Sintering and coking are critical barriers to achieving high performance in dry reforming of methane(DRM)catalysts.A finely dispersed and thermostable Ni-based catalyst is the key to address these issues.By leveraging...Sintering and coking are critical barriers to achieving high performance in dry reforming of methane(DRM)catalysts.A finely dispersed and thermostable Ni-based catalyst is the key to address these issues.By leveraging the intrinsic superiorities of high-entropy oxides in high-temperature stability and low atomic diffusivity,in this study,a highly dispersed Ni-based catalyst is synthesized via an entropycontrolled exsolution of active components.By increasing the number of transition-metal elements in spinel oxides,the active metalsupport interaction(MSI)can be continuously strengthened,which controls the exsolution and thermal stability of Ni-based active metal in harsh reaction conditions of DRM.An optimized medium-entropy spinel(Mg_(0.4)Ni_(0.2)Co_(0.2)Zn_(0.2))Al_(2)O_(4)with the exsolution of finely dispersed Ni–Co nanoparticles displayed superior activity and stability in thermal DRM at 800°C and photothermal DRM.This entropy-controlled MSI and exsolution principle provides a significant strategy for designing robust catalysts resistant to sintering and coking for high-temperature reactions like DRM in thermal and photothermal systems.展开更多
In this study, austenitic stainless steel(ASS) was additively fabricated by an arc-based direct energy deposition(DED) technique. Macrostructure, microstructure, mechanical characteristics at different spatial orienta...In this study, austenitic stainless steel(ASS) was additively fabricated by an arc-based direct energy deposition(DED) technique. Macrostructure, microstructure, mechanical characteristics at different spatial orientations(0°, 90°, and 45°), and wear characteristics were evaluated at the deposited structure top, middle, and bottom regions. Results show that austenite(γ) and delta-ferrite(δ) phases make up most of the microstructure of additively fabricated SS316LSi steel. Within γ matrix, δ phase is dispersed both(within and along) grain boundaries, exhibiting a fine vermicular morphology. The bottom, middle,and top regions of WAAM deposited ASS exhibit similar values to those of wrought SS316L in the tensile and impact test findings. Notably, a drop in hardness values is observed as build height increases. During SEM examinations of fractured surfaces from tensile specimen, closed dimples were observed, indicating good ductility of as-built structure. Wear test findings show signs of mild oxidation and usual adhesive wear. By depositing a mechanically mixed composite layer, an increase in the oxidation percentage was discovered to facilitate healing of worn surfaces. The findings of this study will help in design, production and renovation of products/components that are prone to wear. WAAM-deposited ASS has remarkable strength and ability to withstand impacts;it can be used in the production of armour plates for defence applications, mainly military vehicles and aircraft.展开更多
Laser additive manufacturing(LAM) of tungsten carbide metal matrix composites(MMCs) has been evaluated for surface modification of hot die forming tools,cutting edges,glass tooling,extrusion mandrels,and other abrasiv...Laser additive manufacturing(LAM) of tungsten carbide metal matrix composites(MMCs) has been evaluated for surface modification of hot die forming tools,cutting edges,glass tooling,extrusion mandrels,and other abrasive wear applications.This work focuses on transitions from tool steels to MMCs through a single pass laser powder deposition operation.Issues related to the application of various metal powders and carbides used include surface hardness,porosity,cracking,and dilution.These issues along with factory results that were obtained during this project are discussed.展开更多
In order to solve the problem of automatic defect detection and process control in the welding and arc additive process,the paper monitors the current,voltage,audio,and other data during the welding process and extrac...In order to solve the problem of automatic defect detection and process control in the welding and arc additive process,the paper monitors the current,voltage,audio,and other data during the welding process and extracts the minimum value,standard deviation,deviation from the voltage and current data.It extracts spectral features such as root mean square,spectral centroid,and zero-crossing rate from audio data,fuses the features extracted from multiple sensor signals,and establishes multiple machine learning supervised and unsupervised models.They are used to detect abnormalities in the welding process.The experimental results show that the established multiple machine learning models have high accuracy,among which the supervised learning model,the balanced accuracy of Ada boost is 0.957,and the unsupervised learning model Isolation Forest has a balanced accuracy of 0.909.展开更多
