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Attaining high densification without grain growth is one of the main objectives of the sintering optimization in ceramic materials. For dental implant applications, achieving this objective has a decisive impact on the mechanical resistance, the duration and the translucency of the implant. To improve these sintering outcomes a long experimental explorative study is generally required. In this work, we developed a combined experimental/modeling approach allowing a rapid identification of the optimal sintering conditions. The determination of the model densification and grain growth kinetic constitutive parameters has been done experimentally. We found that the sintering/grain growth kinetics have a detrimental acceleration above a critical temperature level. The pressure-less sintering model able to predict the sintering stress, powder densification and grain growth has been used for the determination of the optimal sintering trajectory. We utilized the two step sintering method to approach the critical temperature without an undesirable grain growth.We obtained translucent sintered specimens with a very limited grain growth.

Extracellular electron transfer (EET) is a mechanism that enables microbes to respire solid‐phase electron acceptors. These EET reactions most often occur in the absence of oxygen, since oxygen can act as a competitive electron acceptor for many facultative microbes. However, for Shewanella oneidensis MR‐1, oxygen may increase biomass development, which could result in an overall increase in EET activity. Here, we studied the effect of oxygen on S. oneidensis MR‐1 EET rates using bioelectrochemical systems (BESs). We utilized optically accessible BESs to monitor real‐time biomass growth, and studied the per‐cell EET rate as a function of oxygen and riboflavin concentrations in BESs of different design and operational conditions. Our results show that oxygen exposure promotes biomass development on the electrode, but significantly impairs per‐cell EET rates even though current production does not always decrease with oxygen exposure. Additionally, our results indicated that oxygen can affect the role of riboflavin in EET. Under anaerobic conditions, both current density and per‐cell EET rate increase with the riboflavin concentration. However, as the dissolved oxygen (DO) value increased to 0.42 mg/L, riboflavin showed very limited enhancement on per‐cell EET rate and current generation. Since it is known that oxygen can promote flavins secretion in S. oneidensis, the role of riboflavin may change under anaerobic and aerobic conditions. Biotechnol. Bioeng. 2017;114: 96–105. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

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The microwave sintering homogeneity of large and complex shape specimens is analyzed. A new approach enabling the fabrication of complex shapes ceramics via 3D printing and microwave sintering is presented. The use of a dental microwave cavity is shown to enable a substantial level of densification of complex shape components while restricting the grain growth. The homogeneity of the processed samples during microwave sintering is studied by an electromagneticthermal-mechanical simulation. The realistic densification behavior, that phenomenologically takes into account the microwave effect, is included in the modeling framework. The simulation indicates the sharp correlation between the microwave field distribution in the cavity, the temperature profile, and the specimen's shape distortion. K E Y W O R D Scomplex shape,