by the addition of competitive vips.
基金supported by the Major Program of National Natural Science Foundation of China(Grant No.42090055)the National Key ScientificInstruments and Equipment Development Projects of China(Grant No.41827808)the National Nature Science Foundation of China(Grant No.42207216).
文摘Reservoir-induced landslides in China's Three Gorges Reservoir area are prone to tensile cracks due to the influenceof their own weight and fluctuationsin water levels.The presence of cracks indicates that the tensile stress in the area has exceeded the tensile strength of the soil,leading to local instability.To explore the impact of tensile failure behavior on the stability and failure modes of reservoir landslides,the Huangtupo Riverside Slump#1 is taken as a case study.By considering local tensile failure,potential tensile cracks are incorporated into the analysis via the limit equilibrium method and reliability theory.The reliability of landslides under different tensile failure scenarios is quantified.Strain-softening characteristics of the soil are combined to further analyze the failure transmission path of the landslide.Finally,these potential failure modes were validated through physical model tests.The results show that cracks developing at rear positions reduce the stability of the slope and increase the probability of instability.During the destruction process,retrogressive failures with multiple sliding surfaces are likely to occur.However,tensile failure at the forefront reduces the likelihood of an individual slide mass descending.Progressive failure results in both regular and skip transmission patterns.Additionally,cracks and water level changes can also lead to shifts in the positions of the most dangerous blocks.Therefore,in practical landslide analysis and prevention,it is necessary to consider local tensile damage and identify potential tensile crack locations in advance to optimize prevention measures and accurately evaluate landslide risk.
基金supported by grants from the National Basic Research Development Program of China (2011CB504401)the National Natural Science Foundation of China (31130024,31070922 and 81261130313)
文摘Glial scarring following severe tissue damage and inflammation after spinal cord injury （SCI） is due to an extreme, uncontrolled form of reactive astrogliosis that typically occurs around the injury site. The scarring process includes the misalignment of activated astrocytes and the deposition of inhibitory chondroitin sulfate proteoglycans. Here, we first discuss recent developments in the molecular and cellular features of glial scar formation, with special focus on the potential cellular origin of scar-forming cells and the molecular mechanisms underlying glial scar formation after SCI. Second, we discuss the role of glial scar formation in the regulation of axonal regeneration and the cascades of neuro-inflammation. Last, we summarize the physical and pharmacological approaches targeting the modulation of glial scarring to better understand the role of glial scar formation in the repair of SCI.
基金We thank Drs Chenbing Guan and Kui Cui （Institute of Neuroscience, Shanghai Institute for Biological Science, China） for technical support in setting up the single-cell migration assay, and Dr Qian Hu （Institute of Neuroscience, Shanghai Institute for Biological Science, China） for microscopic imaging. This study was supported by the National Key Basic Research Program （2006CB500702）, Ministry of Science and Technology of China （2007CB947100）, National Natural Science Foundation of China （30530240 and 30770657）, Program for Changdiang Scholars and Innovative Research Teams in Universities （IRT0528）, and Shanghai Metropolitan Fund for Research and Development （07DJ14005）.
文摘Olfactory ensheathing cells （OECs） are a unique type of glial cells that have axonal growth-promoting properties. OEC transplantation has emerged as a promising experimental therapy of axonal injuries and demyelinating diseases. However, some fundamental cellular properties of OECs remain unclear. In this study, we found that the distinct OEC subpopulations exhibited different migratory properties based on time-lapse imaging of single isolated cells, possibly due to their different cytoskeletal organizations. Moreover, OEC subpopulations displayed different attractive migratory responses to a gradient of lysophosphatidic acid （LPA） in single-cell migration assays. Finally, we found that OEC subpopulations transformed into each other spontaneously. Together, these results demonstrate, for the first time to our knowledge, that distinct OEC subpopulations display different migratory properties in vitro and provide new evidence to support the notion of OECs as a single cell type with malleable functional phenotypes.
文摘This paper presents a novel sizing and optimization approach for the emerging serieshybrid unmanned convertiplane,which can be used to translate the top-level design requirements into the design parameters corresponding to the optimal power supply strategy and minimum total takeoff weight.The method comprehensively considers the design constraints in the rotor,fixedwing,and transition modes,and pays special attention to the characteristic response of Series Hybrid Electric System(S-HES)in complex application scenarios,especially the coupling of battery power,energy,and state-of-charge under high-power discharge conditions,the variation of fuel economy,and the adjustment of power supply strategy.With proposed method,it's possible to rapidly explore the design space in the initial design stage and find out the optimal design results with high confidence.A case study was proposed to verify the approach.The results reveal the particularity of convertiplane in terms of power requirements,and prove the necessity to consider detailed S-HES characteristic responses during parameter determination.The optimal design parameters were obtained through the hybrid control parameter optimization,which verified the effectiveness of proposed method.Possible errors and corresponding correction methods were also presented.
