Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosph...Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray imaging.However,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the magnetopause.The analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration models.This makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical models.We propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the magnetosphere.The idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch estimator.The Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the estimator.Experimental results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural similarity.The restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving the reconstruction results.Hence,the proposed technology may be feasible for processing SXI-simulated observation images.展开更多
Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resista...Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.展开更多
The interfacial nonradiative recombination loss caused by the deep traps and mismatched band alignment restrained the commercial viability of perovskite solar cells(PSCs). Herein, we have constructed ferrocene carboxy...The interfacial nonradiative recombination loss caused by the deep traps and mismatched band alignment restrained the commercial viability of perovskite solar cells(PSCs). Herein, we have constructed ferrocene carboxylic acid(FcA) and octafluoropentyl-ferrocenyl-carboxylate(OFFcA) interstitial conductive mediums to modulate the integral heterointerface properties and the photovoltaic performances of PSCs.By comparing the passivation strengths of the two molecules, we found that the synergistic effects among Fc/Fc^(+)redox shuttle, C=O group, and F substituents realize the optimal elimination of interfacial trap sources. Electron-withdrawing F groups reinforce the capacity of the Fc/Fc^(+)redox shuttle for the healing of metallic Pb defects and provide extensive anchoring sites to stabilize the organic components.Additionally, the homogeneity of the OFFcA layer as well as the humidity stability of perovskite film are facilitated through the introduction of F substituents, which reduce the contact resistance and improve the interfacial charge transfer. The champion OFFcA-modified device delivers an exceptional PCE of 23.62%, exceeding those of the control(PCE=22.32%) and FcA-modified(PCE=23.06%) devices.Moreover, the unencapsulated OFFcA-modified device retains 82.7% of the primary efficiency at 60%RH for more than 50 d and only loses less than 10% of the primary efficiency when stored in a glove box for more than 2000 h.展开更多
Moisture-enabled electricity(ME)is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can b...Moisture-enabled electricity(ME)is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can be directly applied to energy harvesting and signal expression.However,ME can be unreliable in numerous applications due to its sluggish response to moisture,thus sacrificing the value of fast energy harvesting and highly accurate information representation.Here,by constructing a moisture-electric-moisture-sensitive(ME-MS)heterostructure,we develop an efficient ME generator with ultra-fast electric response to moisture achieved by triggering Grotthuss protons hopping in the sensitized ZnO,which modulates the heterostructure built-in interfacial potential,enables quick response(0.435 s),an unprecedented ultra-fast response rate of 972.4 mV s^(−1),and a durable electrical signal output for 8 h without any attenuation.Our research provides an efficient way to generate electricity and important insight for a deeper understanding of the mechanisms of moisture-generated carrier migration in ME generator,which has a more comprehensive working scene and can serve as a typical model for human health monitoring and smart medical electronics design.展开更多
This paper presents a novel framework aimed at quantifying uncertainties associated with the 3D reconstruction of smoke from2Dimages.This approach reconstructs color and density fields from 2D images using Neural Radi...This paper presents a novel framework aimed at quantifying uncertainties associated with the 3D reconstruction of smoke from2Dimages.This approach reconstructs color and density fields from 2D images using Neural Radiance Field(NeRF)and improves image quality using frequency regularization.The NeRF model is obtained via joint training ofmultiple artificial neural networks,whereby the expectation and standard deviation of density fields and RGB values can be evaluated for each pixel.In addition,customized physics-informed neural network(PINN)with residual blocks and two-layer activation functions are utilized to input the density fields of the NeRF into Navier-Stokes equations and convection-diffusion equations to reconstruct the velocity field.The velocity uncertainties are also evaluated through ensemble learning.The effectiveness of the proposed algorithm is demonstrated through numerical examples.The presentmethod is an important step towards downstream tasks such as reliability analysis and robust optimization in engineering design.展开更多
Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry...Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry,and global climate.To investigate which plant conserves best the core eudicots common ancestor genome,we compared Arcto-Tertiary relict Nyssaceae and 30 other eudicot plant families.The genomes of Davidia involucrata(a known living fossil),Camptotheca acuminata and Nyssa sinensis,one per existent genus of Nyssaceae,were performed comparative genomic analysis.We found that Nyssaceae originated from a single Nyssaceae common tetraploidization event(NCT)-autotetraploidization 28-31 Mya after the core eudicot common hexaploidization(ECH).We identified Nyssaceae orthologous and paralogous genes,determined its chromosomal evolutionary trajectory,and reconstructed the Nyssaceae most recent ancestor genome.D.involucrata genome contained the entire seven paleochromosomes and 17 ECH-generated eudicot common ancestor chromosomes and was the slowest in mutation among the analyzed 42 species of 31 plant families.Combing both its high retention of paleochromosomes and its low mutation rate,D.involucrata provides the best case in conservation of the core eudicot paleogenome.展开更多
