Carbon peak and carbon neutrality(dual-carbon)are important targets for the international response to climate change.The Silk Road Economic Belt is a strategic resource region and is important for future ecological en...Carbon peak and carbon neutrality(dual-carbon)are important targets for the international response to climate change.The Silk Road Economic Belt is a strategic resource region and is important for future ecological environment and tourism development.Based on the“dual-carbon”targets,the Single index quantification,Multiple index synthesis,and Poly-criteria integration evaluation model were used in this study to measure the coordinated development index of the ecological environment,public service,and tourism economy along the Silk Road Economic Belt and to analyze its spatial and temporal evolution.Further,it explores the dynamic evolution and development trend of the three systems using the Kernel Density and Grey Markov Prediction Model.The results show that the coordinated development index along this region needs to be improved during the study period.Furthermore,the coordinated development index of the Southwest region is relatively higher than that of the Northwest region.From the development trend of the three systems,all of them develop in a stable manner;however,the tourism economy system is easily affected by external disturbances.The coordinated development index of the three systems changes dynamically and tends to be in a good state of coordination.There is a certain spatial and temporal heterogeneity.The gravity center of the coordinated development index has been in the Southwest region.During the forecast period,the coordinated development index along this region will improve significantly,while insufficient and unbalanced development will continue.展开更多
The Schrödinger equation for the 2S and 2P states of the lithium-like ions Z=5–7,9–10 is solved by using the Rayleigh-Ritz variational method in Hylleraas coordinates.The leading-order relativistic and QED corr...The Schrödinger equation for the 2S and 2P states of the lithium-like ions Z=5–7,9–10 is solved by using the Rayleigh-Ritz variational method in Hylleraas coordinates.The leading-order relativistic and QED corrections are calculated perturbatively and higher-order corrections are estimated.The transition frequencies between the 2S_(1/2)and 2P_(J)(J=1/2,3/2)states are determined and compared with experimental and other theoretical results.Specifically,isotope shifts are also calculated for B^(2+).展开更多
Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the e...Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.展开更多
High performance electro-optic modulator,as the key device of integrated ultra-wideband optical systems,have be-come the focus of research.Meanwhile,the organic-based hybrid electro-optic modulators,which make full us...High performance electro-optic modulator,as the key device of integrated ultra-wideband optical systems,have be-come the focus of research.Meanwhile,the organic-based hybrid electro-optic modulators,which make full use of the advant-ages of organic electro-optic(OEO)materials(e.g.high electro-optic coefficient,fast response speed,high bandwidth,easy pro-cessing/integration and low cost)have attracted considerable attention.In this paper,we introduce a series of high-perform-ance OEO materials that exhibit good properties in electro-optic activity and thermal stability.In addition,the recent progress of organic-based hybrid electro-optic devices is reviewed,including photonic crystal-organic hybrid(PCOH),silicon-organic hy-brid(SOH)and plasmonic-organic hybrid(POH)modulators.A high-performance integrated optical platform based on OEO ma-terials is a promising solution for growing high speeds and low power consumption in compact sizes.展开更多
With the rapid development of the Internet of things and e-commerce, feature-based image retrieval and classification have become a serious challenge for shoppers searching websites for relevant product information. T...With the rapid development of the Internet of things and e-commerce, feature-based image retrieval and classification have become a serious challenge for shoppers searching websites for relevant product information. The last decade has witnessed great interest in research on content-based feature extraction techniques. Moreover, semantic attributes cannot fully express the rich image information. This paper designs and trains a deep convolutional neural network that the convolution kernel size and the order of network connection are based on the high efficiency of the filter capacity and coverage. To solve the problem of long training time and high resource share of deep convolutional neural network, this