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排序方式: 共有542条查询结果,搜索用时 31 毫秒
81.
Harinarayan Das Nipa Debnath Atsushi Toda Takahiko Kawaguchi Naonori Sakamoto Hiromichi Aono Kazuo Shinozaki Hisao Suzuki Naoki Wakiya 《Advanced Powder Technology》2017,28(7):1696-1703
The superparamagnetic magnesium ferrite (MgFe2O4) dense nanospheres are synthesized by ultrasonic spray pyrolysis (USP) method from different concentrations of the initial precursor solution. The effect of precursor solution concentration on the particle’s size, morphology, and superparamagnetic behavior has been investigated. XRD results confirm that studied precursor concentration (0.06, 0.12 and 0.24 M) exhibited single phase cubic structure. The mean crystallites size (called as primary particles) of 0.06, 0.12 and 0.24 M samples are 9.6, 11.5, 11.0 nm, respectively but the entire nanosphere’s diameter (called as secondary particles) increases from 206 to 340 nm with increasing precursor concentration. TEM analysis also reveals that nanospheres consist of densely aggregated crystallites of spherical shape and smooth surface. The value of polydispersity index (PDI) shows narrower size distribution for lower concentration. Magnetic properties indicate the superparamagnetic nature for all samples. Herein, the appropriate induction heat generation rate with better morphology was obtained for 0.06 M concentration. Ion release in the aqueous solution of the composition (about 95% for Mg; 99% for Fe) indicating better stability has been confirmed by ICP-OES test. In this approach, as-synthesized nanospheres are suitable for using as a heating agent in magnetic thermotherapy application. 相似文献
82.
Hiromichi Sagitani 《Journal of the American Oil Chemists' Society》1981,58(6):738-743
In many emulsion systems, creaming occurs during the first stage of emulsion breakdown. To reduce the rate of creaming, emulsions
having small and uniform droplets are desirable. In this work, types and HLB of nonionic surfactants, emulsification methods,
and combinations of oils and nonionic surfactants were investigated in order to make stable and homogeneous emulsions. Emulsification
was attained by dissolving the surfactants in the oil phases. The addition speed and volume of water to the oil phases were
important factors affecting the emulsion droplet size. The change of the solute state in the process of emulsification was
observed stage by stage, and the mechanism of emulsification was elucidated. Homogeneous emulsions were formed in the HLB
region, showing liquid crystalline and gel phases in the emulsifying process. The addition speed of water to the oil phase
was very important in forming the liquid crystalline and gel phases. Polyoxyethylene(n)sorbitan monostearate could emulsify
three kinds of oils (hydrocarbon, fatty acid ester and triglyceride). Polyoxyethylene(n)alkyl ether could emulsify hydrocarbon
and fatty acid ester. Polyoxyethylene(n)-monostearate could emulsify only hydrocarbon. Surfactants with proper HLB which were
soluble in the oil phase and in the presence of a very small amount of water formed a stable emulsion. The solubility state
of oil and surfactant was the key to making a fine emulsion. 相似文献
83.
Small peptides with less than 1000 in molecular weight are not considered amenable to sandwich immunoassays due to their difficulty of simultaneous recognition by two antibodies. As an alternative, we attempted noncompetitive detection of small peptides by open sandwich enzyme-linked immunosorbent assay (OS-ELISA) utilizing the antigen-induced enhancement of antibody VH/VL interaction. Taking fragments of human osteocalcin (BGP), a major non-collagen peptide produced in bone, as model peptides, OS immunoassay was performed using the cloned VH and VL cDNAs from two anti-BGP monoclonal antibodies either recognizing the N- or C-terminal fragment, respectively. When the clones were used for OS-ELISA with immobilized VL fragment and phage-displayed VH fragment, enhanced VH/VL interaction upon BGP addition was observed. Especially the clone for the C-terminal fragment showed a superior detection limit as well as a wider working range than those of competitive assay. The result was reproduced with purified VH-alkaline phosphatase and MBP-VL fusion proteins, where the latter was directly immobilized onto the microplate wells. The minimum detectable fragment was the hexamer including the C-terminus. This simple approach with a single monoclonal antibody with a short measurement time may prove a useful tool in immunodiagnostics as well as in proteomics research. 相似文献
84.
新型一维材料:纳米蛇型碳管 总被引:1,自引:1,他引:0
由非晶态碳制备了一类新型纳米碳绳,因其卷绕形状、多层叠片和清晰可见的管壁,称之为纳米蛇型碳管(NCSTs)。形貌观察表明其由直径约73nm的碳穹顶相叠而成,穹顶间距为0.34nm,蛇管长度可达0.2mm。其制备是将脱灰煤和纳米硅的混合物通过温度为3000~4500K的Ar/H2等离子体炬,在反应产物中可以观察到大量的NCSTs。文中对该新型结构的形成机理和纳米硅微粒的催化作用进行了讨论,分析了NCSTs的化学组成和电子结构,并对其力学、电学、化学等性能和应用前景进行了预测。 相似文献
85.
