With the proposal of the Belt and Road Initiative,the exchanges and cooperation between China and Latin America in various fields are rapidly warming up,and both sides actively promote cross-regional,cross-country,and...With the proposal of the Belt and Road Initiative,the exchanges and cooperation between China and Latin America in various fields are rapidly warming up,and both sides actively promote cross-regional,cross-country,and cross-cultural international talent education.The proposal of Chengdu-Chongqing economic circle coincides with a great change unseen in a century.Under the background of far-reaching and complicate changes in both domestic and international environment,the trend of all-round cooperation between the Chengdu-Chongqing economic circle and Latin American countries and regions has been deepening.However,the quantity,quality,level and economic cross-regional training of regional Latin American international talents still present some structural imbalances and challenges compared with the development of trans-regional economic cooperation.Based on this,the study will focus on the current situation of nurturing international talents in Latin America by the Chengdu-Chongqing economic circle,and provide suggestions for the joint training of talents in Latin America and China-Latin America educational cooperation and exchanges.It will also make for jointly build a China-Latin America Community of Shared Future and respond to the Belt and Road initiative with a certain reference value.展开更多
A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenyle...A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenylenediamine are both selected as the nitrogen,carbon sources and co-polymerized on Si@SiO_(2),in which SiO_(2)is functionalized as a void template.SEM and TEM observation show that Si nanoparticles are encapsulated in a hollow and interconnected carbon cages with a thickness of less than 10 nm,which is inclined to agglomerate together to form larger particles in micrometer scale.The variation of mole ratio of aniline and ortho-phenylenediamine will enable the change of nitrogen doping level in the carbon layer and ranges from 3.2%to 8.4%.The nitrogen is doped into the carbon framework in the form of pyridinic,pyrrolic and graphitic nitrogen.Electrochemical tests indicate that the nitrogen content influences the SEI formation and the lithiation of Si nanoparticles.The potential for the decomposition of electrolyte to form SEI film and the alloying of Si-Li negatively shift when the nitrogen doping content is increased.Furthermore,the cycling performance of Si@void@NC is improved when raising the nitrogen content in the carbon.And the optimal nitrogen content is 7.5%,which is corresponding to the mole ratio of aniline to ortho-phenylenediamine is 5:5.展开更多
The fabrication of constructs with gradients for chemical,mechanical,or electrical composition is becoming critical to achieving more complex structures,particularly in 3D printing and biofabrication.This need is unde...The fabrication of constructs with gradients for chemical,mechanical,or electrical composition is becoming critical to achieving more complex structures,particularly in 3D printing and biofabrication.This need is underscored by the complexity of in vivo tissues,which exhibit heterogeneous structures comprised of diverse cells and matrices.Drawing inspiration from the classical Tesla valve,our study introduces a new concept of micromixers to address this complexity.The innovative micromixer design is tailored to enhance the re-creation of in vivo tissue structures and demonstrates an advanced capability to efficiently mix both Newtonian and non-Newtonian fluids.Notably,our 3D Tesla valve micromixer achieves higher mixing efficiency with fewer cycles,which represents a significant improvement over the traditional mixing method.This advance is pivotal for the field of 3D printing and bioprinting,and offers a robust tool that could facilitate the development of gradient hydrogel-based constructs that could also accurately mimic the intricate heterogeneity of natural tissues.展开更多
Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchangemembrane fuel cells.The impacts of the equivalent weight(EW)of perfluorosulfonic acid-based ionomers on the plati...Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchangemembrane fuel cells.The impacts of the equivalent weight(EW)of perfluorosulfonic acid-based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully explored.Four membrane electrode assemblies(MEAs)were prepared by using a commercial Fe-N-C catalyst,two perfluorosulfonic acid ionomers with different EWs,that is,Aquivion 720(A720)and Nafion 1100(N1100),and two ionomer-tocatalyst(I/C)ratios.The four MEAswere characterized to understand the impact of the ionomer EW and content on the capacitance,proton conductivity,and mass transport on the cathode.The mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water generation.Low EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton conductivity.However,when used at high I/C,it can cause severewater flooding at high current density due to the enhanced liquid water uptake,especially at high relative humidity,resulting in lower catalyst utilization and higher mass transport resistance.展开更多
Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin elec-trodes are first developed as highly active anodes for proton exchange mem-brane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily...Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin elec-trodes are first developed as highly active anodes for proton exchange mem-brane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room temperature.Combined with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes.Notably,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in catalysts.Overall,due to the high activ-ity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates commercialization of PEMECs and renewable energy evolution.展开更多