paper designed a shallow convolutional neural network to achieve the similar classification accuracy. The deep and shallow convolutional neural networks have data pre-processing, feature extraction and softmax classification. To evaluate the classification performance of the network, experiments were conducted using a public database Caltech256 and a homemade product image database containing 15 species of garment and 5 species of shoes on a total of 20,000 color images from shopping websites. Compared with the classification accuracy of combining content-based feature extraction techniques with traditional support vector machine techniques from 76.3% to 86.2%, the deep convolutional neural network obtains an impressive state-of-the-art classification accuracy of 92.1%, and the shallow convolutional neural network reached a classification accuracy of 90.6%. Moreover, the proposed convolutional neural networks can be integrated and implemented in other colour image database.展开更多
Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This pap...Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.展开更多
Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low price.In this work,a series o...Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low price.In this work,a series of well-dispersed nitrogen-coordinated Ru-clusters on carbon black(Ru_(x)N_(y)/C)were prepared by pyrolyzing different Ru-containing sandwich compounds as the Ru sources.The higher thermal stability of these complexed sandwich precursors(bis(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)monomer,dichloro(p-cymene)Ru(II)dimer,and chloro(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)tetramer)affords the control of coordinated state for the resulting Ru-clusters,in comparison of that derived from ruthenium chlorides.After the pyrolysis treatment,the Ru coordinated state in Ru_(x)N_(y)/C,with the Ru–N and Ru–Ru bonds,still showed the structural inheritance from the Ru(II)monomer,dimer,and tetramer,but using ruthenium chlorides as the Ru source resulted in the nanoscale Ru agglomerations.The ORR testing exhibited that the Ru_(x)N_(y)/C sample derived from the Ru(II)tetramer(Ru_(x)N_(y)/C-T)presents the higher catalytic activity than the other obtained samples in either alkaline or acidic electrolytes.Even in the acidic electrolyte,Ru_(x)N_(y)/C-T shows the comparable ORR activity to that of Pt/C catalysts,and it shows the superior tolerance against methanol and CO.The X-ray absorption spectroscopy and density functional theory calculations demonstrate that these tetra-nuclear Ru-clusters could be the most active site due to their broadened d-orbital bands and lower energy d-band center than those of other subnano species and nanocrystals,and their favorable Yeager-type adsorption of O_(2)-molecules is also contributed to promoting O–O bond cleavage and accelerating the ORR process.展开更多
Owing to the large exciton binding energy(>100 meV)of most organic materials,the process of exciton dissociation into free electrons and holes is seriously hindered,which plays a key role in the photocatalytic syst...Owing to the large exciton binding energy(>100 meV)of most organic materials,the process of exciton dissociation into free electrons and holes is seriously hindered,which plays a key role in the photocatalytic system.In this study,a series of chalcogen(S,Se)-substituted mesoporous covalent organic frameworks(COFs)have been synthesized for enhanced photocatalytic organic transformations.Photoelectrochemical measurements indicate that the introduction of semi-metallic Se atom and the enlargement of conjugation degree can not only reduce the exciton binding energy accelerating the charge separation,but also reduce the band gap of COFs.As a result,the COF-NUST-36 with the lowest exciton binding energy(39.5 meV)shows the highest photocatalytic performance for selective oxidation of amines(up to 98%Conv.and 97.5%Sel.).This work provides a feasible method for designing COFs with high photocatalytic activity by adjusting exciton binding energy.展开更多
