Variable material screw-based material extrusion(S-MEX)3D printing technology provides a novel approach for fabricating composites with continuous material gradients.Nevertheless,achieving precise alignment between th...Variable material screw-based material extrusion(S-MEX)3D printing technology provides a novel approach for fabricating composites with continuous material gradients.Nevertheless,achieving precise alignment between the process parameters and material compositions is challenging because of fluctuations in the melt rheological state caused by material variations.In this study,an invertible extrusion prediction model for 0-40 wt% short carbon fiber reinforced polyether-ether-ketone(SCF/PEEK)in the S-MEX process was established using an invertible neural network(INN)that demonstrated the capabilities of forward flow rate prediction and inverse process optimization with accuracies of 0.852 and 0.877,respectively.Moreover,a strategy for adjusting the screw speeds using process parameters obtained from the INN was developed to maintain a consistent flow rate during the variable material printing process.Benefiting from uniform flow,the linewidth accuracy was improved by 77%,and the surface roughness was reduced by 51%.Adjusting the process parameters by using an INN offers significant potential for flow rate control and the enhancement of the overall performance of variable material 3D printing.展开更多
Objective:To evaluate the physical properties of commonly used 3D-printed materials and the dose attenuation around a high-dose-rate ^(192)Ir source,in order to provide a reference for selecting appropriate 3D-printed...Objective:To evaluate the physical properties of commonly used 3D-printed materials and the dose attenuation around a high-dose-rate ^(192)Ir source,in order to provide a reference for selecting appropriate 3D-printed materials for brachytherapy.Methods:Fifteen 3D-printed materials(12 non-metallic material and 3 metallic material)were assessed.Each material was fabricated into a wafer with a diameter of 30 mm and thickness of 3 mm using 3D printing.The CT number of each material was measured,and attenuation measurements were conducted with a Valencia skin applicator and well-type ionization chamber.192Ir was used as the radioactive source,and the attenuated ionization charges were normalized against that obtained in the presence of a solid water phantom at the same depth.Results:The CT number of nylon was(-7.78±3.36)HU,closest to water among all materials.The CT numbers of the other 11 non-metallic materials were below 300 HU.Moreover,the CT number of the Al alloy was(1,350.89±374.55)HU,while the CT numbers of the Ti alloy and stainless steel exceeded 2,976 HU,reaching the upper limit of the CT number range.The results of the attenuation measurements were normalized with the solid water phantom.The average attenuation coefficients of a polyamide,epoxy resin,photosensitive resin,carbon fiber,silica gel,Al alloy,Ti alloy,and stainless steel were 1.003,0.994,0.992,0.995,0.995,0.967,0.939,and 0.866,respectively.Conclusions:Among the common 3D-printed materials with a density similar to that of water,nylon exhibited the best performance,while the metallic materials caused significant dose attenuation and exhibited CT number distortion.As a result,care should be taken when metallic materials are used as 3D-printed materials for brachytherapy.展开更多
Biofabrication,also known as bioprinting,has been widely used in the field of biomedicine.The three most important factors in biofabrication are 3D bioprinter,biomaterials to be printed(bioinks),and the printing objec...Biofabrication,also known as bioprinting,has been widely used in the field of biomedicine.The three most important factors in biofabrication are 3D bioprinter,biomaterials to be printed(bioinks),and the printing object(application).This review provides a detailed introduction to the latest research progress in these aspects.In particularly,the bioinks for bioprinting require strict biocompatible requirements.Four typical materials,i.e.metal/alloys,ceramics,polymers,and their composites,were introduced in detail,and their printing process and application scenarios were summarized,respectively.There are many applications of biofabrication in clinical practice.The application of biofabrication in skeletal system,skin and soft tissue,cardiovascular system,digestive system,respiratory system,urinary system,nervous system,plastic surgery and medical aesthetics were briefly introduced.The applications of biofabrication has a wide range of clinical need.Biofabrication is an innovative technology that is expected to further promote the clinical precision treatments.展开更多
