With the rapid development of wearable electronics,flexible pressure sensors have attracted wide attention in human–computer interaction and intelligent machines.However,it is a challenge to achieve a sensor with hig...With the rapid development of wearable electronics,flexible pressure sensors have attracted wide attention in human–computer interaction and intelligent machines.However,it is a challenge to achieve a sensor with high sensitivity,wide measurement range,and wearing comfortability.Here,we develop an oriented electrospinning thermoplastic polyurethane/polyacrylonitrile(TPU/PAN)nanofibers(OETPN)based piezoresistive pressure sensor(PONPS)in which the active layer and the electrode are assembled perpendicularly.The interdigital electrode is fabricated by spraying silver nanowires(AgNWs)on the OETPN through a mask plate.The active layer is composed of OETPN coated with MXene,encapsulated on the electrode by polyurethane(PU)film.The porous structure of nanofibers membrane broadens the measurement range of the sensor.Employing oriented nanofibers as active layer can improve the sensitivity in low pressure,because oriented nanofibers without interweaving nanofibers are more compressible than disordered nanofibers.Electrode prepared using the spraying method creates nanoscale microstructure and increases sensitivity.The perpendicular assembly has greater response between the active layer and the electrode than the parallel assembly to improve the sensitivity.The sensor exhibits high sensitivity(6.71 kPa^(−1),0.02–2 kPa)and wide measurement range(0.02–700 kPa).The sensor can detect weak signals such as radial artery.A pressure array constructed precisely represents the distribution of pressure.An intelligent throat is created by combining machine learning algorithms with the PONPS.It can detect and recognize subtle throat vibrations while speaking,achieving recognition accuracy up to 100%using support vector machine(SVM)for five words with different syllables.The fabricated sensor shows promising prospects in personal healthcare and intelligent robots.展开更多
Understanding the evolution process and formation mechanism of nanoscale structures is crucial to controllable synthesis of inorganic nanomaterials with well-defined geometries and unique functionalities. In addition ...Understanding the evolution process and formation mechanism of nanoscale structures is crucial to controllable synthesis of inorganic nanomaterials with well-defined geometries and unique functionalities. In addition to the conventional Ostwald ripening process, oriented aggregation has been recently found to be prevalent in nanocrystal growth. In this new mechanism, primary small nanocrystals firstly spontaneously aggregate in the manner of oriented attachment, and then the large crystalline materials are formed via the process of interparticle recrystallization. Furthermore, controllable fabrication of the ordered nanocrystal solid materials that has shown specific collective properties will promote the application of inorganic nanocrystal in devices. Therefore, investigation of the mechanism of oriented aggregation is essential to controllable synthesis of nanocrystals and ordered nanocrystal solid materials. In this review, we summarize recent advances in the preparation of nanocrystal materials, which are mostly focused on our work about the role of self-assembly in construction of inorganic nanostructural materials.展开更多
Mesocrystals, which are assemblies of crystallographically oriented nanocrystals, have received increasing attention due to their unique properties such as high crystallinity, high porosity, oriented subunit alignment...Mesocrystals, which are assemblies of crystallographically oriented nanocrystals, have received increasing attention due to their unique properties such as high crystallinity, high porosity, oriented subunit alignment, and similarity to highly sophisticated biominerals. However, the controlled synthesis of TiO 2 mesocrystals has not been realized until recently, probably because of the difficulty in accurately controlling the reaction processes that produce TiO 2 crystals. In this review, recent advances in the synthesis and applications of TiO 2 mesocrystals are summarized with particular attention paid to the mechanisms of their formation. Three typical pathways for the preparation of TiO 2 mesocrystals are discussed, namely topotactic transformation, direct synthesis in solution, and growth on supports. The potential applications of TiO 2 mesocrystals in lithium ion batteries, photocatalysis, enzyme immobilization, and antireflection materials are also described.展开更多
