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排序方式: 共有480条查询结果,搜索用时 4 毫秒
1.
N. Satou A. Morikawa K. Ohmoto H. Urabe H. Shintani K. Wakasa M. Yamaki 《Journal of materials science. Materials in medicine》1996,7(12):749-752
This study was designed to evaluate the bacterial adhesion to five types of experimental composite-based resins and a commercial composite resin used as a control. Physicochemical surface characteristics of composite resins with and without an artificial saliva coating were measured. The relationship between the numbers of adhering cells (Streptococcus sanguis, S. mutans and S. sobrinus) and surface characteristics was analysed. The values of contact angles and the number of adhering cells were small with saliva coating. S. sanguis ATCC 10557 showed a positive correlation (r=0.835, p<0.05) with the contact angles of uncoated resins, whereas no relationship was observed for saliva-coated resins. With S. mutans Ingbritt the cell numbers adhering to resins correlated strongly (p<0.01) with the values of zeta potential of resins for either saliva coated or uncoated. Electrical repulsion forces had a strong contribution to adherence of cells such as S. mutans and S. sobrinus which show a high absolute zeta potential. 相似文献
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We examined the influence of polyaniline (PAn)'s unit sequence and doping with low molecular weight dopants or polymer dopants on permeation property. It was found that CO2 permeability was increased by the formation of a quinonediimine unit in PAn with the oxidation. CO2 sorption amount of PAn was decreased by oxidation. The increase of CO2 permeability with oxidation, therefore, resulted from the increase of diffusivity, which was attributable to morphological variation by the increase of a quinonediimine unit. The permselectivity of PAn films was found to be remarkably improved by doping. In particular, the selectivity value of the PAn film doped with polyvinyl sulphonic acid as a polymer dopant went up to over 2,000. This remarkable increase of selectivity was found to result in the increase of selectivity, depending on diffusivity. It was also found that the permselectivity of the PAn film doped by polymer dopants was surpassed, as compared with that doped by low molecular dopants. © 1995 John Wiley & Sons, Inc. 相似文献
5.
The crystalline structures of inclusion complexes of γ-cyclodextrin (γ-CD) with poly(ethylene glycol), poly(ethylene adipate), poly(propylene glycol) and poly(isobutylene) were studied by electron microscopy, in combination with X-ray diffraction works and measurements of thermal properties by DSC and TGA. The crystalline structure of as-prepared complexes was tetragonal and its cell dimensions were a = b = 2.380 nm and c = 1.48 nm. When an as-prepared sample was dried in a vacuum at room temperature, the tetragonal modification was transformed into the monoclinic one with the projected cell dimensions of a = 1.75, b = 1.36 nm and γ = 110°. The transformation occurred by progressive ‘shifting’ of rows of polymer necklaces in the [110] direction along the (110) plane in an original tetragonal lamellar crystal. Complexes lost weight by 10-15% in the process of heating up to 140 °C. The tetragonal crystalline modification was transformed into the hexagonal one, and concurrently, the X-ray diffraction profiles of annealed complexes were broadened. When a sample was dried in a vacuum at room temperature or annealed at high temperatures, followed by exposure to water vapor, the original tetragonal crystalline structure was recovered, restoring the original degree of orientation of crystallites in the sample. When water molecules were removed, the lateral stacking order of γ-CD-polymer complexes was destroyed, but the basic necklace structure in which polymer chains threaded through the cavity of γ-CD rings' structure could be retained. 相似文献
6.
T. Katsumata S. Toyomane R. Sakai S. Komuro T. Morikawa 《Journal of the American Ceramic Society》2006,89(3):932-936
SrAl2 O4 :Eu2+ phosphor crystals co-doped with auxiliary activators such as La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y have been grown by the floating zone (FZ) technique. Photoluminescence spectrum (PL), time-resolved PL, and thermally stimulated luminescence (TSL) are evaluated to clarify the long-duration phosphorescence mechanism of SrAl2 O4 , Eu, and Ln phosphors. TSL spectra were measured in the temperature range from RT to 600 K to evaluate the depth and densities of the traps generated by the doping of auxiliary activators that are responsible for the long-duration phosphorescence. The peak wavelength of PL does not vary with auxiliary activator elements, while decay curves vary greatly with the auxiliary activators. The trap depth and the densities of the trapped carriers estimated based on the hole trap model also vary with the auxiliary activator elements. The traps generated at around E =0.5 eV by the auxiliary activators, Nd, Dy, and Tm, with sufficient densities are effective for the long-duration phosphorescence. 相似文献
7.