Heat treatment is crucial for the optimization of additively manufactured components.Laser-powder bedfused(L-PBFed) magnesium-rare earth(Mg-RE) alloys are highly suitable for lightweight engineering applications becau...Heat treatment is crucial for the optimization of additively manufactured components.Laser-powder bedfused(L-PBFed) magnesium-rare earth(Mg-RE) alloys are highly suitable for lightweight engineering applications because of their high specific strengths and top-down fabrication.However,L-PBFed Mg-RE alloys have unique non-equilibrium features that cause difficulty in the context of conventional heat treatments based on equilibrium phase diagrams or quasi-equilibrium solidification;these challenges severely limit their performance.This study systematically reveals the unique governing mechanism of the solution-treatment temperature over the precipitation evolution and age-hardening responses of L-PBFed WE43 alloy.The results indicate grain coarsening and increased heterogeneity following solution treatment.Under a low solution heat-treatment temperature(400℃),the in-situ phases partially dissolve but coarse Mg41Nd2Y phases form;under a high solution heat-treatment temperature(500℃),the precipitates dissolve but the nucleation site density decreases through excessive defect annihilation.Under optimized solution treatment(450℃),a defect network is retained via lattice distortions,which enables nucleation of shearable β'/β1 phases and stacking faults(SFs) during aging.These shearable β'/β1 phases and SFs impede the dislocations,as an anti-phase boundary energy barrier is established,causing dislocation accumulation and strong strain gradients at the interfaces.Consequently,optimized solution treatment coupled with aging heat treatment yields stronger precipitation strengthening and heterodeformation-induced strengthening owing to the higher density of shearable micro structures and growing grain-size heterogeneity.This work elucidates solute-defect coupling in L-PBFed WE43 solution aging and provides new insights for the heat treatment of L-PBFed Mg-RE alloys.展开更多
In recent years,bone tissue engineering has emerged as a promising solution to the limitations of current gold standard treatment options for bone related-disorders such as bone grafts.Bone tissue engineering provides...In recent years,bone tissue engineering has emerged as a promising solution to the limitations of current gold standard treatment options for bone related-disorders such as bone grafts.Bone tissue engineering provides a scaffold design that mimics the extracellular matrix,providing an architecture that guides the natural bone regeneration process.During this period,a new generation of bone tissue engineering scaffolds has been designed and characterized that explores the incorporation of signaling molecules in order to enhance cell recruitment and ingress into the scaffold,as well as osteogenic differentiation and angiogenesis,each of which is crucial to successful bone regeneration.Here,we outline and critically analyze key characteristics of successful bone tissue engineering scaffolds.We also explore candidate materials used to fabricate these scaffolds.Different growth factors involved in the highly coordinated process of bone repair are discussed,and the key requirements of a growth factor delivery system are described.Finally,we concentrate on an analysis of scaffold-based growth factor delivery strategies found in the recent literature.In particular,the incorporation of two-phase systems consisting of growth factor-loaded nanoparticles embedded into scaffolds shows great promise,both by providing sustained release over a therapeutically relevant timeframe and the potential to sequentially deliver multiple growth factors.展开更多
In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)monitoring.The leech-inspired suction mechanism generated a local ...In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)monitoring.The leech-inspired suction mechanism generated a local soft vacuum facilitating appropriate contact with the human skin.Subsequently,an electrocardiogram(ECG)sensor,termed a leech-inspired origami(LIO)sensor,was constructed using the developed dry electrode.The LIO with a sensing robot system ensures reliable ECG signals with a signal-to-noise ratio of 21.7±0.56 dB.From the paired detection of ECG and photoplethysmography(PPG)through human-robot interaction,BP monitoring was demonstrated.The average difference of the systolic BP between that estimated by the sensing robot and that monitored by the sphygmomanometer was 0.03 mmHg,indicating the reliable BP monitoring ability of the sensing robot.The LIO sensing system inspired by origami and leech behaviors makes BP sensing tools feasible,which in turn would further the development of a remote healthcare monitoring robotic system.展开更多
