Shimizu (Japan)

As a response to aging of cultured urease-producing microorganisms, the blending method was examined to obtain the required carbonate production amount using the apparent viability (Rcv) based on previous research. As a result, a significantly higher carbonate content than the amount of CaCl2 2H2O used was produced. Since this trend has been obtained in previous studies, it was judged that carbonate hydrate was formed. As a next step, a penetration test of soil-biocement-liquid (BCS) was conducted to investigate the properties and behavior of the BCS system, taking into account the microscopic properties of the BCS response. The depth distribution of carbonate content (C) was measured by the acid dissolution method of soil sampled from the specimen. It was assumed that the C-profile was formed by adsorption based on the diffuse double layer of microorganisms. It was shown that the amount of precursor-carbonate (precursor CPR), the optical density (OD) of viable bacteria, and the physical amount of soil adsorbed at that position can be estimated from C obtained at the various depths. In addition, the previously obtained formulas among CPR, viable OD, and Rcv shown are briefly explained in this paper.

Triple junctions between fundamental tectonic units are where different compositions and magmatic processes interact. We investigated the intersection of a spreading center with an island arc within the Philippine Sea Plate, i.e. an arc-ridge-arc triple junction, using a combination of submersible sampling and shipboard geophysics. We use Ar Ar dating, elemental concentrations and Sr-Nd-Pb radiogenic isotope ratios to constrain the structure, age and origin of magmatism as spreading interacted with the arc. Between 33 and 31 Ma the tip of the West Philippine Basin spreading center was in the back-arc west of the Kyushu-Palau arc. Spreading volcanism had mantle-like Ce/Pb and Th/Ce indicating a lack of slab flux. Radiogenic isotopes form a trajectory towards low 143 Nd/ 144 Nd and high 20x Pb/ 204 Pb, but extend to Δ 208 Pb/ 204 Pb > 85 which corresponds to an EM-2-like mantle component rather than pelagic sediment input from the slab. The final stage of spreading-related activity occurred between 31 and 28.5 Ma when the spreading axis rotated from NW-SE to E -W and propagated eastwards into the arc. It resulted in magmatism contemporaneous with the adjacent frontal arc. This final magmatism extended the radiogenic isotopic trajectories observed in the earlier spreading towards less radiogenic Pb and higher 143 Nd/ 144 Nd, i.e. towards MORB from the EM-2 component. However, during the final stage magmatism La/Sm, Nb/Zr increased while Pb and Sr isotopes became progressively more radiogenic, demonstrating a progressive decrease in the degree of partial melting and preferential tapping of the EM-2 component. This change in melt generation and composition appears a common process at the end of spreading. • Magmatism at arc-ridge-arc triple junction in the Philippine Sea Plate was studied. • CBF Rift spreading center intersected KPR arc, caused overlapping MORB magmatism. • Interaction between a volcanic arc and a spreading centre caused excess magmatism. • Spreading center at wanning stage preferentially consumes more enriched mantle.

This paper discusses time-dependent behaviour of cut slopes in clay shales, special attention being paid to the effect of strength deterioration due to softening and a stress transfer phenomenon associated with progressive yielding. Cutting is analyzed as an example using a finite element method with realistic modeling of softening effect. Progressive behaviour of the cut slope is illustrated. It is shown that the displacement and stress change in the slope are traced up to collapse, and that excessive stresses resulting from local yielding are transferred progressively to the surrounding elements in the slope.

The concept of the ecological niche, defined as the basic habitat requirements for a species, is central to understanding species geographic distributions and predicting their responses to environmental change. However, identifying the essential niche for large regional communities remains a challenge because niche axes can be "hidden" by the complexity of the underlying ecological processes. Here, applying advanced species distribution modelling to nationwide environmental DNA survey data, we identified hidden niche axes of the Japanese coastal fish community and investigated the response diversity to these axes. Our survey detected 1,220 coastal fish species. The hidden niche axes collectively explained most of the variation in fish biodiversity and revealed five biogeographic boundaries for the regional community. These niches of the Japanese fish community may primarily relate to several processes due to ocean currents, such as environmental filters, transport from source areas and dispersal barriers. We also found that the response diversity to niche axes was positively correlated with species richness, although local communities with particularly high response diversity were geographically biased. A better understanding of the niche axes of the regional ecological community should help to mitigate the loss of biodiversity and ecosystem services caused by ongoing environmental change.

