Japan Space Forum

Abstract Environmental plastic pollution remains a major global concern due to the slow oxidative degradation of micro- and nanoplastics (MPs/NPs). This study explores rapid thermal–oxidative degradation of isotactic polypropylene (iPP) using hydrogen peroxide (H 2 O 2 ) under high-pressure hydrothermal conditions to generate reactive oxygen species (ROS). Complete mineralization occurred at ≥ 27% H 2 O 2 , while 3–21% induced controlled fragmentation into MPs/NPs with tunable surface oxidation. SEM, FT-IR, XPS, DSC, and Py-GC/MS analyses confirmed chain scission, formation of carbonyl and hydroxyl groups, reduced crystallinity, and suppression of propylene trimer formation. Pressurized hydrothermal conditions enhanced oxidation kinetics, shortening degradation from years to hours. Overall, high-pressure H 2 O 2 oxidation effectively accelerates polymer breakdown and limits secondary pollutants, presenting a promising route for sustainable MPs/NPs removal in aquatic systems. Graphical abstract

ABSTRACT Soil organic carbon (SOC) is essential for maintaining soil functioning as well as for mitigating climate change. SOC stabilisation in mineral‐associated organic matter (MAOM) fraction plays a key role, and MAOM distribution should be quantified in divergent environments to improve predictions of SOC dynamics. However, quantitative information on the OC storage capacity of MAOM based on MAOM distribution is still limited, especially in tropical alkaline soils, which might have a lower OC storage capacity because of weaker interactions between C and clay via cation bridges such as Ca and Mg, compared to common Al‐, Fe‐organo‐metal complexes in tropical acidic soils. This study aimed to evaluate the OC storage capacity of MAOM based on the relationship between the mass proportion (%) and OC content in MAOM (g C kg −1 soil) in 46 tropical alkaline surface soils of southern India with variable soil types (Alfisols, Inceptisols, and Vertisols) and land uses (paddy fields, croplands, and bushes). Boundary line analysis was used to estimate the upper distribution of MAOM‐C for our dataset, and the slope of the regression line (0.16, R 1 = 0.16, p < 0.001) was substantially lower compared to that in a previous review of tropic soils (0.53, R 1 = 0.46, p < 0.005) mainly conducted on acidic to neutral soils (Fujisaki et al., 2018). We found that MAOM‐C content was positively correlated with Ca ex , Mg ex , and clay, and was well predicted by Mg ex both in a simple and multiple linear regression model. Considering the alkaline soil pH of dataset (8.0 ± 0.1), these results indicate that a lower OC storage capacity in this study might be attributed to the weaker interactions between OC and minerals via cation bridges in tropical alkaline soils. There were no significant differences in the slope of the linear regression lines between soil types and land uses, except that the slope in Alfisols was greater than that in Vertisols, and all the slopes were consistently lower than that of Fujisaki et al. (2018), similar to that of the boundary line analysis for the whole dataset. Our results provide direct evidence that tropical alkaline soils have a substantially lower organic carbon storage capacity as MAOM than that of tropical acidic to neutral soils. Further study is necessary to elucidate the factors controlling the low OC storage capacity in this area.

Abstract The effects of altered gravity on longevity remains unknown. We investigated the effects of exposure to space microgravity and hypergravity on the longevity of Caenorhabditis elegans throughout its adult life. Microgravity was demonstrated to shorten lifespan and accelerate the rate of aging compared to artificial 1G conditions in orbit. Conversely, hypergravity extended the lifespan and delayed aging. The lifespan of deletion mutants in the daf-16 gene, which encodes the DAF-16/FOXO transcription factor that regulates stress, sensation, and aging, was shortened by microgravity more than that of the wild type and not extended by hypergravity. We identified several DAF-16 target genes involved in the lifespan extension induced by hypergravity, including cav-1, hsp-17, acdh-1, and ZK105.13, which were upregulated by DAF-16 in hypergravity and tended to be downregulated in microgravity. These findings suggest that gravity influences longevity in C. elegans, at least partly, through the regulation of DAF-16.

Abstract The soluble precursors of elastin protein and elastin-like polypeptides (ELPs) are polymers that typically undergo liquid‒liquid phase separation to form coacervates. In addition to their fundamental importance in biology, the dynamic nature of coacervates makes them attractive platforms as innovative materials in bioengineering and nanomedicine. This focus review presents the latest research on the requirements of elastin-like polypeptide sequences for phase separation and the dynamics of coacervates. Research attempting to control the phase-transition behavior of ELPs in living cells is also presented. In addition, a molecular design strategy for ELPs to obtain anisotropic nanofibers by coacervation, their functionalization for biomaterial applications, and the unique viscoelastic properties of hydrogels composed of nanofibers are discussed. These research trends indicate that the molecular design of ELPs enables control of the dynamics and morphology of coacervates. This fundamental knowledge will be useful for the dynamic functional design of drug delivery systems and scaffolds for regenerative medicine.

