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Wings of insects exhibit many functions apart from flying. In particular, their anti-reflection function is important for insects to avoid detection by their enemies. This function can be applied to anti-reflection bio-mimetic films in engineering fields. For such applications, confirming the anti-reflection mechanisms of insect wings is important. Herein, we used electron microscopy to compare the surfaces of green lacewing wings with and without a surface wax structure and recorded the transmittance spectra to clarify the surface structural and optical properties of insect wings. The spectral transmittance was higher for wings with a surface wax structure than for wings without a wax layer in the light wavelength regime from 500 to 750~nm. We constructed a concise model of the green lacewing wing with flake-like surface structure with a graded effective refractive index corresponding to the wing samples with a surface wax layer; we also constructed a simple thin-film model corresponding to the wing samples without a wax layer. The graded refractive indices were calculated using the effective medium theory, and the transmittance spectra of such models were then calculated using the transfer-matrix method. It was observed that the calculated spectra are in good agreement with the experimental results. In addition, wing samples without a surface structure induce thin-film interference. These results suggest that a wax structure can reduce the reflectance and increase the transmittance enabling the green lacewings to avoid detection by their enemies. These findings may lead to further advances in both the bio-mimetic field and fundamental research fields.

Activated human eosinophils, as well as neutrophils, can release extracellular chromatin to form DNA traps through cytolytic extracellular trap cell death (ETosis). Although formations of neutrophil DNA traps are recognized in patients with various inflammatory conditions, neither the presence of ETosis-derived eosinophil DNA traps in human allergic diseases nor the characteristics of these DNA traps have been studied.

Ultrafiltration (UF) membranes composed of an ultrathin and ordered layer of silica nanoparticles (NPs) was fabricated via spin-assisted layer-by-layer (LbL) assembly in dehydrated conditions. Anionic silica NPs and cationic sacrificial polymers were alternately stacked on an anodic aluminum oxide support membrane via electrostatic interactions. The assembly was then calcinated to remove the sacrificial polymers and form a stacked-NP membrane. The structure of the NP layers was controlled by altering the number of stacked-NP layers formed during the LbL assembly processes and performing an ethanol-based dehydration treatment. Increasing the number of NP layers increased the total thickness of the stacked-NP layer and decreased the water permeability. The rejection performance against dextran was improved by increasing the number of NP layers, indicating a decrease in the number of defects. The ethanol-based dehydration treatment successfully decreased the total thickness of the stacked-NP layer and improved the rejection performance against dextran. The surface morphology of the NP layers became smoother by the ethanol-based treatment. These results indicate that the ethanol-based treatment produces dense NP layers with an ordered structure by removing water molecules adsorbed on the sacrificial polymers and NPs. The performance of the stacked-NP membranes was superior to that of commercial UF membranes.

Statement of problem The effects of the application of aqueous coloring liquids on the mechanical properties of zirconia have not yet been investigated. Purpose The purpose of this in vitro study was to evaluate the effects of 3 different coloring techniques and the number of coloring liquid applications on the hardness of zirconia.

Biomineralization involves complex processes and interactions between organic and inorganic matters, which are controlled in part by the cells. The objectives of this study were, first, to perform a systematic and ultrastructural investigation of the initial mineral formation during secondary ossification center of mouse femur based on material science and biology viewpoint, and then develop novel biomaterials for mineralization based on the in vivo findings. First, we identified the very initial mineral deposition at postnatal day 5 (P5) at the medial side of femur epiphysis by nanocomputed tomography. Initial minerals were found in the surroundings of hypertrophic chondrocytes. Interestingly, histological and immunohistochemical analyses showed that initial mineralization until P6 was based on chondrocyte activity only, i.e., it occurred in the absence of osteoblasts. Moreover, electron microscopy-based ultrastructural analysis showed that cell-secreted matrix vesicles were absent in the early steps of osteoblast-independent endochondral ossification. Instead, chondrocyte membrane nanofragments were found in the fibrous matrix surrounding the hypertrophic chondrocytes. EDS analysis and electron diffraction study indicated that cell membrane nanofragments were not mineralized material, and could be the nucleation site for the newly formed calcospherites. The phospholipids in the cell membrane nanofragments could be a source of phosphate for subsequent calcium phosphate formation, which initially was amorphous, and later transformed into apatite crystals. Finally, artificial cell nanofragments were synthesized from ATDC5 chondrogenic cells, and in vitro assays showed that these nanofragments could promote mineral formation. Taken together, these results indicated that cell membrane nanofragments were the nucleation site for mineral formation, and could potentially be used as material for manipulation of biomineralization.