This study investigates a metal laser direct-writing additive manufacturing process for potential in-space applications.The feasibility of stable deposition under various gravitational conditions—specifically at angl...This study investigates a metal laser direct-writing additive manufacturing process for potential in-space applications.The feasibility of stable deposition under various gravitational conditions—specifically at angles of 0°,90°,and 180°between the deposition direction and gravitational acceleration,and under zero-gravity—is demonstrated.The analysis reveals that a stable metal deposition layer can be formed under different gravity conditions by establishing a strong liquid bridge connection with the substrate;however,the direction of gravitational acceleration significantly affects the cross-sectional morphology of the deposition layer.By comparing different parameters,it is found that the best cross-sectional morphology can be obtained when the wire feeding speed is 120 mm/min and the ratio to the moving speed is 1.0.Notably,a higher wire feeding rate correlates with an increased temperature gradient within the heat-affected zone.On this basis,a thin-walled cylindrical piece printed at a 90°angle between the deposition gravity directions exhibits an outer surface cylindricity of 0.294mm,a size deviation range of-0.168 mm to 0.126 mm,a maximum size deviation of 0.168 mm on the outer surface,and a surface roughness of less than 8.142μm.The results indicate that this process produces printed parts with high surface quality and geometric accuracy.Tensile tests on the printed parts demonstrate that they possess excellent mechanical properties.This study provides valuable insights and a meaningful exploration of future in-orbit metal manufacturing.展开更多
Bioinspired Multi-Metal Structures(MMSs)combine distinct properties of multiple materials,benefiting from improved properties and providing superior designs.Additive Manufacturing(AM)exhibits enormous advantages in ap...Bioinspired Multi-Metal Structures(MMSs)combine distinct properties of multiple materials,benefiting from improved properties and providing superior designs.Additive Manufacturing(AM)exhibits enormous advantages in applying different materials and geometries according to the desired functions at specific locations of the structure,having great potential in fabricating multi-materials structures.However,current AM techniques have difficulty manufacturing 3D MMSs without material cross-contamination flexibly and reliably.This study demonstrates a reliable,fast,and flexible direct ink writing method to fabricate 3D MMSs.The in-situ material-switching system enables the deposition of multiple metallic materials across different layers and within the same layer.3D Fe-Cu MMSs with complex geometries and fine details are fabricated as proof of concept.The microstructures,chemical and phase compositions,and tensile fracture surfaces of the Fe-Cu interfaces indicate a well-bonded interface without cracks,delamination,or material cross-contamination.We envision this novel method making other metallic combinations and even metal-ceramic components.It paves the way for manufacturing 3D MMSs using AM and establishes the possibilities of numerous MMSs applications in engineering fields.展开更多
Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and app...Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and applying ~100 fs oscillator operating at 517 nm wavelength and 76 MHz repetition rate. The proof of concept was experimentally demonstrated and benchmarking 3D woodpile nanostructures, micro-scaffolds, free-form micro-object “Benchy” and bulk micro-cubes are successfully produced. The essential novelty underlies the fact that non-amplified laser systems delivering just 40-500 p J individual pulses are sufficient for inducing localized cross-linking reactions within hundreds of nanometers in cross sections. And it is opposed to the prejudice that higher pulse energies and lower repetition rates of amplified lasers are necessary for structuring non-photosensitized polymers. The experimental work is of high importance for fundamental understanding of laser enabled nanoscale 3D additive manufacturing and widens technology’ s field of applications where the avoidance of photo-initiator is preferable or is even a necessity, such as micro-optics, nano-photonics, and biomedicine.展开更多
Academic writing is social interaction between writer and reader,during which writers can employ discursive and non-discursive features to construct their identities.However,many student writers who are users of Engli...Academic writing is social interaction between writer and reader,during which writers can employ discursive and non-discursive features to construct their identities.However,many student writers who are users of English as an additional language(EAL)may find it challenging to construct their identities in academic writing.Properly constructed identity in academic writing can help EAL student writers develop a stronger sense of self,exercise their agency,and negotiate the academic discourse.Therefore,this paper reviews empirical studies on EAL student writers'identity construction when they write in English to investigate the features of identities that EAL student writers construct in texts and the factors that influence their identity construction.The findings show that,compared with expert writers and native-English-speaking(NES)counterparts,EAL student writers tend to present a weak authorial identity.Furthermore,EAL student writers tend to be more engaged with texts than with readers and lack commitment to their claims.The identities that EAL student writers construct in academic writing are also interwoven with EAL students'English proficiency levels,educational experience,disciplinary conventions,genre affordances,and audience awareness.The findings of this literature review can help teachers and educators raise EAL students’identity awareness and facilitate students in strategically constructing writer identities in academic writing.展开更多
