Large-scale screening of hundreds or even thousands of crystallization conditions while with low sample consumption is in urgent need, in current structural biology research. Here we describe a fully-automated droplet robot for nanoliter-scale crystallization screening that combines the advantages of both automated robotics technique for protein crystallization screening and the droplet-based microfluidic technique. A semi-contact dispensing method was developed to achieve flexible, programmable and reliable liquid-handling operations for nanoliter-scale protein crystallization experiments. We applied the droplet robot in large-scale screening of crystallization conditions of five soluble proteins and one membrane protein with 35–96 different crystallization conditions, study of volume effects on protein crystallization, and determination of phase diagrams of two proteins. The volume for each droplet reactor is only ca. 4–8 nL. The protein consumption significantly reduces 50–500 fold compared with current crystallization stations.

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Hf 0.25 Zr 0.25 Sn 0.25 Ti 0.25 )O 2 high-entropy ceramics were designed and prepared, and their microwave dielectric characteristics were investigated together with the microstructures. The single-phase structure in space group Pbcn was determined, and the excellent microwave dielectric characteristics were achieved in the present ceramics: ε r = 25.6, Qf = 74 600 GHz at 6.5 GHz and τ f = −47 ppm/ • C. The significant improvement of Qf value was achieved with a prolonged sintering, where the dielectric constant increased slightly while the negative τ f decreased in the absolute value at first and then turned to increase. The variation tendency of microwave dielectric characteristics was deeply linked with the microstructure homogeneity, and the introduction of Hf and Sn elements to create the high-entropy ceramics resulted in the disordered state, and finally led to the improved Qf value. The present work provided an effective approach to achieve enhanced Qf value in microwave dielectric ceramics.

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