This study focused on the production of polypropylene(PP)/silver(Ag)composites via additive manufacturing.This study aimed to enhance the quality of medical-grade PP in material extrusion(MEX)three-dimensional printin...This study focused on the production of polypropylene(PP)/silver(Ag)composites via additive manufacturing.This study aimed to enhance the quality of medical-grade PP in material extrusion(MEX)three-dimensional printing(3DP)by improving its mechanical properties while simultaneously adding antibacterial properties.The latter can find extremely important and versatile properties that are applicable in defense and security domains.PP/Ag nanocomposites were prepared using a novel method based on a reaction occurring while mixing appropriate quantities of the starting polymers and additives,namely polyvinylpyrrolidone(PVP)as the matrix material and silver nitrate(AgNO_(3))as the filler.This process produced three-dimensional(3D)printed filaments,which were then used to create specimens for a series of standardized tests.It was found that the mechanical properties of the nanocomposites were enhanced in relation to pristine PP,especially for the PP matrix with various loadings of AgNO_(3)and PVP,such as 5.0 wt%and 2.5 wt%,respectively.The voids,inclusions,and actual-to-nominal dimensions also showed improved results.The 3DP specimens exhibited a more effective biocidal performance against Staphylococcus aureus than Escherichia coli,which developed an inhibition zone only in the case of PP with filler loading percentages of AgNO_(3)and PVP at 10.0 wt%and 5.0 wt%,respectively Compounds possessing such properties can be beneficial for various applications requiring increased mechanical properties and biocidal capabilities,such as in the Defence or medical industries.展开更多
Ⅳ.Development of Printing Technology i.16 characters guideline and 28 characters guidefine directed the development of China’s printing technology Mr.Fan Muhan chaired 16 characters guideline in September,1982,which...Ⅳ.Development of Printing Technology i.16 characters guideline and 28 characters guidefine directed the development of China’s printing technology Mr.Fan Muhan chaired 16 characters guideline in September,1982,which includes laserphototypesetting,展开更多
According to statistics of Printing and Printing Equipment Industries Association of China (PEIAC), the total output value of printing industry of China in 2007 reached 440 billion RMB , the total output value of prin...According to statistics of Printing and Printing Equipment Industries Association of China (PEIAC), the total output value of printing industry of China in 2007 reached 440 billion RMB , the total output value of printing equipment was展开更多
(connected to the last month’s Print China) V.Regional Economy Regional imbalance appeared in development of China’s printing industry because of impact of gov-
The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to this.Against this background,...The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to this.Against this background,based on the classical Park cement exothermic model of hydration,we propose and construct a numerical model of the first exothermic peak,taking into account the proportions of C_(3)S,C_(3)A and quicklime in particular.The calculated parameters are calibrated by means of relevant published exothermic test data.It is found that this developed model offers a good simulation of the first exothermic peak of hydration for C_(3)S and C_(3)A proportions from 0 to 100% of cement clinker and reflects the effect of quicklime content at 8%-10%.The unique value of this research is provision of an important computational tool for applications that are sensitive to the first exothermic peak of hydration,such as 3D printing.展开更多
Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine.Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to...Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine.Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood vessels.Scaffold-based tissue engineering approaches are effective methods to form new blood vessel tissues.The demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue engineering.Recent advances in 3D printing have facilitated fabrication of vascular scaffolds,contributing to broad prospects for tissue vascularization.This review presents state of the art on modeling methods,print materials and preparation processes for fabrication of vascular scaffolds,and discusses the advantages and application fields of each method.Specially,significance and importance of scaffold-based tissue engineering for vascular regeneration are emphasized.Print materials and preparation processes are discussed in detail.And a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting,electrospinning,and Lego-like construction.And related studies are exemplified.Transformation of vascular scaffolds to clinical application is discussed.Also,four trends of 3D printing of tissue engineering vascular scaffolds are presented,including machine learning,near-infrared photopolymerization,4D printing,and combination of self-assembly and 3D printing-based methods.展开更多
This study aims to understand the distribution of reinforcement material in the matrix,evaluate the adherence between layers,and determine the air gap between printing roads.We printed the specimen with two different ...This study aims to understand the distribution of reinforcement material in the matrix,evaluate the adherence between layers,and determine the air gap between printing roads.We printed the specimen with two different composite materials,Polylactic Acid(PLA)reinforced with acrylic particles,and another filament reinforced with short carbon fibers.For the observations of the samples,we used a Confocal Microscope.We estimated the porosity of the material by comparing the expected mass with that achieved after manufacture.By pixel count,after binarization,we found the average percentage of acrylate particulate.They showed fair distribution through the PLA matrix even after the manufacturing process.The determination of fibers alignment was made by binarization of image,together with k-means and edge detection.This combination of methods allows estimating the fiber alignment by orientation straight lines.The manufacturing process did not offer good alignment of the fibers,even with the filament initially well aligned.展开更多