基金supported by the National Natural Science Foundation of China (31700924, 31571066, 31771129, and 31871026)the National Basic Research Development Program of China (2016YFA0100802)
文摘The correct differentiation of oligodendrocyte precursor cells(OPCs) is essential for the myelination and remyelination processes in the central nervous system.Determining the regulatory mechanism is fundamental to the treatment of demyelinating diseases. By analyzing the RNA sequencing data of different neural cells, we found that cyclin-dependent kinase 18(CDK18) is exclusively expressed in oligodendrocytes. In vivo studies showed that the expression level of CDK18 gradually increased along with myelin formation during development and in the remyelination phase in a lysophosphatidylcholine-induced demyelination model, and was distinctively highly expressed in oligodendrocytes. In vitro overexpression and interference experiments revealed that CDK18 directly promotes the differentiation of OPCs, without affecting their proliferation or apoptosis. Mechanistically, CDK18 activated the RAS/mitogen-activated protein kinase kinase1/extracellular signal-regulated kinase pathway, thus promoting OPC differentiation. The results of the present study suggest that CDK18 is a promising cell-type specific target to treat demyelinating disease.
基金supported by the International Cooperation and Exchange of the National Natural Science Foundation of China(81461138035)the National Natural Science Foundation of China(81371326,31371068,and 31571066)the National Key Research and Development Program of China(2016YFA0100802)
文摘Multiple sclerosis（MS） is a classical inflammatory demyelinating disease of the central nervous system（CNS）. Microglia are the main resident immune cells in the CNS and are closely associated with the pathogenesis of MS.In the present study, we found that mi R-30 a was highly expressed in jellyfish-like microglia in chronic active lesions of MS patients, as well as in the microglia of mice with experimental autoimmune encephalomyelitis（EAE） at the chronic phase. In vitro, the conditioned supernatant of mouse microglia overexpressing miR-30 a promoted the apoptosis of oligodendrocyte precursor cells（OPCs）, and inhibited OPC differentiation. In vivo, overexpressing miR-30 a in transplanted microglia exacerbated the progression of EAE.Overexpression and knock-down experiments in primary cultured mouse microglia showed that mi R-30 a increased the expression of IL-1 b and i NOS, which are pro-inflammatory, while inhibiting the expression of Ym-1 and CD206.Mechanistically, mi R-30 a inhibited the expression of Ppargc1 b, which is the co-activator of peroxisome proliferator-activated receptor gamma, resulting in pro-inflammatory effects. Our work shows that mi R-30 a is an important regulator of the inflammatory response in microglia, and may be a promising therapeutic target for inflammatory diseases like MS in the CNS.
基金the National Natural Science Foundation of China (Nos.21701019 and 21861132004)Doctoral Scientific Research Launching Fund Project of Liaoning province (No.2019BS-050)。
文摘The design and synthesis of a phenoxazine-based metal-organic tetrahedro n(Zn4L4) as biomimetic lectin for selectively recognition of glucosamine(GlcN) was reported.Different from the free phenoxazinebased ligand(L),Zn4L4 displayed the highest fluorescent intensity enhancement efficiency toward GlcN over other related natural mono-and disaccharides.Fluorescence titration demonstrated a 1:1 stoichiometric host-vip complex was formed with an association constant about 4.03 × 104 L/mol.1H NMR spectroscopic studies confirmed this selectivity resulted from the multiple hydrogen bonding interactions formed between GlcN and Zn4L4.The present results suggested that rational arrangement of recognition sites in the confined space of metal-organic cage is crucial for the selectivity toward target vips.
基金supports by the National Natural Science Foundation of China(NSFC,52271113)the Natural Science Foundation of Shaanxi Province,China(2020JM 218)+1 种基金the Fundamental Research Funds for the Central Universities(CHD300102311405)HPC platform,Xi’an Jiaotong University。
文摘The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.
基金The National Key Research and Development Program of the Ministry of Science and Technology,China,under contract No.2017YFC1404300the Scientific and Technological Innovation Project of the Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2016ASKJ02the Aoshan Talents Program of the Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2015ASTP.
