Time series forecasting and analysis are widely used in many fields and application scenarios.Time series historical data reflects the change pattern and trend,which can serve the application and decision in each appl...Time series forecasting and analysis are widely used in many fields and application scenarios.Time series historical data reflects the change pattern and trend,which can serve the application and decision in each application scenario to a certain extent.In this paper,we select the time series prediction problem in the atmospheric environment scenario to start the application research.In terms of data support,we obtain the data of nearly 3500 vehicles in some cities in China fromRunwoda Research Institute,focusing on the major pollutant emission data of non-road mobile machinery and high emission vehicles in Beijing and Bozhou,Anhui Province to build the dataset and conduct the time series prediction analysis experiments on them.This paper proposes a P-gLSTNet model,and uses Autoregressive Integrated Moving Average model(ARIMA),long and short-term memory(LSTM),and Prophet to predict and compare the emissions in the future period.The experiments are validated on four public data sets and one self-collected data set,and the mean absolute error(MAE),root mean square error(RMSE),and mean absolute percentage error(MAPE)are selected as the evaluationmetrics.The experimental results show that the proposed P-gLSTNet fusion model predicts less error,outperforms the backbone method,and is more suitable for the prediction of time-series data in this scenario.展开更多
Antimony selenide(Sb_(2)Se_(3))is an emerging solar cell material.Here,we demonstrate that an organic small molecule of 4,4',4''-tris(carbazol-9-yl)-triphenylamine(TCTA)can efficiently passivate the anode ...Antimony selenide(Sb_(2)Se_(3))is an emerging solar cell material.Here,we demonstrate that an organic small molecule of 4,4',4''-tris(carbazol-9-yl)-triphenylamine(TCTA)can efficiently passivate the anode interface of the Sb_(2)Se_(3)solar cell.We fabricated the device by the vacuum thermal evaporation,and took ITO/TCTA(3.0 nm)/Sb_(2)Se_(3)(50 nm)/C60(5.0 nm)/Alq3(3.0 nm)/Al as the device architecture,where Alq3 is the tris(8-hydroxyquinolinato)aluminum.By introducing a TCTA layer,the open-circuit voltage is raised from 0.36 to 0.42 V,and the power conversion efficiency is significantly improved from 3.2%to 4.3%.The TCTA layer not only inhibits the chemical reaction between the ITO and Sb_(2)Se_(3)during the annealing process but it also blocks the electron diffusion from Sb_(2)Se_(3)to ITO anode.The enhanced performance is mainly attributed to the suppression of the charge recombination at the anode interface.展开更多
According to the production experience,the author summarizes the cultivation techniques of Qiuyue pear from orchard construction,shaping and pruning,fruit management,underground management,coping with natural disaster...According to the production experience,the author summarizes the cultivation techniques of Qiuyue pear from orchard construction,shaping and pruning,fruit management,underground management,coping with natural disasters,and pest control,in order to provide a reference for producers.展开更多
Although CoO is a promising electrode material for supercapacitors due to its high theoretical capacitance,the practical applications still suffering from inferior electrochemical activity owing to its low electrical ...Although CoO is a promising electrode material for supercapacitors due to its high theoretical capacitance,the practical applications still suffering from inferior electrochemical activity owing to its low electrical conductivity,poor structural stability and inefficient nanostructure.Herein,we report a novel Cu0/Cu+co-doped CoO composite with adjustable metallic Cu0 and ion Cu+via a facile strategy.Through interior(Cu+)and exterior(Cu0)decoration of CoO,the electrochemical performance of CoO electrode has been significantly improved due to both the beneficial flower-like nanostructure and the synergetic effect of Cu0/Cu+co-doping,which results in a significantly enhanced specific capacitance(695 F g^(-1) at 1 A g^(-1))and high cyclic stability(93.4%retention over 10,000 cycles)than pristine CoO.Furthermore,this co-doping strategy is also applicable to other transition metal oxide(NiO)with enhanced electrochemical performance.In addition,an asymmetric hybrid supercapacitor was assembled using the Cu0/Cu+co-doped CoO electrode and active carbon,which delivers a remarkable maximal energy density(35 Wh kg^(-1)),exceptional power density(16 kW kg^(-1))and ultralong cycle life(91.5%retention over 10,000 cycles).Theoretical calculations further verify that the co-doping of Cu^(0)/Cu^(+)can tune the electronic structure of CoO and improve the conductivity and electron transport.This study demonstrates a facile and favorable strategy to enhance the electrochemical performance of transition metal oxide electrode materials.展开更多
In this study,we have modeled the sputtering process of energetic He;ions colliding with W nano-fuzz materials,based on the physical processes,such as the collision and diffusion of energetic particles,sputtering and ...In this study,we have modeled the sputtering process of energetic He;ions colliding with W nano-fuzz materials,based on the physical processes,such as the collision and diffusion of energetic particles,sputtering and redeposition.Our modeling shows that the fuzzy nanomaterials with a large surface-to-volume ratio exhibit very high resistance to sputtering under fusion-relevant He;irradiations,and their sputtering yields are mainly determined by the thickness of fuzzy nano0materials,the reflection coefficients and mean free paths of energetic particles,surface sputtering yields of a flat base material,and the geometry of nano-fuzz.Our measurements have confirmed that the surface sputtering yield of a W nano-fuzz layer with the columnar geometry of nano-fuzz in cross-section is about one magnitude of order lower than the one of smooth W substrates.This work provides a complete model for energetic particles colliding with the nano-fuzz layer and clarifies the fundamental sputtering process occurring in the nano-fuzz layer.展开更多
