Van der Waals density functional study of n -alkane adsorbed on metal surfaces

Hamamoto Y., Shimada T., Kimura T., et al. Van der Waals density functional study of n -alkane adsorbed on metal surfaces. Physical Review B 110, 075409 (2024); https://doi.org/10.1103/PhysRevB.110.075409.We present a comprehensive study of n-alkane adsorbed on metal surfaces using the van der Waals density functional (vdW-DF) method. This method outperforms the density functional theory calculations within the local density or generalized gradient approximation in terms of a better description of a wide range of physisorption systems. Especially, our results demonstrate that vdW-DFs with improved accuracy nicely predict the adsorption heights of n-alkanes on close-packed metal surfaces. We also show that the C-H stretching frequencies and infrared absorption spectra are useful for discriminating the competing adsorption structures. Detailed analyses of the properties of n-alkanes on metal surfaces, however, reveal some discrepancies with experimental results, suggesting that further improvement of vdW-DF or the application of a more sophisticated technique is necessary for a systematic description of the n-alkane-metal interfaces with higher accuracy

Spatially resolved metabolic distribution for unraveling the physiological change and responses in tomato fruit using matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI–MSI)

Information on spatiotemporal metabolic behavior is indispensable for a precise understanding of physiological changes and responses, including those of ripening processes and wounding stress, in fruit, but such information is still limited. Here, we visualized the spatial distribution of metabolites within tissue sections of tomato (Solanum lycopersicum L.) fruit using a matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI–MSI) technique combined with a matrix sublimation/recrystallization method. This technique elucidated the unique distribution patterns of more than 30 metabolite-derived ions, including primary and secondary metabolites, simultaneously. To investigate spatiotemporal metabolic alterations during physiological changes at the whole-tissue level, MALDI–MSI was performed using the different ripening phenotypes of mature green and mature red tomato fruits. Although apparent alterations in the localization and intensity of many detected metabolites were not observed between the two tomatoes, the amounts of glutamate and adenosine monophosphate, umami compounds, increased in both mesocarp and locule regions during the ripening process. In contrast, malate, a sour compound, decreased in both regions. MALDI–MSI was also applied to evaluate more local metabolic responses to wounding stress. Accumulations of a glycoalkaloid, tomatine, and a low level of its glycosylated metabolite, esculeoside A, were found in the wound region where cell death had been induced. Their inverse levels were observed in non-wounded regions. Furthermore, the amounts of both compounds differed in the developmental stages. Thus, our MALDI–MSI technique increased the understanding of the physiological changes and responses of tomato fruit through the determination of spatiotemporally resolved metabolic alterations

Development and Performance of the Engineering Model of ARICA-2

We present the status of the engineering model (EM) of 2U Cubesat, AGU Remote Innovative Cubesat Alert system-2 (ARICA-2). The main goal of ARICA-2 is to demonstrate the real-time alert system of transient astronomical sources, such as gamma-ray bursts (GRBs), using commercial satellite network services such as Iridium and Globalstar. In parallel, we have a dedicated amateur mission to provide a store and forward capability for communication among amateurs. The GRB alert and the housekeeping data are also broadcast through the amateur CW transmitter. ARICA-2 was selected as one of the JAXA Innovative Satellite Technology Demonstration-4 projects in 2022 and is scheduled to be launched in the Japanese fiscal year 2025. The communication component of ARICA-2 has two commercial satellite network devices: Inmarsat\u27s SBD9603N, Globalstar\u27s STX-3, and the UHF transmitter using 435 MHz amateur frequency. The onboard computer is Sony\u27s Spresense, low-power, and six-core microcontroller board. Thanks to its multi-core processor, Spresense can run tasks in parallel by processing in individual cores, which reduces the risk of a single failure. The gamma-ray detector comprises two layers of scintillator crystals, Csl(TI) and EJ-270. The scintillation lights of each crystal are read out by eight chips of Hamamatsu\u27s MPPC S14160-6050HS. The attitude control component consists of three-axis magnetic torques, a gyro sensor, a magnetic sensor, and infrared cameras. The infrared cameras work as the Sun\u27s and the Earth\u27s sensors. The EPS, battery, solar panels, and a 2U structure are space-qualified components of ACC-Clyde Space Inc. The development of the engineering model (EM) started in August 2023. We complete the manufacture of most of the components in February 2024. And then, the integration of the EM finished on May 2024. We report the development and various test results of the EM of ARICA-2

Discussion

海外地域調査と地誌学 : 地理学の貢献と課