Hiromichi Watanabe Hideki Azuma Hiroyuki Nakano Takashi Sato Masashi Ohkawa Takeo Maruyama Minoru Shimba 《Electrical Engineering in Japan》1998,125(2):44-51
The frequency stability of a semiconductor laser deteriorated under direct frequency shift keying (FSK) when stabilization depended entirely upon an external frequency reference. Therefore, the PEAK method was devised for the purpose of improving frequency stability. This method requires two distinct frequency components and, therefore, will not work effectively in a communications system that produces a succession of identical frequencies, as does the FSK method on occasion. This paper, then, explains the results of our comparative analysis of the two modulation methods. The evaluation of frequency stability requires us to use a beat note between two stabilized laser beams, referred to here, as “signal” and “reference,” lasers. The reference laser is stabilized by a method that takes advantage of the magneto-optical effect. This laser restrains the tendency of the beat note frequency to broaden in other stabilization methods, and even makes it possible to predetermine the beat frequency to be employed. The improvement in frequency stability obtained is about one order of magnitude. © 1998 Scripta Technica, Electr Eng Jpn, 125(2): 44–51, 1998 相似文献
86.
87.
Katsushi Furutani Hiromichi Sato Masayuki Suzuki 《The International Journal of Advanced Manufacturing Technology》2009,40(11-12):1093-1101
This paper describes the influence of the discharge current and the pulse duration on the titanium carbide (TiC) deposition process by electrical discharge machining (EDM) with titanium (Ti) powder suspended in working oil. Although the influence of the electrical conditions for removal EDM has been investigated, the criteria for deposition have not been discussed. In the experiments, a 1-mm copper rod was used for an electrode to prevent the flushing of working oil from the gap between the electrode and a workpiece. Ti powder reacted with the cracked carbon from the working oil, then depositing a TiC layer on a workpiece surface. A major criterion of the deposition or removal was the discharge energy over a pulse duration of 10 μs. A thickness of the TiC layer became the maximum at a certain discharge current and pulse duration. Larger discharge energy and power promoted the removal by heat and pressure caused by the discharge. The removal was classified further into two patterns; cracks were observed on the Ti-rich surface in removal pattern 1 and a workpiece was simply removed in removal pattern 2. The maximum hardness of the deposition was 2000 Hv. The workpiece about 10 μm beneath its surface was also hardened because of the dispersion of TiC. The machining conditions for the hardest deposition did not coincide with those for the highest one. Therefore, the discharge current and pulse duration should be optimized for the deposition. 相似文献
88.
Masanori Hara Kaori YudouEmiko Kinoshita Kayoko OkazakiKazuyoshi Ichinose Kuniaki WatanabeMasao Matsuyama 《International Journal of Hydrogen Energy》2011,36(19):12333-12337
To study the alloying effects on ZrMn2-H system, thermodynamic properties of Zr(Mn1−xCox)2 hydride were measured by volumetric method. ZrMn2 gave a single plateau region in the pressure-composition isotherm. On the other hand, double plateaus were clearly observed in Zr(Mn0.7Co0.3)2 and Zr(Mn0.6Co0.4)2-H systems. The appearance of the double plateau characteristics would be explained in view of the hydrogen binding in the tetrahedral occupation sites in Zr(Mn1−xCox)2. Since the hydrogen binding in the tetrahedral 2ZrMnCo site would be less stable than that in the 2Zr2Mn site, the equilibrium pressure increases with increasing cobalt content. The appearance of the first plateau was ascribed the increase in the bonding of Mn-H in 2Zr2Mn site adjoining the 2ZrMnCo site. 相似文献
89.
Umemura K Noguchi Y Ichinose T Hirose Y Mayama S 《Journal of nanoscience and nanotechnology》2010,10(8):5220-5224
We investigated the morphology and physical-chemical properties of baked and unbaked nanoporous frustules. Scanning electron microscopy (SEM) observations showed that the nanoporous structures of frustules unchanged at 400 degrees C even after baking for 6 h. During baking at 800 degrees C, the frustule structures changed dramatically. On the other hand, Fourier transform infrared spectroscopy (FTIR) of bulk frustule samples indicated that physical-chemical properties of the frustules had clearly changed after baking at not only 800 degrees C but also 400 degrees C. These results showed that the reconstruction of the structures had occurred inside the frustules, even though the morphology of the frustules had not apparently changed at 400 degrees C. In order to characterize the exact shape of the frustules, living diatom cells were grown on a functionalized mica surface, and then baked without any chemical treatment for SEM study. This 'direct baking' technique is effective for comparing minute structures of the frustules, because completed combination of every part of the frustules can be observed. 相似文献
90.
Hideyuki HIRAZAWA Hiromichi AONO Takashi Naohara Tsunehiro MAEHARA Yuji WATANABE 《钢铁研究学报(英文版)》2012,(Z1):596-599
Mg1-XCuXFe2O4 type spinel ferrite was prepared by solid reaction method in order to discuss the heat generation ability in AC magnetic field.The cubic type ferrite structure was obtained for X=0-0.6 samples calcined at1200℃,and the mixture phase of cubic and tetragonal structures were obtained for X=0.7,0.8 samples from XRD result.The highest lattice parameter and highest hysteresis loss value were also shown at X=0.6 sample,the crystal distortion was increased with increase the Cu2+substitution in cubic type ferrite structure.The sized nano Mg0.4Cu0.6Fe2O4 powder was prepared by physical milling method using beads milling.The highest heat generation in the AC magnetic field was obtained for the 6 h milled samples using 0.1mm beads.The Cu2+substitution for MgFe2O4 ferrite and the beads milling were very effective for the improvement of their heat generation ability in AC magnetic field. 相似文献