A new generation of RFID materials with de- signed-in compatibility helps raise quality, reliability and process efficiency If RFID technology is headed for the heights predicted by forecasters, it will require an ong...A new generation of RFID materials with de- signed-in compatibility helps raise quality, reliability and process efficiency If RFID technology is headed for the heights predicted by forecasters, it will require an ongoing evolution of new materials and re- lated technologies to help reduce card/label assembly costs and improve performance. From a materials standpoint, the critical elements in any printed RFID inlay include the chip, the chip attachment method, the antenna,展开更多
The development of efficient and sustainable composites remains a primary objective of both research and industry.In this study,the use of biochar,an eco-friendly reinforcing material,in additive manufacturing(AM)is i...The development of efficient and sustainable composites remains a primary objective of both research and industry.In this study,the use of biochar,an eco-friendly reinforcing material,in additive manufacturing(AM)is investigated.A high-density Polyethylene(HDPE)thermoplastic was used as the matrix,and the material extrusion(MEX)technique was applied for composite production.Biochar was produced from olive tree prunings via conventional pyrolysis at 500°C.Composite samples were created using biochar loadings in the range of 2.0-10.0 wt.%.The 3D-printed samples were mechanically tested in accordance with international standards.Thermogravimetric analysis(TGA)and Raman spectroscopy were used to evaluate the thermal and structural properties of the composites.Scanning electron microscopy was used to examine the fractographic and morphological characteristics of the materials.The electrical/dielectric properties of HDPE/biochar composites were studied over a broad frequency range(10-2 Hz-4 MHz)at room temperature.Overall,a laborious effort with 12 different tests was implemented to fully characterize the developed composites and investigate the correlations between the different qualities.This investigation demonstrated that biochar in the MEX process can be a satisfactory reinforcement agent.Notably,compared to the control samples of pure HDPE,biochar increased the tensile strength by over 20%and flexural strength by 35.9%when added at a loading of 4.0 wt.%.The impact strength and microhardness were also significantly improved.Furthermore,the Direct current(DC)conductivity of insulating HDPE increased by five orders of magnitude at 8.0 wt.%of biochar content,suggesting a percolation threshold.These results highlight the potential of C-based composites for the use in additive manufacturing to further exploit their applicability by providing parts with improved mechanical performance and eco-friendly profiles.展开更多
In recent few years, significant improvement has been made in developing largescale 3 D printer to accommodate the need of industrial-scale 3 D printing. Cementitious materials that are compatible with 3 D printing pr...In recent few years, significant improvement has been made in developing largescale 3 D printer to accommodate the need of industrial-scale 3 D printing. Cementitious materials that are compatible with 3 D printing promote rapid application of this innovative technique in the construction field with advantages of cost effective, high efficiency, design flexibility and environmental friendly. This paper firstly reviews existing 3 D printing techniques that are currently being used in commercial3 D printers. It then summarizes three latest development of largescale 3 D printing systems and identifies their relationships and limiting factors. Thereafter, critical factors that are used to evaluate the workability and printable performance of cementitious materials are specified. Easy-extrusive, easy-flowing, well-buildable, and proper setting time are significant for cementitious material to meet the critical requirements of a freeform construction process. Finally, main advantages, potential applications and the prospects of future research of 3 D printing in construction technology are suggested. The objective of this work is to review current design methodologies and operational constraints of largescale 3 D printing system and provide references for optimizing the performance of cementitious material and promote its responsible use with largescale 3 D printing technology.展开更多
Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as th...Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as the National Additive Manufacturing Innovation Institute,is the nation’s leading and collaborative partner in AM/3DP technology research,discovery,creation,and innovation,working efficiently to innovate and accelerate AM/3DP to increase America’s global manufacturing competitiveness(https://americamakes.us).German展开更多
Flexible thermoelectric materials are presented with potential applications in electronic devices and energy conversion due to their convenient preparation,good flexibility,and various forms.However,as ductility is ra...Flexible thermoelectric materials are presented with potential applications in electronic devices and energy conversion due to their convenient preparation,good flexibility,and various forms.However,as ductility is rarely observed in inorganic semiconductors and ceramic insulators,reports on applications of inorganic oxide materials in flexible thermoelectric materials are sparse.Here,we report a new method for the synthesis of a flexible Na_(1.4)Co_(2)O_(4) thermoelectric material based on Na_(1.4)Co_(2)O_(4) bulk materials,which are prepared by a self-flux method and painted on print paper.Seebeck coefficient and power factor of the obtained thermoelectric material are 78-102 μVK^(-1) and 159e223 mWm^-(1)K^(-2),respectively,in a temperature range of 303-522 K,which are superior to those values of other conductive polymers and their compounds.More interestingly,the n-type Na_(1.4)Co_(2)O_(4) flexible material is obtained in the painting process at higher pressure with Seebeck coefficients of109 to183 μVK^(-1) in a temperature range of 303-522 K.The convenient preparation method of these novel flexible thermoelectric materials may be expanded to the synthesis of other flexible thermoelectric materials,which will be the focus of future work.展开更多
Printed and flexible electronics are definitely promising cutting-edge electronic technologies of the future. They offer a wide-variety of applications such as flexible circuits, flexible displays, flexible solar cell...Printed and flexible electronics are definitely promising cutting-edge electronic technologies of the future. They offer a wide-variety of applications such as flexible circuits, flexible displays, flexible solar cells, skinlike pressure sensors, and radio frequency identification tags in our daily life. As the most-fundamental component of electronics, electrodes are made of conductive materials that play a key role in flexible and printed electronic devices. In this review, various inorganic conductive materials and strategies for obtaining highly conductive and uniform electrodes are demonstrated. Applications of printed electrodes fabricated via these strategies are also described. Nevertheless, there are a number of challenges yet to overcome to optimize the processing and performance of printed electrodes.展开更多
As a physical interface,a prosthetic liner is commonly used as a transition material between the residual limb and the stiff socket.Typically made from a compliant material such as silicone,the main function of a pros...As a physical interface,a prosthetic liner is commonly used as a transition material between the residual limb and the stiff socket.Typically made from a compliant material such as silicone,the main function of a prosthetic liner is to protect the residual limb from injuries induced by load-bearing normal and shear stresses.Compared to conventional liners,custom prosthetic lower-extremity(LE)liners have been shown to better relieve stress concentrations in painful and sensitive regions of the residual limb.Although custom LE liners have been shown to offer clinical benefits,no review article on their design and efficacy has yet been written.To address this shortcoming in the literature,this paper provides a comprehensive survey of custom LE liner materials,design,and fabrication methods.First,custom LE liner materials and components are summarized,including a description of commercial liners and their efficacy.Subsequently,digital methods used to design and fabricate custom LE liners are addressed,including residual limb biomechanical modeling,finite element-based design methods,and 3-D printing techniques.Finally,current evaluation methods of custom/commercial LE liners are presented and discussed.We hope that this review article will inspire further research and development into the design and manufacture of custom LE liners.展开更多
Subject Code:B04Under the financial support of the National Natural Science Foundation of China,the research team led by Prof.Xie Tao(谢涛)at the State Key Laboratory of Chemical Engineering,College of Chemical and Bi...Subject Code:B04Under the financial support of the National Natural Science Foundation of China,the research team led by Prof.Xie Tao(谢涛)at the State Key Laboratory of Chemical Engineering,College of Chemical and Biological Engineering,Zhejiang University,developed an ultrafast process to produce shape changing materials with complex 3Dgeometries.This work was published in Advanced Materials(2016,DOI:10.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.12202547,62461160259)Shaanxi Province Qingchuangyuan“Scientist and Engineering”Team Construction Project(Grant Nos.2022KXJ-102,2022KXJ-106)+1 种基金Fundamental Research Funds for the Central UniversitiesProgram for Innovation Team of Shaanxi Province(Grant No.2023-CX-TD-17).