A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports biomechanics.While pressure sensors have been studied extensively,battery-free functions working in wirel...A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports biomechanics.While pressure sensors have been studied extensively,battery-free functions working in wireless detection have not been studied much.Here,we report a 3D-structured origami-based architecture sensor for wireless pressure monitoring.We developed an architectured platform for wireless pressure sensing through inductorcapacitor(LC)sensors and a monopole antenna.A personalized smart insole with Miura-ori origami designs has been 3D printed together with conductive 3D printed sensors seamlessly.Wireless monitoring of resonant frequency and intensity changes of LC sensors have been demonstrated to monitor foot pressure for different postures.The sensitivity of the wireless pressure sensor is tunable from 15.7 to 2.1 MHz/kPa in the pressure ranges from 0 to 9 kPa and from 10 to 40 kPa,respectively.The proposed wireless pressure-sensing platform can be utilized for various applications such as orthotics,prosthetics,and sports gear.展开更多
We present here a 3D-printed pressure mapping mat,equipped with customizable architecture sensors,that offers a cost-effective and adaptable solution,overcoming the size constraints and sensing accuracy issues commonl...We present here a 3D-printed pressure mapping mat,equipped with customizable architecture sensors,that offers a cost-effective and adaptable solution,overcoming the size constraints and sensing accuracy issues commonly associated with existing commercial pressure mats across various fields,such as healthcare and sports applications.Leveraging a pillar-origami structure,the demonstrated sensor offers multifaceted stiffness properties,effectively filtering skin deformations and enabling capacitive pressure sensing.Notably,the sensor’s detection range can be finely tuned,spanning from 70 to 2500 kPa,with a sensitivity range between 0.01 kPa^(−1) and 0.0002 kPa^(−1),and an impressive response time of just 800 milliseconds.Furthermore,the inclusion of a modular sensor array enhances maintenance and allows for greater flexibility in shaping and enhancing the device’s resolution.This technology finds practical applications in wireless foot pressure mapping and sports protection pads,marking a significant milestone in the advancement of flexible and custom-shaped pressure sensor technology.展开更多
基金supported by the National Key R&D Program of China(2023YFB4104600)National Natural Science Foundation of China(52572313)+1 种基金Tangshan Talent Funding Project(A202202007)Shenzhen Science and Technology Innovation Commission under Grant No.20231120185819001。
文摘Sintering and coking are critical barriers to achieving high performance in dry reforming of methane(DRM)catalysts.A finely dispersed and thermostable Ni-based catalyst is the key to address these issues.By leveraging the intrinsic superiorities of high-entropy oxides in high-temperature stability and low atomic diffusivity,in this study,a highly dispersed Ni-based catalyst is synthesized via an entropycontrolled exsolution of active components.By increasing the number of transition-metal elements in spinel oxides,the active metalsupport interaction(MSI)can be continuously strengthened,which controls the exsolution and thermal stability of Ni-based active metal in harsh reaction conditions of DRM.An optimized medium-entropy spinel(Mg_(0.4)Ni_(0.2)Co_(0.2)Zn_(0.2))Al_(2)O_(4)with the exsolution of finely dispersed Ni–Co nanoparticles displayed superior activity and stability in thermal DRM at 800°C and photothermal DRM.This entropy-controlled MSI and exsolution principle provides a significant strategy for designing robust catalysts resistant to sintering and coking for high-temperature reactions like DRM in thermal and photothermal systems.
基金Science&Engineering Research Board(SERB),DST,for its financial assistance received from the project(vide sanction order no.SPG/2021/003383)。
文摘In this study, austenitic stainless steel(ASS) was additively fabricated by an arc-based direct energy deposition(DED) technique. Macrostructure, microstructure, mechanical characteristics at different spatial orientations(0°, 90°, and 45°), and wear characteristics were evaluated at the deposited structure top, middle, and bottom regions. Results show that austenite(γ) and delta-ferrite(δ) phases make up most of the microstructure of additively fabricated SS316LSi steel. Within γ matrix, δ phase is dispersed both(within and along) grain boundaries, exhibiting a fine vermicular morphology. The bottom, middle,and top regions of WAAM deposited ASS exhibit similar values to those of wrought SS316L in the tensile and impact test findings. Notably, a drop in hardness values is observed as build height increases. During SEM examinations of fractured surfaces from tensile specimen, closed dimples were observed, indicating good ductility of as-built structure. Wear test findings show signs of mild oxidation and usual adhesive wear. By depositing a mechanically mixed composite layer, an increase in the oxidation percentage was discovered to facilitate healing of worn surfaces. The findings of this study will help in design, production and renovation of products/components that are prone to wear. WAAM-deposited ASS has remarkable strength and ability to withstand impacts;it can be used in the production of armour plates for defence applications, mainly military vehicles and aircraft.
