Many of the patterns seen in Origami are currently being explored as a platform for building functional engineering systems with versatile characteristics that cater to niche applications in various ...technological fields. One such pattern is the Kresling pattern, which can be used to construct mechanical springs with unconventional properties and rich translational-rotational restoring behavior. In this paper, we investigate, both theoretically and experimentally, the quasi-static behavior of a pair of serially-connected Kresling Origami springs under different end loading conditions. We show that, depending on the end loading of the spring, it can exhibit coupled/ decoupled motion; one, two, or three equilibria; fixed, quasi-zero, or variable stiffness; and symmetric/asymmetric restoring behavior. We also present a technique to predict the restoring behavior of the serially-connected springs by combining a simple truss model with the experimentally-identified restoring behavior of a single unit. The technique permits accurate prediction of the deformation path of any number of serially-connected springs. We believe that serially connected Kresling Origami Springs offer a pathway towards the design of axial and torsional springs with unique and versatile functionalities.
•The static behavior of two serially-connected Kresling springs is analyzed.•The spring can undergo purely axial/torsional or coupled motion under loading.•Interesting bifurcations of the spring equilibria are discussed.•Such bifurcations are used to program the restoring behavior of the spring.
The main aim of this research is to formulate a method of creating an accurate, personalised anthropomorphic phantom, retaining efficient production at a low cost. The project accomplishment ...consisted of selecting appropriate materials, designing and printing the phantom, which was afterwards used in radiotherapy plan verification based on dosimetric measurements. Finally, data collected with radiotherapy film was analysed with the use of the gamma index. Obtained results show that a phantom created with the proposed method provides an alternative for the water phantom in terms of practical application in the verification of a cancer patient's treatment plan.
•PLA proved to be good material for mimicking a variety of soft tissues in terms of both cost and quality.•Proposed designing method may be used for both personalised phantom and bolus printing.•Described phantom may be customised for use of other radiation detectors apart from radiochromic film.
•We have successfully fabricated the insulin-PLGA/PDA/PCL composite scaffolds.•The scaffolds can provide a slow, sustained release of insulin.•The scaffolds stimulated chondrocytes proliferation and ...BMSCs differentiation.•The scaffolds enhanced bone and cartilage repair in vivo.
Due to the poor ability of self-repair and regeneration, articular cartilage and subchondral bone defects and degradation are still a big problem nowadays. The aim of the present study is to fabricate and investigate a 3D printed polycaprolactone (PCL) scaffold modified by insulin-releasing PLGA nanoparticles for osteochondral repair. The double-emulsion solvent evaporation method is used to fabricate the insulin-coated PLGA nanoparticles, and the physicochemical characterization of the nanoparticles and scaffolds are tested. The cell studies in vitro and animal experiments in vivo are also investigated. The results show the hydrophilicity of the scaffolds is highly improved when coated with polydopamine (PDA), and the insulin release curve of the insulin-PLGA/PDA/PCL scaffolds exhibit a slowly and sustained profile after an initial burst release. The in vitro studies show that the insulin-PLGA/PDA/PCL scaffolds significantly improve the osteogenic differentiation of rabbit bone mesenchymal stem cells (rBMSCs) and the proliferation of chondrocytes. And the in vivo studies show that the insulin-PLGA/PDA/PCL scaffolds significantly improve repair of cartilage and subchondral bone after 8- and 12-week implantation in rabbit osteochondral defects. These findings exhibit that the insulin-PLGA/PDA/PCL scaffolds can provide a slowly, sustained release of insulin and may be a promising strategy for osteochondral repair.
•An integrally porous MoS2/Ni electrode was synthesized by the 3D printing technique.•The 3D printed MoS2/Ni exhibited excellent removal performance and reusability.•The MoS2 increased the ...dechlorination efficiency via the “Hydrogen spillover process”.•Degradation mechanism and pathway for FLO were proposed.