Inorganic phosphate(Pi)is often limited in soils due to precipitation with iron(Fe)and aluminum(Al).To scavenge heterogeneously distributed phosphorus(P)resources,plants have evolved a local Pi signaling pathway that ...Inorganic phosphate(Pi)is often limited in soils due to precipitation with iron(Fe)and aluminum(Al).To scavenge heterogeneously distributed phosphorus(P)resources,plants have evolved a local Pi signaling pathway that induces malate secretion to solubilize the occluded Fe-P or Al-P oxides.In this study,we show that Pi limitation impaired brassinosteroid signaling and downregulated BRASSINAZOLE-RESISTANT 1(BZR1)expression in Arabidopsis thaliana.Exogenous 2,4-epibrassinolide treatment or constitutive activation of BZR1(in the bzr1-D mutant)significantly reduced primary root growth inhibition under Pi-starvation conditions by downregulating ALUMINUM-ACTIVATED MALATE TRANSPORTER 1(ALMT1)expression and malate secretion.Furthermore,At BZR1 competitively suppressed the activator effect of SENSITIVITY TO PROTON RHIZOTOXICITY 1(STOP1)on ALMT1 expression and malate secretion in Nicotiana benthamiana leaves and Arabidopsis.The ratio of nuclear-localized STOP1 and BZR1 determined ALMT1 expression and malate secretion in Arabidopsis.In addition,BZR1-inhibited malate secretion is conserved in rice(Oryza sativa).Our findings provide insight into plant mechanisms for optimizing the secretion of malate,an important carbon resource,to adapt to Pi-deficiency stress.展开更多
Summary What is already known on this topic?Men who have sex with men(MSM)in China have a high rate of human immunodeficiency virus(HIV)infection.Pre-exposure prophylaxis(PrEP)and postexposure prophylaxis(PEP)have bee...Summary What is already known on this topic?Men who have sex with men(MSM)in China have a high rate of human immunodeficiency virus(HIV)infection.Pre-exposure prophylaxis(PrEP)and postexposure prophylaxis(PEP)have been shown to be effective in preventing HIV,which may help to contain the HIV epidemic among MSM.What is added by this report?This study found that knowledge and usage of PrEP were low among MSM,indicating that this population is at high risk for HIV infection.Promotion of PrEP and PEP among MSM is necessary to reduce the risk of HIV infection in this population.What are the implications for public health practice?PrEP and PEP are novel HIV prevention strategies that have been demonstrated to be effective and safe.To further reduce HIV transmission among MSM in China,it is necessary to promote the use of PrEP and PEP.展开更多
Healthy soils are essential for sustainableagricultural development and soil health requires carefulassessment with increasing societal concern over envir-onmentally friendly agricultural development. Soil healthis th...Healthy soils are essential for sustainableagricultural development and soil health requires carefulassessment with increasing societal concern over envir-onmentally friendly agricultural development. Soil healthis the capacity of soil to function within ecologicalboundaries to sustain productivity, maintain environmentalquality, and promote plant and animal health. Physical,chemical and biological indicators are used to evaluate soilhealth;the biological indicators include microbes, proto-zoa and metazoa. Nematodes are the most abundantmetazoa and they vary in their sensitivity to pollutants andenvironmental disturbance. Soil nematode communitiesare useful biological indicators of soil health, withcommunity characteristics such as abundance, diversity,community structure and metabolic footprint all closelycorrelated with the soil environment. The community size,complexity and structure reflect the condition of the soil.Both free-living and plant parasitic nematodes are effec-tive ecological indicators, contributing to nutrient cyclingand having important roles as primary, secondary andtertiary consumers in food webs. Tillage inversion,cropping patterns and nutrient management may havestrong effects on soil nematodes, with changes in soilnematode communities reflecting soil disturbance. Somefree-living nematodes serve as biological models to testsoil condition in the laboratory and because of theseadvantages soil nematodes are increasingly being used asbiological indicators of soil health.展开更多
Patients with cancer are at increased risk of severe infections.From a cohort including 3060 patients with confirmed COVID-19,109(3.4%)cancer patients were included in this study.Among them,23(21.1%)patients died in t...Patients with cancer are at increased risk of severe infections.From a cohort including 3060 patients with confirmed COVID-19,109(3.4%)cancer patients were included in this study.Among them,23(21.1%)patients died in the hospital.Cancer patients,especially those with hematological malignancies(41.6%),urinary carcinoma(35.7%),malignancies of the digestive system(33.3%),gynecological malignancies(20%),and lung cancer(14.3%),had a much higher mortality than patients without cancer.A total of 19(17.4%)cancer patients were infected in the hospital.The clinical characteristics of deceased cancer patients were compared with those of recovered cancer patients.Multivariate Cox regression analysis indicated that a Nutritional Risk Screening(NRS2002)score≥3(adjusted hazard ratio(HR)11.00;95%confidence interval(CI)4.60–26.32;P<0.001),high-risk type(adjusted HR 18.81;95%CI 4.21–83.93;P<0.001),tumor stage IV(adjusted HR 4.26;95%CI 2.34–7.75;P<0.001),and recent adjuvant therapy(<1 month)(adjusted HR 3.16;95%CI 1.75–5.70;P<0.01)were independent risk factors for in-hospital death after adjusting for age,comorbidities,D-dimer,and lymphocyte count.In conclusion,cancer patients showed a higher risk of COVID-19 infection with a poorer prognosis than patients without cancer.Cancer patients with high-risk tumor,NRS2002 score≥3,advanced tumor stage,and recent adjuvant therapy(<1 month)may have high risk of mortality.展开更多