Textiles,integral to human life for centuries,have recently garnered significant interest for electronic applications.However,traditional fabrication methods for electronic textiles(E-textiles)are typically complex.Th...Textiles,integral to human life for centuries,have recently garnered significant interest for electronic applications.However,traditional fabrication methods for electronic textiles(E-textiles)are typically complex.This research introduces an innovative approach utilizing Direct Ink Writing(DIW)3D printing to develop multifunctional wearable electronic textiles.Specifically,the study addresses the creation of a strain sensor and an interconnect electrode directly printed onto textile substrates.The DIWprinted strain sensor exhibited excellent sensitivity,achieving a gauge factor of 11.07,significant linearity(R^(2)~0.99),and consistent performance under repeated mechanical stress.Additionally,the interconnect electrode was engineered to selectively bridge textile layers through controlled impregnation,resulting in stable resistance values(0.2-0.4Ω)under strain and pressure.These components were effectively incorporated into smart garments,facial masks,and multilayered gloves,enabling precise real-time monitoring of body movements,respiration,and tactile recognition,thus significantly advancing functionality and versatility in wearable electronics.展开更多
Multi-photon three-dimensional(3D)nanoprinting technology,renowned for its 3D processing capability and nano-scale resolution beyond the diffraction limit,has garnered significant attention in the micro/nano-additive ...Multi-photon three-dimensional(3D)nanoprinting technology,renowned for its 3D processing capability and nano-scale resolution beyond the diffraction limit,has garnered significant attention in the micro/nano-additive manufacturing field.This technology finds widespread applications in optics,biology,and mechanical engineering research.However,its broader adoption in industrial production and applications has been hindered by limitations such as relatively slow processing speed and restricted material formability and functionality.This paper presents the latest advancements in multi-photon 3D nanoprinting,with a focus on analyzing optical methods to enhance the processing speed of scanning and projection techniques.Additionally,it examines issues related to the formability and functionality of commonly used photosensitive materials,including organic polymers,inorganic compounds,and composite materials.In conclusion,this paper offers a comprehensive summary from the perspectives of productivity,cost,materials,and cross-scale processing,along with proposed routes and future directions.展开更多
文摘This study investigates a metal laser direct-writing additive manufacturing process for potential in-space applications.The feasibility of stable deposition under various gravitational conditions—specifically at angles of 0°,90°,and 180°between the deposition direction and gravitational acceleration,and under zero-gravity—is demonstrated.The analysis reveals that a stable metal deposition layer can be formed under different gravity conditions by establishing a strong liquid bridge connection with the substrate;however,the direction of gravitational acceleration significantly affects the cross-sectional morphology of the deposition layer.By comparing different parameters,it is found that the best cross-sectional morphology can be obtained when the wire feeding speed is 120 mm/min and the ratio to the moving speed is 1.0.Notably,a higher wire feeding rate correlates with an increased temperature gradient within the heat-affected zone.On this basis,a thin-walled cylindrical piece printed at a 90°angle between the deposition gravity directions exhibits an outer surface cylindricity of 0.294mm,a size deviation range of-0.168 mm to 0.126 mm,a maximum size deviation of 0.168 mm on the outer surface,and a surface roughness of less than 8.142μm.The results indicate that this process produces printed parts with high surface quality and geometric accuracy.Tensile tests on the printed parts demonstrate that they possess excellent mechanical properties.This study provides valuable insights and a meaningful exploration of future in-orbit metal manufacturing.
基金National Natural Science Foundation of China,China(Grant ID:52105343 and 52021003)China Postdoctoral Science Foundation,China(Grant ID:2021M701387 and 2022T150259)Department of Science and Technology of Jilin Province,China(Grant ID:2020122214JC).
文摘Bioinspired Multi-Metal Structures(MMSs)combine distinct properties of multiple materials,benefiting from improved properties and providing superior designs.Additive Manufacturing(AM)exhibits enormous advantages in applying different materials and geometries according to the desired functions at specific locations of the structure,having great potential in fabricating multi-materials structures.However,current AM techniques have difficulty manufacturing 3D MMSs without material cross-contamination flexibly and reliably.This study demonstrates a reliable,fast,and flexible direct ink writing method to fabricate 3D MMSs.The in-situ material-switching system enables the deposition of multiple metallic materials across different layers and within the same layer.3D Fe-Cu MMSs with complex geometries and fine details are fabricated as proof of concept.The microstructures,chemical and phase compositions,and tensile fracture surfaces of the Fe-Cu interfaces indicate a well-bonded interface without cracks,delamination,or material cross-contamination.We envision this novel method making other metallic combinations and even metal-ceramic components.It paves the way for manufacturing 3D MMSs using AM and establishes the possibilities of numerous MMSs applications in engineering fields.
