Background Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries.However,there are several inherent limitations.In this study,a novel biomedical porous ...Background Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries.However,there are several inherent limitations.In this study,a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility.Methods Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant.Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility.Twenty-four rabbits were performed discectomy only (control group),discectomy with autologous bone implanted (autograft group),and discectomy with porous tantalum implanted (tantalum group) at 3 levels:L3–L4,L4–L5,and L5–L6 in random order.All the 24 rabbits were randomly sacrificed at the different post-operative times (2,4,6,and 12 months;n = 6 at each time point).Histologic examination and micro-computed tomography scans were done to evaluate the fusion process.Comparison of fusion index scores between groups was analyzed using one-way analysis of variance.Other comparisons of numerical variables between groups were made by Student t test.Results All rabbits survived and recovered without any symptoms of nerve injury.Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ± 0.32 vs.2.83 ± 0.38, F= 244.60, P = 0.709).Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ± 0.06 vs.1.23 ± 0.04, t = –0.644, P = 0.545),which indicated the BMSC proliferation without toxicity.SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant.No implant degradation,wear debris,or osteolysis was observed.Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces.Conclusion This novel porous tantal展开更多
The application of ensemble learning models has been continuously improved in recent landslide susceptibility research,but most studies have no unified ensemble framework.Moreover,few papers have discussed the applica...The application of ensemble learning models has been continuously improved in recent landslide susceptibility research,but most studies have no unified ensemble framework.Moreover,few papers have discussed the applicability of the ensemble learning model in landslide susceptibility mapping at the township level.This study aims at defining a robust ensemble framework that can become the benchmark method for future research dealing with the comparison of different ensemble models.For this purpose,the present work focuses on three different basic classifiers:decision tree(DT),support vector machine(SVM),and multi-layer perceptron neural network model(MLPNN)and two homogeneous ensemble models such as random forest(RF)and extreme gradient boosting(XGBoost).The hierarchical construction of deep ensemble relied on two leading ensemble technologies(i.e.,homogeneous/heterogeneous model ensemble and bagging,boosting,stacking ensemble strategy)to provide a more accurate and effective spatial probability of landslide occurrence.The selected study area is Dazhou town,located in the Jurassic red-strata area in the Three Gorges Reservoir Area of China,which is a strategic economic area currently characterized by widespread landslide risk.Based on a long-term field investigation,the inventory counting thirty-three slow-moving landslide polygons was drawn.The results show that the ensemble models do not necessarily perform better;for instance,the Bagging based DT-SVM-MLPNNXGBoost model performed worse than the single XGBoost model.Amongst the eleven tested models,the Stacking based RF-XGBoost model,which is a homogeneous model based on bagging,boosting,and stacking ensemble,showed the highest capability of predicting the landslide-affected areas.Besides,the factor behaviors of DT,SVM,MLPNN,RF and XGBoost models reflected the characteristics of slow-moving landslides in the Three Gorges reservoir area,wherein unfavorable lithological conditions and intense human engineering activities(i.e.,reservoir water level fluctuation,residen展开更多
With the development of green data centers,a large number of Uninterruptible Power Supply(UPS)resources in Internet Data Center(IDC)are becoming idle assets owing to their low utilization rate.The revitalization of th...With the development of green data centers,a large number of Uninterruptible Power Supply(UPS)resources in Internet Data Center(IDC)are becoming idle assets owing to their low utilization rate.The revitalization of these idle UPS resources is an urgent problem that must be addressed.Based on the energy storage type of the UPS(EUPS)and using renewable sources,a solution for IDCs is proposed in this study.Subsequently,an EUPS cluster classification method based on the concept of shared mechanism niche(CSMN)was proposed to effectively solve the EUPS control problem.Accordingly,the classified EUPS aggregation unit was used to determine the optimal operation of the IDC.An IDC cost minimization optimization model was established,and the Quantum Particle Swarm Optimization(QPSO)algorithm was adopted.Finally,the economy and effectiveness of the three-tier optimization framework and model were verified through three case studies.展开更多
