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51.
Shinichi Takeuchi Toshio Sato Norimichi Kawashima 《Colloids and surfaces. B, Biointerfaces》2002,24(3-4):207-216
Nonlinear response of microbubbles illuminated with ultrasound pulse was investigated through experiments and numerical calculations to build the basis for ultrasound blood flow image enhancement system (harmonic imaging system) using higher harmonic components based on nonlinear behavior of microbubbles for ultrasound contrast agents. The effects of membrane coating, size distribution and randomness of spatial distribution of microbubbles were examined. The relationship between the number of cycles in illuminated pulse and the higher harmonic component excitation efficiency, in particular, was studied and a tendency was found for the number of cycles larger than six cycles to cause gradual increase in the second harmonic component excitation efficiency. The simulated and experimental results were in good agreement. Furthermore, the simulated results using the conventional mathematical model ignoring the compressibility of liquid around bubbles showed a tendency of variation opposite to that of experimental results in the relationship between the illuminated ultrasound frequency and the second harmonic component excitation efficiency. On the contrary, the simulated results taking account of compressibility showed a good agreement with the experimental results. 相似文献
52.
A new method for the measurement of trace amounts of HONO has been developed. Nitrous acid in the ambient air is absorbed in an aqueous solution by an air-dragged aqua-membrane-type denuder. The absorbed nitrite is reacted with 2,3-diaminonaphthalene, and the formed 1-naphthotriazol is measured using a fluorescence method. The calibration curve of HONO shows a straight line from 0 to 4000 ppt, and the detection limit is estimated to be 8.1 ppt calculated as being three times of the base line noise. The time resolution, which is defined as the time required to become a constant value by changing from 0 to ca. 1000 ppt was 2 min. The present method is not affected by NO(2), NO, SO(2), O(3) NH(3) or mixtures of these gases and organic nitrate, organic carboxylic acids, alcohols and aldehydes. The determination results of HONO concentrations in the ambient air by the present method are in good agreement with those by the annular denuder system and the differential optical absorption method. 相似文献
53.
Kiyoshi?NomuraEmail author Shigeyo?Suzuki Yuya?Koike Hongling?Li Atsushi?Okazawa Norimichi?Kojima 《Hyperfine Interactions》2016,237(1):26
The dilute magnetic properties of SrSn1?xFexO3 (x = 0.01 ? 0.15) prepared by sol-gel and thermal decomposition methods were investigated by 57Fe Mössbauer spectrometry, magnetometry, and X-ray diffractometry. It was found that SrSnO3 doped with 2–8 % Fe show weak ferromagnetism although only paramagnetic doublets are observed in 57Fe Mössbauer spectra at room temperature (RT), whereas SrSnO3 doped with 10–15 % Fe show relatively strong ferromagnetism, and the sextets are additionally observed in the 57Fe Mössbauer spectra at RT. The weak ferromagnetism by doping 2–8 % Fe is considered to be caused by the induced magnetic defects, and the ferromagnetism by doping 10–15 % Fe are considered mainly due to the magnetic coupling between dilute Fe 3+ partially substituted at Sn 4+ sites in the orthorhombic structure of SrSnO3?δ accompanying the oxygen deficiencies. It is further remarkable that poor crystalline 8 % Fe doped SrSnO3?δ obtained by annealing at 600 °C shows relatively high saturation magnetization and low coercivity. 相似文献
54.
55.
Misa Hirose Saori Toyota Nobutoshi Ojima Keiko Ogawa-Ochiai Norimichi Tsumura 《Optical Review》2017,24(4):517-528
In this paper, principal component analysis is applied to the distribution of pigmentation, surface reflectance, and landmarks in whole facial images to obtain feature values. The relationship between the obtained feature vectors and the age of the face is then estimated by multiple regression analysis so that facial images can be modulated for woman aged 10–70. In a previous study, we analyzed only the distribution of pigmentation, and the reproduced images appeared to be younger than the apparent age of the initial images. We believe that this happened because we did not modulate the facial structures and detailed surfaces, such as wrinkles. By considering landmarks and surface reflectance over the entire face, we were able to analyze the variation in the distributions of facial structures and fine asperity, and pigmentation. As a result, our method is able to appropriately modulate the appearance of a face so that it appears to be the correct age. 相似文献
56.
Optical Review - We evaluated the robustness of a method used to estimate five components (i.e., melanin, oxy-hemoglobin, deoxy-hemoglobin, shading, and surface reflectance) from the spectral... 相似文献
57.