Here, we report the production of 3D-printed MoS2/Ni electrodes (3D-MoS2/Ni) with long-term stability and excellent performance by the selective laser melting (SLM) technique. As a cathode, the obtained 3D-MoS2/Ni could maintain a degradation rate above 94.0% for florfenicol (FLO) when repeatedly used 50 times in water. We also found that the removal rate of FLO by 3D-MoS2/Ni was about 12 times higher than that of 3D-printed pure Ni (3D-Ni), attributed to the improved accessibility of H*. In addition, the electrochemical characterization results showed that the electrochemically active surface area of the 3D-MoS2/Ni electrode is about 3-fold higher than that of the 3D-Ni electrode while the electrical resistance is 4 times lower. Based on tert-butanol suppression, electron paramagnetic resonance and triple quadrupole mass spectrometer experiments, a “dual path” mechanism and possible degradation pathway for the dechlorination of FLO by 3D-MoS2/Ni were proposed. Furthermore, we also investigated the impacts of the cathode potential and the initial pH of the solution on the degradation of FLO. Overall, this study reveals that the SLM 3D printing technique is a promising approach for the rapid fabrication of high-stability metal electrodes, which could have broad application in the control of water contaminants in the environmental field.
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•A zero-valent copper (3D-ZVC) TPMS structure was fabricated via 3D printing.•3D-ZVC can bear 13 kg of load, 8666 times higher than its own weight.•3D-ZVC showed superior catalytic ...activity to Cu2+ and Cu powder in PMS activation.•3D-ZVC is convenient to separate and displays excellent stability after 23 cycles.•Toxicity estimation analysis was used to evaluate the products of TC degradation.
Three-dimensional (3D) printing has demonstrated great potential in wastewater purification. Herein, a facile 3D printing strategy is utilized to prepare zero-valent copper (3D-ZVC). The obtained 3D-ZVC framework displays a hierarchically porous structure and a rough surface, which correspond to excellent mechanical robustness and catalytic performance in degrading multiple organic pollutants through peroxymonosulfate (PMS) activation. The 3D-ZVC/PMS/Vis system is capable of achieving a tetracycline (TC) degradation efficiency of over 96.5 % within 20 min, which greatly exceeds that of homogeneous Cu2+/PMS/Vis and contemporary powder/PMS/Vis systems as a result of the unique hierarchical porous structure and cycling of Cu(I)/Cu(II) in 3D-ZVC. Furthermore, the 3D-ZVC/PMS/Vis system exhibits a broad pH resistance range (3.21–10.18), spectacular adaptability, unparalleled stability, and excellent reusability after 23 successive cycles. Electrons and various reactive oxygen species, including SO4−, OH, O2−, and 1O2, are all involved in the decomposition of TC, with 1O2 playing a dominant role. The influence parameters and possible intermediates of the 3D-ZVC/PMS/Vis system are investigated. Toxicity estimation analysis indicates that the toxicity of TC degradation products has been significantly reduced, which is further confirmed through growth control experiments of bean sprouts. This study highlights a prospective and feasible application of 3D printing in environmental remediation through PMS activation.
This article compares and evaluates the marginal and internal fitness and three-dimensional (3D) accuracy of class II inlays fabricated using Tescera (TS) resin, milling of hybrid and zirconia ...blocks, and 3D printing with NextDent C&B.
Fifty-two mesio-occlusal inlays were fabricated using conventional method with TS, milling of Lava Ultimate (LU), milling of Zolid Fx multilayer (ZR), and 3D printing (
= 13 each). The marginal and internal fitness were evaluated at six points in the mesio-distal section of a replica under a digital microscope (160× magnification), and the accuracy was evaluated using 3D software. Analyses were conducted using
-test, one-way analysis of variance (ANOVA) and two-way ANOVA, while Duncan's multiple range test was used for post hoc analyses (
= 0.05).