基金Supported by the U.S. Department of Energy(DOE),Office of Industrial Technology under contract DE-PS0703ID14425:Industrial Materials for the Future Program and through contracts with Spirex Corporation and Owens-Illinois
文摘Laser additive manufacturing(LAM) of tungsten carbide metal matrix composites(MMCs) has been evaluated for surface modification of hot die forming tools,cutting edges,glass tooling,extrusion mandrels,and other abrasive wear applications.This work focuses on transitions from tool steels to MMCs through a single pass laser powder deposition operation.Issues related to the application of various metal powders and carbides used include surface hardness,porosity,cracking,and dilution.These issues along with factory results that were obtained during this project are discussed.
文摘In order to solve the problem of automatic defect detection and process control in the welding and arc additive process,the paper monitors the current,voltage,audio,and other data during the welding process and extracts the minimum value,standard deviation,deviation from the voltage and current data.It extracts spectral features such as root mean square,spectral centroid,and zero-crossing rate from audio data,fuses the features extracted from multiple sensor signals,and establishes multiple machine learning supervised and unsupervised models.They are used to detect abnormalities in the welding process.The experimental results show that the established multiple machine learning models have high accuracy,among which the supervised learning model,the balanced accuracy of Ada boost is 0.957,and the unsupervised learning model Isolation Forest has a balanced accuracy of 0.909.
基金financially supported by the National Natural Science Foundation of China(Nos.52201105 and 52475324)the National Key Research and Development Program of China(Nos.2023YFB3408003 and 2023YFB3308001)+6 种基金the New Chongqing Youth Innovative Talents Project(No.2024NSCQQNCXX0342)Chongqing Technology Innovation and Application Development Special Major Project(No.CSTB2024TIADSTX0016)the National Foreign Expert Project(No.H20240161)Innovation Support Program for Overseas Returnees in Chongqing(No.cx2023061)the Research Project from Chongqing Key Laboratory of High-performance Structural Additive Manufacturing(No.02090011044158)Chengdu Key Research and Development Support Program(No.2023-YF11-00077-HZ)the Fundamental Research Foundation for the Central Universities in China(Nos.2024IAISQN012 and 2023CDJKYJH049)
文摘Heat treatment is crucial for the optimization of additively manufactured components.Laser-powder bedfused(L-PBFed) magnesium-rare earth(Mg-RE) alloys are highly suitable for lightweight engineering applications because of their high specific strengths and top-down fabrication.However,L-PBFed Mg-RE alloys have unique non-equilibrium features that cause difficulty in the context of conventional heat treatments based on equilibrium phase diagrams or quasi-equilibrium solidification;these challenges severely limit their performance.This study systematically reveals the unique governing mechanism of the solution-treatment temperature over the precipitation evolution and age-hardening responses of L-PBFed WE43 alloy.The results indicate grain coarsening and increased heterogeneity following solution treatment.Under a low solution heat-treatment temperature(400℃),the in-situ phases partially dissolve but coarse Mg41Nd2Y phases form;under a high solution heat-treatment temperature(500℃),the precipitates dissolve but the nucleation site density decreases through excessive defect annihilation.Under optimized solution treatment(450℃),a defect network is retained via lattice distortions,which enables nucleation of shearable β'/β1 phases and stacking faults(SFs) during aging.These shearable β'/β1 phases and SFs impede the dislocations,as an anti-phase boundary energy barrier is established,causing dislocation accumulation and strong strain gradients at the interfaces.Consequently,optimized solution treatment coupled with aging heat treatment yields stronger precipitation strengthening and heterodeformation-induced strengthening owing to the higher density of shearable micro structures and growing grain-size heterogeneity.This work elucidates solute-defect coupling in L-PBFed WE43 solution aging and provides new insights for the heat treatment of L-PBFed Mg-RE alloys.
