Journal of the Society of Powder Technology, Japan
Online ISSN : 1883-7239
Print ISSN : 0386-6157
ISSN-L : 0386-6157
Volume 42, Issue 11
Displaying 1-8 of 8 articles from this issue
  • Takeshi Konno, Mikihiko Kobayashi, Mitsuru Egashira, Norio Shinya
    2005 Volume 42 Issue 11 Pages 758-764
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Newly developed manipulator using microprobe has a function of welding for small metal particles. The welding is carried out by contact discharge welding method and non-contact discharge welding method. High voltages are applied to the probe when the probe touches the particle with the former method, while it is applied when the probe is positioned at 20μm above the particle with the latter method. The welded particle is detached, and the fractured joint is observed by an SEM. The fractured joint is less than 5μm in each side of square cross section with the contact discharge welding regardless of the welding time. Followed by the contact discharge welding, the non-contact discharge welding is carried out to increase the welding interface. When nitrogen gas is introduced toward the surface during the welding, the discharge flare generated at the tip of the probe extends along the surface of the particle to the joint. Molten metal is piled around the joint and the welding interface is increased.
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  • Hiroyuki Tsujimoto, Kaori Hara, Yoshiaki Kawashima
    2005 Volume 42 Issue 11 Pages 765-772
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    This paper describes pharmacological effect of inhaled PLGA nano-composite powder with insulin to beagle dogs as a preclinical test. By a novel particle assembly technique consisting of the spherical crystallization and freeze drying, two types of the nano-composite formulations were prepared for type 1 diabetes mellitus, the first one (preparation (1)) was freeze dried insulin encapsulated PLGA nano-spheres with sugar alcohol; the second one (preparation (2)) was the freeze dried PLGA nano-spheres with sugar alcohol and insulin. These preparations could easily reconstruct the original PLGA nano-spheres in saline, which were intratracheally into the dogs spontaneously breathing. The insulin solution was subcutaneously administered as a reference.
    It was found that the PLGA nano-spheres administered intratracheally immediately appeared pharmacological effect and significantly prolonged glycemic effect compared to those of the subcutaneous injection. The pharmacological effects of the preparation (1) and (2) evaluated by the AAC of glycemic profile were approximately 3.5 times higher than the subcutaneous injection.
    Furthermore, the preparation (2) could reduce the dosage amount compared with the preparation (1) to obtain the same pharmacologic effect.
    Thus, the nano-composite preparations presented here could be formulated to the clinical test as a next stage.
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  • Ken-ichiro Tanoue, Yasuhiro Itoh, Tsuneyasu Nagatomo, Hiroaki Masuda
    2005 Volume 42 Issue 11 Pages 773-781
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Tribo-electrification between stainless-steel target and organic powder particles has been studied experimentally based on the current generated by the electrification of the organic powder particles. Experimental apparatus with a unit of coaxial dual tubes, where the initial charge is hardly generated before impacting on the target, has been utilized. Charge transfer by the particle impact is about several hundred times of the initial charge. Furthermore, this experimental system has an adequate repeatability for average charge transfer and standard deviation of instantaneous charge transfer. Depending on the surface of the stainless-steel target, transition of the charge transfer with operation time dramatically changes. For a virgin stainless target, the charge (negative) transfer decreases with time and then approaches to 0μC/g. On the other hand, for a target with a bonding agent on the surface, the charge transfer increases with time and approaches a constant value. For composite particles made by adding small amount of guest particles through mixing, the average charge transfer increases drastically. While composite particles coated by long time mixing shows smaller average charge transfer than those by simple mixing. The charge transfer increases in the 1.3-1.7 power of air velocity. Mass fraction of the guest particles before and after the impact is measured and it is found that the coefficient of variation for charge transfer relates to the separation of the guest particles from the host particles.
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  • Kouichi Nagata
    2005 Volume 42 Issue 11 Pages 782-789
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Adhesive properties of alumina green sheets containing Poly vinyl butyral (PVB) and Dioctyl phthalate (DOP) were investigated. 10wt% of PVB was added while DOP was varied between 0 and 6wt%. By the dynamic visco-elasticity measurement (1 and 10Hz), the glass transition temperature (Tg) of green sheet was found to be 4.7-14.4K higher than that of binder film at the same PVB/DOP ratio. Apparent Tg of DOP was estimated to be 204K through the measurements of Tg of binder films with various PVB/DOP ratios. Adhesive properties of green sheet appeared at a temperature 30 to 40K higher than Tg of the green sheet. Scanning electron microscope observation and ATR-FTIR analysis showed that PVB and DOP were distributed on the side in contact with a PET film at a larger fraction that the opposite side. This is caused by the difference in the wetting characteristics between PVB and PET film when they are wet with DOP. In laminating process of green sheet, the adhesion force may occur by two steps. First the surface of green sheet is wet with DOP and then the adhesion force at the laminating interface grows because of the formation of binder chains between the ceramic particles.
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  • Norio Murase, Kazuyuki Hirao
    2005 Volume 42 Issue 11 Pages 790-798
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    This article reviews the synthesis and the photoemission properties of semiconductor nanocrystals. The quantum size effects, the growth mechanism, the surface condition for high emission efficiency, and the single particle spectroscopy are described. The liquid-phase nanocrystallization is carried out either in water or organic solvent. Since the synthesis in water has an advantage over the sol-gel processing, we have intensively investigated the application. Glass phosphor with emission efficiencies higher than 50% were successfully prepared from the water dispersible nanocrystals by controlling the surface properties. The degree of photo-degradation is also estimated quantitatively.
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  • Shusaku Harada
    2005 Volume 42 Issue 11 Pages 799-803
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Sedimentation of solid particles is an important phenomenon in various engineering processes related to coating, accumulation, separation, filtration and so on. It is well-known that the sedimentation velocity in a stationary fluid is influenced by hydrodynamic interactions between particles and is a function of volumetric concentration of particles. In addition, the hydrodynamic interactions induce complex effects, such as the large-scale fluctuations in the sedimentation velocity, the self-diffusion of particles and the instability at the interface of sedimenting suspension. In this paper, the hydrodynamic diffusion, which is one of the hydrodynamic effects, of particle layer with a finite height is discussed. Researches on the hydrodynamic diffusion are reviewed and our recent numerical studies on the diffusivity of particles in microscale are reported.
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  • 2005 Volume 42 Issue 11 Pages 811-812
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • Kuniaki Gotoh
    2005 Volume 42 Issue 11 Pages 814
    Published: November 10, 2005
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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