Revealing the molecular packing,intermolecular interactions,and aggregation behaviors in the nanocrystalline bulk heterojunction(BHJ)domains undertake the tasks for future materials design for efficient solar cells,es...Revealing the molecular packing,intermolecular interactions,and aggregation behaviors in the nanocrystalline bulk heterojunction(BHJ)domains undertake the tasks for future materials design for efficient solar cells,especially in understanding the structure–property relationship of isomeric non-fullerene acceptors(NFAs).Theoretical calculations reveal that 2ClIC-βδ,withβ-andδ-chlorine-substituted terminal groups,achieves a relatively higher dipole moment for enhanced intermolecular interactions.More importantly,when comparing the single-crystal X-ray diffraction patterns of three isomeric NFAs,BTIC-BO4Cl-βδ,BTIC-BO4Cl-βγ,and BTIC-BO4Cl,the synergistic effect of chlorine atoms at theβ-andδ-positions endows BTIC-BO4Cl-βδbetter molecular planarity with a dihedral angle of 1.14°.In turn,this creates the shortestπ∙∙∙πdistance(3.28Å)and smallest binding energies(−51.66 kcal mol^(−1))of the three NFAs,resulting in the tightest three-dimensional network packing structure with a framework of L_(x)=14.0Åand L_(y)=13.6Å.Such a structure has multiple intermolecular interactions for better charge transfer.However,the chlorine atomat theγ-position in the other two isomers contributes to non-intermolecular interactions with subordinate packing arrangements.Subsequently,the red-shifted UV-absorption and higher electron mobility observed in neat films of BTIC-BO4Cl-βδagree well with its more ordered crystallinity.This leads to a more suitable fiber-like phase separation in the corresponding active blend,ultimately improving the device performance with superior charge transport.As a result,the highest power conversion efficiency of 17.04%with a current density of 26.07 mA cm^(−2)was obtained with the BTIC-BO4Cl-βδ-based device.The carrier dynamics test and grazing incidence wide-angle X-ray scattering measurement indicate that the packing arrangement of molecules in the nanocrystalline BHJ domains is consistent with their crystallinity.This work investigates the structure–property differences 展开更多
Extracting uranium from seawater offers opportunities for sustainable nuclear fuel supply,but the task is quite challenging due to the low uranium concentration(~3 ppb)in seawater.Here,based on the Knoevenagel condens...Extracting uranium from seawater offers opportunities for sustainable nuclear fuel supply,but the task is quite challenging due to the low uranium concentration(~3 ppb)in seawater.Here,based on the Knoevenagel condensation reaction of aldehyde and acetonitrile groups,a novel stable sp^(2)carbon-linked three-dimensional covalent organic framework(3D COF),TFPM-PDANAO was prepared as a porous platform for uranium extraction from seawater.The TFPM-PDAN-AO designed with regular 3D pore channel of 7.12 A provides a specific channel for uranyl diffusion,which exhibits high selectivity and fast kinetics for uranium adsorption.Meanwhile,the superior stability and optoelectronic properties enable it an excellent porous platform for uranium electroextraction.By applying alternating voltages between-5 and 0 V,uranyl ions can rapidly migrate and enrich into the porous structure of TFPM-PDAN-AO,then inducing the electrodeposition of uranium compounds to form the charge neutral species(Na_(2)O(UO_(3)H_(2)O)x)with an unprecedentedly high adsorption capacity of 4,685 mg g^(-1).This work not only expands the application prospects of functionalized 3D COFs,but also provides a technical support for the electrodeposition adsorption of uranium from seawater.展开更多
Si materials are widely considered to be the next-generation anode to replace the current commercial graphite-based anode due to its high energy density.However,the large volume variation of silicon during(de)lithiati...Si materials are widely considered to be the next-generation anode to replace the current commercial graphite-based anode due to its high energy density.However,the large volume variation of silicon during(de)lithiation process leads to rapid capacity decay,hindering its commercial application.Although the various hollow structure designs of Si nanomaterials have improved their cycling stability in the laboratory,the high-pressure calendering process in the current industrial electrode preparation process might collapse the hollow structure and weaken the structural advantages of hollow silicon anode materials.In this work,a silicon carbon composite material(Si@3DC)in which Si nanoparticles were anchored on a three-dimensional carbon framework through carbon films was prepared by a simple proton exchange method.The three-dimensional carbon framework with multiple hierarchical pores of Si@3DC was compatible with the high-pressure calendering process,but also could provide expansion space for Si nanoparticles during the lithiation process,and ensure good electronic and ionic conductivity.The carbon film on the surface of Si nanoparticles promoted the formation of stable solid electrolyte interphase(SEI)films,ensuring the good cycle stability of Si@3DC.展开更多