The running stability of high-speed train is largely constrained by the wheel-rail coupling relationship,and the continuous wear between the wheel and rail surfaces will profoundly affect the dynamic performance of th...The running stability of high-speed train is largely constrained by the wheel-rail coupling relationship,and the continuous wear between the wheel and rail surfaces will profoundly affect the dynamic performance of the train.In recent years,under the background of increasing train speed,some scientific researchers have proposed a new idea of using the lift force generated by the aerodynamic wings(aero-wing)installed on the roof to reduce the sprung load of the carriage in order to alleviate the wear and tear of the wheel and rail.Based on the bidirectional running characteristics of high-speed train,this paper proposes a scheme to apply aero-wings with anteroposterior symmetrical cross-sections on the roof of the train.After the verification of the wind tunnel experimental data,the relatively better airfoil section and extension formof anteroposterior symmetrical aero-wing is selected respectively in this paper,and the aero-wings are fixedly connected to the roof of the train through the mounting column to conduct aerodynamic simulation analysis.The research shows that:compared with the circular-arc and oval crosssections,this paper believes that the crescent cross-section can form greater aerodynamic lift force in a limited space.Considering factors such as aerodynamic parameters,ground effect,and manufacturing process,this paper proposes to adopt aero-wings with arc type extension form and connect them to the roof of the train through mounting columns with shuttle cross-section.When the roof of the train is covered with aero-wings and runs at high speed,the sprung load of the carriages can be effectively reduced.However,there are certain hidden dangers in the tail carriage due to the large amount of lift force,so,the intervention of the aero-wing lifting mechanism is required.At the same time,it is necessary to optimize the overall aerodynamic drag force reduction in the followup work.展开更多
Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by usin...Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by using syntenic analysis combined with phylogenomic analysis of C.chinensis and four other representative genomes from basal and core eudicots,we confirmed that the WGD event in C.chinensis was shared by Aquilegia coerulea and Papaver somniferum L.and quickly occurred after Ranunculales diverged from other eudicots,likely a Ranunculales common tetraploidization(RCT).The synonymous nucleotide substitutions at synonymous sites distribution of syntenic blocks across these genomes showed that the evolutionary rate of the P.somniferum genome is faster than that of the C.chinensis genome by approximately 13.7%,possibly due to Papaveraceaes having an additional special tetraploidization event(PST).After Ks correction,the RCT dated to 115—130 million years ago(MYA),which was close to the divergence of Ranunculaceaes and Papaveraceaes approximately115.45—130.51 MYA.Moreover,we identified homologous genes related to polyploidization and speciation and constructed multiple sequence alignments with different reference genomes.Notably,the event-related subgenomes in the basal genomes all showed genomic fractionation bias,suggesting a likely allopolyploid nature of the RCT,PST and T-Alpha and T-Beta events in Tetracentron sinense.In addition,we detected that the sixteen P450 subfamilies were markedly expanded in the genomes of Ranunculales,and most of them were related to the RCT and PST events.We constructed a new platform for Early Eudicot Comparative Genomic Research(http://www.cgrpoee.top/index.html)to store more information.In summary,our findings support the WGD of C.chinensis shared by Ranunculales,which is likely an allotetraploidization event.This present effort offered new insights into the evolution of key polyploidization events and the genes related to secondary metabolites during the diversification of early eudicots.展开更多
With the further advancement of the“National Fitness”strategy and the continuous development of the information age,the National Fitness Activity Centers have become more comprehensive.The comprehensiveness is refle...With the further advancement of the“National Fitness”strategy and the continuous development of the information age,the National Fitness Activity Centers have become more comprehensive.The comprehensiveness is reflected in the design of diversified sports functions and spaces.The article serves to explore the comprehensive development trend of National Fitness Activity Centers.Through summarizing and sorting out domestic and foreign cases,the trend of the comprehensive development of National Fitness Activity Centers is predicted at three levels:industry,city,and individual functions.展开更多
Aiming at deep roadway anchorage solids, laboratory similar model tests were used to reveal the mechanical properties of anchorage solids with different anchorage lengths under the coupling effect of temperature and p...Aiming at deep roadway anchorage solids, laboratory similar model tests were used to reveal the mechanical properties of anchorage solids with different anchorage lengths under the coupling effect of temperature and pressure, and SPSS statistical analysis software was used to conduct linear regression analysis of the ultimate anchorage force obtained from the tests. The results show that: through multiple linear regression analysis, the influence degree of temperature and pressure coupling on the ultimate anchorage force is arranged in order of anchoring length > surrounding rock strength > temperature > side pressure coefficient, and the linear regression equation of the model is obtained. Compared with the linear regression equation of simulation results, the model has a high explanatory ability.展开更多