The SBPDN (Steel Bar Prestressed Deformed Normal relaxation) bar, which has ultra-high yield strength yet much lower bond resistance than conventional deformed bars, has been recently proposed to be used as the longitudinal rebar instead of a normal-strength deformed bar to simply realize strong earthquake-resilient concrete components. To facilitate and promote the application of concrete components reinforced with SBPDN rebars to the structures located in earthquake-prone regions, it is indispensable to develop reliable and effective anchoring means and clarify the bond strength of SBPDN bars embedded in concrete and/or grout mortar. This paper presents experimental information on the pull-out tests of fifteen SBPDN bars embedded in grout mortar, along with a discussion on the effective anchorage details and the bond strength of SBPDN bars. The tested SBPDN bars have a nominal diameter of 22.2 mm, the maximum diameter currently available on the market. All SBPDN bars were embedded in high-strength grout mortar with a targeted compressive strength of 60 MPa. The primary experimental variables included the end anchorage details, the diameter of sheath ducts, and the embedded length of the bars. Test results demonstrated that either screwing two nuts and a washer at the end of SBPDN bars or providing a rolling-threaded end region was effective in preventing them from premature slip from grout mortar. If the embedment length was 20 times the bar diameter or longer, the proposed two anchorages could ensure the SBPDN bar to fully develop its specific yielding strength as high as 1275 MPa. In addition, it has also been experimentally revealed that the bond strength of SBPDN bars embedded in grout mortar was much lower than that of conventional deformed bars and varied between 2.84 MPa and 3.98 MPa.

本研究は特定用途制限地域による沿道型商業施設に対する規制誘導のあり方や課題を明らかにすると共に、人口減少時代における運用のあり方も含め同制度を検証することを目的とする。全国の地方都市において2024年10月時点で指定されていた全特定用途制限地域（284区域）から、白地地域の幹線道路に店舗面積制限を行う事例を、沿道指定型、規制型、準規制型として全事例抽出した（217区域、54自治体）。2024年3月末時の全大型店データを基に、①まちづくり三法改正後でも白地区域では1万㎡未満の店舗の立地は増加に転じていること、②その中で特定用途制限地域の指定は、特に3000〜5000㎡未満の店舗の立地抑制に効果を上げていること、③リテイルバーク型の連担型店舗の規制誘導に適していないこと、④今後は立地適正化計画と連携する形で1000〜3000㎡の店舗の適切な誘導に力点を置くべきであること、等を明らかにした。

BackgroundThe transparent jellyfish body is often difficult to see underwater, as its refractive index is similar to that of seawater, resulting in a low light reflectance on the body surface. Nevertheless, the outlines of jellyfish can be recognized by the slight reflection of light from their body surfaces. In some jellyfish species, the epidermis covering the body surface has an array of microvilli, nanostructures that can potentially reduce light reflection. However, the anti-reflective effect is minimal in water, as the difference in the refractive indices of tissue and seawater is so small that reflectance is low, even on flat surfaces. In jellyfish that have pneumatophores, structures used in floating and drifting on the sea surface, light reflection on the surface is expected to be large and noticeable owing to the large differences in refractive indices between the pneumatophore exposed above the water surface and air. In the current study, we examined the epidermal ultrastructure and refractive index of the pneumatophores of a Portuguese man o’ war (Physalia physalis) and a by-the-wind sailor (Velella velella).ResultsThe refractive index of P. physalis pneumatophores measured with an Abbe refractometer was approximately 1.344. Microvillar arrays were found in epidermal cells of both P. physalis and V. velella. Based on the length, thickness, and pitch of the microvilli, we constructed simplified structural models for the simulation of light reflection using rigorous coupled wave analysis (RCWA). Our simulations showed that reflectance on the microvillar models could be greater or less than that on the flat surface, depending on light conditions (wavelength and angle of incidence), but with an overall effect of reduced reflection. Reflection reduction in microvillar models was particularly significant at large incident angles, where reflectance was extremely high on the flat surface.ConclusionsMicrovillar arrays found on the epidermis potentially reduce surface reflections of the pneumatophore and contribute to the reduction in visibility of the pleustonic hydrozoans above the sea surface. Moreover, less reflection at the pneumatophore surface indicates greater transmission of light through transparent bodies, potentially providing a counter-illumination effect that obscures the shadow of the hydrozoan bodies, depending on the intensity of ambient light.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40851-025-00253-4.

Sound fields around a barrier edge with an open-tube array are numerically calculated to investigate how the tube array affects barrier performance. Results show that the open tubes arrayed on the source side of the barrier edge are effective in some cases. On basis of the results, a hypothesis regarding the effects of the open tubes at the barrier edge is considered and tested. It is revealed that sound pressure levels behind the barrier are significantly suppressed when the phase difference between incident waves from the source to the upper and lower ends of a tube is small.

Abstract The Universal Block Floating System (UBFS) is a system developed for simple construction of floating platform for various applications on water, such as floating architecture and water-based recreation. The UBFS will make it possible to experience activities on water quickly and easily. This paper presents the results of the verification for the construction system by demonstration tests conducted over the past two years and future developments in the use of this technology on water. In June 2023, the first full-scale verification tests for floating architecture using the UBFS on water was conducted in Lake Hamana (Shizuoka, Japan). In addition to the verification tests of building, towing, and disassembling the floating structure, the facility was used as trial applications of floating architecture using the UBFS where visitors could experience the activity on the actual floating architecture, as a place to enjoy meals on the lake, and as a pier for sightseeing boats. A survey by questionnaire was conducted on swaying experience and floating facility needs, and measurements were taken of wave height and of the response of the floating structure. The research shows the relationship between the response of people to sway and the measurement data of sway, and expectations for the floating architecture.