文摘Variable material screw-based material extrusion(S-MEX)3D printing technology provides a novel approach for fabricating composites with continuous material gradients.Nevertheless,achieving precise alignment between the process parameters and material compositions is challenging because of fluctuations in the melt rheological state caused by material variations.In this study,an invertible extrusion prediction model for 0-40 wt% short carbon fiber reinforced polyether-ether-ketone(SCF/PEEK)in the S-MEX process was established using an invertible neural network(INN)that demonstrated the capabilities of forward flow rate prediction and inverse process optimization with accuracies of 0.852 and 0.877,respectively.Moreover,a strategy for adjusting the screw speeds using process parameters obtained from the INN was developed to maintain a consistent flow rate during the variable material printing process.Benefiting from uniform flow,the linewidth accuracy was improved by 77%,and the surface roughness was reduced by 51%.Adjusting the process parameters by using an INN offers significant potential for flow rate control and the enhancement of the overall performance of variable material 3D printing.
基金supported by grants from the National High Level Hospital Clinical Research Funding(2022-PUMCH-A-101)the National High Level Hospital Clinical Research Funding(2022-PUMCH-B-052),China.
文摘Objective:To evaluate the physical properties of commonly used 3D-printed materials and the dose attenuation around a high-dose-rate ^(192)Ir source,in order to provide a reference for selecting appropriate 3D-printed materials for brachytherapy.Methods:Fifteen 3D-printed materials(12 non-metallic material and 3 metallic material)were assessed.Each material was fabricated into a wafer with a diameter of 30 mm and thickness of 3 mm using 3D printing.The CT number of each material was measured,and attenuation measurements were conducted with a Valencia skin applicator and well-type ionization chamber.192Ir was used as the radioactive source,and the attenuated ionization charges were normalized against that obtained in the presence of a solid water phantom at the same depth.Results:The CT number of nylon was(-7.78±3.36)HU,closest to water among all materials.The CT numbers of the other 11 non-metallic materials were below 300 HU.Moreover,the CT number of the Al alloy was(1,350.89±374.55)HU,while the CT numbers of the Ti alloy and stainless steel exceeded 2,976 HU,reaching the upper limit of the CT number range.The results of the attenuation measurements were normalized with the solid water phantom.The average attenuation coefficients of a polyamide,epoxy resin,photosensitive resin,carbon fiber,silica gel,Al alloy,Ti alloy,and stainless steel were 1.003,0.994,0.992,0.995,0.995,0.967,0.939,and 0.866,respectively.Conclusions:Among the common 3D-printed materials with a density similar to that of water,nylon exhibited the best performance,while the metallic materials caused significant dose attenuation and exhibited CT number distortion.As a result,care should be taken when metallic materials are used as 3D-printed materials for brachytherapy.
基金supported by National Key Research and Development Program of China(Grant Nos.2023YFC2411300,2023YFB4605800)National Natural Science Foundation of China(Grant No.32471474)+2 种基金Sichuan Science and Technology Program(Grant Nos.2024YFHZ0125,2022NSFSC1405)China Postdoctoral Science Foundation(Grant No.2022M722268)Research and Develop Program,West China Hospital of Stomatology Sichuan University(Grant No.RD-03-202406).
文摘Biofabrication,also known as bioprinting,has been widely used in the field of biomedicine.The three most important factors in biofabrication are 3D bioprinter,biomaterials to be printed(bioinks),and the printing object(application).This review provides a detailed introduction to the latest research progress in these aspects.In particularly,the bioinks for bioprinting require strict biocompatible requirements.Four typical materials,i.e.metal/alloys,ceramics,polymers,and their composites,were introduced in detail,and their printing process and application scenarios were summarized,respectively.There are many applications of biofabrication in clinical practice.The application of biofabrication in skeletal system,skin and soft tissue,cardiovascular system,digestive system,respiratory system,urinary system,nervous system,plastic surgery and medical aesthetics were briefly introduced.The applications of biofabrication has a wide range of clinical need.Biofabrication is an innovative technology that is expected to further promote the clinical precision treatments.
