Clinical Usefulness of Korean Red Ginseng in Postmenopausal Women with Severe Climacteric Disturbance

Yoshihiro Kikuchi(Yoshihiro Kikuchi),Takehiko Tode(Takehiko Tode),Junko Hirata(Junko Hirata),Hideyuki Nakata(Hideyuki Nakata),Tsunekazu Kita(Tsunekazu Kita) 고려인삼학회 2003 Journal of Ginseng Research Vol.27 No.3

The aim of this study is to evaluate clinical usefulness of Korean red ginseng (RG) on various postmenopausal syndromes. Total plasminogen inhibitor-1 (tPAI-1) in peripheral blood from 9 postmenopausal women with climacteric syndromes (CS) was measured before and 3 months after treatment with daily oral administrat i on of 6g RG and that from 8 postmenopausal women without any CS was also measured as healthy controls. Blood samples were collected in the early morning on the bed-rest. Psychological conditions of postmenopausal women with CS were measured before and 3 months after treatment with RG using simplified menopausal index (SMI). In addition, OKETSU (blood stagnation) syndrome scores and KI deficiency (generalized energy stagnation) scores proposed by Terasawa et al., were recorded before and 3months after treatment with RG in postmenopausal women with CS and in healthy postmenopausal women. OKETSU syndrome scores and tPAI-1 levels in postmenopausal patients with CS were significantly (P<0.001 and<br/> P<0.01) higher than those in healthy postmenopausal women without CS. Similarly, SMI scores and KI deficiency scores in postmenopausal patients with CS were about three-fold higher than those without any CS. When RG was administered for 3 months, KI deficiency scores and OKETSU scores as well as SMI scores declined around the levels of healthy postmenopausal women. Although tPAI-1 levels significantly (P<0.05) decreased after treatment with RG, those did not reach the levels of healthy postmenopausal women. Clinical usefulness of administration of RG to postmenopausal women with CS was confirmed from evaluation not only by modern medicine but also by traditional KAMPO medicine.

Sintering behavior of large size, Sm-doped ceria solid electrolyte disk

Yoshihiro Hirata,Yukio Yoshimura,Soichiro Sameshima,Hidekazu Sueyoshi,Toshiya Doi,Teruhisa Horit 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.4

The sinterability of a submicrometre-sized Sm-doped ceria solid solution powder(SDC, powder A) with a composition of Ce0.8Sm0.2O1.9 and a mechanically mixed submicrometre-sized Sm2O3-CeO2 powder (powder B) was studied at 1300-1550 oC in air in order to make a practical solid electrolyte disk of 150 mm diameter. No phase change was observed in powder A heated at 600-1550 oC. The Sm2O3 component in powder B dissolved into the CeO2 powder at temperatures above 1500 oC. The sinterability of powder A was higher than powder B. The formation of SDC in powder B at 1500-1550 oC enhanced the sinterability. No cracks and no warps were observed in the small (10 mm diameter) and large (150 mm diameter) disks after sintering at 1300-1550 oC. The uniformity of microstructure was higher for the disk from powder A than from powder B.

Pressure filtration of colloidal SiC particles

Yoshihiro Hirata,Yosuke Tanaka,Seiya Nakagawa,Naoki Matsunaga 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3

The consolidation behavior of colloidal SiC particles (30 or 800 nm diameter) with and without polyacrylic ammonium (dispersant, PAA) at pH 7 was examined using a developed pressure filtration apparatus in the pressure range from 100 kPa to 19 MPa at a constant crosshead speed or at a constant compressive pressure of a piston. In the electrostatically-stabilized colloidal suspensions (5 vol%-30 nm SiC (powder A), 30 vol%-800 nm SiC (powder B)) without PAA, a phase transition from a well-dispersed suspension to a flocculated suspension occurred when the applied pressure exceeded a critical pressure (ΔPtc = 0.2−0.4MPa). The addition of PAA suppressed the phase transition. The height of the compressive piston as a function of filtration time at a constant applied pressure was simulated by an established filtration theory for a well-dispersed suspension and a newly-developed filtration theory for a flocculated suspension. The experimental results for both the suspensions of powders A and B with and without PAA were simulated well by the new model for flocculated suspension. The packing density of consolidated powders A and B in the filtration apparatus depended on the applied pressure, but the density after calcination was independent of the compressive pressure. The consolidation behavior of colloidal SiC particles (30 or 800 nm diameter) with and without polyacrylic ammonium (dispersant, PAA) at pH 7 was examined using a developed pressure filtration apparatus in the pressure range from 100 kPa to 19 MPa at a constant crosshead speed or at a constant compressive pressure of a piston. In the electrostatically-stabilized colloidal suspensions (5 vol%-30 nm SiC (powder A), 30 vol%-800 nm SiC (powder B)) without PAA, a phase transition from a well-dispersed suspension to a flocculated suspension occurred when the applied pressure exceeded a critical pressure (ΔPtc = 0.2−0.4MPa). The addition of PAA suppressed the phase transition. The height of the compressive piston as a function of filtration time at a constant applied pressure was simulated by an established filtration theory for a well-dispersed suspension and a newly-developed filtration theory for a flocculated suspension. The experimental results for both the suspensions of powders A and B with and without PAA were simulated well by the new model for flocculated suspension. The packing density of consolidated powders A and B in the filtration apparatus depended on the applied pressure, but the density after calcination was independent of the compressive pressure.