基金Project(S-MIP-20-17) supported by the Research Council of LithuaniaProject(871124) supported by the EU Horizon 2020, Research and Innovation program LASERLAB-EUROPE JRA。
文摘Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and applying ~100 fs oscillator operating at 517 nm wavelength and 76 MHz repetition rate. The proof of concept was experimentally demonstrated and benchmarking 3D woodpile nanostructures, micro-scaffolds, free-form micro-object “Benchy” and bulk micro-cubes are successfully produced. The essential novelty underlies the fact that non-amplified laser systems delivering just 40-500 p J individual pulses are sufficient for inducing localized cross-linking reactions within hundreds of nanometers in cross sections. And it is opposed to the prejudice that higher pulse energies and lower repetition rates of amplified lasers are necessary for structuring non-photosensitized polymers. The experimental work is of high importance for fundamental understanding of laser enabled nanoscale 3D additive manufacturing and widens technology’ s field of applications where the avoidance of photo-initiator is preferable or is even a necessity, such as micro-optics, nano-photonics, and biomedicine.
文摘Academic writing is social interaction between writer and reader,during which writers can employ discursive and non-discursive features to construct their identities.However,many student writers who are users of English as an additional language(EAL)may find it challenging to construct their identities in academic writing.Properly constructed identity in academic writing can help EAL student writers develop a stronger sense of self,exercise their agency,and negotiate the academic discourse.Therefore,this paper reviews empirical studies on EAL student writers'identity construction when they write in English to investigate the features of identities that EAL student writers construct in texts and the factors that influence their identity construction.The findings show that,compared with expert writers and native-English-speaking(NES)counterparts,EAL student writers tend to present a weak authorial identity.Furthermore,EAL student writers tend to be more engaged with texts than with readers and lack commitment to their claims.The identities that EAL student writers construct in academic writing are also interwoven with EAL students'English proficiency levels,educational experience,disciplinary conventions,genre affordances,and audience awareness.The findings of this literature review can help teachers and educators raise EAL students’identity awareness and facilitate students in strategically constructing writer identities in academic writing.
基金supported by the Ministry of Trade,Industry&Energy(MOTIE,RS-2023-00258591)National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2019-NR040066)National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00407084).
文摘Textiles,integral to human life for centuries,have recently garnered significant interest for electronic applications.However,traditional fabrication methods for electronic textiles(E-textiles)are typically complex.This research introduces an innovative approach utilizing Direct Ink Writing(DIW)3D printing to develop multifunctional wearable electronic textiles.Specifically,the study addresses the creation of a strain sensor and an interconnect electrode directly printed onto textile substrates.The DIWprinted strain sensor exhibited excellent sensitivity,achieving a gauge factor of 11.07,significant linearity(R^(2)~0.99),and consistent performance under repeated mechanical stress.Additionally,the interconnect electrode was engineered to selectively bridge textile layers through controlled impregnation,resulting in stable resistance values(0.2-0.4Ω)under strain and pressure.These components were effectively incorporated into smart garments,facial masks,and multilayered gloves,enabling precise real-time monitoring of body movements,respiration,and tactile recognition,thus significantly advancing functionality and versatility in wearable electronics.
基金financially supported by the National Key Research and Development Program of China(2021YFF0502700)the National Natural Science Foundation of China(52275429 and 62205117)+4 种基金the Innovation Project of Optics Valley Laboratory(OVL2021ZD002)the Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)the West Light Foundation of the Chinese Academy of Sciences(xbzg-zdsys-202206)the Knowledge Innovation Program of Wuhan-Shuguangthe Hubei Provincial Natu-ral Science Foundation of China(2022CFB792).
文摘Multi-photon three-dimensional(3D)nanoprinting technology,renowned for its 3D processing capability and nano-scale resolution beyond the diffraction limit,has garnered significant attention in the micro/nano-additive manufacturing field.This technology finds widespread applications in optics,biology,and mechanical engineering research.However,its broader adoption in industrial production and applications has been hindered by limitations such as relatively slow processing speed and restricted material formability and functionality.This paper presents the latest advancements in multi-photon 3D nanoprinting,with a focus on analyzing optical methods to enhance the processing speed of scanning and projection techniques.Additionally,it examines issues related to the formability and functionality of commonly used photosensitive materials,including organic polymers,inorganic compounds,and composite materials.In conclusion,this paper offers a comprehensive summary from the perspectives of productivity,cost,materials,and cross-scale processing,along with proposed routes and future directions.