文摘While prokaryotes play key roles in nutrient cycling and energy flow during Phaeocystis globosa blooms,the information on the spatial and diel temporal distribution of the prokaryotic community during Phaeocystis blooms remains scarce.In January 2019,we used high-throughput sequencing of the 16S rRNA gene to explore the spatial and diel variations of particle-attached(PA)and free-living(FL)prokaryotic communities during the blooming phase of P.globosa in Beibu Gulf,Guangxi,China.The results suggested a significant spatial variation pattern in the horizontal distribution of prokaryotic communities,while there was no significant difference in the vertical direction.Both spatial distance and environmental variables shaped the horizontal distribution of the prokaryotic community structure,while environmental variables,particularly the abundance of P.globosa colony and Chl a,showed more significant influence and were closely related to the structure and variation of the prokaryotic community.Strong vertical mixing of the water column disrupted the vertical structure heterogeneity of the prokaryotic community in winter.There were significant differences in the diel samples of PA prokaryotic communities,but not in the FL prokaryotic communities.Nitrate,ammonium and the abundance of P.globosa colony were the key environmental variables impacting the diel variations of prokaryotic communities over the sampling period.The present study provided valuable information to depict the spatial-temporal variations of the microbial community and its association with environmental parameters during P.globosa bloom in the tropical gulf.
基金supports by National Natural Science Foundation of China(NSFC,No.52271113)Natural Science Foundation of Shaanxi Province,China(Nos.2019JM-189,2020JM-218)the Fundamental Research Funds for the Central Universities(Nos.CHD300102311405,CHD300102312405),HPC platform,Xi'an Jiaotong University.
文摘To solve the problem of energy scarcity and widespread environmental contamination,it is necessary to design green and low-cost photocatalysts for water splitting.In this paper,a new penta-graphene/AlAs_(5)(PG/AlAss)van der Waals(vdW)heterostructure is proposed and its performance for photocatalytic hydrolysis is calculated using the first-principles method.The findings suggest that the PG/AIAss heterostructure belong to type-ll indirect semiconductor,and the edge position and band gap width of this heterostructure satisfy the requests of redox reaction.Furthermore,the oxidation reaction(OER)on the AIAss side and the hydrogen evolution reaction(HER)on the PG side are thermodynamically spontaneous under different conditions.Surprisingly,the introduction of strain engineering has changed the position of the band edge and light absorption performance of PG/AlAss heterostructure,which is powerful for the performance of photocatalytic water splitting.The PG/AlAs_(5) vdw heterostructure exhibits well visible light absorption intensity without applying strain and biaxial strain of 2%.In conclusion,the findings suggest that the PG/AlAss vdW heterostructure is a prospecting catalyst for visible-light hydrolysis.
基金supports by National Natural Science Foundation of China(NSFC,Nos.51471124,U1766216)National Key R&D Program of China(No.2018YFB0905600)+1 种基金Natural Science Foundation of Shaanxi province,China(Nos.2019JM-189,2020JM218)supported by HPC Platform,Xi’an Jiaotong University。
文摘Designing and developing the highly efficient photocatalysts is full of significance to achieve spontaneous photolysis water.In this work,using the first-principles calculations,we have performed a systematic theoretical study of water splitting photocatalytic activity of the InS e/g-CN heterojunction.It is concluded that the In Se/g-CN heterojunction is a typical type-II semiconductor,whose electrons and holes can be effectively separated.And the potential of the conduction band minimum(CBM)and valence band maximum(VBM)satisfy the requirements for photolysis water.Moreover,the changes of Gibbs free energy(ΔG)of the oxygen evolution reaction(OER)and the hydrogen evolution reaction(HER)are calculated to investigate thermodynamic sustainability of photolysis water.The results show that when pH=7,the potential driving force provided by the InSe/g-CN heterojunction can ensure the spontaneous progress of HER and OER.In addition,it is found that the solar conversion efficiency(η;)of the In Se/g-CN heterojunction is up to 13.7%,which indicates it has broad commercial application prospects.Hence,the In Se/g-CN heterojunction is expected to be an excellent candidate for photolysis water.
文摘The minimax path location problem is to find a path P in a graph G such that the maximum distance d_(G)(v,P)from every vertex v∈V(G)to the path P is minimized.It is a well-known NP-hard problem in network optimization.This paper studies the fixed-parameter solvability,that is,for a given graph G and an integer k,to decide whether there exists a path P in G such that max v∈V(G)d_(G)(v,P)≤k.If the answer is affirmative,then graph G is called k-path-eccentric.We show that this decision problem is NP-complete even for k=1.On the other hand,we characterize the family of 1-path-eccentric graphs,including the traceable,interval,split,permutation graphs and others.Furthermore,some polynomially solvable special graphs are discussed.