Thermodynamics of colloidal suspensions

Yoshihiro Hirata,Yosuke Tanaka 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.4

This paper succeeds in the description of activity (a), chemical potential (μ), and their thermodynamic relations of dispersed and flocculated particles of a one-component colloidal system. The activity of dispersed particles (ad) is expressed by Henry’s law and equal to the product of the molar fraction (α) of dispersed particles in a suspension and the activity coefficient (γ0) expressed by Vi/Vmax (Vi : total volume fraction of dispersed and flocculated particles, Vmax : maximum packing density of particles). The activity of flocculated particles (ag) follows Raoult’s law and is expressed as (1 − α) using the Gibbs-Duhem equation. The μ value is represented by the defined activity. The difference of μ for the dispersed and flocculated particles (Δμ = μg− μd) was used to evaluate the stability of the colloidal state. The Δμ value was also coupled with the activation energy (ΔGm) for the formation of particle clusters from the dispersed state. The enthalpy term (ΔHm) in the activation energy is equivalent to the maximum value of the interaction energy (Ei(max)) as a function of distance between two particles in the DLVO theory. Based on the above analysis, a colloidal phase diagram for one-component systems of 10-1000 nm diameters was constructed. This phase diagram explains well the experimentally-determined packing density for dispersed and flocculated suspensions. This paper succeeds in the description of activity (a), chemical potential (μ), and their thermodynamic relations of dispersed and flocculated particles of a one-component colloidal system. The activity of dispersed particles (ad) is expressed by Henry’s law and equal to the product of the molar fraction (α) of dispersed particles in a suspension and the activity coefficient (γ0) expressed by Vi/Vmax (Vi : total volume fraction of dispersed and flocculated particles, Vmax : maximum packing density of particles). The activity of flocculated particles (ag) follows Raoult’s law and is expressed as (1 − α) using the Gibbs-Duhem equation. The μ value is represented by the defined activity. The difference of μ for the dispersed and flocculated particles (Δμ = μg− μd) was used to evaluate the stability of the colloidal state. The Δμ value was also coupled with the activation energy (ΔGm) for the formation of particle clusters from the dispersed state. The enthalpy term (ΔHm) in the activation energy is equivalent to the maximum value of the interaction energy (Ei(max)) as a function of distance between two particles in the DLVO theory. Based on the above analysis, a colloidal phase diagram for one-component systems of 10-1000 nm diameters was constructed. This phase diagram explains well the experimentally-determined packing density for dispersed and flocculated suspensions.

Interaction between ultrafine ceria particles and glycine

Yoshihiro Hirata,Hisanori Shimazu,Hideyuki Takahashi,Soichiro Sameshima 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.1

An ultrafine ceria powder of 15 nm equivalent spherical particle diameter was dispersed at 2 vol% solid in aqueous solutions with and without glycine (H2NCH2COOH) of 0.05-5.0 mass% against ceria. The addition of glycine increased the zeta potential of the ceria toward positive values in acidic suspensions. The phase separation of ceria suspensions due to the decreased repulsive energy with decreasing particle size, was suppressed by the steric stabilization effect of the adsorbed glycine. No significant influence of the glycine addition on the zeta potential and phase separation of the basic suspension was measured.

Electrodeposition of an alumina precursor on a silicon carbide surface

Yoshihiro Hirata,Masaru Murao,Tomoyuki Maeda,Naoki Matsunaga,Soichiro Sameshima 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

An electrodeposition method was used to form nanometre-sized alumina particles on a silicon carbide surface. A direct current in the range from 0.15 to 11.8 mA/m2 was flowed between a cylindrical carbon cathode and a porous silicon carbide anode in an aqueous solution containing ethylenediaminetetraacetatoaluminium (III) (Al-EDTA¯) at a pH 6. The current density increased with an increase of the applied voltage and showed a maximum as a function of deposition time. The deposited alumina precursor was estimated to be (OH)Al(OOCH)2. After calcination at 800ºC in an Ar atmosphere, the uniformly deposited precursor changed to alumina particles with a specific surface area of 44.3 m2/g. An electrodeposition method was used to form nanometre-sized alumina particles on a silicon carbide surface. A direct current in the range from 0.15 to 11.8 mA/m2 was flowed between a cylindrical carbon cathode and a porous silicon carbide anode in an aqueous solution containing ethylenediaminetetraacetatoaluminium (III) (Al-EDTA¯) at a pH 6. The current density increased with an increase of the applied voltage and showed a maximum as a function of deposition time. The deposited alumina precursor was estimated to be (OH)Al(OOCH)2. After calcination at 800ºC in an Ar atmosphere, the uniformly deposited precursor changed to alumina particles with a specific surface area of 44.3 m2/g.

