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31.
Kuno A. Zheng G. D. Matsuo M. Takano B. Shi J. A. Wang Q. 《Hyperfine Interactions》2002,141(1-4):321-326
In this study, 57Fe Mössbauer spectroscopy has been applied to sediments collected from Qinghai Lake in Qinghai Province, China, to investigate the vertical distribution of iron species. Their Mössbauer spectra consisted of four doublets ascribable to one paramagnetic high-spin Fe3+, two paramagnetic high-spin Fe2+ with different quadrupole splittings, and one diamagnetic low-spin Fe2+ that corresponds to pyrite (FeS2). The distribution of pyrite suggested climatic changes during the past nine thousand years. It was demonstrated that the iron speciation in the salt lake sediments by Mössbauer spectroscopy can be used to reconstruct the past environment.
相似文献32.
Tin dioxide thin films have been deposited on alumina substrates by different methods in order to test their reliability as
a breath analyser. Despite the obvious simplicity of spray pyrolysis, both the structural and electrical properties of the
films thus prepared were strongly dependent to the deposition conditions. The samples exhibited poor crystallinity and porous
microstructure. They were sensitive to ethanol vapour but since the resistance of the samples reached several MΩ, antimony
doping was performed to fit a more convenient detection range. An alternative method was then used to prepare tin dioxyde
thin films by evaporation of metallic tin followed by thermal oxidation. In this case, grain size was enhanced up to 100 nm
but films remained highly porous. The ethanol sensitivity of evaporated samples was determined. In order to study more accurately
the influence of microstructure on sensing ability, dense thin films were prepared using a CVD method with tetrabutyl tin
as precursor. Preliminary results indicated that films with different crystallite sizes could be grown by varying the deposition
temperature.
Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995 相似文献
33.
D. Moromachi A. Kuno M. Matsuo 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(2):495-498
In order to investigate the transition of tidelands, we collected sediments in Yatsu tideland and Nekozane river mouth in Tokyo Bay. The vertical distributions of elements were determined by instrumental neutron activation analysis and prompt gamma-ray analysis. In Yatsu tideland the vertical distribution changed in a great extent, which was considered as an influence of the neighboring reclamation. They were categorized into four groups, and two parameters were created by applying principal component analysis. Chemical states of iron and sulfur were also investigated by Mössbauer spectroscopy and X-ray absorption fine structure. These results show that Yatsu tideland became an anaerobic environment. 相似文献
34.
The two∑ ? reactions at rest∑ ? p→Λ 0 n and∑ ? p→Λ 0 n have been studied in order to determine the capture ratio $$r_c = \frac{{\sum ^ - p \to \sum ^0 n}}{{(\sum ^ - p \to \sum ^0 n) + (\sum ^ - p \to \Lambda ^0 n)}}$$ , theΛ 0-lifetime and the∑ ?-Λ 0 mass difference. The following results were obtained: $$\begin{gathered} rc = 0.474 \pm 0.016 \hfill \\ \tau _{\Lambda ^0 } = (2.47 \pm 0.08) \times 10^{ - 10} \sec \hfill \\ M_{\sum ^ - } - M_{\sum ^0 } = 81.64 \pm 0.09{{MeV} \mathord{\left/ {\vphantom {{MeV} {c^2 }}} \right. \kern-\nulldelimiterspace} {c^2 }} \hfill \\ \end{gathered} $$ The∑ ?-mass was determined from the range of the stopping∑ ?-hyperons,M ∑} =1197.19±0.32 MeV/c 2. 相似文献
35.
Synthesis and mesomorphic behavior of nine members of each of the two classes of 6-phenyl- and 2-phenyltetralins and five members of the 2-trans-cyclohexyltetralins are reported. The synthesis of one member of each class is described in detail. Besides the target compounds, more than twenty intermediates showed liquid crystalline properties; their transition temperatures are recorded (see Tables 1-6). 相似文献
36.
Y. Kuno J. Imazato K. Nishiyama K. Nagamine T. Yamazaki K. Matsuta S. Ise Y. Nojiri T. Minamisono 《Hyperfine Interactions》1988,39(3):253-267
NMR measurements on12B nuclei implanted in a thin sheet of highly oriented pyrolytic graphite (Grafoil) have been made to study the magnitude of
the polarization of12B and its electric quadrupole coupling. The magnitude of the residual polarization of12B held in carbon material is of crucial importance to the experiment measuring the average polarization of12B produced in the muon capture by12C. It was found that the polarization of12B can be maintained at 101.0±2.2% in Grafoil under a magnetic field of 3 kG. The electric quadrupole coupling was determined
to bee
2
qQ/h=+1207.3±8.2 kHz. From the magnitude and the sign of the electric field gradienteq, the location of12B was found to be a substitutional site in the carbon lattice. The anomalous B-C bond involving thesp
2
hybrid orbitals with partially filledp
z
electrons is also discussed. 相似文献
37.
38.
Niklaus Hriger Dobrila
ivanov Horst H. A. Linde Kuno Meyer 《Helvetica chimica acta》1972,55(7):2549-2562
From the toad venom Ch'an Su the bufadienolides 1, 4, 9, 10, 12, 15, 17, 20, 22, 25 and 18 , the latter as diacetate 19 were isolated and their structure elucidated. 相似文献
39.
Preparation of thin film SOFCs working at reduced temperature 总被引:1,自引:0,他引:1
SOFCs are expected to become competitive devices for electrical power generation, but successful application is dependent
on decreasing working temperature from 1000 to 800 °C, without detrimental effects on resistance and on electrode processes.
This requires a reduction of the stabilised zirconia electrolyte thickness and an optimisation of the electrodes and interfaces.
We have studied the preparation of a thin film SOFC device working at intermediate temperatures (less than 850 °C). The electrolyte
must be very dense and as thin as possible to avoid ohmic losses. Electrodes, anode and cathode, must be porous enough to
enable the gas fluxes to go through. Ni/YSZ cermet anodes have been prepared by a conventional ceramic method and support
the cells. Thin Yttria Stabilised Zirconia electrolytes (YSZ) have been deposited by RF sputtering, DC sputtering and spray
pyrolysis onto a Ni/YSZ cermet. Thin film La0.7Sr0.3MnO3 (LSM) cathodes have been deposited onto the electrolytes by a spray-pyrolysis method. We present here the preparation and
the characterisation of each component and the electrochemical performance of such cells at 850 °C.
Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998. 相似文献
40.
T. Kondow Y. Kuno R. Kadono J. Imazato K. Nagamine T. Yamazaki 《Physics letters. A》1985,110(6):319-322
The precession frequencies of negative-muon spin rotation in highly oriented pyrolytic graphite and its second stage Rb compound were measured at room temperature. The results showed that a μ- C-C bond is formed from sp2 hybrid orbitals involving the partially filled pz orbital and that intercalation influences the σ as well as the π bonds. 相似文献