Md. Majibur Rahman Khan Hideaki Morikawa Mikihiko Miura Yoshie Fujimori Masanobu Nagura 《Carbon》2007,45(5):1035-1042
Carbon fibers were prepared from silk fibers after an iodine treatment and the carbon yield, fiber morphology, structure and mechanical properties were investigated. A single or multi-step carbonization process was used for the preparation. In the single step process, silk fibroin (SF) fibers were heated from 25 to 800 °C with a heating rate of 5 °C min−1 under Ar atmosphere. However, the carbon fiber obtained was partially melted and was too fragile to handle. For better performance, SF fibers were treated with iodine vapor at 100 °C for 12 h and untreated and iodinated SF fibers were heated from 25 to 800 °C by a multi-step carbonization process, which was defined based on the optimum thermal degradation rate of silk. In this multi-step process, the carbon fibers obtained from iodinated SF were structurally intact and stable in appearance, and the carbon yield achieved was ca. 36 wt.%, much higher than the value for untreated SF. X-ray diffraction, Raman spectroscopy and transmission electron microscopic observation revealed that the obtained carbon fibers from both untreated and iodinated SFs had a basically amorphous structure. The strength of carbon fibers prepared from iodinated SF using the multi-step carbonization was considerably increased compared to that of untreated SF. According to viscoelastic measurement, by heating above 280 °C the iodine introduced intermolecular cross-linking of the SF, and its melt flow was inhibited which produced a higher yield and better performance of the carbon fiber. 相似文献
8.
A technique for separating similar and diverse ionogenic mixtures into their individual homologs was studied by high performance
liquid chromatography on an octadecyl-silica (TSK Gel LS-410) column. Conditions used for the separation were: column size,
6 mm id×200 mm; mobile phase, water/methanol (15:85, v/v) containing (a) 1.0 M sodium perchlorate and adjsting to pH 2.5 with
phosphoric acid, (b) 0.1 M and pH 3.5; column temp., 50 C. By using 2 mobile phase conditions, various surfactant mixtures
were separated into their individual homologs and simultaneously distinguished from each other, regardless of their ionogenic
properties. 相似文献
9.
A periodically poled structure with 6.95 /spl mu/m period and 10 mm interaction length was fabricated in a 1 mm-thick 1.8 mol% MgO doped near-stoichiometric LiNbO/sub 3/ (MgSLN) by using a multi-pulse poling technique. Blue SHG characteristics of this periodically poled MgSLN were investigated, in comparison with a periodically poled 5 mol% MgO doped congruent LiNbO/sub 3/. 相似文献
10.
Takuya Morikawa Tatsuya Ashitani Hisayoshi Kofujita Koetsu Takahashi 《Holz als Roh- und Werkstoff》2014,72(5):651-657
The antitermitic activity of extracts from the branch heartwood of Chamaecyparis obtusa (hinoki) against Japanese termites (Reticulitermes speratus) was compared with that of the trunk. Samples of branch and trunk heartwood were extracted with n-hexane, ethyl acetate, and methanol successively. n-Hexane extracts of branch and trunk heartwood were strongly antitermitic, and branch heartwood contained greater quantities of active n-hexane extracts than trunk heartwood. Germacra-1-(10), 5-dien-4β-ol, t-cadinol, α-cadinol, hinokiresinol, and hinokinin were separated from the branch extracts and the termiticidal and antifeedant activity of these compounds was tested by no-choice and dual-choice test methods. The sesquiterpenoids, germacra-1-(10), 5-dien-4β-ol, t-cadinol and α-cadinol were strongly termiticidal. The norlignan hinokiresinol and lignan hinokinin had weak termiticidal, and strong antifeedant and repellent activity. High concentrations of germacra-1-(10), 5-dien-4β-ol and hinokiresinol were present in branch heartwood. These compounds protect hinoki branches from termites and other harmful organisms. Hinoki branch heartwood, which is usually unused, is a potential source of active antitermitic compounds. 相似文献