Volume 1, 2025

  • Recovery of phosphate from carbonized sewage sludge by chlorination

    The present research group has recently found a method to recover phosphorus, which is called “biological and technical nutrient”, from sewage sludge as phosphorus chloride forms. Specifically, we have developed a simple sewage sludge recycling technology that first carbonizes sewage sludge to improve handling, then chlorinates the resulting carbonized material at 500℃, and finally separates phosphorus chloride species and impurities by a cooled deposition method. This method can be applied to sewage sludge incineration ash, livestock manure, steelmaking slag, etc.

    Yuuki Mochizuki, and Naoto Tsubouchi

    Biomass and Bioenergy，Volume 199，Article 107890

  • Investigation of Single Ammonia Droplet Evaporation Characteristics Under High Temperature and Pressure Conditions

    Ammonia is a promising alternative fuel for significantly reducing CO₂ emissions. However, to utilize it efficiently, it is necessary to develop technologies that enable direct spray combustion of liquid ammonia. In this study, we clarified—for the first time in the world—the evaporation characteristics of ammonia droplets under high-temperature and high-pressure conditions. Furthermore, we obtained essential droplet evaporation data necessary for the development of ammonia spray combustion technology.

    Leang So Khuong, Nozomu Hashimoto, Yu Ito, Nobuto Nakamichi, Yusuke Konno, and Osamu Fujita

    Fuel, Vol. 399, No. 135600

  • Unveiling the origin of diffusion suppression of hydrogen isotopes at the α-Al₂O₃(0001)/α-Cr₂O₃(0001) interfaces

    Hydrogen in metallic materials causes degradation known as hydrogen embrittlement, which renders the materials brittle. Therefore, to promote the use of hydrogen energy in applications such as fuel cells and nuclear fusion reactors, strategies to prevent hydrogen permeation into structural materials are essential. In this study, we elucidated the mechanism by which coating multiple layers of different ceramic films on metal surfaces, which serve as hydrogen permeation barriers, can more effectively suppress hydrogen permeation than single-layer ceramic films. This research can contribute to extending the service life of metallic materials in a hydrogen environment.

    Yuji Kunisada, Ryotaro Sano, and Norihito Sakaguchi

    International Journal of Hydrogen Energy, Volume 97, Pages 1327-1334

  • Effect of Wet−dry Cycles and Water-to-cement Ratios on Cement Paste Carbonation

    Cement production consumes a significant amount of energy and releases CO₂ emissions, while concrete waste can potentially reabsorb CO₂. This study examined the effect of relative humidity (especially wet-dry cycles) on the carbonation of hardened cement pastes. Wet–dry cycles increased porosity and caused the decomposition of calcium silicate hydrate (C-S-H) through shrinkage and deformation during drying. As a result, the highest CO₂ absorption in the wet-dry cycle sample was twice that of the constant RH. Additionally, the amount of CO₂ captured during the 28-day wet-dry cycle accounted for about 17% of the annual CO₂ emissions from cement production.

    Zhiwei Zhao, Dayoung Oh (researchmap.jp, researchgate.net, scholar.google.com), Ryoma Kitagaki, Tianlong Zheng, and Ippei Maruyama

    Journal of Advanced Concrete Technology, 23, 205-222

  • Development of a novel in-sediment passive sampler for profiling orthophosphate and internal phosphorus release near the sediment–water interface in a eutrophic lake

    The release of orthophosphate (PO₄) from lake sediments is now recognized as an important phosphorus source that maintains lake eutrophication. Therefore, quantifying PO₄ release is important for lake management. In this study, we developed a novel sampler to determine the PO₄ flux from lake sediment. The sampler was installed at the sediment–water interface (SWI) in a eutrophic lake. The vertical and horizontal PO₄ concentrations around the sampler were obtained. The obtained data enabled in situ quantification of the PO₄ fluxes at the SWI.

    Kazuto Sano, Jumpei Ueda, Akira Hafuka, and Katsuki Kimura

    Water Research, 282, 123634

  • Spatiotemporal mode extraction for fluid–structure interaction using mode decomposition

    We proposed a method to extract the spatiotemporal modes of structural deformation obtained from fluid-structure interaction analysis using Dynamic Mode Decomposition (DMD). By applying this method, it becomes possible to identify the dominant structural deformation modes in systems where fluid forces induce significant structural changes, such as flexible aeroshells.

    Yusuke Takahashi

    Journal of Sound and Vibration, Vol. 597, Part A

  • Nucleation probability of methane + propane mixed-gas hydrate depending on gas composition

    Natural gas hydrate contains large amounts of natural gas and is attracting attention as one of the future domestic resources, or as its storage and transportation medium. For its industrial use, it is one of the problems that the nucleation process is difficult to control. This study has revealed that the nucleation probability of methane + propane mixed-gas hydrate, as a mimic of natural-gas hydrate, depends on the composition. This result will help develop technology for industrial use of gas hydrates.

    Tsutomu Uchida, Masato Hayama, Motoi Oshima, and Kenji Yamazaki

    Energy & Fuels, 39 (10), 4782-4789, 2025

  • Transport of radioactive elements in concrete due to utilization of recycled aggregate contaminated with nuclides

    In the future, a huge amount of concrete waste will be generated in preparation for the demolition of nuclear power plants. From the perspective of rational processing and disposal, it is possible to reuse this waste, particularly waste with low levels of radioactivity, as recycled aggregate. Clarifying how radioactive materials migrate inside concrete is extremely important in building a safe and secure society.

    Yingyao Tan, Takafumi Sugiyama, Katsufumi Hashimoto, and Junxiao Liu

    Construction and Bulding Materials, Volume 471, 11 April 2025, 140689

  • Mussel Adhesive Protein-Assisted Magnetic Recovery of Microplastics from Aquatic Environments

    Mussel adhesive proteins can adhere to a wide range of materials, from iron (inorganic) to plastic (organic). By taking advantage of this adhesive property, we can form a composite of microplastics and magnetic microparticles, which can be magnetically recovered from an aqueous solution with an efficiency greater than 99%.

    Anju Pilakka Veedu, Kazunori Nakashima,* Takahiro Sato, Ami Sasabe, Keita Suzuki, Chikara Takano, and Satoru Kawasaki

    ACS ES&T Water, 5, 2087−2095 (2025)

  • Photoinduced Metal–Insulator Phase Separation Depending on the Conformational Order of Molecules in β-(BEDT-TTF)₂I₃

    In this study, the role of the conformational order of organic molecules in photo-induced phase separation (PIPS), which forms the basis for ultrafast switching devices, is investigated. The results show that PIPS occurs below 150 K in the partially ordered phase and below 75 K in the homogeneously ordered phase. This result implies that conformational order plays a crucial role in determining the temperature at which PIPS occurs, providing significant insight for room-temperature operation, which is essential for the practical application of devices.

    Kensho Nagata, Satoshi Tsuchiya, Koichi Nakagawa, Hiromi Taniguchi, and Yasunori Toda

    Journal of the Physical Society of Japan 94, 044701

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