Wormholelike mesoporous carbons(WMCs) with three different pore diameters(D_p),namely WMC-F7(D_p=8.5nm),WMC-F30(D_p=4.4nm),and WMC-FO(D_p = 3.1nm) are prepared via a modified sol-gel process.Then PtRu nanoparticles wi...Wormholelike mesoporous carbons(WMCs) with three different pore diameters(D_p),namely WMC-F7(D_p=8.5nm),WMC-F30(D_p=4.4nm),and WMC-FO(D_p = 3.1nm) are prepared via a modified sol-gel process.Then PtRu nanoparticles with the particle size(d_(Pt)) of ~3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method.It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction.PtRu/WMC-F7 with Dp > 2d_(Pt) exhibits the largest electrochemical surface area(ESA) and the highest activity toward methanol electrooxidation.With the decrease in D_p,PtRu/WMC-F30 and PtRu/WMC-FO have much lower ESA and electrochemical activity,especially for the isopropanol electrooxidation with a larger molecular size.When D_p is more than twice d_(Pt),the mass transfer of reactants and electrolyte are easier,and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced.展开更多
The effect of cerium(Ce)on the solidification microstructure of Cr_(4)Mo_(4)V bearing steel was investigated via a combined experimental and theoretical method.With a trace amount(0.056 wt%)of Ce addition,the coarse c...The effect of cerium(Ce)on the solidification microstructure of Cr_(4)Mo_(4)V bearing steel was investigated via a combined experimental and theoretical method.With a trace amount(0.056 wt%)of Ce addition,the coarse columnar grains in as-cast microstructure transform into equiaxed ones,and the average diameter is reduced from 56 to 27μm.The network-like and bulky primary MC and M2C carbides at the interdendritic regions become disconnected and refined,and their volume percentage decreases from4.15 vol%to 2.1 vol%.Ce-inclusions acting as heterogeneous nucleation agents of prior-austenite grains and Ce atoms segregating at grain boundaries,both contribute to the refinement of grains.Thermodynamic calculations reveal that primary carbides are precipitated afterγ-austenite forms near the end of the solidification process.The modification of primary carbides in size and amount is mainly attributed to the isolated remaining melt separated by refinedγ-austenite grains in which the nucleation of carbides is promoted,while the growth is restrained owing to the less segregation of alloying elements.展开更多
High-efficiency photocatalytic hydrogen evolution(PHE)relies on the development of inexpensive,stable,and efficient photocatalysts.Cadmium sulfide(CdS),as a typical binary metal sulfide,has attracted considerable rese...High-efficiency photocatalytic hydrogen evolution(PHE)relies on the development of inexpensive,stable,and efficient photocatalysts.Cadmium sulfide(CdS),as a typical binary metal sulfide,has attracted considerable research attention due to its negative conduction band position,narrow band gap for visible-light response,and strong driving force for PHE.However,the construction of CdSbased photocatalysts and the PHE rate still require improvement for practical applications.In this review,recent advances in CdS-based photocatalysts for PHE via water splitting are systematically summarized.First,the semiconductor properties of CdS,including the crystal and band structures,are briefly introduced.Afterward,the fundamental mechanisms of PHE using semiconductor photocatalysts via water splitting are discussed.Subsequently,the photoactivity of bare CdS with different morphologies and structures,CdS with cocatalyst loading,and CdS-based heterojunction photocatalysts are reviewed and discussed in detail.Finally,the challenges and prospects for exploring advanced CdS-based photocatalysts are provided.展开更多
miRNAs are important regulators of gene expression and play key roles in the development of cancer, including osteosarcoma. During the development of osteosarcoma, the expression of miR-22 is significantly downregulat...miRNAs are important regulators of gene expression and play key roles in the development of cancer, including osteosarcoma. During the development of osteosarcoma, the expression of miR-22 is significantly downregulated, making miR-22 as a promising therapeutic target against osteosarcoma. To design and fabricate efficient delivery carriers of miR-22 into osteosarcoma cells, a hydroxyl-rich reduction-responsive cationic polymeric nanoparticle, TGIC-CA (TC), was developed in this work, which also enhanced the therapeutic effects of Volasertib on osteosarcoma. TC was prepared by the ring-opening reaction between amino and epoxy groups by one-pot method, which had the good complexing ability with nucleic acids, reduction-responsive degradability and gene transfection performance. TC/miR-22 combined with volasertib could inhibit proliferation, migration and promote apoptosis of osteosarcoma cells in vitro. The anti-tumor mechanisms were revealed as TC/ miR-22 and volasertib could inhibit the PI3K/Akt signaling pathway synergistically. Furthermore, this strategy showed outstanding tumor suppression performance in animal models of orthotopic osteosarcoma, especially in patient-derived chemo-resistant and chemo-intolerant patient-derived xenograft (PDX) models, which reduced the risk of tumor lung metastasis and overcame drug resistance. Therefore, it has great potential for efficient treatment of metastasis and drug resistance of osteosarcoma by the strategy of localized, sustained delivery of miR-22 using the cationic nanocarriers combined with non-traditional chemotherapy drugs.展开更多
