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排序方式: 共有289条查询结果,搜索用时 15 毫秒
91.
92.
Fumihiko Ozaki Dr. Shunsuke Tanaka YoungHyun Choi Dr. Wataru Osada Kozo Mukai Dr. Mitsuaki Kawamura Dr. Masahiro Fukuda Dr. Masafumi Horio Prof. Dr. Takanori Koitaya Prof. Dr. Susumu Yamamoto Prof. Dr. Iwao Matsuda Prof. Dr. Taisuke Ozaki Prof. Dr. Jun Yoshinobu 《Chemphyschem》2023,24(22):e202300477
Sulfur vacancy on an MoS2 basal plane plays a crucial role in device performance and catalytic activity; thus, an understanding of the electronic states of sulfur vacancies is still an important issue. We investigate the electronic states on an MoS2 basal plane by ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and density functional theory calculations while heating the system in hydrogen. The AP-XPS results show a decrease in the intensity ratio of S 2p to Mo 3d, indicating that sulfur vacancies are formed. Furthermore, low-energy components are observed in Mo 3d and S 2p spectra. To understand the changes in the electronic states induced by sulfur vacancy formation at the atomic scale, we calculate the core-level binding energies for the model vacancy surfaces. The calculated shifts for Mo 3d and S 2p with the formation of sulfur vacancy are consistent with the experimentally observed binding energy shifts. Mulliken charge analysis indicates that this is caused by an increase in the electronic density associated with the Mo and S atoms around the sulfur vacancy as compared to the pristine surface. The present investigation provides a guideline for sulfur vacancy engineering. 相似文献
93.
Mukai T Suganuma N Soejima K Sasaki J Yamamoto F Maeda M 《Chemical & pharmaceutical bulletin》2008,56(3):260-265
Matrix metalloproteinase-2 (MMP-2) is an attractive target for the diagnosis of cancer and atherosclerosis in nuclear imaging. A cyclic decapeptide, cCTTHWGFTLC (cCTT), has been used as the mother compound for the development of MMP-2-imaging agents with high potency and selectivity. Most of radiolabeled derivatives of cCTT currently developed for in vivo studies of MMP-2, however, suffer from low accumulation in the target tissues, such as tumors. For enhanced in vivo stability and tissue penetration, we designed a linear beta-tetrapeptide analog, H-beta 3-Phe-beta-Ala-beta 3-Trp-beta 3-His-OH (1), to mimic cCTT. The component beta-amino acids were prepared by reduction of N-protected alpha-amino acid methyl esters to the alcohols, followed by conversion into the cyanides, and subsequent hydrolysis. Compound 1 was obtained from these beta-amino acids by the conventional solution method. In MMP-2 inhibition assay, compound 1 displayed desirably significant inhibition, which was comparable to cCTT. These findings suggest that compound 1 may serve as a mother compound in the design and development of in vivo MMP-2-imaging agents. 相似文献
94.
Keisuke HIROTA Hiroo MATSUSE Shunji KOYA Ryuki HASHIDA Masafumi BEKKI Yoko YANAGA Kiyoko JOHZAKI Mami TOMINO Fumihiko MOURI Satoshi MORISHIGE Shuki OYA Yoshitaka YAMASAKI Koji NAGAFUJI Naoto SHIBA 《Physical Therapy Research》2021,24(1):69
Objective: Muscle atrophy is associated with autologous stem cell transplantation (ASCT)-related outcomes in patients with malignant lymphoma (ML). However, the impact of ASCT on muscle mass remains unclear in patients with ML. The aims of this study were to investigate changes in muscle mass and risk profiles for muscle atrophy after ASCT. Method: We enrolled 40 patients with refractory ML (age 58 [20-74] years, female/male 16/24, body mass index (BMI) 21.1 kg/m2 [17.1-29.6]). Psoas muscle mass was assessed using the psoas muscle index (PMI) before and after ASCT. Statistical analysis used: Independent factors associated with a severe decrease rate of change in PMI were evaluated by decision-tree analysis, respectively. Results: PMI was significantly decreased after ASCT (4.61 vs. 4.55 cm2/m2; P=0.0425). According to the decision-tree analysis, the regimen was selected as the initial split. The rates of change in PMI were −5.57% and −3.97% for patients administered MCEC and LEED, respectively. In patients who were administered LEED, the second branching factor was BMI. In patients with BMI < 20.3 kg/m2, the rate of change in PMI was −7.16%. On the other hand, the rate of change in PMI was 4.05% for patients with BMI ≥ 20.3 kg/m2. Conclusion: We demonstrated that muscle mass decreased after ASCT in patients with ML. Patients who received MCEC and patients with low BMI were at risk for a decrease in muscle mass. 相似文献
95.