文摘This study focused on the production of polypropylene(PP)/silver(Ag)composites via additive manufacturing.This study aimed to enhance the quality of medical-grade PP in material extrusion(MEX)three-dimensional printing(3DP)by improving its mechanical properties while simultaneously adding antibacterial properties.The latter can find extremely important and versatile properties that are applicable in defense and security domains.PP/Ag nanocomposites were prepared using a novel method based on a reaction occurring while mixing appropriate quantities of the starting polymers and additives,namely polyvinylpyrrolidone(PVP)as the matrix material and silver nitrate(AgNO_(3))as the filler.This process produced three-dimensional(3D)printed filaments,which were then used to create specimens for a series of standardized tests.It was found that the mechanical properties of the nanocomposites were enhanced in relation to pristine PP,especially for the PP matrix with various loadings of AgNO_(3)and PVP,such as 5.0 wt%and 2.5 wt%,respectively.The voids,inclusions,and actual-to-nominal dimensions also showed improved results.The 3DP specimens exhibited a more effective biocidal performance against Staphylococcus aureus than Escherichia coli,which developed an inhibition zone only in the case of PP with filler loading percentages of AgNO_(3)and PVP at 10.0 wt%and 5.0 wt%,respectively Compounds possessing such properties can be beneficial for various applications requiring increased mechanical properties and biocidal capabilities,such as in the Defence or medical industries.
文摘Ⅳ.Development of Printing Technology i.16 characters guideline and 28 characters guidefine directed the development of China’s printing technology Mr.Fan Muhan chaired 16 characters guideline in September,1982,which includes laserphototypesetting,
文摘According to statistics of Printing and Printing Equipment Industries Association of China (PEIAC), the total output value of printing industry of China in 2007 reached 440 billion RMB , the total output value of printing equipment was
文摘(connected to the last month’s Print China) V.Regional Economy Regional imbalance appeared in development of China’s printing industry because of impact of gov-
基金financially supported by the National Natural Science Foundation of China(Grant No.52178240)the Shanghai Scientific Research Program(No.21DZ1200401).
文摘The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to this.Against this background,based on the classical Park cement exothermic model of hydration,we propose and construct a numerical model of the first exothermic peak,taking into account the proportions of C_(3)S,C_(3)A and quicklime in particular.The calculated parameters are calibrated by means of relevant published exothermic test data.It is found that this developed model offers a good simulation of the first exothermic peak of hydration for C_(3)S and C_(3)A proportions from 0 to 100% of cement clinker and reflects the effect of quicklime content at 8%-10%.The unique value of this research is provision of an important computational tool for applications that are sensitive to the first exothermic peak of hydration,such as 3D printing.
文摘Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine.Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood vessels.Scaffold-based tissue engineering approaches are effective methods to form new blood vessel tissues.The demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue engineering.Recent advances in 3D printing have facilitated fabrication of vascular scaffolds,contributing to broad prospects for tissue vascularization.This review presents state of the art on modeling methods,print materials and preparation processes for fabrication of vascular scaffolds,and discusses the advantages and application fields of each method.Specially,significance and importance of scaffold-based tissue engineering for vascular regeneration are emphasized.Print materials and preparation processes are discussed in detail.And a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting,electrospinning,and Lego-like construction.And related studies are exemplified.Transformation of vascular scaffolds to clinical application is discussed.Also,four trends of 3D printing of tissue engineering vascular scaffolds are presented,including machine learning,near-infrared photopolymerization,4D printing,and combination of self-assembly and 3D printing-based methods.
文摘This study aims to understand the distribution of reinforcement material in the matrix,evaluate the adherence between layers,and determine the air gap between printing roads.We printed the specimen with two different composite materials,Polylactic Acid(PLA)reinforced with acrylic particles,and another filament reinforced with short carbon fibers.For the observations of the samples,we used a Confocal Microscope.We estimated the porosity of the material by comparing the expected mass with that achieved after manufacture.By pixel count,after binarization,we found the average percentage of acrylate particulate.They showed fair distribution through the PLA matrix even after the manufacturing process.The determination of fibers alignment was made by binarization of image,together with k-means and edge detection.This combination of methods allows estimating the fiber alignment by orientation straight lines.The manufacturing process did not offer good alignment of the fibers,even with the filament initially well aligned.