Lignin is the largest natural aromatic biopolymer,but usually treated as industrial biomass waste.The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of po...Lignin is the largest natural aromatic biopolymer,but usually treated as industrial biomass waste.The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of polymers.However,the weak interfacial interaction between industrial lignin and polymer induces poor compatibility and serious agglomeration in polymer owing to the strong intermolecular force of lignin.As such,it is extremely difficult to prepare high performance lignin/polymer biocomposites.Recently,we proposed the strategy of in situ construction of interfacial dynamic bonds in lignin/polymer composites.By taking advantage of the abundant oxygen-containing polar groups of lignin,we inserted dynamic bonding connection such as hydrogen bonds and coordination bonds into the interphase between lignin and the polymer matrix to improve the interfacial interactions.Meanwhile,the natural amphiphilic structure characteristics of lignin were utilized to construct the hierarchical nanophase separation structure in lignin/polymer composites.The persistent problems of poor dispersity and interfacial compatibility of lignin in the polymer matrix were effectively solved.The lignin-modified polymer composites achieved simultaneously enhanced strength and toughness.This concise review systematically summarized the recent research progress of our group toward building high-performance lignin/polymer biocomposites through the design of interfacial dynamic bonds(hydrogen bonds,coordination bonds,and dynamic covalent bonds)between lignin and different polymer systems(polar plastics,rubber,polyurethane,hydrogels,and other polymers).Finally,the future development direction,main challenges,and potential solutions of lignin application in polymers were presented.展开更多
The semantic representation of the trajectory is conducive to enrich the content oftrajectory data mining. A trajectory summarisation generation method based on themobile robot behaviour analysis was proposed to reali...The semantic representation of the trajectory is conducive to enrich the content oftrajectory data mining. A trajectory summarisation generation method based on themobile robot behaviour analysis was proposed to realize the abstract expression andsemantic representation of the spatio-temporal motion features of the robot and itsenvironmental interaction state. First, the behavioural semantic modelling and representationof the mobile robot are completed by modelling the sub-trajectory andcalculating the topological behaviour (TOP). Second, Chinese word segmentation andsemantic slot filling methods are used to combine with hierarchical clustering to performbasic word extraction and classification for describing trajectory sentences. Then, thedescription language frame is extracted based on the TOP, and the final trajectorysummarisation is generated. The result shows that the proposed method can semanticallyrepresent robot behaviours with different motion features and topological features,extract two verb-frameworks for describing the sentences according to their topologicalfeatures, and dynamically adjust the syntactic structure for the different topological behavioursbetween the target and the environment. The proposed method can generatesemantic information of relatively high quality for spatio-temporal data and help tounderstand the higher-order semantics of moving robot behaviour.展开更多
The use of non-food lignocellulosic biomass to produce ethanol fits into the strategy of a global circular economy with low dependence on fossil energy resources.Xylose is the second most abundant sugar in lignocellul...The use of non-food lignocellulosic biomass to produce ethanol fits into the strategy of a global circular economy with low dependence on fossil energy resources.Xylose is the second most abundant sugar in lignocellulosic hydrolysate,and its utilization in fermentation is a key issue in making the full use of raw plant materials for ethanol production and reduce production costs.Saccharomyces cerevisiae is the best ethanol producer but the organism is not a native xylose user.In recent years,great efforts have been made in the construction of xy-lose utilizing S.cerevisiae strains by metabolic and evolutionary engineering approaches.In addition,managing global transcriptional regulation works provides an effective means to increase the xylose utilization capacity of recombinant strains.Here we review the common strategies and research advances in the research field in order to facilitate the researches in xylose metabolism and xylose-based fermentation.展开更多
A simple method using a water soluble lignin quaternary ammonium salt (LQAS) and TiO2 has been developed for the preparation of lignin/TiO2 nanocomposites in an aqueous medium under mild conditions. The LQAS/TiO2 nano...A simple method using a water soluble lignin quaternary ammonium salt (LQAS) and TiO2 has been developed for the preparation of lignin/TiO2 nanocomposites in an aqueous medium under mild conditions. The LQAS/TiO2 nanocomposites contain well-dispersed small particles with excellent ultraviolet (UV) shielding abilities and good compatibilities with waterborne polyurethane (WPU). When the LQAS/TiO2 nanocomposites were blended with WPU, the UV absorbance and the tensile ductility of the WPU increased significantly. The composite WPU hybrid film containing 6 wt-% LQAS/TiO2 nanocomposite had the highest visible light transmittance and had excellent ultraviolet aging properties. After 192 h of UV light irradiation, the tensile strength of the composite film was above 8 MPa and the elongation at break was 800%. This work highlights new possibilities for the utilization of alkali lignin.展开更多
Semi-solid forging of iron-based alloys during solidification has unique characteristics distinct from those of the classical hot forging.With the aim of acquiring precise knowledge concerning the microstructural evol...Semi-solid forging of iron-based alloys during solidification has unique characteristics distinct from those of the classical hot forging.With the aim of acquiring precise knowledge concerning the microstructural evolution of bearing steel Cr4 Mo4 V in this process,a series of semi-solid forging experiments were carried out in which samples were wrapped in a designed pure iron sheath.The effects of forging temperature and forging reduction on the grain morphology and liquid flow behavior were investigated,respectively.By forging solidifying metal(FSM),bulky primary dendrites were broken and spheroidal grains with an average shape factor of 0.87 were obtained at 1360?C.With the decreasing forging temperature to 1340?C,the microstructural homogeneity can be improved.On the other hand,it shows that a higher forging reduction(50%)is essential for the spheroidization of grains and elimination of liquid segregation.Those microstructural characteristics are related to different motion mechanisms of solid and liquid phases at different forging temperatures.Additionally,the effect of semi-solid forging on the eutectic carbides was also investigated,and the results demonstrate that the higher diffusion capacity and less liquid segregation jointly lower the large eutectic carbides and consequently cause its uniform distribution during FSM.展开更多
