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121.
Mg isotope fractionation in biogenic carbonates of deep-sea coral, benthic foraminifera, and hermatypic coral 总被引:1,自引:0,他引:1
Yoshimura T Tanimizu M Inoue M Suzuki A Iwasaki N Kawahata H 《Analytical and bioanalytical chemistry》2011,401(9):2755-2769
High-precision Mg isotope measurements by multiple collector inductively coupled plasma mass spectrometry were applied for
determinations of magnesium isotopic fractionation of biogenic calcium carbonates from seawater with a rapid Mg purification
technique. The mean δ26Mg values of scleractinian corals, giant clam, benthic foraminifera, and calcite deep-sea corals were −0.87‰, −2.57‰, −2.34‰,
and −2.43‰, suggesting preferential precipitation of light Mg isotopes to produce carbonate skeleton in biomineralization.
Mg isotope fractionation in deep-sea coral, which has high Mg calcite skeleton, showed a clear temperature (T) dependence from 2.5 °C to 19.5 °C: 1,000 × ln(α) = −2.63 (±0.076) + 0.0138 (±0.0051) × T(R
2 = 0.82, p < 0.01). The δ26Mg values of large benthic foraminifera, which are also composed of a high-Mg calcite skeleton, can be plotted on the same
regression line as that for deep-sea coral. Since the precipitation rates of deep-sea coral and benthic foraminifera are several
orders of magnitude different, the results suggest that kinetic isotope fractionation may not be a major controlling factor
for high-Mg calcite. The Mg isotope fractionation factors and the slope of temperature dependence from deep-sea corals and
benthic foraminifera are similar to that for an inorganically precipitated calcite speleothem. Taking into account element
partitioning and the calcification rate of biogenic CaCO3, the similarity among inorganic minerals, deep-sea corals, and benthic foraminiferas may indicate a strong mineralogical
control on Mg isotope fractionation for high-Mg calcite. On the other hand, δ26Mg in hermatypic corals composed of aragonite has been comparable with previous data on biogenic aragonite of coral, sclerosponges,
and scaphopad, regardless of species differences of samples. 相似文献
122.
Eiichi Masumoto Hiroshi Maruoka Fumi Okabe Sho Nishida Yuki Yoshimura Toshihiro Fujioka Kenji Yamagata 《Journal of heterocyclic chemistry》2011,48(1):96-104
Dihydropyridazinones 4a , 4b , N‐substituted dihydropyrazoles 5b , 5c , 5d , and O‐substituted pyrazoles 6a , 6b , 6c , 6d have been synthesized starting from spirocyclopropanepyrazole derivative 2 . Treatment of 2 with α‐chloro esters, e.g., methyl chloroacetate, ethyl chloroacetate, isopropyl chloroacetate, and tert‐butyl chloroacetate, in potassium carbonate/sodium iodide system caused ring opening and subsequent C‐ or N‐attack nucleophilic substitution to give the corresponding dihydropyridazinones 4a , 4b and N‐substituted dihydropyrazoles 5b , 5c , 5d . On the other hand, in the absence of sodium iodide, O‐substituted pyrazoles 6a , 6b , 6c , 6d were obtained from 2 via an O‐attack nucleophilic substitution. J. Heterocyclic Chem., 2011. 相似文献
123.
124.
Heisler IA Mazur K Yamaguchi S Tominaga K Meech SR 《Physical chemistry chemical physics : PCCP》2011,13(34):15573-15579
Acetic acid is capable of forming strong multiple hydrogen bonds and therefore different dimeric H-bonded structures in neat liquid phase and in solutions. The low frequency Raman spectra of acetic acid (neat, in aqueous solution and as a function of temperature) were obtained by ultrafast time and polarization resolved optical Kerr effect (OKE) measurements. Isotropic OKE measurements clearly reveal a specific totally symmetric mode related to the dimeric structure H-bond stretching mode. The effects of isotope substitution, water dilution and temperature on this mode were investigated. These results together with anisotropic OKE measurements and density functional theory calculations for a number of possible dimers provide strong evidence for the cyclic dimer structure being the main structure in liquid phase persisting down to acetic acid concentrations of 10 M. Some information about the dimer structure and concentration dependence was inferred. 相似文献
125.
Journal of Theoretical Probability - We consider symmetric stable-type processes with degenerate/singular Lévy densities via Dirichlet form theory. We give conditions of some global path... 相似文献
126.
Yoshihiro Fukumoto Koji Ohata Rui Tsukagoshi Keiich Kawanabe Haruhiko Akiyama Toshihiro Mata Misaka Kimura Noriaki Ichihashi 《Physical Therapy Research》2013,16(1):22-27
Objective: To investigate changes in hip and knee muscle strength in patients before and after total hip arthroplasty (THA) in comparison with that in healthy adults. Methods: The study included 21 women who underwent unilateral THA (THA group) and 21 age-matched healthy women (healthy group). Maximal isometric strengths of hip flexors, extensors, and abductors, and knee extensors and flexors were measured before surgery and at 4 weeks and 6 months after surgery. Results: Before surgery, muscle strength on both sides, except for hip flexors on the uninvolved side, was significantly lower in the THA group than the corresponding muscle strength in the healthy group. Up to 6 months after THA, strength of all muscle groups on both sides was significantly improved compared with their preoperative status, although the knee extensor strength on the involved side temporarily worsened at 4 weeks. However, the strength of hip extensors and knee extensors on the involved side, and hip abductors on both sides in the THA group remained below that in the healthy group. Conclusions: Our results suggest that rehabilitation specialists should consider increasing the focus on the uninvolved side and encourage patients to continue strength training beyond 6 months after surgery. 相似文献
127.
Toshihiro Yoshimura Yusuke Tamenori Nozomu Iwasaki Hiroshi Hasegawa Atsushi Suzuki Hodaka Kawahata 《Journal of synchrotron radiation》2013,20(5):734-740
Magnesium K‐edge X‐ray absorption near‐edge structure (XANES) spectra have been investigated to develop a systematic understanding of a suite of Mg‐bearing geological materials such as silicate and carbonate minerals, sediments, rocks and chemical reagents. For the model compounds the Mg XANES was found to vary widely between compounds and to provide a fingerprint for the form of Mg involved in geologic materials. The energy positions and resonance features obtained from these spectra can be used to specify the dominant molecular host site of Mg, thus shedding light on Mg partitioning and isotope fractionation in geologic materials and providing a valuable complement to existing knowledge of Mg geochemistry. 相似文献
128.
Dang Ngoc Quang Marc Stadler Jacques Fournier Toshihiro Hashimoto 《Tetrahedron》2006,62(26):6349-6354
Four azaphilones named cohaerins C-F, along with 4,5,4′,5′-tetrahydroxy-1,1′-binaphthyl were isolated from the methanolic extract of the stromata of Annulohypoxylon cohaerens (Ascomycetes, Xylariaceae). Cohaerins C-E constitute typical azaphilones, bearing a γ-lactone ring, while cohaerin F has an unprecedented carbon skeleton, lacking the lactone ring of the azaphilones and with an aliphatic side chain being attached directly to the azaphilone backbone by a C-C bond. Their structures were determined by 2D NMR, IR, UV, and CD spectroscopy. They showed moderate inhibitory activity of nitric oxide production in RAW cells, and strong and nonselective antimicrobial effects. 相似文献
129.
130.