Solid-state perovskite nanocrystals are promising coherent light sources, as there is optical feedback within the crystal structure. In order to utilize the high performance of perovskites for on-chip applications, or...Solid-state perovskite nanocrystals are promising coherent light sources, as there is optical feedback within the crystal structure. In order to utilize the high performance of perovskites for on-chip applications, or observe new physical phenomena, these crystals must be integrated with pre-fabricated electronic or photonic structures. However, the material's fragility has made the deterministic transfer a great challenge thus far. Here, we report the first deterministic transfer of perovskite nanocrystals with sub-micron accuracy. Cesium lead halide(CsPbI_3) nanocrystals were directly synthesized on flexible polydimethylsiloxane(PDMS) stamps via chemical vapor deposition(CVD) and subsequently transferred onto arbitrary substrates/structures. We demonstrated the transfer of a CsPbI_3 crystalline nanoplate(NP)onto an 8 mm fiber core and achieved single-mode whispering gallery mode lasing. Our method can be extended to a variety of other arbitrary substrates(e.g., electrodes, photonic structures, micromechanical systems), laying the foundations for previously unattainable opportunities in perovskites-based devices.展开更多
Water-insoluble organic compounds(WIOCs)are an important fraction of atmospheric fine particulate matters(PM_(2.5)),which could affect the climate system and threaten human health potentially.In this study,molecular c...Water-insoluble organic compounds(WIOCs)are an important fraction of atmospheric fine particulate matters(PM_(2.5)),which could affect the climate system and threaten human health potentially.In this study,molecular characterization of WIOCs in PM_(2.5) were investigated by 15 T Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)with atmospheric pressure photoionization(APPI)source in positive ion mode.A total of 2573 and1875 molecular formulas were identified in WIOCs extracted by dichloromethane,which were collected in hazy and normal days,respectively.The identified molecular formulas were further classified into four major subgroups,including CH,CHN,CHO and CHNO compounds.CHO compounds predominated in WIOCs,accounting for more than 60%in both samples.CHNO compounds(26.6%)and CH compounds(16.1%)were the second highest subgroups in WIOCs from the hazy days and normal days,respectively.The relative abundance and number of nitro-substituted aromatic compounds were significantly higher in hazy days than in normal days.The molecular composition of WIOCs was more complex in hazy days while more aromatic compounds were identified in normal days.展开更多
文摘With the proposal of the Belt and Road Initiative,the exchanges and cooperation between China and Latin America in various fields are rapidly warming up,and both sides actively promote cross-regional,cross-country,and cross-cultural international talent education.The proposal of Chengdu-Chongqing economic circle coincides with a great change unseen in a century.Under the background of far-reaching and complicate changes in both domestic and international environment,the trend of all-round cooperation between the Chengdu-Chongqing economic circle and Latin American countries and regions has been deepening.However,the quantity,quality,level and economic cross-regional training of regional Latin American international talents still present some structural imbalances and challenges compared with the development of trans-regional economic cooperation.Based on this,the study will focus on the current situation of nurturing international talents in Latin America by the Chengdu-Chongqing economic circle,and provide suggestions for the joint training of talents in Latin America and China-Latin America educational cooperation and exchanges.It will also make for jointly build a China-Latin America Community of Shared Future and respond to the Belt and Road initiative with a certain reference value.
基金supported by grants Hubei Province Technology Innovation Project(2018AAA056)Open Fund of Hubei Collaborative Innovation Center for High Efficient Utilization of Solar Energy(HBSKFZD2017006)+1 种基金Innovative Research and Development Institute of Guangdong(No.2018B090902009)Innovation and entrepreneurship training program for College Students(No.201710500024).
文摘A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenylenediamine are both selected as the nitrogen,carbon sources and co-polymerized on Si@SiO_(2),in which SiO_(2)is functionalized as a void template.SEM and TEM observation show that Si nanoparticles are encapsulated in a hollow and interconnected carbon cages with a thickness of less than 10 nm,which is inclined to agglomerate together to form larger particles in micrometer scale.The variation of mole ratio of aniline and ortho-phenylenediamine will enable the change of nitrogen doping level in the carbon layer and ranges from 3.2%to 8.4%.The nitrogen is doped into the carbon framework in the form of pyridinic,pyrrolic and graphitic nitrogen.Electrochemical tests indicate that the nitrogen content influences the SEI formation and the lithiation of Si nanoparticles.The potential for the decomposition of electrolyte to form SEI film and the alloying of Si-Li negatively shift when the nitrogen doping content is increased.Furthermore,the cycling performance of Si@void@NC is improved when raising the nitrogen content in the carbon.And the optimal nitrogen content is 7.5%,which is corresponding to the mole ratio of aniline to ortho-phenylenediamine is 5:5.
基金supported by the National Key Research and Development Program of China(No.2018YFA0703000)the National Natural Science Foundation of China(No.52275294).
