This paper mainly reviews the designs of electrohydrodynamic (EHD) inkjet printing machine and related applications. The review introduces the features of EHD printing and its possible research ...directions. Significant progress has been identified in research and development of EHD high-resolution printing as a direct additive manufacturing method, and more effort will be driven to this direction soon. An introduction is given about current trend of additive manufacturing and advantages of EHD inkjet printing. Designs of EHD printing platform and applications of different technologies are discussed. Currently, EHD jet printing is in its infancy stage with several inherent problems to be overcome, such as low yielding rate and limitation of stand-off height. Some potential modifications are proposed to improve printing performance. EHD highresolution printing has already been applied to precision components for electronics and biotechnology applications. This paper gives a review about the latest research regarding EHD used for high-resolution inkjet printing. A starting base is given to help researchers and students to get a quick overview on the recent development of EHD printing technology
Zinc-Magnesium (Zn-Mg) alloy as a novel biodegradable metal holds great potential in biodegradable implant applications as it is more corrosion resistant than Magnesium (Mg). However, the mechanical ...properties, biodegradation uniformity, and cytotoxicity of Zn-Mg alloy remained as concerns. In this study, hot extrusion process was applied to Zn-1 wt % Mg (Zn-1Mg) to refine its microstructure. Effects of hot extrusion on biodegradation behavior and mechanical properties of Zn-1Mg were investigated in comparison with Mg rare earth element alloy WE43. Metallurgical analysis revealed significant grain size reduction, and immersion test found that corrosion rates of WE43 and Zn-1Mg were reduced by 35% and 57%, respectively after extrusion. Moreover, hot extrusion resulted in a much more uniform biodegradation in extruded Zn-1Mg alloy and WE43. In vitro cytotoxicity test results indicated that Zn-1Mg alloy was biocompatible. Therefore, hot extruded Zn-1Mg with homogenous microstructure, uniform as well as slow degradation, improved mechanical properties, and good biocompatibility was believed to be an excellent candidate material for load-bearing biodegradable implant application.
The onset of multi-material 3D printing and the combination of smart materials into the printable material has led to the development of an exciting new technology called 4D printing. This paper will ...introduce the background and development into 4D printing, discuss water reactive 4D printing methods and temperature reactive 4D printing, modelling and simulation software, and future applications of this new technology. Smart materials that react to different external stimuli are described, along with the benefits of these smart materials and their potential use in 4D printing applications; specifically, existing light-reactive smart materials. 4D printing has the prospective to simplify the design and manufacturing of different products and the potential of automating actuation devices that naturally react to their environment without the need for human interaction, batteries, processors, sensors, and motors.
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In this study, a comprehensive analysis of a novel zinc alloy osteosynthesis system in a canine mandibular fracture model is presented. The efficacy of the system was compared for ...PLLA (poly-l-lactic acid) and titanium materials using X-ray radiography, micro-CT tomography, undecalcified bone histomorphometry, and a three-point bending test. Histology, blood normal, blood biochemical, and serum zinc concentration tests were also performed to assess the biosafety of the zinc alloy osteosynthesis system. The degradability of the zinc alloy was evaluated using a micro-CT and scanning electron microscope during the 24-week post operation period. The results showed that zinc alloy possesses good mechanical properties that support fracture healing. Its uniform and slow corrosion leads to adequate degradation behavior in 24 weeks. Additionally, the zinc alloy proved to be biocompatible, indicating that this novel osteosynthesis system is safe for use in the body. The results of the study demonstrate that this zinc alloy-based osteosynthesis system is a promising candidate for a new generation of osteosynthesis systems, with further improvements required in the future.
Abstract Multifunctional bone scaffold materials have been produced from a biodegradable polymer, poly( l -lactic acid) (PLLA), and 1–10% wt of octadecylamine-functionalized nanodiamond (ND-ODA) via ...solution casting followed by compression molding. By comparison to pure PLLA, the addition of 10% wt of ND-ODA resulted in a significant improvement of the mechanical properties of the composite matrix, including a 280% increase in the strain at failure and a 310% increase in fracture energy in tensile tests. The biomimetic process of bonelike apatite growth on the ND-ODA/PLLA scaffolds was studied using microscopic and spectroscopic techniques. The enhanced mechanical properties and the increased mineralization capability with higher ND-ODA concentration suggest that these biodegradable composites may potentially be useful for a variety of biomedical applications, including scaffolds for orthopedic regenerative engineering.