TiO2-seashell composites prepared via a sol-gel method were used to generate carbonate radicals(·CO3–) under solar light irradiation. ·CO3–, a selective radical, was employed to degrade the target tetracyc...TiO2-seashell composites prepared via a sol-gel method were used to generate carbonate radicals(·CO3–) under solar light irradiation. ·CO3–, a selective radical, was employed to degrade the target tetracycline hydrochloride contaminant. A series of characterizations was carried out to study the structure and composition of the synthesized TiO2-seashell composite. This material exhibits excellent solar light-driven photochemical activity in the decomposition of tetracycline hydrochloride. The possible pathway and mechanism for the photodegradation process were proposed on the basis of high-resolution electrospray ionization time-of-flight mass spectrometry experiments. Finally, we investigated the reusability of the TiO2-seashell composite. This study is expected to provide a new facile pathway for the application of ·CO3– radicals to degrade special organic pollutants in water.展开更多
Cardiovascular disease is the leading cause of human death worldwide. Autophagy is an evolutionarily conserved degradation pathway,which is a highly conserved cellular degradation process in which lysosomes decompose ...Cardiovascular disease is the leading cause of human death worldwide. Autophagy is an evolutionarily conserved degradation pathway,which is a highly conserved cellular degradation process in which lysosomes decompose their own organelles and recycle the resulting macromolecules.Autophagy is critical in maintaining cardiovascular homeostasis and function, and excessive or insufficient autophagy or autophagic flux can lead to cardiovascular disease. Enormous evidence indicates that exercise training plays a beneficial role in the prevention and treatment of cardiovascular diseases. The regulation of autophagy during exercise is a bidirectional process. For cardiovascular disease caused by either insufficient or excessive autophagy, exercise training restores normal autophagy function and delays the progression of cardiovascular disease.An in-depth exploration and discussion of exercise-mediated regulation of autophagy in the cardiovascular system can broaden our view about the prevention of various autophagy-related diseases through exercise training. In this article, we review autophagy and its related signaling pathways,as well as autophagy-dependent beneficial effects of exercise in cardiovascular system.展开更多
Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly re...Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.展开更多
Diabetes has become a global concern at present,among which type 2 diabetes mellitus(T2DM)accounts for approximately 90%-95%of patients.T2DM is a type of metabolic disorder syndrome that results from a genetic defect,...Diabetes has become a global concern at present,among which type 2 diabetes mellitus(T2DM)accounts for approximately 90%-95%of patients.T2DM is a type of metabolic disorder syndrome that results from a genetic defect,and it is based on insulin resistance and an insulin secretion disorder.The occurrence of T2DM is usually the outcome of both genetic and environmental factors and their interactions.The etiology and pathogenesis of diabetes have not been fully elucidated,and no radical therapeutic cure has been found.Patients with T2DM suffer from complications such as the development of a chronic hyperglycemic condition and even serious metabolic disorders and organ damage in the body and depression and dementia,in addition to other chronic complications.Many studies have suggested that diet is crucial in the development of diabetes and the control of blood glucose.Natural substances have the characteristics of low toxicity and few side effects and may be key to the development of diabetic health products and preventive treatments.This paper reviews the etiology,pathogenesis,risks,treatments and diets related to T2DM to summarize the types of recently available natural products,from both local and foreign sources,for lowering blood glucose at home and their application in supplementary hypoglycemic foods.The key findings and conclusions suggest that there are various known T2DM-inducing factors,including genetic and environmental factors and three types of hybrid factors.展开更多
Fruit detection and counting are essential tasks for horticulture research.With computer vision technology development,fruit detection techniques based on deep learning have been widely used in modern orchards.However...Fruit detection and counting are essential tasks for horticulture research.With computer vision technology development,fruit detection techniques based on deep learning have been widely used in modern orchards.However,most deep learning-based fruit detection models are generated based on fully supervised approaches,which means a model trained with one domain species may not be transferred to another.There is always a need to recreate and label the relevant training dataset,but such a procedure is time-consuming and labor-intensive.This paper proposed a domain adaptation method that can transfer an existing model trained from one domain to a new domain without extra manual labeling.The method includes three main steps:transform the source fruit image(with labeled information)into the target fruit image(without labeled information)through the CycleGAN network;Automatically label the target fruit image by a pseudo-label process;Improve the labeling accuracy by a pseudo-label self-learning approach.Use a labeled orange image dataset as the source domain,unlabeled apple and tomato image dataset as the target domain,the performance of the proposed method from the perspective of fruit detection has been evaluated.Without manual labeling for target domain image,the mean average precision reached 87.5%for apple detection and 76.9%for tomato detection,which shows that the proposed method can potentially fill the species gap in deep learning-based fruit detection.展开更多
