This study aimed to investigate the stainless steel 316L processing by means of selective laser melting (SLM). The processing parameters under consideration included laser power (25-225 W), scanning speed (50-320 mm/s), and scan spacing (0.04 and 0.06 mm). Every processing was constrained the layer thickness as of 100 µm. All parameters were performed based on two experiments, line scanning and multiple layers scanning. Each of final workpieces was examined by visual inspection, density measurement, hardness, and built rate. From the experiments, the optimal processing conditions which produced the smooth tracks were obtained. The workpiece processed by this optimal processing condition presented quality characteristics with 97.6% density and 220±6 HV hardness.

The aim of this study was to investigate the relation between the amount of glycosaminoglycans (GAGs) secreted and the level of apoptosis induced by hydrogen peroxide (H2O2) in porcine chondrocytes cultured on two different biodegradable PCL/PHBV scaffolds: one had primary pores solely, while the other possessed both primary and secondary pores, namely PCL/PHBV/0%NaCl and PCL/PHBV/50%NaCl scaffolds, respectively. The scaffolds with an average primary pore size of 200 μm were primarily fabricated by a fused deposition modeling (FDM) machine, and secondary pores on the material surface were then generated after NaCl leaching in a sodium hydroxide solution. The investigation was performed comparatively under static and dynamic environments. In static culture study, more pronounced GAG accumulation was found on the PCL/PHBV/50%NaCl scaffold, suggesting that the secondary pores could promote the chondrogenic function of chondrocytes, and the primary pores could further accommodate the cells to grow and function more productively. Meanwhile, the significant reductions in the levels of apoptosis of chondrocytes, studied in a H2O2-dose dependent manner (0-2 mM), were observed with a use of a flow cytometer when the chondrocytes were cultured on the PCL/PHBV/50%NaCl scaffold in which more GAG content was found. In dynamic culture study, although the total GAG content detected on the PCL/PHBV/50%NaCl scaffold was still significantly higher than that measured on the PCL/PHBV/0%NaCl scaffold, these GAG accumulations were tremendously greater than those found in the static culture. As a consequence, far less oxidative stress-induced apoptotic death was observed in the cells cultured under the dynamic culture. Moreover, cells seemed to be well protected from apoptosis, in the presence of considerable amounts of GAGs; similar degrees of apoptosis (~25%) were observed on the cells cultured on each scaffold at all H2O2 concentrations studied. The obtained results had demonstrated that the degree of chondrocyte apoptosis was somehow related to the level of GAG accumulation.

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Zirconia has been recently introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures, in combination with CAD/CAM techniques. To understand the clinical performance, it is important to establish the fundamental relationships between the intrinsic microstructural characteristics, mechanical properties and the machining properties. In this study, a series of zirconia blanks with systematically controlled presintering stage were milled using a 4 axes CNC milling machine. The pre-sintering heating rate and temperature of the blanks affect in opposite manner hardness and machinability. Cutting condition, surface roughness, geometric accuracy and machining time were then optimized by varying cutting feed (mm/min), depth of cut (mm), and step offset (mm). Phase stability and mechanical properties of the products were re-assessed to understand the effect of machining damage.