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排序方式: 共有363条查询结果,搜索用时 406 毫秒
61.
Kazuma Oikawa Kei Toyota Shigeaki Sakatani Yamato Hayashi Hirotsugu Takizawa 《Ceramics International》2019,45(4):4201-4207
In this study, new rGO-silica xerogel nanocomposites (SX-rGO) and its glass fiber reinforced composites (GFR-SX-rGO) were prepared, and its microstructure and thermal properties were evaluated. The raw material was a mixed dispersion prepared by adding 0.01–2.5?wt% of reduced graphene oxide (rGO) to waterglass (6% SiO2). A hydrogel was prepared via sol-gel reaction of this raw material, which was then immersed in hydrochloric acid, hydrophobized in a siloxane/2-propanol reaction system, and then dried at ambient pressure to obtain a hydrophobic carbon-silica xerogel composite. The obtained samples were characterized by N2 physisorption (at 77?K), solid 29Si Magic angle spinning nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, hydrophobicity, and thermal conductivity. It was found that as the amount of rGO was increased, the specific surface area of the nanocomposite decreased by ~25% from 535 to 403?cm2/g, and the average pore size and pore volume were almost halved. The thermal decomposition temperature of the SX-rGO was increased markedly by the addition of rGO. Moreover, the GFR-SX-rGO-0.5 showed low density (0.208?g/cm3), high contact angle (146°) and low thermal conductivity (0.0199?W/mK). 相似文献
62.
Takehisa K 《Applied optics》1997,36(3):584-592
Scaling up of a high average power dye laser amplifier is discussed. Differences in the characteristics between a high average power dye laser amplifier with transverse pumping and longitudinal pumping are presented by a simple theory and simulations. The simulation results for dye laser amplifiers of 10-kW average output power show that longitudinal pumping is as efficient as transverse pumping with the potential of orders of magnitude lower dye flow rate. New pumping designs are also proposed for a dye laser amplifier aimed to achieve high gain with high efficiency to reduce the number of amplifier stages. Simulation results suggest that the new designs, in comparison with a conventional amplifier, can produce several orders of magnitude higher gain without decreasing the conversion efficiency. 相似文献
63.
Masaaki Takehisa Sueo Machi Hiromasa Watanabe Takashi Ueno Seiichi Takahashi Ryoji Tsuchiya Kanji Otaguro Isao Motoda Yoshio Takasaka Kazukiyo Miyanaga Waichiro Kawakami Kouichi Yamaguchi Takanobu Sugo Hayato Nakajima Terutaka Watanabe Chuhei Hinachi 《应用聚合物科学杂志》1979,24(3):853-864
Radiation-induced bulk polymerization of ethylene was carried out with use of a pilot plant with a 10 liter reactor at pressures of 225–400 kg/cm2, temperatures of 30–95°C, ethylene feed rates of 5–28 kg/hr, and dose rate of 3.8 × 105 rad/hr. Characteristics of the process are mild polymerization conditions and capability of producing medium density polyethylene in powder form. The spacetime yield and molecular weight of polymer were in the range of 3.5 to 13.1 g/liter hr and 2.2 × 104 to 14 × 104, respectively. The space-time yield increased with mean residence time and 2.4 powders of pressure, and decreased with temperature. Molecular weight changed similarly with the reaction conditions. These results were consistent with those of the bench plant experiment and the scale effect was small. Polymer deposit to the reactor wall limited a period of continuous operation of the plant. The amount of deposited polymer was increased with the square of reaction time. The rate of polymer deposit was proportional to polymer concentration and to the cube of pressure. The polymer deposit cannot be solved in the bulk process. 相似文献
64.
Temperature dependence of birefringence and stress for natural rubber vulcanizates at strained state
The temperature dependence of stress and birefringence for natural rubber vulcanizates under medium and large deformation was measured for the processes of cooling, heating and re-cooling. In order to investigate the relation between the stress and crystal phase, the observed birefringence, Δt, was converted into the crystallinity, Xv, by the following equation: where Δn0c, Δn0a, fa and fc are the intrinsic birefringence of the crystal, that of the amorphous phase, the orientation factor of crystallites, and that of amorphous phase, respectively. The fusion of crystallites induced by the thermal crystallization resulted in the increasing contractile force, while the fusion of strain-induced crystallites induced the reduction of contractile force. 相似文献
65.
Networks were prepared in the swollen and dry states to investigate the influence of physical relaxation on chemical stress–relaxation. The stress–relaxation behavior of solution-cured samples was different significantly from that of the samples crosslinked conventionally. The same result was also observed in the number of chain scission for both kinds of samples. On the other hand, the number of chain scission estimated by using the swelling method for samples crosslinked conventionally was in good agreement with that by the chemical stress–relaxation for solution-cured samples. It was found that there is little or no influence of the physical relaxation caused by entanglements, and no effect of dangling chains arising from scission in the equilibrium swelling. The relative change of network chain density determined by means of the swelling method was also consistent with that by sol fraction determination. These results indicate that the swelling method can be used as a measure of a degree of degradation on chemorheology. Taking into account the influence of physical relaxation on chemical stress–relaxation, a new relationship between the relative stress decay and the relative network chain density was experimentally proposed. 相似文献
66.