4D printing is an emerging additive manufacturing technology that combines the precision of 3D printing with the versatility of smart materials. 4D printed objects can change their shape over time ...with the application of a stimulus (i.e., heat, light, moisture). Light driven smart materials are attractive because light is wireless, remote, and can induce a rapid shape change. Herein, we present a method for fabricating polymeric bilayer actuators via 3D printing which reversibly change their shape upon exposure to light. The photoactive layer consists of a poly(siloxane) containing pendant azobenzene groups. Two different photoactive polymers were synthesized, and the photomechanical effect displayed by the bilayers was evaluated. These bilayers exhibit rapid actuation with full cycles completed within seconds, and photo generated stresses ranging from 1.03 to 1.70 MPa.
•Extruded Zn-0.02 Mg-0.02Cu alloy had superior mechanical properties.•The Zn-based alloy exhibited no toxicity in zebrafish embryos model.•The Zn-based alloy showed good biocompatibility in vivo ...subcutaneous tissue.
In this study, hot extruded pure Zn and Zn-0.02Mg-0.02Cu alloy were prepared. Compared with the pure Zn, the tensile yield strength, ultimate tensile strength and hardness of the Zn-based alloy were significantly improved, reaching 216.29 ± 3.27 MPa, 262.25 ± 5.02 MPa and 74.40 ± 1.84 HV, respectively, satisfying the criteria of biodegradable stents. Electrochemical corrosion and immersion test showed that the corrosion rates of the Zn-based alloy were higher than those of pure Zn. In addition, the Zn-based alloy exhibited excellent biocompatibility for the development of zebrafish embryos and in vivo subcutaneous tissue without severe inflammatory response. These results indicate that the novel Zn-based alloy has a huge potential in cardiovascular stents.
3D printing is an ever growing industry that provides many benefits to the advanced manufacturing and design industry. However, parts tend to be static, rigid, and lack multi-purpose use. Recently, a ...new technology has emerged that uses 3D printing to print parts with the ability to change shape over time when exposed to different external stimuli. This new technology has been called 4D printing. Creation of a new material that is capable of changing shape when exposed to different stimuli and possess the ability to be 3D printed can be a difficult and a long process. Due to this strenuous process, the potential of a common fused deposition modelling material, poly(lactic) acid (PLA), for use in 4D printing is investigated and the concept of combining PLA with nylon fabric for the creation of smart textiles is explored. PLA possesses thermal shape memory behaviour and maintains these abilities when combined with nylon fabric that can be thermomechanically trained into temporary shapes and return to their permanent shapes when heated.
Political communicators work under the assumption that information provision, such as framing, may influence audiences and elicit some desired attitudinal or behavioral shift. However, some political ...issues, such as climate change, have become polarized along party lines, with partisans seemingly impervious to disconfirming information. On these highly polarized issues, can framing sway partisans to moderate their positions, or are partisans so motivated in their issue stances that framing fails? Using a variety of vignettes, and Republican climate change skepticism as a case, this article reports an experiment of how partisans respond to counter-attitudinal framing on a sharply polarized issue. Results indicate that Republicans are resistant to frames that encourage support of governmental action or personal engagement against climate change. There is strong evidence of motivated skepticism, given widespread backfire (or 'boomerang') effects and decreased attitudinal ambivalence following exposure to framing, suggesting that issue polarization may severely constrain attempts at communication.
To reduce the long-term side effects of permanent metallic stents, a new generation of cardiovascular stents called “biodegradable stents” is being extensively developed. Zinc has been considered as ...a promising candidate material for biodegradable cardiovascular stents due to its excellent biocompatibility and appropriate biodegradability. However, weak mechanical properties limit its further clinic application. In this study, hot extruded pure Zn and Zn-0.02 Mg alloy were prepared. Compared with pure Zn, Zn-0.02 Mg alloy showed more homogeneous microstructure, much smaller grain size and higher mechanical strength. Zn-0.02 Mg alloy presented uniform corrosion morphologies during the immersion process, and its corrosion rates was higher than that of pure Zn. Hemocompatibility results showed that the Zn-based alloy had extremely low hemolysis rate (0.74 ± 0.15%) and strong inhibitory effect on blood coagulation, platelet adhesion and aggregation. Zn-0.02 Mg alloy also exhibited excellent cytocompatibility. Its extracts could significantly promote the proliferation of endothelial cells. Moreover, the antibacterial activities of the Zn-based alloy were demonstrated by spread plate assay, live/dead viability assay and bacterial morphology observation. These results indicate that the extruded Zn-0.02 Mg alloy has a potential in biodegradable cardiovascular stents.
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