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排序方式: 共有254条查询结果,搜索用时 15 毫秒
101.
Nao Kamei-Ishikawa Keiko Tagami Shigeo Uchida 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):247-252
Plant uptake of radiocesium (137Cs) was investigated in consideration of the relationships with naturally existing 133Cs and potassium (K). We first determined plant-unavailable fraction of 137Cs in soil by batch sorption and sequential extraction methods with a radiotracer. Then, using the data obtained from the
batch sorption and extraction methods, we clarified the relationships of plant-available and plant-unavailable fractions between
137Cs, 133Cs, and K in soil. Additionally, 137Cs concentrations in crop were estimated using 137Cs in soil and several factors, i.e. fixation ratio of 137Cs in soil, cation exchange capacity, and K concentration in crop. The results implied that the fixation ratio of 137Cs in soil was a very important key to understanding 137Cs plant uptake. 相似文献
102.
Hyoe Takata Tatsuo Aono Keiko Tagami Shigeo Uchida 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):795-799
For safety assessments of geological repositories of nuclear waste, understanding of uranium (U) fate in estuarine areas is
important because U chemical behavior in the areas is expected to be complex. Environmental transfer parameters such as sediment–water
distribution coefficients (K
d) and concentration ratios (CRs) for marine organisms are useful in mathematical models for the assessment. However, due to
its low concentration in estuarine water, K
d and CF data for U are scarce. Thus we studied a rapid method for separation and concentration of U from estuarine water samples
using NOBIAS-CHELATE PA1 resin columns followed by inductively coupled plasma mass spectrometry (ICP-MS) for U measurement.
Chemical recovery was about 100% at pH of 5.7 ± 0.1 from the water samples and alkali and alkaline earth metals were removed.
The method was used to measure U concentrations in estuarine water samples collected at eight Japanese estuarine areas; they
ranged from 0.1 to 3.8 μg L−1. We also measured U concentrations in sediment and marine organism samples by ICP-MS after acid digestion. Using these values,
we observed K
d (range: 39–284 L kg−1) and CRs (0.86–52 L kg−1 for macroalgae, 0.087–15 L kg−1 for crustaceans, and 0.52–93 L kg−1 for molluscs). 相似文献
103.
Kawamorita S Ohmiya H Iwai T Sawamura M 《Angewandte Chemie (International ed. in English)》2011,50(36):8363-8366
Immobile but active: A silica-supported "compact" phosphane, Silica-SMAP, can be used in the Pd-catalyzed borylation of aryl chlorides or bromides with bis(pinacolato)diboron. The Silica-SMAP/Pd system significantly expands the substrate scope of the borylation toward sterically and electronically challenging aryl halides. 相似文献
104.
Jian Zheng Hyoe Takata Keiko Tagami Tatsuo Aono Kazuhiro Fujita Shigeo Uchida 《Microchemical Journal》2012
A simple and rapid analytical method to measure total iodine in seawater using sector-filed ICP-MS is presented here. The new method avoided tedious and complicated organic iodine decomposing and redox treatment. In addition, no pre-concentration and separation operations are needed. The seawater was diluted 100-fold with 0.5% TMAH prior to SF-ICP-MS analysis. Te was added as internal standard. Due to the high sensitivity of SF-ICP-MS, excellent detection limit of 0.23 ng ml? 1 in original seawater was obtained. By applying this newly developed method, for the first time, the total iodine concentrations in Japanese coastal seawaters in 14 estuaries were investigated. An average value of 58.26 ± 6.30 ng ml? 1 (n = 59) for total iodine concentration was obtained for future study on the estimation of sediment–water distribution coefficients and the concentration ratios from water to organisms in Japanese coastal marine environment. 相似文献
105.
106.
Martinez U Asazawa K Halevi B Falase A Kiefer B Serov A Padilla M Olson T Datye A Tanaka H Atanassov P 《Physical chemistry chemical physics : PCCP》2012,14(16):5512-5517
This article reports the synthesis and performance of unsupported Ni(1-x)Zn(x) electrocatalysts for the oxidation of hydrazine in alkaline media. Characterization of these catalysts was achieved using XRD, SEM, and TEM to confirm phase compositions, crystal structures, and morphologies. High performance was observed for the α-Ni(0.87)Zn(0.13) and β(1)-Ni(0.50)Zn(0.50) electrocatalysts with an onset potential of -0.15 V (vs. RHE) and a mass activity of 4000-3800 A g(cat)(-1) at 0.4 V (vs. RHE), respectively. Additionally, in situ IRRAS studies were conducted to understand the mechanism of oxidation. These results demonstrate the feasibility of Ni(1-x)Zn(x) catalysts for direct hydrazine anionic fuel cells. 相似文献
107.