Sb_2S_3 is a kind of stable light absorption materials with suitable band gap, promising for practical applications. Here we demonstrate that the engineering on the composition ratio enables significant improvement in...Sb_2S_3 is a kind of stable light absorption materials with suitable band gap, promising for practical applications. Here we demonstrate that the engineering on the composition ratio enables significant improvement in the device performance. We found that the co-evaporation of sulfur or antimony with Sb_2S_3 is able to generate sulfur-or antimony-rich Sb_2S_3. This composition does not generate essential influence on the crystal structure, optical band and film formability, while the carrier concentration and transport dynamics are considerably changed. The device investigations show that sulfur-rich Sb_2S_3 film is favorable for efficient energy conversion, while antimony-rich Sb_2S_3 leads to greatly decreased device performance. With optimizations on the sulfur-rich Sb_2S_3 films, the final power conversion efficiency reaches5.8%, which is the highest efficiency in thermal evaporation derived Sb_2S_3 solar cells.展开更多
Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in el...Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting(MC-ESR)process.A transient 2 D numerical model was also built to verify the experimental results and proposed mechanisms.The number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF,while remained almost the same in electrode matrix and MZ.The inclusions in LMF migrated from edge to mid region of LMF,accompanied with removal process.In addition,the kinetic conditions for inclusion migrating to LMF/slag interface(LSI)were enhanced during MC-ESR process,thereby improving the inclusion removal efficiency in LMF.This work highlights the 3 D characterization and motion/removal mechanisms of inclusions in electrode tip,as well as sheds new light on preparing high purity materials.展开更多
Metabolic engineering to produce tricarboxylic acid(TCA)cycle-derived chemicals is usually associated with problems of low production yield and impaired cellular metabolism.In this work,we found that fatty acid(FA)fee...Metabolic engineering to produce tricarboxylic acid(TCA)cycle-derived chemicals is usually associated with problems of low production yield and impaired cellular metabolism.In this work,we found that fatty acid(FA)feedstocks could enable high-yield production of TCA cycle-derived chemicals,while maintaining an efficient and balanced metabolic flux of the glyoxylate-TCA cycle,which is favorable for both product synthesis and cell growth.Here,we designed a novel synthetic pathway for production of β-alanine,an important TCA cycle-derived product,from FAs with a high theortecial yield of 1.391 g/g.By introducing panD,improving aspA,and knocking out iclR,glyoxylate shunt was highly activated in FAs and the yield of β-alanine reached 0.71 g/g from FAs,much higher than from glucose.Blocking the TCA cycle at icd/sucA/fumAC nodes could increase β-alanine yield in a flask cultivation,but severely reduced cell growth and FA utilization during fed-batch processes.Replenishing oxaloacetate by knocking out aspC and recovering fumAC could restore the growth and lead to a titer of 35.57 g/l.After relieving the oxidative stress caused by FA metabolism,β-alanine production could reach 72.05 g/l with a maximum yield of 1.24 g/g,about 86% of the theoretical yield.Our study thus provides a promising strategy for the production of TCA cycle-derived chemicals.展开更多
A template-free carbonization-activation route is developed to fabricate sub-nanopore-containing porous carbon by using a novel polypyrrole(PPy)hydrogel as a precursor.This design of PPy hydrogel precursor containing ...A template-free carbonization-activation route is developed to fabricate sub-nanopore-containing porous carbon by using a novel polypyrrole(PPy)hydrogel as a precursor.This design of PPy hydrogel precursor containing molecular-scale grids(diameter~2.0 nm)allows for homogeneous N,O-codoping into the porous carbon scaffold during the pyrolysis process.A subsequent activation step produces activated porous carbons(APCs)with tailored pore structures,which renders the APCs abundant subnanopores on their surface to increase the specific capacitance as extra capacitance sites.Coupled with large specific surface area and abundant heteroatoms,the optimized APC4/1 displays excellent specific capacitance of 379 F/g for liquid-state supercapacitor and 230 F/g for solid-state supercapacitor.The solid-state supercapacitor shows a high energy density of 22.99 Wh/kg at power density of 420 W/kg,which is higher than most reported porous carbon materials and satisfy the urgent requirements of elementary power source for electric vehicles.Moreover,this method can be easily modified to fabricate sub-nanopore-containing porous carbons with preferred structures and compositions for many applications.展开更多
基金the Beijing Chaoyang District Collaborative Innovation Project(No.CYXT2013)the subject support of Beijing Municipal Science and Technology Key R&D Program-Capital Blue Sky Action Cultivation Project(Z19110900910000)+1 种基金“Research and Demonstration ofHigh Emission Vehicle Monitoring Equipment System Based on Sensor Integration Technology”(Z19110000911003)This work was supported by the Academic Research Projects of Beijing Union University(No.ZK80202103).