Objective:To evaluate preoperative serum calcium concentration and investigate the association between calcium level and positive peritoneal cytology in endometrial carcinoma(EC).Methods:A total of 510 patients who we...Objective:To evaluate preoperative serum calcium concentration and investigate the association between calcium level and positive peritoneal cytology in endometrial carcinoma(EC).Methods:A total of 510 patients who were diagnosed with EC and had surgery were initially enrolled in this study at Peking University People's Hospital between January 2012 and December 2016.Clinical characteristics and preoperative serum calcium,albumin,carbohydrate antigen(CA)125,CA19-9,carcinoembryonic antigen(CEA)were extracted from patient records and evaluated according to postoperative peritoneal cytology.Predictive factors were assessed with Cox univariate and multivariate analyses.Factors selected from multivariate analysis results were used to build a predictive model.Results:A total of 510 patients are identified in our database and 444 patients who fulfilled inclusion and exclusion criteria are included in this study.Univariate analysis revealed that ionized calcium concentration was closely related to positive peritoneal cytology,tumor grade and lymph-vascular space invasion(LVSI).Moreover,peritoneal cytology was significantly associated with hypertension,tubal ligation,serum CA125,CA19-9,CEA and ionized calcium level.Multivariate analysis revealed that albumin-adjusted calcium level,CA125 and tubal ligation were independent predictive factors of positive peritoneal cytology(P<0.05).A combination of ionized calcium level with the other two indexes yielded significantly great area under the curve(AUC=0.824).Conclusions:This study enhanced the value of preoperative ionized calcium level.We also identified several potential biomarkers to predict positive peritoneal cytology in EC patients before surgery.展开更多
In this manuscript,Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites was fabricated via an ultrasonic-assisted process.The activity of the as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites for photocatalytic CO_(2) ...In this manuscript,Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites was fabricated via an ultrasonic-assisted process.The activity of the as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites for photocatalytic CO_(2) reduction was studied under visible light.The as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites show a superior activity for photocatalytic CO_(2) reduction to produce CH4 and CO,with an optimum activity achieved over 0.5 Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6).The obvious superior activity observed over Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites as compared with bare Cs_(2)AgBiBr_(6) and bare Bi_(2)WO_(6) as well as a mechanical mixture of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) can be owe to the fabrication of an efficient S-scheme heterojunction,which accelerates the separation of the photogenerated charge carriers in Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) without sacrificing the high redox capability of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6).This work demonstrates that the coupling of two photocatalytic materials with staggered band alignment to form an S-scheme heterojunction is an effective strategy to develop efficient photocatalytic systems and also highlights the promising role of using lead free perovskites in photocatalysis.展开更多
Geological hazard is an adverse geological condition that can cause loss of life and property.Accurate prediction and analysis of geological hazards is an important and challenging task.In the past decade,there has be...Geological hazard is an adverse geological condition that can cause loss of life and property.Accurate prediction and analysis of geological hazards is an important and challenging task.In the past decade,there has been a great expansion of geohazard detection data and advancement in data-driven simulation techniques.In particular,great efforts have been made in applying deep learning to predict geohazards.To understand the recent progress in this field,this paper provides an overview of the commonly used data sources and deep neural networks in the prediction of a variety of geological hazards.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42322408,42188101,41974211,and 42074202)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDJ-SSW-JSC028)+1 种基金the Strategic Priority Program on Space Science,Chinese Academy of Sciences(Grant Nos.XDA15052500,XDA15350201,and XDA15014800)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y202045)。
文摘Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray imaging.However,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the magnetopause.The analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration models.This makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical models.We propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the magnetosphere.The idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch estimator.The Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the estimator.Experimental results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural similarity.The restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving the reconstruction results.Hence,the proposed technology may be feasible for processing SXI-simulated observation images.