文摘A new generation of RFID materials with de- signed-in compatibility helps raise quality, reliability and process efficiency If RFID technology is headed for the heights predicted by forecasters, it will require an ongoing evolution of new materials and re- lated technologies to help reduce card/label assembly costs and improve performance. From a materials standpoint, the critical elements in any printed RFID inlay include the chip, the chip attachment method, the antenna,
文摘The development of efficient and sustainable composites remains a primary objective of both research and industry.In this study,the use of biochar,an eco-friendly reinforcing material,in additive manufacturing(AM)is investigated.A high-density Polyethylene(HDPE)thermoplastic was used as the matrix,and the material extrusion(MEX)technique was applied for composite production.Biochar was produced from olive tree prunings via conventional pyrolysis at 500°C.Composite samples were created using biochar loadings in the range of 2.0-10.0 wt.%.The 3D-printed samples were mechanically tested in accordance with international standards.Thermogravimetric analysis(TGA)and Raman spectroscopy were used to evaluate the thermal and structural properties of the composites.Scanning electron microscopy was used to examine the fractographic and morphological characteristics of the materials.The electrical/dielectric properties of HDPE/biochar composites were studied over a broad frequency range(10-2 Hz-4 MHz)at room temperature.Overall,a laborious effort with 12 different tests was implemented to fully characterize the developed composites and investigate the correlations between the different qualities.This investigation demonstrated that biochar in the MEX process can be a satisfactory reinforcement agent.Notably,compared to the control samples of pure HDPE,biochar increased the tensile strength by over 20%and flexural strength by 35.9%when added at a loading of 4.0 wt.%.The impact strength and microhardness were also significantly improved.Furthermore,the Direct current(DC)conductivity of insulating HDPE increased by five orders of magnitude at 8.0 wt.%of biochar content,suggesting a percolation threshold.These results highlight the potential of C-based composites for the use in additive manufacturing to further exploit their applicability by providing parts with improved mechanical performance and eco-friendly profiles.
基金supported by the National Major Research Instrument Development Project of the National Natural Science Foundation of China(51627812)the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology,KFJJ13-11M)
文摘In recent few years, significant improvement has been made in developing largescale 3 D printer to accommodate the need of industrial-scale 3 D printing. Cementitious materials that are compatible with 3 D printing promote rapid application of this innovative technique in the construction field with advantages of cost effective, high efficiency, design flexibility and environmental friendly. This paper firstly reviews existing 3 D printing techniques that are currently being used in commercial3 D printers. It then summarizes three latest development of largescale 3 D printing systems and identifies their relationships and limiting factors. Thereafter, critical factors that are used to evaluate the workability and printable performance of cementitious materials are specified. Easy-extrusive, easy-flowing, well-buildable, and proper setting time are significant for cementitious material to meet the critical requirements of a freeform construction process. Finally, main advantages, potential applications and the prospects of future research of 3 D printing in construction technology are suggested. The objective of this work is to review current design methodologies and operational constraints of largescale 3 D printing system and provide references for optimizing the performance of cementitious material and promote its responsible use with largescale 3 D printing technology.
基金supported by the National Natural Science Foundation of China (51575267 and 51322509)the National Key Research and Development Program ‘‘Additive Manufacturing and Laser Manufacturing’’ (2016YFB1100101)+5 种基金the Top-Notch Young Talents Program of China, the NSFC-DFG Sino-German Research Project (GZ 1217)the Key Research and Development Program of Jiangsu Provincial Department of Science and Technology of China (BE2016181)the 333 High-level Talents Training Project (BRA2015368), the Aeronautical Science Foundation of China (2015ZE52051)the Outstanding Youth Foundation of Jiangsu Province of China (BK20130035)the Program for New Century Excellent Talents in University (NCET-13-0854)the Fundamental Research Funds for the Central Universities (NE2013103, NP2015206 and NZ2016108)
文摘Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as the National Additive Manufacturing Innovation Institute,is the nation’s leading and collaborative partner in AM/3DP technology research,discovery,creation,and innovation,working efficiently to innovate and accelerate AM/3DP to increase America’s global manufacturing competitiveness(https://americamakes.us).German
基金This project was supported by the National Natural Science Foundation of China under the Nos.51702168 and 51927801the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure under the No.SKL201705SICthe Inner Mongolia Engineering Research Center of Multifunctional Copper Materials.
