Maki Ashida
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View article: Corrosion behavior of Zr-14Nb-5Ta-1Mo alloy in simulated body fluid
Corrosion behavior of Zr-14Nb-5Ta-1Mo alloy in simulated body fluid Open
Metals that are used to reconstruct skeletal structures often interfere with magnetic resonance imaging (MRI) owing to differences in magnetic susceptibility; consequently, metals with lower magnetic susceptibilities need to be developed f…
View article: Galvanic Corrosion among Ti-6Al-4V ELI Alloy, Co-Cr-Mo Alloy, 316L-Type Stainless Steel, and Zr-1Mo Alloy for Orthopedic Implants
Galvanic Corrosion among Ti-6Al-4V ELI Alloy, Co-Cr-Mo Alloy, 316L-Type Stainless Steel, and Zr-1Mo Alloy for Orthopedic Implants Open
In orthopedics, occasionally, different types of metals are used in applications in which they are in contact with each other. However, few studies have electrochemically investigated the galvanic corrosion of orthopedic implants formed of…
View article: Severe plastic deformation for producing superfunctional ultrafine-grained and heterostructured materials: An interdisciplinary review
Severe plastic deformation for producing superfunctional ultrafine-grained and heterostructured materials: An interdisciplinary review Open
Ultrafine-grained and heterostructured materials are currently of high interest due to their superior mechanical and functional properties. Severe plastic deformation (SPD) is one of the most effective methods to produce such materials wit…
View article: Effects of High-Pressure Torsion on Mechanical Properties of Biocompatible Ti–6Al–7Nb Alloy
Effects of High-Pressure Torsion on Mechanical Properties of Biocompatible Ti–6Al–7Nb Alloy Open
Ti–6Al–7Nb alloys have been widely used in the medical field, particularly in artificial hip joints, spinal fixators, and dental implants, owing to their light weight, low toxicity, and superior corrosion resistance. Grain refinement throu…
View article: Development of a Surface Treatment to Achieve Long-Lasting Antimicrobial Properties and Non-Cytotoxicity through Simultaneous Incorporation of Ag and Zn via Two-Step Micro-Arc Oxidation
Development of a Surface Treatment to Achieve Long-Lasting Antimicrobial Properties and Non-Cytotoxicity through Simultaneous Incorporation of Ag and Zn via Two-Step Micro-Arc Oxidation Open
A customized micro-arc oxidation (MAO) treatment technique was developed to obtain antibacterial properties with no toxicity on Ti surfaces. A two-step MAO treatment was used to fabricate a specimen containing both Ag and Zn in its surface…
View article: Galvanic Corrosion among Ti–6Al–4V ELI Alloy, Co–Cr–Mo Alloy, 316L-Type Stainless Steel, and Zr–1Mo Alloy for Orthopedic Implants
Galvanic Corrosion among Ti–6Al–4V ELI Alloy, Co–Cr–Mo Alloy, 316L-Type Stainless Steel, and Zr–1Mo Alloy for Orthopedic Implants Open
In orthopedics, occasionally, different types of metals are used in applications in which they are in contact with each other. However, few studies have electrochemically investigated the galvanic corrosion of orthopedic implants formed of…
View article: Developing Microstructure and Enhancing Strength of Ti–6Al–7Nb Alloy with Heat Treatment Processed by High-Pressure Torsion
Developing Microstructure and Enhancing Strength of Ti–6Al–7Nb Alloy with Heat Treatment Processed by High-Pressure Torsion Open
Ti–6Al–7Nb alloy with and without heat treatment was processed by high-pressure torsion (HPT), and subsequently its microstructures and mechanical properties were investigated. Herein, the development of the microstructure by HPT processin…
View article: X‐ray photoelectron spectroscopy‐based valence band spectra of passive films on titanium
X‐ray photoelectron spectroscopy‐based valence band spectra of passive films on titanium Open
Titanium (Ti) is always covered by thin passive films. Thus, valence band (VB) spectra, obtained using X‐ray photoelectron spectroscopy (XPS), are superpositions of the VB spectra of passive films and that of the metallic Ti substrate. In …
View article: Evaluation of cytocompatibility and osteoconductivity of Zr-14Nb-5Ta-1Mo alloy with MC3T3-E1 cells
Evaluation of cytocompatibility and osteoconductivity of Zr-14Nb-5Ta-1Mo alloy with MC3T3-E1 cells Open