The analysis of the current big data policy for scientific research can promote the ecological optimization of big data policy,and is a positive response to the national big data strategy.This paper constructs a“dual...The analysis of the current big data policy for scientific research can promote the ecological optimization of big data policy,and is a positive response to the national big data strategy.This paper constructs a“dual three-dimensional framework”to analyze the central and local science data policies from 2013 to 2022.With the dissemination and popularization of the concept of scientific data sharing,policies and regulations related to scientific data management have been issued,which promotes the emergence of scientific data policy ecology.The scientific data policy ecology is a complex and multicollaborative dynamic system composed of policy text,policy environment and related personnel,the core of which lies in the policy itself,aiming to ensure the security of scientific data and promote the development of science.There are the following problems in the scientific data policy ecology:In terms of policy text,the policy effectiveness is low and the use of policy tools is uneven.In terms of relevant personnel,the cooperation network density among various subjects is low and there is a lack of highquality talents.In terms of policy environment,there is an imbalance of regional funding support.It also puts forward some optimization strategies,such as strengthening the systematization of policy texts,improving the degree of coordination of policy subjects to form a long-term cooperation network,and improving the degree of compatibility between environment,personnel and policies.展开更多
A high-efficiency electro-thermal heater requires simultaneously high electrical and thermal conductivities to generate and dissipate Joule heat efficiently.A low in put voltage is essential to en sure the heaters saf...A high-efficiency electro-thermal heater requires simultaneously high electrical and thermal conductivities to generate and dissipate Joule heat efficiently.A low in put voltage is essential to en sure the heaters safe applications.However,the low voltage gen erally leads to low saturated temperature and heati ng rate and hence a low thermal efficie ncy.How to reduce the in put voltage while maintai ning a high electro-thermal efficiency is still a challenge.Herein,a highly electrical and thermal conductive film was 8nstructed using a graphene-based composite which has an internal three-dimensional(3D)conductive network.In the 3D framework,cellulose nanocrystalline(CNC)phase with chiral liquid crystal manner presents in the form of alig ned helix betwee n the graphe ne oxide(GO)layers.Carbon nano dots(CDs)are assembled泊side the composite as con ductive nano fillers.Subseque nt an neali ng and compressi on results in the formati on of the assembled GO-CNC-CDs film.The carb on ized CNC nano rods(CNR)with the helical alignment act as irrplane and through-pla ne conn ecti ons of n eighbori ng reduced GO(rGO)nano sheets,forming a con ductive network in the composite film.The CDs with ultrafast electr ons tran sfer rates provide additi onal electro ns and phonons tran sport paths for the composite.As a result,the obtai ned graphe ne?based composite film(rGO-CNR-CDs)exhibited a high thermal conductivity of 1,978.6 W m^-1·K^-1 and electrical conductivity of 2,053.4 S·cm^-1,respectively.The composite film showed an outstanding electro-thermal heating efficiency with the saturated temperature of 315℃and maximum heating rate of 44.9℃·s^-1 at a very low in put voltage of 10 V.The freestandi ng graphe ne composite film with the delicate nano structure desig n has a great pote ntial to be integrated into electro-thermal devices.展开更多
A 3-D coordination polymer [PbNH(CH2COO)2] 1 has been prepared under hydrothermal conditions and its crystal structure was studied by single-crystal X-ray diffraction. The compound belongs to orthorhombic system, spac...A 3-D coordination polymer [PbNH(CH2COO)2] 1 has been prepared under hydrothermal conditions and its crystal structure was studied by single-crystal X-ray diffraction. The compound belongs to orthorhombic system, space group Fdd2 with unit cell parameters: a = 13.6304(6), b = 36.295(1), c = 5.0821(2) ? V = 2514.19(17) 3, Z = 16, Mr = 338.28, Dc = 3.575 g/cm3, F(000) = 2400 and m(MoKa) = 2.679 cm-1. The final R and wR are 0.0290 and 0.0685, respectively, for 874 observed reflections with I > 2s(I). The lead has a distorted tetragonal pyramid environment with four oxygen donors in the basal plane and one nitrogen donor in the axial site. Micro-channels are observed in the neutral 3-D network of 1.展开更多