Toshihiro Ogino Toshiyuki Mitachi Kok Hooi Chan Hiroshi Oikawa Masaki Tsushima 《Soils and Foundations》2008,48(2):287-295
An experimental technique for reconstructing the received wave of bender element tests based on linear system theory is shown in this paper. In order to identify the frequency response of testing apparatus, bender element tests using frequency-swept signals are performed. Received waves for one-period sine pulse transmitting with various frequencies are calculated and compared with observed waves in several kinds of soil samples and testing apparatuses. The linearity of the testing system is also confirmed by coherence function. It is shown that calculated data are less affected by random noise and show good agreement with observed data in regards to not only waveform itself but also resulting shear wave velocity. It is mentioned that this technique can provide simulations for arbitrary transmitted waveform with high signal/noise ratio after laboratory tests are performed. It is also mentioned that this technique is advantageous when sufficient amplitude of received wave cannot be ensured or shear wave velocity must be verified, for example, due to uncertainty of arrival time by near-field effect. 相似文献
67.
Katsunari Oikawa Toshihiro Omori Yuji Sutou Haruhiko Morito Ryosuke Kainuma Kiyohito Ishida 《Metallurgical and Materials Transactions A》2007,38(4):767-776
Phase equilibria and martensitic and magnetic transitions of the β (B2 and L21) phase in the Ni–Fe–Ga system were investigated. The b phase was found to be in equilibrium with the γ (A1 structure) or
γ′ (L12 structure) phase. The Curie temperature, T
c
, equilibrium temperature, T
o
5 (Ms + Af)/2, martensitic transition starting temperature, M
s
, and reverse transition finishing temperature, Af , of the β single–phase alloys were sensitive to the Fe and Ga compositions.
The Fe substitution for Ni decreased and increased the T
o
and T
c
, respectively. The Ga substitution for Ni or Fe decreased both the T
o
and T
c
. The entropy change accompanying the reverse martensitic transition showed compositional dependence due to the magnetic contribution.
The saturation magnetization I
s
of the Ni–Fe–Ga system showed a strong dependence on the magnetic valence Z
M
. The Is values of the Ni–Fe–Ga alloys annealed at 1023 K showed the same Z
m
dependence as other ferromagnetic shape memory alloy (FSMA) systems.
This article is based on a presentation made in the symposium entitled "Phase Transformations in Magnetic Materials," which
occurred during the TMS Annual Meeting, March 12-16, 2006, in San Antonio, Texas, under the auspices of the Joint TMS–MPMD
and ASMI–MSCTS Phase Transformations Committee. 相似文献
68.
T. Noji H. Akagawa T. Oikawa Y. Ono Y. Koike 《Journal of Low Temperature Physics》1999,117(3-4):705-709
Single crystals of Ca
0.5
La
1.25
Ba
1.25
Cu
3O
y
and NdBaSrCu
3
O
y
with the dimensions of the order of 1×1×0.5 mm
3
have been grown by the travelling-solvent floating zone method. As-grown single-crystals are tetragonal and non-superconducting. Through the annealing in oxygen, single crystals of Ca
0.5
La
1.25
Ba
1.25
Cu
3
O
y
have become superconductors with T
c
= 55 - 65 K, keeping the tetragonal structure. On the other hand, single crystals of NdBaSrCu
3
O
y
have changed from tetragonal to orthorhombic through the annealing in oxygen, though they have become superconductors with T
c
= 55 K. 相似文献
69.
70.
The antimicrobial effects of spices and herbs from 18 plant species were examined on a foodborne pathogen, Vibrio parahaemolyticus, with the use of combinations of temperatures and nutrient levels. Basil, clove, garlic, horseradish, marjoram, oregano, rosemary, and thyme exhibited antibacterial activities at incubation of 30 degrees C, while with the exception of horseradish, the same spices and additional 7 species exhibited the activities at 5 degrees C. The lowest MIC (minimum inhibitory concentration) was 0.125% observed in clove and marjoram at 30 degrees C in a nutrient rich medium. Lowering of incubation temperature produced little effect on the MICs except for turmeric. The decreasing of the MIC in turmeric appeared to be basically attributed to the sensitivity of the bacterium to coldness. In nutrient poor medium, the lowest was 0.001 and 0.00025% in marjoram at 30 degrees C and at 5 degrees C, respectively. The sensitivity to several spices and herbs was similar among different clinical serotypes including the emerging strain O3:K6. These results suggest that the spices and herbs can be practical for protecting seafood from the risk of contamination by V. parahaemolyticus and used in hurdle technology with low temperature. 相似文献