Mitsuhara K Tagami M Matsuda T Visikovskiy A Takizawa M Kido Y 《The Journal of chemical physics》2012,136(12):124303
This paper reveals the fact that the O adatoms (O(ad)) adsorbed on the 5-fold Ti rows of rutile TiO(2)(110) react with CO to form CO(2) at room temperature and the oxidation reaction is pronouncedly enhanced by Au nano-clusters deposited on the above O-rich TiO(2)(110) surfaces. The optimum activity is obtained for 2D clusters with a lateral size of ~1.5 nm and two-atomic layer height corresponding to ~50 Au atoms∕cluster. This strong activity emerging is attributed to an electronic charge transfer from Au clusters to O-rich TiO(2)(110) supports observed clearly by work function measurement, which results in an interface dipole. The interface dipoles lower the potential barrier for dissociative O(2) adsorption on the surface and also enhance the reaction of CO with the O(ad) atoms to form CO(2) owing to the electric field of the interface dipoles, which generate an attractive force upon polar CO molecules and thus prolong the duration time on the Au nano-clusters. This electric field is screened by the valence electrons of Au clusters except near the perimeter interfaces, thereby the activity is diminished for three-dimensional clusters with a larger size. 相似文献
108.
Katsumichi Tagami 《Journal of magnetism and magnetic materials》2012,324(3):355-362
This paper reports perpendicular magnetic recording (PMR) circumstances and the results based on the reference published by NEC. The PMR flexible disks using Co-Cr-Ta films were investigated. Pass wear durability of Co-Cr-Ta film strongly depends on the base film surface roughness and Young's modulus values of Co-Cr-Ta films. Pass wear durability, more than 10 million passes, was confirmed under a high temperature (60 °C) and a high humidity (80% RH) condition, as well as a low temperature (5 °C) condition. The read/write characteristics for double-layered PMR media were examined by using a combination of a single-pole-type (SPT) write head and a magnetoresistive (MR) read head, and a conventional merged ring type inductive (ID) write head/MR read head. By differential equalization of the reproduced voltage, the bit error rate less than 10−6 at 3 Gb/in.2 was obtained for the SPT/MR head combination. The antenna effect for PMR realization was analyzed using the merged ring type ID/MR head. In order to increase the magnetic circuit resistance from the ID head pole to the soft underlayer, we developed the sendust (FeAlSi) soft underlayer with low magnetic permeability. We confirmed that the recorded signal has better stability under the ID/MR head-loaded condition than the SPT head-loaded condition. These results show that there are the head and media solutions to realize PMR. We had confidence that we could use the basic structure of the commercial ID/MR head for the PMR head. 相似文献
109.
T. Matsuda M. Tagami K. Mitsuhara A. Visikovskiy M. Shibuya Y. Kido 《Surface science》2012,606(23-24):1942-1947
The atomic structure of the 3C-SiC(001)-3 × 2 reconstructed surface was analyzed precisely by high-resolution medium energy ion scattering (MEIS). The present MEIS analysis unambiguously shows that the (3 × 2) surface consists of Si adatoms (1/3 ML, 1 ML = 1.05 × 1015 atoms/cm2) on top and underlying Si adlayer (2/3 ML) on the bulk truncated Si plane. As the result, the most probable structure is focused on the Two Adlayer Asymmetric Dimer Model predicted by ab initio calculations and the modified versions with alternating long and short dimers in the 2nd adlayer proposed by photoelectron diffraction (PED) and by grazing incidence X-ray diffraction (GIXRD) analyses. Observed MEIS spectra are well reproduced by the structure relatively close to that determined by PED rather than GIXRD. Interestingly, the first principle calculations using VASP (Vienna ab initio simulation package) prefer symmetric dimers in the second Si adlayer and non-relaxed interplanar distance between the top Si and 2nd C plane of the bulk-truncated surface, which are, however, unable to reproduce the observed MEIS spectra. The distorted 2nd adlayer (asymmetric dimers) may correlate with the compressed interplanar distance between the underlying Si and C planes. 相似文献
110.
Osakai T Yoshimura T Kaneko D Nagatani H Son SH Yamagishi Y Yamada K 《Analytical and bioanalytical chemistry》2012,404(3):785-792
The previously introduced technique of potential-modulated fluorescence (PMF) spectroscopy was used to study the potential-induced fluorescence change of some different dyes at the polarized 1,2-dichloroethane (DCE)/water (W) interface. A zwitterionic dye (POLARIC 488PPS) showed a PMF response similar to that for the previously studied dye (di-4-ANEPPS) with the same ionic state, and the PMF response was likewise explained by the potential-dependent reorientation of the dye at the DCE/W interface. Though a monocationic dye (POLARIC 488PM) showed no distinct PMF signal, a dicationic dye (di-2-ANEPEQ) showed two relatively weak but detectable PMF signals at lower and higher potential. It has thus been found that the ionic state of a potential-sensitive dye strongly influences the potential-induced reorientation of the dye at the interface and consequently its PMF response. These results support the reorientation/solvatochromic mechanism proposed for "slow" dyes but do not necessarily exclude the electrochromic mechanism proposed for "fast" dyes. PMF spectroscopy would provide useful information on the design of slow dyes for the measurement of the resting potential of cell membranes. 相似文献