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Fully dense zirconia parts were produced by shaping using Fused Deposition Modeling (FDM) and microwave (MW) sintering. The samples were obtained using an usual 3D printer and a commercial 3 mol% yttria-stabilized zirconia filament. The printing parameters were adapted to the printer and the filament. Then, the samples were debinded with a two-step process, i.e., chemical and thermal debinding. The debinded samples were sintered in a multimode microwave instrumented cavity. Full density was achieved with shorter thermal cycles compared with conventional sintering. Dilatometric curves for microwave sintering show similar behavior during densification, as in conventional sintering. The evolution of measured temperature vs time confirms the good control of the thermal cycle allowed by the MW device.

The number of patients suffering from diseases linked with hormone deficiency (e.g., type 1 diabetes mellitus) has significantly increased in recent years. As organ transplantation presents its limits, the design of novel robust devices for cell encapsulation is of great interest. The current study reports the design of a novel hybrid alginate microcapsule reinforced by titania via a biocompatible synthesis from an aqueous stable titania precursor (TiBALDH) and a cationic polyamine (PDDAC) under mild conditions. The biocompatibility of this one-pot synthesis was confirmed by evaluation of the cytotoxicity of the precursor, additive, product, and by-product. The morphology, structure, and properties of the obtained hybrid microcapsule were characterized in detail. The microcapsule displayed mesoporous, which was a key parameter to allow the diffusion of nutrients and metabolites and to avoid the entry of immune defenders. The hybrid microcapsule also showed enhanced mechanical stability compared to the pure alginate microcapsule, making it an ideal candidate as a cell reservoir. HepG2 model cells encapsulated in the hybrid microcapsules remained intact for 43 days as highlighted by fluorescent viability probes, their oxygen consumption, and their albumin secretion. The study provides a significant progress in the conception of the robust and biocompatible reservoirs of animal cells for cell therapy.

MW sintering is a sintering process in which samples directly heat by absorption of the electromagnetic field, leading to a fast volume heating. Thus, the materials are heated due to their own dielectric properties. Zirconia Toughened Alumina (ZTA) is of particular interest for MW sintering because of the difference of dielectric properties between alumina and zirconia. In this study, ZTA pellets with different volume fractions of zirconia were sintered in a MW multimode cavity with different sintering cells, i.e., with or without susceptor. These experiments show that all the samples were densified whatever the configuration. But the evolution of power and temperature vs time during the sintering cycle shows a better heating capability when the volume fraction of zirconia increases. The influence of the material to heat is more visible when sintering without susceptor. This was confirmed by other experiments, where the samples were heated by a constant incident power in a single-mode cavity.

The combination of three-dimensional (3D) printing technologies and microwave (MW) sintering offers new perspectives for minimizing material, energy and time waste. This study aimed at conducting a parametric study on the sintering of robocast porcelain by conventional and MW heating in a multimode cavity (2.45 GHz, 3 kW). The effect of heating rate, dwell temperature and dwell duration on sample density, shrinkage and microstructure was investigated on small pellets. With conventional heating, a good densification was achieved with a 2 h dwell at 1250 °C, independent of heating rate (1–20 °C/min). A similar density was reached using microwave hybrid heating at a much higher heating rate (100 °C/min), shorter dwell (30 min) and slightly higher sintering temperature (1300 °C). Without susceptor, a longer pre-heating step was required to initiate the sample heating, thus extending the heat treatment duration. This study provides seeding data for the development of greener processes for aluminosilicate ceramic manufacturing.

Atmospheric carbon dioxide levels have been rising since the industrial revolution, with the most dramatic increase occurring since the end of World War II. Carbon dioxide is widely regarded as one of the major factors contributing to the greenhouse effect, which is of major concern in today’s society because it leads to global warming. Photosynthesis is Nature’s tool for combating elevated carbon dioxide levels. In essence, photosynthesis allows a cell to harvest solar energy and convert it into chemical energy through the assimilation of carbon dioxide and water. Therefore photosynthesis is regarded as an ideal way to harness the abundance of solar energy that reaches Earth and convert anthropologically generated carbon dioxide into useful carbohydrates, providing a much more sustainable energy source. This Minireview aims to tackle the idea of immobilizing photosynthetic unicellular organisms within inert silica frameworks, providing protection both to the fragile cells and to the external ecosystem, and to use this resultant living hybrid material in a photobioreactor. The viability and activity of various unicellular organisms are summarized alongside design issues of a photobioreactor based on living hybrid materials.

Natural photosynthesis is a highly efficient process that uses sunlight irradiation to convert carbon dioxide into value‐added biomass. This review summarizes the recent advances in the transformation of solar energy into electrical power through the exploitation of photosynthetically active proteins, organelles, and living cells. During the past decade, the considerable progress made in bioentities immobilization offers the possibility to integrate biological systems into electronic devices. Even though solar energy technologies are gaining increasing attention, photosynthetic biofuel cells are still in their infancy. Advances in materials science are necessary to protect, stabilize, and even increase the catalytic performance of bioentities. Moreover, host materials could guarantee higher loading and better electrical charge transport, which would be crucial in the commercial success of biofuel cells. In the future, such semi‐artificial hybrid assemblies could hold promise as sustainable sources of energy.

Review: 170 refs.

Review: 264 refs.

Natural photosynthesis is a highly efficient process that uses sunlight irradiation to convert carbon dioxide into value‐added biomass. The Review by p. 476 ff.,Bao‐Lian Su et al. summarizes the recent advances in the transformation of solar energy into electrical power, as represented here on the Inside Cover, through the exploitation of photosynthetically active proteins, organelles, and living cells.