Human embryonic stem cells(hESCs)are pluripotent cells that have the ability of unlimited self-renewal and can be differentiated into different cell lineages,includ-ing neural stem(NS)cells.Diverse regulatory signalin...Human embryonic stem cells(hESCs)are pluripotent cells that have the ability of unlimited self-renewal and can be differentiated into different cell lineages,includ-ing neural stem(NS)cells.Diverse regulatory signaling pathways of neural stem cells differentiation have been discovered,and this will be of great benefit to uncover the mechanisms of neuronal differentiation in vivo and in vitro.However,the limitations of hESCs resource along with the religious and ethical concerns impede the pro-gress of ESCs application.Therefore,the induced pluri-potent stem cells(iPSCs)via somatic cell reprogramming have opened up another new territory for regenerative medicine.iPSCs now can be derived from a number of lin-eages of cells,and are able to differentiate into certain cell types,including neurons.Patient-specifi c iPSCs are being used in human neurodegenerative disease modeling and drug screening.Furthermore,with the development of somatic direct reprogramming or lineage reprogramming technique,a more effective approach for regenerative medicine could become a complement for iPSCs.展开更多
基金supported by the Hebei Province Cultural and Artistic Science Planning and Tourism Research Project[Grant No.HB22-ZD002].
文摘Carbon peak and carbon neutrality(dual-carbon)are important targets for the international response to climate change.The Silk Road Economic Belt is a strategic resource region and is important for future ecological environment and tourism development.Based on the“dual-carbon”targets,the Single index quantification,Multiple index synthesis,and Poly-criteria integration evaluation model were used in this study to measure the coordinated development index of the ecological environment,public service,and tourism economy along the Silk Road Economic Belt and to analyze its spatial and temporal evolution.Further,it explores the dynamic evolution and development trend of the three systems using the Kernel Density and Grey Markov Prediction Model.The results show that the coordinated development index along this region needs to be improved during the study period.Furthermore,the coordinated development index of the Southwest region is relatively higher than that of the Northwest region.From the development trend of the three systems,all of them develop in a stable manner;however,the tourism economy system is easily affected by external disturbances.The coordinated development index of the three systems changes dynamically and tends to be in a good state of coordination.There is a certain spatial and temporal heterogeneity.The gravity center of the coordinated development index has been in the Southwest region.During the forecast period,the coordinated development index along this region will improve significantly,while insufficient and unbalanced development will continue.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11774080)supported by NSERC of Canada
文摘The Schrödinger equation for the 2S and 2P states of the lithium-like ions Z=5–7,9–10 is solved by using the Rayleigh-Ritz variational method in Hylleraas coordinates.The leading-order relativistic and QED corrections are calculated perturbatively and higher-order corrections are estimated.The transition frequencies between the 2S_(1/2)and 2P_(J)(J=1/2,3/2)states are determined and compared with experimental and other theoretical results.Specifically,isotope shifts are also calculated for B^(2+).
基金financial support from National Natural Science Foundation of China(91534123,91834303,U1862117)supported by the State Key Laboratory of Multiphase Complex Systems(MPCS-2017-A-01)support by State key laboratory of Multiphase Complex Systems(MPCS)Facility Upgradation Program
文摘Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.
基金the National Natural Science Foundation of China(No.62175267)the Beijing Municipal Natural Science Foundation(No.4192061)+1 种基金the Fundamental Research Funds for the Central Universities(2020MDJC13)the Beijing Talents Foundation(2018000021223ZK45)for the financial support.
