A series of highly dense barium titanate (BaTiO 3 ) ceramics with the average grain size (GS) from 0.29 to 8.61 lm are successfully prepared by two-step sintering, and the GS effect on piezoelectric coefficient (d 33 ) is systematically discussed in this work. It is found that when GS above 1 lm, d 33 can be enhanced with decreasing GS, reaching a maximum value of 519 pC/N around 1 lm due to the high activity of domain wall mobility. Subsequently, d 33 rapidly drops with a further decrease in GS owing to the reduced domain density. The results suggest that it is possible to prepare high-performance BaTiO 3 ceramics by controlling the GS and domain configuration properly, which brings great revitalization to the BaTiO 3based piezoceramics.

Cancer is one of the leading causes of human death, despite enormous efforts to explore cancer biology and develop anticancer therapies. The main challenges in cancer research are establishing an efficient tumor microenvironment in vitro and exploring efficient means for screening anticancer drugs to reveal the nature of cancer and develop treatments. The tumor microenvironment possesses human-specific biophysical and biochemical factors that are difficult to recapitulate in conventional in vitro planar cell models and in vivo animal models. Therefore, model limitations have hindered the translation of basic research findings to clinical applications. In this review, we introduce the recent progress in tumor-on-a-chip devices for cancer biology research, medicine assessment, and biomedical applications in detail. The emerging tumor-on-a-chip platforms integrating 3D cell culture, microfluidic technology, and tissue engineering have successfully mimicked the pivotal structural and functional characteristics of the in vivo tumor microenvironment. The recent advances in tumor-on-a-chip platforms for cancer biology studies and biomedical applications are detailed and analyzed in this review. This review should be valuable for further understanding the mechanisms of the tumor evolution process, screening anticancer drugs, and developing cancer therapies, and it addresses the challenges and potential opportunities in predicting drug screening and cancer treatment.

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In this paper, a typical Li‐ and Ta/Sb‐modified alkaline niobate‐based ceramics prepared by conventional sintering and two‐step sintering were investigated in terms of their phase transition behaviors and various properties. The phase structures of the ceramics sintered by conventional sintering shifted remarkably from a polymorphic phase transition (PPT) to a tetragonal symmetry with the increase of sintering temperature. However, the ceramics sintered by two‐step sintering maintained PPT over a wide sintering temperature range. Similar to that, the various properties of the ceramics sintered by conventional sintering are strongly dependent on sintering temperature and the ceramics with good properties can only be obtained in a narrow sintering temperature range, while the ceramics with excellent properties were obtained by two‐step sintering over a wide sintering temperature range. The results indicate that two‐step sintering is an effective way to broaden the sintering temperature range of (K, Na)NbO3‐based ceramics.

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