文摘The fabrication of constructs with gradients for chemical,mechanical,or electrical composition is becoming critical to achieving more complex structures,particularly in 3D printing and biofabrication.This need is underscored by the complexity of in vivo tissues,which exhibit heterogeneous structures comprised of diverse cells and matrices.Drawing inspiration from the classical Tesla valve,our study introduces a new concept of micromixers to address this complexity.The innovative micromixer design is tailored to enhance the re-creation of in vivo tissue structures and demonstrates an advanced capability to efficiently mix both Newtonian and non-Newtonian fluids.Notably,our 3D Tesla valve micromixer achieves higher mixing efficiency with fewer cycles,which represents a significant improvement over the traditional mixing method.This advance is pivotal for the field of 3D printing and bioprinting,and offers a robust tool that could facilitate the development of gradient hydrogel-based constructs that could also accurately mimic the intricate heterogeneity of natural tissues.
基金National Renewable Energy Laboratory for the U.S.Department of Energy(DOE)under Contract No.DE-AC36-08GO28308Argonne National Laboratory is managed for the U.S.Department of Energy by the University of Chicago Argonne,LLC,also under contract DE-AC-02-06CH11357+1 种基金supported by the U.S.Department of Energy,Office of Energy Efficiency and Renewable Energy,Hydrogen and Fuel Cell Technologies Office(HFTO).This research used resources of the Advanced Photon Source(APS)a U.S.Department of Energy Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchangemembrane fuel cells.The impacts of the equivalent weight(EW)of perfluorosulfonic acid-based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully explored.Four membrane electrode assemblies(MEAs)were prepared by using a commercial Fe-N-C catalyst,two perfluorosulfonic acid ionomers with different EWs,that is,Aquivion 720(A720)and Nafion 1100(N1100),and two ionomer-tocatalyst(I/C)ratios.The four MEAswere characterized to understand the impact of the ionomer EW and content on the capacitance,proton conductivity,and mass transport on the cathode.The mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water generation.Low EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton conductivity.However,when used at high I/C,it can cause severewater flooding at high current density due to the enhanced liquid water uptake,especially at high relative humidity,resulting in lower catalyst utilization and higher mass transport resistance.
基金the support from the U.S.Department of Energy's Office of Energy Efficiency and Renewable Energy(EERE)under the Hydrogen and Fuel Cell Technologies Office Awards DE-EE0008426 and DE-EE0008423and National Energy Technology Laboratory under Award DEFE0011585.
文摘Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin elec-trodes are first developed as highly active anodes for proton exchange mem-brane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room temperature.Combined with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes.Notably,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in catalysts.Overall,due to the high activ-ity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates commercialization of PEMECs and renewable energy evolution.
基金supported by the National Natural Science Foundation of China (61875001, 61521004, 61874003, and 11474007)the National Key Research and Development Program of China (2018YFA0306900 and 2017YFA0206301)+1 种基金Beijing Natural Science Foundation (4182028), the National Basic Research Program of China (2013CB921901)and the ‘‘1000 Youth Talent Plan” Fund
文摘Solid-state perovskite nanocrystals are promising coherent light sources, as there is optical feedback within the crystal structure. In order to utilize the high performance of perovskites for on-chip applications, or observe new physical phenomena, these crystals must be integrated with pre-fabricated electronic or photonic structures. However, the material's fragility has made the deterministic transfer a great challenge thus far. Here, we report the first deterministic transfer of perovskite nanocrystals with sub-micron accuracy. Cesium lead halide(CsPbI_3) nanocrystals were directly synthesized on flexible polydimethylsiloxane(PDMS) stamps via chemical vapor deposition(CVD) and subsequently transferred onto arbitrary substrates/structures. We demonstrated the transfer of a CsPbI_3 crystalline nanoplate(NP)onto an 8 mm fiber core and achieved single-mode whispering gallery mode lasing. Our method can be extended to a variety of other arbitrary substrates(e.g., electrodes, photonic structures, micromechanical systems), laying the foundations for previously unattainable opportunities in perovskites-based devices.
基金supported by the National Natural Science Foundation of China(Grant No.91643104)for the financial support。
文摘Water-insoluble organic compounds(WIOCs)are an important fraction of atmospheric fine particulate matters(PM_(2.5)),which could affect the climate system and threaten human health potentially.In this study,molecular characterization of WIOCs in PM_(2.5) were investigated by 15 T Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)with atmospheric pressure photoionization(APPI)source in positive ion mode.A total of 2573 and1875 molecular formulas were identified in WIOCs extracted by dichloromethane,which were collected in hazy and normal days,respectively.The identified molecular formulas were further classified into four major subgroups,including CH,CHN,CHO and CHNO compounds.CHO compounds predominated in WIOCs,accounting for more than 60%in both samples.CHNO compounds(26.6%)and CH compounds(16.1%)were the second highest subgroups in WIOCs from the hazy days and normal days,respectively.The relative abundance and number of nitro-substituted aromatic compounds were significantly higher in hazy days than in normal days.The molecular composition of WIOCs was more complex in hazy days while more aromatic compounds were identified in normal days.
