The inclusion of a healing chamber in dental implants has been shown to promote biological healing. In this paper, a novel numerical approach to the design of the healing chamber for additive-manufactured dental implants is proposed. This study developed an algorithm for the modeling of bone growth and employed finite element method in ANSYS to facilitate the design of healing chambers with a highly complex configuration. The model was then applied to the design of dental implants for insertion into the posterior maxillary bones. Two types of ITI® solid cylindrical screwed implant with extra rectangular-shaped healing chamber as an initial design are adopted, with which to evaluate the proposed system. This resulted in several configurations for the healing chamber, which were then evaluated based on the corresponding volume fraction of healthy surrounding bone. The best of these implants resulted in a healing chamber surrounded by around 9.2% more healthy bone than that obtained from the original design. The optimal design increased the contact area between the bone and implant by around 52.9%, which is expected to have a significant effect on osseointegration. The proposed approach is highly efficient which typically completes the optimization of each implant within 3–5 days on an ordinary personal computer. It is also sufficiently general to permit extension to various loading conditions.

In this study, phosphate surface pretreatment (PSPT) and poly[pyromellitic dianhydride-co-4,4ʹ-oxydianiline] polyimide (PMDA-ODA PI) coating were used to provide corrosion protection for Mg-5 wt.% Sn alloy. PSPT enhanced the adhesion of PI coating by mechanical interlocking and chemical anchoring. Surface roughness was increased and provided stronger mechanical interlocking. Phosphates were formed on the alloy surface to act as anchor groups. Energy dispersive X-ray spectrometer and X-ray photoelectron spectroscopy results indicated that bonds formed between anchor groups and PI coating. The bonds provided chemical anchoring and enhanced the adhesion of PI coating. The increase of corrosion resistance of PI coating on Mg-5 wt.% Sn alloy (E corr = −0.86 V/SCE, I corr ¼ 4:9 Â 10 À2 µA cm −2 and corrosion rate far less than 0:1 ml cm À2 day À1 Þ showed the bonds were stable enough to stand the attack of electrolyte and inhibit the electrochemical reaction at the interface. IntroductionMagnesium alloys possess enormous advantages for high-performance automotive applications due to their superior properties such as low density, high specific mechanical strength, good heat conductivity, and good damping capacity. [1,2] Besides, the low density of magnesium alloy also satisfies the increasing demand for high energy efficiency in the automobile industry. Nowadays, most commercial uses of magnesium alloy are based on the well-developed Mg-Al system alloys. With the increasing needs of applications at elevated temperatures, Mg-Sn system alloys may take the place of Mg-Al system to be used due to its better mechanical properties at elevated temperature. [3,4] However, the better mechanical properties of Mg-Sn system at elevated temperature are not enough to replace Mg-Al system to be used as commercialized magnesium alloy. It is well known that poor corrosion resistance is the major barrier to hinder the industrialization of magnesium alloy. Besides, the lack of aluminum which forms Al 2 O 3 to protect the substrate from corrosion [5] in Mg-Sn system makes corrosion resistance of Mg-Sn system much worse than that of Mg-Al system.[6] Therefore,

The microstructure and characteristics of bulk magnesium consolidated from Mg powder by equal channel angular extrusion (ECAE) were investigated. Cu cans filled with Mg powder, of about 74 µm in diameter, were ECAE processed for one, two and four passes via the Bc route at 473, 523 and 573 K. The microstructure of ECAE-processed samples was observed by OM and SEM. The density of each sample was determined using Archimedes' principle. Microhardness and compression tests were conducted to investigate the mechanical properties of each ECAE-processed sample. The best consolidated condition between powders was achieved after four passes of ECAE at 573 K. Density at 98.4% of the ideal density of bulk Mg was achieved, microhardness was about 49 Hv, and compressive yield stress was about 100 MPa.

Abstract:The present study aims to investigate the effect of a trans-disciplinary design of curricula, deemed a powerful tool for teaching and research on complex environmental problems, with a goal to help solve the real problems that climate change has brought to the coastal environment in Taiwan. Three major real-life problems in southern Taiwan-declining mullet fisheries, flooding, and coral bleaching-were integrated into four courses. Adopting a qualitative case study method, the researchers investigated the student perceptions of the trans-disciplinary learning experiences, their attitudes toward marine and coastal environmental protection, and their capability of solving the problems related to marine and coastal environments. The researchers employed various methods to analyze the student reflection reports, student self-evaluation forms, and the tape-recorded class meetings. The findings suggest the following: the trans-disciplinary curriculum stands to be an innovative yet indispensable design for coastal management education; such a curriculum benefits students by equipping them with essential knowledge and skills to succeed in future marine conservation; action learning for marine and coastal sustainability serves as the final goal of trans-disciplinary learning project; a trans-disciplinary case study on the design of curricula provides effective knowledge integration of marine and coastal sustainability.