文摘Time series forecasting and analysis are widely used in many fields and application scenarios.Time series historical data reflects the change pattern and trend,which can serve the application and decision in each application scenario to a certain extent.In this paper,we select the time series prediction problem in the atmospheric environment scenario to start the application research.In terms of data support,we obtain the data of nearly 3500 vehicles in some cities in China fromRunwoda Research Institute,focusing on the major pollutant emission data of non-road mobile machinery and high emission vehicles in Beijing and Bozhou,Anhui Province to build the dataset and conduct the time series prediction analysis experiments on them.This paper proposes a P-gLSTNet model,and uses Autoregressive Integrated Moving Average model(ARIMA),long and short-term memory(LSTM),and Prophet to predict and compare the emissions in the future period.The experiments are validated on four public data sets and one self-collected data set,and the mean absolute error(MAE),root mean square error(RMSE),and mean absolute percentage error(MAPE)are selected as the evaluationmetrics.The experimental results show that the proposed P-gLSTNet fusion model predicts less error,outperforms the backbone method,and is more suitable for the prediction of time-series data in this scenario.
基金This work was supported by the High Level Talents Project Fund of Hainan Basic and Applied Research Program(NATURAL SCIENCE)(Grant No.2019RC118).
文摘Antimony selenide(Sb_(2)Se_(3))is an emerging solar cell material.Here,we demonstrate that an organic small molecule of 4,4',4''-tris(carbazol-9-yl)-triphenylamine(TCTA)can efficiently passivate the anode interface of the Sb_(2)Se_(3)solar cell.We fabricated the device by the vacuum thermal evaporation,and took ITO/TCTA(3.0 nm)/Sb_(2)Se_(3)(50 nm)/C60(5.0 nm)/Alq3(3.0 nm)/Al as the device architecture,where Alq3 is the tris(8-hydroxyquinolinato)aluminum.By introducing a TCTA layer,the open-circuit voltage is raised from 0.36 to 0.42 V,and the power conversion efficiency is significantly improved from 3.2%to 4.3%.The TCTA layer not only inhibits the chemical reaction between the ITO and Sb_(2)Se_(3)during the annealing process but it also blocks the electron diffusion from Sb_(2)Se_(3)to ITO anode.The enhanced performance is mainly attributed to the suppression of the charge recombination at the anode interface.
文摘According to the production experience,the author summarizes the cultivation techniques of Qiuyue pear from orchard construction,shaping and pruning,fruit management,underground management,coping with natural disasters,and pest control,in order to provide a reference for producers.
基金financially supported by the National Science Foundation of China(Grant No.11804106)。
文摘Although CoO is a promising electrode material for supercapacitors due to its high theoretical capacitance,the practical applications still suffering from inferior electrochemical activity owing to its low electrical conductivity,poor structural stability and inefficient nanostructure.Herein,we report a novel Cu0/Cu+co-doped CoO composite with adjustable metallic Cu0 and ion Cu+via a facile strategy.Through interior(Cu+)and exterior(Cu0)decoration of CoO,the electrochemical performance of CoO electrode has been significantly improved due to both the beneficial flower-like nanostructure and the synergetic effect of Cu0/Cu+co-doping,which results in a significantly enhanced specific capacitance(695 F g^(-1) at 1 A g^(-1))and high cyclic stability(93.4%retention over 10,000 cycles)than pristine CoO.Furthermore,this co-doping strategy is also applicable to other transition metal oxide(NiO)with enhanced electrochemical performance.In addition,an asymmetric hybrid supercapacitor was assembled using the Cu0/Cu+co-doped CoO electrode and active carbon,which delivers a remarkable maximal energy density(35 Wh kg^(-1)),exceptional power density(16 kW kg^(-1))and ultralong cycle life(91.5%retention over 10,000 cycles).Theoretical calculations further verify that the co-doping of Cu^(0)/Cu^(+)can tune the electronic structure of CoO and improve the conductivity and electron transport.This study demonstrates a facile and favorable strategy to enhance the electrochemical performance of transition metal oxide electrode materials.
基金supported by the National Key R&D Program of China(No.2017YFE0300106)National Natural Science Foundation of China(No.11320101005)+1 种基金Liaoning Provincial Natural Science Foundation(Nos.20180510006,2019-ZD0186)Natural Science Basis Research Program of Shanxi Province(No.2020GY-268)。
文摘In this study,we have modeled the sputtering process of energetic He;ions colliding with W nano-fuzz materials,based on the physical processes,such as the collision and diffusion of energetic particles,sputtering and redeposition.Our modeling shows that the fuzzy nanomaterials with a large surface-to-volume ratio exhibit very high resistance to sputtering under fusion-relevant He;irradiations,and their sputtering yields are mainly determined by the thickness of fuzzy nano0materials,the reflection coefficients and mean free paths of energetic particles,surface sputtering yields of a flat base material,and the geometry of nano-fuzz.Our measurements have confirmed that the surface sputtering yield of a W nano-fuzz layer with the columnar geometry of nano-fuzz in cross-section is about one magnitude of order lower than the one of smooth W substrates.This work provides a complete model for energetic particles colliding with the nano-fuzz layer and clarifies the fundamental sputtering process occurring in the nano-fuzz layer.
基金supported by the National Natural Science Foundation of China (no. 91434106)
文摘Wormholelike mesoporous carbons(WMCs) with three different pore diameters(D_p),namely WMC-F7(D_p=8.5nm),WMC-F30(D_p=4.4nm),and WMC-FO(D_p = 3.1nm) are prepared via a modified sol-gel process.Then PtRu nanoparticles with the particle size(d_(Pt)) of ~3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method.It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction.PtRu/WMC-F7 with Dp > 2d_(Pt) exhibits the largest electrochemical surface area(ESA) and the highest activity toward methanol electrooxidation.With the decrease in D_p,PtRu/WMC-F30 and PtRu/WMC-FO have much lower ESA and electrochemical activity,especially for the isopropanol electrooxidation with a larger molecular size.When D_p is more than twice d_(Pt),the mass transfer of reactants and electrolyte are easier,and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced.
