サイボウ フカツ コウカ オ ネラッタ チタン ヒョウメン ショリホウ

Thromboembolism events around the cannula and cardiac periventricular were oftenly reported after implanting ventricular assist devices. To assist preventing these problems, we have studied the surface structural modification, based on the titanium (Ti) micro-porous structure, the chemical modification, and the hydro-oxidization treatment. The purpose of this study is the fabrication and evaluation of their fundamental modification that would be the factor of the neointimal growth in vivo. Titanium powder was mixed with melted thermoplastic wax as the plastic compound method, and with calcium phosphate paste as the ceramics compound method. From each paste, adequate specimens were manufactured after sintering. Specimens were measured the porosity and the pore size, and were also evaluated in several mechanical properties. Compared to two methods for manufacturing the Ti micro-porous materials, the plastic compounds showed the fine characteristics in mechanical properties. But for applying as the scaffold for neointimal and blood compatible materials, these specimens would be better for promoting the blood vessel neointima. For the chemical modification of Ti materials surface, bulk Ti specimens were operated with the hydroxide treatment for modification. For promoting the cell growth, type I collagen were put on as the amino group rich container, and fixed with isocyanate for deriving the urethane bonding on the surface. After these treatments, specimens were measured their fixed collagen. Specimens were also observed by SEM, and analyzed by X-ray photoelectron spectroscopy. Fibroblast cells were also harvested on specimens’ surface for studying the performances as the scaffold. Our hydroxide treatment showed the favorable performance for the stability of hydroxyl gel surface and modified collagen, and also indicated as the fine scaffold. Our results indicated the possibility of application for perivascular position and blood contacting situation, by promoting the cell-activation depending on micro-porous structure and modified titanium surface. Especially by choosing and trying the adequate cell activating factor concerning among the multiple organs and implantable devices, these treatment would be widely applicable for them

イオン液体含有レジン添加型グラスアイオノマーセメントの通電によるせん断接着強度低下 : オンデマンド剥離可能な歯科用スマートセメントのコンセプトと実証

With improvement of bonding strength of recent dental cement, it is difficult nowadays to remove restorations without excessive force or vibration to tooth, occasionally resulting in damage of dentin, enamel, and dental root. Therefore, “smart” dental cement indicating strong bonding and easy debonding-on-demand simultaneously is required. In this research, resin-modified glass-ionomer-cement containing an ionic-liquid, tris(2-hydroxyethyl)methylammonium methylsulfate was produced, and the shear bonding strength before and after direct current application were evaluated. The prototype cement containing 15 to 20 mass% ionic-liquid indicated simultaneously no significant reduction of shear bonding strength from that of the original cement not containing ionic-liquid, and significant reduction of bonding strength to approximately 20% of that of the original cement after direct current application of more than 2 mmC/mm2. The prototype cement in this research demonstrated that the concept of smart dental cement electrically debonding-on-demand is feasible

ボールミリング法で改質したβ-TCPセメントの諸特性への粉液比の影響

The authors have developed a β-tricalcium-phosphate (β-TCP) powder modified mechano-chemically through the application of a ball-milling process (mβ-TCP). The resulting powder can be used in a calcium-phosphate-cement (CPC). In this study, the effects of the powder-to-liquid ratio (P/L ratio) on the properties of the CPCs were investigated, and an appropriate P/L ratio that would simultaneously improve injectability and strength was clarified. The mβ-TCP cement mixed at a P/L ratio of 2.5 and set in air exhibited sufficient injectability until 20 min after mixing, and strength similar to or higher than that mixed at a P/L ratio of 2.0 and 2.78. Although the mβ-TCP cements set in vivo and in SBF were found to exhibit a lower strength than those set in air, it did have an appropriate setting time and strength for clinical applications. In conclusion, P/L ratio optimization successfully improved the strength of injectable mβ-TCP cement

Steady Rotation of Micropolar Fluid Sphere in Concentric Spherical Container

AbstractThe problem of slow steady rotation of a micropolar fluid sphere in concentric spherical container filled with viscous fluid is studied. The appropriate boundary conditions are taken on the surface of the sphere. The hydrodynamic couple and wall correction factor exerted on the micropolar fluid sphere is obtained. The dependence of the wall correction factor on the micropolarity parameter and spin parameter is presented graphically and discussed. The hydrodynamic couple acting on a solid sphere in a cell model and on a solid sphere in an unbounded medium are obtained from the present analysis

