Solvothermal synthesis of hair-like carbon nanotubes onto sub-micron-sized spherical metal oxide catalyst cores.

Long- and uniform-length, and high-density hair-like carbon nanotubes (CNTs) were produced by CNT growth on sub-micron-sized spherical catalyst supports. The nanosized catalysts (FeO x , CoO x , and NiO x ) that were supported in/on the sub-micron-sized spherical metal oxides (TiO2, ZrO2, SnO2, and CeO2) were prepared via one-step solvothermal and/or two-step impregnation methods. The nanosized catalysts supported in/on the spherical metal oxide supports were converted into CNT conjugates with the CNT-hair morphology via a chemical thermal vapor deposition technique using ethyne gas as a carbon source; the CNTs grew on the central spherical metal oxide core under the base growth process conditions. Among the many types of candidate spherical catalyst materials, the combination of FeO x as a catalyst for CNT growth and ZrO2 as a support led to the best growth of CNT-hair under the reaction conditions, which included a temperature of 730 °C, pressure of 65 Pa, a 10 sccm ethyne gas flow, and a reaction time of 10 s. The CNTs consisted of five-to-eight-layered multi-wall structures with lengths of approximately 3 µm. The CNT-hair that was obtained using the solvothermally embedded catalyst showed higher crystallinity and was dense, thick, and straight, while the corresponding CNT-hair obtained using the impregnated catalyst was slightly sparse, thin, and curly. A unique layer structure constructed using large quantities of uniform CNT-hair, including multiple CNT yarns similar to fuzzy balls or cotton candies, was assembled. The CNT-hair conjugate, specifically constructed in a layer structure with core FeO x /ZrO2 catalysts and tangled CNT yarns, had an appearance similar to frog eggs. Therefore, we successfully prepared suitable catalysts for CNT-hair production and fabricated a layer structure consisting of large numbers of CNT-hair conjugates. The unique structures are expected as a new metamaterial with intriguing physical properties, including isotropic absorption of polarized light and electromagnetic waves.

Spillover and spillback risks of ectoparasites by an invasive squirrel Callosciurus erythraeus in Kanto region of Japan.

Invasive organisms can alter host-parasite relationships in a given ecosystem by spreading exotic parasites and/or becoming a new reservoir for native ones. Since these problems affect management programs of the invasive host organisms, it is necessary to monitor them individually. The Pallas's squirrel Callosciurus erythraeus is an invasive arboreal mammal introduced into Japan that threatens to exacerbate ecological and public health problems by spreading native and exotic parasites. However, only limited surveys have been available especially for ectoparasites, using the traditional combing method in which the possibility of oversight is inherent. Here, we evaluated the ectoparasite occurrences in Kanto region of Japan, using the whole-shaving method as an alternative approach. As a result of examining 52 hosts from two invaded districts (Yokohama and Yokosuka), chigger mites (Leptotrombidium spp.) and fleas (Ceratophyllus anisus and Ceratophyllus indages indages) were newly recovered in addition to the previously reported tick (Haemaphysalis flava) and exotic lice (Enderleinellus kumadai and Neophaematoponis callosciuri). The parasite burdens were higher in Yokosuka and in male host individuals, affecting infracommunity richness and composition. Our findings on the variety of native and exotic ectoparasites, at higher abundances in some cases than previously known, may suggest that both the spillover and spillback risks need to be adjusted upwards.

Citrus peel polymethoxyflavones, sudachitin and nobiletin, induce distinct cellular responses in human keratinocyte HaCaT cells.

A variety of polyphenols have been isolated from plants, and their biological activities have been examined. Sudachitin (5,7,4'-trihydroxy-6,8,3'-trimethoxyflavone) is a polymethoxyflavone that is isolated from the peel of Citrus sudachi. Although we previously reported that sudachitin possesses an anti-inflammatory activity, its other biological activities are not yet understood. In this study, we report a novel biological activity of sudachitin, which selectively induced apoptosis in human keratinocyte HaCaT cells. Another polymethoxyflavone, nobiletin (5,6,7,8,3',4'-hexamethoxyflavone), promoted autophagy but not apoptosis in HaCaT cells. On the other hand, 3'-demethoxysudachitin (5,7,4'-trihydroxy-6,8-dimethoxyflavone) failed to induce apoptosis and autophagy. These results show that three polymethoxyflavones have different effects on apoptosis and autophagy in HaCaT cells. Understanding the structure and biological activity of polymethoxyflavones may lead to the discovery of potential candidates for cancer drug development without significant toxic side effects. Abbreviations: ROS: reactive oxygen species; DMSO: dimethyl sulfoxide; MTT: 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; PARP: poly(ADP-ribose) polymerase; PI: propidium iodide; MAPK: mitogen-activated protein kinase.