The photoreversible color switching system(PCSS)is attracting increasing attention for use in alleviating energy crisis and environmental problems.We report a robust PCSS in which lattice matching enables bottom-up or...The photoreversible color switching system(PCSS)is attracting increasing attention for use in alleviating energy crisis and environmental problems.We report a robust PCSS in which lattice matching enables bottom-up oriented assembly between metal-organic frameworks(MOFs)and inorganic nanocrystals(INCs),two distinct entities that differ drastically in structure and function.Specifically,cubic-phase Prussian blue(PB)of a framework backbone is spontaneously attached to rutile TiO_(2)nanowires in a defined orientation triggered by the lattice matching between the(001)plane of TiO_(2)and the(222)plane of PB.Ultraviolet light irradiation accelerates the photoelectron transport within the oriented TiO_(2)/PB system and enables fast photo switching.The derived TiO_(2)/PB paper can be ranked as one of the best light-printing papers in literature because of its high resolution(∼µm)and capability to be repeatedly written for>100 times without significant loss of contrast.The ultrathin TiO_(2)nanowires are rich in oxygen and Ti vacancies,which allow visible-and sunlight-light printing.Density functional theory calculations suggest that the[Fe(CN)_(6)]^(4−) ligand from the PB attaches preferentially to the(110)surface of TiO_(2)to give the ordered TiO_(2)/PB assembly.The findings demonstrate the strong versatility of particles-mediated assembly in advanced materials design.展开更多
Inspired by the curved branches of fractal trees, hooked Ni–Fe fibers were grown in situ in Ni–Fe composite coatings on a spheroidal graphite cast iron substrate. These hooked Ni–Fe fibers exhibited inclination ang...Inspired by the curved branches of fractal trees, hooked Ni–Fe fibers were grown in situ in Ni–Fe composite coatings on a spheroidal graphite cast iron substrate. These hooked Ni–Fe fibers exhibited inclination angles of about 39°, which was in accordance with the theoretical prediction of 37°. Ni–Fe nanostructures self-assembled to form dendrites and evolved into hooked fibers by an oriented attachment reaction. The orientation rotation of Ni–Fe nanostructures played an important role in the growth of curved hooked Ni–Fe fibers. During sliding wear tests, the volume loss of the spheroidal graphite cast iron substrate was 2.2 times as large as that of the Ni–Fe coating reinforced by hooked fibers. The good load-transferring ability of hooked Ni–Fe fibers led to an improvement in their wear properties during wear tests.展开更多
A simple, surfactant-free, and environmentally benign method has been developed to synthesize a novel 3D flocculus-like CuO hierarchical nanostructure self-assembled with 2D nanosheet as building blocks. Detailed proo...A simple, surfactant-free, and environmentally benign method has been developed to synthesize a novel 3D flocculus-like CuO hierarchical nanostructure self-assembled with 2D nanosheet as building blocks. Detailed proofs demonstrate that the overall synthetic process underwent the dehydration and re-crystallization of precursor Cu（OH）2 nanowires, and the subsequent two-step oriented attachment. In addition, 3D butterfly-like and flower-like CuO nanostructures consisted of 2D nanosheets could be obtained by adjusting the concentration of NaOH（cNaoH） in the solution. CNaOH played a key role in tailoring the thickness of the nanosheets and changing the morphology of the product. This report may be helpful to constructing fine-tune hierarchical CuO nanostructures under basic conditions.展开更多
Virtual assembly is a Virtual Reality (VR) based engineering application which allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. To model the virtual assembly process, new methodology...Virtual assembly is a Virtual Reality (VR) based engineering application which allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. To model the virtual assembly process, new methodology must be applied. Based on the idea that the virtual assembly system is an event driven system, the interactive behavior and information model is proposed to describe the dynamic process of virtual assembly. Definition of the object-oriented model of virtual assembly is put forward.展开更多
The graphene oxide powder(GOP)obtained from the spray drying process often exhibits poor redispersibility which is considered due to the partial reduction of GO sheets.The reduction of drying temperature can effective...The graphene oxide powder(GOP)obtained from the spray drying process often exhibits poor redispersibility which is considered due to the partial reduction of GO sheets.The reduction of drying temperature can effectively increase the redispersibility of GOP,but result in a decreased drying efficiency.Herein,we found that the redispersibility of GOP is strongly affected by its microstructure,which is determined by the feed concentration.With the increase of feed concentration,the GO nanosheet assembly varies from the disordered stacking to relatively oriented assembly,making the morphology of the GOP transform from balllike(the most crumpled one)to flakelike(the least crumpled one),and the 0.8 mgml 1 is the threshold concentration for the morphology,structure,and redispersibility change.Once the feed concentration reaches 0.8 mg ml 1,the appearance of the nematic phase in droplet ensures the relatively oriented assembly of GO sheets to form the layered structure with a low crumpling degree,which greatly improves the polar parts surface tension of the solid GOP,making the GOP easier to form hydrogen bonding with water during the redispersion process,thus stabilizing dispersion.This work provides useful information for understanding the relationships between the morphology,microstructure,and final redispersibility of GOPs.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52175554,52205608,and 62171414)the Fundamental Research Program of Shanxi Province(Nos.20210302123059 and 20210302124610)the program for the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2020L0316).
