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851.
852.
C. D. Bredl K. Petersen S. Arnold G. Sparn F. Steglich S. Takahashi M. Tachiki B. Runtsch T. Wolf 《Zeitschrift für Physik B Condensed Matter》1992,86(2):187-191
We report measurements of the low-temperature thermal conductivity of YBa2Cu3O7– (0.1) single crystals (T
c
=84 K) both parallel (
a, b
) and perpendicular (
c
) to the CuO2 planes. Whereas
c
(T) is found to be identical, within experimental resolution, with the phonon contribution
ph
(T),
a, b
(T) contains an additional term linear in temperature,AT. We ascribeAT to the contribution of unpaired electronic carriers residing in the chain layers. Measurements performed in external magnetic fieldsB8 T support this interpretation. Our observations can be explained by an internal multilayer (IML) model in which it is assumed that strong superconductivity is generated within the CuO2 layers and weak superconductivity is induced in the chain layers by the proximity effect. The fit of the experimental results to the IML model reveals that approximately 15% of the electronic carriers remain unpaired in YBa2Cu3O7 belowT=1 K. 相似文献
853.
854.
T. Takeda M. Fujiwara M. Kurosawa N. Takahashi M. Tamura T. Kawabata Y. Fujikawa K. N. Suzuki N. Abe T. Kubota T. Takahashi 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):811-824
In this paper, cheap liquorice residue was used to prepare activated carbon (AC), thioacetamide (TAA) was used to modify the AC, and the adsorption experiments were conducted in the simulated acid radioactive wastewater with low uranium concentration to study the adsorption behavior and mechanism for uranium by TAA modified AC (TAA–AC). The removal efficiency by TAA–AC was 92.1–98.2% from the 1 mg L?1 uranium solution at pH 2–6. The adsorption equilibrium data were well fitted by Dubinin–Radushkevich model, and the maximum adsorption capacity was estimated to be 340 mg g?1. TAA–AC showed an enhanced selectivity for uranium in the presence of competitive ions. Furthermore, the adsorption experiments were conducted in the actual acid radioactive wastewater with low uranium concentration from an in situ leach uranium mine. The high adsorption rate (98.3%) and selectivity (Kd?=?3.78×104 mL g?1) for uranium were observed in the actual acid radioactive wastewater, and the adsorption rate was found to maintain 96.2% over six cycles of adsorption–desorption. 相似文献
855.
Tadayuki Takahashi Tatsuya Ito Seong-Yun Kim 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):1067-1073
To separate heat-generating Cs from high-level liquid waste (HLLW), the extraction of Cs(I) using 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (calix[4]arene-R14) in combination with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) ionic liquids ([C n mim][NTf2], where n?=?2, 4, and 6) was investigated. Under moderately acidic conditions, the calix[4]arene-R14/[C n mim][NTf2] system showed a higher extraction efficiency (ECs) than that exhibited by the conventional calix[4]arene-R14/dichloromethane system. All extraction processes reached equilibrium within 5 min. Slope analysis revealed that the Cs:calix[4]arene-R14 inclusion complex has a 1:1 stoichiometry. The extraction was found to be exothermic and influenced by the presence of Na(I). These extraction systems exhibited high efficiency and selectivity for Cs(I) in simulated HLLW. 相似文献
856.
Dr. Kosuke Ono Shunsuke Shimo Dr. Kohei Takahashi Dr. Nobuhiro Yasuda Dr. Hidehiro Uekusa Prof. Nobuharu Iwasawa 《Angewandte Chemie (International ed. in English)》2018,57(12):3113-3117
Dynamic interconversion between large covalent organic cages was achieved simply by heating or acid/base treatment. A mixture of the boroxine cages 12‐mer and 15‐mer was cleanly converted into a pyridine adduct of the 9‐mer boroxine cage upon treatment with pyridine, and the geometry of N‐coordinated boron atoms changed from trigonal to tetrahedral. The reverse reaction was achieved by heating or acid treatment. In this process, the larger boroxine cages 12‐mer and 15‐mer were found to be entropically favored owing to the release of free pyridine molecules from 9‐mer ?6 Py. 相似文献
857.
Utilization of Donor–Acceptor Interactions for the Catalytic Acceleration of Nucleophilic Additions to Aromatic Carbonyl Compounds
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Tatsuhiro Uchikura Dr. Kosuke Ono Dr. Kohei Takahashi Prof. Nobuharu Iwasawa 《Angewandte Chemie (International ed. in English)》2018,57(8):2130-2133
A conceptually new method for the catalytic electrophilic activation of aromatic carbonyl substrates, by utilizing donor–acceptor interactions between an electron‐deficient macrocyclic boronic ester host ( [2+2] BTH‐F ) and an aromatic carbonyl guest substrate, was realized. In the presence of a catalytic amount of [2+2] BTH‐F , dramatic acceleration of the nucleophilic addition of a ketene silyl acetal towards either electron‐rich aromatic aldehydes or ketones was achieved. Several control experiments confirmed that inclusion of the aromatic substrates within [2+2] BTH‐F , through efficient donor–acceptor interactions, is essential for the acceleration of the reaction. 相似文献
858.
859.
860.
A liquid jet emerging from a nozzle or an orifice whose outlet is slightly elliptic has a series of minute-amplitude waves on its surface. A quite simple technique is proposed which enables detecting such waves even if they are no longer recognizable with the aid of ordinary backlighting of the jet.This note describes a part of a study Measurements of dynamic surface tension in relation to phase-change heat transfer which was subsidized from the Ministry of Eduction, Science and Culture, Japan through Grant No. 02650167 相似文献