Two reported three-dimensional covalent organic frameworks(3D-COFs),COF-300 and COF-301,which have hierarchical porous structures and large pore volumes,were synthesized and employed as host materials for lithium-sulf...Two reported three-dimensional covalent organic frameworks(3D-COFs),COF-300 and COF-301,which have hierarchical porous structures and large pore volumes,were synthesized and employed as host materials for lithium-sulfur batteries.Owing to possessing excellent porosities as well as abundant hydroxyl groups in the pore walls,COF-301 can not only trap lithium polysulfides(PSs)via physical adsorption inside the pores,but also capture PSs by chemical interactions to relieve the shuttle effect.Interestingly,it is the first time that 3D-COFs were utilized as host materials for lithium-sulfur batteries as well as hydroxyl groups were introduced into COFs for improving the battery performance.As a result,COF-301@S as cathode material could reserve the capacity of 411.6 mA·h·g^-1 after 500 cycles with only 0.081%fading per cycle at 0.5 C,exhibiting better battery performance compared with COF-300@S.This study not only expands the applications of 3D-COFs but also provides a new route for designing lithium-sulfur batteries.展开更多
The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-cry...The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-crystal diffraction. It belongs to orthorhombic with space group Pccn, a = 20.949(3), b = 17.470(3), c = 20.345(3) Angstrom, V = 7446(2) Angstrom(3), Z = 8, D-c = 1.242 g/cm(3), mu = 1.365 mm(-1), F(000) = 2864, R = 0.0544 and wR = 0.1417. The tin atom is of five-coordination in a trigonal bipyramidal structure by bridging two carboxylate groups in different directions and the resulting structure which contains straight twist large ring channels along the axes of a, b and c is a three-dimensional framework polymer containing two different tin atoms.展开更多
文摘Background Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries.However,there are several inherent limitations.In this study,a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility.Methods Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant.Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility.Twenty-four rabbits were performed discectomy only (control group),discectomy with autologous bone implanted (autograft group),and discectomy with porous tantalum implanted (tantalum group) at 3 levels:L3–L4,L4–L5,and L5–L6 in random order.All the 24 rabbits were randomly sacrificed at the different post-operative times (2,4,6,and 12 months;n = 6 at each time point).Histologic examination and micro-computed tomography scans were done to evaluate the fusion process.Comparison of fusion index scores between groups was analyzed using one-way analysis of variance.Other comparisons of numerical variables between groups were made by Student t test.Results All rabbits survived and recovered without any symptoms of nerve injury.Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ± 0.32 vs.2.83 ± 0.38, F= 244.60, P = 0.709).Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ± 0.06 vs.1.23 ± 0.04, t = –0.644, P = 0.545),which indicated the BMSC proliferation without toxicity.SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant.No implant degradation,wear debris,or osteolysis was observed.Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces.Conclusion This novel porous tantal
基金This research was funded by the National Natural Science Foundation of China(Grant No.41877525)the National Natural Science Foundation of China(Grant No.41601563)。
文摘The application of ensemble learning models has been continuously improved in recent landslide susceptibility research,but most studies have no unified ensemble framework.Moreover,few papers have discussed the applicability of the ensemble learning model in landslide susceptibility mapping at the township level.This study aims at defining a robust ensemble framework that can become the benchmark method for future research dealing with the comparison of different ensemble models.For this purpose,the present work focuses on three different basic classifiers:decision tree(DT),support vector machine(SVM),and multi-layer perceptron neural network model(MLPNN)and two homogeneous ensemble models such as random forest(RF)and extreme gradient boosting(XGBoost).The hierarchical construction of deep ensemble relied on two leading ensemble technologies(i.e.,homogeneous/heterogeneous model ensemble and bagging,boosting,stacking ensemble strategy)to provide a more accurate and effective spatial probability of landslide occurrence.The selected study area is Dazhou town,located in the Jurassic red-strata area in the Three Gorges Reservoir Area of China,which is a strategic economic area currently characterized by widespread landslide risk.Based on a long-term field investigation,the inventory counting thirty-three slow-moving landslide polygons was drawn.The results show that the ensemble models do not necessarily perform better;for instance,the Bagging based DT-SVM-MLPNNXGBoost model performed worse than the single XGBoost model.Amongst the eleven tested models,the Stacking based RF-XGBoost model,which is a homogeneous model based on bagging,boosting,and stacking ensemble,showed the highest capability of predicting the landslide-affected areas.Besides,the factor behaviors of DT,SVM,MLPNN,RF and XGBoost models reflected the characteristics of slow-moving landslides in the Three Gorges reservoir area,wherein unfavorable lithological conditions and intense human engineering activities(i.e.,reservoir water level fluctuation,residen