文摘With the rapid development of wearable electronics,flexible pressure sensors have attracted wide attention in human–computer interaction and intelligent machines.However,it is a challenge to achieve a sensor with high sensitivity,wide measurement range,and wearing comfortability.Here,we develop an oriented electrospinning thermoplastic polyurethane/polyacrylonitrile(TPU/PAN)nanofibers(OETPN)based piezoresistive pressure sensor(PONPS)in which the active layer and the electrode are assembled perpendicularly.The interdigital electrode is fabricated by spraying silver nanowires(AgNWs)on the OETPN through a mask plate.The active layer is composed of OETPN coated with MXene,encapsulated on the electrode by polyurethane(PU)film.The porous structure of nanofibers membrane broadens the measurement range of the sensor.Employing oriented nanofibers as active layer can improve the sensitivity in low pressure,because oriented nanofibers without interweaving nanofibers are more compressible than disordered nanofibers.Electrode prepared using the spraying method creates nanoscale microstructure and increases sensitivity.The perpendicular assembly has greater response between the active layer and the electrode than the parallel assembly to improve the sensitivity.The sensor exhibits high sensitivity(6.71 kPa^(−1),0.02–2 kPa)and wide measurement range(0.02–700 kPa).The sensor can detect weak signals such as radial artery.A pressure array constructed precisely represents the distribution of pressure.An intelligent throat is created by combining machine learning algorithms with the PONPS.It can detect and recognize subtle throat vibrations while speaking,achieving recognition accuracy up to 100%using support vector machine(SVM)for five words with different syllables.The fabricated sensor shows promising prospects in personal healthcare and intelligent robots.
基金supported by the National Natural Science Foundation for Distinguished Youth Scholars of China (21025310, Z.Y.T.)National Natural Science Foundation of China (91027011, Z.Y.T.)National Basic Research Program of China (973 Program) (2009CB930401,Z.Y.T.)
文摘Understanding the evolution process and formation mechanism of nanoscale structures is crucial to controllable synthesis of inorganic nanomaterials with well-defined geometries and unique functionalities. In addition to the conventional Ostwald ripening process, oriented aggregation has been recently found to be prevalent in nanocrystal growth. In this new mechanism, primary small nanocrystals firstly spontaneously aggregate in the manner of oriented attachment, and then the large crystalline materials are formed via the process of interparticle recrystallization. Furthermore, controllable fabrication of the ordered nanocrystal solid materials that has shown specific collective properties will promote the application of inorganic nanocrystal in devices. Therefore, investigation of the mechanism of oriented aggregation is essential to controllable synthesis of nanocrystals and ordered nanocrystal solid materials. In this review, we summarize recent advances in the preparation of nanocrystal materials, which are mostly focused on our work about the role of self-assembly in construction of inorganic nanostructural materials.
基金supported by the National Natural Science Foundation of China (21073005, 21173010, and 51121091)National Basic Research Program of China (973 Program, 2007CB936201)
文摘Mesocrystals, which are assemblies of crystallographically oriented nanocrystals, have received increasing attention due to their unique properties such as high crystallinity, high porosity, oriented subunit alignment, and similarity to highly sophisticated biominerals. However, the controlled synthesis of TiO 2 mesocrystals has not been realized until recently, probably because of the difficulty in accurately controlling the reaction processes that produce TiO 2 crystals. In this review, recent advances in the synthesis and applications of TiO 2 mesocrystals are summarized with particular attention paid to the mechanisms of their formation. Three typical pathways for the preparation of TiO 2 mesocrystals are discussed, namely topotactic transformation, direct synthesis in solution, and growth on supports. The potential applications of TiO 2 mesocrystals in lithium ion batteries, photocatalysis, enzyme immobilization, and antireflection materials are also described.
