Differences in the spatial distribution and shell morphology of Thylacodes adamsii (Gastropoda: Vermetidae) distributed in the Pacific and the Sea of Japan coastal areas of Japan

Thylacodes adamsii is a sessile gastropod and common inhabitant of rocky shores along the warm temperate coastal regions of Japan. We investigated the spatial distribution of this species in Shirahama facing to the Pacific Ocean, and in Maizuru facing to the Sea of Japan. Results showed that this species inhabits the middle intertidal zone in low densities in Shirahama, whereas it lives in high densities on oyster shells in the subtidal zone in Maizuru. Additionally, distinct shell morphology was found in the populations between the two localities. Observations of radular morphology suggest that they are most probably conspecific. Distinct shell morphology may be a result of adaptation to the different habitats

Mucus-net feeding behavior by the sessile gastropod Thylacodes adamsii (Gastropoda: Vermetidae)

Vermetid gastropod Thylacodes adamsii secrete a mucus net for feeding. We observed a feeding behavior of T. adamsii in the intertidal zone of Shirahama, the coast facing the Pacific Ocean. Thylacodes adamsii spread its mucus net within 20minutes of submergence. Creating a network of mucus threads immediately after submergence may be important for efficient feeding when T. adamsii is distributed in the intertidal zone. Additionally, we investigated the organisms trapped in the mucus net, because identifying the species from the stomach contents of T. adamsii was difficult. The organisms trapped on T. adamsii mucus nets in Shirahama included Dinophyta, Nematoda, Annelida, Arthropoda, Gastropoda, Chordata, and particles of seaweeds. By contrast, the most frequently trapped organisms in Maizuru, the coast facing the Sea of Japan, were diatoms. The difference between organisms trapped in Shirahama and Maizuru is probably due to the different vertical distribution of T. adamsii at the two locations

Citizen science reveals the present range and a potential native predator of the invasive slug Limax maximus Linnaeus, 1758 in Hokkaido, Japan

The giant garden slug Limax maximus Linnaeus, 1758 (Limacidae, Pulmonata) is considered one of the most widely spread terrestrial molluscs in the world and is a formidable pest of agricultural and horticultural crops. This slug was recently introduced to Japan, where its population is now rapidly increasing and spreading. A naturalised population of L. maximus was first discovered in Hokkaido, Japan, in 2012 in the isolated natural forest of Maruyama Forest Park in Sapporo City, and the species has become common in this area. In the present study, we investigated observations of L. maximus reported by ordinary citizens acting as "citizen scientists" to assess the recent expansion of this invasive slug. We posted an announcement in the local newspaper requesting reports of the occurrence of L. maximus via e-mail and analysed 38 observations provided by local citizens. As a result of these reports, 16 naturalised populations of L. maximus were detected in Hokkaido, several of which were quite far from the original population in Sapporo City. Moreover, a terrestrial macrophagous leech, Orobdella kawakatsuorum Richardson, 1975 (Arhynchobdellida, Orobdellidae), is reported as a potential native predator of L. maximus for the first time

Equiaxed grain formation by intrinsic heterogeneous nucleation via rapid heating and cooling in additive manufacturing of aluminum-silicon hypoeutectic alloy

The high strength of Al-Si hypoeutectic alloys additively manufactured by powder-bed fusion is of great scientific interest. To date, the mechanism of grain refinement near the fusion line, which contradicts conventional Hunt's columnar–equiaxed transition criteria, remains to be elucidated. Here we present the first report on the mechanism of grain refinement. When a laser was irradiated on cast Al-Si alloy consisting of coarse α-Al grain and α-Al/Si eutectic regions, grain refinement occurred only near the eutectic regions. This strongly suggests that the Si phase is crucial for grain refinement. Multi-phase-field simulation revealed that rapid heating due to the laser irradiation results in unmelted Si particles even above the liquidus temperature and that the particles act as heterogeneous nucleation sites during the subsequent re-solidification. These results suggest the feasibility of a novel inoculant-free grain refinement that is applicable to eutectic alloys comprising phases with a significant melting point difference.Masayuki Okugawa, Yuta Ohigashi, Yuya Furishiro, Yuichiro Koizumi, Takayoshi Nakano, Equiaxed grain formation by intrinsic heterogeneous nucleation via rapid heating and cooling in additive manufacturing of aluminum-silicon hypoeutectic alloy, Journal of Alloys and Compounds, Volume 919, 2022, 165812, ISSN 0925-8388, https://doi.org/10.1016/j.jallcom.2022.165812

Manufacturing of Poly-DL-Lactic Acid Nanosheets and Evaluation of Tribological Characteristics between Nanosheet Surfaces and Fingers

Attention is focused on ultra-thin polymer films (nanosheets) that have high flexibility and adhesiveness and their thickness can be controlled to several tens of nanometers. These nanosheets can be neatly attached to surfaces with complex irregularities without the use of adhesives. Therefore, the ratio of surface area to thickness is very large, and we believe that the relationship with friction is very significant in nanosheet technology for biomedical applications such as wearable devices and wound dressings. The purpose of this study is to investigate the contact mechanism of nanosheets with human fingertip skin in terms of friction coefficient by using the microgravure printing method, which enables thin film coating. From the results of film thickness measurements, it was found that nanosheets of any thickness can be fabricated by the microgravure printing method. The friction measurement results showed that the coefficient of friction of the nanosheets decreased except for vertical loads above Fz=2N. The coefficient of friction increased as the contact area increased. It was found to increase with increasing vertical load under the immersion in water conditions, and conversely, it decreased under the drying condition except for the high normal load of 2N. Furthermore, the coefficient of friction was found to increase with increasing nanosheet thickness. Observation of wear traces showed that when the vertical load was sufficiently high (Fz = 2 N), wear traces containing oily traces such as sebum and sweat appeared on the nanosheet surface. This is thought to function as a lubricant. Polymer nanosheets are a new material, and there have been few studies on friction with this material. Research on friction is very important because polymer nanosheets are expected to be applied to wound dressings and displays of electronic devices

Generation of Embryonic Stem Cell Lines from Immature Rabbit Ovarian Follicles

In mammalian ovaries, many immature follicles remain after the dominant follicles undergo ovulation. Here we report the successful production of rabbit embryonic stem cells (ESCs) from oocytes produced by in vitro culture of immature follicles and subsequent in vitro maturation treatment. In total, we obtained 53 blastocysts from oocytes that received intracytoplasmic sperm injection followed by in vitro culture. Although only weak expression of POU5f1 was observed in the inner cell masses of in-vitro-cultured follicle-derived embryos, repeated careful cloning enabled establishment of 3 stable ESC lines. These ESC lines displayed the morphological characteristics of primed pluripotent stem cells. The ESC lines also expressed the pluripotent markers Nanog, POU5f1, and Sox2. Further, these ESCs could be differentiated into each of the 3 different germ layers both in vitro and in vivo. These results demonstrate that immature follicles from rabbits can be used to generate ESCs. Moreover, the use of rabbit oocytes as a cell source provides an experimental system that closely matches human reproductive and stem cell physiology.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140197/1/scd.2012.0300.pd