基金Project supported by the National Natural Science Foundation of China(52031013,52173305,52233017)the National Key Research and Development Program(2018YFA0702900)。
文摘The effect of cerium(Ce)on the solidification microstructure of Cr_(4)Mo_(4)V bearing steel was investigated via a combined experimental and theoretical method.With a trace amount(0.056 wt%)of Ce addition,the coarse columnar grains in as-cast microstructure transform into equiaxed ones,and the average diameter is reduced from 56 to 27μm.The network-like and bulky primary MC and M2C carbides at the interdendritic regions become disconnected and refined,and their volume percentage decreases from4.15 vol%to 2.1 vol%.Ce-inclusions acting as heterogeneous nucleation agents of prior-austenite grains and Ce atoms segregating at grain boundaries,both contribute to the refinement of grains.Thermodynamic calculations reveal that primary carbides are precipitated afterγ-austenite forms near the end of the solidification process.The modification of primary carbides in size and amount is mainly attributed to the isolated remaining melt separated by refinedγ-austenite grains in which the nucleation of carbides is promoted,while the growth is restrained owing to the less segregation of alloying elements.
基金the Natural Science Foundation of Hainan Province(grant no.521RC495)the National Natural Science Foundation of China(grant nos.22109034,22109035,52164028,and 62105083)+1 种基金the Foundation of State Key Laboratory of Marine Resource Utilization in South China Sea(Hainan University,grant no.MRUKF2021029)the Start-up Research Foundation of Hainan University(grant nos.KYQD(ZR)-20008,20082,20083,20084,21065,21124,and 21125).
文摘High-efficiency photocatalytic hydrogen evolution(PHE)relies on the development of inexpensive,stable,and efficient photocatalysts.Cadmium sulfide(CdS),as a typical binary metal sulfide,has attracted considerable research attention due to its negative conduction band position,narrow band gap for visible-light response,and strong driving force for PHE.However,the construction of CdSbased photocatalysts and the PHE rate still require improvement for practical applications.In this review,recent advances in CdS-based photocatalysts for PHE via water splitting are systematically summarized.First,the semiconductor properties of CdS,including the crystal and band structures,are briefly introduced.Afterward,the fundamental mechanisms of PHE using semiconductor photocatalysts via water splitting are discussed.Subsequently,the photoactivity of bare CdS with different morphologies and structures,CdS with cocatalyst loading,and CdS-based heterojunction photocatalysts are reviewed and discussed in detail.Finally,the challenges and prospects for exploring advanced CdS-based photocatalysts are provided.
基金supported by National Natural Science Foundation of China(Grant Nos.51973021,52221006,52173275,51932002 and 51903013)Beijing Municipal Health Commission(BJRITO-RDP-2023,PXM 2020_026275_000002 and BMHC-2021-6)+2 种基金National Key Research and Development Program(Grant No.2021YFC2400500)Beijing Jishuitan Hospital Nova Program(Grant Nos.XKXX202115 and XKXX202114)Beijing Outstanding Young Scientist Program(Grant No.BJJWZYJH01201910010024).
文摘miRNAs are important regulators of gene expression and play key roles in the development of cancer, including osteosarcoma. During the development of osteosarcoma, the expression of miR-22 is significantly downregulated, making miR-22 as a promising therapeutic target against osteosarcoma. To design and fabricate efficient delivery carriers of miR-22 into osteosarcoma cells, a hydroxyl-rich reduction-responsive cationic polymeric nanoparticle, TGIC-CA (TC), was developed in this work, which also enhanced the therapeutic effects of Volasertib on osteosarcoma. TC was prepared by the ring-opening reaction between amino and epoxy groups by one-pot method, which had the good complexing ability with nucleic acids, reduction-responsive degradability and gene transfection performance. TC/miR-22 combined with volasertib could inhibit proliferation, migration and promote apoptosis of osteosarcoma cells in vitro. The anti-tumor mechanisms were revealed as TC/ miR-22 and volasertib could inhibit the PI3K/Akt signaling pathway synergistically. Furthermore, this strategy showed outstanding tumor suppression performance in animal models of orthotopic osteosarcoma, especially in patient-derived chemo-resistant and chemo-intolerant patient-derived xenograft (PDX) models, which reduced the risk of tumor lung metastasis and overcame drug resistance. Therefore, it has great potential for efficient treatment of metastasis and drug resistance of osteosarcoma by the strategy of localized, sustained delivery of miR-22 using the cationic nanocarriers combined with non-traditional chemotherapy drugs.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.22222805,22038004,and 22078116)Guangdong Provincial Key Research and Development Program(Grant No.2020B1111380002)Natural Science Foundation of Guangdong Province(Grant No.2021A1515010121).