基金This work was supported by the National Institutes of Health Grant R01-EB022025the UT-Portugal Collaborative Research program(CoLAB)Intelligent scaffolds for molecular recognition of advanced applications in regenerative medicine.
文摘In recent years,bone tissue engineering has emerged as a promising solution to the limitations of current gold standard treatment options for bone related-disorders such as bone grafts.Bone tissue engineering provides a scaffold design that mimics the extracellular matrix,providing an architecture that guides the natural bone regeneration process.During this period,a new generation of bone tissue engineering scaffolds has been designed and characterized that explores the incorporation of signaling molecules in order to enhance cell recruitment and ingress into the scaffold,as well as osteogenic differentiation and angiogenesis,each of which is crucial to successful bone regeneration.Here,we outline and critically analyze key characteristics of successful bone tissue engineering scaffolds.We also explore candidate materials used to fabricate these scaffolds.Different growth factors involved in the highly coordinated process of bone repair are discussed,and the key requirements of a growth factor delivery system are described.Finally,we concentrate on an analysis of scaffold-based growth factor delivery strategies found in the recent literature.In particular,the incorporation of two-phase systems consisting of growth factor-loaded nanoparticles embedded into scaffolds shows great promise,both by providing sustained release over a therapeutically relevant timeframe and the potential to sequentially deliver multiple growth factors.
基金supported by the Discovery and Discovery Accelerator Supplement Grant 2016-04334funded by the Natural Sciences and Engineering Research Council of Canada (NSERC)。
文摘In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)monitoring.The leech-inspired suction mechanism generated a local soft vacuum facilitating appropriate contact with the human skin.Subsequently,an electrocardiogram(ECG)sensor,termed a leech-inspired origami(LIO)sensor,was constructed using the developed dry electrode.The LIO with a sensing robot system ensures reliable ECG signals with a signal-to-noise ratio of 21.7±0.56 dB.From the paired detection of ECG and photoplethysmography(PPG)through human-robot interaction,BP monitoring was demonstrated.The average difference of the systolic BP between that estimated by the sensing robot and that monitored by the sphygmomanometer was 0.03 mmHg,indicating the reliable BP monitoring ability of the sensing robot.The LIO sensing system inspired by origami and leech behaviors makes BP sensing tools feasible,which in turn would further the development of a remote healthcare monitoring robotic system.
基金supported by the Discovery and Discovery Accelerator Supplement Grant 2016-04334funded by the Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports biomechanics.While pressure sensors have been studied extensively,battery-free functions working in wireless detection have not been studied much.Here,we report a 3D-structured origami-based architecture sensor for wireless pressure monitoring.We developed an architectured platform for wireless pressure sensing through inductorcapacitor(LC)sensors and a monopole antenna.A personalized smart insole with Miura-ori origami designs has been 3D printed together with conductive 3D printed sensors seamlessly.Wireless monitoring of resonant frequency and intensity changes of LC sensors have been demonstrated to monitor foot pressure for different postures.The sensitivity of the wireless pressure sensor is tunable from 15.7 to 2.1 MHz/kPa in the pressure ranges from 0 to 9 kPa and from 10 to 40 kPa,respectively.The proposed wireless pressure-sensing platform can be utilized for various applications such as orthotics,prosthetics,and sports gear.
基金support from the Natural Sciences and Engineering Research Council of Canada(NSERC)and Hodgson Orthopedic Group.
文摘We present here a 3D-printed pressure mapping mat,equipped with customizable architecture sensors,that offers a cost-effective and adaptable solution,overcoming the size constraints and sensing accuracy issues commonly associated with existing commercial pressure mats across various fields,such as healthcare and sports applications.Leveraging a pillar-origami structure,the demonstrated sensor offers multifaceted stiffness properties,effectively filtering skin deformations and enabling capacitive pressure sensing.Notably,the sensor’s detection range can be finely tuned,spanning from 70 to 2500 kPa,with a sensitivity range between 0.01 kPa^(−1) and 0.0002 kPa^(−1),and an impressive response time of just 800 milliseconds.Furthermore,the inclusion of a modular sensor array enhances maintenance and allows for greater flexibility in shaping and enhancing the device’s resolution.This technology finds practical applications in wireless foot pressure mapping and sports protection pads,marking a significant milestone in the advancement of flexible and custom-shaped pressure sensor technology.