基金supported by the Key Technology Projects of the China Southern Power Grid Corporation(STKJXM20200059)the Key Support Project of the Joint Fund of the National Natural Science Foundation of China(U22B20123)。
文摘With the development of green data centers,a large number of Uninterruptible Power Supply(UPS)resources in Internet Data Center(IDC)are becoming idle assets owing to their low utilization rate.The revitalization of these idle UPS resources is an urgent problem that must be addressed.Based on the energy storage type of the UPS(EUPS)and using renewable sources,a solution for IDCs is proposed in this study.Subsequently,an EUPS cluster classification method based on the concept of shared mechanism niche(CSMN)was proposed to effectively solve the EUPS control problem.Accordingly,the classified EUPS aggregation unit was used to determine the optimal operation of the IDC.An IDC cost minimization optimization model was established,and the Quantum Particle Swarm Optimization(QPSO)algorithm was adopted.Finally,the economy and effectiveness of the three-tier optimization framework and model were verified through three case studies.
基金supported by the National Natural Science Foundation of China(grant nos.21733005,21975115)Guangdong Provincial Key Laboratory of Catalysis(grant no.2020B121201002)+2 种基金Guangdong Innovative and Entrepreneurial Research Team Program(grant no.2016ZT06G587)Shenzhen Fundamental Research Program(grant nos.JCYJ20210324120010028,JCYJ20200109140801751)Shenzhen Sci-Tech Fund(grant no.KYTDPT20181011104007).
文摘Revealing the molecular packing,intermolecular interactions,and aggregation behaviors in the nanocrystalline bulk heterojunction(BHJ)domains undertake the tasks for future materials design for efficient solar cells,especially in understanding the structure–property relationship of isomeric non-fullerene acceptors(NFAs).Theoretical calculations reveal that 2ClIC-βδ,withβ-andδ-chlorine-substituted terminal groups,achieves a relatively higher dipole moment for enhanced intermolecular interactions.More importantly,when comparing the single-crystal X-ray diffraction patterns of three isomeric NFAs,BTIC-BO4Cl-βδ,BTIC-BO4Cl-βγ,and BTIC-BO4Cl,the synergistic effect of chlorine atoms at theβ-andδ-positions endows BTIC-BO4Cl-βδbetter molecular planarity with a dihedral angle of 1.14°.In turn,this creates the shortestπ∙∙∙πdistance(3.28Å)and smallest binding energies(−51.66 kcal mol^(−1))of the three NFAs,resulting in the tightest three-dimensional network packing structure with a framework of L_(x)=14.0Åand L_(y)=13.6Å.Such a structure has multiple intermolecular interactions for better charge transfer.However,the chlorine atomat theγ-position in the other two isomers contributes to non-intermolecular interactions with subordinate packing arrangements.Subsequently,the red-shifted UV-absorption and higher electron mobility observed in neat films of BTIC-BO4Cl-βδagree well with its more ordered crystallinity.This leads to a more suitable fiber-like phase separation in the corresponding active blend,ultimately improving the device performance with superior charge transport.As a result,the highest power conversion efficiency of 17.04%with a current density of 26.07 mA cm^(−2)was obtained with the BTIC-BO4Cl-βδ-based device.The carrier dynamics test and grazing incidence wide-angle X-ray scattering measurement indicate that the packing arrangement of molecules in the nanocrystalline BHJ domains is consistent with their crystallinity.This work investigates the structure–property differences
基金supported by the National Natural Science Foundation of China(22036003,21976077)the Natural Science Foundation of Jiangxi Province(20212ACB203009,20212ACB-203011)。
文摘Extracting uranium from seawater offers opportunities for sustainable nuclear fuel supply,but the task is quite challenging due to the low uranium concentration(~3 ppb)in seawater.Here,based on the Knoevenagel condensation reaction of aldehyde and acetonitrile groups,a novel stable sp^(2)carbon-linked three-dimensional covalent organic framework(3D COF),TFPM-PDANAO was prepared as a porous platform for uranium extraction from seawater.The TFPM-PDAN-AO designed with regular 3D pore channel of 7.12 A provides a specific channel for uranyl diffusion,which exhibits high selectivity and fast kinetics for uranium adsorption.Meanwhile,the superior stability and optoelectronic properties enable it an excellent porous platform for uranium electroextraction.By applying alternating voltages between-5 and 0 V,uranyl ions can rapidly migrate and enrich into the porous structure of TFPM-PDAN-AO,then inducing the electrodeposition of uranium compounds to form the charge neutral species(Na_(2)O(UO_(3)H_(2)O)x)with an unprecedentedly high adsorption capacity of 4,685 mg g^(-1).This work not only expands the application prospects of functionalized 3D COFs,but also provides a technical support for the electrodeposition adsorption of uranium from seawater.