The cytocompatibility and osteoconductivity of the Zr-14Nb-5Ta-1Mo alloy were investigated using a mouse osteoblastic cell line (MC3T3-E1) to promote the application of this newly developed alloy in dental/medical treatment. The initial ce…
View article: Development of Electrochemical Surface Treatment to Visualize Critical Corrosion-Inducing Inclusions of Zr in Chloride Environments
Development of Electrochemical Surface Treatment to Visualize Critical Corrosion-Inducing Inclusions of Zr in Chloride Environments Open
An electrochemical surface treatment was developed to visualize the corrosion-inducing inclusions of Zr in chloride environments. Pure Zr and Zr alloy (Zr–0.5O–0.5C) were evaluated in this study. The electrochemical surface treatment consi…
View article: Corrosion Behavior and Bacterial Viability on Different Surface States of Copper
Corrosion Behavior and Bacterial Viability on Different Surface States of Copper Open
本研究では大腸菌と表面化学状態の異なる銅(Cu)との相互作用を検討した.その結果,表面化学状態が主としてCu+の試料では,大腸菌によってCuイオン溶出が促進し,対照的に表面化学状態がCu2+の試料は,大腸菌による影響を受けなった.無菌溶液または細菌含有溶液浸漬前後の試料のXPS解析結果より,表面化学状態が主としてCu+の試料では,腐食生成物生成が大腸菌によって阻害されることが明らかとなった.
View article: Investigation of the Long-Term Antibacterial Properties of Titanium by Two-Step Micro-Arc Oxidation Treatment
Investigation of the Long-Term Antibacterial Properties of Titanium by Two-Step Micro-Arc Oxidation Treatment Open
Recently, biofilm formation caused by bacterial adhesion and colonization has been recognized as the major cause of failure in orthopedic and dental implant surgeries. In this study, a customized micro-arc oxidation (MAO) treatment techniq…
View article: Crystallographic texture- and grain boundary density-independent improvement of corrosion resistance in austenitic 316L stainless steel fabricated via laser powder bed fusion
Crystallographic texture- and grain boundary density-independent improvement of corrosion resistance in austenitic 316L stainless steel fabricated via laser powder bed fusion Open
Improvement of corrosion resistance of austenitic 316L stainless steel via laser powder bed fusion (LPBF) is currently a prominent research topic; however, the effects of crystallographic texture and the related grain boundary density on t…
View article: Development of Electrochemical Surface Treatment for Improvement of Localized Corrosion Resistance of Zirconium in Chloride Environment
Development of Electrochemical Surface Treatment for Improvement of Localized Corrosion Resistance of Zirconium in Chloride Environment Open
An electrochemical surface treatment technique was developed in this study to improve the localized corrosion resistance of zirconium in a chloride ion environment. A combination of anodic and cathodic polarization cycles was applied to in…
View article: Enhancement of antibacterial property of titanium by two-step micro arc oxidation treatment
Enhancement of antibacterial property of titanium by two-step micro arc oxidation treatment Open
A customized micro arc oxidation (MAO) treatment technique was developed to obtain desirable antibacterial properties on titanium surfaces. The two-step MAO treatment was applied to fabricate a specimen containing both Ag and Zn in its sur…
View article: Development of Electrochemical Surface Treatment for Improvement of Localized Corrosion Resistance of Zirconium in Chloride Environment
Development of Electrochemical Surface Treatment for Improvement of Localized Corrosion Resistance of Zirconium in Chloride Environment Open
塩化物イオン環境におけるZrの局部腐食発生を抑制する電気化学的表面処理方法を開発した．アノード／カソードサイクルによりZrの局部腐食を誘発する介在物の選択的除去を試みた．処理後の試料表面には介在物の溶解を示す浅いくぼみが観察された．高濃度のリン酸緩衝生理食塩水中で定電流アノードと定電位カソードの分極サイクルを行うことで，生理食塩水中の孔食電位は2 V以上まで上昇し，耐局部腐食性の大幅な向上が認められた．
View article: Effect of Impurity Elements on Localized Corrosion of Zirconium in Chloride Containing Environment
Effect of Impurity Elements on Localized Corrosion of Zirconium in Chloride Containing Environment Open
To clarify the mechanism of localized corrosion on zirconium in chloride environments, corrosion tests of zirconium and its alloys were performed using conventional and micron-scale measurement systems with surface areas of 0.35 cm 2 and l…
View article: Initial formation kinetics of calcium phosphate on titanium in Hanks' solution characterized using XPS
Initial formation kinetics of calcium phosphate on titanium in Hanks' solution characterized using XPS Open