基金supported by the National Key Research and Development Program of China(2020YFA0710303)the National Natural Science Foundation of China(U1905215,51772053,52072076)。
文摘The photoreversible color switching system(PCSS)is attracting increasing attention for use in alleviating energy crisis and environmental problems.We report a robust PCSS in which lattice matching enables bottom-up oriented assembly between metal-organic frameworks(MOFs)and inorganic nanocrystals(INCs),two distinct entities that differ drastically in structure and function.Specifically,cubic-phase Prussian blue(PB)of a framework backbone is spontaneously attached to rutile TiO_(2)nanowires in a defined orientation triggered by the lattice matching between the(001)plane of TiO_(2)and the(222)plane of PB.Ultraviolet light irradiation accelerates the photoelectron transport within the oriented TiO_(2)/PB system and enables fast photo switching.The derived TiO_(2)/PB paper can be ranked as one of the best light-printing papers in literature because of its high resolution(∼µm)and capability to be repeatedly written for>100 times without significant loss of contrast.The ultrathin TiO_(2)nanowires are rich in oxygen and Ti vacancies,which allow visible-and sunlight-light printing.Density functional theory calculations suggest that the[Fe(CN)_(6)]^(4−) ligand from the PB attaches preferentially to the(110)surface of TiO_(2)to give the ordered TiO_(2)/PB assembly.The findings demonstrate the strong versatility of particles-mediated assembly in advanced materials design.
基金financially supported by the Project of Education Department of Liaoning Province,China(No.990790)the National Natural Science Foundation of China(No.51402035)
文摘Inspired by the curved branches of fractal trees, hooked Ni–Fe fibers were grown in situ in Ni–Fe composite coatings on a spheroidal graphite cast iron substrate. These hooked Ni–Fe fibers exhibited inclination angles of about 39°, which was in accordance with the theoretical prediction of 37°. Ni–Fe nanostructures self-assembled to form dendrites and evolved into hooked fibers by an oriented attachment reaction. The orientation rotation of Ni–Fe nanostructures played an important role in the growth of curved hooked Ni–Fe fibers. During sliding wear tests, the volume loss of the spheroidal graphite cast iron substrate was 2.2 times as large as that of the Ni–Fe coating reinforced by hooked fibers. The good load-transferring ability of hooked Ni–Fe fibers led to an improvement in their wear properties during wear tests.
基金Supported by the Natural Science Foundation of Heilongjiang Province, China（No.QC2012C072）.
文摘A simple, surfactant-free, and environmentally benign method has been developed to synthesize a novel 3D flocculus-like CuO hierarchical nanostructure self-assembled with 2D nanosheet as building blocks. Detailed proofs demonstrate that the overall synthetic process underwent the dehydration and re-crystallization of precursor Cu（OH）2 nanowires, and the subsequent two-step oriented attachment. In addition, 3D butterfly-like and flower-like CuO nanostructures consisted of 2D nanosheets could be obtained by adjusting the concentration of NaOH（cNaoH） in the solution. CNaOH played a key role in tailoring the thickness of the nanosheets and changing the morphology of the product. This report may be helpful to constructing fine-tune hierarchical CuO nanostructures under basic conditions.
文摘Virtual assembly is a Virtual Reality (VR) based engineering application which allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. To model the virtual assembly process, new methodology must be applied. Based on the idea that the virtual assembly system is an event driven system, the interactive behavior and information model is proposed to describe the dynamic process of virtual assembly. Definition of the object-oriented model of virtual assembly is put forward.
基金the National Key R&D Program of China(2019YFD1101200,2019YFD1101204)Natural Science Foundation of China(51772150)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Jiangsu Provincial Key Research and Development Program(BE2018008-1).
文摘The graphene oxide powder(GOP)obtained from the spray drying process often exhibits poor redispersibility which is considered due to the partial reduction of GO sheets.The reduction of drying temperature can effectively increase the redispersibility of GOP,but result in a decreased drying efficiency.Herein,we found that the redispersibility of GOP is strongly affected by its microstructure,which is determined by the feed concentration.With the increase of feed concentration,the GO nanosheet assembly varies from the disordered stacking to relatively oriented assembly,making the morphology of the GOP transform from balllike(the most crumpled one)to flakelike(the least crumpled one),and the 0.8 mgml 1 is the threshold concentration for the morphology,structure,and redispersibility change.Once the feed concentration reaches 0.8 mg ml 1,the appearance of the nematic phase in droplet ensures the relatively oriented assembly of GO sheets to form the layered structure with a low crumpling degree,which greatly improves the polar parts surface tension of the solid GOP,making the GOP easier to form hydrogen bonding with water during the redispersion process,thus stabilizing dispersion.This work provides useful information for understanding the relationships between the morphology,microstructure,and final redispersibility of GOPs.
