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891.
The adsorption of cationic and neutral R6G molecules on Au nanoparticles was elucidated by surface enhanced Raman scattering (SERS). The steric hindrance at hydroethyl amino (‐N(H)Et) groups in R6G was evidenced by the observation that R6G+ adsorb on as‐prepared gold nanoparticles (AuNPs) only with electrostatic forces, in contrast to the electrostatic and chemical adsorption of R123+ with dihydro amino (‐NH2) groups on as‐prepared AuNPs. Large steric hindrance at the amino groups in R6G yielded saturated coverage of 700 molecules/AuNP for R6G+ significantly fewer than 1000 molecules/AuNP for R123+. In addition, neutral R6G0 on AuNPs showed markedly enhanced peaks at 1200–1600 cm−1, which were not observed in Raman spectra of R6G0 in bulk solution, and also in SERS of R6G+ on AuNPs. These bands are attributed to vibrational modes of an outer phenyl ring and ethyl amino groups, which are vertical to a xanthene plane, on the basis of theoretical analysis of molecular vibrations. Thus, Raman scattering of these bands is enhanced under an inclined orientation of R6G0 molecules chemisorbed on AuNPs via lone pair electrons at amino groups. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
892.
Yu Komatsu Megumi Kayanuma Mitsuo Shoji Kazuhiro Yabana Kenji Shiraishi Masayuki Umemura 《Molecular physics》2013,111(12):1413-1421
In photosynthetic organisms, light energy is converted into chemical energy through the light absorption and excitation energy transfer (EET) processes. These processes start in light-harvesting complexes, which contain special photosynthetic pigments. The exploration of unique mechanisms in light-harvesting complexes is directly related to studies, such as artificial photosynthesis or biosignatures in astrobiology. We examined, through ab initio calculations, the light absorption and EET processes using cluster models of light-harvesting complexes in purple bacteria (LH2). We evaluated absorption spectra and energy transfer rates using the LH2 monomer and dimer models to reproduce experimental results. After the calibration tests, a LH2 aggregation model, composed of 7 or 19 LH2s aligned in triangle lattice, was examined. We found that the light absorption is red shifted and the energy transfer becomes faster as the system size increases. We also found that EET is accelerated by exchanging the central pigments to lower energy excited pigments. As an astrobiological application, we calculated light absorptions efficiencies of the LH2 in different photoenvironments. 相似文献
893.
We have experimentally investigated the negative magneto-rheological effect that is theoretically predicted to appear in a dispersion composed of spindle-like hematite (α-Fe2O3) particles. The spindle-like hematite particles were synthesized by aging a solution of FeCl3 and KH2PO4 for 72?h at 373?K. The particle size distribution was determined by digital image analysis from electronic microscope observation of the particles. In the present study we considered a glycerol–water-based dispersion in order to clarify the influence of the shear rate and the magnetic field strength on the negative magneto-rheological effect. Measurement of the viscosity was carried out using a rotational-type rheometer in an external magnetic field generated by Helmholtz coils. The main results obtained can be summarized as follows. The viscosity of a hematite/glycerol–water dispersion relative to that with no applied magnetic field decreases with increasing magnetic field strength: that is, we observed the negative viscosity effect that has previously been predicted from theoretical considerations. Moreover, the negative magneto-rheological effect is observed to decrease with increasing shear rate, which also agrees qualitatively with the theoretical prediction. 相似文献
894.
Koji Kamagata Hiroyuki Tomiyama Yumiko Motoi Masayoshi Kano Osamu Abe Kenji Ito Keigo Shimoji Michimasa Suzuki Masaaki Hori Atsushi Nakanishi Ryohei Kuwatsuru Keisuke Sasai Shigeki Aoki Nobutaka Hattori 《Magnetic resonance imaging》2013
Objective
The pathological changes in Parkinson disease begin in the brainstem; reach the limbic system and ultimately spread to the cerebral cortex. In Parkinson disease (PD) patients, we evaluated the alteration of cingulate fibers, which comprise part of the limbic system, by using diffusional kurtosis imaging (DKI).Methods
Seventeen patients with PD and 15 age-matched healthy controls underwent DKI with a 3-T MR imager. Diffusion tensor tractography images of the anterior and posterior cingulum were generated. The mean kurtosis (MK) and conventional diffusion tensor parameters measured along the images in the anterior and posterior cingulum were compared between the groups. Receiver operating characteristic (ROC) analysis was also performed to compare the diagnostic abilities of the MK and conventional diffusion tensor parameters.Results
The MK and fractional anisotropy (FA) in the anterior cingulum were significantly lower in PD patients than in healthy controls. The area under the ROC curve was 0.912 for MK and 0.747 for FA in the anterior cingulum. MK in the anterior cingulum had the best diagnostic performance (mean cutoff, 0.967; sensitivity, 0.87; specificity, 0.94).Conclusions
DKI can detect alterations of the anterior cingulum in PD patients more sensitively than can conventional diffusion tensor imaging. Use of DKI can be expected to improve the ability to diagnose PD. 相似文献895.
ABSTRACTWe have developed a technique for neutron diffraction experiments at pressures up to 40?GPa using a Paris-Edinburgh press at the PLANET beamline in J-PARC. To increase the maximum accessible pressure, the diameter of the dimple for sample chamber at the top of the sintered diamond anvils is sequentially reduced from 4.0?mm to 1.0?mm. As a result, the maximum pressure increased and finally reached 40?GPa. By combining this technique with the beam optics which defines the gauge volume, diffraction patterns sufficient for full-structure refinements are obtainable at such pressures. 相似文献
896.
We propose a betting strategy based on Bayesian logistic regression modeling for the probability forecasting game in the framework of game-theoretic probability by Shafer and Vovk [1]. We prove some results concerning the strong law of large numbers in the probability forecasting game with side information based on our strategy. We also apply our strategy for assessing the quality of probability forecasting by the Japan Meteorological Agency. We find that our strategy beats the agency by exploiting its tendency of avoiding clear-cut forecasts. 相似文献
897.
Shin Hattori 《Mathematische Zeitschrift》2013,274(3-4):933-953
Let $p>2$ be a rational prime and $K/ \mathbb Q _p$ be an extension of complete discrete valuation fields. Let $\mathcal G $ be a truncated Barsotti–Tate group of level $n$ , height $h$ and dimension $d$ over $\mathcal{O }_K$ with $0<d<h$ . In this paper, we show that if the Hodge height of $\mathcal G $ is less than $1/(p^{n-2}(p+1))$ , then there exists a finite flat closed subgroup scheme of $\mathcal G $ of order $p^{nd}$ over $\mathcal{O }_K$ with standard properties as the canonical subgroup. 相似文献
898.
899.
Makina Saito Makoto Seto Shinji Kitao Yasuhiro Kobayashi Masayuki Kurokuzu Yoshitaka Yoda 《Hyperfine Interactions》2012,205(1-3):87-90
Langmuir-Blodgett (LB) films of octadecanoyl hydroxamic acid (C18N) complexed with Fe3?+? ions have been prepared at various subphase pH values. The LB films consisting of different number of layers were investigated by 57Fe conversion electron M?ssbauer spectroscopy (CEM) at room temperature. The CEM detector contained a piece of α-iron, enriched with 57Fe, using as an internal standard. The M?ssbauer pattern of the C18N/Fe LB films is a doublet with parameters δ = 0.35?mm/s and Δ = 0.74?mm/s. A gradual increase of the relative occurrence of the doublet compared to the sextet of the internal standard was observed with the increasing number of layers, indicating the nearly uniform distribution of Fe among the LB layers. 相似文献
900.