The marginal and internal fitness of the 3D and ZR were significantly superior to that of the TS and LU. For LU, ZR, and 3D, a significant discrepancy between the marginal gap and internal gap was observed (
< 0.05). On evaluating accuracy, trueness was significantly higher in ZR than in TS and LU; precision was significantly higher in 3D and ZR than in TS and LU (
< 0.05).
The marginal and internal fitness and the accuracy of TS, ZR, and 3D were within the clinically acceptable range. The marginal and internal fitness and accuracy of 3D were better than those of TS and LU, which are commonly used in dentistry. There is immense potential for using 3D-printed inlays in routine clinical practice.
High conductive graphene flexible circuits are printed through 3D printing. PLA are chosen as the substrate of graphene. Graphene can be homodispersed in the PLA substrate.
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•3D print ...technique is used to print flexible circuits.•Highly conductive PLA-graphene composites are fabricated for 3D printing.•2D and 3D flexible circuits are printed rapidly.•The flexible circuits exhibit superior conductivity and mechanical properties.
Fused depositing modeling (FDM) is a fast, efficient process among 3D printing techniques. In this paper, we report the fabrication of the 3D printed flexible circuits based on graphene. Modified two-step in-situ reduced method is used to synthesize reduced graphene oxide (r-GO), whose conductivity can reach to 600S/cm. Polylactic acid (PLA) and r-GO are mixed by melt blending. The SEM images show that the r-GO can be homogenous dispersed in the PLA. The 3D print-used composites filaments with the diameter of 1.75mm are fabricated through melt extrusion. The conductivity of the composite filaments from 3D printer can reach to 4.76S/cm (6wt% r-GO). The orientation of r-GO occurs during the extrusion process, which contributing to increase the conductivity of the filaments. The composite also exhibit superior mechanical property. The printed 2D and 3D flexible circuits have strong interface bonding force between the layers. The filaments from 3D printer can replace the copper wire because of the high conductivity. This arbitrary 3D graphene-based structure printing technic may open a new prospect in electronic and energy storage fields.
The objective of this study is to evaluate, through a systematic review of the scientific literature and meta‐analysis, the applications of three‐dimensional (3D) printing in the surgical treatment ...of complex fractures of the appendicular skeleton, mainly in terms of effectiveness and safety. A systematic review of the scientific literature was conducted in MEDLINE (PubMed) and the Cochrane Library combining different keywords. A specific methodological assessment scale was developed and applied to included papers. Ten studies were included; all of them were controlled trials, except for one retrospective observational cohort study. We observed statistically significant differences between the group that used 3D printing and the control group in terms of reduction in surgical time, reduction in the volume of blood lost during surgery and reduction in the number of intraoperative fluoroscopies, in favor of the 3D printing group. No statistically significant differences were observed in terms of fracture healing time, postoperative joint function, or postoperative complications. Meta‐analysis revealed more favorable results for 3D‐printing compared with conventional surgery, with the greatest difference observed for the number of intraoperative fluoroscopies. 3D printing might be considered effective and safe in the surgical treatment of anatomically complex appendicular skeleton fractures, in terms of reducing surgical time, lost blood volume, and radiation exposure of surgeons and patients.
In this article, we discuss the impacts of using 3D printing in education. Our primary goal is to evaluate the pedagogical impact of lessons utilizing 3D printing. We asked one hundred ninety ...students in four reference schools about the acceptability of existing 3D materials for teaching. Although the results show high attractiveness for the target group, it turned out that the available lessons primarily focus on the acquisition of technical skills and do not use the potential of education in other areas. We, therefore, proposed a concept for creating multidisciplinary teaching lessons that connect the technical part with other educational areas. We show the application of our concept in a newly developed lesson in biology, where we again evaluate its acceptance among the students. The results show that although the multidisciplinary lessons are more complex, they are still acceptable to the students, and, most importantly, they add significant educational value. Finally, we discuss the possibilities of incorporating 3D printing into the teaching curriculum. We also use a selected use case to illustrate the real-world problems we have encountered.
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