文摘High performance electro-optic modulator,as the key device of integrated ultra-wideband optical systems,have be-come the focus of research.Meanwhile,the organic-based hybrid electro-optic modulators,which make full use of the advant-ages of organic electro-optic(OEO)materials(e.g.high electro-optic coefficient,fast response speed,high bandwidth,easy pro-cessing/integration and low cost)have attracted considerable attention.In this paper,we introduce a series of high-perform-ance OEO materials that exhibit good properties in electro-optic activity and thermal stability.In addition,the recent progress of organic-based hybrid electro-optic devices is reviewed,including photonic crystal-organic hybrid(PCOH),silicon-organic hy-brid(SOH)and plasmonic-organic hybrid(POH)modulators.A high-performance integrated optical platform based on OEO ma-terials is a promising solution for growing high speeds and low power consumption in compact sizes.
文摘With the rapid development of the Internet of things and e-commerce, feature-based image retrieval and classification have become a serious challenge for shoppers searching websites for relevant product information. The last decade has witnessed great interest in research on content-based feature extraction techniques. Moreover, semantic attributes cannot fully express the rich image information. This paper designs and trains a deep convolutional neural network that the convolution kernel size and the order of network connection are based on the high efficiency of the filter capacity and coverage. To solve the problem of long training time and high resource share of deep convolutional neural network, this paper designed a shallow convolutional neural network to achieve the similar classification accuracy. The deep and shallow convolutional neural networks have data pre-processing, feature extraction and softmax classification. To evaluate the classification performance of the network, experiments were conducted using a public database Caltech256 and a homemade product image database containing 15 species of garment and 5 species of shoes on a total of 20,000 color images from shopping websites. Compared with the classification accuracy of combining content-based feature extraction techniques with traditional support vector machine techniques from 76.3% to 86.2%, the deep convolutional neural network obtains an impressive state-of-the-art classification accuracy of 92.1%, and the shallow convolutional neural network reached a classification accuracy of 90.6%. Moreover, the proposed convolutional neural networks can be integrated and implemented in other colour image database.
基金funded by Youth Science Foundation Fund Project of National Natural Science Foundation of China(51607148)Science and Technology R&D Program of China State Railway Group Co.,Ltd.(SY2020G001)Project of Sichuan Science and Technology Program(2021YJ0028)。
文摘Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.
基金supported by the National Key Research and Development Program of China(No.2022YFE0110400)the National Natural Science Foundation of China(Nos.52122207,52173245,52130206,U20A20337,and 52221006)the Fundamental Research Funds for the Central Universities(No.CLYY2022).
文摘Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low price.In this work,a series of well-dispersed nitrogen-coordinated Ru-clusters on carbon black(Ru_(x)N_(y)/C)were prepared by pyrolyzing different Ru-containing sandwich compounds as the Ru sources.The higher thermal stability of these complexed sandwich precursors(bis(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)monomer,dichloro(p-cymene)Ru(II)dimer,and chloro(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)tetramer)affords the control of coordinated state for the resulting Ru-clusters,in comparison of that derived from ruthenium chlorides.After the pyrolysis treatment,the Ru coordinated state in Ru_(x)N_(y)/C,with the Ru–N and Ru–Ru bonds,still showed the structural inheritance from the Ru(II)monomer,dimer,and tetramer,but using ruthenium chlorides as the Ru source resulted in the nanoscale Ru agglomerations.The ORR testing exhibited that the Ru_(x)N_(y)/C sample derived from the Ru(II)tetramer(Ru_(x)N_(y)/C-T)presents the higher catalytic activity than the other obtained samples in either alkaline or acidic electrolytes.Even in the acidic electrolyte,Ru_(x)N_(y)/C-T shows the comparable ORR activity to that of Pt/C catalysts,and it shows the superior tolerance against methanol and CO.The X-ray absorption spectroscopy and density functional theory calculations demonstrate that these tetra-nuclear Ru-clusters could be the most active site due to their broadened d-orbital bands and lower energy d-band center than those of other subnano species and nanocrystals,and their favorable Yeager-type adsorption of O_(2)-molecules is also contributed to promoting O–O bond cleavage and accelerating the ORR process.