基金funded by the Science and Technology Research and Development Plan of the China State Railway Group Company Limited(No.N2023J053).
文摘Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.
基金National Natural Science Foundation of China (22072034)China Postdoctoral Science Foundation (2020T130147, 2020M681084, and 2022M710949)+1 种基金Postdoctoral Foundation of Heilongjiang Province (LBH-Z19059 and LBH-Z22106)Natural Science Foundation of Heilongjiang Youth Fund (YQ2021B002)。
文摘The interfacial nonradiative recombination loss caused by the deep traps and mismatched band alignment restrained the commercial viability of perovskite solar cells(PSCs). Herein, we have constructed ferrocene carboxylic acid(FcA) and octafluoropentyl-ferrocenyl-carboxylate(OFFcA) interstitial conductive mediums to modulate the integral heterointerface properties and the photovoltaic performances of PSCs.By comparing the passivation strengths of the two molecules, we found that the synergistic effects among Fc/Fc^(+)redox shuttle, C=O group, and F substituents realize the optimal elimination of interfacial trap sources. Electron-withdrawing F groups reinforce the capacity of the Fc/Fc^(+)redox shuttle for the healing of metallic Pb defects and provide extensive anchoring sites to stabilize the organic components.Additionally, the homogeneity of the OFFcA layer as well as the humidity stability of perovskite film are facilitated through the introduction of F substituents, which reduce the contact resistance and improve the interfacial charge transfer. The champion OFFcA-modified device delivers an exceptional PCE of 23.62%, exceeding those of the control(PCE=22.32%) and FcA-modified(PCE=23.06%) devices.Moreover, the unencapsulated OFFcA-modified device retains 82.7% of the primary efficiency at 60%RH for more than 50 d and only loses less than 10% of the primary efficiency when stored in a glove box for more than 2000 h.
基金the Natural Science Foundation of Beijing Municipality(2222075)National Natural Science Foundation of China(22279010,21671020,51673026)Analysis&Testing Center,Beijing Institute of Technology.
文摘Moisture-enabled electricity(ME)is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can be directly applied to energy harvesting and signal expression.However,ME can be unreliable in numerous applications due to its sluggish response to moisture,thus sacrificing the value of fast energy harvesting and highly accurate information representation.Here,by constructing a moisture-electric-moisture-sensitive(ME-MS)heterostructure,we develop an efficient ME generator with ultra-fast electric response to moisture achieved by triggering Grotthuss protons hopping in the sensitized ZnO,which modulates the heterostructure built-in interfacial potential,enables quick response(0.435 s),an unprecedented ultra-fast response rate of 972.4 mV s^(−1),and a durable electrical signal output for 8 h without any attenuation.Our research provides an efficient way to generate electricity and important insight for a deeper understanding of the mechanisms of moisture-generated carrier migration in ME generator,which has a more comprehensive working scene and can serve as a typical model for human health monitoring and smart medical electronics design.
基金funded by the National Natural Science Foundation of China(NSFC)(No.52274222)research project supported by Shanxi Scholarship Council of China(No.2023-036).
文摘This paper presents a novel framework aimed at quantifying uncertainties associated with the 3D reconstruction of smoke from2Dimages.This approach reconstructs color and density fields from 2D images using Neural Radiance Field(NeRF)and improves image quality using frequency regularization.The NeRF model is obtained via joint training ofmultiple artificial neural networks,whereby the expectation and standard deviation of density fields and RGB values can be evaluated for each pixel.In addition,customized physics-informed neural network(PINN)with residual blocks and two-layer activation functions are utilized to input the density fields of the NeRF into Navier-Stokes equations and convection-diffusion equations to reconstruct the velocity field.The velocity uncertainties are also evaluated through ensemble learning.The effectiveness of the proposed algorithm is demonstrated through numerical examples.The presentmethod is an important step towards downstream tasks such as reliability analysis and robust optimization in engineering design.