文摘Lignin is the largest natural aromatic biopolymer,but usually treated as industrial biomass waste.The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of polymers.However,the weak interfacial interaction between industrial lignin and polymer induces poor compatibility and serious agglomeration in polymer owing to the strong intermolecular force of lignin.As such,it is extremely difficult to prepare high performance lignin/polymer biocomposites.Recently,we proposed the strategy of in situ construction of interfacial dynamic bonds in lignin/polymer composites.By taking advantage of the abundant oxygen-containing polar groups of lignin,we inserted dynamic bonding connection such as hydrogen bonds and coordination bonds into the interphase between lignin and the polymer matrix to improve the interfacial interactions.Meanwhile,the natural amphiphilic structure characteristics of lignin were utilized to construct the hierarchical nanophase separation structure in lignin/polymer composites.The persistent problems of poor dispersity and interfacial compatibility of lignin in the polymer matrix were effectively solved.The lignin-modified polymer composites achieved simultaneously enhanced strength and toughness.This concise review systematically summarized the recent research progress of our group toward building high-performance lignin/polymer biocomposites through the design of interfacial dynamic bonds(hydrogen bonds,coordination bonds,and dynamic covalent bonds)between lignin and different polymer systems(polar plastics,rubber,polyurethane,hydrogels,and other polymers).Finally,the future development direction,main challenges,and potential solutions of lignin application in polymers were presented.
基金supported in part by the NSFC(No.61771177,U1934211)Shaanxi Province Key Research and Development Program(No.2021GY-087).
文摘The semantic representation of the trajectory is conducive to enrich the content oftrajectory data mining. A trajectory summarisation generation method based on themobile robot behaviour analysis was proposed to realize the abstract expression andsemantic representation of the spatio-temporal motion features of the robot and itsenvironmental interaction state. First, the behavioural semantic modelling and representationof the mobile robot are completed by modelling the sub-trajectory andcalculating the topological behaviour (TOP). Second, Chinese word segmentation andsemantic slot filling methods are used to combine with hierarchical clustering to performbasic word extraction and classification for describing trajectory sentences. Then, thedescription language frame is extracted based on the TOP, and the final trajectorysummarisation is generated. The result shows that the proposed method can semanticallyrepresent robot behaviours with different motion features and topological features,extract two verb-frameworks for describing the sentences according to their topologicalfeatures, and dynamically adjust the syntactic structure for the different topological behavioursbetween the target and the environment. The proposed method can generatesemantic information of relatively high quality for spatio-temporal data and help tounderstand the higher-order semantics of moving robot behaviour.
基金supported by the National Key Research and Develop-ment Program of China(2021YFC2101303)the National Natural Science Foundation of China(32170039).
文摘The use of non-food lignocellulosic biomass to produce ethanol fits into the strategy of a global circular economy with low dependence on fossil energy resources.Xylose is the second most abundant sugar in lignocellulosic hydrolysate,and its utilization in fermentation is a key issue in making the full use of raw plant materials for ethanol production and reduce production costs.Saccharomyces cerevisiae is the best ethanol producer but the organism is not a native xylose user.In recent years,great efforts have been made in the construction of xy-lose utilizing S.cerevisiae strains by metabolic and evolutionary engineering approaches.In addition,managing global transcriptional regulation works provides an effective means to increase the xylose utilization capacity of recombinant strains.Here we review the common strategies and research advances in the research field in order to facilitate the researches in xylose metabolism and xylose-based fermentation.
基金the National Natural Science Foundation of China (Grant Nos. 21436004 and 21706082)the Science and Technology Program of Guangzhou (201707020025)+1 种基金the Fundamental Research Funds for the Central Universities (D2174110)Guangdong Province Science Foundation for Cultivating National Engineering Research Center for Efficient Utilization of Plant Fibers (2017B090903003) for the financial support.
文摘A simple method using a water soluble lignin quaternary ammonium salt (LQAS) and TiO2 has been developed for the preparation of lignin/TiO2 nanocomposites in an aqueous medium under mild conditions. The LQAS/TiO2 nanocomposites contain well-dispersed small particles with excellent ultraviolet (UV) shielding abilities and good compatibilities with waterborne polyurethane (WPU). When the LQAS/TiO2 nanocomposites were blended with WPU, the UV absorbance and the tensile ductility of the WPU increased significantly. The composite WPU hybrid film containing 6 wt-% LQAS/TiO2 nanocomposite had the highest visible light transmittance and had excellent ultraviolet aging properties. After 192 h of UV light irradiation, the tensile strength of the composite film was above 8 MPa and the elongation at break was 800%. This work highlights new possibilities for the utilization of alkali lignin.
基金supported financially by the National Key Research and Development Program(No.2018YFA0702900)the National Natural Science Foundation of China(Nos.U1508215,51774265 and 51701225)+3 种基金the National Science and Technology Major Project of China(No.2019ZX06004010)the Key Program of the Chinese Academy of Sciences(No.ZDRW-CN-2017-1)the Program of CAS Interdisciplinary Innovation TeamGleeble engineer Jiajun He for her technical support in superhot experiments.
文摘Semi-solid forging of iron-based alloys during solidification has unique characteristics distinct from those of the classical hot forging.With the aim of acquiring precise knowledge concerning the microstructural evolution of bearing steel Cr4 Mo4 V in this process,a series of semi-solid forging experiments were carried out in which samples were wrapped in a designed pure iron sheath.The effects of forging temperature and forging reduction on the grain morphology and liquid flow behavior were investigated,respectively.By forging solidifying metal(FSM),bulky primary dendrites were broken and spheroidal grains with an average shape factor of 0.87 were obtained at 1360?C.With the decreasing forging temperature to 1340?C,the microstructural homogeneity can be improved.On the other hand,it shows that a higher forging reduction(50%)is essential for the spheroidization of grains and elimination of liquid segregation.Those microstructural characteristics are related to different motion mechanisms of solid and liquid phases at different forging temperatures.Additionally,the effect of semi-solid forging on the eutectic carbides was also investigated,and the results demonstrate that the higher diffusion capacity and less liquid segregation jointly lower the large eutectic carbides and consequently cause its uniform distribution during FSM.