One cause of the excellent hard‐tissue compatibility of Ti and Ti alloys compared with other metals is their ability to form calcium phosphate in biological environments. This is confirmed by many studies, although the formation mechanism …
View article: Time-Transient Effects of Silver and Copper in the Porous Titanium Dioxide Layer on Antibacterial Properties
Time-Transient Effects of Silver and Copper in the Porous Titanium Dioxide Layer on Antibacterial Properties Open
Recently, silver (Ag) and copper (Cu) have been incorporated into a titanium (Ti) surface to realize their antibacterial property. This study investigated both the durability of the antibacterial effect and the surface change of the Ag- an…
View article: Corrosion Behavior and Bacterial Viability on Different Surface States of Copper
Corrosion Behavior and Bacterial Viability on Different Surface States of Copper Open
This study investigates the interaction between E. coli bacteria and various surface states of Cu. Pure Cu was oxidized at 298 K, 673 K, and 1273 K, and its surface chemical state was characterized using X-ray photoelectron spectroscopy. T…
View article: Investigation of antibacterial effect of copper introduced titanium surface by electrochemical treatment against facultative anaerobic bacteria
Investigation of antibacterial effect of copper introduced titanium surface by electrochemical treatment against facultative anaerobic bacteria Open
This study investigated the efficacy of copper (Cu) as an antibacterial element incorporated on titanium (Ti) surface by electrochemical treatment. Cu was incorporated onto Ti surface by micro-arc oxidation (MAO). A small amount of Cu was …
View article: Design of Zirconium Quaternary System Alloys and Their Properties
Design of Zirconium Quaternary System Alloys and Their Properties Open
Two multicomponent β-type Zr alloys were designed using the d-electron alloy design method, and their mechanical properties, magnetic susceptibility, and Young's modulus were evaluated. A phase stability (Bo–Md) map was constructed by perf…
View article: Strengthening of Ti-6Al-7Nb alloy by high-pressure torsion processing
Strengthening of Ti-6Al-7Nb alloy by high-pressure torsion processing Open
A Ti-6Al-7Nb alloy with three different initial microstructures was processed by high-pressure torsion (HPT) and the resultant microstructure and mechanical properties of the alloy after HPT processing were investigated. The microstructure…
View article: Chemical and Biological Roles of Zinc in a Porous Titanium Dioxide Layer Formed by Micro-Arc Oxidation
Chemical and Biological Roles of Zinc in a Porous Titanium Dioxide Layer Formed by Micro-Arc Oxidation Open
This study investigated the time transient effect of zinc (Zn) in the porous titanium dioxide formed by micro-arc oxidation (MAO) treatment routinely performed for Zn-containing electrolytes. The aim of our analysis was to understand the c…
View article: The Effects of Various Metallic Surfaces on Cellular and Bacterial Adhesion
The Effects of Various Metallic Surfaces on Cellular and Bacterial Adhesion Open
The effects of Ti, Nb, Ta, Zr, and Ag on cellular and bacterial adhesion were investigated in this study. Moreover, the relationships between surface compositions, metal ion release behaviors, and biological responses were examined. As a r…
View article: Three-dimensional quantification of magnetic resonance imaging artifacts associated with shape factors
Three-dimensional quantification of magnetic resonance imaging artifacts associated with shape factors Open
Differences in the volumes of artifacts caused by variously shaped titanium objects on magnetic resonance imaging (MRI) were evaluated. Spherical-, square cubic-, and regular tetrahedron-shaped isotropic, and elongated spherical-, elongate…
View article: Surface characterization of commercially available yttria-stabilized tetragonal zirconia polycrystalline in water and Hanks’ solution using X-ray photoelectron spectroscopy
Surface characterization of commercially available yttria-stabilized tetragonal zirconia polycrystalline in water and Hanks’ solution using X-ray photoelectron spectroscopy Open
To elucidate the mechanism of adhesion of soft and hard tissues to yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP), Y-TZP and titanium disks were immersed in ultrapure water and in Hanks' solution, and the changes in the surf…