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| 2. |
- Aimi, Hikaru, et al.
(författare)
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Endwise type lignin present as small lignin fragments linked to carbohydrate
- 2005
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Ingår i: Chemistry and performance of composites containing wood and natural plant fibres. - Carlton, VIC : Appita. ; , s. 427-430
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Konferensbidrag (refereegranskat)abstract
- The content of glyceraldehyde-2-aryl ether type structure in water soluble LCC fractions, which was obtained from Japanese cedar and birch residual wood meal after MWL isolation, was determined by the use of ozonation method. Quite high amount of glyceraldehyde-2-aryl ether type structure was found in water soluble LCC fractions of both species, which was about 3-5 times higher than that of other fractions. This result as well as the high content of β-1 structure in these fractions shown in our previous papers suggest that lignin in these fractions has characteristics as endwise type lignin, because abundance of both of these structures are typical for this type of lignin. These results are in good accordance with the generally accepted hypothesis that glyceraldehyde-2-aryl ether type structure and β-1 structure are generated at the same time by radical coupling reaction. It was also indicated that these two structures are present very close to each other in lignin.
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| 3. |
- Harakawa, Hiroki, et al.
(författare)
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A super-Earth orbiting near the inner edge of the habitable zone around the M4.5 dwarf Ross 508
- 2022
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 74:4, s. 904-922
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Tidskriftsartikel (refereegranskat)abstract
- We report the near-infrared radial velocity (RV) discovery of a super-Earth planet on a 10.77 d orbit around the M4.5 dwarf Ross 508 (Jmag = 9.1). Using precision RVs from the Subaru Telescope IRD (InfraRed Doppler) instrument, we derive a semi-amplitude of 3.92ms−1, corresponding to a planet with a minimum mass msini=4.00M⊕. We find no evidence of significant signals at the detected period in spectroscopic stellar activity indicators or MEarth photometry. The planet, Ross 508 b, has a semi-major axis of 0.05366au. This gives an orbit-averaged insolation of ≈1.4 times the Earth’s value, placing Ross 508 b near the inner edge of its star’s habitable zone. We have explored the possibility that the planet has a high eccentricity and its host is accompanied by an additional unconfirmed companion on a wide orbit. Our discovery demonstrates that the near-infrared RV search can play a crucial role in finding a low-mass planet around cool M dwarfs like Ross 508.
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| 4. |
- Hirano, T., et al.
(författare)
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An Earth-sized Planet around an M5 Dwarf Star at 22 pc
- 2023
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 165:3
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Tidskriftsartikel (refereegranskat)abstract
- We report on the discovery of an Earth-sized transiting planet (R p = 1.015 ± 0.051 R ⊕) in a P = 4.02 day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc. The planet candidate was first identified by analyzing the light-curve data obtained by the K2 mission, and it is here shown to exist in the most recent data from TESS. Combining the light curves with the data secured by our follow-up observations, including high-resolution imaging and near-infrared spectroscopy with IRD, we rule out false-positive scenarios, finding a low false-positive probability of 2 × 10−4. Based on IRD’s radial velocities of K2-415, which were sparsely taken over three years, we obtain a planet mass of 3.0 ± 2.7 M ⊕ (M p < 7.5 M ⊕ at 95% confidence) for K2-415b. Being one of the lowest-mass stars (≈0.16 M ⊙) known to host an Earth-sized transiting planet, K2-415 will be an interesting target for further follow-up observations, including additional radial velocity monitoring and transit spectroscopy.
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| 5. |
- Ito, Hiroaki, et al.
(författare)
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COMPARISON OF THE β-O-4 BOND CLEAVAGE MECHANISM OF C6-C3 AND C6-C2 LIGNIN MODEL COMPOUNDS DURING ACIDOLYSIS
- 2009
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Ingår i: 15th International Symposium on Wood, Fiber and Pulping Chemistry, Oslo, Norway June 15 – 18 2009. ; , s. P-052
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Konferensbidrag (refereegranskat)abstract
- The cleavage mechanism of β-O-4 bond was comparedbetween a C6-C3 and a C6-C2 type lignin modelcompounds, veratrylglycerol-β-guaiacyl ether (VG), andveratrylglycol-β-guaiacyl ether (V’G), under acidolysisconditions (82% aqueous 1,4-dioxane solution containingHBr or HCl at 85oC). The disappearance rate of V’G wasfaster than VG. It was confirmed that V’G primarilyconverts into an enol ether compound, 1-(2-methoxyphenoxy)-2-(3,4-dimethoxyphenyl)ethylene, viathe H2O elimination, and subsequently, the β-O-4 bondcleaves affording guaiacol and a Hibber’s ketone, 3,4-dimethoxyphenylacetaldehyde. On the other hand, themechanism for the VG disappearance was unclear mainlybecause of the extreme lability of 2-(2-methoxyphenoxy)-3-(3,4-dimethoxyphenyl)prop-2-en-1-ol, another enolether compound. The proton activity in two acidolysissystems, 0.20 mol/l HBr and 0.25 mol/l HCl, wereassumed to be the same based on the observation that thehydrolysis rates of a carbohydrate model compound,methyl α-D-glycopyranoside, were the same in bothsystems. The disappearance rates of V’G in these systemswere almost the same, while VG disappeared faster in theHBr system. These results suggest that the mechanism ofthe disappearances of VG and V’G is not the same and thecounter anions of the acids influence the disappearancerate of VG more significantly than V’G.
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| 6. |
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| 7. |
- Karlsson, Olov, et al.
(författare)
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Isolation of lignin-carbohydrate bonds in wood : model experiments and preliminary application to pine wood
- 2004
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Ingår i: Journal of Wood Science. - : Springer Science and Business Media LLC. - 1435-0211 .- 1611-4663. ; 50:2, s. 141-150
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Tidskriftsartikel (refereegranskat)abstract
- A novel method for analysis of benzylic ether type lignin-carbohydrate bonds has been developed by using model compounds. Four diastereomers of model compound 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-3-(methyl -d-glucopyranoside-6-O-yl)-1-propanol (GGMGP), were ozonized in acetic acid/water/methanol 16:3:1 for 1h at 0°C. The product from ozonation of each diastereomer was saponified and the corresponding -etherified tetronic acid (TAMGP) was isolated using ion exchange chromatography. Minor amounts of methyl -d-glucopyranoside (MGP) and small amounts of a gluconic acid etherified with tetronic acid (TAGLCA), tetronic acid, gluconic acid, and glyceric acid were detected in the product mixture of ozonated benzylic ether type model compounds. The results suggest that a benzyl ether bond between lignin and carbohydrate is rather stable during the ozone treatment. Acid treatments with sulfuric acid or trifluoroacetic acid of the derived TAMGP led to cleavage of the glucosidic bond but only a small amount of products (tetronic acid and glucose) resulting from cleavage of the -ether bond were formed. The successful chemical treatments were used for studies of benzylic ether bonds in Japanese red pine. The results suggest the presence of benzylic ether bonds to polysaccharides in the wood.
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| 8. |
- Karlsson, Olov, et al.
(författare)
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Ozonation of a lignin-carbohydrate complex model compound of the benzyl ether type
- 2000
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Ingår i: Journal of Wood Science. - 1435-0211 .- 1611-4663. ; 46:3, s. 263-265
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Tidskriftsartikel (refereegranskat)abstract
- Evidence for the presence of lignin-carbohydrate bonds of the benzylic ether type in wood and pulps may be obtained by use of ozonation treatment to selectively degrade the lignin. It was found that the benzyl ether bond in 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxy-phenoxy)-3-(methyl--d-glucopyranosid-6-O-yl)-1-propanol was rather stable during ozonation in acetic acid-water-methanol 1631 at 0°C. The corresponding acid, 3,4-dihydroxy-2-(methyl--d-glucopyranosid-6-O-yl)-butanoic acid, was found to be the major reaction product. The use of ozonation followed by acid hydrolysis in connection with studies of lignincarbohydrate linkages is briefly discussed.
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| 9. |
- Kuzuhara, Masayuki, et al.
(författare)
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Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy
- 2024
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 969:1
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Tidskriftsartikel (refereegranskat)abstract
- Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (P(or)b) of 12.76 days. The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous P-orb from TESS data. We confirmed the transit signal and P-orb using ground-based photometry with MuSCAT2 and MuSCAT3, and validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host star is inactive, with an X-ray-to-bolometric luminosity ratio of log L-X/L-bol approximate to - 5.7. Joint analysis of the light curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 +/- 0.05 R-circle plus, a 3 sigma mass upper limit of 3.9M(circle plus), and an equilibrium temperature of 315 +/- 6 K assuming zero albedo. The transmission spectroscopy metric (TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
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| 10. |
- Matsumoto, Taro, et al.
(författare)
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Ninein Is Expressed in the Cytoplasm of Angiogenic Tip-Cells and Regulates Tubular Morphogenesis of Endothelial Cells
- 2008
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 28, s. 2123-2130
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Tidskriftsartikel (refereegranskat)abstract
- Objective— Angiogenesis is an integral part of many physiologicalprocesses but may also aggravate pathological conditions suchas cancer. Development of effective angiogenesis inhibitorsrequires a thorough understanding of the molecular mechanismsregulating vessel formation. The aim of this project was toidentify proteins that regulate tubular morphogenesis of endothelialcells.Methods and Results— Phosphotyrosine-dependent affinity-purificationand mass spectrometry showed tyrosine phosphorylation of nineinduring tubular morphogenesis of endothelial cells. Ninein wasrecently identified as a centrosomal microtubule-anchoring protein.Our results show that ninein is localized in the cytoplasm inendothelial cells, and that it is highly expressed in the vasculaturein normal and pathological human tissues. Using embryoid bodiesas a model of vascular development, we found that ninein isabundantly expressed in the cytoplasm of endothelial cells duringsprouting angiogenesis, in particular in the sprouting tip-cell.In accordance, siRNA-dependent silencing of ninein in endothelialcells inhibited tubular morphogenesis.Conclusions— In this study, we show that ninein is expressedin developing vessels and in endothelial tip cells, and thatninein is critical for formation of the vascular tube. Thesedata strongly implicate ninein as an important new regulatorof angiogenesis.Proteins orchestrating morphological changes accompanying formationof the vascular tube constitute new targets for antiangiogenictherapy. In this study, we identify the microtubule-anchoringprotein ninein as an important new regulator of tubular morphogenesisof endothelial cells. This is the first report of a functionalrole of ninein in angiogenesis.
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