基金financially supported by the National Natural Science Foundation of China(No.22171136)the Natural Science Foundation of Jiangsu Province(Nos.BK20220928,BK20220079)+4 种基金the Fundamental Research Funds for the Central Universities(Nos.30921011102,30922010902)the Medical Innovation and Development Project of Lanzhou University(No.lzuyxcx-2022-156)CAMS Innovation Fund for Medical Sciences(CIFMS,Nos.2019-I2M-5-074,2021-I2M-1-026,2021-I2M-3-001)the Startup Funding from Nanjing University of Science and Technology(Nos.AE89990,AE89991/376)G.Zhang acknowledges the support of the Thousand Young Talent Plan.
文摘Owing to the large exciton binding energy(>100 meV)of most organic materials,the process of exciton dissociation into free electrons and holes is seriously hindered,which plays a key role in the photocatalytic system.In this study,a series of chalcogen(S,Se)-substituted mesoporous covalent organic frameworks(COFs)have been synthesized for enhanced photocatalytic organic transformations.Photoelectrochemical measurements indicate that the introduction of semi-metallic Se atom and the enlargement of conjugation degree can not only reduce the exciton binding energy accelerating the charge separation,but also reduce the band gap of COFs.As a result,the COF-NUST-36 with the lowest exciton binding energy(39.5 meV)shows the highest photocatalytic performance for selective oxidation of amines(up to 98%Conv.and 97.5%Sel.).This work provides a feasible method for designing COFs with high photocatalytic activity by adjusting exciton binding energy.
基金supported by the National Key Research and Development Program of China(2022YFD1900700)the National Natural Science Foundation of China(32072663)the Opening Project of Guangdong Provincial Key Laboratory of Quality&Safety Risk Assessment for Agroproducts(SZKF202201)。
文摘Inorganic phosphate(Pi)is often limited in soils due to precipitation with iron(Fe)and aluminum(Al).To scavenge heterogeneously distributed phosphorus(P)resources,plants have evolved a local Pi signaling pathway that induces malate secretion to solubilize the occluded Fe-P or Al-P oxides.In this study,we show that Pi limitation impaired brassinosteroid signaling and downregulated BRASSINAZOLE-RESISTANT 1(BZR1)expression in Arabidopsis thaliana.Exogenous 2,4-epibrassinolide treatment or constitutive activation of BZR1(in the bzr1-D mutant)significantly reduced primary root growth inhibition under Pi-starvation conditions by downregulating ALUMINUM-ACTIVATED MALATE TRANSPORTER 1(ALMT1)expression and malate secretion.Furthermore,At BZR1 competitively suppressed the activator effect of SENSITIVITY TO PROTON RHIZOTOXICITY 1(STOP1)on ALMT1 expression and malate secretion in Nicotiana benthamiana leaves and Arabidopsis.The ratio of nuclear-localized STOP1 and BZR1 determined ALMT1 expression and malate secretion in Arabidopsis.In addition,BZR1-inhibited malate secretion is conserved in rice(Oryza sativa).Our findings provide insight into plant mechanisms for optimizing the secretion of malate,an important carbon resource,to adapt to Pi-deficiency stress.
文摘Summary What is already known on this topic?Men who have sex with men(MSM)in China have a high rate of human immunodeficiency virus(HIV)infection.Pre-exposure prophylaxis(PrEP)and postexposure prophylaxis(PEP)have been shown to be effective in preventing HIV,which may help to contain the HIV epidemic among MSM.What is added by this report?This study found that knowledge and usage of PrEP were low among MSM,indicating that this population is at high risk for HIV infection.Promotion of PrEP and PEP among MSM is necessary to reduce the risk of HIV infection in this population.What are the implications for public health practice?PrEP and PEP are novel HIV prevention strategies that have been demonstrated to be effective and safe.To further reduce HIV transmission among MSM in China,it is necessary to promote the use of PrEP and PEP.
基金the National KeyResearch and Development Program of China (2017YFD0202102,2016YFD0200405, and 2016YFE0101100).
