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Additive manufacturing (AM) is a powerful tool for fabricating ceramics with novel and/or improved properties by enabling access to unique part architecture and geometry, and control of pore structure and distribution. In this review we show that layer-wise and direct writing AM processes can be used to fabricate microscopically-textured ceramics with unique crystallographic orientations by combining templated grain growth (TGG) with manipulation of the rheological properties of the feedstock, printhead geometry and printing speed during layer-wise and direct writing AM processes. For TGG the shear gradient, and resultant local torque, during printing aligns anisotropically-shaped template particles which serve as substrates for subsequent oriented grain growth and increase in crystallographic texture in the final part during sintering. We show how the deposition flow field and rheology of AM feedstocks coupled with anisotropic printing nozzles enables enhanced template alignment by impacting the torque gradient during deposition. Prospects for AM of textured ceramics are presented. Graphical abstract

Controllable growth and facile transferability of a crystalline film with desired characteristics, acquired by tuning composition and crystallographic orientation, become highly demanded for advanced flexible devices. Here the desired crystallographic orientations and facile transferability of a crystalline film can be achieved by “thru‐hole epitaxy” in a straightforward and undemanding manner with no limitation on the layer number and polarity of a 2D space layer and the surface characteristics. The crystallographic alignment can be established by the connectedness of the grown material to the substrate through a small net cross‐sectional area of thru‐holes, which also allows the straightforward detachment of the grown material. Thru‐hole epitaxy can be adopted for the realization of advanced flexible devices on large scale with desired crystallographic orientation and facile transferability. It is found that epitaxial growth and facile detachment of crystallographically aligned domains with a substrate are possible by thru‐hole epitaxy. Unlike remote epitaxy, no stringent requirements on the number of a layer or the polarity of a 2D space layer are necessary. The proposed thru‐hole epitaxy can be implemented even with SiO2 as a 3D space layer.

The crystallographic alignment, microstructure and magnetic properties were studied for La0.6Ca0.6Sr0.1Fe12.4Co0.4O19 ferrite permanent magnets prepared with standard ceramic method. The effect of cold isostatic pressing (CIP) and sintering temperature on the structural and magnetic properties of the magnets were investigated. The CIP significantly improves the density of the green compact and final magnets, but undermines the crystallographic alignment of the magnets simultaneously. As a result, the remanence of the magnet achieves optimal value under the compromise between the increased density and the degraded alignment. Moreover, the coercivity of the magnet increases linearly with the increment of the CIP pressure due the fact that CIP processed samples bear more uniform and finer grains in favor of high coercivity. Under optimal CIP pressure and sintering temperature, the magnet obtains best magnetic properties of Br of 0.439 T, Hcj of 396 kA m−1, Hcb of 311 kA m−1, and (BH)maxof 35.8 kJ m−3.

This paper demonstrates three-dimensional alignment of ß-FcSi2 in sintered bulk specimens. The three-dimensional alignment was achieved by using an oscillating magnetic field during slip-casting under a magnetic field of 6T. Sintering using direct electric current heating was performed in various conditions. The degree of alignment did not significantly degrade during sintering process. Apparent density became as high as 97%. The degree of alignment tended to increase as grain size increased.

Texture-engineered ceramics enable access to a vast array of novel texture-property relations leading to property values ranging between those of single crystals and isotropic bulk ceramics. Recently developed templated grain growth and magnetic alignment texturing methods yield high quality crystallographic texture, and thus significant advances in achievable texture-engineered properties in magnetic, piezoelectric, electronic, optical, thermoelectric, and structural ceramics. In this paper, we outline the fundamental basis for these texture-engineered properties and review recent contributions to the field of texture-engineered ceramics with an update on the properties of textured lead-free and lead-based piezoelectrics. We propose that further property improvements can be realized through development of processes that improve crystallographic alignment of the grain structure, create biaxial texture, and explore a wider array of crystallographic orientations. There is a critical need to model the physics of texture-engineered ceramics, and more comprehensively characterize texture, thus enabling testing of texture orientation-property relations and materials performance. We believe that in situ measurements of texture evolution can lead to a more fundamental and comprehensive understanding of the mechanisms of texture development.