基金supported by the National Natural Science Foundation of China(Grant Nos.32170236,31501333,and 32000405)Natural Science Foundation of Hebei Province(Grant No.C2020209064)the Innovation and Entrepreneurship Training Program for College Students of North China University of Science and Technology(Grant No.X2019252)。
文摘Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry,and global climate.To investigate which plant conserves best the core eudicots common ancestor genome,we compared Arcto-Tertiary relict Nyssaceae and 30 other eudicot plant families.The genomes of Davidia involucrata(a known living fossil),Camptotheca acuminata and Nyssa sinensis,one per existent genus of Nyssaceae,were performed comparative genomic analysis.We found that Nyssaceae originated from a single Nyssaceae common tetraploidization event(NCT)-autotetraploidization 28-31 Mya after the core eudicot common hexaploidization(ECH).We identified Nyssaceae orthologous and paralogous genes,determined its chromosomal evolutionary trajectory,and reconstructed the Nyssaceae most recent ancestor genome.D.involucrata genome contained the entire seven paleochromosomes and 17 ECH-generated eudicot common ancestor chromosomes and was the slowest in mutation among the analyzed 42 species of 31 plant families.Combing both its high retention of paleochromosomes and its low mutation rate,D.involucrata provides the best case in conservation of the core eudicot paleogenome.
基金supported by National Key Research and Development Program of China (2020YFA0710902)National Natural Science Foundation of China (12172308)Project of State Key Laboratory of Traction Power (2023TPL-T05).
文摘The running stability of high-speed train is largely constrained by the wheel-rail coupling relationship,and the continuous wear between the wheel and rail surfaces will profoundly affect the dynamic performance of the train.In recent years,under the background of increasing train speed,some scientific researchers have proposed a new idea of using the lift force generated by the aerodynamic wings(aero-wing)installed on the roof to reduce the sprung load of the carriage in order to alleviate the wear and tear of the wheel and rail.Based on the bidirectional running characteristics of high-speed train,this paper proposes a scheme to apply aero-wings with anteroposterior symmetrical cross-sections on the roof of the train.After the verification of the wind tunnel experimental data,the relatively better airfoil section and extension formof anteroposterior symmetrical aero-wing is selected respectively in this paper,and the aero-wings are fixedly connected to the roof of the train through the mounting column to conduct aerodynamic simulation analysis.The research shows that:compared with the circular-arc and oval crosssections,this paper believes that the crescent cross-section can form greater aerodynamic lift force in a limited space.Considering factors such as aerodynamic parameters,ground effect,and manufacturing process,this paper proposes to adopt aero-wings with arc type extension form and connect them to the roof of the train through mounting columns with shuttle cross-section.When the roof of the train is covered with aero-wings and runs at high speed,the sprung load of the carriages can be effectively reduced.However,there are certain hidden dangers in the tail carriage due to the large amount of lift force,so,the intervention of the aero-wing lifting mechanism is required.At the same time,it is necessary to optimize the overall aerodynamic drag force reduction in the followup work.
基金funded by the National Natural Science Foundation of China(Grant Nos.32170236 and 31501333)the Natural Science Foundation of Hebei Province(Grant No.C2020209064)the Youth Foundation of Educational Committee of Hebei Province(Grant No.QN2020139)。
文摘Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by using syntenic analysis combined with phylogenomic analysis of C.chinensis and four other representative genomes from basal and core eudicots,we confirmed that the WGD event in C.chinensis was shared by Aquilegia coerulea and Papaver somniferum L.and quickly occurred after Ranunculales diverged from other eudicots,likely a Ranunculales common tetraploidization(RCT).The synonymous nucleotide substitutions at synonymous sites distribution of syntenic blocks across these genomes showed that the evolutionary rate of the P.somniferum genome is faster than that of the C.chinensis genome by approximately 13.7%,possibly due to Papaveraceaes having an additional special tetraploidization event(PST).After Ks correction,the RCT dated to 115—130 million years ago(MYA),which was close to the divergence of Ranunculaceaes and Papaveraceaes approximately115.45—130.51 MYA.Moreover,we identified homologous genes related to polyploidization and speciation and constructed multiple sequence alignments with different reference genomes.Notably,the event-related subgenomes in the basal genomes all showed genomic fractionation bias,suggesting a likely allopolyploid nature of the RCT,PST and T-Alpha and T-Beta events in Tetracentron sinense.In addition,we detected that the sixteen P450 subfamilies were markedly expanded in the genomes of Ranunculales,and most of them were related to the RCT and PST events.We constructed a new platform for Early Eudicot Comparative Genomic Research(http://www.cgrpoee.top/index.html)to store more information.In summary,our findings support the WGD of C.chinensis shared by Ranunculales,which is likely an allotetraploidization event.This present effort offered new insights into the evolution of key polyploidization events and the genes related to secondary metabolites during the diversification of early eudicots.