文摘Healthy soils are essential for sustainableagricultural development and soil health requires carefulassessment with increasing societal concern over envir-onmentally friendly agricultural development. Soil healthis the capacity of soil to function within ecologicalboundaries to sustain productivity, maintain environmentalquality, and promote plant and animal health. Physical,chemical and biological indicators are used to evaluate soilhealth;the biological indicators include microbes, proto-zoa and metazoa. Nematodes are the most abundantmetazoa and they vary in their sensitivity to pollutants andenvironmental disturbance. Soil nematode communitiesare useful biological indicators of soil health, withcommunity characteristics such as abundance, diversity,community structure and metabolic footprint all closelycorrelated with the soil environment. The community size,complexity and structure reflect the condition of the soil.Both free-living and plant parasitic nematodes are effec-tive ecological indicators, contributing to nutrient cyclingand having important roles as primary, secondary andtertiary consumers in food webs. Tillage inversion,cropping patterns and nutrient management may havestrong effects on soil nematodes, with changes in soilnematode communities reflecting soil disturbance. Somefree-living nematodes serve as biological models to testsoil condition in the laboratory and because of theseadvantages soil nematodes are increasingly being used asbiological indicators of soil health.
基金the State Key Project on Infectious Diseases of China(No.2018ZX10723204-003)the National Natural Science Foundation of China(Nos.81874065 and 81874149)the Hepato-BiliaryPancreatic Cancer Investigation Fund of Chen Xiao-ping Foundation for the Development of Science and Technology of Hubei Province(No.CXPJJH11800001-2018356).
文摘Patients with cancer are at increased risk of severe infections.From a cohort including 3060 patients with confirmed COVID-19,109(3.4%)cancer patients were included in this study.Among them,23(21.1%)patients died in the hospital.Cancer patients,especially those with hematological malignancies(41.6%),urinary carcinoma(35.7%),malignancies of the digestive system(33.3%),gynecological malignancies(20%),and lung cancer(14.3%),had a much higher mortality than patients without cancer.A total of 19(17.4%)cancer patients were infected in the hospital.The clinical characteristics of deceased cancer patients were compared with those of recovered cancer patients.Multivariate Cox regression analysis indicated that a Nutritional Risk Screening(NRS2002)score≥3(adjusted hazard ratio(HR)11.00;95%confidence interval(CI)4.60–26.32;P<0.001),high-risk type(adjusted HR 18.81;95%CI 4.21–83.93;P<0.001),tumor stage IV(adjusted HR 4.26;95%CI 2.34–7.75;P<0.001),and recent adjuvant therapy(<1 month)(adjusted HR 3.16;95%CI 1.75–5.70;P<0.01)were independent risk factors for in-hospital death after adjusting for age,comorbidities,D-dimer,and lymphocyte count.In conclusion,cancer patients showed a higher risk of COVID-19 infection with a poorer prognosis than patients without cancer.Cancer patients with high-risk tumor,NRS2002 score≥3,advanced tumor stage,and recent adjuvant therapy(<1 month)may have high risk of mortality.
基金the National Basic Research Program 973 program(No.2012CB966800)the Thousand Youth Talents Program and the Pioneer Programs of Chinese Academy of Sciences。
文摘Human embryonic stem cells(hESCs)are pluripotent cells that have the ability of unlimited self-renewal and can be differentiated into different cell lineages,includ-ing neural stem(NS)cells.Diverse regulatory signaling pathways of neural stem cells differentiation have been discovered,and this will be of great benefit to uncover the mechanisms of neuronal differentiation in vivo and in vitro.However,the limitations of hESCs resource along with the religious and ethical concerns impede the pro-gress of ESCs application.Therefore,the induced pluri-potent stem cells(iPSCs)via somatic cell reprogramming have opened up another new territory for regenerative medicine.iPSCs now can be derived from a number of lin-eages of cells,and are able to differentiate into certain cell types,including neurons.Patient-specifi c iPSCs are being used in human neurodegenerative disease modeling and drug screening.Furthermore,with the development of somatic direct reprogramming or lineage reprogramming technique,a more effective approach for regenerative medicine could become a complement for iPSCs.
