Phase boundaries (PBs) are known to contribute to the outstanding performances of lead‐based and lead‐free materials. However, a lack of PBs restricts the promotion of piezoelectric performance in bismuth layer‐structured ferroelectrics (BLSFs). In this work, a pseudo PB, ie, pseudotetragonal distortion (regulated by Ce), is proposed to promote the piezoelectric properties of CaBi2Nb2O9‐based ceramics, and an excellent piezoelectric constant (d33) of 20.2 pC/N with a high Curie temperature of 923°C is obtained. Verified Ce incorporation into the (Bi2O2)2+ layer alters the environment of the (Bi2O2)2+ layer, thereby influencing the atomic displacement in the Nb‐O octahedron and modulating the theoretical spontaneous polarization (Ps). Strengthening of the pseudotetragonal distortion is favorable to the polarization switching, and maintains the theoretical Ps of ceramics at a high level, thus realizing the promotion of d33. Furthermore, pseudotetragonal distortion guarantees good thermal depoling performance of the ceramic, which remains at 89.6% (18.1 pC/N) of its initial d33 after depoling at 875°C. This work provides clear guidance on obtaining high d33 and good thermal stability in BLSFs.
54 human genes were selected as test targets for parallel cloning, expression, puri®cation and crystallization. Proteins from these genes were selected to have a molecular weight of between 14 and 50 kDa, not to have a high percentage of hydrophobic residues (i.e. more likely to be soluble) and to have no known crystal structures and were not known to be subunits of heterocomplexes. Four proteins containing transmembrane regions were selected for comparative tests. To date, 44 expression clones have been constructed with the Gateway 2 cloning system (Invitrogen, The Netherlands). Of these, 35 clones were expressed as recombinant proteins in Escherichia coli strain BL21 (DE3)-pLysS, of which 12 were soluble and four have been puri®ed to homogeneity. Crystallization conditions were screened for the puri®ed proteins in 96-well plates under oil. After further re®nement with the same device or by the hanging-drop method, crystals were grown, with needle, plate and prism shapes. A 2.12 A Ê data set was collected for protein NCC27. The results provide insights into the high-throughput target selection, cloning, expression and crystallization of human genomic proteins.
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