文摘With the further advancement of the“National Fitness”strategy and the continuous development of the information age,the National Fitness Activity Centers have become more comprehensive.The comprehensiveness is reflected in the design of diversified sports functions and spaces.The article serves to explore the comprehensive development trend of National Fitness Activity Centers.Through summarizing and sorting out domestic and foreign cases,the trend of the comprehensive development of National Fitness Activity Centers is predicted at three levels:industry,city,and individual functions.
文摘Aiming at deep roadway anchorage solids, laboratory similar model tests were used to reveal the mechanical properties of anchorage solids with different anchorage lengths under the coupling effect of temperature and pressure, and SPSS statistical analysis software was used to conduct linear regression analysis of the ultimate anchorage force obtained from the tests. The results show that: through multiple linear regression analysis, the influence degree of temperature and pressure coupling on the ultimate anchorage force is arranged in order of anchoring length > surrounding rock strength > temperature > side pressure coefficient, and the linear regression equation of the model is obtained. Compared with the linear regression equation of simulation results, the model has a high explanatory ability.
文摘TiO2-seashell composites prepared via a sol-gel method were used to generate carbonate radicals(·CO3–) under solar light irradiation. ·CO3–, a selective radical, was employed to degrade the target tetracycline hydrochloride contaminant. A series of characterizations was carried out to study the structure and composition of the synthesized TiO2-seashell composite. This material exhibits excellent solar light-driven photochemical activity in the decomposition of tetracycline hydrochloride. The possible pathway and mechanism for the photodegradation process were proposed on the basis of high-resolution electrospray ionization time-of-flight mass spectrometry experiments. Finally, we investigated the reusability of the TiO2-seashell composite. This study is expected to provide a new facile pathway for the application of ·CO3– radicals to degrade special organic pollutants in water.
基金supported by grants from the National Natural Science Foundation of China(81722008,91639101,and 81570362 to J.Xiao,and 81800358 to L.Wang)from the Innovation Program of Shanghai Municipal Education Commission(2017-01-07-00-09-E00042 to J.Xiao)+1 种基金from the Science and Technology Commission of Shanghai Municipality(17010500100 and 18410722200 to J.Xiao)from the development fund for Shanghai talents(to J.Xiao)。
文摘Cardiovascular disease is the leading cause of human death worldwide. Autophagy is an evolutionarily conserved degradation pathway,which is a highly conserved cellular degradation process in which lysosomes decompose their own organelles and recycle the resulting macromolecules.Autophagy is critical in maintaining cardiovascular homeostasis and function, and excessive or insufficient autophagy or autophagic flux can lead to cardiovascular disease. Enormous evidence indicates that exercise training plays a beneficial role in the prevention and treatment of cardiovascular diseases. The regulation of autophagy during exercise is a bidirectional process. For cardiovascular disease caused by either insufficient or excessive autophagy, exercise training restores normal autophagy function and delays the progression of cardiovascular disease.An in-depth exploration and discussion of exercise-mediated regulation of autophagy in the cardiovascular system can broaden our view about the prevention of various autophagy-related diseases through exercise training. In this article, we review autophagy and its related signaling pathways,as well as autophagy-dependent beneficial effects of exercise in cardiovascular system.
基金the NSFC(22075019)National Key R&D Program of China(2017YFB1104300)。
文摘Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.
基金supported by the Educational Department o f Liaoning Province(LQN201713)Liaoning University(LDQN2019017)+1 种基金Liaoning Provincial Science and Technology Department(2020-bs-080)the Ministry of Science and Technology,Taiwan(MOST 109-2221-E-005-012)。
文摘Diabetes has become a global concern at present,among which type 2 diabetes mellitus(T2DM)accounts for approximately 90%-95%of patients.T2DM is a type of metabolic disorder syndrome that results from a genetic defect,and it is based on insulin resistance and an insulin secretion disorder.The occurrence of T2DM is usually the outcome of both genetic and environmental factors and their interactions.The etiology and pathogenesis of diabetes have not been fully elucidated,and no radical therapeutic cure has been found.Patients with T2DM suffer from complications such as the development of a chronic hyperglycemic condition and even serious metabolic disorders and organ damage in the body and depression and dementia,in addition to other chronic complications.Many studies have suggested that diet is crucial in the development of diabetes and the control of blood glucose.Natural substances have the characteristics of low toxicity and few side effects and may be key to the development of diabetic health products and preventive treatments.This paper reviews the etiology,pathogenesis,risks,treatments and diets related to T2DM to summarize the types of recently available natural products,from both local and foreign sources,for lowering blood glucose at home and their application in supplementary hypoglycemic foods.The key findings and conclusions suggest that there are various known T2DM-inducing factors,including genetic and environmental factors and three types of hybrid factors.
