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Teeth exemplify architectures comprising an interplay of inorganic and organic constituents, resulting in sophisticated natural composites. Rodents (Rodentia) showcase extraordinary adaptations, with their continuously growing incisors surpassing human teeth in functional and structural optimizations. In this study, employing state-of-the-art direct atomic-scale imaging and nanoscale spectroscopies, we present compelling evidence that the release of material from ameloblasts and the subsequent formation of iron-rich enamel and surface layers in the constantly growing incisors of rodents are complex orchestrated processes, intricately regulated and independent of environmental factors. The synergistic fusion of three-dimensional tomography and imaging techniques of etched rodent́s enamel unveils a direct correlation between the presence of pockets infused with ferrihydrite-like material and the acid resistant properties exhibited by the iron-rich enamel, fortifying it as an efficient protective shield. Moreover, observations using optical microscopy shed light on the role of iron-rich enamel as a microstructural element that acts as a path for color transmission, although the native color remains indistinguishable from that of regular enamel, challenging the prevailing paradigms. The redefinition of "pigmented enamel" to encompass ferrihydrite-like infusion in rodent incisors reshapes our perception of incisor microstructure and color generation. The functional significance of acid-resistant iron-rich enamel and the understanding of the underlying coloration mechanism in rodent incisors have far-reaching implications for human health, development of potentially groundbreaking dental materials, and restorative dentistry. These findings enable the creation of an entirely different class of dental biomaterials with enhanced properties, inspired by the ingenious designs found in nature.

The availability of aberration correctors for the probe-forming lenses makes simultaneous modification and characterization of materials down to atomic scale inside a transmission electron microscopy (TEM) realizable. In this work, we report on the electron-beam-induced reconstructions of three types of antiphase boundaries (APBs) in a probe-aberration-corrected TEM. With the utilization of high-angle annular dark-field scanning transmission electron microscopy (STEM), annular bright-field STEM, and electron energy-loss spectroscopy, the motion of both heavy element Mn and light element O atomic columns under moderate electron beam irradiation are revealed at atomic resolution. Besides, Mn segregated in the APBs was observed to have reduced valence states which can be directly correlated with oxygen loss. Charge states of the APBs are finally discussed on the basis of these experimental results. This study provides support for the design of radiation-engineering solid-oxide fuel cell materials.

We demonstrate that the growth of F16CuPc 1-D nanostructures can be directed by templates of gold nanoparticles. The growth occurs via vapor-phase transport, whereby the gold nanoparticles act as nucleation sites for F16CuPc molecules and promote their anisotropic growth. The F16CuPc 1-D structures adopt diameters of approximately 15-30 nm independent of the nanoparticle size. This approach enables a technologically simple and inexpensive fabrication of very uniform organic 1-D structures (aspect ratio of approximately 30) and precise control of their location and packing density.