基金supported by the Fundamental Research Funds for the Central Universities(WK2060140023,CX3430000001,and WK2060140024)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(2016FXZY003)the National Natural Science Foundation of China(U1732150)
文摘Sb_2S_3 is a kind of stable light absorption materials with suitable band gap, promising for practical applications. Here we demonstrate that the engineering on the composition ratio enables significant improvement in the device performance. We found that the co-evaporation of sulfur or antimony with Sb_2S_3 is able to generate sulfur-or antimony-rich Sb_2S_3. This composition does not generate essential influence on the crystal structure, optical band and film formability, while the carrier concentration and transport dynamics are considerably changed. The device investigations show that sulfur-rich Sb_2S_3 film is favorable for efficient energy conversion, while antimony-rich Sb_2S_3 leads to greatly decreased device performance. With optimizations on the sulfur-rich Sb_2S_3 films, the final power conversion efficiency reaches5.8%, which is the highest efficiency in thermal evaporation derived Sb_2S_3 solar cells.
基金the financial support of the National Key Research and Development Program of China(Nos.2016YFB0300401,2018YFF0109404 and 2016YFB0301401)the National Natural Science Foundation of China(Nos.U1860202,U1732276,50134010,51704193,51904184 and 52004156)+1 种基金the Science and Technology Commission of Shanghai Municipality(Nos.13JC14025000 and 15520711000)the China Postdoctoral Science Foundation(No.2020M671072)。
文摘Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting(MC-ESR)process.A transient 2 D numerical model was also built to verify the experimental results and proposed mechanisms.The number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF,while remained almost the same in electrode matrix and MZ.The inclusions in LMF migrated from edge to mid region of LMF,accompanied with removal process.In addition,the kinetic conditions for inclusion migrating to LMF/slag interface(LSI)were enhanced during MC-ESR process,thereby improving the inclusion removal efficiency in LMF.This work highlights the 3 D characterization and motion/removal mechanisms of inclusions in electrode tip,as well as sheds new light on preparing high purity materials.
基金National Key Research and Development Project of China(Grant No.2018YFA0901400)National Natural Science Foundation of China(Grant No.32070068).
文摘Metabolic engineering to produce tricarboxylic acid(TCA)cycle-derived chemicals is usually associated with problems of low production yield and impaired cellular metabolism.In this work,we found that fatty acid(FA)feedstocks could enable high-yield production of TCA cycle-derived chemicals,while maintaining an efficient and balanced metabolic flux of the glyoxylate-TCA cycle,which is favorable for both product synthesis and cell growth.Here,we designed a novel synthetic pathway for production of β-alanine,an important TCA cycle-derived product,from FAs with a high theortecial yield of 1.391 g/g.By introducing panD,improving aspA,and knocking out iclR,glyoxylate shunt was highly activated in FAs and the yield of β-alanine reached 0.71 g/g from FAs,much higher than from glucose.Blocking the TCA cycle at icd/sucA/fumAC nodes could increase β-alanine yield in a flask cultivation,but severely reduced cell growth and FA utilization during fed-batch processes.Replenishing oxaloacetate by knocking out aspC and recovering fumAC could restore the growth and lead to a titer of 35.57 g/l.After relieving the oxidative stress caused by FA metabolism,β-alanine production could reach 72.05 g/l with a maximum yield of 1.24 g/g,about 86% of the theoretical yield.Our study thus provides a promising strategy for the production of TCA cycle-derived chemicals.
基金financial support from National Natural Science Foundation of China(Nos.51902222,51603142,U1610255)Key Laboratory of Yarn Materials Forming and Composite Processing Technology,Zhejiang Province(No.MTC2019-03)+2 种基金Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Nos.2019L0164 and 2019L0255)the Shanxi Provincial Key Innovative Research Team in Science and Technology(Nos.2015013002-10 and 201605D131045-10)Key R&D Program of Shanxi Province(International Cooperation,No.201903D421077)。
文摘A template-free carbonization-activation route is developed to fabricate sub-nanopore-containing porous carbon by using a novel polypyrrole(PPy)hydrogel as a precursor.This design of PPy hydrogel precursor containing molecular-scale grids(diameter~2.0 nm)allows for homogeneous N,O-codoping into the porous carbon scaffold during the pyrolysis process.A subsequent activation step produces activated porous carbons(APCs)with tailored pore structures,which renders the APCs abundant subnanopores on their surface to increase the specific capacitance as extra capacitance sites.Coupled with large specific surface area and abundant heteroatoms,the optimized APC4/1 displays excellent specific capacitance of 379 F/g for liquid-state supercapacitor and 230 F/g for solid-state supercapacitor.The solid-state supercapacitor shows a high energy density of 22.99 Wh/kg at power density of 420 W/kg,which is higher than most reported porous carbon materials and satisfy the urgent requirements of elementary power source for electric vehicles.Moreover,this method can be easily modified to fabricate sub-nanopore-containing porous carbons with preferred structures and compositions for many applications.