基金supported financially by the National Key Research and Development Program of China(No.2017YFB0307701).
文摘Si materials are widely considered to be the next-generation anode to replace the current commercial graphite-based anode due to its high energy density.However,the large volume variation of silicon during(de)lithiation process leads to rapid capacity decay,hindering its commercial application.Although the various hollow structure designs of Si nanomaterials have improved their cycling stability in the laboratory,the high-pressure calendering process in the current industrial electrode preparation process might collapse the hollow structure and weaken the structural advantages of hollow silicon anode materials.In this work,a silicon carbon composite material(Si@3DC)in which Si nanoparticles were anchored on a three-dimensional carbon framework through carbon films was prepared by a simple proton exchange method.The three-dimensional carbon framework with multiple hierarchical pores of Si@3DC was compatible with the high-pressure calendering process,but also could provide expansion space for Si nanoparticles during the lithiation process,and ensure good electronic and ionic conductivity.The carbon film on the surface of Si nanoparticles promoted the formation of stable solid electrolyte interphase(SEI)films,ensuring the good cycle stability of Si@3DC.
基金supported by the Grant from the Project“Trends,Priorities,and Logic of Science and Technology Policy in the New U.S.Administration(Biden Administration)”commissioned by the International Department of the Ministry of Science and Technology of China(2021ICR12)
文摘The analysis of the current big data policy for scientific research can promote the ecological optimization of big data policy,and is a positive response to the national big data strategy.This paper constructs a“dual three-dimensional framework”to analyze the central and local science data policies from 2013 to 2022.With the dissemination and popularization of the concept of scientific data sharing,policies and regulations related to scientific data management have been issued,which promotes the emergence of scientific data policy ecology.The scientific data policy ecology is a complex and multicollaborative dynamic system composed of policy text,policy environment and related personnel,the core of which lies in the policy itself,aiming to ensure the security of scientific data and promote the development of science.There are the following problems in the scientific data policy ecology:In terms of policy text,the policy effectiveness is low and the use of policy tools is uneven.In terms of relevant personnel,the cooperation network density among various subjects is low and there is a lack of highquality talents.In terms of policy environment,there is an imbalance of regional funding support.It also puts forward some optimization strategies,such as strengthening the systematization of policy texts,improving the degree of coordination of policy subjects to form a long-term cooperation network,and improving the degree of compatibility between environment,personnel and policies.
基金This work was supported by the National Key R&D Program of China(Nos.2016YFA0202900 and 2016YFC1402400)National Natural Science Foundation of China(No.51672173)+2 种基金Shanghai Science and Technology committee(No.17JC1400700 and 18520744700)Science and Technology Planning Project of Guangdong Province(No.2016A010103018)The authors gratefully acknowledge the Shanghai Synchrotron Radiation Facility(SSRF)and Shanghai LEVSON Group Co.,Ltd.for the measurements.