文摘Flexible thermoelectric materials are presented with potential applications in electronic devices and energy conversion due to their convenient preparation,good flexibility,and various forms.However,as ductility is rarely observed in inorganic semiconductors and ceramic insulators,reports on applications of inorganic oxide materials in flexible thermoelectric materials are sparse.Here,we report a new method for the synthesis of a flexible Na_(1.4)Co_(2)O_(4) thermoelectric material based on Na_(1.4)Co_(2)O_(4) bulk materials,which are prepared by a self-flux method and painted on print paper.Seebeck coefficient and power factor of the obtained thermoelectric material are 78-102 μVK^(-1) and 159e223 mWm^-(1)K^(-2),respectively,in a temperature range of 303-522 K,which are superior to those values of other conductive polymers and their compounds.More interestingly,the n-type Na_(1.4)Co_(2)O_(4) flexible material is obtained in the painting process at higher pressure with Seebeck coefficients of109 to183 μVK^(-1) in a temperature range of 303-522 K.The convenient preparation method of these novel flexible thermoelectric materials may be expanded to the synthesis of other flexible thermoelectric materials,which will be the focus of future work.
基金supported by the National Natural Science Foundation of China(Nos.51475093,U1632115)the Science and Technology Commission of Shanghai Municipality(No.14JC1400200)+1 种基金the National Key Technologies R&D Program of China(No.2015ZX02102-003)the Changjiang Young Scholars Programme of China
文摘Printed and flexible electronics are definitely promising cutting-edge electronic technologies of the future. They offer a wide-variety of applications such as flexible circuits, flexible displays, flexible solar cells, skinlike pressure sensors, and radio frequency identification tags in our daily life. As the most-fundamental component of electronics, electrodes are made of conductive materials that play a key role in flexible and printed electronic devices. In this review, various inorganic conductive materials and strategies for obtaining highly conductive and uniform electrodes are demonstrated. Applications of printed electrodes fabricated via these strategies are also described. Nevertheless, there are a number of challenges yet to overcome to optimize the processing and performance of printed electrodes.
基金supported by the Fundamental Research Funds for the Central Universities(Grant number JKF-YG-22-B010)the National Institutes of Health(Grant number 5R01EB024531-03).
文摘As a physical interface,a prosthetic liner is commonly used as a transition material between the residual limb and the stiff socket.Typically made from a compliant material such as silicone,the main function of a prosthetic liner is to protect the residual limb from injuries induced by load-bearing normal and shear stresses.Compared to conventional liners,custom prosthetic lower-extremity(LE)liners have been shown to better relieve stress concentrations in painful and sensitive regions of the residual limb.Although custom LE liners have been shown to offer clinical benefits,no review article on their design and efficacy has yet been written.To address this shortcoming in the literature,this paper provides a comprehensive survey of custom LE liner materials,design,and fabrication methods.First,custom LE liner materials and components are summarized,including a description of commercial liners and their efficacy.Subsequently,digital methods used to design and fabricate custom LE liners are addressed,including residual limb biomechanical modeling,finite element-based design methods,and 3-D printing techniques.Finally,current evaluation methods of custom/commercial LE liners are presented and discussed.We hope that this review article will inspire further research and development into the design and manufacture of custom LE liners.
文摘Subject Code:B04Under the financial support of the National Natural Science Foundation of China,the research team led by Prof.Xie Tao(谢涛)at the State Key Laboratory of Chemical Engineering,College of Chemical and Biological Engineering,Zhejiang University,developed an ultrafast process to produce shape changing materials with complex 3Dgeometries.This work was published in Advanced Materials(2016,DOI:10.
