A projection X-ray microscope has been constructed by modifying a scanning electron microscope (HITACHI S-2500CX). Characteristic internal structures and their changes in an aphid, a fly, an ant, a water bear and a beetle are observed first, non-destructively, by X-ray microscope. Stereo-pair X-ray micrographs of Golgi-stained sections of porcine liver show a network of bile canaliculi and stellate cells. The very clear micrographs presented indicate the usefulness of the microscope in studies of entomology and histology. In some micrographs, very thin whiskers or hairs are visible, which suggests that a phase-contrast effect is present in the imaging. X-ray micrographs of an ant hair taken at various distances between the X-ray source and the specimen, D_ś, indicate that the image enhancement due to the phase contrast increases with increasing D_s. Degree of the lateral coherence of X-rays of wave length 0.1 nm is theoretically estimated near the hair, with the result that the coherence increases from about zero (almost complete incoherence) at D_s = 0.1 mm to about unity (almost complete coherence) at D_s = 6 mm, in agreement with the observation.

Luminescent europium (Eu) and dysprosium (Dy) doped yttrium–vanadate (Y–V) nanoparticles (NPs) were synthesized in the cavity of the protein, apoferritin. Y–V NPs were synthesized by incubating a solution of apoferritin with Y³⁺ and VO₃ ⁻ ions in the presence of ethylene diamine-N-N′-diacetic acid (EDDA). EDDA plays an important role in preventing Y–vanadate precipitation in bulk solution by chelating the Y³⁺ ions. Using high resolution electron microscopy, the obtained NPs in the apoferritin cavities were confirmed to be amorphous, and to consist of Y and V. Eu-doped Y–V (Y–V:Eu) NPs were synthesized by the same procedure as Y–V NPs, except that Eu(NO₃)₃ was added. Y–V:Eu NPs exhibited a strong absorption peak due to the O–V charge transfer transition and remarkable luminescence at 618 nm due to the ⁵D₀ → ⁷F₂ transition. The luminescence lifetime of Y:Eu and Y–V:Eu NPs measured in H₂O and D₂O solution showed reduction of non-radiative transition to the O–H vibration in Y–V:Eu NPs. Accordingly, Y–V NPs showed strong luminescence compared to Y:Eu NPs. Dy-doped Y–V NPs were also synthesized in apoferritin cavities and showed luminescence peaks at 482 nm and 572 nm, corresponding to ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_13/2 transitions. These NPs stably dispersed in water solution since their aggregation was prevented by the protein shell. NPs encapsulated in the protein are likely to be biocompatible and would have significant potential for biological imaging applications.