Polymerization-induced self-assembly (PISA) has emerged as a powerful technique for generating microphase-separated structures, but research has primarily focused on systems exhibiting "disordered" structures. Here, we demonstrate the facile construction of various highly ordered microphase-separated structures via PISA, with and without kinetic control through manipulation of the glass transition temperature (T g) of the core-forming blocks. We synthesized diblock copolymers in an ionic liquid (40 wt% solute) by polymerizing styrene or 2-hydroxyethyl acrylate from one end of poly(ethylene glycol). When using polystyrene as the core-forming block, its high T g relative to the polymerization temperature resulted in the formation of kinetically trapped structures, including pure hexagonal close-packed (HCP) spheres exhibiting X-ray diffraction peaks up to the 17th-order. Conversely, lower-T g core-forming block [poly(2-hydroxyethyl acrylate)] led to thermodynamically stable, highly ordered structures, including a double-gyroid morphology. These results highlight the efficacy of PISA for generating diverse, highly ordered microphase-separated structures from simple diblock copolymers and demonstrate its potential to access structures unattainable through conventional ex situ polymerization.

ABSTRACT This paper presents a 610 MHz radio survey covering 1.94 deg$^2$ around the North Ecliptic Pole (NEP), which includes parts of the ${\it AKARI}$ (ADF-N) and Euclid, Deep Fields North. The median 5$\sigma$ sensitivity is 28 $\mu$Jy beam$^{-1}$, reaching as low as 19 $\mu$Jy beam$^{-1}$, with a synthesized beam of 3.6 arcsec $\times$ 4.1 arcsec. The catalogue contains 1675 radio components, with 339 grouped into multicomponent sources and 284 ‘isolated’ components likely part of double radio sources. Imaging, cataloguing, and source identification are presented, along with preliminary scientific results. From a non-statistical sub-set of 169 objects with multiwavelength AKARI and other detections, luminous infrared galaxies (LIRGs) represent 66 ${{\ \rm per\ cent}}$ of the sample, ultra-luminous infrared galaxies (ULIRGs) 4 ${{\ \rm per\ cent}}$, and sources with L$_{IR}$ < 10$^{11}$ $\mathrm{ L}_{\odot }\,$ 30${{\ \rm per\ cent}}$. In total, 56 ${{\ \rm per\ cent}}$ of sources show some AGN presence, though only seven are AGN-dominated. ULIRGs require three times higher AGN contribution to produce high-quality SED fits compared to lower luminosity galaxies, and AGN presence increases with AGN fraction. The PAH mass fraction is not significant, although ULIRGs have about half the PAH strength of lower IR-luminosity galaxies. Higher luminosity galaxies show gas and stellar masses an order of magnitude larger, suggesting higher star formation rates. For LIRGs, AGN presence increases with redshift, indicating that part of the total luminosity could be contributed by AGN activity rather than star formation. Simple cross-matching revealed 13 ROSAT QSOs, 45 X-ray sources, and 61 sub-mm galaxies coincident with GMRT radio sources.

The analysis of cells frozen within the International Space Station (ISS) will provide crucial insights into the impact of the space environment on cellular functions and properties. The objective of this study was to develop a method for cryopreserving blood cells under the specific constraints of the ISS. In a ground experiment, mouse blood was directly mixed with a cryoprotectant and gradually frozen at −80 °C. Thawing the frozen blood sample resulted in the successful recovery of viable mononuclear cells when using a mixed solution of dimethylsulfoxide and hydroxyethyl starch as a cryoprotectant. In addition, we developed new freezing cases to minimize storage space utilization within the ISS freezer. Finally, we confirmed the recovery of major mononuclear immune cell subsets from the cryopreserved blood cells through a high dimensional analysis of flow cytometric data using 13 cell surface markers. Consequently, this ground study lays the foundation for the cryopreservation of viable blood cells on the ISS, enabling their analysis upon return to Earth. The application of this method in ISS studies will contribute to understanding the impact of space environments on human cells. Moreover, this method may find application in the cryopreservation of blood cells in situations where research facilities are inadequate.

Recent technological advances have accelerated the use of artificial intelligence (AI) in the world. Public concerns over AI in ethical, legal, and social issues (ELSI) may have been enhanced, but their awareness has not been fully examined between countries and cultures. We created four scenarios regarding the use of AI: “voice,” “recruiting,” “face,” and “immigration,” and compared public concerns in Japan, the US, Germany, and the Republic of Korea (hereafter Korea). Additionally, public ELSI concerns in respect of AI were measured using four items: ethics, tradition, law and social benefit. Respondents with AI knowledge tended to exhibit stronger concern about ELSI in various situations. In terms of law concerns, Japanese respondents displayed greater concerns. In contrast, the US, when compared Japan, expressed a relatively optimistic view of the current law landscape. Regarding social benefits, Korea, compared to Japan, exhibited a more positive outlook, whereas Germany, in comparison to Japan, expressed heightened concerns about it across different scenarios.

We have developed a protein array system, named "Phospho-Totum", which reproduces the phosphorylation state of a sample on the array. The protein array contains 1471 proteins from 273 known signaling pathways. According to the activation degrees of tyrosine kinases in the sample, the corresponding groups of substrate proteins on the array are phosphorylated under the same conditions. In addition to measuring the phosphorylation levels of the 1471 substrates, we have developed and performed the artificial intelligence-assisted tools to further characterize the phosphorylation state and estimate pathway activation, tyrosine kinase activation, and a list of kinase inhibitors that produce phosphorylation states similar to that of the sample. The Phospho-Totum system, which seamlessly links and interrogates the measurements and analyses, has the potential to not only elucidate pathophysiological mechanisms in diseases by reproducing the phosphorylation state of samples, but also be useful for drug discovery, particularly for screening targeted kinases for potential drug kinase inhibitors.