Kikuchi H Saito Y Sekiya J Okano Y Saito M Nakahata N Kubohara Y Oshima Y 《The Journal of organic chemistry》2005,70(22):8854-8858
[structure: see text] We have explored the diversity of secondary metabolites produced by cellular slime molds to examine the possible use of such cellular slime molds as a resource for novel drug development. A new aromatic amide, brefelamide (1), was isolated from methanol extracts of the fruiting bodies of Dictyostelium brefeldianum and D. giganteum. The structure of 1 was determined by spectral means including EIMS and (1)H and (13)C NMR. The total synthesis of 1 was carried out to confirm the structure and obtain sufficient samples for performing biological evaluation. Interestingly, compound 1 inhibited the cellular proliferation of 1321N1 human astrocytoma cells. 相似文献
58.
Ben Nanzai Kenji Okitsu Norimichi Takenaka Hiroshi Bandow 《Research on Chemical Intermediates》2009,35(8-9):841-849
The effect of initial concentration of linear alkylbenzene sulfonate (LAS: p-octylbenzene sulfonate (LAS C8), p-nonylbenzene sulfonate (LAS C9), p-dodecylbenzene sulfonate (LAS C12)) on the rate of sonochemical degradation was investigated over a wide concentration range under Ar atmosphere by 200 kHz ultrasonic irradiation. The degradation rate of each LAS increased with increasing initial concentration of LAS and then started to decrease with the different behavior depending on the types of LASs. This result indicated that the cavitation efficiency was gradually changed by their concentrations and the optimum LAS concentrations for their effective degradation existed. The maximum degradation rates were observed at 250 μM of LAS C12, 1250 μM of LAS C9, and 2500 μM of LAS C8, respectively. These optimum concentrations were found to be about four to six times smaller than these critical micelle concentrations (CMCs). It was also found that the maximum degradation rates at the optimum concentrations were observed to be almost linearly correlated with their CMCs. Based on the obtained results, it could be suggested that the micelle formation occurs in the interfacial region of cavitation bubbles during rectified diffusion and this phenomenon reduces the cavitation efficiency. In addition, from the results of the rate of the sonochemical degradation of LASs and the yield of hydrogen peroxide, the existence of thermal gradient in the interfacial region of cavitation bubbles was also confirmed. 相似文献
59.
Tada M Kojima N Izumi Y Taniike T Iwasawa Y 《The journal of physical chemistry. B》2005,109(20):9905-9916
Vanadium monomers with chiral tridentate Schiff-base ligands were supported on SiO(2) through a chemical reaction with surface silanols, where we found a new chirality creation by the self-dimerization of the vanadyl complexes on the surface. The chiral self-dimerization and the role of surface silanols in the self-assembly were investigated by means of X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), diffuse-reflectance ultraviolet/visible (DR-UV/VIS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), electron spin resonance (ESR), and density functional theory (DFT) calculations. The surface vanadyl complexes had a distorted square-pyramidal conformation with a V=O bond. FT-IR spectra revealed that the Ph-O moiety of Schiff-base ligands was converted to Ph-OH by a surface-concerted reaction between the vanadium precursors and surface SiOH groups. The Ph-OH in an attached vanadyl complex interacted with a COO moiety of another vanadyl complex by hydrogen bonding to form a self-dimerized structure at the surface. The interatomic distance of V-V in the surface self-assembly was evaluated to be 0.40 +/- 0.05 nm by ESR after O(2) adsorption. The self-dimerized V structure on SiO(2) was modeled by DFT calculations, which demonstrated that two vanadium monomers with Ph-OH linked together by two hydrogen bonds and their V=O groups were directed opposite to each other. The surface self-dimerization of the vanadium precursors fixes the direction of the V=O bond and the plane of the Schiff-base ligand. Thus, a new chiral reaction field was created by two types of chirality: the chiral Schiff-base ligand and the chiral V center. We have also found that the chiral self-dimerized vanadyl complexes exhibit remarkable catalytic performance for the asymmetric oxidative coupling of 2-naphthol: 96% conversion, 100% selectivity to 1,1'-binaphthol (BINOL), and 90% enantiomeric excess (ee). Increasing the vanadium loading on SiO(2) caused a dramatic swell of enantioselectivity, and the maximum 90% ee was observed on the supported catalyst with the full coverage of the vanadyl complex (3.4 wt % vanadium). This value is equivalent to the maximum ee reported in homogeneous catalysis for the coupling reaction. Furthermore, the supported vanadium dimers were reusable without loss of the catalytic performance. To our knowledge, this is the first heterogeneous catalyst for the asymmetric oxidative coupling of 2-naphthol. 相似文献
60.
Shigeo Katsumura 《中国化学快报》2009,(10)
(-)-7-Isopropyl-cis-1-amino-2-indanol,a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π-azaelectrocyclization, has been prepared previously by two methods.Each however involved using of one extreme condition, i.e.high temperature or high pressure,for the respective reaction.A modified reaction route employed mild condition for synthesis was presented in this report. 相似文献