基金supported by National Natural Science Foundation of China(NSFC)program U19A2061Japan Science and Technology Agency(JST)CREST program JPMJCR1512,SICORP Program JPMJSC16H2 and aXis program JPMJAS2018.
文摘Fruit detection and counting are essential tasks for horticulture research.With computer vision technology development,fruit detection techniques based on deep learning have been widely used in modern orchards.However,most deep learning-based fruit detection models are generated based on fully supervised approaches,which means a model trained with one domain species may not be transferred to another.There is always a need to recreate and label the relevant training dataset,but such a procedure is time-consuming and labor-intensive.This paper proposed a domain adaptation method that can transfer an existing model trained from one domain to a new domain without extra manual labeling.The method includes three main steps:transform the source fruit image(with labeled information)into the target fruit image(without labeled information)through the CycleGAN network;Automatically label the target fruit image by a pseudo-label process;Improve the labeling accuracy by a pseudo-label self-learning approach.Use a labeled orange image dataset as the source domain,unlabeled apple and tomato image dataset as the target domain,the performance of the proposed method from the perspective of fruit detection has been evaluated.Without manual labeling for target domain image,the mean average precision reached 87.5%for apple detection and 76.9%for tomato detection,which shows that the proposed method can potentially fill the species gap in deep learning-based fruit detection.
基金supported by National Natural Science Foundation of China (No. 81874108, No. 81802607)
文摘Objective:To evaluate preoperative serum calcium concentration and investigate the association between calcium level and positive peritoneal cytology in endometrial carcinoma(EC).Methods:A total of 510 patients who were diagnosed with EC and had surgery were initially enrolled in this study at Peking University People's Hospital between January 2012 and December 2016.Clinical characteristics and preoperative serum calcium,albumin,carbohydrate antigen(CA)125,CA19-9,carcinoembryonic antigen(CEA)were extracted from patient records and evaluated according to postoperative peritoneal cytology.Predictive factors were assessed with Cox univariate and multivariate analyses.Factors selected from multivariate analysis results were used to build a predictive model.Results:A total of 510 patients are identified in our database and 444 patients who fulfilled inclusion and exclusion criteria are included in this study.Univariate analysis revealed that ionized calcium concentration was closely related to positive peritoneal cytology,tumor grade and lymph-vascular space invasion(LVSI).Moreover,peritoneal cytology was significantly associated with hypertension,tubal ligation,serum CA125,CA19-9,CEA and ionized calcium level.Multivariate analysis revealed that albumin-adjusted calcium level,CA125 and tubal ligation were independent predictive factors of positive peritoneal cytology(P<0.05).A combination of ionized calcium level with the other two indexes yielded significantly great area under the curve(AUC=0.824).Conclusions:This study enhanced the value of preoperative ionized calcium level.We also identified several potential biomarkers to predict positive peritoneal cytology in EC patients before surgery.
文摘In this manuscript,Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites was fabricated via an ultrasonic-assisted process.The activity of the as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites for photocatalytic CO_(2) reduction was studied under visible light.The as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites show a superior activity for photocatalytic CO_(2) reduction to produce CH4 and CO,with an optimum activity achieved over 0.5 Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6).The obvious superior activity observed over Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites as compared with bare Cs_(2)AgBiBr_(6) and bare Bi_(2)WO_(6) as well as a mechanical mixture of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) can be owe to the fabrication of an efficient S-scheme heterojunction,which accelerates the separation of the photogenerated charge carriers in Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) without sacrificing the high redox capability of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6).This work demonstrates that the coupling of two photocatalytic materials with staggered band alignment to form an S-scheme heterojunction is an effective strategy to develop efficient photocatalytic systems and also highlights the promising role of using lead free perovskites in photocatalysis.
文摘Geological hazard is an adverse geological condition that can cause loss of life and property.Accurate prediction and analysis of geological hazards is an important and challenging task.In the past decade,there has been a great expansion of geohazard detection data and advancement in data-driven simulation techniques.In particular,great efforts have been made in applying deep learning to predict geohazards.To understand the recent progress in this field,this paper provides an overview of the commonly used data sources and deep neural networks in the prediction of a variety of geological hazards.