文摘A high-efficiency electro-thermal heater requires simultaneously high electrical and thermal conductivities to generate and dissipate Joule heat efficiently.A low in put voltage is essential to en sure the heaters safe applications.However,the low voltage gen erally leads to low saturated temperature and heati ng rate and hence a low thermal efficie ncy.How to reduce the in put voltage while maintai ning a high electro-thermal efficiency is still a challenge.Herein,a highly electrical and thermal conductive film was 8nstructed using a graphene-based composite which has an internal three-dimensional(3D)conductive network.In the 3D framework,cellulose nanocrystalline(CNC)phase with chiral liquid crystal manner presents in the form of alig ned helix betwee n the graphe ne oxide(GO)layers.Carbon nano dots(CDs)are assembled泊side the composite as con ductive nano fillers.Subseque nt an neali ng and compressi on results in the formati on of the assembled GO-CNC-CDs film.The carb on ized CNC nano rods(CNR)with the helical alignment act as irrplane and through-pla ne conn ecti ons of n eighbori ng reduced GO(rGO)nano sheets,forming a con ductive network in the composite film.The CDs with ultrafast electr ons tran sfer rates provide additi onal electro ns and phonons tran sport paths for the composite.As a result,the obtai ned graphe ne?based composite film(rGO-CNR-CDs)exhibited a high thermal conductivity of 1,978.6 W m^-1·K^-1 and electrical conductivity of 2,053.4 S·cm^-1,respectively.The composite film showed an outstanding electro-thermal heating efficiency with the saturated temperature of 315℃and maximum heating rate of 44.9℃·s^-1 at a very low in put voltage of 10 V.The freestandi ng graphe ne composite film with the delicate nano structure desig n has a great pote ntial to be integrated into electro-thermal devices.
基金This work was supported by the State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter+1 种基金 Chinese Academy of Sciences (CAS) the Ministry of Science and Technology of China (001CB1089)
文摘A 3-D coordination polymer [PbNH(CH2COO)2] 1 has been prepared under hydrothermal conditions and its crystal structure was studied by single-crystal X-ray diffraction. The compound belongs to orthorhombic system, space group Fdd2 with unit cell parameters: a = 13.6304(6), b = 36.295(1), c = 5.0821(2) ? V = 2514.19(17) 3, Z = 16, Mr = 338.28, Dc = 3.575 g/cm3, F(000) = 2400 and m(MoKa) = 2.679 cm-1. The final R and wR are 0.0290 and 0.0685, respectively, for 874 observed reflections with I > 2s(I). The lead has a distorted tetragonal pyramid environment with four oxygen donors in the basal plane and one nitrogen donor in the axial site. Micro-channels are observed in the neutral 3-D network of 1.
基金supported by the National Natural Science Foundation of China(Nos.21674026,21574032,51573125,51573147,51803149,51973155,and 51633007(the State Key Program))the Sino-German Center for Research Promotion(No.GZ1286)the Chinese Academy of Sciences(No.121D11KYSB20170031).
文摘Two reported three-dimensional covalent organic frameworks(3D-COFs),COF-300 and COF-301,which have hierarchical porous structures and large pore volumes,were synthesized and employed as host materials for lithium-sulfur batteries.Owing to possessing excellent porosities as well as abundant hydroxyl groups in the pore walls,COF-301 can not only trap lithium polysulfides(PSs)via physical adsorption inside the pores,but also capture PSs by chemical interactions to relieve the shuttle effect.Interestingly,it is the first time that 3D-COFs were utilized as host materials for lithium-sulfur batteries as well as hydroxyl groups were introduced into COFs for improving the battery performance.As a result,COF-301@S as cathode material could reserve the capacity of 411.6 mA·h·g^-1 after 500 cycles with only 0.081%fading per cycle at 0.5 C,exhibiting better battery performance compared with COF-300@S.This study not only expands the applications of 3D-COFs but also provides a new route for designing lithium-sulfur batteries.
基金the National Natural Science Foundation of China (No. 20271025)the Natural Science Foundation of Shandong province (No. Z2001B02)the State Key Laboratory of Crystal Materials,Shandong University
文摘The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-crystal diffraction. It belongs to orthorhombic with space group Pccn, a = 20.949(3), b = 17.470(3), c = 20.345(3) Angstrom, V = 7446(2) Angstrom(3), Z = 8, D-c = 1.242 g/cm(3), mu = 1.365 mm(-1), F(000) = 2864, R = 0.0544 and wR = 0.1417. The tin atom is of five-coordination in a trigonal bipyramidal structure by bridging two carboxylate groups in different directions and the resulting structure which contains straight twist large ring channels along the axes of a, b and c is a three-dimensional framework polymer containing two different tin atoms.
