Chiba Institute of Science

Collagen and gelatin are promising cell scaffold materials, but their structural instability under physiological conditions necessitates crosslinking treatment. This study evaluated UV crosslinking (254 nm, 0-180 min) as a non-toxic alternative to chemical crosslinking for collagen sheets (CS) and gelatin sheets (GS). Physicochemical properties were characterized by gel fraction analysis, atomic force microscopy (AFM) in PBS, and Fourier transform infrared spectroscopy (FT-IR), while NIH-3T3 fibroblast proliferation was evaluated by CCK-8 assay. UV crosslinking dramatically improved GS water resistance (gel fraction increased from 22% to 80% at 60 min) while maintaining smooth nanoscale surfaces (Rq: 1-4 nm), whereas CS exhibited inherent high stability (90% gel fraction without UV treatment, reaching 95-98% after irradiation). Both materials achieved maximum elastic modulus at 60 min (CS: 2.0 MPa; GS: 1.5 MPa). UV irradiation significantly enhanced cell proliferation on both substrates compared to untreated controls (p < 0.05). CS showed consistently high proliferation across all UV-treated conditions (day 3 absorbance: ~2.5-2.7), while GS exhibited progressive increases reaching a maximum at 180 min (absorbance: ~2.9). The continued GS enhancement despite slightly decreased elastic modulus suggests that chemical factors, possibly related to RGD motif accessibility, contribute beyond mechanical optimization. UV crosslinking effectively establishes structural stability essential for cell scaffold function, with both materials representing effective, biocompatible scaffolds for tissue engineering applications.

Correction for 'Modular and chromatography-free synthesis of natural linear polyamines' by Masato Takahashi et al., Org. Biomol. Chem., 2026, 24, 675-680, https://doi.org/10.1039/D5OB01807B.

The total electron content is an integrated value of ionospheric electron density (Ne) along the satellite-receiver ray path; therefore, it cannot directly resolve ionospheric disturbances in the vertical direction. In this work, to better understand the continuous evolution of co-seismic ionospheric disturbances (CIDs) at different altitudes, we conducted an accurate three-dimensional (3-D) visualization of CIDs associated with the 2011 M9.0 Tohoku-Oki earthquake based on the computerized ionospheric tomography technique. The results clearly revealed the 3-D morphological discrepancies of CIDs caused by Rayleigh waves, acoustic-gravity waves originating from the epicenter, and internal gravity waves induced by the tsunami waves. Further, we investigated the propagation and distribution of Ne disturbances along altitude. It was found that Ne disturbances triggered by different wave patterns exhibited different evolution characteristics in the vertical direction. The application of 3-D ionospheric detection has the potential to enhance the robustness of the earthquake and tsunami early warning systems.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-26074-1.

Dielectric elastomers offer several advantages such as low cost, high efficiency, high output, large deformations, light weight, and ease of stacking. Recently, it has become possible to lift a weight of 8 kg by more than 1 mm at a speed of 88 ms using 0.15 g of a dielectric elastomer. Additionally, transparent or nearly transparent electrodes can be fabricated using carbon nanotubes or carbon black, respectively. Through leveraging these properties, researchers are exploring applications such as transparent lenses and high-performance transparent speakers, with the ultimate aim of integrating this technology into portable devices like digital cameras, video cameras, and mobile phones. New potential applications being considered include transparent power-assist devices, wearable generators, wind power generators, and wave power generators. Transparency allows these devices to blend into their surroundings, whilst not being obtrusive to observers and the environment. In this study, we review elastomer and electrode materials aimed at improving the performance of dielectric elastomer actuators, sensors, and generators. We also discuss challenges related to transparent electrodes and propose potential solutions. Based on these results, potential applications are also discussed.

ObjectiveThis study aimed to investigate the background information of suicide cases with a history of psychiatric consultations using postmortem data from the Osaka Prefectural Medical Examiner’s Office. The goal was to explore the relationship between psychiatric consultations and the timing of suicide. Methods: A retrospective analysis was conducted on 191 suicide cases recorded in 2017. Background data such as gender, age, occupation, method of suicide, and the time interval between the last psychiatric consultation and suicide were analyzed. Descriptive statistics and correlation analysis were used to examine trends. Results: Females accounted for 55.0% of the cases, with most individuals being middle-aged (56.0%) and unemployed (70.7%). Hanging (44%) was the most common suicide method, while Mondays (24.1%) had the highest suicide frequency. The median time between the last psychiatric consultation and suicide was 9 days, and a strong negative correlation (r = -0.79) was observed between this interval and the number of suicides. Conclusion: The findings suggest that suicides often occur shortly after psychiatric consultations, emphasizing the need for timely intervention. Postmortem data can offer critical insights into suicide risks. However, further research is needed to better understand psychiatric consultation details and their link to suicide prevention.

To support disaster prevention, it is essential to know in advance when scenarios start to distinguish one from the others, thus requiring the development of early detection methods of such separations. Ensemble prediction systems has been developed to provide scenarios of evolutions via their ensemble members, because the future state of the atmosphere predicted by a single ensemble member is less meaningful than the estimate of the future probability density from all the ensemble members. By construction, the primary function of an ensemble prediction system is to provide forecasters with a degree of uncertainty and level of confidence. For the last couple of years, we have developed different approaches which take advantage of the information provided by different ensemble prediction systems.Tropical cyclone tracks forecasted by a prediction system sometimes group together into trajectories parting away from each other. An objective method, based on a robust clustering approach, has been created to detect such separation scenarios in the Mesoscale Ensemble Prediction System developed by the Japan Meteorological Agency. At each initialization time, when the number of clusters is greater than 1, local separation scenarios exist. Separations are related to different steering environments predicted by the different ensemble members.On the same data used for the clustering, we also applied biological concepts such as the Waddington&amp;#8217;s epigenetic landscape, and bioinformatics techniques like the graph-Hodge decomposition, to produce &amp;#8220;MeteoScape&amp;#8221;, an innovative way to characterize the evolution of a tropical cyclone. Particularly, &amp;#8220;MeteoScape&amp;#8221; can detect the possible paths and their associated probabilities of realization, as well as the regional separatrix, i.e., the spatial boundary between paths/scenarios, regardless of the initialization time (as in the clustering approach).Using the cases of intense precipitations that occurred in western Japan in July 2018 and August 2021, we introduce a way to detect separation scenarios in a n-dimensional space. A dimensionality reduction technique is applied to the geopotential height at 500 hPa extracted from two different ensemble prediction systems (the Japanese Mesoscale Ensemble Prediction System and the North American National Centers for Environmental Prediction). In the resulting 3-dimensional latent space, trajectories of ensemble members at different initialization times can also part away. We show that these separations are linked to attracting atmospheric trajectories.Further, the different techniques developed provide information on controllability, particularly where and when a manipulation could be performed.