Dr. Naoki Ousaka Fumihiko Mamiya Yoshiaki Iwata Dr. Katsuyuki Nishimura Prof. Dr. Eiji Yashima 《Angewandte Chemie (International ed. in English)》2017,56(3):791-795
A one-handed 310-helical hexapeptide is efficiently encapsulated within the helical cavity of st-PMMA when a fullerene (C60) derivative is introduced at the C-terminal end of the peptide. The encapsulation is accompanied by induction of a preferred-handed helical conformation in the st-PMMA backbone with the same-handedness as that of the hexapeptide to form a crystalline st-PMMA/peptide-C60 inclusion complex with a unique optically active helix-in-helix structure. Although the st-PMMA is unable to encapsulate the 310-helical peptide without the terminal C60 unit, the helical hollow space of the st-PMMA is almost filled by the C60-bound peptides. This result suggests that the C60 moiety can serve as a versatile molecular carrier of specific molecules and polymers in the helical cavity of the st-PMMA for the formation of an inclusion complex, thus producing unique supramolecular soft materials that cannot be prepared by other methods. 相似文献
96.
97.
Naoto Yamaguchi Tatsuya Naiki Takamitsu Kohzuma Toshikazu Takada Fumihiko Sakata Seiji Mori 《Theoretical chemistry accounts》2011,128(2):191-206
Model reaction mechanisms in the biosynthesis of prostaglandin D2 (PGD2) and prostaglandin E2 (PGE2) from prostaglandin H2 with PGD2/E2 synthase were examined using the ab initio second-order Møller–Plesset perturbation method and density functional theory. The reaction was modeled similar to the isomerization of 2,3-dioxabicyclo[2.2.1]heptane to 3-hydroxycyclopentanone in the presence of MeS?. An explicit solvation of two H2O molecules was also considered, and two probable types of reaction mechanisms were demonstrated. One mechanism starts with proton abstraction from an oxygen-bound carbon at the endoperoxide by a thiolate ion and the other is stepwise and involves attack of a thiolate anion on an oxygen of the endoperoxide group in the first step with protonation of the other oxygen, followed by deprotonation from a carbon-attached oxygen to break an O–S bond to yield PGD2 or PGE2. We also found that the mPW1LYP hybrid method was superior to the B3LYP functional for systems with respect to the state-of-the-art CCSD(T) energetics. 相似文献
98.
Ishii N Mamiya J Ikeda T Winnik FM 《Chemical communications (Cambridge, England)》2011,47(4):1267-1269
Irradiation at room temperature of α,ω-di-[4-cyanophenyl-4'-(6-hexyloxy)-azobenzene]-poly-(N-isopropylacrylamide) (Az(2)-PNIPAM) solutions in water/1,4-dioxane (6 mol% dioxane) reversibly converts a turbid suspension into a clear solution, demonstrating for the first time that cononsolvency of PNIPAM in mixed aqueous solvents in synergy with preferential chromophore solvation can act as actuators of responsive systems. 相似文献
99.
Kashiwagi T Yamada N Hirayama K Suzuki C Kashiwagi Y Tsuchiya F Arata Y Kunishima N Morikawa K 《Journal of the American Society for Mass Spectrometry》2000,11(1):54-61
Electrospray ionization mass spectrometry (ESI-MS) was applied to the analysis of the dissociation and denaturation processes of a heterodimeric yeast killer toxin SMKT. The two distinct subunits of SMKT noncovalently associate under acidic conditions, but become dissociated and denatured under neutral and basic conditions. In order to understand the unique pH-dependent denaturation mechanism of this protein, a pH titration was performed by utilizing ESI-MS. The molecular ions of the heterodimer which possesses the highly ordered structure, were mainly observed below pH 4.6. However, the two subunits immediately dissociated at this pH. The spectra measured with various settings of the mass spectrometer indirectly demonstrated that the pH-dependent dissociation occurs in the liquid phase. The current result as well as the three-dimensional structure of SMKT suggest that the deprotonation of a specific carboxyl group triggers a cooperative dissociation process of this protein. In conclusion, the pH titration of a protein by ESI-MS is particularly effective, when the unfolding process or the biological function of the protein is related to the interaction with other molecules. 相似文献
100.
Masakatsu Matsumoto Fumihiko Kakuno Aoi Kikkawa Naoyuki Hoshiya Nobuko Watanabe Hisako K. Ijuin 《Tetrahedron letters》2009,50(20):2337-2341
Bicyclic dioxetane 5 bearing a 3-hydroxynaphthalen-2-yl group and its analogs 14 and 15 decomposed to give light with efficiencies of only 0.002-0.005% in a tetrabutylammonium fluoride (TBAF)/THF system, which was as expected for dioxetanes with a so-called ‘even’ substitution pattern. However, the chemiluminescence efficiencies (ΦCL) markedly increased when these dioxetanes were decomposed with alkaline metal t-butoxide in THF. This enhancement of ΦCL by alkaline metal ion was most likely due to the highly ordered conformation of an aromatic ring by chelate formation of the metal ion with both an oxido anion and oxygen atom of a tetrahydrofuran ring in an intermediary dioxetane like 12. Alkaline metal ion-enhanced chemiluminescence was similarly observed for dioxetane 6 bearing a 2-hydroxyphenyl group. 相似文献