Hot-pressing and mechanical properties of SiC ceramics with polytitanocarbosilane

Yoshihiro Hirata,Nobuhiro Hidaka,Soichiro Sameshima,Hidekazu Sueyoshi 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.4

An SiC power of median size 0.8 µm was mixed with an Al2O3 powder of median size 0.2 µm in a 0.3 M-Y(NO3)3 solution at pH 5 to distribute homogeneously the sintering additives (Al2O3+Y3+ ions) around the SiC particles. In a 30 vol% SiC suspension, the network structure of SiC particles was formed by the heterocoagulation through the adsorbed Al2O3 and Y3+ions. The aqueous suspension of the SiC-Al2O3 (1.17 vol%)- Y3+ ions (0.94 vol% Y2O3) system was consolidated by filtration through a gypsum mold and formed green compacts of 52-55% of theoretical density. Polytitanocarbosilane (PTC) of 0.04-5.2 vol% was infiltrated into the calcined SiC compact. The SiC compacts with and without PTC were hot-pressed under a pressure of 39 MPa at 1950oC in an Ar atmosphere. Addition of PTC to the SiC compact increased the sinterability, flexural strength and fracture toughness of SiC and suppressed the grain growth during the hot-pressing. The measured mechanical values of SiC with 1.3 vol% PTC were as follows: average four-point flexural strength 711 MPa, fracture toughness 5.9 MPa·m1/2, Vickers hardness 19-21 GPa, and Weibull modulus 12.5.

Preparation microstructures and electrical properties of a Ni/Sm-doped ceria cermet as an anode material of a solid oxide fuel cell

Yoshihiro Hirata,Soichiro Sameshima,Keisuke Higashinakagawa 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.1

This paper reports the preparation, microstructures and electrical properties of a Ni (55 vol%)/Sm-doped ceria cermet. A nickel powder of median size 14 μm or a NiO powder of median size 2.5 μm was mixed with Sm-doped ceria (SDC) powder(median size 0.87 μm) with a composition of Ce0.8Sm0.2O1.9, which was produced by the calcination of an oxalate solid solution (Ce0.8Sm0.2)2(C2O4)3 at 600캜. The mixtures of Ni/SDC (sample A) and NiO/SDC (sample B) were sintered at 1300 캜 in air to a relative density of 58.6% and 97.3%, respectively. During the sintering of the cermet, the Ni powder was oxidized to NiO in sample A. The NiO component in the as-sintered cermet was reduced to Ni in a H2-H2O atmosphere of an oxygen partial pressure ~10.20 atm at 700캜. Both the cermets showed a high stability of high electronic conduction to 100 h of heating at 700캜 in a low oxygen partial pressure atmosphere. Sample A with large Ni particles was too brittle to handle after the heating. Sintering of the fine Ni grains in sample B proceeded at 700C

Analysis of particle connection in a two-component powder compact by electrical conductivity measurements

Yoshihiro Hirata,Yuki Koreeda,Soichiro Sameshima 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.4

Particle connection in a two-component powder compact was quantitatively evaluated by electrical conductivity measurements. As a model system, an alumina powder (median size 0.33 µm, insulator) was mixed with an indium tin oxide powder (ITO, In2O3-SnO2, median size 0.20 µm, electronic conductor) in aqueous solutions at pH 3.0-10.3 to make different types of microstructures of the consolidated powder compacts. The rheological properties of the suspensions and the packing density and electrical conductivity of the powder compacts consolidated by filtration were greatly dominated by the dispersibility of the matrix phase particles (Al2O3) rather than by the dispersibility of the second phase particles (ITO). The Al2O3-ITO compacts prepared from a well-dispersed suspension at pH 3, showed a high electrical conductivity which was independent of the relative density (60-95%). Particle connection between ITO particles was formed in the consolidated green compacts. The electrical conductivity of the powder compacts processed with a high viscosity suspension at pH 10, was low and enhanced when the bulk density exceeded 60% relative density by sintering. The network of ITO particles was formed by a decrease in the distance between ITO particles during the densification.

Mixing Rules of Young's Modulus, Thermal Expansion Coefficient and Thermal Conductivity of Solid Material with Particulate Inclusion

Hirata, Yoshihiro,Shimonosono, Taro The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.1

This analyzed a Young's modulus (E), a thermal expansion coefficient (TEC, ${\beta}$) and a thermal conductivity (${\kappa}$) of the material with simple cubic particulate inclusion using two model structures: a parallel structure and a series structure of laminated layers. The derived ${\beta}$ equations were applied to calculate the ${\beta}$ value of the W-MgO system. The accuracy was higher for the series model structure than for the parallel model structure. Young's moduli ($E_c$) of sintered porous alumina compacts were theoretically related to the development of neck growth of grain boundary between sintered two particles and expressed as a function of porosity. The series structure model with cubic pores explained well the increased tendency of $E_c$ with neck growth rather than the parallel structure model. The thermal conductivity of the three phase system of alumina-mullite-pore was calculated by a theoretical equation developed in this research group, and compared with the experimental results. The pores in the sintered composite were treated as one phase. The measured thermal conductivity of the composite with 0.5-25% porosity (open and closed pores) was in accordance with the theoretical prediction based on the parallel structure model.