The presence of protein structures with atypical folds in the Protein Data Bank (PDB) is rare and may result from naturally occurring knots or crystallographic errors. Proper characterisation of such folds is imperative to understanding the basis of naturally existing knots and correcting crystallographic errors. If left uncorrected, such errors can frustrate downstream experiments that depend on the structures containing them. An atypical fold has been identified in P. falciparum dihydrofolate reductase (PfDHFR) between residues 20–51 (loop 1) and residues 191–205 (loop 2). This enzyme is key to drug discovery efforts in the parasite, necessitating a thorough characterisation of these folds. Using multiple sequence alignments (MSA), a unique insert was identified in loop 1 that exacerbates the appearance of the atypical fold-giving it a slipknot-like topology. However, PfDHFR has not been deposited in the knotted proteins database, and processing its structure failed to identify any knots within its folds. The application of protein homology modelling and molecular dynamics simulations on the DHFR domain of P. falciparum and those of two other organisms (E. coli and M. tuberculosis) that were used as molecular replacement templates in solving the PfDHFR structure revealed plausible unentangled or open conformations of these loops. These results will serve as guides for crystallographic experiments to provide further insights into the atypical folds identified.

This study develops a fabrication technique to obtain Fe-free and Fe-bearing (Fe:Mg = 1:9) olivine aggregates not only with high density and fine grain size but with crystallographic preferred orientation (CPO). A magnetic field (≤12 T) is applied to synthetic, fine-grained (~120 nm), olivine particles dispersed in solvent. The alignment of certain crystallographic axes of the particles with respect to a magnetic direction is anticipated due to magnetic anisotropy of olivine. The dispersed particles are gradually consolidated on a porous alumina mold covered with a solid–liquid separation filter during drainage of the solvent. The resultant aligned consolidated aggregate is then isostatically pressed and vacuum sintered. We find that (1) preparation of fully reacted olivine particles, with less propensity to coalesce; (2) preparation of a suspension with highly dispersed particles; and (3) application of a certain strength of the magnetic field are essential to obtain well-sintered and well-aligned aggregates. High density (i.e., <1 vol% porosity) and fine grain size (~1 μm) Fe-free and Fe-bearing olivine aggregates were successfully synthesized with uniaxially aligned a - and c -axes, respectively. Attempts to uniaxially align the magnetization hard axis and to triaxially align Fe-bearing olivine by rotating the suspension in the magnetic field succeeded in obtaining weakly developed CPO aggregates.

The cyanobacterial clock proteins KaiA and KaiB are proposed as regulators of the circadian rhythm in cyanobacteria. Mutations in both proteins have been reported to alter or abolish circadian rhythmicity. Here, we present molecular models of both KaiA and KaiB from the cyanobacteria Anabaena sp PCC7120 deduced by crystal structure analysis, and we discuss how clock‐changing or abolishing mutations may cause their resulting circadian phenotype. The overall fold of the KaiA monomer is that of a four‐helix bundle. KaiB, on the other hand, adopts an alpha–beta meander motif. Both proteins purify and crystallize as dimers. While the folds of the two proteins are clearly different, their size and some surface features of the physiologically relevant dimers are very similar. Notably, the functionally relevant residues Arg 69 of KaiA and Arg 23 of KaiB align well in space. The apparent structural similarities suggest that KaiA and KaiB may compete for a potential common binding site on KaiC.

It has been reported that an anisotropic magnetic field could produce the three-dimensional alignment of fine single-crystal particles with the orthorhombic crystal structure.However,the three-dimensional alignment was achieved only in suspensions.Fabrication of bulk"single"materials that have the three-dimensional alignment of grains has been desired.This study proposes a procedure for the fabrication,which consists of slip casting under an oscillating magnetic field and sintering.Optimization of casting and sintering conditions achieved the three-dimensionally aligned bulkβ-FeSi2.

The work reported here concerns a proposed nanomanufacturing strategy to assemble aligned quasi-one-dimensional nanostructure arrays with intrinsic and concurrent control over the resultant number, pitch, and linewidth. For the first time, a standard lithography and crystallographic etching approach have been combined to synthesize periodic, sublithographic, and line edge roughness (LER)-free surface arrays for selective conjugation of nanowires. Key experimental modules have been developed, including the formation of LER-free substrate arrays, formation of periodically dissimilar surfaces, selective conjugation of nanowires, and stamping transfer of nanowire arrays. In particular, successful assembly of Si nanowires onto periodic Si/SiO x surfaces and subsequent transfer of the resultant aligned Si nanowire arrays onto a different substrate surface have been repeatedly demonstrated. The dependences and probability of nanowire aligned assembly have also been examined. The proposed strategy is based on a wafer-scale and very large-scale integration (VLSI)-compatible philosophy, and alignment to pre-existing features on the target substrate is also inherently allowed as a side benefit. Besides, LER-free features could be created, which arguably enables extreme linewidth scaling with suppressed variations.