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311.
Kotaro Suzaki Kentaro Tsuchiya Atsumu Tezaki 《Proceedings of the Combustion Institute》2007,31(1):295-303
The time resolved product formation in oxidation of dimethyl ether (DME) has been studied between 298-625 K and 20-90 torr total pressure. Near-infrared frequency modulation spectroscopy (FMS) with Herriott type multi pass optics and UV absorption spectroscopy (UV) were conducted in the same cell. The reaction was initiated by pulsed photolysis in a mixture of Cl2, O2, and DME via CH3OCH2 radical formation. The reaction process was investigated through FMS measurement of HO2 and OH, and UV measurement of CH3OCH2O2. The yields of HO2 and OH are obtained by comparison with reference mixtures, Cl2, O2, and CH3OH for HO2, and Cl2, O2, CH3OH, and NO for OH, which convert 100% of initial Cl to HO2 and OH. The CH3OCH2O2 yield is also obtained. It was found that the HO2 yield increases sharply over 500 K mainly with a longer time constant than that of R + O2 reaction, while a prompt component exists throughout the temperature range at a few percent yield. OH was found to be produced promptly at a yield considerably larger than that known for the simplest alkanes. The CH3OCH2O2 profile has a prompt rise followed by a gradual decay whose rate is consistent with the slow HO2 formation. The species profiles were successfully predicted with a model constructed by modifying the existing one to suit the reduced pressure condition. After modification, it was inferred that the HO2 formation over 500 K is secondary from HCHO + OH and HCO + O2 and a part of HCO is formed directly from the O2 adduct, whereas the HO2 formation below 500 K is governed by CH3OCH2O2 chemistry. The HCO forming pathway via isomerization-decomposition of the O2 adduct, which was not included in the former models, was supported by our quantum-chemical calculations. 相似文献
312.
Low-intensity pulsed ultrasound (LIPUS) is an established therapy for fracture repair and has been used widely in the clinics, but its underlying mechanism of action remains unclear. The aim of the current research was to determine the effect of LIPUS on gap junctional cell-to-cell intercellular communication in rat bone marrow stromal cells (BMSC) in vitro and to determine whether the ability of BMSCs to communicate by gap junctions would affect their response to LIPUS. Single or daily-multiple LIPUS treatment at 1.5 MHz, 30 mW/cm2, for 20 min was applied to BMSC. We demonstrated that BMSC form functional gap junctions and single LIPUS treatment significantly increased the intracellular dye transfer between BMSC. In addition, activated phosphorylation of ERK1/2 and p38 by LIPUS stimulation was diminished when cells were treated with a gap junction inhibitor 18β-glycyrrhetinic acid (18β). We further demonstrated that 18β diminished the significant increase in alkaline phosphatase activity following LIPUS stimulation. These results suggest a potential role of gap junctional cell-to-cell intercellular communication on the effects of LIPUS in BMSC. 相似文献
313.
Kotaro Ono 《Journal of statistical physics》2011,142(1):43-57
Within the canonical formalism, we consider a polydisperse lattice-gas model and a polydisperse continuous system interacting
with the Kac potential. We obtain rigorous expressions for free energy densities. We also exhibit phase diagrams of the bidisperse
lattice-gas model. 相似文献
314.
Dr. Shabbir Muhammad Kotaro Fukuda Takuya Minami Dr. Ryohei Kishi Dr. Yasuteru Shigeta Dr. Masayoshi Nakano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(5):1677-1685
To reveal new structure–property relationships in the nonlinear optical (NLO) properties of fullerenes that are associated with their open‐shell character, we investigated the interplay between the diradical character (yi) and second hyperpolarizability (longitudinal component, γzzzz) in several fullerenes, including C20 , C26 , C30 , C36 , C40 , C42 , C48 , C60 , and C70 , by using the broken‐symmetry density functional theory (DFT; LC‐UBLYP (μ=0.33)/6‐31G*//UB3LYP/6‐31G*). We found that the large differences between the geometry and topology of fullerenes have a significant effect on the diradical character of each fullerene. On the basis of their different diradical character, these fullerenes were categorized into three groups, that is, closed‐shell (yi=0), intermediate open‐shell (0<yi<1), and almost pure open‐shell compounds (yi?1), which originated from their diverse topological features, as explained by odd‐electron‐density and spin‐density diagrams. For example, we found that closed‐shell fullerenes include C20 , C60 , and C70 , whereas fullerenes C26 and C36 and C30 , C40 , C42 , and C48 are pure and intermediate open‐shell compounds, respectively. Interestingly, the γzzzz enhancement ratios between C30 / C36 and C40 / C60 are 4.42 and 11.75, respectively, regardless of the smaller π‐conjugation size in C30 and C40 than in C36 and C60 . Larger γzzzz values were obtained for other fullerenes that had intermediate diradical character, in accordance with our previous valence configuration interaction (VCI) results for the two‐site diradical model. The γzzzz density analysis shows that the large positive contributions originate from the large γzzzz density distributions on the right‐ and left‐extended edges of the fullerenes, between which significant spin polarizations (related to their intermediate diradical character) appear within the spin‐unrestricted DFT level of theory. 相似文献
315.
