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Nakata, Yuto; Sasaki, Takehiko*; Thomsen, B.; Shiga, Motoyuki
Chemical Physics Letters, 845, p.141285_1 - 141285_9, 2024/06
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Using density functional theory and metadynamics simulations, we study cellobiose hydrolysis and glucose hydrogenation with silica-supported platinum and palladium catalysts in hot water, relevant to green cellulose conversion. It is found that cellobiose hydrolysis can proceed by the attack of hydrogen atoms adsorbed on metal or protons spilled over to silica forming glucose. Glucose can then be hydrogenated by hydrogen atoms adsorbed at platinum/water interface forming sorbitol. The reaction barriers of hydrolysis and hydrogenation at platinum/water interface are both lower than that at palladium/water interface, which explains the experimental finding that the platinum performs as a better catalyst than palladium.
Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*
Geochemical Journal, 57(5), p.155 - 175, 2023/00
Times Cited Count：2 Percentile：32.37(Geochemistry & Geophysics)In the thick marine sediments, groundwater altered from seawater during the burial diagenesis may exist. Such altered ancient seawater will be called fossil seawater. In such a field, groundwater flow is considered extremely slow because it is not affected by the seepage of meteoric water even after the uplift. During diagenesis, dehydration from silicates causes changes such as a decrease in the salinity of the porewater. However, dehydration reactions alone cannot quantitatively explain water chemistry changes. In this study, we developed an analytical model that considers the dehydration reaction from silicates during the burial process and the upward migration of porewater due to compaction and examined the possible evolution of porewater chemistry. The results showed that the water chemistry, which was strongly influenced by the dehydration reaction from opal-A to quartz and from smectite, was similar to the observations from boring surveys. The results suggest that the fossil seawater formed during the diagenesis may have been preserved since the uplift and strongly supports the slow groundwater flow in the area where the fossil seawater exists.
Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count：7 Percentile：39.36(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*
no journal, ,
no abstracts in English
Komura, Yuto*; Kashiwaya, Koki*; Miyakawa, Kazuya; Nakata, Kotaro*; Koike, Katsuaki*
no journal, ,
no abstracts in English
Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*
no journal, ,
In the thick marine sediments, groundwater altered from seawater during the burial diagenesis may exist. Such altered ancient seawater will be called fossil seawater. In such a field, groundwater flow is considered extremely slow because it is not affected by the seepage of meteoric water even after the uplift. During diagenesis, dehydration from silicates causes changes such as a decrease in the salinity of the porewater. However, dehydration reactions alone cannot quantitatively explain water chemistry changes. In this study, we developed an analytical model that considers the dehydration reaction from silicates during the burial process and the upward migration of porewater due to compaction and examined the possible evolution of porewater chemistry. The results showed that the water chemistry, which was strongly influenced by the dehydration reaction from opal-A to quartz and from smectite, was similar to the observations from boring surveys. The results suggest that the fossil seawater formed during the diagenesis may have been preserved since the uplift and strongly supports the slow groundwater flow in the area where the fossil seawater exists.
Komura, Yuto*; Kashiwaya, Koki*; Miyakawa, Kazuya; Nakata, Kotaro*; Koike, Katsuaki*
no journal, ,
no abstracts in English
Komura, Yuto*; Kashiwaya, Koki*; Miyakawa, Kazuya; Nakata, Kotaro*; Koike, Katsuaki*
no journal, ,
no abstracts in English