強度と注入性に優れるβ-TCP基セメントへのジルコニア添加の効果

Injectable calcium phosphate cements (CPCs) exhibit many advantages as bone substitution materials. However, the strength of injectable CPCs after setting are often insufficient. In our previous studies, mechano-chemically modification of β-tricalcium phosphate cement powder through a planetary ball-milling process exhibited simultaneous improvement in the strength and injectability of CPC. Two plausible effects of this process are: changes in the CPC powder properties and zirconia abrasion powder contamination from the milling pot and balls. The objective of the present study is to separately evaluate these two effects on the strength and injectability of CPCs. The calculated injectability of the cement paste with and without the addition of zirconia powder were higher than 65% at 6 h after mixing. These values were much higher than that of the CPC paste without mechano-chemically modification, and similar to that of CPC with zirconia abrasion powder contamination. By contrast, the compression strength of the set CPC with zirconia powder additives were higher than that without the addition, and similar to that of CPC with zirconia abrasion powder contamination. These results suggest that the changes in the CPC powder properties due to mechano-chemically modification mainly affected the injectability of the CPC paste, and the zirconia abrasion powder contamination of the CPC powder affected the strength of the set CPC

生体医用応用を目的としたTi合金中のα相とβ相の体積磁化率の評価

Metallic medical devices in the human body cause serious artifacts in magnetic resonance imaging owing to the volume magnetic susceptibility (χν) mismatch between the device and tissue around the device. To reduce artifacts, medical devices produced from alloys with χν values of approximately −9 × 10−6 are required. Controlling the phase constitution is a basic technique used to control the χν value of an alloy, and the χν value of each phase is a fundamental property. In this study, an α+β-type Ti alloy and two β-type Ti alloys were investigated. The estimated χν values of the α-phase of the alloys were similar to or smaller than that of pure Ti. In contrast, the estimated χν values of the β-phase of the alloys were larger than that of pure Ti. Since the χν value of pure Ti is much larger than −9 × 10−6, the χν values of the β-phases suggested that increasing the volume fraction of the β-phase was not appropriate for producing a Ti alloy with a lower χν value

レジン添加型グラスアイオノマーセメントの通電後の剪断強度減少に対するイオン液体含有の有無と水中浸漬の影響

The enhancement in the bonding strength of advanced dental cements has enabled long-lasting dental restorations. However, the high bonding strength can cause difficulty in removing these restorations. Therefore, “smart” dental cements with simultaneous strong bonding and easy on-demand debonding ability are required. A resin-modified glass-ionomer-cement (RMGIC) with an ionic liquid (IL) has demonstrated significant reduction in the bonding strength with current application (CA). This research investigates the effects of immersion in distilled water on the electric conductivity and bonding strength of RMGIC with and without an IL and CA. The RMGIC without the IL exhibited significant electric conductivity after immersion, and a significant decrease in bonding strength with CA. In comparison, the electric conductivity after immersion and the decrease in bonding strength with CA were greater for RMGIC with the IL. Thus, the feasibility of smart dental cements capable of electrically debonding-on-demand is indicated

レジン添加型グラスアイオノマーセメントの電気伝導度と通電によるせん断試験強度低下に塩化ナトリウム溶液浸漬が与える影響

Advancements in dental cements have considerably improved their bond strengths. However, high bond strength often makes the removal of restorations difficult. Thus, smart dental cements that show controllable bond strength are required. A conventional resin-modified glass-ionomer-cement demonstrated a significant reduction in the bond strength after current application. However, for this system, the ions in the cement are released into the oral cavity, resulting in a reduction of the electrical conductivity and in losses of the expected on-demand debonding property. Herein, the effects of immersion in 0.9 and 15% NaCl solutions on the electrical conductivity and debonding properties were investigated. The cement immersed in 0.9% NaCl solution from 1 to 28 days maintained similar bond strength reductions after current application, whereas that in 15% NaCl solution initially showed no bond strength reduction after 1 day but exhibited an increase in the bond strength reduction after immersion for 28 days

高い変形能を示すチタン繊維編物内部への骨成長

Objectives: The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo. Material and Methods: A Ti fibre with a diameter of 150 μm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit’s hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis. Results: The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block. Conclusions: The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression