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71.
The spectrum of magnetic resonance is typically affected by a modulated structure in an incommensurate phase, resulting in the broadened spectrum characterized by ‘edge singularities’. We demonstrate that the modulated structure in the crystal where molecular motion exists is responsible for the narrowing of the spectrum in the fast motional region by means of the simulation of 2H NMR spectrum of [Mg(H2O)6][SiF6]. The program developed by combining the theories of phase solitons in the incommensurate phase and motional change of 2H NMR spectrum was used for the simulation. We obtained a good agreement between the theoretical 2H NMR spectrum and experimental one for [Mg(H2O)6][SiF6]. 相似文献
72.
Masami Sawada Yasuo Okumura Hitoshi Yamada Yoshio Takai Shigetoshi Takahashi Takahiro Kaneda Keiji Hirose Soichi Misumi 《Journal of mass spectrometry : JMS》1993,28(12):1525-1528
Using fast atom bombardment (FAB) mass spectrometry (MS), cross-chiral relationships were confirmed for the first time for the diasteromeric host-guest complexations between the chiral crown ether host (1) and the chiral organic ammonium ion guest (2) on the basis of the relative peak intensities (RPI). Both host–guest combinations (R, R, R, R) – 1, (R) – 2 and (S, S, S, S) – 1, (S) – 2 obviously provided larger RPI values than the combination of both (R, R, R, R) – 1, (S) – 2 and (S, S, S, S) – 1, (R) – 2 by a factor of 1.6 as an averaged value: 1.87 (n = 4)/1.16 (n = 4) = 1.6. These results are consistent with the expected stabilities of the host-guest complexations by CPK model examinations. Successfully observed cross-chiral examinations strongly suggest a potentially useful FABMS/RPI methodology for rapidly searching newly designed and synthesized crown ether-like host compounds with a higher degree of enantioselectivity. 相似文献
73.
A series of iminodiacetic acid (IDA)-linked polyamides (DpPyPyPy-IDA-PyPyPyDp) were prepared and constitute polyamides joined head-to-head by a functionalizable five-atom linker. It was found that the IDA linker exerts a unique influence over the DNA binding conformation differing from both the beta-alanine (extended) or gamma-aminobutyric acid (hairpin) linkers, resulting in cooperative parallel side-by-side 2:1 binding in an extended conformation most likely with a staggered versus stacked alignment. A generalized variant of a fluorescent intercalator displacement (FID) assay conducted on a series of hairpin deoxyoligonucleotides containing a systematically varied A/T-rich binding-site size was used to distinguish between the binding modes of the IDA-linked polyamides. 相似文献
74.
The electrical resistivity of the hybridized 4f-(5d/6s) system interacting with LA phonons is calculated by applying the memory function method to the periodic Anderson model in Hartree-Fock approximation. We propose a new mechanism to explain in part the anomalous resistivity of mixed valence compounds such as CePd3. For finite hybridizationV a finite fraction of 4f electrons participates in electrical conduction leading to an essential change of the normald band current. Resistivity and the fraction of 4f electrons increase with increasing value of [V/(E–)]2 where (E–) is the distance between the effective positionE of the 4f level and the chemical potential. In typical mixed valence systems [V/(E–)]2 is strongly temperature dependent and decreases with increasing temperature. This explains the high temperature resistivity behaviour of CePd3. For (E–) being small compared to the Debye-temperature the resistivity is enhanced and becomes extremely sensitive to small changes of (E–).Work performed within the research program of the Sonderforschungsbereich 125, Aachen-Jülich-Köln 相似文献
75.
N Otsuka M Fukunaga K Morita S Ono K Nagai T Furukawa S Yanagimoto T Tomomitsu H Kawahara H Tanaka 《Radioisotopes》1988,37(6):330-335
In order to detect the varicocele, scrotal scintigraphies by using 99mTc-HSA-D were performed in 14 patients with male infertile or palpable mass in left scrotum on physical examinations. Abnormal pooling of 99mTc-HSA-D, indicative of varicocele lesion, could be found in left scrotum in 9 cases, confirmed surgically or clinically. Compared with 99mTc-HSA, 99mTc-HSA-D was superior in high uptake ratio of varicocele to soft tissue and in nonvisualization of bladder. Thus, 99mTc-HSA-D scrotal scintigraphy seemed to be of a great use to detect the varicocele. 相似文献
76.
Electrochemically driven clathration/declathration of ferrocene and its derivatives by a nanometer-sized coordination cage 总被引:1,自引:0,他引:1
The electrochemical, NMR, and crystallographic studies clearly indicate that the clathration and declathration of ferrocene and its derivatives in a self-assmbled Pd(II)-linked nanometer-sized cage can be controlled by the oxidation state of the guest. Namely, the guests are clathrated when they are reduced but declathrated when they are oxidized. The process is rapid on the NMR time scale but slow on the CV time scale. 相似文献
77.
Hetero-biaryl compounds were prepared via the Suzuki-Miyaura coupling reaction of hetero-aryl moieties containing an unprotected NH2 group and arylboronic acids. D-t-BPF was found to be an efficient ligand for the cross-coupling of NH2-unprotected hetero-aryl chlorides with phenylboronic acid. 相似文献
78.
Yasuhiro Ono Ryuji IshikawaYuzuru Miyazaki Yoshinobu IshiiYukio Morii Tsuyoshi Kajitani 《Journal of solid state chemistry》2002,166(1):177-181
The layered oxide thermoelectric material β-Na0.67CoO2 has been studied by powder neutron diffraction, electric and magnetic measurements. This compound includes an edge-sharing CoO6 slab and a highly vacant Na+ sheet in a unit cell (space group symmetry C2/m, a=4.9023(4) Å, b=2.8280(2) Å, c=5.7198(6) Å and β=105.964(6)° at 300 K). The evaluated formal valence of cobalt ion, +3.33(1), is ascribed to the coexistence of Co3+ and Co4+ in the ratio 2:1. Polycrystalline β-Na0.67CoO2, a p-type thermoelectric material, exhibits metallic behavior of the electric resistivity below 300 K. The Curie-Weiss-type magnetic susceptibility indicates antiferromagnetic interactions between magnetic cobalt ions in the edge-sharing CoO6 slab. 相似文献
79.
Hirofumi Ono Hiroyuki Yamada Shigenobu Matsuda Kunihiko Okajima Takeshi Kawamoto Hideki Iijima 《Cellulose (London, England)》1998,5(4):231-247
An intensive study for aqueous microcrystalline cellulose (MCC) suspensions was carried out in view of the relationship between a viscosity and a 1H spin-spin relaxation time (T2) of water. An investigation was carried out for four suspension systems with the different particle size distributions. The proton mole ratio () of bound water against MCC particles and T2 of bound water (T2,b) were evaluated from the T2 values obtained by Carr-Purcell- Meiboom-Gill (C.P.M.G) method and those by solid echo method, respectively. As a result of these analyses, the T2,b value for the aqueous MCC suspension was evaluated as 5 × 10–3 s and it was found that the system having a larger tended to show a higher viscosity. By relating the above results to the observation of the suspensions by an optical microscope, it was concluded that a network formed by MCC particles plays an important role in generating a high viscosity of MCC suspension, and that an averaged mobility of water molecules is sensitively affected by the network structure. 相似文献
80.
Nobuko WatanabeYasuhiro Nagashima Takahiro YamazakiMasakatsu Matsumoto 《Tetrahedron》2003,59(26):4811-4819
Tetrabutylammonium fluoride induces the decomposition of 1-tert-butyl-4,4-dimethyl-5-(3-siloxyphenyl)-2,6,7-trioxabicyclo[3.2.0]heptane (4a) in DMSO to form an oxyanion of aromatic ketone (14a) as an emitter with high singlet-chemiexcitation yield comparable with that for a chemically initiated electron exchange luminescence (CIEEL) active dioxetane producing an oxyanion of aromatic ester as an emitter. A 7-siloxynaphthalen-2-yl analog (4b) was found on similar treatment to emit light with the maximum wavelength the longest among CIEEL-active dioxetanes hitherto known. 相似文献