316.
Kotaro Nakamura Kazuki Kurihara Hiroshi Kawaguchi Takayuki Obata Hiroshi Ito Eiji Okada 《Optical Review》2016,23(2):316-322
Three-dimensional head models with the structures constructed from the MR head images of 40 volunteers were constructed to analyze light propagation in the subject-specific head models. The mean optical path length in the head and the partial optical path length in the brain at 13 fiducial points for each volunteer were estimated to evaluate the intersubject and spatial variability in the optical path lengths. Although the intersubject variability in the optical path lengths is very high, the spatial variability in the average of the mean optical path length and partial optical path length is similar to the previously reported data. The mean optical path length in the head increases, whereas the partial optical path length in the brain decreases with an increase in the depth of the brain surface. The partial optical path length is highly correlated with the depth of the brain surface in comparison to the mean optical path length in the head. 相似文献
317.
Kotaro Satoh Masami Kamigaito Mitsuo Sawamoto 《Journal of polymer science. Part A, Polymer chemistry》2000,38(15):2728-2733
Aqueous sulfonic acids (HOSO2R; R = CH3, Ph‐p‐CH3, and Ph‐p‐NO2), coupled with a water‐tolerant Lewis acid, ytterbium triflate [Yb(OTf)3; OTf = OSO2CF3], initiate the cationic suspension polymerization of p‐methoxystyrene (pMOS) in heterogeneous aqueous media. They induce controlled polymerization of pMOS at 30 °C, and the molecular weights of the polymers (weight‐average molecular weight/number‐average molecular weight ∼ 1.7) increase with conversion. These suspension polymerizations are initiated by the entry of sulfonic acid from the aqueous phase into the organic phase and proceed via reversible activation of the sulfonyl terminus by the Lewis acid. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2728–2733, 2000 相似文献
318.
Let X be a locally compact Polish space and G a non-discrete Polish ANR group. By C(X,G), we denote the topological group of all continuous maps endowed with the Whitney (graph) topology and by Cc(X,G) the subgroup consisting of all maps with compact support. It is known that if X is compact and non-discrete then the space C(X,G) is an l2-manifold. In this article we show that if X is non-compact and not end-discrete then Cc(X,G) is an (R∞×l2)-manifold, and moreover the pair (C(X,G),Cc(X,G)) is locally homeomorphic to the pair of the box and the small box powers of l2. 相似文献
319.
Yujiro Hayashi Prof. Dr. Hirofumi Yamaguchi Maya Toyoshima Kotaro Okado Takumi Toyo Mitsuru Shoji Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(33):10150-10159
The synthesis of a protected dephosphofostriecin, and thereby a formal synthesis of fostriecin, has been accomplished. The synthetic challenges were the construction of four stereogenic centers and the conformationally labile cis‐cis‐trans‐triene moiety. Previous total syntheses have employed at least two asymmetric reactions that required the use of an external chiral auxiliary. Although remote stereoinduction in a 1,4‐relationship is considered difficult, we have developed a notable 1,4‐asymmetric induction that utilizes an alkyne–cobalt complex for the control of C5 stereochemistry by the C8 stereogenic center. The stereochemistry at C11 was established by 1,3‐asymmetric induction with a higher‐order alkynyl‐zinc reagent. Thus, only one asymmetric reaction requiring an external chiral auxiliary was employed in this route. The labile cis‐cis‐trans‐triene unit was constructed at a late stage of the synthesis by diastereoselective coupling of a dienyne and an aldehyde unit, followed by reduction. 相似文献
320.
Masahiro Takeda Tadaaki Hashimoto Takayoshi Fujii Shin Ono Toshiaki Yoshimura Choichiro Shimasaki Hiroyuki Morita 《Heteroatom Chemistry》1999,10(5):363-367
Previously, a facile formation of a thioaldehyde by the thermolysis of a heteroaryl phenacyl sulfoxide was confirmed by the detection of a cycloadduct with 2,3‐dimethyl‐1,3‐butadiene. The usefulness of benzothiazolyl phenacyl sulfoxide as a precursor for 2‐oxo‐2‐phenylethanethial was studied under the same conditions in the presence of various dienes and anthracene. In all cases, the Diels‐Alder cycloadducts were formed in moderate to good yields, and the addition of triethylamine as external base was revealed to be effective for carrying out the thermolysis under milder reaction conditions and for the improvement of yields. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 363–367, 1999 相似文献